DESC:Priority Claim
[0001] This application claims priority from the provisional application numbered 202041018493 filed with Indian Patent Office, Chennai on 30th April 2020 entitled “A biodegradable polyethylene terephthalate packaging material for alcoholic beverages and process of molding thereof”, the entirety of which is expressly incorporated herein by reference.
Preamble to the description
[0002] The following specification particularly describes the invention and the manner in which it is to be performed:
Description of the invention
Technical field of the invention
[0003] The present invention relates to a biodegradable Polyethylene Terephthalate (PET) packaging material and a process of molding the biodegradable PET packaging material. More particularly, the invention relates to the composition of the biodegradable PET container or bottle using biodegradation additive blended in appropriate proportion with PET resin. The invention also discloses an injection stretch blow molding process for preparation of biodegradable PET container or bottle resulting in safe and biodegradable primary packaging of alcoholic beverages.
Background of the invention
[0004] A wide variety of packaging materials are used based on the components and constituents packed. However, plastic is the most commonly used packaging material. While glass, metal and paper are also widely in use for packaging, the most cost-effective material is plastic as it offers many significant advantages such as good barrier, mechanical strength, compatibility with a wide range of products and ease of transit and handling. Plastic also lends itself to a versatile range of established technologies for conversion into rigid or flexible packaging forms.
[0005] Generally, PET is a common thermoplastic polymer of the polyester family. While PET has many other applications of packaging, it is primarily used as raw material for making food packaging components such as bottles or containers for alcoholic beverages, carbonated beverages, edible oils, water, cosmetics, pharmaceutical products, etc. However, limiting the use of single-use packaging material manufactured using polymers such as High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), PET, Polypropylene (PP), Polystyrene (PS) and Expandable Polystyrene (EPS) is an effective measure to mitigate pollution caused by the improper disposal of these packaging materials. Around 40% of the plastic produced globally is used for manufacturing ‘single-use’ packaging materials. ‘Single-use’ packaging materials manufactured using plastics are increasingly becoming a major concern in the current scenario because, on one side, they pollute environment when disposed inappropriately and on the other side they can cause health hazards by toxins that leach out of plastics while they are in contact with foodstuff. Further, due to improper disposal and poor waste management systems, single-use packaging materials often end up in land fill posing environmental risks.
[0006] Hence, developing an alternative, safe and sustainable packaging solution at an affordable price is extremely important for the continuity of several businesses. The packaging formats and materials that are biodegradable in landfill yet stable and safe for them to be used for packaging of foodstuff would be a potential solution in the given context.
[0007] One of the ways to overcome the environmental risks related to single-use plastic packaging is to focus on blending recycled plastic with virgin plastic for manufacturing of packaging materials. Increasing recycled plastic content for packaging might be a prudent choice in countries with mature waste recycling infrastructure, but addition of recycled plastic may not always be safe and also is not allowed in many countries due to lack of adequate plastic recycling infrastructure, well-organized waste segregation and disposal system. In this existing scenario, infusing recycled PET content into virgin PET for packaging that is intended to be in direct contact with foodstuff is not a feasible option to overcome the plastic waste problem across all countries. There are several countries, including India, wherein the local food safety regulation does not even permit or approve use of recycled plastics for packaging applications that are intended to be in direct contact with foodstuff.
[0008] In the above context, biodegradable packaging solutions that are capable of biodegrading into non-toxic materials can be a sought-after alternate in defining a waste-free future.
[0009] Biodegradable polymers when disposed into municipal waste, the polymers degrade without leaving toxic residue and micro-plastics could be the most desired solution to replace fossil fuel-based plastics used in packaging. The biodegradable polymers derived from bio-based feedstock have certain limitations such as lack of stability and compatibility required for protecting foodstuff in good quality during transit, handling and storage. The characteristics such as hydrophilicity, crystallinity, melt instability and thermal retrogradation limit the industrial usage of such biodegradable polymers for injection molded rigid packaging components meant for packaging of alcoholic beverages that demand a high degree of hydrophobicity.
[0010] Another approach of manufacturing biodegradable polymer is by synthesizing renewable monomers such as lactic acid and subjecting to polymerization to obtain Polylactic acid (PLA), which is an environmentally safe substitute. These polymers thus obtained lend themselves into rigid and flexible packaging formats, including being highly amenable to the thermoforming process and further offer good hydrophobicity. However, alcohol dissolution followed by polymer chain scission of PLA polymer matrix make the polymer vulnerable for packaging of alcoholic beverages. The presence of hydroxyl groups in water, as well as in ethyl alcohol, that are the main ingredients of alcoholic beverages, results in strong chemical affinity towards renewable sources of biodegradable polymers because of their similar polarity. The dissolution kinetics of biodegradable polymers comprising hydroxyl groups aggravates due to the strong polarity and hydrophilic nature of alcoholic beverages. Hence, PLA based polymer is not a suitable option for primary packaging of alcoholic beverages.
[0011] Alternatively, non-renewable feedstock for the production of biodegradable polymers seems to be a promising choice for the packaging of alcoholic beverages. The low degree of polarity observed with such non-renewable sources of biodegradable polymer results in the poor dissolution of the polymers into alcoholic solutions. Further, the functional requirement of primary packaging components for alcoholic beverages can be comparatively demanding, particularly with regard to the mechanical stability of such packaging materials.
[0012] It is indeed hard to find an ideal biodegradable polymer that has the confluence of alcohol compatibility, mechanical stability and shelf stability while at the same time is biodegradable in an environmentally safe manner.
[0013] The Patent Application “JP2014198422A” entitled “Injection stretch blow molded bottle and method for manufacturing the same” relates to a method for manufacturing an injection stretch blow molded bottle obtained by subjecting a PET resin composition to the said method. The method comprises the manufacture of transparent bottles by subjecting polyethylene terephthalate (PET) resin composition to the injection stretch blow molding process. The invention makes use of mechanically recycled PET resin composition, which is subjected to the said process to manufacture a preform, the molding is carried out by holding the molten resin holding pressure in the metal molding die at 10-50 MPa.
[0014] The Patent Application “US20020004090A1” entitled “Method for packaging beverages in non-modified polyethylene terephthalate containers” relates to a method for packaging beverages. More particularly, the invention discloses non-modified polyethylene terephthalate containers. The method comprises pasteurizing the beverage, cooling the pasteurized beverage to a temperature below which the containers are deformed, sterilizing the containers and container tops, filling the sterilized containers with a cooled pasteurized beverage, corking the filled sterilized containers, and further pasteurizing the filled and corked containers to a temperature lower than at which the containers are deformed by the action of an excessive amount of heat. The invention applies to the packaging of beverages.
[0015] The Patent Application “CN102391625B” entitled “PET (polyethylene terephthalate) composite material for high-temperature-resistant beverage bottle and preparation process thereof” relates to PET beverage bottles with a high temperature resistant composite material and the process of preparation for the manufacture of the said PET bottles. The composite material comprises polyethylene terephthalate around 52 to 62 parts, nano calcium carbonate around 25 to 35 parts, polyphenylene ether around 10 to 14 parts, antioxidant around 0.01 to 0.1 parts, crosslinking agent around 0.02 to 0.08 parts, lubricant around 0.5 to 1.5 parts. The invention further discloses a process of preparing the beverage bottle with PET refractory composite material. The PET beverage bottles are resistant to high temperature, have good processability, inexpensive and are particularly suitable for packaging beer bottles due to the composite materials used in the process.
[0016] The Patent Application “DE102008054538A1” entitled “Beverage packaging useful as beverage bottles, comprises polymer basic material consisting of polyethylene terephthalate and an agent for improving the barrier properties of the polyethylene terephthalate against gases” discloses a beverage package comprising polyethylene terephthalate and an agent for increasing the barrier properties. The beverage bottles are resistant to moisture, gases and radiation. The additives used along with PET are selected from the group comprising IR absorbers, heat stabilizers, anti-blocking agents, antistatic agents, dyes, catalysts such as titanium-containing catalysts and/or antimony-containing catalysts and additional UV absorbers.
[0017] The Patent Application “AU666435B2” entitled “Method for injection molding polyethylene terephthalate” related to a method for injection molding an uncrystallized or crystallized polyethylene terephthalate into a desired molded form such as preform. The method for injection molding the PET employs a vent type injection unit as a means for omitting the preliminary drying, the unit does not develop a poor screw biting, even when the molding material used is an uncrystallized or crystallized PET. The vent type injection unit can feed a certain amount of the material to injection mold. Thus, it results in the desired transparent molded form such as a preform and uses the preform to produce a thin-wall container at a low cost.
[0018] The Patent Application “US20140197580A1” entitled “Method for producing a bio-pet polymer” related to a method for producing a bio-PET. More particularly, specific methods for producing a bio-PET using a crystallization retarding compound. The invention also relates to a method for producing bio-PET packaging elements such as bottles and a method for producing bio-PET bottles using a crystallization retarding compound.
[0019] Although, there are several grades of plastics available to manufacture packaging materials but biodegradable packaging materials to provide an environmentally safe substitute are fewer. Further, several biodegradable polymer packaging materials are not suitable for alcoholic beverages due to hydrophobicity and inadequate mechanical properties. Hence, there is a need for a rigid packaging material with biodegradability, which is compatible and appropriate for the packaging of alcoholic beverages.
Summary of the Invention
[0020] The present invention relates to a biodegradable polyethylene terephthalate packaging material and a process of molding the biodegradable PET packaging material. More particularly, the invention relates to composition of the polyethylene terephthalate packaging material using biodegradation additive blended in appropriate proportion with PET resin and also relates to the injection stretch blow molding process resulting in safe and biodegradable primary packaging of alcoholic beverages such as bottles or containers.
[0021] The composition of the biodegradable PET bottle or container comprises a masterbatch at a concentration in the range between 0% and 3%, a biodegradation additive at a concentration in the range between 1% and 2%, and the PET resin at a concentration in the range between 95% and 99%. The masterbatch aids in imparting bright, durable and consistent color to the polymer resins. The masterbatch used is but not limited to Renol 3136F. The biodegradation additive used is a polyester copolymer with additive ingredient comprising scissoring agent, organic chemoattractant, organic polymer and few organic nutrients and the PET resin used is considered safe for food packaging materials.
[0022] The biodegradable PET bottle or container as per the invention is manufactured by a single-stage injection stretch blow molding process, which results in the conversion of the thermoplastic resin to containers or bottles.
[0023] The process comprises blending the polymer granules (PET resin) at a concentration in the range between 95% and 99% with masterbatch at a concentration in the range between 0% and 3% and biodegradation additive at a concentration in the range between 1% and 2%. The blended mixture is fed into a screw barrel extruder for melting the mixture and obtain a homogenous mix of polymers and the homogenous mix of the molten polymer is passed through hot runners into injection molds. Then the injection molding technology is used to produce a preform from the molten polymer such that the mold releases the preforms and further subjected to conditioning. The bottle neck finish is formed during injection molding process. The preforms are reheated to glass transition temperature in the conditioning chamber and the conditioned perform is placed inside a stretch and blow mold to stretch the preform longitudinally by introducing a stretch rod. Finally, the preform is blown using two-level air pressure circumferentially to obtain a fully shaped bottle.
[0024] The PET bottle manufactured in the present invention is analyzed for different characteristics such as rate of biodegradability, toxicity, its effect on seed germination, shoot length, root length and biomass in Sorghum species. The results indicated a good biodegradability rate after 90 days and the toxicity results indicated that the residue of the anaerobic biodegradation did not affect the seed germination rate, shoot length, root length and biomass of Sorghum species.
[0025] The composition of the invention provides an environmentally safe, biodegradable, and a cost-effective alternative compared to the existing packaging materials for alcoholic beverages.
Brief description of the drawings
[0026] The foregoing and other features of embodiments will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.
[0027] Figure 1 tabulates the composition of the biodegradable PET bottle along with the weight percentage.
[0028] Figure 2 illustrates a flowchart for the injection stretch blow molding process used for making biodegradable PET bottles.
[0029] Figure 3 illustrates the comparative account of cumulative biogas in inoculum, positive control and the test sample.
[0030] Figure 4 tabulates the effect of residue of PET bottle on seed germination, root length, shoot length and biomass of Sorghum species.
Detailed description of the invention
[0031] Reference will now be made in detail to the description of the present subject matter, one or more examples of which are shown in figures. Each example is provided to explain the subject matter and not a limitation. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention.
[0032] In order to more clearly and concisely describe and point out the subject matter of the claimed invention, the following definitions are provided for specific terms, which are used in the following written description.
[0033] The term "Polymer" refers to a material made of a long-repeated chain of monomers.
[0034] The term "Biodegradable", means capable of being decomposed or decay naturally.
[0035] The term "Masterbatch", refers to a concentrated mixture of pigments or additives encapsulated into a polymer carrier. Some of these masterbatches are used to impart color or other properties to the plastics.
[0036] The term "Chemoattractant", refers to a substance that attracts motile cells towards such substances to enhance the degradation of pollutants.
[0037] The term "Preform", refers to an object in its initial form which when heated and blown takes the intended shape, as the context requires.
[0038] The present invention overcomes the drawback of the existing state-of-the-art technologies by providing a biodegradation additive blended with a polymer resin for manufacturing a biodegradable, environmentally safe packaging material for alcoholic beverages.
[0039] An embodiment of the invention discloses the composition of the biodegradable Polyethylene Terephthalate (PET) container or bottle comprising a masterbatch, a biodegradation additive and a PET resin.
[0040] Figure 1 tabulates the composition of the biodegradable PET bottle along with weight percentage. The composition of the biodegradable PET bottle comprises masterbatch at a concentration in the range between 0% and 3%, biodegradation additive at a concentration in the range between 1% and 2%, and the PET resin at a concentration in the range between 95% and 99%.
[0041] The masterbatch additive used in the composition aids in imparting bright, durable and consistent color to the polymer resins. The masterbatch used is Renol 3136F but not limited to the specified grade, any masterbatch which is appropriate as per food safety regulations for PET packaging that are intended to be in direct contact with foodstuff is suitable for the manufacture of the biodegradable PET bottle.
[0042] The biodegradation additive used in the composition is a polyester copolymer with additive ingredient comprising scissoring agent, organic chemoattractant, organic polymer and few organic nutrients. The biodegradation additive is environmentally safe and non-toxic, moreover, it enables high solid anaerobic biodigestion in the landfill. The biodegradation additive used is Bio D PET Bt grade.
[0043] The PET resin used in the composition is considered safe for food packaging materials. The bottle grade PET resin obtained is suitable for various food, beverage, water, cosmetics, hair oil, disinfectants and pharmaceutical packaging. The PET resin used is Relpet G5801, but not limited to the specified grade, an appropriate PET resin as per the food safety regulation is suitable for the manufacture of the biodegradable PET bottles.
[0044] The invention further discloses a single-stage injection stretch blow molding process for the preparation of the biodegradable PET bottles. The process results in the conversion of the thermoplastic resin to containers or bottles.
[0045] Figure 2 illustrates a flow chart for the injection stretch blow molding process used for making biodegradable PET bottles. The process (200) comprises a step (201), of blending the polymer granules (PET resin) at a concentration in the range between 95% and 99% with masterbatch at a concentration in the range between 0% and 3% and biodegradation additive at a concentration in the range between 1% and 2%. At step (202), the blended mixture is fed into a screw barrel extruder for melting the mixture and obtain a homogenous mix of polymers. At step (203), the homogenous mix of the molten polymer is pushed through hot runners into injection molds. The biodegradation additive is homogeneously distributed throughout the resulting packaging component. At step (204), the injection molding technology is used to produce a preform from the molten polymer. At step (205), the mold releases the preforms, further subjected to conditioning. The bottle neck finish is formed during injection molding process. At step (206), the preforms are reheated to glass transition temperature in the conditioning chamber. Heating the preforms to glass transition temperature makes the preform amenable for stretching and blowing. At step (207), the conditioned perform is placed inside a stretch and blow mold to stretch the preform longitudinally by introducing a stretch rod. Finally, at step (208), the preform is blown using two-level air pressure circumferentially to obtain a fully shaped bottle.
[0046] The biodegradation additive is used in a proportion such that the biodegradable packaging material is in conformance with the prevailing food safety standard.
[0047] In addition, the biodegradability of the packaging material is in conformance with the ISO 15985:2014, that specifies a method for evaluation of ultimate anaerobic biodegradability of plastics based on organic compounds under high-solids anaerobic-digestion conditions by measurement of evolved biogas at the end of the test.
[0048] The following examples are offered to illustrate various aspects of the invention. However, the examples are not intended to limit or define the scope of the invention in any manner.
Example: 1: Determination of the ultimate anaerobic biodegradation under high-solids anaerobic-digestion conditions by analyzing the released biogas
[0049] The PET bottle manufactured as per the present invention is subjected to test to determine the ultimate anaerobic biodegradability based on organic compounds under high-solids anaerobic-digestion conditions.
[0050] The test is designed to be an optimized simulation of an intensive anaerobic digestion process and thus determines the ultimate biodegradability of a test material under high-solids anaerobic digestion conditions. The methanogenic inoculum is derived from anaerobic digesters operating on pre-treated household waste, preferably only the organic fraction.
[0051] The test includes three groups namely the inoculum, positive control and the test sample. In order to determine the anaerobic biodegradation, the inoculum is prepared by mixing 1000 kg of wet mass with amount of test material or reference material containing 15 g to 20 g of volatile solids for each test vessel. The test material mixed with the inoculum is introduced into a static digestion vessel where it is intensively digested under optimum temperature and moisture conditions for a test period of 15 days or longer until a plateau in the biodegradation has been reached. Analytical grade cellulose is used as positive control. The incubation reaction shall be in the dark or in diffused light in an enclosure that is maintained at a constant temperature of 52°C ± 2°C with a pH in the range between 7.5 to 8.5. The biogas generated as result of biodegradation is clearly observed in the form of bubbles.
[0052] The evolved biogas volume is collected and tested for production of ultimate biodegradation products such as methane and carbon dioxide.
[0053] Figure 3 illustrates the comparative account of cumulative biogas in inoculum, positive control and the test sample. The biogas i.e., methane and carbon dioxide evolved during the reaction is continuously monitored and measured at regular intervals in test, inoculum and positive control to determine the cumulative biogas production. The percentage biodegradation is given by the ratio of the amount of biogas evolved from the test material to the maximum theoretical amount of biogas that is produced from the test material. The maximum theoretical amount of biogas produced is calculated from the measured total organic carbon (TOC). This percentage biodegradation does not include the amount of carbon converted to new cell biomass, which is not metabolized in turn to biogas during the course of the test.
[0054] The results indicated that the increase in the biogas volume confirms the trend of conversion of carbon content in test sample to gaseous phase indicating increased rate of test sample biodegradation over the test period of 90 days with a biodegradation rate of 11.12 %. This interprets that the sample is continued to be exposed under anaerobic digestion conditions, the rate of biodegradation is accelerated, and the sample liberates biogas which is measured.
[0055] Further, the eco-toxicity of the residues from biodegradation is in conformance with OECD 208:2016 standard specifying seedling emergence and seedling growth test.
Example 2: Analysis of effects of residue from PET bottle anaerobic biodegradation on seedling emergence and growth
[0056] The PET bottle of the present invention is analyzed for eco-toxicity by using the residues from PET bottle anaerobic biodegradation. In order to analyse the effects of residues from PET bottle anaerobic biodegradation, the 180 mL PET bottle is subjected to biodegradation under high solid anaerobic digestion conditions for incubation period of 90 days as per ISO 15985:2014 test method. The resultant residue digested sludge and PET bottle biodegradation product and biomass in the reactor is collected and used as Test Substance.
[0057] The effect of residue obtained from anaerobic biodegradation of the PET bottle is analyzed on seed germination, root growth, shoot growth and biomass of Sorghum species. The seed germination rate is analyzed by placing ten seeds of Sorghum species of uniform size in a Petri dish with five test concentrations of 1 g/kg, 3 g/kg, 9 g/kg, 27 g/kg and 81 g/kg and a control in the dark environment in triplicates. After 4 days, the seeds are removed to determine the germination rate and effect of test substance in accordance with the standard germination testing method of the International Seed Testing Association.
[0058] Further, in order to analyze the toxicity on root growth, shoot growth and biomass, the plants are grown in small plastic pots. The moisture in the soil is maintained continuously. The seeds are set under 12/12 hours light and dark cycle and temperature of 300C during the day and 220C during the night with an average relative humidity of 75%. The seedlings are allowed to grow for 2 weeks and are harvested after two weeks to measure the shoot growth, root growth and biomass.
[0059] Figure 4 tabulates the effect of residue of PET bottle on seed germination, root length, shoot length and biomass of Sorghum species. The results indicated that the mean survival of emerged control seedlings is 90% for the duration. The seeds are properly germinated in different test concentrations without any difference in rate compared to the control. In addition, the seedlings also did not exhibit any phytotoxic effects such as chlorosis, necrosis, welting, leaf and stem deformation with respect to the control. The residue of the PET bottle did not induce any toxic effects on root and shoot length and on the biomass of Sorghum species with respect to the control. The results interpret that the residue obtained from anaerobic biodegradation of PET bottles under high solid digestion conditions for 90 days did not show toxic effect on seed emergence and growth of Sorghum species plants thus proving its safety anticipated environmental exposures.
[0060] The packaging material made with biodegradable additive also confirms to the overall migration and aldehyde migration limits as per prevailing food safety standards. The migration studies are carried out with simulation of 40% v/v ethanol at 400C for 10 days. The results indicated the value of 10.0 mg/dm2 interpreting the compliance with food safety and standards.
[0061] The PET bottle manufactured with a biodegradation additive as per the composition and process described in the invention is safe to be used for the packaging of alcoholic beverages, wherein the alcohol content could be up to 42.8% v/v. The strain at break and the compression strength of the packaging material are comparable between the packaging component made by blending biodegradation additive and the conventional PET packaging component. Therefore, the invention provides an environmentally safe, biodegradable, and a cost-effective alternative compared to the existing packaging materials for alcoholic beverages.
,CLAIMS:We Claim,
1. A composition of biodegradable Polyethylene Terephthalate (PET) container or a bottle, the composition comprising:
a. masterbatch at a concentration in the range between 0% and 3%.
b. a biodegradation additive at a concentration in the range between 1% and 2%; and
c. a PET resin at a concentration in the range between 95% and 99%.
Wherein the masterbatch imparts bright, durable and consistent color to the PET resin.

2. The composition as claimed in claim 1, wherein the masterbatch used is as per food safety regulations for PET packaging and is Renol 3136F but not limited to the specified grade.

3. The composition as claimed in claim 1, wherein the biodegradation additive is a polyester copolymer with one or more additive ingredients comprising scissoring agent, organic chemoattractant or organic polymer.

4. The composition as claimed in claim 1, wherein the PET container or bottle is safe, biodegradable and cost-effective packaging material for alcoholic beverage.

5. The composition as claimed in claim 1, wherein the biodegradable additive is homogeneously distributed throughout the packaging material to enable biodegradability.

6. A process for the preparation of the biodegradable PET container or a bottle, the process comprises the steps of:

a. blending 95% to 99% of PET resin with 0% to 3% of masterbatch and 1% and 2% biodegradation additive (201);
b. feeding the blended mixture into a screw barrel extruder for melting the mixture and to obtain a homogenous mix of polymers (202);
c. pushing the homogenous mix of the molten polymer through hot runners into injection molds (203);
d. using the injection molding technology to produce a preform from the molten polymer (204);
e. conditioning the bottles released from the molds (205);
f. reheating the preforms to glass transition temperature in the conditioning chamber (206);
g. introducing a stretch rod to the conditioned performs placed inside the stretch and blowing mold to stretch the preform longitudinally (207); and
h. blowing the preform using two level air pressure circumferentially to obtain a fully shaped container or a bottle (208).

7. The process as claimed in claim 6, wherein the biodegradation additive is homogeneously distributed throughout the resulting packaging component.