Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Patent
1998-10-05
2000-11-14
Kuhns, Allan R.
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
264153, 264251, 264320, B29C 4406, B29C 5102
Patent
active
061465631
DESCRIPTION:
BRIEF SUMMARY
The invention is in the field of the packaging industry and relates to a method according to the generic part of the first independent claim, which method serves for manufacturing packaging items of parts thereof by thermoforming corresponding blanks, in particular for manufacturing multilayer packaging items which contain at least one layer serving a specific function, e.g. a barrier layer. The invention further relates to an apparatus for carrying out the method and to packaging items and parts thereof which items or parts are manufactured according to the inventive method.
Many packaging items are manufactured from thermoplastic materials by thermoforming corresponding blanks. If the item is to consist of a plurality of layers serving different purposes, the blanks are usually made from a multi-layer sheet or film material produced e.g. by coextrusion or lamination, which sheet or film material contains all the necessary layers. Such layers are e.g. outer layers of polyethylene or polypropylene giving the item its necessary mechanical strength (bulk-layers) and inner layers serving specific functions (functional layers) such as e.g. barrier functions for improvement of the tightness of the item regarding aroma compounds (aroma barrier layer) regarding gas loss or exchange (gas barrier layer) or regarding light (light barrier layer). Further layers may be adhesive layers for improving the adhesion between outer layers and inner layers and/or surfaces layers serving as sealing layers.
Layers for specific functions such as barrier functions usually consist of more expensive material than the layers giving the item its mechanical strength. Gas barrier layers consist e.g. of ethylene-vinyl alcohol copolymer, which material is not only costly but also represents a foreign body in the packaging item possibly causing recycling problems. For these reasons it is one of the aims of development, to reduce the thickness of such layers, e.g. barrier layers, to the minimum thickness needed for the specific function.
Known methods for manufacturing packaging items including producing a multilayer sheet or film material and thermoforming this material or corresponding blanks punched out of the material, give satisfactory results as long as the thickness of the finished thermoformed item is small and as long as this thickness is more or less homogeneous, i.e. as long as the finished item has a small and substantially uniform wall thickness. If the thickness of the item to be made by thermoforming, differs considerably for varying portions of the item, at least the thicker parts of the packaging item will contain layers whose thickness is not determined by their function only, but much more by the manufacturing method.
In the publication EP-533437 it is proposed to produce thermoformable blanks for multilayer packaging items from a sheet material and add the bulk material by injection moulding it onto the sheet material.
Plastic bottles for water or soft drinks are e.g. made from a middle cylindrical part and bottom and top parts welded to the cylindrical part. The cylindrical part is preferably made from a multilayer sheet material by welding two opposite edges of a flat blank together. Top and bottom parts are made by thermoforming blanks of a similar sheet material. The top part includes a threaded neck portion around a pouring opening on which neck portion, after filling the bottle, a threaded cover is fixed. To give this neck portion sufficient mechanical strength, it needs to have a wall thickness of approximately 1.2 mm. For the reminder of the top part, for the bottom part and the cylinder part, a thickness of approximately 0.6 mm is sufficient.
The top part of such a bottle may serve to illustrate the above discussed problems arising in production of packaging items with areas of different wall thickness and containing at least one layer which, for a specific function needs to have at least a given minimum thickness and which, for mostly economical reasons should not be thicker. For the above described bottle, th
REFERENCES:
patent: 3717544 (1973-02-01), Valyi
patent: 3939239 (1976-02-01), Valyi
patent: 4327052 (1982-04-01), Sauer
patent: 4797244 (1989-01-01), Sauer
patent: 5049060 (1991-09-01), O'Leary
patent: 5647495 (1997-07-01), Orimoto et al.
Charriere Olivier
Holland Geoff
Kuhns Allan R.
Tetra Laval Holdings & Finance
LandOfFree
Method for manufacturing packaging items or parts thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing packaging items or parts thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing packaging items or parts thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2062032