U.S. patent application number 09/740589 was filed with the patent office on 2002-08-22 for translucent polycarbonate composition, method for preparation thereof, and articles derived therefrom.
This patent application is currently assigned to General Electric Company. Invention is credited to Heeringen, Mark van, Hendrix, Bart Peter Gerard, Hoogland, Gabrie, Verhoogt, Hendrik.
Application Number | 20020115792 09/740589 |
Document ID | / |
Family ID | 24977196 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020115792 |
Kind Code |
A1 |
Verhoogt, Hendrik ; et
al. |
August 22, 2002 |
Translucent polycarbonate composition, method for preparation
thereof, and articles derived therefrom
Abstract
Translucent polycarbonate compositions include an aromatic
polycarbonate, a cycloaliphatic polyester, and a polyolefin. The
compositions have excellent optical characteristics and superior
physical properties, particularly low-temperature impact strength,
compared to translucent polycarbonate-polyester blends requiring
inorganic fillers.
Inventors: |
Verhoogt, Hendrik; (Bergen
op Zoom, NL) ; Hoogland, Gabrie; (Breda, NL) ;
Heeringen, Mark van; (Bergen op Zoom, NL) ; Hendrix,
Bart Peter Gerard; (Bergen op Zoom, NL) |
Correspondence
Address: |
Frank A. Smith
General Electric Company
One Plastics Avenue
Pittsfield
MA
01201
US
|
Assignee: |
General Electric Company
|
Family ID: |
24977196 |
Appl. No.: |
09/740589 |
Filed: |
December 19, 2000 |
Current U.S.
Class: |
525/133 |
Current CPC
Class: |
C08L 23/0869 20130101;
C08L 69/00 20130101; C08L 67/02 20130101; C08L 23/00 20130101; C08L
69/00 20130101; C08L 2666/02 20130101 |
Class at
Publication: |
525/133 |
International
Class: |
C08L 001/00 |
Claims
What is claimed is:
1. A molded translucent thermoplastic composition, comprising:
about 60 to about 99.8 weight percent of an aromatic polycarbonate;
about 0.1 to about 30 weight percent of a cycloaliphatic polyester;
about 0.1 to about 8 weight percent of a polyolefin; wherein the
molded composition has a transmission of about 15 to about 65% as
measured on a 2.0 mm thick plaque; and wherein all weight
percentages are based on the weight of the total composition.
2. The composition of claim 1, wherein the aromatic polycarbonate
is derived from at least one dihydric phenol selected from the
group consisting of 1,1-bis(4-hydroxyphenyl)methane;
1,1-bis(4-hydroxyphenyl)et- hane; 2,2-bis(4-hydroxyphenyl)propane;
2,2-bis(4-hydroxyphenyl)butane; 2,2-bis(4-hydroxyphenyl) octane;
1,1-bis(4-hydroxyphenyl)propane; 1,1-bis(4-hydroxyphenyl)-n-butane;
bis(4-hydroxyphenyl)phenylmethane;
2,2-bis(4-hydroxy-1-methylphenyl)propane;
1,1-bis(4-hydroxy-t-butylphenyl- )propane;
2,2-bis(4-hydroxy-3-bromophenyl)propane; 1,1-bis(4-hydroxyphenyl-
)cyclopentane; and 1,1-bis(4-hydroxyphenyl)cyclohexane.
3. The composition of claim 2, wherein the at least one dihydric
phenol comprises 2,2-bis(4-hydroxyphenyl)propane.
4. The composition of claim 1, wherein the cycloaliphatic polyester
comprises recurring units of the formula 7wherein R.sup.f
represents an alkyl or cycloalkyl radical having 2 to about 20
carbon atoms, and R.sup.g is an alkyl or a cycloalkyl radical
having 2 to about 20 carbon atoms with the proviso that at least
one of R.sup.f or R.sup.g comprises a cycloalkyl group.
5. The composition of claim 1, wherein the cycloaliphatic polyester
comprises
poly(1,4-cyclohexanedimethanol-1,4-cyclohexanedicarboxylate).
6. The composition of claim 1, wherein the aromatic polycarbonate
and the cycloaliphatic polyester are miscible.
7. The composition of claim 1, wherein the polyolefin is derived
from at least one monomer having from 2 to about 10 carbon
atoms.
8. The composition of claim 1, wherein the polyolefin comprises a
linear low-density polyethylene.
9. The composition of claim 1, wherein the polyolefin comprises a
polyolefin plastomer.
10. The composition of claim 1, wherein the polyolefin comprises 0
to about 50 weight percent acid-modified polyolefin.
11. The composition of claim 1, further comprising a
transesterification quencher selected from the group consisting of
mono-, di-, and tri-hydrogen phosphites and their metal salts;
mono-, di-, and tri-hydrogen phosphates and their metal salts;
mono- and di-hydrogen phosphonates and their metal salts;
pyrophosphates and their metal salts; and mixtures comprising at
least one of the foregoing quenchers.
12. The composition of claim 11, wherein the catalyst quencher
comprises mono zinc phosphate.
13. The composition of claim 11, wherein the catalyst quencher
comprises phosphorous acid.
14. The composition of claim 1, further comprising at least one
additive selected from the group consisting of whitening agents,
thermal stabilizers, antioxidants, light stabilizers, plasticizers,
colorants, impact modifiers, extenders, antistatic agents, mold
releasing agents, additional resins, blowing agents, and processing
aids.
15. The composition of claim 1, having a transmission measured on a
2.0 mm thick plaque of about 15 to about 55%.
16. The composition of claim 1, having a haze measured on a 2.0 mm
thick plaque not less than about 90%.
17. The composition of claim 1, having an Izod Notched Impact
Strength measured at 0.degree. C. according to ASTM D256 not less
than about 500 J/m.
18. The composition of claim 1, having an Izod Notched Impact
Strength measured at 0.degree. C. according to ASTM D256 not less
than about 700 J/m.
19. The composition of claim 1, having an Izod Notched Impact
Strength measured at 0.degree. C. according to ASTM D256 not less
than about 800 J/m.
20. The composition of claim 1, having a yellowness index measured
according to ASTM D1925 on a 2.0 mm plaque not greater than about
35.
21. A molded translucent thermoplastic composition, comprising:
about 75 to about 95 weight percent of an aromatic polycarbonate;
about 5 to about 15 weight percent of a cycloaliphatic polyester;
about 0.5 to about 3 weight percent of a polyolefin plastomer;
wherein the molded composition has a transmission of about 25 to
about 50% as measured on a 2.0 mm thick plaque; and wherein all
weight percentages are based on the weight of the total
composition.
22. A molded translucent thermoplastic composition, comprising the
reaction product of: about 60 to about 99.8 weight percent of an
aromatic polycarbonate; about 0.1 to about 30 weight percent of a
cycloaliphatic polyester; about 0.1 to about 8 weight percent of a
polyolefin; wherein the molded composition has a transmission of
about 15 to about 65% as measured on a 2.0 mm thick plaque; and
wherein all weight percentages are based on the weight of the total
composition.
23. A method of preparing a translucent thermoplastic composition,
comprising: premixing a composition comprising about 60 to about
99.8 weight percent of an aromatic polycarbonate; about 0.1 to
about 30 weight percent of a cycloaliphatic polyester; and about
0.1 to about 8 weight percent of a polyolefin; to form a dry blend;
and melt mixing the dry blend to form the thermoplastic
composition; wherein the molded composition has a transmission of
about 15 to about 65% as measured on a 2.0 mm thick plaque; and
wherein all weight percentages are based on the weight of the total
composition.
24. An article comprising the composition of claim 1.
25. A translucent sheet comprising the composition of claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a thermoplastic composition
comprising aromatic polycarbonate. In particular, the invention
relates to a translucent polycarbonate composition having excellent
physical properties.
[0002] Aromatic polycarbonates are engineering thermoplastics that
combine desirable mechanical, optical, thermal, and electrical
properties. When extruded in sheet form, aromatic polycarbonates
have high transparency and excellent impact strength, making them
ideal for a variety of glazing applications including roofs,
greenhouses, sunrooms, and swimming pool enclosures. For structures
in hot climates or for the southern exposure of structures in
various climates, it is often desirable to use polycarbonate sheets
having reduced light transmission in the form of opal whiteness
and/or translucency.
[0003] It is known in the art that polycarbonate resins can be
rendered translucent by the use of one or more inorganic additives
such as titanium dioxide, zinc oxide, zinc sulfide, lead carbonate,
and barium sulfate (see, for example, U.S. Pat. No. 4,252,916 to
Mark, and Japanese Unexamined Patent Publication Nos. JP 06-306266
and JP 09-048911). It is also known to make polycarbonate
translucent via addition of a partially fluorinated polyolefin
(see, for example, U.S. Pat. No. 4,252,916 to Mark), a polyolefinic
resin in combination with a plasticizer (see, for example, Japanese
Unexamined Patent Publication JP 05-017599A),
poly(dimethylsiloxane) gum in combination with finely divided
silica (see, for example, U.S. Pat. No. 3,933,730 to Hoogeboom),
poly(methyl silsesquioxane) (see, for example, European Patent No.
604,130 to Ohtsuka et al.), or spherical transparent thermoplastic
particles (see, for example, International Publication No. WO
00/27927).
[0004] Of the above methods, the addition of light-scattering
pigments, such as barium sulfate or calcium carbonate, is presently
favored for commercial production of translucent polycarbonate
compositions. However, the addition of such inorganic pigments
adversely affects the physical properties of the sheet, especially
its low temperature impact strength.
[0005] There remains a need for translucent polycarbonate
formulations with improved low temperature impact strength.
BRIEF SUMMARY OF THE INVENTION
[0006] A translucent polycarbonate composition comprises:
[0007] about 60 to about 99.8 weight percent of an aromatic
polycarbonate;
[0008] about 0.1 to about 30 weight percent of a cycloaliphatic
polyester;
[0009] about 0.1 to about 8 weight percent of a polyolefin;
[0010] wherein the molded or extruded composition has a
transmission of about 15% to about 65% at a thickness of 2.0 mm
according ASTM D-1003; and wherein all weight percentages are based
on the weight of the total composition.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] Translucency and high impact strength are provided by a
thermoplastic composition comprising:
[0012] about 60 to about 99.8 weight percent of an aromatic
polycarbonate;
[0013] about 0.1 to about 30 weight percent of a cycloaliphatic
polyester;
[0014] about 0.1 to about 8 weight percent of a polyolefin;
[0015] wherein the molded or extruded composition has a
transmission of about 15% to about 65% at a thickness of 2.0 mm
according ASTM D-1003; and wherein all weight percentages are based
on the weight of the total composition.
[0016] The inventors have discovered that polyolefins are
especially suited for reducing the transparency of blends of
aromatic polycarbonate and cycloaliphatic polyester while improving
the low temperature impact strength of those blends compared to
formulations relying on inorganic pigments for translucency. While
polyolefins have sometimes been employed as impact modifiers in
polycarbonate compositions, it should be noted that other types of
impact modifiers, including methacrylate-butadiene-st- yrene (MBS)
copolymers and styrene-(ethylene-butylene)-styrene block
copolymers, have been found by the present inventors to be
unsuitable for the present compositions because they do not provide
the necessary reduction in transmittance at a similar
concentration. It is therefore especially surprising that the
desirable combination of properties is provided by the blends
comprising polyolefins.
[0017] As used herein, the terms "polycarbonate" and "aromatic
polycarbonate" include compositions having structural units of the
formula 1
[0018] in which at least about 60 percent of the total number of
R.sup.1 groups are aromatic organic radicals and the balance
thereof are aliphatic, alicyclic, or aromatic radicals. Preferably,
R.sup.1 is an aromatic organic radical and, more preferably, a
radical of the formula
--A.sup.1--Y.sup.1--A.sup.2--
[0019] wherein each of A.sup.1 and A.sup.2 is a monocyclic divalent
aryl radical having from 6 to 12 carbon atoms and Y.sup.1 is a
bridging radical having one or two bridging atoms that separate
A.sup.1 from A.sup.2. In an exemplary embodiment, one atom
separates A.sup.1 from A.sup.2. Illustrative, non-limiting examples
of radicals of this type are --O--, --S--, --S(O)--,
--S(O).sub.2--, --C(O)--, methylene, cyclohexyl-methylene,
2-[2,2,1]-bicycloheptylidene, ethylidene, isopropylidene,
neopentylidene, cyclohexylidene, cyclopentadecylidene,
cyclododecylidene, and adamantylidene. The bridging radical Y.sup.1
can be a hydrocarbon group or a saturated hydrocarbon group such as
methylene, cyclohexylidene or isopropylidene.
[0020] Preferred dihydroxy compounds include those in which only
one atom separates A.sup.1 and A.sup.2. As used herein, the term
"dihydroxy compound" includes, for example, bisphenol compounds
having the formula 2
[0021] wherein R.sup.a and R.sup.b each represent a halogen atom or
a monovalent hydrocarbon group and may be the same or different; p
and q are each independently integers from 0 to 4; and X.sup.a
represents one of the groups of the formula 3
[0022] wherein R.sup.c and R.sup.d each independently represent a
hydrogen atom or a monovalent linear or cyclic hydrocarbon group
and R.sup.e is a divalent hydrocarbon group.
[0023] Some illustrative, non-limiting examples of suitable
dihydroxy compounds include dihydric phenols and the
dihydroxy-substituted aromatic hydrocarbons disclosed by name or
formula (generic or specific) in U.S. Pat. No. 4,217,438 to
Brunelle et al. A nonexclusive list of specific examples of the
types of bisphenol compounds includes the following:
1,1-bis(4-hydroxyphenyl)methane; 1,1-bis(4-hydroxyphenyl)ethane;
2,2-bis(4-hydroxyphenyl)propane (hereinafter "bisphenol A" or
"BPA"); 2,2-bis(4-hydroxyphenyl)butane; 2,2-bis(4-hydroxyphenyl)
octane; 1,1-bis(4-hydroxyphenyl)propane;
1,1-bis(4-hydroxyphenyl)-n-butane;
bis(4-hydroxyphenyl)phenylmethane;
2,2-bis(4-hydroxy-1-methylphenyl) propane;
1,1-bis(4-hydroxy-t-butylphenyl)propane; bis(hydroxyaryl)alkanes
such as 2,2-bis(4-hydroxy-3-bromophenyl)propane;
1,1-bis(4-hydroxyphenyl)- cyclopentane; and
bis(hydroxyaryl)cycloalkanes such as
1,1-bis(4-hydroxyphenyl)cyclohexane; and the like, as well as
combinations comprising at least one of the foregoing.
[0024] Aromatic polycarbonate resins typically are prepared by
reacting the dihydroxy compound with a carbonate precursor, such as
phosgene, a haloformate or a carbonate ester and generally in the
presence of an acid acceptor and a molecular weight regulator.
These aromatic polycarbonates can be manufactured by known
processes, such as, for example, by reacting a dihydroxy compound
with a carbonate precursor, in accordance with methods set forth in
the literature including the interfacial polymerization and melt
polymerization processes. Generally in the melt polymerization
process, the dihydroxy compound is reacted with a diester carbonate
such as diphenyl carbonate, whereas in the interfacial
polymerization the dihydroxy compound is reacted with a carbonyl
chloride such as phosgene.
[0025] It is also possible to employ aromatic polycarbonates
resulting from the polymerization of two or more different dihydric
phenols or a copolymer of a dihydric phenol with a glycol or with a
hydroxy- or acid-terminated polyester or with a dibasic acid or
with a hydroxy acid or with an aliphatic diacid in the event a
carbonate copolymer rather than a homopolymer is desired for use.
Generally, useful aliphatic diacids have from 2 to about 40
carbons. A preferred aliphatic diacid is dodecanedioic acid.
Polyarylates and polyester-carbonate resins or their blends can
also be employed. Branched polycarbonates are also useful, as well
as blends comprising a linear polycarbonate and a branched
polycarbonate. The branched polycarbonates may be prepared by
adding a branching agent during polymerization.
[0026] These branching agents are well known and may comprise
polyfunctional organic compounds containing at least three
functional groups, which may be hydroxyl, carboxyl, carboxylic
anhydride, haloformyl and mixtures comprising at least one of the
foregoing. Specific examples include trimellitic acid, trimellitic
anhydride, trimellitic trichloride, tris-p-hydroxy phenyl ethane,
isatin-bis-phenol, tris-phenol TC
(1,3,5-tris((p-hydroxyphenyl)isopropyl)benzene), tris-phenol PA
(4(4(1,1-bis(p-hydroxyphenyl)-ethyl) alpha,alpha-dimethyl
benzyl)phenol), 4-chloroformyl phthalic anhydride, trimesic acid
and benzophenone tetracarboxylic acid, and the like. The branching
agents may be added at a level of about 0.05 to about 2.0 weight
percent. Branching agents and procedures for making branched
polycarbonates are described in U.S. Pat. Nos. 3,635,895 and
4,001,184. All types of polycarbonate end groups are contemplated
as being within the scope of the present invention.
[0027] Preferred aromatic polycarbonates are based on bisphenol A,
in which each of A.sup.1 and A.sup.2 is p-phenylene and Y.sup.1 is
isopropylidene. Preferably, the weight average molecular weight of
the polycarbonate is about 5,000 to about 200,000, more preferably
about 10,000 to about 100,000 and still more preferably about
15,000 to about 35,000.
[0028] The aromatic polycarbonate may be present at about 60 to
about 99.8 weight percent, based on the total weight of the
composition, with about 85 to about 98 weight percent being
preferred, and about 90 to about 97.5 weight percent being more
preferred.
[0029] The cycloaliphatic polyester resin comprises a polyester
having repeating units of the formula 4
[0030] where at least one R.sup.f or R.sup.g is a cycloalkyl
containing radical.
[0031] The polyester is a condensation product where R.sup.f is the
residue of an aryl, alkane or cycloalkane containing diol having 6
to 20 carbon atoms or chemical equivalent thereof, and R.sup.g is
the decarboxylated residue derived from an aryl, aliphatic or
cycloalkane containing diacid of 6 to 20 carbon atoms or chemical
equivalent thereof with the proviso that at least one R.sup.f or
R.sup.g is cycloaliphatic. Preferred polyesters of the invention
will have both R.sup.f and R.sup.g cycloaliphatic.
[0032] The present cycloaliphatic polyesters are condensation
products of aliphatic diacids, or chemical equivalents and
aliphatic diols, or chemical equivalents. The present
cycloaliphatic polyesters may be formed from mixtures of aliphatic
diacids and aliphatic diols but must contain at least 50 mole % of
cyclic diacid and/or cyclic diol components, the remainder, if any,
being linear aliphatic diacids and/or diols. The cyclic components
are necessary to impart good rigidity to the polyester and to allow
the formation of transparent blends due to favorable interaction
with the polycarbonate resin.
[0033] The polyester resins are typically obtained through the
condensation or ester interchange polymerization of the diol or
diol equivalent component with the diacid or diacid chemical
equivalent component.
[0034] R.sup.f and R.sup.g are preferably cycloalkyl radicals
independently selected from the following formulas: 5
[0035] The preferred cycloaliphatic radical R.sup.g is derived from
the 1,4-cyclohexyl diacids and most preferably greater than 70 mole
% thereof in the form of the trans isomer. The preferred
cycloaliphatic radical R.sup.f is derived from the 1,4-cyclohexyl
primary diols such as 1,4-cyclohexyl dimethanol, most preferably
more than 70 mole % thereof in the form of the trans isomer.
[0036] Other diols useful in the preparation of the polyester
resins of the present invention are straight chain, branched, or
cycloaliphatic alkane diols and may contain from 2 to 20 carbon
atoms. Examples of such diols include but are not limited to
ethylene glycol; propylene glycol, i.e., 1,2- and 1,3-propylene
glycol; butanediol, i.e. 1,3- and 1,4-butanediol; diethylene
glycol; 2,2-dimethyl-1,3-propane diol; 2-ethyl, 2-methyl,
1,3-propane diol; 1,3- and 1,5-pentane diol; dipropylene glycol;
2-methyl-1,5-pentane diol; 1,6-hexane diol; dimethanol decalin,
dimethanol bicyclo octane; 1,4-cyclohexane dimethanol and
particularly its cis- and trans-isomers;
2,2,4,4-tetramethyl-1,3-cycl- obutanediol (TMCBD), triethylene
glycol; 1,10-decane diol; and mixtures of any of the foregoing.
Preferably a cycloaliphatic diol or chemical equivalent thereof and
particularly 1,4-cyclohexane dimethanol or its chemical equivalents
are used as the diol component. Chemical equivalents to the diols
include esters, such as dialkylesters, diaryl esters and the
like.
[0037] When using cycloaliphatic diol components, a mixture of cis-
and trans isomers may be employed, the ratio ranging from about 1:1
to about 1:5, and further a high trans isomer content (>70%) is
most preferred. Mixtures of diols or chemical equivalents of the
diols including esters and ethers, such as dialkyl esters, diaryl
esters, and the like can also be useful.
[0038] The diacids useful in the preparation of the aliphatic
polyester resins of the present invention preferably are
cycloaliphatic diacids. This is meant to include carboxylic acids
having two carboxyl groups each of which is attached to a saturated
carbon. Preferred diacids are cycloaliphatic or bicycloaliphatic
diacids having from 6 to 20 carbon atoms, for example
1,4-cyclohexanedicarboxylic acid and especially is
trans-1,4-cyclohexanedicarboxylic acid or chemical equivalent.
Other cycloaliphatic acids include decahydronaphthalene
dicarboxylic acid, norbornene dicarboxylic acids, bicyclooctane
dicarboxylic acids. Mixtures of cycloaliphatic diacids and linear
aliphatic diacids are also useful provided the polyester has at
least one monomer containing a cycloaliphatic ring. Illustrative
examples of linear aliphatic diacids are succinic acid, adipic
acid, dimethyl succinic acid, and azelaic acid.
[0039] Cyclohexanedicarboxylic acids and their chemical equivalents
can be prepared, for example, by the hydrogenation of cycloaromatic
diacids and corresponding derivatives such as isophthalic acid,
terephthalic acid or naphthalene dicarboxylic acids in a suitable
solvent such as water or acetic acid at room temperature and at
atmospheric pressure using suitable catalysts such as rhodium
supported on a suitable carrier of carbon or alumina. See,
Friefelder et al., Journal of Organic Chemistry, volume 31, pages
3438 ff. (1966); and U.S. Pat. Nos. 2,675,390 and 4,754,064. They
may also be prepared by the use of an inert liquid medium in which
a phthalic acid is at least partially soluble under reaction
conditions and a catalyst of palladium or ruthenium in carbon or
silica. See, U.S. Pat. Nos. 2,888,484 and 3,444,237.
[0040] Typically, during hydrogenation, two or more isomers are
obtained in which the carboxylic acid groups are in cis- or
trans-positions. The cis- and trans-diastereomers can be separated
by crystallization with or without a solvent, for example,
n-heptane, or by distillation. The cis-isomer tends to blend
better; however, the trans-diastereomer has higher melting and
crystallization temperatures and is especially preferred. Mixtures
of the cis- and trans-diastereomers are useful herein as well, and
preferably when such a mixture is used, the trans-isomer will
comprise at least about 70 parts by weight and the cis-isomer will
comprise the remainder based upon 100 parts by weight of cis- and
trans-isomers combined. A mixture of diastereomers or more than one
diacid may be used in the cycloaliphatic polyester resins of this
invention.
[0041] Chemical equivalents of these diacids include esters, alkyl
esters (e.g. dialkyl esters), diaryl esters, anhydrides, acid
chlorides, acid bromides, salts, and the like. The preferred
chemical equivalents comprise the dialkyl esters of the
cycloaliphatic diacids, and the most preferred chemical equivalent
comprise the dimethyl ester of the acid, particularly
dimethyl-trans-1,4-cyclohexanedicarboxylate.
[0042] Dimethyl-1,4-cyclohexanedicarboxylate can be obtained by
ring hydrogenation of dimethyl terephthalate, and two diastereomers
having the carboxylic acid groups in the cis- and trans-positions
are obtained. The diastereomers can be separated, the trans-isomer
being especially preferred. Mixtures of the isomers are suitable as
explained above and preferably in the ratios as explained
above.
[0043] A preferred cycloaliphatic polyester is
poly(cyclohexane-1,4-dimeth- ylene cyclohexane-1,4-dicarboxylate)
also referred to as
poly(1,4-cyclohexane-dimethanol-1,4-dicarboxylate) (PCCD) which has
the formula: 6
[0044] With reference to the previously set forth general formula,
for PCCD, R.sup.f is derived from 1,4 cyclohexane dimethanol; and
R.sup.g is a cyclohexane ring derived from cyclohexanedicarboxylate
or a chemical equivalent thereof. The favored PCCD has a cis/trans
formula
[0045] Preferred cycloaliphatic polyesters will have weight average
molecular weights (determined by gel permation chromatography using
polystyrene standards) of about 30,000 to about 150,000 atomic mass
units (amu), with about 60,000 to about 100,000 amu being
preferred, and about 65,000 to about 95,000 amu being more
preferred. Preferred cycloaliphatic polyesters will also have
viscosities of about 500 to about 25,000 poise, with about 1,000 to
about 20,000 poise being preferred, and about 2,000 to about 4,000
poise being more preferred.
[0046] The preferred aliphatic polyesters used in the present
transparent/translucent molding compositions have a glass
transition temperature (Tg) which is above 50.degree. C., more
preferably above 80.degree. C. and most preferably above about
100.degree. C.
[0047] Cycloaliphatic polyesters are commercially available from,
for example, Eastman Chemical. Alternatively, cycloaliphatic
polyesters can be synthesized following the teachings of, for
example, U.S. Pat. Nos. 2,465,319, 5,986,040, and 6,084,055. The
reaction is generally run in the presence of a suitable catalyst,
such as tetraisopropyl titanate or tetrakis(2-ethyl hexyl)titanate,
in a suitable amount, typically about 50 to 200 ppm of titanium
based upon the final product.
[0048] The cycloaliphatic polyester may be present at about 0.1 to
about 30 weight percent, based on the total weight of the
composition, with about 1 to about 15 weight percent being
preferred, and about 1 to about 10 weight percent being more
preferred.
[0049] Polyolefins suitable for the composition include
homopolymers and copolymers. Preferred polyolefins include those
derived from monomers containing from 2 to about 10 carbon atoms.
Some illustrative non-limiting examples of these polyolefins
include polyethylene, polypropylene, polybutylene, polyhexene,
polyisobutylene, and ethylenepropylene copolymer.
[0050] In one embodiment the polyolefin is free of fluoride
substituents. In another embodiment, the polyolefin is free of all
halide substituents (that is, all substituents from Group VIIA of
the periodic table).
[0051] Methods for the preparation of the polyolefins are
abundantly described in the literature and are well known to those
skilled in the art. Polyethylene, for example, can be prepared by
various procedures using cationic, anionic or free radical
initiating catalysts, with conditions varied to produce a range of
molecular weights and densities and various degrees of branching or
non-branching. In one procedure, which involves free radical
initiation, ethylene gas is polymerized in the presence of a
peroxide initiating catalyst at a pressure between 15,000 and
40,000 pounds per square inch (psi) and a temperature between
100.degree. C. and 200.degree. C. to produce a relatively low
density polymer, for example 0.90 to 0.94 g/cm.sup.3.
[0052] The polyethylene can also be prepared by low pressure
processes to obtain a polymer of higher molecular weight and a
higher density. In one such procedure, known as the Phillips
process, ethylene is contacted in an inert solvent slurry of a
catalyst such as chromium oxide supported on silica-aluminum, at
pressures of 400 to 500 psi and temperatures of 130.degree. to
170.degree. C., followed by extraction of the polymer with hot
solvent and purification, to produce a polyethylene product having
a density between 0.96 to 0.97 g/cm.sup.3. Still other procedures
are possible, such as emulsion polymerization in aqueous media in
the presence of a peroxy compound, as well as suspension
polymerization at low temperatures using a silver salt-peroxide
redox system.
[0053] Another suitable polyolefin is polypropylene, a common
commercial form of which is isotactic polypropylene. Such polymers
can be prepared by anionically initiated reactions using Ziegler
type catalysts, for example titanium halide such as TiCl.sub.4 in
combination with an organometallic co-catalyst such as trialkyl
aluminum halide. Polymerization proceeds readily at temperatures
between 25.degree. C. and 100.degree. C. to yield a polymer in the
form of a slurry of insoluble granular powder.
[0054] Copolymers of ethylene and propylene can be prepared using
procedures similar to those for polyethylene and other polyolefins;
for instance by the polymerization reaction of a mixture of
ethylene and propylene in the presence of a Ziegler type catalyst
or by free-radical initiation under high pressures.
[0055] Examples of higher polyolefins are polymers based on
2-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, and the like.
They can be prepared by known procedures including those described
in Encyclopedia of Polymer Science and Technology, John Wiley &
Sons, Inc., Vol. 9, pp. 440-460, 1965, incorporated herein by
reference.
[0056] Particularly preferred polyolefins include linear low
density polyethylenes (LLDPE). Linear low density polyethylenes are
well known materials that are available commercially, for example,
from Exxon under the tradename ESCORENE.RTM. or from Dow Chemicals
under the tradename DOWLEX.RTM.. Alternatively, they may readily be
prepared by state of the art polymerization processes such as those
described in U.S. Pat. Nos. 4,128,607, 4,354,009, 4,076,698, and
European Patent Application No. 4645 (published Oct. 17, 1979).
These polymers have a density between about 0.92 and 0.96
gram/milliliter. These linear low density polyethylene polymers are
actually co-polymers of ethylene and a minor amount, typically less
than 20 mole percent, preferably less than 15 mole percent, of an
alpha olefin of 3 to 18 carbon atoms, preferably 3 to 10 carbon
atoms, more preferably 4 to 8 carbon atoms. These linear low
density polyethylenes are distinguishable from polymers such as
high pressure low density polyethylene and high density
polyethylene made from Zeigler catalyst systems in that they are
substantially free of side chain branching, having a controlled
concentration of simple side chain branching as opposed to random
branching.
[0057] The preferred linear low density polyethylene co-polymers
are prepared from ethylene and one or more alpha olefins selected
from the group consisting of propylene, 1-butene, 1-pentene,
4-methyl-1-pentene, 1-hexene, and 1-octene, most preferably
1-butene and 1-octene. Polymers of desired density may be obtained
by controlling the co-polymerization ratio of ethylene to alpha
olefin during co-polymerization. The addition of increasing amounts
of the co-monomers to the co-polymers results in lowering the
density of the co-polymer.
[0058] The melt indices of useful linear low density polyethylenes
may vary widely. However, when using linear low density
polyethylene derived from ethylene and a short chain monomer, for
example 1-butene, it is preferred that such linear low density
polyethylenes have melt indices of at least 5, preferably at least
10, more preferably at least about 12 gram/10 minutes. With linear
low density polyethylenes derived from longer chain monomers, for
example 1-octene, the melt indices of the linear low density
polyethylenes may be even lower.
[0059] In general, the co-polymerization of linear low density
polyethylene can take place in either a gas phase fluidized bed
reaction or liquid phase solution process reactor, preferably the
former, at pressures ranging from normal to 5,000 psi, preferably
less than 1,000 psi and at temperatures of from 20.degree. C. to
310.degree. C., preferably 30.degree. C. to 115.degree. C. in the
presence of a suitable high activity catalysts. Typical catalyst
systems comprise a transition metal complex catalyst, preferably
comprising at least one compound of a transition element of group
IVB, VB, or VIB having a halide and/or hydrocarbon group attached
to said transition metal and a reducing component such as a metal
halide or a compound having metal attached directly to carbon, for
example metal alkyl. Highly satisfactory catalyst systems comprise
(a) a Group IVB or Group VB metal compound bearing at least one
halogen atom and (b) a lithium or aluminum or magnesium alkyl
compound, especially LiAl(hydrocarbon).sub.4. Such systems include,
for example, TiCl.sub.4 and LiAl(alkyl).sub.4, VOCl.sub.3 and
Li(alkyl), MoCl.sub.3 and Al(alkyl).sub.3, TiCl.sub.4 and
(alkyl)MgBr, and the like. Catalyst systems such as these as well
as other useful catalysts systems are disclosed in U.S. Pat. Nos.
4,128,607, 4,354,009, 4,076,698, and European Patent Application
No. 4645. Such catalyst systems are used in a molar ratio of
ethylene to catalyst of about 35,000:1 to about 400,000:1.
[0060] The preferred linear low density polyethylene co-polymers so
produced have an unsaturated group content of less than or equal to
about 1, and preferably from about 0.1 to about 0.3 carbon-carbon
double bonds per 1000 carbon atoms and a n-hexane extractables
content (at 50.degree. C.) of less than about 3, preferably less
than about 2, weight percent. Preferred materials include those
made by the Unipol process, which is described in Chem. Eng., Dec.
3, 1979, pages 80-85.
[0061] Highly preferred polyolefins include polyolefin plastomers.
Polyolefin plastomers are substantially linear
ethylene/alpha-olefin copolymers. The alpha-olefin monomer
preferably has from 4 to 8 carbon atoms. Polyolefin plastomers are
characterized by a density of about 0.88 to about 0.92 g/ml, a
molecular weight distribution M.sub.w/M.sub.n not greater than
about 4 and a melt flow ratio I.sub.10/I.sub.2 of not less than
about 7. The molecular weight distribution M.sub.w/M.sub.n is a
ratio of the weight average molecular weight to the number average
molecular weight of the copolymer, while the melt flow ratio
I.sub.10/I.sub.2 is a ratio of the melt index at the 10 kg loading
to the melt index at the 2.16 kg loading at 190.degree. C.
according to ASTM D1238. The polyolefin plastomers are
distinguished from other polyolefins, including LLDPE, in Mw/Mn
and/or I.sub.10/I.sub.2.
[0062] Suitable polyolefin plastomers include those sold by
ExxonMobil under the tradename EXACT.RTM. as, for example, the
ethylene/butene copolymer EXACT.RTM. 4033 having Mw/Mn of about 1.8
and the ethylene/octene copolymer EXACT.RTM. 8201 having Mw/Mn of
about 2.7; and by Dow Chemical Company under the tradename
AFFINITY.RTM. as, for example, the ethylene/octene copolymer
AFFINITY.RTM. PL1880.
[0063] Suitable polyolefins include graft copolymers of any of the
above polyolefins with unsaturated acids or acid derivatives,
including acrylic acid, maleic acid, maleic anhydride, itaconic
acid, and the like. These acid-modified polyolefins may be prepared
by known methods including those described in, for example, U.S.
Pat. Nos. 3,404,135 to W. Tietz, 3,461,108 to Heilman et al., and
3,560,456 to Hazen et al. Especially preferred are the
acid-modified polyolefins of linear low density polyethylene and
maleic anhydride (LLDPE-g-MAH), which are commercially available
from, for example, ExxonMobil under the tradename EXXELOR.RTM.
(these materials include maleic anhydride-modified copolymers of
(a) ethylene and butene, or (b) ethylene and octene); and the
acid-modified polyolefin plastomers available from ExxonMobil as,
for example, MDEX 95-2 and MDEX 96-2.
[0064] The total amount of polyolefin may be about 0.1 to about 8
weight percent, based on the total weight of the composition, with
about 0.5 to about 4 weight percent being preferred, and about 1 to
about 2.5 weight percent being more preferred. This total amount of
polyolefin may preferably comprise 0 to about 100 weight percent,
more preferably about 0 to about 50 weight percent, yet more
preferably about 20 to about 40 weight percent, acid-modified
polyolefin, with the remainder being unmodified polyolefin.
[0065] The composition may further comprise a catalyst quencher.
Catalyst quenchers, as used herein, are agents that quench any
residual polymerization catalyst remaining from the synthesis of
the polycarbonate or the cycloaliphatic polyester resin. The
residual catalyst needs to be quenched to prevent any
transesterification reaction between the polycarbonate and the
cycloaliphatic polyester resin. There is no particular limitation
on the structure of the quencher. Suitable transesterification
quenchers include mono-, di-, and tri-hydrogen phosphites and their
metal salts; mono-, di-, and tri-hydrogen phosphates and their
metal salts; mono- and di-hydrogen phosphonates and their metal
salts; pyrophosphates and their metal salts; mixtures comprising at
least one of the foregoing quenchers; and the like. The suitability
of a particular compound for use as a transesterification quencher
and the determination of how much is to be used may be readily
determined by preparing a mixture of the cycloaliphatic polyester
and the aromatic polycarbonate with and without the particular
transesterification quencher and determining the effect on melt
viscosity, gas generation or color stability or the formation of
interpolymer.
[0066] The mono-, di-, and tri-hydrogen phosphites and their metal
salts have the formula
P(OR.sup.1).sub.a(OM.sup.n+.sub.1/n).sub.3-a
[0067] wherein each R.sup.1 is independently C.sub.1-C.sub.12
alkyl, C.sub.1-C.sub.12 aryl, or C.sub.1-C.sub.18 alkylaryl; each M
is independently hydrogen or a metal atom selected from Group IA,
IIA, IB, or IIB of the periodic table; a is 0-2; and n is 1 or 2.
Preferred compounds in this class include phosphorous acid,
H.sub.3PO.sub.3.
[0068] The mono-, di-, and tri-hydrogen phosphates and their metal
salts have the formula
O.dbd.P(OR.sup.1).sub.a(OM.sup.n+.sub.1/n).sub.3-a
[0069] wherein R.sup.1, M, a, and n are as defined for the
phosphites above. Preferred compounds in this class include those
in which a=0 and M is a metal atom selected from Group IB or IIB of
the periodic table. A preferred compound is mono zinc phosphate
(MZP; ZnHPO.sub.4).
[0070] The mono- and di-hydrogen phosphonates and their metal salts
have the formula
P(R.sup.1)(OR.sup.1).sub.b(OM.sup.n+.sub.1/n).sub.2-b
[0071] wherein R.sup.1, M, and n are defined as above, and b=0 or
1.
[0072] The pyrophosphates and their metal salts have the
formula
M.sup.z.sub.xH.sub.yP.sub.qO.sub.3q+1
[0073] wherein M is as defined for the phosphites above, x is 1-12,
y is 1-12, q is 2-10, and z is 1-5, with the proviso that the sum
(xz)+y is equal to q+2. M is preferably a Group IA or IIA metal.
Preferred compounds in this class include Na.sub.3HP.sub.2O.sub.7;
K.sub.2H.sub.2P.sub.2O.sub.7; KNaH.sub.2P.sub.2O.sub.7; and
Na.sub.2H.sub.2P.sub.2O.sub.7. The particle size of the polyacid
pyrophosphate should be less than 75 micrometers, preferably less
than 50 micrometers and most preferably less than 20
micrometers.
[0074] These and other quenchers, including quencher mixtures, are
described, for example, in U.S. Pat. Nos. 4,401,804 to Wooten et
al., 4,532,290 to Jaquiss et al., and 5,354,791 to Gallucci,
5,441,997 to Walsh et al., 5,608,027 to Crosby et al., and
5,922,816 to Hamilton.
[0075] As mentioned above, the determination of how much of a
particular quencher is to be used may be readily determined by
preparing the composition with and without the particular compound
and determining the effect on melt viscosity, gas generation or
color stability or the formation of interpolymer. Typical quencher
amounts are about 0.001 to about 2 weight percent, preferably about
0.005 to about 1 weight percent, more preferably about 0.01 to
about 0.5 weight percent.
[0076] Various other additives may be used alone or in combination.
As used herein, additives may include such materials as whitening
agents, thermal stabilizers, antioxidants, light stabilizers,
plasticizers, colorants, impact modifiers, extenders, antistatic
agents, mold releasing agents, additional resins, blowing agents,
and processing aids. The different additives that can be
incorporated in the compositions are commonly used and known to one
skilled in the art. Illustrative descriptions of such additives may
be found in R. Gachter and H. Muller, Plastics Additives Handbook,
4th edition, 1993.
[0077] Examples of thermal stabilizers include triphenyl phosphite,
tris-(2,6-dimethylphenyl)phosphite, tris-(2,4-di-t-butyl-phenyl)
phosphite, tris-(mixed mono-and di-nonylphenyl)phosphite,
dimethylbenzene phosphonate and trimethyl phosphate. Examples of
antioxidants include
octadecyl-3-(3,5-di-tert-butyl4-hydroxyphenyl)propionate, and
pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]-
. Examples of light stabilizers include
2-(2-hydroxy-5-methylphenyl)benzot- riazole,
2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole and
2-hydroxy-4-n-octoxy benzophenone. Examples of plasticizers include
dioctyl-4,5-epoxy-hexahydrophthalate,
tris-(octoxycarbonylethyl)isocyanur- ate, tristearin and epoxidized
soybean oil. Examples of the antistatic agents include glycerol
monostearate, sodium stearyl sulfonate, and sodium
dodecylbenzenesulfonate. Examples of mold releasing agents include
pentaerythritol tetrastearate, stearyl stearate, beeswax, montan
wax, and paraffin wax. Examples of other resins include but are not
limited to polypropylene, polystyrene, polymethyl methacrylate, and
polyphenylene oxide. Combinations of any of the foregoing additives
may be used. Such additives may be mixed at a suitable time during
the mixing of the components for forming the composition.
[0078] In one embodiment, the composition is substantially free of
inorganic fillers. By this it is meant that the composition
comprises less than 2 weight percent, preferably less than 1 weight
percent, more preferably 0 weight percent, of inorganic fillers.
Inorganic fillers may include particulate fillers, such as barium
sulfate, and fibrous fillers, such as glass fibers. Various other
fillers, including particulate, plate-shaped, and fibrous fillers,
are described, for example, in U.S. Pat. No. 4,763,133 to Takemura
et al. While the composition is generally free of inorganic
materials that function primarily as fillers, it may comprise small
amounts, typically less than about 1 weight percent, preferably
less than about 0.5 weight percent, more preferably less than about
0.25 weight percent, of insoluble whiteners or colorants, which
function primarily to adjust the color of the composition. Such
insoluble colorants are described in R. Gachter and H. Muller,
Plastics Additives Handbook, 4th edition, 1993.
[0079] In an alternative embodiment, inorganic fillers may be
present in an amount that contributes significantly to reducing the
transmission or increasing the haze of the composition.
[0080] The production of the compositions may utilize any of the
blending operations known for the blending of thermoplastics, for
example blending in a kneading machine such as a Banbury mixer or
an extruder. The sequence of addition is not critical but all
components should be thoroughly blended.
[0081] To prepare the resin composition, the components may be
mixed by any known methods. Typically, there are two distinct
mixing steps: a premixing step and a melt mixing step. In the
premixing step, the dry ingredients are mixed together. The
premixing step is typically performed using a tumbler mixer or
ribbon blender. However, if desired, the premix may be manufactured
using a high shear mixer such as a Henschel mixer or similar high
intensity device. The premixing step is typically followed by a
melt mixing step in which the premix is melted and mixed again as a
melt. Alternatively, the premixing step may be omitted, and raw
materials may be added directly into the feed section of a melt
mixing device, preferably via multiple feeding systems. In the melt
mixing step, the ingredients are typically melt kneaded in a single
screw or twin screw extruder, a Banbury mixer, a two roll mill, or
similar device.
[0082] In a preferred embodiment, the composition will have a melt
volume rate measured at 300.degree. C./1.2 kg according to ISO 1133
of about 7 mL/10 minutes to about 13 mL/10 minutes, preferably
about 9 mL/10 minutes to about 12 mL/10 minutes. In another
preferred embodiment, the composition after molding or extruding
will exhibit at least one of (1) a transmission measured on a 2.0
mm thick plaque according to ASTM D1003 of about 15% to about 65%,
preferably about 20% to about 55%, more preferably about 30% to
about 45%; (2) a haze measured on a 2.0 mm thick plaque according
to ASTM D1003 not less than about 90%, preferably not less than
about 95%, more preferably not less than about 98%; (3) a
yellowness index measured for 2.0 mm samples according to ASTM
D1925 not greater than about 35, preferably not greater than about
30, more preferably not greater than about 25; (4) an Izod notched
impact measured at 0.degree. C. according to ASTM D256 of not less
than about 500 J/m, preferably not less than about 700 J/m, more
preferably not less than about 800 J/m; (5) an Izod notched impact
measured at -20.degree. C. according to ASTM D256 of not less than
about 150 J/m, preferably not less than about 200 J/m, more
preferably not less than about 400 J/m; and (6) a Flexplate Impact
energy at break measured at 23.degree. C. and 3.0 millimeter
thickness according to ISO 6603-2 not less than about 100 J,
preferably not less than about 110 J, more preferably not less than
about 115 J.
[0083] The optical properties and impact resistance of the
composition make it suitable for use in a variety of applications
where translucency is preferred to transparency, including, for
example, lighting fixtures, ornaments, and signs. The composition
is particularly well adapted for use in a variety of glazing
applications including, for example, roofs, greenhouses, sun rooms,
swimming pool enclosures, and the like.
[0084] The compositions described above may be used in the
fabrication of translucent sheets. Techniques for the extrusion of
translucent 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
Nissel, 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.
[0085] The invention is further illustrated by the following
non-limiting examples.
EXAMPLES
[0086] The following examples employed the materials listed in
Table 1 according to the formulations listed in Tables 2, 4, and 5.
All amounts are weight percents based on the total weight of the
composition unless otherwise indicated.
[0087] All ingredients were mixed in a ribbon blender and extruded
on a Leistritz twin screw extruder. Samples comprising
polycarbonate and the cycloaliphatic polyester PCCD were extruded
at 285.degree. C. to form pellets while compositions comprising
polycarbonate but no polyester were extruded at 300.degree. C.
Injection molding of the PCCD-containing pellets was performed at
280.degree. C. (mold temperature 80.degree. C.) while pellets with
polycarbonate but no polyester were molded at 300.degree. C. (mold
temperature 90.degree. C.).
1TABLE 1 Properties or Material Trade name/Source Function
Polycarbonate 1 GE Plastics IV = 58-59 ml/g Polycarbonate 2 GE
Plastics IV = 63.2-65.8 ml/g Poly(alpha-olefin) DURASYN .RTM. 166/
Release agent Amoco Tris(2,4-di-t- IRGAFOS .RTM. 168/ Heat
stabilizer butylphenyl)phosphite Ciba-Geigy
Octadecyl-3-(3,5-di-tert- IRGANOX .RTM. 1076/ Antioxidant butyl-4-
Ciba-Geigy hydroxyphenyl)propionate Pentaerythritol tetrakis (3-
SANDOSTAB .RTM. 4020/ Co-stabilizer laurylthiopropionate) Sandoz
(PELTP) Mono zinc phosphate MZP/Berkimpex Catalyst (MZP) France
quencher H.sub.3PO.sub.3 (45% aqueous Phosphorous acid/ Catalyst
solution) Caldic quencher Poly(cyclohexanedimetha PCCD/Eastman
M.sub.w = 91000 nol-1,4- Chemical g/mol (4000
cyclohexanedicarboxylate) poise) Ethylene-based plastomer EXACT
.RTM. 4033/ Plastomer ExxonMobil Maleic acid anhydride MDEX 95-2
and Modified modified ethylene MDEX 96-2/ plastomer copolymer
ExxonMobil BaSO.sub.4 Portaryte X-15/ Inorganic filler/ Ankerpoort
light diffuser TiO.sub.2 (coated) RL-91/Millenium White pigment
Bis(2,4-di-t-butylphenyl) ULTRANOX .RTM. 626/ Co-stabilizer
pentaerythritol GE Specialty diphosphite Chemicals Di-(tert-butyl-
UVITEX .RTM. OB/Ciba- Optical benzoxazolyl thiophene) Geigy
brightener 3,4- Epoxy ERL4221/ Cycloaliphatic
epoxycyclohexylmethyl- Union Carbide epoxy 3,4-
epoxycyclohexylcarbox- ylate 2-(2-hydroxy-5-tert- CYASORB .RTM.
UV5411/ UV-stabilizer octylphenyl)-benzotriazole Cytec
Examples 1 and 2, Comparative Example A
[0088] Examples 1 and 2 and Comparative Example A were prepared
using the materials specified in Table 1 according to the
formulations listed in Table 2.
[0089] Optical properties (transmission and haze measured according
ASTM D1003; yellowness index measured according ASTM D1925) of 2.0
mm thick plaques were measured on a Gardner XL-835 Colorimeter.
Notched Izod impact strengths at 23.degree. C., 0.degree. C., and
-20.degree. C. were measured on molded impact bars (3.2 mm thick)
according to ASTM D256. Flex plate impact was measured at
23.degree. C. on 3.0 millimeter thick plaques according to ISO
6603-2; reported values are the average of 5 test samples for the
impact tests. From the granulate the melt volume rate (MVR) was
measured according ISO 1133 (300.degree. C./1.2 kg) in units of
ml/10 min. Glass transition temperature (T.sub.g) of granulate was
measured on a Perkin-Elmer DSC-7 differential scanning calorimeter.
Results are presented in Table 2.
2 TABLE 2 Comparative Example 1 Example 2 Example A COMPOSITIONS
Polycarbonate 1 87.05 77.05 89.4 Additives (release agent, 0.8 0.8
-- stabilizer, antioxidant) Co-Stabilizer (PELTP) 0.1 0.1 -- EXACT
.RTM. 4033 1.5 1.5 -- MDEX 96-2 0.5 0.5 -- PCCD 4000 poise 10 20 --
Catalyst Quencher (MZP) 0.05 0.05 -- Color masterbatch containing:
Polycarbonate 2 -- -- 8.517 Co-stabilizer -- -- 0.106 Optical
brightener -- -- 0.027 Cycloaliphatic Epoxy -- -- 0.106 UV
stabilizer (UV5411) -- -- 0.106 Barium Sulfate (BaSO.sub.4) -- --
1.59 Titanium Dioxide (TiO.sub.2) -- -- 0.148 PROPERTIES
Transmission 32.9 36.9 30.3 Yellowness Index (YI) 33.0 28.9 31.4
Haze 100 100 100 T.sub.g (.degree. C.) 138 129 151 Izod Notched
Impact Strength 816 863 900 at 23.degree. C. (J/m) Izod Notched
Impact Strength 808 809 206 at 0.degree. C. (J/m) Izod Notched
Impact Strength 658 154 165 at -20.degree. C. (J/m) Melt Volume
Rate at 300.degree. C., 1.2 9.3 11.5 5.69 kg (mL/10 min) Flexplate
Impact Maximum 8865 8816 8697 Force (N) Flexplate Impact Energy at
109.0 113.5 83.6 Max. (J) Flexplate Impact Energy at 113.5 119.7
91.0 Break (J) Flexplate Impact Deflection at 23.1 23.3 20.7 Break
(mm)
[0090] Samples of all 3 formulations exhibited ductile failure
performance in flex plate impact testing and Izod notched impact
testing at 23.degree. C. Impact testing at 0.degree. C. showed
brittle failure for the Comparative Example A while Examples 1 and
2 still exhibited ductile performance.
[0091] The results in Table 2 illustrate some of the advantages of
the inventive compositions. Versus Comparative Example A, Examples
1 and 2 exhibit higher low-temperature impact strength, higher
Flexplate impact strength, and higher melt volume rate (i.e., lower
viscosity) while having a similar light transmittance.
[0092] Plaques molded of the formulations of Examples 1 and 2 and
Comparative Example A were tested for its artificial weathering
performance in a Xenon 1200 LM apparatus according to ISO 4892 part
2. Values are normalized to the Yellowness Index value (YI-value)
at 0 hours (presented in Table 2) and listed in Table 3 as delta YI
values. The results show that the PC/CCD/plastomer blends are less
yellowing than the comparative example, which contains BaSO.sub.4,
TiO.sub.2, and a UV-stabilizer.
3 TABLE 3 delta YI value Exposure Comparative hours Example A
Example 1 Example 2 0 0 0 0 45 1.6 1.8 1.5 69 3.3 2.9 2.3 159 8.9
6.4 5 249 13.6 8.9 7.6 415 17 12.6 11.2 891 22.2 16.9 15.5
Examples 3-7
[0093] Examples 3-7 were prepared using the materials specified in
Table 1 according to the formulations listed in Table 4. Properties
were measured as described above, and results are presented in
Table 4.
4 TABLE 4 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 COMPOSITIONS Polycarbonate
1 87.1 87.05 93.05 88.05 83.05 Additives (antioxidant + 0.8 0.8 0.8
0.8 0.8 heat stabilizer + release agent) PELTP 0.1 0.1 0.1 0.1 0.1
Mono zinc phosphate -- 0.05 0.05 0.05 0.05 PCCD (4000 Poise) 10 10
5 10 15 EXACT .RTM. 4033 1.5 1.5 0.75 0.75 0.75 MDEX 95-2 0.5 0.5
0.25 0.25 0.25 PROPERTIES Izod Notched Impact at 852.0 823.5 857.5
827.5 848.5 23.degree. C. (J/m) Izod Notched Impact at 797.0 786.0
801.0 590.0 207.5 0.degree. C. (J/m) Izod Notched Impact at 683.5
748.1 594.5 211.0 164.5 -10.degree. C. (J/m) MVR at 300.degree.
C./1.2 kg 8.8 11.1 9.0 10.9 12.6 (mL/10 min) Transmission 30.9 33.3
41.6 39.3 45.9 Haze 100.3 100.4 99.9 100.1 99.8 Yellowness Index
(YI) 50.9 27.6 24.7 27.8 19.0
[0094] From the results in Table 4 it can be seen that an
unquenched sample (Example 3) is yellower than a quenched one
(Example 4). Examples 5-7 show that higher polyester amounts are
associated with lower viscosities (manifested as higher MVR). Also,
at a constant level of plastomers, higher polyester amounts are
associated with lower impact resistance at 0.degree. C. and
-20.degree. C.
Comparative Examples B AND C, Examples 8-12
[0095] In Table 5 compositions and properties are presented for
polycarbonate and polycarbonate/polyester blends comprising barium
sulfate (BaSO.sub.4) as a light-diffusing agent (Comparative
Examples B and C) as well as for polycarbonate/polyester blends
comprising polyolefins. Comparative Examples B and C comprising
barium sulfate have low impact values at 0.degree. C., -10.degree.
C., and -20.degree. C. compared to Examples 8-12 comprising
polyolefins. Use of phosphorous acid (H.sub.3PO.sub.3; Example 9)
instead of mono zinc phosphate (MZP; Example 8) as a catalyst
quencher reduces yellowing without affecting the impact
strength.
5 TABLE 5 Comp. Comp. Ex. B Ex. C Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12
COMPOSITIONS Polycarbonate 1 89.4 78.94 88 87.99 93.44 92.94 92.44
Antioxidant -- 0.3 0.3 0.3 0.3 0.3 0.3 Heat stabilizer -- 0.1 0.1
0.1 0.1 0.1 0.1 Mono zinc phosphate -- -- 0.05 -- -- -- --
H.sub.3PO.sub.3 (45% in water) -- 0.06 -- 0.06 0.06 0.06 0.06 PCCD
resin (4000 poise) -- 10 10 10 5 5 5 EXACT .RTM. 4033 -- -- 1.05
1.05 0.7 1.05 1.4 MDEX 95-2 -- -- 0.45 0.45 0.3 0.45 0.6 TiO.sub.2
(coated) -- -- 0.05 0.05 0.1 0.1 0.1 Color masterbatch containing:
Polycarbonate 2 8.517 8.517 -- -- -- -- -- TiO.sub.2(coated) 0.148
0.148 -- -- -- -- -- BaSO.sub.4 1.59 1.59 -- -- -- -- --
UV-stabilizer 0.106 0.106 -- -- -- -- -- Epoxy 0.106 0.106 -- -- --
-- -- Whitening agent 0.027 0.027 -- -- -- -- -- Co-stabilizer
0.106 0.106 -- -- -- -- -- PROPERTIES Izod Notched Impact 900.0
142.0 857.5 850.5 888.5 824.5 815.0 (23.degree. C.) Izod Notched
Impact at 205.5 -- 846.0 836.0 843.5 797.0 816.5 0.degree. C.(J/m)
Izod Notched Impact at -- -- 816.9 820.5 850.0 793.0 791.5
-10.degree. C. (J/m) Izod Notched Impact at 165.5 116.5 184.5 204.0
197.0 452.5 765.5 -20.degree. C. (J/M) MVR at 300.degree. C./1.2 kg
5.7 12.5 9.9 11.1 10.0 10.2 10.0 (ml/10 min) Transmission (2.0 mm)
30.3 28.2 35.4 39.1 35.1 32.7 30.2 Haze (2.0 mm) 100.1 100.2 100.3
100.3 100.3 100.3 100.3 Yellowness Index (YI) 31.5 41.0 31.5 24.6
28.8 30.3 31.5
[0096] While preferred embodiments have been shown and described,
various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the present invention has been
described by way of illustration and not limitation.
[0097] All cited patents and other references are incorporated
herein by reference in their entirety.
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