U.S. patent application number 10/828457 was filed with the patent office on 2007-07-26 for inorganic-organic polymer nanocomposite and methods for making and using.
Invention is credited to Koichi Takamura.
Application Number | 20070173580 10/828457 |
Document ID | / |
Family ID | 46324976 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070173580 |
Kind Code |
A1 |
Takamura; Koichi |
July 26, 2007 |
INORGANIC-ORGANIC POLYMER NANOCOMPOSITE AND METHODS FOR MAKING AND
USING
Abstract
A method of forming a composition comprising adding at least one
first compound that is at least one of an alkali metal salt, an
ammonium salt, an alkali metal hydroxide, or an ammonium hydroxide
and at least one second compound that is at least one of a Group
IIA salt, a Group IIIA salt, a Group IIIB salt, a copper salt, a
zinc salt, a cadmium salt, a manganese salt, an iron salt, a cobalt
salt, or a nickel salt to a latex. This method allows for the
formation of nanoparticles in the composition.
Inventors: |
Takamura; Koichi;
(Charlotte, NC) |
Correspondence
Address: |
BASF CORPORATION;Patent Department
1609 BIDDLE AVENUE
MAIN BUILDING
WYANDOTTE
MI
48192
US
|
Family ID: |
46324976 |
Appl. No.: |
10/828457 |
Filed: |
April 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10332894 |
Mar 10, 2003 |
6855754 |
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PCT/US02/33343 |
Jun 18, 2002 |
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10828457 |
Apr 20, 2004 |
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09790273 |
Feb 21, 2001 |
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10332894 |
Mar 10, 2003 |
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PCT/US01/44988 |
Nov 29, 2001 |
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10828457 |
Apr 20, 2004 |
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09790273 |
Feb 21, 2001 |
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10828457 |
Apr 20, 2004 |
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60256709 |
Dec 18, 2000 |
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Current U.S.
Class: |
524/423 |
Current CPC
Class: |
C08L 95/005 20130101;
C08K 2201/014 20130101; C08K 3/01 20180101; C08L 95/00 20130101;
C08L 2666/08 20130101; C08L 2666/08 20130101; C08L 53/00 20130101;
C08L 95/005 20130101; C08L 53/00 20130101; C08L 2666/74 20130101;
C08L 2666/74 20130101; C08L 53/02 20130101; C08K 3/01 20180101;
C08L 95/00 20130101; C08L 95/005 20130101; C08L 95/005 20130101;
C08K 3/013 20180101; C08L 95/00 20130101; C08L 95/00 20130101; C08L
95/005 20130101 |
Class at
Publication: |
524/423 |
International
Class: |
C08K 3/30 20060101
C08K003/30 |
Claims
1. A method of forming a composition comprising adding at least one
first compound in an amount from greater than 0 to about 4 parts by
weight of the composition that is at least one of an alkali metal
salt, an ammonium salt, an alkali metal hydroxide, or an ammonium
hydroxide and at least one second compound in an amount from
greater than 0 to about 2 parts by weight of the composition that
is at least one of a Group IIA salt, a Group IIIA salt, a Group
IIIB salt, a copper salt, a zinc salt, a cadmium salt, a manganese
salt, an iron salt, a cobalt salt, or a nickel salt to a latex,
wherein the salts of the at least one second compound are selected
from the group consisting of chlorides, sulfates nitrates, and
combinations thereof, and the latex remains a stable
dispersion.
2. The method of claim 1 further comprising drying the
composition.
3. The method of claim 1, wherein the at least one first compound
is added before the at least one second compound.
4. The method of claim 1, wherein the at least one second compound
is added before the at least one first compound.
5. (canceled)
6. (canceled)
7. The method of claim 1, wherein the salts of the at least one
first compound are selected from the group consisting of sulfates,
carbonates, silicates, phosphates, phosphites, borates, fluorides,
sulfites, oxalates, citrates, and combinations thereof.
8. The method of claim 1, wherein the alkali metal of the at least
one first compound is at least one of sodium or potassium.
9. The method of claim 1, wherein the at least one first compound
is selected from the group consisting of sodium hydroxide (NaOH),
sodium sulfate (Na.sub.2SO.sub.4), sodium bisulfate (NaHSO.sub.4),
sodium carbonate (Na.sub.2CO.sub.3), sodium bicarbonate
(NaHCO.sub.3), sodium metasilicate (Na.sub.2SiO.sub.3), sodium
disilicate (Na.sub.2Si.sub.2O.sub.5), sodium orthosilicate
(Na.sub.4SiO.sub.4), sodium orthophosphate (Na.sub.3PO.sub.4),
disodium hydrogen phosphate (Na.sub.2HPO.sub.4), sodium dihydrogen
phosphate (NaH.sub.2PO.sub.4), hexasodium metaphosphate
((NaPO.sub.3).sub.6), trisodium metaphosphate ((NaPO.sub.3).sub.3),
sodium triphosphate (Na.sub.5P.sub.3O.sub.10), sodium hypophosphite
(NaH.sub.2PO.sub.2), sodium dihydrogen orthophosphite
(NaH.sub.2PO.sub.3), sodium metaborate (NaBO.sub.2), sodium sulfite
(Na.sub.2SO.sub.3), sodium citrate (Na.sub.3C.sub.6H.sub.5O.sub.7),
potassium hydroxide (KOH), potassium sulfate (K.sub.2SO.sub.4),
potassium bisulfate (KHSO.sub.4), potassium carbonate
(K.sub.2CO.sub.3), potassium bicarbonate (KHCO.sub.3), potassium
sodium carbonate (KNaCO.sub.2), potassium metasilicate
(K.sub.2SiO.sub.3), potassium tetrasilicate
(K.sub.2Si.sub.4O.sub.9), potassium orthophosphate
(K.sub.3PO.sub.4), dipotassium hydrogen phosphate
(K.sub.2HPO.sub.4), potassium dihydrogen phosphate
(KH.sub.2PO.sub.4), hexapotassium metaphosphate
((KPO.sub.3).sub.6), tetrapotassium metaphosphate
((KPO.sub.3).sub.4), potassium pyrophosphate
(K.sub.4P.sub.2O.sub.7), potassium subphosphate (K.sub.2PO.sub.3),
potassium hypophosphite (KH.sub.2PO.sub.2), potassium dihydrogen
orthophosphite (KH.sub.2PO.sub.3), potassium metaborate
(KBO.sub.2), potassium tetraborate (K.sub.2B.sub.4O.sub.7),
potassium fluoride (KF), potassium sulfite (K.sub.2SO.sub.3),
potassium hydrogen sulfite (KHSO.sub.3), potassium citrate
(K.sub.3C.sub.6H.sub.5O.sub.7), monobasic potassium citrate
(KH.sub.2C.sub.6H.sub.5O.sub.7), ammonium hydroxide (NH.sub.4OH),
ammonium sulfate ((NH.sub.4).sub.2SO.sub.4), ammonium bisulfate
(NH.sub.4HSO.sub.4), ammonium carbonate ((NH.sub.4).sub.2CO.sub.3),
ammonium bicarbonate (NH.sub.4HCO.sub.3), ammonium orthophosphate
((NH.sub.4).sub.3PO.sub.4), diammonium hydrogen phosphate
((NH.sub.4).sub.2HPO.sub.4), ammonium dihydrogen phosphate
(NH.sub.4H.sub.2PO.sub.4), ammonium sodium phosphate
(NaNH.sub.4HPO.sub.4), ammonium hypophosphite
(NH.sub.4H.sub.2PO.sub.2), ammonium dihydrogen orthophosphite
(NH.sub.4H.sub.2PO.sub.3), ammonium fluoride (NH.sub.4F), ammonium
sulfite ((NH.sub.4).sub.2SO.sub.3), ammonium bisulfite
(NH.sub.4HSO.sub.3), ammonium binoxalate (NH.sub.4HC.sub.2O.sub.4),
diammonium citrate ((NH.sub.4).sub.2HC.sub.6H.sub.5O.sub.7),
triammonium citrate ((NH.sub.4).sub.3C.sub.6H.sub.5O.sub.7), and
combinations thereof.
10. (canceled)
11. The method of claim 1, wherein the at least one second compound
is selected from the group consisting of calcium chloride
(CaCl.sub.2), calcium nitrate (Ca(NO.sub.3).sub.2), magnesium
chloride (MgCl.sub.2), magnesium nitrate (Mg(NO.sub.3).sub.2),
magnesium sulfate (MgSO.sub.4), aluminum chloride (AlCl.sub.3),
aluminum nitrate (Al(NO.sub.3).sub.3), aluminum sulfate
(Al.sub.2(SO.sub.4).sub.3), beryllium chloride (BeCl.sub.2),
beryllium nitrate (Be(NO.sub.3).sub.2), beryllium sulfate
(BeSO.sub.4), copper (II) chloride (CuCl.sub.2), copper (II)
nitrate (Cu(NO.sub.3).sub.2), copper (II) sulfate (CuSO.sub.4),
strontium chloride (SrCl.sub.2), strontium nitrate
(Sr(NO.sub.3).sub.2), barium chloride (BaCl.sub.2), barium nitrate
(Ba(NO.sub.3).sub.2), zinc chloride (ZnCl.sub.2), zinc nitrate
(Zn(NO.sub.3).sub.2), zinc sulfate (ZnSO.sub.4), cadmium chloride
(CdCl.sub.2), cadmium nitrate (Cd(NO.sub.3).sub.2), cadmium sulfate
(CdSO.sub.4), scandium chloride (ScCl.sub.3), scandium nitrate
(Sc(NO.sub.3).sub.3), scandium sulfate (Sc.sub.2(SO.sub.4).sub.3),
gallium chloride (GaCl.sub.3), gallium nitrate
(Ga(NO.sub.3).sub.3), gallium sulfate (Ga.sub.2(SO.sub.4).sub.3),
indium chloride (InCl.sub.3), indium nitrate (In(NO.sub.3).sub.3),
indium sulfate (In.sub.2(SO.sub.4).sub.3), lanthanum chloride
(LaCl.sub.3), lanthanum nitrate (La(NO.sub.3).sub.3), manganese
(II) chloride (MnCl.sub.2), manganese (II) nitrate
(Mn(NO.sub.3).sub.2), manganese (II) sulfate (MnSO.sub.4), iron
(II) chloride (FeCl.sub.2), iron (II) nitrate (Fe(NO.sub.3).sub.2),
iron (II) sulfate (FeSO.sub.4), iron (III) chloride (FeCl.sub.3),
iron (III) nitrate (Fe(NO.sub.3).sub.3), iron (III) sulfate
(Fe.sub.2(SO.sub.4).sub.3), cobalt (II) chloride (CoCl.sub.2),
cobalt (II) nitrate (Co(NO.sub.3).sub.2), cobalt (II) sulfate
(CoSO.sub.4), cobalt (III) chloride (CoCl.sub.3), nickel chloride
(NiCl.sub.2), nickel nitrate (Ni(NO.sub.3).sub.2), nickel sulfate
(NiSO.sub.4), and combinations thereof.
12. The method of claim 1, wherein combinations of the at least one
first compound and the at least one second compound are selected
from the group consisting of I+V, II+V, IlIl+V, IV+V, I+IV+V, I+VI,
II+VI, III+VI, I+VII, II+VII, and IlIl+VlI, wherein I) at least one
of sodium hydroxide, sodium carbonate, sodium silicate, and/or
sodium phosphate; II) at least one of potassium hydroxide,
potassium carbonate, potassium silicate, and/or potassium
phosphate; III) at least one of ammonium hydroxide, ammonium
carbonate, ammonium silicate, and/or ammonium phosphate; IV) at
least one of sodium sulfate, potassium sulfate, and/or ammonium
sulfate; V) at least one of calcium chloride and/or calcium
nitrate; VI) at least one of magnesium chloride, magnesium nitrate,
and/or magnesium sulfate; and VII) at least one of aluminum
chloride, aluminum nitrate, and/or aluminum sulfate.
13. The method of claim 1, wherein the at least one first compound
is at least one of a sodium salt or sodium hydroxide, and the at
least one second compound is at least one of calcium chloride
and/or calcium nitrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. Ser. No.
10/332,894, filed 14 Jan. 2003, which is a national stage
application of [0002] A. International Application No.
PCT/US02/33343, which was filed on 18 Jun. 2002, which is a
continuation-in-part of International Application No.
PCT/US01/44988, which was filed on 20 Nov. 2001 (20.11.01), which
claims priority to U.S. Serial No. 09/790,273, filed on 21 Feb.
2001 (21.02.01), and to U.S. Serial No. 60/256,709, filed on 18
Dec. 2000 (18.12.00), and [0003] B. International Application No.
PCT/US01/44988, which was filed on 20 Nov. 2001 (20.11.01), which
claims priority to U.S. Ser. No. 09/790,273, filed on 21 Feb. 2001
(21.02.01), and to U.S. Ser. No. 60/256,709, filed on 18 Dec. 2000
(18.12.00), all of which are iricorporated herein by reference.
BACKGROUND OF THE INVENTION
[0004] Inorganic particles and/or clays have typically been
incorporated into polymeric compositions during the polymerization
of the polymer. This forms a nanocomposite composition. This method
may be difficult to accomplish. It would be desirable to have a
method of forming nanocomposite compositions without the difficulty
of addition of the nanoparticles during polymerization.
SUMMARY OF THE INVENTION
[0005] The invention relates to a method of forming a composition
comprising adding at least one first compound that is at least one
of an alkali metal salt, an ammonium salt, an alkali metal
hydroxide, or an ammonium hydroxide and at least one second
compound that is at least one of a Group IIA salt, a Group IIIA
salt, a Group IIIB salt, a copper salt, a zinc salt, a cadmium
salt, a manganese salt, an iron salt, a cobalt salt, or a nickel
salt to a latex.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a photo-micrograph of fine inorganic crystals
generated by mixing equal volume of 30% aqueous CaCI.sub.2 and 35%
(NH.sub.4).sub.2HP0.sub.4 solutions.
[0007] FIG. 2 is a photo-micrograph of a thin cross-section of
dried latex film containing approximately 2 wt % of Ca-phosphate
nano-crystals.
[0008] FIG. 3(a) is a graph of the tensile strength vs. elongation
of BUTONAL.RTM. NX1118 latex film with and without Ca-phosphate
nano-crystals. The latex was dried one day in room temperature then
placed in an oven of 60.degree. C. for additional 24 hours. FIG.
3(b) is a graph of the tensile strength of the same films after
being immersed in water for 24 hours.
[0009] FIG. 4 is a graph of tensile strength vs. elongation similar
to FIG. 3, but BUTONAL.RTM. NS198 latex was used instead of the
BUTONAL.RTM. NX1118 latex.
[0010] FIG. 5 is a graph of tensile strength vs elongation for the
BUTONAL.RTM. NX1118 latex film with and without Ca-phosphate
nano-crystals. The latex films were heat treated at 100.degree. C.
for 3 hours after drying in ambient temperature for 6 days.
[0011] FIGS. 6(a) and (b) are graphs of tensile strength vs.
elongation for the latex films heat aged for 20 minutes (a) and 40
minutes (b) in a forced airflow oven at 160.degree. C.
[0012] FIG. 7 is a graph of tensile strength vs. elongation with
BUTONAL.RTM. NS198 latex and Ca-phosphate nano-crystal modified
latex.
DETAILED DESCRIPTION
[0013] As used throughout, ranges are used as a shorthand for
describing each and every value that is within the.range. Any value
within the range can be selected as the terminus of the range. When
used, the phrase "at least one of" refers to the selection of any
one member individually or any combination of the members. The
conjunction "and" or "or" can be used in the list of members, but
the "at least one of" phrase is the controlling language. For
example, at least one of A, B, and C is shorthand for A alone, B
alone, C alone, A and B, B and C, A and C, or A and B and C.
[0014] In the following detailed description, preferred embodiments
are described in detail to enable practice of the invention.
Although the invention is described with reference to these
specific preferred embodiments, it will be understood that the
invention is not limited to these preferred embodiments. But to the
contrary, the invention includes numerous alternatives,
modifications and equivalents as will become apparent from
consideration of the following detailed description.
[0015] The present invention includes a composition formed by
mixing a polymer latex, at least one first compound selected from
the group consisting of alkali metal salts, ammonium salts, alkali
metal hydroxides, and ammonium hydroxide; and at least one second
compound preferably selected from the group consisting of Group
IIA, Group IIIA, Group IIIB, copper, zinc, cadmium, manganese,
iron, cobalt and nickel salts. By combining alkali metal or
ammonium salts or hydroxides in solution, and one or more salts
such as a Group IIA, Group IIIA, Group IIIB, copper, zinc, cadmium,
manganese, iron, cobalt or nickel salts in solution, a composition
is formed that contains fine inorganic crystals. When the latex is
dried, a latex polymer nanocomposite is formed. The polymer
nanocomposite has improved mechanical and heat aging properties as
compared to the polymer without the inorganic particles.
[0016] The latex can be any latex. The latex is prepared before the
addition of the first or second compound. Suitable polymer latices
include, but are not limited to, cationic SBR (styrene-butadiene
rubber) latices, natural rubber latices, polychloroprene latices
(e.g. NEOPRENES.RTM. latices available from E.I. Du Pont de
Nemours), carboxylated (polystyrene-butadiene) latices, and acrylic
latices. The list of various latices can be found in "Polymer
Dispersions and Their Industrial Applications" ed. by D. Urban and
K. Takamura, Wiley-VCH, 2002. These latices used for this invention
should maintain their dispersion stability during the process.
Preferably, a cationic SBR latex is used. The cationic SBR latex
emulsion typically includes between about 0.1 and about 10%, and
more preferably, between about 2% and about 6% by weight cationic
surfactants. The latex used for this invention should remain as a
stable dispersion by the addition of aqueous solutions of the
second compounds. Suitable cationic SBR latices include
BUTONAL.RTM. NX1118 and BUTONAL.RTM. NS 198, commercially available
from BASF Corporation.
[0017] The present composition is prepared by mixing at least one
compound selected from the group consisting of alkali metal salts,
alkali metal hydroxides, ammonium salts, and ammonium hydroxide in
the composition. The alkali metal and ammonium salts and hydroxides
are preferably added to the composition in aqueous solution in an
amount from greater than 0 to about 4 parts by weight, more
preferably, from about 0.005 to about 3 parts by weight (based on
the weight of the salt or hydroxide and not the salt or hydroxide
solution). Because the alkali metal and ammonium salts and
hydroxides added to the composition are added in aqueous solution,
the salts and hydroxide of the invention are water-soluble and
preferably have a solubility in water at 20.degree. C. of greater
than about 10 g/100 mL. The salts for use in the invention include
but are not limited to sulfates, carbonates, silicates, phosphates,
phosphites, borates, fluorides, sulfites, oxalates and citrates.
Suitable alkali metal and ammonium salts and hydroxides for use in
the invention include but are not limited to sodium hydroxide
(NaOH), sodium sulfate (Na.sub.2SO.sub.4), sodium bisulfate
(NaHSO.sub.4), sodium carbonate (Na.sub.2CO.sub.3), sodium
bicarbonate (NaHCO.sub.3), sodium metasilicate (Na.sub.2SiO.sub.3),
sodium disilicate (Na.sub.2Si.sub.2O.sub.5), sodium orthosilicate
(Na4SiO.sub.4), sodium orthophosphate (Na.sub.3PO.sub.4), disodium
hydrogen phosphate (Na.sub.2HPO.sub.4), sodium dihydrogen phosphate
(NaH.sub.2PO.sub.4), hexasodium metaphosphate ((NaPO.sub.3).sub.6),
trisodium metaphosphate ((NaPO.sub.3).sub.3), sodium triphosphate
(Na.sub.5P.sub.3O.sub.10), sodium hypophosphite
(NaH.sub.2PO.sub.2), sodium dihydrogen orthophosphite
(NaH.sub.2PO.sub.3), sodium metaborate (NaBO.sub.2), sodium sulfite
(Na.sub.2SO.sub.3), sodium citrate (Na.sub.3C.sub.6H.sub.5O.sub.7),
potassium hydroxide (KOH), potassium sulfate (K.sub.2SO.sub.4),
potassium bisulfate (KHSO4), potassium carbonate (K.sub.2CO.sub.3),
potassium bicarbonate (KHCO.sub.3), potassium sodium carbonate
(KNaCO.sub.2), potassium metasilicate (K.sub.2SiO.sub.3), potassium
tetrasilicate (K.sub.2Si4O.sub.9), potassium orthophosphate
(K.sub.3PO.sub.4), dipotassium hydrogen phosphate
(K.sub.2HPO.sub.4), potassium dihydrogen phosphate
(KH.sub.2PO.sub.4), hexapotassium metaphosphate
((KPO.sub.3).sub.6), tetrapotassium metaphosphate
((KPO.sub.3).sub.4), potassium pyrophosphate
(K.sub.4P.sub.2O.sub.7), potassium subphosphate (K.sub.2PO.sub.3),
potassium hypophosphite (KH.sub.2PO.sub.2), potassium dihydrogen
orthophosphite (KH.sub.2PO.sub.3), potassium metaborate
(KBO.sub.2), potassium tetraborate (K.sub.2B.sub.40.sub.7),
potassium .fluoride (KF), potassium sulfite (K.sub.2SO.sub.3),
potassium hydrogen sulfite (KHSO.sub.3), potassium citrate
(K.sub.3C.sub.6H.sub.50.sub.7), monobasic potassium citrate
(KH.sub.2C.sub.6H.sub.5O.sub.7), ammonium hydroxide (NH.sub.4OH),
ammonium sulfate ((NH.sub.4).sub.2SO.sub.4), ammonium bisulfate
(NH.sub.4HSO.sub.4), ammonium carbonate ((NH.sub.4).sub.2CO.sub.3),
ammonium bicarbonate (NH.sub.4HCO.sub.3), ammonium orthophosphate
((NH.sub.4).sub.3PO.sub.4), diammonium hydrogen phosphate
((NH.sub.4).sub.2HPO.sub.4), ammonium dihydrogen phosphate
(NH.sub.4H.sub.2PO.sub.4), ammonium sodium phosphate
(NaNH.sub.4HPO.sub.4), ammonium hypophosphite
(NH.sub.4H.sub.2PO.sub.2), ammonium dihydrogen orthophosphite
(NH.sub.4H.sub.2PO.sub.3), ammonium fluoride (NH.sub.4F), ammonium
sulfite ((NH.sub.4).sub.2SO.sub.3), ammonium bisulfite
(NH.sub.4HSO.sub.3), ammonium binoxalate (NH.sub.4HC.sub.20.sub.4),
diammonium citrate ((NH.sub.4).sub.2HC.sub.6H.sub.5O.sub.7) and
triammonium citrate ((NH.sub.4).sub.3C.sub.6H.sub.5O.sub.7).
Preferably, the alkali metal and ammonium salts and hydroxides are
salts and hydroxides of sodium, potassium and ammonium and, more
preferably, are hydroxides, sulfates, carbonates, silicates and
phosphates of sodium, potassium and ammonium. In a preferred
embodiment, the alkali metal and ammonium salts and hydroxides
include sodium hydroxide. The alkali metal and ammonium salts and
hydroxides can be provided in hydrated or anhydrous form for use in
the invention.
[0018] The alkali metal and ammonium salts and hydroxides provide
cations that react with the Group IIA, Group IIIA, Group IIIB,
copper, zinc, cadmium, manganese, iron, cobalt and nickel salts
preferably used in the invention as discussed below. Preferably,
the alkali metal and ammonium salts and hydroxides are provided in
stoichiometric excess with respect to these Group IIA, Group IIIA,
Group IIIB, copper, zinc, cadmium, manganese, iron, cobalt and
nickel salts. In addition, a sufficient amount of the alkali metal
and ammonium salts and hydroxides are generally included to
increase the pH of the overall composition to a pH of at least
about 9. If an alkali metal or ammonium salt is used that cannot
produce the desired pH in solution such as the salt of a strong
acid and strong base (e.g. sodium sulfate), at least one alkali
metal or ammonium salt or hydroxide that provides alkalinity to the
composition, i.e., a base such as sodium hydroxide or the salt of a
weak acid and strong base such as sodium carbonate, is preferably
additionally included to provide the desired pH.
[0019] At least one compound preferably selected from the group
consisting of Group IIA (e.g. Be, Mg, Ca, Sr, Ba), Group IIIA (e.g.
Sc, La), Group IIIB (e.g. Al, Ga, In), copper, zinc, cadmium,
manganese, iron, cobalt and nickel salts is also added to the
composition. In addition, water-soluble salts having other cations
can be used in accordance with the invention that react with the
alkali metal and ammonium salts and hydroxides to produce a salt or
hydroxide having a solubility in water at 20.degree. C. of less
than about 0.5 g/100 mL. The Group IIA, Group IIIA, Group IIIB,
copper, zinc, cadmium, manganese, iron, cobalt and nickel salts are
preferably added to the composition in aqueous solution in an
amount from greater than 0 to about 2 parts by weight, more
preferably, in an amount from about 0.001 to about 1 part by weight
(based on the weight of the salt). Preferably, the Group IIA, Group
IIIA, Group IIIB, copper, zinc, cadmium, manganese, iron, cobalt
and nickel salts added to the composition of the invention are
water-soluble and preferably have a solubility in water at
20.degree. C. of greater than about 10 g/100 mL. For example, the
Group IIA, Group IIIA, Group IIIB, copper, zinc, cadmium,
manganese, iron, cobalt and nickel salts can be chlorides, sulfates
or nitrates. Suitable Group IIA, Group IIIA, Group IIIB, copper,
zinc, cadmium, manganese, iron, cobalt and nickel salts include but
are not limited to calcium chloride (CaCl.sub.2), calcium nitrate
(Ca(NO.sub.3).sub.2), magnesium chloride (MgCl.sub.2), magnesium
nitrate (Mg(NO.sub.3).sub.2), magnesium sulfate (MgSO.sub.4),
aluminum chloride (AlCl.sub.3), aluminum nitrate
(Al(NO.sub.3).sub.3), aluminum sulfate (Al.sub.2(SO.sub.4).sub.3),
beryllium chloride (BeCl.sub.2), beryllium nitrate
(Be(NO.sub.3).sub.2), beryllium sulfate (BeSO.sub.4), copper (II)
chloride (CuCl.sub.2), copper (II) nitrate (Cu(NO.sub.3).sub.2),
copper (II) sulfate (CuSO.sub.4), strontium chloride (SrCl.sub.2),
strontium nitrate (Sr(NO.sub.3).sub.2), barium chloride
(BaCl.sub.2), barium nitrate (Ba(NO.sub.3).sub.2), zinc chloride
(ZnCl.sub.2), zinc nitrate (Zn(NO.sub.3).sub.2), zinc sulfate
(ZnSO.sub.4), cadmium chloride (CdCl.sub.2), cadmium nitrate
(Cd(NO.sub.3).sub.2), cadmium sulfate (CdSO.sub.4), scandium
chloride (ScCl.sub.3), scandium nitrate (Sc(NO.sub.3).sub.3),
scandium sulfate (Sc.sub.2(SO.sub.4).sub.3), gallium chloride
(GaCl.sub.3), gallium nitrate (Ga(NO.sub.3).sub.3), gallium sulfate
(Ga.sub.2(SO.sub.4).sub.3), indium chloride (InCl.sub.3), indium
nitrate (In(NO.sub.3).sub.3), indium sulfate
(In.sub.2(SO.sub.4).sub.3), lanthanum chloride (LaCl.sub.3),
lanthanum nitrate (La(NO.sub.3).sub.3), manganese (II) chloride
(MnCl.sub.2), manganese (II) nitrate (Mn(NO.sub.3).sub.2),
manganese (II) sulfate (MnSO.sub.4), iron (II) chloride
(FeCl.sub.2), iron (II) nitrate (Fe(NO.sub.3).sub.2), iron (II)
sulfate (FeSO.sub.4), iron (III) chloride (FeCl.sub.3), iron (III)
nitrate (Fe(NO.sub.3).sub.3), iron (III) sulfate
(Fe.sub.2(SO.sub.4).sub.3), cobalt (II) chloride (COCl.sub.2),
cobalt (II) nitrate (Co(NO.sub.3).sub.2), cobalt (II) sulfate
(CoSO.sub.4), cobalt (III) chloride (CoCl.sub.3), nickel chloride
(NiCl.sub.2), nickel nitrate (Ni(NO.sub.3).sub.2), and nickel
sulfate (NiSO.sub.4). Preferably, the Group IIA, Group IIIA, Group
IIIB, copper, zinc, cadmium, manganese, iron, cobalt and nickel
salts are calcium, magnesium or aluminum salts such as calcium
chloride (CaCl.sub.2), calcium nitrate (Ca(NO.sub.3).sub.2),
magnesium chloride (MgCl.sub.2), magnesium nitrate
(Mg(NO.sub.3).sub.2), magnesium sulfate (MgSO.sub.4), aluminum
chloride (AlCl.sub.3), aluminum nitrate (Al(NO.sub.3).sub.3), and
aluminum sulfate (Al.sub.2(SO.sub.4).sub.3). More preferably, the
Group IIA, Group IIIA, Group IIIB, copper, zinc, cadmium,
manganese, iron, cobalt and nickel salts include calcium chloride
or calcium nitrate. The Group IIA, Group IIIA, Group IIIB, copper,
zinc, cadmium, manganese, iron, cobalt and nickel salts can be
provided in hydrated or anhydrous form.
[0020] The alkali metal and ammonium salts and hydroxides added to
the composition react with the Group IIA, Group IIIA, Group IIIB,
copper, zinc, cadmium, manganese, iron, cobalt and nickel salts
added to the composition to produce at least one Group IIA, Group
IIIA, Group IIIB, copper, zinc, cadmium, manganese, iron, cobalt or
nickel salt or hydroxide having a low solubility in water (if any).
Preferably, the Group IIA, Group IIIA, Group IIIB, copper, zinc,
cadmium, manganese, iron, cobalt and nickel salts or hydroxides
produced by the reaction have a solubility in water at 20.degree.
C. of less than about 0.5 g/100 mL. For example, the Group IIA,
Group IIIA, Group IIIB, copper, zinc, cadmium, manganese, iron,
cobalt and nickel salts and hydroxides produced by the reaction of
the salts added to the composition include but are not limited to
calcium hydroxide (Ca(OH).sub.2), calcium sulfate (CaSO.sub.4),
calcium carbonate (CaCO.sub.3), calcium metasilicate (CaSiO.sub.3),
calcium orthosilicate (Ca.sub.2SiO.sub.4), tricalcium silicate
(3CaO SiO.sub.2), calcium orthophosphate
(Ca.sub.3(PO.sub.4).sub.2), dicalcium orthophosphate (CaHPO.sub.4),
monocalcium orthophosphate (Ca(H.sub.2PO.sub.4).sub.2), calcium
hypophosphate (Ca.sub.2P.sub.2O.sub.6), calcium metaphosphate
(Ca(PO.sub.3).sub.2), calcium pyrophosphate
(Ca.sub.2P.sub.2O.sub.7), calcium orthophosphite (CaHPO.sub.3),
calcium tetraborate (CaB.sub.4O.sub.7), calcium metaborate
(Ca(BO.sub.2).sub.2), calcium fluoride (CaF.sub.2), calcium sulfite
(CaSO.sub.3), calcium oxalate (CaC.sub.2O.sub.4), calcium citrate
(Ca.sub.3(C.sub.6H.sub.5O.sub.7).sub.2), aluminum hydroxide
(Al(OH).sub.3), aluminum silicate (Al.sub.2O.sub.3 SiO.sub.2 or
3Al.sub.2O.sub.3 2SiO.sub.2), aluminum orthophosphate (AlPO.sub.4),
aluminum fluoride (AlF.sub.3), aluminum oxalate
(Al.sub.2(C.sub.2O.sub.4).sub.3), magnesium hydroxide
(Mg(OH).sub.2), magnesium carbonate (MgCO.sub.3), magnesium
metasilicate (MgSiO.sub.3), magnesium orthosilicate
(Mg.sub.2SiO.sub.4), magnesium orthophosphate
(Mg.sub.3(PO.sub.4).sub.2), magnesium monohydrogen orthophosphate
(MgHPO.sub.4), magnesium pyrophosphate (Mg.sub.2P.sub.2O.sub.7),
magnesium orthophosphite (MgHPO.sub.3), magnesium metaborate
(Mg(BO.sub.2).sub.2), magnesium orthoborate
(Mg.sub.3(BO.sub.2).sub.2), magnesium fluoride (MgF.sub.2),
magnesium oxalate (MgC.sub.2O.sub.4), beryllium hydroxide
(Be(OH).sub.2), beryllium carbonate (BeCO.sub.3), beryllium
orthosilicate (Be.sub.2SiO.sub.4), copper (II) hydroxide
(Cu(OH).sub.2), copper (II) carbonate (CuCO.sub.3), copper (II)
orthophosphate (Cu.sub.3(PO.sub.4).sub.2), copper (I) fluoride
(CuF), copper (II) oxalate (CuC.sub.2O.sub.4), copper citrate
(Cu.sub.2C.sub.6H.sub.4O.sub.7), strontium hydroxide
(Sr(OH).sub.2), strontium sulfate (SrSO.sub.4), strontium carbonate
(SrCO.sub.3), strontium metosilicate (SrSiO.sub.2), strontium
orthosilicate (SrSiO.sub.4), strontium orthophosphate
(Sr.sub.3(PO.sub.4).sub.2), strontium monohydrogen orthophosphate
(SrHPO.sub.4), strontium tetraborate (SrB.sub.4O.sub.7), strontium
fluoride (SrF.sub.2), strontium sulfite (SrSO.sub.2), strontium
oxalate (SrC.sub.2O.sub.4), barium sulfate (BaSO.sub.4), barium
carbonate (BaCO.sub.3), barium metasilicate (BaSiO.sub.3), barium
monohydrogen orthophosphate (BaHPO.sub.4), tribarium orthophosphate
(Ba.sub.3(PO.sub.4).sub.2), barium hypophosphate (BaPO.sub.3),
barium pyrophosphate (Ba.sub.2P.sub.2O.sub.7), barium fluoride
(BaF.sub.2), barium sulfite (BaSO.sub.3), barium oxalate
(BaC.sub.2O.sub.4), barium citrate
(Ba.sub.3(C.sub.6H.sub.5O.sub.7).sub.2), zinc hydroxide
(Zn(OH).sub.2), zinc carbonate (ZnCO.sub.3), zinc silicate (2ZnO
SiO.sub.2), zinc metasilicate (ZnSiO.sub.3), zinc orthosilicate
(Zn.sub.2SiO.sub.4), zinc orthophosphate
(Zn.sub.3(PO.sub.4).sub.2), zinc pyrophosphate
(Zn.sub.2P.sub.2O.sub.7), zinc sulfite (ZnSO.sub.3), zinc oxalate
(ZnC.sub.2O.sub.4), zinc citrate
(Zn.sub.3(C.sub.6H.sub.5O.sub.7).sub.2), cadmium hydroxide
(Cd(OH).sub.2), cadmium carbonate (CdCO.sub.3), cadmium
metasilicate (CdSiO.sub.3), cadmium orthophosphate
(Cd.sub.3(PO.sub.4).sub.2), cadmium pyrophosphate
(Cd.sub.2P.sub.2O.sub.7), cadmium dihydrogen phosphate
(Cd(H.sub.2PO.sub.4).sub.2), cadmium sulfite (CdSO.sub.3), cadmium
oxalate (CdC.sub.2O.sub.4), scandium hydroxide (Sc(OH).sub.3),
gallium hydroxide (Ga(OH).sub.3), gallium fluoride (GaF.sub.3),
gallium oxalate (Ga.sub.2(C.sub.2O.sub.4).sub.3), indium hydroxide
(In(OH).sub.3), indium fluoride (InF.sub.3), lanthanum hydroxide
(La(OH).sub.3), lanthanum carbonate (La.sub.2(CO.sub.3).sub.3),
lanthanum oxalate (La.sub.2(C.sub.2O.sub.4).sub.3), manganese (II)
hydroxide (Mn(OH).sub.2), manganese (III) hydroxide (Mn(OH).sub.3),
manganese (II) carbonate (MnCO.sub.3), manganese (II) metasilicate
(MnSiO.sub.3), manganese (II) monohydrogen orthophosphate
(MnHPO.sub.4), manganese (III) orthophosphate (MnPO.sub.4),
manganese (III) metaphosphate (Mn.sub.2(PO.sub.3).sub.6), manganese
(II) pyrophosphate (Mn.sub.2P.sub.2O.sub.7), manganese (II)
orthophosphite (MnHPO.sub.3), manganese (II) oxalate
(MnC.sub.2O.sub.4), manganese (II) citrate
(Mn.sub.3(C.sub.6H.sub.5O.sub.7).sub.2), iron (II) hydroxide
(Fe(OH).sub.2), iron (II) carbonate (FeCO.sub.3), iron (II)
metasilicate (FeSiO.sub.3), iron (II) orthosilicate
(Fe.sub.2SiO.sub.4), iron (II) orthophosphate
(Fe.sub.3(PO.sub.4).sub.2), iron (III) orthophosphate (FePO.sub.4),
iron (III) orthophosphate (FePO.sub.4), iron (III) pyrophosphate
(Fe.sub.4(P.sub.2O.sub.7).sub.3), iron (III) hypophosphite
(Fe(H.sub.2PO.sub.2).sub.3), iron (II) fluoride (FeF.sub.2), iron
(I (FeF.sub.3), iron (II) sulfite (FeSO.sub.3), iron (II) oxalate
(FeC.sub.2O.sub.4), iron (II) citrate (FeC.sub.6H.sub.6O.sub.7), i
citrate (FeC.sub.6H.sub.5O.sub.7), cobalt (II) hydroxide
(Co(OH).sub.2), cobalt (III) hydroxide (Co(OH).sub.3), cobalt (II)
carbonate (COCO.sub.3), cobalt (III) carbonate
(Co.sub.2(CO.sub.3).sub.3), cobalt (II) orthosilicate
(Co.sub.2SiO.sub.4), cobalt (II) orthophosphate
(Co.sub.3(PO.sub.4).sub.2), cobalt (II) sulfite (CoSO.sub.3),
cobalt (II) oxalate (COC.sub.2O.sub.4), nickel hydroxide
(Ni(OH).sub.2), nickel carbonate (NiCO.sub.3), nickel
orthophosphate (Ni.sub.3(PO.sub.4).sub.2), nickel sulfite
(NiSO.sub.3) and nickel oxalate (NiC.sub.2O.sub.4). Typically,
because the calcium, magnesium and aluminum salts are preferred,
the composition includes one or more of the above calcium,
magnesium or aluminum salts. The alkali metal and ammonium salts
resulting from the reaction typically include one or more of sodium
chloride, sodium sulfate, sodium nitrate, potassium chloride,
potassium sulfate, potassium nitrate, ammonium chloride, ammonium
sulfate or ammonium nitrate.
[0021] Some exemplary combinations of the alkali metal and ammonium
salts or hydroxides and the Group IIA, Group IIIA, Group IIIB,
copper, zinc, cadmium, manganese, iron, cobalt and nickel salts
added to the composition include the following: I+V, II+V, III+V,
IV+V, I+IV +V, I+VI, II+VI, III+VI, I+VII, II+VII, and III+VII,
wherein: [0022] I. sodium hydroxide, sodium carbonate, sodium
silicate and/or sodium phosphate; [0023] II. potassium hydroxide,
potassium carbonate, potassium silicate and/or potassium phosphate;
[0024] III. ammonium hydroxide, ammonium carbonate, ammonium
silicate and/or ammonium phosphate; [0025] IV. sodium sulfate,
potassium sulfate and/or ammonium sulfate; [0026] V. calcium
chloride and/or calcium nitrate; [0027] VI. magnesium chloride,
magnesium nitrate and/or magnesium sulfate; and [0028] VII.
aluminum chloride, aluminum nitrate and/or aluminum sulfate.
[0029] More preferably, the first compound includes ammonium or
sodium salts or hydroxide (e.g. ammonium hydroxide or NaOH) and the
second compound includes calcium chloride and/or calcium
nitrate.
[0030] Furthermore, the alkali metal and ammonium salts and
hydroxides listed above and other alkali metal and ammonium salts
can be combined with the Group IIA, Group IIIA, Group IIIB, copper,
zinc, cadmium, manganese, iron, cobalt and nickel salts listed
above or any other Group IIA, Group IIIA, Group IIIB, copper, zinc,
cadmium, manganese, iron, cobalt and nickel salts in many other
combinations in accordance with the invention to provide the
desired pH and a Group IIA, Group IIIA, Group IIIB, copper, zinc,
cadmium, manganese, iron, cobalt and nickel salt or hydroxide
having a low solubility in water.
[0031] The order of addition is not critical but preferred such
that the addition of the first compound would not significantly
change the latex pH or coagulate it. The at least one first
compound can be added before, after, or at the same time as the at
least one second compound. If a cationic latex is used, the pH is
generally 4-5, so the hydroxide or salts should be added as the
second compound to prevent pH increase, which may cause increase in
the latex viscosity. To prevent coagulation, incremental amounts of
the at least one first compound and the at least one second
compound can be made until the entire amount of each is added.
Also, the at least one first compound and the at least one second
compound could be mixed together and added to the latex.
[0032] The alkali metal or ammonium salts or hydroxides in the
composition include the salts formed by the reaction between the
salts and hydroxides added to the composition as discussed above.
Excess alkali metal and ammonium salts and hydroxides added to the
composition such as sodium hydroxide are typically also present,
particularly if desired to maintain the pH of the composition at a
pH of at least about 9. The composition also includes at least one
Group IIA, Group IIIA, Group IIIB, copper, zinc, cadmium,
manganese, iron, cobalt or nickel salt or hydroxide having low
water solubility, e.g., a solubility in water at 20.degree. C. of
less than about 0.5 g/100 mL, and exemplary salts and hydroxides
are mentioned above. The Group IIA, Group IIIA, Group IIIB, copper,
zinc, cadmium, manganese, iron, cobalt and nickel salts added to
the composition (e.g. calcium chloride) can also be present in
small amounts.
[0033] The latex can be dried to provide a nanocomposite film. The
drying can be accomplished by any drying method. The film has
increased tensile strength, elongation, and heat resistance as
compared to a film prepared without the nanoparticles. The film
prepared with this nanoparticles are especially unique of achieving
significantly improved elongation without reducing the tensile
strength. Generally, a polymer film of lower tensile strength has a
high elongation, but a stronger polymer has a limited elongation.
This nanoparticle modified film prepared by the method of the
invention maintains the same or slightly higher tensile strength
with significantly improved elongation as compared to a latex that
was not modified by the method of the invention.
[0034] As shown above, there are a number of possible combinations
of alkali metal and ammonium salts and hydroxides and Group IIA,
Group IIIA, Group IIIB, copper, zinc, cadmium, manganese, iron,
cobalt and nickel salts that can be used in accordance with the
invention. Therefore, there is a lot of flexibility in the method
of the present invention in selecting salts for the preparation of
the compositions. In addition, the amounts of each salt used can
affect the resulting compositions.
[0035] The present invention will now be further described by the
following non-limiting examples. Except where otherwise indicated,
percentages are on a per weight basis and solutions are aqueous
solutions.
[0036] It is understood that upon reading the above description of
the present invention, one skilled in the art could make changes
and variations therefrom. These changes and variations are included
in the spirit and scope of the following appended claims.
EXAMPLE 1
[0037] 5 g of 30% aqueous CaCl.sub.2 (calcium chloride) solution
was added into an equal amount of 35% aqueous
(NH.sub.4).sub.2HPO.sub.4 (ammonium biphosphate) solution. Fine
white precipitate formed immediately upon addition of drops of
ammonium biphosphate solution into the calcium chloride solution.
Precipitates were diluted with water and optical microscope
observation showed the presence of fine platelets of less than 1
micrometer thick and 3-5 micrometer length as shown in FIG. 1.
EXAMPLE 2
[0038] 5 g of 30% aqueous CaCl.sub.2 (calcium chloride) solution
was added into 100 g of cationic styrene-butadiene latex,
BUTONAL.RTM. NX1118 from BASF Corporation. The latex remained as a
stable dispersion. After mixing, 5 g of 35% aqueous
(NH.sub.4).sub.2HPO.sub.4 (ammonium biphosphate) solution was added
under agitation. The latex pH remained below 4.5 during and at the
end of (NH.sub.4).sub.2HPO.sub.4 addition. This procedure was
expected to produce approximately 2 wt % of calcium phosphate
(Ca-phosphate) nano-crystals in the latex polymer. A thin latex
film of approximately 250 .mu.m was prepared by diluting the latex
dispersion from 65% solids to 45% solids with water, spreading the
dispersion on a polytetrafluoroethylene plate, and drying at room
temperature. Masking tape was applied at four comers of the plate
to keep the latex dispersion wetting the plate. After completely
drying, the film was cut to expose a thin cross-section, and the
cross-section was observed under the optical microscope. The
presence of fine nano-crystals was apparent in the entire polymer
film as shown in FIG. 2.
EXAMPLE 3
[0039] The latex dispersion prepared in Example 2 was dried for one
day at room temperature to prepare the latex film as described
above, then cured in an oven at 60.degree. C. for 24 hours. As
comparison, a latex film was also prepared from BUTONAL.RTM. NX1118
latex without addition of calcium chloride or ammonium biphosphate
solutions. These latex films were cut to rectangular latex films of
approximately 3 mm wide and 25 mm long. The tensile strength of the
films with and without Ca-phosphate crystals was determined.
[0040] Measured tensile strength of these latex films were shown in
FIG. 3a. The BUTONAL.RTM. NX1118 latex was not fully dried with the
above described condition and the film had only limited strength of
slightly below 0.5 MPa peak strength and broken at about 250%
elongation. The film developed a thin filament (necking) under
elongation and broke from that weak point. In contrast, the 2%
Ca-phosphate nano-crystal modified latex film did not develop the
necking and maintained its original dimension during elongation
even at above 3,000% elongation and the tensile strength reached
nearly 0.6 MPa at this elongation. The latex film did not break at
3,200% elongation, which was the limit of the instrument used.
[0041] The above-described latex films were soaked in water for one
day, and the tensile strength measured. Excess water was absorbed
with paper towel prior of the measurement. The tensile strength of
the BUTONAL.RTM. NX1118 latex film dropped to below 0.4 MPa peak
strength after immersing in water for 24 hours, and it broke at
about 200% elongation (FIG. 3b). The Ca-phosphate modified latex
film also lost peak strength, but maintained 0.2 MPa strength above
1,000% elongation and did not break even at 3,200% elongation.
EXAMPLE 4
[0042] 5 g of 30% aqueous CaCl.sub.2 (calcium chloride) solution
was added into 100 g of cationic styrene-butadiene latex,
BUTONAL.RTM. NS198 from BASF Corporation. The latex dispersion was
dried for 6 days at room temperature and cured in an oven at
60.degree. C. for 24 hours. As comparison, the latex film was also
prepared with BUTONAL.RTM. NS198 latex without calcium chloride or
ammonium biphosphate solutions. The tensile strength of these films
was determined as in Example 3 and results are shown in FIG. 4. The
latex film of the BUTONAL.RTM. NS198 latex showed slightly above
0.4 MPa maximum tensile strength and the film broke at slightly
above 500% elongation. In contrast, the latex film with
Ca-phosphate nano-crystals did not break even at 3000% elongation
at the maximum tensile strength of 0.45 MPa.
EXAMPLE 5
[0043] The latex film of BUTONAL.RTM. NX1118 modified with
Ca-phosphate nano-crystals was prepared as in Example 3, but it was
dried for 6 days at room temperature and then placed in an oven at
100.degree. C. for 3 hours. The latex film showed only slight
discoloration to light brown after 3 hours of heat aging. In
comparison, the latex film of the BUTONAL.RTM. NX1118 latex became
brown after the same heat treatment. The latex film modified with
Ca-phosphate nano-crystals maintained above 3000% elongation after
the heat treatment. In contrast, the unmodified BUTONAL.RTM. NX1118
latex film was broken at slightly above 2100% elongation.
EXAMPLE 6
[0044] Ca-phosphate nano-crystal modified and unmodified
BUTONAL.RTM. NX1118 latex films were prepared as in Example 5, but
after drying 6 days at room temperature, the films were placed in a
forced airflow oven at 160.degree. C. for 20 minutes. The
unmodified BUTONAL.RTM. NX1118 latex film discolored and had a
brown color. The Ca-phosphate nano-crystal modified film showed
only slight discoloration. The latex films were also heat aged for
40 minutes at the same condition. The unmodified latex film became
dark brown after 40 minutes of heat aging, but the Ca-phosphate
nano-crystal modified one showed less discoloration.
[0045] The tensile strength of the latex film and the Ca-phosphate
nano-crystal modified film were determined after 20 minutes and 40
minutes heat aging at 160.degree. C. (FIG. 6a and b). The
Ca-phosphate modified films maintained above 3000% elongation even
after these severe heat agings.
EXAMPLE 7
[0046] BUTONAL.RTM. NS198 latex modified with Ca-phosphate
nano-crystals was prepared as in Example 4. This latex dispersion
was dried for 6 days at room temperature and heat aged for 40
minutes in a forced airflow oven at 160.degree. C. A latex film of
BUTONAL.RTM.D NS198 latex was also prepared and heat aged at the
same condition. The BUTONAL.RTM. NS198 latex film became dark brown
after 40 minutes of heat aging, but the Ca-phosphate nano-crystal
modified film was lighter color than the unmodified film. The
tensile strength of both latex films was determined and results are
shown in FIG. 7. The unmodified film broke at slightly above 2100%
elongation, but the Ca-phosphate nano-crystal modified film did not
break even at 3000% elongation.
* * * * *