Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Reexamination Certificate
1999-09-13
2001-10-23
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
C528S381000, C528S388000, C528S495000, C528S499000
Reexamination Certificate
active
06307011
ABSTRACT:
FIELD OF INVENTION
This invention relates to the field of processes for recovering at least one modifier compound and at least one polar organic compound from a poly(arylene sulfide) recycle mixture. In this disclosure, at least one polar organic compound is referred to as POC, and poly(arylene sulfide) is referred to as P(AS).
BACKGROUND OF THE INVENTION
The production of P(AS) for a variety of industrial and commercial uses has been known for some time. P(AS) is moldable into various articles including, but not limited to, parts, films, and fibers by means of, for example, injection molding and extrusion molding techniques. These articles have utility in a variety of applications where heat and chemical resistance properties are desired. For example, P(AS) can be utilized as a material for preparing electrical and electronic parts and automotive parts.
Generally, P(AS) is prepared by contacting reactants comprising at least one dihalogenated aromatic compound, at least one POC, at least one sulfur source, and at least one base under polymerization reaction conditions. Molecular weight modifier compounds can be added to produce high molecular weight P(AS). The most preferred modifier compound is sodium acetate due to its availability and effectiveness.
There are several problems associated with the current synthesis of P(AS) that cause the production expenses to be high. First, in both quench and flash P(AS) processes, modifiers utilized to synthesize the high molecular weight P(AS) are used once in the process and are not captured and recycled for subsequent use. This constitutes a great expense in the production of P(AS) due to the higher feedstock and waste disposal expense. Secondly, POC utilized in the process can be recovered, but often at a high cost. For example, n-hexanol is often utilized to extract N-methyl-2-pyrrolidone (NMP), a common POC. Operating the hexanol extractor system can require the handling of as much as 30 to 40 pounds of n-hexanol per pound of P(AS) produced causing high equipment and operational costs.
There is a need in the P(AS) industry for an efficient process to recover the modifier compound and POC from various streams. This invention provides such a process.
SUMMARY OF INVENTION
It is an object of this invention to provide a process to recover at least one modifier compound and at least one POC from a P(AS) recycle mixture.
In accordance with the present invention, a process to recover at least one POC and at least one modifier from a P(AS) recycle mixture is provided, said process comprising (or optionally, “consisting essentially of” or “consisting of”) separating said P(AS) recycle mixture in a first separation zone in the presence of water to yield methanol and a recycle feedstock mixture, wherein said recycle feedstock mixture comprises said POC and said modifier compound.
DETAILED DESCRIPTION OF INVENTION
In this invention, a process is provided to recover at least one modifier compound and at least one POC from a P(AS) recycle mixture. The P(AS) recycle mixture comprises methanol, at least one modifier compound and at least one POC. The P(AS) recycle mixture is obtained when a P(AS) reaction mixture is contacted with methanol in various different processes described subsequently in this disclosure.
P(AS) reaction mixtures useful in this invention can be produced by any method known in the art. Examples of the reaction mixtures useful in this invention are those prepared according to U.S. Pat. Nos. 3,919,177, 4,038,261, 4,038,262, 4,116,947, 4,282,347 and 4,350,810, the entire disclosures of which are herein incorporated by reference. The 4,038,261 patent discloses poly(phenylene sulfide).
Generally, P(AS) reaction mixtures useful in this invention are prepared by contacting a halogenated aromatic compound, at least one POC, at least one sulfur source, at least one base, and at least one modifier compound under polymerization reaction conditions to produce high molecular weight P(AS). The use of modifier compounds in the production of high molecular weight P(AS) is disclosed in U.S. Pat. No. 5,334,701, herein incorporated by reference.
As used herein, the term “high molecular weight” or “high molecular weight P(AS)” means all P(AS) molecules having molecular weights high enough to be commercially desirable and useable in an uncured state. Generally, the melt flow of a high molecular weight P(AS) is less than about 3,000 g/10 minutes. As used herein, the term “low molecular weight” or “low molecular weight P(AS)” means all P(AS) molecules having molecular weights too low to be commercially desirable and, thus, not useable in an uncured state. Generally, the melt flow of a low molecular weight P(AS) is greater than about 3,000 g/10 minutes.
Halogenated aromatic compounds suitable for producing reaction mixtures useful in this invention can be represented by the formula
wherein X is a halogen, and R is selected from the group consisting of hydrogen, halogens, and alkyl, cycloalkyl, aryl, alkylaryl, and arylalkyl radicals having from about 6 to about 24 carbon atoms. Exemplary halogenated aromatic compounds include, but are not limited to, p-dichlorobenzene (DCB), p-dibromobenzene, p-diiodobenzene, 1-chloro-4-bromobenzene, 1-chloro-4-iodobenzene, 1-bromo-4-iodobenzene, 2,5-dichlorotoluene, 2,5 -dichloro-p-xylene, 1-ethyl-4-isopropyl-2,5-dibromobenzene, 1,2,4,5-tetramethyl-3,6-dichlorobenzene, 1-butyl-4-cyclohexyl-2,5-dibromobenzene, 1-hexyl-3-dodecyl-2,5-dichlorobenzene, 1-octadecyl-2,4-diiodobenzene, 1-chloro-2-phenyl-4-bromobenzene, 1,4-diiodo2-p-tolylbenzene, 1,4-dibromo-2-benzylbenzene, 1-octyl-4-(3-methylcyclopentyl)-2,5-dichlorobenzene, and mixtures thereof. The preferred halogenated aromatic compound to produce the reaction mixture is DCB, due to availability, ease of use, and high polymerization productivity.
At least one POC must be utilized to produce the reaction mixture. Exemplary POCs include, but are not limited to, cyclic or acyclic organic amides having from about 1 to about 10 carbon atoms per molecule. Exemplary POCs are selected from the group consisting of formamide, acetamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, N-ethylpropionamide, N,N-dipropylbutyramide, 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), &egr;-caprolactam, N-methyl-&egr;-caprolactam, N,N′-ethylenedi-2-pyrrolidone, hexamethylphosphoramide, tetramethylurea, and mixtures thereof. The preferred POC for use in producing the reaction mixture is NMP due to availability and ease of use.
Any suitable source of sulfur can be used to produce the reaction mixture. Exemplary sulfur sources are selected from the group consisting of thiosulfates, substituted and unsubstituted thioureas, cyclic and acyclic thioamides, thiocarbamates, thiocarbonates, trithiocarbonates, organic sulfur-containing compounds selected from mercaptans, mercaptides and sulfides, hydrogen sulfide, phosphorous pentasulfide, carbon disulfides and carbon oxysulfides, and alkali metal sulfides and bisulfides, and mixtures thereof. It generally is preferred to use an alkali metal bisulfide as a source of sulfur wherein the alkali metal is selected from the group consisting of sodium, potassium, lithium, rubidium, and cesium due to availability and ease of use. The preferred alkali metal bisulfide is sodium bisulfide (NaSH) due to availability and low cost.
Suitable bases to produce the reaction mixture are alkali metal hydroxides selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and mixtures thereof. If desired, the base can be produced in-situ by reaction of the corresponding oxide with water. The preferred base is sodium hydroxide (NaOH) due to availability and ease of use.
At least one modifier compound is utilized to produce the reaction mixture. The modifier compound is selected from the group consisting of alkali metal carboxylates, alkali metal halides which are soluble in POC, water, and mixtures thereof.
Alkali metal carboxylate modifier compounds can be represented by the f
Fodor Jeffrey S.
Geibel Jon F.
Vidaurri Fernando C.
Moore Margaret G.
Owen Polly C.
Phillips Petroleum Company
Zimmer Mare
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