GB2437238A

GB2437238A - Agricultural cover with hydrophilic properties

Info

Publication number: GB2437238A
Application number: GB0608020A
Authority: GB
Inventors: George Murray Baxter; David John Avril
Original assignee: Don and Low Ltd
Current assignee: Don and Low Ltd
Priority date: 2006-04-22
Filing date: 2006-04-22
Publication date: 2007-10-24
Also published as: GB0608020D0

Abstract

An agricultural cover 1 comprising at least one sheet form member 2, the sheet form member comprising hydrophilic means. The sheet is preferably liquid and moisture vapour permeable, and allows passage of sunlight. The sheet may be a fabric, a non woven material such as a spunbond material, or be made of filaments, microfibres, threads or tapes. Alternatively the sheet may be formed from polymers such as polypropylene or polyethylene. The hydrophilic means can be an additive in the form of a melt, and may be a surfactant, a monostearate, or hydroxylamine. Also claimed is a method of making such a cover; and a liquid permeable agricultural cover having means for dispersing liquid droplets which collect on an upper surface of the cover.

Description

SHEETING

FIELD OF INVENTION

The present invention generally relates to sheeting or fabrics. In particular, though not exclusively, the invention relates to an agricultural cover, crop protection cover, horticultural cover, or plant cover.

The invention also relates to a geotextile or to a construction fabric.

BACKGROUND TO INVENTION

Ground covers, such as agricultural crop protection covers, are placed over plants and/or seedlings to provide a barrier to help prevent damage from insects, birds, wind or the like. It is desirable for such a cover to have good light and water transmission properties to prevent plant growth from being inhibited through lack of light or water. Polyethylene plastic sheets can be used as crop covers; however, these can cause the plants underneath to become scorched in sunny conditions and can prevent rain passing through to the plants underneath.

Crop covers made from nonwoven spunbond or spunbonded fabrics have an advantage that the porosity thereof allows rain and water vapour to pass through relatively easily, and the plants underneath tend not to become scorched because they are somewhat shaded. Such covers also act as an effective fleece to form an insulating layer over the plants which helps protect them from frost damage. The cover can also help prevent heat loss from the ground underneath. In short, such covers effectively form a micro-climate environment beneath the cover.

However, spunbond crop covers can suffer damage such as tearing from abrasion on stones or the like, and from damage caused by birds landing on the cover, attempting to access the plants underneath or pecking off insects.

Damage can also occur when the cover is stretched too tightly. It is therefore important to seek to limit damage of a cover to a minimum.

Beneficially such a cover may withstand more than one standard crop growing season. This means that after one season on a field protecting a crop, the cover may be rolled up and stored away to be used in a further growing season, e.g. the following year. This can be an advantage over previous covers, which typically have had a lifespan of one season.

Agricultural fields are often 15 metres or greater

in width. Typical spunbond fabrics are produced in widths of between 2.4 metres to 5 metres, and hence several pieces are usually joined together along the long edges thereof to form a typical crop cover.

Conventionally, joins are made by bonding the fabric pieces with a continuous line or lines of glue applied to long edges of the fabric. It is difficult to monitor the glue line to ensure such remains continuous -which sometimes results in unglued portions of fabric. Also, it has been observed that when damage, for example, tearing occurs such happens to a larger extent at the seams rather than elsewhere on the cover even when a good glue line has been applied. Even though it is believed that the bond strength at the bond seam is relatively high, the seam tear strength of the fabric adjacent to the seam is often lower than that of the fabric itself.

This is rationalised in that fabrics having a high tear strength tend to have loosely adhered fibres of fabric, that is, the fabric does not tear easily, compared with a fabric in which the fibres are more fixedly bonded together, such as at bond points of two pieces of fabric, allowing easier tearing of fabric at or adjacent those points because the fibres do not move or hlgiveT as freely as weakly bonded or loosely adhered fibres.

GB 2 370 807 A by the present Applicant, discloses a sheeting which is an agricultural crop protection cover, ground cover, geotextile or construction fabric, the sheeting comprising at least first and second parts, each part comprising a sheet form member, each part having first and second opposing surfaces, wherein portions of the first and second parts forming at least part of a first surface of the sheeting, and further portions of the second surfaces of the first and second parts forming at least part of a second surface of the sheeting, wherein further the first seam depends from the second surface of the sheeting. Desirably, portions of the first or second surfaces of the first and second parts S provide first and second outer surfaces of the first seam and neither firs nor second outer surfaces of the first seam are joined with the second surface of the sheeting, surface to surface. The content of GB 2 370 807 A is incorporated herein by reference.

The use of agricultural covers or so-called "agricultural fleeces" or "films" as a means of improved crop yield has been known for a number of years, and is known in the art, e.g. from GB 2 370 807 A. These fleeces protect crops from frost, allow an earlier harvest, and in addition, create a micro-climate which is normally about two degrees centigrade (2 C) higher than ambient. This in turn leads to an improvement in crop yields. Additionally, such crop covers prevent infestation by insects.

These covers are typically made from polyethylene (film) or polypropylene (nonwoven fleece) . Requirements for a crop cover for these applications include stability to sunlight, good light transmission properties, good tensile and tear strength properties and permeability to liquids. The Applicant has found that a disadvantage of a polypropylene fleece is that it is hydrophobic in nature.

Rain water, dew and liquid crop sprays tend to lie on the surface of the fleece in poois. Whilst the liquid will eventually penetrate the cover, the distribution of liquid on the crop is very uneven, resulting in an irregular distribution of rain water or spray chemical.

This means that the cover has to be removed at regular intervals to allow efficient crop spraying or irrigation.

It is an object of at least one embodiment of at least aspect of the present invention to obviate and/or at least mitigate one or more problems or disadvantages

in the prior art.

It is an object of at least one embodiment of at least one aspect of the present invention to provide an advantage over the prior art in that water such as rain water is more easily transmitted through the sheeting, fabric or cover, preferably in a substantially uniform manner access the sheeting, fabric or cover, thereby acting to moisten or keep moist the soil therebelow.

This advantage acts to eliminate the cumbersome and labour intensive practice of having to remove the sheeting, fabric or cover thereafter mechanically irrigating the crop, and then relaying the sheeting, fabric or cover.

SURY OF INVENTION

One or more objects of the present invention are sought to be addressed by providing the general solution of an agricultural or horticultural cover comprising a sheet form member having hydrophilic properties. This allows the crop to be uniformly treated or irrigated without having to remove the cover.

According to a first aspect of the present invention there is provided an agricultural cover, horticultural cover, crop cover or plant or seedling cover comprising at least one sheet form member, the sheet form member comprising hydrophilic means.

It is believed that the use of the invention will extend the effective growing season, and may generally increase the yield of a wide range of crops. Prior art crop covers suffer from the major disadvantage that such had to be lifted to irrigate and spray the crop evenly.

This is a very labour intensive operation carried out at regular intervals during the growing season. With a cover according to the invention, lifting is not necessary. Crops may be sprayed with, for example, water, liquid feed, herbicides and insecticides or the like, as required, without the need for removing covers.

A further advantage of a cover according to the invention, in allowing spraying to occur in situ is that the possibility of ingress of insects when the cover is removed, is reduced.

The Applicant has observed that with provision of hydrophilic means or hydrophilic treatment, a rain drop or droplet, upon impact with the cover, disperses through the sheet form member. The dispersed droplet then passes through the cover and forms a mist of finer droplets, which gives more even coverage over the surface of the soil or ground.

The sheet form member is most preferably liquid permeable.

The sheet form member is most preferably gas/air permeable.

The sheet form member is preferably moisture vapour permeable.

The sheet form member is preferably capable of allowing passage of light, e.g. daylight.

The/each sheet form member may comprise a fabric.

The/each sheet form member may comprise a plurality of filaments, microfilaments, microfibres, threads, or tapes.

In a preferred implementation the sheet form member comprises a nonwoven material, such as a spunbond material. In such case the nonwoven material may comprise a plurality of filaments or microfilaments.

The cover may comprise at least first and second parts, each part comprising a sheet form member, each part having first and second opposing surfaces, wherein portions of the first surfaces of the first and second parts are joined at or near respective edges to form a first ultrasonically bonded seam further portions of the first surfaces of the first and second parts forming at least part of a first surface of the sheeting, and further portions of the second surfaces of the first and second parts forming at least part of a second surface of the sheeting, wherein further the first seam depends from the second surface of the sheeting.

Portions of the first or second surfaces of the first and second parts provide first and second outer surfaces of the first seam and neither first nor second outer surfaces of the first seam are joined with the second surface of the sheeting, surface to surface.

The sheet form member may be substantially formed from a polymeric material such as a thermoplastic polymer. The polymeric material may be a polyolefin or polyester. Preferably the polymeric material is polypropylene. Such may provide advantages in terms of weight and cost. Alternatively the polymeric material is polyethylene.

The hydrophilic means may comprise a hydrophilic additive.

The hydrophilic additive may be provided within the sheet form member, e.g. within filaments, microfilaments, microfibres, threads or tapes thereof.

The hydrophilic additive may comprise a melt additive, that is, an additive which is incorporated into a polymeric material melt prior to extrusion.

The hydrophilic additive may be a surfactant.

The hydrophilic additive may be a bi-functional molecule.

The hydrophilic additive may comprise a mono stearate, hydroxylamine or the like, commercially available additives include Irgasurf HL 560 from Ciba Specialty Chemicals.

The filaments may have an average diameter of between 10 microns and 30 microns, preferably between 13 microns and 26 microns, and preferably around 22 microns.

The sheet form member may have a basis weight of between 10 g/m2 and 40 g/m2, and typically around 18 g/m2.

The cover may comprise at least first and second parts each part comprising a sheet form member, each part having first and second opposing surfaces, wherein portions of the first surfaces of the first and second parts are joined at or near respective edges to form a first bonded, e.g. ultrasonically bonded seam, further portions of the first surfaces of the first and second parts forming at least part of a first surface of the parts forming at least part of a first surface of the sheeting, and further portions of the second surfaces of the first and second parts forming at least part of a second surface of the sheeting, wherein further the first seam depends from the second surface of the sheeting.

According to a second aspect of the present invention there is provided a method of manufacturing an agricultural cover, horticultural cover, crop cover or plant cover comprising the step of: forming at least one sheet form member comprising hydrophilic means.

The step of forming the at least one sheet form member comprising hydrophilic means may comprise: providing a polymeric material, which may be pelletised; providing a hydrophilic additive, which may be pellet ised; blending or mixing the polymeric material and the hydrophilic additive to form a mix; extruding the mix to form a plurality of filaments, tapes or threads.

The plurality of filaments may be laid down to form a nonwoven web.

The nonwoven web may be calender bonded to form a spunbond material which may comprise the sheet form member.

A bowl of the calender may be patterned with an island or point bond pattern.

The hydrophilic additive may comprise a hydrophilic material and a carrier polymer, which carrier polymeric material may be compatible with the polymeric material.

According to a third aspect of the present invention there is provided an agricultural cover, horticultural cover, crop cover or plant or seeding cover, the cover being liquid permeable, the crop cover comprising means for dispersing liquid droplets, which, in use, collect an upper surface of the cover.

The droplets may comprise rain water, dew, liquid crop spray or the like.

Optional features of the third aspect of the invention may be taken from the first aspect of the invention.

According to a fourth aspect of the present invention there is provided a method of manufacturing an agricultural crop cover, horticultural cover, crop cover or plant cover comprising the step of: forming at least one sheet form member comprising means for disposing liquid droplets, which, in use, collect on an upper surface of the cover.

According to a fifth aspect of the present invention there is provided a field or crop/plant growing area comprising a cover according to the first or the third aspect of the present invention.

According to a sixth aspect of the present invention there is provided a crop/plant growing house, greenhouse or hothouse comprising, having or being at least partially formed from a cover according to the first or the third aspect of the present invention.

According to a seventh aspect of the present invention there is provided a method of irrigating or spraying a field or crop/plant growing areas comprising the step of: providing a cover according to the first or the second aspect of the present invention;

covering at least part of the field or crop/plant

growing area with the cover; and spraying water and/or liquid plant/crop feed on the cover.

According to an eighth aspect of the present invention there is provided a ground cover, geotextile or construction fabric comprising at least one sheet form member comprising hydrophilic means.

Optional features of the eighth aspect of the invention may be the same as those of the first aspect of the invention.

The construction fabric may comprise a roofing fabric, membrane or underlay may comprise a walling fabric or membrane, e.g. a housewrap.

According to a ninth aspect of the present invention there is provided a method of manufacturing a ground cover, geotextile or construction fabric comprising the step of: forming at least one sheet form member comprising hydrophilic means.

Optional features of the ninth aspect of the invention may be the same as those of the second aspect of the invention.

According to a tenth aspect of the present invention there is provided a ground cover, geotextile or construction fabric, the cover being liquid permeable, the cover comprising means for dispersing liquid droplets, which, in use, collect on an upper surface of the cover.

Optional features of the tenth aspect of the invention may be the same as those of the third or eighth aspects of the invention.

According to an eleventh aspect of the present invention there is provided a method of manufacturing a ground cover, geotextile, or construction fabric comprising the step of: forming at least one sheet form member comprising means for dispersing liquid droplets, which, in use, collect on an upper surface of the cover.

Optional features of the eleventh aspect of the invention may be the same as those of the third aspect of the invention.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present invention will now be described by way of example only, and with reference to the accompanying drawings, which are: Figure 1 a perspective view from above and to one end of a

field having an

agricultural crop cover according to the present invention; Figure 2(a) a sample of a spunbond material used in making an agricultural crop cover

according to the prior art;

Figure 2(b) a sample of a spunbond material used in making an agricultural crop cover according to an embodiment of the present invention; Figure 3 a schematic diagram of a manufacturing apparatus for making the spunbond material of Figure 2 (b); Figure 4 a flow diagram representing steps for producing a single layer of spunbond fabric for use in embodiments of the present invention; Figure 5 a flow diagram representing steps for formation of a sheeting according to an embodiment of the present invention by ultrasonically bonding together two portions of spunbond fabric; Figure 6(a) an ultrasonic bonding apparatus for joining a number of pieces of spunbond fabric according to Figure 4 with seams formed using ultrasonic bonding so as to provide a sheeting according to the present invention; Figure 6(b) the joined fabric pieces of Figure 6(a) which can be opened out to be placed on a

field;

Figure 7 a sheeting according to an embodiment of the present invention including an upstanding seam formed by the process of Figure 6(a); Figure 8 a schematic top view of a sheeting according to an embodiment of the present invention including two portions of nonwoven spunbond fabric joined by an ultrasonically formed three stitch weld seam; Figure 9 a representation of part of an engraved island pattern utilizing oval bond islands provided on an embossing wheel for use in formation of a sheeting according to an embodiment of the present invent ion; Figure 10 a representation of an engraved island pattern utilizing oval bond islands incorporating islands shaped to form a logo to be applied to an embossing wheel; Figures 11(a) and 11(b) schematic cross-sectional views of alternative emboss island profiles taken along line A-A of Figure 9; Figure 11(c) a schematic profile of emboss points across the bond pattern of Figure 9 along line B -B; Figure 12(a) a flow diagram representing steps for producing a woven net for use in sheeting according to an embodiment of the present invention; Figure 12(b) a flow diagram representing steps for producing a nonwoven net for use in sheeting according to an embodiment of the present invention; Figure 13 a flow diagram representing steps for laminating a spunbond sheet to a net using an adhesive technique so as to provide a sheet part for use in sheeting according to an embodiment of the present invention; Figure 14 a flow diagram representing steps for laminating a spunbond sheet to a net using ultrasonic bonding so as to provide a sheet part for use in sheeting according to an embodiment of the present invention; Figure 15 a flow diagram representing steps for laminating a spunbond sheet to a net using a calender so as to provide a sheet part for use in sheeting according to an embodiment of the present invention; Figure 16 a schematic perspective view of a portion of a sheet part comprising a one layer nonwoven spunbond/one layer net laminate for use in an embodiment of the present invention; Figure 17 a schematic perspective view of a portion of a sheet part comprising a one layer nonwoven spunbond/one layer net/one layer nonwoven spunbond laminate for use in an embodiment of the present invention; Figure 18(a) a representation of part of an engraved elongate emboss island pattern provided on an embossing wheel for use in formation of a sheeting according to an embodiment of the present invention; Figure 18(b) a cross-sectional view of an emboss island taken along line A-A of Figure 18 (a) Figure 18(c) a schematic representation of an embossed pattern produced on a fabric after embossing of the fabric with the engraved emboss island pattern of Figure 18(a) the fabric comprising a sheet part according to an embodiment of the present invention; Figure 19(a) a representation of part of an engraved elongate emboss island pattern provided on an embossing wheel for use in formation of a sheeting according to an embodiment of the present invention; Figure 19(b) a cross-sectional view of an emboss island taken along line A-A of Figure 19(a); Figure 19(c) a schematic representation of an embossed pattern produced on a fabric after embossing of the fabric with the engraved emboss island pattern of Figure 19(a), the fabric comprising a sheet part according to an embodiment of the present invention; Figure 20(a) a representation of part of an engraved elongate emboss island pattern provided on an embossing wheel for use in formation of a sheeting according to an embodiment of the present invention; Figure 20(b) a cross-sectional view of an emboss island along line A-A of Figure 20(a); Figure 20(c) a schematic representation of an embossed pattern produced on a fabric after embossing of the fabric with the engraved emboss island pattern of Figure 20 (a) , the fabric comprising a sheet part according to an embodiment of the present invention; Figure 21(a) a representation of part of an engraved elongate emboss island pattern provided on an embossing wheel for use in formation of a sheeting according to an embodiment of the present invention; Figure 21(b) a cross-sectional view of an emboss island taken along line A-A of Figure 21 (a) Figure 21(c) a schematic representation of an embossed pattern produced on a fabric after embossing of the fabric with the engraved emboss pattern of Figure 21(a), the fabric comprising a sheet part according to an embodiment of the present invention; Figure 22 a schematic representation of an ultrasonic bonding apparatus comprising a horn and anvil for bonding the fabric to form seams according to the present invention; Figures 23(a), (b) and(c) differing constructions of seam which may be formed according to the present invention; Figure 23(d) an alternative seam construction which may be formed according to the present invention; Figure 24(a) a representation of part of an engraved elongate emboss island pattern provided on an embossing wheel for use in formation of a sheeting according to an embodiment of the present invention; and Figure 24(b) a cross-sectional view of the emboss island along line A-A of Figure 21(a)

DETAILED DESCRIPTION OF THE DRAWINGS

Referring initially to Figure 1 there is shown an agricultural cover, horticultural cover, crop cover or plant or seedling cover, generally designated 1, according to an embodiment of the present invention. The cover 1 comprises a sheet form member 2 having hydrophilic properties. This allows the crop to be uniformly treated or irrigated without having to remove the cover, as will hereinafter be described in greater detail. The hydrophilic properties provide means for dispersing liquid droplets, which, in use, collect or form on an upper surface of the cover.

The agricultural cover 1 comprises the at least one sheet form member 2, the sheet form member 2 comprising hydrophilic means.

It is believed that the use of the invention will extend the growing season, and generally increase the yield of a wide range of crops. Prior art crop covers suffer from the major disadvantage that such had to be lifted to irrigate and spray the crop evenly. This is a very labour intensive operation carried out at regular intervals during the growing season. With a cover according to the invention, lifting is not necessary.

Crops may be sprayed with, for example, water, liquid feed, herbicides and/or insecticides, as required, without a need for removing covers. A further advantage of a cover according to the invention, in allowing spraying to occur in situ is that the possibility of ingress of insects when the cover is removed is reduced.

The Applicant has observed that with provision of hydrophilic means or hydrophilic treatment, a rain droplet, upon impact with the cover, disperses through the sheet form member. The dispersed droplets then passes though the cover and form a mist of finer droplets, which gives more even coverage over the surface of the soil or ground.

In this embodiment the/each sheet form member 2 is liquid permeable and also gas/air permeable, and moisture vapour permeable, and further, capable of allowing light such as daylight to be transmitted.

The/each sheet form member 2 comprises a fabric in the form of a plurality of filaments, microfilaments, microfibres, threads, or tapes. In this preferred implementation the sheet form members 2 comprise a nonwoven material, and particularly a spunbond material, the nonwoven material comprising a plurality of filaments or microfilaments. The filaments typically have an average diameter of between 10 microns and 30 microns, preferably between 13 microns and 26 microns, e.g. around 22 microns. Also, the sheet form member 2 typically has a basis weight of between 10 g/m2 and 40 g/m2, e.g. around g/m2 microns.

In an alternative implementation the sheet form members 2 comprise a nonwoven, such as a flash spun material. In such case the nonwoven material comprises a plurality of microfibres. In a further alternative implementation the sheet form members 2 comprise a woven material. In such case the woven material comprises a plurality of threads or tapes.

The sheet form members 2 are substantially formed from a polymeric material such as a thermoplastic polymer. The polymeric material can be a polyolefin or polyester. In this preferred implementation the polymeric material is polypropylene. Such provides advantages in terms of weight and cost. In an alternative implementation the polymeric material is polythene.

The hydrophilic means comprises a hydrophilic additive. The hydrophilic additive comprises a melt additive, that is, an additive which is incorporated into a polymeric material melt prior to extrusion. The hydrophilic additive in this embodiment is a surfactant in the form of a bi-functional molecule.

The hydrophilic additive typically comprises a mono stearate, hydroxylamine or the like. A commercially available additive is Irgasurf HL 560 from Ciba Speciality Chemicals.

The cover 2 comprises each part 2a,2b,2c,2d comprising a sheet form member 2, at least first and second parts 2a,2b, having first and second opposing surfaces, in portions of the first surfaces of the first and second parts 2a,2b being joined at or near respective edges to form a first ultrasonically bonded seam 3, further portions of the first surfaces of the first and second parts 2a,2b forming at least part of a first surface of the sheeting, and further portions of the second surfaces of the first and second parts 2a,2b forming at least part of a second surface of the sheeting, wherein further the first seam depends from the second surface of the sheeting. Portions of the first or second surfaces of the first and second parts

2a,2b provide first and second outer surfaces of the first seam and neither first nor second outer surfaces of the first seam are joined with the second surface of the sheeting, surface to surface.

Surface properties of the individual filaments or tapes of which the/each sheet form member 2 is formed, are chemically altered by the hydrophilic means so as to change the surface tension of the filament or tape such that it will allow water to pass through. An example of this can be seen with reference to Figures 2 (a) and 2 (b) The Applicant has established that by adding a suitable hydrophilic means in the form of a hydrophilic additive to the polymer melt during tape or filament extrusion, the water permeability through the fabric of the sheet form member 2, can be significantly improved.

As can be seen from Figure 2 (a) , in a sheet form member 2 of the prior art, water droplets 4 tend to collect on the surface thereof in puddles. However, as can be scan from Figure 2 (b) in a sheet form member 2 of the invention water droplets disperse and soak through the fabric substantially evenly. The hydrophilic additive is a surfactant, which is a bi-functional molecule.

Without wishing to be bound by any theory, it is believed that the additive during processing the hydrophilic additive migrates to the surface of the filament. This allows the additive to align itself between the liquid-air interface along the fabric!s surface and lowers the energy at that point. This allows water-flow to be increased, as the water molecule does not experience the same resistance as from non-treated filaments.

Topical treatment of the fabric surface by a surfactant to enhance water flow is also a possibility.

However, the Applicant believes that such a treatment may not be sufficiently durable for an agricultural or horticultural application where the fabric is required to perform its function for one or more growing seasons.

Topical or surface treatments can relatively easily be removed from the surface during installation and use.

An advantage of melt additives is that they are not easily removed from the surface and do not leech out into the watercourse. Also, any reduction in concentration in additive on the polymer surface can be replenished by a "reservoir' of additive retained in the body of the filament or microfilament, microfibres, thread or tape.

This can be achieved by migration of additive to maintain an equilibrium of concentration between the surface and body of the filament or the like.

Referring now to Figure 3 there is shown a manufacturing apparatus, generally designated 600, for making spunbond material according to the present invention. A method of manufacturing the cover 1 according to the invention comprises the steps of: forming at least one sheet form member 2a,2b,2c,2d comprising hydrophilic means.

The step of forming the at least one sheet form member 2 comprising hydrophilic means comprises: providing a polymeric material, which is typically pelletised; providing a hydrophilic additive, which is typically pelletised; blending or mixing the polymeric material and the hydrophilic additive to form a mix; extruding the mix to form a plurality of filaments, tapes or threads.

The plurality of filaments are laid to form a nonwoven web. The nonwoven web is calendar bonded to form a spunbond material which comprises the sheet form member 2. A bowl of the calendar is normally patterned with an island or point bond pattern.

The hydrophilic additive typically comprises a hydrophilic material and a carrier polymer, which carrier polymeric material is compatible with the polymeric material.

The sheet form members 2a,2b,2c,2d can then be joined together to form the cover 1, e.g. by ultrasonic bonding as detailed hereinafter.

With reference now to Figure 4, polymer feed, typically in the form of polymer granules or powder comprising, for example, polypropylene is blown from a storage silo into a holding hopper, from which it is fed by vacuum into a dosing unit, and then by gravity into a mixing hopper from which it enters an extruder hopper and then an extruder. Other materials, such as the hydrophilic means in the form of hydrophilic additive masterbatch, as well as other additives or masterbatch or the like, can be transferred by vacuum into a separate dosing unit and then fed gravimetrically into the mixing hopper, where it is mixed with the polypropylene before being fed into the extruder hopper. Other additives may comprise colour, UV stabiliser, temperature/heat stabiliser or masterbatches. The polymer is transported by screw feed through a zone heated extruder. The thermal gradient is typically approximately 185 C -215 C. During this process the polymer is melted, and mixed by the screw to give a homogenous melt. On exit, the melt is filtered, then pumped by means of a spin pump to a die block. The die block is a highly engineered metal block which is normally 3.2 metres wide with approximately 12,000 holes, or 2.4 metres wide with approximately 9000 holes. Each of these holes is of the order of 0.6mm in diameter.

The molten polypropylene blend is then pumped through the die to form a multiplicity of continuous filaments, which are extruded downwards through a controlled air flow.

The air flow is controlled to serve three functions: 1. To cool and solidify the filaments, 2. To stretch the filaments, in order to make the fibres finer and to develop fibre tenacity, 3. To deposit filaments in a random fashion on to a moving spin belt, to form a loose unconsolidated web.

The web is transferred from the spin belt to a conveyor belt for emboss bonding in a hot thermal calender to form a sheet part comprising a single layer of spunbond fabric for use in embodiments of the present invention.

With reference to Figure 5, two layers of such sheet parts are overlapped, and the overlapped "C" portions then subjected to ultrasonic energy by feeding the overlapped portions into an ultrasonic apparatus where heat is delivered to the sheet parts by means of a horn.

Local softening and/or melting of the sheet parts occurs where the ultrasonic energy is applied to the sheet part, and the two layers are then able to bond together to form a seam at a joined portion. The joined sheet parts are then wound onto a winder for storage. The above process may be repeated to join as many pieces of fabric together as necessary to give the final sheeting products such as a crop cover product.

Referring to Figure 6(a), as an example, five rolls 1OA -1OE of sheet parts comprising spunbond fabric are schematically shown in perspective from above. The fabric 12 from the top of roll 1OA is unwound and passed over the top of roll lOB. The fabric 14 from the top of roll lOB is then also unwound so that the two layers of fabric are overlapping and extending in the direction of arrow 30. Ultrasound is applied to the overlapped edge of the two pieces of fabric 12,14 as the fabric 12,14 passes through an ultrasonic welding unit 40A.

This process is continued, and the overlapped and joined fabrics 12,14 from rolls 1OA and lOB respectively then passes over the top of roll bC. The fabric 15 from the top of roll bC is then unwound and joined to the fabric 14 from roll lOB by forming a seam using an ultrasonic welding unit 403 at an edge of the overlapped fabrics.

The process continues by joining the fabric 16 from roll 1OD to fabric 15 from roll bC, using ultrasonic welding apparatus 40C, and joining the fabric 14 from roll lOB to fabric 16 from roll 1OD using ultrasonic welding apparatus 40D. The final layered fabric 18 is thus formed as a concertinaed sheet 50 and is wound onto a storage roll 20.

As indicated schematically in Figure 6(b), in use, the concertinaed sheet 50 is unwound from a roll 55 and opened out by unfolding it to its full width while being placed onto a crop field or planting area or the like as indicated by arrows 60 and 70.

An example of an ultrasonic bonding apparatus, e.g. 40A is shown schematically in Figure 22. The apparatus 40A comprises a weld horn 460 and an anvil in the form of a rotatable drum or wheel 465. Fabric 470 to be bonded is passed between the weld horn 460 and anvil drum 465, where the weld horn 460 delivers ultrasound to the fabric 470. The anvil drum 465 has an engraving pattern comprising emboss islands 475 applied to its surface.

Apparatus 40A further comprises a computer controlled force control unit 480 having a force sensor chip 485 which enables the weld horn 460 to move in a vertical direction to ensure a more or less constant pressure is applied to the fabric 470 in response to thickness variations in fabric 470.

Figures 23(a) to 23(d) show several versions of seam construction which may be accomplished with the present invention.

Figure 23(a) shows a sheeting 500 comprised of two fabric layers 510 and 520 joined together by an ultrasonically formed seam 530 consisting of the two bonded fabric layers 510 and 520.

Figure 23 (b) also shows a two fabric layer sheeting 500, but the seam 540 is formed from three bonded fabric layers formed by the top layer 510 being folded back on itself before bonding the layers 510 and 520 together.

Figure 23(c) shows a two fabric layer sheeting which has a four fabric layer seam 550 formed by the top layer 510 and the bottom layer 520 being folded back on themselves before bonding the layers 510 and 520 together.

Figure 23 (d) shows a seam construction showing a two fabric layer sheeting 500 comprised of two fabric layers 510 and 520 in a partially overlapped relationship to one another. The fabric layers 510 and 520 are joined together by an ultrasonically formed seam 535 at the overlap region 537 of the fabric layers 510 and 520.

Figure 7 shows in detail the construction of a seam which is like seam 530 of Figure 23 (a), generally designated 80, as formed by the process illustrated in Figure 6 (a) . The seam 80 may be described as an upstanding seam, although, of course it may not project upwardly, as shown, but may lie on one side or may indeed be downstanding.

As shown, the seam 80 is comprised of one fabric sheet 90 on one side which is joined to another fabric sheet 90 on another side. A bond pattern, generally designated 100, is indicated which is substantially the same as that shown in Figure 9. The pattern 100 is composed of individual emboss or bond points 110, ill and those labelled 110 are spaced at a lower frequency in the direction of arrow 120 than other emboss points 111.

Figure 8 shows a three stitch weld pattern 130 applied to a seam, generally designated 129, of a two layer spunbond laminate fabric 132. The bonding pattern 130 is formed from raised portions or islands on the ultrasonic welding wheel pressing onto the fabric 132 while bonding is progressing. The three stitch weld pattern 130 provides a strong and durable seam 129 because the fibres of the fabric 132 are not fixed into any one position like in a solid bar weld seam (not shown) . This allows the fabric 132 about the seam 129 to "give" somewhat when subjected to a shearing force which ensures the seam 129 is less likely to tear when subjected to stresses.

Figure 9 shows a discontinuous pattern of raised engraving emboss islands, generally designated 140, comprising of oval emboss islands 145. The pattern 140 comprises four substantially parallel lines 150a -150d of emboss islands, and as shown, line 150a has adjacent emboss islands spaced apart at around twice the distance S than those in lines 150b -l5Od.

Furthermore, in this embodiment the emboss islands in the pattern 140 all have the same orientation, so that a long axis of each island is aligned substantially parallel to a long axis of the pattern 140. The lines 150a -150d of islands 145 are arranged so that the islands in one line, e.g. l5Ob, are off-set to those in an adjacent line, e.g. 150c.

Figure 10 shows a series of emboss islands 145 which are arranged as a bond pattern, generally designated 160, The islands 145 are substantially oval and are arranged as series A and series B, separated by an engraved island logo 165 running in between the series A and B. Series B comprises four substantially parallel lines 170a -170d of emboss islands 145, whereas series A comprises three substantially parallel lines 175a -175c of emboss islands 145. The islands 145 in both series A and B are transversely off-set with respect to adjacent emboss islands 145 and in an adjacent line, for example, island 171 is transversely off-set with respect to island 172.

It is noted that within each of lines 175a -175c or 170a -170d of series A or series B respectively, the emboss islands 145 are rotated by 45 with respect to the next island. For example, emboss island 180b is rotated by 45 with respect to emboss island 180a, emboss island 180c is rotated by 45 with respect to emboss island 180b, and emboss island 180d is rotated by 45 with respect to emboss island 180c. The rotation is in the same direction for all emboss islands 145 in the series.

The emboss islands in line 170d are spaced at around twice the distance between those in the other lines 170a -170c and 175a -175c.

The emboss islands logo 165, which can comprise a Trade Mark is provided by a suitably shaped embossing wheel which also carries the emboss islands.

The engraved patterns shown in Figures 9 and 10 when impressed into a fabric during a seam forming operation, provide a strong and durable seam (not shown) because the fibres of the fabric are not fixed into any one position like in a solid bar weld seam (not shown) . This allows the fabric about the seam to "give" somewhat when subjected to a shearing force, which ensures the seam is less likely to tear when subjected to stresses.

Figure 11(b) is a cross-sectional view of a single emboss island 145 of Figure 11(b) as indicated by line A-A on Figure 9.

Figure 11(a) shows a cross-sectional view of an alternative bond island (not shown).

It can be seen that the emboss island 145 of Figure 11(b) has curved edges -indicated by arrow 200 -which may help in providing a bonded point (not shown) in a fabric (not shown) which is less likely to tear or is less damaged as compared to bond points formed by the profile of emboss island shown in Figure 11 (a) Figure 11(c) shows a schematic cross-sectional profile of engraving emboss islands 145 taken across the engraving emboss island pattern 140 of Figure 9 along line B -B. It can be clearly seen that the height of the emboss islands 145 decreases in the direction of arrow 210; thus the point welding in a fabric (not shown) by line 150a of emboss islands of Figure 9 will be the least deeply embossed, with line 150d of emboss islands giving the most deeply embossed welding in the fabric.

Referring now to Figure 12(a) there is shown a flow diagram for producing a woven net for use in a sheeting according to an embodiment of the present invention.

Polypropylene granules are blown from a storage silo and fed into a holding hopper, from which they are fed into a mixing hopper and then into the extruder. Additives, (such as colour masterbatch, UV stabilizer, heat stabilizer and/or chalk) can be fed into separate dosing units, and then into the common mixing hopper where they mix with the polypropylene granules to form a blend before being fed into the extruder.

The polypropylene or blend is then fed into an extruder and through a die to form as either a film or fibres as depending on the type of die used. If a film is formed, it can be slit with blades to form tapes. If fibres are formed, they are drawn into tapes. The tapes are then either calender treated or heat set and then wound. The tapes are then woven into netting using weaving looms.

Figure 12 (b) shows steps for producing a non-woven net for use in a sheeting according to an embodiment of the present invention. Polymer feed, usually polypropylene, is taken from storage and fed into an extruder hopper and then into a round die. The polymer feed is forced through the round die by means of a melt pump. Oscillations of the die facilitate the formation of a netting which forms as a tube which is then slit so that a flat net sheet forms. The net mesh is then deposited onto a conveyor belt and then wound up into a roll. The roll is then unwound, and the net sheet is elongated and widened by a number of rollers. The resultant net is re-rolled to give the finished product.

Figure 13 shows steps for laminating a spunbond fabric to a net using an adhesive so as to form a sheet part for use in a sheeting according to the present invention. The adhesive may be applied to either the net or the spunbond material, either as a hot glue spray which sets as it cools or powder coating which is heat and pressure activated. Alternatively, an adhesive may be co-extruded with the netting material during its manufacture.

The spunbond fabric and net are then brought together and passed through bonding machinery such as a heated calender to fix the two layers together, thus giving a reinforced sheet part.

Figure 14 shows steps to bond a net to a spunbond fabric by means of ultrasonic bonding so as to form a sheet part for use in a sheeting according to an embodiment of the present invention. The steps are essentially the same as for bonding two layers of spunbond fabric. The netting is overlapped substantially completely with the spunbond fabric so that the two layers substantially coincide. The assembly is then fed into the ultrasonic bonding apparatus where local softening of the net and spunbond fabric occurs. The net and spunbond then bond to each other, and the laminate is then wound on to a winder to give a sheet part which is reinforced with a net.

Figure 15 illustrates steps for producing a sheet part or reinforced cover product for use in a sheeting according to an embodiment of the present invention by bonding together a spunbond material and netting using a calender. This is a useful technique when the spunbond and netting materials have similar melting points because they are bonded using heat and pressure applied by the calender.

A sheet part for use in a sheeting according to an embodiment of the present invention is shown in Figure 13, the sheet part comprising a two layer net/spunbond laminate 250. Figure 16 includes a magnified portion of the sheet part represented by the circled area. The net 255 and spunbond fabric 260 are laminated by the ultrasonic bonding method to form a single sheet of laminate material 250.

Another sheet part for use in a sheeting according to an embodiment of the present invention is shown in Figure 17, the sheet part comprising three layer laminate 270. The sheet part comprises two layers of spunbond fabric 260 sandwiching a net 255. The fabric layers 260 and net 255 are bonded together effectively by use of the ultrasonic technique to give a single sheet of laminate material 270.

Figure 18(a) shows a series of engraving elongate raised emboss islands 305, viewed from above, in a discontinuous pattern, generally designated 300 for use in formation of a sheeting according to an embodiment of the present invention. The pattern 300 includes intermittent flat or non-raised regions shown as breaks 310 in the pattern 300. The circled portion of Figure 18(a) is shown to an enlarged scale.

The emboss islands 305 of Figure 18(a) are arranged in seven lines 320a -320g and the emboss islands 305 in one line 320a -320g are off-set to those in an adjacent line 320a -320g. The islands in every other line, that is, lines 320a, 320c, 320e and 320g or 320b, 320d and 320f are not off-set to each other.

Figure 18(b) shows a cross-sectional view of a single emboss island 305 along line A -A in the enlarged scale portion of Figure 18 (a) . It is noted that the edges 330 of the emboss island are not sharp, but are smooth or curved.

Figure 18(c) shows a pattern 340 produced in a fabric seam (not shown) after bonding using the engraved island pattern 300 of Figure l8a.

Figure 19(a) shows a series of engraving emboss islands 305 in a pattern generally designated 350. This pattern 350 is substantially the same as pattern 300 of Figure 18(a) except that the pattern 350 is not fully interrupted, the pattern 350 being joined by uninterrupted line 360 of emboss islands 305. Also, a line 370 distal from line 360 contains bond islands 380a -380d which are curved, and lead into the flat or non-raised areas 390.

Figures 19(b) and 19(c) respectively show a cross-sectional view of a single emboss island 305 along line A -A of Figure 19(a), and the bond pattern 395 produced in a fabric seam (not shown) after bonding with the engraving emboss island pattern 350 of Figure 19 (a) Figure 20(a) shows an alternative engraving bond island pattern 400 which is similar to patterns 300 and 350 in Figures 18(a) and 19(a) respectively.

Flat or non-raised regions 410 of the pattern 400 are shaped so that they taper towards a line 420 of bond islands 415, which is uninterrupted.

Figure 20(b) shows a cross-sectional view of a single emboss island along line A -A on Figure 20(a), and Figure 20(c) shows a pattern 425 produced in a fabric seam (not shown) by engraving emboss island pattern 400.

Figure 21(a) shows an alternative elongate bar pattern 430 interrupted by flat or non-raised regions 440. The pattern 430 consists of regions 450 containing seven lines 435a -435g of solid bar emboss islands 445, which are not offset one from the other.

Figure 21(b) shows a cross-sectional view along line A -A of Figure 21(a), and Figure 21(c) shows a pattern 455 produced in a fabric seam (not shown) when bonded using the engraving emboss island pattern 430 of Figure 21(a).

Figure 22 (a) shows another example of a series of engraving elongate raised emboss islands 565, viewed from above, in a discontinuous pattern generally designated 560 for use in formation of a sheeting according to an embodiment of the present invention. The pattern 560 includes flat or non-raised regions shown as breaks 579 in the pattern 565. The circled portion of Figure 24(a) is shown to an enlarged scale. Pattern 560 is similar to pattern 300 shown in Figure 18 (a) Figure 24(b) shows a cross-sectional view of a single emboss island 565 along line A - A in the enlarged scale portion of Figure 24 (a) . It is noted that the edges 575 of the emboss island are not sharp, but are smooth or curved. It is also noted that a face 580 of the island 565 is wider than the corresponding face 335 of island 305 in Figure 18 (b) It will be appreciated that the embodiments of the present invention hereinbefore described are given by way of example only, and are not limiting of the scope of the invention in any way other embodiments may be envisaged.

For example, any number of layers of spunbond and/or net may be bonded together, possibly using the ultrasonic methods described herein, to produce a reinforced sheeting.

It will also be appreciated that although the disclosed embodiments are described as agricultural covers or horticultural covers, other uses of the disclosed fabrics are possible, and fall within the scope of the invention, such as, though not limited to, ground covers, geotextiles, and construction fabrics.

Claims

CLAIMS

1. An agricultural cover, horticultural cover, crop cover or plant or seedling cover comprising at least one sheet form member, the sheet form member comprising hydrophilic means.
2. A cover as claimed in claim 1, wherein the sheet form member is liquid permeable.
3. A cover as claimed in either of claims 1 or 2, wherein the sheet form member is gas/air permeable.
4. A cover as claimed in any of claims 1 to 3, wherein the sheet form member is moisture vapour permeable.
5. A cover as claimed in any preceding claim, wherein * ** the sheet form member is capable of allowing passage of * S I I...

. 20 light, such as daylight. S.. I. * I * I..
6. A cover as claimed in any preceding claim, wherein *::: : the/each sheet form member comprises a fabric.

**5I55 * S
7. A cover as claimed in any preceding claim, wherein the/each sheet form member comprises a plurality of filaments, microfilaments, microfibres, threads, or tapes.
8. A cover as claimed in any preceding claim, wherein the sheet form member comprises a nonwoven material, such as a spunbond material.
9. A cover as claimed in claim 8, wherein the nonwoven material comprises a plurality of filaments or microfilaments.
10. A cover as claimed in any preceding claim, wherein the sheet form member is substantially formed from a polymeric material such as a thermoplastic polymer.
11. A cover as claimed in claim 10, wherein the polymeric material is a polyolefin or polyester. * S. * . I *SS.
12. A cover as claimed in claim 10, wherein the *SS.

polymeric material is polypropylene. S..
13. A cover as claimed in claim 10, wherein the * * S S. * polymeric material is polyethylene.
14. A cover as claimed in any preceding claim, wherein the hydrophilic means comprises a hydrophilic additive.
15. A cover as claimed in claim 14, wherein the hydrophilic additive is provided within the sheet form member, such as within filaments, microfilaments, microfibres, threads or tapes thereof.
16. A cover as claimed in either of claims 14 or 15, wherein the hydrophilic additive comprises a melt additive.
17. A cover as claimed in any of claims 14 to 16, wherein the hydrophilic additive is a surfactant.
18. A cover as claimed in any of claims 14 to 17, wherein the hydrophilic additive is a bi-functional molecule.

: *.
19. A cover as claimed in any of claims 14 to 18, *S..

. wherein the hydrophilic additive comprises a mono stearate, hydroxylamine or the like. S..

:
20. A cover as claimed in any preceding claim, wherein the filaments have an average diameter of between 10 microns and 30 microns, between 13 microns and 26 microns, or around 22 microns.

21. A cover as claimed in any preceding claim, wherein the sheet form member has a basis weight of between 10 g/m2 and 40 g/m2, or around 18 g/m2.

22. A cover as claimed in any preceding claim, wherein the cover comprises at least first and second parts each part comprising a sheet form member, each part having first and second opposing surfaces, wherein portions of the first surfaces of the first and second parts are joined at or near respective edges to form a first bonded seam, such as an ultrasonically bonded seam, further portions of the first surfaces of the first and second parts forming at least part of a first surface of the sheeting, and further portions of the second surfaces of the first and second parts forming at least part of a second surface of the sheeting, wherein further the first seam depends from the second surface of the sheeting. * I. * S * ***S

23. A cover as claimed in claim 22, wherein portions of *S*.

the first or second surfaces of the first and second * S * *** parts provide first and second outer surfaces of the first seam and neither first nor second outer surfaces of * S S S. S the first seam are joined with the second surface of the sheeting, surface to surface.

24. An agricultural or horticultural cover comprising a sheet form member having hydrophilic properties.

25. A method of manufacturing an agricultural cover, horticultural cover, crop cover or plant cover comprising the step of: forming at least one sheet form member comprising hydrophilic means.

26. A method as claimed in claim 25, wherein the step of forming the at least one sheet form member comprising hydrophilic means comprises: providing a polymeric material, which is optionally pelletised; is providing a hydrophilic additive, which is optionally pelletised; blending or mixing the polymeric material and the : ** hydrophilic additive to form a mix; s'... extruding the mix to form a plurality of filaments, *. 20 tapes or threads. 55*

27. A method as claimed in claim 26, wherein the * 5 5 5 plurality of filaments are laid down to form a nonwoven web.

28. A method as claimed in claim 27, wherein the nonwoven web is calender bonded to form a spunbond material which comprises the sheet form member.

29. A method as claimed in claim 28, wherein a bowl of the calender is patterned with an island or point bond pattern.

30. A method as claimed in claim 29, wherein the hydrophilic means comprises a hydrophilic material and a carrier polymer, which carrier polymeric material is compatible with the polymeric material.

31. An agricultural cover, horticultural cover, crop cover or plant or seeding cover, the cover being liquid permeable, the crop cover comprising means for dispersing liquid droplets, which, in use, collect on an upper * ** surface of the cover. * S S 5.5 *.e* * S SSS*

32. A method as claimed in claim 31, wherein the * S * .5* ** droplets comprise rain water, dew, liquid crop spray or *.. the like. * S S S. * * .

33. A method of manufacturing an agricultural crop cover, horticultural cover, crop cover or plant cover comprising the step of: forming at least one sheet form member comprising means for disposing liquid droplets, which, in use, collect on an upper surface of the cover.

34. A field or crop/plant growing area comprising a cover according to any of claims 1 to 23, claim 24 or either of claims 31 or 32.

35. A crop/plant growing house, greenhouse or hothouse comprising, having or being at least partially formed from a cover according to any of claims 1 to 23, claim 24 or either of claims 31 or 32.

36. A method of irrigating or spraying a field or

crop/plant growing areas comprising the step of: providing a cover according to the first or the second aspect of the present invention;

covering at least part of the field or crop/plant

growing area with the cover; and *.. S spraying water and/or liquid plant/crop feed on the cover.

S *. .

37. A ground cover, geotextile or construction fabric comprising at least one sheet form member comprising hydrophilic means.

38. A fabric as claimed in claim 37, wherein the construction fabric comprises a roofing fabric, membrane or underlay or comprises a walling fabric or membrane, such as a housewrap.

39. A method of manufacturing a ground cover, geotextile or construction fabric comprising the step of: forming at least one sheet form member comprising hydrophilic means.

40. A ground cover, geotextile or construction fabric, the cover being liquid permeable, the cover comprising means for dispersing liquid droplets, which, in use, collect on an upper surface of the cover.

41. A method of manufacturing a ground cover, geotextile, or construction fabric comprising the step of: * I forming at least one sheet form member comprising means for dispersing liquid droplets, which, in use, collect on an upper surface of the cover. S.-

S S p.

42. A cover as hereinbefore described with reference to the accompanying drawings.

43. A method of manufacturing a cover as hereinbefore described with reference to the accompanying drawings.

44. A field or plant growing area comprising a cover as hereinbefore described with reference to the accompanying drawings.

45. A crop/plant growing house, greenhouse or hothouse comprising or having a cover as hereinbefore described with reference to the accompanying drawings.

I * I S

ISIS S.. * S *11.

IS

SI * S.. S..

I S.. * I I I. p

ISIS SI f. .