Claims
- 1. A composition comprising polyphenylene etherpolyester copolymers prepared by the reaction of an epoxytriazine-capped polyphenylene ether with at least one condensation polymer containing carboxy end groups.
- 2. A composition according to claim 1 wherein the condensation polymer is an elastomeric copolyesteramide.
- 3. A composition according to claim 1 wherein the condensation polymer is a polyester comprising structural units of the formula ##STR14## wherein each R.sup.4 is independently a divalent aliphatic, alicyclic or aromatic hydrocarbon radical or polyoxyalkylene radical and A.sup.1 is a divalent aromatic radical.
- 4. A composition according to claim 2 wherein the polyphenylene ether comprises a plurality of structural units having the formula ##STR15## wherein each Q.sup.1 is independently halogen, primary or secondary lower alkyl, phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Q.sup.2 is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or halohydrocarbonoxy as defined for Q.sup.1.
- 5. A composition according to claim 4 wherein A.sup.1 is p- or m-phenylene or a mixture thereof.
- 6. A composition according to claim 5 wherein the polyphenylene ether is a poly(2,6-dimethyl-1,4-phenylene ether).
- 7. A composition according to claim 6 wherein R.sup.1 is methylene and A.sup.1 is p-phenylene.
- 8. A composition according to claim 7 wherein R.sup.4 is ethylene.
- 9. A composition according to claim 7 wherein R.sup.4 is tetramethylene.
- 10. A composition according to claim 7 wherein R.sup.4 is polyoxytetramethylene.
- 11. A composition according to claim 7 wherein the polyester also contains units of the formula ##STR16## wherein R.sup.5 is a polyoxyalkylene radical and A.sup.2 is a trivalent aromatic radical.
Parent Case Info
This application is a continuation-in-part of copending application Serial No. 210,266, filed June 23, 1988, now abandoned.
This invention relates to the preparation of polyphenylene ether-polyester copolymers.
The polyphenylene ethers are a widely used class of thermoplastic engineering resins characterized by excellent hydrolytic stability, dimensional stability, toughness, heat resistance and dielectric properties. However, they are deficient in certain other properties such as workability and solvent resistance. Therefore, there is a continuing search for means for modifying polyphenylene ethers to improve these other properties.
A disadvantage of the polyphenylene ethers which militates against their use for molding such items as automotive parts is their low resistance to non-polar solvents such as gasoline. For increased solvent resistance, it would be desirable to form compositions in which polyphenylene ethers are combined with resins which have a high degree of crystallinity and therefore are highly resistant to solvents. Illustrative of such resins are the thermoplastic polyesters including poly(alkylene dicarboxylates), especially the poly(alkylene terephthalates). Other reasons exist for forming compositions comprising polyphenylene ethers and other polymers containing carboxy end groups, especially such polyesters as polyarylates and elastomeric polyesters.
However, polyphenylene oxide-polyester blends frequently undergo phase separation and delamination. They typically contain large, incompletely dispersed polyphenylene ether particles and no phase interaction between the two resin phases. Molded parts made from such blends are typically characterized by extremely low impact strength, brittleness, delamination and the like.
Numerous methods for compatibilizing polyphenylene ether-polyester compositions have been developed. For example, PCT published application 87/850 describes blends compatibilized by the addition of an aromatic polycarbonate. Said blends are extremely versatile in numerous critical applications such as the fabrication of automobile body parts. However, the presence of polycarbonate may result in degradation of certain other properties such as heat distortion temperature.
In addition, a problem sometimes arises by virtue of the presence of aminoalkyl-substituted end groups on certain commercially available polyphenylene ethers, as described in more detail hereinafter. For optimum impact strength, it is frequently necessary to remove said aminoalkyl-substituted end groups and other amine constituents frequently present as impurities in the polyphenylene ether. Such expedients as the use of amine quenchers and/or vacuum venting of the polyphenylene ether are effective in decreasing amino nitrogen content, but add a step to the processing operation which may be undesirable under certain circumstances.
Various methods are also known for preparing copolymers of polyphenylene ethers with polyesters. Such copolymers are often effective as compatibilizers for blends of the same resins. To facilitate copolymer formation, it is frequently advisable to employ a polyphenylene ether containing functional groups. For example, epoxy groups can react with such nucleophilic groups in polyesters and polyamides as amino, hydroxy and carboxy groups, leading to copolymer formation.
Several methods of preparing epoxy-functionalized polyphenylene ethers are disclosed in various patents and publications. For example, U.S. Pat. No. 4,460,743 describes the reaction of a polyphenylene ether with epichlorohydrin, to produce an epoxy-functionalized polymer. However, this method requires dissolution of the polyphenylene ether in a large excess of epichlorohydrin, a relatively expensive reagent which is also a strong skin irritant and can cause kidney injury.
PCT published application 87/7279 describes the reaction of polyphenylene ethers with terephthaloyl chloride and glycidol to form an epoxy-functionalized polyphenylene ether useful, for example, for the preparation of copolymers with polyesters, but copolymer formation with polyesters by this method requires a solution reaction in relatively expensive and high boiling solvents such as trichlorobenzene and is very slow.
In the same application are described reactions of various epoxy-functionalized ethylenic monomers such as glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether with polyphenylene ethers in the presence of free radical initiators. The resulting epoxy-functionalized materials are useful as intermediates for the preparation of copolymers by melt reaction with polyamides. However, functionalization of the polyphenylene ether by this method most often requires large quantities of the monomer, and certain of such monomers, including glycidyl methacrylate, are toxic. Moreover, the reaction is generally accompanied by homopolymerization of the epoxy-functionalized monomer, and it is then necessary to remove the homopolymer by such complicated operations as dissolution of the crude polymeric product followed by formation and decomposition of a polyphenylene ether-methylene chloride complex. Thus, these materials may hot be readily adaptable to copolymer preparation on an industrial scale.
The present invention provides compositions comprising polyphenylene ether-polyester copolymers formed from highly reactive epoxy-functionalized polyphenylene ethers which may be prepared under simple solution or interfacial conditions using relatively inexpensive reagents. Said compositions have excellent physical properties, particularly when blended with conventional impact modifiers for polyphenylene ethers. They also compatibilize blends containing unfunctionalized polyphenylene ethers.
Accordingly, the invention includes compositions comprising polyphenylene ether- copolymers prepared by the reaction of an epoxytriazine-capped polyphenylene ether with at least one condensation polymer containing carboxy end groups.
Epoxytriazine-capped polyphenylene ethers suitable for use in the preparation of the compositions of this invention, as well as methods for their preparation, are disclosed and claimed in copending, commonly owned application Ser. No. 351,905, filed May 15, 1989. They comprise polymer molecules having end groups of the formula ##STR1## wherein: each Q.sup.1 is independently halogen, primary or secondary lower alkyl (i.e., alkyl containing up to 7 carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms;
R.sup.1 is a divalent aliphatic, alicyclic, heterocyclic or unsubstituted or substituted aromatic hydrocarbon radical.
Said epoxytriazine-capped polyphenylene ethers may be prepared as described hereinafter from the polyphenylene ethers known in the art. The latter encompass numerous variations and modifications all of which are applicable to the present invention, including but not limited to those described hereinafter.
The polyphenylene ethers comprise a plurality of structural units having the formula ##STR3## and in each of said units independently, each Q.sup.1 Q.sup.2 is as suitable as Q.sup.1 and Q.sup.2 are methyl, ethyl, n-propyl, n-butyl, isobutyl, n-amyl, isoamyl, 2-methylbutyl, n-hexyl, 2,3-dimethylbutyl, 2-, 3- or 4-methylpentyl and the corresponding heptyl groups. Examples of secondary lower alkyl groups are isopropyl, sec-butyl and sec-butyl and 3-pentyl. Preferably, any alkyl radicals are straight chain rather than branched. Most often, each Q.sub.1 is alkyl or phenyl, especially C.sub.1-4 alkyl, and each Q.sub.2 is hydrogen. Suitable polyphenylene ethers are disclosed in a large number of patents.
Both homopolymer and copolymer polyphenylene ethers are included. Suitable homopolymers are those containing, for example, 2,6-dimethyl-1,4-phenylene ether units. Suitable copolymers include random copolymers containing such units in combination with (for example) 2,3,6-trimethyl-1,4-phenylene ether units. Many suitable random copolymers, as well as homopolymers, are disclosed in the patent literature.
Also included are polyphenylene ethers containing moieties which modify properties such as molecular weight, melt viscosity and/or impact strength. Such polymers are described in the patent literature and may be prepared by grafting onto the polyphenylene ether in known manner such vinyl monomers as acrylonitrile and vinylaromatic compounds (e.g., styrene), or such polymers as polystyrenes and elastomers. The product typically contains both grafted and ungrafted moieties. Other suitable polymers are the coupled polyphenylene ethers in which the coupling agent is reacted in known manner with the hydroxy groups of two polyphenylene ether chains to produce a higher molecular weight polymer containing the reaction product of the hydroxy groups and the coupling agent, provided substantial proportions of free hydroxy groups remain present. Illustrative coupling agents are low molecular weight polycarbonates, quinones, heterocycles and formals.
The polyphenylene ether generally has a number average molecular weight within the range of about 3,000-40,000 and a weight average molecular weight within the range of about 20,000-80,000, as determined by gel permeation chromatography. Its intrinsic viscosity is most often in the range of about 0.15-0.6 dl./g., as measured in chloroform at 25.degree. C.
The polyphenylene ethers are typically prepared by the oxidative coupling of at least one corresponding monohydroxyaromatic compound. Particularly useful and readily available monohydroxyaromatic compounds are 2,6-xylenol (wherein each Q.sup.1 is methyl and each Q.sup.2 is hydrogen), whereupon the polymer may be characterized as a poly(2,6-dimethyl-1,4-phenylene ether), and 2,3,6-trimethylphenol (wherein each Q.sup.1 and one Q.sup.2 is methyl and the other Q.sup.2 is hydrogen).
A variety of catalyst systems are known for the preparation of polyphenylene ethers by oxidative coupling. There is no particular limitation as to catalyst choice and any of the known catalysts can be used. For the most part, they contain at least one heavy metal compound such as a copper, manganese or cobalt compound, usually in combination with various other materials.
A first class of preferred catalyst systems consists of those containing a copper compound. Such catalysts are disclosed, for example, in U.S. Pat. Nos. 3,306,874, 3,306,875, 3,914,266 and 4,028,341. They are usually combinations of cuprous or cupric ions, halide (i.e., chloride, bromide or iodide) ions and at least one amine.
Catalyst systems containing manganese compounds constitute a second preferred class. They are generally alkaline systems in which divalent manganese is combined with such anions as halide, alkoxide or phenoxide. Most often, the manganese is present as a complex with one or more complexing and/or chelating agents such as dialkylamines, alkanolamines, alkylenediamines, o-hydroxyaromatic aldehydes, o-hydroxyazo compounds, .omega.-hydroxyoximes (monomeric and polymeric), o-hydroxyaryl oximes and .beta.-diketones. Also useful are known cobalt-containing catalyst systems. Suitable manganese and cobalt-containing catalyst systems for polyphenylene ether preparation are known in the art by reason of disclosure in numerous patents and publications.
The polyphenylene ethers which may be employed for the purposes of this invention include those which comprise molecules having at least one of the end groups of the formulas ##STR4## wherein Q.sup.1 and Q.sup.2 are as previously defined; each R.sup.2 is independently hydrogen or alkyl, with the proviso that the total number of carbon atoms in both R.sup.2 radicals is 6 or less; and each R.sup.3 is independently hydrogen or a C.sub.1-6 primary alkyl radical. Preferably, each R.sup.2 is hydrogen and each R.sup.3 is alkyl, especially methyl or n-butyl.
Polymers containing the aminoalkyl-substituted end groups of formula IV are typically obtained by incorporating an appropriate primary or secondary monoamine as one of the constituents of the oxidative coupling reaction mixture, especially when a copper- or manganese-containing catalyst is used. Such amines, especially the dialkylamines and preferably di-n-butylamine and dimethylamine, frequently become chemically bound to the polyphenylene ether, most often by replacing one of the .alpha.-hydrogen atoms on one or more Q.sup.1 radicals The principal site of reaction is the Q.sup.1 radical adjacent to the hydroxy group on the terminal unit of the polymer chain. During further processing and/or bending, the aminoalkyl-substituted end groups may undergo various reactions, probably involving a quinone methide-type intermediate of the formula ##STR5## with numerous beneficial effects often including an increase in impact strength and compatibilization with other blend components. Reference is made to U.S. Pat. Nos. 4,054,553, 4,092,294, 4,477,649, 4,477,651 and 4,517,341, the disclosures of which are incorporated by reference herein.
Polymers with 4-hydroxybiphenyl end groups of formula V are often especially useful in the present invention. They are typically obtained from reaction mixtures in which a by-product diphenoquinone of the formula ##STR6## is present, especially in a copper-halide-secondary-or tertiary amine system. In this regard, the disclosure of U.S. Pat. No. 4,477,649 is again pertinent as are those of U.S. Pat. Nos. 4,234,706 and 4,482,697, which are also incorporated by reference herein. In mixtures of this type, the diphenoquinone is ultimately incorporated into the polymer in substantial proportions, largely as an end group.
In many polyphenylene ethers obtained under the above-described conditions, a substantial proportion of the 90% by weight of the polymer, contain end groups having one frequently both of formulas IV and V. It should be understood, however, that other end groups may be present and that the invention in its broadest sense may not be dependent on the molecular structures of the polyphenylene ether end groups. It is, however, required that a substantial proportion of free, non-hydrogen bonded hydroxy groups be present; that is, that a substantial proportion of hydroxyterminated end groups have structures other than that of formula IV.
The use of polyphenylene ethers containing substantial amounts of unneutralized amino nitrogen may afford compositions with undesirably low impact strengths. The possible reasons for this are explained hereinafter. The amino compounds include, in addition to the aforementioned aminoalkyl end groups, traces of amine (particularly secondary amine) in the catalyst used to form the polyphenylene ether.
The present invention therefore includes the use of polyphenylene ethers in which a substantial proportion of amino compounds has been removed or inactivated. Polymers so treated contain unneutralized amino nitrogen, if any, in amounts no greater than 800 ppm. and more preferably in the range of about 100-800 ppm.
A preferred method of inactivation is by extrusion of the polyphenylene ether at a temperature within the range of about 230.degree.-350.degree. C., with vacuum venting. This is preferably achieved in a preliminary extrusion step, by connecting the vent of the extruder to a vacuum pump capable of reducing the pressure to about 200 torr or less. There may also be advantages in employing vacuum venting during extrusion of the composition of this invention.
It is believed that this inactivation method aids in the removal by evaporation of any traces of free amines (predominantly secondary amines) in the polymer, including amines generated by conversion of aminoalkyl end groups to quinone methides of the type represented by formula VI.
It will be apparent to those skilled in the art from the foregoing that the polyphenylene ethers contemplated for use in the present invention include all those presently known, irrespective of variations in structural units or ancillary chemical features.
The end groups on the epoxytriazine-capped polyphenylene ethers have formula I, in which Q.sup.1 and Q.sup.2 are as previously defined. X may be an alkyl or cycloalkyl radical, typically lower alkyl and especially primary or secondary lower alkyl; an aromatic radical, typically monocyclic and containing 6-10 carbon atoms and especially an aromatic hydrocarbon radical; or a radical of formula II. In formulas I and II, R.sup.1 may be aliphatic, alicyclic, aromatic (including aromatic radicals containing art-recognized substituents) or heterocyclic. It is usually lower alkylene and especially methylene.
The above-described epoxytriazine-capped polyphenylene ether compositions may be prepared by contacting under reactive conditions, in the presence of a basic reagent, at least one polyphenylene ether with an epoxychlorotriazine of the formula ##STR7##
wherein R.sup.1 and X are as previously defined.
Typical epoxychlorotriazines of formula VIII include 2-chloro-4,6-diglycidoxy-1,3,5-triazine (hereinafter "DGCC"), 2-chloro-4-methoxy-6-glycidoxy-1,3,5-triazine,2-chloro-4-(n-butoxy)-6-glycidoxy-1,3,5-triazine (hereinafter "BGCC") and 2-chloro-4-(2,4,6-trimethylphenoxy)-6-glycidoxy1,3,5-triazine (hereinafter "MGCC"). These compounds may also be named as though derived from cyanuric acid and DGCC, BGCC and MGCC may be designated diglycidyl chlorocyanurate, n-butyl glycidyl chlorocyanurate and 2,4,6-trimethylphenyl glycidyl chlorocyanurate, respectively. They may be prepared, for example, by the reaction of 2,4,6-trichlorotriazine (cyanuric chloride) with glycidol or combinations thereof with n-butanol or mesitol. Cyanuric chloride and n-butyl dichlorocyanurate are both commercially available.
Intermediates such as DGCC, BGCC and MGCC and the method for their preparation are disclosed and claimed in copening, commonly owned application Ser. No. 144,901, filed Jan. 19, 1988, now U.S. Pat. No. 4,895,945.
US Referenced Citations (2)
| Number |
Name |
Date |
Kind |
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4732937 |
Sybert |
Mar 1988 |
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4895945 |
Bown et al. |
Jan 1990 |
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Continuation in Parts (1)
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Number |
Date |
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| Parent |
210266 |
Jun 1988 |
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Patent Grant
5089566
