Polyesters

Details Polyesters Polyesters

1997-01-07

1998-05-26

Acquah, Samuel A.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

528272, 528274, 528298, 528308, 5283086, 528482, 528503, C08G 6302

Patent

active

057566445

DESCRIPTION:

BRIEF SUMMARY
This invention relates to polyesters, and in particular to aromatic cyclic polyester oligomers and to a method of production thereof.
Aromatic polyesters, such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, have been used in industrial applications for many years. Commercially available aromatic polyesters are generally produced using polycondensation reactions. The resulting polyesters predominantly contain linear chains of repeat units, but also contain very small amounts, of the order of 1 to 2%, of cyclic oligomers. These "naturally occurring" cyclic oligomers have been isolated and characterised. Generally the cyclic oligomers are low molecular weight species, principally cyclic trimer, tetramer and pentamer. Cooper and Semlyen, Polymer, 1973, Vol 14, p 185-192, describe the extraction of cyclic oligomers, containing up to 10 repeat units, from polyethylene terephthalate.
U.S. Pat. No. 5,039,783 describes a solution process of making cyclic polyester oligomers utilising an unhindered tertiary amine. The resulting cyclic polyester oligomers contain predominantly dimer, trimer, tetramer and pentamer, with the largest polyester oligomer produced containing 12 repeat units. The yield of cyclic oligomers produced in U.S. Pat. No. 5,039,783 is relatively low. In addition, relatively large amounts of linear oligomers are also produced, which means that a relatively expensive extraction stage is required in order to separate the cyclic oligomers from the linear oligomers. U.S. Pat. No. 5,039,783 also describes converting the cyclic polyester oligomers to linear polyesters. The molecular weight of the linear polyesters produced from the cyclic oligomers depends, inter alia, on the molecular weight, ie the number of repeat units, of the cyclic oligomers. There is a requirement for higher molecular weight polyester and improved methods of producing high molecular weight polyester than standard linear polyester polycondensation reactions or by converting the cyclic oligomers described in U.S. Pat. No. 5,039,783 to linear polyesters.
Hodge et al, J Chem Soc Chem Commun, 1993, p 581-583, describes a method of producing aliphatic cyclic polyester oligomers using a solid support.
We have now produced an aromatic cyclic polyester composition and method of production thereof which reduces or substantially overcomes one or more of the aforementioned problems.
Accordingly, the present invention provides a composition comprising a mixture of cyclic polyester oligomers having different numbers of repeat units, wherein the mixture comprises at least one cyclic polyester oligomer containing 15 or more repeat units, and at least one of the repeat units has the formula ##STR1## wherein X represents an alkylene radical containing 2 to 6 carbon atoms, and Y represents a phenylene radical or a naphthalene radical.
The invention further provides a method of producing cyclic polyester oligomers by (i) attaching on to a solid support a monomer containing a unit of formula ##STR2## wherein X represents an alkylene radical containing 2 to 6 carbon atoms, Y represents a phenylene radical or a naphthalene radical, and one of A or B represents a leaving group and the other of A or B represents an attaching group, and (ii) heating the solid support containing the attached monomer, resulting in polymerisation, cyclisation and release from the solid support of cyclic polyester oligomers.
Cyclic polyester oligomers according to the invention contain at least one repeat unit having the formula ##STR3## wherein X preferably represents a propylene, butylene or neopentylene radical, and more preferably an ethylene radical. Y preferably represents a m- or p-phenylene radical.
In a preferred embodiment of the invention the composition of cyclic polyester oligomers comprises greater than 30 mole %, more preferably greater than 50 mole %, particularly greater than 70 mole %, and especially greater than 90 mole % up to 100 mole % of one or more repeat units as defined herein. In a further preferred embodiment

REFERENCES:
patent: 5039783 (1991-08-01), Brunelle et al.
patent: 5214158 (1993-05-01), Brunelle et al.
patent: 5214198 (1993-05-01), Brunelle et al.
patent: 5302484 (1994-04-01), Odell et al.
patent: 5314779 (1994-05-01), Odell et al.
patent: 5348985 (1994-09-01), Pearce et al.
patent: 5550173 (1996-08-01), Hammond et al.
Hodge et al., "A Novel Approach to the Synthesis of Cyclic Oligo-and Poly-esters", J. Chem. Soc., Chem, commun., 1993, 581-583.
Hodge et al. Journal of the Chemical Solciety, Chemical Communications, 1993 Letchworth 6B, pp. 581-583, "A Novel Approach to the Synthesis of Cyclic Oligo -Poly-esters".

Affiliated with

Also associated with

Rating

Polyesters does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Polyesters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyesters will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1961561