Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2002-07-16
2003-04-01
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S274000, C528S275000, C528S286000, C528S302000, C528S308000, C528S308600, C502S150000, C502S162000, C502S208000, C502S170000, C524S706000, C524S710000, C524S711000, C524S713000
Reexamination Certificate
active
06541598
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a composition that comprises or is produced from a titanium compound and a phosphorus compound and to a process for esterification, transesterification, or polymerization of a carbonyl compound in the presence of a catalyst composition and a phosphorus compound.
BACKGROUND OF THE INVENTION
Polyesters such as, for example, polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate, generally referred to as “polyalkylene terephthalates”, are a class of important industrial polymers. They are widely used in fibers, films, and molding applications.
Polyesters can be produced by transesterification of an ester such as dimethyl terephthalate (DMT) with a glycol followed by polycondensation or by direct esterification of an acid such as terephthalic acid (TPA) with a glycol followed by polycondensation. A catalyst is used to catalyze the esterification, transesterification and/or polycondensation.
For example, polyester can be produced by injecting a slurry mixture of TPA and glycol at about 80° C. into an esterifier. Linear oligomer with degree of polymerization less than 10 are formed in one or two esterifiers at temperatures from 240° C. to 290° C. The oligomer is then polymerized in one or two prepolymerizers and then a final polymerizer or finisher at temperatures from 250° C. to 300° C. TPA esterification is catalyzed by the carboxyl groups of the acid.
Antimony is often used for polymerization or polycondensation reaction. However, antimony forms insoluble antimony complexes that plug fiber spinnerets and leads in fiber spinning to frequent shutdowns to wipe spinnerets clean of precipitated antimony compounds. The antimony-based catalysts are also coming under increased environmental pressure and regulatory control, especially in food contact applications.
Titanium catalysts can be used in the esterification, transesterification, and polycondensation reactions. However, the titanium catalysts tend to hydrolyze on contact with water forming glycol-insoluble oligomeric species, which lose catalytic activity. Polyesters produced from an organic titanate also generate yellow discoloration. Even water compatible titanates, such as titanium bis-ammonium lactate, bis-triethanolamine titanate or the titanium sodium citrate catalysts disclosed in EP 812818, when used as polyesterification catalysts, generate significant yellow discoloration in the resultant polymer. Similarly, WO 99/28033 discloses an organometallic compound for producing an ester. The organometallic compound comprises the reaction product of an orthoester of titanium, zirconium, or aluminum, an alcohol containing at least two hydroxyl groups, an organophosphorus compound, and a base. When used as polyesterification catalyst, however, it was found that the organometallic compound also generates undesirably significant yellow discoloration in the final product.
Therefore, there is an increasing need for developing a new catalyst that is efficient, produces a polymer with reduced color, exhibits good catalytic activity, does not result in plugging fiber spinnerets, and is environmentally friendly.
An advantage of the present invention is the polymer produced using the invention catalyst has improved optical properties (e.g., less undesirable color) compared to polymer produced using an organic titanate catalyst alone. Other advantages will become more apparent as the invention is more fully disclosed herein below.
SUMMARY OF THE INVENTION
A composition that can be used for producing polyester is provided, which comprises a titanium compound and a phosphorus compound.
Also provided is a process that can be used for producing polyester, which comprises contacting, in the presence of a catalyst composition and a phosphorus compound, a carbonyl compound and an alcohol in which the composition comprises a titanium compound.
Further provided is a process that can be used to produce a polymer containing reduced insoluble particles or solids, which comprises contacting, in the presence of a catalyst composition and a phosphorus compound in which the catalyst comprises a metal and the phosphorus compound is not phosphoric acid.
DETAILED DESCRIPTION OF THE INVENTION
The term “reduced insoluble particles” or “reduced solids” refers to the quantity of insoluble particles or solids present in a polymer such as polyester produced by the invention process as compared to that produced by a conventional process in which phosphoric acid is present in the conventional process.
According to an embodiment of the invention, the invention composition can comprise, consist essentially of, or consists of, or is produced by combining (A) a titanium compound; (B) either (i) a complexing agent and optionally a first solvent or (ii) a combination of a complexing agent, hypophosphorous acid or a salt thereof, and optionally a first solvent, a zirconium compound, or both, or (iii) combinations of (i) and (ii); and (C) a phosphorus compound; and optionally a second solvent.
According to the invention, the preferred titanium compounds used in component (A) are organic titanium compounds such as, for example, titanium tetrahydrocarbyloxides, also referred to as tetraalkyl titanates herein for they are readily available and effective. Examples of suitable titanium tetrahydrocarbyloxides include those having the formula of Ti(OR)
4
where each R is individually selected from an alkyl, cycloalkyl, alkaryl, hydrocarbyl radical containing from 1 to about 30, preferably 2 to about 18, and most preferably 2 to 12 carbon atoms per radical and each R can be the same or different. Titanium tetrahydrocarbyloxides in which the hydrocarboxyl group contains from 2 to about 12 carbon atoms per radical which is a linear or branched alkyl radical are most preferred because they are relatively inexpensive, more readily available, and effective in forming the solution. Suitable titanium tetrahydrocarbyloxides include, but are not limited to, titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetra-n-butoxide, titanium tetrahexoxide, titanium tetra 2-ethylhexoxide, titanium tetraoctoxide, and combinations of two or more thereof. The titanium tetrahydrocarbyloxides are well known to one skilled in the art. See, for example, U.S. Pat. Nos. 6,066,714 and 6,166,170, the description of which is incorporated herein by reference. Examples of commercially available organic titanium compounds include, but are not limited to, TYZOR® TPT and TYZOR® TBT (tetra isopropyl titanate and tetra n-butyl titanate, respectively) available from E.I. du Pont de Nemours and Company, Wilmington, Del., U.S.A.
According to the invention, the titanium tetrahydrocarbyloxide can also be combined with a zirconium compound to produce a mixture comprising a titanium tetrahydrocarbyloxide and a zirconium tetrahydrocarbyloxide. The presently preferred zirconium tetrahydrocarbyloxides include, but are not limited to, zirconium tetraethoxide, zirconium tetrapropoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetrahexoxide, zirconium tetra 2-ethylhexoxide, zirconium tetraoctoxide, and combinations of two or more thereof. The molar ratio of Ti/Zr can be in the range of from about 0.001:1 to about 10:1.
The complexing agent suitable for use in (B)(i) and (B)(ii) can be a hydroxycarboxylic acid, an alkanolamine, an aminocarboxylic acid, or combinations of two or more thereof. It is presently preferred that it be an &agr;-hydroxycarboxylic acid, an alkanolamine, or an &agr;-aminocarboxylic acid in which the hydrocarbyl group or alkyl group has 1 to about 15, preferably 1 to 10 carbon atoms per group, and combinations of two or more thereof. Examples of suitable complexing agents include, but are not limited to, lactic acid, glycolic acid, citric acid, tartaric acid, malic acid, diethanolamine, triethanolamine, tetrahydroxyisopropylethylenediamine, glycine, bis-hydroxyethyl glycine, hydroxyethyl glycine, and combinations of two or more thereof.
For example, TYZOR® LA is a reac
Davis Timothy M.
Duan Jiwen F.
Mallon Frederick K.
Putzig Donald E.
Acquah Samuel A.
E. I. du Pont de Nemours and Company
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