Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ivb metal
Reexamination Certificate
2001-05-03
2003-11-11
Silverman, Stanley S. (Department: 1754)
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ivb metal
C423S610000, C423S633000, C423S140000, C023S3130FB
Reexamination Certificate
active
06645445
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for efficiently removing titanium oxide or red oxide from an ethylene glycol solvolysis product of a polyester containing titanium oxide or red oxide by agglomerating titanium oxide or red oxide.
PRIOR ART
Currently, the main application field of bis-&bgr;-hydroxyethyl terephthalate is terephthalate-based polyesters and one of the features of the terephthalate-based polyesters is that they have performance well suited to a wide range of fields of molded products such as fibers, films and resins. Especially in the field of fibers out of the wide range of fields, titanium oxide is generally contained in a polymer mainly to draw polish. Mainly in the field of molded products such as bottles, red oxide is experimentally or will be commercially made existent in a polymer. Meanwhile, another feature of the polyesters is that it is relatively easy to restore the polyesters to their raw material stages by depolymerization.
Polyesters, particularly terephthalate-based polyesters typified by polyethylene terephthalate are widely used for various purposes as described above. To produce the polyesters, a process in which an intermediate containing bis-&bgr;-hydroxyethyl terephthalate is obtained by direct esterification between terephthalic acid and ethylene glycol or an ester exchange reaction between a lower alkyl ester of terephthalic acid, especially dimethyl terephthalate and ethylene glycol and then polycondensed at a high temperature under high vacuum is now mainly used practically. Further, the terephthalate-based polyesters can be restored to their raw material stages by depolymerization and polymerized again to obtain polyesters. Therefore, it can be said that they are excellent materials from the viewpoint of resource saving.
However, when recovered polyesters are polyesters containing titanium oxide or polyesters containing red oxide, the content of the titanium oxide or red oxide and the types and contents of other additives change by each recovered polyester and become a barrier to the separation of a substance of interest after a depolymerization reaction in many cases. Therefore, actual operation is frequently impeded.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for removing titanium oxide from an ethylene glycol solvolysis product of a polyester containing titanium oxide with high operation ease and high efficiency.
It is another object of the present invention to provide a process for obtaining a polyester decomposition product containing substantially no titanium oxide by efficiently removing titanium oxide from an ethylene glycol solvolysis product of a polyester containing titanium oxide.
It is still another object of the present invention to provide a process for efficiently removing titanium oxide from an ethylene glycol solvolysis product of a recovered polyester to enable and facilitate recycling of the recovered polyester containing titanium oxide.
It is a further object of the present invention to provide a process for removing red oxide from an ethylene glycol solvolysis product of a polyester containing red oxide with high operation ease and high efficiency.
It is a still further object of the present invention to provide a process for obtaining a polyester decomposition product containing substantially no red oxide by efficiently removing red oxide from an ethylene glycol solvolysis product of a polyester containing red oxide.
It is a still further object of the present invention to provide a process for efficiently removing red oxide from an ethylene glycol solvolysis product of a recovered polyester to enable and facilitate recycling of the recovered polyester containing red oxide.
It is a still further object of the present invention to provide a process for removing red oxide from even a polyester containing red oxide and further carbon black with high operation ease and high efficiency.
Other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are attained by a process for removing titanium oxide from a polyester decomposition product (to be referred to as “first process of the present invention” hereinafter) which comprises the steps of:
(1) mixing at least one compound (may be referred to as “specific compound” hereinafter) selected from the group consisting of calcium oxide, calcium carbonate, calcium hydroxide and red oxide with a polyester decomposition product containing titanium oxide which is an ethylene glycol solvolysis product of a polyester containing titanium oxide to agglomerate titanium oxide contained in the polyester decomposition product; and
(2) subjecting the agglomerated titanium oxide to solid-liquid separation to remove it.
According to the present invention, secondly, the above objects and advantages of the present invention are attained by a process for removing red oxide from a polyester decomposition product (to be referred to as “second process of the present invention” hereinafter) which comprises the steps of:
(1) mixing titanium oxide with a polyester decomposition product containing red oxide which is an ethylene glycol solvolysis product of a polyester containing red oxide to agglomerate red oxide contained in the polyester decomposition product; and
(2) subjecting the agglomerates to solid-liquid separation to remove them.
A description is first given of the first process of the present invention.
In the present invention, the polyester to be decomposed by adding ethylene glycol contains titanium oxide. The content of titanium oxide is 10 wt % or less, preferably 2 wt % or less, more preferably 0.5 wt % or less based on the polyester.
The type of polyester is not limited but preferably an aromatic polyester comprising an aromatic dicarboxylic acid such as terephthalic acid or 2,6-naphthalenedicarboxylic acid as the main dicarboxylic acid component and ethylene glycol as the main glycol component. Out of these, a terephthalate-based polyester comprising ethylene terephthalate as the main constitute component is particularly preferred.
In the present invention, the terephthalate-based polyester is what comprises polyethylene terephthalate as the main constituent component and is also including what copolymerizes at least one other constituent component in a small proportion. The proportion of the copolymerizable component is preferably 40 mol % or less, more preferably 30 mol % or less, much more preferably 20 mol % or less based on the total of all the acid components and all the glycol components. Examples of the copolymerizable component include dicarboxylic acids such as aromatic dicarboxylic acids exemplified by isophthalic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenyl ether dicarboxylic acid, naphthalenedicarboxylic acid, diphenoxyethane dicarboxylic acid and sodium sulfoisophthalic acid, aliphatic dicarboxylic acids exemplified by sebacic acid and adipic acid, and alicyclic dicarboxylic acids exemplified by hexahydroterephthalic acid; and diols such as trimethylene glycol, tetramethylene glycol, hexamethylene glycol, cyclohexane dimethanol, bis-&bgr;-hydroxyethyl bisphenol A, bis-&bgr;-hydroxyethoxydiphenyl sulfone, bis-&bgr;-hydroxyethoxydiphenyl ether, diethylene glycol, polyethylene glycol and the like. A hydroxycarboxylic acid such as p-hydroxyethoxyphenyl carboxylic acid may be used as the copolymerizable component. Further, a polyfunctional compound having a functionality of 3 or more and/or a monofunctional compound may also be used as the copolymerizable component in limits that the polyester keeps linear. Examples of the polyfunctional compound having a functionality of 3 or more include trimesic acid, glycerin, pentaerythritol and the like, and examples of the monofunctional compound include diphenylmonocarboxylic acid, diphenyl ether monocarboxylic acid, phenoxypolyethylene glycol and the like. These copolymerizable co
Inada Shuji
Sato Kikuchi
AIES Co., Ltd.
Anderson Kill & Olick P.C.
Johnson Edward M.
Lieberstein Eugene
Meller Michael N.
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