Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2002-07-02
2004-03-16
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S275000, C528S286000, C528S302000, C528S308000, C528S308600, C525S437000, C525S444000, C524S777000, C524S779000
Reexamination Certificate
active
06706852
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for producing a partially ester-exchanged metal salt of dimethyl sulfoisophthalate solutions in an alcohol from a metal salt of dimethyl sulfoisophthalate 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 an alcohol.
BACKGROUND OF THE INVENTION
Polyesters are widely used to manufacture textile fibers and bottle resins and can be manufactured by combining an alcohol such as ethylene glycol and a carbonyl compound such as dimethyl terephthalate (DMT) or terephthalic acid (TPA). For example, DMT reacts with an alcohol 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 esterifier (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, 4
th
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-SIPM) 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 esterifted 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 lithium 5-sulfoisophthalic acid (Li-SIPA) powder. In order to fully esterify 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 esterfied Na-SIPEG and Li-SIPEG 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, or the second or third vessel of batch polymerization process to make copolyesters.
A metal salt of 5-sulfoisophthalic acid fully esterified with methanol is also commercially available. For example, sodium dimethyl 5-sulfoisophthalate (Na-SIPM) can be purchased from E. I. Du Pont de Nemours and Company, Wilmington, Del., USA (Hereinafter “DuPont”).
It has been commercially practiced to fully ester exchange Na-SIPM with ethylene glycol to produced Na-SIPEG solution in the glycol. Manganese acetate catalyst is used as ester exchange catalyst. Sodium acetate can be added to reduce ether formation. The Na-SIPEG solution is then shipped to polyester producers and added to polyester process.
The processes using fully esterified Na-SIPEG have several disadvantages including the following. About 15 to 20% of Na-SIPEG forms dimer, trimer, and other low molecular weight oligomers due to long reaction time, making its distribution in polyester molecular chains not uniform, which affect spinning and texturing performance. The Na-SIPEG solution must be diluted to 20% or lower to be added into DMT monomer line or TPA oligomer line for acceptable spinning and texturing performance. Cost of 20% Na-SIPEG solution is high because a separate facility is required to make the solution from Na-SIPM powder and glycol. The transportation cost for the 20% solutions is high. High investment cost is needed to build a heated storage tank, pump, and piping system for the 20% solutions. CD polyester producers cannot control the properties of the solutions such as DEG (diethylene glycol). The processes using fully esterified Li-SIPEG have similar disadvantages.
Therefore, there is a need to develop a process to produce a partially ester-exchanged metal salts of dimethyl 5-sulfoisophthalate that are more stable at room temperature, especially at high concentrations. An advantage of using partially ester-changed metal salts of dimethyl 5-sulfoisophthalate is that less dimer, trimer, and other low molecular weight oligomer are produced resulting a more uniform basic dye site distribution in the resulting polymer. Another advantage is that higher concentration equivalent to 40% to 60% Na-SIPEG can be injected into DMT monomer line or TPA oligomer line. Also an advantage is that manganese catalyst is not required. A further advantage of the invention is that the partially ester-exchanged metal salts of 5-sulfoisophthalate can be made immediately before it is used in producing polyester thereby significantly reducing manufacturing and transportation cost.
Additionally, it is well known that phosphoric acid is commonly used to control the discoloration of polyester homopolymer, but phosphoric acid in some cases 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 phosphorus compound, especially those non-acidic ones, to improve the color of dyeable polyester.
SUMMARY OF THE INVENTION
A process that can be used for producing a partially ester-exchanged metal salt of dimethyl 5-sulfoisophthalate is disclosed, which comprises contacting a metal salt of dimethyl 5-sulfoisophthalate with a glycol to produce a mixture and heating the mixture under a condition sufficient to partially ester-exchange the methyl group in the metal salt of dimethyl 5-sulfoisophthalate wherein the mixture optionally comprises a catalyst.
Also 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 partially ester-exchanged metal salt of dimethyl 5-sulfoisophthalate 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.
DETAILED DESCRIPTION OF THE INVENTION
The acronym “SIPM” used in the application can have the formula of (RO(O)C)
2
ArS(O)
2
OM′ in which R is methyl group or mixture of methyl group and hydrogen; and M′ is hydrogen, an alkali metal, an alkaline earth metal, quatemary ammonium or phosphonium, or combinations of two or more thereof. The preferred M′ is an alkali metal such as lithium or sodium. Accordingly, SIPM, unless otherwise specifically indicated, can also include those metal salts of 5-sulfoisoterephthalic acid that are partially or fully esterifted with methanol. As such, “SIPM”, unless otherwise specifically indicated, can be any me
Duan Jiwen F.
Ma Xianyin
Acquah Samuel A.
E. I. du Pont de Nemours and Company
Shay Lucas K.
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