WO2023131974A1

WO2023131974A1 - A home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film and process for preparing the same

Info

Publication number: WO2023131974A1
Application number: PCT/IN2023/050012
Authority: WO
Inventors: Neha Jain; Satej Dharmapurikar
Original assignee: Zerocircle Alternatives Pvt. Ltd.
Priority date: 2022-01-06
Filing date: 2023-01-05
Publication date: 2023-07-13

Abstract

The present invention provides a home-compostable, 100% natural, nontoxic, hydrophobic seaweed polysaccharide based film and process for preparing the same. The said seaweed polysaccharide based film has properties namely: (i) tensile strength 2 MPa to 30 MPa; (ii) elongation at break 20 to 150%; (iii) contact angle 15 to 100 degree; (iv) water vapours transmission rate 50- 1200 gm/m2/day; (v) oxygen transmission rate 0.1 to 50 gm/cc/day; (vi) seal strength 1 to 10 N/mm; (vii) transmittance 20 to 100%; (viii) home compostability 30 days to 180 days. The said seaweed polysaccharide based film has wide applications including but not limited to in the food industry, pharmaceutical industry and paper industry.

Description

A home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film and process for preparing the same

RELATED APPLICATION

[0001] This application bears priority from the provisional application No. 202211000772 with the title ‘A home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film and process for preparing the same’.

FIELD OF INVENTION

[0002] The present invention relates to a home-compostable, 100% natural, nontoxic, hydrophobic seaweed polysaccharide based film and a process for preparing the same.

BACKGROUND OF INVENTION

[0003] In recent decades, this environmental issue has drawn considerable attention from governments, industry and researchers in order to find sustainable, biodegradable alternatives to synthetic plastics. This is particularly the case in packaging applications that represent the largest proportion of the overall plastic usage. Approximately one third of plastics manufactured worldwide are transformed into packaging materials, with the majority converted into single-use applications such as flexible and rigid food packaging, plastic bags and film, among numerous others (Siracusa et al., 2008, “Biodegradable polymers for food packaging: a review”, Trends in Food Science & Technology 19 (12) (2008) 634- 643).

[0004] Extensive research has been conducted to produce bio-plastics from many different sources including animals, plants, and microbes. Some are now commercially available in the global market such as poly(lactic acid) (PLA), poly(hydroxyalkanoates) (PHAs) and starch-based polymers etc. Even though these materials can be produced from many renewable sources, there are still challenges to be addressed due to their limited biomass-availability and also their cultivation or synthesis. [0005] Seaweed is one such material that can offer a source of raw materials from which packaging materials can be produced. Compared with terrestrial plant sources, seaweed offers some considerable advantages including its low cost and abundance in nature. The seaweeds are purported to lessen impacts on the food chain and are generally safe from exposure to chemicals or fertilizers.

[0006] Several polysaccharides, for example carrageenan, alginate, agar, ulvan etc., extracted from seaweeds demonstrate excellent film-forming ability.

[0007] For instance, Carrageenan, obtained from red seaweeds of the class Rhodophyceae, is a sulfated polygalactan with 15-40% ester sulfate content and with an average molecular weight above 100 kDa. Its polymer chains are formed by alternate units of D-galactose and 3, 6-anhydrogalactose joined by a-1,3- and [3- 1,4-glycosidic linkages. Different research work studies have reported the transformation of carrageenan into packaging films for a range of different applications.

[0008] However, these polymer films still exhibit limitations with particular regard to their water vapour permeability (WVP) and water resistance since they are naturally hydrophilic as well as brittle. As a result of these, such inherent weaknesses may limit the widespread applications of these materials.

[0009] Generally, polysaccharides are polar in nature. Hence, the films made of polysaccharides are hydrophilic. The hydrophilicity of seaweed polysaccharides (SWP) is due to polar functionality such as -OH, -SO3-, -COO-etc. The film of seaweed polysaccharides (SWP) is hydrophilic which has very limited applications. In the past, starch polysaccharides are modified using acetylation, alkylation reactions to improve the hydrophobicity. The hydrophobicity can be introduced by shielding the polar group with non-polar moieties.

[0010] Thus the concern is to increase the hydrophobicity of the SWPs to allow their use as sturdy and durable films, while balancing their water solubility, thereby maximising the yield for eco-friendliness in terms of bio-degradability and homecompostability. [0011] Extensive prior art exists that describes the preparation of such films and their properties. For instance, US7067568 discloses a process of preparation of biodegradable films from semi refined kappa carrageenan, wherein the process involves: (i) heating semi-refined carrageenan in water to obtain a crude sol, (ii) centrifuging under hot condition to remove debris and obtain purified semi refined carrageenan as the main film forming material in the form of a clear sol, (iii) boiling to concentrate the sol in an open pan evaporator, (iv) adding glycerol into the formulation as a plasticiser, (v) adding polyvinyl alcohol in solution form into the formulation to increase transparency and toughness, (vi) adding natural rubber latex as a dilute solution into the formulation to improve elasticity and barrier properties; (vii) casting film from hot sol on a conventional casting machine or on a rotating drum, (viii) utilizing the film for diverse applications including preparation of soft capsule, pouches and overhead transparency sheets, (ix) recycling rejected films by converting back into sol. The said invention uses petroleum based products (vinyl acetate) for grafting and therefore is not completely bio-based which will definitely affect its degradability but it takes more time.

[0012] W02014057502 describes biodegradable hydrophobic composite materials and process for the preparation thereof, wherein hydrophobic biodegradable composites comprises: (a) seaweed derived polysaccharides in the range of 30 to 80 wt%; (b) vinylated monomer in the range of 8 to 60 wt %; and (c) plasticizer in the range of 2 to 15 wt%; wherein, the moisture content of said composites is in the range of 5 to 15 wt%.

[0013] Similarly, JP2000-093080 discloses use of polysaccharides like polyvinyl alcohol, polyvinyl pyrrolidone, sodium alginate, etc. in preparation of antibacterial and antifungal agent composition, which is soluble when used.

[0014] US6294202B1 discloses a process for making water-insoluble biodegradable composition containing polyanionic polysaccharides and hydrophobic bio-absorbable polymers to prepare film, foam, mesh matte, or to cast on top of any surface. It is pertinent to mention here that the said reference reports the formation of compositions containing polyanionic polysaccharides and hydrophobic bio-absorbable polymers or copolymers.

[0015] The drawback of the cited prior arts is in the use of petroleum based vinylated polymer and other synthetic polymers that affect the degradability of the end-product. The vinylated monomers in the above cited prior arts impacts hydrophobicity. However, the use of these very polymers also affect the homecompostability and biodegradability of the end product. There is also a glaring lacuna in terms of “non-toxicity” as well as “food safety” of the films thus produced.

[0016] Whereas increased hydrophobicity by use of synthetic and petroleum based polymers and monomers results in increased durability (shelf life) and viability of the end-products, it compromises on their eco-friendliness. On the other hand more focus on home-compostable and environment friendly films usually results in poor stability and easy disintegration on contact with water. Poor physical strength and integrity due to lack of sufficient hydrophobicity (which is attributed to the synthetic and petroleum based polymers in the above cited prior arts) leads to easy degradation and disintegration.

[0017] Further the process employed in the present invention has made optimisations to use 25 to 60% of the biomass in terms of polysaccharide thereby ensuring maximum process yield. The processing also involves use of semi refined polysaccharides. Both these parameters brings down the costing and makes the process economical.

[0018] Therefore, to overcome the shortcomings highlighted in the prior art, there is a need to develop specific seaweed polysaccharide-based films. More specifically, the need is to develop films with improved hydrophobicity along with better physico-mechanical properties while maximising on the yield for eco- friendliness.

[0019] Both the novelty and inventiveness of the recited film are thus attributed to its complete amenability to home-composting, while maintaining the required degree of water resistance (i.e. hydrophobicity) enabling its use as an eco-friendly packaging and laminating material. The application of the film can be extended to food industry as a cling wrap, sturdy food packaging material, dissolvable tea and coffee bags. The increased tensile strength of the film allows its application in making eco-friendly polybags that are sturdy and can carry weight and can also stand erect like paper bags.

[0020] The novelty of the present invention is in maximising the eco-friendliness of the product, i.e. the seaweed polysaccharide based film. The process employed in the present invention uses 100% natural substrates. The product is home- compostable as per the TUV definitions (https://www.tuv-at.be/green-marks/) and results in 100% bio-waste that is non-toxic.

[0021] Further the present invention is unique as it brings together different desirable characteristics in a single film, which has not been seen in any of the prior arts. A marked improvement is visible in the mechanical (tensile strength and elasticity), physical (porosity, and oxygen barrier) and chemical (hydrophobicity, heat saleability, temperature sensitivity, water resistance and anti-microbial) characteristics of the film.

[0022] Whereas plain starch polysaccharides or even plain seaweed polysaccharide films have issues on saleability (Das and Chowdhury “Heat sealing property of starch based self-supporting edible films” Food Packaging and Shelf Life Volume 9, September 2016, Pages 64-68), this problem has been overcome in the present invention, where an increased heat sealability of the film has been reported.

[0023] The present invention provides a solution to the problems of the prior art namely use of petroleum based polymers such as vinylated monomer (e.g. vinyl acetate) which takes more time for degradation and that adversely impacts the environment. The present invention provides a home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film with increased shelf life. The polymeric film takes less time for degradation, is home compostable, eco- friendly and non-toxic. Further, the film of the present invention has improved physico-mechanical and chemical properties and increased durability. The film of the present invention when used for packaging of perishable products (e.g. food items and fruits or any other materials that are degradable due to high oxygen transmission) have shown to increase their shelf life.

OBJECTS OF INVENTION

[0024] One object of the present invention is to provide a home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film.

[0025] Another object of the present invention is to provide a process for preparing a home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film.

[0026] Another object of the present invention is to provide a process for isolation of polysaccharide from seaweeds.

[0027] Yet another object of the present invention is to provide a home- compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film that can be used for preparing laminates.

[0028] Yet another object of the present invention is to provide a home- compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film that has wide application in food, pharmaceutical, paper and other industries.

SUMMARY OF INVENTION

[0029] One of the aspects of the present invention is to provide home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film, wherein the film comprises: i. 2 to 7% (w/w) seaweed polysaccharides; ii. a plasticizer in the ratio of 0.2 to 1 of seaweed polysaccharide; iii. 0.05 to 0.5% (w/w) of an anti-fungal agent; iv. 500 ppm to 10000 ppm of essential oil; v. wax in the range of 5 to 20% of the seaweed polysaccharide vi. 1 to 30% (w/w) of at least one polysaccharide and/or filler; and vii. an emulsifier in the ratio of 0.1 to 0.5 of seaweed polysaccharide; [0030] Another aspect of the present invention is to provide a process for preparing the home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film, wherein the process comprises: a) processing and isolating seaweed polysaccharides; b) heating seaweed polysaccharides from step (a) and water at a temperature in the range of 80 to 120°C for time period in the range of 30 min to 45 min to obtain a solution; c) adding a mixture comprising a plasticizer, an antifungal agent, an essential oil, wax, at least one polysaccharide and/or filler and an emulsifier to the solution obtained from step (b) at the temperature in the range of 80 to 120°C and stirring the solution for the time period in the range of 30 to 45 min; d) spreading the resultant solution on a base substrate and drying the solution to obtain hydrophobic polysaccharide film composition.

[0031] Yet another aspect of the present invention is to provide home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film, wherein the film has tensile strength 2 MPa to 30 MPa; elongation at break 20 to 150%; contact angle 15 to 100 degree; water vapour transmission rate 50 to 1200 gm/m²/day; oxygen transmission rate 0.1 to 50 gm/cc/day; seal strength 1 to 10 N/mm and wherein the shelf life of the film and products made thereof is at least 2 years under ambient conditions.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS AND FIGURES

[0032] Figure 1 illustrates ripening and shelf life studies of banana fruit using in seaweed film (SWF) of the invention and polypropylene (PP) film. Figure la shows fruits are kept in PP glasses that are covered with lids made of SWF and PP respectively and figure 1 b shows fruits entirely covered with sheets made of SWF and PP.

[0033] Figure 2a and 2b illustrate the difference in water and oil resistance properties of base paper and base paper laminated with SWF of the present invention. 1, 2 and 3 are water, oil and ketch up spots on the sheets. [0034] Figure 3 shows difference in decomposition of the PP sheet SWF sheet of the present invention over a period of 30 days.

[0035] Figure 4 shows water droplets on hydrophilic seaweed film (a) and water droplet on hydrophobic seaweed film (b) of the present invention. Inset is the contact angle of the water droplets.

DETAILED DESCRIPTION OF THE INVENTION

[0036] The present disclosure is subject to variations and modifications other than those specifically described. Those skilled in the art would understand that the present disclosure includes all such variations and modifications, including different steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features. The present application describes certain materials and methods to exemplify the invention, however, any methods and materials similar or equivalent variations of those described herein can be used in the practice or testing of the disclosure.

[0037] Further, unless defined otherwise, all technical and scientific terms used herein have the same connotation as commonly understood by a person having ordinary skill in the art.

[0038] Where the term "comprising" is used in the present description, it does not exclude other elements or steps.

[0039] Where an indefinite or definite article is used when referring to a singular noun e.g. "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated.

[0040] In the specification, certain terms are used to describe the invention. Definitions of terms are as follows.

[0041] The term “composition” used herein refers to number of the chemical elements in a specific ratio that make up a particular product. The terms composition and film composition” are used interchangeably in the specification. [0042] The terms “bio-based film” or “film” or “seaweed film” (SWF) are used interchangeably in the specification and refer to the home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based “film” of the present invention.

[0043] The term “shelflife” used in the specification refers to the length of time for which the film can be stored in ambient conditions and remains fit for use and/or consumption. The term “shelflife” is also applied in the specification for perishable items; paper and paper products, food and pharma items for which the film is used either as a laminate/ covering or for material and products (such as tea and coffee bags, food containers etc.) made directly from the film of the present invention.

[0044] The term “Home compostable products” used herein refers to the product that are degradable in the conditions of a well-managed home composter at lower temperatures than in industrial composting plants. Most of them also biodegrade in industrial composting plants.

[0045] The term “Biodegradable products” used herein refers to the products (film or bio-plastics etc.) that are degradable in a specific medium (water, soil, compost) under certain conditions and in varying periods of time.

[0046] The term “Industrially compostable products” used herein refers to the product which are designed to biodegrade in the conditions of an industrial composting plant or an industrial anaerobic digestion plant with a subsequent composting step.

[0047] The term “Natural” used herein refers to the use of biological raw materials for making the film as opposed to the fossil raw material (oil) used in conventional plastic products. The word natural in the present context can be interchangeably used with the words “organic” and “bio-based”.

[0048] Non-Toxic: The term as used herein means the product or the components comprising the product are not poisonous. The product or the components comprising the product are safe to eat or breathe nontoxic substances, and importantly they do not harm the environment. [0049] Food safe: The term food safe as used in the present specification means “Food grade”. The term food safe implies that the product is suitable for contact with consumable food or drink products.

[0050] Laminate: As referred and used in the present specification the word laminate relates to adding a layer or two of the films of the present invention over a product that could belong to food, pharma, paper or other industries in order to provide it increased shelf life, durability, clarity, strength, insulation and better appearance.

[0051] The term “hydrophobic” used herein refers to a property of a substance that repels water. It means lacking affinity for water, and tending to repel or not to absorb water.

[0052] The term “seaweed polysaccharides” used herein refers to polysaccharides derived from seaweed. For example alginate and fucoidan from brown algae, agar and carrageenan from red algae, and ulvan from green algae.

[0053] The term “natural wax” refer to organic compounds with long aliphatic alkyl chains with many functional groups such as fatty acids, primary and secondary alcohols, ketones, aldehydes and fatty acid esters. The waxes can be grouped under lipids, which are a broader group. For the purpose of this invention, the term wax, natural wax and lipid has been interchangeably used.

[0054] The term “mixture” used herein refers to a substance made from a combination of different substances.

[0055] The term “solution” used herein refers to a homogenous mixture of two or more substances in relative amounts that dissolved in a solvent.

[0056] The term “base substrate” used herein refers to a substrate which acts as a support medium. In the present invention base substrate is used for applying said composition to make a film. For example glass surface or acrylic.

[0057] One of the embodiments of the present invention provides a home- compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film comprising: i. 2 to 7%(w/w) seaweed polysaccharides; ii. a plasticizer in the ratio of 0.2 to 1 of seaweed polysaccharide; iii. 0.05 to 0.5%(w/w) of an anti-fungal agent; iv. 500 ppm to 10000 ppm of essential oil; v. wax in the range of 5 to 20% of the seaweed polysaccharide vi. 5 to 30% (w/w) at least one polysaccharide and/or filler; and vii. an emulsifier in the ratio of 0.1 to 0.5 of seaweed polysaccharide;

[0058] Another embodiment of the present invention provides a process for preparing a home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film, the process comprising: a) processing and isolating seaweed polysaccharides from seaweeds; b) heating seaweed polysaccharides obtained from step (a) and water at a temperature in the range of 80 to 120oC for time period in the range of 30 min to 45 min to obtain a solution; c) adding a mixture comprising plasticizer, antifungal agent, essential oil, wax, at least one polysaccharide and/or filler, and emulsifier to the solution obtained from step (b) at the temperature in the range of 80 to 120oC and stirring the solution for the time period in the range of 30 to 45 min; and d) spreading the resultant solution on a base substrate and drying to obtain hydrophobic polysaccharide film.

[0059] Yet another embodiment of the present invention provides a home- compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film, wherein the film has tensile strength 2 MPa to 30 MPa; elongation at break 20 to 150%; contact angle 15 to 100 degree (Figure 4); water vapour transmission rate 50 to 1200 gm/m2/day; oxygen transmission rate 0.1 to 50 gm/cc/day; seal strength 1 to 10 N/mm; and wherein the shelf life of the film and products made thereof is at least 2 years under ambient conditions.

[0060] Another embodiment of the present invention provides a seaweed polysaccharide based film, wherein seaweed polysaccharides is selected from but not limited to pure refined carrageenan, semi -refined carrageenan, alginate, fucoidan, agar, ulvan and combinations thereof.

[0061] Yet another embodiment provides a seaweed polysaccharide based film, wherein the pure or semi-refined carrageenan is selected from different classes, namely kappa, iota or lambda and combinations thereof.

[0062] Another embodiment of the present invention provides a seaweed polysaccharide based film, wherein seaweed polysaccharides are either used alone or in combinations thereof.

[0063] Another embodiment of the present invention provides a seaweed polysaccharide based film, wherein the plasticizer may include but not limited to polyols, sorbitol, glycerol and combinations thereof.

[0064] Yet another embodiment of the present invention a seaweed polysaccharide based film, wherein at least one polysaccharide and/or filler includes but is not limited to methyl cellulose, microcrystalline cellulose, nano crystalline cellulose, HEMP fibre, banana fibre, tapioca starch, com starch, protein extract, organic clay etc., wherein incorporation of polysaccharide and/or filler improved the mechanical strength of the film particularly tensile strength. Hence mechanical strength can be tuned based on the filler and its concentration. Proteins and protein extracts form a network with base polysaccharide through hydrogen bonding which improves the mechanical strength of the film and also improves the moisture barrier properties.

[0065] An embodiment of the invention provides a seaweed polysaccharide based film, wherein the wax is natural wax that may include but is not limited to beeswax, soya wax, carnauba wax, candelilla wax and combinations thereof. Wax is hydrophobic in nature which helps to improve the hydrophobicity of film and reduces the moisture vapour transmittance rate.

[0066] An embodiment of the invention provides a home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film, wherein the organic clay may include but is not limited to well - Kaolin, red clay, rose clay and green clay and combinations thereof. [0067] Another embodiment of the present invention provides a seaweed polysaccharide based film, wherein antifungal agent may include but not limited to sodium benzoate, potassium sorbate and combinations thereof. These are being added into the film at 80 to 120oC temperature. The addition of sodium benzoate, potassium sorbate etc. into the film improves the antifungal properties of the film, subsequently increases the shelf life of the film. It has been observed that seaweed based films are durable for maximum 4 weeks only at ambient temperature conditions and humidity of over 50%. However, the film disclosed in the present invention has been observed to retain its durability very easily for more than one month. The shelf life of the film and the products made thereof is more than 2 years.

[0068] In fact under climatic extremes of tropical conditions the film easily resists any fungal attacks for over a month’s time.

[0069] Yet another embodiment of the present invention provides a seaweed polysaccharide based film, wherein an increased shelflife of perishable items (fruits and food products or any other materials that are degraded due to high oxygen transmission) when packaged and/or laminated with the film of the present invention is at least 1 week. The 100% bio-based composition of the film allows breathability, thereby avoiding trapping of ethylene, 02 and water vapour (no water vapour haze) and maintaining optimal water vapour, moisture, and gas transmittance rates.

[0070] In yet another exemplary embodiment of the present invention there is provided a seaweed polysaccharide based film, wherein a delay is observed in ripening of the fruits laminated or packaged with the film of the present invention. This delay is in the range of 2 days to 2 weeks depending on the fruit and the prevailing ambient conditions of temperature and humidity.

[0071] Yet another embodiment of the present invention provides a seaweed polysaccharide based film, wherein the thickness of the film is in the range of 2 to 250 microns. [0072] Another embodiment of the present invention provides a seaweed polysaccharide based film, wherein essential oil may include but not limited to lemon grass oil, neem oil, eucalyptus oil, clove oil, cinnamon oil, tree tea oil, turmeric and combinations thereof; wherein the addition of essential oils into the film improves the antifungal and antimicrobial properties of the film, and also helps to improve the hydrophobicity to some extent.

[0073] Another embodiment of the present invention the seaweed polysaccharide based film, wherein emulsifier may be selected from but not limited to Span 80, Span 60, Span 20, Tween 80, Tween 20 and combinations thereof; wherein emulsifier is used to shield the polar groups, as a result of this the hydrophobicity of overall system is improved.

[0074] Despite the improved hydrophobicity the films remains high on gas barrier component and heat saleability, wherein heat saleability is improved by application of high boiling polar solvent such as water, ethylene glycol etc.

[0075] In another exemplary embodiment of the present invention there is provided a process for preparing the seaweed polysaccharide based film, wherein the substrates or components used for making the film are of 100% natural origin.

[0076] In another exemplary embodiment of the present invention there is provided a process for preparing the seaweed polysaccharide based film, wherein the substrates or components used for making the film are non-toxic.

[0077] In another exemplary embodiment of the present invention there is provided a process for preparing the seaweed polysaccharide based film, wherein the substrates or components used for making the film are food safe.

[0078] In another embodiment of the present invention there is provided a process for preparing the seaweed polysaccharide based film, wherein the processing and isolating of the seaweed polysaccharides involves the removal of impurities, separation of the seaweed polysaccharide from the aqueous extraction medium, shear stress treatments including treatment with alkaline solutions followed by drying. [0079] In another embodiment of the present invention there is provided a process for preparing the seaweed polysaccharide based film, wherein polysaccharide, raw material, can be obtained from seaweed species including but not limited to Acetabularia, Batrachospermum, Callophyllis, Ceratium, Chlamydomonas, Chlorella, Chondrus, Cladophora, Codium, Eucheuma, Euglena, Furcellaria, Fucus, Gonyaulax, Gymnodinium, Grassilaria, Hydrodictyon, Hypnea, Halymenia, Iridaea, Kappahycus, Laminaria, Mastocarpus, Macrocystis, Nitophyllum, Noctiluca, Oedogonium, Pediastrum, Pelagophycus, Peridinium, Pleurococcus, Porphyra, Sargassum, Scenedesmus, Spirogyra, Solieria, Ulothrix, Ulva, Vaucheria, Volvox and combinations thereof.

[0080] In another embodiment of present invention there is provided a process for preparing the seaweed polysaccharide based film, wherein the seaweed material may be subjected to the shear stress treatment comprises at least one added base selected from the group consisting of an alkali metal hydroxide, an alkali metal carbonate, an alkaline earth metal hydroxide, an alkaline earth metal carbonate, an alkali metal alcoholate and a basic inorganic phosphate.

[0081] Another embodiment of the present invention there is provided a process for preparing the said seaweed polysaccharide based film, wherein SWF shows improved hydrophobicity without compromising the home-compostability.

[0082] The origin and quantity of various components employed for making the films/bio-plastics has a direct impact on both the durability, hydrophobicity as well its home-compostability. In the present invention, durability and hydrophobicity of the recited film are finely balanced against its home-compostability by diligent and innovative research and optimisations carried out. All the elements are 100% biobased (i.e. of natural origin). It has been established that even minimal use of synthetic, petroleum based polymers/monomers can increase the time required for degradation of the products thereby adversely impacting the environment.

[0083] Another embodiment of the present invention provides a process for preparing the seaweed polysaccharide based film, wherein the home compostability or biodegradability of the film vanes with real-life conditions such as temperature, humidity, salinity and pH conditions.

[0084] According to another embodiment of the present specification the said seaweed film is completely biodegraded and/or disintegrated within a period of 30 to 180 days depending on the real-life conditions namely temperature, humidity, salinity and pH of a home bio-composter.

[0085] In yet another embodiment of the present specification the film composition of the invention is produced as sheets; cling wraps; coating and/or laminates onto other goods that include but are not limited to perishable items, food and pharma products, paper and traditional plastics like polyethylene (PE) polypropylene (PP), and low density polyethylene (LDPE); tubular rolls; food containers/boxes; carry bags; and dissolvable tea & coffee bags.

[0086] Another embodiment of the specification provides the hydrophobic seaweed polysaccharide, wherein the thickness of the sheets, cling wraps and laminates of the SWF is in the range of 2 microns to 250 microns.

[0087] According to an embodiment of the present invention the said film composition coating and / or laminates onto other goods increases the shelf life of the said goods which are prone to oxygen induced degradation by days and / weeks depending on their default barrier of the without the coating.

[0088] According to yet another embodiment the said seaweed film coating and/or laminates onto other materials increases the shelf life of the perishable items and other materials by at least 1 week.

[0089] In yet another exemplary embodiment of the present invention there is provided a process for preparing the seaweed polysaccharide based film, wherein the process has optimised the use of biomass in the range of 25 to 60% in terms of polysaccharide thereby ensuring maximum process yield. The process also involves use of semi refined polysaccharides. Both these parameters brings down the costing and makes the process economical and industrially viable. [0090] Another embodiment of the present invention there is provided a process for preparation of seaweed polysaccharide based film, wherein the said film has following properties:

• Tensile strength 2 MPa to 30 MPa

• Elongation at break 20 to 150%

• Contact angle 15 to 100 degree

• Water vapours transmission rate 50- 1200 gm/m2/day

• Oxygen transmission rate 0.1 to 50 gm/cc/day

• Seal strength 1 to 10 N/mm

• Transmittance 20 to 100%

• Home compostability 30 days to 180 days

• The SWF and products made thereof have shelflife of at least two (2) years [0091] Advantages of the present invention over the prior art:

1. Said film composition is home-compostable, 100% organic and bio-based

2. It is non-toxic and eco-friendly

3. It is “food safe” and can be used both in food or pharma industry

4. It enhances shelf life of perishable products (fruits ad food items).

5. It has tensile strength 2 MPa to 30 MPa; elongation at break 20 to 150%; contact angle 15 to 100 degree; water vapour transmission rate 50 to 1200gm/m2/day; oxygen transmission rate 0.1 to 50 gm/cc/day; seal strength 1 to 10 N/mm.

6. It can be used as a laminate on paper and still maintain 100% compostability yet improve the drawbacks of paper. Not possible with PE or synthetic polymer laminates or coating.

7. The lamination/coverings of the SWF can be used for perishable items such as those belonging to food and pharma industry or any other objects that can degrade due to high oxygen transmission, and these objects include but are not limited to the traditional plastics such as polyethylene, polypropylene and low density polyethylene. [0092] The mechanical parameters such as tensile strength and elongation at break were measured using ASTM D 882 standard. Contact angle gives an estimate of hydrophobicity of the membrane and was measured by using ASTM D5946 method. The water vapour emission rates and oxygen transmission rates were measured by ASTM E 96 and D 3985 respectively. The seal strength was measured using ASTM F 88 standard. The home compostability of these film was analysed using AS 5810 methods

[0093] The seaweed polysaccharides used for the present invention were extracted in the lab at Zerocircle, Pune. However, the algal biomass for red, green and brown algae was procured from the farmers involved in seaweed cultivation. The Kappaphyycus, Ulva and Gracilariia were procured from Kutch, Gujarat. The Kappaphyycus biomass was also supplied by farmers of Tuticorin, Tamilnadu. Sargassam biomass on the other hand was procured from the seaweed farmers from Okha, Gujarat.

[0094] Waxes namely beeswax, candelilla wax, soya wax, carnauba waxes and all essential oils were are purchased from Kelkar Foods and Fragrances, Pune, India.

[0095] The Fillers namely nano crystalline cellulose, protein extract and rose clay were purchased from Sigma Aldrich. Microcrystalline cellulose, guar gum were purchased from Hi-media. Hemp was purchased from Texventures LLP, Mumbai.

EXAMPLES

[0096] The disclosure is hereby illustrated with working examples, and is intended to exemplify the working of disclosure only and not intended to be taken restrictively, or to imply any limitations on the scope of the present disclosure.

Example 1

[0097] Five parts of seaweed polysaccharide powder, 3 parts of plasticizer, and one part of candelilla wax was added in 100 parts of warm water and mixed for 10 minutes. The resulting solution was then heated at 80°C in water bath to make a homogenous solution. The resultant solution was defoamed under reduced pressure to remove trapped air. The solution was casted on glass plate and dried under vacuum oven to get home compostable seaweed film. The said experiment was further replicated by replacing candelilla wax with other natural waxes as given below.

[0098] The natural waxes are organic compounds with long aliphatic alkyl chains with many functional groups such as fatty acids, primary and secondary alcohols, ketones, aldehydes and fatty acid esters. Beeswax for instance is an ester of triacontanol and palmitic acid. The waxes add to the hydrophobicity of the membrane. The experiment conducted showed that the natural waxes used can be replaced with each other without much difference in the hydrophobicity of the film. The use of different waxes however was observed to promote a level of rigidity which varies with the type of natural wax.

Table 1 : Use of different waxes in the film composition

Example 2

[0099] Procedure of example 1 was repeated with a mixture of different seaweed polysaccharide and their combinations. In different experimental set ups as provided in the table below, polysaccharide powder five parts was added in 90 parts warm water and mixed for 10 min. The resulting solution was then heated at 80°C in water bath for 30 to 45 minutes. The solution was heated at the same temperature for Ih with stirring at 1000 rpm to become a liquid gel. The plasticizer 2.5 parts were then introduced into the solution and the resulting solution was heated at same temperature. The seaweed polysaccharides are prone to fungal attack. Therefore, antifungal agent was added to improve the shelf life the film at normal environmental condition. The resulting solution was heated at 80°C for 15 min. A packaging solution was produced by pouring the resultant solution in glass container and allowed to dry at room temperature to get Home compostable seaweed film. The weight ratio of polysaccharide to plasticizer was 1 : 0.5. It was observed that whereas the film without any antifungal agent in its formulation degraded in less than 7 days’ time under high humidity (80% and above); the film with antifungal agent in its composition remained sustained for more than a months’ time.

Table 2: Use of different types of seaweed polysaccharides for the seaweed film

Example 3

[0100] Procedure of example 1 was repeated with different seaweed polysaccharide and their combinations. In different experimental set-ups as provided in the table below, polysaccharide powder five parts was added in 90 parts warm water and mixed for 10 min. The resulting solution was then heated at different temperatures depending on the type of polysaccharide used (please see the table below). The solution was heated at the same temperature for Ih with stirring at 1000 rpm to become a liquid gel. Sorbitol 2.5 parts were then introduced into the solution and the resulting solution was heated at same temperature. 0.5 parts of candelilla wax (with respect to the seaweed polysaccharide) was further added followed by the antifungal agent. The resulting solution was heated at 80°C for 15 min. A packaging solution was produced by pouring the resultant solution in glass container and allowed to dry at room temperature to get home compostable seaweed film. The weight ratio of polysaccharide to plasticizer was 1 : 0.5. It was observed that by using mixture of different types of carrageenan the gelling and solution properties were altered which helped in easy drying and casting of the film.

Table 3: Different types of carrageenan used in the seaweed film

Example 4

[0101] Procedure of example 1 was repeated with different grades of seaweed polysaccharide and their combinations were tested. In different set-ups as provided in the table below, different grades of polysaccharide powder or their mixtures were added in 90 parts warm water and mixed for lOmin. The resulting solution was then heated at 80°C in water bath for 30 to 45 minutes. The solution was heated at the same temperature for Ih with stirring at 1000 rpm to become a liquid gel. The Plasticizer 3.5 parts were then introduced into the solution and the resulting solution was heated at same temperature. The resulting solution was heated at 80°C for 15 min. Other components (antifungal agents and natural wax) were added as detailed in Example 2 and 3. A packaging solution was produced by pouring the resultant solution in glass container and allowed to dry at room temperature to get Home compostable seaweed film. The weight ratio of polysaccharide to plasticizer was 1 : 0.5. The difference in the grades of polysaccharide helps in accommodating an increase or decrease in solid content of the film as desired. It also leads to a decrease in drying time of the film. The use of semi-refined carrageenan will also result in reduced cost of production of the film during large-scale production.

Table 4: The use of different grades of carrageenan in the seaweed film

Example 5

[0102] The experimental set up of example 2 was repeated with addition of an essential oil and an antifungal agent. Seaweed polysaccharide powder five parts was added in warm water 90 parts and being mixed from 10 min. The resulting solution was then heated at 100°C in water bath. The solution was heated at the same temperature for Ih with stirring at 1000 rpm to become a liquid gel. The Plasticizer 2.5 parts were then introduced into the solution and the resulting solution was heated at same temperature. The antifungal agent 0.15 parts was added as into the solution and allowed to mix. The essential oil (lemon grass 5%) 0.1 parts were added into the solution and then the mixture was heated at 80°C for 1 h. Essential oils on while on one hand act as antifungal agent, they also add to the transparency to the biofilm. Different oils at varied concentrations were tested for their use in the film of the present invention. Experiments were set up by replacing lemon grass oil with other essential oils as given below. It was observed that in comparison to the other essential oils, the films comprising lemon oil were less transparent. The experiment also exhibited that the addition of essential oils increased the hydrophobicity of the film. Table 5: The use of different types of essential oils on seaweed film composition

Example 6

[0103] The experimental set up of Example 3 was repeated, and different polysaccharides/fillers were tested. Five (5) parts of carrageenan, two (2) parts of plasticizer (glycerol), (0.5) part of a natural wax (lipid) were dispersed in 100 parts of water. One (1) part of either a polysaccharide or other filler cellulose was added to this mixture in different setup as detailed in the table below. The dispersion was heated at 80°C to make the solution homogeneous at 2000 rpm. The resultant solution was defoamed under reduced pressure to remove trapped air. The solution was cooled to 40°C to the casting. The solution was casted on glass plate and dried under vacuum oven to get film.

Table 6: The use of different types of polysaccharides/fillers in seaweed film composition

[0104] The fillers thus added improve the tensile strength of the film. For instance nano-cellulose, hemp and microcrystalline cellulose (MCC) were observed to impart tensile and mechanical strength to the film and also reduced the water vapour transmission rate. In comparison to other fillers, it was noted that MCC produced coarse films with less transparency.

[0105] The films made with seaweed polysaccharides have a directional tearability and such films are easily torn and are not able to withstand weight. The addition of fillers enhances the tensile strength and elongation, while maintaining the OTR of the film of the present invention. For instance, in one of the combinations of the present invention the elongation is enhanced to a level where the film can be used as a cling/sandwich warp. These characteristics of increased tensile strength, elongation %, OTR etc. have broadened the scope of application of the disclosed films. The increased tensile strength of the film mitigates the problem of directional tearability and allows the use of the film as a polybag, which is able to stand like a thick paper bag.

Example 7

[0106] Seaweed polysaccharide powder five parts was added in warm water 90 parts and mixed for 10 mins. The resulting solution was then heated at 120°C in water bath. The solution was heated at the same temperature at for Ih with stirring at 1000 rpm to become a liquid gel. The plasticizer 2.5 parts were then introduced into the solution and the resulting solution was heated at same temperature. The antifungal agent 0.15 parts was added as into the solution and allowed to mix. The essential oil 0.1 parts and emulsifier 0.5 parts were added into the solution and then the mixture was heated at 80°C for 1 h. A packaging solution was produced by pouring the resultant solution in glass container and allowed to dry at room temperature to get home compostable seaweed film. Different sets of experiments were laid out to test different emulsifiers and their concentrations as given below. It was noted that the addition of emulsifier in the formulation improves the homogeneity. Tween 80 acts as the leavening agent while addition of span 80 makes the film glossy.

Table 7: The use of different types of emulsifiers in seaweed film composition

* The percentage of emulsifier is vis-a-vis the seaweed polysaccharide.

Example 8

[0107] In examples 1 to 7, the different variables were tested to see their viability for preparing the seaweed film. Various combinations of the components used for making the film were tried and the films so prepared were tested for their hydrophobicity, tensile strength and other important parameters. The table below provides various permutations and combinations of these variables to produce the home compostable film according to the method of the present invention.

Table 8: Seaweed film compositions

Example 9

[0108] The films as presented in Example 8 above were tried and tested for various physical, mechanical and chemical parameters. The same have been detailed in the table below.

Table 9: Different seaweed film compositions and their characteristics

Example 10

[0109] The films prepared in example 6 and 7 were used for packaging of banana. The shelf life of banana in seaweed film (SWF) is improved compared to conventional plastic. Fruits wrapped in SWF prepared by the method of the present invention showed delayed ripening and resistance to fungal attack as compared to those kept in the Polypropylene (PP) film. In figure 1 (a) the fruits were kept in PP glasses and covered with a lid made of SWF and PP films respectively. The fruits were kept in ambient conditions for 7 days. It was observed that the fruits in PP covered glasses turned black and had fungus growth, the SWF covered banana remained green for the period of the experiment. When covered entirely with the SWF and PP films as shown in Figure lb the SWF covered banana fruits showed delayed ripening in comparison to the PP covered banana fruit, which ripened earlier and caught fungus.

Example 11

[0110] The SWF are hydrophilic in nature however these films are having superior grease resistance and oil resistance. Apart from providing grease resistance, the films have very low oxygen permeability. To improve the grease resistance and oil resistance of the paper, the film prepared in example 6 was used to laminate the paper. The paper was laminated by the SWF as shown in Figure 2 and compared with the base paper. The experiment shows superior grease and oil resistance compared to the base paper. The films being completely bio-based and food safe, have immense application in food industry. With combinations disclosed in the specification and employing sorbitol as a plasticizer, the bio-based film of the present invention can be used as dissolvable tea/coffee bags. On the other hand the increased elongation allows for its use as a cling wrap and also as wraps for bakery products such as beard etc.; similarly the bio-based films with increased thickness and sturdiness can be made into food boxes with grease and oil resistance. Example 12

[0111] The disintegration rate of these films is affected by the ambient conditions. Therefore it was noted that under different prevailing ambient conditions of during the year the film needed an average to 30 to 180 days to get completely disintegrated and decomposed in natural compost. The disintegration also depends on the thickness of the film. Figure 3 illustrates the decomposition of the films. The films used in the present experiment varied in thickness from 10 to 250 microns and their complete decomposition was noted under different temperatures and humidity conditions prevailing over the year. The table below gives the number of days over which the films decomposed completely under varied temperature and humidity conditions.

Table 10: Decomposition of the seaweed film of the present invention

Claims

CLAIMS We Claim:

1. A home compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film comprising: i. 2 to 7% (w/w) seaweed polysaccharides; ii. a plasticizer in the ratio of 0.2 to 1 of seaweed polysaccharide; iii. 0.05 to 0.5%(w/w) of an anti-fungal agent; iv. 500 ppm to 10000 ppm of essential oil; v. wax in the range of 5 to 20% of the seaweed polysaccharide vi. 5 to 30% (w/w) at least one polysaccharide and/or filler; and vii. an emulsifier in the ratio of 0.1 to 0.5 of seaweed polysaccharide.

2. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein the film has tensile strength 2MPa to 30 MPa; elongation at break 20 to 150%; contact angle 15 to 100° (degree); water vapour transmission rate 50 to 1200gm/m2/day; oxygen transmission rate 0.1 to 50 gm/cc/day; seal strength 1.5 to 10 N/mm and wherein the shelf life of film and the products made thereof is at least 2 years under ambient conditions.

3. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein seaweed polysaccharides is selected from pure refined carrageenan, semi-refined carrageenan, alginate, fucoidan, agar, ulvan and combinations thereof.

4. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein the pure or semi-refined carrageenan is selected from kappa, iota or lambda carrageenan and combinations thereof.

5. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein the plasticizer is selected from polyols, sorbitol, glycerol and combinations thereof.

6. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein at least one polysaccharide and/or filler is selected from methyl cellulose, microcrystalline cellulose, nano crystalline cellulose, HEMP fibre, banana fibre, tapioca starch, corn starch, protein extract, organic clay and combinations thereof. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein the wax is natural wax is selected from beeswax, soya wax, carnauba wax, candelilla wax and combinations thereof. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, further comprises of organic clay selected from well-Kaolin, red clay, rose clay and green clay and combinations thereof. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein antifungal agent is selected from sodium benzoate, potassium sorbate and combinations thereof. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein essential oil is selected from lemon grass oil, neem oil, eucalyptus oil, clove oil, cinnamon oil, tree tea oil, turmeric and combinations thereof. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein emulsifier is selected from Span 80, Span 60, Span 20, Tween 80, Tween 20 and combinations thereof. A process for preparing the home-compostable, 100% natural, non-toxic, hydrophobic seaweed polysaccharide based film as claimed in claim 1, the process comprising: a) processing and isolating seaweed polysaccharides; b) heating seaweed polysaccharides obtained from step (a) and water at a temperature in the range of 80 to 120°C for time period in the range of 30 min to 45 min to obtain a solution; c) adding a mixture comprising a plasticizer, an antifungal agent, an essential oil, wax, at least one polysaccharide and /or filler and an emulsifier to the solution obtained from step (b) at the temperature in the range of 80 to 120°C and stirring the solution for the time period in the range of 30 to 45 min; and d) spreading the resultant solution on a base substrate and drying the solution to obtain hydrophobic polysaccharide film composition. The process for preparing the hydrophobic seaweed polysaccharide based film as claimed in claim 12, wherein the processing and isolating of the seaweed polysaccharides involves the removal of impurities, separation of the seaweed polysaccharide from the aqueous extraction medium; shear stress treatments including treatment with alkaline solutions followed by drying; The process for preparing the hydrophobic seaweed polysaccharide based film as claimed in claim 12, wherein seaweed polysaccharide is obtained from Acetabularia, Batrachospermum, Callophyllis, Ceratium, Chlamydomonas, Chlorella, Chondrus, Cladophora, Codium, Eucheuma, Euglena, Furcellaria, Fucus, Gonyaulax, Gymnodinium, Grassilaria, Hydrodictyon, Hypnea, Halymenia, Iridaea, Kappahycus, Laminaria, Mastocarpus, Macrocystis, Nitophyllum, Noctiluca, Oedogonium, Pediastrum, Pelagophycus, Peridinium, Pleurococcus, Porphyra, Sargassum, Scenedesmus, Spirogyra, Solieria, Ulothrix, Ulva, Vaucheria, Volvox and combinations thereof. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein said film is completely biodegraded and/or disintegrated within a period of 30 to 180 days depending on the real-life conditions namely temperature, humidity, salinity and pH conditions of a home bio-composter. The hydrophobic seaweed polysaccharide based film as claimed in claim 1, wherein the said film composition is produced as sheets; cling wraps; coaling and/or laminates onio other goods that include but are not limited to perishable items such as food and pharma products, paper and traditional plastics like polyethylene (PE) polypropylene (PP), and low density polyethylene (LDPE); tubular rolls; food containers/boxes; carry bags; and dissolvable iea & coffee bags. The hydrophobic seaweed polysaccharide based film as claimed in claim 16, wherein the thickness of the sheets, cling wraps and laminates is in the range of 2 to 250 microns. The hydrophobic seaweed polysaccharide based film as claimed in claim 16, wherein the said film coating and/or laminates onto other goods increases the shelf life of the goods by at least 1 week.