Coating processes – Interior of hollow article coating – Coating by vapor – gas – mist – or smoke
Reexamination Certificate
2002-07-15
2004-12-07
Beck, Shrive P. (Department: 1762)
Coating processes
Interior of hollow article coating
Coating by vapor, gas, mist, or smoke
C427S534000
Reexamination Certificate
active
06827972
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to containers, such as bottles or flasks, of a heterogeneous structure made from a material which produces a barrier effect and a polymer material.
DESCRIPTION OF THE PRIOR ART
The disadvantage of containers made from a polymer material such as PET is that they are not impermeable to certain gases, particularly oxygen and carbon dioxide.
This is the reason why carbonated drinks gradually lose their carbon dioxide to the air through the polymer substance: the shelf life of a carbonated liquid contained in a PET bottle will not be more than a few weeks in terms suitability for sale or at most a small number of months (for example 4 to 6).
This is also the reason how oxygen in the air is able to penetrate the polymer material to come into contact with the liquid in the container, placing it at risk of oxidation accompanied by a deterioration in its properties: the shelf life of a bottle made from PET and filled with beer will not be more than a few weeks (for example 2 to 5 weeks) in terms of suitability for sale.
A known approach to this problem is to enhance the natural barrier effect of the polymer substances used to make the containers by lining the polymer wall with a layer of material which has a stronger barrier effect.
Accordingly, it has been proposed that synthetic materials in multiple layers be used for this purpose, such as those based on aliphatic polyamides and/or mixtures of different substances. The containers are then made using multi-layered preforms, in which the layer of material with a barrier effect is located between at least two layers of polymer material (for example PET). Beer bottles made in this manner will have a considerably longer shelf life (for example up to 12 months).
However, one major disadvantage of these multi-layered containers is that the layers will come unstuck from one another. In addition, making the preform, as well as making the container from the preform by blow-moulding or by stretching-blow-moulding, are quite complex processes and require certain precautions, which makes them expensive.
Another proposal is that polymer containers be treated by applying an external coating of an appropriate material such as those known as PVDC or thermo-setting resins. However, the gain in barrier effect achieved as a result is still quite low and the presence of the coating material leads to difficulties when it comes to recycling the basic polymer material.
Moreover, in all the known solutions mentioned above, the polymer material (for example PET) is left in contact with the liquid and does not offer any protection against the disadvantages incurred by this contact: possibility of certain constituents migrating from the polymer into the liquid, possibility of a chemical reaction between the polymer and liquid, acetaldehyde being transferred into the liquid, etc., all factors which are likely to give rise to organoleptic problems.
It has also been proposed that a layer of material with a barrier effect, for example hard carbon, be applied to a wall made from polymer, for example PET, using plasma (document U.S. Pat. No. 5,041,303).
Document EP 0 773 166 also mentions the possibility of forming such a layer of carbon on the internal face of the container wall.
A carbon layer deposited in this manner would, of course, remedy all the disadvantages listed above.
However, a relatively thick layer of hard carbon or diamond-like carbon (DLC) would be needed. The wall of a container made in this way would therefore have an internal layer of hard carbon DLC, which is quite rigid, and an external layer of polymer material such as PET, which is highly deformable. Due to their differing and incompatible mechanical properties, the two layers of polymer and hard carbon end up coming apart or unstuck.
Generally speaking, polymer containers with a barrier effect by implementation of one of the techniques mentioned above are not very common due to the complexity inherent in the different processes, low production rates and the high cost of manufacturing methods of this type.
SUMMARY OF THE INVENTION
The object of the invention is substantially to remedy simultaneously all the problems mentioned above, as encountered with known containers with an improved barrier effect, and to propose a container which will effectively protect its contents whilst being easy to manufacture on an industrial scale, using less complex means under acceptable economic conditions.
To this end, in a first aspect, the invention proposes a container such as a bottle or flask, heterogeneously made from a material with a barrier effect and a polymer material which, as proposed by the invention, is characterised in that the material producing the barrier effect consists of an amorphous carbon material with a polymer tendency, which is applied to a substrate of polymer material. The substrate is a blank of the container and already has the final shape of the container.
By amorphous carbon material with a polymer tendency is meant carbon containing not only CH and CH
2
bonds found in the hard carbon, but also CH
3
bonds which are absent in hard carbon (to get a rough idea, the proportions of CH
3
, CH
2
and CH are respectively 0, 40 and 60 in hard carbon and 25, 60 and 15 in amorphous carbon with a polymer tendency, whereas the proportions of the electronic states sp
3
, sp
2
and sp are respectively 68, 30 and 2 in hard carbon and 53, 45 and 2 in carbon of the polymer type).
Choosing an amorphous carbon material with a polymer tendency overcomes the problem caused by the rigidity of hard carbon or DLC: in practice, amorphous carbon materials with a polymer tendency have a substantially lower mechanical rigidity than that of hard carbon and the deformation capacity of a layer of such a material is comparable with that of a polymer such as PET: a container wall made as proposed by the invention using such an amorphous carbon material with a polymer tendency adhered to a substrate of polymer material such as PET will therefore be able to withstand deformation at normal levels without these two layers coming unstuck.
It is true that inherent in their physical and chemical structure, amorphous carbon materials with a polymer tendency have a lower molecular permeability coefficient than hard carbon which has been used to date and it was thought that any barrier effect they produced was less than perfect. This is one reason why they have not been considered until now and why hard carbon or DLC was used to provide layers with a barrier effect. Surprisingly, tests conducted with amorphous carbon materials with a polymer tendency have shown that the barrier effect obtained under certain operating conditions is generally sufficient in practice for use in the packaging of carbonated liquids or oxidizable liquids.
It would also be conceivable to use carbon-type nano-composites (or DLN)—i.e. composites with reciprocally interleaved dual networks, stabilised and random, one of which is a network of amorphous carbon with a polymer tendency (a-c:H, with up to 50% sp
3
bonds) whilst the other may be a network of silicon stabilised by oxygen (a-Si:o)—and nano-composites incorporating metal atoms.
It is of advantage if the coating of amorphous carbon material with a polymer tendency is of a thickness less than approximately 3000 Å (beyond that, too great a thickness imparts too high a mechanical rigidity to the carbonated coating, with the risk that it will rupture or become unstuck), preferably between 800 and 1500 Å.
It should be pointed out that, although still transparent at the above-mentioned thicknesses, amorphous carbon of the polymer type is amber in colour which helps to protect against ultraviolet rays (as a protection for beer in particular). It has been found that under certain operating conditions, the effectiveness of the barrier against ultra-violet afforded by this protection depends on the thickness of the coating and, interestingly, increases sharply with the intensity of ambient light (factor of about 8 in darkness but a f
Beldi Nasser
Boutroy Naïma
Chollet Patrick
Darras David
Oge Fabrice
Beck Shrive P.
Fletcher, III William Phillip
Sidel
LandOfFree
Container with a coating of barrier effect material, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Container with a coating of barrier effect material, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Container with a coating of barrier effect material, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3316806