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Pressurized containers made of polycarbonate/polyester blends

IP.com Disclosure Number: IPCOM000021303D
Publication Date: 2004-Jan-13
Document File: 2 page(s) / 28K

Publishing Venue

The IP.com Prior Art Database

Abstract

Containers for beverages and beer are often made of metal and in some cases also of glass. Plastic containers will have the benefit of lower weight. Plastic pressurized containers as vessels for carbonized beverages or beer kegs should fulfill several requirements. The pressure in containers can be as high as 7 bars. During transport and practical use the temperature can be up to 75 C. The containers, both filled and unfilled, should not break if dropped from a height up to about 1 meter and if dropped from higher height the containers might break, but in a ductile way (not in sharp pieces). The containers should be resistant, i.e. no breakage, upon burst pressures up to 20 bars. Also the dimension of the containers should not change upon storage under pressure and at higher temperatures. Furthermore the containers should be resistant against a lot of household chemicals as white spirit, ammonia, motor oil, cleaning agents, soaps, acetic acid etc. If the containers are used for beer, the containers should be of course resistant against beer. Furthermore UV-stability is required. The containers might contain an inner bag, e.g. Aluminum based bags that contain the beer, and takes care that no oxygen can migrate into the beer. So, a container of plastic should fulfill the following requirements: high ductility, good creep resistance, resistance against several chemicals. This combination of requirements is not easy to fulfill. Polymer materials as polycarbonate (and a lot of other amorphous polymer(blends)) will have good ductility and creep but lack chemical resistance. Most semi-crystalline polymers will have good chemical resistance, but lack or creep resistance or are not ductile enough. Polyacetals (POM) will have good chemical resistance and in view of the high crystallization degree also a good creep resistance, but it fails in ductile behavior. So, there is a need for pressurized containers made out of a polymeric material that has good ductility and still has good creep and chemical resistance.

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Title: Pressurized containers made of polycarbonate/polyester blends

Date: January 9th, 2004

Introduction:

Containers for beverages and beer are often made of metal and in some cases also of glass. Plastic containers will have the benefit of lower weight.

Plastic pressurized containers as vessels for carbonized beverages or beer kegs should fulfill several requirements. The pressure in containers can be as high as 7 bars. During transport and practical use the temperature can be up to 75 C. The containers, both filled and unfilled, should not break if dropped from a height up to about 1 meter and if dropped from higher height the containers might break, but in a ductile way (not in sharp pieces). The containers should be resistant, i.e. no breakage, upon burst pressures up to 20 bars. Also the dimension of the containers should not change upon storage under pressure and at higher temperatures. Furthermore the containers should be resistant against a lot of household chemicals as white spirit, ammonia, motor oil, cleaning agents, soaps, acetic acid etc.

If the containers are used for beer, the containers should be of course resistant against beer. Furthermore UV-stability is required.

The containers might contain an inner bag, e.g. Aluminum based bags that contain the beer, and takes care that no oxygen can migrate into the beer.

So, a container of plastic should fulfill the following requirements: high ductility, good creep resistance, resistance against several chemicals.

This combination of requirements is not easy to fulfill. Polymer materials as polycarbonate (and a lot of other amorphous polymer(blends)) will have good ductility and creep but lack chemical resistance. Most semi-crystalline polymers will have good chemical resistance, but lack or creep resistance or are not ductile enough. Polyacetals (POM) will have good chemical resistance and in view of the high crystallization degree also a good creep resistance, but it fails in ductile behavior. So, there is a need for pressurized containers made out of a polymeric material that has good ductility and still has good creep and chemical resistance.

New material proposal for pressurized containers:

It is now proposed that Polycarbonate/polyester blends are suitable materials for making pressurized containers and that the requirements described above can be met.

It is known that Polycarbonate/polyester blends, impact modified with an impact modifier – for instance with a so-called core-shell rubber (MBS rubber, e.g. the MBS- rubbers from Rohm and Haes) or High rubber graft ABS impact modifiers (e.g. ABS-333 from GE Plastics), have a very good ductility. Surprisingly these materials also showed good creep resistance and chemical resistance if the polycarbonate /polyester ratio is high enough. Especially PET based materials showed good results.

Results:

Impact test results of containers, m...