FIBER-BASED CONTAINER

Abstract

The invention relates to a fiber-based container comprising a first layer made of compressed pulp, which forms a dimensionally stable sleeve and encloses an interior. The sleeve is at least partially coated with a second layer made of a partially crystalline polyester, and the partially crystalline polyester is applied in the form of a fluid or powder.

Claims

1. Fiber-based container comprising: a first layer of compressed pulp, which forms a dimensionally stable sleeve and encloses an interior; and a second layer made of a partially crystalline polyester applied in the form of a fluid or powder applied to and at least partially coating the sleeve.

2. Container according to claim 1, wherein the second layer is attached to the inner side of the sleeve, which faces the interior.

3. Container according to claim 1, wherein the second layer takes over the function of a barrier from the filling material to the fiber material and the environment.

4. Container according to claim 1, wherein the second layer (15) is constructed by spherulitic polyester crystallization.

5. Container according to claim 1, wherein the container is pressure-stable at an internal pressure of up to 8 bar of shaking pressure, wherein the pressure stability results from the shape and the mechanical properties of the first layer.

6. Container according to claim 1, wherein a water vapor barrier of the container has a value of less than 4 g/m.sup.2d at 23? C. and 50% RH.

7. Container according to claim 1, wherein a water vapor barrier of the container has a value of less than 15 g/m.sup.2d at 30? C. and 80% RH or at 38? C. and 90% RH.

8. Container according to claim 1, wherein an oxygen barrier of the container has a value of less than 1 g/m.sup.2d at 23? C. and 80% RH.

9. Container according to claim 1, wherein a CO2 barrier is defined in that the initial CO2 concentration within the container is between 1 and 10 g/l and deviates from the initial value by no more than 5% within a period of one month.

10. Container according to claim 1, wherein a layer thickness of the second layer is less than 0.3 mm.

11. Container according to claim 1, wherein the second layer has a biobased polyester fraction of at least 80 wt %, wherein the biobasis is defined according to the ASTM D 6866, CEN/TS 16137 and ISO 16620 standards.

12. Container according to claim 1, wherein the second layer is biodegradable according to the DIN EN 13432 standard.

13. Container according to claim 1, wherein the second layer contains nucleating agents, comprising talc or CaCO3.

14. Container according to claim 1, wherein the crystallite melting point of the partially crystalline polyester is less than 245? C.

15. Container according to claim 1, wherein the container contains degradation accelerators for the polyester, comprising alkalizers for a saponification of the partially crystalline polyester and/or enzymes that separate the partially crystalline polyester.

16. Container according to claim 1, wherein the second layer is applied in a powder coating method with a subsequent sintering process or is applied in a spray method.

17. Container according to claim 1, wherein the partially crystalline polyester is modified with a plasma coating for improving one or more barrier properties of the container.

18. Container according to claim 17, wherein the plasma coating is a glass coating on a basis of hexamethyldisiloxane or a diamond-like carbon coating on a basis of acetylene.

19. Container according to claim 11, wherein the biobased polyester is polyethylene terephthalate, polyethylene furanoate, polyethylene isosorbide terephthalate, polylactide, polybutylene succinate, poly-?-caprolactone, or polyhydroxyalkanoate, in particular polyhydroxybutyrate.

20. Container according to claim 11, wherein the biobased polyester is produced in part from CO.sub.2 exhaust gases.

21. Container according to claim 11, wherein the biobased polyester is produced from biomass that is unsuitable as food.

22. Container according to claim 1, wherein the partially crystalline polyester of the second layer contains copolymers.

23. Container according to claim 1, wherein the partially crystalline polyester has a light barrier against UV light, visible light and infrared light, which brings about a transmission reduction between a wavelength of 350 and 550 nm of at least 30%, wherein the light barrier is realized by a coloring of the second layer.

24. Container according to claim 1, wherein the partially crystalline polyester reacts with atmospheric oxygen or contains additives that react with atmospheric oxygen, in particular oxygen scavengers, based on oxidation reactions with other polymers.

25. Container according to claim 1, wherein the partially crystalline polyester of the second layer is present in linear form, branched as long chain branches and short chain branches or crosslinked.

26. Container according to claim 1, wherein the second layer is applied as a powder to an inner side of the sleeve by an electrostatic high-voltage method, or a triboelectric or an electrokinetic friction method, and the container is baked in a sintering furnace, wherein a crystalline phase grows through spherulitic crystallization during a sintering process and a crystallization growth takes place by an addition of nucleating agent and holding the temperature between a glass transition temperature and a crystallite melting point.

27. Container according to claim 26, wherein the partially crystalline polyester is applied as a liquid or gas of present unsaturated polyesters or saturated polyesters to an inner side of the sleeve by means of spray methods, one-axis or multi-axis rotational molding, condensation methods and additionally configured to be covered with a plasma coating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1: shows a side view of a partially cut fiber-based container.

DETAILED DESCRIPTION OF THE INVENTION

[0042] FIG. 1 shows a container which is denoted as a whole by reference sign 11. The container 11 can be a bottle, as shown in FIG. 1. The container 11 has a first layer 13 and a second layer 15. The first layer 13 is molded from compressed pulp, which forms a dimensionally stable sleeve 17 and encloses an interior 19. Pulp is typically understood to mean a mixture of water, fibers (in particular paper fibers) and a binder.

[0043] The sleeve 17 is coated with the second layer 15 at least on the side facing the interior 19. The second layer is formed from a partially crystalline polyester, which is applied as a fluid or powder to the sleeve 17. As a result of the partially crystalline structure, the second layer can optimally fulfill the function of the barrier from the filling material to the fiber material and the environment. The first and the second layer therefore act as a composite material in which the individual layers 13, 15 fulfill different tasks in order to obtain a fluid-tight and pressure-stable container 11.

[0044] If the second layer 15 is also applied to the outer side of the sleeve 17, it can protect the sleeve against the environment. This is particularly practical if the container is used in a humid environment, such as a bath room, and is protected from moisture.

[0045] The container 11 can be closed with a screw cap 21 having an internal thread 23. For this purpose, the screw cap 21 can be screwed onto and unscrewed from the container neck 25. An external thread 27 is molded onto the first layer 13 on the container neck 25 and interacts with the internal thread 23. As shown in FIG. 1, the external thread 27 of the container can be coated with the second layer 15. By means of the coating with the second layer 15, the external thread 27 obtains additional mechanical stability and does not tear when the screw cap 21 is screwed on. On the outer side, standing feet 29 can be molded onto the dimensionally stable sleeve 17 so that the container can stand stably.

[0046] The composite of the first and second layers 13, 15 makes it possible for the container to withstand a shaking pressure of up to 8 bar. The container 11 is therefore suitable for filling carbonated beverages, such as mineral water or beer. The pressure stability results from the shape and the mechanical properties of the first layer 13, and the second layer 15 prevents the first layer 13 from being weakened by the filling material and the environment. The shaking pressure corresponds to the CO2 pressure which arises during a standardized shaking operation. The shaking pressure is measured, for example, by means of a CO2 tester from the company Steinfurth Mess-Systeme GmbH.

[0047] The second layer 15 is advantageously constructed by spherulitic crystallization. This results in the following barrier properties, through which the container 11 is suitable for the filling or storage of carbonated beverages. At 23? C. and 50% RH, the water vapor barrier (WVTR) of the container has a value of less than 4 g/m.sup.2d and advantageously less than 1 g/m.sup.2d. At 30? C. and 80% RH or at 38? C. and 90% RH, the water vapor barrier (WVTR) of the container has a value of less than 15 g/m.sup.2d and advantageously less than 10 g/m.sup.2d. The oxygen barrier (OTR) of the container has a value of less than 1 g/m.sup.2d and advantageously less than 0.2 g/m.sup.2d at 23? C. and 80% RH. The CO2 barrier is defined in that the initial CO2 concentration within the container is between 1 and 10 g/l and deviates from the initial value by no more than 5% and advantageously by no more than 1% within a period of one month. These barrier values result at a layer thickness of the second layer of less than 0.3 mm and advantageously less than 0.1 mm.

[0048] The present container is thus excellently suitable for filling carbonated beverages, wherein the second layer 15 is moreover biobased and biodegradable. The second layer has a biobased polyester fraction of at least 80 wt %, wherein the biobasis is defined according to the ASTM D 6866, CEN/TS 16137 and ISO 16620 standards. The biodegradability of the second layer is defined by the ASTM D 6866, CEN/TS 16137 and ISO 16620 standards.

[0049] The polyester of the second layer 15 has a light barrier with respect to UV light, visible light and infrared light, which brings about a transmission reduction between a wavelength of 350 and 550 nm of at least 30%, wherein the light barrier is advantageously realized by a coloring of the second layer. This light barrier makes it possible for vitamins and unsaturated fats in the beverages to be protected over a long time and not to be degraded or destroyed.

[0050] By using a spherulite-forming polyester, a second layer 15 with high crystalline fractions can be formed. As a result, the second layer 15, and thus also the container 11, has very good barrier values. Polyesters that can form spherulites can also be biobased and biodegradable. The sleeve 17 produced from a pulp provides the pressure stability. The container 11 according to the invention therefore not only has such high barrier values that it is suitable for receiving carbonated beverages but also withstands such high shaking pressure that an increased internal pressure cannot deform it. In addition, the container 11 is produced from a first and a second biobased layer 13, 15 and is biodegradable.