Note: Descriptions are shown in the official language in which they were submitted.
Mo-3643
MD-91-9-PL
COLOR-STABLE AND UV-RESISTANT POLYCARBONATE
AND POLYESTER COMPOSITIONS
Field of the Invention
The invention relates to thermoplastic molding
compositions and more particularly to UV stabilized
compositions based on polycarbonate, polyestercarbonate or
polyesters.
SUMMARY OF THE INVENTION
The present invention resides in the finding that a
thermoplastic molding composition which contains a
polycarbonate and/or an aromatic polyester resin and/or a
polyestercarbonate resin and a particular UV stabilizer is
rendered improved color stability upon the incorporation
therewith of a phenolic compound and an organophosphorous
compound. The composition is suitable for the preparation of
color stable, UV resistant molded articles.
BACKGROUND OF THE INVENTION
The art has long recognized the utility of bis-benzo-
triazole compounds as UV-stabilizing agents in polycarbonate
molding compositions. U.S. Patent 4,948,666 disclosed the
efficacy of such compounds in polycarbonate-based structures.
Organophosphorous compounds have been disclosed to impart
thermal stability to thermoplastic resins. Such compounds have
been disclosed to aid processing and thus prevent thermal
degradation and deterioration of the physical properties of
polymeric resins. Organophosphorous compounds have also been
disclosed to help prevent oxidative degradation which can lead
to yellowing of the resin during high temperature processing or
upon aging at elevated temperatures. Stabilized polycarbonate
35052AP1030
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compositions containing organophosphorous compounds are
described in the following U.S. Patents: 4,888,371; 3,509,091;
4,076,686; 4,102,859; ~,276,233; 4,367,303 and 4,555,540. Both
natural and pigmented formulations are imparted improved
stability upon the incorporation of organophosphorous
compounds.
Of particular relevance in the present context is U.S.
Patent 4,371,647 which disclosed a phosphite entailed in the
present invention to stabilize resinous compositions. The
incorporation of this and similar phosphites is said to enhance
the resistance of certain resins to deterioration resulting
from exposure to heat and light. Polycarbonate resins are
listed among the resins thus effected. Also listed as suitable
resins are polyacrylic acid esters and acrylonitrile/butadiene/
styrene terpolymers.
Hindered phenols have been recognized to impart stability
to polycarbonate compositions as was reported in U.S. Patents
4,581,397 and 4,563,516.
DETATLED DESCRIPTION OF THE INVENTION
The resinous component of the thermoplastic molding
composition of the invention is at least one member selected
from the group consisting of polycarbonate resins, aromatic
polyester resins and polyestercarbonate resins.
Aromatic polycarbonates within the scope of the present
invention are homopolycarbonates and copolycarbonates and
mixtures thereof.
The polycarbonates generally have a we`ight average
molecular weight of 10,000-200,000, preferably 20,000-80,000
and their melt flow rate, per ASTM D-1238 at 300C, is about 1
to about 65 gm/10 min., preferably about 2-15 gm/10 min. They
may be preparecl, for example, by the known diphasic interface
process from a carbonic acid derivative such as phosgene and
dihydroxy compounds by polycondensation (see German Offen-
legungsschriften 2,063,050; 2,063,052; 1,570,703; 2,211,956;
Mo-3643
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2,211,957 and 2,248,817; French Patent 1,561,518; and the
monograph H. Schnell~ "Chemistry and Physics of Poly-
carbonates", Interscience Publishers, New York, New York, 1964,
all incorporated herein by reference).
In the present context, dihydroxy compounds suitable for
the preparation of the polycarbonates of the inventor conform
to the structural formulae (1) or (2).
r ~ ~ H0 H0
~A)~_ t 011 ~
tZ) d (Z) f
(Z) d (z) f
5
wherein
A denotes an alkylene group with 1 to 8 carbon atoms, an
alkylidene group with 2 to 8 carbon atoms, a cycloalkylene
group with 5 to 15 carbon atoms, a cycloalkylidene group with 5
to 15 carbon atoms, a carbonyl group, an oxygen atom, a sulfur
atom, -SO- or -S02- or a radical conforming to
CH3
-C ~ CH3
e and g both denote the number O to 1;
Z denotes F, Cl, Br or C1-C4-alkyl and if several Z radicals
are substituents in one aryl radical, they may be identical or
different from one another;
d denotes an integer of from O to 4; and ::~
f denotes an integer of from O to 3.
Mo-3643
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Among the dihydroxy compounds useful in the practice of
the invention are hydroquinone, resorcinol, bis-(hydroxy-
phenyl)-alkanes, bis-(hydroxyphenyl)-ethers, bis-(hydroxy-
phenyl)-ketones, bis-(hydroxyphenyl)-sulfoxides, bis-(hydroxy-
5 phenyl)-sulfides, bis-(hydroxyphenyl)-sulfones, and ~,~-bis-
(hydroxyphenyl)-diisopropyl-benzenes, as well as their
nuclear-alkylated compounds. These and further suitable
aromatic dihydroxy compounds are described, for example, ;n
U.S. Patents 3,028,356; 2,999,835; 3,148,172; 2,991,273;
3,271,367; and 2,999,846, all incorporated herein by reference.
Further examples of suitable bisphenols are 2,2-bis-
(4-hydroxy-phenyl~-propane (bisphenol A), 2,4-bis-(4-hydroxy-
phenyl)-2-methyl-butane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane,
~,~'-bis-(4-hydroxyphenyl]-p-diisopropylbenzene, 2,2-bis-
(3-methyl-4-hydroxyphenyl)-propane, 2,2-bis-(3-chloro-4-
hydroxyphenyl)-propane, bis-(3,5-dimethyl-4-hydroxyphenyl)-
methane, 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane,
bis-(3,5-dimethyl-4-hydroxyphenyl)-sulfide, bis-(3,5-dimethyl-
4-hydroxyphenyl)-sulfoxide, bis-(3,5-dimethyl-4-hydroxyphenyl)-
sulfone, hydroxy-benzophenone, 2,4-bis-(3,5-dimethyl-4-hydroxy-
phenyl)-cyclohexane, ~,~'-bis-(3,5-dimethyl-4-hydroxyphenyl)-
p-diisopropylbenzene and 4,4'-sulfonyl diphenol.
Examples of particularly preferred aromatic bisphenols are
2,2,-bis-(4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dimethyl-4-
hydroxyphenyl)-propane and 1,1-bis-(4-hydroxyphenyl)-cyclo-
hexane.
The most preferred bisphenol is 2,2-bis-(4-hydroxy-
phenyl)-propane (bisphenol A).
The polycarbonates of the invention may entail in their
structure units derived from one or more of the suitable
bisphenols.
Among the resins su;table in the practice of the invention
are included phenolphthalein-based polycarbonate, copoly-
carbonates and terpolycarbonates such as are described in
Mo-3643
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U.S. Patents 3,036,036 j4,210,741. Other suitable resins have
been described in U.S.Patents 3,030,331; 3,169,121; 3,395,119;
3,729,447; 4,255,556; 4,260,731; 4,369,303 and 4,714,746 all of
which are incorporated by reference llerein.
The polycarbonates of the invention may also be branched
by condensing therein small quantities, e.g., 0.05-2.0 mol %
(relative to the bisphenols) of polyhydroxyl compound.
Polycarbonates of this type have been described, for example,
in German Offenlegungsschriften 1,570,533; 2,116,974 and
o 2,113,374; British Patents 885,442 and 1,079,821 and U.S.
Patent 3,544,514. The following are some examples of
polyhydroxyl compounds which may be used for this purpose:
phloroglucinol; 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-
heptane; 1,3,5-tri-(4-hydroxphenyl)-benzene; 1,1,1-tri-(4-
15 hydroxyphenyl)-ethane; tri-(4-hydroxyphenyl)-phenylmethane;
2,2-bis-~4,4-(4,4'-dihydroxydiphenyl)]-cyclohexyl-propane;
2,4-bis-(4-hydroxy-1-isopropylidine)-phenol; 2,6-bis-(2'-
dihydroxy-5'-methylbenzyl)-4-methylphenol; 2,4-dihydroxy-
benzoic acid; 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)-
20 propane and 1,4-bis-(4,4'-dihydroxytriphenylmethyl)-benzene.
Some of the other polyfunctional compounds are 2,4-dihydroxy-
benzoic acid, trimesic acid, cyanuric chloride and 3,3-bis-
(4-hydroxyphenyl)2-oxo-2,3-dihydroindole.
In addition to the polycondensation process mentioned
25 above, other processes for the preparation of the
polycarbonates of the invention are polycondensation in a
homogeneous phase and transesterification. `The suitable
processes are disclosed in the incorporated herein by
references, U.S. Patents 3,028,365; 2,999,846; 3,153,008; and
2,991,273.
The preferred process for the preparation of poly-
carbonates is the interfacial polycondensation process.
Other methods of synthesis in forming the polycarbonates
of the invention such as disclosed in U.S. Patent 3,912,688,
incorporated herein by reference, may be used.
Mo-3643
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Suitable polycarbonate resins are available in
commerce, for instance, Makrolon FCR, Makrolon 2600, Makrolon
2800 and Makrolon 3100, all of which are bisphenol based
homopolycarbonate resins differing in terms of their respective
molecular weights and characterized in that their melt flow
indices (MFR) per ASTM D-1238 are about 16.5-24, 13-16,
7.5-13.0 and 3.5-6.5 gm/10 min., respectively. These are
products of Mobay Corporation of Pittsburgh, Pennsylvania.
Aromatic polyester resins are high molecular weight
o thermoplastic resins which are well known in the art. These
resins are derived from an aromatic dicarboxylic acid and a
diol component and are characterized in that their intrinsic
viscosity is at least 0.4 deciliters per gram. Optionally, the
aromatic dicarboxylic acid component accounts for at least 85
mole percent of the dicarboxylic acid component. Among the
suitable aromatic dicarboxylic acids are terephthalic acid,
isophthalic acid, napthalene-dicarboxylic acid, diphenylether
dicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfone
dicarboxylic acid and diphenoxyethane dicarboxylic acid. The
optional, at most 15 mole percent of the acid component which
is not aromatic dicarboxylic, may be represented by hydroxy-
carboxylic acids and by aliphatic dicarboxylic acids such as
succinic acid, adipic acid and sebacic acid.
The diol component of these polyesters may contain from 2
to 10 carbon atoms, preferably from 2 to 4 carbon atoms in the
form of linear methylene chains with up to 30 mole percent of
one or more other aliphatic diols having 3 to 8 carbon atoms,
cycloaliphatic diols having from 6 to 15 carbon atoms or
aromatic diols having from 6 to 21 carbon atoms. Examples of
such additional diols ("codiols") include 3-methylpentanediol-
(2,4), 2-methylpentanediol-(1,4), 2,2,4-trimethylpentanediol-
(1,3), 2-ethylhexanediol-(1,3), 2,2,-diethylpropanediol-(1,3),
hexane-diol-(1,3), 1,4-di-(hydroxyethoxy)-benzene, 2,2,-bis-
(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetra-
Mo-3643
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methylcyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)-propane and
2,2-bis-(4-hydroxypropoxyphenyl)-propane.
Typical examples of the diol include ethylene glycol,
trimethylene glycol, tetramethylene glycol and hexamethylene
glycol, neopentyl glycol, cyclohexane dimethylol, tricyclo-
decane dimethylol, 2,2-bis-(4-hydroxyethoxy-phenyl)-propane
The polyesters may be branched by incorporating trihydric
or tetrahydric alcohols or tribasic or tetrabasic acids, as
described in German Offenlegungsschrift No. 1,900,270 and in
U.S. Patent 3,692,744. Examples of suitable branching agents
include trimesic acid, pyromellitic acid, trimethylol-propane
and ethane and pentaerythritol. It is advisable to use no more
than 1 mole percent of branching agent, based on the quantity
of acid component. The polyesters may also contain know mono-
functional compounds such as phenol or benzoic acid as chain
terminators.
The preferred polyesters are characterized in that their
structure comprises units of the general formula (1).
~o+CH2)~0-C~/
wherein n denotes 2 to 4.
The intrinsic viscosity characterizing the suitable
polyester resins in the practice according to the invention
should preferably be in the range of 0.4 to 1.4 grams per
deciliter and, more preferably between 0.4 to 1.4 grams per
deciliter, as measured in a 1 percent solution of phenol and
tetrachloroethane (60:40) at 25C.
Methods for the preparation of the polyester resin
suitable in the present context are known and have been
described in U.S. Patent Nos. 2,463,319 and 3,047,539.
The composition of the invention may include
crystallization rate promoters for the polyester (such as
oligomeric polyesters) to allow lower mold temperatures and
Mo-3643
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shorter injection cycles. Suitable promoters have been taught
in U.S. Patent No. 4,223,113 which disclosure is incorporated
herein by reference.
The polyestercarbonate resins suitable in the practice of
the invention are well known in the art and are available in
commerce, for instance under the trademark Apec, from Bayer AG
of Germany or alternatively from Mobay Corporation. These
resins have been described in the patent literature including
U.S. Patents 3,030,331, 3,169,121;4,194,038; 3,729,447;
o 3,972,852; 4,105,633; 4,219,635; 4,238,596; 4,238,597;
4,252,939; 4,255,556 and 4,260,731; 4,286,083 and 4,429,103 all
of which are incorporated by reference herein. Essentially
these resins may be described structurally as
~0~ C~--O--C _ o~ C ~ ~ ,~
wherein x and y are the molar fractions of the respective
blocks, and they each are in the range of about 0.1 to 0.9,
with the proviso that x + y = 1Ø
The polyestercarbonates of the invention have a weight
average molecular weight of 10,000-200,000, preferably
. 25 20,000-80,000 and their melt flow rate, per ASTM D-1238 at
300C, is about 1 to about 65 gm/10 min., preferably about 2-15
gm/10 min. They may be prepared by know methods, for instance
such as were disclosed in German DOS-2,714,544. Suitable
polyester carbonates have also been disclosed in German Patents
. 30 2,758,030, and 3,016,019 as well as in European Patent 10,840
and in U.S. Patents 3,351,624 and 3,207,814 all incorporated
herein by reference. Essentially, the polyester-
carbonates of the invention are produced by reacting phthalic
acid derivatives - essentially, a mixture of isophthalic and
Mo-3643
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terephthalic acids - with an acid derivative such as phosgene
and dihydroxy compounds by polycondensation (see German Offen-
legungsschriften 2,063,050; 2,063,052; 1,570,703; 2,211,956;
2,211,957 and 2,248,817; French Patent 1,561,518; and the
monograph H. Schnell, "Chemistry and Physics of Poly-
carbonates", Interscience Publishers, New York, 1964, all
incorporated herein by reference).
The dihydroxy compounds suitable for the preparation of
the polyestercarbonates are identical to the ones mentioned
o above relative to the preparation of polycarbonates.
Naturally, the polyestercarbonates may include in their
structure units derived from one or more of the suitable
dihydroxy compounds. Furthermore, branching agents suitable
for use in the context of polycarbonate resins and discussed
above, are also suitable for use in the polyestercarbonates.
In addition to the polycondensation process mentioned
above, other processes for the preparation of the polyester-
carbonates of the invention are polycondensation in a
homogeneous phase and transesterification. The suitable
. 20 . processes are disclosed in the incorporated herein by
references U.S. Patents 3,028,365; 2,999,846; 3,153,008; and
2,991,273.
The preferred process for the preparation of polyester-
carbonates is the interfacial polycondensation process.
25:` Suitable polyestercarbonate resins are available in
commerce, for instance, under the trade name APEC-50, and
APEC-80 which are based on bisphenol A and a mixture of
phthalic and isophthalic acids and phosgene. These resins
differ one from the other in terms of their respective amounts
of aromatic ester and are characterized in that their melt flow
indices (MFR) per ASTM D-1238 are about 12 to 15 gm/10 min. at
360C.
The UV stabilizing agent of the present invention is a -~
bis-benzotriazole conforming structurally to
Mo-3643
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3 ~
-10-
H
B - C - B
R
where R is a C1 22 alkyl,aryl,cycloalkyl,alkyl-aryl or
cycloalkyl-aryl radical and B is a phenylbenzotriazole moiety.
In a preferred embodiment the phenylbenzotriazole moiety
(B) conforms to
x
X~N~ ~\
X Ra
where Ra is a hydrogen or a hydrocarbon radical and X may be
independently a hydrogen or a halogen atom or a hydrocarbon
radical containing up to about 12 carbon atoms. In a more
preferred embodiment, Ra is a linear or branched alkyl and X is
a hydrogen atom. In the most preferred embodiment the UV
absorber is bis[2-hydroxy-5-t -octyl-3-(benzotriazol-2-yl)
phenyl]methane, conforming to
,~N~ OH IH OH ~N ~1
[~ 8~
t C8 17 t C~sH17 :~ ~
The phenolic compound useful in the present context
conforms to "
` (a)' ~H
~
n ~ :
Mo-3643
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~t~
-11-
wherein
R', denotes a C1 22 linear or branched alkyl, cycloalkyl
radical, C6 30 aryl, alkyl-aryl or cycloalkyl-aryl
radical, preferably C2 4 alkyl, most preferably tertlary
butyl radical,and R is a hydrogen or R', and
Z denotes a hydrogen, a Cl 22 alkyl or cycloalkyl, a C6 30
aryl, alkyl-aryl or cycloalkyl radicalt a C1 12 hydroxy
alkyl or hydroxyaryl radical or their ester der;vatives, a
thiol or thioether radical, an olefin, ester or ether
o oligomer or polymer radical, a linear or cyclic
isocyanurate or cyanurate radical, preferably C12 22 alkyl
ester, most preferably C21 alkyl ester, and
n is an integer of 1 to about 10,000 preferably, 1 to 5 most
preferably 1. In the most preferred embodiment, the
phenolic compound is octadecyl-3-5-di-t-butyl-4-hydroxy-
hydrocinnamate conforming to
~o :''
.l
(cH2) 2-c-0 Cl8 37
The phosphorous containing ester in the present context is
a substantially colorless organophosphorous compound conforming
structurally to~
2~ X
\ p ~ R
n
wherein R is a C1 30, preferably C1 ~8 linear or branched
alkyl or alkoxy radical, C6 30 aryl or aryloxy radical, C6 30
alkylaryl or alkylaryloxy or alkyloxyaryl radical or a C5 12
cycloalkyl or cyloalkyloxy radical, X denotes C1 30 alkoxy or
C6 30 aryloxY radical and n is 1 or 2.
Mo-3643 ;~
-12-
In a most preferred embodiment, the organophosphorous
compound of the invention is tetrakis(2,4-di-t-butylphenyl)
4,4'-biphenylenediphosphonite, conforming to
5 ~ ~>~
O~ <~ <O
~ ~'
The preparation of the suitable phosphite has been
disclosed in U.S. Patent 4,371,647 the specification of which
is incorporated herein by reference.
In the practice of the invention the components of the
composition are added to the resin at the quantities indicated
below:
about 0.02 to 0.2 percent, preferably 0.08 to 0.15 percent
of the organophosphorous compound,
about 0.02 to 0.2 percent preferably 0.08 to 0.15 of the
phenolic compound, the sum of these components amounting
to about 0.04 to 0.4% relative to the weight of the
composition.
In a most preferred embodiment, the organophosphorous and
the phenolic compound each are added at a level of about O.O~O
relative to the weight of the composition.
The bis-benzotriazole of the invention is added to the
composition at a level of about 0.01 to 20%, preferably ;
about 0.3 to 10 percent, relative to the weight of the
composition.
The preparation of the molding compositions in accordance
with the invention follows conventional procedures which are
well known in the art. `~
Mo-36~3
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-13-
The molding composition of the invention may also include
conventional additives which are known in the polycarbonate art
for their utility. Included are plasticizers, mold release
agents, flame retardants, hydrolytic stabilizers, pigments,
impact modifiers, fillers and reinforcing agents. The
compositions are useful for preparing molded articles which are
both UV-stable and color stable.
EXPERIMENTAL
Compositions within the scope of the present invention
have been prepared and their properties evaluated. In the
compositions which are described below, the resinous component
was Makrolon 3200 polycarbonate resin which is a bisphenol-A
derived polycarbonate having a melt flow - as determined by
ASTM D-1238 - of about 4 gm/10 min. All the compositions
contained 10% of the UV stabilizer of the invention, namely
Mixxim BB-100- "BB"in the results tabulated below. The
phenolic compound was Irganox 1076 , "I" in the table ,which
conforms structurally to
~H
2G. . ~
(CH2) 2 C C18H37
The phosphorous ester was PEP-Q, "P" in the ~able, which
~5 cJnfrrms to ~
o~ P ~ '.~. i, '
.30 ~ ~k ~
For comparison purpose, an epoxy compound ~ERL-4221) , "E" in
the table below, which conforms to
f~ O-CH2 Q,
Mo-3643 ~ - ~
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. , . . .. .. , , ~ . :, ~ ~ .
- . ... . : . - : : :
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-14-
and an end cap polyether, denoted as "M" in the table below ,
conforming to
r CH3
R - ~ H2 CH - O ~ R
where R = pyranyl radical and n = about 40
were used.
In the table below the amounts of the additive components
are noted in weight percent.
Table 1
Example Additive Components MFR YI1 yI2 Haze1 Haze2
1 none 7.6 23.32 22.26 4.5 4.1
2 0.08 I 8.0 21.64 21.48 2.5 2.5
3 0.16 I 7.5 21.47 21.29 1.1 1.1
4 0.08 P 9.4 19.95 19.71 1.4 1.2
0.20 E 33.7 18.39 18.19 1.0 1.0
6 0.08 I and 0.08 P 8.6 16.48 15.96 O.B 1.0
7 0.17 M 9.3 20.50 20.09 0.7 0.8
Notes:
I denotes the initial values
denotes the value after exposure of 69 hours to a sun lamp
The data show that composition 6 which represents the
invention has the lowest yellowness index and low haze
combination. Also, it appears that the combined activity of
the agent of the invention - Example 6- is more efficacious
than either of them alone - Examples 2 and 4- even if the
amount of the additive (hindered phenol) is doubled- Example 3
- to equal the weight amount of the combination.
Mo-3643
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In an additional set of experiments the the results of
which are tabulated below, the additives were identical to the
ones noted above. The compositions, all based on Makrolon 3200
polycarbonate contained the indicated amount of added
5 components and exhibited the noted melt flow rates and Initial
Yellowness Indices.
Table '2
Example Components MFI YI
8 none 4.91 4.29
9 0.08 P; 0.08 I 5.06 3.33
none3 4.76 4.06
11 0.3 B~ 4.91 5.67
12 0.3 BB;0.08 P;0.08 I 5.14 4.16
13 0.3 BB;0.16 P 5.02 4.29
1 Initial Yellowness index values
2 The compositions 8 and 9 were processed in a twin screw
extruder;
3 The compositions 10-13 were processed in a single screw
extruder.
The data show that the addition of the hindered phenol and
phosphorous ester only, reduced the yellowness index of the
polycarbonate alone by approx. 1 unit (compare Examples 8 to
9). The addition of the UV stabilizer of the invention tends
to increase the yellowness index- Examples 10 and 11. The
addition of twice the amount of the phosphorous ester alone
causes a reduction of the yellowness index of a UV- protected ~;
composition- Example 13. The synergy of the invention is
demonstrated by Example 12 where the hindered phenol and
phosphorous ester reduced the yellowness of the UV stabilized
composition by more than 1.5 units.
Mo-3643
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In yet an additional set of experiments, the additives
were identical to the ones noted above. The compositions, all
contain 10% of a UV stabilizer : compositions 16-18 contained
the UV stabilizer of the invention - noted as BB in the table;
In the comparison examples - Examples 19-21 there was used a UV
stabilizer conforming to
[~N ~ .. L
CH -CH -C-0-CH -CH -CH
available as Tinuvin 840 from Ciba Geigy Corporation - termed
"T" in the table below. In the table below there are
summarized the results of the evaluation.
Table 3
Example Additives MFR YI1
14 none 4.91 4.29
0.08 P; 0.08 I 5.06 3.33
16 10.00 BB; 9.97 18.92
17 10.00 BB;0.17 P 8.67 18.51
18 10.00 BB;0.08 P;0.08 I 8.24 13.02
19 10.00 T; 12.21 14.57
10.00 T;0.17 P; 12.59 16.46
21 10.00 T;0.08 P;0.08 I 13.00 15.61
The data show that the stability of color which is obtained in
compositions containing the UV stabilizer of the invention,
(compare ~xamples 18 to 16) is not shared by compositions which
differ in their UV stabilizer - compare Examples 19 to 21.
Mo-3643
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-17-
The data also show that the synergy in color stability
associated with the combination of the invention - Example 18-
is not shared by a composition which contains twice the amount
of the phosphorous ester- Example 17.
Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be
understood that such detail is solely for that purpose and that
variations can be made therein by those skilled in the art
without departing from the spirit and scope of the invention
o except as it may be limited by the claims.
:
Mo-3643
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