AND APPLICATION THEREOF”

TECHNICAL FIELD

The present disclosure generally relates to the field of polymer science and pertains to a preform precursor composition. Said polymer preform composition comprises polymer and graphene and is characterized by the presence of the graphene at a concentration ranging from about lppm to 20ppm. The graphene in said composition acts as a reheat additive. While graphene does not negatively impact the transparency or colouration of the products so formed, it also allows increased efficiency of product formation. In addition, graphene also imparts enhanced antimicrobial properties to the products so formed. The disclosure also provides a process that allows graphene to be incorporated into the preform precursor composition, enabling application of graphene as a reheat additive. Said composition of the present disclosure finds application in the preparation of preforms for the manufacture of final products such as plastic containers for example, plastic bottles or directly in the preparation of the final products. Said products are prepared from the composition of the present invention by methods such as blow moulding. Accordingly, the present disclosure further provides a process for producing products such as plastic containers from the preform precursor composition.

BACKGROUND OF THE DISCLOSURE Polymer formulations of polyethylene terephthalate (PET) and polypropylene (PP) are commercially established packaging materials. PET bottles used for mineral water and beverage packaging are fabricated using two-step injection stretch blow moulding process. In this process, the polymer preforms generated during the first step are heated up to 105°C and then subjected to stretching / blowing. Preforms are heated by near infrared quartz lamps having wavelength 780 ~ 1800 nm to achieve desired blowing temperature. In other words, the‘preforms’ made from injection blow moulding is subsequently stretch blow moulded to obtain the final bottle shape . As PET and PP have a poor ability to absorb infrared radiation, thereby rendering preform heating as a rate limiting step in bottle manufacturing, as an accepted practice, to facilitate infrared absorption, various reheat additives such as carbon black, iron, red iron oxide, elemental antimony and other black/gray body absorbing compounds are used. The reheat additives used to improve reheat performance are homogeneously dispersed inert materials that exhibit strong absorbance of radiant energy at wavelengths emitted by the infrared lamps (between 500 and 2000 nm). The materials used for reheat applications in PET have also been employed in prior literature which includes carbon black (U.S. Pat. No. 4,408,004), graphite (U.S. Pat No. 5,925,710 and 6,034, 167), black iron oxides (U.S. Pat No. 6,022,920) and red iron oxides (U.S. Pat No. 4,420,581 and U.S. Pat No. 4,250,078). Further, U.S. Pat. No. 4,481,314, discloses the use of certain anthraquinone type dyes for the purposes of improving reheat rates. However, these dyes have substantial absorbance in the visible spectrum, resulting in coloration of the polymer. In addition, their relatively low molar extinction coefficients (e) (in the range of 20,000) require the use of relatively large amounts of the dye (20-100 ppm) to the polymer. A more darkly coloured absorbing compound generally improves heat-up characteristics better than a relatively lighter absorbing compound. However, the more darkly coloured absorbing compounds can only be added in very small quantities due to the larger negative impact on L* (CIE). For example, when carbon black, a very dark black compound, is added to PET in concentrations greater than a few ppm, bottles blown from that PET are gray, dull in appearance, and are perceived to be less attractive than perfectly colourless ones. Reduced antimony metal, which is toxic can be present in PET in concentrations of up to about 50 ppm without having an excessive negative impact on L* because reduced antimony is a gray metal which is much lighter in colour than true black body absorbers like carbon black. However, the US Environmental Protection Agency (USEPA) limits the antimony level in drinking water to a maximum contaminant level (MCL) of 6 ppb. Experimentally, it has been established that, leaching results in nearly double the amount of released antimony over a period of three months.

It is therefore necessary to design an infrared absorber material which can be added to a thermoplastic polymer to improve the reheat rate and transparency (L*) without affecting other characteristics of preforms/bottles such as haze and mechanical properties (burst strength) to meet the benchmark requirements. It is also desired that the introduction of such an additive allows infrared absorption at low loading levels without hampering the transparency and aesthetic appeal of the finished product.

SUMMARY OF THE DISCLOSURE

Accordingly, to address the problems of prior art, the present invention provides a preform precursor composition comprising polymer and graphene at a concentration ranging from about lppm to about 20ppm. In an embodiment, the polymer in said preform precursor is selected from a group comprising polyethylene terephthalate (PET), polypropylene (PP), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene terephthalate glycol (PETG), polyethylene naphthalate (PEN) and polyethylene furandicarboxylate or any combination thereof. In a further embodiment, the graphene is single layered or multi-layered; wherein the multi-layered graphene comprises about 2 layers to about 50 layers.

In the above described preform precursor composition of the present disclosure, the graphene acts as a reheat additive. In a non-limiting embodiment, the graphene reduces reheat time of the preform precursor composition by at least about 30% as compared to commercially available reheat additives. In another non-limiting embodiment, the graphene reduces reheat time by at least about 80% as compared to the composition devoid of the graphene. The present disclosure further provides a process for preparing the preform precursor composition as described above, said process comprising steps of: i . condensation polymerization of the polymer with the graphene to obtain a graphene incorporated polymer resin;

ii. solid state polymerization of the graphene incorporated polymer resin to obtain the preform precursor composition as claimed in claim 1.

Additionally, the present disclosure provides a process for preparing a preform for plastic containers or a plastic container, said process comprising steps of subjecting the preform precursor composition to injection blow moulding to obtain the preform; and optionally subjecting the preform to stretch blow moulding to obtain the plastic container.

Further provided in the present disclosure is the use of the preform precursor composition for preparing a preform for plastic containers or a plastic container.

Furthermore, the present disclosure also relates to a preform for plastic containers or a plastic container prepared from the preform precursor composition. In an embodiment, the plastic container is a plastic bottle.

DETAILED DESCRIPTION OF THE DISCLOSURE

In view of the drawbacks associated, and to remedy the need created by the art available in the field of thermoplastic polymers, the present disclosure aims to provide preform precursor composition comprising polymer and graphene, wherein the graphene acts as a reheat additive for the polymers. Said preform precursor composition typically finds application in the production of preforms for products such as bottles or directly in the production of said products.

However, before describing the product and the process of the present disclosure in greater detail, it is important to take note of the common terms and phrases that are employed throughout the instant disclosure for better understanding of the technology provided herein. Throughout the present disclosure, the term‘graphene’ is intended to convey the conventional meaning of the term known to a person skilled in the art and intends to cover‘graphene’ as an allotrope of carbon consisting of a single or multiple layers of carbon atoms. Thus, the graphene employed in the present disclosure maybe a single layered or multi layered graphene.

The term/phrase‘preform precursor composition’ as used throughout the present disclosure refers to the composition of the present disclosure comprising a combination of polymer and graphene. The composition is fit for partitioning into preforms of required size that may further be moulded into products of interest. Thus, the composition acts as a precursor composition to obtain respective preforms which may be further processed to obtain a final product such as plastic containers. Reference to ‘the composition’ or ‘composition of the present disclosure’ throughout the present disclosure, unless otherwise defined, alludes to the‘preform precursor composition’, as used interchangeably for ease of reference. Throughout the present disclosure, the term‘graphene incorporated polymer resin’ refers to the intermediate formed at the end of the first step (i.e. condensation polymerization) in the process for preparing the preform precursor composition. Said graphene incorporated polymer resin is further subjected to solid state polymerization to obtain the preform precursor composition of the present disclosure.

Throughout the present disclosure, the term‘blow moulding’ or variations thereof, is intended to convey the ordinary conventional meaning of the term known to a person skilled in the art and intends to cover a specific manufacturing process by which hollow plastic parts are formed and can be joined together. In the present disclosure, the term is intended to cover all types of blow mouldings known to a person skilled in the art, including extrusion blow moulding, injection blow moulding, and injection stretch blow moulding.

Throughout the present disclosure, the term‘L*’‘a*’ or‘b*’ is intended to convey the ordinary conventional meaning of the term known to a person skilled in the art and intends to cover a colour space defined by the International Commission on Illumination (CIE) and is used to express colour as numerical values, where L* is for the lightness and a* and b* for the green-red and blue-yellow colour components. Throughout the present disclosure, the term‘reheat additive’ is intended to convey the ordinary conventional meaning of the term known to a person skilled in the art and intends to cover an additive that is incorporated in a polymer and that improves heat absorption and reduces processing time and energy required for blow moulding of the polymer. Reference to ‘commercially available additive’ or ‘commercial additive’ throughout the present disclosure refers to commonly available titanium-based additives that may be procured commercially.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The use of the expression“at least” or“at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. Throughout this specification, the word “comprise”, or variations such as

“comprises” or“comprising” wherever used, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. Further, use of the term‘about’ before values defined in the present disclosure envisages values of about ±10%.

Accordingly, to reiterate, the present disclosure relates to a preform precursor composition comprising polymer(s) and graphene, wherein the graphene is present at a concentration ranging lppm to 20ppm. Said preform precursor composition typically finds application in the production of preforms for final products or directly in the production of final products such as plastic containers, wherein said products are obtained by methods such as but not limited to by injection blow moulding and stretch blow moulding. Examples of such plastic containers include but are not limited to plastic bottles.

In an embodiment, the polymer in the composition is selected from a group comprising polyethylene terephthalate (PET), polypropylene (PP), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene terephthalate glycol (PETG), polyethylene naphthalate (PEN) and polyethylene furandicarboxylate, lactic acid or any combination thereof.

Said polymer(s) comprised in the composition of the present disclosure is typically formed from precursor selected from a group comprising ethylene glycol, terephthalic acid, propylene, 1,4-butane diol, Dimethyl terephthalate, 1,3-propane diol, other diols, naphthalene-2, 6-dicarboxylic acid, and ftiran dicarboxylic acid and poly lactic acid or any combination thereof.

In a non-limiting embodiment, the concentration of graphene in the composition of the present disclosure is about lppm, about 1.5ppm, about 2ppm, about 2.5ppm, about 3ppm, about 3.5ppm, about 4ppm, about 4.5ppm, about 5ppm, about 5.5ppm, about 6ppm, about 6.5ppm, about 7ppm, about 7.5ppm, about 8ppm, about 8.5ppm, about 9ppm, about 9.5ppm, about lOppm, about 10.5ppm, about 10.5ppm, about l lppm, about 11.5ppm, about 12ppm, about 12.5ppm, about 13ppm, about 13.5ppm, about 14ppm, about 14.5ppm, about 15ppm, about 15.5ppm, about 16ppm, about 16.5ppm, about 17ppm, about 17.5ppm, about 18ppm, about 18.5ppm, about 19ppm, about 19.5ppm, or about 20ppm.

Graphene at the aforementioned concentration/loading levels results in an improved infrared absorption capacity of the polymer preforms formed from the composition, during the stretch blow moulding process that the preform formed from the precursor is subjected to for obtaining the final product. Graphene in said composition of the present disclosure acts as a reheat additive. The graphene improves the infrared (IR) absorption capacity of the constituting polymer, such as PET and PP or a combination of both, and allows for corresponding products, such as preforms or bottles, to be produced at a higher rate and with lower energy consumption. This is a result of the intrinsic characteristics of graphene, such as semi metallic band structure, platelet morphology, and presence of large number of functional groups that quickens IR absorption, in combination with controlled synthesis protocols. Further, the graphene also imparts antimicrobial properties to the products formed from the composition. Products of interest include but are not limited to plastic containers such as preforms for plastic bottles or plastic bottles. This in-tum results in taste retention of the content packaged in said containers due to reduced microbial degradation inside the said preforms or bottles.

Thus, in exemplary embodiments, presence of graphene in the preform precursor composition during blow moulding process helps in (a) increasing the production rate of corresponding products such as preforms or bottles, (b) lowering the energy consumption (reduced production cost) without affecting the colour properties of the preform/bottles so formed, and (c) enhancing/maintaining the quality/flavour of the packaged content, inside the preform/bottle.

Moreover, the graphene in the composition helps in improving the transparency (L*, a*, b*) and other optical (haze) and mechanical properties in the preforms for plastic containers or the plastic containers prepared from the composition, due to the few layer/single layer nanostructure of the graphene employed.

In a non-limiting embodiment, graphene in the composition of the present disclosure reduces haze of the plastic containers prepared therefrom by at least about 10%, as compared to plastic containers prepared from compositions comprising commercially available reheat additives. In another non-limiting embodiment, graphene in the composition of the present disclosure reduces reheat time of the preform precursor composition by least about 30% as compared to commercially available reheat additives.

In a further non-limiting embodiment, graphene in the composition of the present disclosure reduces reheat time by at least about 80% as compared to the composition devoid of the graphene.

In an embodiment, the aforementioned properties of the preform precursor composition of the present disclosure are particularly achieved due to the specific concentration of graphene employed in the composition.

Moreover, the number of layers of graphene also has a role to play in the achieving the aforementioned properties. In an exemplary embodiment, the graphene employed in the composition is single layered or multi-layered graphene with a limitation of few layers of graphene. In an embodiment, when the graphene is multi layered graphene, the number of layers of graphene ranges from about 2 to about 50 layers.

In another embodiment, when the graphene is multi-layered graphene, the number of layers of graphene is about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, about 20, about 21, about 22, about 23, about 24, about 25, about 26, about 27, about 28, about 29, about 30, about 31, about 32, about 33, about 34, about 35, about 36, about 37, about 38, about 39, about 40, about 41, about 42, about 43, about 44, about 45, about 46, about 47, about 48, about 49 or about 50.

In a preferred embodiment, when the graphene is multi-layered graphene, the number of layers of graphene ranges from about 15 to about 25.

In an exemplary embodiment, when the graphene is multi-layered graphene, the number of layers of graphene ranges from about 1 to about 15, more preferably from about 1 to about 3. In the present disclosure, graphene may be employed in different forms, including but not limited to graphene nanoplatelets, and graphene oxide or a combination of any of said forms.

In a further embodiment, particle size of the graphene employed in the composition of the present disclosure ranges from about 0.001 pm to about 500pm. Preferably, the particle size of the graphene is less than about 50pm. More preferably, the particle size of the graphene is less than 20pm.

In an exemplary embodiment, about 70% of the population of the graphene employed in the composition has particle size ranging from about 1pm to about 5 pm; about 20% of the population of the graphene has particle size ranging from about 0.5pm to about 1pm, and about 10% of the population of the graphene has particle size ranging from about 5 pm to about 50pm.

As mentioned, inclusion of graphene comprising the number of layers defined above in the preform precursor composition, at the above defined concentration and particle size results in higher production rate (faster moulding), and superior transparency of the preforms/final product prepared therefrom, since said products retain colour properties such as the L*, a*, b* and haze of the polymer. Further, the preforms or the bottles prepared from the composition of the present disclosure show improved antimicrobial behaviour owing to the favourable oxidative processes along the basal planes and sheet edges of the graphene structures that enable lower toxicity, and quality retention of the packaged food products contained in the preforms/bottles.

The present disclosure further provides a process for preparing the composition defined above, wherein the process allows efficient incorporation of the graphene into the polymer matrix.

The process of the present disclosure provides for incorporation of graphene into the polymer matrix through a polymerization-based process that results in a polymer based preform precursor exhibiting fast reheat characteristics. The graphene so employed in the said process is in slurry form, particularly as a stable dispersion of graphene in an organic solvent such as but not limited to monoethylene glycol.

In non-limiting embodiments, the polymerization process is a combination of condensation polymerization and solid-state polymerization processes. Particularly, the present disclosure provides a process for preparing the preform precursor composition as defined above, said process comprising steps of:

i) condensation polymerization of the polymer with the graphene to obtain a graphene incorporated polymer resin;

ii) solid state polymerization of the graphene incorporated polymer resin to obtain the preform precursor composition.

In an embodiment, the condensation polymerization of the polymer with the graphene to obtain a graphene incorporated polymer resin comprises steps of: a) mixing a polymer precursor with an organic solvent to form a slurry; b) adding a catalyst and a contaminant suppressant to the slurry;

c) esterifying the slurry of step (b) to obtain an esterified mixture;

d) adding a slurry of graphene in an organic solvent to the esterified mixture;

e) adding weak acid(s) and colour toner(s) to the mixture obtained at the end of step (d);

f) subjecting the mixture obtained at the end of step (e) to condensation polymerization to prepare the graphene incorporated polymer resin.

In an embodiment of the present disclosure, the polymer precursor is selected from a group comprising ethylene glycol, terephthalic acid, propylene, 1,4-butane diol, Dimethyl terephthalate, 1,3-propane diol, other diols, naphthalene-2, 6-dicarboxylic acid, fiiran dicarboxylic acid and lactic acid or any combination thereof.

In another embodiment, the organic solvent employed to form the slurry of the polymer precursor is selected from a group comprising mono ethylene glycol (MEG), propylene glycol, butylene glycol, and propylene glycol or any combination thereof.

The condensation polymerization process begins by mixing the polymer precursor with the organic solvent (diol) at a specific ratio to arrive at a slurry. In an embodiment, the ratio of the polymer precursor to the organic solvent ranges from about 1: 1.8 to about 1:2.2.

Optionally, isophthalic acid (IP A) or diethylene glycol (DEG) both are also added to the slurry of the polymer precursor. In an embodiment, the IPA is added at a concentration ranging from about 0wt% to about 6wt% and, the DEG is added at a concentration ranging from about 0wt% to about 3wt% to the slurry of the polymer precursor.

In a non-limiting embodiment of the present disclosure, the catalyst is added in an amount ranging from about 280ppm to about 300ppm.

In an exemplary embodiment of the present disclosure, the catalyst employed is antimony in the form of antimony trioxide, where the antimony is provided at a concentration of about 290 ppm.

Further, a contaminant suppressant is added to the same slurry, wherein the contaminant suppressant is selected from a group comprising sodium hydroxide (NaOH) and lithium acetate dehydrate or any combination thereof.

In an embodiment of the present disclosure, the contaminant is diethylene glycol (DEG) and the suppressant employed to prevent its formation is NaOH, wherein the sodium is provided at a concentration of about 25ppm. Further, lithium acetate dehydrate may also be employed for the same purposes.

The above steps of addition of reagents to the polymer slurry is followed by carrying out esterification of the reactants in the slurry to obtain an esterified mixture under appropriate conditions of temperature and pressure. In a non-limiting embodiment, the esterification is carried out at a temperature ranging from about about 240°C to about 292°C and at a pressure ranging from about 1 bar to about 5 bar.

In an exemplary embodiment, the esterification reaction is carried out at a temperature of about 260°C under about 2kg/cm ² (g) pressure. Said step is conducted till esterification of reagents in the afore-defined slurry is achieved, to yield an esterified mixture.

Once the esterification is complete, graphene slurry, which is separately prepared by dispersing graphene in an organic solvent, is then added to the esterified mixture.

In an exemplary embodiment, the graphene slurry is prepared by high shear mixing or by methods such as sonication, hydrodynamic cavitation, and ball milling. Said graphene slurry is prepared in an organic solvent. Said mixing step is crucial to achieve efficient dispersion of graphene in the slurry to avoid defects and loss of transparency in the final product.

In an embodiment, the organic solvent for preparing the graphene slurry is selected from a group comprising mono ethylene glycol (MEG), propylene glycol, butylene glycol, and propylene glycol or any combination thereof.

For example, the graphene slurry is prepared in MEG, a monomer used for polymerization to make PET. Similarly, propylene glycol may be employed as solvent to create PTT, and butylene glycol may be employed as solvent to create PBT polymer.

In a non-limiting embodiment, the graphene slurry is added to the esterified mixture at a concentration ranging from about 0.1% to about 5%.

Addition of graphene slurry to the esterified mixture is followed by addition of a weak acid(s) and colour toner(s) to the mixture. In an embodiment, weak acid(s) such as but not limited to phosphoric acid may be employed. In another embodiment, the colour toner(s) is selected from a group comprising red toner and blue toner or any combination thereof.

In an exemplary embodiment, the weak acid is phosphoric acid and the phosphoric acid is added such that the phosphorus is provided at a concentration ranging from about 5ppm to about 50 ppm. In another exemplary embodiment, the colour toners are red toner and blue toner, such that the red toner is provided at a concentration of about 2 ppm and whereas the blue toner is provided at a concentration of about 7 ppm.

The reaction is thereafter subjected to condensation polymerization under fine vacuum at a specific temperature.

In a non-limiting embodiment, the condensation polymerization is carried out under fine vacuum of less than about 0.5 torr and at a temperature ranging from about 275°C to about 310°C. In an exemplary embodiment, the condensation polymerization is carried out under fine vacuum of less than about 0.5 torr and at a temperature of about 290°C.

In a further embodiment, the condensation polymerization is carried out till the graphene incorporated polymer resin obtained has a viscosity ranging from about 0.54 dl/g to about 0.63 dl/g.

In an embodiment, after achieving desired viscosity, the polymerized material i.e. the graphene incorporated polymer resin is taken out. The polymerized material resulting from the condensation polymerization process is a graphene incorporated polymer resin. Said graphene incorporated polymer resin is preferably taken out as a strand under water and converted into chips using cutter after completion of the condensation polymerization.

The condensation polymerization process as described above is followed by solid state polymerization of the graphene incorporated polymer resin achieved at the end of step (i) of the process of the present disclosure i.e. at the end of step (f) of the condensation polymerization process, at a specific temperature under nitrogen atmosphere. In an embodiment, said resin subjected to the solid-state polymerization is in the form of polymerized chips. Sampling is carried out intermittently during the solid-state polymerization to check intrinsic viscosity (IV) and batch was terminated after achieving a target IV. In a non-limiting embodiment, the solid-state polymerization of the graphene incorporated polymer resin is carried out at a temperature ranging from about 210°C to about 230°C.

In an exemplary embodiment, the solid-state polymerization is carried out at a temperature of about 217°C. Said solid-state polymerization is carried out till the target viscosity of the polymerized product is achieved.

In another non-limiting embodiment, the target viscosity at the end of the solid- state polymerization ranges from about 0.8dl/g to about 0.9dl/g, such as 0.84 ± 0.02 dl/g.

The preform precursor composition of the present disclosure is achieved at the end of the solid-state polymerization process i.e. at the end of step (ii) of the process of the present disclosure.

Optionally, for preform precursor compositions prepared from ester-based polymers, the preform precursor composition is subjected to drying before subjecting the further processing to obtain the precursor for plastic containers or plastic containers directly. In an exemplary embodiment, drying of the preform precursor is performed at about 100°C to about 200°C for about 1 hour to about 4 hours

In an exemplary embodiment, in a typical process, the graphene incorporated polymer resin is injection moulded into preforms of required size for, wherein said preforms may be further processed to prepare plastic containers. In other words, after the polymerization process (i.e. condensation polymerization and solid-state polymerization) is complete, the preform precursor composition is converted into preforms using injection blow moulding. The‘preforms’ made from injection blow moulding are subsequently stretch blow moulded to obtain the final container shape. The stretch blow moulding stretches the preform in axes by mechanical device and in radial by compressed air when the preforms are under high elastic condition in a suitable mould. The preforms are subjected to stretch blow moulding process by heating the preforms up to a specific temperature and then subjected to stretching / blowing. Preforms are heated by near infrared quartz lamps having specific wavelength to achieve desired blowing temperature. The graphene nanoplatelets in the resin allow for enhanced IR absorption to efficiently result in the corresponding product, such as a bottle.

Thus, while the present disclosure primarily relates to a preform precursor composition comprising polymer and graphene, fit for application in obtaining preforms for the preparation of final products such as plastic containers or directly in the preparation of said final products, the present disclosure also provides a process for incorporation of the said graphene in a polymer composition.

In an alternate embodiment, for polymers such as polypropylene (PP), the polymer is melt mixed with a defined amount of graphene to create PP-Graphene masterbatch. Said master batch is then added to another batch of PP and processed into preforms by injection moulding of the graphene incorporated PP. As mentioned above, once the graphene incorporated polymer based preform precursor composition is prepared, preforms are made and subjected to moulding process to obtain the final product, such as plastic containers, for example plastic bottles. In non-limiting embodiments, the moulding process that the preforms prepared from the composition of the present invention are subjected to is a stretch blow moulding process.

Accordingly, the present disclosure further provides a process for preparing a preform for a plastic container or a plastic container, said process comprising steps of subjecting the preform precursor composition of the present disclosure to injection blow moulding to obtain the preform; and optionally subjecting the preform to stretch blow moulding to obtain the plastic container.

Further, the present disclosure provides a method of using the composition for preparing a preform for plastic containers or a plastic container, said method comprising step of subjecting the above defined composition to injection moulding into the preform of required size, optionally followed by blow moulding the preforms into the plastic containers.

In an embodiment, the present disclosure relates to use of the preform precursor composition of the present disclosure for preparing the preform for plastic containers or a plastic container.

In an embodiment, said use comprises steps of subjecting the composition to injection blow moulding to obtain the preform; and optionally subjecting the preform to stretch blow moulding to obtain the plastic container.

In a non-limiting embodiment, the composition of the present disclosure reduces cycle time for blow moulding the preform formed from the preform precursor composition by at least about 10%.

In accordance with the intended application of the composition of the present disclosure as described above, the present disclosure further provides a preform for plastic containers or a plastic container prepared from said composition. In a non-limiting embodiment, plastic container as referred to in the above paragraphs includes containers such as but not limiting to plastic bottles and plastic boxes.

In an embodiment, the preform for plastic container has haze ranging from about 6 to about 12 and the plastic container has haze ranging from about 2.5 to about 3.5. In a non-limiting embodiment, haze of the plastic container is reduced by at least about 10% as compared to a plastic container prepared a composition comprising commercially available reheat additive. In another non-limiting embodiment, haze of the plastic container is reduced by at least about 5% as compared to a plastic container formed from a composition devoid of the graphene.

In a further non-limiting embodiment, antimicrobial activity of the plastic container is about 5% to about 15% higher than a plastic container prepared from a composition comprising commercially available reheat additive.

While the instant disclosure is susceptible to various modifications and alternative forms, specific aspects thereof have been shown by way of examples and drawings and are described in detail below. However, it should be understood that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and the scope of the invention as defined by the appended claims.

EXAMPLES

The present disclosure is further described with reference to the following examples, which are only illustrative in nature and should not be construed to limit the scope of the present disclosure in any manner.

Example 1

Preparation of the polymer composition of the present disclosure comprising graphene

Polymerization of PET resin by condensation polymerization process :

For preparing a batch size of about 55kg, about 47.3kg of purified terephthalic acid (PTA) and about 35.5kg of mono ethylene glycol (MEG) were mixed to prepare a slurry. The mole ratio was maintained at about 1 :2. Further, about 990gms of isophthalic acid (IP A) was also added in PTA-MEG slurry. Thereafter, antimony trioxide was added as a catalyst, in a manner so as to provide about 290ppm of antimony. During the condensation polymerization process, to prevent formation of contaminants, such as diethylene glycol (DEG), NaOH was added in a manner so as to provide about 25 ppm of sodium. The mixture was then subjected to esterification at about 260°C under about 2kg/cm ² (g) pressure.

Once esterification was completed, 0.275gm (5ppm) graphene was added in the form of 13.75gm of a 2% slurry in MEG. Subsequently, phosphoric acid was added to provide about 10 ppm of phosphorus along with red toner at about 2ppm and blue toner at about 7ppm. Condensation polymerization was then carried out under fine vacuum (< 0.5 torr) at about 290°C. After achieving desired viscosity, the material was taken out as a strand under water and converted into chips using cutter.

Solid-state polymerization:

Solid-state polymerization was carried out at about 217°C under nitrogen atmosphere. Sampling was carried out intermittently to check intrinsic viscosity (IV) and batch was terminated after achieving target IV of about 0.84 +/- 0.02 dl/g.

Preform and Stretch Blow Moulding using PET resin:

PET bottles were produced by stretch blow moulding process. Preforms were heated up to about 105°C and then subjected to stretching/blowing. Preforms were heated by near infrared quartz lamps having wavelength about 780nm-1800nm to achieve the desired blowing temperature.

Example 2:

The same procedure was followed for all the additives as in Example 1 for additives - graphene, carbon and commercial additives.

The reheat time for each of said additives at the same concentration (of 5ppm) was measured. The results are provided in Table 1.

The control PET was without any reheat additive. The time taken for control PET was normalized to zero and the rest of the additives performances was measured against it. The time taken for PET for blow moulding in presence of additive was less and hence has been represented as negative in the table. The more the negative number better the reheat value.

Table 1: Reheat time for different additives

From the above examples it is clear that the at the same additive concentration (5 ppm), graphene is much more efficient than the commercial additives as well as carbon.

Example 3:

Bottle moulding trail PET preform precursor with about 3.5ppm of graphene was prepared as per the procedure of Example 1. The preform precursor was dried at about 170°C for about 3.5 hrs before processing. Water grade preforms (weight - about 10 gm, about 22 mm three-star neck) were produced on 8 cavity injection moulding machine. Resin containing the graphene additive was processed at identical processing parameters (about 265°C-275°C) as standard grade resin. No change in cycle time was observed. Dispersion of graphene in the preform was uniform. Preform clarity with RHFC was same as that of standard resin. Blowing trial was carried out on single cavity machine. The bottle volume was about 500ml. Standard resin cycle time was about 4.5 seconds including blowing time of about 1.4 seconds. Blow air pressure was about 24 bar. With graphene, cycle time was reduced to about 4 seconds including blowing time of about 1.3 seconds. This indicates about 11% reduction in cycle time with graphene. At the same time, power settings (infrared heater firing) and thus energy requirements were also reduced for graphene resin.

Example 4:

Analysis of colour properties of the plastic bottle prepared with polymer composition comprising graphene as reheat additive Properties of the polymer were tested after polymerizing according to Example 1 Properties of the polymer (PET) in the presence of graphene 1, graphene 2, commercial reheat additive and control sample were measured. The results are provided in table 1.

Table 2: Comparative properties of preform precursor composition

The above data shows that the incorporation of graphene has no negative impact on the polymerization process and the output polymer based preform precursor composition. Example 5:

Comparison of various batches of graphene with control and commercial reheat additive, when employed as reheat additive in PET precursor composition (as per the procedure of Example 1) was conducted. The different batches of graphene comprised different number of layers of graphene. Observation of bottle properties based on the number of layers of graphene introduced into the preform precursor composition are provided in the table below.

Table 3: Bottle properties after blowing

As can be observed from the above table, graphene with about 80 % of more 1-3 layers shows the best properties of reheat values as well as lowest haze in the bottle. The reheat value increases with increase in the number of graphene layers.

Example 6:

Effect of concentration of graphene on bottle blowing properties

To analyse the effect of concentration of graphene on bottle blowing properties, different concentrations of graphene (about 5ppm, about 25ppm and about 50ppm) were employed in PET preform precursor compositions prepared as per Example 1, and each of said compositions were blown into bottles. Properties of the preforms and the bottles prepared therefrom were observed. The observations are given below. Table 4: Optical properties of preform

Table 5: Optical properties of bottle

It was observed that bottle with about 25 ppm graphene can be blown but with extremely difficulty. Long term production on high speed machine is very critical with such higher concentration of graphene.

Further, bottle with 50 ppm graphene is unable to blow and bottles were bursting due to extremely high infrared absorption characteristics which were making bottles very weak.

In totality, it was observed that the desired properties, in terms of visual properties such as transparency, as described in the embodiment, were achieved by concentration of graphene within the range defined in the present disclosure. At concentrations exceeding said concentration, properties such as haze of the final product were unfavourable.

Example 7:

Comparison of antimicrobial activity of PET bottle with and without graphene

Bottles prepared from compositions devoid of and comprising graphene as per the present invention were taken for comparison. The bottle without graphene is referred to as BotlO and the bottle containing graphene (about 3.5ppm) is referred to as Botl35.

Comparison of antibacterial activity showed an improvement in the antimicrobial activity of the bottle from about 86.7 % in the bottle lacking graphene to about 92.5 % in the bottle prepared from the composition of the present disclosure containing graphene, for Staphylococcus aureus.

Table 6: Analysis of antibacterial activity for S.aureus

Test Bacteria: Staphylococcus ATCC 6538

Further comparison of antibacterial activity showed an improvement in the antimicrobial activity of the bottle from about 82.3 % in the bottle lacking graphene to about 91.9% in the bottle prepared from the composition of the present disclosure containing graphene, for Escherichia coli. Table 7: Analysis of antibacterial activity for E.coli

Test Bacteria: Escherichia coli ATCC 8739

The composition of the present disclosure therefore lends to the preforms or plastic containers of the present invention higher efficiency of antimicrobial activity than compositions devoid of graphene.

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure . It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.