Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-02-19
2004-06-22
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S128000, C524S284000, C524S285000, C524S286000, C524S288000, C524S289000, C524S321000, C524S322000
Reexamination Certificate
active
06753365
ABSTRACT:
BACKGROUND OF INVENTION
Polyetherimide resins are known for high heat distortion temperatures and glass transition temperatures that make their use as coatings, molded articles, composites, and the like very attractive where high temperature resistance is desired. Due to their high glass transition temperature and high melt viscosity, however, polyetherimides are difficult to process into finished products. Molding, extruding, spraying, and the like must be performed at high temperatures to plasticize the polyetherimide resin. Two properties that currently limit the use of polyetherimide compositions, particularly in injection molding applications, are mold release and melt flow.
There remains a need for a polyetherimide composition exhibiting improved mold release and increased melt flow.
SUMMARY OF INVENTION
The above-described and other drawbacks and disadvantages are alleviated by a resin composition comprising a polyetherimide resin and an acidic additive selected from the group consisting of aliphatic carboxylic acids having a vapor pressure less than one atmosphere at 300° C., aromatic carboxylic acids having a vapor pressure less than one atmosphere at 300° C., and combinations comprising at least one of the foregoing acidic additives.
Other embodiments, including articles comprising the composition and a method for preparing the composition, are described in detail below.
DETAILED DESCRIPTION
One embodiment is a composition, comprising a polyetherimide resin and an acidic additive selected from the group consisting of aliphatic carboxylic acids having a vapor pressure less than one atmosphere at 300° C., aromatic carboxylic acids having a vapor pressure less than one atmosphere at 300° C., and combinations comprising at least one of the foregoing acidic additives.
The present inventors have discovered that the acidic additives are effective to increase the melt flow and improve the mold release properties of polyetherimide resins, optionally in combination with polyester resins. These advantages are achieved without significantly compromising other important properties of the composition.
The composition comprises a polyetherimide resin. In one embodiment, the resin is a polyetherimide resin comprising structural units of the formula (I)
wherein the divalent T moiety bridges the 3,3′, 3,4′, 4,3′, or 4,4′ positions of the aryl rings of the respective aryl imide moieties of formula (I); T is —O— or a group of the formula —O-Z-O—; Z is a divalent radical selected from the group consisting of formulae (II)
wherein X is a member selected from the group consisting of divalent radicals of the formulae (III)
wherein y is an integer of 1 to about 5, and q is 0 or 1; R is a divalent organic radical selected from (a) aromatic hydrocarbon radicals having 6 to about 20 carbon atoms and halogenated derivatives thereof, (b) alkylene radicals having 2 to about 20 carbon atoms, (c) cycloalkylene radicals having 3 to about 20 carbon atoms, and (d) divalent radicals of the general formula (IV)
where Q is a covalent bond or a member selected from the group consisting of formulae (V)
where y′ is an integer from 1 to about 5.
Generally, useful polyetherimides have a melt index of about 0.1 to about 10 grams per minute (g/min), as measured by American Society for Testing Materials (ASTM) D1238 at 337° C., using a 6.6 kilogram weight.
In a preferred embodiment, the polyetherimide resin has a weight average molecular weight of about 10,000 to about 150,000 atomic mass units, as measured by gel permeation chromatography, using polystyrene standards. Such polyetherimide resins typically have an intrinsic viscosity greater than about 0.2 deciliters per gram measured in m-cresol at 25° C. An intrinsic viscosity of at least about 0.35 deciliters per gram may be preferred. Also, an intrinsic viscosity of up to about 0.7 deciliters per gram may be preferred.
Included among the many methods of making the polyetherimide resin are those disclosed in, for example, U.S. Pat. Nos. 3,847,867, 3,847,869, 3,850,885, 3,852,242, 3,855,178, and 3,983,093.
In a preferred embodiment, the polyetherimide resin comprises structural units according to formula (I) wherein each R is independently paraphenylene or metaphenylene and T is a divalent radical of the formula (VI).
A particularly preferred polyetherimide resin is the reaction product formed by melt polymerization of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride with one or more of paraphenylene diamine and metaphenylene diamine. The polyetherimides are commercially available from GE Plastics as ULTEM® resins, including, for example, ULTEM® 1000, ULTEM® 1010, ULTEM® 6000, and ULTEM® CRS5000.
The composition may comprise the polyetherimide in an amount of about 50 weight percent to about 99.99 weight percent, based on the total weight of the composition. Within this range it may be preferred to use a polyetherimide amount of at least about 80 weight percent, more preferably at least about 90 weight percent, still more preferably at least about 96 weight percent. Also within this range, it may be preferred to use a polyetherimide amount of up to about 99.9 weight percent, more preferably up to about 99 weight percent, still more preferably up to about 98 weight percent.
In addition to a polyetherimide, the composition comprises an acidic additive selected from aliphatic carboxylic acids having a vapor pressure less than one atmosphere at 300° C., aromatic carboxylic acids having a vapor pressure less than one atmosphere at 300° C., combinations comprising at least one of the foregoing acidic additives, and the like. The acidic additives are in the form of their free carboxylic acids rather than acid salts. It is preferred that the aliphatic carboxylic acids and the aromatic carboxylic acids have a vapor pressure less than one atmosphere at 325° C., more preferably at 350° C. While not wishing to be bound by any particular hypothesis, the present inventors believe that volatility of the acidic additive determines the degree to which it is retained in the composition during compounding and molding steps, particularly compounding steps conducted under partial vacuum. Acidic additives having a vapor pressure greater than or equal to one atmosphere at 300° C. may be too volatile to be sufficiently retained by the composition. The volatility limitation has been expressed as a vapor pressure limitation rather than a boiling point limitation because some of the acidic additives sublime and therefore do not exhibit a true boiling point. That said, for compounds exhibiting a boiling point, the volatility limitation may be expressed as a boiling point greater than about 300° C. at one atmosphere
The acidic additive may comprise an aliphatic carboxylic acid. In one embodiment, the aliphatic carboxylic acid has the structure (VII)
R—(CO
2
H)
n
(VII)
wherein R is a substituted or unsubstituted aliphatic hydrocarbon radical, and n is 1 to about 6. The radical R may be straight chain, branched, cyclic, or a combination thereof. When R is substituted, it may comprise one or more substituents including C
1
-C
18
alkoxy, C
6
-C
18
aryl, C
6
-C
18
aryloxy, nitro, halogeno (preferably chloro), hydroxy, amino, amido, alkoxycarbonyl, or the like. In a preferred embodiment, n is 1 or 2. In another preferred embodiment, n is 1. When R includes an aryl and/or aryloxy substituent, at least one carboxylic acid must be covalently bound to an aliphatic carbon of the aliphatic hydrocarbon radical R. In one embodiment, R is free of aryl substituents.
Although R may include aliphatic unsaturation, it is preferred that R is saturated (i.e., free of aliphatic unsaturation). In a preferred embodiment, the composition comprises a saturated aliphatic monocarboxylic acid. The saturated aliphatic monocarboxylic acid may preferably have about 12 to about 36 carbon atoms. Within this range, the saturated aliphatic monocarboxylic acid may preferably have at least about 14 carbon atoms, more preferably at least about 16 carbon atoms
Brown Sterling Bruce
David Jennifer L.
Gallucci Robert Russell
Jin Yimin
Lindway Martin J.
General Electric Company
Yoon Tae H.
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