Double-layered film

Abstract

This invention relates to a membrane comprising: a first layer, based on the total weight of the first layer, comprising at least 20% by weight of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum, and mixtures thereof, and at least 5% by weight of one or more organic plasticizers; and a second layer, based on the total weight of the second layer, comprising at least one material selected from: plant-derived polysaccharide (wherein the plant-derived polysaccharide is starch); fungal-derived polysaccharide (wherein the fungal-derived polysaccharide is pullulan); and agar, and at least 5% by weight of one or more organic plasticizers; the invention relates to a method for preparing the membrane, the use of the membrane, and a method for using the membrane.

Description

Invention Field

[0001] This invention relates to the field of heat-sealable, highly biodegradable membranes. The membranes of this invention can be used to package products (e.g., powder and liquid products) into pouches using existing heat-sealing equipment at commercially viable production rates. In particular, the membranes of this invention can be used in vertical form-fill-seal (VFFS) or horizontal form-fill-seal (HFFS) packaging equipment, as well as pod forming and filling equipment (e.g., the Hydroforma pod-making machine from Mespack), without major equipment modifications. The membranes of this invention use readily available, inexpensive natural materials that do not require complex or expensive chemical modifications. The membranes are free of synthetic polymers and are rapidly and completely biodegradable. The membranes are soluble in water or dispersible in water. background

[0002] Packaging materials made from renewable materials are gaining increasing attention and importance due to environmental pressures demanding a reduction in petroleum-based feedstocks. These packaging materials include films, particularly those used to wrap and / or seal products. Examples of products packaged using films include sachets, capsules, pouches, stand-up pouches, packets, and bags. Ideally, packaging materials should be highly biodegradable in addition to being derived from renewable sources, thereby minimizing waste disposal issues. Typically, products made from renewable natural raw materials are highly biodegradable unless chemically modified. Chemical modification significantly reduces biodegradability.

[0003] Some packaging films combine natural and synthetic materials. These products typically offer improved environmental properties compared to equivalent products using only synthetic materials. Furthermore, they can provide an optimal balance of physical properties such as strength and barrier properties. However, using synthetic, and often non-biodegradable, materials inherently means that their biodegradability is inferior to products using natural raw materials.

[0004] Water-soluble films made from polyvinyl alcohol are widely available and used—for example, in detergent packaging. They are often marketed as environmentally friendly. An example is Monosol M-8630 from Monosol (now part of Kuraray). Typically, such films are soluble, but in reality, they exhibit poor biodegradability in marine biodegradation tests and can accumulate in the environment.

[0005] Some product and packaging applications require that the packaging materials themselves be edible. In this context, "edible" means that all materials are classified as safe for consumption, regardless of whether they can be digested by humans or provide human nutrition.

[0006] Many biopolymers or naturally derived materials can be used to manufacture packaging films. Widely used examples of biopolymer films include those based on starch and cellulose. Starch is particularly widely used due to its low cost and easy availability. Typically, starch is chemically modified to improve its processability and functionality. One example of modified starch is hydroxypropylated amylose. Other substituents can be hydroxyethyl or hydroxybutyl to form hydroxy ethers, or anhydrides such as maleic phthalic acid or octenyl succinic anhydride can be used to produce starch ester derivatives. Starch films typically exhibit high tensile strength at moderate humidity (e.g., 20°C, 30% to 50% relative humidity (RH)), but generally become much weaker at higher humidity unless they have been highly chemically modified. In particular, many starch films are very sensitive during low-temperature storage because starch is prone to retrogradation.

[0007] Many starch-based products, such as compostable bags, contain significant levels of polybutylene terephthalate (PBAT) to improve their processability and physical properties. PBAT is a biodegradable synthetic polymer. However, it is clearly derived from non-renewable raw materials. Examples of starch-based films are those sold by Plantic Technologies Ltd (now part of Kuraray), which contain modified starch and are available as single-layer and multilayer films.

[0008] Cellulose-based polymers and materials can also form membranes and are widely used. Typically, cellulose membranes are made from so-called “regenerated” cellulose, where cellulose fibers are dissolved in carbon disulfide under alkaline conditions to form a viscose. The viscose is then contacted with an acidic solution to “regenerate” the cellulose. This type of process is resource and energy intensive, and the resulting cellulose membranes are either completely insoluble in water or non-dispersible in water, and they cannot be heat-sealed. Regenerated cellulose is used in NatureFlex membranes, a cellulose-based compostable packaging membrane marketed by Futamura. Other cellulose materials include hydroxypropyl methylcellulose (HPMC) and carboxymethyl cellulose (CMC). HPMC membranes have long been used in the medical field as tablet coatings. However, the synthesis of HPMC itself requires significant inputs and is therefore relatively expensive. Due to the degree of synthetic modification it undergoes, it is not entirely biodegradable.

[0009] Other biopolymers that can be used to make membranes include proteins of both animal and plant origin. Examples of animal proteins that can be used to form membranes include gelatin, collagen, and casein. Gelatin is widely used as a material for tablets and capsules. Casein (a milk protein collected from whey) has long been used to make plastic materials and can be formed into soluble and thermoformable granules or sheets. Such materials do have very good biodegradable properties, but they are animal-derived. Therefore, some people have ethical and moral concerns about the use of such products. Furthermore, in terms of efficient resource use, it is generally better to use plant materials directly rather than indirectly by feeding plants to animals.

[0010] The use of biopolymers in the manufacture of membranes and coatings is becoming increasingly widespread, and ongoing efforts are needed to find alternatives to non-renewable raw materials such as petroleum. This field is vast and broad; the examples given below are for illustrative purposes only.

[0011] Many biopolymers are in use, including plant-based, algae-based, fungal-based, and animal-based materials. Examples of animal-based materials used to manufacture films and coatings include collagen, gelatin, chitosan, shellac, and casein. Examples of plant-based materials used include starch, cellulose, proteins (including pea, soybean, corn, and potato), pectin, etc. Examples of algae-based materials include alginate, carrageenan, furcellaran, and other gums. One example of a fungal-based material is pullulan. The reasons for using biopolymers in these applications are wide-ranging, from the desire to use renewable raw materials to have 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. There is a need to use plant-derived, algae-derived, or fungal-derived biopolymers instead of animal-derived biopolymers, both for ethical and resource efficiency reasons.

[0012] Biopolymers are complex materials and are generally more difficult to process and handle than synthetic polymers. They are typically sensitive to moisture and lose strength in high-humidity environments. This sensitivity to moisture is often an inherent characteristic of biopolymers due to their natural origin and is a major limitation to their wider use. Other issues include poor thermoplasticity, including in the heat-sealing of biopolymer films. Fast, efficient, and heat-damage-free heat sealing is crucial for the industrial production of pouches and many packaging forms. The problems associated with many biopolymers, particularly their poor water resistance, mean that they are often either chemically modified to improve their properties, blended with synthetic polymers, or laminated with other materials, including other biopolymers, to obtain films with improved properties.

[0013] Polyhydroxyalkanoates (PHAs) are increasingly being used due to their good thermoplasticity. PHAs are natural biopolymers derived from microbial fermentation, but they are slow to biodegrade and insoluble.

[0014] An example of animal-based biopolymers is casein. EP3728477A1 describes thermoplastic casein compositions and packaging films made from thermoplastic casein. US9662400B2 describes chitosan films for medical applications. US6448378B2 describes soluble collagen films for delivering therapeutic drugs. A large-scale application of many edible films, including, in particular, collagen-based films, alginate-based films, and protein-based films, is sausage casings. Sausage casings are single-layered and do not require heat sealing. US3408916 describes collagen films for sausage casings. US6730340B1 describes plant-based biopolymer blends for sausage casings based on a mixture of carrageenan and gellan gum.

[0015] Chemical modification of natural polymers or blending of natural and synthetic polymers can improve the physical and processing properties of membranes made from these materials, but usually reduces overall biodegradability, and is complex and really requires the use of non-renewable materials.

[0016] Starch is inexpensive and can be chemically modified to improve its properties. US5498662 describes gas barrier films comprising blends of poly(meth)acrylic acid and starch. Thermoplastic starch is available under the trade name MATER-BI, supplied by Novamont. US20040242732A1, EP2496644B1, and WO2011080623A2 describe biodegradable polymer compositions based on chemically modified starch and synthetic polymers. These materials can be used to form films.

[0017] Cellulose derivatives, particularly cellulose ethers such as hydroxypropyl methylcellulose (HPMC), are used to manufacture membranes, often for medical applications. EP1045000B1 describes an ingestible HPMC membrane. While such materials are generally safe to ingest, they require a high level of synthetic modification. HPMC is frequently used for drug coating due to its selective pH solubility.

[0018] The use of laminates to overcome some limitations of single biopolymers is known. These laminates can contain two or more layers. One of the layers can be a synthetic polymer. The synthetic polymer can be partially or fully biodegradable. Using synthetic polymers is not preferred over using biopolymers because of the use of non-renewable materials, but using a combination of natural and synthetic materials can still be preferred over using entirely synthetic materials. Synthetic polymer layers or highly modified biopolymer layers typically provide enhanced barrier properties or enhanced heat-sealing properties.

[0019] A common type of biopolymer-based laminate is modified starch laminated with a synthetic polymer. One example is EP1581388B1, which describes a co-extrusion method for manufacturing a modified starch film laminated with a biodegradable polyester. US8715816 describes a multilayer film comprising a thermoplastic starch layer and a thermoplastic polyester layer. Other examples of composite laminates are those in which a synthetic polymer is used to provide the heat-sealable layer.

[0020] EP2013290B1 describes a silk fibroin laminated film in which silk fibroin is laminated with another layer (which may be a different protein, such as collagen, or a synthetic polymer). It does not mention heat sealing, and the use of animal products is not preferred.

[0021] WO2023025769 discloses a single-layer carrageenan film for preparing soluble laundry capsules. The capsules are formed by sealing the film with an adhesive.

[0022] Marangoni Junior et al. reviewed monolayer membranes of alginate or blends of alginate with other biopolymers in Carbohydrate Polymers, Vol. 252, 117221 (2021).

[0023] Therefore, there is a need to develop films with adjustable solubility and / or dispersibility, possessing sufficiently robust mechanical properties for use as packaging films, including handling during manufacturing and the ability to withstand transportation and storage. A preferred feature is that the film is edible for food packaging to further minimize waste and increase consumer convenience. A preferred feature is that the film is biodegradable for non-food packaging to minimize environmental pollution. Summary of the Invention

[0024] From a first aspect, the present invention provides a membrane comprising: The first layer, based on its total weight, comprises: At least 20% by weight of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum, and mixtures thereof, and At least 5% by weight of one or more organic plasticizers; and The second layer, based on its total weight, comprises: The material is selected from at least one of plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch, and the fungal-derived polysaccharide is pullulan; and At least 5% by weight of one or more organic plasticizers.

[0025] From another perspective, the present invention provides a method for preparing the membrane as described above, comprising the following steps: (i) Provide a first layer, which, based on the total weight of the first layer, comprises: At least 20% by weight of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum, and mixtures thereof, and At least 5% by weight of one or more organic plasticizers; (ii) Provide a second layer, which, based on the total weight of the second layer, comprises: The material is selected from at least one of plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch, and the fungal-derived polysaccharide is pullulan; and At least 5% by weight of one or more organic plasticizers; and (iii) The first layer and the second layer are formed into the membrane.

[0026] In another respect, the present invention provides a membrane that can be obtained by or through the methods described herein.

[0027] In another respect, the present invention provides a product encapsulated by a membrane as described above.

[0028] From another perspective, the present invention provides a method for packaging a product, comprising the following steps: (i) Encasing the product in a film as described above; and (ii) Heat seal the film surrounding the product to form a pouch.

[0029] In another respect, the present invention provides a small bag prepared by the method described herein.

[0030] On the other hand, the present invention provides the use of the film as described herein for encapsulating products and / or preparing pouches.

[0031] From another perspective, the present invention provides a method for releasing a product encapsulated in a membrane as described herein, comprising the following steps: (i) Place the packaged product in water at a temperature of at least 40°C; and (ii) Disperse the membrane to release the product. Detailed Implementation

[0032] When sourcing raw materials for the packaging film of the present invention, it is preferable to use biopolymers from non-traditional sources, if possible. Such non-traditional raw materials can be combined with conventional raw materials. "Conventional" refers to biopolymers commonly used as human food, such as starch. A particularly preferred biopolymer for the film of the present invention is red algae-derived polysaccharide, which does not directly compete with food crops and does not require valuable farmland.

[0033] The suitability of the membranes of this invention for commercial use depends not only on their positive environmental properties. The membranes must be processable to effectively encapsulate and protect products. They must remain robust in a variety of environments, including during manufacturing, storage, and end-use. They must meet a variety of different requirements, such as elongation and tensile strength. They must also be heat-sealable to form a closed and sealed packaging layer around the product. As used herein, such packaging is referred to as a “pouch,” but the term includes items generally described as pods, capsules, bags, pouches, and sacks.

[0034] In heat sealing, two films are pressed together and heated for a specified time. The application of heat causes polymer chains at the interface to diffuse and migrate from film to film, forming an adhesive as the seal cools. Not all polymer materials are heat-sealed because the mechanism depends on the behavior of the polymer chains at the interface. If these chains do not readily move or migrate, the film will not seal. The ease of heat sealing is a complex interplay between polymer type, crystallinity, plasticizing effect, temperature, and time.

[0035] Without being bound by theory, the poor heat-sealing behavior of typical red algae-derived membranes is thought to stem from the apparent formation of a denser structure in these materials when heated. This effect has been reported in the art and used in some membrane manufacturing processes where heat treatment is used to create denser membranes with lower permeability. The production of red algae-derived membranes typically involves applying heat to remove water. Heat sealing, by definition, requires the application of heat. Therefore, such materials appear inherently less suitable for heat-sealing applications.

[0036] One established approach to sealing biopolymer membranes is to bond the membranes together using an adhesive. This can be combined with the application of heat and pressure to ensure a good seal. This method is feasible for certain types of equipment, such as the Hydroforma encapsulation machine from Mespack, because the roller design allows for the application of adhesive layers on one or two membranes. Nevertheless, adhesives have their own drawbacks, such as the risk of contaminating the encapsulated material or the adhesive becoming contaminated by the encapsulated product, especially when liquids or powders reduce seal robustness.

[0037] However, many packaging companies use vertical forming-fill-seal (VFFS) or horizontal forming-fill-seal (HFFS) technologies to manufacture pouches. The film of this invention is suitable for both.

[0038] In the VFFS process, the film is pulled vertically through the packaging equipment, folded together, and sealed to form a pouch. Typically, a sheet of film is folded around a filling head and sealed to form a cylinder or tube, then sealed at the bottom, the contents are filled through the filling head, and the top is sealed. This method can be used for both powders and liquids. The need to "pull" the film through the equipment means the film needs to have minimum strength. The film cannot be stretched too much, otherwise it will be difficult to control the correct position and alignment. The film cannot feel sticky, otherwise there will be too much friction on the film as it is pulled through the equipment. This means that spraying or applying a coating to a surface while the film strip is pulled through the packaging line is impractical.

[0039] HFFS equipment is very similar to VFFS equipment, but the membrane travels horizontally. It is particularly suitable for packaging solid goods, such as chocolate bars.

[0040] The membrane of this invention is also applicable to encapsulation. In typical encapsulation equipment, such as Mespack's Hydroforma encapsulation machine, a membrane is drawn downwards into a mold to form a cavity by applying a vacuum, material (e.g., liquid detergent) is placed in the cavity, and a second membrane is used to seal the cavity. Sealing can be achieved by heat sealing or by solvent / adhesive sealing or a combination thereof.

[0041] The inventors have discovered that bilayer membranes comprising a layer rich in red algae-derived polysaccharides and a layer comprising at least one material selected from plant-derived polysaccharides, fungal-derived polysaccharides, and agar can overcome the various challenges mentioned above based on the selection of materials and layer thickness. Such membranes of the present invention exhibit good physical properties, such as tensile strength, under a wide range of conditions. They can be made from natural materials without chemical modification and are inexpensive and readily available. They can have controlled solubility or dispersibility and exhibit very high biodegradability. As used herein, the term "water-soluble membrane" or "water-soluble pouch" refers to a membrane or pouch that dissolves in water at a temperature of 20 to 25°C. As used herein, the term "water-dispersible membrane" or "water-dispersible pouch" refers to a membrane or pouch that disperses in water and achieves "high," "very high," or "maximum" results when tested at temperatures in the range of 75°C to 90°C according to the method described in Example 8. Careful selection of material properties and layer thickness means that they can be heat-sealed under industrially relevant conditions without damaging the pouch. The membranes of the present invention typically require at least one surface of a second layer (i.e., at least one surface of a layer comprising at least one material selected from plant-derived polysaccharides, fungal-derived polysaccharides, and agar) to achieve a good seal, whether by heat sealing or when used in encapsulation equipment (e.g., the Hydroforma encapsulation machine from Mespack) that optionally includes solvent sealing. Attempting to seal two first layers (i.e., two layers comprising at least 20% by weight of at least one red algae-derived polysaccharide) together will not provide a robust seal.

[0042] Any film needs to be heat-sealable within a short time to make any production industrially feasible. Packaging lines are designed so that production rate is proportional to the time required for heat sealing. If a heat-sealing operation takes 5 seconds, a single line can only produce a maximum of 12 pouches per minute. This rate is too low to be economically feasible. For most products, the sealing time needs to be 1 second or less, preferably less than 0.5 seconds, to make any production process economically viable. Therefore, the practical definition of heat-sealability needs to include: in addition to forming a robust seal, it needs to be achieved within 1 second or less, preferably less than 0.5 seconds.

[0043] Heat sealing depends on the temperature at the interface of the two membranes being sealed being high enough to begin melting the material at the interface, thereby initiating its migration and interpenetration. The temperature at the interface of the two membranes depends on the following variables.

[0044] (i) Temperature of the heat-applied sealing plate. The higher the temperature, the faster the interface heats up.

[0045] (ii) The contact time between the heating plate and the membrane. A longer contact time allows more time for heat to be conducted through the membrane to the interface.

[0046] (iii) The pressure of the grippers. Higher pressure means faster heat transfer.

[0047] (iv) The thickness of the film through which heat is conducted. The thicker the film, the longer it takes for the intermediate interface to reach a sufficient temperature.

[0048] (v) Thermal conductivity of the layers forming 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 faster the heat is transferred to the interface.

[0049] As mentioned above, the contact time between the heating plate and the membrane needs to be as short as possible. One way to raise the interface temperature sufficiently to minimize the time required for a seal is to use a high sealing temperature. This is effective, but if the temperature is too high (e.g., >160°C), it can thermally damage the red algae-derived polysaccharide layer of the membrane in contact with the sealing plate, resulting in visual defects and other defects around the seal.

[0050] Therefore, the thermal stability of the layer rich in red algae-derived polysaccharides and the limited time available for heat sealing are crucial. According to the invention, a second layer composition with an initial melt temperature of less than 100°C is preferably selected, and the total thickness of the two layers forming the film together is 20 µm to 120 µm. The initial melt temperature is the temperature at which the composition begins to soften and partially melt. For heat sealing to occur, the material at the interface must be at or above the initial melt temperature. Controlling the film thickness allows sufficient heat to be transferred to the interface within the available time, while providing a film with sufficient thickness and robustness for practicality.

[0051] Therefore, a membrane comprising two layers—the first layer being rich in red algae-derived polysaccharides and the second layer being rich in at least one material selected from plant-derived polysaccharides, fungal-derived polysaccharides, and agar—where the thickness of both layers is controlled within specified limits and where the second layer has an initial melting temperature of less than 100°C—provides a robust and preferred biopolymer-based membrane that can be processed using current heat-sealing equipment.

[0052] Therefore, the present invention provides a membrane comprising: The first layer, based on its total weight, comprises: At least 20% by weight of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum, and mixtures thereof, and At least 5% by weight of one or more organic plasticizers; and The second layer, based on its total weight, comprises: The material is selected from at least one of plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch, and the fungal-derived polysaccharide is pullulan; and At least 5% by weight of one or more organic plasticizers.

[0053] The membrane of the present invention comprises a first layer and a second layer. Preferably, the membrane of the present invention consists of two layers (i.e., a first layer and a second layer). However, the membrane of the present invention may comprise other layers. As those skilled in the art will understand, adjacent layers in the membrane of the present invention cannot be identical in composition (i.e., adjacent layers must have sufficiently different compositions to allow the two layers to be distinguished from each other by methods known in the art). In a preferred membrane of the present invention, one surface of the second layer is sealed to one surface of the first layer.

[0054] The membrane of the present invention comprises a first layer containing at least 20% by weight of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum, and mixtures thereof. Algae are broadly classified into three groups based on the pigments in their biomass: Rhodophyta (red algae), Phaeophyta (brown algae), and Chlorophyta (green algae). These three groups of algae differ in chemical composition and the types of carbohydrates, proteins, and lipids, resulting in the extraction of different biopolymers for industrial applications.

[0055] Macroalgae, originally called seaweed, contain varying proportions of cellulose as structural support for their cell walls, and the gaps within these structures are filled with different levels of polysaccharides. Red algae contain large amounts of agar, carrageenan, and alginate.

[0056] In the preferred membrane of the present invention, red algae-derived polysaccharides are extracted from macroalgae.

[0057] Examples of large red algae (or red seaweeds) include *Eucheuma* sp., *Furcellaria* sp., *Gelidiella* sp., *Gracilaria* sp., *Gigartina* sp., *Gelidium* sp., *Gymnogongrus* sp., *Hypnea* sp., *Kappaphycus* sp., *Lemanea* sp., *Mastocarpus* sp., *Palmaria* sp., *Porphyra* sp., *Schmitzia* sp., *Chondrus* sp., *Acrochaetium* sp., and *Audouinella*. species of the genera *Polysiphonia*, *Solieria*, *Vertebrata*, *Pterocladia*, *Acanthopeltis*, and *Asparagopsis* are preferred, with species of *Euchema*, *Rhodophyta*, *Gnaphalium*, or *Gracilaria* being the most preferred. *Euchema cottonii* is the most preferred.

[0058] In the preferred alternative membrane of this invention, red algae-derived polysaccharides are extracted from microalgae. Microalgae are microscopic algae invisible to the naked eye. They are single-celled organisms but can exist in aggregate form.

[0059] The microalgae and macroalgae from which the red algae-derived polysaccharides for the membranes used in this invention are obtained from natural environments (e.g., when collected when washed ashore by coastal waters), produced by aquaculture in ponds, tanks or pipes, or engineered to produce algae-derived polysaccharides under controlled conditions or similar industrial environments.

[0060] Microalgae and macroalgae are sometimes cultivated to capture carbon from carbon dioxide or methane, with the aim of reducing greenhouse gases in the atmosphere. The algae then become a source for extracting algal-derived polysaccharides.

[0061] Alternatively, natural equivalent polymers can be chemically synthesized outside algal cells to produce the same material as that extracted from naturally grown or cultured algae.

[0062] Therefore, as used in this article, the phrase “red algae-derived polysaccharide” refers to polysaccharides obtained from red macroalgae or red microalgae, whether through extraction processes from naturally grown or cultured red macroalgae or red microalgae, or through synthetic processes to produce the same material as that found in naturally grown or cultured red macroalgae or red microalgae.

[0063] As used in this article, the phrase “red algae-derived polysaccharide” (or “red macroalgae-derived polysaccharide”) refers to polysaccharides obtained from red macroalgae, whether through extraction processes from naturally grown or cultured red macroalgae or through synthetic processes to produce the same material as that found in naturally grown or cultured red macroalgae.

[0064] Carrageenan, agar, and red alginic acid belong to a family of polysaccharides typically obtained from the cell walls of red algae. This contrasts with polysaccharides derived from brown algae (e.g., alginate) or green algae (e.g., uranium).

[0065] Carrageenan, agar, and red alginic acid are all polysaccharides with a galactose backbone, but they differ in the proportion and position of sulfate groups and the proportion of 3,6-dehydrated galactose.

[0066] Carrageenan is a linear anionic sulfated polygalactose formed from disaccharide repeating units, consisting of alternating 3-linked β-D-galactopyranose, 4-linked α-D-galactopyranose, or 4-linked 3,6-dehydro-α-D-galactopyranose. Six different classes exist based on the degree of free sulfation, but only three are commercially available: ι, κ, and λ. Carrageenan is used as an additive in the cosmetics, pharmaceutical, and food industries, primarily for controlling product viscosity and as an emulsifier. κ-carrageenan is specifically classified as food additive E407. Processed *Euphorbia tirucalli* is classified as food additive E407a.

[0067] Agar is a linear sulfated galactose. It is a heterogeneous polysaccharide comprising agarose (typically 70%) and agar gum (typically 30%) polymers. It is known for its gelling properties and is largely produced for food applications (e.g., it is classified as food additive E406), where it can replace animal-derived gelatin and is also used in microbiological assays and techniques. Agarose is a linear polysaccharide composed of repeating units of β-1,3-linked D-galactose and α-1,4-linked 3,6-anhydro-L-galactose. Agar gum has the same backbone as agarose but is slightly branched and contains numerous anionic groups such as pyruvate, sulfate, and glucuronide.

[0068] Red alginate is an anionic sulfated polysaccharide. According to EU legislation, it is classified as a food additive along with κ-carrageenan (E407). Red alginate is a salt of a linear polymer composed of [→4)-3,6-dehydrated-D-galactopyranose-(1→3)-galactopyranose-4′-sulfate-(1→] structural units. The weight-average molar mass values ​​reported in the literature vary between approximately 290-500 kDa.

[0069] Therefore, in the membrane of the present invention, at least one red algae-derived polysaccharide in the first layer is selected from carrageenan and red algae gum or a mixture thereof. Preferably, at least one red algae-derived polysaccharide in the first layer is carrageenan, more preferably ι-carrageenan, κ-carrageenan or λ-carrageenan or a mixture thereof, and most preferably κ-carrageenan.

[0070] In the preferred membrane of the present invention, at least one red algae-derived polysaccharide in the first layer is a red algae-derived polysaccharide. Therefore, in the membrane of the present invention, at least one red algae-derived polysaccharide in the first layer is selected from carrageenan and red algae gum, or mixtures thereof. Preferably, at least one red algae-derived polysaccharide in the first layer is carrageenan, more preferably ι-carrageenan, κ-carrageenan, or λ-carrageenan, or mixtures thereof, and most preferably κ-carrageenan.

[0071] In the preferred membrane of the present invention, the thickness of the first layer is 15 µm to 115 µm.

[0072] In the preferred membrane of the present invention, the thickness of the second layer is 5 µm to 80 µm.

[0073] The preferred thickness of the membrane in this invention is 20 µm to 120 µm, more preferably 30 µm to 100 µm.

[0074] In the preferred membrane of the present invention, as measured according to Example 3 of this specification, the second layer has an initial melting temperature of less than 100°C, preferably less than 85°C, and preferably less than 80°C.

[0075] In the alternative preferred film of the present invention, as measured according to Example 3 of this specification, the second layer has an initial melting temperature of at least 55°C.

[0076] In a particularly preferred film of the present invention, as measured according to Example 3 of this specification, the second layer has an initial melting temperature in the range of 55 to 100°C, preferably 55 to 85°C.

[0077] In a preferred membrane of the present invention, the second layer comprises at least one plant-derived polysaccharide, wherein the plant-derived polysaccharide is starch.

[0078] Starch is a carbohydrate polymer and a major energy storage substance in plants. Starch consists of amylose and / or amylopectin. Amylose is a linear polysaccharide chain composed of glucose monomers linked by α(1,4) glycosidic bonds, constituting approximately 20-30% of starch. Amylopectin is a highly branched polymer composed of glucose subunits. It consists of linear chains of glucose units linked by α(1,4) glycosidic bonds and multiple side chains that branch the structure through α(1,6) glycosidic bonds, constituting 70-80% of starch. In its natural form, starch is typically found in semi-crystalline granular form. Sources of starch include, but are not limited to, the fruits, seeds, and roots or tubers of plants.

[0079] Some starches are classified as waxy starches. Waxy starches are primarily composed of amylopectin and lack a perceptible amount of amylose. Typical waxy starches include waxy corn starch, waxy rice starch, waxy potato starch, and waxy wheat starch.

[0080] Alternatively, some starches are classified as high amylose.

[0081] Modified starch is prepared by physically, enzymatically, or chemically treating natural starch to alter its properties. Starch can be modified, for example, by enzymes, heat treatment, oxidation, or reactions with various chemicals.

[0082] In the membrane of the present invention, the starch may be natural starch or modified starch, or a mixture thereof.

[0083] In the preferred membrane of the present invention, the starch is selected from wheat starch, potato starch, pea starch, waxy potato starch, corn starch, waxy corn starch, high amylose corn starch, tapioca starch, cassava starch, rye starch, sorghum starch, chickpea starch, soybean starch, or mixtures thereof, preferably potato starch.

[0084] In the preferred membrane of the present invention, the starch is selected from wheat starch, potato starch, pea starch, corn starch, high amylose corn starch, cassava starch, tapioca starch, rye starch, sorghum starch, chickpea starch, soybean starch or mixtures thereof, preferably potato starch.

[0085] In the alternative preferred membrane of the present invention, the starch is selected from the following modified starches: 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 octenyl succinate, aluminum octenyl succinate, or cationic starch, or mixtures thereof, preferably acid-treated starch.

[0086] In a preferred membrane of the present invention, the second layer comprises at least one fungal-derived polysaccharide, wherein the fungal-derived polysaccharide is pullulan. Pullulan is a linear polysaccharide composed of three maltotriose units linked by α(1-4) glycosidic bonds, wherein consecutive maltotriose units are linked to each other by α(1-6) glycosidic bonds. It is derived from the fungus *Brucea buddinga* (…). Aureobasidium pullulans Pullulan is produced through starch fermentation. It is primarily used by cells to resist desiccation and predation. The presence of this polysaccharide also facilitates molecular diffusion into and out of cells. It is used as a vegetarian alternative to gelatin in pharmaceutical capsules and other medical applications, such as tissue engineering. It is also used as a food additive, under the E number E1204.

[0087] In the preferred membrane of this invention, the second layer comprises agar. As described above, agar is a red algae-derived polysaccharide and is a mixture of two components, primarily agarose and agar gum.

[0088] In the preferred membrane of the present invention, based on the total weight of the second layer, the second layer comprises 40-95% by weight, preferably 50-80% by weight, more preferably 55-75% by weight, of at least one material selected from plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch and the fungal-derived polysaccharide is pullulan.

[0089] The alternative preferred membrane of the present invention, based on the total weight of the membrane, comprises 1-80% by weight, preferably 7-70% by weight, more preferably 15-50% by weight, of at least one or more materials selected from plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch and the fungal-derived polysaccharide is pullulan.

[0090] According to the method described in Glueck et al., 1980, Zeitschrift für Lebensmittel-Untersuchung und -Forschung, 170, 272-279, the preferred membrane of the present invention, based on the total weight of the membrane, contains 3-90% by weight, preferably 15-85% by weight, more preferably 25-80% by weight, and most preferably 35-70% by weight of red algae-derived polysaccharides, said red algae-derived polysaccharides being selected from carrageenan, red algae gum, and mixtures thereof.

[0091] Glueck U and Their HP, 1980, Quantitative determination of some thickenersin dairy products, Zeitschrift für Lebensmittel-Untersuchung und -ForschungArticles 170, 272-279 describe analytical methods for identifying and quantifying carrageenan, red algae gum, agar, and other non-red algae-derived polysaccharides in dairy products. These polysaccharides are extracted from food, and fats, starches, proteins, and carbohydrates are removed by extraction or degradation. This method is also applicable to determining the red algae-derived polysaccharide content of the membranes of this invention. The obtained polysaccharide fractions are analyzed by gas chromatography after hydrolysis with trifluoroacetic acid and derivatization of the resulting monosaccharides with hydroxylamine hydrochloride and acetic anhydride to form aldehyde nitrile acetate derivatives. The polysaccharides can be qualitatively identified by their characteristic monosaccharide patterns and quantified by a single monosaccharide peak. In the case of carrageenan, the only hydrolysis product is galactose.

[0092] Several other analytical methods have been developed to determine carrageenan. These methods include GC, HPLC, colorimetry, electrophoresis, immunoassay, and potentiometry. An overview is provided in Roberts MA and Quemener B, 1999, in their review, *Measurement of carrageenans in food: challenges, progress, and trends in analysis*, *Trends in Food Science and Technology*, 10, 169-181.

[0093] The preferred membrane of the present invention contains 10-50% by weight, preferably 15-45% by weight, and more preferably 20-40% by weight of one or more organic plasticizers, based on the total weight of the membrane.

[0094] Preferably, the one or more organic plasticizers in the first layer are independently selected from: a) A polyol formed from 1 to 20 repeating hydroxylation units, each unit containing 2 to 6 carbon atoms, provided that when the polyol is formed from only one repeating unit, it has at least 4 carbon atoms, excluding sorbitol. b) Ethers, thioethers, organic esters, acetals, and amino derivatives of polyols formed from 1 to 20 repeating hydroxylation units, each unit containing 2 to 6 carbon atoms, excluding acetates, triethyl citrate, and tributyl citrate of glycerol. c) The reaction product of a polyol having 1 to 20 repeating hydroxylation units with a chain extender, each repeating hydroxylation unit containing 2 to 6 carbon atoms. d) An oxidation product of a polyol having 1 to 20 repeating hydroxylation units, each repeating hydroxylation unit comprising 2 to 6 carbon atoms, which contains at least one aldehyde or carboxyl functional group or a mixture thereof.

[0095] More preferably, the one or more organic plasticizers in the first layer are independently selected from glycerol, diglycerol, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethylpropane, polyether polyol, 2-methyl-1,3-propanediol, ethanolamine, polyethylene glycol, propylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, fatty acids (e.g., oleic acid), monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, and organic acids (e.g., lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, or gluconic acid), or mixtures thereof, most preferably a mixture of glycerol, sorbitol, and oleic acid. Preferably, the plasticizer is plant-derived.

[0096] In the preferred film of the present invention, the one or more organic plasticizers are present in the first layer in an amount of 10-50% by weight, more preferably 20-40% by weight, based on dry solids.

[0097] In the alternative preferred membrane of the present invention, the weight ratio of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum and mixtures thereof in the first layer to the organic plasticizer is in the range of 4:1 to 1:1.

[0098] Preferably, the one or more organic plasticizers in the second layer are independently selected from: a) A polyol formed from 1 to 20 repeating hydroxylation units, each unit containing 2 to 6 carbon atoms, provided that when the polyol is formed from only one repeating unit, it has at least 4 carbon atoms, excluding sorbitol. b) Ethers, thioethers, organic esters, acetals, and amino derivatives of polyols formed from 1 to 20 repeating hydroxylation units, each unit containing 2 to 6 carbon atoms, excluding acetates, triethyl citrate, and tributyl citrate of glycerol. c) The reaction product of a polyol having 1 to 20 repeating hydroxylation units, each unit containing 2 to 6 carbon atoms, with a chain extender. d) An oxidation product of a polyol having 1 to 20 repeating hydroxylation units, each unit comprising 2 to 6 carbon atoms, wherein the polyol contains at least one aldehyde or carboxyl functional group or a mixture thereof.

[0099] More preferably, the one or more organic plasticizers in the second layer are independently selected from glycerol, diglycerol, polyethylene glycol, propylene glycol, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethylpropane, polyether polyol, 2-methyl-1,3-propanediol, ethanolamine, sorbitol, mannitol, xylitol, triethyl citrate, fatty acids (e.g., oleic acid), monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, waxes, amino acids, and organic acids (e.g., lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, or gluconic acid), or mixtures thereof, most preferably a mixture of glycerol and sorbitol. Preferably, the plasticizer is plant-derived.

[0100] Alternatively, the one or more organic plasticizers in the second layer are preferably sugar surfactants comprising at least one sugar moiety. The sugar surfactant preferably consists of at least one, preferably more than two monosaccharide units linked by glycosidic bonds, and may include a moiety referred to as "sugar" (two monosaccharide units) or a moiety derived from three monosaccharides. The monosaccharides of the sugar moiety may be of the same type (homopyransin) or different types (heteropyransin). Preferably, the sugar surfactant is ionic, more preferably anionic, cationic, or amphoteric. More preferably, the sugar surfactant is anionic. The sugar surfactant is preferably selected from functionalized alkyl polysaccharides, fatty acid glucosamides, glycine salts, glycolipid biosurfactants, such as rhamnosyl surfactants (e.g., rhamnolipids) or sophorolipids, or mixtures thereof.

[0101] In the preferred membrane of the present invention, one or more organic plasticizers are present in the second layer in an amount of 10-50% by weight, more preferably 20-40% by weight, based on dry solids.

[0102] In a preferred membrane of the present invention, the weight ratio of at least one material selected from plant-derived polysaccharides, fungal-derived polysaccharides and agar to one or more organic plasticizers in the second layer is in the range of 4:1 to 1:1, wherein the plant-derived polysaccharide is starch and the fungal-derived polysaccharide is pullulan.

[0103] As those skilled in the art will understand, 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. The plasticizer may be emulsified using an emulsifier, preferably a nonionic emulsifier, such as polysorbate, before being incorporated into the mixture with the remaining film material.

[0104] When the film is intended for packaging food, the plasticizer must be suitable for human consumption.

[0105] The preferred membrane of the present invention, at 55% relative humidity and 20°C, contains 5-35% by weight, more preferably 7.5-25% by weight, and most preferably 10-20% by weight of water based on the total weight of the membrane.

[0106] In the preferred membrane of the present invention, the first layer further comprises at least one plant-derived or fungal-derived polysaccharide, more preferably plant-derived polysaccharide, and most preferably starch.

[0107] The preferred membrane of the present invention further comprises one or more additives, such as adhesives, oils, fragrances, dyes, pigments, bittering agents, opacifiers, antimicrobial agents such as thymol, anti-blocking agents, lubricants, or structural reinforcing agents such as cellulose nanofibers, cellulose nanocrystals, and cellulose fibers.

[0108] The membranes of this invention, particularly preferred, also contain bittering agents. These bittering agents impart a safety feature to the membranes of this invention, which are not intended for consumption, making them unpalatable in the event that a child or animal attempts to ingest them. Preferably, the bittering agents are selected from: capsaicins, vanillyl ethyl ether, vanillyl propyl ether, vanillyl butyl ether, vanillin propylene glycol acetal, ethyl vanillin propylene glycol acetal, gingerol, 4-(1-menthoxymethyl)-2-(3'-methoxy-4'-hydroxyphenyl)-1,3-dioxolane, pepper oil, pepper oleoresin, ginger oleoresin, vanillyl vanillin, jambooo oleoresin, Japanese pepper bark extract, sanshool, sanshool, black pepper extract, piperine, piperine, jambooo oleoresin, allyl isothiocyanate, resin toxins, and mixtures thereof. Particularly preferred bittering agents include capsaicins, including capsaicin, dihydrocapsaicin, nordihydrocapsaicin, homodihydrocapsaicin, homocapsaicin, and nonivamide. Capsaicin is a particularly preferred bittering agent.

[0109] Bittering agents may also be selected from denamonium salts, such as denamonium benzoate, saccharin denamonium, denamonium chloride, benzoic benzylamine amide, trichloroanisole, methyl anthranilate, and quinine (and salts of quinine). Other examples of bittering agents include flavonoids, such as quercetin and naringin, naringin, sucrose octaacetate, quassinolides, such as quassinolide and strychnine, and agents derived from plant or vegetable substances, such as compounds derived from capsicum plants, compounds derived from cynaro plant species, alkaloids, and amino acids. Preferably, the bittering agent is selected from denamonium benzoate (e.g., Bitrex®), saccharin denamonium, quinine, or salts of quinine. The chemical name of denamonium is benzyl-[2-[(2,6-dimethylphenyl)amino]-2-oxoethyl]-diethylammonium.

[0110] The bittering agent may have a bitterness value of 1,000 to 10,000,000, measured using the standardized method specified in the European Pharmacopoeia (5th edition, Stuttgart 2005, Volume 1, General Monograph 15 Groups, 2.8.15 bitterness value, page 278).

[0111] In the preferred membrane of the present invention, the bittering agent is present in the membrane in the range of 100 to 5000 ppm, preferably 200 to 3000 ppm, and more preferably 500 to 2000 ppm, based on the total weight of the bittering agent and the membrane.

[0112] As those skilled in the art will understand, the bittering agent may be present in the first layer and / or the second layer.

[0113] Alternatively or concurrently, the bittering agent may be provided as a powdered bittering agent in a powder coating applied to the outer surface of the membrane. As used herein, the term "outer surface" refers to the membrane surface that comes into primary contact with the external environment rather than the encapsulated product during use. As used herein, the term "inner surface" refers to the membrane surface that comes into primary contact with the encapsulated product rather than the external environment during use. As those skilled in the art will understand, the membrane of the present invention may be sealed around the product using a fin seal or an overlap seal. A fin seal is preferred. As used herein, the term "fin seal" or "folded seam" refers to a sealing arrangement in which at least a portion of the two inner surfaces of the membrane are sealed together. As those skilled in the art will understand, a fin seal may be prepared by folding a single membrane or by sealing two separate membranes together. As used herein, the term "overlap seal" or "overlapped seam" refers to a sealing arrangement in which at least a portion of the outer surface of the membrane is sealed together with at least a portion of the inner surface of the membrane. As those skilled in the art will understand, an overlap seal may be prepared by folding a single membrane or by sealing two separate membranes together.

[0114] The preferred membrane of the present invention further comprises layered silicates. Preferably, the layered silicates are serpentine minerals, clay minerals, chlorite minerals, or mica minerals, or mixtures thereof. Preferably, the clay minerals are selected from bentonite, kaolinite, pyrophyllite, vermiculite, and montmorillonite (e.g., montmorillonite, Cloisite, Laponite, lithium montmorillonite, etc.), or mixtures thereof.

[0115] As those skilled in the art will understand, the layered silicate may be present in the first layer and / or the second layer.

[0116] In a preferred membrane of the present invention, the membrane comprises a powder coating on its outer surface, and the powder coating comprises a powder lubricant. As those skilled in the art will understand, the powder coating is not equivalent to a first or second layer of the membrane of the present invention. Rather, the powder coating is applied to the final membrane and is typically a discontinuous coverage of discrete individual particles on the membrane surface. The powder coating may be applied to at least 50%, preferably at least 60%, at least 70%, even more preferably at least 80%, and most preferably at least 90% of the outer surface area of ​​the membrane. The powder coating may be applied by any known technique, such as spraying or passing the membrane through a curtain of powder coating composition. The powder coating may be applied at a rate of 100 cm² / cm². 2 0.5 to 10 mg, preferably per 100 cm 2 Not exceeding 5mg, more preferably per 100cm 2 The powder coating is applied to the outer surface of the membrane at a rate ranging from 1.25 to 2.5 mg. Based on the total weight of the powder coating and the membrane, the powder coating may be applied to or present on the outer surface of the membrane in an amount of 100 ppm or more, preferably 200 ppm or more, more preferably 300 ppm or more. Particularly preferably, the powder coating is applied to or present on the outer surface of the membrane in an amount of 100 to 5000 ppm, preferably 200 to 3000 ppm, more preferably 300 to 2000 ppm.

[0117] The heat-sealing strength of the preferred membrane of the present invention is measured by ASTM F88 / F88M-15 at 55% relative humidity and 20°C to be 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. The measurement is performed after the membrane has been conditioned at 55% relative humidity and 20°C for at least one hour, and then subjected to a pressure of 1 to 3 bar at a temperature of 140°C for 1 second for a fin seal or overlap seal.

[0118] The preferred membrane of this invention is substantially free of divalent metal cations selected from calcium, magnesium, strontium, and zinc. As used herein, the phrase "substantially free of divalent metal cations selected from calcium, magnesium, strontium, and zinc" means, based on the total weight of the membrane, as measured by atomic absorption spectrophotometry (AAS), that the membrane contains less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight, more preferably less than 0.05% by weight, more preferably less than 0.01% by weight, more preferably less than 0.005% by weight, more preferably less than 0.001% by weight, more preferably less than 0.0005% by weight, and most preferably 0% by weight of divalent metal cations selected from calcium, magnesium, strontium, and zinc (i.e., Ca2+, Mg2+, Sr2+, and Zn2+). AAS detects elements in a sample by applying electromagnetic radiation of a characteristic wavelength from a light source. Each element absorbs wavelengths differently, and these absorbances are measured against standards. Preferably, flame atomic absorption spectrophotometry (FASS) is used to analyze calcium, magnesium, strontium, and zinc. Typical sample preparation procedures for solid samples involve digestion with concentrated acids, such as HNO3, HCl, or H2SO4. Other sample preparation methods, including microwave and high-pressure digestion, are also used to decompose samples. After dilution of the digestion solution, the sample can be directly injected into the spectrophotometer.

[0119] Preferably, the membranes of the present invention are free of any divalent metal cations selected from calcium, magnesium, strontium, and zinc (i.e., based on the total weight of the membrane, they contain 0% by weight of divalent metal cations selected from calcium, magnesium, strontium, and zinc). However, as those skilled in the art will understand, the membranes of the present invention may contain contaminant levels of divalent metal cations selected from calcium, magnesium, strontium, and zinc. This may occur, for example, if the method used to prepare the membrane involves using hard water containing about 200 mg / L calcium carbonate and about 200 mg / L magnesium carbonate. The preferred membranes of the present invention are made entirely of food-grade materials.

[0120] According to ISO 14851 (2019), after a 28-day test, the preferred membrane of the present invention is biodegradable in fresh water by more than 75%, more preferably more than 80%, even more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95%.

[0121] According to ASTM D6691, after 28 days of testing, the preferred membrane of the present invention is biodegradable in seawater by more than 75%, more preferably more than 80%, even more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95%.

[0122] The present invention also provides a method for preparing the membrane as described above, comprising the following steps: (i) Provide a first layer, which, based on the total weight of the first layer, comprises: At least 20% by weight of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum and mixtures thereof, and at least 5% by weight of one or more organic plasticizers; (ii) Provide a second layer, which, based on the total weight of the second layer, comprises: The material is selected from at least one of plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch, and the fungal-derived polysaccharide is pullulan; and At least 5% by weight of one or more organic plasticizers; and (iii) The first layer and the second layer are formed into the membrane.

[0123] In a preferred method of the invention, step (iii) includes depositing and adhering a surface of the second layer to a surface of the first layer. As those skilled in the art will understand, depositing and adhering a surface of the second layer to a surface of the first layer does not require complete contact at all points along the interface. Instead, discontinuous contact is contemplated, which may create voids, cavities, or compartments. Alternatively, continuous contact is also contemplated, such that depositing and adhering a surface of the second layer to a surface of the first layer does require complete contact at all points along the interface. As those skilled in the art will understand, continuous or discontinuous contact can also be achieved when sealing the films of the invention together.

[0124] In a preferred method of the present invention, step (i) includes using a pre-formed first layer.

[0125] In the alternative preferred method of the present invention, step (ii) includes using a pre-formed second layer.

[0126] In a preferred method of the present invention, step (i) includes forming the first layer. Preferably, the first layer is formed by casting, lamination, or extrusion.

[0127] In a preferred method of the present invention, step (ii) includes forming the second layer. Preferably, the second layer is formed by casting, lamination, or extrusion.

[0128] The preferred method of the present invention includes the following steps: (a) Mixing at least one red algae-derived polysaccharide selected from carrageenan, red algae gum and mixtures thereof and at least one organic plasticizer in water to form mixture (a); (b) Shape the mixture (a) into the first layer on a surface; (c) Mixing at least one material selected from plant-derived polysaccharides, fungal-derived polysaccharides, and agar, and at least one organic plasticizer in water to form mixture (b), wherein the plant-derived polysaccharide is starch, and the fungal-derived polysaccharide is pullulan; and (d) The mixture (b) is shaped into the second layer on the first layer.

[0129] Preferably, step (a) includes additionally mixing at least one plant-derived or fungal-derived polysaccharide to form the mixture (a).

[0130] Preferably, step (a) is performed at a temperature of 15 to 100°C, more preferably 20 to 80°C, and more preferably 25 to 60°C.

[0131] Preferably, in step (b), the mixture (a) is at a temperature of 15 to 100°C, more preferably 15 to 80°C, and more preferably 15 to 50°C.

[0132] Preferably, step (c) is performed at a temperature of 20 to 100°C, more preferably 50 to 90°C.

[0133] Preferably, in step (d), the mixture (b) is at a temperature of 30 to 70°C, more preferably 30 to 50°C (e.g., 40°C).

[0134] Preferably, the mixture (b) is degassed before step (d).

[0135] The preferred method of the present invention includes the following steps: (a) Mixing at least one material selected from plant-derived polysaccharides, fungal-derived polysaccharides and agar and at least one organic plasticizer in water to form a mixture (c), wherein the plant-derived polysaccharide is starch and the fungal-derived polysaccharide is pullulan; (b) The mixture (c) is shaped into the second layer on one surface; (c) Mixing at least one red algae-derived polysaccharide selected from carrageenan, red algae gum and mixtures thereof and at least one organic plasticizer in water to form a mixture (d); (d) The mixture (d) is shaped into the first layer on the second layer.

[0136] Preferably, step (a) is performed at a temperature of 20 to 100°C, more preferably 50 to 90°C.

[0137] Preferably, in step (b), the mixture (c) is at a temperature of 30 to 70°C, more preferably 30 to 50°C (e.g., 40°C).

[0138] Preferably, the mixture (c) is degassed before step (b).

[0139] Preferably, step (c) includes additionally mixing at least one plant-derived or fungal-derived polysaccharide to form the mixture (d).

[0140] Preferably, step (c) is performed at a temperature of 15 to 100°C, more preferably 20 to 80°C, and more preferably 25 to 60°C.

[0141] Preferably, in step (d), the mixture (d) is at a temperature of 15 to 100°C, more preferably 15 to 80°C, and more preferably 15 to 50°C.

[0142] In a preferred method of the present invention, one or more layers are prepared independently by casting or blown film extrusion, preferably by casting, and more preferably by solvent casting.

[0143] Solvent casting can be a two-step process, in which a first layer of material is cast onto a substrate such as Mylar®, corona-treated Mylar®, or a metal strip. The cast mixture can be applied 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 from the roll and rewound through the production line, allowing a second layer to be cast on top of the first layer, and then dried again in an oven. The cast mixture can again be applied at room temperature or heated. This process can be described as a “wet-dry process.” To control the cast thickness, the casting production line is equipped with a metal roller system, where the gap between the rollers controls the wet thickness of the coating. The production line speed and oven temperature are adjusted to obtain the desired dry film thickness and final moisture content. The final dry film is peeled off from the support substrate, wound onto a core, and stored until needed for wrapping or sealing products and optionally sealing the film to form a pouch.

[0144] 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 strip. The cast mixture can be applied 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. The cast mixture can also be applied at room temperature or heated. This process can be described as a “wet-to-wet process” or a “wet-to-semi-dry process.” To control the cast thickness, the production line is equipped with a metal roller system, where the gap between the rollers controls the wet thickness of the coating. The production line speed and oven temperature are adjusted to obtain the desired final dry film thickness and final moisture content. The final dry film is peeled off from the support substrate, then wound onto a roll and stored until it is needed for wrapping or sealing products and optionally sealing the film to form a pouch.

[0145] In both solvent casting processes, it is important that the final film roll can be easily unwound without damaging the film. This is necessary in the middle of a wet-dry process or when the final film is used in a product packaging line.

[0146] The preferred method of the present invention further includes a step of microperforating the membrane. This step may be advantageous when the product to be encapsulated by the membrane is, for example, a powder product, because microperforation can facilitate the release of powder during use.

[0147] The present invention also provides membranes that are obtained or can be obtained by the methods described above herein.

[0148] The present invention also provides products encapsulated by the membrane as described herein.

[0149] In the preferred product of this invention, the membrane is substantially free of divalent metal cations selected from calcium, magnesium, strontium, and zinc. Preferably, the membrane is free of any divalent metal cations selected from calcium, magnesium, strontium, and zinc.

[0150] In the preferred product of this invention, the membrane is made entirely of food-grade materials.

[0151] In the preferred alternative of the present invention, according to ISO 14851 (2019), after a 28-day test, the membrane is biodegradable in fresh water by more than 75%, more preferably more than 80%, even more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95%.

[0152] In the preferred alternative of the present invention, the membrane is biodegradable in seawater by more than 75% after 28 days of testing, more preferably more than 80%, even more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95%, according to ASTM D6691.

[0153] Preferred products of this invention are food, pharmaceutical products, cleaning products, agricultural products (e.g., animal feed or medicines), chemical products, or cosmetics.

[0154] Water activity is the ratio of the vapor pressure of water above a sample in equilibrium to the vapor pressure of pure water under the same conditions (e.g., temperature). It can be referred to as "free water," indicating that it is unbound and available. Water activity can be easily measured in commercially available devices, such as the HygroPalm 23-AW from Rotronic.

[0155] Preferably, the product of the present invention is a solid or powdered product with a water activity of less than 0.65.

[0156] More preferably, the product of the present invention is a solid or powdered product with a water activity of 0.25 to 0.65, more preferably 0.35 to 0.55 (e.g., 0.45).

[0157] Preferred alternatives to the present invention are solid products selected from: soup or seasoning preparations (e.g., soup cubes), personal care products (e.g., soap bars, body scrubs, or solid shampoos), laundry detergent tablets or bars, or dishwasher detergent tablets.

[0158] Preferably, the product of the present invention is a soup cube, laundry detergent tablet, or dishwasher detergent tablet.

[0159] Preferred alternatives to the present invention are powdered products selected from the following: powdered food, powdered beverage, milk powder, powdered soup, powdered hot chocolate, powdered coffee, powdered tea, tea leaves, soap flakes, powdered laundry detergent, and powdered shampoo.

[0160] Preferably, the product of the present invention is a powdered beverage.

[0161] Preferably, the product of the present invention is an aqueous liquid product selected from the following categories with a water activity of less than 0.65: home care or cleaning products or hair care or body care products.

[0162] More preferably, the product of the present invention is an aqueous liquid product with a water activity of 0.25 to 0.65, more preferably 0.35 to 0.55 (e.g., 0.45).

[0163] The preferred alternatives to the present invention are oily or anhydrous liquids, such as body care oils or anhydrous liquid detergents.

[0164] The present invention also provides a method for packaging a product, comprising the following steps: (i) Encasing the product in a film as described above; and (ii) Heat seal the film surrounding the product to form a pouch.

[0165] As those skilled in the art will understand, the heat-sealing step requires contact between multiple portions of a membrane comprising at least one material selected from plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch and the fungal-derived polysaccharide is pullulan. For example, a composite membrane comprising starch and carrageenan can be sealed onto another composite membrane comprising starch and carrageenan, or sealed to itself. However, if the membrane is, for example, a multilayer membrane comprising starch layers and carrageenan layers, it is generally necessary to seal the membranes together through at least one starch-rich surface to achieve a good seal. Attempting to seal the carrageenan layers together does not provide a robust seal. As those skilled in the art will also understand, starch-starch seals are generally stronger than starch-carrageenan seals, thus allowing for adjustable seal strength.

[0166] In the preferred method of the present invention, the duration of step (ii) is less than 2 seconds, more preferably less than 1 second, and most preferably less than 0.5 seconds.

[0167] In the preferred method of the present invention, step (ii) is performed at a temperature below 160°C, more preferably below 140°C, and most preferably below 120°C.

[0168] The present invention also provides pouches prepared by the methods described herein.

[0169] The preferred pouches of this invention are water-dispersible.

[0170] The membranes of the present invention exhibit high dispersibility in warm water. This means they can be used as packaging materials for products, generating zero waste during the final use of the product. For example, the membranes of the present invention can be used to package detergents, such that the membrane disperses in water during the washing process to release the detergent. Alternatively, the membranes of the present invention can be used to package food, such that the membrane disperses in water during the cooking process to release the food.

[0171] According to the invention, the water dispersibility of the membrane was evaluated using 0.75 g samples of each final membrane conditioned at 55% relative humidity and 20°C. The samples were mixed at 300 rpm for 3 minutes in a 600 ml beaker with 300 ml of 20°C reverse osmosis water and freshly boiled reverse osmosis water (i.e., at 75°C to 90°C) using a top stirrer at room temperature. Any residual particles in the final mixture were visually inspected, and water dispersibility was determined using their size according to the following scale: Very low – most particles >30 mm; Low – most particles about 20-30 mm; Medium – most particles about 10-20 mm; High – most particles about 1-10 mm; Very high – most particles <1 mm; Highest – no visible particles. Advantageously, the residue is completely biodegradable, meaning the membrane has no negative environmental impact.

[0172] The present invention also provides the use of the membrane as described herein for encapsulating products and / or preparing pouches.

[0173] The present invention also provides a method for releasing a product encapsulated in a film as described above, comprising the following steps: (i) Place the packaged product in water at a temperature of at least 40°C; and (ii) Disperse the membrane to release the product.

[0174] In a preferred method of the present invention, in step (i), the packaged product is placed in water at a temperature of at least 50°C, more preferably at least 60°C.

[0175] In the preferred method of the present invention, the product is released in step (ii) during the cooking process.

[0176] In the preferred alternative method of the present invention, the product is released in step (ii) during the washing process. Brief description of the attached figures

[0177] Figure 1a This is a photograph of the small bag prepared in Example 10.

[0178] Figure 1bThis is a photograph taken immediately after the small bag prepared in Example 10 was placed in a beaker containing water at 60°C.

[0179] Figure 1c-1f These are a series of photographs taken at 1 minute, 2 minutes, 3 minutes and 5 minutes after the pouches prepared in Example 10 were placed in a beaker containing water at 60°C.

[0180] Example Material κ-carrageenan was purchased from Tokyo Chemical Industries (TCI).

[0181] Tapioca starch (STT-358 Tapioca Starch Alpha - Instant), potato starch (pregelatinized), corn starch, and rice starch were purchased from BakeRite.

[0182] Food-grade glycerin (APC Pure) and potato starch (hot soluble) were purchased from APC.

[0183] Polysorbate 80 and corn amylopectin (starch derived from corn) were purchased from Sigma-Aldrich.

[0184] Pullulan was purchased from Rongsheng Biotechnology Co., Ltd.

[0185] The maltodextrin was purchased from Sigma-Aldrich Co.

[0186] Oleic acid and sorbitol were purchased from Thermo Fisher Scientific.

[0187] Tesco non-biological liquid laundry detergent capsules were purchased from Tesco supermarkets in the UK.

[0188] In this specification, including the following examples, all references to “ambient temperature” or “room temperature” refer to a temperature of about 20 to 25°C.

[0189] Example 1 (Comparative Example): Preparation of Carrageenan Monolayer Prepare κ-carrageenan monolayer according to the following steps: 1. Preparation of oil-in-water emulsion: Weigh 3.25g of oleic acid and 1.60g of polysorbate 80, and mix them with 20mL of reverse osmosis (RO) water in a 50mL Falcon tube. Sonicate the mixture for 5 minutes using a Bandelin Sonoplus ultrasonic instrument (TS113 probe) at 50% amplitude, with an on-time of 1 second and an off-time of 0.2 seconds.

[0190] 2. While the emulsion is cooling, weigh 996.2g of reverse osmosis (RO) water, 6.67g of glycerin, and 6.67g of sorbitol into a 2L plastic beaker. Mix thoroughly with a spatula. Add 4.73g of the cooled emulsion to the plasticizer-water mixture.

[0191] 3. Transfer the mixture to a Karlstein GrandPrix food processor and add 20g of κ-carrageenan.

[0192] 4. Mix them at 30°C and speed 7 for 30 minutes.

[0193] 5. Transfer the mixed formulation to a high-speed mixing vessel and degas at 1950 rpm and 3 mbar for 5 minutes.

[0194] 6. Immediately after high-speed mixing, use an RK Print K303S multi-function coater (at speed 3) and a doctor blade to cast the solution to a wet thickness of 2250 µm.

[0195] 7. The membrane was then dried at 80°C for 3 hours, followed by overnight drying at room temperature.

[0196] A single-layer film is obtained by peeling a dry film from a substrate.

[0197] Example 2 (Comparative Example): Preparation of Starch Monolayer Prepare a starch monolayer according to the following steps: 1. Weigh 500g of reverse osmosis (RO) water, 10.7g of glycerin, and 10.7g of sorbitol into a 1L plastic beaker. Mix thoroughly with a spatula.

[0198] 2. Transfer the solution to a Karlstein GrandPrix food processor and add 50g of tapioca starch.

[0199] 3. Mix at 85°C at speed 4 for 45 minutes.

[0200] 4. Transfer the mixture to a high-speed mixing vessel and degas at 1950 rpm and 3 mbar for 5 minutes.

[0201] 5. While the solution is still warm, use an RK Print K303S multi-function coater at speed 2 with a doctor blade to cast it to a wet thickness of 1200 µm.

[0202] 6. Then dry the membrane in an oven at 80°C for 45 minutes.

[0203] A single-layer film is obtained by peeling a dry film from a substrate.

[0204] Example 3: Determination of the initial melting temperature and sealing strength of polysaccharide monolayers (i) Preparation of polysaccharide monolayers At ambient temperature, 10.0 g of polysaccharide was dispersed in 100 ml of deionized water in a 250 ml flask using a top stirrer. Then, 4.29 g of glycerol was added and the suspension was stirred. The suspension was then sonicated for 10 minutes using a Bandelin Sonoplus sonicator (TS113 probe) at 95% amplitude, with a 1-second on-off cycle. The solution was then placed in an ultrasonic bath at 80°C for 1 minute to remove any air bubbles.

[0205] Pour 20 ml of the solution into a 50 ml Falcon tube. Further degas the solution by removing large air bubbles with a pipette, then cool it to 55°C and pour it onto a flat glass plate with a Mylar® surface. Spread the liquid evenly using a spatula to obtain a wet film approximately 400 micrometers thick. Then place the plate in an oven at 80°C for 50 minutes to dry the film.

[0206] (ii) Measurement of the initial melting temperature by differential scanning calorimetry (DSC) The membranes prepared in step (i) were conditioned overnight at 55% relative humidity and 20°C. The initial melt temperature was a function of the overall membrane composition, including the moisture level. Small test samples (10–20 mg) were cut from each membrane and accurately weighed. Each sample was placed in a 40 µL aluminum pan (#51119870, purchased from Mettler Toledo) and heated from 25°C to 160°C at a heating rate of 10°C / min in a nitrogen atmosphere using a DSC822e from Mettler Toledo. Before sealing, a hole was pierced in the pan cover using a 50 µm diameter needle. An empty pan was used as a reference. The normalized heat flux was recorded and plotted as a function of temperature.

[0207] The initial melting temperature of the sample is defined as the first inflection point in the DSC curve, which shows that the heat flux rate to the sample increases with increasing temperature. As the sample begins to melt, the heat flux to the sample increases, resulting in a gradient change and the inflection point shown in the graph.

[0208] Normalized heat flow plots can be visually assessed by the operator to determine inflection points. However, this analysis is now typically performed using software analysis tools. Such tools are usually included as part of the equipment's operating system. Suitable software includes STARe evaluation software supplied by Mettler-Toledo.

[0209] The data from the normalized DSC plots obtained above were analyzed using STARe evaluation software version 16.30 to determine the initial melting temperature. The results are shown in Table 1 below. The thermal properties of starch mixtures are a complex combination of the relative ratio of amylose to amylopectin in the starch, prior heat treatment, and the levels and properties of other components. Table 1 (iii) Determination of sealing strength Test samples of some layers produced in step (i) were prepared and their seal strength was measured. Test samples with a width of 25 mm 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 (also known as a “folded joint”) in which the two inner surfaces of the membrane are sealed together. An lap seal (also known as an “overlap joint”) is in which the outer surface of the membrane is sealed to the inner surface of the membrane. The test samples of the seal were tested using Technique A (unsupported) in a Tinius Olsen 5ST 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. Table 2 As shown above, the initial melting temperature of a material is inversely proportional to its ability to form a strong seal. For example, STT-based layers have a lower initial melting temperature and form a strong seal. BPS-based layers have a higher initial melting temperature and form a good seal, but it is not as strong as the seal formed by STT-based layers.

[0210] For several reasons, a lower initial melting temperature is advantageous for the plant-derived polysaccharide / fungus-derived polysaccharide / agar layer of the bilayer membrane of this invention. Not only has it been shown that stronger seal strength can be achieved, but a lower initial melting temperature also means that a lower temperature needs to be applied to the outer layer of the bilayer membrane containing red algae-derived polysaccharides in order to achieve an effective seal to the inner layer containing plant-derived polysaccharides / fungus-derived polysaccharides / agar. This means avoiding membrane degradation (e.g., due to combustion) and requiring a shorter residence time to form a seal, making the sealing process more industrially feasible.

[0211] Example 4: Preparation of carrageenan-starch bilayer film (i) Preparation of carrageenan mixture 1. Preparation of oil-in-water emulsion: Weigh 3.25 g of oleic acid and 1.60 g of polysorbate into 80-50 mL Falcon tubes and mix them with 20 mL of water. Sonicate the mixture for 5 minutes using a Bandelin Sonoplus ultrasonic instrument (TS113 probe) at 50% amplitude, with an on-time of 1 second and an off-time of 0.2 seconds.

[0212] 2. While the emulsion is cooling, weigh 996.2g of reverse osmosis (RO) water, 6.67g of glycerin, and 6.67g of sorbitol into a 2L plastic beaker. Mix thoroughly with a spatula.

[0213] 3. Add 4.73g of cooled emulsion to the plasticizer-water mixture.

[0214] 4. Transfer the mixture to a Karlestein GrandPrix food processor and add 20g of κ-carrageenan.

[0215] 5. Mix at 30°C at speed 7 for 30 minutes.

[0216] (ii) Film formation – carrageenan layer 6. Transfer the mixed formulation to a high-speed mixing vessel and degas at 1950 rpm and 3 mbar for 5 minutes.

[0217] 7. Immediately after high-speed mixing, use an RK Print K303S multi-function coater at speed 2 with a doctor blade to cast the solution to a wet thickness of 1700 µm.

[0218] 8. Then dry the film in an oven at 80°C for 3 hours.

[0219] (iii) Preparation of starch mixtures 1. Weigh 500g RO water, 10.7g glycerin, and 10.7g sorbitol into a 1L plastic beaker. Mix thoroughly with a spatula.

[0220] 2. Transfer the solution to a Karlstein GrandPrix food processor and add 50g of tapioca starch.

[0221] 3. Mix at 85°C at speed 4 for 45 minutes.

[0222] (iv) Membrane formation - starch layer 4. Transfer the mixture to a high-speed mixing vessel and degas at 1950 rpm and 3 mbar for 5 minutes.

[0223] 5. Using a scraper, cast the solution onto the κ-carrageenan layer at a speed of 2 to a wet thickness of 300 µm.

[0224] 6. Then dry the membrane in an oven at 80°C for 30 minutes.

[0225] A double-layer film is obtained by peeling the dry film from the substrate.

[0226] Example 5 (Comparative Example): Preparation of Carrageenan / Starch Monolayer 1. Prepare carrageenan solution and starch solution as described in Examples 1 and 2, respectively.

[0227] 2. Mix 150 mL of starch solution and 850 mL of carrageenan solution together.

[0228] 3. Transfer the mixture of starch and carrageenan solution to a Karlstein GrandPrix food processor and mix at 30°C and speed 4 for 15 minutes.

[0229] 4. Immediately after high-speed mixing, use an RK Print K303S multi-function coater at speed 2 with a doctor blade to cast the solution to a wet thickness of 2000 µm.

[0230] 5. Dry the membrane in an oven at 80°C for 3 hours.

[0231] A single-layer film is obtained by peeling a dry film from a substrate.

[0232] Example 6: Measurement of membrane tensile strength and elongation The tensile strength and elongation of the membrane were measured according to ASTM D882. Rectangular test specimens, 80 mm long and 10 mm wide (falling within the specifications described in ASTM D882), were cut and conditioned overnight at 55% RH and 20°C. The test specimens were tested using a Tinius Olsen 5ST tensile testing machine with flat clamp inserts, an initial clamp spacing of 50 mm, and a testing speed of 50 mm / min (strain rate of 1 mm / mm•min).

[0233] Extreme care should be taken when cutting the specimen to prevent damage such as notches and tears that could lead to premature failure, and to ensure repeatable sample quality.

[0234] The results are shown in Table 3 below. Tensile strength is reported in MPa, and elongation at break is reported in %. Table 3 The carrageenan film of Example 1 exhibits very good tensile strength and elongation, making it suitable for packaging applications. However, the starch film of Example 2 has very low tensile strength and high elongation, making it too weak to be used. When the two materials are combined, the films obtained in Examples 4 and 5, whether as blends or as bilayer films, possess good tensile strength and elongation, making them suitable for packaging applications.

[0235] The results show that the bilayer membrane of the present invention has good mechanical properties and is not easily broken or cracked under elongation strain.

[0236] Example 7: Measurement of Sealing Strength Test samples with a width of 25 mm were cut to the dimensions specified in ASTM F88 / F88M-15 and conditioned overnight at 55% relative humidity and 20°C. The test strip samples were then sealed using an RDM heat sealer to obtain either a fin seal (also known as a “folded seam”) where the two inner surfaces of the membrane are sealed together, or an overlap seal (also known as a “knotted seam”) where the outer surface of the membrane is sealed to the inner surface of the membrane. The seals were tested using Technique A (unsupported) on a Tinius Olsen 5ST tensile tester. 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. Triple tests were performed for each example. For each example, the table below presents the average of the maximum heat-sealing force. The average of the three samples is reported as Newtons per meter (N / m) when the maximum force was encountered when all three samples of each example were stretched to failure. For the membrane of Example 4, two sealing types were tested: a fin seal (“starch-starch seal”) in which two starch surfaces are sealed together and an overlap seal (“starch-carrageenan seal”) in which a starch surface is sealed to a carrageenan surface. Table 4 The results showed that the carrageenan film of Example 1 was completely unsealed, while the starch film of Example 2 had high sealing strength. When the two materials were combined into a blend (as in Example 5), the resulting film lacked the characteristics of starch and had low sealing strength, making it unsuitable for forming closed packaging such as pouches. High sealing strength was achieved when the two materials formed a bilayer film (as in Example 4). As shown in Example 4, the highest sealing strength was achieved with a starch-starch seal. A lower but still very good sealing strength was achieved with a starch-carrageenan seal. The results indicate that the bilayer film of the present invention can have very good sealing strength.

[0237] The carrageenan / starch bilayer membrane of Example 4 (membrane thickness of 69 µm, conditioned and stored at 55% relative humidity and 20°C) was used for further sealing strength testing of the starch-starch fin seal at different sealing temperatures, 1-second residence times, and 3 bar pressures. The results are shown in Table 5 below. Table 5 The results show that there is an ideal temperature range for obtaining effective sealing strength for the bilayer membrane of the present invention. The sealing strength is too low at low temperatures, while it begins to decrease at very high temperatures.

[0238] Example 8: Measurement of water dispersibility The water dispersibility of the membranes in Examples 1, 2, 4, and 5 was evaluated using 0.75 g samples of each final membrane conditioned at 55% relative humidity and 20°C. The samples were mixed at 300 rpm for 3 minutes at room temperature using a top stirrer in 300 ml of 20°C reverse osmosis water and freshly boiled reverse osmosis water (i.e., at a temperature of 75°C to 90°C) in a 600 ml beaker.

[0239] Visually inspect the final mixture for any remaining particles and use their size to determine water dispersibility according to the following scale: Not dispersed - remains as a film; Very low - most particles >30 mm; Low - most particles approximately 20-30 mm; Medium - most particles approximately 10-20 mm; High - most particles approximately 1-10 mm; Very high - most particles <1 mm; Highest - no visible particles.

[0240] The results of all these tests are shown in Table 6 below. Table 6 The starch monolayer film of Example 2 is highly dispersible at room temperature and in freshly boiled water.

[0241] The films containing carrageenan do not disperse at room temperature, whether as a single layer in Example 1, a mixture in Example 5, or a double layer in Example 4.

[0242] In freshly boiled water, the carrageenan-only film of Example 1 was highly dispersible, resulting in no visible particles. Films containing starch were also highly dispersible in freshly boiled water, whether as a single layer in Example 2, a mixture in Example 5, or a double layer in Example 4.

[0243] This indicates that the membrane of the present invention can be used to prepare small bags that are insoluble at low water temperatures and maintain their integrity in the presence of water, but are highly soluble at higher water temperatures.

[0244] Example 9: Moisture content of the membrane The moisture content of the various membranes prepared in the above embodiments was measured using an Ohaus MB23 moisture analyzer, wherein the membrane samples were pre-conditioned at 55% relative humidity and 20°C. The results are shown in Table 7 below. Table 7 Example 10: Dispersion of laundry detergent sachets The pouches are prepared using the double-layered film of Example 4, by heat-sealing along the length and ends of the film into a starch-starch fin seal using an RS PRO heat sealer at power 2. The sealed pouches contain a concentrated liquid laundry detergent derived from Tesco non-biological liquid laundry beads, such as... Figure 1a As shown.

[0245] The sachets are easy to handle and maintain their integrity. When added to 250 ml of water at 40°C, 50°C, or 60°C in a 400 ml beaker and stirred with a magnetic stirrer at approximately 340 rpm, the sachets disintegrate and completely release their contents in 5 minutes or less. The higher the temperature, the faster the release, and at 60°C, the release occurs within approximately 1 to 2 minutes. Figure 1b-1f As shown.

[0246] This embodiment demonstrates one of the many uses of the bilayer film of the present invention: the preparation of heat-sealed pouches to provide a single dose of liquid detergent for laundry. The pouches are safe for consumers to handle and release detergent upon contact with warm water in a washing machine.

Claims

1. A membrane comprising: The first layer, based on its total weight, comprises: At least 20% by weight of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum, and mixtures thereof, and At least 5% by weight of one or more organic plasticizers; and The second layer, based on its total weight, comprises: The material is selected from at least one of plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch, and the fungal-derived polysaccharide is pullulan; and At least 5% by weight of one or more organic plasticizers.

2. The membrane of claim 1, wherein the thickness of the membrane is from 20 µm to 120 µm, preferably from 30 µm to 100 µm.

3. The membrane of claim 1, wherein the at least one red algae-derived polysaccharide in the first layer is carrageenan, preferably 1-carrageenan, κ-carrageenan or λ-carrageenan, more preferably κ-carrageenan.

4. The membrane according to any one of claims 1 to 3, wherein, as determined by the method described in Glueck et al., 1980, Zeitschrift für Lebensmittel-Untersuchung und -Forschung, 170, 272-279, the membrane comprises 3-90% by weight, preferably 15-85% by weight, more preferably 25-80% by weight, and most preferably 35-70% by weight of a red algae-derived polysaccharide selected from carrageenan, red algae gum, and mixtures thereof, based on the total weight of the membrane.

5. The membrane according to any one of claims 1 to 4, wherein after the membrane has been conditioned at 55% relative humidity and 20°C for at least one hour, and then sealed as a fin seal or lap seal by applying a pressure of 1 to 3 bar at a temperature of 140°C for 1 second, the membrane 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, as measured by ASTM F88 / F88M-15 at 55% relative humidity and 20°C.

6. The membrane according to any one of claims 1 to 5, wherein the organic plasticizer in the first layer is selected from glycerol, diglycerol, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethylpropane, polyether polyol, 2-methyl-1,3-propanediol, ethanolamine, polyethylene glycol, propylene glycol, sorbitol, mannitol, xylitol, triethyl citrate, oleic acid, monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, wax, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, gluconic acid, and mixtures thereof, preferably a mixture of glycerol, sorbitol, and oleic acid.

7. The membrane according to any one of claims 1 to 6, wherein the organic plasticizer in the second layer is selected from glycerol, diglycerol, polyethylene glycol, propylene glycol, dipropylene glycol, tetraethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethylpropane, polyether polyol, 2-methyl-1,3-propanediol, ethanolamine, sorbitol, mannitol, xylitol, triethyl citrate, oleic acid, monoglycerides, diglycerides, triglycerides, glucose, mannose, fructose, sucrose, urea, lecithin, wax, amino acids, lactic acid, citric acid, glycolic acid, malic acid, tartaric acid, gluconic acid, and mixtures thereof, preferably a mixture of glycerol and sorbitol.

8. The membrane according to any one of claims 1 to 7, wherein, according to ISO 14851 (2019), after a 28-day test, the membrane is biodegradable in fresh water by more than 75%, preferably more than 80%, more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95%.

9. The membrane according to any one of claims 1 to 8, wherein, according to ASTM D6691, after a 28-day test, the membrane is biodegradable in seawater by more than 75%, preferably more than 80%, more preferably more than 85%, even more preferably more than 90%, and most preferably more than 95%.

10. A method for preparing a membrane as described in any one of claims 1 to 9, comprising the following steps: (i) Provide a first layer, which, based on the total weight of the first layer, comprises: At least 20% by weight of at least one red algae-derived polysaccharide selected from carrageenan, red algae gum, and mixtures thereof, and At least 5% by weight of one or more organic plasticizers; (ii) Provide a second layer, which, based on the total weight of the second layer, comprises: The material is selected from at least one of plant-derived polysaccharides, fungal-derived polysaccharides, and agar, wherein the plant-derived polysaccharide is starch, and the fungal-derived polysaccharide is pullulan; and At least 5% by weight of one or more organic plasticizers; and (iii) The first layer and the second layer are formed into the membrane.

11. A membrane that can be obtained by or through the method of claim 10.

12. A product encapsulated by any one of claims 1 to 9 and 11.

13. A method for packaging a product, comprising the following steps: (i) Encasing the product in a film as described in any one of claims 1 to 9 and 11; and (ii) Heat seal the film surrounding the product to form a pouch.

14. The method of 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 performed at a temperature below 160°C, preferably below 140°C, more preferably below 120°C.

15. A pouch prepared by the method of claim 13 or claim 14.

16. Use of the film as described in any one of claims 1 to 9 and 11 for packaging products and / or preparing pouches.

17. A method for releasing a product encapsulated in a film as described in any one of claims 1 to 9 and 11, comprising the steps of: (i) Place the packaged product in water at a temperature of at least 40°C; and (ii) Disperse the membrane to release the product.

18. The method of claim 17, wherein in step (i), the packaged product is placed in water at a temperature of at least 50°C, more preferably in water at a temperature of at least 60°C.

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