Recycled pet barrier bottle

Abstract

The invention relates to a preform for producing a plastic container in a blow moulding method, comprising an elongated, preform body, which is formed so as to be closed at the one longitudinal end thereof and, at the other longitudinal end thereof, has a neck section having a pouring opening. The preform is produced from recycled PET and aliphatic furanoate, wherein the recycled PET has a maximum of 2.5 wt % of isophthalic acid and diethylene glycol, wherein the proportion of isophthalic acid is no higher than 2.0 wt %, and the proportion of diethylene glycol is no higher than 2.0 wt %, wherein all the percentages by weight are based on the total weight of the preform. Turbidity of the preform, measured in accordance with ASTM D I 003-00, is less than 5%, as a result of the admixture of the aliphatic furanoate.

Claims

1. A preform for producing a plastic container in a blow molding process, comprising: an elongated, preform body, which is formed so as to be closed at the one longitudinal end thereof, and, at the other end thereof, has a neck section having a pouring opening, the preform body comprised of recycled PET and aliphatic furanoate, wherein the recycled PET has a maximum of 2.5 percent by weight of a mixture of isophthalic acid and diethylene glycol, wherein either the isophthalic acid or the diethylene glycol of the mixture comprises at most 2.0 percent by weight of the recycled PET, wherein all percentages by weight are based on a total weight of the preform body, and wherein a clouding of the preform body measured according to ASTM D 1003-00 by admixture of the aliphatic furanoate is less than 5%.

2. The preform of claim 1, wherein the admixture of the aliphatic furanoate is between 4% and 40% by weight based on the total weight of the preform body.

3. The preform of claim 1, wherein the preform body has a wall thickness that is between 3 mm and 10 mm.

4. The preform of claim 1, wherein the preform body is configured to form a reusable container.

5. A PET barrier bottle, comprising: an elongated body that is closed at the one longitudinal end thereof, and, at the other end thereof, has a neck section having a pouring opening, the body comprised of recycled PET and aliphatic furanoate, wherein the recycled PET has a maximum of 2.5 percent by weight of a mixture of isophthalic acid and diethylene glycol, wherein either the isophthalic acid or the diethylene glycol of the mixture comprises at most 2.0 percent by weight of the recycled PET, wherein all percentages by weight are based on a total weight of the preform body, wherein a clouding of the preform body measured according to ASTM D 1003-00 by admixture of the aliphatic furanoate is less than 5%, and wherein the aliphatic furanoate has a b value less than 5 and an L value greater than 76 from a CIELAB color space.

6. The PET barrier bottle of claim 5, wherein the body has a wall thickness that it is suitable for refilling or as a reusable bottle.

7. The PET barrier bottle of claim 6, wherein the body has a wall thickness that is between 3 mm and 10 mm.

8. The PET barrier bottle of claim 5, wherein the admixture of the aliphatic furanoate is between 4% and 40% by weight based on the total weight of the preform body.

9. The PET barrier bottle of claim 5, wherein the body is configured to form a reusable PET barrier bottle.

10. A method of producing a preform, comprising: providing a mixture of plastic granules; and producing a preform from the mixture of plastic granules by injection molding, the mixture of plastic granules comprised of recycled PET and an aliphatic furanoate of less than 5.0 percent by weight, wherein the recycled PET has a maximum of 2.5 percent by weight of a mixture of isophthalic acid and diethylene glycol, wherein either the isophthalic acid or the diethylene glycol of the mixture comprises at most 2.0 percent by weight of the recycled PET, wherein all percentages by weight are based on a total weight of the preform, and wherein a haze of the preform is measured according to ASTM D 1003-00.

11. The method of claim 10, wherein the aliphatic furanoate is between 4% and 40% by weight based on the total weight of the preform.

12. The method of claim 10, wherein the mixture is used to form a preform.

13. The method of claim 12, wherein the preform is used to form a reusable PET barrier bottle.

14. A mixture of recycled PET and aliphatic furanoate for forming a preform, comprising: recycled PET having a maximum of 2.5 percent by weight of a mixture of isophthalic acid and diethylene glycol, wherein either the isophthalic acid or the diethylene glycol of the mixture comprises at most 2.0 percent by weight of the recycled PET, and wherein all percentages by weight are based on a total weight of the mixture.

15. The mixture of claim 14, wherein a proportion of the aliphatic furanoate is between 4% and 40% by weight based on the total weight of the mixture.

16. The mixture of claim 14, wherein the mixture is combined to form a preform.

17. The mixture of claim 16, wherein the preform is used to form a reusable PET barrier bottle.

Description

DETAILED DESCRIPTION

(1) The invention relates to a PET barrier bottle, which is produced of at least 50 wt % PET reclaim or recycled PET. For the purpose of this application, PET reclaim is understood to mean a PET raw material which is produced from PET bottles that have already been used. The PET reclaim may be available as granules or as chips obtained by comminuting the bottles. The PET reclaim originates at 100% from already used PET, in particular PET bottles. Newly produced PET, so-called virgin PET, is not present in the PET reclaim.

(2) The more often the PET reclaim is fed into the recycle cycle, the more yellow it turns, turns green and darkens and becomes cloudy. On the one hand, this is due to contaminants, which inevitably accumulate in the PET reclaim. The contaminants may be glass splinters, other polymers, grains of sand, etc. The contaminations themselves and as crystallization seeds for the crystallization of the PET lead to clouding and to a yellow tinge and a green tinge of the PET reclaim.

(3) In addition, the PET reclaim becomes more yellow and green with every further processing.

(4) If the PET bottle contains an addition of polyamide, the polyamide leads to an improved barrier of the PET bottle with respect to oxygen and carbon dioxide. However, the polyamide clearly yellows more heavily than the PET. Therefore, PET bottles containing polyamides are sorted out prior or during recycling, for example by optical sensors (control systems), which, e.g., identify the spectra of the bottles or flakes by laser or infrared or discard yellowish or cloudy bottles or flakes.

(5) The PET barrier bottle has a barrier with respect to oxygen at a fill volume of 500 ml, which is defined in that the oxygen increase into the interior of the bottle is 1 ppm of oxygen within 11 days. The PET barrier bottle has a barrier with respect to carbon dioxide at a fill volume of 500 ml, which is defined in that, within 11 weeks, 20 wt % of carbon dioxide escapes from the interior of the bottle. The aliphatic furanoates effect that the carbon dioxide and/or the oxygen barrier is increased by at least 10% compared to regular PET. In the exemplary embodiment, in a comparable PET bottle with a fill volume of 500 ml, which contains exclusively PET, an increase in oxygen inside the bottle of 1 ppm oxygen occurs within 10 days. In the exemplary embodiment, with a comparable PET bottle with a fill volume of 500 ml, which contains exclusively PET, a carbon dioxide decrease in the interior of the bottle of 20 wt % of carbon dioxide correspondingly results within 10 weeks.

(6) The roasting test is used to identify special bottles that are particularly damaging to the recycling flow due to yellowing and clouding. The results of the roasting test are used to teach and set the optical separation sensors specifically for these bottles.

(7) The added polyamide also causes clouding of the PET bottle as this forms small polyamide domains in the PET matrix, at which the light is scattered.

(8) In addition, catalysts (for example cobalt salts) may be present in the PET bottles, which bring the polyamide but also the PET to oxidation. As a result, the product is protected from the reaction with atmospheric oxygen, since it reacts with the packaging. However, this oxidation reaction also leads to a yellowing of the PET bottle or PET packaging.

(9) In all examples, the yellowing of the PET is due to oxidative and thermal degradation reactions of the PET itself, additives therein or reclaims therein. Accordingly, any processing of the PET in an injection molding machine or a recycling extruder leads to a further yellowing.

(10) Surprisingly, PET recycle can be combined with aliphatic furanoates. After mixing the granule or the PET recycle grinders with the furanoate granule, they form a copolymerization during melting during the injection molding process. The copolymerization also causes the clouding to be reduced because the copolymerization counteracts crystal formation and, in contrast to polyamide, aliphatic furanoates do not form domains in the PET matrix but react with the PET matrix.

(11) A person skilled in the art would not consider a combination of PET recyclate with aliphatic furanoates, since aliphatic furanoates often turn yellow or form domains in the PET themselves during processing and would regard the aliphatic furanoates as contamination.

(12) This not without good reason, since a processing time which is too long or a processing temperature which is too high causes the mixture of the reclaim and the aliphatic furanoates to yellow too much. However, with a longer processing time or an increased processing temperature, copolymerization and transparency are improved. In contrast, a processing temperature and a dwell time which are too low have a positive effect on the prevention of yellowing, but the copolymerization does not take place at a working temperature which is too low.

(13) Temperatures of 270 to 300° C. and dwell times of 30 to 300 seconds in the preform injection molding machine have proven to achieve a sufficient degree of copolymerization and low yellowing.

(14) In addition to the polyethylene furanoate, other aliphatic furanoates can also be used in the mixture with PET recyclate. This may be, for example, polymethylene furanoate, polypropylene furanoate, polybutadiene furanoate or polyphenylene furanoate, or a mixture of several different aliphatic furanoates.

(15) The PET bottles produced with the mixture of PET recyclate and aliphatic furanoates have similarly good barrier properties that are achieved with PET bottles laced with polyamide. The PET bottles, which contain PET recyclate and aliphatic furanoates, can be recycled in contrast to PET bottles laced with polyamide because they yellow much less than the polyamide. Accordingly, it is possible by means of the present invention to add PET bottles with barrier to the recycling flow.

(16) The mixture for producing the PET bottle contains more than 50 wt % of PET recyclate or between 4 and 40 wt % of aliphatic furanoates. If the PET recyclate and the aliphatic furanoate do not add up to 100 wt %, the mixture may additionally contain virgin PET, thus non-recycled PET.

(17) By adding an aliphatic furanoate to the mixture, the PET bottle has a very good b and L value. A b value of less than 5 and an L value greater than 76 can be achieved. These specifications show that the yellow tinge and the amount of darkness are in areas that are acceptable for PET bottles and do not additionally yellow and cloud the recycling stream.

(18) During the injection molding of the preform, which is stretch-blown to produce the PET bottle, the mixture of PET recyclate and aliphatic furanoate is loaded under 300° C. and with a dwell time in the injection molding machine of less than 100 seconds. This reduces the strain on the mixture, which leads to thermal decomposition reactions and an associated high yellowing. The thermal degradation reactions can also be reduced by drying the mixture of PET recyclate and aliphatic furanoate at a temperature above 155° C. prior to processing in the injection molding machine. As a result, shear forces and the thermal degradation in the injection molding machine are also kept as small as possible. An addition of phosphoric acid to the mixture also causes a reduction in thermal degradation.

(19) If the wall thickness of the preform is more than 2 mm, the PET homopolymer tends to have a strong crystallization. The crystallized preform would thus not be able to be blown at all. Therefore, up to 3 wt % of diethylene glycol and up to 6 wt % of isophthalic acid are usually added to the PET. This inhibits crystal formation.

(20) The present PET bottle contains less than 1 wt % of isophthalic acid, because the aliphatic furanoate acts as a crystallization inhibitor due to its excellent copolymerizing properties with PET.