CA2251715C - Uv resistant plastic film or coating used for climate protection - Google Patents
Uv resistant plastic film or coating used for climate protection Download PDFInfo
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- CA2251715C CA2251715C CA002251715A CA2251715A CA2251715C CA 2251715 C CA2251715 C CA 2251715C CA 002251715 A CA002251715 A CA 002251715A CA 2251715 A CA2251715 A CA 2251715A CA 2251715 C CA2251715 C CA 2251715C
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- 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
- A01G9/00—Cultivation in receptacles, forcing-frames or greenhouses; Edging for beds, lawn or the like
- A01G9/14—Greenhouses
- A01G9/1438—Covering materials therefor; Materials for protective coverings used for soil and plants, e.g. films, canopies, tunnels or cloches
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/06—Polyethene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/08—Copolymers of ethene
- C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
- C08L23/0892—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms containing monomers with other atoms than carbon, hydrogen or oxygen atoms
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2312/00—Crosslinking
- C08L2312/08—Crosslinking by silane
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
- Y02A40/25—Greenhouse technology, e.g. cooling systems therefor
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- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Soil Sciences (AREA)
- Environmental Sciences (AREA)
- Laminated Bodies (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
A UV-resistant plastic film or coating on another carrier material is described, which is designed as climate protector, for example to be used in connection with plant growing, particularly in greenhouse curtains, greenhouse films and cover material for outdoor plant growing, awning and the like. The plastic film or the coating contains wholl y or partly a cross-linked polyolefin containing silane groups which have been introduced by co-polymerisation.
Description
UV RESISTANT PLASTIC FILM OR COATING USED FOR CLIMATE PROTECTION
The present invention refers to a UV-resistant plastic film or coating on another carrier material and which in particular is intended as climate protection for example to be used in connection with plant growing, specially in greenhouse curtains, greenhouse films and cover material for outdoor growing, awning etc. These films have a major problem concerning their useful life, since the film is exposed to sunlight and to several chemicals used in for example plant growing.
Background to the invention To increase the life of such films it is known to use a light stabiliser of the kind which hindering amines (HALS- Hindered Amines Light Stabiliser). This is described in for example EP-A
0,214,507. These are very good stabilisers for thin films with long expected lifetimes. They are often combined with other types of stabilisers and also with UV-absorbents to further increase the life. The hindering amines are very reactive and quickly take care of the degradation products that are formed, and they are basic. This makes it easy for them to react with foreign substances which come in contact with the film and particular substances that are acidic, e.g. sulphur-, chlorine- and bromine-based compounds. In some greenhouses such chemicals are extensively used to protect the plant from various diseases and insects. When the hindering amines react with these chemicals their effects are lost and the film's UV-protection is knocked out. Some greenhouse film producers are limiting their warranties for the films life in connection with or exposure during longer periods of time for the following groups and substances, insecticides, fungicides etc., more specifically substances containing bromine, chlorine, fluorine, iodine, sulphur, petroleum-products and wood protecting agent containing copper.
It is also known that films and coatings obtain shorter lives when they are exposed to so called acid rain which may apply to awnings placed in environment with high level of air pollution. The producer of HALS-stabilisers market some types of stabilisers, that shall be suitable in such environments, so called 'acid rain resistant', but tests have shown that their effectiveness does not differ much from the other HALS-stabilisers.
Through JP-A-5245987 a laminated film intended for greenhouses and similar is known. It is said to have high tensile strength and to be transparent and hem-resistant.
The film is made of EVA to which an unsaturated alkoxysilane has been grafted with help of a peroxide, whereafter the polymer was crosslinked. At the grafting the polymer chain is opened up with the peroxide where the silane-group is attached, which later is crosslinked. There is no information about any UV-resistance of this film and in our own experiments (below), it is shown that such silane grafted polyolefin does not have desired UV-resistance.
Fires can start in curtain structures in greenhouses and may spread very rapidly. A desire is therefor to obtain flame proof material, which also must fulfil all the other expectations such as UV-protection, long life etc. of greenhouse curtains.
Object of the invention and its most important characteristics The purpose with the present invention is to obtain a material suitable for plastic film or coating on another carrier material in greenhouse curtains, greenhouse films and cover material for out door greenhouse growing. As mentioned above, it may also have applications in other products, for example awnings and Venetian blinds, since these may too be exposed to acidic environment.
The material shall be UV-stable and not or only in very small degree be effected by exposure to the chemicals they are normally exposed to in a greenhouse environment and, it should also in some cases be flame resistant.
This has according to the present invention been obtained by using a film or a coating, which wholly or partially contains a crosslinked polyolefin-silane-co-polymer.
Hereby means a copolymer where silane groups are placed in the polyolefin chain in a polymerisation process in difference to a grafted polymer where the polyolefin chain is opened up for example by a peroxide, whereafter the silane groups are placed and crosslinked.
Crosslinking of polyolefin-silane-co-polymer is performed preferably by the influence of water and a silaneol condensations catalyst.
The polyolefm consists of preferably a polyethylene, for example low-density polyethylene, LDPE or some of its co-polymers for example EVA or EBA. The higher UV-stability is surprising since the material is almost an ordinary polyolefin co-polymer with the only difference that the molecules are crosslinked to each other, while properties such as crystallinity are almost unchanged. The crosslinked polyolefin can be mixed with a non-crosslinked polyolefin and/or polyolefin co-polymer. The polyolefin, preferably of the group polyethylene, can also contain one or more other co-monomers in addition to the silane-groups. Examples of such co-monomers are vinyl acetate, butyl acrylate, l-butene and 1-octene.
In a multilayer film or coating shall at least one of the layers consist of the crosslinked polyolefin-silane-co-polymer according to the invention, but other layers may consist of other materials, such as heat radiation absorbing material, including EVA, EBA, PET or PA. Any of the layers of the multiple layer film coating can be provided with a flame protective agent as an additive. Any of the layers of the multiple layer film or coating can wholly or partly consist of a halogen-or phosphorous containing polymer.
The film or coating can also be provided with additives. Examples of such additives are pigments, which make it transparent to some wave lengths of the sun light, thus producing selective sunlight shielding. Other additives can be anti-fog agents such as glycerol stearate, glycerol ester or other products to avoid condensation drops. The anti-fog agent might only be added to the outer layer. The film or coating may also be of cellular type, where the ferment - or blow agent, organic or inorganic, is mixed into the plastic when the film is produced, which creates cavities which are closed, open, or connected, when the blow agent is developed. Other examples of additives are mincible thermoplastics, stabilisation agent, lubricant and flame protective agents.
Description of the invention By the crosslinking of the polyolefin-silane-co-polymer an endless three-dimensional molecular structure is built up, which gives the material advantages such as:
~ higher resistance to UV-radiation;
~ higher chemical resistance;
~ higher heat resistance;
~ memory properties in the material, which results in less shrinking and a lower tendency to form permanent folds;
~ higher break strength;
~ better low temperature properties;
~ and combinations of the above mentioned properties.
The polymer composition in the basic chain consists of a polyolefin-co-polymer containing hydrolysable silane groups. Such a polymer composition is described in for example SE-B 462 752.
Desired flame protectiveness is obtained by adding a flame protective agent to the plastic film/coating, or its produced strips, which may be composed of a halogen- or phosphorous containing compound. These may be used without the level of UV-protection being reduced, which is the case, when using the so called HALS-stabilisers to obtain a satisfying life length.
Another alternative is that the carrier material is composed of halogen- or phosphorous containing plastic film or strips of such a film, which are treated with a layer of the crosslinked polyolefin-silane-co-polymer. Suitable halogen or phosphorous containing polymers include PVC, PVDC, PCTFE, PVF, PVDF, FEB, PTFE or E/TFE.
The film or coating can be of a multiple layer type where at least one of the layers contains the cross-linked polyolefin-silane-co-polymer. In a film or coating of the multiple layer type, a flame protective agent can be added to any of the layers. Any of the layers can consist wholly or partly of a halogen- or phosphorous containing polymer.
In the experiments described below a LDPE crosslinked with a vinyl trimethoxy silane is used.
This polymer behaves as a 'normal' low density polyethylene with respect to extrusion properties. This means that the polymer may be extruded to a film on a normal extruder without special rebuilding or additives in the form of special equipment. The crosslinking is obtained after extrusion in the presence of water and a catalyst. The production is described in the example below.
Exa'rtple 1 Production of a blown film containing a crosslinked polyethylene.
As crosslinked polymer we have used a silane crosslinked LDPE from Borealis, LE 4421, with addition of a catalyst in master batch form called LE 4436. LE 4421 is a commercial copolymer where vinyltrimethoxysilane is polymerised in the chain. We have used 5%
catalyst master batch. The polymer and the catalyst were mixed separately just before the extrusion, though this can also be done with the normal mixing equipment as is usually present on the extruder. An advantage with the later method it that one decreases the contact time between the polymer and the catalyst, thereby minimizing the risk for a too early crosslinkage; which creates gels in the film.
The polymer and the catalyst master batch were stored protected from damp and moisture at about 20°C, to decrease the risk for a too early crosslinkage.
The film material with a density of 923 kg/m ' and a MFRS of 0,9 g/10 min was run at a temperature setting of the extruder's heat zones of 150-170 °C.-The screw velocity was 112 rpm which gave a work force of 52 Amp, a melting pressure of 266 bar and a melting temperature of I78 °C.
To obtain a film with for us suitable properties, we used a blow up ratio of 1:2. The melting temperature was kept below 180 °C to avoid problems with gel formation.
To protect the polymer from degradation during the extrusion it was stabilised by process stabilisers in the form of antioxidants.
Example 2 Experiments were made to test the life at different plastic films, that were exposed to UV-radiation and sulphur/sulphur compounds.
The tests performed had as a goal to reflect as far as possible real conditions in greenhouses.
The samples were first exposed to one day and one night of sulphur using a so called sulphur lamp, whereafter it was exposed in an Atlas Xenon Weather-ometer Ci35 A. The conditions in the Weather-Ometer were: 0,35 W/m ~ at 340 nm, 23 h lightl24 h. No water spraying. The conditions should reflect those in Florida. Samples were taken from the Weater-Ometer at regular intervals and were tested in a tensile tester (tensile velocity 100 mm/min) and controlled in an FT-IR to see the carbonyl accumulation at 1718 cm The films tested were:
70 micron LDPE + HALS
70 micron crosslinked LDPE-silane-co-polymer.
Below are the results obtained. They are based on tensile strength measurements.
Table 1. Time to 50% relative stretching A 1400 h > 1500 h B 470 h > 1500 h RECTIFIED SHEET (RULE 91 ) In experiment A the film samples were exposed only to the Weather-Ometer. In experiment B
the samples were first exposed 24 h to a sulphur lamp and thereafter to the Weather- Ometer.
As seen from experiments, the crosslinked film is very UV-stable irrespectively of whether it was exposed to sulphur or not. The uncrosslinked polymer had a good UV-stability when it was not exposed to sulphur, but after exposure the film's UV-stability decreased exponentially. If one wishes to increase the life of the crosslinked polymer it is of course possible to add a HALS-stabiliser to it. The stabiliser's effect at acidic environments may however be questioned.
Example 3 The experiment was performed to compare the life of plastic films of HDPE
silane grafted HDPE and ethene/vinylsilane-co-polymer which has been exposed to UV-radiation The films were exposed in an Atlas Xenon Weather-Ometer Ci35A under the conditions: 0,35 W/m2 at 340 nm, 23 h light/24 h. No water spraying. A simple mechanical test was performed continuously during the time the samples were ageing by taking them out and bending them. As long as this could be performed without the film sample broke or fell into pieces, the ageing continued. The time it took until the sample was broke or became fragile, is given in Table 2.
The films tested were:
A. 50 micron HDPE
B. 50 micron HDPE + HALS
C. 50 micron silane grafted HDPE
D. 50 micron silane grafted HDPE + HALS
E. 70 micron ethylene/vinylsilane co-polymer F. 50 micron ethylene/vinylsilane co-polymer + HALS
G. 50 micron 50/50 (ethylene/vinylsilane co-polymer + HpPE) H. 50 micron 50/50 (ethylene/vinylsilane co-polymer + HDPE) + HALS
Below are the results obtained.
Table 2. Time until the samples became fragile.
A B C D E F G H
1000h 1450h 1300h 1300h >SOOOh >SOOOh >2000h >2000h As seen surprisingly good results were obtained with the ethylene/vinyl co-polymer compared to the silane grafted polyethylene.
The material according to the invention can as already mentioned be in the form of a film or in the form of a coating on another carrier material. The thickness is preferably <~500 micron. With films we refer to both continuous films and small film strips, which can be used in greenhouse curtains. The film or coating can be of multiple layer type where at least one of the layers is composed of crosslinked polyolefin-silane-co-polymer according to the invention, while other layers may be of other material, for example heat absorbing material. Example of such materials are the polyethylene-co-polymers EVA, EBA, PET or PA. Any of the layers of the multiple layer film or coating can have a flame protective agent as an additive. In another embodiment of the invention, any of the layers of the multiple layer or coating wholly or partly consists of a halogen-or phosphorous containing compound.
The film or coating can be pigmented to obtain selective screening of the sunlight to affect plant growth. With this we mean it is transparent only to some wave lengths of the sunlight. Examples of such pigments are interference pigments as described in WO 95/05727. Also addition of UV-absorbents is a possibility, particularly of benzophenone or benzotriazole type. It may also contain so called anti-fog agents to avoid condensation droplets. The anti-fog agent may be added to only the surface layer of the film.
The film or coating may also be a so called cell type, with which we mean a plastic film where a ferment- or bubble component, organic or inorganic, is mixed into the plastic when the film is produced, which creates cavities or bubbles, closed, open, or connected, when the bubbling component is broken down.
An example of how the film can be used is as foldable climate protection curtains or awnings of that kind which comprises with each other connected strips. The strips can be either plaited together or with each other and/or connected through a system of yarn threads, for example through a knitting or weaving process. One example of such a climate protection curtain is described in EP 0 109 951. The strips shall here at least partly contain the UV-resistant plastic film according to this invention.
Another example on the use of the invention is as foldable water proof climate protection curtains or awnings of the kind that comprises of with each other connected strips, yarn treads or a combination of strips and yarn treads, where the curtain on at least one side has a water proof layer wholly or partially composed of the UV-resistant plastic film according to the invention.
At least a part of the strips in the climate curtain or awning can be light permeable. The strips may have an additive of a flame protective agent.
The invention is of course not limited to the described examples, but several modifications are possible within the scope of claims.
RECTIFIED SHEET (RULE 91 )
The present invention refers to a UV-resistant plastic film or coating on another carrier material and which in particular is intended as climate protection for example to be used in connection with plant growing, specially in greenhouse curtains, greenhouse films and cover material for outdoor growing, awning etc. These films have a major problem concerning their useful life, since the film is exposed to sunlight and to several chemicals used in for example plant growing.
Background to the invention To increase the life of such films it is known to use a light stabiliser of the kind which hindering amines (HALS- Hindered Amines Light Stabiliser). This is described in for example EP-A
0,214,507. These are very good stabilisers for thin films with long expected lifetimes. They are often combined with other types of stabilisers and also with UV-absorbents to further increase the life. The hindering amines are very reactive and quickly take care of the degradation products that are formed, and they are basic. This makes it easy for them to react with foreign substances which come in contact with the film and particular substances that are acidic, e.g. sulphur-, chlorine- and bromine-based compounds. In some greenhouses such chemicals are extensively used to protect the plant from various diseases and insects. When the hindering amines react with these chemicals their effects are lost and the film's UV-protection is knocked out. Some greenhouse film producers are limiting their warranties for the films life in connection with or exposure during longer periods of time for the following groups and substances, insecticides, fungicides etc., more specifically substances containing bromine, chlorine, fluorine, iodine, sulphur, petroleum-products and wood protecting agent containing copper.
It is also known that films and coatings obtain shorter lives when they are exposed to so called acid rain which may apply to awnings placed in environment with high level of air pollution. The producer of HALS-stabilisers market some types of stabilisers, that shall be suitable in such environments, so called 'acid rain resistant', but tests have shown that their effectiveness does not differ much from the other HALS-stabilisers.
Through JP-A-5245987 a laminated film intended for greenhouses and similar is known. It is said to have high tensile strength and to be transparent and hem-resistant.
The film is made of EVA to which an unsaturated alkoxysilane has been grafted with help of a peroxide, whereafter the polymer was crosslinked. At the grafting the polymer chain is opened up with the peroxide where the silane-group is attached, which later is crosslinked. There is no information about any UV-resistance of this film and in our own experiments (below), it is shown that such silane grafted polyolefin does not have desired UV-resistance.
Fires can start in curtain structures in greenhouses and may spread very rapidly. A desire is therefor to obtain flame proof material, which also must fulfil all the other expectations such as UV-protection, long life etc. of greenhouse curtains.
Object of the invention and its most important characteristics The purpose with the present invention is to obtain a material suitable for plastic film or coating on another carrier material in greenhouse curtains, greenhouse films and cover material for out door greenhouse growing. As mentioned above, it may also have applications in other products, for example awnings and Venetian blinds, since these may too be exposed to acidic environment.
The material shall be UV-stable and not or only in very small degree be effected by exposure to the chemicals they are normally exposed to in a greenhouse environment and, it should also in some cases be flame resistant.
This has according to the present invention been obtained by using a film or a coating, which wholly or partially contains a crosslinked polyolefin-silane-co-polymer.
Hereby means a copolymer where silane groups are placed in the polyolefin chain in a polymerisation process in difference to a grafted polymer where the polyolefin chain is opened up for example by a peroxide, whereafter the silane groups are placed and crosslinked.
Crosslinking of polyolefin-silane-co-polymer is performed preferably by the influence of water and a silaneol condensations catalyst.
The polyolefm consists of preferably a polyethylene, for example low-density polyethylene, LDPE or some of its co-polymers for example EVA or EBA. The higher UV-stability is surprising since the material is almost an ordinary polyolefin co-polymer with the only difference that the molecules are crosslinked to each other, while properties such as crystallinity are almost unchanged. The crosslinked polyolefin can be mixed with a non-crosslinked polyolefin and/or polyolefin co-polymer. The polyolefin, preferably of the group polyethylene, can also contain one or more other co-monomers in addition to the silane-groups. Examples of such co-monomers are vinyl acetate, butyl acrylate, l-butene and 1-octene.
In a multilayer film or coating shall at least one of the layers consist of the crosslinked polyolefin-silane-co-polymer according to the invention, but other layers may consist of other materials, such as heat radiation absorbing material, including EVA, EBA, PET or PA. Any of the layers of the multiple layer film coating can be provided with a flame protective agent as an additive. Any of the layers of the multiple layer film or coating can wholly or partly consist of a halogen-or phosphorous containing polymer.
The film or coating can also be provided with additives. Examples of such additives are pigments, which make it transparent to some wave lengths of the sun light, thus producing selective sunlight shielding. Other additives can be anti-fog agents such as glycerol stearate, glycerol ester or other products to avoid condensation drops. The anti-fog agent might only be added to the outer layer. The film or coating may also be of cellular type, where the ferment - or blow agent, organic or inorganic, is mixed into the plastic when the film is produced, which creates cavities which are closed, open, or connected, when the blow agent is developed. Other examples of additives are mincible thermoplastics, stabilisation agent, lubricant and flame protective agents.
Description of the invention By the crosslinking of the polyolefin-silane-co-polymer an endless three-dimensional molecular structure is built up, which gives the material advantages such as:
~ higher resistance to UV-radiation;
~ higher chemical resistance;
~ higher heat resistance;
~ memory properties in the material, which results in less shrinking and a lower tendency to form permanent folds;
~ higher break strength;
~ better low temperature properties;
~ and combinations of the above mentioned properties.
The polymer composition in the basic chain consists of a polyolefin-co-polymer containing hydrolysable silane groups. Such a polymer composition is described in for example SE-B 462 752.
Desired flame protectiveness is obtained by adding a flame protective agent to the plastic film/coating, or its produced strips, which may be composed of a halogen- or phosphorous containing compound. These may be used without the level of UV-protection being reduced, which is the case, when using the so called HALS-stabilisers to obtain a satisfying life length.
Another alternative is that the carrier material is composed of halogen- or phosphorous containing plastic film or strips of such a film, which are treated with a layer of the crosslinked polyolefin-silane-co-polymer. Suitable halogen or phosphorous containing polymers include PVC, PVDC, PCTFE, PVF, PVDF, FEB, PTFE or E/TFE.
The film or coating can be of a multiple layer type where at least one of the layers contains the cross-linked polyolefin-silane-co-polymer. In a film or coating of the multiple layer type, a flame protective agent can be added to any of the layers. Any of the layers can consist wholly or partly of a halogen- or phosphorous containing polymer.
In the experiments described below a LDPE crosslinked with a vinyl trimethoxy silane is used.
This polymer behaves as a 'normal' low density polyethylene with respect to extrusion properties. This means that the polymer may be extruded to a film on a normal extruder without special rebuilding or additives in the form of special equipment. The crosslinking is obtained after extrusion in the presence of water and a catalyst. The production is described in the example below.
Exa'rtple 1 Production of a blown film containing a crosslinked polyethylene.
As crosslinked polymer we have used a silane crosslinked LDPE from Borealis, LE 4421, with addition of a catalyst in master batch form called LE 4436. LE 4421 is a commercial copolymer where vinyltrimethoxysilane is polymerised in the chain. We have used 5%
catalyst master batch. The polymer and the catalyst were mixed separately just before the extrusion, though this can also be done with the normal mixing equipment as is usually present on the extruder. An advantage with the later method it that one decreases the contact time between the polymer and the catalyst, thereby minimizing the risk for a too early crosslinkage; which creates gels in the film.
The polymer and the catalyst master batch were stored protected from damp and moisture at about 20°C, to decrease the risk for a too early crosslinkage.
The film material with a density of 923 kg/m ' and a MFRS of 0,9 g/10 min was run at a temperature setting of the extruder's heat zones of 150-170 °C.-The screw velocity was 112 rpm which gave a work force of 52 Amp, a melting pressure of 266 bar and a melting temperature of I78 °C.
To obtain a film with for us suitable properties, we used a blow up ratio of 1:2. The melting temperature was kept below 180 °C to avoid problems with gel formation.
To protect the polymer from degradation during the extrusion it was stabilised by process stabilisers in the form of antioxidants.
Example 2 Experiments were made to test the life at different plastic films, that were exposed to UV-radiation and sulphur/sulphur compounds.
The tests performed had as a goal to reflect as far as possible real conditions in greenhouses.
The samples were first exposed to one day and one night of sulphur using a so called sulphur lamp, whereafter it was exposed in an Atlas Xenon Weather-ometer Ci35 A. The conditions in the Weather-Ometer were: 0,35 W/m ~ at 340 nm, 23 h lightl24 h. No water spraying. The conditions should reflect those in Florida. Samples were taken from the Weater-Ometer at regular intervals and were tested in a tensile tester (tensile velocity 100 mm/min) and controlled in an FT-IR to see the carbonyl accumulation at 1718 cm The films tested were:
70 micron LDPE + HALS
70 micron crosslinked LDPE-silane-co-polymer.
Below are the results obtained. They are based on tensile strength measurements.
Table 1. Time to 50% relative stretching A 1400 h > 1500 h B 470 h > 1500 h RECTIFIED SHEET (RULE 91 ) In experiment A the film samples were exposed only to the Weather-Ometer. In experiment B
the samples were first exposed 24 h to a sulphur lamp and thereafter to the Weather- Ometer.
As seen from experiments, the crosslinked film is very UV-stable irrespectively of whether it was exposed to sulphur or not. The uncrosslinked polymer had a good UV-stability when it was not exposed to sulphur, but after exposure the film's UV-stability decreased exponentially. If one wishes to increase the life of the crosslinked polymer it is of course possible to add a HALS-stabiliser to it. The stabiliser's effect at acidic environments may however be questioned.
Example 3 The experiment was performed to compare the life of plastic films of HDPE
silane grafted HDPE and ethene/vinylsilane-co-polymer which has been exposed to UV-radiation The films were exposed in an Atlas Xenon Weather-Ometer Ci35A under the conditions: 0,35 W/m2 at 340 nm, 23 h light/24 h. No water spraying. A simple mechanical test was performed continuously during the time the samples were ageing by taking them out and bending them. As long as this could be performed without the film sample broke or fell into pieces, the ageing continued. The time it took until the sample was broke or became fragile, is given in Table 2.
The films tested were:
A. 50 micron HDPE
B. 50 micron HDPE + HALS
C. 50 micron silane grafted HDPE
D. 50 micron silane grafted HDPE + HALS
E. 70 micron ethylene/vinylsilane co-polymer F. 50 micron ethylene/vinylsilane co-polymer + HALS
G. 50 micron 50/50 (ethylene/vinylsilane co-polymer + HpPE) H. 50 micron 50/50 (ethylene/vinylsilane co-polymer + HDPE) + HALS
Below are the results obtained.
Table 2. Time until the samples became fragile.
A B C D E F G H
1000h 1450h 1300h 1300h >SOOOh >SOOOh >2000h >2000h As seen surprisingly good results were obtained with the ethylene/vinyl co-polymer compared to the silane grafted polyethylene.
The material according to the invention can as already mentioned be in the form of a film or in the form of a coating on another carrier material. The thickness is preferably <~500 micron. With films we refer to both continuous films and small film strips, which can be used in greenhouse curtains. The film or coating can be of multiple layer type where at least one of the layers is composed of crosslinked polyolefin-silane-co-polymer according to the invention, while other layers may be of other material, for example heat absorbing material. Example of such materials are the polyethylene-co-polymers EVA, EBA, PET or PA. Any of the layers of the multiple layer film or coating can have a flame protective agent as an additive. In another embodiment of the invention, any of the layers of the multiple layer or coating wholly or partly consists of a halogen-or phosphorous containing compound.
The film or coating can be pigmented to obtain selective screening of the sunlight to affect plant growth. With this we mean it is transparent only to some wave lengths of the sunlight. Examples of such pigments are interference pigments as described in WO 95/05727. Also addition of UV-absorbents is a possibility, particularly of benzophenone or benzotriazole type. It may also contain so called anti-fog agents to avoid condensation droplets. The anti-fog agent may be added to only the surface layer of the film.
The film or coating may also be a so called cell type, with which we mean a plastic film where a ferment- or bubble component, organic or inorganic, is mixed into the plastic when the film is produced, which creates cavities or bubbles, closed, open, or connected, when the bubbling component is broken down.
An example of how the film can be used is as foldable climate protection curtains or awnings of that kind which comprises with each other connected strips. The strips can be either plaited together or with each other and/or connected through a system of yarn threads, for example through a knitting or weaving process. One example of such a climate protection curtain is described in EP 0 109 951. The strips shall here at least partly contain the UV-resistant plastic film according to this invention.
Another example on the use of the invention is as foldable water proof climate protection curtains or awnings of the kind that comprises of with each other connected strips, yarn treads or a combination of strips and yarn treads, where the curtain on at least one side has a water proof layer wholly or partially composed of the UV-resistant plastic film according to the invention.
At least a part of the strips in the climate curtain or awning can be light permeable. The strips may have an additive of a flame protective agent.
The invention is of course not limited to the described examples, but several modifications are possible within the scope of claims.
RECTIFIED SHEET (RULE 91 )
Claims
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. UV-resistant plastic film or coating for climate protection, characterized in that the plastic film or coating is wholly or partly composed of a co-polymer which is a crosslinked polyolefin containing silane groups that have been introduced by co-polymerisation.
2. The plastic film or coating according to claim 1, characterized in that the crosslinked polyolefin consists of a polyethylene.
The plastic film or coating according to claim 2, characterized in that the polyethylene is LDPE and/or HDPE.
4. The plastic film or coating according to claim 1, characterized in that the crosslinked polyolefin consists of copolymers of polyethylene.
S. The plastic film or coating according to claim 4, characterized in that the copolymer of polyethylene is EVA or EBA.
6. The plastic film or coating according to any one of claims 1 to 5, characterized in that the polyolefin-silane-co-polymer was crosslinked by the influence of water and a silane condensation catalyst.
7. The plastic film or coating according to any one of claims 1 to 6, characterized in that the plastic film/coating produced of a crosslinked polyolefin is provided with a flame protective agent as an additive.
8. The plastic film or coating according to any one of claims 1 to 7, characterized in that the plastic film or coating is of a multiple layer type where at least one of the layers contains the crosslinked polyolefin-silane-co-polymer.
The plastic film or coating according to claim 8, characterized in that at least one of the other layers contains a heat absorbing material.
10. The plastic film or coating according to claim 9, wherein the heat absorbing material is EVA, EBA, PET or PA.
11. The plastic film or coating according to claim 9 or 10, characterized in that any of the layers of the multiple layer film or coating is provided with a flame protective agent as an additive.
12. The plastic film or coating according to any one of claims 8 to 11, characterized in that any of the layers of the multiple layer film or coating wholly or partly consists of a halogen- or phosphorous containing polymer.
13. The plastic film or coating according to claim 12 wherein the halogen- or phosphorous containing polymer is PVC, PVDC, PCTFE, PVF, PVDF, FEB, PTFE, or E/TFE.
l4. The plastic film or coating according to any one of claims 1 to 13, characterized in that the plastic film or coating is pigmented to produce a selective sunlight shielding.
l 5. The plastic film or coating according to any one of claims 1 to 14, characterized in that the plastic film or coating contains an anti-fog agent as an additive, to prevent condensation drops.
16. The plastic film or coating according to claim 15 wherein the anti-fog agent is glycerol stearate or glycerol ester.
l 7. The plastic film or coating according to any one of claims 1 to 16, characterized in that the plastic film or coating is cellular in structure, having closed or opened cavities/bubbles.
18. The plastic film or coating according to any one of claims 1 to 17, characterized in that the crosslinked polyolefin is mixed with a non-crosslinked polyolefin and/or polyolefin co-polymer.
19. The plastic film or coating according to any one of claims 1 to 18, characterized in that the plastic film or coating contains a UV-stabiliser as an additive.
20. The plastic film or coating according to claim 19, wherein the UV-stabiliser is a HALS-stabiliser.
21. The plastic film or coating according to any one of claims 1 to 20, characterized in that the plastic film or coating contains a UV-absorbent as an additive.
22. The plastic film or coating according to claim 21 wherein the UV-absorbent is benzophenone or benzotriazole.
23. A foldable climate protection curtain or awning which comprises a plurality of inter-connected strips, characterized in that the said strips are at least partly composed of a UV-resistant plastic film, which wholly or partly is a crosslinked polyolefin containing silane groups which have been introduced by co-polymerisation.
24. The foldable climate protection curtain or awning of claim 23 further comprising yarn threads.
25. A foldable, water proof climate protection curtain or awning which comprises a plurality of inter-connected strips and/or yarn threads, characterized in that the curtain on at least one side has a water proof layer wholly or partly containing a UV-resistant plastic film which is wholly or partly a crosslinked polyolefin containing silane-groups which have been introduced by co-polymerisation.
26. Climate protection curtain according to claim 24 or 25, characterized in that at least some of the strips are light permeable.
27. Climate protection curtain according to any one of claims 24 to 26, characterized in that the strips comprise said UV-resistant plastic film with a flame protective agent as an additive.
28. Climate protection curtain according to any one of claims 24 to 27 characterized in that the strips are connected with the yarn threads.
29. The plastic film or coating according to any one of claims 1 to 22, wherein the plastic film or coating is used in connection with plant growing.
30. The plastic film or coating according to any one of claims 1 to 22 or 29, wherein the plastic film or coating is used in greenhouse curtains, greenhouse films, awning, and cover material for plant growing.
1. UV-resistant plastic film or coating for climate protection, characterized in that the plastic film or coating is wholly or partly composed of a co-polymer which is a crosslinked polyolefin containing silane groups that have been introduced by co-polymerisation.
2. The plastic film or coating according to claim 1, characterized in that the crosslinked polyolefin consists of a polyethylene.
The plastic film or coating according to claim 2, characterized in that the polyethylene is LDPE and/or HDPE.
4. The plastic film or coating according to claim 1, characterized in that the crosslinked polyolefin consists of copolymers of polyethylene.
S. The plastic film or coating according to claim 4, characterized in that the copolymer of polyethylene is EVA or EBA.
6. The plastic film or coating according to any one of claims 1 to 5, characterized in that the polyolefin-silane-co-polymer was crosslinked by the influence of water and a silane condensation catalyst.
7. The plastic film or coating according to any one of claims 1 to 6, characterized in that the plastic film/coating produced of a crosslinked polyolefin is provided with a flame protective agent as an additive.
8. The plastic film or coating according to any one of claims 1 to 7, characterized in that the plastic film or coating is of a multiple layer type where at least one of the layers contains the crosslinked polyolefin-silane-co-polymer.
The plastic film or coating according to claim 8, characterized in that at least one of the other layers contains a heat absorbing material.
10. The plastic film or coating according to claim 9, wherein the heat absorbing material is EVA, EBA, PET or PA.
11. The plastic film or coating according to claim 9 or 10, characterized in that any of the layers of the multiple layer film or coating is provided with a flame protective agent as an additive.
12. The plastic film or coating according to any one of claims 8 to 11, characterized in that any of the layers of the multiple layer film or coating wholly or partly consists of a halogen- or phosphorous containing polymer.
13. The plastic film or coating according to claim 12 wherein the halogen- or phosphorous containing polymer is PVC, PVDC, PCTFE, PVF, PVDF, FEB, PTFE, or E/TFE.
l4. The plastic film or coating according to any one of claims 1 to 13, characterized in that the plastic film or coating is pigmented to produce a selective sunlight shielding.
l 5. The plastic film or coating according to any one of claims 1 to 14, characterized in that the plastic film or coating contains an anti-fog agent as an additive, to prevent condensation drops.
16. The plastic film or coating according to claim 15 wherein the anti-fog agent is glycerol stearate or glycerol ester.
l 7. The plastic film or coating according to any one of claims 1 to 16, characterized in that the plastic film or coating is cellular in structure, having closed or opened cavities/bubbles.
18. The plastic film or coating according to any one of claims 1 to 17, characterized in that the crosslinked polyolefin is mixed with a non-crosslinked polyolefin and/or polyolefin co-polymer.
19. The plastic film or coating according to any one of claims 1 to 18, characterized in that the plastic film or coating contains a UV-stabiliser as an additive.
20. The plastic film or coating according to claim 19, wherein the UV-stabiliser is a HALS-stabiliser.
21. The plastic film or coating according to any one of claims 1 to 20, characterized in that the plastic film or coating contains a UV-absorbent as an additive.
22. The plastic film or coating according to claim 21 wherein the UV-absorbent is benzophenone or benzotriazole.
23. A foldable climate protection curtain or awning which comprises a plurality of inter-connected strips, characterized in that the said strips are at least partly composed of a UV-resistant plastic film, which wholly or partly is a crosslinked polyolefin containing silane groups which have been introduced by co-polymerisation.
24. The foldable climate protection curtain or awning of claim 23 further comprising yarn threads.
25. A foldable, water proof climate protection curtain or awning which comprises a plurality of inter-connected strips and/or yarn threads, characterized in that the curtain on at least one side has a water proof layer wholly or partly containing a UV-resistant plastic film which is wholly or partly a crosslinked polyolefin containing silane-groups which have been introduced by co-polymerisation.
26. Climate protection curtain according to claim 24 or 25, characterized in that at least some of the strips are light permeable.
27. Climate protection curtain according to any one of claims 24 to 26, characterized in that the strips comprise said UV-resistant plastic film with a flame protective agent as an additive.
28. Climate protection curtain according to any one of claims 24 to 27 characterized in that the strips are connected with the yarn threads.
29. The plastic film or coating according to any one of claims 1 to 22, wherein the plastic film or coating is used in connection with plant growing.
30. The plastic film or coating according to any one of claims 1 to 22 or 29, wherein the plastic film or coating is used in greenhouse curtains, greenhouse films, awning, and cover material for plant growing.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9601499-8 | 1996-04-17 | ||
| SE9601499A SE506736C2 (en) | 1996-04-17 | 1996-04-17 | UV-resistant plastic film or coating and its use as climate protection |
| PCT/SE1997/000648 WO1997039058A1 (en) | 1996-04-17 | 1997-04-17 | Uv resistant plastic film or coating used for climate protection |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2251715A1 CA2251715A1 (en) | 1997-10-23 |
| CA2251715C true CA2251715C (en) | 2007-04-03 |
Family
ID=37951738
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002251715A Expired - Fee Related CA2251715C (en) | 1996-04-17 | 1997-04-17 | Uv resistant plastic film or coating used for climate protection |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2251715C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI395806B (en) | 2010-04-14 | 2013-05-11 | Ind Tech Res Inst | Encapsulation material |
-
1997
- 1997-04-17 CA CA002251715A patent/CA2251715C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2251715A1 (en) | 1997-10-23 |
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