CA1073831A

CA1073831A - Plastic container and production process

Info

Publication number: CA1073831A
Application number: CA269,319A
Authority: CA
Inventors: Luigi Borla; Guido Stampa
Original assignee: Lonza AG
Current assignee: Lonza AG
Priority date: 1976-01-09
Filing date: 1977-01-07
Publication date: 1980-03-18
Also published as: IT1066196B; FR2337671A1; IL50592A0; ES452715A1; JPS5286870A; LU76541A1; ATA680476A; FI763170A; BR7607829A; DK438876A; AT357054B; GB1517100A; NL7611095A; CH598064A5; BE850215A; ZA765822B; IE43554L; IL50592A; DE2642952A1; NO763323L

Abstract

ABSTRACT OF THE DISCLOSURE: A plastic container having a thick-walled outer jacket layer of a recycled plastic material and a thin-walled inner layer of a new plastic material, which is compatible with the recycled plastic material of the outer jacket layer.

Description

-10'~3~31 13/~CKGROUND Ol~ I`IITS INVI,NTION

1. Field Of This Invention _ This invention relates to a container made of plastic which consists of an outer thick-walled jacket layer and an inner thin-walled layer. This invention also involves a pro-cess for the production of such a container.

2. Prior Art - The importance of plastics in the packaging industry is becoming ever greater, and so is the problem of eliminating the waste plastics.
The idea of reusing synthetic wastes is not new. Thus, : empty waste containers are collected, washed and ground, and the plastic granulates so obtained, possibly with the addition of new material, are used again to form new plastic containers.
such containers, which are obtained from waste plastic (regen-erated), do not satisfy from a hygenic point of view, partic-ularly when used in the food industry, the requirements made on them.

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10'73831 An objee~ o~ tllis invcntion is to provi~G a plastic contailler W}liC}I uscs rc~cncrate~ (recycle~) waste pla~tic an~ which is hy~enically excellellt in performallce. Anotll~r object is to pro-vide a ~roc~ss for pro~ucing such plastic containers. Other ob-jects and a(lvantagcs of tllis inve1ltion are set out herein or are obvious herefrolll to one ordinarily skille~ in the art.

The objects an~ a~vantages of this invention are obvious to one ordinarily skilled in the art here~roln.

The plastic containers of this invention have an outer jacket ,layer made from a regenerated plastic material(s) and an'inner layer o~ a fresh plastic material(s) compatible with the regen-erated material(s) of the jacket layer. Only the stated inner and outer layers are nee~ed.

The-process of this invention for the production of the contain-ers of this lnvention includes grin~in~ up plastic eontainers designed for recycling, using the plastic powder (regenerate) so obtaine~ ~or the production of the outsi~e layer and coating the 2~ inside of the jacket layer with a ne~Y (freshj plastic material-which is compatible with the regenerated plastic material of the jacket layer. m e new plastic material is a polymer selected from the group consisting of poLyester, a copolymerizate of acrylonitrile-styrene, a graft copolymerizate of acrylonitrile-butadiene-styrene, a copolymerizate of acrylonitrile-acrylic ester, a graft polymerizate of acrylonitrile-acrylic ester on a copolymerizate of acrylonitrile-butadiene, and a graft polymerizate of acrylonitrile-acrylic ester on a copolymerizate of acrylonitrile-isoprene.
The coating of the inner layer onto the outer layer

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can be carried out simultaneously with the formation of the outer layer during the production of the entire container or else can be carried out prior or subsequent to the formation of the outer layer. Preferably the coating of the inner layer is achieved simultaneously with the formation of the outer layer during the prcduction of the entire container. For the pre-ferred embodiment, numerous processes are available, such as, co-extrusion-(coating-, laminating-) thermoforming, co-ex-trusion blowing, co-injection, co-injection blowing and com-binations thereof. According to the preferred embodiment, bothmaterials (the regenerated (recycled) plastic and the new plastic material) are shaped simultaneously and connected or bonded.
m e regenerated plastic material and the new plastic material must be compatible with one another. Compatibility in the sense of this invention, means, that the properties of the regenerated plastic material are not significantly impaired by the addition of the plastic material of the inner layer up to a mixing ratio of one to one.
The thickness ratio of the surface ~outer) layer and the inside (inner)layer may vary widely, preferably, however, a thickness ratio of the surface (outer) layer to the inside (inner) layer between 10 to 5 and 10 to 0.01 is selected.
All of the thermoplastics can be used for the outer layer. The plastic material for the inner layer is selected on the basis of compatibility with the plastic material used for the outer layer. The same plastic materlal may be used for both layers.
According to this invention it is possible to produce containers havlng an inner layer which consists of a plastic material that has barrier characteristics. Such plastic materials are, for example, polypropylene, which serves as a _~_ ` 1C~'~3~31 water vapor barrier, and acrylonitrile-containing plastics, like a graft polymerizate of acrylonitrile and methylacrylate on a copolymerizate of acrylonitrile/butadiene, which shows a barrier effect to CO2 and 2 Typical combinations of regenerated plastic material layer/new plastic material layer are:

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1~73831 polyvinyl chloride/polyvinyl chloride;
polyolefin/polypropylenc;
polyester/polyester;
copolymerizatc oE acrylonitrile-styrenc/graft copolymerizate of acrylonitrile-butadine-styrcne;
copolymerizate of acrylonitrile-methyl acrylate/graft copolymer-. izate of acrylonitrile-butadiene-styrene; and copolymerizate of acrylonitrile-methylacrylate/graft polymerizate of acrylonitrile-methyl acrylate on copolymerizate of acrylonit-rile-butadiene.

The regenerated plastic materi~l is produced by grinding, prefer-ably under water, of the recycled containers. The number of the cycles is not critical, as long as the demands made of the con-tainer are fulfilled. . :
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The containers according to this invention, for example, bottles, :
~ kettles, boxes, etc., always show as a result of their special construction a physiologically perfect inside layer and can be used for any packaging purposes.

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I)EI~ .SCRII'l10N ~l TIII~S JNV],NTION

In the drawing:
Figure 1 is a partially cut away side-elevational view of the plastic container of this invention;
Figure 2 is an enlarged cross-sectional view of the wall of the container of Figure l; and Figure 3 is another enlarged cross-sectional view of the wall of the container of Figure 1.

In Figure 1, plastic bottle 11, consists of an outer thick-walled layer 13 made from regenerated plastic obtained by recycling plas-tic material and of an inner thin-walled layer 12 made from new plastic material.

Example 1 A thermoformed preform made from a graft polymerizate of acrylon-itrile with the trademark designation BAREX 210 was fed to the core of an injection-blow molding machine. A copolymerizate con-sisting of about 75 percent by weight of acrylonitrile and about 25 percent by weight of methylacrylate was injected thereon and was blown to a container at a temperature between 140 and 170C
2~ whereby a biaxial orientation developed. The weight ratio be- ;
tween the inner BAREX 210 layer and the outer acrylonitrile-meth-ylacrylate copolymerizate layer was 1 to 20. The container was transparent, hard and impact resistant. The container was ground into a granulate after using and recycling. The regenerate so obtained was used again as a molding material for the outside surface (jacket), as described above. The thermoformed perform consisted of fresh BAREX 210. After ten cycles, the material of the outside layer consisted of about 64.5 percent by weight of acrylonitrilc-mctllylacryl~ltc col~olymcrizate and a~out 35.5 pcr-cent by wei~ht of BARE~ 210. This mixture, vis-a-vis the origin-al acrylonitrile-methylacrylate copolymerizate, showed an in-crease of tensile impact strength of about 90 percent, with the elasticity module remaining about the same.

Example 2 As in Example 1, a preform, this time from a graft polymerizate of acrylonitrile-styrene on butadiene-acrylonitrilc, was fed to the core of an injection-blow molding machine and the outside layer was formed from a copolymerizate of acrylonitrile-styrene.
~ere also the container, after use and recycling, was ground and used again for the outside surface. The inside layer was made from fresh graft copolymerizate of acrylonitrile-styrene.

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Example 3 As in Example 1, containers were formed where both the inside layer as well as the outside layer consisted of polyethylene terephthalate.

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Example 4 A composite sheet, which was produced by co-extrusion, lamin-ation or coating and which consisted of two layers of a graft polymerizate of acrylonitrile-methacrylate on a copolymerizate of acrylonitrile-butadiene, ha~ing the tradename BAREX 210, was thermoformed into a container. The regenerate, obtained by grinding of the used and recycled container, was used for the - production of the outside layer of a new container. The inside layer was formed from fresh BAREX 210. After about ten such ~ 073~331 rccyclin~ stcps, thc ch~racteristics of thc outsi~le layer of the container were still about the same as in the original out-side layer.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A plastic container comprising a crushable outer thick-walled jacket layer and a crushable inner thin-walled layer attached thereto, said outer jacket layer of recycled plastic container material and said inner layer of new, physiologically perfect plastic material compatible with the plastic material of said outer jacket layer, said inner layer comprising a polymer selected of the group consisting of polyester, copolymerizate of acrylonitrile-styrene, graft copolymerizate of acrylonitrile-butadiene-styrene, copolymerizate of acrylonitrile-acrylic ester, graft polymerizate of acrylonitrile-acrylic ester on co-polymerizate of acrylonitrile-butadiene, and graft poly-merizate of acrylonitrile-acrylic ester on copolymerizate of acrylonitrile-isoprene, whereby both layers of the container may be ground up together and used to form a thick walled jacket layer of another plastic container.