Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-05-31
2003-04-22
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C528S206000, C528S218000
Reexamination Certificate
active
06552133
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to polyphenylene ethers, and more particularly to functionalized polyphenylene ethers useful for the compatibilization of copolymer blends.
Polyphenylene ethers are a widely used class of thermoplastic engineering resins characterized by excellent properties including hydrolytic stability, dimensional stability, toughness, heat resistance and dielectric properties. It is of continuing interest to introduce these desirable properties into polymer blends by incorporating the polyphenylene ethers as blend constituents. This is often difficult, however, since the polyphenylene ethers are incompatible with many other polymers.
A strategy frequently used to compatibilize polyphenylene ethers with other polymers is to introduce into the polyphenylene ether functional groups which are reactive with said other polymers, enabling the formation of copolymer-containing compositions in which the copolymers serve as compatibilizers. For example, polyphenylene ethers containing carboxylic acid functional groups or derivatives thereof can form copolymers with such other polymers as polyamides, hydroxy-terminated polyesters and epoxy group-containing polymers.
Carboxy or carboxy-derived groups (e.g., anhydride groups) have been introduced into polyphenylene ethers by reaction through the hydroxy end groups with such compounds as trimellitic anhydride acid chloride, by grafting reactions with such compounds as maleic anhydride or fumaric acid, and by redistribution with acidic compounds such as p-hydroxyphenylacetic acid. Redistribution reactions are often of particular interest since they may be conducted under relatively mild conditions, typically including temperatures not substantially greater than 100° C. and the presence of non-destructive catalysts such as diaryl peroxides and quinones and relatively inert solvents such as toluene. The redistribution reaction results in a breakup of polymer molecules into lower molecular weight molecules containing the desired carboxylic acid or other functional groups.
Redistribution with the aforementioned acidic compounds is somewhat difficult, however, since said compounds are not adequately soluble in solvents such as toluene. Moreover, the mechanism of the redistribution reaction is such that only low levels of such compounds can be incorporated in the polyphenylene ether, owing in part to substitution in the para position which makes that position unavailable for reaction.
U.S. Pat. No. 5,880,221 discloses attempts at redistribution of polyphenylene ethers with various aryl-substituted alkanoic acids. It was found that whereas carboxy phenols bearing two phenolic hydroxyl groups and alkyl substituents ortho to the phenolic hydroxy groups, such as 4,4-bis(3,5-dimethyl-4-hydroxyphenyl)pentanoic acid, did incorporate, simple phenols such as p-hydroxyphenyloctanoic acid did not. Interest continues, therefore, in the development of improved functionalization strategies employing other carboxylic acids, especially those of simpler molecular structure than the aforementioned bisphenolic acid.
Japanese Kokai 5/59,270 and 5/59,272 disclose reaction products of epoxy- and carboxy-functionalized olefin polymers with copolyphenylene ethers in which a portion of the structural units contain a —(CH
2
)
3
OH group. Said copolyphenylene ethers are produced by copolymerization via oxidative coupling of two phenols, one containing and one not containing said group. There is no disclosure of a copolyphenylene ether containing a carboxyalkyl group.
SUMMARY OF THE INVENTION
The present invention is based on the discovery that certain o-hydroxyaromatic-substituted aliphatic carboxylic acids are capable of incorporation under mild conditions into polyphenylene ethers, either by copolymerization or by redistribution. The conditions employed include use of a single solvent in which the polyphenylene ether has high solubility.
One aspect of the invention, therefore, is carboxy-functionalized polyphenylene ethers comprising structural units of the formulas
wherein each Q
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; each Q
2
and Q
3
is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or halohydrocarbonoxy as defined for Q
1
; and R is an alkylene radical containing at least 1 carbon atom.
A further aspect of the invention is a method for preparation of such functionalized polyphenylene ethers which comprises redistributing a polyphenylene ether with a 2-carboxyalkylphenol of appropriate formula (corresponding to formula II) in the presence of a redistribution catalyst.
Another aspect of the invention is a method for production of such functionalized polyphenylene ethers which comprises oxidatively coupling at least one monohydroxyaromatic compound with said 2-carboxyalkyiphenol.
These carboxy-functionalized polyphenylene ethers are reactive and readily form copolymers with other reactive polymers. Therefore, a still further aspect of the invention is resinous compositions comprising copolymers of said functionalized polyphenylene ethers with at least one polymer containing carboxylic acid-reactive functional groups.
DETAILED DESCRIPTION; PREFERRED EMBODIMENTS
The polyphenylene ethers which are functionalized according to the invention are known polymers having structural units of formula I. Both homopolymer and copolymer polyphenylene ethers are included. The preferred homopolymers are those containing 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. Also included are polyphenylene ethers containing moieties prepared by grafting onto the polyphenylene ether in known manner such materials as vinyl monomers or polymers such as polystyrenes and elastomers, as well as coupled polyphenylene ethers in which coupling agents such as low molecular weight polycarbonates, quinones, heterocycles and formals undergo reaction in known manner with the hydroxy groups of two polyphenylene ether chains to produce a higher molecular weight polymer, provided a substantial proportion of free OH groups remains.
The polyphenylene ethers generally have an intrinsic viscosity greater than about 0.25, most often in the range of about 0.25-0.6 and especially 0.4-0.6 dl./g., as measured in chloroform at 25° C.
The polyphenylene ethers are typically prepared by the oxidative coupling of at least one monohydroxyaromatic compound such as 2,6-xylenol or 2,3,6-trimethylphenol. Catalyst systems are generally employed for such coupling; they typically contain at least one heavy metal compound such as a copper, manganese or cobalt compound, usually in combination with various other materials.
Particularly useful polyphenylene ethers for many purposes are those which comprise molecules having at least one aminoalkyl-containing end group. The aminoalkyl radical is covalently bound to a carbon atom located in an ortho position to the hydroxy group. Products containing such end groups may be obtained by incorporating an appropriate primary or secondary monoamine such as di-n-butylamine or dimethylamine as one of the constituents of the oxidative coupling reaction mixture. Also frequently present are 4-hydroxybiphenyl end groups and/or biphenyl structural units, typically obtained from reaction mixtures in which a by-product diphenoquinone is present, especially in a copper-halide-secondary or tertiary amine system. A substantial proportion of the polymer molecules, typically constituting as much as about 90% by weight of the polymer, may contain at least one of said aminoalkyl-containing and 4-hydroxybiphenyl end groups.
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 variati
Pan Yiqun
Yeager Gary William
Brown S. Bruce
General Electric Company
Johnson Noreen C.
Short Patricia A.
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