Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-04-05
2002-11-19
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S462000, C524S497000, C524S500000, C524S414000
Reexamination Certificate
active
06482880
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is directed to a molding resin composition comprising a poly(biphenyl ether sulfone) resin. More particularly the invention is directed to improved molding resin compositions having reduced tendency toward yellowing comprising poly(biphenyl ether sulfone) resin, and to a method for improving the yellowing resistance of poly(biphenyl ether sulfone) resins.
Poly(aryl ether sulfone) resins have been known for nearly three decades. They are tough linear polymers that possess a number of attractive features such as excellent high temperature resistance, good electrical properties, and very good hydrolytic stability. A variety of poly(aryl ether sulfones) are commercially available, including the polycondensation product of 4,4′-dihydroxydiphenyl sulfone with 4,4′-dichlorodiphenyl sulfone and the polymer of bisphenol-A and 4,4′-dichlorodiphenyl sulfone. These and other poly(aryl ether sulfone) resins are widely disclosed and described in the art, including in U.S. Pat. No. 4,108,837 and Canadian Patent No. 847,963. A third commercial poly(aryl ether sulfone) is the poly(biphenyl ether sulfone) resin available from Amoco Performance Products, Inc. under the trademark of Radel® R. The latter resin may be described as the product of the polycondensation of biphenol with 4,4′-dichlorodiphenyl sulfone.
Because of their excellent mechanical and thermal properties coupled with outstanding hydrolytic stability, poly(aryl ether sulfones) have found wide application, including in extruded goods and molded articles for use where exposure to severe environments is contemplated. Parts molded from poly(biphenyl ether sulfone) resins have substantially better mechanical properties than those molded from other readily available poly(aryl ether sulfone) resins, and are generally more chemically resistant.
Although poly(aryl ether sulfone) resins are also highly resistant to mineral acids and salt solutions, when exposed to polar organic solvents, they readily stress crack. Where increased environmental stress crack resistance is desired, blends of poly(aryl ether sulfone) resins have been employed to make them more acceptable for use in a solvent environment without substantially affecting their mechanical or electrical properties. Blends comprising polyetherimide resins and poly(aryl ether sulfone) resins are disclosed in U.S. Pat. No. 4,293,670 to have significantly improved environmental stress crack resistance and good impact strength. A variety of other blends have also been described in the art for these purposes including, for example, blends of poly(aryl ether sulfone) resins with polyamide-imides as well as blends with poly(aryl ether ketone) resins. Copolymers with improved stress-cracking resistance are also known in the art including, for example, co-poly(biphenyl ether sulfone) resins comprising bisphenol A moieties as disclosed and described in U.S. Pat. No. 5,164,166.
Poly(biphenyl ether sulfone) resins are known to exhibit good mechanical properties at elevated temperatures and have excellent high temperature stability. These resins may be combined with suitable flame retarding additives to provide highly desirable chemically-resistant, flame retardant, low heat release materials for use in aircraft interiors and the like, as disclosed in U.S. Pat. No. 5,204,400, and are particularly useful for these purposes when employed in blends with polyaryl ether ketones.
One deficiency of formulations based on poly(biphenyl ether sulfone) resins is the tendency of these resins to yellow rapidly when exposed to ultraviolet radiation such as may be encountered when exposed to sunlight or fluorescent lighting. Although the effect on mechanical properties may be minimal, the cosmetic appearance of articles made from such resins may become severely degraded. The color stability of resin formulations, and particularly those supplied in light colors and intended to be used in fabricating articles visible to the consumer, for example, in trim panels and similar appearance parts of aircraft interiors, may be the determining factor in deciding the commercial acceptability of such goods.
BRIEF SUMMARY OF THE INVENTION
This invention is directed to compositions having improved resistance to yellowing comprising a poly(biphenyl ether sulfone) resin, and to a method for improving the yellowing resistance of poly(biphenyl ether sulfone) resins by combining said resin with particular levels of a polyetherimide resin to form a blend. Molded articles comprising such blends have improved resistance toward yellowing and may be further combined with suitable flame retarding additives to provide highly desirable low heat release materials useful in the manufacture of components for aircraft interiors and the like.
DETAILED DESCRIPTION OF THE INVENTION
Briefly, the poly(biphenyl ether sulfone) resins useful in the practice of this invention comprise the structural unit
The polymer may further comprise up to 50 mole percent, preferably up to about 25 mole percent, still more preferably no more than about 10 mole percent additional arylene sulfone units with the structure
wherein Ar is a monoarylene moiety such as p-phenylene, m-phenylene or the like, or is a diarylene moiety other than biphenyl, for example a bisphenol A, bisphenol S or similar moiety. The presence of these additional arylene sulfone units may have a detrimental effect on the overall balance of properties, hence polymers containing only biphenylether sulfone moieties will generally be preferred.
Poly(biphenyl ether sulfone) resins may be prepared by any of the variety of methods well known in the art for the preparation of poly(aryl ether) resins. Two methods, the carbonate method and the alkali metal hydroxide method, are widely known and used for this purpose. In the alkali metal hydroxide method, disclosed for example in U.S. Pat. No. 4,108,837 and in U.S. Pat. No. 4,175,175, a double alkali metal salt of a dihydric phenol is contacted with a dihalobenzenoid compound in the presence of a sulfur containing solvent as herein above defined under substantially anhydrous conditions. The carbonate method, in which at least one dihydric phenol and at least one dihalobenzenoid compound are heated, for example, with sodium carbonate or bicarbonate and a second alkali metal carbonate or bicarbonate is also widely disclosed in the art, for example in U.S. Pat. No. 4,176,222.
The reduced viscosity of the poly(biphenyl ether sulfone) resins useful in the practice of the invention, measured in an appropriate solvent such as methylene chloride, chloroform, N-methylpyrrolidone or the like, will be at least 0.3 dl/g, preferably at least 0.4 dl/g, and the polymer will be film-forming. Generally, resins having a reduced viscosity in the range of from about 0.3.to about 1.0 dl/g will be readily processable thermally and will be useful for these purposes. Very high molecular weight resins, typically those having a reduced viscosity greater than about 1.0 dl/g, may also be found useful, however, such resins will have a high melt viscosity and be difficult to process and will therefore not be preferred.
Polyetherimides suitable for use in this invention are also well known in the art and are described in, for example, U.S. Pat. Nos. 3,847,867, 3,838,097 and 4,107,147. The polyetherimides may be further described as comprising units of the following structure:
wherein Ar
1
and Ar
2
are independently selected from substituted and unsubstituted divalent aromatic radicals and more particularly may be monoarylene moieties such as p-phenylene, m-phenylene or the like, or selected from diarylene moieties such as, for example a biphenyl, bisphenol A, bisphenol S or similar moiety. Isomeric structures wherein the ether-linked moiety —O—Ar
1
—O— may be attached to the 3 and 3′ positions of the respective aromatic rings are also contemplated as within the description of suitable polyetherimides.
These polyetherimides are readily prepared by any of the methods well known in the art such as those disclose
Cain Edward J.
Lee Katarzyna Wyrozebski
McDermott & Will & Emery
Solvay Advanced Polymers, LLC
LandOfFree
Poly(biphenyl ether sulfone) resins having improved UV... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Poly(biphenyl ether sulfone) resins having improved UV..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Poly(biphenyl ether sulfone) resins having improved UV... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2927272