METHOD FOR CONTROLLING HAZE IN AN ARTICLE COMPRISING A
POLYMER COMPOSITION
BACKGROUND OF THE INVENTION
This invention relates to a method for controlling haze in an article comprising a
polymer composition. More particularly the method relates to controlling haze in
articles comprising polymer compositions, which compositions comprise an alkali
metal halide.
An almost infinite variety of articles comprising polymeric materials form an integral
part of modern commerce and technology. The utility of many such articles depends
upon the transparent nature of the polymer composition from which the article is
fabricated. In many applications requiring a high degree of optical clarity, the haze
level exhibited by the article cannot exceed a certain threshold level. Certain polymer
compositions exhibit a very high level of transparency and low haze values, for
example, polycarbonate. However, other physical properties of such materials, for
example glass transition temperature, make them unsuitable for use in many
applications requiring both a high level of optical clarity and substantial resistance to
the effects of heat. Many polymer compositions are available which possess
outstanding heat resistance, but which are prone to afford articles fabricated from said
polymer compositions which exhibit an unacceptable level of haze.
In some instances, the level of haze exhibited by an article comprising a polymer
composition is found to be dependent upon the method by which the polymer
composition itself is prepared. For example, articles fabricated using polyetherimide
polymer compositions exhibit higher or lower levels of haze depending on the method
used to prepare the constituent polyetherimide. Polyetherimide compositions are
commercially attractive materials due to their combination of high heat performance,
good mechanical properties, chemical resistance and ease of processing. Commercial
Ultem181 polyetherimide compositions find applications in dishware, film, silicon wafer
carriers, and like applications, wherein, low haze is a critical quality factor. Typical
haze levels of commercial Ultem® polyetherimide compositions are found to be below
2%.
As noted, however, the haze levels exhibited by articles fabricated from
polyetherimide compositions are dependent on the process followed to prepare them.
Currently, commercially available polyetherimide compositions are produced using a
"nitro-displacement" process to generate bisphenol-A dianhydride (BPADA) in a
series of steps starting from a mixture of 3-nitro- and 4-nitro-N-methylphthalimide.
The polyetherimide composition is then prepared in a condensation polymerization of
the BPADA with a diamine, such as meta-phenylenediamine. In an alternate
approach, the diamine is first reacted with chlorophthalic anhydride to form a bischlorophthalimide,
which is then reacted with the alkali metal salt of a bisphenol (e.g.
bisphenol A disodium salt) in a "chloro-displacement" polymerization process. In
contrast to the nitro-displacement process, the chloro-displacement process appears to
have advantages with respect to both process simplicity and compositional flexibility.
However, articles fabricated using polyetherimide prepared using the "chlorodisplacement"
process were found unaccountably to exhibit significantly higher haze
levels than articles fabricated using polyetherimide made by the "nitro-displacement"
process. The higher haze levels observed in articles fabricated using polyetherimide
prepared using "chloro-displacement" polymerization detracts significantly from the
commercial attractiveness of the "chloro-displacement" process technology.
Hence, there exists a need to provide a method for controlling haze in an article
comprising polymer compositions, and particularly in articles comprising polymer
compositions prepared using methods allied to the chloro-displacement process used
to prepare polyetherimide compositions.
BRIEF SUMMARY OF THE INVENTION
In one aspect the present invention provides a method for controlling haze in an
article comprising a polymer composition, said method comprising:
(a) providing a polymer composition comprising less than about 25 parts per
million alkali metal halide; and
(b) fabricating an article from said polymer composition.
In a further aspect the present invention provides a method for controlling haze in an
article comprising a polyetherimide composition, said method comprising:
(a) providing a polyetherimide composition comprising less than about 25 parts
per million alkali metal chloride; and
(b) fabricating an article from said polyetherimide composition.
BRIEF DESCRIPTION OF FIGURE
Figure I shows the correlation between sodium chloride concentration in
polyetherimide resin prepared via the chloro-displacement polymerization process and
haze in standard test articles prepared from the polyetherimide resins. The solid lines
are model predictions for haze resulting from the presence of sodium chloride
particles of I and 2 micrometer (urn) average size.
DETAILED DESCRIPTION OF THE INVENTION
The present invention may be understood more readily with reference to the following
detailed description of preferred embodiments of the invention and the examples
included therein. In the following specification and the claims which follow, reference
will be made to a number of terms which shall be defined to have the following
meanings.
The singular forms "a", "an" and "the" include plural referents unless the context
clearly dictates otherwise.
"Optional" or "optionally" means that the subsequently described event or
circumstance may or may not occur, and that the description includes instances where
the event occurs and instances where it does not.
As used herein the term "aliphatic radical" refers to a radical having a valence of at
least one comprising a linear or branched array of atoms which is not cyclic. The
array may include heteroatoms such as nitrogen, sulfur, silicon, selenium and oxygen
or may be composed exclusively of carbon and hydrogen. Aliphatic radicals may be
"substituted" or "unsubstituted". A substituted aliphatic radical is defined as an
aliphatic radical which comprises at least one substituent. A substituted aliphatic
radical may comprise as many substituents as there are positions available on the
aliphatic radical for substitution. Substituents which may be present on an aliphatic
radical include but are not limited to halogen atoms such as fluorine, chlorine,
bromine, and iodine. Substituted aliphatic radicals include trifluoromethyl,
hexafiuoroisopropylidene, chloromethyl; difluorovinylidene; trichloromethyl,
bromoethyl, bromotrimethylene (e.g. -CH2CHBrCH2-). and the like. For convenience,
the term "unsubstituted aliphatic radical" is defined herein to encompass, as part of
the "linear or branched array of atoms which is not cyclic" comprising the
unsubstituted aliphatic radical, a wide range of functional groups. Examples of
unsubstituted aliphatic radicals include allyl, aminocarbonyl (i.e. -CONH2), carbonyl,
dicyanoisopropylidene (i.e. -CH2CHBrCH2-), methyl (i.e. -CH2), methylene (i.e. -
CHz-). ethyl, ethylene, formyl, hexyl, hexamethylene, hydroxymethyl (i.e.-CH20H),
mercaptomethyl (i.e. -CH2SH), methylthio (i.e. -SCH2), methylthiomethyl (i.e. -
CH2SCHa), methoxy, methoxycarbonyl, nitromethyl (i.e. -CH2NOz), thiocarbonyl,
trimethylsilyl, t-butyldimethylsilyl, trimethyoxysilypropyl, vinyl, vinylidene, and the
like. Aliphatic radicals are defined to comprise at least one carbon atom. A C1 - C10
aliphatic radical includes substituted aliphatic radicals and unsubstituted aliphatic
radicals containing at least one but no more than 10 carbon atoms.
As used herein, the term "aromatic radical" refers to an array of atoms having a
valence of at least one comprising at least one aromatic group. The array of atoms
having a valence of at least one comprising at least one aromatic group may include
heteroatoms such as nitrogen, sulftir, selenium, silicon and oxygen, or may be
composed exclusively of carbon and hydrogen. As used herein, the term "aromatic
radical" includes but is not limited to phenyl, pyridyl, furanyl, thienyl, naphthyl,
phenylene, and biphenyl radicals. As noted, the aromatic radical contains at least one
aromatic group. The aromatic group is invariably a cyclic structure having 4n+2
"delocalized" electrons where "n" is an integer equal to 1 or greater, as illustrated by
phenyl groups (n = 1), thienyl groups (n = 1), furanyl groups (n « 1), naphthyl groups
(n = 2), azulenyl groups (n = 2), anthraceneyl groups (n = 3) and the like. The
aromatic radical may also include nonaromatic components. For example, a benzyl
group is an aromatic radical which comprises a phenyl ring (the aromatic group) and a
methylene group (the nonaromatic component). Similarly a tetrahydronaphthyl radical
is an aromatic radical comprising an aromatic group (C6H3) fused to a nonaromatic
component -{CH2)4-. Aromatic radicals may be "substituted" or "unsubstituted". A
substituted aromatic radical is defined as an aromatic radical which comprises at least
one substituent. A substituted aromatic radical may comprise as many substituents as
there are positions available on the aromatic radical for substitution. Substituents
which may be present on an aromatic radical include, but are not limited to halogen
atoms such as fluorine, chlorine, bromine, and iodine. Substituted aromatic radicals
include trifluoromethylphenyl, hexafluoroisopropylidenebis(4-phenyloxy) (i.e. -
OPhC(CF3)2PhO-), chloromethylphenyl; 3-trifluoroviny1-2-thienyl; 3-
trichloromethylphenyl (i.e. 3-CCl3Ph-), bromopropylphenyl (i.e. BrCH2CH2CH2Ph-),
and the like. For convenience, the term "unsubstituted aromatic radical" is defined
herein to encompass, as part of the "array of atoms having a valence of at least one
comprising at least one aromatic group", a wide range of functional groups.
Examples of unsubstituted aromatic radicals include 4-allyloxyphenoxy, aminophenyl
(i.e. H2NPh-), aminocarbonylphenyl (i.e. NH2COPh-), 4-benzoylphenyl,
dicyanoisopropylidenebis(4-phenyloxy) (i.e. -OPhC(CN)2PhO-), 3-methylphenyl,
methylenebis(4-phenyloxy) (i.e. -OPhCH2PhO-), ethylphenyl, phenylethenyl, 3-
formyl-2-thienyl, 2-hexyl-5-furanyl; hexamethylene-l,6-bis(4-phenyloxy) (i.e. -
OPh(CH2)6PhO-); 4-hydroxymethylphenyl (i.e. 4-HOCH2Ph-), 4-
mercaptomethylphenyl (i.e. 4-HSCH2Ph-), 4-methylthiophenyl (i.e. 4-CHjSPh-),
methoxyphenyl, methoxycarbonylphenyloxy (e.g. methyl salicyl), nitromethylphenyl
(i.e. -PhCH2N02), trimethylsilylphenyl, t-butyldimethylsilylphenyl, vinylphenyl,
vinylidenebis(phenyl), and the like. The term "a C3 - C10 aromatic radical" includes
substituted aromatic radicals and unsubstituted aromatic radicals containing at least
three but no more than 10 carbon atoms. The aromatic radical 1-imidazolyl (CaH2N2-)
represents a C3 aromatic radical. The benzyl radical (C7H8-) represents a C7 aromatic
radical.
As used herein the term "cycloaliphatic radical" refers to a radical having a valence of
at least one, and comprising an array of atoms which is cyclic but which is not
aromatic. As defined herein a "cycloaliphatic radical" does not contain an aromatic
group. A "cycloaliphatic radical" may comprise one or more noncyclic components.
For example, a cyclohexylmethyl group (CeHnCHr) is a cycloaliphatic radical which
comprises a cyclohexyl ring (the array of atoms which is cyclic but which is not
aromatic) and a methylene group (the noncyclic component). The cycloaliphatic
radical may include heteroatoms such as nitrogen, sulfur, selenium, silicon and
oxygen, or may be composed exclusively of carbon and hydrogen. Cycloaliphatic
radicals may be "substituted" or "unsubstituted". A substituted cycloaliphatic radical
is defined as a cycloaliphatic radical which comprises at least one substituent. A
substituted cycloaliphatic radical may comprise as many substituents as there are
positions available on the cycloaliphatic radical for substitution. Substituents which
may be present on a cycloaliphatic radical include but are not limited to halogen
atoms such as fluorine, chlorine, bromine, and iodine. Substituted cycloaliphatic
radicals include trifluoromethylcyclohexyl, hexafluoroisopropylidenebis(4-
cyclohexyloxy) (i.e. -OC6HioC(CFj)2 CeHioO-), chloromethylcyclohexyl; 3-
trifluorovinyl-2-cyclopropyl; 3-trichloromethylcyclohexyl (i.e. S-CClsCiHio-),
bromopropylcyclohexyl (i.e. BrCH2CH2CH2 CaHio-). and the like. For convenience,
the term "unsubstituted cycloaliphatic radical" is defined herein to encompass a wide
range of functional groups. Examples of unsubstituted cycloaliphatic radicals include
4-allyloxycyclohexyl, aminocyclohexyl (i.e. H2N CeHio-). aminocarbonylcyclopentyl
(i.e. NHjCOCsHs-). 4-acetyloxycyclohexyl, dicyanoisopropylidenebis(4-
cyclohexyloxy) (i.e. -OC6H10C(CN)2C6H2O-), 3-methylcyclohexyl, methylenebis(4-
cyclohexyloxy) (i.e. -OCH1oCH2HioO-), ethylcyclobutyl, cyclopropylethenyl, 3-
formyl-2-terahydrofuranyl, 2-hexyl-5-tetrahydrofuranyl; hexamethylene-1,6-bis(4-
cyclohexyloxy) (i.e. -O C6H)0 (CH2)6 C6HioO-); 4-hydroxymethylcyclohexyl (i.e. 4-
HOCH2C6H|0-), 4-mercaptomethylcyclohexyl (i.e. 4-HSCH2 CoHio-), 4-
methylthiocyclohexyl (i.e. 4-CH3S C^io-), 4-methoxycyclohexyl, 2-
methoxycarbonylcyclohexyloxy (2-CH3OCO C6H20-), nitromethylcyclohexyl (i.e.
N02CH2C6Hio-), trimethylsilylcyclohexyl, t-butyldimethylsilylcyclopentyl, 4-
trimethoxysilylethylcyclohexyl (e.g. (CH3O)3SiCH2CH2C6H10-), vinylcyclohexenyl,
vinylidenebis(cyclohexyl), and the like. The term "a C3- C10 cycloaliphatic radical"
includes substituted cycloaliphatic radicals and unsubstiruted cycloaliphatic radicals
containing at least three but no more than 10 carbon atoms. The cycloaliphatic radical
2-tetrahydroruranyl (C4H70-) represents a C4 cycloaliphatic radical. The
cyclohexylmethyl radical (C6H||CH2-) represents a C7 cycloaliphatic radical.
It has been discovered that the haze exhibited by articles prepared using polymer
compositions produced in halo-displacement polymerizations, surprisingly, is due to
exceeding a threshold level of residual alkali metal halide in the polymer composition
used to fabricate the article. The alkali metal halide is a by-product of the
polymerization reaction itself. Reducing the alkali metal halide levels in the polymer
composition to 25 ppm or less prior to forming an article from the polymer
composition, results in an article with reduced haze levels and of acceptable optical
quality. The method of controlling haze provided by the present invention permits the
stable and reliable production of articles having haze levels of less than or equal to
about 10%. In one embodiment the haze levels exhibited by the articles are less than
about 5%. In a preferred embodiment the haze levels are less than about 2%.
As noted, the present invention provides a method for controlling haze in an article
comprising a polymer composition generally. Thus, it has been discovered that the
level of haze exhibited by an article comprising a polymer composition may be
controlled by limiting the amount of alkali metal halide present in the polymer
composition from which the article is fabricated to less than about 25 parts per
million. The expression "a polymer composition" refers to a composition of matter
comprising at least one polymeric species. Thus, " a polymer composition" includes
compositions of matter comprising a single polymeric species (e.g. a polyetherimide
comprising structural units derived from BPADA, meta-phenylene diamine, and
aniline having a molecular weight of 45,000 grams per mole), and compositions of
matter comprising a plurality of polymeric species (e.g. a blend of the polyetherimide
comprising structural units derived from BPADA, meta-phenylene diamine, and
aniline having a molecular weight of 45,000 grams per mole with another polymeric
material).
A wide variety of polymeric species are encompassed by the expression "a polymer
composition". These polymeric species include polyethersulfones, polyimides,
polyetherketones, polyetheretherketones, and polyetherimides. Thus in one
embodiment, the present invention provides a method for controlling haze in articles
comprising at least one polymeric species selected from the group consisting of
polyethersulfones, polyimides, polyetherketones, polyetheretherketones, and
polyetherimides. In another embodiment the present invention provides a method for
controlling haze in an article comprising at least one polyethersulfone.
Although, the utility of the method of the present invention to control haze is
illustrated experimentally herein in terms of controlling haze in articles comprising
polyetherimides, the present invention encompasses the control of haze generally in
articles fabricated from a wide variety of polymer compositions. Thus, while the
description and experimental details which follow focus on control of haze in articles
fabricated from polyetherimide compositions, the invention is in no way limited
thereto. In its broadest sense, the present invention includes the control of haze in
articles fabricated from any and all polymer compositions susceptible to
contamination by at least one alkali metal halide wherein the concentration of alkali
metal halide exceeds 25 parts per million.
In various embodiments, the present invention provides a method for controlling haze
in an article comprising a polyetherimide composition. In one embodiment the
method provides an article fabricated using a polyetherimide composition, having 25
parts per million or less of alkali metal halide. The polyetherimide is typically
obtained from a precursor polyetherimide comprising 50 parts per million or more of
alkali metal halide,
The polyetherimide used according to the method of the present invention typically
comprise repeat units having structure of formula 1,
wherein R1 and R2 are independently at each occurrence a halogen atom, a nitro
group, a cyano group, a C1-C12 aliphatic radical, a C3-C12 cycloaliphatic radical, or a
C3-C22 aromatic radical; b and c are independently integers from 0 to 3; Q is a C2-C22
aliphatic radical, a C3-C22 cycloaliphatic radical, or a C2-C22 aromatic radical; X is a
bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, a selenium
atom, a hexafluoroisopropylidene group, a carbonyl group or a linking group having
structure 11
(Figure Removed)
wherein each G1 is independently an C3-C20 aromatic radical; E is selected from the
group consisting of a C3-C20 cycloaliphatic radical, a C3-C20 aromatic radical, a C3-C20
aliphatic radical, a sulfur-containing linkage, a phosphorus-containing linkage, an
ether linkage, a carbonyl group, a tertiary nitrogen atom, and a silicon-containing
linkage; R3 is independently at each occurrence a halogen atom, a C3-C20 aliphatic
radical, C3-C20cycloaliphatic radical, or a C3-C20 aromatic radical; Y1 is
independently at each occurrence a halogen atom, a nitro group, a cyano group, aC3-C20
C2Q aliphatic radical, C3-C20 cycloaliphatic radical, or a C3-C20 aromatic radical; each
m is independently a number from zero through the number of positions on each
respective G1 available for substitution; p is a whole number from zero through the
number of positions on E available for substitution; t is a number greater than or equal
to one; s is either zero or one; and u is a whole number including zero, wherein at
least one of t, s, and u is not equal to zero.
In one embodiment the structural unit Q is derived from a diamine selected from the
group consisting ofC3-C20 aliphatic diamines, C3-C20 cycloaliphatic diamines, and
C3-C22 aromatic diamines.
In other embodiments X in formula 1 comprises a divalent organic radical selected
from aromatic hydrocarbon radicals having 6 to about 22 carbon atoms and
substituted derivatives thereof. In various embodiments said aromatic hydrocarbon
radicals may be monocyclic, polycyclic or fused.
In still other embodiments X in formula I comprises divalent aromatic radicals of the
general formula (111)
(Figure Removed)
wherein the unassigned positional isomer about the aromatic ring is either meta or
para to Z, and Z is a covalent bond or a member selected from the group consisting of
an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, a selenium atom, a
hexafluoroisopropylidene group, a carbonyl group and an alkylene or alkylidene
group of the formula CyHay, wherein y is an integer from 1 to 5 inclusive. In some
particular embodiments y has the value of one or two. Illustrative linking groups
include, but are not limited to, methylene, ethylene, ethylidene, vinylidene, halogensubstituted
vinylidene, and isopropylidene. In other particular embodiments the
unassigned positional isomer about the aromatic ring in formula III is para to Z.
In various embodiments the two amino groups in the diamines are separated by at
least two and sometimes by at least three ring carbon atoms. When the amino group
or groups are located in different aromatic rings of a polycyclic aromatic moiety, they
are often separated from the direct linkage or from the linking moiety between any
two aromatic rings by at least two and sometimes by at least three ring carbon atoms.
Illustrative non-limiting examples of aromatic hydrocarbon radicals include phenyl,
biphenyl, naphthyl, bis(phenyl)methane, bis(phenyl)-2,2-propane, and their
substituted derivatives. In particular embodiments substituents include one or more
halogen groups, such as fluoro, chloro, or bromo, or mixtures thereof; or one or more
straight-chain-, branched-, or cycloalkyl groups having from 1 to 22 carbon atoms,
such as methyl, ethyl, propyl, isopropyl, tert-butyl, or mixtures thereof. In particular
embodiments substituents for aromatic hydrocarbon radicals, when present, are at
least one of chloro, methyl, ethyl or mixtures thereof. In other particular
embodiments said aromatic hydrocarbon radicals are unsubstituted. In some
particular embodiments diamines from which R1 may be derived include, but are not
limited to, meta-phenylenediamine; para-phenylenediamine; mixtures of meta- and
para-phenylenediamine; isomeric 2-methyl- and 5-methyl-4,6-diethyl-l,3-phenylenediamines
or their mixtures; bis(4-aminophenyl)-2,2-propane;
bis(2-chloro-4-amino-3,5-diethylphenyl)methane, 4,4'-diaminodiphenyl, 3,4'-
diaminodiphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-
diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ketone,
3,4'-diaminodiphenyl ketone, and 2,4-toluenediamine. Mixtures of diamines may also
be employed.
In a preferred embodiment the diamine may comprise structural units derived from
the group consisting of meta-phenylenediamine and para-phenylenediamine. The
structural units derived from meta-phenylenediamine and para-phenylenediamine may
be present in an amount corresponding to from about ] to about 99 mole percent and
from about 99 to about 1 mole percent respectively. In one embodiment the structural
units derived from meta-phenylenediamine is present in an amount corresponding to
from about 40 to about 99 mole percent. In a preferred embodiment the structural
units derived from meta-phenylenediamine is present in an amount corresponding to
from about 50 to about 95 mole percent. In one embodiment structural units derived
from para-phenylenediamine is present in an amount corresponding to from about 1 to
about 30 mole percent, In a preferred embodiment structural units derived from paraphenylenediamine
is present in an amount corresponding to from about 2 to about 15
mole percent. With respect to using a mixture of structural units derived from meta
and para-phenylenediamine the term "mole percent" is defined as (number of moles
of structural units derived from meta and para-phenylenediamine /total number of
moles of diamine-derived structures present in the polymer)* 100,
In one embodiment of the present invention, the polymer composition comprising less
than 25 parts per million alkali metal halide is prepared by reacting at least one alkali
metal salt of at least one bisphenol, for example the disodium salt of bisphenol A,
with at least one bis-halo compound selected from the group consisting of l,3-bis[N-
(4-chlorophthalimido)]benzene; 1,4-bis[N-(4-chlorophthalimido)]benzene; 1,3-bis[N-
(3-chlorophthalimido)]benzene; 1,4-bis[N-(3-chlorophthalimido)]benzene; l-[N-(4-
chlorophthalimido)]-3-[N-(3-chlorophthalimido)benzene; l-[N-(4-
chlorophthalimido)]-4-[N-(3-chlorophthalimido)benzene; bis(4-chlorophenyl)
sulfone; bis(4-fluorophenyl) sulfone; bis(4-chlorophenyl) sulfone; l,4-bis(4-
chlorobenzoyl)benzene; 1,4-bis(4-fluorobenzoyl)benzene; 1,3-bis(4-
chlorobenzoyl)benzene; l,3-bis(4-fluorobenzoyl)benzene; and mixtures thereof.
The phrase "at least one" means one member of a group has to be necessarily present,
however, more than one member of the group may also be present. For example, "at
least one bisimide" means that one of the bisimides from the group has to be present,
however, there could be more. For example, the polyetherimide precursor may
comprise a reaction product of a bisphenol A moiety with 1,3-bis[N-(4-
chlorophthalimido)]benzene, however, any one or more of the other bisimides from
the group may also be present.
A precursor polyetherimide comprising more than 50 parts per million alkali metal
halide is typically obtained when the polyetherimide is synthesized using the halodisplacement
process. This overall process involves reacting a diamine with halophthalic
anhydride to form a bis-halophthalimide, followed by halo-displacement
polymerization with an alkali metal salt of a bisphenol, for example the disodium salt
of bisphenol A and a phase transfer catalyst. A typical product mixture obtained
using the halo-displacement process comprises (i) a precursor made by a halodisplacement
polymerization process, (ii) a catalyst, (iii) an alkali metal halide, and
(iv) a substantially water-immiscible organic solvent. In one particular embodiment
the alkali metal halide comprise an alkali metal chloride, alkali metal fluoride and
alkali metal iodide. In a preferred embodiment the alkali metal halide is sodium
chloride.
The catalyst present is typically at least one phase transfer catalyst, which in various
embodiments is substantially stable at the temperatures employed i.e., in the range of
about 125-250°C. Various types of phase transfer catalysts may be employed for this
purpose. They include quaternary phosphonium salts of the type disclosed in U.S. Pat.
No. 4,273,712, N-alkyl-4-dialkylaminopyridinium salts of the type disclosed in U.S.
Pat. Nos. 4,460,778 and 4,595,760, and guanidinium salts of the type disclosed in the
aforementioned U.S. Pat. No. 5,229,482, In some embodiments the phase transfer
catalysts, by reason of their exceptional stability at high temperatures and their
effectiveness in producing high molecular weight aromatic polyether polymers in high
yield, comprise the hexaalkylguanidinium and alpha, omegabis(
pentaalkylguanidinium)alkane salts, particularly the chloride salts. In a particular
embodiment the catalyst is l,6-bis(penta-n-butylguanidinium)hexane dibromide. In
another particular embodiment the catalyst is hexaethylguanidinium chloride.
Typically, at least one substantially water-immiscible organic solvent is also used in
the halo-displacement polymerization process and is therefore typically present in the
precursor polyetherimide-containing product mixture. The at least one solvent may
completely or at least partially dissolve reaction ingredients.
In one embodiment of the present invention suitable solvents are those which have a
boiling point at atmospheric pressure of greater than 110°C, preferably greater than
about125°C
Substantially water-immiscible means that the organic solvent dissolves to the extent
of, in one embodiment, less than about ] 0 weight percent (wt. %), and in another
embodiment less than about 5 wt. % in water. Alternatively, substantially waterimmiscible
means that water dissolves in the solvent to the extent of, in one
embodiment, less than about 10 wt. %, and in another embodiment less than about 5
wt. %. In some embodiments solvents are aromatic solvents, particularly halogenated
aromatic solvents such as chloronaphthalene. In particular embodiments solvents
include diphenylsulfone, anisole, veratrole, chlorinated benzenes, such as
chlorobenzene, dichlorotoluene, 1,2,4-trichlorobenzene, and especially odichlorobenzene.
Mixtures of such solvents may also be employed. The water
miscibility of a preferred solvent, o-DCB is less than 1 percent.
As noted, although simple and flexible, relative to the nitro-displacement process,
product polymers prepared via the halo-displacement process typically contain
relatively high levels of alkali metal halide (i.e. greater than about SO ppm alkali metal
halide). Moreover, the articles produced using polyetherimide produced by the halodisplacement
process were found to have significantly higher haze levels than articles
produced using polymer resin prepared using the nitro-displacement process. The
haze exhibited by a material generally results from the scattering of light transmitted
through the material, by small paniculate matter present in the material. As discussed
above for certain applications of polyetherimide compositions, such as dishware, film
and silicon wafer carriers, low haze is a critical quality factor. Test samples
comprising a precursor poiyetherimide containing greater that about 50 ppm sodium
chloride exhibited higher haze values of about 10 to about 50%. as compared to
identical test samples comprising a polyetherimide resin containing 25 ppm or less of
sodium chloride which gave haze values of less than about 10%.
In one aspect, the present invention provides for the control of haze in an article
comprising a polyetherimide composition by providing a polyetherimide composition
comprising 25 ppm or less of alkali metal halide. Thus, a reaction product mixture
comprising (i) a precursor polyetherimide made by a halo-displacement
polymerization process, (ii) a catalyst, (iii) an alkali metal halide, and (iv) a
substantially water-immiscible organic solvent is purified to obtain the desired value
of alkali metal halide concentration (i.e. 25 ppm or less). The purification of the
mixture to obtain a polyetherimide having 25 ppm or less of alkali metal halide can be
carried out in different ways. The precursor polyetherimide may be purified by
methods disclosed in copending application US 2002015675, filed on December 21,
2001 which is incorporated by reference herein in its entirety. Exemplary methods
are included below.
In one embodiment, the polyetherimide is provided by purifying a product mixture
comprising a precursor polyetherimide via a series of steps, said steps comprising:
(a) quenching the mixture comprising a precursor polyetherimide-containing
organic phase with acid to provide a quenched mixture comprising an organic phase;
(b) contacting the quenched mixture with water and separating a water-containing
phase from the organic phase, using at least one of a liquid/liquid centrifuge, a
solid/liquid centrifuge, a counter-current contact apparatus, a liquid-liquid extractor, a
liquid-liquid continuous extractor, an extraction column, a static mixer, a coalescer, a
homogenizer, or a mixing/settling vessel; and
(c) and isolating the polyetherimide;
to provide a polyetherimide containing 25 ppm or less of alkali metal halide. In one
embodiment, the acid employed in step (a) comprises phosphoric acid which is
typically an aqueous solution of phosphoric acid having sufficient acidity to
completely neutralize any basic species present in the precursor polyetherimidecontaining
organic phase. In some embodiments the use of phorphorous acid in a
quenching step is found to improve the overall stability and appearance of the
product polyetherimide.
In another embodiment, the polyetherimide is provided by purifying a product
mixture comprising a precursor polyetherimide via a series of steps, said steps
comprising:
(a) performing at least one solid separation step on the mixture;
(b) quenching the mixture with acid to provide a quenched mixture; and
(c) extracting the quenched mixture at least once with water.
In another embodiment the polyetherimide is provided by purifying a product mixture
comprising a precursor polyetherimide via a series of steps, said steps comprising;
(a) quenching the mixture with acid to provide a quenched mixture
(b) subjecting the quenched mixture to at least one solid separation step; and
(c) at least one ion exchange step.
In yet another embodiment the polyetherimide is provided by purifying a product
mixture comprising a precursor polyetherimide via a series of steps, said steps
comprising
(a) quenching the mixture with acid to provide a quenched mixture
(b) adding to the quenched mixture an amount of water in a range between about
0.005 wt. % and about 10 wt. % based on the weight of polyetherimide present to
provide a multiphase mixture comprising an alkali metal halide;
(c) agitating the multiphase mixture formed in step (a), whereby a portion of the
alkali metal halide is converted to a form that can be separated by a solid separation;
and
(d) performing at least one solid separation step.
The polyetherimide used according to the method of the present invention may further
comprise various additives which may be used alone or in combination. These
additives include such materials as thermal stabilizers, antioxidants, UV stabilizers,
plasticizers, extenders, antistatic agents, catalyst quenchers, mold releasing agents,
fire retardants, blowing agents, and processing aids. The different additives that can
be incorporated in the polyetherimide resins used according to the method of the
present invention are typically commonly used in resin compounding and known to
those skilled in the art.
"Non-limiting examples of antioxidants include 1RGANOX 1010 (tetrakis [3-(3'5'-ditert-
butyl-4'-hydroxyphenyl)propionyloxymethyl]methane; tris(2, 4-di-tertbutylphenyl)
phosphite; 3,9-di(2, 4-di-tert-butylphenoxy)-2,4,8,] O-tetraoxa-3,9-
diphosphaspiro[5.5]undecane; 3,9-di(2,4-dicumylphenoxy)-2,4,8,10-telraoxa-3,9-
diphosphaspiro[5.5]undecane; tris(p-nonylphenyl)phosphite; 2,2',2"- nitri!o[triethyltris[
3,3',5,5'-tetra-tertbutyl-l,r-biphenyl-2'- diyl]phosphite]; 3, 9-distearyloxy-
2,4,8,10-tetraoxa-3,9-diphosphaspiro[5. 5]undecane; dilauryl phosphite; 3,9-di[2,6-ditert-
butyl-4-methylphenoxy]-2, 4, 8, 10-tetraoxa-3,9-diphosphaspiro[5.5]undecane;
tetrakis( 2, 4-di-tert-butylphenyl)-4, 4'-bis(diphenylene)phosphonite; distearyl
pentaerythritol diphosphite; diisodecyl pentaerythritol diphosphite; 2, 4, 6-tri-»ertbuty!
phenyl-2-butyl-2-ethyM,3-propanedio! phosphite; tristearyl sorbitol
Iriphosphite; tetrakis( 2, 4-di-tert-butylphenyl)-4, 4'-bis(diphenylene)phosphonite;
distearyl pentaerythritol diphosphite; diisodecyl pentaerythritol diphosphite; 2, 4, 6-
tri-tert-butyipheny]-2-butyl-2-ethyl-l,3-propanediol phosphite; tristearyl sorbitol
triphosphite; tetrakis(2, 4-di-tert-butylphenyl)-4,4'- biphenylene diphosphonite; (2, 4,
6-tri-tert-butylphenyl)-2-butyl-2-ethyl-l, 3-propanediolphosphite;
triisodecylphosphite; and mixtures of phosphites containing at least one of the
foregoing. Tris(2, 4-di-ten-butylphenyl) phosphite; 2,4,6-tri-tert-butylphenyl-2-butyl-
2-ethyl-l,3-propanediol phosphite; bis(2, 4-di-tert-butylphenyl)pentaerythritol
diphosphite are especially preferred, as well as mixtures of phosphites containing at
least one of the foregoing phosphites, and the like.
Non-limiting examples of processing aids include, Doverlube® FL-599 (available
from Dover Chemical Corporation), Polyoxyter® (available from Polychem Alloy
Inc.), Glycolube P (available from Lonza Chemical Company), pentaerythritol
tetrastearate, Metablen A-3000 (available from Mitsubishi Rayon), neopentyl glycol
dibenzoate, and the like.
Non-limiting examples of UV stabilizers include 2-(2'-Hydroxyphenyl)-
benzotriazoles, e.g., the 5'-methyl-; 3',5'-di- tert.-butyl-; 5'-tert.-buty]-; 5'-(l,1,3,3-
tetramelhylbutyl)-; 5-chloro- 3'.5'-di-tert.-butyl-; 5-chloro-3'-tert.-buty]-5'-methyl-; 3'-
sec.-butyl- S'-tert.-butyl-; 3'-alpha -methylbenzyl -5'-methyl; 3'- alpha- methylbenzyl-
5'-methyl-5-chloro-; 4'-hydroxy-; 4'-methoxy-; 4'-octoxy-; 3',5'-di-tert.-amyl-; 3'-
methyl-5'-carbomethoxyethyl-; 5-chloro-3',5'- di-tert.-amyl-derivatives; and Tinuvjn®
234 (available from Ciba Specialty Chemicals). Also suitable are the 2, 4-bis-(2'-
hydroxyphenyl)-6-alkyl-s-triazines, e.g., the 6-ethyl-; 6- heptadecyl- or 6-undecylderivatives.
2-Hydroxybenzophenones e.g., the 4-hydroxy-; 4-methoxy-; 4-octoxy-;
4- decyloxy-; 4-dodecyloxy-; 4-benzyloxy-; 4,2l,4'-trihydroxy-; 2,2',4,4'-
tetrahydroxy- or 2'-hydroxy-4,4'-dimethoxy-derivative. 1,3-bis-(2'-Hydroxybenzoyl)-
benzenes, e.g., 1,3-bis-(2'-hydroxy-4'- hexyloxy-benzoyl)-benzene; l,3-bis-(2'-
hydroxy-4'-octy!oxy-benzoyl)- benzene or 1,3-bis-(2'-hydroxy-4'-
dodecyloxybenzoyl)-benzene may also be employed. Esters of optionally substituted
benzole acids, e.g., phenylsalicylate; octylphenylsalicylate; dibenzoylresorcin; bis-(4-
tert.-butylbenzoyl)-resorcin; benzoylresorcin; 3,5-di-tert.-butyl-4-hydroxybenzoic
acid-2,4- di-tert.-butylphenyl ester or -octadecyl ester or -2-methyl-4,6-di-tert.- butyl
ester may likewise be employed. Acrylates, e.g., alpha -cyano- beta, beta •
diphenylacrylic acid-ethyl ester or isooctyl ester, alpha -carbomethoxy-cinnamic acid
methyl ester, alpha-cyano-beta-methyl-p-methoxy-cinnamic acid methyl ester or -
butyl ester or N(beta-carbomethoxyvinyl)-2-methyl-indoline may likewise be
employed. Oxalic acid diamides, e.g., 4,4'-di-octyloxy-oxanilide; 2,2'-di- octyloxy-
5,5'-di-tert.-butyl-oxanilide; 2,2'-di-dodecyloxy-5,5-di-tert.- butyl-oxanilide; 2-
ethoxy-2'-ethyl-oxanilide; N,N'-bis-(3-dimethyl- aminopropyl)-oxalamide; 2-ethoxy-
5-tert.-butyl-2'-ethyloxanilide and the mixture thereof with 2-ethoxy-2'-ethyl-5,4'-ditert.-
butyl-oxanilide; or mixtures of ortho- and para-methoxy- as well as of o- and pethoxy-
disubstituted oxanilides are also suitable as UV stabilizers. Preferably the
ultraviolet light absorber used in the instant compositions is 2-(2-hydroxy-5-
methylphenyl)-2H-benzotriazole; 2-(2- hydroxy-3,5-di-tert-amylphenyl)-2Hbenzotriazole;
2-[2-hydroxy-3,5-di- (alpha,alpha-dimethylbenzyl)phenyl]-2Hbenzotriazole;
2-(2-hydroxy-5-tert- octylphenyl)-2H-benzotriazole; 2-hydroxy-4-
octyloxybenzophenone; nickel bis(O-ethyl 3,5-di-tert-butyl-4-
hydroxybenzylphosphonate); 2,4- dihydroxybenzophenone; 2-(2-hydroxy-3-tertbutyl-
5-methylphenyl)-2H- benzotriazole; nickel butylamine complex with 2,2'-
thiobis(4-tert- butylphenol); 2-ethoxy-2'-ethyloxanilide; 2-ethoxy-2'-ethyl-5,5l-ditertbutyloxanilideora
mixture thereof.
Non-limiting examples of fire retardants include potassium nonaftuorobutylsulfonate,
potassium diphenylsulfone sulfonate, and phosphite esters of polyhydric phenols,
such as resorcinol and bisphenol A.
Non-limiting examples of mold release compositions include esters of long-chain
aliphatic acids and alcohols such as pentaerythritol, guerbet alcohols, long-chain
ketones, siloxanes, alpha-olefin polymers, long-chain alkanes and hydrocarbons
having 15 to 600 carbon atoms.
The articles of the present invention can be made by molding the polyetherimide into
useful shapes by a variety of means such as injection molding, extrusion, rotational
molding, blow molding and thermoforming to form articles such as, for example,
electrical/electronic insulators, dishware, food service trays, electronic chip carriers,
circuit boards, medical devices and film and sheet products.
Techniques for the extrusion of sheets, including solid sheets, multi-wall sheets, and
multi-wall sheets comprising hollow bodies, are known in the art and described in, for
example, U.S. Pat. Nos. 3,476,627 to Squires, 3,565,985 to Schrenk et al., 3,668,288
to Takahashi, 3,918,865 to Missel, 3,933,964 to Brooks, 4,477, 521 to Lehmann et al.,
and 4,707,393 to Vetter. There is no particular limitation on the composition of
additional layers used to form coextruded sheets. There is no particular limitation on
the structure or geometry of the multi-wall sheets. The additional layers may
comprise, for example, fluorescing agents to facilitate manufacturing and/or
ultraviolet light absorbers to improve weatherability. The thickness of the multi-wall
sheet is preferably about 4 mm to about 40 mm, while the thickness of the solid sheet
is preferably about 1 mm to about 12 mm.
While the invention has been described with reference to exemplary embodiments, it
will be understood by those skilled in the art that various changes may be made and
equivalents may be substituted for elements thereof without departing from the scope
and spirit of the invention. In addition, many modifications may be made to adapt a
particular situation or material to the teachings of the invention without departing
from the essential scope thereof. Therefore, it is intended that the invention not be
limited to the particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include all embodiments falling
within the scope of the appended claims. The invention is further illustrated by the
following non-limiting examples.
EXPERIMENTAL SECTION
The following examples are set forth to provide those of ordinary skill in the art with
a detailed description of how the methods claimed herein are evaluated, and are not
intended to limit the scope of what the inventors regard as their invention. Unless
indicated otherwise, parts are by weight, temperature is in °C,
The haze measurements were made on rectangular injection molded plaques having
dimensions of 6" L x 2.5" W x 0.125" T following ASTM Test Method D1003. A
BKY Gardner Haze-guard Plus haze meter was used for the measurements.
The polyetherimide used to find the correlation between alkali metal chloride
concentration and haze levels was prepared by following the method disclosed in
copending application US 2002015675, filed on December 21, 2001 which is
incorporated by reference herein in its entirety.
In Comparative Examples 1-10, test samples of polyetherimide comprising unknown
paniculate matter were scanned using a scanning electron microscopy coupled with
elemental characterization using Energy Dispersive Spectroscopy analysis. It was
found that the composition of the most common particles in the appropriate size range
for scattering light was sodium chloride. Typical sodium chloride particle sizes were
found to be in the range of about 1 to about 2 micrometers (urn). Sodium analyses of
the samples shown in Table 1 were performed and the correlation between sodium
concentration, expressed as parts per million of sodium chloride, and haze was
evaluated. To convert the sodium concentration values obtained in the analyses to
parts per million sodium chloride the initially obtained value was multiplied by a
factor of 2.5.
(Table Removed)
The results of the correlation between sodium chloride concentration and haze in the
Comparative Examples and the Examples are shown in Figure 1 along with model
predictions for the haze generated by sodium chloride particles with average sizes of and 2 urn. It is apparent that there is a good correlation between haze and sodium
chloride concentration, and that the correlation is consistent with model predictions
based on particle size. The results in Figure 1 demonstrate that sodium chloride levels
of 25 ppm or less are necessary to obtain acceptable haze levels, and that sodium
chloride levels of 5 ppm or less would be preferable to assure low haze.
Examples 1-11: In these examples test parts made from polyetherimide with sodium
chloride concentrations of less than 15 ppm were evaluated for their haze levels. The
data given in Table 2 show that reduced sodium chloride levels (15 ppm or less)
correlate with haze levels below 5%, and that this result has been consistently
obtained.
(Table Removed)
Examples 1-11 indicate that if the sodium chloride concentration is maintained at 15
ppm or less a haze level of 5% or less is observed.
The invention has been described in detail with particular reference to preferred
embodiments thereof, but it will be understood by those skilled in the art that
variations and modifications can be effected within the spirit and scope of the
invention.

WHAT IS CLAIMED IS:
1. A method for controlling haze in an article comprising a polymer composition,
said method comprising:
(a) providing a polymer composition comprising less than 25 parts per million
alkali metal halide; and
(b) fabricating an article from said polymer composition.
2. The method according to claim 1 wherein said polymer composition
compnses at least one member selected from the group consisting of polyetherimides,
polyethersulfones, and polyetherketones.
3, The method according to claim 1 wherein said polymer composition
comprises a polyetherimide.
4, The method according to claim 3 wherein said polyetherimide comprises
repeat units having structure I
wherein R1 and R2 are independently at each occurrence a halogen atom, a nitro
group, a cyano group, a C1-C12 aliphatic radical, C3-C12 cycloaliphatic radical, or a Cj-
Ci2 aromatic radical; b and c are independently integers from 0 to 3; Q is a C3-C12
aliphatic radical, a C3-C22 cycloaliphatic radical, or a C3-C22 aromatic radical; X is a
bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, a selenium
atom, a hexafluoroisopropylidene group, a carbonyl group or a linking group having
structure II
(Figure Removed)
wherein each G1 is independently an C3-C20 aromatic radical; E is selected from the
group consisting of a C3-C22 cycloaliphatic radical, aC3-C20 aromatic radical, a C3-C20
aliphatic radical, a sulfur-containing linkage, a phosphorus-containing linkage, an
ether linkage, a carbonyl group, a tertiary nitrogen atom, and a silicon-containing
linkage; R3 is independently at each occurrence a halogen atom, a Q-C20 aliphatic
radical, C3-C20 cycloaliphatic radical, or a C3-C20 aromatic radical; Y1 is
independently at each occurrence a halogen atom, a nitro group, a cyano group, a C20
aliphatic radical,C3-C20cycloaliphatic radical, or a C3-C20 aromatic radical; each
m is independently a number from zero through the number of positions on each
respective G1 available for substitution; p is a whole number from zero through the
number of positibns on E available for substitution; t is a number greater than or equal
to one; s is either zero or one; and u is a whole number including zero, wherein at
least one of t, s, and u is not equal to zero.
5. The method according to claim 4 wherein said structural unit Q is derived
from a diamine selected from the group consisting of C3-C20 aliphatic diamines, C3-
C22 cycloaliphatic diamines, and C3-C20aromatic diamines.
6. The method according to claim 4 wherein said structure 1 comprises structural
units derived from meta-phenylenediamine, and para-phenylenediamine.
7. The method according to claim 6 wherein said meta-ph.enylenediamine, and
said para-phenylenediamine are present in an amount corresponding to from about 1-
99 mole percent and from 99-1 rnole percent respectively.
8. The method according to claim 1 wherein said polymer comprising 25 parts
per million or less of alkali metal halide is provided by purifying a precursor polymer,
said precursor polymer comprising more than about 50 parts per million of alkali
metal halide.
9. The method according to claim 8 wherein said precursor polymer comprising
more than about 50 parts per million alkali metal halide is prepared by a process
which generates alkali metal halide as a by-product.
10. The method according to claim 8 wherein said purifying a precursor polymer
comprises subjecting a product mixture comprising (i) a polymer reaction product
made by a halo-displacement polymerization process, (ii) a catalyst, (iii) an alkali
metal halide, and (iv) a substantially water-immiscible organic solvent, to a series of
processing steps, said steps comprising;
(a) quenching the mixture with acid to provide a quenched mixture
comprising an organic phase;
(b) perform a solid separation step;
(c) contacting the quenched mixture with water using at least one of a
counter-current contact apparatus, an extraction column, a static mixer, a
homogenizer, or a mixing vessel;
(d) separating a water-containing phase from the organic phase, using
at least one of a liquid/liquid centrifuge, a counter-current contact apparatus, a liquidliquid
extractor, a liquid-liquid continuous extractor, an extraction column, a
coalescer, or a settling vessel; and
(e) and isolating the polymer.
11. The method according to claim 10 wherein the polymer comprises the reaction
product of a bisphenol A moiety with at least one member selected from the group
consisting of l,3-bis[N-(4-chlorophthalimido)]benzene, 1,4-bis[N-(4-
chlorophthalimido)]- benzene, 1,3-bis[N-(3-chlorophthalimido)]benzene, 1,4-bis[N-
(3-chlorophthalimido)]benzene, l-[N-(4-chlorophthalimido)]-3-[N-(3-
chlorophthalimido)benzene, 1 -[N-(4-chlorophthalimido)]-4-[N-(3-
chlorophthalimido)benzene, bis(4-chlorophenyl) sulfone, bis(4-fluorophenyl) sulfone;
1,4-bis(4-chlorobenzoyl)benzene and 1,3-bis(4-chlorobenzoyl)benzene.
12. The method according to claim 1 wherein said alkali metal halide is a alkali
metal chloride, alkali metal fluoride or an alkali metal iodide.
13. The method according to claim 12 wherein said alkali metal halide is sodium
chloride.
14. The method according to claim 10 wherein the organic solvent is odichlorobenzene.
15. The method according to claim 1, wherein the article exhibits a haze level less
than or equal to 10%.
16 The method according to claim 15, wherein the article exhibits a haze level
less than or equal to 5%.
17. A method for controlling haze in an article comprising a polymer composition,
said method comprising:
(a) providing a polymer composition comprising less than 25 parts per million
alkali metal chloride; and
(b) fabricating an article from said polymer composition.
18. A method for controlling haze in an article comprising a polyetherimide
composition, said method comprising:
(a) providing a polyetherimide composition comprising less than 25 parts per
million alkali metal chloride; and
(b) fabricating an article from said polyetherimide composition.
19. The method according to claim 18 wherein said polyetherimide comprises
repeat units having structure I
(Figure Removed)
wherein R1 and R2 are independently at each occurrence a halogen atom, a nitro
group, a cyano group, a C1-C12 aliphatic radical, C3-C12 cycJoaliphatic radical, or a Cj-
C)2 aromatic radical; b and c are independently integers from 0 to 3; Q is a C3-C22
aliphatic radical, a C3-C22cycloaliphatic radical, or a C3-C22 aromatic radical; X is a
bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, a selenium
atom, a hexafluoroisopropylidene group, a carbonyl group or a linking group having
structure II
(Figure Removed)
wherein each G1 is independently an C3-C22 aromatic radical; E is selected from the
group consisting of a C3-C20 cycloaliphatic radical, a C3-C20 aromatic radical, a C3-C22
aliphatic radical, a sulfur-containing linkage, a phosphorus-containing linkage, an
ether linkage, a carbonyl group, a tertiary nitrogen atom, and a silicon-containing
linkage; R3 is independently at each occurrence a halogen atom, a C3-C20 aliphatic
radical, C3-C20cycloaliphatic radical, or a C3-C20 aromatic radical; Y1 is
independently at each occurrence a halogen atom, a nitro group, a cyano group, a Q-
C20 aliphatic radical, C3-C20 cycloaliphatic radical, or a C3-020 aromatic radical; each
m is independently a number from zero through the number of positions on each
respective G1 available for substitution; p is a whole number from zero through the
number of positions on E available for substitution; t is a number greater than or equal
to one; s is either zero or one; and u is a whole number including zero, wherein at one
of t, s and u is not equal to zero.
20, The method of Claim 18, wherein the article exhibits a haze level less
than or equal to 10%.
21. The method of Claim 20, wherein the article exhibits a haze level less than or
equal to 5%.