Description:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 & Rule 13)

TITLE OF THE INVENTION:
A COMPOSITION AND METHOD FOR PRODUCTION OF BIODEGRADABLE FILMS

APPLICANT:
Regeno Ventures Private Limited

An Indian entity having address as:
1198, Kingsway Garden, Boyampalayam Pirivu,
PN Road, Tiruppur, Tamil Nadu – 641602, India

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[0001] The present application claims no priority from any of the patent application(s).
TECHNICAL FIELD
[0002] The present disclosure relates to the field of biodegradable materials and polymer-based manufacturing systems. More particularly the present disclosure relates to a composition and method for production of biodegradable films.
BACKGROUND
[0003] Plastics have become an integral part of modern life, revolutionizing industries and enhancing convenience across countless applications. These synthetic polymers, primarily derived from petroleum-based sources, are valued for their durability, lightweight nature, cost-effectiveness, and versatility. From household goods and packaging to automotive components, medical devices, and electronic equipment, plastics have enabled rapid industrialization and innovation. Their ease of production and adaptability has led to an exponential increase in global plastic use over the past century, making them one of the most widespread materials in human society.
[0004] Among the many uses of plastics, packaging remains the largest sector, accounting for a significant portion of total plastic consumption. Flexible plastic films, in particular, are widely used in the food industry to preserve freshness, extend shelf life, and provide safe, hygienic packaging. These films are also employed in agriculture for mulching, in the healthcare sector for sterile wrapping, and in retail for bags and wraps. The functionality of plastic films being waterproof, lightweight, transparent, and mechanically stable has made them indispensable in a wide range of commercial and industrial applications.
[0005] However, the very properties that make plastic films so valuable also contribute to their environmental impact. Conventional plastics such as polyethylene (PE) and polypropylene (PP) are highly resistant to degradation. Once discarded, they persist in the environment for hundreds of years, accumulating in landfills and natural ecosystems. This long-term persistence has led to a global plastic pollution crisis, with plastic waste contaminating oceans, soil, and even entering the food chain in the form of microplastics. The widespread visibility of plastic waste and its effects on marine life and biodiversity have triggered global concern and calls for urgent action.
[0006] In response to this crisis, there has been a growing interest in sustainable materials that can offer similar performance while reducing environmental harm. Regulatory restrictions on single-use plastics in many countries have accelerated the demand for alternative materials. Consumers and industries alike are increasingly aware of the ecological footprint of plastics and are looking toward greener solutions that align with circular economy principles. This shift has opened new avenues for research and development in biodegradable polymers that can decompose under natural or industrial composting conditions.
[0007] Biodegradable films, particularly those derived from renewable resources, have attracted significant attention as promising alternatives to traditional plastic films. These films are made from polymers such as polylactic acid (PLA), polyhydroxyalkanoates (PHAs), cellulose, and starch. PLA, in particular, is commonly used for its properties, as it is insoluble in water, making it ideal for applications where moisture resistance is required. However, a key limitation of PLA films is that they only biodegrade under specific atmospheric conditions. This means they require controlled environments, such as industrial composting, to break down effectively. Consequently, there is an increasing need for the development of films that can biodegrade under normal, everyday atmospheric conditions.
[0008] Further, starch-based biodegradable polymers, in particular, stand out due to their abundance, low cost, and renewable origin. Sourced from crops such as corn, potato, or cassava, starch is a natural polysaccharide that can be processed into films to improve properties.
[0009] Despite this, starch-based biodegradable films face significant challenges. Their inherent hydrophilicity leads to poor moisture resistance, and they often exhibit lower mechanical strength and barrier properties compared to conventional plastics. This limits their use in high-performance applications unless modified or blended with other materials.
[0010] Additionally, economic challenges also persist, as biodegradable film production can be more expensive than petroleum-based alternatives due to limited scale and complex processing techniques. As the global community intensifies efforts to combat plastic pollution and promote sustainable development, starch-based biodegradable films represent a crucial, though evolving, part of the solution.
[0011] Recent advancements in biodegradable films still face notable limitations, including low tensile strength, limited elongation at break, and high oxygen permeability. These shortcomings make such films unsuitable for food packaging applications and ineffective in extending product shelf life. Furthermore, many of these films require use of incinerators for decomposition, which hinders easy and environmentally friendly disposal, especially in the absence of industrial composting facilities. In addition, if accidentally ingested by animals, these materials may pose significant harm, raising concerns about their ecological and biological safety.
[0012] Thus, in light of the above challenges there is a long felt need to develop a composition and method for production of biodegradable films, while addressing at least one of the limitations as discussed above.
SUMMARY
[0013] In an exemplary aspect, the present disclosure provides, a composition for producing a biodegradable film. The composition comprises of one or more starch-based material, present in an amount ranging between 20%-70% w/w of the total weight of the composition. The composition comprises of a polymeric material, present in an amount ranging between 10%-35% w/w of the total weight of the composition. The composition comprises of a plasticizer, present in an amount ranging between 10%-35% w/w of the total weight of the composition. Further, the composition comprises of an antioxidant, present in an amount ranging between 1%-10% w/w of the total weight of the composition. Additionally, the composition comprises of one or more additives.
[0014] In another exemplary aspect, the present disclosure provides, a method for producing a biodegradable film. The method comprising a step of pre-mixing, a plasticizer with a polymeric material to form a premix in a mixer. The method comprising a step of mixing, one or more starch-based material into the premix. Further, the method comprising a step of extruding, the premix through the first extruder at a temperature ranging between 60°C to 180°C to form continuous strands. The method further comprising step of cooling, the continuous strands using a cooling unit to form cooled strands, wherein the cooled strands are cut using a cutting unit into pellets. Further, the method comprising a step of subsequent extruding, the premix through a second extruder at temperature 180°C to 200°C to form a tubular film structure. Also, the method comprising a step of inflating, the tubular film using an inflating unit into a film bubble, wherein the film bubble is cooled at a temperature range between 20°C to 30°C to form a solidified film. Finally, the method comprising the step of, flattening, the solidified film using a roller into a flat biodegradable film.
DETAILED DESCRIPTION
[0015] Reference will now be made in more detail to embodiments, examples of the specification. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein.
[0016] Accordingly, the embodiments are merely described below, to explain aspects of embodiments of the present description. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. Throughout the present disclosure, the expression "at least one of a, b and c" indicates only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof.
[0017] The subject matter of the present disclosure may include various modifications and various embodiments, and example embodiments described in more detail in the detailed description. Effects and features of the subject matter of the present disclosure, and implementation methods therefor will become clear with reference to the embodiments described herein below. The subject matter of the present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
[0018] It will be understood that although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.
[0019] An expression used in the singular may also encompasses the expression of the plural, unless it has a clearly different meaning in the context.
[0020] In the following embodiments, it is to be understood that the terms such as "including," "includes," "having," "comprises," and "comprising," are intended to indicate the existence of the features or elements disclosed in the specification and are not intended to preclude the possibility that one or more other features or elements may exist or may be added.
[0021] The present disclosure provides a composition and method for production of biodegradable films, addressing the growing need for sustainable and eco-friendly alternatives to conventional petroleum-based plastics. With increasing environmental concerns and regulatory pressures to reduce plastic waste, biodegradable films offer a significant advantage as they decompose naturally under composting or environmental conditions, leaving minimal residue. These films are advantageous due to their reduced ecological footprint, renewability, and potential for safe disposal. The scope of biodegradable films covered in this disclosure includes starch-based films, PVA-starch blend films, plasticized films, and films containing natural polymers or biodegradable additives. Applications include single-use packaging, agricultural mulch films, carry bags, and wrapping materials, making them suitable for both industrial and consumer-level use.
[0022] In an embodiment, the composition for producing a biodegradable film, comprises a blend of biodegradable and film-forming materials designed to offer both functional performance and environmental compatibility. The composition includes native starch, modified tapioca starch, fully and partially hydrolyzed polyvinyl alcohol (PVA), glycerol as a plasticizer, and antioxidants to enhance stability. This specific combination enables the formation of films that are flexible, durable, and capable of degrading under natural or industrial composting conditions, making them suitable for a wide range of packaging and disposable applications.
[0023] In an embodiment, the composition comprises of one or more starch-based material, which serve as the primary biodegradable polymers. These starches provide the film with a natural, renewable base that is both compostable and cost-effective. The use of starch enhances the film's biodegradability while contributing to its mechanical strength and film-forming ability. Depending on the formulation, different types or ratios of starch can be used to tailor properties like flexibility, solubility, and degradation rate, making the material suitable for various environmentally friendly applications.
[0024] In a related embodiment, the one or more starch-based material is present in an amount ranging between 20% to 70% w/w of the total weight of the composition. In a preferred embodiment, the one or more starch-based material is present in an amount ranging between 25% to 65% w/w of the total weight of the composition.
[0025] In an embodiment, the starch-based material comprises of a natural starch and a modified starch. Natural starch provides the base structure and biodegradability, while modified starch improves the film's processability, mechanical strength, and moisture resistance. This combination allows for better control over the physical and functional properties of the film, such as flexibility, transparency, and durability, making it more suitable for commercial applications where performance and environmental impact must be balanced.
[0026] In a related embodiment, the natural starch is selected from at least one of corn starch, tapioca starch, potato starch, wheat starch, rice starch, arrowroot starch, sweet potato starch, and sago starch. In a preferred embodiment, the natural starch is tapioca starch.
[0027] The corn starch (Zea mays) is one of the most widely used sources, offering good film-forming properties and easy availability. Tapioca starch (Manihot esculenta) extracted from cassava, known for its high amylopectin content, which improves film strength and flexibility. Potato starch (Solanum tuberosum) provides good viscosity and gel-forming properties, used in biodegradable packaging. Wheat Starch (Triticum aestivum) is less commonly used due to gluten presence but still applicable for biodegradable films. Rice Starch (Oryza sativa) – offers good water resistance, making it useful for moisture-sensitive applications.
[0028] In another related embodiment, the natural starch is present in an amount ranging between 30 %-70 % w/w of the total weight of the composition. In a preferred embodiment, the natural starch is present in an amount ranging between 35 %-60 % w/w of the total weight of the composition.
[0029] In a related embodiment, the modified starches may be selected from etherified starches, esterified starches, pre gelatinised starches and acetylated starches with each of them being processed either physically or chemically to induce physical changes of induce end groups of different -R compounds in the starch matrix.
[0030] Physically modified starches include pre gelatinised starches which are pre-processed to reduce the possibility of retrogradation. Pre gelling reduces the Tg of the starch allowing it to gelatinise quickly and thicken in cold water. The crystalline structure of the starch is reduced because of the process thereby reducing the chances of retrogradation increasing the possibility of easy processing during twin screw extrusion. Chemically modified starches usually eliminate the free hydrogen group in the starch matrix and inserts a R group depending on the processing raw material employed. This reduces brittleness of the starch molecules but also reduces the chances of hydrogen bonding between the starch and the polymer. Small amounts of modified starches have been added to the mix to ensure better mechanical and thermal properties during twin screw extrusion and blown film extrusion.
[0031] In yet another related embodiment, the modified starch is selected from at least one of modified tapioca starch, hydroxypropyl starch, acetate starch, crosslinked starch, oxidized starch, starch phosphate, starch octenyl succinate, cationic starch, carboxymethyl starch (CMS), hydroxyethyl starch, acetylated starch, esterified starch, etherified starch, and dextrin. In a preferred embodiment, the modified starch is the modified tapioca starch such as acetylated starch, esterified starch, and etherified starch.
[0032] In a further related embodiment, the modified starch is present in an amount ranging between 0.1%-25% w/w of the total weight of the composition. In a preferred embodiment, the modified starch is present in an amount ranging between 1%-20% w/w of the total weight of the composition.
[0033] In an embodiment, a weight ratio of the modified starch and the natural starch in the composition is 1: 3 to 1: 11 and preferably, 1:4 to 1:10.
[0034] In an embodiment, the composition comprises of a polymeric material, which enhances the film’s structural integrity and film-forming properties. The inclusion of the polymeric material improves tensile strength, flexibility, and compatibility with starch-based components.
[0035] In another related embodiment, the polymeric material may be selected from at least one of polyvinyl alcohol (PVA), polyethylene glycol (PEG), polycaprolactone (PCL), polymethyl methacrylate (PMMA), and polylactic acid (PLA). In a preferred embodiment, the polymeric material is polyvinyl alcohol (PVA).
[0036] In a related embodiment, the polymeric material is present in an amount ranging between 10%-35% w/w of the total weight of the composition. In a preferred embodiment, the polymeric material is present in an amount ranging between 12%-33% w/w of the total weight of the composition.
[0037] In an embodiment, the polymeric material is a combination of fully hydrolysed polymeric material, and a partially hydrolysed polymeric material, such as fully hydrolyzed polyvinyl alcohol (PVA-A) and partially hydrolyzed polyvinyl alcohol (PVA-B). The fully hydrolyzed PVA contributes to the rigidity, strength, and water resistance of the film, while the partially hydrolyzed PVA enhances flexibility, processability, and solubility.
[0038] PVA is a petroleum-derived, water-soluble synthetic polymer, commonly produced through the hydrolysis of polyvinyl acetate (PVAc). Despite being synthetic, PVA is biodegradable due to its molecular structure, which allows microbial breakdown. The partially hydrolysed PVA and fully hydrolysed PVA. The degree of hydrolysis determines the end groups in the PVA which determines the extent of hydrogen bonding formation with starches influencing final mechanical properties of the films. The ratio of using different grades of PVA is a major factor influencing the final properties of the blend.
[0039] The fully hydrolyzed PVA (98–100% hydrolysis) offers higher water resistance. The partially hydrolyzed PVA (85–95% hydrolysis) is soluble in water and degrades faster, making it preferable for biodegradable films.
[0040] In an embodiment, a weight ratio of fully hydrolysed polymeric material, and a partially hydrolysed polymeric material ranges between 1:1 to 2:1. In a preferred embodiment, the weight ratio of fully hydrolysed polymeric material, and a partially hydrolysed polymeric material ranges between 1.2:1 to 1.8:1.
[0041] This combination allows for the fine-tuning of the film’s mechanical and functional properties, achieving a balanced profile of strength and elongation. By adjusting the ratio of these two forms, the composition can be optimized for specific end-use requirements, making it versatile for various biodegradable film applications.
[0042] In a related embodiment, the fully hydrolysed polymeric material is present in an amount ranging between 1%-20% w/w of the total weight of the composition. In a preferred embodiment, the fully hydrolysed polymeric material is present in an amount ranging between 3%-9% w/w of the total weight of the composition.
[0043] In another related embodiment, the partially hydrolysed polymeric material is present in an amount ranging between 1%-20% w/w of the total weight of the composition. In a preferred embodiment, the partially hydrolysed polymeric material is present in an amount ranging between 6%-18% w/w of the total weight of the composition.
[0044] In an embodiment, the composition comprises of a plasticizer, which plays a crucial role in enhancing the flexibility and workability of the biodegradable film. The plasticizer reduces intermolecular forces between polymer chains, thereby increasing the mobility of the matrix and preventing brittleness. This results in a softer, more elastic film that can withstand bending and stretching without cracking. The presence of a plasticizer is essential for achieving the desired mechanical performance, especially in applications requiring high elongation.
Plasticizers are additives used in biopolymer production to enhance the molecular bonding between starch and PVA, aiding in better flexibility, processability, and mechanical properties.
[0045] In a related embodiment, the plasticizer is present in an amount ranging between 10%-35% w/w of the total weight of the composition. In a preferred embodiment, the plasticizer is present in an amount ranging between 12%-33% w/w of the total weight of the composition.
[0046] In another related embodiment, the plasticizer is selected from at least one of glycerol, sorbitol, polyethylene glycol (PEG), urea, citric acid, triacetin, and propylene glycol. In preferred embodiment, the plasticizer is glycerol.
[0047] Glycerol (vegetable-based or synthetic) is widely used, cost-effective plasticizer that improves flexibility but may increase water absorption. Sorbitol (derived from corn or fruits) provides good water resistance. Citric Acid (natural fruit-based acid) acts as both a plasticizer and a crosslinking agent, improving durability. Urea (synthetic but biodegradable) is used in small amounts to modify starch-PVA interactions and reduce film stiffness.
[0048] The plasticizers reduce the strong hydrogen bonds formed between starch and the polymer molecules by inserting themselves within the chains of the polymers thereby reducing the Wan der Waals forces of attraction. This also reduces the glass transition temperature of the polymer matrix thereby making it more ductile in nature. This therefore increase the elongation at break and decreases the tensile strength of the entire matrix.
[0049] The combination of starch, modified starch, PVA and plasticizers (glycerol, sorbitol) is used in conjunction to obtain films of required characteristics including tensile strength and elongation at break. Starches used anywhere between 35-55% as this specific range provides the maximum availability of free hydrogen molecules for the feasibility of hydrogen bond formation between the starch and the other compounds including the polymers and the plasticizers. Starches are brittle in nature and they do not possess the mechanical properties to form biodegradable films on their own. Thus, different polymers like PVA, PLA, PBAT are added with the starch matrices to facilitate hydrogen bond formation and development of biodegradable films of sufficient mechanical properties.
[0050] PVA which is a water-soluble and biodegradable polymer is used in specified proportions with ranges between 30-20% as this provides avenues for the hydrogen bond formation with the starch molecules thereby not only providing chain strength but also elongation of the chains to induce better mechanical properties. By forming hydrogen bonds with the starch matrix, it reduces the brittleness by the following.
[0051] Both starch and PVA are hydrophilic, allowing strong hydrogen bonding between hydroxyl (-OH) groups. This improves intermolecular cohesion, leading to higher tensile strength and better structural integrity in the film. PVA introduces a more elastic network, allowing polymer chains to move more freely under stress. This makes the film more ductile, increasing impact resistance and elasticity. They also tend to mix with each other well thereby avoiding phase separation while processing. This makes the blend conducive to be used together for a potential hot water-soluble application.
[0052] In an embodiment, the composition comprises of one or more antioxidants. These one or more antioxidants are used to reduce the chances of oxidation of starch at high temperatures and sheer during processing thereby reducing browning of the films due to reduced maillard reaction. This in turn increases the transparency of the films and reduces odour.
[0053] In a related embodiment, the one or more antioxidants are present in an amount ranging between 1% to 10% w/w of the total weight of the composition. In a preferred embodiment, the one or more antioxidants are present in an amount ranging between 3% to 8% w/w of the total weight of the composition.
[0054] In another related embodiment, the one or more antioxidants are selected from the group consisting of green tea extract, citric acid, ascorbic acid, tocopherol (vitamin E), rosemary extract, gallic acid, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), grape seed extract, turmeric extract, ferulic acid, caffeic acid, propyl gallate, quercetin, and curcumin. In a preferred embodiment, the one or more antioxidants are green tea extract, citric acid, and ascorbic acid.
[0055] In an embodiment, the composition comprises of one or more additives selected from the group consisting of stabilizers, colourants, antimicrobials, crosslinking agents, fillers, and flame retardants.
[0056] In an embodiment, the composition has a tensile strength ranging between 10 to 20 MPa and an elongation at break ranging between 150-250%. In a preferred embodiment, the tensile strength ranges between 11-19 MPa and an elongation at break ranging between 170-230%.
[0057] In an embodiment, the composition has a 100% hot water solubility. This means that the biodegradable film fully dissolves in hot water without leaving any residue, making it highly suitable for applications where rapid and complete disintegration is required, such as single-use packaging. The complete solubility enhances the film's eco-friendliness by eliminating the need for industrial composting or additional disposal steps, and ensures that the material poses no harm if accidentally ingested by animals or disposed of in natural water bodies.
[0058] In one embodiment, the method for producing a biodegradable film, involves a series of controlled processing steps designed to ensure uniform blending, stability, and film quality. The method includes the preparation of a homogeneous mixture of starch-based materials, polymeric components, plasticizers, and antioxidants, followed by a resting or soaking phase to promote hydrogen bonding and improve compatibility. This is followed by high-shear mixing to ensure uniform dispersion, and extrusion using a twin screw extruder under optimized temperature and pressure conditions to melt and fuse the ingredients into consistent strands. These strands are then pelletized and further processed in a blow film extruder, where controlled heat and mechanical shear enable the formation of thin, flexible, and durable biodegradable films. The process enhances the film properties such as tensile strength, elongation, and biodegradability.
[0059] In an embodiment, the method involves a step of pre-mixing, a plasticizer with a polymeric material to form a premix. This step is essential to ensure that the plasticizer is evenly distributed throughout the polymer matrix, enhancing the flexibility and processability of the final film. By thoroughly blending these components before adding other ingredients, the premix facilitates better compatibility and interaction among the materials, resulting in improved mechanical properties and consistent film quality during subsequent processing stages.
[0060] In a related embodiment, the premix is allowed to rest for a resting period ranging from 1 to 20 hours prior to the addition of the starch-based material. In a preferred embodiment, the resting period ranges from 1 to 10 hours.
[0061] The resting period is crucial to improve the processability of the blend in the twin screw extruder by reducing the melting point of the PVA through interaction. Moreover, component such as glycerol is hygroscopic, meaning it absorbs water and spreads through the polymer matrix. Soaking allows glycerol to penetrate PVA molecules, breaking intermolecular hydrogen bonds and increasing chain mobility. Furthermore, soaking allows uniform polymer-plasticizer blend, leading to consistent mechanical properties reducing rigidity of the blend.
[0062] In a related embodiment, the method also involves pre-Swelling of PVA for better dissolution. Swelling helps break polymer aggregates, reducing processing time and ensuring a smooth solution. This is especially useful for the twin screw extrusion processes. A pre-soaked PVA needs less heat to dissolve or process, reducing thermal degradation risks. It prevents clumping and uneven viscosity, which is crucial in biodegradable film production.
[0063] In an embodiment, the method involves a step of mixing, one or more starch-based material into the premix in a mixer. This step ensures thorough integration of the starches with the plasticized polymer blend, promoting uniformity in the composition. Proper mixing of starch with the premix is critical to achieving consistent film-forming properties, enhancing biodegradability, and optimizing the mechanical strength and flexibility of the final biodegradable film.
[0064] In a related embodiment, the mixer is selected from at least one of ribbon blender, paddle mixer, ploughshare mixer, double cone blender, V-blender, sigma mixer, vertical screw mixer, conical screw mixer, planetary mixer, and tumble blender. In a preferred embodiment, the first mixer is a ribbon blender.
[0065] In an embodiment, the method involves a step of extruding, the premix in a first extruder at a temperature ranging between 60°C to 180°C to form continuous strands. In a preferred embodiment, the tempretaure in the firest estruder ranges between 65°C to 185°C.
[0066] During this step, the uniformly melted and blended premix is forced through a die to produce long, continuous strands with consistent diameter and texture. Precise control of extrusion parameters such as temperature, and pressure is essential to maintain the homogeneity and quality of the strands, preventing defects like uneven thickness or air bubbles. The temperature and pressure is adjusted to ensure the materials are completely melted and blend homogenously. This optimisation results in enhanced mechanical properties of the biopolymer. Vent holes are provided to remove excess moisture that would hinder the melting and blending of the raw materials.
[0067] In a related embodiment, the first extruder is selected from at least one of twin screw extruder, a single-screw extruder, a co-rotating twin-screw extruder, and a counter-rotating twin-screw extruder. In a preferred embodiment, the first extruder is a twin-screw extruder.
[0068] In another related, embodiment the twin screw extruder has a screw speed ranging between 150 to 200 RPM. In a preferred embodiment, the twin screw extruder has a screw speed ranging between 160 to 190 RPM.
[0069] In yet another related embodiment, operating the extruder at speeds below this range leads to insufficient shear and poor homogenization of the polymer-starch matrix, resulting in non-uniform strand formation. Conversely, screw speeds above 200 RPM tend to introduce excessive shear and thermal energy into the blend, which may cause partial degradation of starch and plasticizers. This thermal degradation can adversely affect the mechanical properties of the film, making it brittle and reducing its elongation at break. Therefore, maintaining the screw speed within the optimal range is critical to achieving a uniform, well-melted blend and ensuring the resulting film exhibits the desired balance of tensile strength and flexibility.
[0070] The temperature and pressure have been optimised across the different zones in the extruder inorder to melt and homogenise the raw materials Multiple vent holes are provided to remove excess moisture. A kneading zone is provided to homogenise and blend the raw materials to result in a uniform blend with the reinforced properties of the individual raw materials. The twin screw extruder design has been optimised to increasing the homogenity by increasing the number of kneading zones. The twin screw extruder with more than 5 die holes are used in the process in order to efficiently maintain the pressure.
[0071] The specified temperature is maintained to ensure proper melting and processing of the blend. The temperatures are maintained along different zones including mixing, kneading and compressing zones. Two side feeders are used to ensure no pressure differential is induced during the process. Pre blend of the raw materials is fed into the extruder with screw configuration consisting of mixing, kneading and compressing zones.
[0072] In an embodiment, the initial temperature range is sufficient to gelatinise the starch and homogenize the blend in the extruder. The temperature is progressively increased to ensure melting of the PVA and formation of a uniform matrix. Twin-screw extrusion is used for processing technique for manufacturing biodegradable polymer blends and biopolymer composites. This ensures efficient mixing, shearing, and compounding of biodegradable raw materials while maintaining optimal processing conditions. A twin-screw extruder consists of two intermeshing screws rotating within a barrel, where the biodegradable polymer blend undergoes feeding and conveying. The screws generate heat and shear, converting the materials into a homogeneous melt. The biopolymer is forced through a die to form films, pellets, or sheets for further processing. Twin-screw extrusion is a key technology for developing high-performance biodegradable packaging materials, offering precise control over material composition, processing temperature, and final product properties.
[0073] In an embodiment, the method involves a step of cooling, the continuous strands using a cooling unit to form cooled strands. These cooled strands are cut using a cutting unit into pellets. This cooling process is carefully controlled to prevent deformation or sticking of the strands, ensuring they maintain a consistent shape and size. These pellets serve as convenient intermediate materials that facilitate easier handling, storage, and feeding into subsequent processing equipment such as blow film extruders, ultimately contributing to the production of high-quality biodegradable films.
[0074] The output strands from the extruder are cooled at room temperature without external water nor air cooling. The strands are cut into pellets to enable ease of processing in the blow film extruder. Unlike regular cooling mechanisms, external water and air are not provided to ensure the output is dry without any air bubbles. A long conveyor belt is provided on which the output strands from the twin screw extruder are cooled down at room temperature.
[0075] In an embodiment, the method involves a step of subsequent extruding, the premix through a second extruder at temperature 180°C to 200°C to form a tubular film structure. In a preferred embodiment, the step of subsequent extruding, the premix through a second extruder at temperature 185°C to 195°C to form a tubular film structure.
[0076] The pellets from the twin screw extruder are fed into the in let of the blow film extruder where the pellets undergo melting and blending. The temperature and pressure are maintained at the optimum range to ensure proper blowing of the pellets into an inflated balloon.
[0077] In a related embodiment, the second extruder is selected from at least one of a blow film extruder, a flat-die extruder, a tubular film extruder, a melt-blown extruder, and an annular die extruder. In a preferred embodiment, the second extruder is a blow film extruder.
[0078] In a related embodiment, the pellets from the output of the twin screw extruder is fed into the blow film extruder. Blow film extrusion is a manufacturing process used to produce thin, continuous plastic films from biodegradable polymers. It is commonly used for making biodegradable films, food packaging, and agricultural films.
[0079] In another related embodiment, the step of subsequent extruding is carried out by maintaining the speed of the second extruder in the range between 10-60 RPM. In a preferred embodiment, the step of subsequent extruding is carried out by maintaining the speed of the second extruder in the range between 20-50RPM.
[0080] In an embodiment, the method involves a step of inflating, the tubular film using an inflating unit into a film bubble. This process applies controlled air pressure to expand the tubular film evenly, creating a thin, uniform bubble that can be stretched to the desired thickness. Proper regulation of inflation parameters ensures consistent film dimensions, improved mechanical properties, and optimal clarity, which are essential for producing high-quality biodegradable films suitable for packaging and other applications.
[0081] In a related embodiment, the tubular film is inflated at a temperature range between 150°C to 200°C. In a preferred embodiment, the tubular film is inflated at a temperature range between 160°C to 190°C into the film bubble.
[0082] In an embodiment, the film bubble is cooled at a temperature range between 10°C-40°C to form a solidified film. In preferred embodiment, the film bubble is cooled at a temperature range between 20°C to 30°C to form a solidified film.
[0083] In an embodiment, the method involves a step of flattening, the solidified film using a roller into a flat biodegradable film. This rolling process smooths and compresses the inflated film bubble, transforming it into uniform, flat sheets with consistent thickness. The controlled pressure and speed of the rollers help eliminate wrinkles and air pockets, enhancing the film’s surface quality and mechanical strength. This step is crucial for producing biodegradable films that are ready for further processing, packaging, or conversion into final products.
[0084] The final biodegradable film product finds versatile applications across multiple industries due to its strength, flexibility, and environmental sustainability. It is well-suited for garment packaging and secondary packaging, providing an eco-friendly alternative for wrapping and transporting textile products. In the retail and grocery sectors, the film can be used for grocery packaging, offering a compostable and safe solution for carrying daily essentials. Its low oxygen permeability and hot water solubility make it ideal for food packaging, enhancing shelf life while ensuring easy disposal. Additionally, it is applicable in garfilm packaging and courier packaging, serving as a sustainable substitute for conventional plastic wraps and pouches used in shipping. In the agricultural domain, the film can be effectively used as mulch films, contributing to soil protection and moisture retention while decomposing naturally after use.
[0085] The following examples are provided to illustrate aspects of the present disclosure and the processes or compositions described herein.
EXAMPLES
EXAMPLE 1: A composition for producing biodegradable film
A series of compositions were developed and evaluated to prepare biodegradable films with varying mechanical properties tailored for specific applications such as packaging, wrapping, and sustainable plastic alternatives. Each formulation was composed of modified starch, tapioca starch, polyvinyl alcohol (PVA), glycerol, and antioxidants, with the ratios varied to balance tensile strength and elongation.
Table 1: Illustrates the concentration of components in used in the formation of biodegradable film.
Components Composition I (%) Composition II (%) Composition III (%)
Modified starch 5 5 5
Tapioca starch 50 40 50
Fully hydrolysed PVA (PVA-A) 12 3 7.5
Partially hydrolysed PVA (PVA-B) 3 12 7.5
Glycerol 20 35 25
Antioxidant 2 5 2

Table 2: Table 1 illustrates the comparison between properties of composition I, II and III.
Composition Tensile strength Elongation at break Hot water solubility at 75 degrees
Composition I 4.2 95 Soluble
Composition II 1.8 120 Soluble
Composition III 4.0 140 Soluble

In conclusion, among the three compositions, Composition 1 delivered high tensile strength but showed limited elongation and lower flexibility, making it suitable for rigid or semi-rigid packaging applications. Composition 2 offered excellent flexibility and elongation but suffered from poor mechanical strength and higher water solubility, limiting its usability in high-moisture or high-load scenarios. Composition 3 demonstrated the most desirable balance, achieving both high tensile strength and elongation at break, with moderate hot water solubility and stable shelf-life performance. Thus, Composition 3 is considered the optimal formulation for biodegradable film applications that require both strength and flexibility along with environmental stability.
Example 2: A method for preparation of a biodegradable film
To produce a biodegradable film using the concentration ranges provided in the composition III (refer example 1 and table 1), glycerol, polyvinyl alcohol (PVA) both fully hydrolysed (PVA-A), and partially hydrolysed (PVA-B) were initially premixed in a ribbon blender and allowed to rest for a period ranging from 10 to 20 hours. After the resting, starch was introduced into the mixture, and the entire batch was blended in a ribbon blender for a period of 1-2 hour to achieve uniform mixing resulting into a moist powder mixture.
This moist powder mixture was subsequently fed into a twin screw extruder. The temperature of the twin screw extruder was maintained between 65°C to 175°C facilitating complete and uniform melting of all components without causing degradation, yielding homogenized strands, which were then cut into uniform pellets. These uniform pellets were cooled using a cooling unit.
Further, these cooled pellets were then introduced into a blow film extruder, where processing parameters were carefully optimized. The blow film extruder speed was maintained in the range between 15-95 RPM, to achieve uniform melting without introducing air bubbles. The blow film extruder temperature was controlled between 185°C to 195°C, which allowed for adequate melting of the pellets and a tubular film structure was formed. This tubular film structure was then inflated into a film bubble at a temperature 160°C to 190°C. Film bubble was again cooled using a cooling unit to a temperature 20°C to 30°C forming a solidified film. Additionally, the solidified film was flattened by using a roller having a final product of flat biodegradable film.
The biodegradable films produced using the above process demonstrated a high tensile strength ranging between 10-20 MPa, a high elongation at break ranging between 15-250%, indicating both mechanical robustness and flexibility. These optimized processing conditions covering mixing, extrusion, and blow film parameters were critical to ensuring consistent quality and performance of the biodegradable film.
Various embodiments of the disclosure offer numerous advantages of the method. The disclosed composition and method provide several technical advantages, but not limited to the following:
• High tensile strength
• High elongation at break
• Low oxygen permeability, making it suitable for food packaging applications and increasing the shelf life
• Hot water soluble, ensuring easy disposal.
• Industrial decomposer is not needed.
• In case of accidental ingestion by animal, no harm would be caused.

[0086] It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the scope of the present disclosure as defined by the following claims, and equivalents thereof.
, C , Claims:WE CLAIM:
1. A composition for producing a biodegradable film, the composition comprising:
one or more starch-based material, present in an amount ranging between 20%-70% w/w of the total weight of the composition;
a polymeric material, present in an amount ranging between 10%-35% w/w of the total weight of the composition;
a plasticizer, present in an amount ranging between 10%-35% w/w of the total weight of the composition;
one or more antioxidants, present in an amount ranging between 1%-10% w/w of the total weight of the composition; and
one or more additives.
2. The composition as claimed in claim 1, wherein the starch-based material comprises of a natural starch and a modified starch.
3. The composition as claimed in claim 2, wherein the natural starch is present in an amount ranging between 30 %-70 % w/w of the total weight of the composition.
4. The composition as claimed in claim 2, wherein the modified starch is present in an amount ranging between 0.1%-25% w/w of the total weight of the composition.
5. The composition as claimed in claim 1, wherein the polymeric material is selected from at least one of polyvinyl alcohol (PVA), polyethylene glycol (PEG), polycaprolactone (PCL), polymethyl methacrylate (PMMA), and polylactic acid (PLA).
6. The composition as claimed in claim 1, wherein the polymeric material is a combination of fully hydrolysed polymeric material, and a partially hydrolysed polymeric material.
7. The composition as claimed in claim 1, wherein a weight ratio of fully hydrolysed polymeric material, and a partially hydrolysed polymeric material is 1:1 to 2:1.
8. The composition as claimed in claim 1, wherein the plasticizer is selected from at least one of glycerol, sorbitol, polyethylene glycol (PEG), citric acid, triacetin, and propylene glycol.
9. The composition as claimed in claim 1, wherein the one or more antioxidants are selected from the group consisting of green tea extract, citric acid, ascorbic acid, tocopherol (vitamin E), rosemary extract, gallic acid, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), grape seed extract, turmeric extract, ferulic acid, caffeic acid, propyl gallate, quercetin, and curcumin.
10. A method for producing a biodegradable film, the method comprising:
pre-mixing, a plasticizer with a polymeric material to form a premix,
mixing, one or more starch-based material into the premix in a mixer;
extruding, the premix in a first extruder at a temperature ranging between 60°C to 180°C to form continuous strands;
cooling, the continuous strands using a cooling unit to form cooled strands,
wherein the cooled strands are cut using a cutting unit into pellets;
subsequent extruding, the pellets through a second extruder at temperature 180°C to 200°C to form a tubular film structure;
inflating, the tubular film in the second extruder into a film bubble,
wherein the film bubble is cooled at a temperature range between 20°C to 30°C to form a solidified film; and
flattening, the solidified film using a roller into a flat biodegradable film.
11. The method as claimed in claim 10, wherein the premix is allowed to rest for a period ranging from 1 to 20 hours prior to the addition of the starch-based material.
12. The method as claimed in claim 10, wherein the step of mixing is carried out in a mixer selected from at least one of ribbon blender, paddle mixer, ploughshare mixer, double cone blender, V-blender, sigma mixer, vertical screw mixer, conical screw mixer, planetary mixer, and tumble blender.
13. The method as claimed in claim 10, wherein the step of extruding is carried out in first extruder selected from at least one of twin screw extruder, a single-screw extruder, a co-rotating twin-screw extruder, and a counter-rotating twin-screw extruder.
14. The method as claimed in claim 10, wherein at step of extruding is carried out by maintaining the speed of the first extruder in the range between 150-200 RPM.
15. The method as claimed in claim 10, wherein the step of subsequent extruding is caried out using a second extruder selected from at least one of a blow film extruder, a flat-die extruder, a tubular film extruder, a melt-blown extruder, and an annular die extruder.
16. The method as claimed in claim 10, wherein at step of subsequent extruding is carried out by maintaining the speed of the second extruder in the range between 10-60 RPM.
17. The method as claimed in claim 13, wherein the tubular film is inflated at a temperature range between 150°C and 200°C.

Dated this 22nd day of August, 2025

PRIYANK GUPTA
IN-PA-1454
AGENT FOR THE APPLICANT