Method for storage and/or transport of lactide particles

Abstract

A method for storage and/or transport of solid lactide particles in a container, includes the steps of a) inserting the lactide particles into the container, b) storing and/or transporting the lactide particles for a period of time in the container, and c) removing the lactide particles from the container. The lactide particles are contained in a big-bag having at least one flexible layer of a plastic material. Storage and/or transport of lactide particles in such big-bag has the advantage that big-bags allow mechanical handling in case of chunks formed by the lactide particles.

Claims

1. A method for storage and/or transport of solid lactide particles in a big-bag comprising at least one flexible layer of a plastic material, said method comprising the following steps: providing an unfilled big-bag; filling the unfilled big-bag with a chemically inert gas; inserting the lactide particles into the big-bag filled with the chemically inert gas; evacuating the big-bag containing the lactide particles and chemically inert gas to substantially remove the gas from the big-bag, closing the evacuated big-bag containing the lactide particles; storing and/or transporting the lactide particles for a period of time in the evacuated big-bag; and removing the lactide particles from the evacuated big bag.

2. The method according to claim 1, further comprising the step of submitting the evacuated big-bag containing the lactide particles to a mechanical crushing operation before removing the lactide particles from the big-bag.

3. The method according to claim 2, and wherein the mechanical crushing operation utilizes a hydraulic crushing apparatus.

4. The method according to claim 3, and further comprising: placing the evacuated big-bag containing the lactide particles on a pallet prior to utilizing the hydraulic crushing apparatus.

5. The method according to claim 1, wherein the chemically inert gas is selected from carbon dioxide, nitrogen and argon, or a mixture thereof.

6. The method according to claim 1, wherein the at least one flexible layer of the big-bag is provided with an inner-liner having a moisture barrier layer.

7. The method according to claim 6, wherein the inner-liner includes an oxygen barrier layer.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

(2) In the drawing:

(3) FIG. 1 shows a container embodied as an octabin for storage and/or transport of lactide particles (not according to the disclosure), and

(4) FIG. 2 shows a container embodied as a big-bag for storage and/or transport of lactide particles (according to the present disclosure).

(5) It is stressed that the Figures are schematic and not to scale.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) In a comparative experiment, the storage and transport of lactide particles in a container not according to the invention (embodied as an octabin) and in a container according to the present invention (embodied as a big-bag) were investigated. For that purpose, an octabin of the type bag in bag (volume 600 kg) having an inner-liner of polyethylene with an oxygen barrier layer and a moisture barrier layer was filled with lactide flakes (PURALACT L). A big-bag (volume 600 kg) having an inner-liner of polyethylene with an oxygen barrier layer and a moisture barrier layer was filled for approximately 70 vol. % with lactide flakes (PURALACT L). Before filling, both types of containers were flushed with a stream of nitrogen gas. After the filling operation with lactide, both containers were sealed and subsequently stored for 30 days at a temperature of 40 C. Before and after the period of storage, the moisture content and the acidity of the lactide were determined.

(7) FIG. 1 shows a perspective view of an octabin 1, which is positioned on a pallet 2. The vertical sides 3 of the octabin have an eight-sided horizontal circumference and are made of cardboard. The octabin is covered on top and bottom with removable covers 4 of cupboard. The octabin comprises an inner-liner of polyethylene (not shown), which is provided with a layer of aluminum as a moisture barrier layer and an oxygen barrier layer.

(8) FIG. 2 shows a perspective view of a big-bag 11, which is made of a flexible, woven layer of polyethylene and/or polypropylene. The big-bag container is provided with four hooks 12 for lifting the big-bag. It is also provided with an inlet spout 13 at the top of the big-bag and an outlet spout (or discharge spout) at the bottom of the big-bag (not shown). Inside the flexible layer of the big-bag, a laminated inner-liner of an aluminum layer sandwiched between two polyethylene layers is attached (not shown). The inner-liner is also provided with an inlet spout and an outlet spout. Said spouts may be sealed to prevent inlet of atmospheric gas. The spouts attached to the flexible layer may be closed by means of short ropes 14.

(9) After the 30 days of storage at 40 C. of the lactide particles, some chunk formation (caking) appeared to have occurred in both types of containers, which caused flow-out problems of the lactide flakes during emptying the containers. However, the lactide outflow from the big-bag containers appeared to be significantly better and quicker than from the octabin container. Moreover, the dimensions of the remaining chunks in the big-bag could easily be reduced by applying mechanical forces (crushing or beating the flexible plastic layer of the container). Reducing lactide chunks in the octabin container appeared to be more difficult, as comparable mechanical actions were not possible in view of expected damage to the cardboard surfaces surrounding said octabin container.

(10) The same containers with the same lactide material (again in flake form) were stored for 90 days at the same temperature of 40 C. After this period, severe caking appeared to have been occurred in both containers. Removing the lactide from the octabin container was only possible after destruction of the octabin. The lactide could not be removed in a simple manner from the big-bag, even not after applying the simple mechanical action of kicking, beating or crushing the outside of this container. However, the dimensions of the lactide chunks could be reduced by means of a mechanical crushing operation applied on the container before removing the lactide. For this purpose, the big-bag was positioned on a pallet in a hydraulic crushing apparatus. Due to the flexible wall of the big-bag, this apparatus was able to press the container with a pressure of several bars. During said crushing operation, the chunks substantially disintegrated into lactide powder, without damage to the big-bag. Such crushing operation could not be applied to octabins, due to immediate damage of the outer walls of cardboard

(11) Some simple experiments showed the effect of the oxygen and the moisture barrier layers. In the absence of these layers, the moisture and oxygen content in the containers (both the octabin and the big-bag type) appeared to be higher than when these layers were present.

(12) In summary, the above-described experiments clearly show that storage and/or transport of lactide particles in big-bag containers has a clear advantage over their storage in octabin containers. This is because big-bags are flexible whereas octabins are not. This difference allows mechanical handling of big-bags in case of chunks formed by the lactide particles, whereas such handling is not possible for octabins.

(13) While aspects of the invention has been illustrated and described in detail in the drawing and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

(14) In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of these claims.