Note: Descriptions are shown in the official language in which they were submitted.
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POLYMER COMPOSITE AND A METHOD FOR ITS PREPARATION
The present invention relates to a composite comprising a polymer and an
inorganic additive, more specifically, layers of a swellable material, and to a method for
preparing the polymer composite.
Polymer composites comprising a polymer matrix having one or more
additives such as a particulate or fiber material dispersed throughout the continuous polymer
matrix are well known. The additive is often added to enhance one or more properties of the
polymer.
Useful additives include inorganic layered materials such as talc, clays and
mica of micron size.
A number of techniques have been described for dispersing the inorganic
layered material into a polymer matrix. It has been suggested to disperse individual layers,
for example, platelets, of the layered inorganic material, throughout the polymer. However,
without some additional treatment, the polymer will not infiltrate into the space between the
layers of the additive sufficiently and the layers of the layered inorganic material will not be
sufficiently uniformly dispersed in the polymer.
To provide a more uniform dispersion, as described in U.S. Patent 4,889,885,
sodium or potassium ions normally present in natural forms of mica-type silicates and other
multilayered particulate materials are exchanged with organic cations (for example,
alkylammonium ions or suitably functionalized organosilanes) thereby intercalating the
individual layers of the multilayered materials, generally by ionic exchange of sodium or
potassium ions. This intercalation can render the normally hydrophilic mica-type silicates
organophilic and expand its interlayer distance. Subsequently, the layered material
(conventionally referred to as "nanofillers") is mixed with a monomer and/or oligomer of the
polymer and the monomer or oligomer polymerized. The intercalated silicate is described as
having a layer thickness of 7 to 12~ and an interlayer distance of 30A or above.
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In WO 93/~1190, an atternative method for forming a composite is described
in which an intercalated layered, particulate material having reactive organositane
compounds is dispersed in a thermoplastic polymer or vulcanizable rubber.
Yet additional composites containing these so-called nanofillers and/or their
methods of preparation are described in U.S. Patents 4,739,007;4,618,528;4,528,235;
4,874,728;4,889,885;4,810,734;4,889,885;4,810,734; and 5,385,776; German Patent
3808623; Japanese Patent J022083~8; European Patent applications 0,398,551;0,358,415;
0,3~2,042; and 0,398,551; and J. Inclusion Phenomena ~, (1987),473?483; Clay Minerals,
10 23,(1988),27; Polym. Preprints, 32 (April 1991),65-66; Poiym. Prints, 28, ~August 1987),
447-448; and Japan Kokai 76,~i09,998.
However, even with these numerous described composites and methods, it
still remains desirable to have an improved composite and method for forming polymer
15 composites derived from a multilayered additive to make composites having improved
properties over the polymer alone.
Accordingly, in one aspect, the present invention is a composite comprising a
polymer matrix having, dispersed therein, delaminated or exfoliated particles derived from a
20 multilayered inorganic material intercalated with an inorganic intercalant. C)ptionally, an
organic intercalant can also be employed. If employed, the optionally employed organic
intercalant can be calcined or at least partially removed from the multilayered inorganic
material.
In another aspect, the present invention is a composite comprising a polymer
matrix having dispersed therein delaminated or exfoliated particies derived from a
multilayered material which has been intercalated with an organic intercalant only which is
subsequently calcined or otherwise at least partially removed from the layered, reinforcing
material.
In a third aspect, the present invention is a method for forming a composite
which method comprises contacting a polymer or a precursor to the polymer with amultilayered inorganic particulate material intercalated with an inorganic polymeric intercalant
and, optionally, an organic intercalant. If the optionally employed organic intercalant is used,
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it can be calcined or at least partiaiiy removed from the multilayered inorganic material prior
to mixing the material with the polymer.
In a preferred embodiment, the polymer is a melt processible, thermoplastic
polymer and the method comprises mixing the polymer and intercalated material atconditions to disperse the intercalated material into the polymer.
The polymeric compositions of this invention can exhibit an excellent balance
of properties and can exhibit one or more superior properties such as improved heat or
10 chemical resistance, ignition resistance, superior resistance to diffusion of polar liquids ancl of
gases, yield strength in the presence of polar solvents such as water, methanol, or ethanol,
or enhanced stiffness and dimensional stability, as compared to composites which contain
the same multilayered material which has not previously been intercalated or where no
intercalated material is employed.
The composites of the present invention are useful in a wide variety of
applications including transportation (for example, automotive and aircraft) parts, electronics,
business equipment such as computer housings, building and construction materials, and
packaging materials.
In the present invention, the polymer matrix of the composite can be
essentially any normally solid polymer, including both thermoset and thermoplastic poiymers
and vulcanizable and thermoplastic rubbers.
A representative thermoplastic polymer which can be employed to prepare the
composites of the present invention is a thermoplastic polyurethane such as derived from the
reaction of a diisocyanate such as
naphthalene diisocyanate, 3,3'-dimethyl-4,4'-di-phenylmethane diisocyanate, 4,4'-
diphenyliso-propylidene diisocyanate, or 4,4'-diisocyanatodiphenylmethane and linear iong-
chain diol such as poly(tetra-methylene adipate), poly(ethylene succinate), or polyether diol.
Another representative thermoplastic polymer is a polycarbonate such as
prepared by the reaction of an aromatic polyol (for example, resorcinol, catechol,
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hydroquinone, a dihydroxynaphthalene, a dihydroxyanthracene, a bis(hydroxyaryl) fluorene, a
dihydroxyphenanthrene, a dihydroxybiphenyl; and a bis(hydroxyphenyl) propane), more
preferably an aromatic diol, with a carbonate precursor (for example, carbonic acid derivative,
phosgene, haloformate, or carbonate ester such as dimethyl carbonate or diphenylcarbonate, poly(methane bis(4-phenyl) carbonate), or poly(1,1-ether bis(4-phenyl)carbonate).
Yet other representative examples include thermoplastic polymers and
copolymers derived from esters of ethylenically unsaturated methacrylic or acrylic acid such
as poly(methyl or ethyl)acrylate, poly(methyl or ethyl)methacrylate, including copolymers of
methyl methacrylate and a monovinylidene aromatic such as styrene, copolymers of ethylene
and ethyl acrylate, methacrylated and butadiene-styrene copolymers; polymers derived from
ethylenically unsaturated monomers such as polyolefins (for example, polypropylene and
polyethylene including high density polyethylene, linear low density polyethylene, ultra low
linear density polyethylene, homogeneously branched, linear ethylene/~-olefin copoiymers,
homogeneously branched, substantially linear ethylene/~-olefin polymers, and high pressure,
free radical polymerized ethylene copolymers such as ethylene-acrylic acid (EAA)copolymers),highly branched low density polyethylene, and ethylene-vinyl acetate (EVA)
copolymers; polymers of monovinylidene aromatics such as polystyrene and syndiotactic
polystyrene including copolymers thereof such as impact modified polystyrene, styrene-
ethylene copolymers, styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene
copolymers and other styrenic copolymers.
Still other representative examples of thermoplastic polymers include
polyesters such as poly(ethylene-1,5-naphthalate), poly(1,4-cyclohexane dimethylene
terephthalate), poly(ethylene oxybenzoate), poly(para-hydroxy benzoate), polyethylene
terephthalate, or polybutylene terephthalate; polysulfones such as the reaction product of the
sodium salt of 2,2-bis(4-hydroxyphenyl) propane and 4,4'-dichlorodiphenyl sulfone;
polyetherimides; and polymers of ethylenically unsaturated nitriles such as polyacrylonitrile;
poly(epichlorohydrin); polyoxyalkylenes such as poly(ethylene oxide); poly(furan); cellulose-
based plastics such as cellulose acetate, cellulose acetate butyrate; silicone based plasticssuch as poly(dimethyl siloxane) and poly(dimethyl siloxane co-phenylmethyl siloxane);
polyether ether ketones; polyamides such as poly(4-amino butyric acid), poly(hexamethylene
adipamide), poly(6-aminohexanoic acid), and poly(2,2,2-tri-methyl hexamethylene
terephthalamide); polylactones such as poly(pivalolactone) and poly(caprolactone);
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poly(aryleno oxides) such as poly(2,6-dimethyl-1,4-phenylene oxide); poly(arylene sulfides)
such as poly(phenylene sulfide); polyetherimides; acetals; polyvinyl chloride; poly(vinylidene
chloride), and blends of two or more of these polymers.
Preferred thermoplastic polymers include the polymers and copolymers of
ethylene and/or propylene, polymers and copolymers of a monovinylidene aromatic
compound, more preferably styrene, polycarbonates, and thermoplastic polyurethanes or
mixtures thereof. Preferred ethylene polymers and copolymers include linear low density
polyethylenes, low density polyethylenes and the homogeneously branched linear and
10 substantially linear ethylene copolymers with a density (ASTM D-792) of 0.85 to 0.92 g/cm3
more preferably of 0.85 to 0.90 0.92 g/cm3, and a measured melt index (ASTM D-1238
(190/2.16)) of 0.1 to 10 g/minutes; substantially linear, functionalized, ethylene copolymers,
particularly a copolymer of ethylene with vinyl acetate containing from 0.5 to 50 weight
percent units derived from vinyl acetate, are especially preferred, especially copolymers of
15 ethylene with vinyl acetate having a melt index of 0.1 to 10 g/10 minutes; and copolymers of
ethylene with acrylic acid containing from 0.5 to 25 weight percent units derived from acrylic
acid.
Representative vulcanizable and thermoplastic rubbers which may be useful in
20 the practice of the present invention include rubbers such as brominated butyl rubber,
chlorinated butyl rubber, polyurethane elastomers, fluoroelatomers, polyester elastomers,
butadiene/acrylonitrile elastomers, silicone elastomers, rubbers derived from conjugated
dienes such as poly(butadiene), poly(2,3-dimethylbutadiene), poly(butadiene-pentadiene),
and poly(isobutylene), ethylene-propylene-diene terpolymer (EPDM) rubbers and sulfonated
25 EPDM rubbers, poly(chloroprene), chlorosulphonated or chlorinated poly(ethylenes), and
poly(sulfide) elastomers. Other examples include block copolymers made up of segments of
glassy or crystalline blocks such as poly(styrene), poly(vinyl-toluene), poly(t-butyl styrene~, or
polyester and elastomeric blocks such as poly(butadiene), poly(isoprene), ethylene propylene
copolymers, ethylene-butylene copolymers, or polyether ester, for example, poly(styrene)-
30 poly(butadiene)-poly(styrene) block copolymers.
Thermoset resins differ from thermoplastic polymers in that they become
substantlally infusible or insoluble irreversibly since they are cured (cross-linked) as opposed
to the thermoplastics which are typically not cross-linkable and soften when exposed to heat
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and are capable of returning to original conditions when cooled. Representative examples of
thermoset polymers which may be useful in the practice of the present invention include
thermoset phenolic resins such as thermosettable resins containing resorcinol, p-tertiary-
octylphenol, cresol, alkylated phenolic novalac, phenolic polyvinyl butyral, and phenolic cresol
and an aldehyde such as formaidehyde, acetaldehyde or furfural; thermoset polyimide resins
such as those curable resins based on pyromellitic dianhydride, 3,3',4,4'-benzophenone-
carboxylic dianhydride and meta-phenylenediamine; thermoset epoxides or epoxy resins
such as the resins containing the reaction product bisphenol A or derivatives thereof, for
example, the diglycidyl ether of bisphenol A, or a polyol such as glycerol with epichlorohydrin
10 and a cross-linking or curing agent such as a polyfunctional amine, for example,
polyalkylenepolyamine; thermoset polyester resins such as the reaction products of an
unsaturated dicarboxylic acid such as maleic or fumaric acid (which may be used in
combination with a saturated acid such as phthalic or adipic acid3 with a dihydric alcohol such
as ethylene, propylene, diethylene and dipropylene glycol which cure upon using an ethylenic
unsaturated curing agent such as styrene or diallyl phthalate, including thermosettable allyl
resins including resins derived from diallyl phthalates, for example, diallyl orthophthalate,
diallyl isophthalate, diallyl fumarates and diallyi maleates; thermoset polyurethanes including
those derived from the reaction of a diisocyanate, for example, toluene diisocyanate,
methylene diphenyl diisocyanate, or isophorone diisocyanate, or a polymeric isocyanate with
a polyhydric alcohol such as polypropylene glycol and, if required, an additional cross-linking
agent such as water; thermoset urea resins; melamine resins, furan resins, and vinyl ester
resins including epoxy (meth)acrylates.
Of these polymers, the preferred thermoplastic polymers are polycarbonates,
homo- and copolymers of styrene, nylons, polyesters, thermoplastic polyurethanes, and
homo- and copolymers of ethylene and propylene; and the preferred thermoset polymers
include the epoxy and urethane resins.
The inorganic layered material which may be used as the reinforcing agent
can be any swellable material which can be intercalated with an inorganic and an organic
intercalant. Representative examples of inorganic layered materials which may be used in
the practice of the present invention include phyllosilicates such as montmorillonite,
nontronite, beidellite, volkonskoite, hectorite, saponite, sauconite, magadiite, and kenyaite; or
vermiculite. Other representative examples include illite minerals such as ledikite; the
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layered double hydroxides or mixed metal hydroxides such as Mg6AI34(OH)188(CO3)1 7H2O
(see W.T. Reichle, J. Catal., 94 (1985), 547), which have positively charged layers and
exchangeable anions in the interlayer spaces; chlorides such as ReCI3 and FeOCI,chalcogenides such as TiSz, MoS2, and MoS3; cyanides such as Ni(CN~2; and oxides such as
5 H2Si20s, V50,3, HTiNbOs, CrO5V05S2, W02V2807, Cr308, MoO3(0H)2, VOP04-2H20,
CaPO4CH3-H2{), MnHAsO4-H20, or Ag6Mo10O33,. Other layered materials or multi-layer
aggregates having little or no charge on the surface of the layers may also be used in this
invention provided they can be intercalated with swelling agents which expand their interlayer
spacing. Mixtures of one or more such materials may also be employed.
Preferred layered materials are those having charges on the layers and
exchangeable ions such as sodium, potassium, and calcium cations, which can be
exchanged, preferably by ion exchange, with ions, preferably cations such as amrrlonium
cations, or reactive organosilane compounds, that cause the multi-lamellar or layered
particies to delaminate or swell. Typically, the negative charge on the surface of the layered
materials is at least 20 milliequivalents, preferably at least 50 milliequivalents, and more
preferably from ~0 to 120 milliequivalents, per 100 grams of the multilayered material.
Particularly preferred are smectite clay minerals such as montmorillonite, nontronite,
beidellite, volkonskoite, hectorite, saponite, sauconite, magadiite, and kenyaite, with hectorite
and montmorilonite having from 20 milliequivalents to 150 milliequivalents per 100 grams
material being more preferred. Most preferred layered materials are phyllosilic~tes
The multilayered material may be intercalated with an inorganic intercalant
and an organic intercalant. The inorganic intercalant can be an inorganic polymeric
substance or an inorganic solid having a colloidalparticle size. Representative polymeric
substances are substances obtained by hydrolyzing a polymerizable metallic alcoholate such
as Si(OR)4, AI~OR)3, Ge~OR)4, Si(OC)2Hs)4, Si(OCH3)4, Ge(OC3H7), or Ge(OC2Hs)4, either alone
or in combination. Representative colloidal sized particles of an inorganic compound which
can be used include the colloidal sized particles of the hydrolyzed form of SiO2 (for example,
Si(OH) or silica sol), Sb2O3, Fe2O3, Al2O3, TiO2, ZrO2 and SnO2 alone or in any combination.
Most preferably, the grain size of the colloidal inorganic should preferably be in a range of
from 5, more preferably from 10, most preferably from 20, to 250, more preferably t20A.
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While it may be possible to intercalate the unmodified form of the inorganic
material between the layers of the multilayered particulate material, the inorganic intercalant
is preferably modified at its surface by a cationic inorganic compound or a metailic alcoholate
different than the polymerizable metallic alcoholate. Representative cationic inorganic
compounds which may be used to surface treat the inorganic intercalant are titanium
compounds, zirconium compounds, hafnium compounds, iron compounds, copper
compounds, chromium compounds, nickel compounds, zinc compounds, aluminum
compounds, manganese compounds, phosphorus compounds, and boron compounds.
Metallic chlorides such as TiC14, metallic oxychlorides such as ZrCOCI2, and nitrate chloride
10 are preferred. Representative metallic alcoholates which can be used to the treat the surface
of the inorganic intercalant are Ti(OR)4, Zr(OR)4, PO(OR)3, or B(OR)3 alone or combination,
with Ti(OC3H,)4, Zr(OC3H7)4, PO(OCH3)3, PO(OC2Hs)3, B(OCH3)3, B(OC2H5)3 being preferred.
The organic intercalant can be any organic material which displaces, totally or
in part, the ions originally on the surface of the multilayered material. In general, the
intercalant contains a functional group which interacts with the negative charges on the
surface of that material. In addition, the intercalant preferably also contains a functional
group reactive with the matrix polymer or possesses some property such as cohesive energy,
a capacity for dispersive, polar, or hydrogen-bonding interactions or other specific
interactions, such as acid/base or Lewis-acid/Lewis-base interactions, to promote the
intermingling ("compatibility") of the matrix polymer and multilayered material.
The organic intercalant can be a water soluble polymer, a reactive
organosilane compound, an onium compound such as an ammonium, phosphonium or
sulfonium salt, an amphoteric surface active agent, or a choline compound.
Representative examples of water-soluble polymers which can be employed
as the organic intercalant in the practice of this invention are water soluble polymers of vinyi
alcohol (for example, poly(vinyl alcohol); polyalkylene glycols such as polyethylene glycol;
water soluble cellulosics polymers such methyl cellulose and carboxymethyl cellulose, the
polymers of ethylenically unsaturated carboxylic acids such as poly(acrylic acid), and their
salts, or polyvinyl pyrrolidone.
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Representative examples of onium compounds include quaternary ammonium
salts (cationic surface active agents) having octadecyl, hexadecyl, tetradecyl, dodecyl or like
moieties; with preferred quaternary ammonium salts inciuding octadecyl trimethyl ammonium
salt, dioctadecyi dimethyl ammonium salt, hexadecyl trimethyl ammonium salt, dihexadecyl
dimethyl ammonium sait, tetradecyl trimethyl ammonium salt, or ditetradecyl dimethyl
ammonium salt .
Representative examples of the amphoteric surface-active agent which can be
employed in this invention include surfactants having an aliphatic amine cationic moiety and a
10 carboxyl, sulfate, sulfone or phosphate as the anionic moiety. Representative examples of
choline compounds include [HOCH2CH2N(CH~)3]+0H-, CsH,4ClNO, CsH,4NOC4H506,
CsH,4NOC~H70,, and CsH14NOC6H,207 .
Representative examples of organosilane compounds include silane agents of
the formula:
~-)nsiR~4~nm)R1m
where (-) is a covalent bond to the surface of the layered material, m is 0, 1 or 2; n is 1, 2 or 3
with the proviso that the sum of m and n is equal to 3; R' is a nonhydrolyzable organic radical
~including alkyl, alkoxyalkyl, alkylaryl, arylalkyl, alkoxyaryl) and is not displaceable during the
formation of the composite; R is the same or different at each occurrence and is an organic
radical which is not hydrolyzable and displaceable during the formation of the composite
which is reactive with the polymer matrix or at least one monomeric component of the
polymer. Representative R groups include amino, carboxy, acylhalide, acyloxy, hydroxy,
isocyanato ureido, halo, epoxy, or epichlorohydryl. Preferred organosilane intercalants
include long chain branched quaternary ammonium salts and/or suitably functionalized
organosilane compounds, as disclosed in WO 93/11190, pages 9-21.
- Organic materials other than those described can also be employed as the
organic intercalants provided they can be intercalated between the layers of the multilayered
particulate material and subsequently degraded such as by calcination to at least partially
remove the intercalant and leave gaps between the layers.
In the practice of the present invention, the multilayered particulate material is
intercalated with the inorganic, if employed, and organic intercalants. While the method of
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intercalation is not particulariy critical, in one embodiment of the present invention, prior to
intercalating the multilayered material, it is swollen in an aqueous or organic liquid. Any
aqueous or organic liquid capable of swelling the multilayered material being intercalated can
be employed. By aqueous liquid it is meant water, including acids and bases as well as
some salt solutions. In addition, solutions of water and one or more water-miscible organic
Iiquids such as the iower alkyl alcohols, for example, methanol and butanol, can be
employed. Representative examples of organic liquids which can be employed include
dimethylformamide, dimethylsulfone, halogenated hydrocarbons, for example, methylene
chloride, or a liquid hydrocarbon, preferably having from 4 to 15 carbon atoms, including
10 aromatic and aliphatic hydrocarbons or mixtures thereof such as heptane, benzene, xylene,
cyclohexane, toluene, mineral oils and liquid paraffins, for example, kerosene and naphtha.
The polymerizable inorganic intercalant is formed as a solution in a suitable solvent such as
ethyl alcohol, or isopropyl alcohol and subsequently hydrolyzed, preferably in the presence of
the multilayered material. For example, a mixture of the multilayered material, swollen in an
15 appropriate swelling material, and the polymerizable inorganic intercalant can be contacted
with a hydrolyzing agent for the polymerizable intercalant to form the inorganic polymer. In
general, the hydrolyzation is conducted at a temperature above 70~C. Subsequent to partial
or complete polymerization, the organic intercalant can be added. The organic intercalant
reacts upon the hydrolyzed surfaces of the layered material.
In the event a colloidal inorganic intercalant is used the organic intercalant can
be added to a dispersion of the colloidal inorganic intercalant. Subsequently, the reaction
product of the organic intercalant with the inorganic intercalant is mixed with the swollen
multilayered material. While the conditions of such intercaiation may vary, in general, it is
advantageously conducted at a temperature of from 30~C to 100~C, more advantageously
25 from 60~C to 70~C.
Following intercalation, the intercalated multilayered filler can be dehydrated
by conventional means such as centrifugal separation and then dried. While drying
conditions most advantageously employed will be dependent on the specific intercalant and
30 multilayered particulate material employed, in general, drying is conducted at temperatures of
at least 40~C to 1 00~C and more advantageously at a temperature of 50~C to 80~C by any
conventional means such as a hot air oven. The organic intercalant can then optionally be
calcined such as by heating to 300~C to 600~C, preferably from 450~G to 550~C.
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In another embodiment of the present invention, the organic intercalant can be
employed to intercalate the multilayered particulate material but the inorganic intercalant is
not employed. In this embodiment, the organic intercalant is calcined such as by heating to
300~C to 600~C, preferably from 450~C to 550~C.
Following intercalation and, if conducted, calcination, the intercalant in tbe
multilayered material forms a layer of charge opposite to the charge on the surface of the
layers of the multilayered particles with the interiayer spacing being dependent on the
intercalants employed and whether the organic intercalant has been calcined or otherwise
10 partially or totally removed. In general, the inter-layer spacing (that is, distance between the
faces of the layers as they are assembled in the intercalated material) is from 5 to 600~ (as
determined by X-ray diffraction) whereas prior to intercalation the interlayer spacing is usually
equal to or less than 4~. This increase in interlayer spacing permits greater penetration of
the polymer matrix into the filler. Preferably, the interlayer spacing of the intercalated filler is
15 at least 8A, more preferably at least 12/b and less than 100~, more preferably less than 30~.
Following preparation of the intercalated multilayered material, the
intercalated, multilayered material and matrix polymer are combined to form the desired
composite.
The amount of the intercalated multilayered material most advantageously
incorporated into the polymer matrix is dependent on a variety of factors including the specific
intercalated material and polymer used to form the composite as well as its desired
properties. Typical amounts can range from 0.001 to 90 weight percent of the intercalated,
layered material based on the weight of the total composite. Generally, the composite
comprises at least 0.1, preferably 1, more preferably 2, and most preferably 4 weight percent
and less than 60, preferably 50, more preferably 45 and most preferably 40 weight percent of
the intercalated, layered material based on the total weight of the composite.
The intercalated, layered material can be dispersed in the monomer(s) which
form the polymer matrix and the monomer(s) polymerized in situ or alternatively, can be
dispersed in the polymer, in melted or liquid form.
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Melt blending is one method for preparing the composites of the present
invention, particularly when forming the composite from a thermoplastic polymer.Techniques for melt blending of a polymer with additives of all types are known in the art and
can typically be used in the practice of this invention. Typically, in a melt blending operation
useful in the practice of the present invention, the polymer is heated to a temperature
sufficient to form a polymer melt and combined with the desired amount of the intercalated,
multilayered material in a suitable mixer, such as an extruder, a Banbury Mixer, a 13rabender
mixer, or a continuous mixer.
In the practice of the present invention, the melt blending is preferably carried
out in the absence of air, such as in the presence of an inert gas, such as argon, neon, or
nitrogen. The melt blending operation can be conducted in a batch or discontinuous fashion
but is more preferably conducted in a continuous fashion in one or more processing zones
such as in an extruder from which air is largely or completely excluded. The extrusion can be
conducted in one zone or step or in a plurality of reaction zones in series or parallel.
Alternatively, the matrix polymer may be granulated and dry mixed with the
intercalated, multilayered material, and thereafter, the composition heated in a mixer until the
polymer is melted to form a flowable mixture. This flowable mixture can then be subjected to
a shear in a mixer sufficient to form the desired composite. This type of mixing and
composite preparation is advantageously employed to prepare composites from boththermoplastic and thermoset polymers.
A polymer melt containing the intercalated, multilayered particulate material
may also be formed by reactive melt processing in which the intercalated, multilayered
material is initially dispersed in a liquid or solid monomer or cross-linking agent which will
form or be used to form the polymer matrix of the composite. This dispersion can be injected
into a polymer melt containing one or more polymers in an extruder or other mixing device.
The injected liquid may result in new polymer or in chain extension, grafting or even cross-
linking of the polymer initially in the melt.
Methods for preparing a composite using in situ type polymerization are alsoknown in the art and reference is made thereto for the purposes of this invention. In applying
this technique to the practice of the present invention, the composite is formed by mixing
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monomers and/or oligomers with the intercalated, multilayered material and subsequently
polymerizing the monomer and/or oligomers to form the polymer matrix of the composite.
The intercalated, multilayered material is advantageously dispersed under
conditions such that at least 80, preferably at least 85, more preferably at least 90, and most
preferably at least 95, weight percent of the layers of the intercalated, multilayered, material
delaminate to form individual layers dispersed in the polymer matrix. These layers may be
platelet particles having two relatively flat or slightly curved opposite faces where the distance
between the faces is relatively small compared to the size of the faces, or needle-like
particles. It is quite probable that the layers of the filler will not delaminate completely in the
polymer, but will form layers in a coplanar aggregate. These layers are advantageously
sufficiently dispersed or exfoliated in the matrix polymer such that at least 80 percent of the
layers are in small multiples of less than 10, preferably less than ~, and more preferably les
than 3, of the layers.
The dimensions of the dispersed delaminated layers may vary greatly, but in
the case of particles derived from clay minerals, the particle faces are roughly hexagonal,
circular, elliptical, or rectangular and exhibit maximum diameters or length from 50 to 2,000~.
As such, the aspect ratio of length/thickness ranges from 10 to 2,000. The aspect ratio which
is most advan~ageously employed will depend on the desired end-use properties. The
particle faces may also be needle-like.
Optionally, the composites of the present invention may contain various other
additives such as nucleating agents, other fillers, lubricants, plasticizers, chain extenders,
colorants, mold release agents, antistatic agents, pigments, or fire retardants,. The optional
additives and ~heir amounts employed are dependent on a variety of factors including the
desired end-use properties.
The composites of this invention exhibit useful properties. For example, they
may exhibit enhanced yield strength and tensile modulus, even when exposed to poiar media
such as water or methanol; enhanced heat resistance and impact strength; improved
stiffness, wet-melt strength, dimensional stability, and heat deflection temperature, and
decreased moisture absorption, flammability, and permeability as compared to the same
polymers which contain the same multilayered material which has not previously been
intercalated or where no intercalated material is employed. Improvements in one or more
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properties can be obtained even though small amounts of intercalated multilayered materials
are employed.
The properties of the composites of the present invention may be further
5 enhanced by post-treatment such as by heat treating or annealing the composite at an
elevated temperature, conventionally from 80~C to 230~C. Generaliy, the annealing
temperatures will be more than 100~C, preferably more than 1 tO~C, and more preferably
more than 120~C, to less than 250~C, preferably less than 220~C, and more preferably less
than 180CC.
The composites of the present invention can be molded by conventional
shaping processes such as melt spinning, casting, vacuum molding, sheet molding, injection
molding and extruding. Examples of such molded articles include components for technical
equipment, apparatus castings, household equipment, sports equipment, bottles, containers,
components for the electrical and electronics industries, car components, and fibers. The
composites may also be used for coating articles by means of powder coating processes or
as hot-melt adhesives.
The composite material may be directly molded by injection molding or heat
pressure molding, or mixed with other polymers. Alternatively, it is also possible to obtain
molded products by performing the in situ polymerization reaction in a mold.
The molding compositions according to the invention are also suitable for the
production of sheets and panels using conventional processes such as vacuum or hot-
pressing. The sheets and panels can be used to coat materials such as wood, glass,ceramic, metal or other plastics, and outstanding strengths can be achieved using
conventional adhesion promoters, for example, those based on vinyl resins. The sheets and
panels can also be laminated with other plastic films such as by coextrusion, the sheets
being bonded in the molten state. The surfaces of the sheets and panels, can be finished by
conventional methods, for example, by lacquering or by the application of protective films.
The composites of this invention are also useful for fabrication of extruded films and film
laminates, as for example, films for use in food packaging. Such films can be fabricated
using conventional film extrusion techniques. The films are preferably from 10 to 10û, more
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preferably from 20 to 100, and most preferably from 25 to 75, microns thick.
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