Description:FIELD OF THE INVENTION
[001] The present invention relates to a biodegradable polymer composition for packaging films under composting conditions, more particularly to packaging films for copper rods, aluminum ingot and plates. The present invention also relates to a process of preparing the biodegradable polymer composition and a method of preparing biodegradable films.

BACKGROUND OF THE INVENTION
[002] Biodegradable polymers began to provide a solution to the problem of Waste Management relating to Plastics from the 70's. Biodegradable polymer undergoes biodegradation when it is buried in the soil leaving no remains of the polymer or other toxic residues. A “biodegradable” polymer is capable of mineralizing completely on burial within a given period of time, leaving no traces of polymer in addition to a total absence of hazardous or toxic residue, unlike degradable polymer.
[003] Currently conventional plastics like polyethylene (PE) are being used for the packaging of copper rods which are basically non-biodegradable and single use creating environment pollution and ecological hazards.
[004] Accordingly, alternate material needs to be developed in place of single use plastic for product packaging purpose replacing the single use plastic which is being used in various application in plant and in manufacturing area particularly for copper and aluminum industries.
[005] Polylactic acid (PLA) is a synthetic thermoplastic polyester which is available in large volumes and used primarily for packaging applications. It has desirable environmental credentials, as it is readily produced from sustainable (plant) feedstock, with lower carbon footprint. In principle PLA can be recycled either by thermoplastic methods or by hydrolytic cracking back down to monomer. Furthermore, PLA undergoes biodegradation by a two-stage process consisting of hydrolysis to low molecular weight oligomers, followed by complete digestion by microorganisms. Although, Polylactic acid (PLA) is a biodegradable material which is sourced from renewable resources, the toughness of PLA is quite low since it is hard and brittle with poor flexibility and hence, its application gets restricted when it is solely used. Accordingly, to overcome the drawbacks of PLA blending of other thermoplastics with PLA is done.
[006] Polybutylene adipate terpthalate (PBAT) is a biodegradable random copolymer, specifically a copolyester of adipic acid, 1,4-butanediol and terephthalic acid and well known for its compostability, good elongation, flexibility, toughness, high processability and thermal stability. However, it has low strength and glossiness. PBAT is used commonly for blending with PLA in order to improve the toughness and elongation at break.
[007] In spite of the various biodegradable polymer composition based on blends of PLA and PBAT known in the art, the packaging films prepared from these biodegradable polymers lack the required properties which make the packaging films not suitable for copper rods, aluminum ingot and plates. The films known in the art lack one or more properties such as – required thickness, transverse tensile strength, longitudinal tensile strength, transverse elongation at break, longitudinal elongation at break, stretchability, compostability, transparency. Further, the films known in the art not useful for packaging of copper rods, aluminum ingot and plates for lack of weather resistance and not being environmentally friendly.
[008] Owing to the foregoing problems, various biodegradable polymer composition has been formulated which addresses the issues of biodegradable packaging films known in the art. Particularly, these compositions address the issues regarding the required thickness, transverse tensile strength, longitudinal tensile strength, transverse elongation at break, longitudinal elongation at break, stretchability, compostable, transparency and weather resistance in addition to being environmentally friendly. The films prepared from these compositions provides a useful packaging of copper rods, aluminum ingot and plates.

SUMMARY OF THE INVENTION
[009] One aspect of the present invention provides biodegradable polymer composition comprising: at least one base matrix polymer, at least one lubricant, at least one plasticizer, at least one light-stabilizer, at least one bio-filler, at least one clarifying agent, at least one chain extender and antioxidant, and compatibilizer A, wherein compatibilizer A comprises Polylactic acid (PLA), at least one compatibilizer and at least one initiator.
[010] Another aspect of the present invention relates to a process for preparing the biodegradable polymer composition comprising the steps: Preparing compatibilizer A pellets by chemical modification of Polylactic acid (PLA) with a compatibilizer and an initiator; Mixing compatibilizer A pellets with at least one base matrix polymer, at least one lubricant, at least one plasticizer, at least one light-stabilizer, at least one bio-filler, at least one clarifying agent, at least one chain extender and an antioxidant to obtain biodegradable polymer composition.
[011] Another aspect of the present invention relates to a biodegradable film and a method of manufacturing the same with the biodegradable polymer composition of the present invention.
[012] Another aspect of the present invention relates to the use of the biodegradable film for of copper rods, aluminum ingot and plates.

BRIEF DESCRIPTION OF THE DRAWINGS
[010] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 demonstrates stretchability of films: a. commercially available PBAT/PLA film, b. biodegradable film according to present invention (HIN-01), c. Virgin PBAT and d. Virgin PLA.
Figure 2 demonstrates transparency of films: a. commercially available PBAT/PLA film, b. biodegradable film according to present invention (HIN-01), c. Virgin PBAT and d. Virgin PLA.

DETAILED DESCRIPTION OF THE INVENTION
[013] The present invention discloses a biodegradable polymer composition comprising: at least one base matrix polymer, at least one lubricant, at least one plasticizer, at least one light-stabilizer, at least one bio-filler, at least one clarifying agent, at least one chain extender and antioxidant, and compatibilizer A, wherein compatibilizer A comprises Polylactic acid (PLA), at least one compatibilizer and at least one initiator.
[014] As used herein, the term “composition” refers to those formulations which are prepared as mixture, amalgam or blend for coating a metal surface. The composition includes a homogenous or heterogeneous solution and similar formulations known to a person skilled in the art.
[015] In a preferred embodiment, biodegradable polymer composition comprises:
- 94 to 96 wt.% at least one base matrix,
- 1 to 3 wt.% compatibilizer A,
- 0.5 to 1 wt. % at least one lubricant,
- 0.5 to 1 wt. % at least one chain extender and anti-oxidant,
- 0.5 to 1 wt. % at least one plasticizer,
- 0.5 to 1 wt. % at least one light-stabilizer,
- 0.5 to 1 wt. % at least one bio-filler,
- 1 to 1.5 wt. % at least one clarifying agent,
wherein the Compatibilizer A comprises:
- 96.9 to 98 wt. % polylactic acid (PLA)
- 3 to 3.1 wt. % at least one compatibilizer
- 0.8 to 1 wt. % at least one initiator
[016] In a preferred embodiment of biodegradable polymer composition at least one base matrix is selected from a polyester polymer or copolyester such as polybutylene adipate terpthalate (PBAT), Polylactic acid (PLA), Polyhydroxyalkanoates (PHA).
[017] In a preferred embodiment of biodegradable polymer composition at least one chain extender and antioxidant are selected from Irgafos®168, Tinuvin®770, Irganox®1010 and functionalized epoxy.
[018] In a preferred embodiment of biodegradable polymer composition at least one plasticizer is selected from Acetyl Tributyl Citrate (ATBC), Polyethylene Glycol 400 (PEG400), Glycerol, Tetraoctyl Pyromellitate and Epoxidized Soybean Oil.
[019] In a preferred embodiment of biodegradable polymer composition at least one light-stabilizer is selected from 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-octoxybenzophenone.
[020] In a preferred embodiment of biodegradable polymer composition at least one bio-filler is selected from calcium carbonate and talcum powder.
[021] In a preferred embodiment of biodegradable polymer composition at least one clarifying agent is selected from Millad NX 8000, Millad 3988, trixylyl phosphate, ethylbenzene aniline.
[022] In a preferred embodiment of biodegradable polymer composition at least one compatibilizer is selected from Glycerol Monostearate (GMS), Glycidyl Methacrylate (GMA), Polypropyleneglycol diglycidyl ether.
[023] In a preferred embodiment of biodegradable polymer composition at least one initiator is selected from cumene peroxide, benzoyl peroxide, iso-propanol, trimethylol propane (TMP).
[024] In a preferred embodiment of biodegradable polymer composition at least one lubricant is selected from Ethylene Bis Stearamide (EBS), Erucamide, Stearic Acid, Zinc Stearate, Calcium Stearate and polyethylene wax.
[025] As used herein, the compatibilizer A refer to PLA modified with at least one compatibilizer and an initiator. In an embodiment of the present invention glycidyl methacrylate (GMA) has been used as the compatibilizer since, it is bi-functional with inherent epoxy groups and double bonds that can graft PLA using benzoyl peroxide as an initiator. This reaction generates PLA-g-GMA chains wherein, the epoxy groups improve the compatibility in between PBAT and PLA.
[026] Further, the bio-filler helps to decrease the static force that arises in between the layers that tend to stick with each other during blown film process. In addition, it can also act as a nucleating agent for improving the crystallization of PBAT as well as PLA and for overall improvement in the mechanical strength of the blend. The increase in crystallization tends to increase the processing efficiency, reduce the forming period of the product resulting a decrease in warpage, deformation and demoulding.
[027] The chain extender can help to reduce the degradation performance tendency of the material owing to heat released, shear and moisture during the time of processing.
[028] The antioxidants can scavenge the free radicals generated during the process protecting the carbon chains from being degraded and also inhibits yellowing, aging and decrease in strength.
[029] The clarifying agent tend to increase the clarity/transparency of the films and the plasticizer reduces the stiffness and improves the flexibility of the blended films.
[030] In another aspect, the present invention relates to a process for preparing the biodegradable polymer composition. The process comprising the following steps:
a. Preparing compatibilizer A pellets by chemical modification of Polylactic acid (PLA) with a compatibilizer and an initiator;
b. Mixing compatibilizer A with at least one base matrix polymer, at least one lubricant, at least one plasticizer, at least one light-stabilizer, at least one bio-filler, at least one clarifying agent, at least one chain extender and antioxidant to obtain the biodegradable polymer composition.
[031] In a preferred embodiment of the process, compatibilizer A pellets are prepared by mixing Polylactic acid (PLA) with a compatibilizer and an initiator in high-speed blender for 5-10 mins and then extruded using twin screw extruder at a speed of 30 rpm.
[032] In a preferred embodiment of the process, mixing of compatibilizer A pellets with at least one base matrix polymer, at least one lubricant, at least one plasticizer, at least one light-stabilizer, at least one bio-filler, at least one clarifying agent, at least one chain extender and antioxidant is done in a high-speed blender for 5-10 mins. Thereafter the mixed pellets are extruded using twin screw extruder at a speed of 30 rpm thereafter the obtained strands are pelletized into pellets of compatibilized blend.
[033] In a preferred embodiment the biodegradable polymer composition blend prepared above is directly used for processing the biodegradable film.
[034] In another aspect, the present invention discloses a method of manufacturing biodegradable film, comprising the following steps:
a. Drying pellets of the biodegradable polymer composition in oven to achieve pre-dried pellets,
b. Blowing the pre-dried pellets to achieve the biodegradable film.
[035] In a preferred embodiment the pellets of biodegradable polymer composition are pre-dried in oven for 24 hrs at 80 °C.
[036] In a preferred embodiment the pre-dried pellets were blown using single screw extruder, preferably at rpm of 30 and extruder Temp maintained at 160/165/170 °C, Die temp- 160 °C.
[037] In another aspect, the present invention discloses a biodegradable film. In preferred embodiment, film is single layer compostable film.
[038] In a preferred embodiment the biodegradable film preferably has a thickness of 40 to 45 µm, transverse tensile strength of 15.2 to 17.2 MPa, longitudinal tensile strength of 22.9 to 24.7 MPa, transverse elongation at break of 620.7 to 638.6 %, longitudinal elongation at break of 476.7 to 664.5 % and stretchability of 200 to 250 % in addition to being compostable, transparent, ecofriendly and weather resistant.
[039] Advantageously, the biodegradable polymer compositions address the issues regarding the required thickness, transverse tensile strength, longitudinal tensile strength, transverse elongation at break, longitudinal elongation at break, stretchability, compostable, transparency and weather resistance in addition to being environmentally friendly. The films prepared from these compositions provides a useful packaging of copper rods, aluminum ingot and plates.

EXAMPLE
[040] The following examples are illustrative of the invention but not limitative of the scope thereof.
[041] Materials and Methods
[042] Materials: Polylactic acid (PLA) with Glycidyl Methacrylate (GMA), Cumene Peroxide, Polybutylene adipate terpthalate (PBAT), Stearic acid, Irgafos®168, Tinuvin®770, Irganox®1010, Glycerol, 2-(2-hydroxy-5-methylphenyl) benzotriazole.
[043] Method: Compatibilizer A was prepared by chemical modification of Polylactic acid (PLA) with Glycidyl Methacrylate (GMA) and Cumene Peroxide wherein, the materials weighed in proportion (96.9 wt% Polylactic acid, 3.1 wt% Glycidyl Methacrylate and 0.8 wt% Cumene Peroxide) are mixed in high-speed blender for 5-10 mins and then extruded using twin screw extruder at a speed of 30 rpm thereafter the obtained strands are pelletized into pellets.
[044] Preparation of biodegradable polymer composition pellets: The compatibilized pellets of PLA/GMA/Cumene peroxide were mixed with weighed proportion of PBAT (96 wt%), bio-filler (CaCO3) (1wt%) and other additives 1 wt% plasticizer, 0.5 wt% antioxidant (Tinuvin®770), 0.5 wt% chain extender, 0.5 wt% lubricant and 1.5 wt% clarifying agent (Milad NX8000) in high speed blender for 5-10 mins. Thereafter the mixed pellets extruded using twin screw extruder at a speed of 30 rpm thereafter the obtained strands are pelletized into pellets.
[045] Preparation of film: The above-mentioned pellet of PBAT/PLA compatibilized blend along with additives was pre-dried in oven for 24 hrs at 80 °C. The pre-dried pellets were then blown using single screw extruder at rpm of 30 and extruder Temp maintained at 160/165/170 °C, Die temp- 160 °C to provide the biodegradable film according to the present invention. The biodegradable film was evaluated for tensile strength (TS), elongation at break (EB), haze and grammage. The results of evaluation are provided in Table 1.
Table 1
Sr. No. Sample Film code TS
(TD)
(MPa) TS
(MD)
(MPa) EB
(TD)
(%) EB
(MD)
(%) Haze
(%) Grammage
(g/m2)
1 Virgin PLA 12.5 8.1 1.2 2.3 1.85 56.24
2 Virgin PBAT 10.8 10.4 494.8 639.7 9.73 22.78
3 Biodegradable Film (HIN-01) 22.9 17.2 620.7 664.5 20 44
4 Commercial PBAT/PLA 1.9 7.6 3.0 8.9 41.38 34.74

[046] It can be seen from above that the biodegradable film according to present invention (HIN-01) indicates better tensile strength and elongation at break in comparison with related known compostable films.
[047] Further, the biodegradable film according to present invention (HIN-01) demonstrates better stretchability (Figure 1b) and transparency (Figure 2b) in comparison to commercially available PBAT/PLA film (Figure 1a and 2a), virgin PBAT film (Figure 1c and 2c) and virgin PLA film (Figure 1d and 2d).
[048] Furthermore, the biodegradable film according to present invention (HIN-01) was evaluated for compostability. The analysis was done as per ISO 17088:2021 standard test with respect to acute earthworm and seed germination, ecotoxicity analysis and heavy metal tests which provides detailed insight regarding the % biodegradability vs. no. of days, heavy metal analysis, eco-friendly nature and sustainability. The compostability analysis is carried out under controlled condition with temperature maintained at 58 °C, ash content of less than 70 %, pH between 7 and 8.2, total dry solids should be between 50 and 55 %, C/N ratio should preferably be between 10 and 40.
[049] The biodegradable film according to present invention (HIN-01) demonstrated a compostability of 92.42 % in 151 days.
[050] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims. , Claims:We Claim
1. A biodegradable polymer composition comprising:
- at least one base matrix polymer,
- at least one lubricant,
- at least one plasticizer,
- at least one light-stabilizer,
- at least one bio-filler,
- at least one clarifying agent,
- at least one chain extender and antioxidant, and
- compatibilizer A,
wherein compatibilizer A comprises Polylactic acid (PLA), at least one compatibilizer and at least one initiator.
2. The composition as claimed in claim 1, comprising:
- 94-96 wt% at least one base matrix polymer,
- 0.5-1 wt% at least one lubricant
- 0.5-1 wt% at least one chain extender and anti-oxidant
- 0.5-1 wt% at least one plasticizer
- 0.5-1 wt% at least one light-stabilizer
- 0.5-1wt% at least one bio-filler
- 1-1.5 wt% at least one clarifying agent, and
- 1-3 wt% at least one compatibilizer A,
wherein the compatibilizer A comprises:
- 96.9-98 wt% Polylactic acid (PLA)
- 3-3.1 wt% at least one compatibilizer
- 0.8-1 wt% at least one initiator.
3. The composition as claimed in claim 1, wherein base matrix is selected from polybutylene adipate terpthalate (PBAT), Polylactic acid (PLA), Polyhydroxyalkanoates (PHA).
4. The composition as claimed in claim 1, wherein Chain extender and anti-oxidant are selected from Irgafos®168, Tinuvin®770, Irganox®1010 and functionalized epoxy.
5. The composition as claimed in claim 1, wherein plasticizer is selected from Acetyl Tributyl Citrate (ATBC), Polyethylene Glycol 400 (PEG400), Glycerol, Tetraoctyl Pyromellitate and Epoxidized Soybean Oil.
6. The composition as claimed in claim 1, wherein light-stabilizer is selected from 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-hydroxy-4-methoxybenzo phenone and 2-hydroxy-4-octoxybenzophenone.
7. The composition as claimed in claim 1, wherein bio-filler is selected from Calcium carbonate and Talcum powder.
8. The composition as claimed in claim 1, wherein clarifying agent is selected from Millad NX 8000, Millad 3988, trixylyl phosphate, ethylbenzene aniline
9. The composition as claimed in claim 1, wherein compatibilizer comprises Glycerol Monostearate (GMS), Glycidyl Methacrylate(GMA), Polypropyleneglycol diglycidyl ether.
10. The composition as claimed in claim 1, wherein the initiator is selected from Cumene Peroxide, Benzoyl Peroxide, Iso-propanol, trimethylol propane (TMP)
11. The composition as claimed in claim 1, wherein the lubricant is selected from Ethylene Bis Stearamide (EBS), Erucamide, Stearic Acid, Zinc Stearate, Calcium Stearate and polyethylene wax.
12. A process for preparing biodegradable polymer composition comprising the following steps:
c. Preparing compatibilizer A by chemical modification of Polylactic acid (PLA) with a compatibilizer and an initiator;
d. Mixing compatibilizer A with at least one base matrix polymer, at least one lubricant, at least one plasticizer, at least one light-stabilizer, at least one bio-filler, at least one clarifying agent, at least one chain extender and antioxidant to obtain biodegradable polymer composition.
13. A biodegradable film comprising biodegradable polymer composition as claimed in claims 1 to 11.
14. The biodegradable film as claimed in claim 13, having thickness of 40-45 µm, transverse tensile strength of 22.9 MPa, longitudinal tensile strength of 17.2 MPa, transverse elongation at break of 620.7 %, longitudinal elongation at break of 664.5 % and stretchability of 200 %.
15. Use of biodegradable film as claimed in claims 13 and 14 for packaging of copper rods, aluminum ingot and plates.
Dated 19th of February 2024
Hindalco Industries Limited
By their Agent & Attorney

(Nisha Austine)
of Khaitan & Co
Reg No IN/PA-1390