WO2015042641A1 - Film plastique formant mulch agricole et sa composite - Google Patents

Film plastique formant mulch agricole et sa composite Download PDF

Info

Publication number
WO2015042641A1
WO2015042641A1 PCT/AU2014/000934 AU2014000934W WO2015042641A1 WO 2015042641 A1 WO2015042641 A1 WO 2015042641A1 AU 2014000934 W AU2014000934 W AU 2014000934W WO 2015042641 A1 WO2015042641 A1 WO 2015042641A1
Authority
WO
WIPO (PCT)
Prior art keywords
film
biodegradable polymer
hydro
oxo
polymer layer
Prior art date
Application number
PCT/AU2014/000934
Other languages
English (en)
Inventor
Douglas Michael Trenchard
Robert Charles TRENCHARD
Original Assignee
Douglas Michael Trenchard
Robert Charles TRENCHARD
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2013903693A external-priority patent/AU2013903693A0/en
Application filed by Douglas Michael Trenchard, Robert Charles TRENCHARD filed Critical Douglas Michael Trenchard
Publication of WO2015042641A1 publication Critical patent/WO2015042641A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G13/00—Protecting plants
    • A01G13/02—Protective coverings for plants; Coverings for the ground; Devices for laying-out or removing coverings
    • A01G13/0256—Ground coverings
    • A01G13/0268—Mats or sheets, e.g. nets or fabrics
    • A01G13/0275—Films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B29C48/185—Articles comprising two or more components, e.g. co-extruded layers the components being layers comprising six or more components, i.e. each component being counted once for each time it is present, e.g. in a layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/327—Layered products comprising a layer of synthetic resin comprising polyolefins comprising polyolefins obtained by a metallocene or single-site catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/10—Inorganic particles
    • B32B2264/102—Oxide or hydroxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/10—Inorganic particles
    • B32B2264/104—Oxysalt, e.g. carbonate, sulfate, phosphate or nitrate particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/71—Resistive to light or to UV
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/716—Degradable
    • B32B2307/7163—Biodegradable
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2410/00—Agriculture-related articles

Definitions

  • the present invention relates to biodegradable and decomposable mulch film and in particular to an agricultural plastic mulch film and a composite thereof,
  • Agricultural plastic mulch film is widely used to cover, enclose or protect the soil for the growing of crops, particularly under fully exposed outdoor conditions, for a given period of time or time of year.
  • standard polyethylene mulch film contains many types of chemicals designed to protect them from exposure to heat during the manufacturing process and from the degrading elements of the environment in which it is used, such as ultraviolet light (UV) absorbers, UV stabilizers, anti-oxidants, processing aids and light absorbers along with components to increase opacity or increase light reflection. All of these are designed to prevent the oxidation and ultimate scission of the long polymer molecules and thus extend the life of the plastic sufficient for easy collection at the end of its useful life. These additives add to the cost of the polymer mix used to produce the mulch film and the added cost and time required to lift, collect and dispose of the film at the end of its life are considerable, especially if the plastic has started io degrade.
  • the mulch film does not have to be lifted and disposed of at the end of the season, but can degrade and be mineralized and can be absorbed into biomass in the soil.
  • the most common method of chemically degrading polyethylene based mulch films is for the long chain molecules of the polymer to be oxidized. Once the molecule is oxidized, it will break forming two shorter molecules. As this process of oxidation and scission continues, the polymer becomes highly oxidized and hydrophific and as the individual molecules become increasingly short and consequentl less flexible; the whole sheet of polyethylene film becomes brittle and fragments. Once the molecular size has been sufficiently reduced, the polyethylene may be assimilated, that is, attacked and mineralized, by the enzymatic actions of microbes.
  • polyethylene is resistant to most chemicals, which makes the oxidation of polyethylene based mulch films a slow process that may take many years to disintegrate the film and even longer to mineralize the components. Attempts have been made to accelerate the degradation of such films by introducing a catalytic prodegradant additive into the polymer mix forming the polyethylene film.
  • This type of polyethylene is known as oxo-biodegradab!e polyethylene.
  • Mulch film is also manufactured from hydro-biodegradable polymers.
  • Hydo- biodegradable mulch films have been successfully manufactured from polyester blends. Polyesters contain an ester functional group in their main chain, which can be cleaved by hydrolysis in the presence of water, acid or alkali, thereby exposing the cleaved long chain polymer fragments to subsequent assimilation and mineralization by the enzymatic activity of microbes.
  • hydro-biodegradable polymers are abte to disintegrate and mineralize without the need for human intervention, these polymers are typically very expensive when compared with polyethylene and are approximately 30% denser, in addition, by virtue of these hydro-biodegradable polymers being readily assimilated by microbes, thei life span can be too short for the mulch film to be effective in protecting the crop for the entire growing season. By the same token, the shelf life of these polymers does not permit Song term storage and the mulch film ro!ls have to be handled with great care as the plastic film may be easily damaged.
  • the polyesters used in making hydro-biodegradable mulch films have a high permeability to water and thus when used in very dry climates where the mulch film is expected to retain soil moisture content, they fail by allowing the moisture to permeate through them.
  • This high moisture permeability is increased when the polyester polymer or blend is blended with starch due to the ability of the starch component to absorb moisture thereby accelerating the hydrolysis and biodegradation of the polymer,
  • Polyester polymers also have a high level of inherent tack and the layers of the plastic tend to stick to each other, this can create excessive tension on the mulch film as it is laid out. This high tack further ensures that should the roll be damaged by being dropped onto a sharp object, the roll is easily dented and where the dent occurs, the mulch film becomes difficult to unwind and easily tears at that point.
  • PLA poly lactic acid
  • PBAT inherently biodegradable polyesters
  • PLA poly lactic acid
  • PBAT inherently biodegradable polyesters
  • Adding a strffer polymer such as PLA to pure polyester improves the tensile properties of the polyester to allow it to be extruded by the blown film process and to reduce the rate of degradation.
  • PLA is also included as it does not hydrolyse below its glass transition temperature, which is in excess of 58°C. This is important as the hydrolysis of PLA is a pre-requisiie for its biodegradation.
  • PLA does not degrade in soil at ambient temperatures and thus delays the disintegration of the mulch film.
  • an agricultural plastic muich film comprising alternating layers of at least one oxo- biodegradable polymer layer and at least one hydro-biodegradable polymer layer.
  • the at least one oxo-biodegradabie polymer layer comprises at least two oxo-biodegradable polymer layers, each forming an outer layer of the agricultural plastic mulch film.
  • the at least one hydro-biodegradable polymer layer comprises at least two hydro-biodegradable polymer layers, each forming an outer layer of the agricultural plastic mulch film.
  • the film further comprises an adhesive to promote adhesion between the at least one oxo-biodegradabie polymer layer and the at least one hydro-biodegradable poiymer layer.
  • the adhesive is selected from the group consisting of a po!yolefin, a polyester and a vinyl polymer.
  • the vinyl polymer is selected from the group consisting of ethyl vinyl acetate, polyisobutylene, and modified forms thereof.
  • the at least one oxo-biodegradable polymer layer comprises a polyolefin polymer.
  • the polyolefin polymer is selected from the group consisting of linear low density polyethylene, low density polyethylene, high density polyethylene, ultra iow density polyethylene, rnetal!ocene linear low density polyethylene, metallocene low density polyethylene, and blends or copolymers thereof.
  • the polyolefin polymer is selected from the group consisting of polypropylene, polyethylene, polyisobutylene, polyisoprene, and blends or copolymers thereof,
  • the at least one oxo-biodegradable polymer layer further comprises an effective amount of at least one prodegradant to promote accelerated photodegradation and/or thermal degradation of the at least one oxo- biodegradable polymer layer.
  • the film furthe comprises at least one enzyme to assist the at least one prodegradant with the photodegradation and/or thermal degradation of the at least one oxo-biodegradable polymer layer,
  • the at least one prodegradant is an organic salt of a polyvalent transition metal.
  • the at least one prodegradant is an organic salt of copper, manganese, iron or cobalt.
  • the at least one prodegradant is selected from the group consisting of manganese stearate, iron stearate and cobalt stearate.
  • the at least one prodegradant is present in an effective amount between about 0.01 and about 20.0 weight percent
  • the at least one prodegradant is present in an effective amount between about 0.1 and about 5.0 weight percent.
  • the at least one hydro-biodegradable polymer layer comprises a biodegradable polyester selected from the group consisting of a linear aliphatic polyester, an aliphatic polyester, an aromatic-aliphatic co-polyester, and blends or copolymers thereof.
  • the at least one hydro-biodegradable polymer layer comprises a biodegradable polyester blended with poly lactic acid (PLA), thermoplastic starch (TPS), or starch.
  • PLA poly lactic acid
  • TPS thermoplastic starch
  • the at least one hydro-biodegradable polymer layer comprises a po!yhydroxyalkanoate (PHA) or a copolymer thereof either in pure form or blended with poiy lactic acid (PLA), starch, thermoplastic starch (TPS), or other polyester polymer.
  • PHA po!yhydroxyalkanoate
  • PES thermoplastic starch
  • the at least one hydro-biodegradable polymer layer comprises poly (3-hydroxybutyrate) (PHB) or a copolymer thereof either in pure form or blended with poly lactic acid (PLA), starch, thermopiastic starch (TPS) or other polyester polymer.
  • PHB poly (3-hydroxybutyrate)
  • PHA poly lactic acid
  • TPS thermopiastic starch
  • the at least one hydro-biodegradable polymer layer comprises polybutylenesuccinate (PBS) or poly(buty!ene succinate adipate) (PBSA) or copolymers thereof either in pure form or biended with poly lactic acid (PLA), starch or other polyester polymer.
  • PBS polybutylenesuccinate
  • PBSA poly(buty!ene succinate adipate)
  • PHA polylactic acid
  • the at least one hydro-biodegradable polymer layer comprises poiy (butylene adipate-co-terephthalate) (PBAT) or a copolymer thereof either in pure form or blended with poly lactic acid (PLA), starch, thermoplastic starch (TPS) or other polyester polymer.
  • PBAT poiy (butylene adipate-co-terephthalate)
  • PHA poly lactic acid
  • TPS thermoplastic starch
  • the at least one hydro-biodegradable polymer layer comprises poly(propylene carbonate) (PPC) or a copolymer thereof either in pure form or blended with poly lactic acid (PLA) , starch, thermoplastic starch (TPS) or othe polyester polymer.
  • PPC poly(propylene carbonate)
  • PLA polylactic acid
  • TPS thermoplastic starch
  • the at least one hydro-biodegradable polymer layer is not soluble in water.
  • the at least one oxo-biodegradabie polymer layer and/or the at least one hydro-biodegradable polymer layer each comprise an effective amount of at least one additive selected from the group consisting of an anti-oxidant, a UV stabiliser, a UV absorber, a colourant and a filler.
  • the colourant is selected from the group consisting of carbon black, coated or uncoated titanium dioxide or coated or uncoated aluminium flakes.
  • the filler is selected from the group consisting of calcium carbonate, kaolin, talc and clay.
  • the filler is selected from the group consisting of starch, polymerised starch and thermoplastic starch (TPS).
  • TPS thermoplastic starch
  • the at least one oxo-biodegradab!e polymer layer and the at least one hydro-biodegradable polymer layer are bonded together during a process of coextrusion or extrusion lamination or print lamination to form a co- extruded sheet of the agricultural plastic mulch film.
  • the co-extrusion process is a blown film process or a cast film process.
  • the co-extruded sheet comprises three or more alternate layers of the at least one oxo-biodegradable polymer layer and the at least one hydro- biodegradable polymer layer.
  • the co-ext ided sheet has an overall density that is less than the density of the at least one hydro-biodegradable polymer layer.
  • the at least one oxo-biodegradable polymer layer comprises from about 5% to about 40% of the total film thickness.
  • the at least one hydro-biodegradable polymer layer comprises from about 20% to about 90% of the total film thickness.
  • the co-extruded sheet is thinned according to the process of machine direction orientation ⁇ MDO) by stretching the film in a generally lengthwise machine direction.
  • a composite agricultural plastic mulch film comprising at least two agricultural plastic mulch films according to the first aspect bonded together during a process of co- extrusion, extrusion lamination or print lamination to form a single coextruded sheet of the composite agricultural plastic mulch film.
  • the at least two agricultural plastic mulch films are bonded together via contact between either one outer oxo-biodegradable polymer layer from each film or between one outer hydro-biodegradable polymer layer from each film.
  • the contacted outer oxo-biodegradable layers or outer hydro-biodegradable polymer layers of the two films form a single corresponding oxo- biodegradable polymer layer or hydro-biodegradable polymer layer on bonding.
  • the at least two agricultural plastic mulch films are bonded together by virtue of the inherent tackiness of the respective at least one oxo- biodegradable polymer layers located at the interface between the at least two agricultural plastic mulch films.
  • the at least two agriculturaS plastic mulch films are bonded together using an adhesive.
  • the adhesive is an additive blended into the polymer of at least one of the at least two agricultural piastic mulch films that migrates to the interface between the at least two agricultural plastic mulch films after the process of co- extrusion, extrusion lamination or print lamination.
  • the coextruded sheet is thinned according to the process of machine direction orientation (MDO) by stretching the coextruded sheet in a generally lengthwise machine direction.
  • MDO machine direction orientation
  • a method for producing an agricultural plastic mulch film comprising the steps of;
  • a method for producing a composite agriculturaS plastic mulch film comprising the steps of:
  • each of the plurality of perforations is about 0,1 mm to about 10 mm in diameter.
  • each of the plurality of perforations is about 0.5 mm to about 5 mm in diameter.
  • the plurality of perforations are in spaced apart arrangement.
  • the plurality of perforations are spaced apart by about 1 mm to about 200 mm.
  • the plurality of perforations are spaced apart by about 5 mm to about 120 mm.
  • the plurality of perforations are elongate.
  • each of the elongate perforations is about 3 mm to about 12 mm in length.
  • the plurality of elongat perforations are spaced apart by about 5 mm to about 100 mm.
  • each of the plurality of perforations comprises a cross or star shaped configuration.
  • the method further comprises the step of:
  • the invention resides in a method of suppressing the growth of weeds in a target area including the step of locating an agricultural plastic mulch film of the first aspect or a composite agricultural plastic mu!ch film of the second aspect over the target area.
  • Figure 1 shows a cross sectional view of a three-layered agricultural plastic mulch film produced according to a preferred embodiment of the present invention
  • Figure 2 shows a cross sectional view of a five-layered composite agricultural plastic mulch film produced according to another preferred embodiment of the present invention.
  • Figure 3 shows a three-dimensional view of the five-layered composite agricultural plastic mulch film of Fig, 2 in which the individual oxo- and hydro- biodegradable polymer layers of the composite film have been peeled back at one corner to reveal the alternating oxo- and hydro-biodegradable polymer layers.
  • a preferred embodiment of the present invention resides in an agricultural plastic mulch film comprising alternating layers of an oxo-biodegradable polymer layer and a hydro-biodegradable polymer layer bonded together via a suitable process.
  • the agricultural plastic mulch film of the present invention may be produced by conventional methods used in producing multilayer films including coextrusion and extrusion lamination techniques of blown, smooth cast, or cast embossed manufacturing processes.
  • the agricultural plastic mulch film is formed by coextrusion. Melted and plasticated streams of the individual polymer layer materials are fed into a coextrusion die. While in the die, the molten polymer layers are juxtaposed and bonded to one another then emerge from the die a single coextruded sheet of agricultural plastic mulch film.
  • the alternating layers of the oxo-biodegradab!e polymer and the hydro-biodegradable polymer are bonded together by virtue of the inherent tackiness of one or both polymers and are welded together by being in contact with each other whilst in a molten state.
  • the total thickness of the agricultural plastic mulch film and the individual polymer layers contained therein may vary according to the relative extrusion output speeds of the various co-extruders and the relative speed at which the extruded sheet is drawn off from the die.
  • the preferred agricultural plastic mulch film has a total thickness up to about 0.5 mm and, more preferably, from about 0.005 mm to about 0.15 mm, or even more preferably from about 0.01 mm to about 0.05 mm, or any other thickness range contained therein.
  • each individual polymer layer may be similar or different in addition to having similar or different compositions.
  • the thickness of each polymer layer is therefore independent and may vary within the parameters set by the total thickness of the film. In any case, it will be understood that each of the individual polymer layers will have sufficient thickness and body so as to be evenly spread across the sheet
  • the coextruded sheet may be further subjected to post extrusion machine direction orientation (MDO), wherein the sheet is passed between two or more temperature controlled nip rollers each of which travels at a different rotational speed.
  • MDO post extrusion machine direction orientation
  • the coextruded sheet is stretched in a generally lengthwise machine direction, which causes the main chai molecules and much of the side branching molecules of the polymers within the coextruded sheet to be pulled taught and straightened and orientated closely to each other in a generally linear direction.
  • the sheet is drawn out to a point beyond the yield of the film and is stretched up to a point between the yield point and immediately short of the breaking point of stretch, wherein the resultant film is increased in strength with minimal yield in the machine direction but yields easily in the transverse direction.
  • the thickness and width of the original coextruded sheet are reduced, with the thickness being reduced by between 5% and 80%.
  • the MDO process thus results in a coextruded sheet in which the thickness of each of the individual polymer layers remains in relative proportion to each other and the relative thickness they were extruded in, but are drawn to be extremely thin. Moreover, the integrity of each of the individual polymer layers contained within the sheet is maintained intact.
  • One advantage of this is that the resulting agricultural plastic mulch film can be thinned while still retaining the individual properties of the polymers contained within the layers and has sufficient strength to be easily laid on the growing bed.
  • One further advantage of employing the MDO process is that the coextruded sheet may be thinned whilst retaining the breaking strength equivalent to the original thickness.
  • the inventors of the present invention have found that b employing a combination of the extrusion and MDO processes, it is possible to produce an agricultural plastic mulch film of uniform thickness as a result of the individual oxo- and hydro-biodegradable polymer layers each having a uniform thickness across the dimensions of the agricultural plastic mulch film. Moreover, the individual oxo- and hydro-biodegradable polymer layers are also thinner than could otherwise be achieved by the extrusion process alone.
  • the oxo-biodegradab!e polymer layer of the agricultural plastic mulch film comprises a polyolefin selected from the following group of polyolefin polymers including, but not iimited to: polyethylene, polypropylene, polyisobutylene, polyisoprene, and blends or copolymers thereof, metallocene-catalyzed polyolefin resins, and mixtures thereof.
  • Suitable polyethylenes include, in particular, low density polyethylene (LDPE), high density polyethylene (HOPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), metallocene linear low density polyethylene (mLLDPE), metallocene low density polyethylene (mLDPE), and blends or copolymers thereof.
  • LDPE low density polyethylene
  • HOPE high density polyethylene
  • LLDPE linear low density polyethylene
  • ULDPE ultra low density polyethylene
  • mLLDPE metallocene linear low density polyethylene
  • mLDPE metallocene low density polyethylene
  • the hydro-biodegradable polymer layer comprises a biodegradable polyester selected from the following group of polyesters including, but not iimited to: a linear afiphatic polyester, an aliphatic polyester, an aromatic-aliphatic co-polyester, and blends or copolymers thereof.
  • Suitable polyesters include, in particular, a poiyhydroxya!kanoate (PHA), polybutylene succinate (PBS), poly(buty!ene succinate adipate) (PBSA), poly (butyiene adipate-co-terephthatate) (PBAT), po!y(propylene carbonate) (PPC), either in pure form or in the form of a blend or copolymer thereof.
  • PHA poiyhydroxya!kanoate
  • PBS polybutylene succinate
  • PBSA poly(buty!ene succinate adipate)
  • PBAT poly (butyiene adipate-co-terephthatate)
  • PPC po!y(propylene carbonate)
  • the hydro-biodegradable layer comprises a biodegradable polyester blended with poly lactic acid (PLA), starch, thermoplastic starch (TPS) or other polyester poiymer.
  • PLA poly lactic acid
  • TPS thermoplastic starch
  • the oxo-biodegradable poiymer layer and/or the hydro- biodegradable poiymer layer comprise an effective amount of one or more additives selected from the group consisting of: antioxidants, stabilisers, UV absorbers, colourants, and the like.
  • the agricultural plastic mulch film comprises more than one oxo-biodegradable polymer layer and/or more than one hydro- biodegradable poiymer layer
  • each of the oxo- biodegradable polymer layers and/or each of the hydro-biodegradable polymer layers may comprise different additives, or amounts thereof, as required.
  • Colourants may be added to the oxo-biodegradable polymer layers and/or the hydro-biodegradable poiymer layers to yield coloured layers, opaque layers, or translucent layers as required.
  • Preferred colourants include black, white, red, blue, yellow, green, and orange, as well as other colours suitable for agricultural plastic mulch films.
  • the colourant comprises a pigment selected from the group consisting of carbon black, coated or uncoated titanium dioxide or coated or uncoated aluminium flakes.
  • UV stabilizers may be used to selectively extend the useful life of the agricultural plastic mulch film when it is exposed to the damaging effects of sunlight.
  • UV Inhibitors protect the film layers by interfering with the free radical decomposition of the polymer molecules. UV absorbers will convert harmful UV radiation into heat.
  • the amount of UV stabilizer concentrates used in the preferred film of the present invention may vary layer by layer such that the individual polymer layers degrade at different rates.
  • An antioxidant may be present in the oxo-biodegradab!e polymer layers and/or the hydro-biodegradable polymer layers in an effective stabilizing amount sufficient to stabilize the corresponding agricultural plastic mulch film against oxidative degradation for the useful life of the agricultural plastic mulch film.
  • the antioxidant is present in the oxo-biodegradable polymer layers and/or the hydro-biodegradable polymer layers in an effective amount of between about 0.001 and about 1 .0 weight percent, preferably between about 0.0025 and about 0.5 weight percent, based on the weight of the agricultural plastic mulch film.
  • Polymeric processing aids may also be used in a layer. Fluoropolymers, fluoropoSymer blends, and fluoroelastomers are particularly preferred, but any processing aid known in the art for use in polymer films would be suitable.
  • Prodegradants having their degradation activity activated by UV light or by an elevated thermal environment may also be used to promote accelerated photodegradation and/or thermal degradation of the corresponding oxo- biodegradable polymer layer.
  • the prodegradant may be employed by itself or used in conjunction with an enzyme to assist with the photodegradation and/or thermal degradation process.
  • Suitable prodegradants may include but are not limited to; organic salts of polyvalent transition metals such as copper, manganese, iron or cobalt.
  • the prodegradant is selected from the group consisting of manganese stearate, iron stearate and cobalt stearate.
  • the prodegradant is typically present within the oxo-biodegradable polymer layer in an effective amount of between about 0.01 weight percent and about 20.0 weight percent, more preferably between about 0.1 and about 5.0 weight percent, based on the weight of the agricultural plastic mulch film.
  • the agricultural plastic muich fiim may contain several alternating layers of the oxo-biodegradable polymer and the hydro- biodegradable polymer, each bonded to and supporting each other and adding tensile properties to the final coextruded sheet.
  • the agricultural plastic mulch fiim comprises two oxo-biodegradable polymer layers, each forming an outer layer of the agricultural plastic mulch film, and one hydro-biodegradable polymer layer disposed substantially therebetween.
  • This three layer agricultural plastic mulch film is referred to hereon in as an OHO-type film.
  • the outer oxo-biodegradable polymer layers of the OHO-type film will prevent water from reaching the inner hydro-biodegradable polymer layer until such time as the outer oxo-biodegradable pofymer layers have degraded and cracked to allow the ingress of water and microbes.
  • the hydro-biodegradable polymer layer of the OHO-type film is not water soluble because as the outer oxo-biodegradable polymer layers degrade, water is allowed to ingress into the inner hydro-biodegradable polymer layer. Should the inner hydro-biodegradable poiymer layer be water soluble, then any ingressed water will quickly spread throughout the hydro-biodegradable polymer layer causing it to become quickly dissolved and/or hydrolysed and the tensile properties of the hydro-biodegradable polymer forming the layer substantially reduced. This will severely reduce the tensile properties of the coextruded sheet and negate the ability of the agricultural plastic mulch film to perform its required function.
  • the inner hydro- biodegradable polymer layer is ideally comprised of a polymer that will not dissolve in the presence of water and microbes, but will degrade by hydrolysis and only do so in the area where the moisture and microbes are in contact with the hydro- biodegradable polymer layer.
  • the inner hydro-biodegradable polymer layer is aiso ideally comprised of a polymer that does not have too low a softening point such that it would meit under hot conditions, in this respect, the hydro-biodegradable poiymer iayer preferably excludes such water soluble and low melting polymers as poly vinyl alcohol (PVOH), polycaprolactone (PCL), and any modified forms or biends thereof.
  • the inner hydro-biodegradable polymer Iayer comprises a polyester, preferably a synthetic polyester.
  • the inner hydro-biodegradable poiymer layer of the OHO-type film is comprised of an aromatic or aromatic/aliphatic polyester such as PBAT or PLA or PHA or PHB or PBSA or similar
  • any part of the OHO-type film which is buried underground degrades by being assimilated by microbes resulting in holes being formed in the OHO-type film.
  • the OHO-type film retains a substantia! strength enabling it to remain in contact with the ground.
  • the two outer oxo-biodegradable polymer layers of the OHO-type film each comprise a mixture of mLLDPE and LDPE, and the inner hydro-biodegradable polymer layer comprises PBAT.
  • the two outer oxo- biodegradable polymer layers of the OHO-typ film each comprise a mixture of LLDPE and LDPE, and the inner hydro-biodegradable polymer layer comprises PBAT.
  • the agricultural plastic mulch film is of an OHO-type configuration having a total thickness of 0.013 mm.
  • the thickness of each separate oxo-biodegradabie polymer layer is preferably about 0.00325 mm and the thickness of the hydro-biodegradable polymer Iayer is preferably aboutO.0065 mm.
  • the agricultural plastic mulch film comprises two hydro-biodegradable polymer layers, each forming an outer Iayer of the agricultural plastic mulch film and one oxo-biodegradable polymer iayer disposed therebetween.
  • This three iayer agricultural plastic mulch film is referred to hereon in as an HOH-type film.
  • the outer hydro-biodegradable polymer layers of the HOH-type film have oxygen barrier properties and as such will protect the inner oxo-biodegradable polymer Iayer from oxidation until the two outer hydro-biodegradable polymer layers have degraded. Once the faster biodegradable hydro-biodegradable polymer layers have disintegrated, all of the polymer layers will be delaminated and the agricultural plastic mulch film will lose the additional tensile properties achieved by all of the polymer layers being bonded together.
  • the hydro-biodegradable polymer layers have oxygen barrier properties and as such will protect the inner oxo-biodegradable polymer Iayer from oxidation until such time as the hydro-biodegradable polymer layers have degraded.
  • all the polymer layers will become delaminated such that the Goextruded sheet loses the additional tensile properties achieved by the polymer layers being bonded together.
  • the two hydro-biodegradab!e polymer layers of the HOH-type film may contain UV light stabilizers or absorbers which, combined with the oxygen barrier properties of the hydro-biodegradable polymer layer, will delay the onset of the oxidative degradation of the inner oxo-biodegradable polymer layer.
  • the oxo-biodegradable polymer layer provides a solid backing sheet which holds the entire agricultural plastic mulch film intact even though the hydro- biodegradable polymer layers have been hydroiysed and biodegradation has commenced.
  • the agricultural plastic mulch film of the present invention is not limited to the three-iayered OHO-type and HOH-type films described above, but may comprise four or more alternating layers of the oxo-biodegradable polymer and the hydro-biodegradable polymer, more preferably, five or more alternating layers, with a greater preference for agricultural plastic mulch films in which the outer layers are formed from oxo-biodegradable polymers.
  • FIG. 1 there is shown a cross sectional view of an agricultural plastic mulch film 10 in the form of a single co-extruded sheet comprising the three-layered OHO-type configuration.
  • the film 10 consists of a top layer 20 comprised of an oxo-biodegradable polymer layer, an intermediate layer 30 comprised of a hydro-biodegradable polymer, and a !ower layer 40 comprised of the same oxo-biodegradable polymer.
  • the three layers may each be of the same thickness, or of a different thickness depending on the polymers chosen and/or the application.
  • the three-layered agricultural plastic mulch film 10 shown in Fig. 1 may have the HOH-type configuration.
  • a three-layered OHO-type agricultural plastic mulch film was manufactured with outer oxo-biodegradable layers comprising a blend of polyethylene and carbon black masterbatch and including a prodegradant masierbatch, and an inner hydro-biodegradable layer comprising a biend of aromatic/aliphatic polyester PBAT black masterbatch and a commercially available UV stabilizer.
  • the thickness of the resulting OHO-type agricultural plastic mulch film was 18 microns, in which the two outer oxo-biodegradable polymer layers were 5 microns in thickness each, and the inner hydro-biodegradable polymer layer was 8 microns in thickness.
  • a three-layered OHO-type agricultural plastic mulch film was manufactured with outer oxo-biodegradable layers comprising a blend of polyethylene and carbon black masterbatch and including a prodegradant masterbatch and an inner hydro-biodegradable layer comprising a blend of aromatic aliphatic polyester PBAT black masterbatch and a commercially available UV stabilizer.
  • the thickness of the resulting OHO-type agricultural plastic mulch film was 18 microns, in which the two outer oxo-biodegradable polymer layers were 5 microns in thickness each, and the inner hydro-biodegradable polymer layer was 8 microns in thickness.
  • the OHO-type agricultural plastic mulch film was subjected to a number of trials in which pieces of the mulch film were placed vertically into a compost environment consisting of an enclosure designed for home compost having side vents to allow air circulation and a lid to prevent the ingress of additional water.
  • the enclosure was filled with mature potting soil and mature composted cattle and sheep manure and placed outdoors where a maximum temperature of 25 degrees centigrade was experienced and kept moist.
  • the holes formed in the extruded sheet assist with the disintegration of the outer oxo-biodegradable polymer layers as they are oxidized.
  • the inner hydro-biodegradable polymer layer of the OHO-type agricultural plastic mulch film had been substantially assimilated by microbes such that when the mulch film was pulled, small pieces would break off in the hand as the mulch film tore between holes. This action would certainly help reduce the detrimental environmental effect the mulch film would have on the soil.
  • a composite agricultural plastic mulch film comprising at least two of the agricultural plastic mulch films described above bonded together during a process of extrusion, extrusion lamination or print lamination to produce the composite agricultural plastic mulch film in the form of a single coextruded sheet.
  • the two agricultural plastic mulch films used in the formation of the composite agricultural plastic mulch film are of the OHO-type, bonded together by virtue of the inherent tackiness of the corresponding outer oxo- biodegradable polymer layers located at the interface formed between the two agricultural plastic mulch films.
  • the two bonded oxo-biodegradable polymer layers can be thought of, In terms of its practical functioning, as being a single oxo- biodegradable polymer layer.
  • the resulting five-iayered composite agricultural plastic mulch film (or six layered if the two central adhered oxo-biodegradable layers are counted individually) thus comprises a single oxo-biodegradable polymer layer disposed substantially between two hydro-biodegradable poiymer layers in an HOH- type arrangement, with a further oxo-biodegradable polymer layer disposed on either side as the outer layers of the composite agricultural plastic mulch film.
  • This five- layered composite agricultural plastic mulch film of alternating oxo-biodegradable poiymer layers and hydro-biodegradable polymer layers is referred to hereon in as an OHOHO-type film.
  • the bonding between the corresponding outer oxo-biodegradable polymer layers of the two agricultural plastic mulch films is not limited to the inherent tackiness of the two layers to effect bonding, but may rely on the use of an adhesive to bond the two layers together.
  • the adhesive may be introduced as an additive into the poiymer mix used for forming the outer oxo-biodegradable polymer layer of at least one of the two agricultural plastic mulch films.
  • the heat associated with the process causes the adhesive to migrate to the surface of the outer oxo-biodegradable poiymer layer.
  • the adhesive is presented at the interface between the two agricultural plastic mulch films for use in bonding the two OHO-type agricultural plastic mulch films together.
  • the adhesive may simply be applied to the surface of the outer polymer layer of at least one of the two OHO-type agricultural plastic mulch films to be used in the formation of the composite agricultural plastic mulch film to act as a tie-layer for bonding the two OHO-type agricultural plastic mulch films together.
  • Suitable adhesives for use as the tie-layer may include, but are not limited to: a high tack, low molecular weight adhesive polymer such as an oxo- biodegradable polyolefin, a vinyl poiymer such as ethyl vinyl acetate (EVA), or a polyester polymer such as poly isobutylene (PIB), or modified forms thereof.
  • a high tack, low molecular weight adhesive polymer such as an oxo- biodegradable polyolefin, a vinyl poiymer such as ethyl vinyl acetate (EVA), or a polyester polymer such as poly isobutylene (PIB), or modified forms thereof.
  • the OHOHO-type composite agricultural plastic mulch film is produced by the three-layer co-extrusion blown film process, wherein an outer oxo-biodegradable polymer layer of one or both of the two OHO- type agricultural plastic mulch films may, in addition to comprising a prodegradant, also contain one or more other additives, including antioxidants, UV stabilizers and/or colourants.
  • the hydro-biodegradable polymer layer of one or both of the two OHO- type agricultural plastic mulch films may be comprised of a single hydro- biodegradable polymer or a blend of different hydro-biodegradable polymers, and. ma also contain one or more additives including colourants, UV absorbers, antioxidant additives, and/or UV light stabilizers.
  • the remaining oxo-biodegradable polymer layer of each of the two OHQ- type agriculturai plastic mulch films that combine during the co-extrusion blown film process to form the eventual single inner oxo-biodegradable polymer layer of the OHOHO-type composite agriculturai plastic mulch film may each contain a different loading of prodegradant, antioxidant, UV stabilizers and/or colourants from that of the other layer, or indeed, different from that of the oxo-biodegradable polymer layers forming the eventual outer layers of the OHOHO-type composite agricultura! plastic mulch film.
  • one or both of these two remaining oxo- biodegradable polymer layers may be manufactured from a high-tack, low molecular weight polymer or may contain sufficient poly isobutylene (P!B) as an additive in order to bond the two layers together.
  • P!B poly isobutylene
  • These additives or polymers will ensure that once the extruded bubble has passed through the top draw-off nip rollers in the extrusion process, the film will be blocked and both collapsed sides of the resulting OHOHO-type composite agricultural plastic mulch film will be laminated to form a single coextruded sheet
  • the thickness of the various layers of the OHOHO-type composite agricultural plastic mulch film may be different from each other.
  • the combined oxo-biodegradable polymer layers forming the inner oxo- biodegradable polymer layer of the OHOHO-type composite agricultural plastic mulch film may be much thinner than the outer oxo-biodegradable polymer layers.
  • this five-layered OHOHO-type composite agricultural plastic mulch film may be manufactured by the coextruded blown film process or by the coextruded cast film process as a single coextruded sheet from five separate and bonded alternating layers of oxo-biodegradable polymer and hydro- biodegradable polymer directly from the extrusion die.
  • this five-layered OHOHO-type composite agricultural plastic mulch film may be manufactured by the coextruded blown film process or by the coextruded cast film process as a single coextruded sheet from three separate oxo-biodegradable polymer layers bonded together using tie layers comprised of adhesive polymer so as to bond the inner oxo-biodegradable polymer and the two outer oxo-biodegradable polymer layers together in a manner which makes it extremely difficult to delaminate each layer.
  • the tie- layer in this arrangement is a high tack hydro-biodegradable polymer. This will result in well bonded and laminated alternating layers of oxo-biodegradable polymer and hydro- biodegradable polymer directly from the extrusion die,
  • FIG. 2 there is shown a cross sectional view of a composite agricultural plastic mulch film 100 in the form of a single laminated sheet of the five-layered OHOHO-type configuration.
  • the five-layered composite film 100 is formed as a result of two three-layered co-extruded sheets of the OHG-type agricultural plastic mulch film 10 (designated as film 10A and film 10B in Fig. 2), being laminated together in the presence of a suitable adhesive 50, such as poiyisobutyiene (PIB), to form the OHOOHO"-type co-extruded sheet, and then may be further subjected to the MDO process to form the eventual OHOHO-type configuration.
  • a suitable adhesive 50 such as poiyisobutyiene (PIB)
  • the inner facing oxo-biodegradable polymer layers 40A, 40B of the corresponding two agricultural mulch films 10A, 10B combine during the lamination process to form a single oxo-biodegradable polymer layer 40AB.
  • On either side of the central single oxo-biodegradable polymer layer 40AB is an intermediate hydro-biodegradable polymer layer 30A and 30B, with an outer oxo-biodegradable polymer layer 20A and 20B, respectively, laminated on top of that
  • FIG. 3 there is shown a three-dimensional view of the five-layered composite agricultural mulch film 100 in which the individual oxo- and hydro-biodegradable polymers layers of the composite film 100 have been peeled back at one corner of the composite film 100.
  • the five layers of the composite film 100 may each be of the same thickness, or of a different thickness depending on the polymers chosen and/or the application. It will also be appreciated that the five-layered composite film 100 shown in Figs. 2 and 3 may also have the HOHOH-type configuration.
  • HOHOH-type film [00161] By using this same method described above, it wilt be appreciated that a five-layered HOHOH-type composite agricultural plastic mulch film may also be manufactured as a single coextruded sheet from three separate hydro-biodegradable polymer layers bonded together using tie layers comprised of an oxo-biodegradable polyolefin.
  • th agricultural plastic mulch film is manufactured so that it comprises a plurality of perforations in one or more of the outer polymer layers or perforated through the entire thickness of the sheet.
  • Such perforations will allow the ingress of water to, and accelerate the degradation of, any hydro-biodegradable polymer layers located within the mulch film, thus accelerating the delamination and consequent degradation of the oxo- biodegradable polymer layers.
  • Inner oxo-biodegradable polymer layers will also degrade faster because additional oxygen will be available to these layers after delamination.
  • the reduced bonding strength between the oxo- biodegradable polymer layers and the hydro-biodegradable polymer layers will allow greater surface area to be made available for microbial attack of the oxo- biodegradable polymer layers.
  • the perforations may be of any size and shape and in any number in the film. The perforations can be in various directions and designs.
  • each of the perforations is about 0.1 mm to about 10 mm in diameter, more preferably about 0.5 mm to about 5 mm in diameter, and optimally about 1 mm to about 2 mm in diameter.
  • the perforations are ideal!y distributed across ail or part of the coextruded sheet in spaced apart arrangement.
  • the perforations are spaced apart by about 1 mm to about 200 mm, more preferably by about 5 mm to about 120 mm, and optimally by about 10 mm to about 100 mm.
  • perforations may be produced by various mechanisms including, but not limited to: mechanical drilling/punching, burning with pins into the films, piercing the film with sharp pins, laser burning, and the like.
  • the perforations in the coextruded sheet may comprise short slits of between 3 mm and 12 mm in length, and spaced apart from each other by between 5 mm and 100 mm.
  • the perforations may comprise slits having a cross- or star-shaped configuration.
  • the agricultural plastic mulch film is manufactured so that some or all of the alternating oxo-biodegradable polymer and hydro-biodegradable polymer layers of the mulch film incorporate a percentage of filler as an additive to aid micropore formation in the agricultural plastic mulch film when it is stretched. This inclusion allows airflow through the coextruded sheet and is commonly used in items such a breathable nappies and climate controlled packaging.
  • the filler may be an inorganic material or an organic material.
  • the filler is provided in the form of finely ground inorganic particles in masterbatch form.
  • the filler particles should have a mean particle diameter of about 0.1 to about 10 microns, more preferably, from about 0.5 to about 5.0 microns, and optimally from about 1.5 to about 3 microns.
  • Suitable filler materials may include, but are not limited to: calcium carbonate, kaolin, talc or clay. These filler particles may be provided in their natural form or coated to aid their dispersion in the oxo-biodegradable polymer or hydro- biodegradable polymer prior to forming the polymer layer.
  • the filler is an organic material selected from the group consisting of starch, polymerised starch and thermoplastic starch (TPS).
  • TPS thermoplastic starch
  • the inventors have found that under normal co-extrusion conditions that do not employ a tie layer, the bond formed between the oxo-biodegradabSe polymer layer and the hydro-biodegradable polymer layer of a single coextruded sheet of agricultural plastic mulch film will not withstand delamination by being pulled apart at the edge of the sheet using adhesive packing tape attached to either side of the sheet, This low level of lamination adhesion is advantageous as it allows for the polymer layers to be easily de!aminated as they are degraded.
  • a further advantage of manufacturing mulch film by means of a co- extrusion process having alternating layers of oxo-biodegradable polyoiefin and hydro-biodegradable polymer is that the overall density of the resulting coextruded sheet is reduced from that of the pure hydropoiymer blend alone.
  • polyoiefin poiymers such as polyethylene and polypropylene have a density of betwee 0.87 and 0.95 g/cm 3
  • polyester which is the most commonly used hydro-biodegradable polymer, has a density of 1.18 to 1.25 g/cm 3 .
  • the average density of the coextruded sheet can be reduced to around 1.03 g/cm 3 depending on the thickness of the various polyme layers.
  • This reduction in density means substantially less polymer, by weight, is needed than with hydro-biodegradable polymers alone. This also has cost implications in that all polymers are sold by weight and a less dense polymer will allow a greater area of mulch film to be made with a particular weight of polymer.
  • the mulch film it is often desired for the mulch film to be made thin in order to reduce the amount of polymer used in order to reduce the cost of the product and the environmental impact of the plastic. Even though the mulch film is thin, there is a desire that it retain substantial mechanical properties in order to allow it to be laid by mechanical means.
  • a three-layered OHO-type blown film bubble has a wall thickness of 20 microns (that is, a total of 40 microns, when collapsed into a lay- flat tube). The walls of the lay-flat tube are then bonded together by extrusion lamination to afford a five-layered OHOHO-type composite agricuitura! film.
  • the outer oxo-biodegradable polymer layer of the wall of the lay tube is 10 microns in thickness
  • the inner hydro-biodegradable polymer layer is 5 microns in thickness
  • the inner oxo-biodegradable pofymer layer of the wall of the lay tube is 5 microns in thickness.
  • the resulting five-layered OHOHO-type composite agricultural plastic mulch film has two outer oxo-biodegradable polymer layers of 10 microns each, an inner blocked and laminated oxo-biodegradable polymer layer of 10 micron (that is, two 5 micron layers laminated together) and two intermediate hydro- biodegradable polymer layers of 5 microns each.
  • the two outer oxo-biodegradable polymer layers of the OHOHO-type composite agricultural plastic mulch film have a thickness of 3 microns each
  • the inner oxo- biodegradable polymer layer has a thickness of 3 microns (that is, two 1.5 micron layers laminated together), and two intermediate hydro-biodegradable polymer layers of 1.5 microns.
  • the overall thickness of the MDO processed OHOHO-type plastic composite agricultural plastic mulch film is 9 microns, but due to the molecular orientation when a load is applied in the machine direction, such as when the sheet is pulled tight by being laid as mulch film, it will have tensile properties, that is, a breaking strength, almost equivalent to a 40 micron thick sheet.
  • the MDO plastic sheet has reduced tensile properties in the transverse direction. This enables the sheet to be easily stretched in the transverse direction allowing it to be stretched over rough soil without holes being formed, while retaining tensile strength and low elongation in the machine direction.
  • the individual oxo-biodegradab!e and hydro- biodegradable polymer layers of the agricultural plastic mulch film envisaged in the preferred embodiments of the present invention will each be made very thin (between 0.5 and 8 microns). Once delamination has occurred, these individual layers of up to 8 microns will not easily resist degradation.
  • a further advantage of this method of manufacturing the agricultural plastic mulch film is that the hydro-biodegradable polymer layers, by being subject to MDO, increase their resistance to oxygen permeation as the molecules of the polymer are straightened and oriented closely to each other, reducing the possibility of oxygen molecules passing through the MDO processed hydro-biodegradable polymer layer. This reduced oxygen transmission assists with maintaining the integrity of any inner layers of oxo-bsodegradable polymer, maintaining the completeness of the sheet as the hydro-biodegradable polymer is degraded.
  • the orientation of the oxo-biodegradable polymer molecules reduces the number of nibs and gels which can prove difficult to oxidize when in a tight gel formation.
  • the reduced transverse molecular orientation of these layers also assists with accelerating the embrittlement of the plastic sheet by oxidative molecular scission.
  • an OHO-type agricultural plastic mulch film is extruded as a relatively thick sheet, preferably having a total thickness of 0.0275 mm.
  • the resultant co-extruded sheet will having an OHOOHO"-type configuration with a combined thickness of 0.055 mm.
  • the inner facing oxo-biodegradabie polymer layers of the two OHO-type sheets are combined in the presence of an adhesive to form the central ⁇ " oxo-biodegradabie polymer layer of the OHOOHQ"-type co-extruded sheet, having a combined thickness of 0.005 mm
  • the two intermediate hydro-biodegradable polymer layers located either side of the central "OO * oxo-biodegradabie polymer layer are each extruded at 0.015 mm in thickness
  • the two outer oxo-biodegradabie polymer layers are each extruded at 0,0075 mm in thickness.
  • the resultant composite agricultural plastic mulch film will have an OHOHO-type configuration in which the central "GO" oxo-biodegradabie polymer layer will form a single laminated oxo-biodegradabie polymer layer having a total thickness of 0.002 mm (that is, two individual oxo-biodegradabie polymer layers of 0.001 mm thickness being laminated into a single layer of 0.002 mm thickness), the two intermediate hydro-biodegradabl poiymer layers either side of the central laminated oxo-biodegradabie polymer layer wit! each be of 0.003 mm in thickness, and the two outer hydro-biodegradable poiymer layers will be of 0.0015 mm in thickness, affording the composite agricultural plastic mulch film with a total thickness of 0.0 1 mm.
  • UV stabilizer 111 stabilizer 0.8 1 1 1
  • the above table provides typical material blends used in each oxo- biodegradable polyme layer (O) and hydra-biodegradable polymer layer (H) of a three-layered OHO-type agricultural plastic muich film manufactured by the extrusion blown film process, and the corresponding five-layered OHOHO-type composite agricultural plastic mulch film produced by laminating the walls of the corresponding lay flat tube into a single sheet when passing through the extrusion haul off nip rollers.
  • This Iaminated sheet is then subjected to machine direction orientation (1V1DO) by being stretched by a ratio of 1 to 4, reducing the film's width and thickness and increasing its length.
  • alternating is employed herein to refer to alternating layers of oxo-biodegradabl polymer and hydro-biodegradable polymer in the agricultural plastic mulch films.
  • the two oxo- biodegradable polymer layers or two hydro-biodegradable layers that are bonded together at the interface between the Iaminated agricultural plastic mulch films function as a single oxo-biodegradable polymer layer or a single hydro-biodegradabie iayer such that the composite agricultural plastic mulch fiim comprises "alternating" layers of cxo-biodegradable polymer and hydro-biodegradable polymer.
  • photodegradable as used herein is meant to denote a polymeric material characterized by susceptibility to ultraviolet (UV) light initiated oxidative chain scission reactions resulting in molecular weight reduction, (preferably substantialiy complete loss) of tensile strength, and embrittlement to the extent that mechanical stresses, such as those arising from wind or rain break the polymeric material into smaller fragments,
  • thermodegradabie as used herein is meant to denote a thermoplastic material characterized by a susceptibility to the scissioning of main chain chemical bonds as a result of overcoming bond dissociation energies under the influence of moderately elevated temperature e.g., such as heating at temperatures above room temperature.
  • moderately elevated temperature e.g., such as heating at temperatures above room temperature.
  • the results of thermal degradation include changes in the physical and chemical properties of the thermoplastic material, such as molecular weight reduction, loss of tensile strength, and embrittlement, to the extent that mechanical stress (such as that encountered when an article made from the thermoplastic material is treated in such a heated environment, buried, and tilled in soil or compost) break the article into minute fragments.
  • biodegradable is used herein to denote a material characterized by susceptibility to attack from living organisms which are capable of producing enzymes or pH changes that hydroiyze chemical bonds present in the materia! to form specific decomposition products that can be utilized by the attacking organisms or by other organisms for energy production or synthesis of new compounds.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Laminated Bodies (AREA)

Abstract

L'invention concerne un film plastique formant mulch agricole, comprenant des couches en alternance, à savoir au moins une couche polymère oxobiodégradable et au moins une couche polymère hydrobiodégradable, ledit film plastique formant mulch agricole s'avérant offrir des avantages d'utilisation particuliers en termes de temps de dégradation utile et contrôlable et de dégradation totale appropriée de manière à réduire la nécessité de ramassage du film au terme de sa durée de vie utile.
PCT/AU2014/000934 2013-09-25 2014-09-24 Film plastique formant mulch agricole et sa composite WO2015042641A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2013903693 2013-09-25
AU2013903693A AU2013903693A0 (en) 2013-09-25 A biodegradable oriented plastic agricultural mulch

Publications (1)

Publication Number Publication Date
WO2015042641A1 true WO2015042641A1 (fr) 2015-04-02

Family

ID=52741628

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2014/000934 WO2015042641A1 (fr) 2013-09-25 2014-09-24 Film plastique formant mulch agricole et sa composite

Country Status (1)

Country Link
WO (1) WO2015042641A1 (fr)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106977898A (zh) * 2017-05-25 2017-07-25 中国科学院长春应用化学研究所 一种黑色母料、其制备方法及黑色地膜
CN108276792A (zh) * 2018-01-29 2018-07-13 甘肃华瑞农业股份有限公司 一种含牛粪的可降解保温地膜及其制造方法
CN109320833A (zh) * 2018-11-02 2019-02-12 廖荣金 一种可降解地膜及制备方法
CN109354747A (zh) * 2018-11-02 2019-02-19 廖荣金 一种可降解薄膜及制备方法
CN109367172A (zh) * 2018-08-09 2019-02-22 束建军 一种生物基全降解抗菌保鲜袋及其制备方法
CN110227282A (zh) * 2019-07-09 2019-09-13 浙江工业大学 一种废旧农用聚乙烯地膜在吸附疏水性有机污染物中的应用
WO2020072590A1 (fr) * 2018-10-03 2020-04-09 Swm Luxembourg Sarl Compositions de mélange polymère et filet extrudé dégradable fabriqué à partir de celles-ci
US10675845B2 (en) * 2014-10-27 2020-06-09 Tipa Corp. Ltd. Biodegradable sheets
WO2020252233A1 (fr) * 2019-06-13 2020-12-17 Delstar Technologies, Inc. Filet extrudé dégradable réalisé à partir de compositions de mélange de polymères
CN112568040A (zh) * 2020-12-10 2021-03-30 李军安 一种利于农作物果实生长的地膜
CN112586246A (zh) * 2020-11-06 2021-04-02 陕西富隆新塑材有限公司 一种全回收-全降解复合型地膜及其制备方法
CN114149667A (zh) * 2021-12-30 2022-03-08 江苏华盛材料科技集团有限公司 棉花专用高耐候生物降解地膜
CN114340889A (zh) * 2019-09-13 2022-04-12 普朗蒂克科技有限公司 多层结构体、其制备方法及包装容器
JP7056036B2 (ja) 2017-08-24 2022-04-19 三菱ケミカル株式会社 植物保護資材および植物保護資材用樹脂組成物
CN114685949A (zh) * 2020-12-28 2022-07-01 上海昶法新材料有限公司 生物降解材料、其原料组合物及其制备方法和应用
CN115386093A (zh) * 2022-09-15 2022-11-25 佛山(华南)新材料研究院 一种降解塑料材料的制备方法
KR102479768B1 (ko) * 2022-09-02 2022-12-22 주식회사 큐앤아이 바이오매스 기반 친환경 롤백 및 이의 제조 방법
CN116180294A (zh) * 2023-03-01 2023-05-30 海宁天福经编涂层有限公司 一种可降解服装面料的制作方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5108807A (en) * 1990-03-14 1992-04-28 First Brands Corporation Degradable multilayer thermoplastic articles
US20010014383A1 (en) * 2000-01-26 2001-08-16 Bernard Debaux Mulch sheet and method of manufacturing the same
WO2001093678A2 (fr) * 2000-06-09 2001-12-13 The Procter & Gamble Company Articles agricoles et procedes agricoles comprenant des copolymeres biodegradables
WO2003035753A1 (fr) * 2001-10-19 2003-05-01 The Procter & Gamble Company Compositions de copolymeres de polyhydroxyalcanoate et d'amidon destinees a des stratifies et des films
US7662463B2 (en) * 2006-08-18 2010-02-16 Pliant Corporation Agricultural barrier films having superior tear strength properties
WO2012067471A2 (fr) * 2010-11-19 2012-05-24 Skc Co., Ltd. Film multicouche écologique
JP2012148507A (ja) * 2011-01-20 2012-08-09 Japan Polyethylene Corp 農業用積層フィルム

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5108807A (en) * 1990-03-14 1992-04-28 First Brands Corporation Degradable multilayer thermoplastic articles
US20010014383A1 (en) * 2000-01-26 2001-08-16 Bernard Debaux Mulch sheet and method of manufacturing the same
WO2001093678A2 (fr) * 2000-06-09 2001-12-13 The Procter & Gamble Company Articles agricoles et procedes agricoles comprenant des copolymeres biodegradables
WO2003035753A1 (fr) * 2001-10-19 2003-05-01 The Procter & Gamble Company Compositions de copolymeres de polyhydroxyalcanoate et d'amidon destinees a des stratifies et des films
US7662463B2 (en) * 2006-08-18 2010-02-16 Pliant Corporation Agricultural barrier films having superior tear strength properties
WO2012067471A2 (fr) * 2010-11-19 2012-05-24 Skc Co., Ltd. Film multicouche écologique
JP2012148507A (ja) * 2011-01-20 2012-08-09 Japan Polyethylene Corp 農業用積層フィルム

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10675845B2 (en) * 2014-10-27 2020-06-09 Tipa Corp. Ltd. Biodegradable sheets
CN106977898A (zh) * 2017-05-25 2017-07-25 中国科学院长春应用化学研究所 一种黑色母料、其制备方法及黑色地膜
JP7056036B2 (ja) 2017-08-24 2022-04-19 三菱ケミカル株式会社 植物保護資材および植物保護資材用樹脂組成物
CN108276792A (zh) * 2018-01-29 2018-07-13 甘肃华瑞农业股份有限公司 一种含牛粪的可降解保温地膜及其制造方法
CN109367172A (zh) * 2018-08-09 2019-02-22 束建军 一种生物基全降解抗菌保鲜袋及其制备方法
CN112771121A (zh) * 2018-10-03 2021-05-07 斯瓦蒙卢森堡有限责任公司 聚合物共混物组合物以及由其制成的可降解挤出网
WO2020072590A1 (fr) * 2018-10-03 2020-04-09 Swm Luxembourg Sarl Compositions de mélange polymère et filet extrudé dégradable fabriqué à partir de celles-ci
CN109354747A (zh) * 2018-11-02 2019-02-19 廖荣金 一种可降解薄膜及制备方法
CN109320833A (zh) * 2018-11-02 2019-02-12 廖荣金 一种可降解地膜及制备方法
WO2020252233A1 (fr) * 2019-06-13 2020-12-17 Delstar Technologies, Inc. Filet extrudé dégradable réalisé à partir de compositions de mélange de polymères
CN110227282A (zh) * 2019-07-09 2019-09-13 浙江工业大学 一种废旧农用聚乙烯地膜在吸附疏水性有机污染物中的应用
EP4043207A4 (fr) * 2019-09-13 2023-11-01 Plantic Technologies LTD Structure multicouche, son procédé de production et contenant d'emballage
CN114340889A (zh) * 2019-09-13 2022-04-12 普朗蒂克科技有限公司 多层结构体、其制备方法及包装容器
CN112586246A (zh) * 2020-11-06 2021-04-02 陕西富隆新塑材有限公司 一种全回收-全降解复合型地膜及其制备方法
CN112568040A (zh) * 2020-12-10 2021-03-30 李军安 一种利于农作物果实生长的地膜
CN114685949A (zh) * 2020-12-28 2022-07-01 上海昶法新材料有限公司 生物降解材料、其原料组合物及其制备方法和应用
WO2022142240A1 (fr) * 2020-12-28 2022-07-07 上海昶法新材料有限公司 Matériau biodégradable, sa composition en matières premières, son procédé de préparation et son utilisation
CN114149667A (zh) * 2021-12-30 2022-03-08 江苏华盛材料科技集团有限公司 棉花专用高耐候生物降解地膜
KR102479768B1 (ko) * 2022-09-02 2022-12-22 주식회사 큐앤아이 바이오매스 기반 친환경 롤백 및 이의 제조 방법
CN115386093A (zh) * 2022-09-15 2022-11-25 佛山(华南)新材料研究院 一种降解塑料材料的制备方法
CN115386093B (zh) * 2022-09-15 2023-08-22 佛山清粤新材料科技有限公司 一种降解塑料材料的制备方法
CN116180294A (zh) * 2023-03-01 2023-05-30 海宁天福经编涂层有限公司 一种可降解服装面料的制作方法

Similar Documents

Publication Publication Date Title
WO2015042641A1 (fr) Film plastique formant mulch agricole et sa composite
US5849374A (en) Compostable multilayer structures, methods for manufacture, and articles prepared therefrom
KR102058392B1 (ko) 생분해성 필름의 제조방법 및 이로부터 제조된 멀칭 필름
US5849401A (en) Compostable multilayer structures, methods for manufacture, and articles prepared therefrom
US5540962A (en) Degradable package for containment of liquids
JP6239025B2 (ja) 膨張された温室の覆い用の分離可能層を有する多層プラスチックフィルム
US7132490B2 (en) Lactic acid-based resin composition
US6625923B2 (en) Biodegradable paper-based agricultural substrate
WO2007027163A2 (fr) Film en polypropylène biorienté dégradable et/ou biodégradable
WO1999063001A1 (fr) Composition de resine de polyester biodegradable, composition de resine biodesintegrable et objets moules que ces compositions permettent de fabriquer
EP2882586B1 (fr) Film de matière plastique multi-couches comprenant des couches séparables pour la couverture d'une serre gonflée
BRPI0709982B1 (pt) Película de embalagem, seu método de fabricação e elemento de embalagem para gêneros alimentícios
WO2014209602A1 (fr) Emballage en film mousse
EP2658906B1 (fr) Feuille moussante écologique
US6401390B1 (en) Multilayer biodegradable mulch and methods for preparing and using the same
US20060280923A1 (en) Controlled multilayer degradable film
KR102480157B1 (ko) 차단 포장용 적층 구조체
JP2003305817A (ja) 多層フィルムまたはシート
KR101352952B1 (ko) 농업용 반사필름 및 그 제조방법
CN110272551A (zh) 一种聚乳酸薄膜及其制备方法
JP7274491B2 (ja) 生体適合性バリア包装のための積層構造体
JP2005193620A (ja) 共押出多層生分解性シュリンクフィルム
WO2013008551A1 (fr) Emballage comprenant un matériau d'emballage et un produit biodégradable destiné à l'agriculture et à la sylviculture
JP2001088865A (ja) 新聞紙包装材

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 14848974

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 14848974

Country of ref document: EP

Kind code of ref document: A1