METHOD FOR THE DIRECT PRODUCTION OF POLYESTER ARTICLES FOR PACKAGING PURPOSES AND ARTICLES OBTAINED THEREFROM
First Claim
1. Method for the production of polyester articles for packaging purposes, containing an amount less than 10 ppm of acetaldehyde, consisting of essentially the following steps:
- a) providing a polyethylene terephthalate based polymer melt which is directly produced by conversion of more than 90 weight % of terephthalic acid or dimethyl terephthalate and ethylene glycol, the polymer melt having an intrinsic viscosity (IV0) at an outlet of a polycondensation reactor in a range of 0.5 dl/g to 0.90 dl/g;
b) adding to sad the polymer melt, a mixture of at least one inert and at least one reactive substances which reacts with at least one of the groups selected from the group consisting of the —
COOH, —
OH, —
COO—
CH═
CH2 end groups of the polyester and the ester bonds of the polyester chain in order to cause an increase of the sum of end groups from an initial level SE0 at the end of step a) to a first level SE1 at the end of his step b); and
c) removing low molecular weight monomer substances having a molecular weight of not greater than 500 g/mol present and formed, the non-reacted reactive substance(s) and the inert substance(s) added during step b) after a reaction time of greater than 1 second and less than 3600 seconds by subjecting the polymer melt to a degassing step comprising applying a vacuum of 0.05-800 mbar causing a partial polycondensation, which thereby causes a decrease of the sum of end groups from said first level SE1 to a second sum of end group level SE2 at the end of this step; and
d) converting directly the obtained polymer melt into desired articles.
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Accused Products
Abstract
The present invention is related to a method for the direct production of polyester articles for packaging purposes, in particular for the production of hollow bodies, thermoformed sheets and films, said articles containing an amount of acetaldehyde less than 10 ppm. This method is characterised in that it essentially comprises a step in which the initial level SE0 of the sum of end groups in the polymer melt is increased by adding a mixture of at least one inert and at least one reactive substance to said polymer melt to a second level SE1 and a degassing step consisting in essentially applying a vacuum to the previously obtained polymer melt to cause a removal of low molecular weight substances present and formed, of non reacted reactive substance(s) and inert substance(s) added during previous step before the so obtained polymer melt is directly converted into the desired articles.
40 Citations
14 Claims
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1. Method for the production of polyester articles for packaging purposes, containing an amount less than 10 ppm of acetaldehyde, consisting of essentially the following steps:
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a) providing a polyethylene terephthalate based polymer melt which is directly produced by conversion of more than 90 weight % of terephthalic acid or dimethyl terephthalate and ethylene glycol, the polymer melt having an intrinsic viscosity (IV0) at an outlet of a polycondensation reactor in a range of 0.5 dl/g to 0.90 dl/g; b) adding to sad the polymer melt, a mixture of at least one inert and at least one reactive substances which reacts with at least one of the groups selected from the group consisting of the —
COOH, —
OH, —
COO—
CH═
CH2 end groups of the polyester and the ester bonds of the polyester chain in order to cause an increase of the sum of end groups from an initial level SE0 at the end of step a) to a first level SE1 at the end of his step b); andc) removing low molecular weight monomer substances having a molecular weight of not greater than 500 g/mol present and formed, the non-reacted reactive substance(s) and the inert substance(s) added during step b) after a reaction time of greater than 1 second and less than 3600 seconds by subjecting the polymer melt to a degassing step comprising applying a vacuum of 0.05-800 mbar causing a partial polycondensation, which thereby causes a decrease of the sum of end groups from said first level SE1 to a second sum of end group level SE2 at the end of this step; and d) converting directly the obtained polymer melt into desired articles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 12, 13, 14)
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10. Polyester articles for packaging purposes comprising an acetaldehyde content of less than 10 ppm, provided by a method consisting of essentially the following steps:
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a) providing a polyethylene terephthalate based polymer melt which is directly produced by conversion of more than 90 weight % of terephthalic acid or dimethyl terephthalate and ethylene glycol, the polymer melt having an intrinsic viscosity (IV0) at an outlet of a polycondensation reactor in a range of 0.5 dl/g to 0.90 dl/g; b) adding to the polymer melt, a mixture of at least one inert and at least one reactive substances which reacts with at least one of the groups selected from the group consisting of the —
COOH, —
OH, —
COO—
CH═
CH2 end groups of the polyester and the ester bonds of the polyester chain in order to cause an increase of the sum of end groups from an initial level SE0 at the end of step a) to a first level SE1 at the end of step b);c) removing low molecular weight monomer substances having a molecular weight ≦
500 g/mol present and formed, the non-reacted reactive substance(s) and the inert substance(s) added during step b) after a reaction time of >
1 second and <
3600 seconds by subjecting the polymer melt to a degassing step comprising applying a vacuum of 0.05-800 mbar causing a partial polycondensation, which thereby causes a decrease of the sum of end groups from said first level SE1 to a second sum of end group level SE2 at the end of this step; andd) converting directly the obtained polymer melt into desired articles.
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11. Method for the production of polyester articles comprising less than 10 ppm acetaldehyde, comprising the steps:
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a) providing a polyethylene terephthalate based polymer melt which is produced by conversion of more than 90 weight % of terephthalic acid or dimethyl terephthalate and ethylene glycol, the polymer melt having an intrinsic viscosity (IV0) at the outlet of the polycondensation reactor in a range of 0.5 dl/g to 0.90 dl/g; b) adding to the polymer melt, a mixture of at least one inert and at least one reactive substances which reacts with the —
COOH, —
OH, or —
COO—
CH═
CH2 end groups of the polyester and/or with the ester bonds of the polyester chain thereby causing an increase of the sum of end groups from an initial level SE0 at the end of step a) to a first level SE1 at the end of step b),c) removing low molecular weight monomer substances that are formed and have a molecular weight of not greater than 500 g/mol, the non-reacted reactive substance(s) and the inert substance(s) added during step b) after a reaction time of less than 3600 seconds by subjecting the polymer melt to a degassing step causing a decrease of the sum of end groups from the first level SE1 to a second sum of end group level SE2 at the end of step c); and d) converting directly the polymer melt into the desired articles.
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Specification