Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2001-03-15
2002-11-12
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S271000, C528S272000
Reexamination Certificate
active
06479619
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for producing partially esterified metal salts of sulfoisophthalic acid solutions in a glycol and to a process for producing a polymer comprising repeat units derived from sulfoisophthalic acid or salt thereof or ester thereof, a carbonyl compound, and a glycol in which a phosphorus compound can be used to improve polymer properties.
BACKGROUND OF THE INVENTION
Polyesters are widely used to manufacture textile fibers and bottle resins and can be manufactured by combining a glycol such as ethylene glycol and a carbonyl compound such as dimethyl terephthalate (DMT) or terephthalic acid (TPA). For example, DMT reacts with a glycol such as ethylene glycol to form bis-glycolate ester of terephthalate (“monomer”) in the ester exchanger column. The monomer is polymerized by condensation reactions in one or two prepolymerizers and then a final polymerizer or finisher. TPA can be combined with ethylene glycol to form a slurry at 60 to 80° C. followed by injecting the slurry into an esterifier. Linear oligomer with degree of polymerization less than 10 is formed in one or two esterifiers (first and second, if two) at temperatures from 240° C. to 290° C. The oligomer is then polymerized in one or two prepolymerizers and then in a final polymerizer or finisher at temperatures from 250° C. to 300° C.
Additives such as catalysts, stabilizers, delusterants, and toners are often added to the TPA slurry before the esterifier, in the esterifier, or in the oligomer before the prepolymerizer. Commercial polyester processes commonly use antimony compounds as polycondensation catalyst and phosphorous compounds as stabilizers. See generally, Encyclopedia of Chemical Technology, 4th edition, John Wiley, New York, 1994, Volume 10, pages 662-685 and Volume 19, pages 609-653.
However, it is difficult to incorporate a dye material into or onto these polyesters. Therefore, copolymers comprising repeat units derived from terephthalic acid, sulfoisophthalic acid, and glycol are widely used because they can be used to make fibers dyeable by basic dyes or polyester hydrolyzable in water. Such copolymers are referred to as cationic dyeable (CD) polyesters and can be produced by adding small amounts of a sulfonated isophthalate metal salt or its ester such as, for example, sodium dimethylsulfoisophthalate (Na-DMSIP) powder to the ester exchanger of DMT process. Fiber made from CD copolymer gives brilliant shades on dyeing with basic/cationic dyes and also dyes with disperse dyes to deeper shades.
U.S. Pat. No. 5,559,205 discloses a process for adding fully esterified bis(2-hydroxyethyl) sodium 5-sulfoisophthalate (Na-SIPEG) or bis(2-hydroxyethyl) lithium 5-sulfoisophthalate (Li-SIPEG) to the monomer line of DMT process, or oligomer line or the second esterifier of TPA process to make cationic dyeable polyesters.
U.S. Pat. No. 6,075,115 discloses a process for making Na-SIPEG solution and Li-SIPEG solution from sodium 5-sulfoisophthalic acid (Na-SIPA) and to, lithium 5-sulfoisophthalic acid (Li-SIPA) powder. In order to fully esterify the Na-SIPA and Li-SIPA, special titanium catalyst was used, which comprises (1) a titanium compound, a solubility promoter, a phosphorus source, and optionally a solvent, or (2) a titanium compound, a complexing agent, a phosphorus source, and optionally a solvent, a sulfonic acid. The fully esterified Na-SIPEG and LiSIPEG solutions were manufactured by a vendor and then shipped to polyester producers. The solution was then injected into the monomer line of DMT process, or oligomer line or the second esterifier of TPA process to make copolyesters.
These processes have several disadvantages including (1) high cost of 20% Na-SIPEG solution and 20% Li-SIPEG solution, because a separate facility is required to make these solutions from Na-SIPA or Li-SIPA powder and glycol; (2) high transportation cost for the 20% solutions; (3) high investment cost to build a heated storage tank, pump, and piping system for the 20% solutions; (4) cationic dyeable polyester producers cannot control the properties of the solutions such as DEG (diethylene glycol), acidity, carboxyl groups, and concentration; and (5) a tendency to form dimer and/or trimer in the solutions.
Therefore, there is a need to develop a process to produce a partially esterified Na-SIPA solution and Li-SIPA solution that is more stable and less likely to form solids when cooled to room temperature, especially at high concentrations. An advantage of the invention is that the partially esterified Na-SIPA and Li-SIPA solutions can be made immediately before it is used in producing polyester thereby significantly reducing manufacturing and transportation cost. Another advantage is that the unesterified carboxyl groups partially accelerate the polycondensation reaction thereby improving productivity. Also an advantage is that the properties of the solution can be better controlled. A further advantage is that less dimer, trimer, or tetramer is produced rendering a more stable Na-SIPA or Li-SIPA solution and more uniform basic dye site distribution in the resulting polymer.
Additionally, it is well known that phosphoric acid is commonly used to control the discoloration of polyester homopolymer, but phosphoric acid does not improve the color of copolymer derived from terephthalic acid and sulfoisophthalic acid. Thus, there is also a need to develop a process using a nonacidic phosphorus compound to improve the color of dyeable polyester.
Furthermore, stainless steel or carbon steel is commonly used as surface metal of process equipment, such as heat exchanger, for commercial production of a polymer having repeat units derived from an alkali metal SIPA. An alkali metal SIPA prepolymer formed during the production was found to stick on the metal surface of the process equipment degrading or carbonizing into black solids and, subsequently, resulting in process plugging, which requires shutdown every 1 to 4 months to clean the plugged tubes. Therefore, it is also a need to identify process equipment for producing a polymer having repeat units derived from an alkali metal SIPA.
SUMMARY OF THE INVENTION
A process that can be used for producing a partially esterified SIPA in a first glycol is disclosed. The process comprises contacting a SIPA to produce a mixture and heating the mixture under a condition sufficient to partially esterify the SIPA wherein the mixture optionally comprises a catalyst.
Also disclosed is a process that can be used for controlling the color of a dyeable polyester. The process comprises contacting, optionally in the presence of a phosphorus compound and/or a catalyst, a SIPA or partially esterified SIPA with either (a) a polymerization mixture comprising a carbonyl compound and a second glycol or (b) an oligomer derived from a carbonyl and a second glycol.
Further disclosed is a process for producing a dyeable polyester. The process comprises contacting, optionally in the presence of a phosphorus compound and/or a catalyst, a SIPA or partially esterified SIPA with either (a) a polymerization mixture comprising a carbonyl compound and a second glycol or (b) an oligomer derived from a carbonyl and a second glycol wherein the process is carried out in a vessel or process equipment having nickel or a nickel alloy as surface metal or fluoropolymer as a surface.
DETAILED DESCRIPTION OF THE INVENTION
The acronym “SIPA” used herein can have the formula of (RO(O)C)
2
ArS(O)
2
OM in which each R can be the same or different and is hydrogen or an alkyl group containing 1 to about 6 carbon atoms or hydroxyalkyl group containing 1 to 6 carbon atoms; Ar is a phenylene group; and M is hydrogen, an alkali metal, an alkaline earth metal, quaternary ammonium or phosphonium, or combinations of two or more thereof. The preferred M is an alkali metal such as lithium or sodium. Accordingly, SIPA, unless otherwise specifically indicated, can also include those that are partially or fully esterified.
As such, “SIPA”, unless otherwise specifically indicated, can collectively refer to
Boykin Terressa M.
E. I. du Pont de Nemours and Company
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