GB2069927A - Horticultural sheet materials and articles made of such sheet materials - Google Patents

Abstract

Horticultural sheet materials in the form of planting bags, tubes or cover sheets are disclosed which are composed of two layers of sheet material. One layer is adapted to be innermost in use and is UV stabilised for horticultural use whilst the other layer is adapted to be outermost in use and has greater radiation reflection characteristics than the inner layer thereby decreasing the overall radiation absorbed by the sheet material.

Description

SPECIFICATION Horticultural sheet materials and articles made of such sheet materials This invention relates to horticultural sheet materials by which term there is intended to be meant continuous sheets of such material, sheet materials in the form of tubes, and sheet materials in the form of bags widely utilized for the purposes of containing earth or other suitable strata in which plants can be grown.

Horticultural sheet materials, in particular those formed into horticultural bags, are utilized in large quantities. In particular, horticultural bags are utilized by nurserymen for the propagation and saie of plants on a large scale.

It is generally accepted that horticultural bags, and in fact other sheet materials in tubular form or ordinary sheets thereof, must be resistant against the action of ultra-violet light and sunlight in general. In order to achieve such resistance to the action of the rays of the sun, a large proportion of carbon black is usually embodied in a suitable plastics material, such as polyethylene. This renders the horticultural bags or sheet material black and effectively resistant in the desired manner. Also such plastics materials are effectively strong and retain their strength over a satisfactory period of time.

However, the black colour does tend to promote absorption of solar energy which, in turn, increases the temperature of the bag and the adjacent soil appreciably. This can tend to damage the roots of a plant and also increases the rate of evaporation of moisture from the soil or other substrata.

It is accordingly the object of this invention to provide horticultural sheet material which may optionally be in the form of tubes or bags which have improved characteristics over those at present generally utilized.

In accordance with this invention there are provided horticultural sheet materials optionally in the form of tubes thereof or horticultural bags wherein the sheet material comprises two layers, one of which is opaque and UV stabilised for horticultural use and the other of which exhibits greater light and radiation reflection characteristics than the first mentioned layer.

Further features of the invention provide for the first mentioned layer to be a conventional black UV stabilised plastics material, for example, polyethylene material embodying carbon black, and for the second and operatively outer layer to be optionally of a different type of material but of a colour exhibiting greater radiation reflection characteristics than the first mentioned layer.

There are numerous sheet materials which can be made to operate in accordance with this invention and the manner of their manufacture may vary widely. Thus the invention applied to sheets of horticultural plastics materials wherein the two layers are co-extruded so as to become permanently secured together and wherein the coextruded layers may be of different types of plastics material. Thus, for example, the invention includes a preferred co-extruded plastics material wherein the first and operatively inner layer, is a carbon black UV stabilised polyethylene material of a type often used for horticultural purposes and the second and operatively outer layer is an ethylvinyl acetate co-polymer.

The latter material may conveniently have a green or any other suitable colour which exhibits suitable radiation reflective characteristics superior to that of the usual black polyethylene material.

Alternatively, the two layers of material could be formed by a lamination process of preformed sheet materials or alternatively, by a coating process, for example by spraying a layer onto the outside of a prefabricated sheet of material.

The invention is in no way confined to plastics materials but includes within its scope flexible rubber sheets, paper sheets and the like which could be bonded or otherwise associated with a second layer of an optionally different material of a different category. In all cases, however, the sheet material would be waterproof or rendered waterproof in order to serve the desired function.

The sheet material may be micro-perforated as provided by our co-pending patent application No. 77/6889 in order to achieve the advantages set forth in the specification thereof. These are primarily the ease of manufacture, and the retention of soil or other sub-strata therein without it being capable of being washed out of substantially larger holes were they provided.

However, where required, the plastics sheet materials in the form of bags may also be perforated with larger apertures in the conventional manner or such larger apertures may be provided in the alternative to such micro perforations.

Also, the horticultural sheet materials, whether in sheet, tubular or bag form, may carry an embossed design or pattern which may be primarily ornamentation but may also be primarily if not exclusively, structural insofar as it acts as reinforcing.

Whilst the invention includes within its scope fiat sheets of material which may be formed to be placed over a ground surface to prevent excessive evaporation therefrom in known manner, and also to tubular formations of sheet material, the largest application of the invention is envisaged to be in the field of horicultural bags.

Thus a horticultural bag will now be described with reference to the accompanying drawing which illustrates in perspective view, a partially opened bag.

In this embodiment of the invention a horticultural bag is made in the usual way by heat sealing across one end 1 thereof, a tubular formation of sheet material whereof the side regions 2 are folded inwardly in known manner to provide a bag 3. The plastics material could be micro-perforated as indicated by numeral 4 and could also, either in the alternative, or in addition to such micro-perforations, be provided with the conventional larger holes 5 at the lower region thereof.

In this particular embodiment of the invention the sheet has its inner surface 6 defined by an inner layer of plastics material which, in this case, is a substantially conventional black, carbon black impregnated polyethylene material. The outer layer 7 which is co-extruded with the inner layer is, on the other hand, of an ethyl-vinyl acetate co polymer and is of a bright green colour. This colour and material enhances the weatherability and resistance to the elements of the bag since it serves to reduce the heat and ultra-violet ray absorption by the bag as a result of its better reflection characteristics. Also, it greatly increases the aesthetic appearance of the horticultural bag.

Thus a horticultural bag and, of course, any other horticultural sheet materials in tubular or sheet form according to this invention have appreciably improved characteristics over the conventional monolayer black horticultural sheet materials or bags commonly available at the present time.

It has been found that the above described horticultural bags can be made at a cost comparable to that of simple mono-layer black bags as a result of the increased strength provided by the outer layer when made of the particular materials mentioned above.

There will, of course, be numerous other types of materials which can be utilized as mentioned above without departing from the scope of this invention which is aimed primarily at reflecting solar-radiation to some extent away from horticultural sheet materials or bags by the provision of an outer layer having better reflecting characteristics than the opaque inner layer.

Claims (14)

1. Horticultural sheet material comprising two layers, one of which is opaque and UV stabilised for horticultural use and the other of which exhibits greater light and radiation reflection characteristics than the first mentioned layer.

2. Horticultural sheet material as claimed in claim 1 in which the first mentioned layer is of a black, UV stabilised plastics material.

3. Horticultural sheet material as claimed in claim 2 in which the first mentioned layer is polyethylene material embodying carbon black.

4. Horticultural sheet material as claimed in any one of the preceding claims in which the second and operatively outer layer is of a colour exhibiting greater radiation reflection characteristics than the colour of the first mentioned layer.

5. Horticultural sheet material as claimed in any one of the preceding claims in which the second or outer layer is a suitably coloured plastics material.

6. Horticultural sheet material as claimed in any one of the preceding claims in which the second or outer layer is an ethyl-vinyl acetate copolymer.

7. Horticultural sheet material as claimed in any one of the preceding claims in which both layers are plastics material which are co-extruded to permanently bond them together.

8. Horticultural sheet material as claimed in any one of the preceding claims in which the sheet material is micro-perforated.

9. Horticultural sheet material as claimed in any one of the preceding claims in which a design or pattern is embossed into the sheet material.

10. Horticultural sheet material substantially as herein described with reference to the accompanying drawing.

11. Horticultural sheet material as claimed in any preceding claim which is waterproof or has been rendered waterproof.

12. Horticultural sheet material as claimed in any one of the preceding claims in which the sheet material is in the form of a tube.

13. A horticultural bag made from a.sheet material as claimed in any of claims 1 to 11.

14. A horticultural bag substantially as herein described with reference to the accompanying drawing.