Alginate-starch film

Abstract

The present invention relates to the field of heat-sealable, highly biodegradable films comprising completely natural, plant-derived polymers, including salts of alginic acid and carbohydrates. The films of the present invention can be used to package products, such as powdered and liquid products, into pouches at commercially viable production rates using commercially available heat-sealing equipment. In particular, the films of the present invention can be used in vertical form-fill-seal (VFFS) packaging equipment without the need for equipment modifications. The films of the present invention use natural materials that are readily available, inexpensive, and do not require extensive or expensive chemical modification. The films do not contain synthetic polymers and are rapidly and completely biodegradable. The films can be soluble or insoluble.

Description

[Technical Field]

[0001] The present invention relates to the field of heat-sealable, highly biodegradable films comprising completely natural, plant-derived polymers, including salts of alginic acid and carbohydrates. The films of the present invention can be used to package products, such as powdered and liquid products, into pouches at commercially viable production rates using commercially available heat-sealing equipment. In particular, the films of the present invention can be used in vertical-form-fill-seal (VFFS) packaging equipment without the need for equipment modifications. The films of the present invention use natural materials that are readily available, low-cost, and do not require extensive or expensive chemical modification. The films do not contain synthetic polymers and are rapidly and completely biodegradable. The films can be soluble or insoluble. [Background technology]

[0002] Packaging materials made from renewable materials are becoming increasingly interesting and important as environmental pressures drive a move away from petroleum-based raw materials. Such packaging materials include films that are particularly useful for wrapping and / or enveloping products. Examples of products that use films for packaging include sachets and bags. It is highly desirable for packaging materials to not only be obtained from renewable materials, but also be highly biodegradable to minimize waste disposal issues. Typically, products made from renewable natural raw materials are highly biodegradable unless they are chemically modified. Chemical modification can dramatically reduce the biodegradability profile.

[0003] Some packaging films combine natural and synthetic materials. Such products typically have an improved environmental profile compared to comparable products that use only synthetic materials. In addition, such products can provide an optimal balance of physical properties such as strength and barrier resistance. However, the use of synthetic materials, typically non-biodegradable materials, inherently means that the biodegradation profile is not as good as that of materials that use entirely natural raw materials.

[0004] Water-soluble films made from polyvinyl alcohol are widely available and are widely used, for example, in detergent packaging. In many cases, these water-soluble films are marketed as environmentally friendly. An example is Monosol M-8630 manufactured by Monosol (now Kuraray). While typically soluble, these films are poorly biodegradable in marine biodegradation tests and can accumulate in the environment.

[0005] Some product and packaging applications require that the packaging material itself be edible. In this context, "edible" means that all of the materials are classified as safe for eating, regardless of whether they are digestible by humans or capable of providing human nutrition.

[0006] Many biopolymers, or naturally derived materials, can be used to make packaging films. Examples of widely used biopolymer films include starch and cellulose-based films. Starches are particularly popular due to their low cost and ready availability. Typically, starches are modified to improve their processability and functionality. One example of a modified starch is hydroxypropylated amylose starch. Other substituents can be hydroxyethyl or hydroxybutyl to form hydroxyether substitutions, or anhydrides such as maleic phthalic anhydride or octenyl succinic anhydride can be used to produce starch ester derivatives. Starch films typically have high tensile strength at moderate humidity (e.g., 30%-50% at 20°C), but typically become much weaker at higher humidity unless they are highly chemically modified. In particular, many starch films are highly susceptible to storage at low temperatures due to the starch's tendency to retrogradation.

[0007] Many starch-based products, such as compostable bags, contain significant levels of polybutene adipate terephthalate (PBAT) to improve their processability and physical properties. PBAT is a biodegradable synthetic polymer. However, PBAT is clearly derived from non-renewable sources. An example of a starch-based film is that sold by Plantic Technologies Ltd (now part of Kuraray). Plantic films contain modified starch and are available as both monolayer and multilayer films.

[0008] Cellulose-based polymers and materials can also form films, and these polymers and materials are also widely used. Cellulose films are generally made from so-called "regenerated" cellulose. In this process, cellulose fibers are dissolved in carbon disulfide under alkaline conditions to form viscose. The viscose is then contacted with an acidic solution to "regenerate" the cellulose. This process is resource- and energy-intensive, and the resulting cellulose film is not entirely water-soluble or water-dispersible and does not heat-seal. Regenerated cellulose is used in NatureFlex film, a compostable cellulose-based packaging film sold by Futamura. Other cellulose materials include hypoxypropyl methyl cellulose (HPMC) and carboxymethyl cellulose (CMC). HPMC films have long been used in the medical field as tablet coatings. However, HPMC itself requires considerable effort to synthesize and is therefore relatively expensive. HPMC films are not fully biodegradable due to the level of synthetic modification.

[0009] Other biopolymers that can be used to make films include proteins, both animal- and plant-based. Examples of animal proteins that can be used to form films include gelatin, collagen, and casein. Gelatin is very widely used as a tablet and capsule material. Casein (a milk protein collected from whey) has long been used to make plastic materials and can be formed into soluble, thermoformable pellets or sheets. While such materials have very good biodegradability profiles, they are animal-derived. As a result, some people have moral and ethical concerns regarding the use of such products. Furthermore, from the perspective of efficient resource use, it is generally more environmentally preferable to be able to use plant materials directly rather than indirectly by feeding plants to animals.

[0010] The use of biopolymers to make films and coatings is becoming increasingly widespread, and much effort continues to be focused on using naturally derived, renewable materials as replacements for non-renewable raw materials such as petroleum. The field is broad and extensive, and the examples provided below are for illustrative purposes.

[0011] Many biopolymers, including plant- and animal-based materials, are in use. Examples of animal-based materials used to make films and coatings include collagen, gelatin, chitosan, shellac, and casein. Examples of plant-based materials used include starch, cellulose, proteins (including pea, soy, corn, and potato), alginate, carrageenan and other gums, pullulan, pectin, and others. The reasons for using biopolymers in these applications range from the desire to use renewable raw materials, to having more biodegradable materials, to using more biocompatible materials for medical applications, and even to providing edible packaging. Films and other packaging materials made from biopolymers can be soluble or insoluble. For both ethical reasons and resource efficiency, there is a need to use plant-based biopolymers rather than animal-based biopolymers. Alginate, commonly obtained from seaweed, is an attractive biopolymer because it can be made into a robust film. However, alginate films do not easily heat seal.

[0012] Biopolymers are complex materials and are often more difficult to process and handle than synthetic polymers. Typically, biopolymers are sensitive to moisture and lose strength in humid environments. This vulnerability of biopolymers to moisture is typically an inherent characteristic of their natural origin and is a major limitation to their more widespread use. Other issues include poorer thermoplastic properties, including heat sealing, of biopolymer films. Rapid and effective heat sealing without thermal damage is important for the industrial production of pouches and many packaging formats. The challenges associated with many biopolymers, particularly their poor water resistance, mean that to obtain films with improved properties, biopolymers are often chemically modified to improve their properties, blended with synthetic polymers, or laminated with other materials, including other biopolymers.

[0013] Polyhydroxyalkanoates are increasingly being used due to their good thermoplastic properties. PHAs are natural biopolymers obtained from microbial fermentation, but they are slow to biodegrade and insoluble.

[0014] An example of an animal-based biopolymer is casein. EP 3728477 (A1) describes a thermoplastic casein composition and a packaging film made from the thermoplastic casein. U.S. Pat. No. 9662400 (B2) describes a chitosan film useful for medical applications. U.S. Pat. No. 6448378 (B2) describes a soluble collagen film used to deliver drug therapeutics. A large-scale application of many edible films, including (among others) collagen, alginate, and protein-based films, is for sausage casings. Sausage casings do not need to be heat-sealed. U.S. Pat. No. 3408916 describes a collagen film used for sausage casings. U.S. Pat. No. 6730340 (B1) describes a plant-based biopolymer blend for sausage casings based on a mixture of carrageenan and gellan gum.

[0015] U.S. Patent No. 10,092,925 (B2) and Patent No. 6,010,068 (B2) describe production processes for making alginate films. Heat sealing is not mentioned. JP 05-30891 (A) describes the use of blends of alginate with other polysaccharides, primarily pullulan. The patent states that pure alginate films do not heat seal. Blending high levels of pullulan with alginate results in films that are sealable and insoluble. Pullulan is expensive to use on a large scale as the main component of films.

[0016] Chemically modifying or blending natural polymers with synthetic polymers can improve the physical and processing properties of films made from these materials, but often reduces overall biodegradability and requires the use of complex, non-renewable materials.

[0017] Starch is inexpensive and can be modified to improve its properties. U.S. Patent No. 5,498,662 describes a gas barrier film comprising a blend of poly(meth)acrylic acid and starch. Thermoplastic starch is available under the trade name MATER-BI supplied by Novamont. U.S. Patent Application Publication No. 2004 / 0242732 (A1), European Patent No. 2,496,644 (B1), and International Publication No. 2011080623 (A2) describe biodegradable polymer compositions based on modified starch and synthetic polymers. These materials can be used to form films.

[0018] Cellulose derivatives, particularly cellulose ethers such as hydroxypropylmethylcellulose, are commonly used to create films for medical applications. European Patent No. 1045000(B1) describes ingestible HPMC films. While such materials are often safe for ingestion, they require a high level of synthetic modification. HPMC is often used in drug coatings due to its selective pH solubility.

[0019] The use of laminated films to overcome some of the limitations of single biopolymers is known. These laminates can include two or more layers. One of the layers can be a synthetic polymer. The synthetic polymer can be partially or completely biodegradable. While the use of synthetic polymers is less preferred than the use of biopolymers due to the use of non-renewable materials, the use of a combination of natural and synthetic materials can still be preferable compared to fully synthetic materials. Synthetic polymer layers or highly modified biopolymer layers typically provide enhanced barrier properties or enhanced heat-sealing properties. The layers can preferably be different biopolymers.

[0020] A common type of biopolymer-based laminate is modified starch laminated with a synthetic polymer. An example of this is EP 1581388 (B1), which describes a co-extrusion process for producing modified starch films laminated with biodegradable polyesters. U.S. Patent No. 8715816 describes a multilayer film comprising a thermoplastic starch layer and a thermoplastic polyester layer. Another example of a composite laminate film is when a synthetic polymer is used to provide a heat-sealing layer.

[0021] European Patent No. 2013290(B1) describes a silk protein laminated film in which silk protein is laminated with another layer, which can be either a different protein such as collagen or a synthetic polymer. Heat sealing is not mentioned, and the use of animal products is not preferred.

[0022] Publication No. 2009-061108(A) discloses an edible laminated film comprising (among other things) an alginate layer and a starch layer that can be used to form a package. The starch layers can be sealed together. No details of the film or materials are given, nor are any details given regarding the production of an article comprising the laminated film.

[0023] Publication No. 2016-034841(A) discloses an edible laminated film comprising one layer of shellac and another layer of either starch, gelatin, or pullulan. Packets can be made from the laminated film with the shellac layer on the inside. Shellac is an animal product, and production details are not provided.

[0024] Published Patent Application No. 2010-136685(A) describes a laminated film containing a cationic biopolymer, typically chitosan, and an anionic biopolymer, typically gelatin. One biopolymer is cast, and then a second biopolymer is cast on top. The resulting film is insoluble. The film can be heat-sealed, but no details are given, and the use of animal products is not recommended.

[0025] U.S. Patent No. 5,089,307(A) describes an edible heat-sealable laminated film. The film comprises a layer of carrageenan and a sealing layer selected from casein, soy protein, or gelatin. Alginate is not disclosed.

[0026] Patent No. 4063481 (B2) describes a multi-layer packaging film in which one layer contains regenerated cellulose, and other layers contain acrylic resins and other synthetic resins.

[0027] European Patent No. 3721721 (A1) describes an edible multilayer film containing three layers of different "hydrocolloid substances," where the first layer may be alginate, the second layer may contain starch, and the third layer may contain agar. The film can be heat-sealed, but production details are not given.

[0028] Therefore, there is a need to develop an alginate-based film with tunable solubility that has sufficiently robust mechanical properties for use as a packaging film, including the ability to withstand handling during the manufacturing process and transportation and storage at low temperatures. A preferred feature is that the food packaging be edible to further minimize waste and increase consumer convenience. Summary of the Invention

[0029] Viewed from a first aspect, the present invention provides a film comprising: a first layer, based on a total weight of the first layer: At least 20% by weight of one or more monovalent salts of alginic acid, and a first layer comprising at least 5 wt. % of one or more organic plasticizers; a second layer, based on the total weight of the second layer: one or more carbohydrates other than alginic acid and its salts; at least 5% by weight of one or more organic plasticizers, and a second layer comprising less than 20% by weight of alginate; A film is provided in which one surface of the second layer is sealed to one surface of the first layer.

[0030] Preferably, the film of the first aspect of the present invention has a thickness of 20 μm to 120 μm.

[0031] Preferably, in the film of the first aspect of the present invention, the first layer further comprises one or more divalent alginates selected from calcium alginate and magnesium alginate.

[0032] Preferably, in the film of the first aspect of the present invention, the second layer has an onset melting temperature in the range of 55°C to 85°C, determined as per the method described in Example 3 herein.

[0033] Preferably, in the film of the first aspect of the present invention, the second layer comprises starch and / or pullulan.

[0034] Preferably, the film of the first aspect of the present invention comprises 3 to 90 wt. %, preferably 15 to 85 wt. %, more preferably 25 to 80 wt. %, and most preferably 35 to 70 wt. % of one or more alginates, based on the total weight of the film, as determined according to the HPLC method in Journal of Chromatographic Science 2013;51:208-214.

[0035] Preferably, the film of the first aspect of the invention has a heat seal strength of at least 40 N / m, preferably at least 60 N / m, more preferably at least 80 N / m, even more preferably at least 100 N / m, and most preferably at least 120 N / m, when measured according to ASTM F88 / F88M-15 at 55% relative humidity and 20°C after the film has been conditioned at 55% relative humidity and 20°C for at least 1 hour and then sealed at a temperature of 120°C and a pressure of 3 bar applied for 1 second.

[0036] Viewed from a second aspect, the present invention provides a process for preparing a film as defined above, said process comprising: (i) a first layer, based on the total weight of the first layer: at least 20% by weight of one or more monovalent alginates, and providing a first layer comprising at least 5% by weight of one or more organic plasticizers; (ii) a second layer, based on the total weight of the second layer: one or more carbohydrates other than alginic acid and its salts; at least 5% by weight of one or more organic plasticizers, and providing a second layer comprising less than 20% by weight alginate; (iii) sealing one surface of the second layer to one surface of the first layer.

[0037] Viewed from a third aspect, the present invention provides a product encapsulated by a film as described above.

[0038] Preferably, in the product of the third aspect of the invention, the film is more than 75% biodegradable according to ASTM D6691, preferably more than 80%, more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95%.

[0039] Viewed from a fourth aspect, the present invention provides a method of encapsulating a product, the method comprising: (i) wrapping a product with the film of any one of claims 1 to 7, with the first layer being the outer layer; (ii) heat sealing the film around the product to form a pouch.

[0040] Preferably, in the process of the fourth aspect of the present invention, the duration of step (ii) is less than 2 seconds, more preferably less than 1 second, more preferably less than 0.5 seconds, and step (ii) is carried out at a temperature of less than 160°C, preferably less than 140°C, preferably less than 120°C.

[0041] Viewed from a fifth aspect, the present invention provides the use of the above for enclosing a product and / or for preparing a sachet.

[0042] Viewed from a sixth aspect, the present invention provides a pouch prepared by the above method.

[0043] Viewed from a seventh aspect, the present invention provides a method of releasing a product encapsulated in a film as described above, the method comprising: (i) placing the encapsulated product in water; (ii) dispersing the film, thereby releasing the product. DETAILED DESCRIPTION OF THE INVENTION

[0044] When sourcing raw materials for the packaging film of the present invention, it is preferable to use non-traditional sources of biopolymers whenever possible. Such non-traditional raw materials can be combined with conventional raw materials. "Conventional" refers to biopolymers typically used in human food, such as starch. Particularly preferred biopolymers for the film of the present invention are alginate-based polymers and salts. Alginates are typically obtained from seaweed, which does not directly compete with food crops and does not require valuable agricultural land.

[0045] Alginic acid is a polysaccharide typically obtained from the cell walls of brown algae. It is a biopolymer of β-D-mannuronic acid and α-L-guluronic acid, available in various molecular weights and monomer ratios depending on the source. This results in alginic acid solutions with various viscosities. Alginates are widely used in many applications, including film production. Films can be water-soluble or water-insoluble, depending on whether the alginate is cross-linked, typically with divalent metal ions, or not. Sodium alginate-based films are typically water-soluble, while films containing calcium alginate are mostly water-insoluble.

[0046] The suitability of the films of the present invention for commercial use depends not only on their favorable environmental profile. The film must be processable. The film must be robust through the multiple environments to which it is exposed, including manufacturing, storage, and end use. The film must meet several different requirements, such as permeability, elongation, and tensile strength. The film must also be heat-sealable.

[0047] The inventors have found that many films with high (greater than 20%) alginate content are often difficult to heat seal. This lack of heat sealability has significantly limited the wider use of alginate-based films due to the large existing manufacturing base that uses heat-sealing packaging lines and the many different types of packaging equipment that use heat sealing.

[0048] In heat sealing, two films are pressed together and exposed to heat for a specific period of time. The application of heat causes the diffusion and migration of polymer chains at the interface from film to film, resulting in the formation of a bond when the seal is cooled. Not all polymeric materials will heat seal because the mechanism depends on the behavior of the polymer chains at the interface. If these chains do not move or migrate easily, the film will not seal. The ease of heat sealing is a complex interaction of polymer type, crystallinity level, plasticization, temperature, and time.

[0049] Without wishing to be bound by theory, the poor heat-sealing behavior of typical alginate films is believed to be due to the more compact structure that alginate materials appear to form when exposed to heat. This effect has been reported in the art and is used in several alginate film production processes that use heat treatment to create denser, less permeable films. The production of alginate films often involves the application of heat to remove water. Heat-sealing, by definition, requires the application of heat. Therefore, alginate appears inherently less suitable for heat-sealing applications. While it may be possible to heat-seal alginate films if high levels of selected other materials are added to the film composition, this negates many of the benefits of using alginate in the first place.

[0050] One established route to sealing alginate films is to use an adhesive to bond the films together. This can be combined with the application of heat and pressure to ensure a good seal. Such an approach is feasible for certain types of equipment, such as the Hydroforma pouch-making machine manufactured by Cloud Packaging Inc. (now part of Mespack), because the drum design allows for the application of an adhesive layer on one or both films. Nevertheless, adhesives carry their own drawbacks, such as the risk of contamination of the enclosed material or of the adhesive by the enclosed product, especially when liquids or powders reduce the robustness of the seal. However, many packaging companies use vertical form-fill-seal (VFFS) technology to make pouches.

[0051] In the VFFS process, films are pulled through packaging equipment, interlocked, and sealed to form pouches. Typically, strips of film are wrapped around a fill head and sealed to form a cylinder or tube, which is then sealed at the bottom, filled with the contents through the fill head, and then sealed at the top. This technique can be used for both powders and liquids. The need to "pull" the film through the equipment means that it must have a minimum strength. The film must not be overstretched, as this would make it very difficult to control the precise positioning and alignment of the film. The film must not be sticky to the touch, as this would cause too much friction on the film as it is pulled through the equipment. This means that it is simply not practical to spray or apply a coating to one side of the film strip as it is pulled through the packaging line.

[0052] The film is also suitable for use in horizontal form, fill, and seal packaging equipment. In a typical HFFS machine, as in a Hydroforma pouch-making machine, a sheet of film is drawn into a mold to form a cavity by applying a vacuum, material is placed into the cavity, and a second sheet of film is used to seal the cavity. Sealing can be by heat sealing, or by solvent / adhesive sealing, or a combination thereof.

[0053] Typically, the films of the present invention are suitable for producing a variety of packaging forms including flexible pouches, blister packs, pods, sachets, flow wraps, wraps, sticks, and doy packs.

[0054] The inventors have discovered that multilayer films comprising an alginate-rich layer and a carbohydrate-rich layer can overcome the various challenges highlighted above based on the selection of layer materials and thicknesses. Such films of the present invention have good physical properties, such as strength, over a wide range of conditions. The films can be made from plant-based materials, do not require chemical modification, are low-cost, and are readily available. The films can have controlled solubility and be highly biodegradable. Careful selection of the layer material properties and thicknesses means that the films can be heat-sealed under industrially relevant conditions without damaging the pouch. Films of the present invention typically need to be sealed to each other by the carbohydrate-rich layer to obtain a good seal, whether by heat sealing or solvent sealing (when used in HFFS equipment). Attempting to seal alginate layers to each other or the carbohydrate layer to the alginate layer does not result in a robust seal.

[0055] Any film must be heat-sealable within a short time for any production to be industrially viable. The design of VFFS packaging lines means that production speed is directly related to the time it takes to perform heat sealing. If it takes 5 seconds to perform the heat sealing operation, an individual line can only make 12 pouches per minute. This speed is too slow to be economically viable. For most products, for any production process to be economically viable, the sealing time must be less than 1 second, preferably less than 0.5 seconds. Therefore, the actual definition of heat-sealability must include not only the ability to form a robust seal, but also the need for this to be achievable in less than 1 second, preferably less than 0.5 seconds.

[0056] Heat sealing relies on the temperature at the interface of the two films to be sealed being high enough to begin to melt the materials at the interface, thereby allowing them to migrate and interpenetrate. The temperature at the interface of the two films depends on the following variables:

[0057] (i) The temperature of the sealing plate to which the heat is applied. The higher the temperature, the faster the interface heats up.

[0058] (ii) The time the heating plate is in contact with the film. A longer time allows more time for heat to be conducted through the film layer to the interface.

[0059] (iii) The thickness of the film through which heat is conducted: the thicker the film, the longer it takes for the central interface to reach a sufficient temperature.

[0060] (iv) Thermal conductivity of the layers that make up the film. The rate at which heat is transferred across each layer of the film depends on the thermal conductivity of the film. The higher the thermal conductivity, the more quickly heat is transferred to the interface.

[0061] As mentioned above, the time that the heating plate is in contact with the film should be kept as short as possible. One way to minimize the time required for the interface temperature to rise sufficiently to cause sealing is to use a high sealing temperature. While this is effective, if the temperature is too high (e.g., above 160°C), it can thermally damage the alginate layer of the film that is in contact with the sealing plate, resulting in visual and other defects around the seal.

[0062] Therefore, the thermal stability of the alginate-rich layer and the limited time available for heat sealing are crucial. According to the present invention, the carbohydrate layer composition is preferably selected to have a thermal initiation temperature of less than 85°C, combined with a total thickness of 20 μm to 120 μm for the two layers that together form the film. The thermal initiation temperature is the temperature at which the composition begins to soften and partially melt. For heat sealing to occur, the materials at the interface must be at or above the thermal initiation temperature. Controlling the film thickness allows for sufficient heat transfer to the interface within the available time, while still providing a film of sufficient thickness and robustness for practical use.

[0063] Thus, a film comprising two layers, one rich in alginate and the other rich in carbohydrate, where the thicknesses of the two layers are controlled within certain limits and the carbohydrate-rich layer has an onset temperature of less than 85°C, provides a preferred plant biopolymer-based film that is robust and processable with commercially available heat sealing equipment.

[0064] Accordingly, the present invention provides a film comprising: a first layer, based on a total weight of the first layer: at least 20% by weight of one or more monovalent alginates, and a first layer comprising at least 5 wt. % of one or more organic plasticizers; a second layer, based on the total weight of the second layer: one or more carbohydrates other than alginic acid and its salts; at least 5% by weight of one or more organic plasticizers, and a second layer comprising less than 20% by weight of alginate; A film is provided in which one surface of the second layer is sealed to one surface of the first layer.

[0065] In the films of the present invention, the first layer comprises at least one monovalent alginate. In preferred films of the present invention, the first layer comprises at least one alkali metal salt of alginic acid. More preferably, the first layer comprises lithium alginate, sodium alginate, potassium alginate, ammonium alginate, or a mixture thereof, with sodium alginate being most preferred.

[0066] In an alternative preferred film of the present invention, the first layer further comprises one or more divalent alginates selected from calcium alginate and magnesium alginate, with calcium alginate being most preferred.

[0067] In a preferred film of the present invention, the first layer has a thickness of 15 μm to 115 μm. In an alternative preferred film of the present invention, the second layer has a thickness of 5 μm to 80 μm. A preferred film of the present invention has a thickness of 20 μm to 120 μm.

[0068] In preferred films of the present invention, the second layer has an onset melt temperature of less than 85°C, preferably less than 80°C, determined as described in Example 3 herein.

[0069] In an alternative preferred film of the present invention, the second layer has an onset melt temperature of at least 55°C, determined as described in Example 3 herein.

[0070] Most preferably, the second layer has an onset melting temperature in the range of 55 to 85°C, determined as described in Example 3 herein.

[0071] In preferred films of the present invention, the one or more carbohydrates other than alginic acid and its salts in the second layer are selected from monosaccharides, disaccharides, oligosaccharides, polysaccharides, and mixtures thereof. More preferably, the second layer comprises at least one carbohydrate that is a polysaccharide. Most preferably, the polysaccharide is a starch.

[0072] Starch is a carbohydrate polymer. Starch is essentially composed of amylose and / or amylopectin, and in its natural form, it is typically in the form of semi-crystalline granules. Starch sources include, but are not limited to, fruits, seeds, and plant roots or tubers.

[0073] Some starches are classified as waxy starches, which consist essentially of amylopectin and lack significant amounts of amylose. Exemplary waxy starches include waxy maize starch, waxy rice starch, waxy potato starch, and waxy wheat starch.

[0074] Alternatively, some starches are classified as high amylose starches.

[0075] Modified starches are prepared by treating native starch physically, enzymatically, or chemically to alter its properties. Starch can be modified, for example, by enzymes, heat treatment, oxidation, or reaction with various chemicals.

[0076] In the films of the present invention, the starch may be a native starch or a modified starch, or a mixture thereof.

[0077] In preferred films of the present invention, the starch is selected from wheat starch, potato starch, pea starch, waxy potato starch, maize starch, waxy maize starch, high amylose maize starch, tapioca starch, cassava starch, rye starch, sorghum starch, chickpea starch, soybean starch, or mixtures thereof, preferably potato starch.

[0078] In an alternative preferred film of the present invention, the starch is a modified starch selected from acid treated starch, dextrin, alkali modified starch, bleached starch, oxidized starch, enzyme treated starch, maltodextrin, cyclodextrin monostarch phosphate, distarch phosphate, acetylated starch, hydroxypropylated starch, hydroxyethyl starch, sodium starch octenyl succinate, aluminum starch octenyl succinate or cationic starch, or mixtures thereof, preferably acid treated starch.

[0079] Alternatively, the polysaccharide is pullulan.

[0080] In preferred films of the present invention, the second layer comprises starch and / or pullulan.

[0081] In preferred films of the present invention, the second layer comprises 40 to 95 wt %, preferably 50 to 80 wt %, more preferably 55 to 75 wt % carbohydrate based on the total weight of the second layer.

[0082] Alternately preferred films of the present invention comprise 1 to 80 wt %, preferably 7 to 70 wt %, more preferably 15 to 50 wt % of one or more carbohydrates based on the total weight of the film.

[0083] Preferred films of the present invention comprise 3 to 90 wt. %, preferably 15 to 85 wt. %, more preferably 25 to 80 wt. %, and most preferably 35 to 70 wt. % of one or more monovalent alginates, based on the total weight of the film, as determined according to the HPLC method in Journal of Chromatographic Science 2013;51:208-214.

[0084] Preferred films of the present invention comprise 10 to 50 wt %, preferably 15 to 45 wt %, more preferably 20 to 40 wt % of one or more organic plasticizers, based on the total weight of the film.

[0085] Preferably, the one or more organic plasticizers in the first layer are independently selected from the group consisting of: a) polyols formed by 1 to 20 repeating hydroxylated units with at least 4 carbon atoms, each unit containing 2 to 6 carbon atoms, except for sorbitol, if the polyol is formed by only one repeating unit; b) ethers, thioethers, inorganic and organic esters, acetals, and amino derivatives of polyols formed by 1 to 20 repeating hydroxylated units each containing 2 to 6 carbon atoms, excluding acetate esters of glycerin, triethyl citrate, and tributyl citrate; c) polyol reaction products having 1 to 20 repeating hydroxylated units each containing 2 to 6 carbon atoms with a chain extender; d) Polyol oxidation products having 1 to 20 repeating hydroxylated units each containing 2 to 6 carbon atoms and containing at least one aldehyde or carboxylic acid functional group, or mixtures thereof.

[0086] More preferably, the one or more organic plasticizers in the first layer are independently selected from glycerol, polyethylene glycol, propylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, fatty acids (e.g., oleic acid), glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, and organic acids (e.g., lactic acid, citric acid, glycolic acid, malic acid, or tartaric acid), or mixtures thereof, with a mixture of glycerol, sorbitol, and oleic acid being most preferred. Preferably, the plasticizer is vegetable-based.

[0087] In preferred films of the present invention, the one or more organic plasticizers are present in the first layer in an amount of 10 to 50 wt. %, more preferably 20 to 40 wt. %, based on the total weight of the first layer, at 55% relative humidity and 20°C.

[0088] In an alternative preferred film of the present invention, the weight ratio of alginate to organic plasticizer in the first layer ranges from 4:1 to 1:1.

[0089] Preferably, the one or more organic plasticizers in the second layer are independently selected from the group consisting of: a) polyols formed by 1 to 20 repeating hydroxylated units with at least 4 carbon atoms, each unit containing 2 to 6 carbon atoms, except for sorbitol, if the polyol is formed by only one repeating unit; b) ethers, thioethers, inorganic and organic esters, acetals, and amino derivatives of polyols formed by 1 to 20 repeating hydroxylated units each containing 2 to 6 carbon atoms, excluding acetate esters of glycerin, triethyl citrate, and tributyl citrate; c) polyol reaction products having 1 to 20 repeating hydroxylated units each containing 2 to 6 carbon atoms with a chain extender; d) Polyol oxidation products having 1 to 20 repeating hydroxylated units each containing 2 to 6 carbon atoms and containing at least one aldehyde or carboxylic acid functional group, or mixtures thereof.

[0090] More preferably, the one or more organic plasticizers in the second layer are independently selected from glycerol, diglycerol, triethylene glycol, polyethylene glycols such as PEG400 and other polyethylene glycols, propylene glycol, dipropylene glycol, polypropylene glycol, sorbitol, mannitol, xylitol, glycerin, pentaerythritol, compounds produced by adding ethylene oxide to sorbitol and other polyalcohols, triethyl citrate, fatty acids (e.g., oleic acid), glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, and organic acids (e.g., lactic acid, citric acid, glycolic acid, malic acid, or tartaric acid), sugar surfactants, or mixtures thereof, with a mixture of glycerol and sorbitol being most preferred. Preferably, the plasticizer is vegetable-based.

[0091] The term sugar surfactant means that the surfactant contains at least one sugar moiety. A sugar surfactant is preferably composed of at least one, preferably three or more monosaccharide units linked glycosidically and may contain what is called a "sugar" moiety (two monosaccharide units) or three monosaccharides.

[0092] The monosaccharides of the sugar moiety may be of the same type (homopolysaccharides) or different (heteropolysaccharides).

[0093] Preferably, the sugar surfactant is ionic, more preferably anionic, cationic, or amphoteric. More preferably, it is anionic. The sugar surfactant is preferably selected from functionalized alkyl polyglycosides, fatty acid glucamides, glycinates, glycolipid biosurfactants, such as rhamnosurfactants (e.g., rhamnolipids) or sophorolipids, or any combination thereof.

[0094] In preferred films of the present invention, the one or more organic plasticizers are present in the second layer in an amount of 10 to 50 wt. %, more preferably 20 to 40 wt. %, based on the total weight of the second layer, at 55% relative humidity and 20°C.

[0095] In preferred films of the present invention, the weight ratio of the one or more carbohydrates to the one or more organic plasticizers in the second layer ranges from 4:1 to 1:1.

[0096] As will be understood by one of ordinary skill in the art, the one or more organic plasticizers may be the same in the first layer and the second layer, or the one or more organic plasticizers in the first layer and the second layer may be different.

[0097] If the film is for packaging food, the plasticizer must be suitable for human consumption.

[0098] Preferred films of the present invention contain 7.5 to 35 wt. % water, more preferably 10 to 30 wt. %, and most preferably 15 to 25 wt. % water, based on the total weight of the film, at 55% relative humidity and 20°C.

[0099] In preferred films of the present invention, the first layer further comprises at least one carbohydrate, more preferably a polysaccharide, and most preferably a starch.

[0100] In an alternative preferred film of the present invention, the second layer further comprises a divalent metal salt. Preferably, the divalent metal salt is an alkaline earth metal salt or a transition metal salt, more preferably, the alkaline earth metal salt is a magnesium salt or a calcium salt, with a calcium salt being most preferred.

[0101] The preferred transition metal salts are zinc salts.

[0102] Preferably, the calcium salt is selected from calcium chloride, calcium acetate, calcium citrate, calcium gluconate, with calcium chloride being most preferred.

[0103] In preferred films of the invention, the divalent metal salt is present in the second layer in an amount of 0.1 to 5 wt %, more preferably 0.2 to 4 wt %, and most preferably 0.5 to 3 wt %, based on the total weight of the second layer, at 55% relative humidity and 20°C.

[0104] Preferred films of the present invention further comprise one or more additives such as gums, oils, flavors, dyes, pigments, opacifiers, bittering agents, antimicrobial agents such as thymol, antiblocking agents, or structure enhancing agents such as cellulose nanofibers, cellulose nanocrystals, and cellulose fibers.

[0105] A preferred film of the present invention further comprises a phyllosilicate. Preferably, the phyllosilicate is a serpentine mineral, a clay mineral, a chlorite mineral, or a mica mineral, or a mixture thereof. Preferably, the clay mineral is selected from bentonite, kaolinite, pyrophyllite, vermiculite, and smectite (e.g., montmorillonite, cloisite, laponite, hectorite, etc.), or a mixture thereof.

[0106] As will be appreciated by those skilled in the art, the phyllosilicate can be present in the first layer and / or the second layer.

[0107] Preferred films of the present invention have a heat seal strength of at least 40 N / m, more preferably at least 60 N / m, even more preferably at least 80 N / m, even more preferably at least 100 N / m, and most preferably at least 120 N / m, measured according to ASTM F88 / F88M-15 at 55% relative humidity and 20°C after the film has been conditioned at 55% relative humidity and 20°C for at least 1 hour and then sealed at a temperature of 120°C and a pressure of 3 bar applied for 1 second.

[0108] A preferred alternative film of the present invention has a heat seal strength of at least 40 N / m, more preferably at least 60 N / m, measured according to ASTM F88 / F88M-15 at 55% relative humidity and 20°C, after the film has been conditioned at 55% relative humidity and 20°C for at least 1 hour and then sealed at a temperature of 120°C and a pressure of 3 bar applied for 1 second.

[0109] The present invention also provides a process for preparing the above film, the process comprising: (i) a first layer, based on the total weight of the first layer: At least 20% by weight of one or more alginates, and providing a first layer comprising at least 5% by weight of one or more organic plasticizers; (ii) a second layer, based on the total weight of the second layer: one or more carbohydrates other than alginic acid and its salts; at least 5% by weight of one or more organic plasticizers, and providing a second layer comprising less than 20% by weight alginate; (iii) sealing one surface of the second layer to one surface of the first layer.

[0110] In a preferred process of the present invention, step (i) involves the use of a pre-formed first layer.

[0111] In an alternative preferred process of the present invention, step (ii) involves the use of a pre-formed second layer.

[0112] In a preferred process of the present invention, step (i) comprises forming the first layer, preferably by casting, laminating or extrusion.

[0113] In a preferred process of the present invention, step (i) comprises forming the second layer, preferably by casting, laminating or extrusion.

[0114] A preferred process of the present invention comprises: (a) mixing at least one salt of alginic acid and at least one organic plasticizer in water, optionally using sonication, to form mixture (a); (b) forming the mixture (a) into said first layer on a surface; (c) mixing at least one carbohydrate and at least one organic plasticizer in water, optionally using sonication, to form mixture (b); (d) forming the mixture (b) into the second layer on the first layer.

[0115] Preferably, step (a) comprises further mixing at least one carbohydrate to form said mixture (a).

[0116] Preferably, in step (b), mixture (a) is at a temperature in the range of 40 to 85° C., more preferably 50 to 60° C. (e.g., 55° C.). Most preferably, in step (b), mixture (a) is at ambient temperature.

[0117] Preferably, step (c) comprises further mixing a divalent metal salt to form mixture (b) above.

[0118] Preferably, step (c) is carried out at a temperature in the range of 10 to 90°C. Preferably, in step (d), mixture (b) is at a temperature in the range of 40 to 85° C., more preferably 50 to 60° C. (e.g., 55° C.). Most preferably, in step (d), mixture (b) is at ambient temperature.

[0119] Prior to step (d), mixture (b) is preferably degassed.

[0120] A preferred process of the present invention comprises: (a) mixing at least one carbohydrate and at least one organic plasticizer in water, optionally using sonication, to form a mixture (c); (b) forming the mixture (c) into said second layer on the surface; (c) mixing at least one salt of alginic acid and at least one organic plasticizer in water, optionally using sonication, to form mixture (d); (d) forming the mixture (d) into the first layer on the second layer.

[0121] Preferably, step (a) includes further mixing a divalent metal salt to form mixture (c) as described above.

[0122] Preferably, step (c) comprises further mixing at least one carbohydrate to form mixture (d) as described above.

[0123] Preferably, step (a) is carried out at a temperature in the range of 10 to 90°C. Preferably, in step (c), mixture (a) is at a temperature in the range of 40 to 70°C, more preferably 50 to 60°C (for example 55°C).

[0124] Preferably, prior to step (b), mixture (c) is degassed.

[0125] Preferably, step (c) is carried out at a temperature in the range of 18 to 25°C, more preferably 20 to 23°C.

[0126] Preferably, in step (d), the mixture (d) has a temperature in the range of 10 to 90°C.

[0127] In a preferred process of the present invention, one or more films are independently made by casting or blown film extrusion, preferably by casting, more preferably by solvent casting.

[0128] Solvent casting can be a two-step process in which a first layer of material is cast onto a substrate such as Mylar®, or corona-treated Mylar®, or a metal belt. The mixture cast can be at room temperature or heated. Immediately after coating, the material is dried in an oven and the film is wound onto a core. The roll of the first layer (which may still be on Mylar®) is unwound and rewound through the line so that a second layer can be cast on top of the first layer and dried again in an oven. Again, the mixture cast can be at room temperature or heated. This process is sometimes referred to as a "wet-on-dry process." To control the casting thickness, the casting line is equipped with a system of metal rollers, with the gap between the rollers controlling the wet thickness of the coating. The line speed and oven temperature are adjusted to achieve the desired dry film thickness and final moisture content. The final dry film is peeled from the support substrate and then wound onto a core, wrapped or encapsulated in a product, and optionally sealed to form a pouch.

[0129] Solvent casting can also be a one-step continuous process in which a first layer of material is cast onto a substrate such as Mylar®, corona-treated Mylar®, or a metal belt. The mixture cast can be at room temperature or heated. After coating and drying or partially drying in an oven, a second layer can be cast on top of the first layer and finally dried in a second oven. Again, the mixture cast can be at room temperature or heated. This process is sometimes referred to as a "wet-on-wet process" or a "wet-on-semi-dry process." To control the casting thickness, the line is equipped with a system of metal rollers, with the gap between the rollers controlling the wet thickness of the coating. The line speed and oven temperature are adjusted to achieve the desired final dry film thickness and moisture content. The final dry film is peeled from the support substrate and then wound onto a core to encase or encapsulate the product, optionally sealing the film and storing it until needed to form a pouch.

[0130] In both solvent casting processes, it is important that the final roll of film can be unwound easily and without damage to the film. This is necessary when using the final film in the intermediate portion of a wet-on-dry process or on a product packaging line. The ease with which the film can be unwound is evaluated using the peel method described herein.

[0131] The present invention also provides a product coated with or enclosed by the above film.

[0132] In preferred products of the present invention, the film is made exclusively from food-grade materials.

[0133] In alternative preferred products of the present invention, the film is more than 75% biodegradable according to ASTM D6691 after 28 days, more preferably more than 80%, even more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95%.

[0134] Preferred products of the present invention are food products, pharmaceutical products, cleaning products, agricultural products (eg animal feed) or drugs, chemical products, or cosmetics.

[0135] Preferably, the product of the present invention is a solid, powdered or liquid product having a water activity of less than 60%.

[0136] Alternative preferred products of the present invention are solid products selected from soup or flavor preparations (e.g., stock cubes), personal cleansers (e.g., soap bars, body scrubs, or solid shampoos), laundry detergent tablets or bars, or dishwasher detergent tablets.

[0137] Preferably, the product of the present invention is a stock cube or a laundry detergent tablet or a dishwasher detergent tablet.

[0138] An alternative preferred product of the present invention is a powder product selected from powdered food, powdered drink, powdered milk, powdered soup, powdered hot chocolate, powdered coffee, flake soap, powdered laundry detergent, and powdered shampoo.

[0139] Preferably, the product of the present invention is a powdered beverage.

[0140] Also preferably, the product of the present invention is a liquid product selected from an oil having a water activity of less than 60% or a hair care product or a body care product.

[0141] The present invention also provides a method of encapsulating a product, the method comprising: (i) encasing the product in the film with the first layer being the outer layer; (ii) heat sealing the film around the product.

[0142] As will be understood by those skilled in the art, the heat-sealing process requires contact between sections of a film that contains one or more carbohydrates other than alginic acid and its salts.For example, a composite film containing starch and alginate can be sealed to another composite film containing starch and alginate, or to itself.However, if the film is a multi-layer film, for example, containing a starch layer and an alginate layer, the starch layer must be sealed to another film containing starch, or to itself.This is because starch can melt (or gel) at a much lower temperature than alginate.Residual water present in the starch layer also helps to lower the melting (or gelatinization) temperature of starch.

[0143] In a preferred method of the invention, the duration of step (ii) is less than 2 seconds, more preferably less than 1 second, most preferably less than 0.5 seconds.

[0144] In an alternative preferred process of the present invention, step (ii) is carried out at a temperature below 160°C, more preferably below 140°C, most preferably below 120°C.

[0145] The present invention also provides the use of the above film to encapsulate a product.

[0146] The present invention also provides a pouch prepared by the above method.

[0147] Preferred sachets of the present invention are water-dispersible.

[0148] The film of the present invention has high water dispersibility, which means that the film can be used as a packaging material for products that does not generate any waste during the final use of the product. For example, the film of the present invention can be used to package detergents, so that the film disperses in water to release the detergent during the washing process. Alternatively, the film of the present invention can be used to package food, so that the film disperses in water to release the food during the cooking process.

[0149] According to the present invention, the water-dispersibility of the films is evaluated using a 0.75 g sample of each of the final films conditioned at 55% relative humidity and 20°C. The samples are mixed in a 600 ml beaker in 300 ml of both 20°C reverse osmosis water and freshly boiled reverse osmosis water (i.e., having a temperature range of 75.1°C to 90.2°C) using an overhead stirrer at 300 rpm for 3 minutes at room temperature. The final mix is ​​visually inspected for residual particles, and the size of the residual particles is used to determine water-dispersibility on the following scale: Very low—most particles greater than 30 mm; Low—most particles about 20-30 mm; Average—most particles about 10-20 mm; High—most particles about 1-10 mm; Very high—most particles less than 1 mm; Maximum—no visible particles. Dispersibility is reported as the average of two different temperature observations, each of which is assigned an integer value for these purposes. Advantageously, the residue is completely biodegradable, which means that the film has no adverse effect on the environment.

[0150] The present invention also provides the use of the above film for preparing a pouch.

[0151] The present invention also provides a method for releasing a product encapsulated in the above film, the method comprising: (i) placing the encapsulated product in water; (ii) dispersing the film, thereby releasing the product.

[0152] In a preferred method of the present invention, the product is released in step (ii) during the cooking process.

[0153] In an alternative preferred method of the present invention, the product is released in step (ii) during the washing process. [Brief explanation of the drawings]

[0154] [Figure 1a] 1 is a photograph of a pouch prepared in Example 13.

[0155] [Figure 1b] 1 is a photograph of a sachet prepared in Example 13 immediately after being placed in a beaker of water.

[0156] [Figure 1c] 1 is a series of photographs of a pouch prepared in Example 13 at 2 seconds, 52 seconds, 60 seconds, 72 seconds, and 138 seconds, respectively, after being placed in a beaker of water. [Figure 1d] 1 is a series of photographs of a pouch prepared in Example 13 at 2 seconds, 52 seconds, 60 seconds, 72 seconds, and 138 seconds, respectively, after being placed in a beaker of water. [Figure 1e] 1 is a series of photographs of a pouch prepared in Example 13 at 2 seconds, 52 seconds, 60 seconds, 72 seconds, and 138 seconds, respectively, after being placed in a beaker of water. [Figure 1f] 1 is a series of photographs of a pouch prepared in Example 13 at 2 seconds, 52 seconds, 60 seconds, 72 seconds, and 138 seconds, respectively, after being placed in a beaker of water. [Figure 1g] 1 is a series of photographs of a pouch prepared in Example 13 at 2 seconds, 52 seconds, 60 seconds, 72 seconds, and 138 seconds, respectively, after being placed in a beaker of water. [Example]

[0157] material Sodium alginate and calcium chloride dihydrate were purchased from Thermo Fisher Scientific. The viscosity of a 1% solution of sodium alginate at 20°C was 350-550 mPas.

[0158] Vivapure® FD150 sodium alginate was purchased from JRS (Germany). The viscosity of a 1% solution of sodium alginate at 20°C was 20-50 mPas.

[0159] Tapioca starch (Alpha Instant), potato starch (pregelled), corn starch, and rice starch were purchased from BakeRite.

[0160] Food grade glycerol (APC Pure), propylene glycol, and potato starch (heat soluble) were purchased from APC.

[0161] Antifoam (aqueous silicone emulsion), polysorbate 80, and corn amylopectin (starch from corn) from Sigma-Aldrich Co.

[0162] Waxy maize starch (Ultratex) was purchased from Special Ingredients Ltd.

[0163] Pullulan was purchased from Rongsheng Biotechnology Co.Ltd.

[0164] Maltodextrin was purchased from Sigma-Aldrich Co.

[0165] Oleic acid, sorbitol, and thymol were purchased from Thermo Fisher Scientific.

[0166] In the following examples, all references to "ambient temperature" or "room temperature" are references to a temperature of approximately 20°C.

[0167] Example 1: Preparation of alginate monolayers 400 ml of water was mixed with 14 g of alginic acid in a 600 ml beaker at ambient temperature using an overhead stirrer to form a homogeneous solution. 6 g of glycerol was then added with stirring, and 4 drops of antifoaming agent were added. The mix was stirred for 45 minutes. 25 ml of the mix was poured into a 50 ml Falcon tube. The mix was removed and poured onto a flat glass plate with a Mylar® surface. A knife blade was used to spread the liquid evenly on the plate, resulting in a 700 micron wet film of the alginate mix. The glass plate was then dried overnight at ambient temperature to form a dry film.

[0168] Example 2: Preparation of carbohydrate monolayers 30.0 g of tapioca starch (STT) was dispersed in 300 ml of deionized water at ambient temperature in a 600 ml flask using overhead stirring. 12.86 g of glycerol was then added and the suspension was stirred. The suspension was then sonicated for 30 minutes at 95% amplitude using a Bandelin sonicator, with a 1 second on, 0.2 second off cycle. The solution was then placed in an 80°C sonicator bath for 1 minute to remove air bubbles.

[0169] 20 ml of the solution was poured into a 50 ml Falcon tube. The solution was then further degassed by removing large air bubbles with a pipette, cooled to 55°C, and poured onto a flat glass plate with a Mylar® surface. A knife blade was used to spread the liquid evenly, resulting in a wet film of the starch mix approximately 400 microns thick. The plate was then placed in an 80°C oven for 50 minutes to form a dry film.

[0170] Example 3: Determination of Melting Initiation Temperature and Sealing Strength of Carbohydrate Monolayers (i) Preparation of carbohydrate monolayers 10.0 g of carbohydrate was dispersed in 100 ml of deionized water at ambient temperature in a 250 ml flask using overhead stirring. 4.29 g of glycerol was then added and the suspension was stirred. The suspension was then sonicated for 10 minutes at 95% amplitude using a Bandelin sonicator, with a cycle of 1 second on and 0.2 seconds off. The solution was then placed in an 80°C sonicator bath for 1 minute to remove air bubbles.

[0171] 20 ml of the solution was poured into a 50 ml Falcon tube. The solution was then further degassed by removing large air bubbles with a pipette, cooled to 55°C, and poured onto a flat glass plate with a Mylar® surface. A knife blade was used to spread the liquid evenly, resulting in a wet film approximately 400 microns thick. The plate was then placed in an oven at 80°C for 50 minutes to dry the film layer.

[0172] (ii) Measurement of melting temperature by differential scanning calorimetry (DSC) The films produced in step (i) were conditioned overnight at 55% relative humidity and 20°C. The onset of melting temperature is a function of the overall film composition, including the moisture level. A small test sample (10–20 mg) was cut from each film and accurately weighed. Each sample was placed in a 40 μL aluminum pan (#51119870, purchased from Mettler Toledo) and heated under nitrogen atmosphere from 25°C to 160°C at a heating rate of 10°C / min using a Mettler Toledo DSC822e. A hole was pierced in the pan lid using a 50 μm diameter needle before sealing. An empty pan was used as a reference. Normalized heat flow was recorded and plotted as a function of temperature.

[0173] The onset melting point of a sample is defined as the first inflection point in the DSC curve that indicates an increasing rate of heat flow to the sample with increasing temperature. As the sample begins to melt, the heat flow to the sample increases, thus causing a change in slope and an inflection point on the graph.

[0174] The normalized heat flow plot can be visually evaluated by an operator to determine inflection points in the graph. However, this analysis is currently typically performed using software analysis tools. Such analysis tools are typically included as part of the instrument operating system. Suitable software includes the STARe evaluation software supplied by Mettler-Toledo.

[0175] The data from the normalized DSC plots obtained above were analyzed using STARe evaluation software version 16.30 to determine the onset melting temperature. The results are shown in Table 1 below. The thermal properties of a starch mixture are a complex combination of the relative ratio of amylose to amylopectin in the starch, previous heat treatment, and the levels and nature of other components.

[0176] [Table 1] (iii) Determination of seal strength Test samples of some of the layers produced in step (i) were prepared and subjected to seal strength measurements. 25 mm wide test samples were cut to the dimensions specified in ASTM F88 / F88M-15 and conditioned overnight at 55% RH and 20°C. The test strip samples were then sealed using an RDM heat sealer to obtain a fin seal. The sealed specimens were tested using technique A (unsupported) in a Tinnius Olsen tensile tester. A sealing temperature of 100°C and a dwell time of 1 second were used. The results are shown in Table 2 below.

[0177] [Table 2] As demonstrated above, the melting initiation temperature of a material is inversely proportional to the material's ability to form a strong seal. For example, an STT-based layer has a low initiation temperature and forms a strong seal. A BPS-based layer has a slightly higher initiation temperature and forms a similarly strong seal. However, a CSS-based layer has a much higher initiation temperature and, as a result, forms a seal with much lower seal strength.

[0178] The lower initiation temperature of the carbohydrate-containing layer of the multilayer film of the present invention is advantageous for several reasons. Not only has it been demonstrated that greater seal strength can be achieved, but the lower initiation temperature means that a lower temperature needs to be applied to the outer alginate-containing layer of the multilayer film of the present invention to result in an effective seal of the inner carbohydrate-containing layer. This means that film degradation (e.g., as a result of burning) is avoided, and a shorter residence time is required to form the seal, making the sealing process more commercially viable.

[0179] Example 4: Preparation of alginate-starch multilayer films (i) Preparation of alginate mixture 400 ml of water was mixed with 14 g of alginic acid in a 600 ml beaker at ambient temperature using an overhead stirrer to form a homogeneous solution. 6 g of glycerol was then added with stirring, followed by 4 drops of antifoaming agent. The mix was stirred for 45 minutes. The mix was then further degassed under vacuum using a laboratory speed mixer.

[0180] (ii) Film formation—alginate layer 25 ml of the mix produced in step (i) was poured into a 50 ml Falcon tube. The mix was removed and poured onto a flat glass plate with a Mylar® surface. Using a knife blade, the liquid was spread evenly on the plate to obtain a 1100 micron wet film of the alginate mix. The glass plate was then dried overnight at ambient temperature to form a dry film layer.

[0181] (iii) Preparation of starch mixture 40.0 g of tapioca starch (STT) was dispersed in 400 ml of deionized water at ambient temperature in a 600 ml flask using overhead stirring. 17.14 g of glycerol was then added and the suspension was stirred. The suspension was then sonicated for 40 minutes at 95% amplitude using a Bandelin sonicator with a 1 second on, 0.2 second off cycle. The solution was then placed in a sonicator bath at 80°C for 1 minute to remove air bubbles.

[0182] (iv) Film formation - starch layer 7 ml of the mix produced in step (iii) was poured into a 50 ml Falcon tube. The mix was then further degassed by removing large air bubbles with a pipette, cooled to 55°C, and then spread using a knife blade onto the exposed surface of the dry film prepared in step (ii) (i.e., the surface not in contact with the glass plate) to obtain a wet film of the starch mix approximately 250 microns thick. The plate was then placed in an oven at 80°C for 30 minutes to form a multilayer film.

[0183] Comparative Example 1: Preparation of Alginate / Starch Monolayers 50 ml of the mix produced in step (iii) of Example 4 was added to 220 ml of the mix produced in step (i) of Example 4 in a 400 ml beaker using an overhead stirrer at ambient temperature to form a homogeneous mixture. The mix was placed in an 80°C sonicator bath for 5 minutes to remove air bubbles. 30 ml of the mix was poured into a 50 ml Falcon tube. The mix was removed and poured onto a flat glass plate with a Mylar® surface and evenly spread using a knife blade to obtain a 1350 micron wet film of the alginate-starch blend. The glass plate was then allowed to dry overnight at ambient temperature to form a dry film.

[0184] Example 5: Measurement of film tensile strength and elongation Rectangular test specimens 80 mm long and 10 mm wide were cut (which fell within the specifications set forth in ASTM D882) and conditioned overnight at 55% RH and 20°C. Test specimens were tested using a Tinnius Olsen tensile tester with flat grip inserts, an initial grip separation of 50 mm, and a test speed of 50 mm / min (strain rate of 1 mm / mm·min).

[0185] Great care was taken when cutting the specimens to prevent nicks and tears that would cause premature failure and to ensure repeatable specimen quality.

[0186] The results are shown below in Table 3. Tensile strength is reported in MPa and elongation at break in %.

[0187] [Table 3] The alginate film of Example 1 has very good tensile strength, while the starch film of Example 2 does not and is too brittle to be useful. When the two materials are combined, the resulting film, whether as a blend or as a multilayer, has acceptable tensile strength. However, the blend (Comparative Example 1) has little elongation, while the multilayer (Example 4) has an elongation closer to that of the alginate film of Example 1. The results demonstrate that the multilayer films of the present invention have good strength and are less likely to crack under elongational strain.

[0188] Example 6: Measurement of seal strength Test specimens 25 mm wide were cut to the dimensions specified in ASTM F88 / F88M-15 and conditioned overnight at 55% RH and 20°C. The test strip specimens were then sealed using an RDM heat sealer to obtain a fin seal. The sealed specimens were tested in a Tinnius Olsen tensile tester using Technique A (unsupported). A sealing temperature of 140°C, a dwell time of 1 second, and a pressure of 3 bar were used. The results are shown in Table 4 below. The maximum force each specimen was subjected to when stressed to failure is reported in Newtons per meter (N / m).

[0189] [Table 4] The results show that the alginate film of Example 1 does not seal at all, while the starch film of Example 2 has good seal strength. When the two materials are combined into a blend (Comparative Example 1), the resulting film has low seal strength, but when they are combined into a multilayer (Example 4), very high seal strength is achieved. The results demonstrate that the multilayer films of the present invention have excellent seal strength.

[0190] The alginate / starch multilayer of Example 4 (having a film thickness of 58 μm and conditioned and stored at a relative humidity of 55% and a temperature of 20° C.) was subjected to further seal strength tests at different sealing temperatures and dwell times using a pressure of 3 bar. The results are shown in Table 5 below.

[0191] [Table 5] The results show that for the multilayer films of the present invention, the longer the dwell time, the lower the temperature required to achieve effective seal strength.

[0192] Example 7: Ca 2+ Preparation of alginate monolayers using ions 400 ml of water was mixed with 14 g of alginic acid in a 600 ml beaker at ambient temperature using an overhead stirrer to form a homogeneous solution. 6 g of glycerol was then added with stirring, and 4 drops of antifoaming agent were added. The mix was stirred for 45 minutes. 0.26 g of CaCl2 was added to the solution and stirred. 50 ml of the mix was poured into a 50 ml Falcon tube. The mix was removed and poured onto a flat glass plate with a Mylar® surface. A knife blade was used to spread the liquid evenly on the plate, resulting in an 1100 micron wet film of the alginate mix. The glass plate was then dried overnight at ambient temperature to form a dry film.

[0193] Example 8: Ca 2+ Preparation of starch monolayers using ions 20.0 g of tapioca starch (STT) was dispersed in 200 ml of deionized water at ambient temperature in a 600 ml flask using overhead stirring. 8.57 g of glycerol was then added and the suspension was stirred. The suspension was then sonicated for 20 minutes at 95% amplitude using a Bandelin sonicator with a 1 second on, 0.2 second off cycle. 0.41 g of CaCl2 was added to the solution and stirred. The solution was then placed in an 80°C sonicator bath for 1 minute to remove air bubbles.

[0194] 20 ml of the mix was poured into a 50 ml Falcon tube. The mix was then further degassed by removing large air bubbles with a pipette, cooled to 55°C, and poured onto a flat glass plate with a Mylar® surface. A knife blade was used to spread the liquid evenly, resulting in a wet film of the starch mix approximately 400 microns thick. The plate was then placed in an 80°C oven for 50 minutes to form a dry film.

[0195] Comparative example 2: Ca 2+ Preparation of alginate-starch monolayers using ions This film was prepared according to the method of Comparative Example 1, except that once a homogeneous mixture was formed, 0.30 g of CaCl was added during overhead stirring before removing air bubbles in a sonicator bath.

[0196] Example 9: Ca 2+ Preparation of alginate-starch multilayer films using ions (i) Preparation of alginate mixture 400 ml of water was mixed with 14 g of alginic acid in a 600 ml beaker at ambient temperature using an overhead stirrer to form a homogeneous solution. 6 g of glycerol was then added with stirring, followed by 4 drops of antifoaming agent. The mixture was stirred for 45 minutes.

[0197] (ii) Film formation—alginate layer 50 ml of the mix produced in step (i) was poured into a 50 ml Falcon tube. The mix was removed and poured onto a flat glass plate with a Mylar® surface. Using a knife blade, the liquid was spread evenly on the plate to obtain a 1100 micron wet film of the alginate mix. The glass plate was then allowed to dry overnight at ambient temperature to form a dry layer.

[0198] (iii) Preparation of starch and calcium mixture 20.0 g of tapioca starch (STT) was dispersed in 200 ml of deionized water at ambient temperature in a 600 ml flask using overhead stirring. 8.57 g of glycerol was then added and the suspension was stirred. The suspension was then sonicated for 20 minutes at 95% amplitude using a Bandelin sonicator with a 1 second on, 0.2 second off cycle. 0.41 g of CaCl2 was added to the solution and stirred. The solution was then placed in an 80°C sonicator bath for 1 minute to remove air bubbles.

[0199] (iv) Film formation - starch / calcium layer 20 ml of the mix produced in step (iii) was poured into a 50 ml Falcon tube. The mix was then further degassed by removing large air bubbles with a pipette, cooled to 55°C, and spread using a knife blade onto the exposed surface of the dry film prepared in step (ii) (i.e., the surface not in contact with the glass plate) to obtain a wet film of the starch mix approximately 250 microns thick. The plate was then placed in an oven at 80°C for 30 minutes to form a multilayer film.

[0200] Example 10: Preparation of starch-alginate multilayer films with calcium ions (i) Preparation of starch and calcium mixture 20.0 g of tapioca starch (STT) was dispersed in 200 ml of deionized water at ambient temperature in a 600 ml flask using overhead stirring. 8.57 g of glycerol was then added and the suspension was stirred. The suspension was then sonicated for 20 minutes at 95% amplitude using a Bandelin sonicator with a 1 second on, 0.2 second off cycle. 0.41 g of CaCl2 was added to the solution and stirred. The solution was then placed in an 80°C sonicator bath for 1 minute to remove air bubbles.

[0201] (ii) Film formation – starch / calcium layer 20 ml of the mix produced in step (i) was poured into a 50 ml Falcon tube. The mix was then further degassed by removing large air bubbles with a pipette, cooled to 55°C, and then poured onto a flat glass plate with a Mylar® surface. A knife blade was used to spread the liquid evenly, resulting in a wet film of the starch mix approximately 250 microns thick. The plate was then placed in an 80°C oven for 30 minutes to form a film.

[0202] (iii) Preparation of alginate mixture 400 ml of water was mixed with 14 g of alginic acid in a 600 ml beaker at ambient temperature using an overhead stirrer to form a homogeneous solution. 6 g of glycerol was then added with stirring, followed by 4 drops of antifoaming agent. The mixture was stirred for 45 minutes.

[0203] (iv) Film formation—alginate layer 50 ml of the mix produced in step (iii) was poured into a 50 ml Falcon tube. The mix was then removed and spread using a knife blade onto the exposed surface of the dried film prepared in step (ii) (i.e., the surface not in contact with the glass plate) to obtain a wet film of the alginate mix approximately 1100 microns thick. The glass plate was then allowed to dry overnight at ambient temperature to form a multilayer film.

[0204] Example 11: Measurement of film tensile strength, elongation, seal strength, and water dispersibility The tensile strength and elongation at break of the films of Examples 4 and 7-10, and Comparative Example 2 were tested according to the methods outlined in Example 5.

[0205] The seal strength of the films of Examples 4 and 7-10, and Comparative Example 2, was tested according to the method outlined in Example 6, except a sealing temperature of 100° C. and a dwell time of 1 second were used.

[0206] The water-dispersibility of the films of Examples 4 and 7-10 and Comparative Example 2 was evaluated using 0.75 g samples of each of the final films conditioned at 55% relative humidity and 20°C. The samples were mixed in a 600 ml beaker in 300 ml of both 20°C reverse osmosis water and freshly boiled reverse osmosis water (i.e., having a temperature range of 75.1°C to 90.2°C) using an overhead stirrer at 300 rpm for 3 minutes at room temperature. The final mixes were visually inspected for residual particles, and the size of the residual particles was used to judge water-dispersibility on the following scale: Very Low—Most particles >30 mm; Low—Most particles about 20-30 mm; Average—Most particles about 10-20 mm; High—Most particles about 1-10 mm; Very High—Most particles less than 1 mm; Max—No visible particles. Dispersibility is reported as the average of two different temperature observations, each of which can be assigned an integer value for these purposes.

[0207] The results of all these tests are shown in Table 6 below.

[0208] [Table 6] The results show that the inclusion of calcium ions in the alginate monolayer (Example 7) leads to lower values ​​of seal strength, whereas in the case of the starch monolayer (Example 8), the inclusion of calcium ions reduces the seal strength to lower, but still acceptable, values ​​compared to the starch monolayer without calcium ions (Example 2).

[0209] At low heat sealing temperatures (e.g., 100°C as used herein), the multilayer film without calcium ions (Example 4) had a seal strength of 194.8 N / m, but the multilayer film with calcium ions in the starch layer 2+ The inclusion of Ca ions increases the seal strength to 516-600 N / m (Examples 9 and 10). Without wishing to be bound by theory, this is due to the interaction of alginate ions and Ca at the interface between the two layers. 2+This is thought to be due to a small amount of cross-linking occurring between the Ca ions. Interestingly, this effect can be achieved by first casting either the alginate or starch layer. 2+ In the absence of Ca ions, the initial starch layer is destroyed due to the high water content of the alginate mixture being cast, making it virtually impossible to cast the starch layer initially. 2+ This is possible by including ions. Again, without wishing to be bound by theory, it is believed that this is due to the presence of alginate / Ca ions at the interface between the two layers which provides a barrier to water. 2+ This is believed to be due to crosslinking. Furthermore, it was found that the multilayer in which the starch layer was formed first (Example 10) had higher tensile strength and elongation than the multilayer in which the alginate layer was formed first (Example 9). Without wishing to be bound by any theory, it is believed that crosslinking begins when the alginate layer interacts with calcium ions. When the alginate layer is formed first (Example 9), the alginate is dry and solid when the wet starch begins to dissolve at the interface due to the water it carries. Thus, Example 9 also crosslinks at the interface, but because the remaining bulk of the layer is solid, the bulk remains uncrosslinked. When the starch layer is formed first (Example 10), the alginate layer is still wet and highly mobile, allowing a higher level of crosslinking to be achieved by the time it dries completely.

[0210] Ca 2+ The water-dispersibility of the Ca-containing multilayer film depends on the order of layer formation. When the alginate layer is formed first (as in Example 9), the final multilayer film has a Ca 2+The resulting multilayer film has high dispersibility, similar to that of the multilayer film prepared without ions (Example 4). When the starch layer is formed first (as in Example 10), the final multilayer film has very low dispersibility. Without wishing to be bound by any theory, it is believed that in Example 9, crosslinking is achieved only at the interface of the two layers, whereas in Example 10, crosslinking is achieved over a larger volume. Thus, the order of layer formation can be used as a means to control the water-dispersibility of the film (e.g., for different end-use applications) while maintaining good heat-sealing properties.

[0211] Example 12: Moisture content of films The moisture content of the various films prepared in the above examples was measured using an Ohaus MB23 moisture analyzer, with the film samples first conditioned at 55% relative humidity and a temperature of 20° C. The results are shown in Table 7 below.

[0212] [Table 7] Example 13: Dispersion of Laundry Detergent Sachets The multilayer film of Example 9 was used to produce sachets by heat sealing along the length and edges of the film using an RS PRO heat sealer on Power 2. The sealed sachets contained concentrated liquid laundry detergent for use in liquid laundry pods.

[0213] The sachets were easily handled and maintained their integrity. When added to 250 ml of water at 20°C in a 400 ml beaker and stirred at approximately 340 rpm using a magnetic stirrer, the sachets disintegrated and completely released their contents after approximately 2 minutes and 20 seconds, as shown in Figures 1a-1g.

[0214] This example demonstrates one of several uses for the multilayer film of the present invention: preparing heat-sealed sachets for providing single-dose liquid laundry detergent. The sachets are safe for consumer handling and release the detergent upon contact with water in a washing machine.

[0215] Example 14: Preparation of alginate-starch multilayer films with mixed plasticizers (i) Preparation of alginate mixture In a plastic container, 6.49 g of oleic acid and 3.20 g of polysorbate 80 were added to 200 ml of deionized water, which was sonicated for 5 minutes at 50% amplitude using a Bandelin sonicator with a cycle of 1 second on, 0.2 seconds off to form an emulsion.

[0216] The following room temperature ingredients were added to a Klarstein Grand Prix food processor (500 W power, 2.5 liter volume) equipped with four standard stainless steel blades while mixing on speed 4: 1800.00 g of reverse osmosis water, 56.54 g of glycerol, and 56.54 g of sorbitol. The sonicated oleic acid emulsion prepared above was then added to this mixture, followed by 210.00 g of Vivapure® sodium alginate.

[0217] The food processor was set to a temperature of 85°C and allowed to mix for 60 minutes, skimming any material that had accumulated on the sides back into the mixture every 10 minutes.

[0218] The mixture was then transferred to a Hauschild Speedmixer and mixed at 50 mbar and 1500 rpm for 3 minutes and allowed to cool to room temperature.

[0219] (ii) Film formation—alginate layer 80-100 ml of the mixture produced in step (i) was poured onto a flat glass plate at room temperature. Using an RK Print K303S multicoater equipped with a doctor blade set at speed 3, the liquid was spread evenly onto the plate to obtain a 600 micron wet film of the alginate mixture. The glass plate was then dried in an oven at 50°C for 40 minutes to form a dry film layer.

[0220] (iii) Preparation of starch mixture In a Klarstein Grand Prix food processor (500W power, 2.5 liter volume) equipped with four standard stainless steel blades, the following room temperature ingredients were added while mixing on speed 4: 2000.00 g reverse osmosis water, 45.00 g glycerol, and 45.00 g sorbitol, followed by 210.00 g tapioca starch (STT).

[0221] The food processor was set to a temperature of 85°C and allowed to mix for 60 minutes, skimming any material that had accumulated on the sides back into the mixture every 10 minutes.

[0222] The mixture was then transferred to a Hauschild Speedmixer and mixed at 50 mbar and 1500 rpm for 3 minutes and allowed to cool to room temperature.

[0223] (iv) Film formation - starch layer 30-45 ml of the mix produced in step (iii) was poured at room temperature onto the exposed surface of the dried film prepared in step (ii) (i.e., the surface not in contact with the glass plate) and then spread using an RK Print K303S multicoater equipped with a doctor knife blade set at speed 3 to obtain a wet film of the starch mixture approximately 350 microns thick. The plate was then placed in a 50°C oven for 15 minutes to form a multilayer film.

[0224] Example 15: Preparation of alginate-starch multilayer films on a solvent casting line (i) Preparation of alginate mixture For each film, the alginate layer was prepared by first adding the following room temperature ingredients to a Klarstein Grand Prix food processor (500 W power, 2.5 liter volume) equipped with four standard stainless steel blades while mixing at speed 4: a) For Film 15A: 2000 g reverse osmosis water, 90.00 g glycerol, and 210.00 g Vivapur® sodium alginate.

[0225] b) For Film 15B: 2000 g reverse osmosis water, 90.00 g glycerol, and 210.00 g Vivapur® sodium alginate.

[0226] c) For Film 15C: 2000 g reverse osmosis water, 56.54 g glycerol, 56.54 g sorbitol, and 210.00 g Vivapur® sodium alginate.

[0227] d) For Film 15D: 2000 g reverse osmosis water, 56.54 g glycerol, 56.54 g sorbitol, and 210.00 g Vivapur® sodium alginate.

[0228] In each case, the food processor was set to a temperature of 85°C and allowed to mix for 60 minutes, with any material that had accumulated on the sides being skimmed back into the mix every 10 minutes. Each mix was then transferred to a Hauschild Speedmixer and mixed at 50mbar and 1500 rpm for 3 minutes and then allowed to cool to room temperature.

[0229] For film 15E, the preparation of the alginate mixture was similar to Example 14, part (i).

[0230] (ii) Preparation of starch mixture For each film, the starch layer was prepared by first adding the following room temperature ingredients to a Klarstein Grand Prix food processor (500 W power, 2.5 liter volume) equipped with four standard stainless steel blades while mixing at speed 4: a) For Film 15A: 2000 g reverse osmosis water, 75.00 g glycerol, and 0.30 g thymol. Then 300.00 g tapioca starch (STT) was slowly added.

[0231] b) For Film 15B: 2000 g reverse osmosis water, 64.29 g glycerol, 64.29 g sorbitol, and 0.30 g thymol. Then, 300.00 g tapioca starch (STT) was slowly added.

[0232] c) For Film 15C: 2000.00 g reverse osmosis water, 75.00 g glycerol, and 0.30 g thymol. Then 300.00 g tapioca starch (STT) was slowly added.

[0233] d) For Film 15D: 2000.00 g reverse osmosis water, 64.29 g glycerol, 64.29 g sorbitol, and 0.3 g thymol. Then 300.00 g tapioca starch (STT) was slowly added.

[0234] In each case, the food processor was set to a temperature of 85°C and allowed to mix for 60 minutes, with any material that had accumulated on the sides being skimmed back into the mix every 10 minutes. Each mix was then transferred to a Hauschild Speedmixer and mixed at 50mbar and 1500 rpm for 3 minutes and then allowed to cool to room temperature.

[0235] For Film 15E, the preparation of the starch mixture was similar to Example 14, part (iii).

[0236] (iii) Solvent casting Films were prepared on a 500 mm wide Mylar® substrate by a solvent casting wet-on-dry process on a line running at 4 m / min through a 10 m long oven, drying the alginate mixture as the first layer, followed by the starch mixture as the second layer. For Film 15E, the Mylar® substrate was corona treated. Oven conditions were set as shown in Table 8, and roller settings and line speeds were varied to achieve the required dry thickness and moisture content.

[0237] [Table 8] Example 16: Properties of Alginate-Starch Multilayer Films Prepared in a Solvent Casting Line The film prepared in Example 15 was then tested for strength and elongation, the ability to peel the film from a roll, seal strength, and dispersibility in water, all of which are important properties required for the film to be able to be handled on an industrial packaging line, form a pouch around a product, and disperse the package in water to release the contents.

[0238] The tensile strength and elongation at break of the films were tested according to the methods outlined in Example 5. The results are shown in Table 9.

[0239] [Table 9] All films had good tensile strength and elongation, making them suitable for packaging lines.

[0240] Film peeling was tested according to the "Peel Test" described herein. Prior to rolling, samples were equilibrated at the selected relative humidity for 24 hours. Typically, tests were conducted at 33%, 44%, 55%, and 75% relative humidity to cover the range of humidity experienced in industrial environments. Using a small 1 cm diameter cardboard core, a strip of film, typically 25 cm long and 4 cm wide, was rolled onto the cardboard core. The rolled film was allowed to stand at 23°C for 24 hours at the selected humidity. The film was then peeled from the roll and rated according to the scale in Table 10. The results are shown in Table 11. [Table 10] The seal strength of the films was tested according to the method outlined in Example 6, except a seal temperature of 130°C and a dwell time of 1 second and 4 bar were used. The results are shown in Table 11.

[0241] The water dispersibility was tested by the method shown in Example 11. The results are shown in Table 11.

[0242] [Table 11] In the peel test, Films 15A and 15B were very difficult to unwind from the roll and failed at all relative humidities. This made it difficult to use a casting line process because the final film could not be rolled, but other casting and drying techniques could be used. Both of these films had only glycerol as a plasticizer in the first layer.

[0243] Both Film 15C and Film 15D passed the peel test with no resistance at 33% RH and some resistance at 55% RH. Both films had a first layer with a mixed plasticizer system of both glycerol and sorbitol.

[0244] Film 15E also passed the peel test with no resistance at 33% RH, very little resistance at 55% RH, and some resistance at 75% RH. This film contained a first layer with a mixed plasticizer system of glycerol, sorbitol, and a fatty acid, oleic acid.

[0245] Films 15C, 15D, and 15E all had good maximum heat seal strength. Films 15A and 15B were also suitable for heat sealing because they have the same second layer as Films 15C and 15D. All of these films would also be suitable for preparing sealed pouches and other sealed packages.

[0246] All films had very good dispersibility in water, demonstrating that sachets formed from these films are suitable for releasing the contents of the sachet into water during use in a dishwasher, washing machine, or shower, bathtub, or sink, etc.

[0247] Example 17: Properties of Alginate-Starch Multilayer Films with Propylene Glycol (i) Preparation of alginate mixture To a Klarstein Grand Prix food processor (500 W power, 2.5 liter volume) equipped with four standard stainless steel blades, the following room temperature ingredients were added while mixing on speed 4: 2000 g reverse osmosis water, 35 g glycerol, 35 g sorbitol, 70 g propylene glycol, and 210 g Vivapur® alginate.

[0248] The food processor was set to a temperature of 85°C and allowed to mix for 60 minutes, skimming any material that had accumulated on the sides back into the mix every 10 minutes. The mixture was then transferred to a Hauschild Speedmixer and mixed at 50 mbar and 1500 rpm for 3 minutes and allowed to cool to room temperature.

[0249] (ii) Film formation—alginate layer 80-100 ml of the mixture produced in step (i) was poured onto a flat glass plate at room temperature. Using an RK Print K303S multicoater equipped with a doctor blade set at speed 3, the liquid was spread evenly onto the plate to obtain a 600 micron wet film of the alginate mixture. The glass plate was then dried in an oven at 50°C for 40 minutes to form a dry film layer.

[0250] (iii) Preparation of starch mixture In a Klarstein Grand Prix food processor (500W, 2.5 liter capacity) equipped with four standard stainless steel blades, the following room temperature ingredients were added while mixing on speed 4: 2000.00g reverse osmosis water, 90.00g glycerol, and then 210.00g tapioca starch (STT).

[0251] The food processor was set to a temperature of 85°C and allowed to mix for 60 minutes, skimming any material that had accumulated on the sides back into the mix every 10 minutes. The mixture was then transferred to a Hauschild Speedmixer and mixed at 50 mbar and 1500 rpm for 3 minutes and allowed to cool to room temperature.

[0252] (iv) Film formation - starch layer 30-45 ml of the mix produced in step (iii) was poured at room temperature onto the exposed surface of the dried film prepared in step (ii) (i.e., the surface not in contact with the glass plate) and then spread using an RK Print K303S multicoater equipped with a doctor knife blade set at speed 3 to obtain a wet film of the starch mixture approximately 350 microns thick. The plate was then placed in a 50°C oven for 15 minutes to form a multilayer film.

[0253] The prepared Film 17A had good mechanical properties. Peel was tested according to the "Peel Test" described in Example 15. The seal strength of the film was tested according to the method outlined in Example 6, except that a seal temperature of 130°C, a dwell time of 1 second, and 4 bar were used.

[0254] The results are shown in Table 11.

[0255] [Table 12] Film 17A contained a mixture of the plasticizers glycerol, sorbitol, and propylene glycol in the first layer. The propylene glycol had no detrimental effect on the heat seal, as can be seen by comparing it with the similar values ​​for Film 15C. The peel performance of Film 17A was slightly improved relative to 15C.

Claims

1. A film, a first layer, based on a total weight of the first layer, at least 20% by weight of one or more monovalent alginates, and a first layer comprising at least 5 wt. % of one or more organic plasticizers; a second layer, based on a total weight of the second layer, one or more carbohydrates other than alginic acid and its salts; at least 5% by weight of one or more organic plasticizers; and a second layer comprising less than 20% by weight of alginate; A film wherein one surface of the second layer is sealed to one surface of the first layer.

2. The film of claim 1, wherein the film has a thickness of from 20 μm to 120 μm.

3. 3. The film of claim 1 or 2, wherein the first layer further comprises one or more divalent alginates selected from calcium alginate and magnesium alginate.

4. 4. The film of any one of claims 1 to 3, wherein the second layer has an onset melting temperature in the range of 55°C to 85°C, determined as described in Example 3 herein.

5. The film of any one of claims 1 to 4, wherein the second layer comprises starch and / or pullulan.

6. 6. The film according to any one of claims 1 to 5, wherein the film comprises 3 to 90 wt. %, preferably 15 to 85 wt. %, more preferably 25 to 80 wt. %, and most preferably 35 to 70 wt. % of one or more alginates, based on the total weight of the film, as determined according to the HPLC method in Journal of Chromatographic Science 2013;51:208-214.

7. 7. A film according to any one of claims 1 to 6, wherein the film has a heat seal strength of at least 40 N / m, preferably at least 60 N / m, more preferably at least 80 N / m, even more preferably at least 100 N / m, and most preferably at least 120 N / m, when measured according to ASTM F88 / F88M-15 at 55% relative humidity and 20°C, after the film has been conditioned at 55% relative humidity and 20°C for at least 1 hour and then sealed at a temperature of 120°C and a pressure of 1 to 3 bar applied for 1 second.

8. 8. The film according to any one of claims 1 to 7, wherein the organic plasticizer in the first layer is selected from glycerol, polyethylene glycol, propylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, oleic acid, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, and mixtures thereof, with a mixture of glycerol, sorbitol, and oleic acid being preferred.

9. 9. The film according to any one of claims 1 to 8, wherein the organic plasticizer in the second layer is selected from glycerol, polyethylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, glucose, mannose, fructose, sucrose, urea, lecithin, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, and mixtures thereof, with a mixture of glycerol and sorbitol being preferred.

10. A process for preparing the film of any one of claims 1 to 9, comprising: (i) a first layer, based on the total weight of the first layer: at least 20% by weight of one or more monovalent alginates, and providing a first layer comprising at least 5% by weight of one or more organic plasticizers; (ii) a second layer, based on the total weight of the second layer: one or more carbohydrates other than alginic acid and its salts; at least 5% by weight of one or more organic plasticizers; and providing a second layer comprising less than 20% by weight alginate; (iii) sealing one surface of said second layer to one surface of said first layer.

11. A product encapsulated by the film according to any one of claims 1 to 9.

12. 12. The article of manufacture of claim 11, wherein the film is more than 75%, preferably more than 80%, more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95% biodegradable according to ASTM D6691 after 28 days of testing.

13. 1. A method of encapsulating a product, comprising: (i) encasing the product in the film of any one of claims 1 to 9, with the first layer being the outer layer; (ii) heat sealing the film around the product to form a pouch.

14. 14. The method according to claim 13, wherein the duration of step (ii) is less than 2 seconds, more preferably less than 1 second, more preferably less than 0.5 seconds, and wherein step (ii) is carried out at a temperature less than 160°C, preferably less than 140°C, preferably less than 120°C.

15. Use of a film according to any one of claims 1 to 9 for enclosing a product and / or for preparing a sachet.

16. A sachet prepared by the method of claim 13 or 14.

17. A method for releasing a product encapsulated in a film according to any one of claims 1 to 9, comprising the steps of: (i) placing the encapsulated product in water; (ii) dispersing said film, thereby releasing said product.

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