The present invention is directed to an improved moldable thermoplastic
composition having in admixture a particular polymer or blends of particular polymers
and a particulate mineral additive. The particulate mineral additive of this invention
has needle like particles of a relatively small diameter and having a high aspect
ratio of length to diameter. A molded article employing the composition of this
invention can have a lower coefficient of thermal expansion (CTE) and/or a high
distinctness of image (DOI), which results in a molded article that can have a Class
A surface, or an improved surface, as well as other improved properties, particularly
impact when compared to other mineral additives.
A class A surface has been defined in many different ways with no
universal definition. One accepted definition is a glossy, smooth and polished surface
which should be as smooth as that of a current automobile exterior part made from
sheet metal. Another definition is that the visible surface of the article in the
finished state is free of exposed glass fibers, flash, sharp edges, visible parting
lines, crazing, porosity, hair line cracks, blisters, and obvious repairs. In the
present invention, another way of determining a Class A surface is based on the
distinctiveness of image (DOI), which is a determination or measurement of reflective
The compositions of the present invention are useful in many applications,
but particularly in automotive exterior body panel applications such as fascia and
side cladding parts, and can even find use in such parts as fenders, hoods, panels,
trunk lids, door panels, etc. Due to the bake oven temperatures employed during
painting of the automobile, as low a coefficient of thermal (CTE) expansion is wanted
so as to obtain as close tolerances as possible between molded thermoplastic parts
or between plastic and metal parts but still retain all other valuable properties
of the thermoplastic parts being used. In other words, the parts would have predictable
finished dimensions. In addition, the parts made with the compositions of this invention
can have a Class A surface as measured by distinctness of image (DOI), which is
a measure of reflective light waves.
DESCRIPTION OF RELATIVE ART
U.S. Patent 5,091,461 discloses and claims an amorphous polymer matrix
and an organic filler having improved properties of reduced coefficient of thermal
expansion, high falling dart impact resistance and good resistance to heat under
load. The composition consists of an aromatic polycarbonate, a rubber modified homopolymer
or copolymer, such as acryonitrile-butadiene-styrene (ABS) and an inorganic filler
having a particle size of a diameter of less than 44 microns (µm) and a diameter
to thickness ratio of 4 to 24. The inorganic fillers disclosed, however, are clays
and talcs. The patent also discloses that the filler's large dimension is the diameter
and the thickness is the small dimension showing that the filler is more of a plate
shape particle or a flake shaped particle.
With the ever increasing use of plastics in automotive application,
particularly external parts thereof, there is a need for plastic parts that have
a low coefficient of thermal expansion and stability under the high heat of the
baking ovens. This is to avoid excessive expansion of the plastic parts under heat
which would result in buckling or misfit such as, for example, a fender or a door
of an automobile. Also important is impact resistance, particularly in such parts
as fascia and side cladding, which is a plastic strip running along the lower part
of the outside of the automobile, as well as in other exterior automotive body parts.
It is also important that such molded parts have a Class A surface.
When using such fillers as glass fibers, mica, glass flake, clay,
or talc fillers not having the particular particle size of this invention in thermoplastic
compositions, one or more of the desired properties is affected, such as DOI is
lowered (which is a measure of the surface smoothness), brittleness occurs, poor
resistance to impact, little or no CTE reduction, etc.
Therefore, it is an object of this invention to provide an improved
thermoplastic molding composition having a lower coefficient of thermal expansion.
Another object of this invention is to provide an improved thermoplastic
molding composition which when molded can result in a Class A surface as determined
by distinctness of image.
Yet another object of this invention is to provide an improved thermoplastic
molding composition which when molded has improved surface characteristics.
Still another object of this invention is to provide an improved thermoplastic
molding composition which when molded has improved impact resistance.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, there is provided an improved
thermoplastic molding composition having, in the molded state, a lower coefficient
of thermal expansion (CTE) and a higher distinctness of image (DOI) comprising in
intimate admixture of (1) a thermoplastic polymer which may be either a copolyetherimide
ester, a polyalkylene terephthalate, an aromatic polycarbonate, a rubber modified
homopolymer or copolymer of a vinyl aromatic monomer, a polyphenylene ether, a polyamide,
blends thereof, or blends thereof with other polymers, and (2) a fine needle like
particulate mineral additive wherein the needle like particles have a mean number
average length of about 1.0 µm to about 50 µm and a mean number average diameter
of about 0.1 µm to about 10 µm. The thermoplastic polymer portion of the intimate
admixture of this invention is preferable at least about 30 to about 95 weight percent
and more particularly at least about 50 to about 95 weight percent. The mineral
additive portion of the intimate admixture is preferably about 70 to about 5 weight
and more particularly about 50 to about 5 weight percent the weight percents being
based on the total weight of the thermoplastic molding composition disclosed herein.
The copolyetherimide esters that may be employed in this invention
consist of a multiplicity of recurring long chain ester units and short chain ester
units that can be joined through imido-ester linkages. The hard segments of these
elastomers consist essentially of multiple short chain ester units represented by
wherein R is a divalent radical remaining after removal of carboxyl groups from
an aromatic dicarboxylic acid having a molecular weight less than about 300, and
D is a divalent radical remaining after removal of hydroxyl groups from a diol having
a molecular weight less than about 250; provided said short chain ester units amount
to about 20-85 percent by weight of said copolyetherimide ester.
The soft segments of these polymers are derived from poly(oxyalkylene
diimide) diacid which can be
characterized by the following formula:
Wherein, each R" is independently a trivalent organic radical, preferably a C2
to C20 aliphatic, aromatic or cycloaliphatic trivalent organic radical;
R' is independently hydrogen or a monovalent organic radical preferably selected
from the group consisting of C1 to C6 aliphatic and cycloaliphatic
radicals and C6 to C12 aromatic radicals, e.g., benzyl, much
preferably hydrogen; and G' is the radical remaining after the removal of the terminal
(or as nearly terminal as possible) amino groups of a long chain ether diamine having
an average molecular weight of from about 600 to about 12,000, preferable from about
900 to about 4,000, and a carbon-to-oxygen ratio of from 1.8 to about 4.3.
These long chain ether glycols from which the polyoxyalkylene diamine
is prepared include poly (ethylene ether) gylcol; poly(propylene ether) glycol;
poly(tetramethylene ether) gylcol; random or block copolymers of ethylene oxide
and propylene oxide, including propylene oxide terminated poly (ethylene ether)
gylcol; and random or block copolymers of tetrahydrofuran with minor amounts of
a second monomer such as methyl tetrahydrofuran. Especially preferred poly(alkylene
ether) gylcols are poly(propylene ether) gylcol and poly(ethylene ether) gylcol
end capped with poly(propylene ether) gylcol and/or propylene oxide.
The tricarboxylic component is a carboxylic acid anhydride containing
an additional carboxylic group or the corresponding acid thereof containing two
imide forming vicinal carboxyl groups in lieu of the anhydride group. Mixtures thereof
are also suitable. The additional carboxylic group must be esterified and preferably
and substantially nonimidizable.
Further, while trimellitic anhydride is preferred as the tricarboxylic
component, any of a number of suitable tricarboxylic acid constituents will occur
to those skilled in the art.
Generally, the thermoplastic elastomers comprise the reaction product
of dimethyltherephthalate, preferably with up to about 40 mole percent of another
dicarboxylic acid; 1,4-butanediol, generally, with up to about 40 mole percent of
another saturated or unsaturated aliphatic and/or cycloaliphatic diol, and a polyoxyalkylene
diamide diacid prepared from a polyoxyalkalene diamine of molecular weight, about
600 to about 12,000, preferable from about 900 to about 4,000, and trumellitic anhydride.
Mixtures of two different diols can be employed, such as 1,4-butanediol and 1,4-butenediol.
The polyetherimide esters described herein and the procedures for
their preparation are more fully described in U.S. Pat. Nos. 3,123,192, 3,763,109;
3,651,014; 3,663,655; and 3,801,547 incorporated herein by reference.
The preparation of the copolyetherimide ester is more fully described
in U.S. Patent 4,556, 705, also incorporated herein by reference.
Another thermoplastic resin that may be employed in the practice of
this invention are the copolyether esters which also consist of a multiplicity of
recurring long chain ester units and short chain ester units, joined head-to-tail
through ester linkages. The long chain ester units are represented by the formula:
and the said short chain ester units are represented by the formula:
wherein G is a divalent radical remaining after the removal of terminal hydroxyl
groups from a poly(alkyleneoxide) glycol having a number average molecular weight
of about 400 to about 6,000 and a carbon to oxygen atomic ratio of about 2.0-4.3;
R is a divalent radical remaining after removal of carboxyl groups from an aromatic
dicarboxylic acid having a molecular weight of less than about 300 and D is a divalent
radical remaining after removal of hydroxyl groups from a diol having a molecular
weight less than about 250; provided said short chain ester units amount to about
25-70 percent by weight of said copolyetherester.
A more detailed description of suitable copolyether esters and procedures
for their preparation are further described in U.S. Patent Nos. 3,023,192; 3,651,014;
3,763,109; 3,766,146; and 4,355,155, which are incorporated herein by reference.
The high molecular weight polyalkylene terephthalates are another
thermoplastic resin that may be employed in the practice of the present invention,
and they are polyesters derived from an aliphatic or cycloaliphatic diol or mixtures
thereof, containing 2 or more carbon atoms and at least one aromatic dicarboxylic
acid. The polyester which are utilized herein are available commercially or can
be prepared by known techniques, such as by the alcoholysis of esters of the phthalic
acid or combination of phthalic acids with an aliphatic diol and subsequent polymerization,
by heating the diol with the free acids or with halide derivatives thereof, and
similar processes. These are described in U.S. Pat. Nos. 2,465,319 and 3,047,539,
One class of preferred polyesters employed in the practice of this
invention will be of the family consisting of high molecular weight, polymeric aliphatic
terephthalates and/or isophthalates having repeating units of the general formula:
wherein n is a whole number of from two to four, and mixtures of such esters, including
copolyesters of terephthalic and isophthalic acids of up to about 30 mole percent
of isophthalic units.
Especially preferred polyesters are poly(ethylene terephthalate) and
poly(1,4-butylene terephthalate), although poly(propylene terephthalate) may also
be employed herein.
Illustratively, high molecular weight polyesters will have an intrinsic
viscosity of at least about 0.4 deciliters/gram and, preferably, at least about
0.7 deciliters/gram as measured in a 60:40 phenol tetrachloroethane mixture at 30°C.
At intrinsic viscosities of at least about 1.1 deciliters/gram, there is a further
enhancement in toughness of the present compositions.
Also included within the scope of the present invention with respect
to the high molecular weight linear polyesters are combinations of polybutylene
terephthalates and polyethylene terephthalates. The combinations may be blends thereof,
or blends of copolymers of polybutylene terephthalate and polyethylene terephthalate
with homopolymers of polybutylene terephthalate, or copolymers of the two polyesters.
The preferred combination is a blend of polybutylene terephthalate and polyethylene
terephthalate. Although during extrusion of the blend of the two polyesters, some
copolymer may be formed, probably in about the 5 weight percent range. Normally,
a phosphorous stabilizer is added, particularly a phosphite, in order to inhibit
the formation of the copolymer of the polybutylene terephthalate and the polyethylene
terephthalate. In the blends thereof, the composition will generally consist essentially
of about 30 to 70 and preferably 40 to 60 parts by weight of the polybutylene terephthalate
and correspondingly about 70 to 30 parts and preferably about 60 to 40 parts by
weight of the polyethylene terephthalate, the parts by weight being based on the
total weight of the polybutylene terephthalate and polyethylene terephthalate.
Also contemplated herein are the above polyesters with minor amounts,
e.g., from 0.5 to about 2 percent by weight, of units derived from aliphatic acids
and/or aliphatic polyols, to form copolyesters. The aliphatic polyols include glycols
such as poly(ethylene glycol). These can be made following the teachings of, for
example, U.S. Pat. Nos. 2,465,319 and 3,047,539.
Among the units which can be present in the copolyesters are those
derived from aliphatic dicarboxylic acids, e.g., of up to and above about 50 carbon
atoms, including cycloaliphatic straight and branched chain acids, such as adipic
acid, cyclohexanediacetic acid, dimerized C16-C18 unsaturated
acids (which have 32 to 36 carbon atoms), trimerized acids, and the like.
Another preferred class of polyesters employed in the present invention
are derived from a cycloaliphatic diol and an aromatic dicarboxylic acid prepared
by condensing either the cis- or trans-isomer (or mixtures thereof) of, for example,
1,4-cyclohexanedimethanol with the aromatic dicarboxylic acid so as to produce a
polyester having recurring units having the following formula:
wherein the 1,4-cyclohexane dimethanol is selected from the cis- and trans-isomers
thereof and R10 represents an aryl radical containing 6 to 20 carbon
atoms and which is the decarboxylated residue derived from an aromatic dicarboxylic
Examples of aromatic dicarboxylic acids indicated by R10
in the formula above include isophthalic or terephthalic acid, 1,2-di(p-carboxyphenyl)ethane,
4,4'dicarboxydiphenyl ether, etc., and mixtures of these. All of these acids contain
at least one aromatic nucleus. Fused rings can also be present such as in 1,4 or
1,5 naphthalenedicarboxylic acids. The preferred dicarboxylic acid is terephthalic
acid or mixtures of terephthalic and isophthalic acid.
A preferred polyester may be derived from the reaction of either the
cis- or trans-isomer (or a mixture thereof) of 1,4-cyclohexanedimethanol with a
mixture of iso- and terephthalic acids. These polyesters have repeating units of
Another preferred polyester is a copolyester derived from a cyclohexanedimethanol,
an alkylene glycol and an aromatic dicarboxylic acid. These copolyesters are prepared
by condensing either the cis- or trans-isomer (or mixtures thereof) of, for example,
1,4-cyclohexanedimethanol and an alkylene glycol with an aromatic dicarboxylic acid
so as to produce a copolyester having repeating units of the following formula:
wherein the 1,4-cyclohexanedimethanol is selected from the cis- and trans-isomers
thereof, R10 is a previously defined, n is an integer of 2
to 4, the c units comprise from about 10 to about 90 percent by weight, and the
d units comprise from about 10 to about 90 percent by weight.
The preferred copolyesters may be derived from the reaction of either
the cis- or trans-isomer (or mixtures thereof) of 1,4-cyclohexanedimethanol and
ethylene glycol with terephthalic acid in, for example, a molar ratio of 1:2:3.
These copolyesters have repeating units of the following formula:
wherein c and d are as previously defined.
The polyesters are described herein are either commercially available
or can be produced by methods well known in the art such as those set forth in,
for example, U.S. Pat. No. 2,901,466.
The preferred cycloaliphatic polyesters are poly(1,4-cyclohexanedimethanol
tere/iso-phthalate) and a copolyester of 1,4-cyclohexanedimethanol, ethylene glycol
and terephthalic acid and poly(ethylene terephthalate) as previously described.
The polyesters used herein have an intrinsic viscosity of at least
about 0.4 and may be as high as about 2.0 dl/g. measured in a 60:40 phenol/tetrachloroethane
mixture of similar solvent at 23°-30° C.
The aromatic polycarbonates employed in the instant invention are
well known polymers and are disclosed in many U.S. patents such as U.S. Patents
2,999,835, 3,038,365, 3,334,154, and 4,131,575, all of which are incorporated herein
by reference. Such aromatic polycarbonates are prepared from dihydroxy phenols and
carbonate precursors. The polycarbonates suitable for use in the instant invention
generally have a number average molecular weight of from about 8,000 to about 80,000
and preferably from about 10,000 to about 50,000 and an intrinsic viscosity (I.V.)
of about 0.35 to about 1.0 deciliters per gram (dl/g) as measured in methylene chloride
Suitable dihydroxy phenols employed in the preparation of the polycarbonates
include for example 2,2-bis(4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane,
2,2-bis(4-hydroxy-3-methylphenyl) propane, 4,4-bis(4-hydroxyphenyl) heptane, 2,2,-(3,5,3',5'-tetrachloro-4,4'-dihydroxyphenyl)
propane, 2,2-(3,5,3',5'tetrabromo-4,4'-dihydroxyphenyl)propane, and 3,3'-dichloro-4,
4'-dihydroxydiphenyl)methane. Other dihydroxy phenols which are also suitable for
use in the preparation of the above polycarbonates are also disclosed in the above
references which have been incorporated herein by reference.
It is of course possible to employ two or more different dihydroxy
phenols in preparing the polycarbonates of the invention. In addition, branched
polycarbonates such as those described in U.S. Patent 4,001,184 can also be utilized
in the practice of the instant invention, as well as blends of a linear aromatic
polycarbonate and a branched aromatic polycarbonate. The branched polycarbonate
resins may be prepared by reacting (i) at least one dihydroxy phenol of the type
described herein, (ii) a carbonate precursor, and (iii) a minor amount of a polyfunctional
organic compound. The polyfunctional organic compounds used in making the branched
polycarbonates are well known in the art and are disclosed, for example, in the
U.S. Patent Nos. 3,525,712; 3,541,049; 3,544,514; 3,635,895; 3,816,373; 4,001,184;
4,294,953, and 4,204,047, all of which are hereby incorporated herein by reference.
These polyfunctional organic compounds are generally aromatic in nature and contain
at least three functional groups which may be, for example, hydroxyl, carboxyl,
carboxylic anhydride, haloformyl, and the like. Some illustrative nonlimiting examples
of these polyfunctional compounds include trimellitic anhydride, trimellitic acid,
trimellityl trichloride, 4-chloroformyl phthalic anhydride, pyomellitic dianhydride,
mellitic acid, mellitic anhydride, trimesic acid, benzophenonetetracarboxylic acid,
benzophenonetetracarboxylic acid, benzophenone-tetracarboxylic anhydride, and 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)
heptene-2. The amount of this polyfunctional organic compound or branching agent
used is in the range of from about 0.05 to about 2 mole percent based on the amount
of dihydric phenol employed, and preferable from about 0.1 to about 1 mole percent.
The processes for preparing the polycarbonate employed in the instant
invention are well known in the art. There are many patents fully describing the
preparation of the polycarbonates including those recited previously herein, and
as well as U.S. Patent 4,937,130 and U.S. Patent 4,513,037, both of which are incorporated
herein by references.
As described in the prior art, a carbonate precursor is.employed to
prepare the polycarbonates such as a carbonyl halide, a carbonate ester or a haloformate.
Typically, the well known carbonate precursor is a carbonyl chloride. A typical
carbonate ester is diphenyl carbonate. A typical haloformate is a bishaloformate
of a dihydroxyphenol such as the bishaloformate of ethylene glycol. The above carbonate
precursors are merely typical or those that can be employed and are not intended
to be limiting. Such carbonate precursors are also well known in the art and are
listed in the prior art cited previously herein.
The polycarbonate employed herein may also be a copolyestercarbonate
as described in U.S Patent 4,430,484 and in the other references cited in U.S. Patent
4,430,484, which is incorporated herein by reference. Preferred polyestercarbonates
are those derived from the dihydroxyphenols and carbonate precursors described above
and aromatic dicarboxylic acids or their relative derivatives thereof, such as the
acid dihalides, e.g. dichlorides. In addition, a mixture of dicarboxylic acids can
be employed such as terephthalic acid and isophthalic acid. Further, their respective
acid chlorides can also be used. Thus, a useful class of aromatic polyestercarbonates
are those prepared from bisphenol-A, terephthalic acid or isophthalic acid or a
mixture thereof and a carbonyl chloride also known as phosgene. These copolyestercarbonates
are also commonly known as polyphthalate carbonates and are, also described in U.S.
Patent 4,465,820, incorporated herein by reference.
Rubber modified homopolymers and copolymers of vinyl aromatic monomers
that can be employed in the present invention include the rubber modified homopolymers
and copolymers of styrene or a-methylstyrene with a copolymerizable comonomer. Preferred
comonomers include acrylonitrile which may be employed alone or in combination with
other comonomers, particularly methylmethacrylate, methacrylonitrile, fumaronitrile
and/or an N-arylmaleimide such as N-phenylmaleimide. Highly preferred copolymers
contain from about 70 to about 80 percent styrene monomer and 30 to 20 percent acrylonitrile
Suitable rubbers include the well known homopolymers and copolymers
of conjugated dienes, particularly butadiene, as well as other rubbery polymers
such as olefin polymers, particularly copolymers of ethylene, propylene and optionally
a nonconjugated diene, or acrylate rubbers, particularly homopolymers and copolymers
of alkyl acrylates having from 4 to 6 carbons in the alkyl group. In addition, mixtures
of the foregoing rubbery polymers may be employed if desired. Preferred rubbers
are homopolymers of butadiene and copolymers thereof with up to about 30 percent
by weight styrene. Such copolymers may be random or block copolymers, and, in addition,
may be hydrogenated to remove residual unsaturation.
The rubber modified copolymers are preferably prepared by a graft
generating process such as by a bulk or solution polymerization or by emulsion polymerization
of the copolymer in the presence of the rubbery polymer. In the emulsion polymerization
to form graft copolymers of rubbery substrates, it is previously known in the art
to employ agglomeration technology to prepare large and small rubber particles containing
the copolymer grafted thereto. In the process, various amounts of an ungrafted matrix
of the copolymer are also formed. In the solution or built polymerization of a rubber
modified copolymer of a vinyl aromatic monomer, a matrix copolymer is formed. The
matrix further contains rubber particles having copolymer grafted thereto occluded
A particularly desirable product comprises rubber modified copolymer
blend comprising both the mass or solution polymerized rubber modified copolymer
and additional quantities of an emulsion polymerized and preferably agglomerated
rubber modified copolymer containing a bimodal particle-sized distribution. A most
preferred rubber modified copolymer comprises a butadiene rubber modified copolymer.
Butadiene rubber modified copolymers of styrene and acrylonitrile are referred to
in the art as ABS resins.
The polyphenylene esters employed in the practice of this invention
are a well known class of compounds sometimes referred to as polyphenylene oxides.
Examples of suitable polyphenylene ethers and processes for their preparation can
be found in U.S. Pat. Nos. 3,3086,874; 3,3086,875; 3,257,357; and 3,257,358 which
are incorporated by reference. Compositions of the present invention will encompass
homopolymers, copolymers and graft copolymers obtained by the oxidative coupling
of phenolic compounds. The preferred polyphenylene ethers used as base resins in
compositions of the present invention will be comprised of units derived from 3,6-dimethyl
phenol. Also contemplated are PPE copolymers comprised of units derived from 2,6-dimethyl
phenol and 2,3,6-trimethyl phenol.
A particularly useful polyphenylene ether would be poly(2,6-dimethyl-1,4-phenylene
ether) having an intrinsic viscosity (I.V.) greater than, approximately 0.10 dl/g
as measured in chloroform at 25°C. The I.V. will typically be between 0.30 and 0.60
The polyamide resins useful in the practice of the present invention
are known as nylons, and are characterized by the presence of an amide group (-CONH-).
Nylon-6 and nylon 6,6 are the generally preferred polyamides and are available from
a variety of commercial sources. The polyamides may be either amorphous or crystalline
Typical examples of the polyamides or nylons, as these are often called,
include for example polyamides 6, 6/6, 11, 12, 6/3, 6/4, 6/10, and 6/12, as well
as polyamides resulting from terephthalic acid and/or isophthalic acid and trimethyl
hexamethylene diamine, polyamides resulting from adipic acid and meta xylylenediamines,
polyamides resulting from adipic acid, and metaxylylenediamines, polyamides resulting
from adipic acid, azelaic acid and 2,2-bis-(p-aminocyclohexyl)propane and polyamides
resulting from terephthalic acid and 4,4'-diamino-dicyclohexylmethane. Mixtures
and/or copolymers of two or more of the foregoing polyamides or prepolymers thereof,
respectively, are also within the scope of the present invention. Preferred polyamides
are the polyamides 6, 6/6, 11, and 12, most preferably polyamide 6/6.
It is also to be understood that the use of the term "polyamides"
herein and in the appended claims is intended to include the toughened or super
tough polyamides. Super tough polyamides, or super tough nylons, as they are more
commonly known, are available commercially, e.g. from E. I. duPont under the tradename
Zytel ST, or may be prepared in accordance with a number of U.S. Patents, including,
among others, Epstein U.S. Pat. No. 4,174,358; Novak U.S. Pat. No. 4,474,927; Roura
U.S. Pat. No. 4,346,194; and Joffrion U.S. Pat. No. 4,251,644, all of which are
herein incorporated by reference. These super tough nylons are prepared by blending
one or more polyamides with one or more polymeric or copolymeric elastomeric toughening
agents. Suitable toughening agents are disclosed in the above-identified U.S. Pat.
Nos., as well as in Caywood, Jr. U.S. Pat. No. 3,884,882 and Swiger U.S. Pat. No.
4,147,740 and Gallucci et al., "Preparation and Reactions of Epoxy-Modified Polyethylene",
J. APPL. POLY. SCI. V. 27, pp. 425-437 91982) all incorporated herein by reference.
Typically, these elastomeric polymers and copolymers may be straight chain or branched,
as well as graft polymers and copolymers, including core-shell graft copolymers,
and are characterized as having incorporated therein either by copolymerization
or by grafting on the preformed polymer, a monomer having functional and/or active
or highly polar groupings capable of interacting with or adhering to the polyamide
matrix so as to enhance the toughness of the polyamide polymer.
As stated previously, the thermoplastic composition of this invention
may also comprise blends of the above polymers. An example of such blends may be
blends of an aromatic polycarbonate and an ABS in a range of about 30 to about 70
weight percent of polycarbonate and about 70 to about 30 weight percent of ABS based
on the weight of the polymers employed. In another system, a blend of the polycarbonate
and a polyalkylene terephthalate (polybutylene terephthalate) may also be employed
herein. Still another blend that may be employed in the practice of this invention
is a blend of a polyphenylene ether and a polyamide. Yet another blend may be that
of copolyetherimide ester or a copolyether ester and a polyalkylene terephthalate
(PBT), or a blend of a polycarbonate, a polybutylene terephthalate (PBT) and ABS.
The above blends are merely some of the typical blends that may be employed in the
practice of this invention and other blends will become obvious to those skilled
in the art in view of the disclosure herein.
In addition, as stated previously, blends of the above polymers with
other polymers are also included within the scope of the present invention. For
example, blends of polyphenylene ether and a styrene polymer may be employed, such
as NORYL® resin sold by General Electric Company. Copolymers of styrene and
methyl-methacrylate may also be used herein with any of the polymers described above.
Polyethylene and polycarbonate is another blend that may be employed herein. Again,
these blends are merely representative of some of the blends that may be employed
herein and other such blends will be obvious to those skilled in the art in view
of the teachings disclosed herein.
The mineral additive employed in the practice of this invention has
needle like particles. While any such mineral additive may be employed herein, the
particles should have the particle size distribution as disclosed herein. Preferably,
the mineral filler consists essentially of calcium meta silicate, which is also
referred to as calcium silicate, and more commonly as wollastonite. However, since
the mineral is mined, other ingredients may also be present in wollastonite, such
as trace amounts of aluminum oxide, magnesium oxide and/or iron oxide. Although
wollastonite is identified as calcium meta silicate, there may be some free silicon
dioxide present therein as well. The mineral filler of this invention consists essentially
of needle like particles having a mean number average length of about 1.0 µm to
about 50 µm and and a mean number average diameter of about 0.1 µm to about 10 µm.
Preferably, at least 80 percent of the needle like particles of the mineral additive
have a length of about 5 µm to about 40 µm, and more specifically at least 50 percent
of the needle like particles have a length of about 5 µm to about 25 µm. This results
in a number average aspect ratio of length to diameter of up to about 6 and preferably
ranging from less than about 1.0 to about 10.
The preferred mineral additive employed in the present invention is
wollastonite or also known as calcium meta silicate, having the particular particle
morphology disclosed previously. Wollastonites are well known minerals and are used
as fillers in thermoplastics. However, the known and previously employed wollastonites
have a mean number average length of about 90 µm, and a mean average diameter of
about 15µm or greater. Also, at least 50 percent of the particles have a length
ranging from about 15 µm to over 50 µm, with at least 80 percent of the particles
ranging from 15 to about 150 µm.
It has also been found that when the composition of this invention
is injection molded, the mineral additive particles may undergo a breaking or shearing,
which may result in a decrease of the aspect ratio. Even though this shearing may
occur, the mean average aspect ratio would probably still be within the range of
less than about 1 to about 10.
The object of this invention is to provide an improved thermoplastic
molding composition as described previously having the advantage of providing molded
articles having a lower CTE and a high or improved DOI. It has also been found that
certain compositions of this invention are ductile compared to previously commonly
employed wollastonites, as demonstrated in the Examples. It has further been unexpectedly
discovered that the use of the particular wollastonite of this invention may also
result in a higher DOI, as compared in previously employed wollastonites or other
fillers. For example, as shown in the Examples, the use of the wollastonite of this
invention greatly increased the DOI of the molded article over previously known
fillers. In addition, the mineral filler herein disclosed also provides greater
impact strength as determined by the Dynatup impact test, even though brittle breaks
may occur. This is demonstrated in the Examples, wherein higher energy is required
to break or pierce the sample, again in comparison to previously known wollastonite.
This represents that even though the break may be brittle, greater impact is necessary
in order to achieve breakage. The results show that a substantial greater energy
is required, both at room temperature and at subzero temperatures. It is surprising
that the substantial unexpected property increases that are achieved with the particular
mineral additives of this invention. Even when employed in combination with other
fillers, which are described hereinafter, dramatic increases in properties can be
The mineral additive of this invention may act as a filler or it may
act as a reinforcing agent or it may act as a combination of both. The particular
mineral additive may also preferably have a surface treatment on the particles such
as with a silane surface treatment such as an alkoxy silane or other type of coupling
agent such as a titinate or zirconate for example. However, the critical feature
of the present invention is that by employing the particular mineral additive disclosed
herein, the results achieved as shown in the Examples are not achieved with previously
known fillers such as carbon fibers, mica, talc, glass fibers, and even previously
known wollastonites, other than the wollastonite having the particle morphology
disclosed in this invention.
In addition, it has also been unexpectedly discovered that articles
molded from the improved composition of this invention may have a Class A surface.
The test procedure employed in this invention for determining Class A surface is
the distinctness of image (DOI) test procedure (as later described herein), which
is a determination of the percentage of reflective light waves that are reflected
from the surface of the molded article. The higher the percentage, the smoother
is the surface. In the present invention, articles molded with the composition herein
disclosed can have a DOI of greater than 95% as compared to lower DOI's for the
same composition employing previously known fillers or reinforcing agents when molded
under the same conditions. As is understood by those skilled in the art, the composition
itself is an important and critical factor in obtaining a Class A surface. However,
properly prepared surfaces of the mold employed in injection molding or whatever
mold is employed in molding are also a factor in achieving a Class A surface along
with the factor of the composition. With a dull or slightly imperfect mold surface,
one may still obtain a Class A surface with an article molded from the composition
of this invention. On the other hand, a roughened mold surface may well not produce
a Class A surface on an article molded from the composition of this invention, regardless
of the composition. All things being equal, i.e. a properly polished mold surface,
molded articles molded from the composition of this invention can have a Class A
surface as determined by the DOI.
In addition, the composition of this invention may include other additives
such as impact modifiers, heat and light stabilizers, flame retardants and other
additives well known to those skilled in the art. An impact modifier can be an important
additive where increased or improved impact resistance is wanted. While many known
impact modifiers may be employed herein providing that the impact modifier employed
enhances the impact properties of the molded article substantially without affecting
the other physical properties of the composition of this invention, particularly
useful are the rubbery shell-core type of impact modifiers. One type of shell-core
impact modifier is the all acrylic modifier, i.e. one having a polyacrylate core
such as polybutyl acrylate with a shell of a methyl methacrylate such as styrene
methyl methacrylate or an acrylonitrile methyl methacrylate shell. Another type
of shell-core impact modifiers is one having a polybutadiene core that is preferably
a cross-linked polybutadiene core with an acrylate shell such as the same types
of acrylate shells disclosed above. Sometimes it is advantageous to use linking
compounds or linking monomers during the polymerization of the impact modifiers
in order to link or bind the shell to the core. Another type of rubbery impact modifier
that may be employed herein is styrene-butadiene-tyrene triblock copolymers, or
styrene-ethylene/butylene-styrene triblock copolymers or styrene ethylene/propylene-styrene
diblock copolymers. These are available from Shell Chemical which is sold under
the trademark Kraton. The amount of impact modifier that may be optionally employed
herein is about 0.5 to about 25 parts by weight based on the weight of the polymer,
the mineral additive and the impact modifier. Such impact modifiers as described
above are available commercially from various polymer manufacturers.
Also contemplated as part of this invention are blends of mineral
additives such as blends of the mineral additive of this invention with other fillers
such as mica, talc, carbon black, or other minerals not having the needle like morphology
of the mineral additive of this invention Even the blend of minerals produces improvement
in such properties as DOI and/or the CTE, i.e. by lowering the CTE. For example,
a blend of the polymers of this invention with just mica demonstrates (not with
the mineral filler of this invention) that a low DOI is obtained on molded parts.
However, when adding wollastonite having the particle morphology disclosed in this
invention to a blend of a polymer and mica, the DOI is dramatically improved, and
the CTE is lowered. This can also occur with blends of the mineral additive of this
invention and other mineral additives. The use of such blends can produce lower
CTE and better or improved DOI, as demonstrated in the Examples. The amount of other
mineral additive that can be blended with the mineral additive of this invention
should be that amount that does not affect the increased properties of CTE, DOI,
impact, etc. obtained with the mineral additive of the invention. In effect, one
can use a lower cost mineral additive in place of part of the mineral additive of
this invention without significantly affecting the increased properties afforded
by the instant additive disclosed herein. Preferably, the amount of mineral additive
of this invention should be about at least 50 percent by weight of the additive,
and, more particularly, about at least 70 percent by weight with the balance being
such other mineral additive not of the needle like particles disclosed herein.
Also included within the scope of this invention, is the use of a
blend of needle like particles having the morphology of the mineral additive of
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following Examples are set forth to illustrate the present invention
and are not to be construed as limiting the scope of this invention thereto. Unless
otherwise indicated, all parts and percentages are on a weight basis.
EXAMPLES 1 - 4
All ingredients were dry blended in a laboratory tumbler. The blend
was then fed to a twin screw 58 mm. co-rotating intermeshing extruder. The temperature
of the extruder was at about 480°F to about 520°F flat temperature profile along
the extruder barrel, depending on the polymer used, and one skilled in the art would
well know the temperature to use. The die temperature through which the composition
was extruded was about the same temperature as the extruder barrel temperature,
namely about 480°F to about 500°F. The extrudate was pelletized and dried at a temperature
of about 230°F for 2 hours in a hot air circulating oven. The pelletized compositions
were then molded into test specimens using an 80 ton Van Dorn injection molding
machine. The temperature of the molding machine was at about 480°F to a about 500°F
with a mold temperature of about 150°F, again depending on the polymer employed
and would well be within the knowledge of one skilled in the art. The size of the
test specimens varied depending on the test to be run. For notched IZOD impact,
the tests specimens were about 3" long by 1/2" wide by 1/8" thick and were tested
in accordance with ASTM D630A. For Dynatup impact testing and paint testing, the
test specimens molded were about 4" in diameter by about 1/8" thick. The Dynatup
test was performed under ASTM test procedure D3763-86 using the Dynatup impact testing
equipment by General Research Instruments. Briefly, the test procedure involves
subjecting samples to a falling dart impact. The dart is about a 0.5" diameter rod
about 1.5" long and has a rounded, blunt end, which is the end that impacts upon
the sample. The molded sample is clamped in a holding device. The date is on a vertical
sled or shaft, with weights added for energy impact determination. The test is designed
to force failure of the sample in order to determine the type of failure occurring.
The average velocity of the falling dart was about 11.3 feet per second, and the
impact energy was 100 foot-pounds, with a drop height of two feet.
In the Dynatup impact test, the energy absorbed by the sample by the
falling dart is plotted on a graph from the time the dart first hits the sample
until it punctures through the sample. E(max) is the maximum energy absorbed by
the sample at the peak of the graph, which is a chart of the energy absorbed by
the sample. E(tot) is the total energy absorbed over the range of time the dart
first hits the sample until it punctures through the sample. Generally, E(max) and
E(tot) are the average of several samples for each formulation tested, as shown
in the tables.
The DOI test procedure was developed to determine the effect fillers
in materials may have on specular gloss of the topcoat paint when no primer, sealer,
surfacer, etc. is used. Some automobile parts are so prepared with topcoat only.
Since DOI will vary depending on the paint color, a high gloss black automotive
paint is used as the standard. This paint yields a DOI of 99+% when properly applied
to unfilled materials, i.e. plastics without inorganic fillers such as glass, mica,
clay, etc. Samples are all painted together with an automatic paint spraying machine
(Spraymation #310740) to insure proper uniformity and repeatability of application
parameters (flash time, paint thickness, etc.). When the paint is cured, the DOI
is measured in several locations on each sample with a meter. An ATI model #1792
special gloss meter is used. The results are reported in the Tables below.
The wollastonite of this invention employed in the Examples was NYGLOS
wollastonite, having an average mean diameter based on number average of less than
about 4.5 µm and an average mean length of about 24 µm. The wollastonite of the
prior art employed in the Examples was NYAD G wollastonite, having an average mean
diameter based on number average of about 16 µm and an average mean length of about
90 µm. Both wollastonites are from NYCO Company. The morphology of the NYGLOS and
NYAD G wollastonites was determined on the raw material, i.e. before compounding
with the particular resins and other additives to prepare the formulations set forth
in the Tables. The method employed was light microscopy. Photomicrographs were made
using transmitted bright field illumination on a Zeiss Photomicroscope interfaced
to a Zeiss IBAS image analysis system. From the photomicrographs, particles were
measured and number average mean results were obtained as reported above. Particle
size distribution was also determined.
The results of the above tests were as follows:
EXAMPLES 5 - 10
Examples 1 - 4 were repeated, except that the ingredients and compositions
were as reported in Table 2 below:
Examples 1 - 4 were repeated, except that the formulations employed
herein were as reported in Table 3, along with the results obtained.
EXAMPLES 17 - 24
Examples 1 - 4 were repeated, except that the formulations employed
herein were as reported in Table 4, along with the results.
Several blends were prepared, each of which contained 49 parts by
weight poly(2,6-dimethyl-1,4-phenylene ether) which had an intrinsic viscosity of,
approximately, 0.45 dl/g as measured in chloroform at 25°C, 0.70 part citric acid
monohydrate compatibilizing agent, 10 parts rubber modifier (Kraton, G- 1651 Shell
Chemical, a styrene-ethylene/butylene-styrene triblock copolymer), 0.30 part Irganox
1076 hindered phenol stabilizer, 0.10 part KI stabilizer, and 10 parts of a specified
The foregoing blended components of the composition were fed to the
feedthroat of a 30 mm. Werner & Pfleiderer twin screw extruder which was fitted
with a downstream addition port. The extruder was set at 550°F, and was fitted with
a downstream addition port.
An additional 31 parts of a nylon component specified in the table
were fed at the downstream addition port.
The resulting extruded strand was chopped into pellets, dried and
molded into ASTM test parts in a Newbury 3 ounce injection molder having a 550°
F set temperature profile and a mold set temperature of 150°F. All test results
described in Table 1 were performed in accordance with ASTM test specifications.
The polyamide component designated as nylon 6,6 was NP-10,000 from
Nylon Polymers. The nylon 6 was Nycoa 471 from Nylon Corp. of America.
The filled compositions were prepared in the same fashion as set forth
in the previous para-
graph, except the filled compositions consisted of a blend of 40 parts of the poly(2,6-dimethyl-1,4-phenylene
ether), 36 parts of the nylon 6/6, 10 parts of the Kraton G-1651, 0.7 parts of citric
acid, and 14 parts of the filler, which is as set forth in Table 5 below with the
results of the tests run on the Examples, namely Dynatup Impact, coefficient of
thermal expansion (CTE), DOI and tensile elongation. Tensile elongation was determined
in accordance with ASTM test procedure D638. The other test procedures are as described
in Examples 1 - 4.
The above examples were materials tested for their suitability for painted automotive
bodypanels. D means number average diameter of the fibers. L means number average
length of the fibers. The compositions comprised 70% by weight polybutylene terephthalate,
20 percent by weight polyetherimide ester resin, and 10 percent by weight reinforcing
fiber based on the entire weight of the composition. A DOI value of at least 95%
is necessary for a composition to be suitable for the automotive body panels, preferably
having a DOI of at least 99%. Examples 40°C - 45°C are comparative examples. Examples
34 - 38 exhibit sufficiently high DOI values. DOI is measured after exposure of
the composition to 280°F. Preferably the coefficient of thermal expansion is between
3 x 10-5 inches/inch/°F and 5 x 10-5 inches/inch/°F, more
preferably between 4 x 10-5 inches/inch/°F and 5 x 10-5 inches/inch/°F.
Therefore, in the present invention, it is to be understood by those
skilled in the art that various changes may be made in the particular embodiments
described above without departing from the spirit and scope of the invention as
defined in the appended claims
An improved thermoplastic molding composition comprising in admixture (1) a
thermoplastic polymer selected from the group consisting of a copolyetherimide ester,
a copolyether ester, a polyalkylene terephthalate, an aromatic polycarbonate, a
rubber modified homopolymer or copolymer of a vinyl aromatic monomer, a polyphenylene
ether, a polyamide, blends thereof, and blends thereof with other polymers, and
(2) a particulate mineral additive having needle like particles wherein the needle
like particles have a number average mean length of about 1.0 µm to about 50 µm
and a number average mean diameter of about 0.1 to about 10.0.
The thermoplastic molding composition of Claim 1 wherein the thermoplastic polymer
(1) is a copolyetherimide ester.
The thermoplastic molding composition of claim 1 wherein the thermoplastic polymer
(1) is a blend of a copolyetherimide ester and a high molecular weight polyalkylene
The composition of claim 1 wherein the mineral additive is calcium meta silicate.
The thermoplastic molding composition of claim 1 wherein the thermoplastic polymer
(1) is a blend of a copolyetherimide ester and a polybutylene terephthalate.
The composition of claim 1 comprising about 95 to about 30 weight percent of
the thermoplastic polymer (1) and correspondingly about 5 to about 70 weight percent
of the particulate mineral additive (2), based on the weight of components (1) and
The composition of claim 6 wherein the thermoplastic polymer (1) is a blend
of a polyalkylene terephthalate and an aromatic polycarbonate.
The composition of claim 7 wherein the composition comprises a blend of thereof
with an impact modifier.
The composition of claim 8 wherein the impact modifier is a shell-core impact
The composition of claim 1 wherein the thermoplastic polymer (1) is acrylonitrile-butadiene-styrene.
The composition of claim 1 wherein at least 50 percent of the particles of the
mineral additive have a length of about 5.0 µm to about 25 µm.
An improved thermoplastic molding composition consisting essentially of admixture
(1) a thermoplastic polymer selected from the group consisting of a copolyetherimide
ester, a copolyether ester, a polyalkylene terephthalate, a rubber modified homopolymer
or copolymer of a vinyl aromatic monomer, a polyphenylene ether, a polyamide, blends
thereof, and blends thereof with other polymers, and (2) a particulate mineral having
needle like particles wherein the needle like particles have a number average mean
length of about 1.0 µm to about 50 µm and a number average mean diameter of about
0.1 to about 10.
The composition of claim 12 consisting essentially of about 95 to about 30 weight
percent of (1) and correspondingly about 5 to about 70 weight percent of (2), based
on the weight of components (1) and (2).
The composition of claim 12 wherein the composition consists essentially of
a blend thereof with an impact modifier.
The composition of claim 14 wherein the impact modifier is a shell-core impact
The composition of claim 12 wherein the thermoplastic polymer is a blend of
a polyphenylene ether, a polyamide and a rubbery impact modifier.
The composition of claim 12 wherein the mineral additive is calcium meta silicate.
The composition of claim 12 wherein at least 50 percent of the particles-of
the mineral additive have a length of about 5.0 µm to about 25 µm.
The composition of claim 12 wherein the particulate mineral having needle like
particles is a blend thereof with another mineral additive.
The composition of claim 19 wherein the blend consists essentially of at least
about 50 percent by weight of the particulate mineral additive based on the total
weight of the particulate mineral additive.
The composition of claim 12 consisting essentially of (1) a polycarbonate, (2)
a rubber modified copolymer of a vinyl aromatic monomer, and (3) a particulate mineral
consisting essentially of at least 50 weight percent of the particulate mineral
having needle like particles.
The composition of claim 21 wherein the rubber modified copolymer of a vinyl
aromatic monomer is an acrylonitrile-butadiene-styrene copolymer and the particulate
mineral is a blend of the needle like particle and another mineral selected from
the group consisting of mica, talc and mixtures of mica and talc.