CA2072193A1 - Color-stable and uv-resistant polycarbonate and polyester compositions - Google Patents

Abstract

Mo-3643 COLOR-STABLE AND UV-RESISTANT POLYCARBONATE
AND POLYESTER COMPOSITIONS
ABSTRACT OF THE DISCLOSURE
A thermoplastic molding composition is disclosed containing a polycarbonate and/or an aromatic polyester resin and/or a polyestercarbonate resin. The composition which contains a bis-benzotriazole compound as a UV stabilizer is rendered improved color stability upon the incorporation therewith of a phenolic compound and a phosphorous ester. The composition is suitable for the preparation of color stable, UV
resistant molded articles.

Mo3643

Description

Mo-3643 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 . . . . ~
. j . . . .

~7~ i' 2 ~

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 - , , . . . .

~JI 7~ '" ~ .3 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 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 -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 . .~.
. ~ . .. -,. ~

....
. . .

2.~ ~-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 . . . : -~, .
. . - ~ , . ~ .- . ~ , ' - :- . : ' .

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 . . .

. ~ . . -çq ~ r~ 3 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 ' J ~

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 . - ~
. ~ .

3 i 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 :
..
- :~- . -g i~?J ~

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 . ~:

, . . . . .

3 ~

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 , , ~t~

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 ;~

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 ..
.
- ' ,..... , ' . - , : : : - . `

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 ~ - ~

- . - ~
. . . , - - . . ~ . , , :
.. . . . . . . .. . . .
. , . . .. .. , , ~ . :, ~ ~ .
- . ... . : . - : : :

.. . . . ..

. . . . . . . .

~`s,3 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 .

~: . - .: . . . . . .
. :~ . ~ . . . . .

.. - .
.. . .. ..

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 ~ . . . . . .

: . - ~ . . ; - : ~

~7~

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

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 ' L IJ ~

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 - ~ - , :

..

.:

- :

Claims (9)

1. A thermoplastic molding composition comprising (i) at least one resin selected from the group consisting of polycarbonate, aromatic polyester and polyestercarbonate, (ii) a UV- stabilizing compound conforming structurally to where R is a C1-22 alkyl, aryl, cycloalkyl, alkyl-aryl or cycloalkyl-aryl radical and B is a phenylbenzotriazole moiety, and (iii) a phenolic compound conforming to wherein R' denotes a C1-22 linear or branched alkyl, cycloalkyl radical, C6-30 aryl, alkyl-aryl or cycloalkyl-aryl radical, and R is a hydrogen or R' , and Z denotes a member selected from the group consisting of a hydrogen atom, a C1-22 alkyl,C1-22 cycloalkyl, a C6-30 aryl, C6-30 alkyl-aryl, C6-30 cycloalkyl radical, a C1-12 hydroxy alkyl,C1-12 hydroxyaryl radical and their ester derivatives, a thiol radical, a thioether radical, an olefin, an ester radical, an ether radical, a linear or cyclic isocyanurate, a linear or cyclic cyanurate radical, and Mo-3643 n is an integer of 1 to about 10,000, and (iv) a substantially colorless organophosphorus compound conforming structurally to:

wherein R is selected from the group consisting of C1-30 alkyl radical, C1-30 alkoxy radical, C6-30 aryl radical, C6-30 aryloxy radical, C6-30 alkylaryl radical, C6-30 alkylaryloxy radical, C6-30 alkyloxyaryl radical, C5-12 cycloalkyl radical and C5-12 cyloalkyloxy radical, and X denotes C1-30 alkoxy or C6-30 aryloxy radical and m is 1 or 2.

2. The composition of Claim 1 wherein said phenylbenzo-triazole moiety conforms to where Ra is a hydrogen or a hydrocarbon radical and X may be independently hydrogen or a halogen atom or an hydrocarbon radical containing up to about 12 carbon atoms.

3. The composition of Claim 2 wherein said Ra is a linear or branched alkyl and X is a hydrogen atom.

4. The composition of Claim 3 wherein said UV absorber is bis[2-hydroxy-5-t-octyl-3-(benzotriazol-2-yl)phenyyl] methane.

5. The composition of Claim 1 wherein said phenolic compound is characterized in that said R' is C2-4 alkyl.

Mo-3643

6. The composition of Claim 1 wherein said Z is a C12-22 alkyl ester.

7. The composition of Claim 1 wherein said n is 1 to 5.

8. The composition of Claim 4 wherein said phenolic compound isoctadecyl-3-5-di-t-butyl-4-hydroxy-hydrocinnamate..

9. The composition of Claim 1 wherein said organo-phosphorous compound is characterized in that said R is C6-18 aryl radical and X is a C6-18 aryloxy radical.
The composition of Claim 8 wherein said organo-phosphorous compound is tetrakis(2,4-di-t-butylphenyl) 4,4'-biphenylene diphosphonite.

Mo-3643