U.S. patent application number 10/911531 was filed with the patent office on 2005-01-13 for zirconium/metal oxide fibres.
This patent application is currently assigned to Rothmans, Benson & Hedges Inc.. Invention is credited to Woodhead, James L..
Application Number | 20050009693 10/911531 |
Document ID | / |
Family ID | 23238892 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050009693 |
Kind Code |
A1 |
Woodhead, James L. |
January 13, 2005 |
Zirconium/metal oxide fibres
Abstract
A zirconium metal oxide fibre comprises zirconium oxide and a
metal oxide. The fibre is made by adding a metal oxide in a
suitable form to a colloidal dispersion of an amorphous zirconium
polymer. The mixed colloidal dispersion is subsequently made into a
fibre. The fibre may be used as a substitute for glass fibre in the
manufacture of paper and paper-like materials. The fibre's
thickness is substantially uniform and has a length usually in
excess of one micron.
Inventors: |
Woodhead, James L.;
(Banbury, GB) |
Correspondence
Address: |
BANNER & WITCOFF
1001 G STREET N W
SUITE 1100
WASHINGTON
DC
20001
US
|
Assignee: |
Rothmans, Benson & Hedges
Inc.
North York
CA
AMR International Corp.
Bridgetown
BB
|
Family ID: |
23238892 |
Appl. No.: |
10/911531 |
Filed: |
August 5, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10911531 |
Aug 5, 2004 |
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10242676 |
Sep 13, 2002 |
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6790807 |
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60318614 |
Sep 13, 2001 |
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Current U.S.
Class: |
502/302 ;
502/349 |
Current CPC
Class: |
C01G 25/00 20130101;
C01G 25/02 20130101; C04B 35/62655 20130101; C04B 35/6225 20130101;
C04B 2235/3225 20130101; C04B 2235/526 20130101; C04B 2235/3232
20130101; C04B 35/62625 20130101; C01P 2006/22 20130101; C04B
35/6264 20130101; C04B 2235/442 20130101; C04B 35/634 20130101;
C04B 2235/3217 20130101; C04B 2235/44 20130101; C04B 2235/449
20130101; C04B 2235/444 20130101; D01F 9/08 20130101; C04B
2235/3229 20130101; C01P 2004/10 20130101; C04B 2235/3208 20130101;
C04B 2235/3206 20130101; C04B 2235/3418 20130101; C04B 2235/3224
20130101; C04B 2235/443 20130101; C04B 2235/765 20130101 |
Class at
Publication: |
502/302 ;
502/349 |
International
Class: |
B01J 023/00 |
Claims
1-32. (Cancelled).
33. Use of an amorphous viscoelastic zirconium polymer of the
formula:[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2n-
H.sub.2O (I)wherein X is a zirconium polymer compatible anion and n
is a whole number from 1 to less than 200, as a spinning aid for
making a zirconium/metal based fibre.
34. A process of claim 33 wherein X is selected from the group
consisting of NO.sub.3.sup.-, Cl.sup.- and ClCH.sub.2COO.sup.-.
35. A spinning aid of claim 33 wherein said metal of said
zirconium/metal based fibre is selected from the group consisting
of at least one of a Group IIA metal, a transition metal, a Group
IIIA metal and a Group IIIB metal.
36. A spinning aid of claim 33 wherein n is a whole number from 1
to about 100.
37. A spinning aid of claim 33 wherein said metal of said
zirconium/metal based fibre is a lanthanide metal.
38. A spinning aid of claim 33 wherein said metal of said
zirconium/metal based fibre is selected from the group consisting
of at least one of cerium, yttrium, scandium, magnesium and
calcium.
39. A spinning aid of claim 35 wherein said metal of said
zirconium/metal based fibre is present in up to 50 weight % of the
total equivalent zirconium oxide content.
40. A spinning aid of claim 39 wherein said metal of said
zirconium/metal based fibre is present in up to 25 weight % of the
total equivalent zirconium oxide content.
41. A spinning aid of claim 35 wherein said formula has a ratio of
X to zirconium in the range of about 1.0 to 0.98 to about 1.0 to
1.3.
42. A synergistic combination of at least one fugitive spinning aid
with an amorphous viscoelastic zirconium polymeric inorganic
spinning aid of the
formula:[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2-
n.2nH.sub.2O (I)wherein X is a zirconium polymer compatible anion
and n is a whole number from 1 to less than 200, said combination
being suitable for forming a zirconium/metal based fibre.
43. A synergistic combination of claim 42, wherein X is selected
from the group consisting of NO.sub.3.sup.-, Cl.sup.- and
ClCH.sub.2COO.sup.-.
44. A synergistic combination of claim 42 wherein said metal of
said zirconium/metal based fibre is selected from the group
consisting of at least one of a Group IIA metal, a transition
metal, a Group IIIA metal and a Group IIIB metal.
45. A synergistic combination of claim 42 wherein n is a whole
number from 1 to about 100.
46. A synergistic combination of claim 42 wherein said metal of
said zirconium/metal based fibre is a lanthanide metal.
47. A synergistic combination of claim 44 wherein said metal of
said zirconium/metal based fibre is selected from the group
consisting of at least one of cerium, yttrium, scandium, magnesium
and calcium.
48. A synergistic combination of claim 42 wherein said fugitive
spinning agent is selected from the group consisting of polyvinyl
pyrrolidone, polyethylene oxide, polyvinylalcohol, polyurethane,
polyacrylic acid salt, polyacrylamide and polyvinylmethyl
ether.
49. A synergistic combination of claim 48 wherein said fugitive
spinning agent is polyethylene oxide.
50. A synergistic combination of claim 49 wherein said polyethylene
oxide has a molecular weight of about 5,000,000 g/mol.
51. A synergistic combination of claim 50 wherein the amount of
said polyethylene oxide is 1.5 weight % of the total equivalent
zirconium/metal oxide.
52. A synergistic combination of claim 42 wherein said metal of
said zirconium/metal based fibre is present in up to 50 weight % of
the total equivalent zirconium/metal oxide.
53. A synergistic combination of claim 52 wherein said metal of
said zirconium/metal based fibre is present in up to 25 weight % of
the total equivalent zirconium/metal oxide.
54. A synergistic combination of claim 42 wherein said formula has
a ratio of X to zirconium in the range of about 1.0 to 0.98 to
about 1.0 to 1.3.
55. A green zirconium/metal based fibre comprising a mixed
colloidal dispersion of a metal, wherein said metal is selected
from the group consisting at least one of a Group IIA metal, a
transition metal, a Group IIIA metal and a Group IIIB metal, and an
amorphous zirconium polymer of the
formula:[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2-
n.2nH.sub.2O (I)wherein X is a zirconium polymer compatible anion
and n is a whole number from 1 to less than 200.
56. A synergistic combination of claim 55, wherein X is selected
from the group consisting of NO.sub.3.sup.-, Cl.sup.- and
ClCH.sub.2COO.sup.-.
57. A green fibre of claim 55 wherein said metal of said
zirconium/metal based fibre is selected from the group consisting
of at least one of a Group IIA metal, a transition metal, a Group
IIIA metal and a Group IIIB metal.
58. A green fibre of claim 55 wherein n is a whole number from 1 to
about 100.
59. A green fibre of claim 55 wherein said metal is a lanthanide
metal.
60. A green fibre of claim 55 wherein said metal is selected from
the group consisting of at least one of cerium, yttrium, scandium,
magnesium and calcium.
61. A green fibre of claim 55 wherein said metal is present in up
to 50 weight % of the total equivalent zirconium/metal oxide.
62. A green fibre of claim 61 wherein said metal is present in up
to 25 weight % of the total equivalent zirconium/metal oxide.
63. A green fibre of claim 55 wherein said formula has a ratio of X
to zirconium in the range of about 1.0 to 0.98 to about 1.0 to 1.3.
Description
STATEMENT OF THE INVENTION
[0001] A zirconium/metal oxide fibre comprises zirconium oxide and
a metal oxide. The fibre has sufficient structural strength such
that for example it may be used as a substitute fibre for glass
fibre in the manufacture of paper and paper-like materials.
Preferably the fibre's thickness is substantially uniform and has a
length in excess of 1 micron.
[0002] The metal oxide fibre is made by adding a metal oxide in a
suitable form, preferably as a solution of the metal salt (or a
colloidal dispersion of the metal) to a colloidal dispersion
comprising an amorphous zirconium polymer of the formula:
[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2nH.sub.2O
(I)
[0003] wherein X is a zirconium polymer compatible anion and n is a
whole number.
[0004] The mixed colloidal dispersion is subsequently made into a
mixed metal oxide fibre. Preferably the colloidal dispersion of the
zirconium polymer of formula (I) is made in accordance with a
modification to the process described in U.K. Patent 1,181,794
where, for example, zirconium carbonate or zirconium hydroxide is
reacted to form the colloidal dispersion containing the polymer of
formula (I).
[0005] According to a most preferred embodiment, the invention
relates to a zirconium/metal oxide fibre that comprises zirconium
oxide and a lanthanide oxide. Preferably, the lanthanide/zirconium
oxide fibre is made by adding a solution of a lanthanide, most
preferably lanthanide nitrate (or a lanthanide colloidal
dispersion) to a colloidal dispersion comprising an amorphous
zirconium polymer of the formula:
[Zr.sub.4(OH).sub.12(NO.sub.3).sub.2(H.sub.2O).sub.4].sub.n(NO.sub.3).sub.-
2n.2nH.sub.2O (I)
[0006] The lanthanide nitrate solution is preferably formed by
reacting a lanthanide carbonate, hydroxide or oxide with nitric
acid.
[0007] It was surprisingly found that one could add a highly
concentrated solution of a metal salt (or metal oxide colloidal
dispersion) to the colloidal dispersion of zirconium polymer of
formula (I) creating a mixed colloidal dispersion whereby the
charge balance remains intact preventing adverse precipitation
within the mixed colloidal dispersion. The preferred ratio of X to
zirconium in the polymer of formula (I) is in the range of about
1.0:0.98 to 1.0 to 1.3 to ensure the colloidal dispersion formation
although, for reasons later discussed, the ratio may fall outside
this range. The pH of the colloidal dispersion is preferably in the
range from about 1.5 to about 2. Due to the viscoelastic properties
of the zirconium polymer of formula (I), the zirconium polymer of
formula (I) can act as a spinning aid such that the concentrated
mixed colloidal dispersion has a viscoelasticity that is suitable
for fibre formation by techniques such as spray drying, drawing or
blow spinning. The resultant green fibres are of a stable dried
gel. These green fibres are heat treated to drive off volatiles to
form crystalline fibres comprising zirconium oxide and metal
oxide.
[0008] Although the zirconium polymer of formula (I) has a
viscoelasticity that is suitable for fibre formation on its own,
other spinning agents may be incorporated into the mixed colloidal
dispersion such that the synergistic combination of both the
zirconium polymer of formula (I) and at least one other spinning
agent facilitates fibre formation. Preferably, these other spinning
aids are organic based and are fugitive (volatile) during heat
treatment. Examples of exemplary spinning aids include polyethylene
oxide and polyvinylpyrrolidone.
BACKGROUND OF THE INVENTION
[0009] It is known that metal oxide catalysts can be incorporated
on the surface of various types of fibres for decomposing various
compositions or for purifying exhaust gases. For example, U.S. Pat.
No. 5,094,222 describes a mixture of ceramic fibres containing an
oxidation catalyst for decomposition of fats and oils. The ceramic
fibres are made from at least one of the following oxides: silicon
oxide, zirconium oxide and aluminum oxide. The oxidation catalyst
can be selected from at least one of a variety of metal oxides.
U.S. Pat. No. 5,165,899 describes a porous fibrous structure for
purification of exhaust gases. The fibrous structure is made of
metal alloy fibrils of the MCrAIX type where M is a matrix chosen
from iron, and/or nickel and/or cobalt and X is chosen from
zirconium, yttrium, cerium and lanthanum metal. Japanese Patent
3,060,738 describes cerium oxide mixed and other components which
were mixed with an alumina-silica ceramic fibre to provide a
catalyst that decomposes soot. Also, U.S. Pat. No. 3,860,529
describes Group III B metal oxide impregnated zirconia fibres.
[0010] Metal oxide catalysts have also been used in an extruded
form. Canadian Patent 2,274,013 describes an extruded form of a
ceria/zirconia mixture to treat exhaust gases.
[0011] Similarly, metal oxide catalysts can also be used as
coatings on various types of fibres for primarily purifying exhaust
gases. See for example U.S. Pat. Nos. 5,040,551; 5,075,275;
5,195,165; 5,759,663; 5,944,025; 5,965,481 and U.K. Patent
2,236,493. For instance, to purify exhaust gas, U.S. Pat. No.
5,075,275 describes a catalyst carrier, such as porous heat
resistant fibres, which have been coated with cerium and barium
oxides. U.S. Pat. No. 5,759,663 describes a high temperature
resistant lath of woven ceramic where the fibres of the lath are
coated with chromium oxide, silicone carbide and cerium oxide. U.K.
Patent 2,236,493 describes a honeycomb filter impregnated with
cesium, copper, and cerium or lanthanum to oxidize carbonaceous
particles.
[0012] All of the above-mentioned references either refer to metal
oxides as incorporated on the surface of fibres, as an extruded
form, as coatings on fibres, or as impregnating the fibre. Several
references exist that refer to metal oxides in fibre form only and
further describe various processes for making such fibres. For
instance, U.S. Pat. No. 5,911,944 describes a fibre made by
dispersing a raw material containing at least one metal hydrate and
hydrated metal compound in an alcohol-based solvent
(Bpt.>70.degree. C.) forming a colloidal dispersion. The
colloidal dispersion is heated not higher than 100.degree. C.,
which produces a polymer of the raw material. The polymer is
converted to a complex. The complex is concentrated until it has
spinnability. The colloidal dispersion is stretched to form a fibre
precursor that causes gelation. The gelatinized fibre precursor is
heated to produce a fibre. U.S. Pat. No. 3,846,527 describes making
inorganic fibres that normally would not be spinnable. This was
done by dry spinning a solution or colloidal dispersion with a
linear polymeric fibre-forming material. U.K. Patent 1,402,544
describes the preparation of mixed metal oxide fibres by using
metal alkoxide(s) capable of converting to spinels. Rare-earth
metals are not known to form spinels. U.K. Patent 1,322,723
describes a process for producing fibrous material wherein
zirconium oxide is capable of reacting chemically with silica
fibrils to assist in bonding the fibrils together.
[0013] U.K. Patent 2,059,933 describes the preparation of alumina
or zirconia fibres by spinning an aqueous solution of the
corresponding metal salt, a precursor to the metal oxide fibre. The
specific examples relate only to formation of alumina fibres. These
particular fibres can be made from an aqueous solution containing
other metals whose salts are hydrolysed at a pH less than 7 to
yield a mixed metal fibre. To prevent gelling or precipitation
within the aqueous solution, aliphatic or aromatic amines are added
to the solution to remove excess anions to create a more desirable
solution for fibre formation. In the present invention, however,
excess nitrate anions within the zirconium polymer colloidal
dispersion, as described in U.K. Patent 1,181,794, result in
formation of spheres that would be detrimental to formation of our
desired mixed metal oxide fibres.
[0014] Several patents have dealt with a Group IIA, a Group IIIA or
a lanthanide metal oxide colloidal dispersion that can form gels,
which can be used to make ceramic materials as described in U.S.
Pat. No. 4,181,532. These colloidal dispersions can also be used as
coatings, as described in U.S. Pat. No. 4,231,893. U.S. Pat. No.
4,356,106 describes a process for making a colloidal dispersion
that involves using dry cerium oxide hydrate and a deaggregating
agent to form a dry dispersible cerium compound.
[0015] Several references exist that refer, specifically, to
various processes for making metal oxide/zirconium oxide fibres.
U.S. Pat. No. 5,468,548 describes making reinforced fibres for high
temperature composites consisting of a matrix and eutectic fibres
dispersed in the matrix. The eutectic fibres can be selected from a
series of metal oxides and the reference suggests several optional
metal oxides including ceria and zirconia. The matrix and fibres
are very specific in that the coefficient of thermal expansion of
the matrix should be similar to the eutectic fibre. U.S. Pat. No.
3,891,595 discusses making friction materials that contain 40-85%
of a synthetic inorganic refractory metal oxide fibre and 15-35% of
a binder. The metal oxide fibre may contain zirconia and 1-10% of a
stabilizer, such as alkaline oxides, yttria and rare earth oxides.
`Stabilizers` determine the crystal structure, e.g. tetragonal or
cubic, and prevent the formation of the monoclinic crystal
structure of zirconia. Stabilizers may also suppress growth of
crystallites. A typical binder is a phenol-formaldehyde resin. U.S.
Pat. No. 3,992,498 describes preparation of a fibre by making a
solution of a polar solvent, a metal compound and an organic
polymer. The metal can be zirconium. The solution is extruded into
at least two gas streams and partially dried. The solution may also
contain a lanthanide metal as a phase stabilizer or as a
luminescent salt. U.S. Pat. Nos. 4,927,622, 5,053,214 and 5,112,781
describe a process that involves making an aqueous solution of
zirconium-based granules and a phase stabilizer (1-35 wt %), such
as calcium, yttrium, cerium and hafnium oxides, and fiberizing the
solution. This particular process involves making and drying the
zirconium-based granules before making the fibre. U.S. Reissued
Pat. No. 35,143 describes a process for making a ceramic fibre that
involves mixing crystalline zirconium grains, a zirconia compound,
solvent and a phase stabilizer (more than 0 and up to 20 mol % of
the stabilizer).
[0016] There are also several patents that discuss formations of
colloidal dispersions of mixed metal oxides. For instance, U.S.
Pat. No. 4,788,045 describes preparing a stabilized zirconia powder
that involves mixing a zirconia hydrate colloidal dispersion (pH
0.5-5), containing acicular crystals with dimensions ranging from
10 to 50 nm, with a solution of a stabilizer such as cerium (<30
mol %). The powder formed can be used in ceramics. U.S. Pat. No.
5,004,711 describes forming a zirconia colloidal dispersion from a
solution containing a zirconium salt and a stabilizer, such as
yttrium, lanthanum, cerium, calcium and magnesium oxides. The
solution is mixed with a strong base anion-exchange resin and the
resulting colloidal dispersion is recovered. U.S. Pat. No.
5,238,625 describes a process for making a stabilized zirconia
colloidal dispersion, which involves hydrolyzing a zirconium
alkoxide using aqueous hydrogen peroxide in the presence of an acid
and a stabilizing agent to form a hydrolysate. The hydrolysate is
evaporated to form a dried hydrolysate, which is redissolved into
an organic solvent.
[0017] The present invention employs the colloidal dispersion of an
amorphous zirconium polymer of formula (I), which was described in
U.K. Patent 1,181,794. Although this U.K. patent describes that a
few percent by weight of a stabilizer such as lime or yttria may be
added to the polymer of formula (I), it does not contemplate the
addition of excessive amounts of the metal to the polymer of
formula (I). In this respect, it was generally understood that the
addition of higher proportions of metals would destroy colloidal
dispersions, such as those of the polymer of formula (I).
SUMMARY OF THE INVENTION
[0018] According to an aspect of the invention, there is provided a
process for making a zirconium/metal based fibre, the process
comprising:
[0019] i) mixing a metal salt solution or metal oxide colloidal
dispersion, wherein the metal is selected from the group consisting
of at least one of a Group IIA metal, a transition metal, a Group
IIIA metal and a Group IIIB metal, with a colloidal dispersion of
an amorphous zirconium polymer of the formula:
[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2nH.sub.2O
(I)
[0020] wherein X is a zirconium polymer compatible anion and n is a
whole number from 1 to less than 200, to provide a mixed colloidal
dispersion; and
[0021] forming the mixed colloidal dispersion into the
zirconium/metal based fibre.
[0022] According to another aspect of the invention, X is selected
from the group consisting of NO.sub.3.sup.-, Cl.sup.- and
ClCH.sub.2COO.sup.- and more preferably, n is a whole number from 1
to about 100.
[0023] According to another aspect of the invention, the colloidal
dispersion of the zirconium polymer has a ratio of X to zirconium
in the range of about 1.0 to 0.98 to about 1.0 to 1.3 to maintain
the polymer colloidal dispersion.
[0024] According to another aspect of the invention, the colloidal
dispersion of the zirconium polymer has a pH in the range of about
1.5 to about 2.0 to maintain the polymer colloidal dispersion.
[0025] According to yet another aspect of the present invention,
the metal is a lanthanide metal.
[0026] According to yet another aspect of the present invention,
the metal is selected from the group consisting of at least one of
cerium, yttrium, scandium, magnesium and calcium.
[0027] According to yet another aspect of the present invention,
the metal salt solution is selected from the group consisting of at
least one of a metal nitrate, metal chloride, metal acetate and
metal perchlorate.
[0028] According to yet another aspect of the present invention,
the metal oxide colloidal dispersion is made from a metal salt
substrate selected from the group consisting of at least one of a
metal nitrate, metal chloride, metal acetate and metal
perchlorate.
[0029] According to yet another aspect of the present invention, at
least one fugitive spinning agent is included in the mixing step.
The fugitive spinning agent may be selected from the group
consisting of polyvinyl pyrrolidone, polyethylene oxide,
polyvinylalcohol, polyurethane, polyacrylic acid salt,
polyacrylamide and polyvinylmethyl ether.
[0030] According to another aspect of the invention, the step of
forming the fibre includes: concentrating the mixed colloidal
dispersion of step i) such that the mixed colloidal dispersion
becomes viscoelastic and forming the mixed viscoelastic colloidal
dispersion into the fibre. Preferably, the mixed viscoelastic
colloidal dispersion has a concentration ranging from about 300 g/L
to 600 g/L.
[0031] According to another aspect of the invention, the fibre
diameter is controlled by conventional drawing of said mixed
viscoelastic colloidal dispersion.
[0032] According to another aspect of the invention, the fibre is
dried and fired to form a crystalline zirconium oxide/metal oxide
fibre. Preferably, the fibre is a zirconium oxide/cerium oxide
fibre.
[0033] In yet another aspect of the invention, there is provides a
use of an amorphous viscoelastic zirconium polymer of the
formula:
[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2nH.sub.2O
(I)
[0034] wherein X is a zirconium polymer compatible anion and n is a
whole number from 1 to less than 200, as a spinning aid for making
a zirconium/metal based fibre.
[0035] In yet another aspect of the invention, there is provided a
synergistic combination of at least one fugitive spinning aid with
an amorphous viscoelastic zirconium polymeric inorganic spinning
aid of the formula:
[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2nH.sub.2O
(I)
[0036] wherein X is a zirconium polymer compatible anion and n is a
whole number from 1 to less than 200, said combination being
suitable for forming a zirconium/metal based fibre.
[0037] In yet another aspect of the invention, there is provided a
green zirconium/metal based fibre comprising a mixed colloidal
dispersion of a metal, wherein said metal is selected from the
group consisting at least one of a Group IIA metal, a transition
metal, a Group IIIA metal and a Group IIIB metal, and an amorphous
zirconium polymer of the formula:
[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2nH.sub.2O
(I)
[0038] wherein X is a zirconium polymer compatible anion and n is a
whole number from 1 to less than 200.
[0039] According to another aspect of the invention, X is selected
from the group consisting of NO.sub.3.sup.-, Cl.sup.- and
ClCH.sub.2COO.sup.- and more preferably, n is a whole number from 1
to about 100.
[0040] According to another aspect of the invention, the metal of
the zirconium/metal based fibre is selected from the group
consisting of at least one of a Group IIA metal, a transition
metal, a Group IIIA metal and a Group IIIB metal. Preferably, the
metal of the zirconium/metal based fibre is a lanthanide metal.
More preferably, the metal of the zirconium/metal based fibre is
selected from the group consisting of at least one of cerium,
yttrium, scandium, magnesium and calcium.
[0041] According to another aspect of the invention, the metal of
the zirconium/metal based fibre is present in up to 50 weight % of
the total equivalent zirconium oxide content.
[0042] According to another aspect of the invention, the formula
has a ratio of X to zirconium in the range of about 1.0 to 0.98 to
about 1.0 to 1.3.
DETAILED DESCRIPTION OF THE INVENTION
[0043] Accordingly, the present invention relates to a novel
amorphous, green zirconium/metal fibre. The green fibre is a
precursor to a zirconium/metal oxide fibre. Additionally, the
present invention relates to a process for making such fibres and
the general use of an amorphous zirconium polymer as a spinning
aid.
[0044] The fibre is made by adding a solution of a metal salt
solution (or a metal oxide colloidal dispersion) to a colloidal
dispersion comprising an amorphous zirconium polymer of the
formula:
[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2nH.sub.2O
(I)
[0045] wherein X is a zirconium polymer compatible anion in
providing a colloidal dispersion. The anion is an ionic constituent
which ensures the formation of a stable dispersion. The anion is
derived from a conjugate acid that provides pH in the dispersion
which is most preferably about 1.5 to 2. Preferred anions may be
selected from the group consisting of nitrate, chloride and
chloroacetate. In formula (I), n is a whole number and preferably
ranges from 1 to less than 200 and, preferably, from 1 to about
100.
[0046] The mixing is preferably done at a temperature from about 0
to 90.degree. C., more preferably, from about 15 to 25.degree. C.
The preferred ratio of X to zirconium in the polymer of formula (I)
is such that it ensures colloidal dispersion formation. The ratio
of X to zirconium is, preferably, about 1.0:0.98 to about 1.0 to
1.3. However, it is understood the ratio of X to zirconium may fall
outside this range, providing the resultant polymer of Formula I
remains intact. The pH of the colloidal dispersion may preferably
range from about 1.5 to about 2. The mixed colloidal dispersion is
then concentrated, made into the green fibre, which is subsequently
made into the zirconium/metal oxide fibre.
[0047] The colloidal dispersion of the zirconium polymer of formula
(I) may be made in accordance with a modification to the process
described in U.K. Patent 1,181,794. In order to facilitate an
understanding of that process, it is outlined as follows. A
dispersion or slurry of zirconium carbonate or zirconium hydroxide
is reacted with an approximate equimolar amount of conjugate acid
of the anion X which is preferably nitric acid, hydrochloric acid
or chloroacetic acid, to provide the polymer of formula (I). The
reaction is preferably carried out at about 50.degree. C. to
70.degree. C. with agitation. The reaction mixture is preferably
maintained at a pH of about 1.5 to about 2.0 with an X to zirconium
mole ratio of about 1.0:0.98 to about 1.0:1.3. These preferred
conditions provide for the polymer formation and its stability in
the dispersion.
[0048] The metal salt solutions that are useful for the preparation
of the metal oxide fibre of this invention include a salt solution
of at least one of a Group IIA metal, a transition metal, a Group
IIIA metal and a Group IIIB metal. In particular, the metal salt
solution may be made from the following metal salts: YCl.sub.3,
Y.sub.2(CO.sub.3).sub.3, Y(C.sub.2H.sub.3O.sub.2).sub.3,
Y(NO.sub.3).sub.3, CaCl.sub.2, CaCO.sub.3,
Ca(C.sub.2H.sub.3O.sub.2).sub.2, CaClO.sub.4, Ca(NO.sub.3).sub.2,
MgCl.sub.2, MgCO.sub.3, Mg(C.sub.2H.sub.3O.sub.2).sub- .2,
Mg(ClO.sub.4).sub.2, Mg(NO.sub.3).sub.2, CeCl.sub.3,
Ce.sub.2(CO.sub.3).sub.3, Ce(C.sub.2H.sub.3O.sub.2).sub.3,
Ce(ClO.sub.4).sub.3, and Ce(NO.sub.3).sub.3.
[0049] In accordance with this invention, the solution of the metal
salt is added to the colloidal dispersion of zirconium polymer of
formula (I). A mixed colloidal dispersion is formed whereby the
charge balance remains intact, preventing adverse precipitation
within the mixed colloidal dispersion. This unexpected stability of
the mixed colloidal dispersion is quite surprising. Thus, at least
one type of metal salt solution may be added to the amorphous
zirconium polymer to yield up to 50 weight % of the total
equivalent zirconium/metal oxide content in the fibre. More
preferably, the metal salt solution is added to yield up to 25
weight % of the total equivalent zirconium/metal oxide content in
the fibre.
[0050] Metal oxide colloidal dispersions useful for the preparation
of the metal oxide fibre of this invention include at least one of
a Group IIA metal, a transition metal, a Group IIIA metal and a
Group IIIB metal oxide colloidal dispersion. In particular, the
metal oxide colloidal dispersion may be made from the following
metal salts: YCl.sub.3, Y.sub.2(CO.sub.3).sub.3,
Y(C.sub.2H.sub.3O.sub.2).sub.3, Y(NO.sub.3).sub.3, CaCl.sub.2,
CaCO.sub.3, Ca(C.sub.2H.sub.3O.sub.2).sub.- 2, CaClO.sub.4,
Ca(NO.sub.3).sub.2, MgCl.sub.2, MgCO.sub.3,
Mg(C.sub.2H.sub.3O.sub.2).sub.2, Mg(ClO.sub.4).sub.2,
Mg(NO.sub.3).sub.2, CeCl.sub.3, Ce.sub.2(CO.sub.3).sub.3,
Ce(C.sub.2H.sub.3O.sub.2).sub.3, Ce(ClO.sub.4).sub.3, and
Ce(NO.sub.3).sub.3.
[0051] Preferably, the metal oxide colloidal dispersion is made by
mixing an aqueous slurry of the metal salt with an acid to yield a
hydrolyzable salt. The preferred acids are nitric acid or
hydrochloric acid. Alternatively, if the initial metal salt is a
nitrate or a chloride, this step of mixing the nitrate or chloride
salt with acid is unnecessary. By either approach, the resulting
hydrolyzable salt such as metal nitrate or metal chloride is
hydrolyzed. Preferably, it is hydrolyzed and oxidized by adding a
mixture of ammonium hydroxide and hydrogen peroxide. A metal
hydroxide is obtained and admixed with water and a strong acid to
yield a slurry. The strong acid may be, for example, nitric acid,
hydrochloric acid or perchloric acid, and is capable of
deaggregating the resulting insoluble metal hydrate. A residue from
the slurry is then admixed with water to give the metal oxide
colloidal dispersion.
[0052] Again, by adding the metal oxide colloidal dispersion to the
colloidal dispersion of zirconium polymer of formula (I), a mixed
colloidal dispersion is created. Surprisingly, the charge balance
remains intact, preventing adverse precipitation within the mixed
colloidal dispersion. Thus, the metal oxide colloidal dispersion
may be added to the amorphous zirconium polymer to yield up to 50
weight % of the total equivalent zirconium/metal oxide content in
the fibre. More preferably, the metal oxide colloidal dispersion is
added to yield up to 25 weight % of the total equivalent
zirconium/metal oxide content in the fibre.
[0053] Cerous and/or ceric salts can be converted into cerium (IV)
colloids relatively easily, which, like the cerium (III) salt
solutions, can be readily mixed with the zirconium polymer of
formula (I) without serious adverse effect on the dispersion. For
example, in one particular embodiment, a zirconium/cerium oxide
fibre is made by adding a solution of cerium nitrate to the polymer
of Formula (I). The cerium nitrate solution is made by mixing
cerium carbonate with nitric acid or by dissolving cerium nitrate
in water. The solution is then admixed with a colloidal dispersion
comprising the preferred amorphous zirconium polymer of the
formula:
[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2nH.sub.2O
(I)
[0054] wherein X is preferably NO.sub.3.sup.-. The mixing is done
at approximately 15 to 25.degree. C.
[0055] In a second embodiment, a zirconium/cerium oxide fibre is
made by an alternative route. The zirconium/cerium oxide fibre is
made by adding a colloidal dispersion of cerium nitrate to the
zirconium polymer of formula (I). The dispersion is made by
admixing an aqueous slurry of cerium carbonate with nitric acid.
The resulting cerium nitrate is hydrolyzed and oxidized through the
addition of a mixture of ammonium hydroxide and hydrogen peroxide.
Cerium (IV) hydroxide is obtained and admixed with water and nitric
acid to yield a slurry. A residue from the slurry is admixed with
water to give the cerium oxide colloidal dispersion. The cerium
oxide colloidal dispersion is then added to a colloidal dispersion
comprising the preferred amorphous zirconium polymer of the
formula:
[Zr.sub.4(OH).sub.12(X).sub.2(H.sub.2O).sub.4].sub.n(X).sub.2n.2nH.sub.2O
(I)
[0056] wherein X is preferably NO.sub.3.sup.-. The mixing is done
at approximately 15 to 25.degree. C.
[0057] In general, the mixed colloidal dispersion of this invention
is fiberized by concentrating the mixed dispersion such that it has
a viscoelasticity that is suitable for fibre formation by
techniques such as spinning, drawing, blowing or extrusion.
Preferably, the concentrated mixed colloidal dispersion has a
viscosity of at least 0.8 poise, more preferably 0.8 to 5.0 poise
and most preferably 0.8 to 2.5.
[0058] The fibre diameter is controlled by conventional drawing
techniques such as pulling or drawing, centrifugal spinning, nozzle
injection or blow spinning. Preferably, the polymer solutions are
spray-dried by centrifugal spinning, nozzle injection or disc
atomization to give fibres several centimeters long. Most
preferably, these fibres have less than 15% non-fibrous
material.
[0059] The resultant amorphous, green fibres are of a stable dried
gel. These green fibres are heat treated, preferably to 500.degree.
C., to drive off volatiles to form crystalline fibres comprising
zirconium oxide and the selected metal oxide. The crystalline
fibres formed have a tetragonal crystal structure. However, as the
metal oxide concentration increases beyond 50% by weight of the
total equivalent zirconium/metal oxide content, the crystalline
fibres tend towards a cubic crystal structure.
[0060] Specifically, the mixed colloidal dispersion is capable of
being spun into a fibre due to the viscoelastic properties of the
zirconium polymer of formula (I) itself. The metal salt solution
(or the metal oxide colloidal dispersion) lacks the viscoelastic
properties for conversion alone into a fibre. Through addition of
the metal salt solution (or the metal oxide colloidal dispersion)
to the colloidal dispersion of the zirconium polymer of formula
(I), the polymer can act as a spinning aid such that the
concentrated mixed colloidal mixture can become viscoelastic and
hence, spinnable.
[0061] Although the zirconium polymer of formula (I) has a
viscoelasticity that is suitable for fibre formation, other
spinning agents may be incorporated into the mixed colloidal
dispersion such that the synergistic combination of both the
zirconium polymer of formula (I) and at least one other spinning
agent facilitate fibre formation. Preferably, these other fugitive
spinning aids are organic based and hence dissipate during heat
treatment. Suitable spinning aids include polyvinyl pyrrolidone,
polyethylene oxide, polyvinylalcohol, polyurethane, polyacrylic
acid salt, polyacrylamide and polyvinylmethyl ether.
[0062] In a preferred embodiment, 1.5% of polyethylene oxide
(molecular weight is 5,000,000) is added to the mixed colloidal
dispersion.
[0063] In general, the fibers may be formed by spraying a
conditioned feed using a Mobile Minor spray dryer made by NIRO of
Wisconsin, United States.
[0064] The conditioned feed, for example, may be formed by
concentrating a colloidal dispersion such that the dispersion has a
viscoelasticity suitable for fibre 5 formation or it may be formed
by adding a spinning aid to the colloidal dispersion such that the
dispersion has a viscoelasticity suitable for fibre formation. The
conditioned feed is pumped at a rate of 1.0 L/hour to the dryer
that has been fitted with disc atomization or nozzle injection. The
inlet temperature is maintained in the range of 150.degree. C. to
280.degree. C. with the outlet temperature in the range of
80.degree. C. to 110.degree. C.
[0065] The following Examples are being submitted to further
illustrate various aspects of the present invention. These Examples
are intended to be illustrative only and are not intended to limit
the scope of the present invention.
EXAMPLES
The Zirconium Polymer of Formula (I)
Example 1
[0066] Zirconium carbonate (2.5 kg, 42% by weight zirconium oxide)
was added to 0.52 L of nitric acid (15.3 M) with stirring. The
mixture was stirred using a Silverson homogeniser to break the
lumps of zirconium carbonate. To prevent premature gelation, a
further 0.071 L of nitric acid was added. The dispersion was
digested at 55.degree. C. to accelerate the formation of the
dispersion to a semi-transparent colloidal dispersion of the
zirconium polymer of formula (I).
[0067] The final volume was 1.75 L having a density of 1.70 g/ml
and containing 600 g/L zirconium oxide equivalent. The
nitrate/zirconium mole ratio was 1.07 and the dispersion had a pH
of about 2.0.
Example 2
[0068] Zirconium carbonate (1.0 kg, 38% by weight zirconium oxide)
was added to 0.197 L of nitric acid (15.5 M) with stirring to yield
a main solution.
[0069] A fraction (0.200 kg) of the zirconium carbonate was
separately slurried with water (0.10 L) and vigorously stirred to
break down any lumps of paste. This aqueous slurry was added to the
main solution and digested at 55.degree. C. to 60.degree. C. to
give a clear colloidal dispersion (0.85 L) containing 447 g/L
zirconium oxide equivalent. The nitrate/zirconium mole ratio was
1.0 and the dispersion had a pH of about 2.0.
Example 3
[0070] Zirconium carbonate (1.0 kg, 38% by weight zirconium oxide)
was dispersed in nitric acid (3.05 moles) to yield 0.85 L of a
colloidal dispersion of the zirconium polymer of formula (I), which
contained 447 g/L of zirconium oxide equivalent. The mole ratio of
nitrate/zirconium was 1.0 and the dispersion had a pH of about 2.0.
The colloidal dispersion of the polymer had a density of 1.64 g/ml
and a viscosity of 0.87 poise. The colloidal dispersion of the
polymer was concentrated by evaporation to give a polymer solution
that was 40% by weight zirconium oxide equivalent. The dispersion
became viscoelastic and continuous fibres could be drawn from it.
The fibres gelled with non-sticky surfaces.
Example 4
[0071] Using the same procedure as described in Example 3, 1.5% of
polyethylene oxide (mwt: 5,000,000 g/mol) was added to the
resulting colloidal dispersion of the polymer. The resulting
viscosity of the dispersion was 2.5 poise. The dispersion was spray
dried to yield a fibre containing less than 15% of a non-fibrous
material which is normally referred to as the slot.
Metal Oxide Colloidal Dispersion/Solutions
Example 5
[0072] Cerium carbonate (50 g, 99.9% purity) containing 69.3% by
weight cerium oxide equivalent was slurried with distilled water
(0.1 L) and dissolved by adding nitric acid (38.4 ml; 16 M). The
resulting neutral solution was boiled for a few minutes, filtered
to remove traces of insoluble matter, and diluted to 1 L with water
to give a cerous nitrate solution. A mixture comprising ammonium
hydroxide (40 ml, 18 M), hydrogen peroxide (20 ml, "100 volume")
and water (160 ml) was added with stirring to the cerous nitrate
solution prepared and maintained at 75.degree. C. The resulting
insoluble, dark brown cerium (IV) peroxide complex rapidly faded in
colour and after the complete addition of the ammonium
hydroxide/hydrogen peroxide mixture, a creamy-white precipitate of
cerium (IV) hydroxide was obtained having a pH of 7.0.
[0073] The precipitate was centrifuged and washed twice by stirring
with successive 1 L volumes of distilled water. The separated
precipitate was stirred with distilled water (750 ml) and nitric
acid (12.5 ml of 16 M) to give a nitric acid/cerium oxide mole
ratio of 1. The resulting slurry was boiled for 15 minutes to
deaggregate the cerium (IV) hydroxide and give a conditioned
slurry. The pH of the conditioned slurry was less than 1.
[0074] After cooling the slurry was centrifuged and the residue
admixed with distilled water (150 ml) to give a semi-transparent
greenish colloidal dispersion.
Example 6
[0075] 1 kg of cerium (IV) oxide hydrate ("Ceria Hydrate" obtained
from Rhne Poulenc) was placed in a saggar and heated for 1 hour in
a muffle furnace at 320.degree. C. in air. The resulting dry
dispersible cerium compound powder (0.78 kg) had a crystallite size
of 59.ANG. and the nitrate/cerium oxide ratio was 0.14.
[0076] 1 g of the dispersible cerium compound powder was dispersed
by stirring in hot demineralized water to form a colloidal
dispersion having a concentration of 645 g/L cerium oxide
equivalent. The dispersible cerium compound was 92.1 weight %
dispersible in the hot demineralized water.
Example 7
[0077] Cerium carbonate was dissolved in nitric acid to give
solutions containing 450 g/L of cerium oxide equivalent. The
nitrate/cerium oxide mole ratio was 3.0.
Mixed Zirconium/Metal Oxide Colloidal Dispersions
Example 8
[0078] The colloidal dispersion of the zirconium polymer of formula
(I) was made as described in Example 2. This colloidal dispersion
(0.95 L, 427 g of zirconium oxide equivalent) was mixed with a
cerium oxide colloidal dispersion (0.375 L, 142 g of cerium oxide
equivalent), made as described in Examples 5 or 6, to yield a mixed
colloidal dispersion of 75% zirconium oxide and 25% cerium oxide
equivalent. No adverse effect, e.g. gelling or significant increase
in viscosity, occurred. The mixed colloidal dispersion (1.45 L) had
a density of 1.45 g/mL and a viscosity of 0.6 poise was unchanged
when aged for several hours. The mixed colloidal dispersion was
evaporated to yield a viscosity of at least 0.8 poise such that it
may be fiberized.
Example 9
[0079] The colloidal dispersion of the zirconium polymer of formula
(I) was made as described in Example 2. This colloidal dispersion
(0.1 L, density was 1.6 g/ml, 45 g of zirconium oxide equivalent)
was mixed with a cerium oxide colloidal dispersion (0.128 L, 1.36
g/ml, 45 g of cerium oxide equivalent), made as described in
Examples 5 or 6, to yield a mixed colloidal dispersion of 50%
zirconium oxide and 50% cerium oxide equivalent. No adverse effect,
e.g. gelling or significant increase in viscosity, occurred. The
mixed colloidal dispersion (0.228 L) contained 90 g of mixed
oxide.
Example 10
[0080] The colloidal dispersion of the zirconium polymer of formula
(I) was made as described in Example 2. This colloidal dispersion
(1.0 L, 447 g/L of zirconium oxide equivalent) was mixed with a
yttrium nitrate solution (0.125 L, 400 g/L of yttrium oxide
equivalent), which was made by dissolving yttrium carbonate in
nitric acid, to yield a mixed colloidal dispersion of 90% zirconium
oxide and 10% yttrium oxide equivalent. No adverse effect, e.g.
gelling or significant increase in viscosity, occurred.
Example 11
[0081] The colloidal dispersion of the zirconium polymer of formula
(I) was made as described in Example 2. This colloidal dispersion
(1.0 L, 447 g/L of zirconium oxide equivalent) was mixed with 0.376
L (300 g/L of aluminum oxide equivalent) of an aluminum nitrate
solution (made by dissolving aluminum nitrate in water) or an
aluminum hydroxy nitrate solution (made by heating solid aluminum
nitrate to produce [Al(OH).sub.2(NO).sub.3].sub.n.xH.sub.2O which
is dissolved in water) to yield a mixed colloidal dispersion of 75%
zirconium oxide and 25% aluminum oxide equivalent. No adverse
effect, e.g. gelling or significant increase in viscosity,
occurred.
Example 12
[0082] The colloidal dispersion of the zirconium polymer of formula
(I) was made as described in Example 2. This colloidal dispersion
(0.191 L, 448 gL of zirconium oxide equivalent) was mixed with a
SYTON silica colloidal dispersion (adjusted to pH 1.5) (0.138L, 301
g/L of silicon oxide equivalent) to yield a mixed colloidal
dispersion of 67.4% zirconium oxide and 32.6% silicon oxide
equivalent. The viscosity was 0.13 poise. No adverse effect, e.g.
gelling or significant increase in viscosity, occurred.
Mixed Zirconium/Metal Oxide Fibres
Example 13
[0083] 0.74 L of the mixed colloidal dispersion of Example 9,
containing 290 g of mixed oxide equivalent, was blended with 11.5 g
of polyethylene oxide (PEO, molecular weight of 400,000) to yield
4.0 weight % PEO based on the mixed oxide equivalent. After mixing
to give the required rheology, this feed was filtered through a 150
micron sieve and spray dried using a NIRO Mobile Minor spray dryer.
The feed was pumped at a rate of 1.0 L/hour to the dryer that has
been fitted with disc atomization or nozzle injection. The inlet
temperature is maintained in the range of 150.degree. C. to
280.degree. C. with the outlet temperature in the range of
80.degree. C. to 110.degree. C. The green fibre obtained is then
heated to 500.degree. C. to yield the mixed oxide fibre.
Example 14
[0084] 0.74 L of the mixed colloidal dispersion of Examples 9, 10,
11 or 12, containing 290 g of mixed oxide equivalent, was blended
with 4.3g of polyethylene oxide (PEO, molecular weight of
5,000,000) to yield 1.5 weight % PEO based on the mixed oxide
equivalent. After mixing to give the required rheology, this feed
was filtered through a 150 micron sieve and spray dried using a
NIRO Mobile Minor spray dryer. The feed was pumped at a rate of 1.0
L/hour to the dryer that has been fitted with disc atomization or
nozzle injection. The inlet temperature is maintained in the range
of 150.degree. C. to 280.degree. C. with the outlet temperature in
the range of 80.degree. C. to 110.degree. C. The green fibre
obtained is then heated to 500.degree. C. to yield the mixed oxide
fibre.
Example 15
[0085] The mixed colloidal dispersion of Examples 9, 10 or 11, was
evaporated to yield a concentration greater than 600 g/L of mixed
oxide equivalent. This feed was spray dried using a NIRO Mobile
Minor spray dryer. The feed was pumped at a rate of 1.0 L/hour to
the dryer that has been fitted with disc atomization or nozzle
injection. The inlet temperature is maintained in the range of
150.degree. C. to 280.degree. C. with the outlet temperature in the
range of 80.degree. C. to 110.degree. C. The green fibre obtained
is then heated to 500.degree. C. to yield the mixed oxide
fibre.
[0086] Although preferred embodiments of the invention have been
described herein in detail, it will be understood by those skilled
in the art that variations may be made thereto without departing
from the spirit of the invention or the scope of the appended
claims.
* * * * *