FAIR-CT96-3255 Biodegradable packaging film materials for high barrier applications

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Biopolymers/Gums : FAIR Area 2.1 - Chemical and Physical Processes : Packaging

	Proposal No:	FAIR-CT96-3255
	Date Prepared:	September 1999
	Source:	Progress report September 1998

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Progress report September 1998

Summary

Introduction The overall aim of the project is to provide biodegradable polymer films, based on renewable resources, for medium and for high barrier flexible packaging applications. These are to be, in comparison to the conventional polymers presently used:

• competitive in terms of functionality (i.e. that they fulfil the technical and legislative requirements for application in the selected fields)
• comparable in integral costs for materials, processing, use and waste management
• compatible with anaerobic and aerobic biological waste management strategies
• allow improvements in terms of environmental impacts over the whole product life cycle

The project aims to supply at least two different types of biodegradable packaging films, namely medium barrier films and high barrier films. In both cases conventional, non-biodegradable films, will serve as a reference in terms of technical performance. The packed products envisaged for this project are:

• hygiene articles (for application of the medium barrier films)
• herbs/spices and cereals (for application of the high barrier films)

The waste management schemes foreseen for these products after their use are:

• conventional aerobic treatment together with the municipal bio-waste (composting) for the food packaging
• combined anaerobic / aerobic treatment in a communal waste water treatment plant, for the wrappings of hygiene articles

The environmental impacts of the materials to be developed in the course of this project will be compared to those of their reference counterparts over their whole life cycle. Focus will be given to globally relevant environmental impact parameters, especially in terms of the relative impact of use of non-renewable and renewable energy dependent resources and their contribution to global warming.

Activities Softeners with low migration properties were screened. Appropriate formulations of lacquers and adhesives were composed and tested. These included lacquers on pure cellophane and adhesives in cellophane laminates together with other biodegradable thermoplastic materials. Vacuum coating was carried out with transparent and metallic barrier materials on cellophane material. Methods for cellophane film pre-treatment relating to humidity inside the film were optimised. Basic investigations on material deposition, such as film thickness, as a function of web speed and the influence of a film pre-treatment were investigated.

Lamination of cellophane to several other biodegradable thermoplastic films with and without new biodegradable adhesives was investigated. Lacquer coating of virgin and vapour deposited cellophane films was done so far on handsheet samples. Special attention has to be paid to the amount of wet lacquer used, in order to obtain the most suitable dry lacquer weight. Machine parameters were harmonised according to the substrate.

All activities carried out in all tasks were accompanied by a detailed analysis evaluating every step in terms of their contribution to the objectives. In particular, mechanical and extraction experiments were carried out to characterise the softened cellophane films. Therrnomechanical behaviour and water vapour transmission of each sample was checked in order to optimise product properties and process parameters. Biodegradation measurements of starting materials was carried out in advance of other experiments. Biodegradation measurements of laminates and lacquered cellophane reel material will be carried out as samples become available.

Progress The identified plasticisers are in concert with the biodegradability requirements. All tested plasticisers can be incorporated in sufficient amounts into the cellulose and give a sufficient plasticising effect. Medium technical scale film production, on the basis of these plasticisers could not so far be performed; mainly due to delays in setting up the equipment, but also due to the need to perform preliminary. However, no problems are expected in achieving this.

Vacuum coating for additional barrier performance is generally possible, but difficulties arise due to out-gassing of humidity from the films. This problem, however, is mostly specific to 1-chamber- laboratory coating equipment. At the larger scale, 2-chamber systems are usual. These should allow coating of paper on transfer to a larger scale operation. Plasma pre-treatment of the films is not advisable, due to additional out gassing of plasticisers. As adhesive properties are sufficient without pre-treatment, this does not raise severe problems.

Biodegradable adhesives and lacquers can be produced in the quantities required for production of reel materials. They show an overall fair performance in adhesive and heat sealing properties. However, these still have to be optimised for larger scale operation.

Overall, samples have been obtained under laboratory conditions that are close to the requirements of the end users in terms of water vapour barriers, heat sealability and other, mainly mechanical properties. The scale up procedures suffers from time delays, originating from experimental difficulties, but not from principal problems.

Progress Four softeners were identified for further trials in cellophane reel materials. A set of 4 lacquers and 2 adhesives is available for further processing on reel materials. A standard operating procedure for vacuum coating of cellophane was established in order to obtain a standard quality for further lacquering and laminating steps. Four biodegradable polymer materials were identified for their use as top-coating films. Their potential in combination with the previous tested adhesives and vacuum coated cellophane films was shown to be suitable in handsheet samples.