"BIODEGRADABLE PLASTIC MATERIAL"

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The present invention refers to a biodegradable plastic material, which combines the properties of biodegradability with a resilience comparable to that of common synthetic plastic materials .

Plastic materials have unique properties and are used for a variety of applications in all fields. In addition to that, there are cleanliness requirements which often impose to use plastic materials, for disposable goods (for example syringes) or as wrappings. This use creates big disposal problems. As a matter of fact, although the resistance of plastic materials to the majority of chemical and atmospheric agents causes them not to be defined as polluting materials, from this very character- istic an accumulation thereof in the environment derives, causing serious disposal problems.

In recent times, recycling processes of the main plastic materials have been started, feeding the charge of fresh polymer with waste material of the same chemical composition. Such proc- esses, however, have the major drawback that the waste materials can be introduced in the charge only up to a percentage (full recycling is not normally possible) and such percentage is typically below 50% (often around 30%) . Hence such solution, despite being conceptually attractive and although it partly reduces disposal problems, is not the final solution.

Attempts have been made to create hydrosoluble or photo- lythic plastic materials. Such solution, in any case, despite being effective in limiting the mass of "visible" plastic material put aside, in fact causes such material to become pollut- ing, since it causes non-natural materials to seep into the water-bearing layers and the soil.

A remarkable improvement has been made possible by plastic materials made of corn starch (for example the so-called Mater- bi) , which are compostable and biodegradable, with no release of agents which may be harmful in any way. However, such material is excessively rigid and hence fragile. In order to be able to be used without it falling apart, very small thicknesses must be

used, which, however, may lead to rips in the product (consider, for example, the bags for sorting the organic part of waste) .

The Applicant has recently suggested the use of recyclable plastifiers which, combined with the plastic material of natural origin, allowed to obtain the same elastic and plastic properties of ordinary synthetic materials, obtaining biodegradability by composting a non-negligible portion of the material and recycling the other portion, so as to remarkably reduce the percentage of material remaining in the environment. However, this so- lution, too, which in any case is so far the most sustainable from an environmental point of view, nevertheless still releases non-biodegradable agents, which it is necessary to recycle with some technical difficulty, such as the separation from the composted fraction of the plastifier. In order to solve the above reported problems, the present invention suggests a plastic material consisting of a biodegradable thermoplastic polymer, characterised in that materials of vegetable origin are used as plastifier.

The present invention concerns a plastic material, having properties not below, or even above, those of any synthetic thermoplastic material, manufactured starting from a biodegradable thermoplastic polymer. As a biodegradable thermoplastic polymer plastic materials can be used based on corn starch (for example the so-called Mater Bi ^® ) , based on citric acid esthers (for example the so-called Citrofol ^® ) , also obtained in wine fermenting processes, based on soy oil, the so-called bio-PVC (a PVC which contains additions of a polymer which makes it biodegradable) , vegetable fibres.

Other materials which can be employed are polymers based on caprolactone, polylactic acid, aromatic-aliphatic co-polymers

(for example the one sold under the trade name of Ecoflex ^® ) , a composite of polylactic acid and aromatic-aliphatic co-polymers

(such as the one sold under the trade name of Ecovio ^® ) .

All the above listed materials have the feature of being able to be biodegraded, regardless of the fact that they are of natural, synthetic or mixed origin.

In order to be able to have the elastic, plastic and duc-

tile properties typical of a plastic material, it is necessary to add a plastifier. According to the present invention, vegetable substances are used, in particular vegetable oils, such as rapeseed oil or soybean oil or citric acid esthers (such as Citrofol ^® ) .

To the above-said plastic material further vegetable and natural additives can be added, to model the mechanical, physical and aesthetic properties thereof, such as, for example, rapeseed seeds, soybean seeds, grapefruit seeds, sunflower seeds, alfalfa, clover, wheat chaff, rice chaff, cork.

Natural antibacterials can also be added. Particularly useful is chitosan, obtained, for example, from crab or shrimp shells .

Finally, natural fragrances and expanders for food can be envisaged.

The present invention hence allows to obtain a plastic material which displays the same mechanical properties as synthetic ones, which is, however, fully biodegradable by composting, originating from perfectly renewable sources. The plastic material according to the present invention, manufactured according to conventional polymerisation techniques and possibly formed in a composite product in a known manner, can have the most diverse uses. In particular, it can be used in the field of footwear, for the manufacture of apparatuses, boxes, plugs, key-holders, car parts, small household tools, apparatuses for medical use, etcetera.