PROCESS AND APPARATUS FOR PRODUCING PACKETS

Abstract

Provided is a process for thermoforming a gas and liquid permeable layer (10) of thermoplastic material having an average thickness of less than 1.0 mm, the process comprising the steps of bringing the layer of thermoplastic material, at a temperature below that required for thermoforming, into contact with a mould (16) at a temperature above that of a thermoforming temperature of the thermoplastic material; pressing the mould into contact with the layer of thermoplastic material, the contact between mould and thermoplastic material causing heat to transfer from the mould to the thermoplastic material and raising the temperature of the thermoplastic material to a thermoformable temperature; such pressing thereby causing thermoforming of the thermoplastic material to conform to the shape of the mould.

Claims

1.-13. (canceled)

14. A process for producing infusion packets with infusible tea leaves deposited therein, the process comprising the steps of: (i) providing a gas and liquid permeable layer of thermoplastic material which exhibits plastic deformation behavior over a temperature range of at least about 20 C.; and having an average thickness of less than about 0.5 mm, wherein the thermoplastic material comprises polyethylene terephthalate or poly-lactic acid; (ii) bringing the layer of thermoplastic material, at a temperature below that required for thermoforming, into contact with a mold at a temperature above that of a thermoforming temperature of the thermoplastic material; wherein the thermoplastic material, before coming into contact with the mold, is at a temperature of from about 15 C. to about 35 C.; wherein the temperature of the mold is at least about 100 C.; (iii) pressing the mold into contact with the layer of thermoplastic material, said mold having a tetrahedral or hemispherical conformity shape; wherein heat transfer from the mold to the layer of thermoplastic material raises the temperature of the layer of thermoplastic material to a thermoformable temperature; such pressing thereby causing thermoforming of the layer of thermoplastic material to conform to the shape of the mold; followed by (iv) depositing infusible tea leaves onto the layer of thermoformed thermoplastic material which is formed into packet shape; and further followed by (v) sealing the thermoformed packet to produce a sealed porous infusion packet with infusible tea leaves deposited therein.

15. The process according to claim 14, wherein the thermoplastic material exhibits plastic deformation behavior over a temperature range of at least about 40 C.

16. The process according to claim 14, wherein the layer of thermoplastic material is made from woven fibers of thermoplastic material.

17. The process according to claim 16, wherein the fibers have a diameter of less than about 0.5 mm.

Description

[0029] The invention will now by illustrated by way of example and with reference to the following figures, in which:

[0030] FIG. 1 is a schematic representation of thermoforming apparatus suitable for carrying out a process according to the present invention

[0031] FIG. 2 is a schematic representation of the same apparatus as shown in FIG. 1 during carrying out a process according to the present invention.

[0032] Turning to the figures, FIG. 1 shows a woven sheet of 50 micrometres thick poly lactic acid 10 clamped in place by upper clamps 12 and lower clamps 14. The woven sheet 10 is at 20 C.

[0033] Positioned above the woven sheet is a male former 16, at a temperature of 120 C.

[0034] In use, the male former 16 moves downwards to come into contact with the woven sheet 10. As it makes contact, the portion of the woven sheet 10 that come into contact with the male former 16 rapidly heat up to 120 C. due to its very low heat capacity.

[0035] The male former continues to move downwards, heating and thermoforming the woven sheet simultaneously, until the male former is in the position shown in FIG. 2.

[0036] Once the woven sheet 10 is fully thermoformed, the male former retracts and the woven sheet rapidly cools and sets, again due to its very low heat capacity.