Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing oxygen-containing organic compound
Reexamination Certificate
1998-07-21
2001-02-06
Marx, Irene (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing oxygen-containing organic compound
C435S134000, C435S196000, C435S136000, C435S145000
Reexamination Certificate
active
06184010
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for enzymatic hydrolysis of cyclic oligomers of poly(ethylene terephthalate), which process comprises subjecting the cyclic oligomer to the action of one or more carboxylic ester hydrolases.
BACKGROUND ART
Poly(ethylene terephthalate) fibers accounts for the main part of the polyester applied by the textile industry. The fibers are produced by e.g. poly-condensation of terephthalic acid and ethylene glycol, and drawing of fibers from a melt. During these processes, at high temperatures, cyclic oligomers, in particular cyclic tri(ethylene terephthalate), are formed in and on the fibers.
Cyclic oligomers tend to give fabrics with a content of poly(ethylene terephthalate) fibers a grayish appearance. This is due to deposits of cyclic oligomers on the surface of the fabric, which is particularly outspoken after high temperature wet processes like HT (high temperature) dyeing. The cyclic oligomers are difficult to remove and may even be resistant to an alkaline post treatment [cf. G. Valk et al.; Melliand Textilberichte 1970 5 504-508]. Therefore, to be effective, the alkaline treatment has to be severe, which results in a significant loss of fiber material. Also, organic extraction of the cyclic oligomers is a technical possibility, but not industrially feasible.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an enzymatic process for removal of cyclic oligomers of poly(ethylene terephthalate), in particular cyclic tri(ethylene terephthalate), by which process the cyclic oligomers are enzymatically hydrolyzed to linear fragments, which can then be removed under gentle conditions, or which may even be leftover. Thus the process of the invention avoids the need for harsh chemicals or organic extraction.
Accordingly, the invention provides a process for enzymatic hydrolysis of cyclic oligomers of poly(ethylene terephthalate), which process comprises subjecting the cyclic oligomer to the action of one or more carboxylic ester hydrolases.
DETAILED DISCLOSURE OF THE INVENTION
The present invention relates to a process for enzymatic hydrolysis of cyclic oligomers of poly(ethylene terephthalate). More specifically the invention provides a process for enzymatic hydrolysis of cyclic oligomers of poly(ethylene terephthalate), which process comprises subjecting the cyclic oligomer to the action of one or more carboxylic ester hydrolases, in particular lipolytic and/or biopolyester hydrolytic enzyme(s). In the context of this invention a biopolyester is a polyester of biological origin.
The process of the invention may in particular be applied to yarns or fabrics with a content of poly(ethylene terephthalate) fibers, during which process the content of cyclic oligomers, which were formed as byproducts during synthesis and processing of the fibers, becomes eliminated or at least significantly reduced.
Polyester Fabrics
Poly(ethylene terephthalate) is synthesized by condensation, drawn into fibers from a melt, possibly cut to stables, possibly mixed with other fiber types, and spun to yarn. The yarn is dyed and knitted into cloth or made into carpets, or the yarn is woven into fabric and dyed. These processes can be followed by finishing (post treatment) steps.
During synthesis and drawing, cyclic oligomers of poly(ethylene terephthalate) are formed on and in the fibers. These cyclic oligomers are partly deposited on machinery, partly staying on/in the fibers, which turns out to give an undesirable grayish appearance of the final fabric or carpet.
Cyclic oligomers can be removed by organic extraction, but such a process is not industrially feasible due to cost and problems in handling and regeneration of large quantities of organic solvents. Cyclic oligomers can also be removed by an alkaline post scouring step, but to be effective the alkaline treatment has to be severe and results in significant loss of fiber material, too.
According to the present invention, removal of cyclic oligomers, in particular cyclic trimers, can be accomplished by hydrolysis with one or more hydrolytic enzymes. The enzyme breaks the ring structure of the cyclic oligomer by hydrolyzing an ester bond. The resulting product creates less of a problem, because it can be removed under gentle conditions or even leftover in the product.
The enzymatic treatment does not have the disadvantages valid for organic extraction and alkaline post scouring, in particular is does not require large quantities of organic solvent to be involved, and there is no significant loss of fiber material.
The process of the invention is readily applicable in the textile industry as it can be carried out using existing wet processing apparatus, such as in a beam dyer, a Pad-Roll, a Jigger/Winch, a J-Box, or Pad-Steam types of apparatus. The process preferably takes place during the finishing (post treatment) step.
In a preferred embodiment the process of the invention may be accomplished on cyclic oligomers of poly(ethylene terephthalate) present on and/or in fibers or in yarn or fabric made (or partially made) from poly(ethylene terephthalate) fibers. Thus, the polyester yarn or fabric may be any yarn or fabric that is made from pure poly(ethylene terephthalate), or that is made from blends of poly(ethylene terephthalate) fibers and any other material conventionally used for making yarns or fabrics.
Thus, in a preferred embodiment, the invention provides a process for enzymatic treatment of polyester fibers, which process comprises subjecting the polyester fiber or fabric to the action of one or more carboxylic ester hydrolases, in particular lipolytic and/or biopolyester hydrolytic enzyme(s).
The polyester fabric may be any fabric or fabric blend comprising polyester. Preferably the fabric comprises more than 50% (w/w) of polyester, in particular more than 75% (w/w) of polyester, more than 90% (w/w) of polyester, or more than 95% (w/w) of polyester. In a most preferred embodiment, the process of the invention is applied to fabrics or textiles or yarns consisting essentially of poly(ethylene terephthalate) polyester material, i.e. pure poly(ethylene terephthalate) polyester material.
Hydrolytic Enzymes
The enzymatic finishing process of the invention may be accomplished using any carboxylic ester hydrolases, in particular lipolytic enzyme and/or any biopolyester hydrolytic enzyme. Such enzymes are well known and defined in the literature, cf. e.g. Borgström B and Brockman H L, (Eds.);
Lipases;
Elsevier Science Publishers B.V., 1984, and Kolattukudy P E;
The Biochemistry of Plants,
Academic Press Inc., 1980 4 624-631.
In the context of this invention lipolytic enzymes include true lipases, esterases, phospholipases, and lyso-phospholipases. More specifically the lipolytic enzyme may be a lipase as classified by EC 3.1.1.3, EC 3.1.1.23 and/or EC 3.1.1.26, an esterase as classified by EC 3.1.1.1, EC 3.1.1.2, EC 3.1.1.6, EC 3.1.1.7, and/or EC 3.1.1.8, a phospholipase as classified by EC 3.1.1.4 and/or EC 3.1.1.32, and a lyso-phospholipase as classified by EC 3.1.1.5.
The lipolytic enzyme preferably is of microbial origin, in particular of bacterial, of fungal or of yeast origin.
In a particular embodiment, the lipolytic enzyme used may be derived from a strain of Absidia, in particular
Absidia blakesleena
and
Absidia corymbifera,
a strain of Achromobacter, in particular
Achromobacter iophagus,
a strain of Aeromonas, a strain of Alternaria, in particular
Alternaria brassiciola,
a strain of Aspergillus, in particular
Aspergillus niger
and
Aspergillus flavus,
a strain of Achromobacter, in particular
Achromobacter iophagus,
a strain of Aureobasidium, in particular
Aureobasidium pullulans,
a strain of Bacillus, in particular
Bacillus pumilus, Bacillus strearothermophilus
and
Bacillus subtilis,
a strain of Beauveria, a strain of Brochothrix, in particular
Brochothrix thermosohata,
a strain of Candida, in particular
Candida cylindracea
(
Candida rugosa
),
Candida paralipolytica,
and
Candida antarctica,
a strain of Chromobacter, in
Koch Rainhard
Lund Henrik
Pedersen Lars Saaby
Riegels Martin
Green Reza
Lambiris Elias J.
Marx Irene
Novo Nordisk A S
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