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Improved polyester production, polyester quality improvement and enhancing melt strength of polyesters by the use of phosphonates in combination with polyfunctional compounds

IP.com Disclosure Number: IPCOM000022516D
Publication Date: 2004-Mar-19

Publishing Venue

The IP.com Prior Art Database

Abstract

In the present publication the advantages of using organic phosphonates in combination with polyfunctional compounds in polyester production, as well as the effect of improving polyester quality and enhancing polyester melt strength are described. It is well known that phosphorous containing substances provide benefits during synthesis of polyesters, as well as improved polyester quality. This leads to advantages during production of end products, such as for example bottles, sheets, injection molded articles, films, fibers, yarns and textiles.

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March 19, 2004

Research disclosure

Improved polyester production, polyester quality improvement and enhancing melt strength of polyesters by the use of phosphonates in combination with polyfunctional compounds

It is well known that phosphorous containing substances provide benefits during synthesis of polyesters, as well as improved polyester quality. This leads to advantages during production of end products, such as for example fibers, yarns and textiles. The use of phosphorous containing compounds in various stages of the polyester production is for example described in US 6 489 434, US 6 392 005 and TW 090 125 470.

In the present publication the advantages of using organic phosphonates in combination with polyfunctional compounds in polyester production are described, as well as the effect of improving polyester quality and enhancing polyester melt strength.

Suitable polyesters are for example homopolyesters or copolyesters, which are composed of aliphatic, cycloaliphatic or aro­ma­tic dicarboxylic acids and diols or hydroxycarboxylic acids.

Preferred polyesters are polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytrimethylene tereph­thalate (PTT), and their copolyesters with isophthalic acid, phthalic acid, di-ethylene glycol or cyclohexane dimethanol.

The polyesters can be prepared by direct esterification (PTA process) and also by trans­esteri­fication (DMT process). Any of the known catalyst systems may be used for the prepa­ration.

This polycondensation generally leads to a medium molecular weight, which can be expressed as Intrinsic Viscosity (I.V.) between 0.55 and 0.65 dl/g. Such polyester grades are used for films (e.g. BO-PET), staple fiber, yarn, micro fibers. The fibers may be very fine in the case of micro fibers or rather thick for technical textiles. They are typically in the range of from 100 to 5000 dtex (g/10000m).

For some applications, such as, for example techni­cal fibers, bottles, specialty films and sheets, high molecular weights of the polyester are necessary. These can be obtained for example by solid-state polyconden­sation, SSP, (S.Fakirov, Kunststoffe, 74 (1984), 218 and R. E. Grützner, A. Koine, Kunststoffe, 82 (1992), 284). The prepolymer is in this case subjected to thermal treatment above the glass transition temperature and below the melt temperature of the polymer under inert gas or under vacuum.

By this procedure I.V.-values well above 0.8 dl/g are achieved. The increased molecular weight provides PET with enhanced mechanical properties and higher melt viscosity (which is necessary for melt-converting into the final article). Such polyester grades are used for bottles, injection molded articles, sheets, airbag, broad fabrics, functional clothing, conveyor belt, seat belt, tire cord, hoses, nets, ropes, sewing thread, slings, strapping, transmission belts, fiber reinforcements in plastics (e.g. polypropylene, polyethylene, polystyrene, etc)....