GB2469014A

GB2469014A - Biodegradable composition

Info

Publication number: GB2469014A
Application number: GB0821754A
Authority: GB
Inventors: Adrianne Jacqueline Jones
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-11-28
Filing date: 2008-11-28
Publication date: 2010-10-06
Also published as: GB0821754D0

Abstract

A biodegradable composition comprises raw fibres (e.g. flax, hemp, grass, straw, coconut or banana skins) which after being de-baled and chopped are mixed with a biodegradable resin (especially cashew nut shell liquid, CNSL) that has been produced in a liquid, powdered or granular form. The composition may include a slow-release fertilizer and/or a weed suppressing preparation.

Description

Composition The present invention relates to a fibrous composition and, in particular, to a degradable fibrous composition and preferably one which is fully biodegradable.

The non-biodegradability of a wide range of product in current use constitutes one of the serious problems contributing to environmental pollution. Land pollution is the degradation of earth's land surfaces often caused by human activities and their misuse of land resources. Haphazard disposal of urban and industrial wastes are a few factors Non-biodegradable materials that would be not only useful but also necessary to replace on a large scale, are principally polypropylene (PP), polystyrene (PS), polyethylene (PE) and polyethylene terephthalate (PET) , in so far as they are materials that are bound to remain intact in landfill sites for hundreds of years.

Products such as compositions, plant pots, clay pigeons, plant seedling protection and the like are all manufactured from material with limited or no biodegradability and as such contribute to land pollution. Non-biodegradable plastics and other non-sustainable resources are typically used.

Such products can also be hazardous to the well being and health of natural wildlife.

The use of biodegradable materials, especially for single-serve and disposable containers, packaging and articles conventionally produced using synthetic resins has consequently become a primary need for safeguarding the environment.

In addition, a problem with manufacturing products made using natural biodegradable materials is that they are normally unsuitable for use in injection moulding techniques. As a result it is impossible to manufacture these products or it is prohibitively expensive as cost efficient manufacturing processes cannot be used.

It is an object of the present invention to overcome one or more of the aforementioned disadvantages.

According to a first aspect of the present invention there is provided a biodegradable composition comprising a natural fibre matrix and a binding agent, wherein the binding agent comprises a resin.

The present invention is a biodegradable material, usable for the production of products.

More in particular, the composition may be used to produce a biodegradable material suitable for the production of single-serve articles, such as for example disposable containers and packaging, medical articles, toys, dishes, etc., presenting high qualities of structural resistance and at the same time being totally biodegradable and, hence, having little or no environmental impact.

The biodegradable material according to the invention constitutes a valid and advantageous alternative, in economic terms, to costly biodegradable synthetic polymers.

The term "natural fibre" used herein and in the claims should be understood as encompassing fibre derived from plants or animals.

The term "biodegradable" used herein and in the claims should be understood as encompassing capable of being broken down into innocuous products by the action of living things, such as micro-organism.

The term "natural resin" used herein and in the claims should be understood as encompassing any naturally occurring resin, such as those derived from plants, seeds etc. Preferably, the resin is derived from cashew nut shell liquid (CNSL). The CNSL may be pure or a natural residue.

The natural fibre may be derived from flax, hemp, coconut, banana skin, mineralised straw, treated grass waste and/or other natural fibres.

The fibre matrix preferably comprises a plurality of fibres having a diameter of between 0.5 -50 mm in length.

The composition preferably comprises the following: a) 40 -80% fibre; b) 20 60% resin; and c) 0 -5% cross linking agent.

d) Optionally, 0 -10% fertiliser, UV stabiliser and/or biocide.

The present invention provides a composition for manufacturing products designed to degrade into a loose fibrous state over a predetermined time span. It will be appreciated that because the core of the products will comprise a biodegradable fibre, once the exterior coating of resin starts to degrade, the fibre matrix is exposed to environmental conditions and therefore also starts to degrade. Unlike conventional photo-degradable products, which tend to disintegrate into large pieces, the fibrous nature of the composition of the present invention means that ultimately it will decompose back into a loose fibrous state that will absorb moisture and form a beneficial mulch around the base of the plant etc., unlike the large pieces of conventional photo-degradable shelters, which serve no additional purpose and tend to litter the planting area and be carried away by the wind to form a nuisance elsewhere. The mulch will then degrade naturally.

For example, conventional compositions are typically cast from photo-degradable plastics materials that are designed to degrade within 5 to 7 years. It has been found, however, that such supports do not fully degrade within the time frame but disintegrate gradually between 10 to 15 years into separate pieces so that the unsightly remains of the supports can still be present around the tree or shrub for some considerable time. As much tree and shrub planting is carried out for landscaping purposes, having disintegrating supports still visible some years after planting is undesirable and in order to remedy the situation it is common practice to remove the supports after a sufficient period of time has elapsed to enable the trees or shrubs have become established. However, apart from the effort involved, an additional problem is created because the remains of the compositions removed from such sites have to be disposed of. Typically, they end up as refuse in landfill sites where they are buried. However, as they are only photo-degradable, once buried degradation will take longer and they therefore can become an environmental nuisance.

The degradable resin is preferably also fully biodegradable but can be subject to other forms of degradation in addition to or instead of biodegradation.

There are three main routes to degradation, as follows.

1. Biodegradation, wherein the material is broken down by the action of micro-organisms, such as bacteria and yeasts. Such degradation is slow in the atmosphere but more active when the material is in direct contact with soil.

2. Photo-degradation, as mentioned above, wherein ultra-violet light acts at a molecular level to breakdown the molecules of the material into smaller molecules, thus causing the material to disintegrate.

3. Moisture degradation, wherein a continual softening and hardening of a material by the action of water absorption, either above or below ground level, causes the material to disintegrate.

Preferably, the degradable resin comprises an exterior coating over the side surfaces of the fibres of the fibre matrix. The resin stiffens and binds the fibres and also slows its own biodegradation, which may otherwise occur too quickly. Hence, the quantity of resin used is a factor to be taken into account when determining a required life for the product.

Such time spans can be substantially predetermined by choosing an appropriate percentage of resin and the thickness of the coating.

It is expected that in most cases, moulded products will have an overall thickness that is in the range 1 mm to [please advise] mm but that in some cases could be as much as [please advise] mm, of which up to 2 mm on each side would comprise the thickness of the outer resin coating.

It will be appreciated that ideally, as soon as the resin coating has degraded to the extent that the fibre matrix has become substantially exposed to environmental conditions, the shelter will thereafter disintegrate very quickly into a loose fibrous state that can form a mulch around the base of the plant, as indicated above. The fibres, then being in contact with the soil, will themselves commence a more rapid biodegradation.

The fibre matrix may be manufactured from many different types of fibrous material but preferably is substantially made from flax fibres. Other biodegradable materials that could be use instead or in addition are hemp, mineralized straw and appropriately treated grass waste.

The life-span of products may be enhanced by incorporating a UV-stabilizer.

All of these resins biodegrade completely into nontoxic residues.

Advantageously, the composition can be impregnated with a slow-release fertilizer and/or a weed suppressing preparation. These impregnations are preferably designed to become active after biodegradation of the shelter.

Hence, even after the composition has degraded it may still have a useful purpose for the formerly enclosed plant.

Preferably the composition further comprises a cross-linking agent for forming a more solid structure/product.

Preferably also, the fibre matrix is impregnated with a slow-release fertilizer and/or a weed suppressing preparation. These impregnations may be in a liquid, powdered or granular form and mixed with the fibres or scattered between the fibre layers during manufacture.

According to a second aspect of the present invention there is provided a method of manufacturing a biodegradable product comprising the steps of: heating a composition as described hereinabove to a temperature sufficient to melt the resin; shaping the composition into the desired shape, for the product and allowing the composition to cool.

According to a third aspect of the present invention there is provided a method of manufacturing a composition for injection moulding.

The present invention will now be described, by way of example, with reference to the following example, in which:-The composition is made from raw flax fibres which after being de-baled are mixed with one of the degradable resin that has been produced in a liquid, powdered or granular form. It is expected that typically the mixture will comprise fibres, resin and cross linking agent but the exact quantities can be varied in order that the finished mat is likely to degrade within a desired time span. If any further additive are to be included within the product, such as a slow-release fertilizer this is also preferably incorporated into the mixture at this stage in a liquid, granular or powdered form.

The natural fibres are chopped to 50mm diameter to 0.5mm long depending on the required strength of the end product, the longer the fibre the stronger the mechanical strength of the final product.

The CSNL resin is heated which time a the cross linking agent is added.

The fibres are fed into a large mixture where the CNSL mixture is added slowly to the fibres.

The fibre/resin mixture is then fed into a pelletising machine where it is passed through holes having the requisite diameter where the size of the pellet is determined.

The pellets are fed into the Injection Moulding machine and fed via a large screw into the Injection tool.

Whilst the pellets are passing through the screw section of the machine they will be heated up and the CNSL resin turned into a liquid. As the mixture enters the tool and fills the moulding cavity it will cross link and harden the mixture to form the shape that is inside the tool. The composition will then be allowed to cool within the tool.

The tool will then open and the part inside will be ejected.

Claims

CLAIMS1. A biodegradable composition comprising a natural fibre matrix and a binding agent, wherein the binding agent comprises a resin.
2. A composition as claimed in claim 1 comprising: a) 40 -80% chopped fibre; b) 20 -60% resin; and c) 0 -5% cross linking agent.d) Optionally, 0 -10% fertiliser, UV stabiliser and/or biocide.
3. A composition as claimed in any one of Claims I or 2, wherein the degradable resin comprises an exterior coating over each of the side surfaces of the fibre matrix.
4. A composition as claimed in any of Claims I to 3, wherein the fibres in are cross-linked.
5. A composition as claimed in any one of Claims I to 4, wherein the matrix is substantially made from at least one of a mixture of flax fibres from mineralized straw and treated grass waste.
6. A composition as claimed in any one of the previous Claims wherein the resin substantially comprises cashew nut shell liquid resin.8. A composition as claimed in any one of the Claims wherein the fibre matrix is impregnated with a slow-release fertilizer and/or weed suppressing preparation.9. The method of making a composition comprising the steps of manufacturing either matrix or biodegradable fibres; coating the fibres with a degradable resin; and injection moulding or extruded the mixture to form a product.10. The method as claimed in Claim 6 comprising impregnating the fibre matrix with slow-release fertilizer and/or a weed suppressing preparation.