Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-08-24
2002-08-20
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S174000, C528S487000, C528S493000, C528S495000, C528S499000, C528S50200C, C528S503000
Reexamination Certificate
active
06437080
ABSTRACT:
PROCESS FOR PREPARING POLYMERS
The present invention relates to a process for the preparation of polymer compositions, the polymer compositions obtained by the process of the invention, method for the manufacture of composites, prepregs and the shaped articles employing the polymer compositions obtained with the process of the invention; and the manufactured products thereof. Specifically the present invention relates to a process for the preparation of polyaromatic compositions of desired molecular weight range, the compositions obtained by the process, a method for the manufacture of composites, prepregs and shaped articles with use of the compositions, and manufactured products thereof.
The use of curable compositions such as epoxy, cyanate, phenolic and like resins, both reinforced and unreinforced has been known for a long time in a wide variety of structural commercial and military applications. Sports devices, building materials, aeronautical, land and nautical vehicles have all found light weight carbon-based touch materials give enhanced performance.
More recently, classes of polyaromatic compositions comprising polyaryl thermoplastic components containing ether- and/or thioether-linked repeating units in the form of polyether aromatics and polyetherether aromatics are known for the manufacture of engineering polymers and composites having unique properties for the above structural applications in terms of strength, fracture toughness and high temperature stability and resistance.
Processes for the preparation of polyaromatics are known in “Polyaromatics”, P. T. McGrail. Polymer International 41 (1996) 103-121, polyaromatics and their synthesis are reviewed. The polymers are traditionally manufactured by nucleophilic processes for the condensation of alkali metal salts of monomers with elimination of water.
The review details the synthesis of the known Victrex PES and PEEK polymers comprising repeating polyether sulphone and ketone units which are prepared from bisphenol-S and hydroquinone with a halogenated monomer, traditionally by a process which enables the manufacture in high molecular weight. The process entails heating together alkali metal salts of monomers in diphenyl sulphone (DPS), a solvent which is solid from room temperature. Water produced as a by product of reaction is eliminated at the elevated reaction temperatures employed. Since DPS is a solid at room temperature up to about 150° C., it is not possible to precipitate the product polymer into a non-solvent at non-extreme temperatures. The solid which is formed on cooling which comprises a mixture of the desired polymer, DPS and residual salts, must be ground to a fine powder and put through a complex production cycle to remove the residual DPS and salts by leaching out. Finally, the polymer is dried.
A very accurate control of stoichiometry and polymerisation conditions is required in order to avoid leaching out polymer composition together with residual DPS and salts. This means that the molecular weight of polymer composition must be sufficiently high to give minimum solubility in extractant. This further complicates subsequent stages of injection molding, impregnating and the like by virtue of the high relative viscosity of the high molecular weight polymer components of the polymer composition, requiring processing at elevated temperatures.
The review also details the synthesis of a class of polysulphones which are prepared from bisphenol-A and DCDPS. This process traditionally entails heating together alkali metal salts of monomers in sulphoxide or sulphone, preferably dimethylsulphoxide (DMSO) under anhydrous conditions. In order to conduct the polymerisation reaction under anhydrous conditions it is necessary to form the alkali metal salts of monomers in a first stage in presence of an azeotrope, with removal of water prior to commencing the second stage polymerisation. The process is typically carried out at a limited maximum reaction temperature and even with use of highly reactive precursors it is not possible to develop high molecular weight. Moreover the process is cumbersome and costly due to the two stage nature, requiring intermediate processing for water removal, and due to the presence of azeotrope in both stages requiring isolation and processing of product polymer with non aqueous media.
Accordingly a first object of the present invention is to provide a process for preparation of polyaromatic compositions in which polymer reaction and isolation may be conducted independently, of constraints imposed by reaction components and for the removal of by-products of reaction.
A second object of the present invention is to provide a process for the preparation of polyaromatic compositions with use of an effective fluid combination enabling effective isolation of the product composition in convenient form.
A third object of the present invention is to provide a process for the preparation of polyaromatic compositions in a calculated molecular weight range of polymer which may be achieved independently of constraints imposed by the process such as solubility constraints and the like.
A fourth object of the present invention is to provide high quality injection molded, impregnated or otherwise shaped articles obtained with improved processing advantages of polymer compositions of the invention.
We have now surprisingly found that the above objects can be met in admirable manner with use of a novel process for the preparation of polyaromatic compositions.
Accordingly in its broadest aspect there is provided according to the present invention a process for the preparation of a polymer composition comprising at least one aromatic or a mixture thereof, the process comprising:
i) obtaining a reaction mixture comprising polymer precursors in a first fluid boiling in excess of 100° C.;
ii) subjecting the reaction mixture to a first elevated temperature in excess of 100° C. to generate the alkali metal salts of polymer precursors and the polymer reaction products thereof; and
iii) subjecting the reaction product mixture to at least a second temperature and isolating the reaction product in the form of a polymer composition which is substantially insoluble in a second fluid, from the first fluid which is substantially soluble in the second fluid, by contacting with an amount of second fluid:
wherein the process is conducted in substantial absence of an effective amount of an azeotrope.
It is a particular advantage that the process of the present invention can be carried out as an integrated single stage process. This is partially attributable to the fact that the process is self regulating or may be regulated in terms of production of volatiles in manner which is compatible with the progress of the reaction and with the reaction components themselves.
It is a further advantage of the process of the present invention that processing and isolation are integrated in manner that neither imposes constraints on the other in terms of incompatibility of components and conditions, but rather that features of processing and isolation are adapted for mutual enhancement in terms of convenience and efficiency.
Reference herein to first and second fluid is to an substance or mixtures of substances which is liquid at the first and second reaction and isolation temperatures.
Preferably the composition is soluble to less than 20% in the second fluid, more preferable to less than 10%, for example 0 to 5%. Preferably the first fluid is soluble to more than 50% in the second fluid, more preferably more than 80%, for example 85-100%.
It has surprisingly been found that the process of the invention eliminates constraints on choice of solvents such that the polymer composition may be isolated by precipitation in convenient manner as hereinbefore defined.
The first fluid suitably comprises at least one dipolar aprotic solvent which acts to promote the polymerisation reaction. Preferable, the first fluid boiling in excess of 100° C. is selected from one or more of sulphur oxides, such as sulphoxides and sulphones, formamide
Carter Jeffrey Thomas
McGrail Patrick Terence
Cytec Technology Corp.
Truong Duc
Van Tassel & VandenHoff
Wasserman Fran
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