Process for the manufacture of low molecular weight...

Details Process for the manufacture of low molecular weight... Process for the manufacture of low molecular weight...

2000-12-13

2001-10-16

Truong, Duc (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Treating polymer containing material or treating a solid...

C528S217000, C528S212000, C528S214000, C264S050000, C264S459000

Reexamination Certificate

active

06303748

ABSTRACT:

FEDERALLY SPONSORED RESEARCH
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a novel process for the manufacture of very low molecular weight polyphenylene ether resin, typically within the intrinsic viscosity range of about 0.08 dl/g to about 0.16 dl/g as measured in chloroform at 25° C.
The invention also relates to the polyphenylene ether resin made by the process as well as blends and articles containing the polyphenylene ether resin made by the process.
2. Brief Description of the Related Art
Polyphenylene ether resins (hereinafter “PPE”) are commercially attractive materials because of their unique combination of physical, chemical, and electrical properties. Furthermore, the combination of PPE with other resins provides blends which result in additional overall properties such as chemical resistance, high strength, and high flow.
The processes most generally used to produce PPE involve the self-condensation of at least one monovalent phenol in the presence of an oxygen containing gas and a catalyst comprising a metal amine complex to produce resins typically within the intrinsic viscosity range of about 0.35 dl/g to about 0.65 dl/g as measured in chloroform at 25° C.
These processes are typically carried out in the presence of an organic solvent and the reaction is usually terminated by removal of the catalyst from the reaction mixture. The catalyst metal, after being converted into a soluble metal complex with the aid of a chelating agent, is removed from the polymer solution with standard extraction techniques, such as liquid-liquid extraction. The PPE polymer can be isolated in a variety of methods although generally by anti-solvent precipitation.
As new commercial applications are sought for PPE, a wider range of intrinsic viscosity resins, especially lower intrinsic viscosity resins, have been desired. As intrinsic viscosity decreases in PPE resins, the level of hydroxyl groups increases and the rheological properties change dramatically (lower viscosity as intrinsic viscosity decreases) as compared to current commercially available high molecular weight PPE produced by the methods previously described. The physical properties of PPE remain highly desirable and sought after in applications such as, for example, adhesives, sealants and gels based on SBC, SBR, or epoxies for automotive, housing, cabeling, membranes and electrical applications. Also, epoxy based composites for aerospace, automotive structural members and sporting equipment are desirable applications as are electrical laminates, and IC encapsulation materials based on epoxies and unsaturated polyesters. Friction materials and abrasives compounds based on phenolic are also sought after. PPE is also useful as an additive in various thermoplastic and thermoset materials including, e.g., polypropylene, polystyrene, ABS, polycarbonate, polyetherimide, polyamides, polyesters, and the like and also thermosetting resins such as, for example, epoxies, unsaturated polyesters, polyurethanes, allylic thermosets, bismaleimides, phenolic resins, and the like. Varying enhanced properties may be improved in different systems such as, for example, improved heat performance, flame retardancy improvement, decrease of electrical properties like Dk and Df, decrease in moisture absorption, increased creep resistance, thermal expansion reduction, chemical resistance to acids and bases, for various applications such as, for example, automotive and house hold and electrical goods.
It is therefore apparent that a need exists for the development of processes for the manufacture of very low molecular weight polyphenylene ether resin, typically within the intrinsic viscosity range of about 0.08 dl/g to about 0.16 dl/g as measured in chloroform at 25° C.
SUMMARY OF THE INVENTION
The needs discussed above have been generally satisfied by the discovery of a process for preparing PPE having an intrinsic viscosity within the range of about 0.08 dl/g to about 0.16 dl/g as measured in chloroform at 25° C. comprising oxidative coupling in a reaction solution at least one monovalent phenol species using an oxygen containing gas and a complex metal catalyst to produce a PPE having an intrinsic viscosity within the range of about 0.08 dl/g to about 0.16 dl/g as measured in chloroform at 25° C.; removing at least a portion of the complex metal catalyst with an aqueous containing solution; and isolating the PPE through devolatilization of the reaction solvent.
The description that follows provides further details regarding various embodiments of the invention.
DESCRIPTION OF THE DRAWINGS
Not applicable
DETAILED DESCRIPTION OF THE INVENTION
This invention provides for a process for the preparation of low molecular weight PPE, preferably having an intrinsic viscosity between about 0.08 dl/g and 0.16 dl/g, by oxidative coupling at least one monovalent phenol species, preferably at least a portion of which have substitution in at least the two ortho positions and hydrogen or halogen in the para position, using an oxygen containing gas and a complex metal-amine catalyst, preferably a copper (I)-amine catalyst, as the oxidizing agent and extracting at least a portion of the metal catalyst as a metal-organic acid salt with an aqueous containing solution, and isolating the PPE through devolatilization of the reaction solvent. In one embodiment, the process affords a PPE that has less than a 10% increase, preferably less than 5% increase in intrinsic viscosity after heating into the melt phase. In another embodiment, the process affords a PPE that has less than a 10% decrease, preferably less than 5% decrease, most preferably less than 3% decrease in intrinsic viscosity after an equilibration step following the oxidative coupling reaction.
The PPE employed in the present invention are known polymers comprising a plurality of structural units of the formula
wherein each structural unit may be the same or different, and in each structural unit, each Q
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; and each Q
2
is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or halohydrocarbonoxy as defined for Q
1
. Most often, each Q
1
is alkyl or phenyl, especially C
1-4
alkyl, and each Q
2
is hydrogen.
Both homopolymer and copolymer PPE 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 PPE containing moieties prepared by grafting vinyl monomers or polymers such as polystyrenes and elastomers, as well as coupled PPE 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 poly(phenylene ether) chains to produce a higher molecular weight polymer, provided a substantial proportion of free OH groups remains. Also included are PPE's containing a functional endgroup, obtained from reaction with a reactive compound having the functional endgroup.
The low molecular weight PPE generally have a number average molecular weight within the range of about 1250 to about 7000 and a weight average molecular weight within the range of about 2500 to about 15,000, as determined by gel permeation chromatography, with a preferred number average molecular weight within the range of about 1750 to about 4000 and a weight average molecular weight within the range of about 3500 to about 9,000, as determined by gel permeation chromatography. Alternatively, the intrinsic viscosity (hereinafter “I.V.”) of the low molecular weight PPE is most often in the range of about 0.08-0.16 dl./g., preferably in the range of about 0.10-0.14 dl./g., as measured in chloroform at

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