POLYPHENYLENE ETKER RESIN COMPOSITIONS CONTAINING POLYPENTENAMER

This invention relates to improved composi- tions of a polyphenylene ether resin containing poly¬ pentenamer. Reinforced and flame-retardant composi¬ tions are also provided.

Background of the Invention - The polypheny¬ lene ether resins are a family of engineering thermo- plastics that are well known to the polymer art. These polymers may be made by a variety of catalytic and non-catalytic processes from the corresponding phenols or reactive derivatives thereof. By way of illustra¬ tion certain of the polyphenylene ethers are disclos- ed in U.S. Patents 3,306,874; 3,306,875; 3,257,357 and 3,256,358. Polyphenylene ethers may be prepared by an oxidative coupling reaction comprising passing any oxygen-containing gas through a reaction solution of a phenol and metal-amine complex catalyst. Dis- closures relating to processes for preparing poly¬ phenylene ether resins, including graft copolymers of polyphenylene ethers with styrene type compounds, are found in U.S. Patents 3,356,761; British Patent 1,291,609; and U.S. Patents 3,337,892; 3,219,626; 3,342,892; 3,344,166; 3,384,619; 3,440,217; 3,661,848; 3,733,299; 3,383,102 and 3,988,297. Disclosures re¬ lating to metal based catalysts which do not include amines, are known from patents such as U.S. Patents 3,442,885 (copper-amidines) ; 3,573,257 (metal- alcholate or -phenolate) ; and 3,445,880 (cobalt che- late≤) . A non-catalytic process is described in

U.S. Patent 3,383,212. U.S. Patent 3,383,435 dis¬ closes polyphenylene ether-styrene resin compositions, All of the above-mentioned disclosures are incorporat¬ ed by reference. In the prior art, rubber-modified styrene resins have been admixed with polyphenylene ether resins to form compositions that have modified prop¬ erties. U.S. Patent 3,383,435, discloses rubber- modified styrene resin-polyphenylene ether resin compositions wherein the rubber component is of the unsaturated type such as polymers and copolymers of butadiene. The physical properties of these composi¬ tions are such that it appears that many of the properties of the styrene resins have been upgraded, while the moldability of the polyphenylene ethers are improved.

The conventional polymerization of conju¬ gated dienes yields rubber with the structure (CH=CH- CH2)£ _χ » with two methylene groups between each double bond. Recent development of procedures for ring-opening polymerization of cycloolefins has made it possible to prepare polyalkenamers having the general structure where n represents the number of carbon atoms in the cycloolefin ring, minus two. One of the polyalkenamers is of particu¬ lar interest. It has been found that polyphenylene ether resin compositions containing polypentenamer have improved impact strength.

Description of the Invention , In accordance with the invention there are provided compositions comprising:

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(a) a polyphenylene ether resin, and

(b) polypentenamer, or polypentenamer- modified alkenyl aromatic resin.

The compositions of this invention may also contain an alkenyl aromatic resin modified with polypentenamer or a rubber.

The preferred polyphenylene ethers are of the formula

Q wherein the oxygen ether atom of one unit is connect¬ ed to the benzene nucleus of the next adjoining unit, n is a positive integer and is at least 50, and each Q is a monovalent substituent selected from the group consisting of hydrogen, halogen, hydrocarbon radicals free of a tertiary alpha-carbon atom, halohydrocarbon radicals having at least two carbon atoms between the halogen atom and the phenyl nucleus, hydrocarbonoxy ra¬ dicals, and halohydrocarbonoxy radicals having at least two carbon atoms between the halogen atom and the phenyl nucleus, Examples of polyphenylene ethers correspond¬ ing to the above formula can be found in the above- referenced patents. Especially preferred is poly (2,6-dimethyl-l,4-phenylene) ether.

Polypentenamer is produced by a ring ex- pansion polymerization of cyclopentene. For example, the ring expansion polymerization of cyclopentene

results in a polymer of formula

wherein m is at least 30. See, for example, "Rubber Reviews For 1974", Rubber Chemistry and Technology, Vol. 47, pages 511-596.

Polypentenamer can have either a cis or trans steric configuarion, and a useful polypentena¬ mer will probably be comprised of both cis and trans configurations. For example, a polypentenamer obtain¬ ed from Goodyear Tire and Rubber Co. contains 80% trans and 20% cis.

The alkenyl aromatic resin should have at least 35% of its unit o- matic monomer of the

wherein Rl and R2 are sist¬ ing of hydrogen and lower alkyl or alkenyl groups of from 1 to 6 carbon atoms; R 3 and R4 are selected frou the group consisting of chloro, bromo, hydrogen, and loweralkyl groups of from 1 to 6 carbon atoms; and R and R are selected from the group consisting of hydro¬ gen and lower alkyl and alkenyl groups of from 1 to 6 carbon atoms or R and R may be concatenated together with hydrocarbyl groups to form a naphthyl group.

Specific examples of alkenyl aromatic mono- mer include styrene, bromostyrene,O^-methy1styrene, vinylxylene, divinylbenzene, vinyl naphthalene and vinyl-toluene.

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The alkenyl aromatic monomer may be copoly- merized with materials such as these having the general formula - ^■ &

R ⁷ --C(H) _n t - - - (CH ₂ ) _τ - -Rr ^>9 ' m wherein the dotted lines each represent a single or

7 8 a double carbon to carbon bond; R and R taken together represent a Q 0

0 0 C linkage, R is selected from the group consisting of hydrogen, vinyl, alkyl of from 1 to 12 carbon atoms , alkenyl of from 1 to 12 carbon atoms, alkylcarboxylic acid of from 1 to 12 carbon atoms, and alkenylcarboxylic acid 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 anydride and aconotic anhydride.

The alkenyl resins include, by way of example, homopolymers such as homopolystyrene and poly(chloro- styrene), and styrene-containing copolymers, such as styrene-chlorostyrene copolymers, styrene-bromosty- rene copolymers , the styrene acrylonitrile - - -alkyl styrene copolymers, styrene-acrylonitrile copolymers, styrene butadiene copolymers, styrene-acrylonitrile butadiene copolymers, poly-oζ-me hy1styrene, copolymers of ethylvinylbenzene, divinylbenzene, and styrene maleic anhydride copolymers, and block copolymers of styrene butadience and styrene-butadiene styrene.

The styrene-maleic anhydride copolymers are described in U.S. Patents 3,971,939; 3,336,267 and 2,769,804, all of which are incorporated herein by reference.

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The alkenyl aromatic resin can be modified with rubbers or polypentenamer. Among the rubbers which can be employed are natural and synthetic elas¬ tomers, such as diene rubbers, e.g., polybutadiene and polyisoprene. Moreover, the rubbers can comprise random, block and interpolymers of conventional types, e.g., butadiene-styrene copolymers and styrene-buta- diene styrene block copolymers.

The alkenyl aromatic resins are modified with a rubber or polypentenaπ_er by polymerizing the al¬ kenyl aromatic monomer in the presence of the rubber or polypentenamer.

The components of the composition of this . invention are combinable in a fairly wide range of proportions.. Preferably, compositions comprised of a polyphenylene ether resin and polypentenamer will comprise from about 1 to 99 parts by weight of polyphenylene ether resin, and from about 1 to 99 parts by weight of polypentenamer based on the total weight of the composition. Compositions comprised of a polyphenylene ether resin, a rubber-modified alkenyl aromatic resin, and polypentenamer will preferably be comprised from about 10 to 90 parts by weight of polyphenylene ether resin, from about 90 to 10 parts by weight of rubber-modified alkenyl aromatic resin, and from about 1 to 50 parts by weight of polypente¬ namer, based on the total weight of the composition. Compositions comprised of apolyphenylene ether resin and polypentenamer-modified alkenyl aromatic resin will preferably comprise from about 10 to 99

parts by weight of polyphenylene ether resin and from about 1 to 90 parts by weight of polypentenamer-modi¬ fied alkenyl aromatic resin, based on the total weight of the composition. The modified alkenyl aromatic resin can con¬ tain from about 4 to 757o of rubber or polypentenamer as modifier.

Compositions comprised of polypentenamer- modified alkenyl aromatic resin have particularly good impact strength if a small amount of polyphenylene ether resin, about 1 to 257o by weight, based on the total amount of polypentenamer and styrene present is added to the polymerization mixture after phase in- verson. When polyphenylene ether resin is added before phase inversion, the rubber particles in the product are large, and the final compositions containing poly¬ phenylene ether resin have lower impact strength.

The composition of the invention can also in¬ clude other ingredients, such as flame retardants, ex- tenders, processing aids, pigments, stabilizers, plasti- cizers, fillers such as mineral fillers and glass flakes and fibers, and the like. In particular, re¬ inforcing fillers, in amounts sufficient to impart re¬ inforcement, can be used, e.g., aluminum, iron, nickel, carbon filaments, silicates, such as acicular calcium silicate, asbestos, titanium dioxide, potassium tita- nate and titanate whiskers and glass flakes and fibers. It is to be understood that, unless the filler adds to the strength and stiffness of the composition, it is only a filler and not a reinforcing filler as con¬ templated herein. In particular, the reinforcing fil¬ lers increase the flexural strength, the flexural modulus, the tensile strength and the heat distortion

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temperature.

Although it is only necessary to have at least a reinforcing amount of the reinforcement present, in general, the filler will comprise from about 10 to about 90 parts by weight of the total composition. In general, the best properties will be ob¬ tained if the sized filamentous glass reinforcement comprises from about 1 to about 80% by weight based on the combined weight of glass, and polymers and preferably from about 10 to about 50% by weight. Es¬ pecially preferably the glass will comprise from about 10 to about 40% by weight based on the combined weight of glass and resin. Generally, for direct molding use, up to about 60% of glass can be present without caus- ing flow problems. However, it is useful also to pre¬ pare the compositions containing substantially great¬ er quantities, e.g., up to 70 to 80% by weight of glass. These concentrates can then be custom blended with resin compositions that are not glass reinforced to provide any desired glass content of a lower value.

Because it has been found that certain com¬ monly used flamable sizings on the glass, e.g., dex- trinized starch or synthetic polymers, contribute fla - mability often in greater proportion than expected from the amount present, it is preferred to use light¬ ly sized or unsized glass reinforcements in those compositions of the present invention which are flame- retardant. Sizings, if present, can readily be re¬ moved by heat cleaning or other techniques well known to those skilled in the art.

It is also a feature of this invention to provide flame-re ardant thermoplastic compositions, as defined above, by modifying the compositions to include a flame-retardant additive in a minor proportion but in an amount at least sufficient to render the com¬ positions non-burning or self-extinguishing. The flame-retardant additives useful in this invention com¬ prise a family of chemical compounds well known to those skilled in the art. Such flame-retardant additives include a halogenated organic compound, a halogenated organic compound in admixture with an antimony com¬ pound, elemental phosphorus, a phosphorus compound, compounds containing phosporus -nitrogen bonds, or a mixture of two or more of the foregoing. Especially preferred are decabromodiphenyl ether or hexabromodiphenyl ether, alone or mixed with antimony oxide.

The preferred phosphates are trixylylphos- phate, tert-butyl-phenyldiphenyl phosphate, and tri- phenyl phosphate. It is also preferred to use tri- phenyl phosphate in combination with decabromodiphenyl ether and, optionally, antimony oxide. Expecially preferred is a composition comprised of mixed triaryl phosphates with one or more isopropyl groups on some or all of the aryl rings, such as Kronitex 50 supplied by Food Machinery Corporation.

In general, however, the amount of flame- redardant additive will be from about 0.5 to 50 percent by weight based on the total weight of the composition. A preferred range will be from about 1 to 25 percent by weight, and an especially preferred range will be from about 3 to 15 percent by weight. Smaller amounts

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of compounds highly concentrated in the elements responsible for flame-retardance will be sufficient, e.g., elemental red phosphorus will be preferred at about 0.5 to 10 percent by weight based on the weight of the total composition, while phosphorus in the form of triphenyl phosphate will be used at about 3 to 25 percent by weight, and so forth.

The composition of the invention may be formed by conventional techniques, that is, by first dry mix- ing the components to form a premix, and then passing the premix through an extruder at an elevated tempera¬ ture, e.g., 425 to 640'F (218 to 338'C). Compounding should be carried out to insure that the residence time in the machine is short; that the temperature is carefully controlled; that the frictional heat is utilized; and that an intimate mixture between the resins and the additives is obtained.

Description of the Preferred Embodiment

The following examples are set forth as further il- lustration of the invention and are not to be construed as limiting the invention thereto.

Example I A composition comprising a 78:22 ratio of polyphenylene ether resin (PPO) to triphenyl phosphate was prepared by mixing 585 g of PPO, 165 g of triphenyl phosphate, 3.8 g of tridecyl phosphite, 1.1 g of zinc sulfide, and 1.1 g of zinc oxide and then extruding the mixture with a 28 mm twin-screw extruder. The extruded pellets were then molded into standard test pieces on a 3 oz. Newbury screw injection molding machine.

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PPO and polypentenamer (80% trans, 20% cis, available fromGoϊdyear Tire and Rubber Co.) were dis¬ solved in toluene and coprecipitated with methanol to yield a product comprised of 90% by weight PPO and 10% by weight polypentenamer. Three hundred grams of the coprecipitated composition, 170 g of PPO, 124 g of triphenyl phosphate, 2.85 g of tridecyl phos¬ phite, 0.8 g of zinc sulfide, and 0.8 zinc oxide were mixed together to form a mixture having approx¬ imately the same ration of PPO to triphenyl phosphate as the first composition. The mixture was extruded and standard test pieces were formed as above.

Physical properties of the composition were as follows:

PROPERTY CONTROL EXAMPLE I* Elongation (%) 77 82 Tensile Yield (psi) (10,500)740 (9,600)675 kg/cm Tensile Strength (psi) (8,600) 605 (9,400) ₆₀₀ kg/cm

Izod Impact (ft. lbs./in.) (0.8) 4.4 (3.1) 16.9 kg-cm/cm Gardner Impact (in. lbs.) (30) 34.5 (225) 259 cm-kg Heat Distortion Temp. (*F) (188) 86.7 (200) 93.3 «C

* Containing 6.2 parts of polypentenamer per hundred parts of PPO plus polypentenamer. It can be seen from the above that the com¬ position containing polypentenamer had improved pro¬ perties, particularly impact strength, as compared to the control.

Example II A 35:65 composition of PPO and rubber-modi¬ fied polystyrene was prepared as described in Example I, from 350 g of PPO, 650 g of FG-834 (a polybutadiene- modified polystyrene available from Foster Grant Co.), 70 g of triphenyl phosphate, 5 g of tridecyl phosphite, 1.5 g of zinc sufide, and 1.5 g of zinc oxide. A second composition having the same ratio of PPO to polystyrene was prepared from 350 g of a 90:10 co- precipitated PPO and polypentenamer mixture, 540 g of FG-834, 62.3 of triphenyl phosphate, 4.5 g of tri¬ decyl phosphite, 1.3 g of zinc sufide, and 1.3 g of zinc oxide. The composition made without polypentenamer bad Izod impact strength of 30.5 kg-cm/cm (5.6 ft. lbs./ in.); the composition containing 3.9 parts per hundred parts of polypentenamer had Izod impact strength of 41.3 kg-cm/cm) (7.6 ft. lbs./in.).

Example III One hundred grams of polypentenamer was dis- solved in 1150 g of styrene, 1.2 g of tert-butyl pera- cetate was added, and the solution was transferred to a one gallon stainless steel reactor, stirred by a 8.9 cm x 1.3 cm (3 1/2" by 1/2") six blade turbine stirrer. The mixture was stirred at 800 rpm and heated at 100 C . After three hours at this temperature 8 g of tert-butyl peroxide was added, and the mixture was suspended in 1500 ml of water containing 4 g of poly (vinyl alcohol) and 3 g of gelatin. Polymerization was completed by heating the suspension for one hour at 100 C, two hours at 120 ^P C, one hour at 140*fc, and then 2 1/2 hours at 155*C. The mixture was cooled,

and the beads of modified polystyrene were filtered off, washed with water, and dried.

Example IV One hundred grams of polypentenamer and 900 g of polystyrene were polymerized as described in Example III.

Example V One hundred grams of polypentenamer and 900 g of polystyrene were polymerized by the procedure described in Example III, except that the stirrer speed was increased to 1600 rpm. After three hours at 100 °C , 100 g of PPO (I.V. = 0.38 dl/g) was added. The solution was stirred for 15 minutes and then sus¬ pended and the polymerization was completed by the heating schedule.described in Example III.

Example VI Polymerization was carried out as des¬ cribed in Example V, except that the PPO was added immediately after the beginning of the reaction, as soon as the reaction temperature reached 90*C. The reactor was then sealed and the temperature was in¬ creased to 100*O. After three hours at this tempera¬ ture, the mixture was suspended, and polymerization completed as described in Example III. The polymers prepared according to Examples

III to VI were evaluated for particle size, gel con¬ tent, and swell index by use of the procedures des¬ cribed in commonly assigned, U.S. patent application Serial No. 787,253, filed April 13, 1977, incorporat- ed herein by reference. The results were as follows:

Table 2.

Exaπple Polypentenamer PPO Added Particle Size Gel Swell by weight) (microns) i%L Index 1 1

III 8 None 1.1 30.5 11.6

IV 10 None 1.1 34.9 7.6

V 10 After Phase 1.1 21.7 10.4 Inversion

VI 10 Before Phase 4.0 32.2 12.7 Inversion

Example VII Three hundred grams of the polymer produced in Example III, 200 g of PPO, 6 g of Tridecyl phos¬ phite, 18 g of triphenyl phosphate, 0.9 g of zinc sulfide, and 0.9 g of zinc oxide were mixed and ex¬ truded at 30.2*C (575 ^β F) in a 28mm twin-screw ex¬ truder. The pellets were molded at 260 °C (500*^) into standard test pieces in a screw injection molding machine. The polymers produced in Examples IV, V and VI were similarly extruded and molded, except that with the polymers of Examples V and VI the quantities were changed to 224 g of PPO and 276 g of polystyrene to maintain the samePPO-polystyrene ratio . as in Example IV. Properties of the compositions are listed in Table 3.

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Table 3.

Example Elongation Tensile Yield Tensile Strength Ino Impact Gardner Impact

2 2 (ft.lbs./in.) % (psi) kg/cm (psi) kg/cm kg-cm/cπi (iii.lbϊ ^j ) cm-kg i

III 55 (11,800) 830 (8,200) 575 (1.2) 6.5 (175) 202 '

IV 56 (10,800) 759 (9,200) 647 (1.7) 9.2 (275) 317

V 50 (11,000) 773 (8,400) 591 (4.1) 22.3 (275) 317

VI 69 (11,200) 787 (9,500) 668 (1.8) 9.8 (125) 144

As shown in Table 3, the composition of Ex¬ ample V, wherein PPO was added after phase inversion, had the best impact strength.