WO1981002021A1

WO1981002021A1 - Stabilization of polyphenylene ether-compositions by tetrasubstituted piperidines

Info

Publication number: WO1981002021A1
Application number: PCT/US1981/000041
Authority: WO
Inventors: V Abolins; G Cooper
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1980-01-14
Filing date: 1981-01-13
Publication date: 1981-07-23
Anticipated expiration: 1982-07-14
Also published as: JPS56501881A

Abstract

Novel stabilized compositions of polyphenylene ethers based on the use of a tetrasubstituted piperidine alone or in combination with a phosphite or a hydroxybenzotriazole or a hindered phenol.

Description

Stabilization of Polyphenylene Ether- Compositions by Tetrasubstituted Piperidines

Background of the Invention - The term "polyphenylene ether resin" is descriptive of a well known group of polymers that may be made by a variety of catalytic and non-catalytic processes. By way of illustration, certain of the polyphenylene ethers are disclosed in Hay, U.S. Patent No. 3,306,874 and 3,306,875, and in Stamatoff, 3,257,357 and 3,257,358, In the Hay patents the polyphenylene ethers are prepared by an oxidative couplingreaction coroprising passing an oxygen-containing gas through a reaction solution of a phenol and a metal-amine complex catalyst. Other disclosures relating to processes forpreparing polyphenylene ethers are round in Fox U.S Patent 3,356,761; Sumitomo, U.K. Patent 1,291,609; Bussinget al, O.S. Patent No. 3,337,499; Blanchard et al , 3,219,626; Laakso et al, 3,342,892; Borman, 3,344,166; Hori et al, 3,384,619; Faurote et al 3,440,217; and disclosures relating to metal based catalysts which do not include amines, are known from patents such as Wieden et al, U.S. Patent

No. 3,442,885 (cooper-amidines); Nakashio et al, U.S. Patent No. 3,573,257 (metal-alcoholate or phenolate); Kobayashi et al, U.S. Patent No. 3,455,880 (cobalt chelates); and the like. In the Stamatoff patents, the polyphenylene ethers are produced by reacting the corresponding phenolate ion with an initiator, such as a peroxy acid salt, an acid peroxide, a hypophalite, and the like, in the presence of a complexing agent. Disclosures relating to non-catalytic processes, such as oxidation with lead dioxide, silver oxide, etc., are described in Price et al, U.S. Patent No. 3,382,212. Cizek, U.S. 3,383,435 diclsoses compositions of polyphenylene ethers and styrene resins. All of the abovementioned disclosures are incorporated herein by reference.

Hydroxybenzophenones and hydroxybenzotriazoles in combination with organic nickel complexes have been utilized in stabilizing polyphenylene ether compositions against ultraviolet light instability. It has been found that a tetrasubstituted piperidine is a very effective agent for preventing the ultraviolet light induced discoloration of polyphenylene ether resin compositions. This stabilizer also imparts thermal stability and can be used alone or in combination with a phosphite or a hydroxybenzotriazole or a hindered phenolic antioxidant.

The tetrasubstituted piperidines have been used in the prior art as an ultraviolet stabilizer for polystyrene, polyolefins polyurethanes and for segmented copolyesters. In addition, this stabilizer in combination with a 2- (2H-benzotriazol-2-yl)-p-cresol has been used in the prior art for stabilizing polyolefins and polystyrene. Cf. Poliplasti No. 235 pp 40-46 (1977) and U.S. 3,640,926, which are incorporated by reference. An advantage attributed to the use of the tetrasubstituted piperidine stabilizer is that it produces no change in initial color of polyphenylene ethers which has resulted from stabilizers such as the organic nickel complexes.

Accordingly, it is an object of this invention to prepare novel polyphenylene ether compositions that posses improved resistance to photoyellowing on exposure to ultraviolet light. It is a further object of this invention to provide improved thermal-oxidative stability to polyphenylene ether compositions.

Detailed Description of the Invention This invention provides stabilized molding compositions which comprise:

(a) a polyphenylene ether resin or a polyphenylene ether resin in combination with a vinyl aromatic resin; and

(b) an amount of a piperidine derivative having the general formula:

wherein R₁ and R₂ , which may be the same of different, each are an alkyl group, or they form, together with the carbon atom to which they are attached, a saturated alicyclic group with 5 to 7 ring carbon atoms or a group of the formula:

n is an integer of 1 to 3 inclusive; and when n is 1, R₃ is an acyl group, an N-substituted carbamoyl group having as a substituent alkyl, cycloalkyl or aryl, an N-Monosubstituted thiocarbamoyl group having as a substituent alkyl, cycloalkyl or aryl, a monovalent group obtained by removing a hydroxyl group from a sulfinic acid, a sulfonic acid, a phosphorus-containing acid or a boric acid, an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group or a group of the general formula:

(wherein R₁ and R₂ are as defined as above) when n is 2, R₃ is a diacyl, derived from a dibasic aliphatic or aromatic carboxylic acid, a dicarbamoyl group in which two carbamoyl groups are combined by interruption of aryl, alkyl, diarylalkane or diaryl ether, a carbonyl group, a divalent group obtained by removing two hydroxyl groups from a disulfonic acid, a phosphorus-containing acid or a boric acid, an alkylene group, an arylene group or arylene dialkylene group, and when n is 3, R₃ is a triacyl group derived from an aromatic, cycloaliphatic or furane tricarboxylic acid, a tricarbamoyl group in which three carbamoyl groups are attached to one aryl group, a trivalent group obtained by removing three hydroxyl groups from a trisulfonic acid, a phosphorus-containing acid or a boric acid, alkanetriyl, an arenetriyl group or an arenetriyltrialkylene group; or a salt thereof with phosphoric acid, carbonic acid, citric acid, stearic acid or benzoic acid, alone or in combination with a phosphite or a hydroxybenzotriazole or a hindered phenolic antioxidant in an amount that is sufficient to stabilize said molding composition to the effects of ultraviolet light or to thermal oxidative embrittlement.

The polyphenylene ether resins comprise polymers of structural units of the formula:

wherein Q is selected from the group consisting of hydrogen, hydrocarbon radicals, halohydrocarbon radicals having at least two carbon atoms between the halogen atom and the phenyl nucleus, hydrocarbonoxy radicals and halohydrocarbonoxy radicals having at least two carbon atoms between the halogen atom and the phenyl nucleus, Q' and Q" are the same as Q and in addition halogen, with the proviso that Q and Q' are both free of a tertiary carbon atom and n is an integer of at least 50.

The preferred polyphenylene ether resin is a poly (2 , 6-dimethyl-1,4-phenylene) ether resin having an intrinsic viscosity of from about 0.4 to about 0.65 dl/g as measured in chloroform at 30°C.

The vinyl aromatic resin will have at least 25% of units derived from monomers of the formula:

wherein R¹ and R² are selected from the group consisting of lower alkenyl groups of from 1 to 6 carbon atoms and hydrogen;R³, R⁴ and R⁵ are selected from the group consisting of chloro, bromo, hydrogen and (lower) alkyl of from 1 to 6 carbon atoms;

R ⁶ and R⁷ are selected from the group consisting of hydrogen and (lower) alkyl and alkenyl group of from 1 to 6 carbon atoms or R⁶ and R⁷ may be concatenated together with hydrocarbyl groups to form a naphthyl group. Styrene is the preferred vinyl aromatic compound.

An α, β-unsaturated cyclic anhydride may be copolymerized with the vinyl aromatic compound. These compounds may be represented by the formula :

wherein the dotted lines represent a single or double carbon to carbon bond, R ⁷ and R⁸ taken together represents a

linkage, R⁹ is selected from the group consisting of hydrogen, vinyl, alkenyl alkylcarboxylic or alkenylcarboxylic of from 1 to 12 carbon atoms, n is 1 or 2, depending on the position of the carbon-carbon double bond, and m is an integer of from 0 to about 10. Examples include maleic anhydride, citraconic anhydride, itaconic anhydride, aconitic anhydride and the like.

Rubber, i.e. 1-15 parts by weight may be employed in preparing the rubber-modified polymers of a vinyl aromatic compound such as polybutadiene rubber, butyl rubber, styrenebutadiene rubber, acrylonitrile rubber, ethylene-propylene copolymers, natural rubber, EPDM rubbers, and the like. If desired, thermoplastic rubbers such as the AB or ABA block copolymers may be used at 1-15 parts by weight of composition. Suitable ABA block copolymers are the Kraton or Kraton G polymers that are described in U.S. 3,646,162 and U.S. 3,595,942, respectively, both of which patents are incorporated by reference. The vinyl aromatic resin can comprise from 40 to 0 parts by weight of the α, β nnsaturated cyclic anhydride, from 60 to 100 parts by weight of a vinyl aromatic compound and from 1 to 25 parts by weight of rubber. The preferred copolymers will comprise from about 85 to 95 parts by weight of the vinyl aromatic compound and about 10 parts by weight of the rubber. A preferred vinyl aromatic polymer is rubber modified, high impact polystyrene.

A preferred rubber modified vinyl aromatic α, β-unsaturated cyclic anhydride copolymer is Dylark 240, available from Arco Polymers, Dylark 240 is a high impact styrene maleic anhydride copolymer containing 9-10% rubber, 9% maleic anhydride, and the balance being styrene.

A preferred class of tetrasubstituted piperidines are the mono or di-acyl esters such as the benzoate, adipate and most preferably the sebacic acid diester of 2 , 2,6, 6-tetramethyl-4- hydroxypiperidine.

The compositions may comprise from 15 to 95 parts by weight of a polyphenylene ether resin from 85 to 5 parts by weight of a vinyl aromatic resin; from 0.05 to 5.0 parts by weight and more preferably 0.1 to 0.5 parts by weight of the tetrasubstituted piperidine and optionally from 0.1 to 5.0 parts by weight of the hydroxybenzotriazole and optionally 0.25 to 1.5 parts of a phosphite ester or 0.1 to 0.5 parts of a hindered phenolic an oxidant.

If no vinyl aromatic resin is present, the polyphenylene ether resin may comprise 60 to 99 parts by weight; from 0.1 to 5.0 parts by weight of tetrasubstituted piperidine; from 0.5 to 2 parts by weight of a phosphite compound; from 0-15 parts by weight of a thermoplastic rubber; 0 to 30 parts by weight of a phosphate plasticizer.

The useful hydroxybenzotriazoles include 2- (2H-benzotriazol-2-yl)-p-cresol; 2- (2H-benzotriazol-2-yl)-4,6-di-tertpentylphenol; 2-tert-butyl-6- (5-chloro-2H-benzotriazol-2-yl) pcresol; 2 ,4-di-tert-butyl-6- (5chloro-2H-benzotriazol-2-yl) phenol. Other compounds of this type may be found in U.S. 3,004,896 which is hereby incorporated by reference.

The phosphite esters have the structure P (OR)₃ wherein R is phenyl or an alkyl group of 6-12 carbon atoms such as hexyl, nonyl, decyl or dodecyl. They are described in 3,969,306.

The term hindered phenol is used to describe a compound having at least one phenolic hydroxyl group which has di-ortho substituted alkyl groups such as tert-butyl groups. Examples of these compounds are 2 , 6-di-tert-butyl-p-cresol; 2,2'methylenebis

(4-methy1-6-tert-butyl phenol; 4, 4 ' -butylidenabis (6-tert-butylm-cresol); 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butyl phenyl) butane; 4, 4 'methylenebis (2 , 6-di-tert-butyl phenol; octadecyl 3 (3 ' ,5 ' -di-tert-butyl-4-hydroxy phenyl) propionate; 2 , 6-di (1methylheptadecyl) p-cresol; 1,3,5-trimethyl-2,4,6-tris (3,5-ditert-butyl-4-hydroxybenzene; and tetrakis (methylene 3-(3',5'- di-tert-butyl-4' -hydroxybenzene; and tetrakis (methylene 3-(3",5'- the hindered phenols are described in U.S. 3,282,939; U.S. 3,338,833; U.S. 3,969,306 and U.S. 3,364,171 all of which are incorporated by reference. The phosphate plasticizers are the phosphates described in U.S. 4,077,934 which is incorporated by reference.

The compositions of this invention may also include amounts of fillers such as from 1-40 parts by weight of a reinforcing filler such as filamentous glass or other fillers such as quartz, metal fibers, wollastonite or the fillers mentioned in U.S. 4,080,351, columns 3 and 4 which is hereby incorporated by reference. If desired flame retardants may be added in a minor proportion to impart flame retardant properties to the compositions. Flame retardants such as those described in U.S. 3,833,535, which is incorporated by reference may be utilized in the compositions of the invention.

The composition may be prepared by tumbling powdered forms of the components, extruding the mixed powders into a continuous strand, chopping the strands into pellets and thereafter molding the pellets into the desired shape. These techniques are well known and do not form a part of the invention. All references to parts refer to parts by weight-

Description of the Preferred Embodiments -

Example 1

350 g of poly (2,6-dimethyl-1,4-phenylene) ether (PPO^R, General Electric Co., IV of about 0.5 dl/g in CHC1₃ at 30°C) , 650 g of rubber modified high impact polystyrene* , 70 g of triphenyl

* Foster Grant 834 phosphate and 50 g of titanium dioxide were mixed together and extruded at 550°F in a 28 mm twin-screw extruder, with no vacuum applied. The extruded pellets were molded in a screw injection molding machine into plates measuring 3-1/4 x 2-1/2 x 1/8". Another blend, identical with the first, except for the addition of 5 g of the sebacic acid diester of 2,2,6,6-tetramethyl-4- hydroxypiperidine was similarly extruded and molded.

The molded plates were placed in racks on a rotating platform protected by a single thickness (0.090 inches) of ordinary window glass and exposed at a distance of three inches to a battery of fluorescent blacklight lamps. Yellowness index was measured each day according to the procedure of ASTM Test No. D1925 and the time reσuired for an increase of one yellowness unit was .estimated from a graph of the data obtained. The control blend, without stabilizer, increased one unit in 36 days; the blend containing 0.5 phr of the sebacic acid diester required 61 days to increase by one unit of yellowness. It is believed that the mild extrusion conditions and the absence of vacuum contributed to the stability.

Example 2

A control blend was extruded and molded, as described in Example 1, from 300 g of poly (2,6-dimethyl-1,4-phenylene) ether, 300 g of polystyrene, 6 g of tridecyl phosphite, 18 g of triphenyl phosphate, 9 g of low molecular weight polyethylene , 0.9 g of zinc sulfide, 0.9 g of zinc oxide, and 18 g of titanium dioxide. Other blends were prepared in the same way, with the addition of 0,25, 0.50, and 1.0 phr of the sebacic acid diester of Example 1; another blend contained 0.5 phr of the sebacic acid diester of Example 1 and 0.5 phr of Irganox 1076, a phenolic antioxidant. The initial yellowness index of all the samples were essentially the same (24.6 ⁺ 0.5). The plates were exposed as described in Example 1; the times required for one unit increase in yellowness index are listed below:

Sebacic Acid Time in one unit

Diester increase in Y.I, (days)

None 11 .4 0.25 15. 0 0.50 21. 3 1.00 22 . 1 0.50* 18. 5

Example 3

A control blend containing 585 g of poly (2,6-dimethyl- 1.4-phenylene) ether, 165 g of triphenyl phosphate, and 22.5 g of titanium dioxide was extruded and molded as described in Example 1. A second blend was similarly prepared, with the addition of 3 g of the sebacic acid diester of Example 1. A third blend was prepared from 585 g of poly (2,6-dimethyl-l,4-phenylene) ether, 165 g of triphenyl phosphate, 6 g of tridecyl phosphite, and 22.5 of titanium dioxide, and a fourth having the same composition as the third, with the addition of 3 g of the sebacic acid diester of Example 1. The plates were exposed under the conditions described in Example 1;

* Also contained 0.50 phr Irganox 1076, which is octadecyl-3- (3' ,5' -di-tert-butyl-4' -hydroxyphenyl) propionate. Sebacic Acid

Tridecyl phosphite Diester Time to one unit

(Phr) (phr) increase in Y.I. (days)

None None 13.8

None 0.5 19.3

1.0 None 14.2

1.0 0.5 21.5

Example 4

500 g of poly (2,6-dimethyl-1,4-phenylene) ether, 500 g of rubber modified high impact* polystyrene, 10 g tridecyl phosphite, 15 g of polyethylene, 30 g of triphenyl phosphate, 1.5 g of zinc fulfide, 1.5 g of zinc oxide, and 30 g of titanium dioxide were blended and extruded as described in Example 1, except that a vacuum of 25 inches of mercury was applied to the extruder vent. Other blends were prepared in the same way, with the addition of varying amounts of the sebacic acid diester of Example 1,2- (2H-benzotriazol-2-yl) 4 , 6-di-tert-pentylphenol or a phenolic antioxidant**. The molded plates were exposed as described in Example 1, with the following results:

* Foster Grant 834 ** Irganox 1076 Sebacic Acid 2- (2H-benzotriozol- Phenolic Days to Diester 2-yl ) 4 , 6-di-tert- antioxidant increase one (phr) pentylphenol (phr) unit to Y.I.

None None None 7.2

0.5 None None 10.0

0.25 0.25 None 10.0

0.25 0.25 0.25 10.0

None 0.5 None 8.5

Example 5

A base composition of 40 parts of poly (2 , G-dimethyl-1,4- phenylene) ether resin having an IV of about 0.5 dl/g in CHCI₃ at 30°C; 60 parts of rubber modified, high impact polystyrene (Foster Grant 834): 8 parts of a mixture of tri-arylphosphates * with the aryl groups comprising phenyl mono-isopropyl phenyl, di propylphenyl said mixture having an average of about one isopropyl group per aromatic ring; 1 part of diphenyl decyl phosphite; 1.5 parts of polyethylene; 0.15 parts of zinc sulfide and 0.15 parts of zinc oxide were extruded in a 28mm twin-screw extruder at a temperature of about 550°F and the extruded strands were chopped into small pellets. 50 parts of the base composition, 50 parts of styrene-maleic anhydride copolymer**, 4 parts of hydrogehated styrene-butadiene triblock copolymers***, 5 parts of titanium dioxide and 0.5 parts of hindered phenolic antioxidant**** were extruded and molded into 1/8" x 2-1/2" x 3-1/4" plates. Other blends

* Kronitex 50

** Dylark 240

*** Kraton G-1652

**** Irganox 1076 of the same composition, with the addition of small amounts of stabilizers were similarly extruded and molded. The plates were placed in racks on a rotating platform and exposed at a distance of three inches to a battery of fluorescent blacklight lamps as in Example 1 but without the glass covering. Yellowness index was measured at twenty-four hour intervals according to the procedure of ASTM Test No. D1925 and the time required for an increase of one yellowness unit was estimated from a graph of the data. Results of these tests are listed in Table 1. A mixture of 1.5 parts of the sebacic acid diester of Example 1 and 1.5 parts of 2- (2-H-benzotriazol-2-yl) 4 , 6-di-tert-butyl phenol delays the beginning of photoyellowing substantially more than 3 parts of either the sebacic acid diester of Example 1 or 2-2 (2-H-benzotria zol-2-yl) 4 ,6-di-tert- butyl phenol alone. After fifteen days exposure, the increase in yellowness of the blend containing the mixture of stabilizers was less than half that for the blends containing only a single stabilizer.

Example 6 100 parts of the base composition of Example 5, 5 parts of titanium dioxide; 0.5 parts of hindered phenolic antioxidant* and varying amounts of stabilizers was extruded, molded, and tested as described in Example 5 , with the results shown in Table 2. A mixture of 2.5 parts of a mixture of the sebacic acid diester of Example 1 with 2.5 parts of either 2- (2H-benzo- triazol-2-yl)-jo-cresol or 2- (2H-benzotriazol-2-yl)4,6-di-tert- pentylphenol delayed the onset of yellowing substantially longer than five parts of any of the stabilizers alone and the increase in yellowness after 15 days in the blend containing mixtures of stabilizers was less than half that of blends containing a single stabilizer.

Example 7

Blends of 50 parts of the base composition of Example 5, 50 parts styrene-maleic acid copolymer*, 4 parts hydrogenated styrene-butadiene triblock copolymer**, 5 parts titanium dioxide, 0.5 parts of hindered phenolic antioxidant***, and varying amounts of light stabilizers were extruded, molded and tested as described in Example 5, with the results in Table 3. Mixtures of the sebacic acid diester of Example 1 with either 2-(2H-benzo triazol-2-yl) -p-cresol or 2- (2H-benzotriazol-2-yl) 4 , 6-di-tert- pentylphenol were more effective than the some total amount of either stabilizer alone.

* Dylark 240

** Kraton G-1652

*** Irganox 1076 Example 8 A mixture of 55 parts of poly (2,6-dimethyl-1,4- phenylene) ether resin having an IV of about 0.5 dl/g as measured in CHC1₃ at 30°C; 45 parts of rubber modified, high impact polystyrene (Amoco 6H6) : 3.5 parts of the tri-arylphosphate used in Example 5; 1 part of diphenyl decyl phosphite; 1.5 parts of polyethylene; and 3 parts of titanium dioxide was extruded in a twin-screw extruder and the extruded pellets were then molded into standard test pieces in a screw injection molding machine. Two additional compositions were prepared in the same way which also included 0.2 parts of the sebacic acid diester and 0.2 parts sebacic acid diester and 0.2 parts of 2,6-di-tert-butyl-4-methyl- phenol (BHT) . The test pieces were aged in a circulating air oven at 115°C and the time to embrittlement was determined.

Control 45-46 days

Sebacic Acid Diester (0.2) 91-98 days

Sebacic Acid Diester (0.2) 98-105 days

BHT (0.2)

Example 9

A mixture of 55 parts of poly (2,6-dimethyl-1,4-ρhenylene) ether resin 45 parts of rubber modified, high impact polystyrene, (Foster Grant 834 butadiene modified polystyrene); 1 part of diphenyldecylphosphite; 3.5 parts of the tri-arylphosphate of Example 5; 0.15 parts of zinc sulfide; 0.15 parts of zinc oxide; 3 parts of polyethylene; and 3 parts of titanium dioxide were extruded and molded in the manner described in Example 8. An additional stabilized composition was prepared which included 0.2 parts of the sebacic acid diester and 0.2 parts of octadecyl-3-

(3',5' -di-tert-butyl-4'-hydrocyphenyl) propionate. The control composition embrittled in 31-35 days at 115°C while the stabilized composition remained ductile for 54-57 days.

Example 10

Compositions were prepared as described in Example 9 except that an EPDM modified polystyrene (12% Epcar EPDM rubber) was substituted for the butadiene modified polystyrene of Example 9. The times to embrittlement of test pieces at 115ºC are listed below:

Additive Time To Embrittlement

Control 51-55 days

0,2 parts of octadecyl-3- 55-58 days (3',5' -di-tert-butyl-4' - hydroxyphenyl) propionate

0.2 parts of the sebacic 68-71 days acid diester

0.2 parts sebacic acid 85-89 days diester and 0.2 parts of octadecyl-3- (3',5'-di-tert- butyl-4'-hydroxyphenol) propionate

Example 11

A resin composition containing 50 parts of poly (2,6- dimethyl-1,4-phenylene) ether; 50 parts of rubber modified, high impact polystyrene; 1.5 parts polyethylene; 3 parts triphenylphosphate; 0.15 parts zinc sulfide and 0.15 parts zinc oxides were extruded and molded as described in Example 9. Compositions were prepared using this resin composition with the addition of the listed stabilizers and these compositions were aged in air at 115°C.

Time to diphenyl decyl Embrittlement phosphite Additive (days)

None None 43-50

None 0.25 phr sebacic acid 57-61 diester

1 phr None

1 phr 0.25 phr octadecyl 3- 74-78

(3',5' -di-tert-butyl

-4-hydroxyphenyl) propionate phr 0.25 sebacic acid 86-91 diester phr 0.25 phr sebacic acid 91 diester and 0.25 phr 3- (3'-5' -di-tert-butyl-4- hydroxyphenyl) propionate

Obviously many variations will suggest themselves to those skilled in the art from the above detailed description without departing from the scope or spirit of the invention. It is, therefore, to be understood that changes may be made in the particular embodiments of the invention as defined by the appended claims.

Claims

Claims A stabilized molding composition which comprises:

(b) an amount of a piperidine derivative having the general formula:

wherein R₁ and R₂, which may be the same or different, each are an alkyl group, or they form, together with the carbon atom to which they are attached, a saturated alicyclic group with 5 to 7 ring carbon atoms or a group of the formula:

n is an integer of 1 to 3 inclusive; and when n is 1, R₃ is an acyl group, an N-substituted carbamoyl group having as a substituted alkyl, cycloalkyl or aryl, an N-monosubstituted thiocarbamoyl group having as a substituent alkyl, cycloalkyl or aryl, a monovalent group obtained by removing a hydroxyl group from a sulfinic acid, a sulfonic acid, a phosphorus-containing acid or a boric acid, an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group or a group of the general formula:

(wherein R₁ and R₂ are as defined as above) when n is 2, R₃ is a diacyl, derived from a dibasic, aliphatic or aromatic carboxylic acid, a dicarbamoyl group in which two carbamoyl groups are combined by interruption or aryl, alkyl, diarylalkane or diaryl ether, a carbonyl group, a divalent group obtained by removing two hydroxyl groups from a disulfonic acid, a phosphorus-containing acid or a boric acid, an alkylene group, an arylene group or arylene dialkylene group, and when n is 3, IL is a triacyl group derived from an aromatic, cycloaliphatic or furane tricarboxylic acid, a tricarbamoyl group in which three carbamoyl groups are attached to one aryl group, a trivalent group obtained by removing three hydroxyl groups from a trisulfonic acid, a phosphorus-containing acid or a boric acid, alkanetriyl, an arenetriyl group or an arenetriyltrialkylene group; or a salt thereof with phosphoric acid, carbonic acid, citric acid, stearic acid or benzoic acid, alone or in combination with a phosphite or a hydroxybenzotriazole or a hindered phenolic antioxidant in an amount that is sufficient to stabilize said molding composition to the effects of ultraviolet light or to thermal oxidative embrittlement.

A composition as defined in claim 1 wherein the polyphenylene ether resin has structural units of the formula:

wherein Q is selected from the group consisting of hydrogen, hydrocarbon radicals, halohydrocarbon radicals having at least two carbon atoms between the halogen atom and the phenyl necleus, hydrocarbonoxy radicals and halohydrocarbonoxy radicals having at least two carbon atoms between the halogen and the phenyl nucleus, Q' and Q" are the same as Q and in addition halogen with the proviso that Q and Q' are both free of a tertiary carbon atom and n is an integer of at least 50.

A composition as defined in claim 2 which includes as a vinyl aromatic resin a resin having at least 25% of its units derived from monomers of the formula:

wherein R¹ and R² are selected from the group consisting of lower alkenyl groups of from 1 to 6 carbon atoms and hydrogen. R³, R⁴ and R⁵ are selected from the group consisting of chloro, bromo, hydrogen and (lower) alkyl of from 1 to 6 carbon atoms; R⁶ and R⁷ are selected from the group consisting of hydrogen and (lower) alkyl and alkenyl groups 1 to 6 carbon atoms to form a naphthyl group.

A composition as defined in claim 3 wherein the vinyl aromatic resin includes units derived from an α β-unsaturated cyclic anhydride of the formula:

wherein the dotted lines represent a single or a double carbon to carbon bond, R⁷ and R⁸ taken together represent a

linkage, R⁹ is selected from the group consisting of hydrogen, vinyl, alkyl, alkenyl, alkylcarboxylic acid or alkenylcarboxylic acid of from 1 to 12 carbons, n is 1 or 2, depending on the position of the carbon-carbon double bond and m is an integer of from 0 to about 10.

A composition as defined in claim 4 wherein the composition includes a reinforcing amount of a reinforcing filler.

A composition as defined in claim 4 wherein the composition includes a flame retardant amount of a flame retardant.

A stabilized molding composition which comprises:

(a) from 15 to 95 parts by weight of a polyphenylene ether resin;

(b) from 5 to 85 parts by weight of a vinyl aromatic resin; and

(c) from 0.05 to 5.0 parts by weight of the sebacic acid diester of 2,2,6, 6-tetramethyl-4-hydroxypiperidine.

A composition as defined in claim 7 wherein 0.1 to 0.5 parts of component (c) is present.

A composition as defined in claim 7 wherein the polyphenylene ether resin is poly (2,6-dimethyl-1,4-phenylene) ether and the vinyl aromatic resin is a rubber modified, high impact styrene resin.

A stabilized molding composition which comprises:

(a) from 60 to 99 parts by weight of a polyphenylene ether resin;

(b) 0-15 parts of a thermoplastic rubber

(c) 0-30 parts of a phosphate plasticizer

(d) from 0.1 to 5.0 parts by weight of the sebacic acid diester of 2,2,6, 6-tetramethyl-4-hydroxypiperidine.

(e) from 0.5 to 2 parts by weight of a phosphite compound. A composition as defined in claim 10 wherein the polyphenylene ether resin is poly (2,6-dimethyl-1,4-phenylene) ether resin and the phosphite compound is tridecyl phosphite. A composition as defined in claim 10 wherein the phosphate plasticizer is tri-phenylphosphate. A stabilized molding composition which comprises:

(a) from 15 to 95 parts by weight of a polyphenylene ether resin;

(b) from 5 to 85 parts by weight of the vinyl aromatic resin;

(c) from 0.05 to 5.0 parts by weight of the sebacic acid diester of 2 , 2 ,6 ,6-tetramethyl-4-hydrocypiperidine; and

(d) from 0.05 to 5.0 parts by weight of a hydroxybenzotriazole.

A composition as defined in claim 13 wherein the polyphenylene ether is poly (2,6-dimethyl-1,4-phenylene) ether and the vinyl aromatic resin is rubber modified, high impact poly-styrene. A composition as defined in claim 14 wherein the hydroxybenzotriazole is 2- (2H-benzotriazol-2-yl)-p-cresol. A composition as defined in claim 14 wherein the hydroxybenzotriazole is 2- (2H-benzotriazol-2-yl)-4,4-ditert-pentylphenol. A composition as defined in claim 14 wherein the hydroxybenzotriazole is 2-(2H-benzotriazol-2-yl)-4,6-di tert-butylphenol.