Patent Application
20230234096
The present invention relates to a water-soluble film, useful for product applications such as pods and tablets, with an integrated water-dispersible nanocomposite barrier against any permeation offering several advantages compared to prior-art water-soluble film executions; and a method for producing water-soluble films with an integrated water-dispersible nanocomposite barrier against any permeation.
Water-soluble films are gaining wider acceptance for use in consumer products, such as liquid detergent pods and automatic dish washer dry powder tablets. To be effective such water-soluble films must maintain properties (strength, permeation barrier) when exposed to chemicals, yet disperse or completely dissolve when immersed in water. The multi-compartment pods introduced by P&G on the market enable the separation of chemistries in top/bottom compartments via a water-soluble film lying flat in the middle of the pod. The water-soluble film must be thick enough to avoid chemical exchanges between the top/bottom compartments, or from exterior contaminants, and must be thin enough to completely dissolve in water during use.
Consumers find that pods may often get sticky over time even when they are not exposed prematurely to water or to a highly humid environment. This is because some of the chemistries held within the pod migrate through the external pod film over time, since today's soluble films are little barrier to the liquid ingredients held within the package. The barrier performance of today's soluble films also causes other issues e.g. migration of chemical species between the separate chambers of a multi-chamber package, making it difficult to separate reactive species even when they are initially separated in different chambers. With time they will diffuse and react together prematurely, before use, limiting the eventual performance of the overall product. Some examples of chemical species present in products that are desirable to limit migration of are: water, perfumes, surfactants, bleaches, hueing dyes, highly migrating Na+ cation, Fe2+ cation.
A common way of producing water-soluble films is via solution casting. An example of commercially available water-soluble film is M8630 from MonoSol LLC in Gary, Ind., USA. Other example of commercially available water-soluble film is traded as Solublon® from Aicello.
Using this current technology, it is only possible to produce a water-soluble film as one layer or monolayer. For those applications where barrier functionality is desirable, the prior art opted for either applying the barrier materials on top of the already formed water-soluble film or dispersing the barrier materials within the components of the water-soluble film. An example of barrier materials dispersed within the components of the water-soluble film is given in the patent application WO2007/027224. If the barrier material is applied on top of the already formed water-soluble film, the seal ability of the water-soluble film on the coated surface is affected, or the barrier performance is negligible. If the barrier material is dispersed within the components of the water-soluble film, the solubility of the water-soluble film is affected, or the barrier performance is negligible. In both cases the barrier performance must be balanced together with other important film properties, thus lowering the barrier performance.
Water-soluble films are also produced via melt extrusion. This process is capable to produce water-soluble multilayer films, provided that the rheological properties and interfacial energies among the different layers do not substantially differ. For those applications where barrier functionality is desirable, the prior art dispersed the barrier materials within the components of the middle layer of the water-soluble film. Also, in this case, water solubility and barrier performance must be balanced together, thus lowering the barrier performance.
As such, there remains an unmet need for water-soluble films and packages made therefrom, such as sachets and pouches, which have improved barrier when exposed to vapour, and yet dissolve or disperse to sufficiently small sized particles sufficiently fast when immersed or exposed to water, such as rinse water or wash water. Sufficiently small and fast depends on the particular product application. For a Single Unit Dose article (SUD), the time required will be less than the wash cycle of the washing machine. For a package for a shower body or hair wash product, the time is less than the average shower time, and for a package that might end up being littered the time is less than a day. Dispersion should be to the extent that the material is compatible with the drainage systems without compromising the product performance. It is therefore an aspect of the present disclosure to provide a water-soluble film having improved barrier against diffusion of undesired chemicals (even water vapour) prior to being thoroughly immersed in water, yet can subsequently substantially dissolve or disperse when immersed in water, such as rinse water or wash water.
A water-soluble film with an integrated water-dispersible nanocomposite barrier is provided that comprises a first water-soluble polymeric layer having a plane; a second water-soluble polymeric layer having a plane; a water-dispersible nanocomposite barrier layer disposed between the first and second water-soluble polymeric layers.
Method of making a water-soluble film with an integrated water-dispersible nanocomposite barrier is provided that comprises applying a first aqueous solution of a water-soluble polymeric composition onto the surface of a removeable flat carrier, such as PET films or steel belts; removing the water from the first aqueous solution of a water-soluble polymeric composition to obtain a first water-soluble polymeric layer; applying an aqueous dispersion of a water-dispersible nanocomposite barrier onto the surface of the first water-soluble polymeric layer; removing the water from the aqueous dispersion of a water-dispersible nanocomposite barrier to obtain a water-dispersible nanocomposite barrier layer; applying a second aqueous solution of a water-soluble polymeric composition onto the surface of the water-dispersible nanocomposite barrier layer; removing the water from the second aqueous solution of a water-soluble polymeric composition to obtain a second water-soluble polymeric layer; removing the flat carrier from the resulting water-soluble nanocomposite barrier film.
The invention describes a water-soluble film with an integrated water-dispersible nanocomposite barrier against water vapour permeation offering several advantages compared to prior art water-soluble films; and a method for making water-soluble films with an integrated water-dispersible nanocomposite barrier layer.
As used herein, the term “water-dispersible” means breaking apart in water in small fragments smaller than a tenth of millimeter. These fragments can, but do not need to be stably suspended in water.
As used herein, the term “nanocomposite” refers to heterogeneous materials comprising orderly spaced hydrophilic nanoplatelets and intercalated polymeric fillers at the nanometric scale; “nanometric scale” means below about 100 nanometers.
As used herein, the term “water vapour transmission rate” or “WVTR” refers to the rate at which water vapour is transmitted through a film, when measured according to the water vapour transmission test method set forth in the test methods section.
As used herein, the term “dissolution time” refers to the time required for a water-soluble film to be dissolved, when measured according to the dissolution test method set forth in the test methods section.
As used herein, the term “copolymer” means a polymer formed from two, or more, types of monomeric repeating units. The term “copolymer” as used herein further encompasses terpolymers, such as terpolymers having a distribution of vinyl alcohol monomer units, vinyl acetate monomer units, and possibly butene diol monomer units; however, if the copolymer is substantially fully hydrolyzed, substantially no vinyl acetate monomeric units may be present.
As used herein, the term “degree of hydrolysis” refers to the mole percentage of vinyl acetate units that are converted to vinyl alcohol units when a polymeric vinyl alcohol is hydrolyzed.
As used herein, when the term “about” modifies a particular value, the term refers to a range equal to the particular value, plus or minus twenty percent (±20%). For any of the embodiments disclosed herein, any disclosure of a particular value, can, in various alternate embodiments, also be understood as a disclosure of a range equal to about that particular value (i.e. ±20%).
As used herein, when the term “approximately” modifies a particular value, the term refers to a range equal to the particular value, plus or minus fifteen percent (±15%). For any of the embodiments disclosed herein, any disclosure of a particular value, can, in various alternate embodiments, also be understood as a disclosure of a range equal to approximately that particular value (i.e. ±15%).
As used herein, when the term “substantially” modifies a particular value, the term refers to a range equal to the particular value, plus or minus ten percent (±10%). For any of the embodiments disclosed herein, any disclosure of a particular value, can, in various alternate embodiments, also be understood as a disclosure of a range equal to approximately that particular value (i.e. ±10%).
As used herein, when the term “nearly” modifies a particular value, the term refers to a range equal to the particular value, plus or minus five percent (±5%). For any of the embodiments disclosed herein, any disclosure of a particular value, can, in various alternate embodiments, also be understood as a disclosure of a range equal to approximately that particular value (i.e. ±5%).
The thickness of the water-soluble polymeric layer 10 between the first surface 12 and the second surface 14 can range from about 1 μm to about 1000 μm, preferably from about 10 μm to about 250 μm, more preferably from about 25 μm to about 125 μm.
The water-soluble polymeric layer 10 comprises at least one water-soluble polymer. Depending on the application, the water-soluble polymer(s) can be selected among available options to dissolve in water at 23° C. temperature within seconds, or minutes, or hours. A polymer requiring more than 24 hours to dissolve in water at 23° C. temperature will not be considered as water-soluble.
The thickness of the water-dispersible nanocomposite barrier layer 20 ranges from about 0.1 μm to about 20 μm, preferably from about 0.1 μm to about 10 μm, more preferably from about 0.1 μm to about 5 μm.
The water-dispersible nanocomposite barrier layer 20 is a nanocomposite comprising orderly spaced hydrophilic nanoplatelets and intercalated polymeric fillers at the nanometric scale, wherein the basal spacing measured via X-ray diffraction (XRD) is lower than 100 Å, preferably lower 60 Å, more preferably lower than 20 Å.
Nanoplatelets are plate-like nanoparticles characterized by high aspect ratio between the diameter and the orthogonal height. The high aspect ratio enables a “brick wall” to be formed where nanoplatelets lay down parallel to the surface of the underlying water-soluble polymeric layer, overlapping each other and laying on top of each other, thus lowering drastically the migration of molecules, whether gaseous or liquid, through the nanoplatelets layer. The higher the aspect ratio, the higher the barrier performance that can be obtained. Typical aspect ratio for montmorillonite exfoliated nanoplatelets is about 100 or more (Cadène et all, JCIS 285(2):719-30 Jun. 2005).
The water-dispersible nanocomposite barrier layer 20 of the present disclosure may be optically opaque, preferably translucent, even more preferably transparent, depending on the nanocomposite material (nanoplatelets exfoliation level, polymeric intercalation between the nanoplatelets, impurities level) and the nanocomposite application process (nanocomposite orientation).
Preferably, the water-dispersible nanocomposite barrier layer 20 is flexible and stretchable. When converting the water-soluble film of the present disclosure through a line for printing, sheeting, slitting, rewinding and other typical converting operations to make articles such as pouches, the water-soluble film of the present disclosure may be elongated up to 200%. This can cause the water-dispersible nanocomposite barrier layer 20 to break. It is thus preferred that the water-dispersible nanocomposite barrier layer 20 is flexible and stretchable without breaking. Preferably, the water-dispersible nanocomposite barrier layer 20 can be elongated at least 20%, more preferably at least 30%, even more preferably at least 50%, most preferably at least 100% and up to 200% without breaking.
The thickness of the water-soluble polymeric layer 30 between the first surface 112 and the second surface 114 can range from about 1 μm to about 1000 μm, preferably from about 10 μm to about 250 μm, more preferably from about 25 μm to about 125 μm.
The water-soluble polymeric layer 30 comprises at least one water-soluble polymer. Depending on the application, the water-soluble polymer(s) can be selected among available options to dissolve in water at 23° C. temperature within seconds, or minutes, or hours. A polymer requiring more than 24 hours to dissolve in water at 23° C. temperature will not be considered as water-soluble.
Each layer of the present disclosure is distinct and separated from the others. By distinct layer, it is meant that the water-dispersible nanocomposite barrier layer 20 within the water-soluble film 100 comprises substantially the nanocomposite barrier materials only, and that the boundaries between the water-dispersible nanocomposite barrier layer 20 and the surrounding water-soluble polymeric layers 10 and 30 are distinguished by a large composition change over a small distance, creating a sharp boundary that is readily seen by microscopy techniques known in the art. The boundary layer, i.e. the intermediate layer of intermediate composition between the water-dispersible nanocomposite barrier layer and the adjacent water-soluble polymeric layer, is no more than 2 μm thick, seen by microscopy techniques known in the art.
When the water-soluble film of the present disclosure is immersed in water (i.e. in applications where the water-soluble film is required to disappear in water), the outer polymeric layers dissolve in water, the inner barrier layer is no longer protected and breaks up in water, the nanocomposite barrier materials disperse in water, thus enabling the entire film to disappear in water.
The water-soluble film comprising a water-dispersible nanocomposite barrier layer of the present disclosure may be opaque, preferably translucent, even more preferably transparent, depending on the materials.
The water-soluble film of the present disclosure may comprise a printed area. Printing may be achieved using standard printing techniques, such as flexographic, gravure, or inkjet printing.
A nanocomposite comprises orderly spaced hydrophilic nanoplatelets and intercalated polymeric fillers at the nanometric scale, wherein the basal spacing measured via XRD is lower than 100 Å, preferably lower 60 Å, more preferably lower than 20 Å.
Nanoplatelets are solid plate-like nanoparticles characterized by high aspect ratio between the diameter and the orthogonal height. High aspect ratio delivers a parallel arrangement of the nanoplatelets, and a longer diffusion path length for chemicals through the nanoplatelets, thus delivering barrier functionality. It is desirable that nanoplatelets are free from defects such as cracks and holes lowering the barrier performance. It is also desirable that nanoplatelets are easily exfoliated in water, both for application purpose (e.g. wet coating) and end-of-life scenarios (e.g. wastewater treatment plants), but highly cohesive when dried. Nanoplatelets are currently used in the industry as rheological modifier, flame retardant, anticorrosion coating and/or chemical barrier. Nanoplatelets can be obtained from natural sources and used as such, or can purified and modified from natural sources, or can be synthetised in furnaces for purity and performance reasons.
Natural phyllosilicates, such as serpentine, clay, chlorite and mica, consist of nanoplatelets stacked together. Natural clays, such as smectites and vermiculites, consist of nanoplatelets stacked together, swelling in presence of water. Smectites, such as montmorillonite and hectorite, consist of nanoplatelets stacked together, swelling the most in presence of water. Natural smectites can be purified and modified, such as sodium cloisite from BYK, obtained from bentonite, a natural mineral containing 60-80% montmorillonite, and cationic exchanged with monovalent sodium for exfoliation purposes. Smectites can be also synthetised, such as laponite manufactured from BYK, and sodium hectorite synthetised at the University of Bayreuth.
Water-soluble polymers, copolymers or derivatives thereof suitable for use as water-soluble polymeric layer are selected from polyvinyl alcohol (PVOH), polyvinyl alcohol copolymers such as butenediol-vinyl alcohol copolymers (BVOH), which are produced by copolymerization of butenediol with vinyl acetate followed by the hydrolysis of vinyl acetate, suitable butenediol monomers being selected from 3,4-diol-1-butene, 3,4-diacyloxy-1-butenes, 3-acyloxy-4-ol-1-butenes, 4-acyloxy-3-ol-1-butenes and the like; polyvinyl pyrrolidone; polyalkylene oxides, such as polyethylene oxides or polyethylene glycols (PEG); poly(methacrylic acid), polyacrylic acids, polyacrylates, acrylate copolymers, maleic/acrylic acids copolymers; polyacrylamide; poly(2-acrylamido-2-methyl-1-propanesulfonic acid (polyAMPS); polyamides, poly-N-vinyl acetamide (PNVA); polycarboxylic acids and salts; cellulose derivatives such as cellulose ethers, methylcellulose, hydroxyethyl cellulose, carboxymethylcellulose; hydroxypropyl methylcellulose; natural gums such as xanthan and carrageenan gum; sodium alginates; maltodextrin, low molecular weight dextrin; polyamino acids or peptides; proteins such as casein and/or caseinate (e.g. such as those commercialized by Lactips).
Preferred water-soluble polymers are polyvinyl alcohol, polyethylene oxide, methylcellulose and sodium alginate. For applications where a “plastic free” product is desired, the majority component of the water-soluble polymer layer may be a naturally derived polymer, such as sodium alginate. Preferably, the level of polymer in the water-soluble polymeric layer is at least 60%.
The water-soluble polymer has an average molecular weight (measured by gel permeation chromatography) of about 1,000 Da to about 1,000,000 Da, or any integer value from about 1,000 Da to about 1,000,000 Da, or any range formed by any of the preceding values such as about 10,000 Da to about 300,000 Da, about 20,000 Da to about 150,000 Da, etc. More specifically polyvinyl alcohol would have a molecular weight in the range of 20,000-150,000 Da. Polyethylene oxide would have a molecular weight in the range of 50,000 Da to 400,000 Da. Methylcelluloses would have a molecular weight in the range 10,000 Da to 100,000 Da. Methylcellulose may be methoxyl substituted, for example from about 18% to about 32% and may be hydroxy-propoxyl substituted, for example from about 4% to about 12%. Sodium alginate would have a molecular weight in the range 10,000 to 240,000 Da.
If homopolymer polyvinyl alcohol is used, the degree of hydrolysis could be 70-100%, or any integer value for percentage between 70% and 100%, or any range formed by any of these values, such as 80-100%, 85-100%, 90-100%, 95-100%, 98-100%, 99-100%, 85-99%, 90-99%, 95-99%, 98-99%, 80-98%, 85-98%, 90-98%, 95-98%, 80-95%, 85-95%, 90-95%, etc.
The water-soluble polymeric layers of the water-soluble film with an integrated water-dispersible nanocomposite barrier may contain disintegrants, plasticizers, surfactants, lubricants/release agents, fillers, extenders, antiblocking agents, detackifying agents, antifoams, or other functional ingredients. In the case of articles containing compositions for washing, the water-soluble polymeric layers may include functional detergent additives to be delivered to the wash water, for example organic polymeric dispersants, or other detergent additives.
It may be required for certain applications that the water-soluble polymeric layers contain disintegrants to increase the dissolution rate in water of the water-soluble film with an integrated water-dispersible nanocomposite barrier. Suitable disintegrants are, but are not limited to, corn/potato starch, methyl celluloses, mineral clay powders, croscarmellose (cross-linked cellulose), crospovidone (cross-linked polyvinyl N-pyrrolidone, or PVP), sodium starch glycolate (cross-linked starch). Preferably, the water-soluble polymeric layers comprise between 0.1% and 15%, more preferably from about 1% to about 15% by weight of disintegrants.
Preferably, the water-soluble polymeric layers may contain water-soluble plasticizers. Preferably, the water-soluble plasticizer is selected from water, polyols, sugar alcohols, and mixtures thereof. Suitable polyols include polyols selected from the group consisting of glycerol, diglycerol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols up to 400 Da molecular weight, neopentyl glycol, 1,2-propylene glycol, 1,3-propanediol, dipropylene glycol, polypropylene glycol, 2-methyl-1,3-propanediol, methylene glycol, trimethylolpropane, hexylene glycol, neopentyl glycol, and polyether polyols, or a mixture thereof. Suitable sugar alcohols include sugar alcohols selected from the group consisting of isomalt, maltitol, sorbitol, xylitol, erythritol, adonitol, dulcitol, pentaerythritol and mannitol, or a mixture thereof. In some cases, the plasticizer could be selected from the following list: ethanolamine, alkyl citrate, isosorbide, pentaerythritol, glucosamine, N-methylglucamine or sodium cumene sulfonate. Less mobile plasticizers such as sorbitol or polyethylene oxide can facilitate the formation of water-soluble polymeric layers with greater barrier properties than water-soluble polymeric layers including a more mobile plasticizer such as glycerol. In some circumstances when there is a desire to use as many naturally derived materials as possible, the following plasticizers could also be used: vegetable oil, polysorbitol, dimethicone, mineral oil, paraffin, C1-C3 alcohols, dimethyl sulfoxide, N, N-dimethylacetamide, sucrose, corn syrup, fructose, dioctyl sodium-sulfosuccinate, triethyl citrate, tributyl citrate, 1,2-propylene glycol, mono, di- or triacetates of glycerin, natural gums, citrates, and mixtures thereof. More preferably, water-soluble plasticizers are selected from glycerol, 1,2-propanediol, 20 dipropylene glycol, 2-methyl-1,3-propanediol, trimethylolpropane, triethylene glycol, polyethylene glycol, sorbitol, or a mixture thereof, most preferably selected from glycerol, sorbitol, trimethylolpropane, dipropylene glycol, and mixtures thereof. Preferably, the water-soluble polymeric layers comprise between 5% and 50%, more preferably between 10% and 40%, even more preferably from about 12% to about 30% by weight of plasticizers.
Preferably, the water-soluble polymeric layers of the present disclosure comprises a surfactant. Suitable surfactants may belong to the non-ionic, cationic, anionic or zwitterionic classes. Suitable surfactants are, but are not limited to, poloxamers (polyoxyethylene polyoxypropylene glycols), alcohol ethoxylates, alkylphenol ethoxylates, tertiary acetylenic glycols and alkanolamides (nonionic), polyoxyethylene amines, quaternary ammonium salts and quaternized polyoxyethylene amines (cationic), and amine oxides, N-alkylbetaines and sulfobetaines (zwitterionic). Other suitable surfactants are dioctyl sodium sulfosuccinate, lactylated fatty acid esters of glycerol and propylene glycol, lactylic esters of fatty acids, sodium alkyl sulfates, polysorbate 20, polysorbate 60, polysorbate 65, polysorbate 80, lecithin, acetylated fatty acid esters of glycerol and propylene glycol, and acetylated esters of 5 fatty acids, and combinations thereof. Preferably, the water-soluble polymeric layers comprise between 0.1% and 2.5%, more preferably from about 1% to about 2% by weight of surfactants.
Preferably the water-soluble polymeric layers of the present disclosure comprises lubricants/release agents. Suitable lubricants/release agents are, but are not limited to, fatty acids and their salts, fatty alcohols, fatty esters, fatty amines, fatty amine acetates and fatty amides. Preferred lubricants/release agents are fatty acids, fatty acid salts, fatty amine acetates, and mixtures thereof. Preferably, the water-soluble polymeric layers comprise between 0.02% to 1.5%, more preferably from about 0.1% to about 1% by weight of lubricants/release agents.
Preferably the water-soluble polymeric layers of the present disclosure comprises fillers, extenders, antiblocking agents, detackifying agents. Suitable fillers, extenders, antiblocking agents, detackifying agents are, but are not limited to, starches, modified starches, crosslinked polyvinylpyrrolidone, crosslinked cellulose, microcrystalline cellulose, silica, metallic oxides, calcium carbonate, talc, and mica. Preferably, the water-soluble polymeric layers comprise between 0.1% to 25%, more preferably from about 1% to about 15% by weight of fillers, extenders, antiblocking agents, detackifying agents. In absence of starch, the water-soluble polymeric layers comprise preferably between 1% to 5% by weight of fillers, extenders, antiblocking agents.
Preferably the water-soluble polymeric layers of the present disclosure comprises antifoams. Suitable antifoams are, but are not limited to, polydimethylsiloxanes and hydrocarbon blends. Preferably, the water-soluble polymeric layers comprise between 0.001% and 0.5%, more preferably from about 0.01% to about 0.5% by weight of antifoams.
Benefit agents may also be incorporated in the water-soluble polymeric layers. As such, it is possible to deliver benefit agents via articles such as pouches, which are not compatible with the product or composition inside the article. Examples of benefit agents are, but are not limited to, cleaning agents, soil suspending agents, anti-redeposition agents, optical brighteners, bleaches, enzymes, perfume compositions, bleach activators and precursors, shining agents, suds suppressor agents, fabric caring compositions, surface nurturing compositions.
Bittering agents may also be incorporated in the outer water-soluble polymeric layer, which is legally required in some regions for certain applications such as pods. Suitable bittering agents are, but are not limited to, naringin, sucrose octa-acetate, quinine hydrochloride, denatonium benzoate, or mixtures thereof. Preferably, the water-soluble polymeric layers comprise between 1 ppm and 5000 ppm, more preferably from about 100 ppm to about 2500 ppm, even more preferably from about 250 ppm to about 2000 ppm by weight of bittering agents.
The water-soluble film or water-soluble article of the present disclosure may be coated with antiblocking/detackifying agents. Suitable antiblocking/detackifying agents are, but are not limited to, talc, zinc oxide, silicas, siloxanes, zeolites, silicic acid, alumina, sodium sulphate, potassium sulphate, calcium carbonate, magnesium carbonate, sodium citrate, sodium tripolyphosphate, potassium citrate, potassium tripolyphosphate, calcium stearate, zinc stearate, magnesium stearate, starch, modified starches, clay, kaolin, gypsum, cyclodextrins or mixtures thereof.
There are numerous non-limiting embodiments for making water-soluble films with an integrated water-dispersible nanocomposite barrier described herein. As shown in
In one non-limiting embodiment of the method, a water-soluble polymeric layer 10 is formed onto the surface of a flat carrier (e.g. untreated PET film, stainless steel belt, fluorinated polymeric belt or any other suitable carrier materials); a water-dispersible nanocomposite barrier layer 20 is formed onto at least one of the surfaces 12, 14 of the previously formed water-soluble polymeric layer 10; a second water-soluble polymeric layer 30 is then formed onto at least one of the surfaces 112, 114 of the previously formed water-dispersible nanocomposite barrier layer; the flat carrier is finally removed from the resulting water-soluble nanocomposite barrier film.
To make water-soluble polymeric layer 10 or 30, an aqueous polymeric solution is typically formed by taking the water-soluble polymer as solid form and first dissolving it into water using moderate stirring, typically 20% water-soluble polymers for 80% water by weight. The aqueous polymeric solution is then further combined with other additives such as plasticizers under moderate stirring at high temperature. The aqueous polymeric solution is then coated onto a flat surface carrier (e.g. untreated PET film, stainless steel belt, fluorinated polymeric belt or any other suitable materials) and the water removed via IR, convective or diffusive drying process.
Without being limited to theory, it is believed that the most important material properties of the aqueous polymeric solution are: a) the solids content at given temperature between 20-95° C.; b) the resulting viscosity of the aqueous polymeric solution at that temperature, higher viscosity being better for maximum distinction/separation between the layers; c) the wetting of the aqueous polymeric solution either onto a flat carrier, or onto a water-dispersible nanoplatelets layer, or onto another water-soluble polymeric layer, higher wetting being better.
To make water-dispersible nanocomposite barrier layer 20, an aqueous nanocomposite dispersion is typically formed by taking the water-dispersible nanoplatelets as solid form and let them exfoliate in water first. The aqueous nanoplatelets dispersion is then further combined with an aqueous polymeric solution under moderate stirring. The resulting aqueous nanocomposite dispersion would typically contain 1% to 10% solids, depending on the coating process selected for the application. The aqueous nanocomposite dispersion is then coated onto a given substrate and the water is then removed via drying.
Without being limited to theory, it is believed that the most important material property of the nanocomposite are: a) the aspect ratio of the nanoplatelets (the higher aspect ratio being the better for barrier performance); b) the total exfoliation and dispersion of the nanoplatelets in water, to maximise the barrier performance; c) the choice of the polymeric filler, and the weight ratio between the nanoplatelets and the polymeric filler, to minimise the basal spacing between the nanoplatelets without phase separation, thus maximising the barrier performance.
Without being limited to theory, it is also believed that the most important processability properties of aqueous nanocomposite dispersions are: a) the viscosity of the aqueous nanocomposite dispersion, higher viscosities being better for maximum distinction/separation between the layers and therefore maximum barrier performance; b) the wetting of the aqueous nanocomposite dispersion either onto a water-soluble polymeric layer or onto another water-dispersible nanocomposite layer; c) the shear applied on the aqueous nanocomposite dispersion, the higher being the better for parallel nanoplatelets orientation to the barrier plane; d) the water removal from the dispersion via diffusive drying without generating defects such as pinholes or cracks in the nanocomposite barrier layer.
Many processes were tested for coating aqueous nanocomposite dispersions: wire rod coating, anilox roll coating, reverse roll coating, slot die extrusion coating, roll-to-roll coating, and spray coating. Aqueous extrusion coating via tailored slot die (e.g. FMP Technology, Coatema) proved the most reliable processes provided proper infeed of the aqueous nanocomposite dispersion. Coating processes delivering superior shearing of the aqueous nanocomposite dispersion are preferred, as superior shearing delivers superior parallel orientation of the nanoplatelets within the nanocomposite barrier layer, thus resulting in superior barrier performance. That barrier performance is nonetheless also dependent to the overall thickness of the water-dispersible nanocomposite barrier layer. Typically, the thickness of the water-dispersible nanocomposite barrier layer is in the range 0.1 μm to 10 μm to provide an adequate barrier performance whilst maintaining sufficient mechanical flexibility and mechanical resistance.
In another non-limiting embodiment of the method, the water-dispersible nanocomposite barrier layer 20 is obtained in multiple application steps of coating and drying the aqueous nanocomposite dispersion, each nanocomposite sublayer masking hypothetical defects in the underlaying nanocomposite sublayer, thus delivering maximum barrier performance. To do so, a first water-dispersible nanocomposite barrier sublayer is formed onto the water-soluble polymeric layer 10 according to any of the above-mentioned methods; Subsequently, one or more additional water-dispersible nanocomposite barrier sublayers may be added until the desired water-dispersible nanocomposite barrier layer thickness is obtained. Following this method, relatively thick water-dispersible nanocomposite barrier layers can be formed. Where increased optical transparency and mechanical flexibility is desired, the additional water-dispersible nanocomposite barrier sublayers can be separated by additional thin water-soluble polymeric sublayers. The various polymeric or barrier sublayers may have substantially the same chemical composition or a different one, to deliver different properties to the overall structure. The adhesion between the sublayers is solely provided by the molecular interactions between the water-soluble polymeric sublayers and the water-dispersible nanocomposite barrier sublayers. Similarly, the cohesion among the water-dispersible nanocomposite barrier sublayers is solely provided by the molecular interactions among the nanocomposite barrier materials.
The drying step is typically performed by conveyor dryers, such as those commercialized by Krönert under the brand name Drytec, by Coatema under the brand name ModulDry and/or by FMP Technologies GmbH (Erlangen, Germany) under the brand name SenDry or PureDry. In some embodiments, the drying substrate is guided through the hot air tunnel by a running belt (belt dryers), by multiple idlers (rolling dryers) or by multiple hot air nozzles (floatation dryers). Without being limited to theory, it is believed that the most important parameters of the drying process are: a) the residence time of the drying substrate into the hot air tunnel, typically about 50 s for 60μ thick aqueous polymeric solution containing 25% solids; b) the temperature profile of the hot air in the tunnel, typically up to about 95° C.; c) the velocity of the hot air flowing above the substrate, typically about 25 m/s. The heating system can be electrical, thermal oil, steam or gas-fire based.
The water-soluble film of the present disclosure may contain residual moisture depending on the hygroscopy of the water-soluble film components and the isotherm of the water-soluble film at given temperature and humidity conditions measured by Karl Fischer titration. For instance, water-soluble polyvinyl-alcohol films may contain about 4-8% residual moisture at 23° C. and 50% r.H.
The water-soluble film with an integrated water-dispersible nanocomposite barrier described herein can be formed into articles, including but not limited to those in which water-soluble film with an integrated water-dispersible nanocomposite barrier is used as a packaging material. Such articles include, but are not limited to water-soluble pouches, sachets, and other containers. Water-soluble pouches and other such containers that incorporate the water-soluble film with an integrated water-dispersible nanocomposite barrier described herein can be made in any suitable manner known in the art. The water-soluble film with an integrated water-dispersible nanocomposite barrier can be provided either before or after forming the same into the final article. In either case, in certain embodiments it is desirable when making such articles, that the surface of a water-soluble polymeric layer onto which the barrier layer is applied, forms an outer surface of the article.
There are number of processes for making water-soluble articles. These include but are not limited to processes known in the art such as: vertical form fill sealing processes, horizontal form fill sealing processes, and formation of the pouches in molds on the surface of a circular drum. In vertical form fill sealing processes, a vertical tube is formed by folding a substrate. The bottom end of the tube is sealed to form an open pouch. This pouch is partially filled allowing a head space. The top part of the open pouch is then subsequently sealed together to close the pouch, and to form the next open pouch. The first pouch is subsequently cut, and the process is repeated. The pouches formed in such a way usually have pillow shape. Horizontal form fill sealing processes use a die having a series of molds therein. In horizontal form fill sealing processes, a substrate is placed in the die and open pouches are formed in these molds, which can then be filled, covered with another layer of substrate, and sealed. In the third process (formation of pouches in molds on the surface of a circular drum), a substrate is circulated over the drum and pockets are formed, which pass under a filling machine to fill the open pockets. The filling and sealing take place at the highest point (top) of the circle described by the drum, e.g. typically, filling is done just before the rotating drum starts the downwards circular motion and sealing just after the drum starts its downwards motion. In any of the processes that involve a step of forming of open pouches, the substrate can initially be molded or formed into the shape of an open pouch using thermoforming, vacuum forming, or both. Thermoforming involves heating the molds and/or the substrate by applying heat in any known way such as contacting the molds with a heating element, or by blowing hot air or using heating lamps to heat the molds and/or the substrate. In the case of vacuum forming, vacuum assistance is employed to help drive the substrate into the mold. In other embodiments, the two techniques can be combined to form pouches, for example, the substrate can be formed into open pouches by vacuum forming, and heat can be provided to facilitate the process. The open pouches are then filled with the composition to be contained therein. The filled, open pouches are then closed, which can be done by any method. In some cases, such as in horizontal pouch forming processes, the closing is done by continuously feeding a second material or substrate, such as a water-soluble substrate, over and onto the web of open pouches and then sealing the first substrate and second substrate together. The second material or substrate can comprise the water-soluble polymeric layer 10 described herein. It may be desirable for the surface of the second substrate onto which the barrier layer is applied, to be oriented so that it forms an outer surface of the pouch.
In such a process, the first and second substrates are typically sealed in the area between the molds, and, thus, between the pouches that are being formed in adjacent molds. The sealing can be done by any method. Methods of sealing include heat sealing, solvent welding, and solvent or wet sealing. The sealed webs of pouches can then be cut by a cutting device, which cuts the pouches in the web from one another, into separate pouches. Processes of forming water-soluble pouches are further described in U.S. patent application Ser. No. 09/994,533, Publication No. US 2002/0169092 A1, published in the name of Catlin, et al.
The sealing mechanism can be thermal heat sealing, water sealing, moisture sealing, ultrasonic sealing, infrared sealing, or any other type of sealing deemed suitable.
As shown in
The pouches 300 formed by the foregoing methods, can be of any form and shape which is suitable to hold the composition 400 contained therein, until it is desired to release the composition 400 from the water-soluble pouch 300, such as by immersion of the water-soluble pouch 300 in water. The pouches 300 can comprise one compartment, or two or more compartments (that is, the pouches can be multi-compartment pouches). In one embodiment, the water-soluble pouch 300 may have two or more compartments that are in a generally superposed relationship and the pouch 300 comprises upper and lower generally opposing outer walls, skirt-like side walls, forming the sides of the pouch 300, and one or more internal partitioning walls, separating different compartments from one another. If the composition 400 contained in the pouches 300 comprises different forms or components, the different components of the composition 400 may be contained in different compartments of the water-soluble pouch 300 and may be separated from one another by a barrier of water-soluble material.
The pouches or other containers 300 may contain a unit dose of one or more compositions 400 for use as/in laundry detergent compositions, automatic dishwashing detergent compositions, hard surface cleaners, stain removers, fabric enhancers and/or fabric softeners, hair care compositions, beauty care compositions, oral care compositions, health care compositions, personal cleansing compositions, and household cleansing compositions; for example shampoo, conditioner, mousse, face soap, hand soap, body soap, liquid soap, bar soap, moisturizer, skin lotion, shave lotion, toothpaste, mouthwash, hair gel, hand sanitizer, laundry detergent compositions dishwashing detergent, automatic dishwashing machine detergent compositions, cosmetics, and over-the-counter medication, razors, absorbent articles, wipes, hair gels, food and beverage, animal food products, menstrual cups, exfoliating pads, electrical and electronic consumer devices, brushes, applicators, ear plugs, eye masks, eye patches, face masks, agricultural products, plant food, plant seeds, insecticides, ant killers, alcoholic beverages, animal food products, electronics, pharmaceuticals, confectionary, petfood, pet healthcare products, cannabis derived products, hemp derived products, CBD based products, other products derived from drugs other than cannabis, vitamins, non-pharmaceutical natural/herbal “wellness” products, food and beverage and new product forms where contact with small amounts of water could create premature pouch dissolution, unwanted pouch leakage and/or undesirable pouch-to-pouch stickiness. Typical absorbent articles of the present disclosure include but are not limited to diapers, adult incontinence briefs, training pants, diaper holders, menstrual pads, incontinence pads, liners, absorbent inserts, pantiliners, tampons, period pants, sponges, tissues, paper towels, wipes, flannels, and the like. Pouch stickiness from migrating chemistries from within the formulated product will also be reduced. The composition 400 in the pouches 300 can be in any suitable form including, but not limited to: liquids, gels, pastes, creams, solids, granules, powders, capsules, pills, dragees, solid foams, fibers, etc. The different compartments of multi-compartment pouches 300 may be used to separate incompatible ingredients. For example, it may be desirable to separate bleaches and enzymes into separate compartments. Due to likely improvements in barrier performance, the dyes and perfumes typically used in some Fabric and Home Care products should have greater stability inside these new pouches. Other forms of multi-compartment embodiments may include a powder-containing compartment in combination with a liquid-containing compartment. Additional examples of multiple compartment water-soluble pouches are disclosed in U.S. Pat. No. 6,670,314 B2, Smith, et al.
The water-soluble pouches 300 may be dropped into any suitable aqueous solution (such as hot or cold water), whereupon water-soluble film with an integrated water-dispersible nanocomposite barrier 100 forming the water-soluble pouches 300 dissolves to release the contents of the pouches. The water-soluble film with an integrated water-dispersible nanocomposite barrier 100 described herein can also be used for coating products and other articles. Non-limiting examples of such a product are laundry detergent tablets or automatic dishwashing detergent tablets. Other examples include coating products in the food and beverage category where contact with small amounts of water could create premature dissolution, unwanted leakage and/or undesirable stickiness.
Additional product forms (articles) include, disposable aprons, laundry bags, disposable hospital bedding, skin patches, face masks, disposable gloves, disposable hospital gowns, medical equipment, skin wraps, agricultural mulch films, shopping bags, sandwich bags, trash bags, emergency blankets and clothing, building/construction wrap & moisture resistant liners, primary packaging for shipping, such as envelopes and mailers, non-absorbent clothing articles that can be used to encase clothing items, for example dresses, shirts, suits, and shoes.
When testing and/or measuring a material, if the relevant test method does not specify a particular temperature, then the test and/or measure is performed on specimens at 23° C. (±3° C.), with such specimens preconditioned at that temperature. When testing and/or measuring a material, if the relevant test method does not specify a particular humidity, then the test and/or measure is performed on specimens at 35% (±5%), with such specimens preconditioned at that humidity. Testing and/or measuring should be conducted by trained, skilled, and experienced personnel, according to good laboratory practices, via properly calibrated equipment and/or instruments.
1) Film Dispersion/Dissolution in Water
This test method measures the total time for the complete dissolution of a particular film specimen when the test is performed according to Slide Dissolution Test, which is Test Method 205 (MSTM 205), as set forth in paragraphs 116-131 of US published patent application US20150093526A1, entitled “Water-soluble film having improved dissolution and stress properties, and packets made therefrom”. The entire publication is hereby incorporated as reference. The dissolution test method used herein is the same as that set forth in US20150093526A1, except that the temperature of the distilled water is 23° C., the beaker diameter is about 10 cm and the test duration limit is 24 hours. The results are Individual and Average Disintegration Time (the time to where the film beaks apart) and Individual and Average Dissolution Time (the time to where no solid residues are visible). Unless otherwise specified, Dissolution Test Method uses distilled water maintained at 23° C. The Dissolution Test Method does not apply to materials other than films having an overall thickness equal or less than 3 mm. A film of the present disclosure is considered water-soluble if the average dissolution measured according to this dissolution test method takes less than 24 hours.
2) Water Vapour Transmission Rate (WVTR)
This test method is performed according to ASTM F1249-13 under the following test conditions: temperature of 40° C. (±0.56° C.) and relative humidity of 50% (±3%) or 90% (±3%). The water vapour transmission rate was measured by the instrument Permatran-W Model 3/33 from Mocon in Minneapolis (USA) and is reported in [g/m2/day]. For materials outside of the Scope (§ 1.1) of ASTM F-1249-13, the water vapour transmission rate test method does not apply.
3) Scanning Electron Microscopy (SEM)
SEM images were recorded with the instrument Zeiss Ultra Plus from Carl Zeiss AG (Oberkochen, Germany) operating at 5.0 kV and equipped with an in-lens secondary electron detector. The sample specimen was prepared by cutting via scalpel a cross-section of the film at room temperature condition.
4) Transmission Electron Microscopy (TEM)
TEM images of the sandwich-layered film cross-sections were recorded employing the microscope JEOL-JEM-2200FS (JEOL GmbH, Germany). Cross-sections were prepared from the films by applying a JEOL EM-09100IS Cryo Ion Slicer (JEOL GmbH, Germany).
5) Basal Spacing Via X-Ray Diffraction (XRD)
X-ray diffraction was measured on Bragg-Brentano-type instrument (Empyrean Malvern Panalytical BV, The Netherlands) applying Cu Kα radiation (λ=1.54187 Å). The diffractometer was equipped with a PIXcel-1D detector. The X-ray diffraction patterns were analyzed using Malvern Panalytical's Highscore Plus software to determine the basal spacing (door).
6) Small-Angle X-Ray Scattering (SAXS)
As preliminary, the birefringence optical property of the dispersion was checked with a self-made crossed-polarizer. SAXS analysis of the nematic dispersions were then conducted in 1 mm glass capillaries (Hilgenberg, Germany) at 23° C. by using the system Ganesha Air (SAXSLAB, Denmark). The system was equipped with a rotating anode copper X-ray source MicroMax 007HF (Rigaku Corp., Japan) and a position-sensitive detector PILATUS 300K (Dectris, Switzerland). The sample-to-detector positions were adjustable, covering a wide range of scattering vectors q.
Preparation of Water-Soluble Polyvinyl Alcohol (PVOH) Solution (30% Solids)
700 g of bi-distilled water was heated to 85° C. in a beaker. 240 g of solid PVOH powder (Selvol 205 ex Sekisui Chemical, Japan), 30 g of glycerol (CremerGLYC 3109921 ex Cremer Oleo, Germany) and 30 g of sorbitol (Neosorb® P 100 T, Roquette, France) were added under magnetic stirring at 200 rpm. The solution was maintained under reflux at 85° C. for 2 hours under stirring up to 200 rpm to dissolve all the solid components. Prior of usage, the PVOH solution was homogenized and defoamed under vacuum (50 mbar) for 10 min under stirring up to 2500 rpm using a SpeedMixer DAC 400.2 VAC-P equipment ex Hauschild (Germany).
Preparation of Water-Dispersible Hectorite Dispersion (6% Solids)
Sodium hectorite [Na0.5]inter[Mg2.5Li0.5]oct[Si4]tetO10F2 was synthesized, as follows: High purity reagents of SiO2 (Merck, fine granular, washed and calcined quartz), LiF (ChemPur, 99.9%, powder), MgF2 (ChemPur, 99.9%, 3-6 mm pieces, fused), MgO (Alfa Aesar, 99.95%, 1-3 mm fused lumps) and NaF (Alfa Aesar, 99.995%, powder) were carefully weighed according to the composition in the formula. Crucibles made of molybdenum (25 mm outer diameter, 21 mm inner diameter, 180 mm length) were supplied by Plansee SE (Reutte, Austria). These crucibles were first heated up to 1600° C. under vacuum inside a quartz tube placed within a copper based high-frequency induction heating coil for cleaning purpose. The reagents were then added into a crucible under argon atmosphere (glovebox) and heated up to 1200° C. under vacuum to remove any residual water. The crucible was then sealed with a molybdenum lid by heating both parts up to the melting point of molybdenum. The sealed crucible was thus placed horizontally in a graphite furnace under argon atmosphere and rotated at 1750° C. for 80 min. The crucible was then opened, the resulting sodium hectorite was collected, grinded via planetary ball mill, and dried in a clean crucible at 250° C. under argon atmosphere for 14 hours. The crucible was then sealed with a molybdenum lid and annealed at 1045° C. for 6 weeks in a graphite furnace to increase the homogeneity of the sodium hectorite. The material was then placed in a desiccator at (23° C., 43% rH) to reach the hydrated formula [Na0.5]inter[Mg2.5Li0.5]oct[Si4]tetO10F2·[H2O]2. Bi-distilled water was then added to reach 6% hectorite dispersion in water. Finally, the dispersion was left 1 week at 23° C. for spontaneous delamination of the hectorite nanoplatelets, thus yielding maximum aspect ratio of the hectorite nanoplatelets. The aspect ratio ranges between 400 and 40000.
Preparation of Water-Dispersible Hectorite/PEG Nanocomposite Dispersion (1% Solids)
117 g of 6% hectorite dispersion in water was firstly diluted at 23° C. with 583 g bi-distilled water to obtain 700 g of 1% hectorite dispersion in water. 3 g of PEG 10,000 g/mol supplied by Sigma-Aldrich was separately dissolved at 23° C. with 297 g bi-distilled water to obtain 300 g of 1% PEG 10000 solution. Both dispersion and solution were mixed together at 23° C. to deliver 1000 g of 1% hectorite/PEG 10000 dispersion in water (ratio 70:30). Birefringence optical properties indicate the self-orientation of the hectorite nanoplatelets parallel to each other in the dispersion. 1D small-angle X-ray scattering (SAXS) analysis confirmed the nematic liquid crystal state of the dispersion.
Preparation of Water-Dispersible Hectorite/PEO Nanocomposite Dispersion (1% Solids)
117 g of 6% hectorite dispersion in water was firstly diluted at 23° C. with 583 g bi-distilled water to obtain 700 g of 1% hectorite dispersion in water. 3 g of PEO 2000000 g/mol supplied by Sigma-Aldrich was separately dissolved with 297 g bi-distilled water at 80° C. under agitation to obtain 300 g of 1% PEO 2000000 solution. Both dispersion and solution were mixed together at 23° C. to deliver 1000 g of 1% hectorite/PEO 2000000 dispersion in water (ratio 70:30). Birefringence optical properties indicate the self-orientation of the hectorite nanoplatelets parallel to each other in the dispersion. 1D small-angle X-ray scattering (SAXS) analysis confirmed the nematic liquid crystal state of the dispersion.
Preparation of Water-Dispersible Hectorite/PVOH Nanocomposite Dispersion (5% Solids)
333 g of 6% hectorite dispersion in water was firstly diluted at 23° C. with 67 g bi-distilled water to obtain 400 g of 5% hectorite dispersion in water. 30 g of PVOH grade Poval 10-98 supplied by Kuraray was separately dissolved with 570 g bi-distilled water at 80° C. under agitation to obtain 600 g of 5% PVOH solution. Both dispersion and solution were mixed together at 23° C. to deliver 1000 g of 5% hectorite/PVOH dispersion in water (ratio 40:60). Birefringence optical properties indicate the self-orientation of the hectorite nanoplatelets parallel to each other in the dispersion. 1D small-angle X-ray scattering (SAXS) analysis confirmed the nematic liquid crystal state of the dispersion.
Lab-Scale Making of Water-Soluble Film with Integrated Water-Dispersible Nanocomposite Barrier
All aqueous solutions/dispersion were homogenized at 2500 rpm and degassed at (23° C., 50 mbar) using a SpeedMixer DAC 400.2 VAC-P from Hauschild & Co KG (Hamm, Germany) for 5 min. prior to their usage. A 36μ thick polyethylene terephthalate (PET) film grade Optimont® 501 ex Bleher Folientechnik GmbH (Germany) was used as carrier without further surface treatment. As next step, the carrier film was coated with 30% PVOH solution (described previously) using an automated doctor blade coating equipment (ZAA 2300, Zehntner GmbH Testing Instruments, Switzerland). The speed was set to 15 mm/s, and the blade height was set to 250 μm. The wet coating was dried for 30 min. at 60° C. and the resulting dry layer was about 28 μm thick and composed of 80% PVOH grade Selvol 205, 10% glycerol, 10% sorbitol.
1) Water-Soluble Film with Integrated Water-Dispersible Hectorite/PEG Nanocomposite Barrier
In one embodiment, the Hectorite/PEG nanocomposite barrier was applied by spray coating using a fully automated spray coating system (SATA 4000 LAB HVLP 1.0 mm spray gun ex SATA (Germany). The distance between the spraying nozzle and the PVOH coated PET film was set to 17 cm. Subsequently, the 1% Hectorite/PEG nanocomposite dispersion (described previously) was fed under constant 4 bar pressure in the spray nozzle and applied onto PVOH coated PET film. The wet coating was dried for 30 min at 50° C. and the resulting dry layer was 40 nm thick. The spraying and drying cycle was repeated 100 times, and the resulting dry layer was 4 μm thick and composed of 70% hectorite and 30% PEG 10000 g/mol. As next step, the nanocomposite barrier was coated with 30% PVOH solution (described previously) using the automated doctor blade coating equipment (described previously) and the resulting dry layer was about 26 μm thick and composed of 80% PVOH, 10% glycerol, 10% sorbitol. At this point, the carrier PET film was removed, thus delivering a water-soluble film with an integrated nanocomposite barrier.
2) Water-Soluble Film with Integrated Water-Dispersible Hectorite/PEO Nanocomposite Barrier
In one embodiment, the Hectorite/PEO nanocomposite barrier was applied by spray coating using a fully automated spray coating system (SATA 4000 LAB HVLP 1.0 mm spray gun ex SATA (Germany). The distance between the spraying nozzle and the PVOH coated PET film was set to 17 cm. Subsequently, the 1% Hectorite/PEO nanocomposite dispersion (described previously) was fed under constant 4 bar pressure in the spray nozzle and applied onto PVOH coated PET film. The wet coating was dried for 30 min at 50° C. and the resulting dry layer was 40 nm thick. The spraying and drying cycle was repeated 100 times, and the resulting dry layer was 4 μm thick and composed of 70% hectorite and 30% PEO 2000000 g/mol. As next step, the nanocomposite barrier was coated with 30% PVOH solution (described previously) using the automated doctor blade coating equipment (described previously) and the resulting dry layer was about 26 μm thick and composed of 80% PVOH, 10% glycerol, 10% sorbitol. At this point, the carrier PET film was removed, thus delivering a water-soluble film with an integrated nanocomposite barrier.
3) Water-Soluble Film with Integrated Water-Dispersible Hectorite/PVOH Nanocomposite Barrier
In one embodiment, the Hectorite/PVOH nanocomposite barrier was applied by doctor blading coating equipment (ZAA 2300, Zehntner GmbH Testing Instruments, Switzerland). The speed was set to 15 mm/s, and the blade height was set to 100 μm. The 5% Hectorite/PVOH nanocomposite dispersion (described previously) was applied onto PVOH coated PET film. The wet coating was dried for 4 hours at 60° C. and composed of 40% hectorite and 60% PVOH grade Poval 10-98. As next step, the nanocomposite barrier was coated with 30% PVOH solution (described previously) using the same equipment and the resulting dry layer was about 26 μm thick and composed of 80% PVOH, 10% glycerol, 10% sorbitol. At this point, the carrier PET film was removed, thus delivering a water-soluble film with an integrated nanocomposite barrier.
The below comparative example consists of water-soluble films with an integrated barrier layer made of non-dispersible barrier materials in water, therefore not suitable for this application.
Preparation of the PVDC Solution (20% Solids)
1000 g of methyl-ethyl-ketone (MEK) and ethyl-acetate (EA) solvent mixture (60:40) is heated up in a glass beaker to 50° C. inside a protective fume hood. 200 g of polyvinylidene dichloride, powder grade Resin F310 ex Asahi Kasei is added under magnetic stirring. Once completed, the stirring level is increased to the maximum level and the heating is switched off. After about 2 hours of constant stirring at maximum level, the PVDC powder is completely dissolved. The solution is stored over night at room temperature (RT) to eliminate any residual foam.
A. Water-Soluble Film with Integrated Water-Insoluble PVDC Barrier
In one embodiment, a first water-soluble polymeric layer was formed by coating 50μ aqueous PVOH solution (30% solids) at 80° C. onto an untreated PET carrier film (Hostaphan RN 50-350 ex Mitsubishi) via anilox roll and the water removed via convective drier from Drytec set at 95° C.
A second and third water-soluble polymeric layers were added onto the first water-soluble polymeric layer via the same process. The resulting dry layer was 39μ thick and its composition was 80% PVOH grade Selvol 205 ex Sekisui Chemicals, 9.5% glycerol, 9.5% sorbitol and 1% Hecostat from Hecoplast. The non-dispersible PVDC barrier was then added by coating 30μ PVDC solution in MEK/EA at 50° C. onto the water-soluble polymeric layer via anilox roll and the MEK/EA solvent removed via convective dryer from Drytec set at 95° C. The resulting dry layer was 3μ thick and its composition was 100% PVDC grade F310 ex Asahi Kasei. One additional water-soluble polymeric layer was added by coating 50μ aqueous PVOH solution at 80° C. onto the non-dispersible PVDC barrier layer via anilox roll and the water removed via convective drier from Drytec set at 95° C. The resulting dry layer was 15μ thick and its composition was 80% PVOH grade Selvol 205 ex Sekisui Chemicals, 10% glycerol, 10% sorbitol.
As shown in table 2 above, although the PVDC barrier layer delivers low WVTR, water insoluble PVDC does not meet the requirements of the invention according to this disclosure.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”
Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this disclosure.
| Number | Date | Country | |
|---|---|---|---|
| 63303610 | Jan 2022 | US |
