U.S. patent application number 13/738852 was filed with the patent office on 2013-05-23 for polymer composite film with barrier functionality.
This patent application is currently assigned to BAYER INNOVATION GMBH. The applicant listed for this patent is BAYER INNOVATION GMBH. Invention is credited to Ralf DUJARDIN, Arno SCHMUCK, Almuth STREITENBERGER.
Application Number | 20130130048 13/738852 |
Document ID | / |
Family ID | 40002996 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130130048 |
Kind Code |
A1 |
DUJARDIN; Ralf ; et
al. |
May 23, 2013 |
POLYMER COMPOSITE FILM WITH BARRIER FUNCTIONALITY
Abstract
Polymer composite material with barrier functionality, in
particular for the use in fumigation methods, comprising at least
one base polymer compound and at least one barrier functional
layer, wherein the barrier functional layer comprises at least one
binder that is cross-linkable and after cross-linking capable of
water absorbing and gel-forming.
Inventors: |
DUJARDIN; Ralf;
(Duesseldorf, DE) ; SCHMUCK; Arno; (Leichlingen,
DE) ; STREITENBERGER; Almuth; (Koeln, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BAYER INNOVATION GMBH; |
Duesseldorf |
|
DE |
|
|
Assignee: |
BAYER INNOVATION GMBH
DUESSELDORF
DE
|
Family ID: |
40002996 |
Appl. No.: |
13/738852 |
Filed: |
January 10, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12175276 |
Jul 17, 2008 |
8372417 |
|
|
13738852 |
|
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60956755 |
Aug 20, 2007 |
|
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60951016 |
Jul 20, 2007 |
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Current U.S.
Class: |
428/516 ;
427/209; 427/393.5 |
Current CPC
Class: |
Y10T 428/31725 20150401;
A01G 13/0275 20130101; Y10T 428/31786 20150401; Y10T 428/31913
20150401; Y10T 428/31551 20150401; Y10T 428/31507 20150401; Y10T
428/31855 20150401 |
Class at
Publication: |
428/516 ;
427/393.5; 427/209 |
International
Class: |
A01G 13/00 20060101
A01G013/00 |
Claims
1. Polymer composite material with barrier functionality comprising
at least one base polymer compound and at least one barrier
functional layer, wherein the barrier functional layer comprises at
least one binder that is cross-linkable and after cross-linking,
said binder is capable of water absorption and/or is
gel-forming.
2. Polymer composite material according to claim 1, wherein the
binder is capable of absorbing at least about 15, times the weight
thereof in an aqueous solution containing 0.9 weight percent sodium
chloride.
3. Polymer composite material according to claim 1 wherein the
polymer composite material comprises a multilayer coating structure
wherein the same or different barrier functional layers are
incorporated into repeating coating layers.
4. Polymer composite material according to claim 1, further
comprising at least one coating layer and an organic biocide is
incorporated into said coating layer.
5. Polymer composite material according to claim 4 wherein the
organic biocide is at least one selected from the group consisting
of pesticides, herbicides, insecticides, algicides, fungicides,
moluscicides, miticides, rodenticides, germicides, antibiotics,
antibacterials, antivirals, antifungals, antiseptics,
antiprotozoals, antiparasites, antiseptics and disinfectants.
6. Polymer composite material according to claim 1, wherein the
base polymer compound is selected from the group consisting of
polyethylene terephthalate, polyvinyl chloride, polyolefins such as
polyethylene and polypropylene, polystyrene, polyester, polyether,
polyacrylate, polycarbonate, polyamide and polyurethane.
7. Polymer composite material according to claim 4, wherein said at
least one coating layer comprises gelatin.
8. Polymer composite material according to claim 4, wherein said at
least one coating layer comprises at least one additive.
9. Polymer composite material according to claim 4, wherein said at
least one coating layer comprises at least one carrier fluid.
10. Method for the production of a polymer composite material
according to claim 1, comprising: coating the base polymer compound
with the barrier functional compound comprising a carrier fluid and
a binder, and curing the barrier functional compound comprising
said carrier fluid and said binder to form a coating layer.
11. Method according to claim 10 wherein the method further
comprises coating at least two sides of the base polymer compound
with a different mixture, each comprising at least one barrier
functional layer.
12. Method according to claim 10, wherein said coating comprises
curtain coating.
13. A method according to claim 10, adopted for use in agriculture
and/or horticulture.
14. A method of claim 13, wherein said method involves mulch film,
fumigation film and/or propagation film.
15. Mulch film, fumigation film and/or propagation film comprising
a polymer composite material according to claim 1.
16. Material of claim 2, wherein said binder comprises a
superabsorbent polymer.
17. Material of claim 2, wherein said binder comprises
polyacrylate.
18. Material of claim 8, wherein said additive comprises a
hardener.
19. Material of claim 8, wherein said additive comprises
formaldehyde.
20. Material of claim 9, wherein said fluid comprises water and/or
an organic solvent.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation application of U.S.
application Ser. No. 12/175,276, filed Jul. 17, 2008, which claims
the benefit of U.S. Provisional Appl. No. 60/956,755, filed Aug.
20, 2007, and U.S. Provisional Appl. No. 60/951,016, filed Jul. 20,
2007, the content of which are incorporated herein by reference in
their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to polymer composite films
with barrier functionality, methods of producing such polymer
composite films and their use, in particular for agricultural
fumigation.
[0004] 2. Description of Related Art
[0005] A wide variety of polymer films like biodegradable mulch
films for reducing weed growth or special biodegradable
horticulture pots are known which are used in the field of
agriculture. An emphasis in the equipment of these polymer films
lies in the task either to stabilize the material against
environmental and chemical influences or to improve the
biodegradability of the material.
[0006] Examples for agricultural films stabilized against
pesticides with an additive can be found in Japanese application JP
631 75 072. In the European patent application EP 0214507 there are
UV stabilizers described which are used in films for outdoor
agriculture.
[0007] Apart from that, olefin polymer films containing various
types of additives are generally known in the art. In U.S. Pat. No.
4,538,531, for example, an improved olefin based polymer film for
the use in fumigation methods is described comprising a
permeability reducing amount of one or more fatty acid derivatives
such as stearicamide.
[0008] However, the balance between resin cost, polymer
processability, film strength, film life span, and film barrier
ability is still a challenge.
[0009] This problem is particularly acute in the area of films used
for confinement of chemical treatment agents, and especially soil
treatment tarpaulins or soil covering materials. For these and
similar uses large amount of film are used to confine chemical
treatment agents to the area where they are applied and are desired
and expected to treat. The chemical treatment agents used, often
volatile gases, tend to diffuse, wash, dissolve or blow away unless
prevented from doing so. The rapid loss or escape of these treating
chemicals can be undesirable for several reasons. For example, the
chemicals may be hazardous or toxic, the desired treatment effects
may not be achieved and/or lager amounts of chemicals may be
required to achieve the desired effects.
[0010] The problem of providing a film fit for the use as
confinement in the described methods is further complicated by the
fact that during usage such films are subjected to conditions that
punctures and tears tend to occur.
[0011] All yet known polymer films in agriculture or horticulture
share the problem that the lifespan of the confinement material is
often shortened due to the necessity of various additives. The
additives can render the polymer films more brittle which reduces
the permeability for gaseous compounds on the one hand and the
resistance to punctures on the other hand. Furthermore, most known
fumigation films are composed of barrier polymers like poly
ethylene vinyl alcohol or polyamide sandwiched between olefin
polymer layers to keep them from swelling. Alternatively,
metallised multi-layered films are used. Such multi-layered
structures show significant stiffness together with a high tendency
to roll up. Both features make the application in the field
complicated and labour intensive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic of a gas permeator analytic cell as
used in connector with the present invention; and
[0013] FIG. 2 is a chart showing transmission rate.
SUMMARY OF THE INVENTION
[0014] Therefore, it is the object of the present invention to
provide a polymer composite film preferably for the use in
agricultural fumigation methods which has an improved barrier
functionality, a good processability, and a long lifespan together
with a reduced stiffness and a reduced tendency to roll up.
[0015] It is another object of the present invention to provide a
method for the production of such a polymer composite film.
[0016] This object is solved by a polymer composite film with
barrier functionality, in particular for the use in agriculture,
comprising at least one base polymer compound and at least one
barrier functional layer, wherein the barrier functional layer
comprises at least one binder that is cross-linkable and after
cross-linking capable of water absorbing and gel-forming. In a
preferred embodiment of the invention, the binder is capable of
absorbing at least about 15, more preferably 25 times its weight in
an aqueous solution containing 0.9 weight percent sodium chloride;
preferably the binder is a superabsorbent polymer, more preferably
the binder is a polyacrylate.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0017] Under the term base polymer compound all polymer compounds
are understood which show a sufficient UV and weather stability to
withstand constant outdoor exposure at least for 12 months and do
not react with organic biocides used in agriculture and whose
properties are not changed by the organic biocide. As the
flexibility of polymer material is dependent upon the material
thickness; especially flexible films of 10 .mu.m to 250 .mu.m
thickness are understood under the term base polymer material.
[0018] Under the term barrier functional layer there are all
polymer based coating layers understood which are capable of
building a water barrier especially to the permeation of fumigation
gases which are emitted by diffusion from fumigated soil. In
another preferred embodiment of the invention the barrier
functional layer comprises water and a superabsorbent polymer which
is capable of a water take-up of at least least 100 weight % per
gram polymer.
[0019] Fumigation is a method of pest control that completely fills
an area with gaseous pesticides to suffocate or poison the pests
within. It is utilized for control of pests in buildings, soil,
grain, and produce, and is also used during processing of goods to
be imported or exported to prevent transfer of exotic organisms.
Over the area to be treated a rubber or polymer film is placed.
This concentrates the gases as well as keeps them from escaping and
doing harm to people and wildlife in the neighbourhood.
[0020] Methyl bromide was among the most widely used fumigants
until its production and use was restricted by the Montreal
Protocol due to its role in ozone depletion. Other widely used
fumigants include phosphine, 1,3-dichloropropene, chloropicrin,
methyl isocyanate, methyl iodide, hydrogen cyanide, sulfuryl
fluoride, hydrogen disulphide and formaldehyde.
[0021] Fumigation usually involves the following phases. First the
area to be fumigated is usually covered to create a sealed
environment; next the fumigant is released into the space to be
fumigated; then, the space is held for a set period while the
fumigant gas percolates through the space and acts on and kills any
infestation in the area, next the space is ventilated so that the
poisonous gases are allowed to escape from the space, and render it
safe to enter.
[0022] Advantageously, the polymer composite material with the
barrier functional layer of the present invention is capable of
securing the confinement of fumigation chemicals over a long period
of time while still remaining good processability and a long life
span. By employing a barrier functional layer comprising at least
one binder that is cross-linkable and after cross-linking capable
of water absorbing and gel-forming, the permeability of the
fumigation chemicals is strongly reduced. The inventive combination
with at least one binder that is cross-linkable and after
cross-linking capable of water absorbing and gel-forming for the
barrier layer secures that water is (during use) absorbed but also
prevents that the absorbed water is evaporated even in the harshest
conditions. Apart from that, due to the barrier coating layer a
much easier handling of the inventive film is achieved by reducing
the stiffness and the tendency to roll up.
[0023] The base polymer compound according to the present invention
can be selected from the group consisting of polyethylene
terephthalate, polyvinyl chloride, polyolefins such as polyethylene
(such as for example LDPE, HDPE) and polypropylene, polystyrene,
polyester, polyether, polyacrylate, polycarbonate, polyamide and
polyurethane which can optionally comprise commonly used pigments,
UV stabilizers, UV absorbers, IR absorber and light diffuser. These
materials show the required resistance to outdoor exposure and can
be used in form of flexible films as wells as molded inflexible
articles like trays and pots.
[0024] The barrier coating layer of the present invention is
preferably formulated from three components: binders, additives and
the carrier fluid. Generally, the barrier coating layer should show
the same resistance to outdoor exposure like the base polymer
compound.
[0025] Binders primarily function as an adhesive to the base
polymer. Binders are polymer adhesive systems with varying
molecular weights. The molecules in the binder can be cross-linked
during the curing stage to improve strength and create the polymer
composite material.
[0026] In the preferred embodiment of the present invention the
barrier coating layer can be based on water soluble polymer
adhesive systems comprising binders which are cross-linkable and
which are after cross-linking water insoluble but water-swellable
and capable of gel-forming by water absorbing. The term
"cross-linkable" according to the present invention indicates that
the binders form a network preferably initiated by heat, pressure,
radiation and/or chemicals (hereinafter also referred to as
hardener). The term "gel-forming" according to the present
invention refers to a colloid structure comprising at least 50%, at
least 75% and typically at least 95% wt liquid, which is
immobilized by surface tension between it and a macromolecular
network of fibres built from a small amount of binders. In a
preferred embodiment the liquid of the gel is water and the gel is
a hydrogel in which water is the dispersion medium.
[0027] The binders are preferably selected from the group
comprising gelatin; alginates; cellulose based polymers such as
methyl cellulose, hydroxymethyl cellulose, carboxymethylcellulose,
cellulose acetate phthalate, and the like; starch based polymers
such as carboxymethyl starch; natural gums, such as gum arabic,
locust bean gum, carrageenan gum and xanthan gum; pectins; polymers
formed from acid-group containing monomers, such as poly(acrylates)
(including poly(acrylic acid), poly(methacrylic acid), and the
like), poly(ethers), poly(acrylamides), poly(vinyl alcohol), maleic
anhydride copolymers, poly(vinyl sulfonates), hydrolyzed
acrylonitrile grafted starch, acrylic acid grafted starch,
poly(N-vinyl pyrrolidone), poly(2-hydroxyethylacrylate),
poly(2-hydroxyethyl-methacrylate), poly(sodium acrylate-co-acrylic
acid), poly(vinylsulfonic acid), poly(ethyleneoxide), block
co-polymers of ethylene oxide with polyamides, polyesters, and
polyurethanes, and salt forms mixtures and copolymers of the
above.
[0028] Particularly preferred binders comprise water soluble (but
after crosslinking insoluble) chemical and/or physical
cross-linkable adhesive polymers such as polyvinyl alcohol,
polyvinyl methyl ether; polyvinyl pyrrolidone; polyethylene oxide;
cellulose derivatives such as dextrans and starches; polyacrylates
such as polyacrylacid, polyacrylamides, methyl cellulose, carboxy
methyl cellulose, starch-based polymers, gelatin, casein, xanthan
hydroxyl-ethyl-cellulose hydroxyl propyl cellulose and/or
dispersions from block co-polymers of ethylene oxide with
polyurethane.
[0029] Illustrative examples of particularly useful gel-forming,
water absorbing cross-linkable coating binders that are capable,
under the most favorable conditions, of absorbing at least about 5,
more preferably at least 10, even more preferably at least 15 and
most preferably at least 25 times its weight in an aqueous solution
containing 0.9 weight percent sodium chloride are preferably
selected from the group comprising superabsorbers such as
poly(acrylates) including poly(acrylic acid), poly(methacrylic
acid), and the like), maleic anhydride copolymers, poly(vinyl
sulfonates), poly(sodium acrylate-co-acrylic acid),
poly(vinylsulfonic acid), (as for example described in the US
patents U.S. Pat. No. 6,737,491, U.S. Pat. No. 6,849,685, U.S. Pat.
No. 6,887,961, U.S. Pat. No. 7,115,321, U.S. Pat. No. 6,964,803,
U.S. Pat. No. 6,808,801, U.S. Pat. No. 7,205,259), gelatin and/or
dispersions from block co-polymers of ethylene oxide with
polyurethane.
[0030] A particularly useful coating material according to the
present invention comprises the combination of at least two water
absorbent cross-linkable polymer binders, wherein one water
absorbent cross-linkable polymer binder is gelatin. In a
particularly preferred embodiment coating layers comprise the
combination of a gelatin binder and a superabsorber binder such as
a polyacrylate binder.
[0031] Gelatin has been shown to be surprisingly beneficial as it
supports the attachment of the water absorbent cross-linkable
polymers to the base polymer without substantially interfering with
the properties of the water absorbent cross-linkable polymers.
[0032] Any gelatin such as photographic gelatin, feed gelatin,
edible gelatin, industrial gelatin, protein gelatin and so on can
be used for such a preferred coating layer. By adding as an
additive a hardener, the gelatin is cross-linked due to a reaction
of free amino-, imino- and hydroxyl groups.
[0033] Additives are defined as insoluble pigments or low molecular
weight chemicals in coating formulations that allow coatings to
perform specific functions but do not contribute to the biocide
function. Additives include but are not limited to pigments.
Pigments are typically the colorant portion of a coating material,
but can also perform corrosion protection or stability in
ultraviolet (UV) light. Additives also include but are not limited
to non-pigments. Non-pigment additives include stabilizers to block
attacks of ultraviolet light or heat, hardener to speed up the
cross-linking reaction, co-solvents to increase viscosity, or
plasticizers to improve uniform coating.
[0034] In a further preferred embodiment of the invention, a
hardener, preferably formaldehyde is used as an additive to
crosslink the coating layer material and to improve the attachment
of the layer material to the base polymer.
[0035] A particularly useful composite material relates to a base
polymer wherein the coating materials comprise a combination of
water absorbent cross-linkable polymers, preferably superabsorbers,
more preferably polyacrylates, gelatin and a hardener, preferably
formaldehyde.
[0036] The carrier fluid is typically a liquid such as an organic
solvent or water. The carrier fluid allows the coating materials to
flow and be applied by methods such as spraying, dipping, cascade
and/or curtain casting. This component may be in the coating
formulation before application, but evaporates afterwards to allow
the solid materials to immobilize and form the polymer composite
material. The polymer composite material can optionally be
dried.
[0037] The carrier fluid might therefore be completely absent,
partially present or present in the final, ready-to-use polymer
composite material. In a preferred embodiment the carrier fluid is
absent or only partially present in the final, ready-to-use polymer
composite material. However, the skilled person in the art
acknowledges that water or another liquid will be absorbed by the
polymer composite material during use and will play an important
role for the functionality of the polymer composite material.
[0038] In a further preferred embodiment of the invention water or
aqueous solutions with ethanol, aceton, 1,4-dioxane,
tetrahydrofuran, dichlormethane, acetonitrile, dimethylformamide,
dimethylsulfoxide, acetic acid, n-butanol, isopropanol, n-propanol,
methanol, formic acid and/or other solvents known to the skilled
person in the art are used as carrier fluids.
[0039] In a further preferred embodiment of the invention, the base
polymer is Corona treated to enhance the attachment of the coating
layer(s) to the base polymer.
[0040] In another preferred embodiment of the invention, the base
polymer (preferably in form of a film) is at least on one side
Corona treated and comprises at least on one side at least one
layer with a binder, preferably superabsorbers and more preferably
polyacrylates. In a preferred embodiment, the base polymer further
comprises at least on one side at least one coating layer with an
additive, preferably a hardener. In another preferred embodiment at
least one of these coating layers further comprises gelatin. In a
more preferred embodiment of the invention all layers further
comprise gelatin. In a more preferred embodiment of the invention,
the base polymer further comprises at least one coating layer with
at least one organic biocide.
[0041] In another preferred embodiment of the invention, the base
polymer is preferably on both sides Corona treated and has on both
sides at least two layers comprising at least one coating layer
with binder(s), preferably superabsorbers and more preferably
polyacrylates. In a preferred embodiment, the base polymer further
comprises at least one coating layer with an additive, preferably a
hardener (for closing-off). In another preferred embodiment at
least one of these coating layers further comprises gelatin. In a
more preferred embodiment of the invention all layers further
comprise gelatin.
[0042] The polymer composite material according to another
preferred embodiment of the present invention can be a multilayer
coating structure and the barrier functional layer is incorporated
into repeating coating layers. As an example, different binders can
be incorporated in different layers or a layer can comprise
different binders. A preferred embodiment of the invention
comprises a polymer composite material wherein the polymer
composite material is of a multilayer coating structure and wherein
the same or different barrier functional layers are incorporated
into repeating coating layers.
[0043] By the incorporation of the barrier functional layer into
repeating coating layers a control of the confinement rates is even
better achievable. Apart from that, different barrier functional
layers can be incorporated so that even scratches and superficial
damages of the film do not impart the safe containment of the
potentially hazardous chemicals. It is known that all other
fumigants besides methyl bromide and methyl iodide have a lack of
effectiveness on pest management in soil fumigation. In another
preferred embodiment of the present invention an organic biocide is
added to the barrier functional layer.
[0044] Like that, the coating layer can not only confine the
fumigation chemicals and thus reduce the amount needed for
effective treatment but it can also prevent the soil from being
infested again. Accordingly, even less chemical is needed to
achieve the desired effect.
[0045] The organic biocide is preferably selected from the group
consisting of pesticides, herbicides, insecticides, algicides,
fungicides, moluscicides, miticides, and rodenticides. Moreover,
the organic biocide can even more preferably be selected from the
group consisting of germicides, antibiotics, antibacterials,
antivirals, antifungals, antiseptics, antiprotozoals and/or
antiparasites as well as mixtures thereof.
[0046] In another preferred embodiment of the invention the organic
biocide is selected from the group of antiseptics and/or
disinfectants for medical use and food as well as mixtures
thereof.
[0047] As the regulations for chemical substances being considered
safe for the use in the agricultural, food and medical field are
constantly changing, such organic biocides are most preferred for
the present invention which comply with the actual official
regulations for chemical substances and especially for antiseptics
and disinfectants in those fields.
[0048] Especially those substances which are listed in the European
the Biocidal Products Directive (98/8/EC) by the European
Commission are preferably used as organic biocides according to the
present invention.
[0049] In another preferred embodiment of the present invention the
organic biocide is selected from the group comprising acetamides
and anilides herbicides like alachlor, acetochlor, metolachlor,
naproamid, carbamate and thiocarbamate herbicides like asulam,
terbucarb, thiobencarb, chlorphenoxy herbicides like 2,4,-D,
2,4-DP, 2,4-DB, 2,4,5-T, MCPA, MCPB, MCPP, dicamba, dipyridyl
herbicides like paraquat, diquat, nitrophenolic and dinitrocresolic
herbicides like alconifen, oyxfluorfen, rimsulfuron,
trifloxysulforon, cyclohexyloxim herbicides like clethodim,
sethoxydim, phosphonate herbicides like glyphosate, glyfusinate,
fosamine ammonium, triazine, triazone, traizolon herbicides like
simazine, cyanazine, metribuzin, carfentrazone, urea herbicide
derivatives like diuron, flumeturon, linuron, haloulfuron,
ethoxysulforon, antibiotics insecticides like abamecitin, spinosad,
cyclodien insecticides like endosulfan, insect growth regulators
like pyriproxfen, carbamate insecticides like methomyl, oxamyl,
nicotenoide herbicides like imidacloprid, pyrethroid herbicides
like cyfluthrin, esfenvalerate, lambda-cyhalothrin, oxadiazine
insecticides like indoxacarb, organophosphorus insecticides like
methamidophos, acephate, naled, malathion, acetamide and anilide
fungicides like mefenoxam, boscalid; fenhexamid, aliphatic nitrogen
fungicides like cymoxanil, aromatic fungicides like chlorothalonil,
dichloran, carbamate and thiocarbamate fungicides like mancozeb,
maneb, propamocarb, thiram, conacol, myclobutanil, imidazole,
morpholin and oxazol insecticides, thiophanate, dimetomorph,
famoxadone, organophosphorous fungicides like fosetyl, phatlimid
fungicides like captan, strobillurin fungicides like azoxystrobin,
pyraclostrobin, trifloxystrobin, azibenzolar, urea derivative
fungicides like bentaluron, pencycuron, oquinazamid, quaternary
ammonium antiseptic compounds like benzalkonium chloride, cetyl
pyridinium chloride, quaternary ammonium related antiseptic
compounds like chlorhexidine gluconate, polyhexamethylene biguanide
hydrochloride and octenidine dihydrochloride.
[0050] Most preferably, the organic biocide of the present
invention is a non-liquid non-oil substance at room temperature
with low volatility whereby the substance is solid or formulated in
solid form. The choice of such substances improves the release
controllability and the storage stability of the polymer composite
material. Especially, essential oils as organic biocides should be
avoided because of the difficulty to provide an even dispersion in
the polymer base compound. Furthermore, the mechanical stability of
the polymer composite material could be deterred in the production
process due to bubble wrap and the like if liquids or substances
with high volatility would be incorporated.
[0051] In another embodiment of the present invention the polymer
composite material can withstand at least 24 months of outside
exposure to sunlight and weather. That is independent on whether
there is a coating layer present or not. By having such a minimum
resistance the polymer compound is sure to fulfil the requirements
of the intended use in agriculture as fumigation or mulch film, for
instance.
[0052] Likewise, the polymer composite material should not be
biodegradable. The function of the polymer composite material
should be usable over a long period of time so that for example no
weeds, pests or fungi can harm the plants as they grow in a field
under the protection of the polymer composite biocide material.
Furthermore, the articles of the intended use like films should be
useable over a wider period of time and should not degrade in one
planting and harvesting season, for example. Especially the
mechanical stability of the films should be kept high because the
film should preferably be retractable from the field and
reusable.
[0053] It is within the scope of the present invention that the
inventive polymer composite material comprises additional pigments,
additives and fillers which are widely known to the skilled
person.
[0054] In another preferred embodiment of the present invention the
barrier functional layer is capable of absorbing water to comprise
a water barrier of at least 0.4 mm thickness. Thus, a minimal
confinement can be provided even over a long period of time and in
hot weather conditions.
[0055] Preferably the thickness of the whole coating layer with
binder(s), preferably superabsorbers and preferably also with
gelatin is between 1-100 .mu.m, preferably 5-40 .mu.m, and
particularly preferred 10-30 .mu.m. The whole coating layer can be
produced by coating several layers of binder(s), preferably
superabsorbers and preferably also gelatin for example with cascade
or curtain casting. The thickness of the whole coating layer with
the additive, preferably the hardener is 0.2-5 .mu.m, preferably
0.5-3 .mu.m, even more preferably 2-3 .mu.m. The whole coating
layer with the additive, preferably hardener and preferably also
with gelatin can be produced by coating several layers of the
hardener and preferably with gelatin for example with cascade or
curtain casting.
[0056] The base polymer has a thickness of 10 to 250 .mu.m,
preferably of 20 to 120 .mu.m, more preferably 20-50 .mu.m.
[0057] Another subject of the present invention is a method for the
production of a polymer composite material according to the present
invention including the step of [0058] coating the base polymer
compound with at least one barrier functional compound comprising a
carrier fluid and a binder, preferably a superabsorbent polymer,
more preferably a polyacrylate polymer and curing the mixture to
give a coating layer.
[0059] The "barrier functional compound" preferably further
comprises gelatin. In a preferred embodiment of the invention,
binders, preferably superabsorbers, more preferably polyacrylates,
gelatin and as an additive a hardener are used as barrier
functional compounds.
[0060] The coating compounds can be applied to the workpiece made
of the base polymer in a variety of ways. Coatings compounds can be
sprayed over the part, or the part can be dipped into a tank of
coating material. Other methods include showering parts with
coatings or rolling parts between large barrels to spread on the
coating.
[0061] Cascade casting or curtain casting advantageously allows the
application of multiple layers, also of different thicknesses, onto
the polymer composite material in a one work step.
[0062] The application of the coating layer is preferably carried
out by curtain coating. The method of curtain coating is well known
in the field of photographic films and papers and can be
advantageously applied to the coating of the present invention.
Improved methods of curtain coating procedures that can be used to
produce the polymer composite material of the present invention
includes such procedures as they are described in EP 1 023 949 A1,
EP 938 935 A2, U.S. Pat. No. 5,906,865, DE 195 00 402, and EP 275
015 B1, which are therefore incorporated by reference.
[0063] In the process of curtain coating, a base film or paper web
is moved continuously by a transport device through a coating zone
and is thereby coated with one or more layers either wholly or
partially by the free-falling liquid curtain.
[0064] In the photographic industry, this process is used, for
example, to apply photosensitive and photoinsensitive coatings.
These coatings comprise mostly multiple layers formed from aqueous
coating solutions which are coated as layer composites in the
liquid state onto the base. The curtain in the curtain-coating
process can be wider or narrower than the base. The base of the
photographic application is mostly a synthetic film or a paper web.
Coating speeds can vary in accordance with the base material and
thickness and with the thickness of the liquid curtain and its
viscosity, for example. In so called high coating speed
applications the photographic coating solutions can be applied at a
base speed from more than 250 meters per minute. The coated base
then passes through a drying device in which the coating solution
is dried. The dry film web is wound up. At this point, the edges of
the web must be dry or else the individual layers of the roll will
adhere.
[0065] With the advantageous possibility of producing the polymer
composite material of the present invention by curtain coating the
base polymer compound with the coating layer comprising carrier
fluid, binder(s), preferably a superabsorbent polymer and
optionally gelatin and/or additives, high production speed and low
cost bulk production can be achieved.
[0066] In a preferred embodiment, curtain coating on a preferably
Corona treated base polymer with a coating comprising a binder,
preferably a superabsorber and a carrier fluid is conducted. In
another preferred embodiment, the coating with the binder further
comprises gelatin. In an additional preferred embodiment, a
hardener as an additive is added shortly before curtain coating to
the coating. A further preferred curtain coating method is
conducted with a second coating comprising as an additive a
hardener with a carrier fluid. In another preferred embodiment, the
second coating comprises gelatin, a carrier fluid and a hardener as
an additive and the hardener is added to the gelatin shortly before
the curtain coating. A further preferred curtain coating method is
conducted with a third coating comprising at least one biocide and
optionally gelatin and a carrier fluid.
[0067] Preferably, the method according to the present invention
comprises the further step of coating both sides of the base
polymer compound with a different mixture each comprising at least
one barrier functional layer.
[0068] Like that, it is possible to incorporate different barrier
functional layers, one for instance for the direct uptake of
chemicals diffused from the soil and the other one as further
confinement layer on the outer surface of the film.
[0069] As already shortly mentioned above, a polymer composite
material according to present invention or a product obtained by a
method according to the present invention can be preferably used in
agriculture as confinement film for fumigation methods.
[0070] The invention also relates to mulch film, fumigation film,
propagation film comprising a polymer composite material as
discussed herein.
FIGURES
[0071] FIG. 1: Schematic design of the gas permeation analytical
cell [0072] Legend: 1: Feed Gas; 2: thermostated; 3: Pressure
Gauge; 4: Exhaust Gas; 5: to quadrupol mass spectrometer; 6: to
vacuum pump; 7: Pressure Gauge; 8: Film; 9: Porous Metal Plate; 10:
Shut-Off Valve (accumulation volume between shut-off valves=6.95
cm.sup.3); 11: Purge Gas
[0073] FIG. 2: Overall transmission rate
EXAMPLES
Example 1
Manufacturing of Propagation Films
[0074] Propagation films by coating a polyethylene film with
following additional layers was manufactured by using curtain
casting machine:
Film 1:
[0075] Base: Corona treated 100 .mu.m thick Low-density
polyethylene (LDPE) polyethylene film
[0076] First layer: 9.36 g/m.sup.2 superabsorber S1 (flexible
absorbent binder composed of: 20-40% by weight Sodium Polyacrylate
(CAS-No.: 9003-04-7), 2-5% by weight polyethylene glycol (CAS-No.:
25322-68-3), water (CAS-No.: 7732-18-5) dissolved in 53.40 g water
[0077] Second layer: 9.36 g/m.sup.2 superabsorber S1 dissolved in
53.40 g water [0078] Third layer: 9.36 g/m.sup.2 superabsorber S1
dissolved in 53.40 g water [0079] Fourth layer: 9.36 g/m.sup.2
superabsorber S1 dissolved in 53.40 g water
Film 2:
[0080] Base: Corona treated 100 .mu.m thick Low-density
polyethylene (LDPE) polyethylene film [0081] First layer: 9.36
g/m.sup.2 superabsorber S1 [0082] and 3.12 g/m2 gelatin dissolved
in 53.40 g water [0083] Second layer: 9.36 g/m.sup.2 superabsorber
S1 [0084] and 3.12 g/m2 gelatin dissolved in 53.40 g water [0085]
Third layer: 9.36 g/m.sup.2 superabsorber S1 [0086] and 3.12 g/m2
gelatin dissolved in 53.40 g water [0087] Fourth layer: 9.36
g/m.sup.2 superabsorber S1 [0088] and 3.12 g/m2 gelatin dissolved
in 53.40 g water [0089] Fifth layer: 2.34 g/m2 gelatin dissolved in
27.53 g water [0090] Sixth layer: 1.20 g/m2 gelatin [0091] 1.33
g/m2 hardener H1 (formaldehyde, concentration: 10% in water;
coating amount 0.086 g hardener H1 per g gelatin). Gelatin and
hardener are premixed shortly before curtain coating with 28.20 g
water
Film 3:
[0092] Base: Corona treated 100 .mu.m thick Low-density
polyethylene (LDPE) polyethylene film [0093] First layer: 9.36
g/m.sup.2 superabsorber S1 [0094] and 3.12 g/m2 gelatin dissolved
in 26.70 g water [0095] Second layer: 9.36 g/m.sup.2 superabsorber
S1 [0096] and 3.12 g/m2 gelatin dissolved in 26.70 g water [0097]
Third layer: 9.36 g/m.sup.2 superabsorber S1 [0098] and 3.12 g/m2
gelatin dissolved in 26.70 g water [0099] Fourth layer: 9.36
g/m.sup.2 superabsorber S1 [0100] and 3.12 g/m2 gelatin dissolved
in 26.70 g water [0101] Fifth layer: 2.34 g/m2 gelatin dissolved in
27.53 g water [0102] Sixth layer: 1.2 g/m2 gelatin, 1.33 g/m2
hardener H1 premixed shortly before curtain coating with 28.20 g
water.
[0103] After coating, the films were dried
Example 2
Mechanic Stability of the Films
[0104] Than, the films prepared according to example 1 were soaked
for 10 minutes in distilled water. Subsequently, excessive water
was drained and the mechanic stability was tested by washing-up the
soaked layers with flowing warm water. Whereas the superabsorber S1
layers dissolve from the polyethylene layer in film 1, the
additional layers in films 2 and 3 do not dissolve from the
polyethylene layer.
Example 3
Permeability of the Films for Methyl Bromide
Analytical Procedure:
[0105] Gas permeability of coated (see example 1) and uncoated
low-density polyethylene (LDPE) films were measured by manometric
determination of the permeating quantity of gas (by measuring the
increase in pressure) and in situ determination of the gas
composition using a connected mass spectrometer for multigas
measurements
Description of the Analytical Device:
[0106] The analytical device used is a gas permeation cell from
Mecadi GmbH (Homurg/Saar). This analytical cell consists of two
temperature-controllable stainless steel cylinder heads, between
which the film to be analyzed is clamped in a gastight manner. The
film is sealed against the two cell halves by pressing a Viton O
ring into the film material from both sides. On the receiving side
the film material rests on a porous sintered metal plate in order
not only to guarantee the mechanical stability of the film even
when a considerably higher absolute pressure is present on the
source side than on the receiving side, but also to ensure that no
significant reduction occurs in the free film area available for
permeation. High precision pressure sensors (0.1 mbar resolution)
for recording the changes in the absolute pressure are screwed into
both cell halves. The receiving side of the cell can be sealed
towards the exterior (see FIG. 1) by three VSM precision metering
valves (leak rate: <1-10.sup.-9 mbar*l/sec). The volume of the
receiving side is determined once by gas-pyknometric analysis and a
connected accumulation volume.
Procedure for Standard Analysis:
[0107] The analytical cell is kept at a constant temperature of
25.5 (+/-0.2).degree. C. The temperature on the receiving side is
continuously recorded. After inserting the film, the analytical
cell is purged on the source side with an inert gas for at least 30
minutes and evacuated on the receiving side down to the final
pressure of the vacuum pump (about 2 mbar). Then the gas or gas
mixture to be permeated (the feed gas) is introduced into the
source side. The gas perfuses the source side at a constant rate of
20 sccm for the entire duration of the gas accumulation process on
the receiving side. About at least 20 minutes after beginning to
introduce the feed gas into the source side of the cell the valves
leading to the pump and to the mass spectrometer are closed and the
gas accumulation process begins on the receiving side. The increase
in pressure on the receiving side is recorded as a function of time
by a connected measured data logger. After allowing gas to
accumulate for several hours the valve leading to the mass
spectrometer is opened and the accumulated gas composition on the
receiving side of the cell is analyzed. The ion streams determined
by the mass spectrometer are quantified by prior calibration
measurements. The oxygen content of the gas atmosphere is also
examined in order to determine whether air has penetrated the
receiving side of the cell from the exterior due to leaks.
Special Analysis using a Film Moistened on the Source Side:
[0108] In order to moisten the film to a specific degree prior to
the permeation analysis it is moistened by sweeping the source side
with nitrogen at a rate of 20 sccm. For this purpose the nitrogen
is bubbled through a water column of a height of 10 cm before being
introduced into the permeation cell. By means of this process
relative humidity of about 50% is produced on the source side. The
duration of this pre-treatment is at least 12 hours. Then the moist
nitrogen is replaced by dry nitrogen by allowing dry nitrogen to
flow through the source side of the cell for 10 minutes. During
this pre-treatment period the receiving side of the cell is
permanently evacuated.
[0109] Permeation experiments were performed with nitrogen and a
gas mixture of 5 Vol. % MeBr in nitrogen. Test results were
obtained for LDPE films by MeBr/nitrogen permeation at dry and
moist conditions.
[0110] Overall permeation (MeBr/N2 Mixture) is reduced by a factor
of 50-100 by coating the LDPE films. Overall permeability (MeBr/N2
Mixture) is not significantly effected by moistening the coated
film before permeation (see FIG. 2).
* * * * *