DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

1. TITLE OF THE INVENTION:
MULTI-LAYER HEAT-SHRINK FILM AND A PREPARATION METHOD THEREOF
2. APPLICANT:
GARWARE HI-TECH FILMS LIMITED, an Indian company of the address Garware House, 50-A, Swami Nityanand Marg, Western Express Highway, Vile Parle(east), Mumbai-400057, Maharashtra, India.

The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
[1] The present disclosure relates to a heat-shrink film. More specifically, the present disclosure relates to a multi-layer heat-shrink film and a preparation method thereof.
BACKGROUND OF INVENTION
[2] Product labels made of films are provided over packaged products (say, containers, bottles, boxes, etc.) to communicate product details as well as to enable the end consumer to identify said products. For example, dairy products, beverages, cosmetic formulations, pharmaceutical formulations, etc. have one or more product labels provided over the said packaged products.
[3] Conventionally, the films having high shrinkage property are preferred for preparing the product labels for these packaged products. To maintain high shrinkage property of these product labels, the conventional films are made amorphous.
[4] Although these product labels made from conventional films are easy to apply on products for the manufacturer and aesthetically pleasing to the consumer, they are a nightmare for the recyclers. Current recycling methods followed in majority of the material recovery facilities (MRF) subject the containers wrapped in these conventional films to a grinder to produce flakes thereof. These flakes are then subjected to high temperatures for further downstream processing. At this high temperature, the amorphous nature of the conventional films induces clumping among the flakes and adulterates the recycled materials.
[5] Therefore, there arises a need for a film which overcomes the aforementioned challenges associated with the conventional films.
SUMMARY OF INVENTION
[6] Particular embodiments of the present disclosure are described herein below with reference to the accompanying drawings, however, it is to be understood that the disclosed embodiments are mere examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.
[7] In an embodiment, the present disclosure relates to a multi-layer heat-shrink film including a first layer, a third layer, and a second layer disposed therebetween. The first layer is made of at least one first co-polyester resin and one or more additives. The third layer is made of at least one third co-polyester resin and one or more additives. The second layer is made of at least one second co-polyester resin and one or more additives. The at least one of the first layer and the third layer is relatively more crystalline than the second layer.
[8] In yet another embodiment, the present disclosure relates to a method to prepare a multi-layer heat-shrink film by preparing a first co-polyester resin with one or more dibasic acid components, one or more diol components, at least one nucleating agent, and at least one anti-blocking agent. Then, preparing a second co-polyester resin with one or more dibasic acid components, one or more diol components, at least one melt strengthening agent, and at least one anti-blocking agent. Then, preparing a third co-polyester resin with one or more dibasic acid components, one or more diol components, at least one nucleating agent, and at least one anti-blocking agent. Then, mixing the first co-polyester resin and the third co-polyester resin with at least one antioxidant to obtain a first mixture and a third mixture respectively. Then, mixing the second co-polyester resin with at least one antioxidant and at least one chain extender to obtain a second mixture. Then, extruding the first mixture, the second mixture and the third mixture using an extruder to obtain a first melt, a second melt and a third melt. Then, co-extruding the first melt, the second melt and the third melt to obtain a first layer, a second layer, and a third layer of a multi-layer heat-shrink film. Then, cooling the first melt, the second melt and the third melt to obtain the multi-layer heat-shrink film. Then, orienting the multi-layer heat-shrink film.
BRIEF DESCRIPTION OF DRAWINGS
[9] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the apportioned drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the disclosure is not limited to specific methods and instrumentality disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[10] Fig. 1 depicts a film 10 in accordance with an embodiment of the present disclosure.
[11] Fig. 2 depicts a method 200 to prepare the film 10 in accordance with an embodiment of the present disclosure.
[12] Fig. 3 depicts a method 300 to evaluate a clumping ratio of the film 10 and regenerating polyester-based chips in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE DRAWINGS
[13] Prior to describing the invention in detail, definitions of certain words or phrases used throughout this patent document will be defined: the terms "include" and "comprise", as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "coupled with" and "associated therewith", as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, or the like. Definitions of certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases.
[14] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.
[15] Although the method steps of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that the disclosed embodiments can encompass an order of method steps other than the particular, sequential order disclosed. For example, method steps described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed herein. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses.
[16] Furthermore, the described features, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments. These features and advantages of the embodiments will become more fully apparent from the following description and apportioned claims, or may be learned by the practice of embodiments as set forth hereinafter.
[17] The present disclosure relates a multi-layer heat-shrink film (hereinafter, film) and a preparation method thereof. The film may be used as a product label on a container of various consumer goods, for example, dairy products, beverages, cosmetic formulations, pharmaceutical formulations, or the like.
[18] The film of the present disclosure includes at least three layers co-extruded together. The layers of the film include a first layer, a second layer and a third layer. The second layer is disposed between the first layer and the third layer. Each of the layers of the film are made of at least one co-polyester resin having at least one dicarboxylic acid component copolymerized with at least one diol component. At least one of the first layer and the third layer may be relatively more crystalline than the second layer. In an embodiment, both the first layer and the third layer are relatively more crystalline than the second layer. The first layer and the third layer, being crystalline in nature, prevent clumping of the film (or a plurality of flakes thereof) at high temperatures. In an exemplary embodiment, the film has a clumping ratio of less than 1% when the clumping ratio is evaluated as per PET S-08 2022 guidelines published by The Association of Plastic Recyclers (APR). The second layer, being amorphous in nature, provides high shrinkage to the film. In an exemplary embodiment, the film has a shrinkage of 72% or more in a transverse direction (TD) when the film is kept in (or subjected to) water at 98 °C for 30 seconds. At least one of the first layer and the third layer may have a crystallization time (Tc½) ranging from 5 minutes to 30 minutes when measured at 160 °C using a differential scanning calorimeter (DSC). The said Tc½ corresponds to good (washable) ink receptive property for printing and reduced to no clumping property for excellent recycling.
[19] The film of the present disclosure may be at least partially transparent (or optically clear). In an embodiment, the film has a haze value of less than 10% when measured using Haze-gard Plus (HM001, Germany) as per method disclosed in ASTM D-4603. The film has an intrinsic viscosity ranging from 0.6dl/g to 1.2dl/g as per method disclosed in ASTM D-1003. The melting temperature (Tm) of the film ranges from 190 °C to 215 °C when measured using a differential scanning calorimeter (DSC).
[20] Additionally or optionally, at least one of the first layer or the third layer of the film is provided with an anti-static coating. The anti-static coating helps to eliminate static charge generated during handling of the film for example, during winding, slitting, etc.
[21] Now referring to the figures, Fig. 1 illustrates an exemplary multi-layer heat-shrink film 10 (hereinafter, film 10) of the present disclosure. The film 10 has a pre-defined thickness ‘x‘. The thickness ‘x’ of the film 10 ranges from 30 microns (µm) to 65 microns (µm). In an exemplary embodiment, the thickness of the film 10 is 45 microns (µm). The film 10 includes at least three layers. In an exemplary embodiment, as shown in Fig. 1, the film 10 includes a first layer 11, a second layer 13 and a third layer 15. The second layer 13 is disposed between the first layer 11 and the third layer 15. At least one of the first layer 11 and the third layer 15 may have a crystallization time (Tc½) ranging from 5 minutes to 30 minutes when measured at 160 °C using a differential scanning calorimeter (DSC). In an exemplary embodiment, about 10 mg of the first layer 11 (and the third layer 15, separately) (i.e., the sample) was placed in a sample port of DSC-7 (manufactured by Perkin Elmer). The DSC-7 was programmed to heat the sample from 50 °C to 300 °C at a rate of 20 °C/min and hold the sample at 300 °C for 2 minutes. Thereafter, the sample was quenched from 300 °C to 160 °C at a rate of 200 °C/min and held at 160 °C for 90 minutes. The Tc½ was derived from a peak (in minutes) obtained from the DSC-7. The said Tc½ corresponds to good ink receptive property for printing and for reduced clumping property for recycling.
[22] The melting temperature (Tm) of the first layer 11 (and the third layer 15) ranges from 190 °C to 215 °C when measured using a differential scanning calorimeter (DSC). In an exemplary embodiment, about 10 mg of the first layer 11 (and the third layer 15, separately) (i.e., the sample) was placed in a sample port of DSC-7 (manufactured by Perkin Elmer). The sample was heated from 50 °C to 300 °C at a rate of 20 °C/min and the DSC thermogram was obtained to determine the Tm.
[23] The intrinsic viscosity of the first layer 11 (and the third layer 15) ranges from 0.690 dl/g to 0.720 dl/g. In an exemplary embodiment, 125 mg of the first layer 11 (and the third layer 15, separately) (i.e., the sample) was added into 25 mL of solvent having 60 parts phenol and 40 parts tetrachloroethane. The sample was dissolved in the said solvent by heating for one hour at about 110 °C to obtain a solution. The intrinsic viscosity of the resultant solution was measured at 25 °C as per method disclosed in ASTM D-4603.
[24] The first layer 11 may have a pre-defined thickness relative to the thickness ‘x’ of the film 10. The thickness of the first layer 11 may range from 0.05 times to 0.15 times (or from 5% to 15% of) the thickness ‘x’ of the film 10. In an embodiment, the thickness of the first layer 11 is 0.1 times (or 10% of) the thickness ‘x’ of the film 10.
[25] The first layer 11 is made of at least one first co-polyester resin and one or more additives. The first co-polyester resin includes one or more dibasic acid components copolymerized with one or more diol components. The dibasic acid component(s) of the first co-polyester resin includes a pre-defined amount of at least one of terephthalic acid, isophthalic acid, adipic acid, orthophthalic acid, sebacic acid, naphthalene dicarboxylic acid, azalaic acid, succinic acid, or the like. In an exemplary embodiment, the first co-polyester resin includes a predefined amount of purified terephthalic acid (PTA) as the dibasic acid component.
[26] The diol component(s) of the first co-polyester resin includes a pre-defined amount of at least one of ethylene glycol, diethylene glycol, triethylene glycol, butane diol, neopentyl glycol (NPG), monoethylene glycol (MEG), cyclohexane dimethanol, 2-methyl-1,3-propanediol, or the like. The first co-polyester resin includes 80 mol% to 90 mol% MEG and 10 mol% to 20 mol% NPG as the diol components. In an exemplary embodiment, for every 100 mol% of PTA the first co-polyester resin includes 88 mol% MEG and 12 mol% NPG. In another exemplary embodiment, for every 100 mol% of PTA the first co-polyester resin includes 87 mol% MEG and 13 mol% NPG. In yet another exemplary embodiment, for every 100 mol% of PTA the first co-polyester resin includes 86 mol% MEG and 14 mol% NPG.
[27] The additives of the first layer 11 include at least one nucleating agent, at least one anti-blocking agent (or inert inorganic particles), and at least one antioxidant. The amount of the nucleating agent in the first layer 11 may range from 1500 ppm to 4500 ppm. The nucleating agent may be at least one of sodium benzoate, talc, etc. In an embodiment, the first layer 11 includes 2750 ppm sodium benzoate as the nucleating agent. The nucleating agent imparts crystallinity to a surface of the first layer 11 and makes crystalline domain on the surface of the first layer 11. The crystallinity of the first layer 11 prevents clumping of the film 10 at high temperatures during, for example, recycling of the film 10 and/or containers wrapped with the film 10.
[28] The amount of the anti-blocking agent in the first layer 11 may range from 100 ppm to 1000 ppm. The average particle size of the anti-blocking agent in the first layer 11 may range between 1 microns (µm) and 5 microns (µm). The anti-blocking agent may include at least one of silica, silicon dioxide, calcium carbonate, talc, kaolin, etc. In an embodiment, the first layer 11 includes 425 ppm of silica having particle size of 2 microns (µ) to 4 microns (µ) as the anti-blocking agent. The anti-blocking agent helps to improve frictional properties, handling properties, roll formation, etc. of the first layer 11.
[29] The amount of the antioxidant in the first layer 11 may range from 0.05% (w/w) to 0.2% (w/w). In an embodiment, the first layer 11 includes 0.1% (w/w) of Irganox-1010 (pentaerhthritol tetrakis(3-(3,5-di-tert-butly-4-hydroxyphenyl)propionate)) as the antioxidant. The antioxidant helps to reduce degradation of the first copolyester resin during co-extrusion of the film 10.
[30] The second layer 13 may have a pre-defined thickness relative to the thickness ‘x’ of the film 10. The thickness of the second layer 13 may range from 0.70 times to 0.90 times (or from 70% to 90% of) the thickness ‘x’ of the film 10. In an embodiment, the thickness of the second layer 13 is 0.8 times (or 80% of) the thickness ‘x’ of the film 10. The crystallization time (Tc ½) of the second layer 13 may not be observed (i.e., no peak is observed when measured using a differential scanning calorimeter (DSC)) due to its amorphous nature. The melting temperature (Tm) of the second layer 13 ranges from 190 °C to 215 °C when measured using a differential scanning calorimeter (DSC). In an exemplary embodiment, about 10 mg of the second layer 13 (i.e., the sample) was placed in a sample port of DSC-7 (manufactured by Perkin Elmer). The sample was heated from 50 °C to 300 °C at a rate of 20 °C/min and the DSC thermogram was obtained to determine the Tm.
[31] The intrinsic viscosity of the second layer 13 ranges from 0.690 dl/g to 0.720 dl/g. In an exemplary embodiment, 125 mg of the second layer 13 (i.e., the sample) was added into 25 mL of solvent having 60 parts phenol and 40 parts tetrachloroethane. The sample was dissolved in the said solvent by heating for one hour at about 110 °C to obtain a solution. The intrinsic viscosity of the resultant solution was measured at 25 °C as per method disclosed in ASTM D-4603.
[32] The second layer 13 is made of at least one second co-polyester resin and one or more additives. The second co-polyester resin includes one or more dibasic acid components copolymerized with one or more diol components, etc. The dibasic acid component(s) of the second co-polyester resin includes a pre-defined amount of at least one of terephthalic acid, isophthalic acid, adipic acid, orthophthalic acid, sebacic acid, naphthalene dicarboxylic acid, azalaic acid, succinic acid, or the like. In an exemplary embodiment, the second co-polyester resin includes a predefined amount of purified terephthalic acid (PTA) as the dibasic acid component.
[33] The diol component(s) of the second co-polyester resin includes a pre-defined amount of at least one of ethylene glycol, diethylene glycol (DEG), triethylene glycol, butane diol, neopentyl glycol (NPG), monoethylene glycol (MEG), cyclohexane dimethanol, 2-methyl-1,3-propanediol, or the like. The second co-polyester resin includes 80 mol% to 90 mol% MEG, 5 mol% to 20 mol% NPG, and 1 mol% to 10 mol% of DEG as diol components. In an exemplary embodiment, for every 100 mol% of PTA the second co-polyester resin includes 86 mol% MEG, 12 mol% NPG, and 2 mol% DEG. In another exemplary embodiment, for every 100 mol% of PTA the second co-polyester resin includes 85 mol% MEG, 13 mol% NPG, and 2 mol% DEG. In another exemplary embodiment, for every 100 mol% of PTA the second co-polyester resin includes 84 mol% MEG, 14 mol% NPG, and 2 mol% DEG. In another exemplary embodiment, for every 100 mol% of PTA the second co-polyester resin includes 83 mol% MEG, 15 mol% NPG, and 2 mol% DEG. In yet another exemplary embodiment, for every 100 mol% of PTA the second co-polyester resin includes 82 mol% MEG, 16 mol% NPG, and 2 mol% DEG. The addition of DEG into the second layer 13, makes the second layer 13 amorphous compared to the first layer 11 and the third layer 15.
[34] The additives of the second layer 13 include at least one melt strengthening agent, at least one anti-blocking agent (or inert inorganic particles), at least one antioxidant and at least one chain extender. The second layer 13 does not include any nucleating agent as an additive thereby retaining its amorphous nature and high shrinkage property.
[35] The amount of the melt strengthening agent in the second layer 13 may range from 100 ppm to 1000 ppm. The melt strengthening agent may be at least one of Joncryl ADR-4300, Joncryl ADR-4468, etc. In an exemplary embodiment, the second layer 13 includes 1000 ppm Joncryl ADR-4300 as the melt strengthening agent. In another exemplary embodiment, the second layer 13 includes 200 ppm Joncryl ADR-4468 as the melt strengthening agent. The melt strengthening agent helps to preserve the mechanical properties (for example, tensile strength) of the film 10 without impairing its shrinkage property.
[36] The amount of the anti-blocking agent in the second layer 13 may range from 100 ppm to 1000 ppm. The average particle size of the anti-blocking agent in the second layer 13 may range between 1 microns (µm) and 5 microns (µm). The anti-blocking agent may include at least one of silica, silicon dioxide, calcium carbonate, talc, kaolin, etc. In an embodiment, the first layer 11 includes 425 ppm of silica having particle size of 3.5 microns (µ) to 4.0 microns (µ) as the anti-blocking agent. The anti-blocking agent helps to improve frictional properties, handling properties, roll formation, etc. of the second layer 13.
[37] The amount of the antioxidant in the second layer 13 may range from 0.05% (w/w) to 0.2% (w/w). In an embodiment, the second layer 13 includes 0.1% (w/w) of Irganox-1010 (pentaerhthritol tetrakis(3-(3,5-di-tert-butly-4-hydroxyphenyl)propionate)) as the antioxidant. The antioxidant helps to reduce degradation of the second copolyester resin during co-extrusion of the film 10.
[38] The amount of the chain extender in the second layer 13 may range from 0.01% (w/w) to 0.10% (w/w). The chain extender may be at least one of Johncryl ADR-4300, Johncryl ADR-4468, any polymeric chain extender with low epoxy equivalent weight moieties, etc. In an exemplary embodiment, the second layer 13 includes 0.1% (w/w) of Johncryl ADR-4300 as the chain extender. In another exemplary embodiment, the second layer 13 includes 0.02% (w/w) of Joncryl ADR-4468 as the chain extender. The chain extender helps in retaining the mechanical properties (for example, tensile strength) of the second layer 13 during co-extrusion of the film 10.
[39] The melt strengthening agent, the antioxidant, and the chain extenders of the second layer 13 prevent hydrolytic degradation when the second co-polyester is processed to prepare the film 10.
[40] The third layer 15 may have a pre-defined thickness relative to the thickness ‘x’ of the film 10. The thickness of the third layer 15 may range from 0.05 times to 0.15 times (or from 5% to 15% of) the thickness ‘x’ of the film 10. In an embodiment, the thickness of the third layer 15 is 0.1 times (or 10% of) the thickness ‘x’ of the film 10.
[41] The third layer 15 is made of at least one third co-polyester resin and one or more additives. In an exemplary embodiment, the third co-polyester resin is same as the first co-polyester resin of the first layer 11. In yet another exemplary embodiment, the composition of the third layer 15 including the third copolyester resin and the additives are same as that of the first layer 11.
[42] Fig. 2 depicts an exemplary method 200 for preparing the film 10.
[43] In an exemplary embodiment, the film 10 obtained from the method 300 is rolled (or wound) to form a jumbo roll. Each jumbo roll includes a pre-defined length of the film 10 and a pre-defined width. Then this jumbo roll may be slitted, using slitting machines, in various sizes. The length and width of the slit rolls may vary, on the basis of requirements of the customer (or end-user). The direction of the width of the film 10 corresponds to the transverse direction (TD) of the film 10. The direction of the length of the film 10 corresponds to the machine direction (MD) of the film 10.
[44] The method 200 commences at step 201a by preparing a first co-polyester resin. In an exemplary embodiment, the first co-polyester resin is prepared by esterification and polymerization. The first co-polyester resin includes one or more dibasic acid component, one or more diol component, at least one nucleating agent, and at least one anti-blocking agent (or inert inorganic particles). The dibasic acid component of the first co-polyester resin includes a pre-defined amount of at least one of terephthalic acid, isophthalic acid, adipic acid, orthophthalic acid, sebacic acid, naphthalene dicarboxylic acid, azalaic acid, succinic acid, or the like. The diol component of the first co-polyester resin includes a pre-defined amount of at least one of ethylene glycol, diethylene glycol, triethylene glycol, butane diol, neopentyl glycol (NPG), monoethylene glycol (MEG), cyclohexane dimethanol, 2-methyl-1,3-propanediol, or the like. The nucleating agent may be at least one of sodium benzoate, talc, etc. The amount of the nucleating agent in the first co-polyester resin may range between 1500 ppm to 4500 ppm. The anti-blocking agent may include at least one of silica, silicon dioxide, calcium carbonate, talc, kaolin, etc. The amount of the anti-blocking agent in the first co-polyester may range between 100 ppm to 1000 ppm.
[45] In an exemplary embodiment, the first co-polyester resin is made of 100 mol% PTA (dibasic component), 88 mol% MEG (diol component), 12 mol% NPG (diol component), 2750 ppm sodium benzoate (nucleating agent), and 425 ppm silica (anti-blocking agent). In another exemplary embodiment, the first co-polyester resin is made of 100 mol% PTA (dibasic component), 87 mol% MEG (diol component), 13 mol% NPG (diol component), 2750 ppm sodium benzoate (nucleating agent), and 425 ppm silica (anti-blocking agent). In yet another exemplary embodiment, the first co-polyester resin is made of 100 mol% PTA (dibasic component), 86 mol% MEG (diol component), 14 mol% NPG (diol component), 2750 ppm sodium benzoate (nucleating agent), and 425 ppm silica (anti-blocking agent).
[46] In an exemplary embodiment, a stainless-steel reactor equipped with a mechanical stirrer, a fractionating column, a condenser and a heating system is charged with one or more dibasic acid component, and one or more diol component and esterified at 250-255 °C for 2-3 hours to obtain a monomer. The monomer obtained by esterification is transferred to a polymerization reactor along with a polymerization catalyst (0.045% (w/w) antimony trioxide) and a heat stabilizer (0.09% (w/w) triphenyl phosphate). The polymerization reaction is then conducted at 255-285 °C by gradually reducing a pressure from 730 mm of Hg to less than or equal to 1.0 mm of Hg to obtain the first co-polyester resin. The first co-polyester resin is casted in the form of strands by applying nitrogen pressure to the polymerization reactor and converted into granules by quenching in cold water.
[47] At step 201b, the second co-polyester resin is prepared. In an exemplary embodiment, the second co-polyester resin is prepared by esterification and polymerization. The second co-polyester resin includes one or more dibasic acid component, one or more diol component, at least one melt strengthening agent, and at least one anti-blocking agent (or inert inorganic particles). The dibasic acid component of the second co-polyester resin includes a pre-defined amount of at least one of terephthalic acid, isophthalic acid, adipic acid, orthophthalic acid, sebacic acid, naphthalene dicarboxylic acid, azalaic acid, succinic acid, or the like. The diol component of the first co-polyester resin includes a pre-defined amount of at least one of ethylene glycol, diethylene glycol, triethylene glycol, butane diol, neopentyl glycol (NPG), monoethylene glycol (MEG), cyclohexane dimethanol, 2-methyl-1,3-propanediol, or the like. The melt strengthening agent may be at least one of Joncryl ADR-4300, Joncryl ADR-4468, etc. The amount of the melt strengthening agent in the second co-polyester may range from 100 ppm to 1000 ppm. The anti-blocking agent may include at least one of silica, silicon dioxide, calcium carbonate, talc, kaolin, etc. The amount of the anti-blocking agent in the second co-polyester resin may range between 100 ppm to 1000 ppm.
[48] In an exemplary embodiment, the second co-polyester resin is made of 100 mol% PTA (dibasic component), 86 mol% MEG (diol component), 12 mol% NPG (diol component), 2 mol% DEG (diol component), 1000 ppm Joncryl ADR-4300 (melt strengthening agent), and 425 ppm silica (anti-blocking agent). In yet another exemplary embodiment, the second co-polyester resin is made of 100 mol% PTA (dibasic component), 82 mol% MEG (diol component), 16 mol% NPG (diol component), 2 mol% DEG (diol component), 200 ppm Joncryl ADR-4468 (melt strengthening agent), and 425 ppm silica (anti-blocking agent).
[49] In an exemplary embodiment, a stainless-steel reactor equipped with a mechanical stirrer, a fractionating column, a condenser and a heating system is charged with one or more dibasic acid component, and one or more diol component and esterified at 250-255 °C for 2-3 hours to obtain a monomer. The monomer obtained by esterification is transferred to a polymerization reactor along with a polymerization catalyst (0.045% (w/w) antimony trioxide) and a heat stabilizer (0.09% (w/w) triphenyl phosphate). The polymerization reaction is then conducted at 255-285 °C by gradually reducing a pressure from 730 mm of Hg to less than or equal to 1.0 mm of Hg to obtain the second co-polyester resin. The second co-polyester resin is casted in the form of strands by applying nitrogen pressure to the polymerization reactor and converted into granules by quenching in cold water.
[50] At step 201c a third co-polyester resin is prepared. In an exemplary embodiment, the third co-polyester resin is prepared by esterification and polymerization. The third co-polyester resin includes one or more dibasic acid component, one or more diol component, at least one nucleating agent, and at least one anti-blocking agent (or inert inorganic particles). The dibasic acid component of the first co-polyester resin includes a pre-defined amount of at least one of terephthalic acid, isophthalic acid, adipic acid, orthophthalic acid, sebacic acid, naphthalene dicarboxylic acid, azalaic acid, succinic acid, or the like. The diol component of the third co-polyester resin includes a pre-defined amount of at least one of ethylene glycol, diethylene glycol, triethylene glycol, butane diol, neopentyl glycol (NPG), monoethylene glycol (MEG), cyclohexane dimethanol, 2-methyl-1,3-propanediol, or the like. The nucleating agent may be at least one of sodium benzoate, talc, etc. The amount of the nucleating agent in the third co-polyester resin may range between 1500 ppm to 4500 ppm. The anti-blocking agent may include at least one of silica, silicon dioxide, calcium carbonate, talc, kaolin, etc. The amount of the anti-blocking agent in the first co-polyester may range between 100 ppm to 1000 ppm.
[51] In an exemplary embodiment, the third co-polyester resin is made of 100 mol% PTA (dibasic component), 88 mol% MEG (diol component), 12 mol% NPG (diol component), 2750 ppm sodium benzoate (nucleating agent), and 425 ppm silica (anti-blocking agent). In another exemplary embodiment, the third co-polyester resin is made of 100 mol% PTA (dibasic component), 87 mol% MEG (diol component), 13 mol% NPG (diol component), 2750 ppm sodium benzoate (nucleating agent), and 425 ppm silica (anti-blocking agent). In yet another exemplary embodiment, the third co-polyester resin is made of 100 mol% PTA (dibasic component), 86 mol% MEG (diol component), 14 mol% NPG (diol component), 2750 ppm sodium benzoate (nucleating agent), and 425 ppm silica (anti-blocking agent).
[52] In an exemplary embodiment, a stainless-steel reactor equipped with a mechanical stirrer, a fractionating column, a condenser and a heating system is charged with one or more dibasic acid component, and one or more diol component and esterified at 250-255 °C for 2-3 hours to obtain a monomer. The monomer obtained by esterification is transferred to a polymerization reactor along with a polymerization catalyst (0.045% (w/w) antimony trioxide) and a heat stabilizer (0.09% (w/w) triphenyl phosphate). The polymerization reaction is then conducted at 255-285 °C by gradually reducing a pressure from 730 mm of Hg to less than or equal to 1.0 mm of Hg to obtain the third co-polyester resin. The third co-polyester resin is casted in the form of strands by applying nitrogen pressure to the polymerization reactor and converted into granules by quenching in cold water.
[53] In an exemplary embodiment, the steps 201a, 201b, are 201c of the method 200 are executed in parallel. In an alternative embodiment, the steps 201a, 201b, are 201c of the method 200 are executed sequentially.
[54] At step 203a, the first co-polyester resin is homogenously mixed with the one or more additives, for example, the at least one antioxidant in a first mixing section of an extruder to obtain a first mixture. The amount of the antioxidant ranges from 0.05% (w/w) to 0.2% (w/w). In an exemplary embodiment, the first co-polyester resin is mixed with 0.1% (w/w) of Irganox-1010 (antioxidant).
[55] At step 203b, the second co-polyester resin is homogenously mixed with the one or more additives, for example, the at least one antioxidant and the at least one chain extender in a second mixing section of the extruder to obtain a second mixture. The amount of the antioxidant ranges from 0.05% (w/w) to 0.2% (w/w). The chain extender may be at least one of Johncryl ADR-4300, Johncryl ADR-4468, any polymeric chain extender with low epoxy equivalent weight moieties, etc. The amount of the chain extender ranges from 0.01% (w/w) to 0.10% (w/w). In an exemplary embodiment, the second co-polyester resin is mixed with 0.1% (w/w) of Irganox-1010 (antioxidant), and 0.05% (w/w) of Johncryl ADR-4300 (chain extender). In another exemplary embodiment, the second co-polyester resin is mixed with 0.1% (w/w) of Irganox-1010 (antioxidant), and 0.02% (w/w) of Johncryl ADR-4468 (chain extender).
[56] Additionally or optionally, the second mixture is mixed with a regrind polyester at a predefined concentration. The predefined concentration may range between 0-50 %. In an exemplary embodiment, the regrind polyester includes the film 10 of the present disclosure after it is being recycled.
[57] At step 203c, the third co-polyester resin is homogenously mixed with the one or more additives, for example, the at least one antioxidant in a third mixing section of the extruder to obtain a third mixture. The amount of the antioxidant ranges between 0.05% (w/w) and 0.2% (w/w). In an exemplary embodiment, the third co-polyester resin is mixed with 0.1% (w/w) of Irganox-1010 (antioxidant).
[58] In an exemplary embodiment, the steps 203a, 203b, are 203c of the method 200 are executed in parallel. In an alternative embodiment, the steps 203a, 203b, are 203c of the method 200 are executed sequentially.
[59] At step 205a, the first mixture is pre-heated to a pre-defined temperature for a pre-defined time period in a first drying section of a dryer. The pre-defined temperature ranges from 40 °C to 60 °C. The pre-defined time period ranges from 1 hour to 8 hours depending upon the moisture content of the first mixture. In an exemplary embodiment, the first mixture is heated to 40 °C to 60 °C. Pre-heating the first mixture helps to remove moisture content that may compromise co-extrusion of the film 10.
[60] At step 205b, the second mixture is pre-heated to a pre-defined temperature for a pre-defined time period in a second drying section of the dryer. The pre-defined temperature ranges from 40 °C to 60 °C. The pre-defined time period ranges from 1 hour to 8 hours depending upon the moisture content of the second mixture. In an exemplary embodiment, the second mixture is heated to 40 °C to 60 °C. Pre-heating the second mixture helps to remove moisture content that may compromise co-extrusion of the film 10.
[61] At step 205c, the third mixture is pre-heated to a pre-defined temperature for a pre-defined time period in a third drying section of the dryer. The pre-defined temperature ranges from 40 °C to 60 °C. The pre-defined time period ranges from 1 hour to 8 hours depending upon the moisture content of the third mixture. In an exemplary embodiment, the third mixture is heated to 40 °C to 60 °C. Pre-heating the third mixture helps to remove moisture content that may compromise co-extrusion of the film 10.
[62] In an exemplary embodiment, the steps 205a, 205b, are 205c of the method 200 are executed in parallel. In an alternative embodiment, the steps 205a, 205b, are 205c of the method 200 are executed sequentially.
[63] At step 207a, the first mixture is extruded, by using the extruder, to obtain a first melt. The extruder is set at a pre-defined temperature under a predefined pressure ranging from 240 °C to 275 °C and 5 mmHg to 20 mmHg. In an exemplary embodiment, the extruder is set at a temperature of 265-275 °C and a pressure of 5-10 mmHg.
[64] At step 207b, the second mixture is extruded, by using the extruder, to obtain a second melt. The extruder is set at a pre-defined temperature under a predefined pressure ranging from 240 °C to 275 °C and 5 mmHg to 20 mmHg. In an exemplary embodiment, the extruder is set at a temperature of 265-275 °C and a pressure of 5-10 mmHg.
[65] At step 207c, the third mixture is extruded, by using the extruder, to obtain a third melt The extruder is set at a pre-defined temperature under a predefined pressure ranging from 240 °C to 275 °C and 5 mmHg to 20 mmHg. In an exemplary embodiment, the extruder is set at a temperature of 265-275 °C and a pressure of 5-10 mmHg.
[66] In an exemplary embodiment, the steps 207a, 207b, are 207c of the method 200 are executed in parallel. In an alternative embodiment, the steps 207a, 207b, are 207c of the method 200 are executed sequentially.
[67] At step 209, the first melt, the second melt and the third melt, after their respective extrusion, are co-extruded to obtain the three layers of the film 10, namely the first layer 11, the second layer 13 and the third layer 15 respectively. In an exemplary embodiment, the first melt, the second melt and the third melt are forced through a coat hanger type film die to achieve sheet-like form of the film 10.
[68] At step 211, the first melt, the second melt and the third melt are cooled (or quenched) to a pre-defined temperature ranging from 25 °C to 35 °C to obtain the film 10 (or cast film). In an exemplary embodiment, the melt is quenched over a chilled roller by using electrostatic pinning.
[69] Although the present disclosure describes preparation of the film 10 via extrusion process, other functionally equivalent processes are within the scope of the teachings of the present disclosure.
[70] At step 213, the film 10 obtained from step 211 is oriented by a five-stage process. Orienting the film 10 helps to achieve enhanced shrinkage.
[71] In a first stage of step 213, the film 10 is passed through a machine direction (MDO) set at a first pre-defined temperature. The MDO is provided with a plurality of rollers. The film 10 is passed in between the rollers of the MDO. The rollers of the MDO are maintained at the first pre-defined temperature. The first pre-defined temperature ranges from 80 °C to 120 °C. In an exemplary embodiment, the rollers of the machine direction (MDO) are set at 60-80 °C.
[72] Additionally or optionally, the film 10 may be simultaneously subjected to infrared heating when the film 10 is passed through the MDO. Passing the film 10 through the machine direction (MDO) helps to pre-heat the film.
[73] In a second stage of step 213, the film 10 is stretched at a second pre-defined temperature at a first pre-defined stretch ratio in the machine direction (MD) as the film 10 travels in the machine direction at a first pre-defined line speed. The second pre-defined temperature ranges from 80°C to 120 °C. Stretching the film 10 yields a web width of the film 10. The first pre-defined stretch ratio ranges from 4 to 6 times in the transverse direction (TD) of the initial width of the film 10. The first predefined line speed of the tenter frame ranges from 50 m/min to 90 m/min. The first pre-defined stretch ratio and the first pre-defined line speed is selected basis on final thickness of the film 10 obtained at step 211.
[74] In an optional third stage of step 213, one or more layers of coating is applied on at least one surface (or face) of the film 10, i.e., either on the first layer 11 or the third layer 15. The layer of coating may be selected from an acrylic coating, a co-polymer base coating, an anti-static coating or a combination thereof. The anti-static coating may include one of water-soluble conductive ionic compound having at least one conductive group selected from a sulfonic group, a sulfonate group, a quaternary ammonium salt, a tertiary ammonium salt, a carboxyl group, a hydroxy group, an amino group, an epoxy group, an aziridinyl group, an active methyle group, a sulfinic group, an aldehyde group and/or a vinylsulfone group. In an exemplary embodiment, only one side (or face) of the film 10 is online coated with the anti-static coating using a reverse gravure system. The anti-static coating helps to eliminate static charge generated during handling of the film 10, for example, during winding, slitting, etc.
[75] In an optional fourth stage of the step 213, the film 10 is subjected to heat setting (or annealing) at a fourth pre-defined temperature. The fourth pre-defined temperature ranges from 70 °C to 55 °C. In an exemplary embodiment, the film 10 is annealed at an annealing section of the tenter frame by gradually reducing the temperature from 55 °C to 40 °C. Heat setting the film 10 helps to improve stability of the film 10.
[76] In an optional fifth stage of step 213, the film 10 is stretched at a fifth pre-defined temperature at a second pre-defined stretch ratio in the transverse direction (TD) as the film 10 travels in the machine direction (MD) at a second pre-defined line speed. The fifth pre-defined temperature ranges from 85°C to 90 °C. The second pre-defined stretch ratio ranges from 2.5 – 7 times the initial width of the film 10, preferably 3 – 3.5 times the initial width of the film 10. The second predefined line speed of the tenter frame ranges from 50 m/min to 90 m/min. The second pre-defined stretch ratio and the second pre-defined line speed is selected basis the final thickness of the film 10 obtained at step 211. Stretching the film 10 in the transverse direction (TD) helps to improve the shrinkage property of the film 10.
[77] At step 215, the film 10 obtained from step 213 is subjected to a surface cooling surface. In an embodiment, the film 10 is passed between a group of rollers. The rollers are maintained at a third pre-defined temperature. The third predefined temperature ranges between 20 °C and 30 °C. The film 10 is then wound on Jumbo Winders and further slitted in to smaller widths and lengths, for easy storage and use. The film 10 obtained at step 213 has a pre-defined thickness ranging from 30 microns to 65 microns depending upon the end-applications.
[78] Fig. 3 depicts a method 300 to evaluate clumping of polyester containers (or containers) provided with the film 10 of the present disclosure while regenerating the container (or chips thereof) in a recycling process. In an exemplary embodiment, the container is a container having at least 90% polyethylene terephthalate (PET). In an exemplary embodiment, the clumping is evaluated as per PET S-08 2022 guidelines published by The Association of Plastic Recyclers.
[79] The method commences at step 301 by providing a container at least partially wrapped with the film 10 via a seaming technique. The seaming technique includes making a tubular/cylindrical sleeve out of the film 10 corresponding to the container. The edges of the sleeve made out of the film 10 in the longitudinal direction are sealed by solvents like 1,3-dioxolane, tetrahydrofuran or a combination thereof. The sleeve made out of the film 10 is then mounted over the container and passed through a hot air tunnel or steam tunnel. The hot air tunnel is maintained at a temperature ranging from 140 °C to 180 °C. The steam tunnel is maintained at a temperature ranging from 80 °C to 100 °C. Passing the container wrapped with the sleeve made of the film 10 helps the sleeve to shrink and cling to the outer surface of the container. The sleeve made out of the film 10 may optionally be printed with an ink.
[80] At step 303, the container provided with the film 10 is grinded into flakes having a pre-defined size ranging from 0.5 mm to 12 mm. In an exemplary embodiment, the size of the flakes obtained from the grinding is less than 12.5 mm. The flakes are weighed to determine an initial weight (i). The flakes include both, the flakes made of the film 10 and the flakes made of the container.
[81] At an optional step 305, the flakes are subjected to at least one washing with at least one pre-defined solution/solvent. Subjecting the flakes to the wash removes the ink (and other impurities) from the film 10 thereby preventing adulteration of the flakes in subsequent steps.
[82] In an exemplary embodiment, the flakes are first washed by immersing the flakes in an aqueous solution of sodium hydroxide (NaOH) having a concentration of 1% at 85 °C for 5-30 minutes. Thereafter, the flakes are optionally washed in water at room temperature.
[83] At an optional step 307, the flakes are dried at least once at a pre-defined temperature ranging from 60 °C to 175 °C for a pre-defined time period ranging from 10-30 minutes. In an exemplary embodiment, the flakes are dried at 65 °C for 20 minutes.
[84] At step 309, the flakes are subjected to a pre-defined temperature for a pre-defined time period to obtain a plurality of regenerated polyester-based chips. In an exemplary embodiment, the flakes are kept inside an oven maintained at 195 °C for 90 minutes. In another exemplary embodiment, the flakes are first maintained at 165 °C for 30 minutes and then at 195 °C for 90 minutes.
[85] At step 311, the flakes are transferred to a screen having a pre-defined pore size. In an exemplary embodiment, the pore size of the screen is 12.5 mm.
[86] At step 313, the screen is shaken. Any residual flakes (or clumps thereof) are weighed to determine clumping weight (c) of the flakes.
[87] At step 315, the clumping ratio is calculated by the relation [clumping weight (c)/initial weight (i)] x 100. In an exemplary embodiment, the clumping ratio is less than 1%.
[88] The present disclosure will now be explained with the help of the following examples:
[89] Example 1 (Present disclosure):
[90] A first layer 11 and a third layer 15 of the film 10 of the present disclosure were prepared using the following compositions and evaluated for their respective properties:
SAMPLE (First layer 11/Third layer 15) Composition
PTA – dibasic acid (M%) MEG – diol (M%) NPG – diol
(M%) SILICA – anti-blocking agent
(PPM) SODIUM BENZOATE – nucleating agent
(PPM)
Resin-1 100 88 12 425 0
Resin-2 100 88 12 425 1500
Resin-3 100 88 12 425 2750
Resin-3a 100 87 13 425 2750
Resin-3b 100 86 14 425 2750
Resin-4 100 88 12 425 3500
Resin-5 100 88 12 425 4500

SAMPLE
(First layer 11/Third layer 15) Properties
Tc ½ (min) Tm (°C) I.V. (dl/g)
Resin-1 No peak 207 0.730
Resin-2 19.03 207.4 0.740
Resin-3 10.32 207.2 0.710
Resin-3a 13.5 206 0.731
Resin-3b 16.6 203 0.713
Resin-4 7.9 207.8 0.690
Resin-5 7.98 208 0.720

[91] Example 2 (Present disclosure):
[92] A second layer 13 of the film 10 of the present disclosure was prepared using the following compositions and evaluated for their respective properties:
SAMPLE
(Second layer 13) Composition
PTA – dibasic acid (M%) MEG – diol (M%) NPG – diol
(M%) DEG – diol
(M%) SILICA – anti-blocking agent
(PPM) Melt strengthening agent (ppm)
Resin-6 100 86.34 11.69 1.96 425 (Johncryl ADR-4300)
1000
Resin-7 100 82.0 16.0 2.00 425 (Johncryl ADR-4468)
200

SAMPLE
(Second layer 13) Properties
Tc ½ (min) Tm (°C) I.V. (dl/g)
Resin-6 NO PEAK 204 (CAPILLARY) 0.745
Resin-7 NO PEAK 202 (CAPILLARY) 0.735

[93] Example 3 (Present disclosure):
[94] A film 10, having 45 microns thickness, was co-extruded using the first layers 11, the second layers 13 and the third layers 15 obtained from the above examples and evaluated for their respective properties:

Sample
(First layer 11/Second layer 13/Third layer 15)


Second layer 13 composition (% wt.)


First layer 11 composition (% wt.)
Third layer 15 composition (% wt.)
Example 2 above Irgonax-1010 Johncryl ADR-4300, Joncryl ADR-4468 Example 1 above Irgonax-1010 Example 1 above Irgonax-1010
Film 1
RESIN-6 Antioxidant Chain extender Resin-1 Antioxidant Resin-1 Antioxidant
99.8 0.1 0.1 99.9 0.1 99.9 0.1
Film 2
RESIN-6 Antioxidant Chain extender Resin-2 Antioxidant Resin-2 Antioxidant
99.8 0.1 0.1 99.9 0.1 99.9 0.1
Film 3
RESIN-6 Antioxidant Chain extender Resin-3 Antioxidant Resin-3 Antioxidant
99.8 0.1 0.1 99.9 0.1 99.9 0.1
Film 4
RESIN-6 Antioxidant Chain extender Resin-4 Antioxidant Resin-4 Antioxidant
99.8 0.1 0.1 99.9 0.1 99.9 0.1
Film 5
RESIN-6 Antioxidant Chain extender Resin-5 Antioxidant Resin-5 Antioxidant
99.8 0.1 0.1 99.9 0.1 99.9 0.1
Film 6 RESIN-7 Antioxidant Chain extender Resin-3a Antioxidant Resin-3a Antioxidant
99.85 0.1 0.05 99.9 0.1 99.9 0.1
Film 7 RESIN-7 Antioxidant Chain extender Resin-3b Antioxidant Resin-3b Antioxidant
99.88 0.1 0.02 99.9 0.1 99.9 0.1
Film 7a RESIN-7 Antioxidant Chain extender Resin-3b Antioxidant Resin-3b Antioxidant
99.88 0.1 0.02 99.9 0.1 99.9 0.1
Film 7a RESIN-7 Antioxidant Chain extender Resin-3b Antioxidant Resin-3b Antioxidant
99.88 0.1 0.02 99.9 0.1 99.9 0.1

Sample
(First layer 11/Second layer 13/Third layer 15) Properties
%Haze Tensile St. (Kg/cm2) Clumping ratio (as per APR PET S-08 2022) Seaming Printing Shrinkage in shrink direction @98°C/30 sec.
Film 1
(10%/80%/10%) 4.5-5.5 2700-2800 2% OK OK 77-78
Film 2
(10%/80%/10%) 4.8-5.7 2720-2790 0.9% OK OK 76-77
Film 3
(10%/80%/10%) 5.0-6.1 2700-2780 0.5% OK OK 76-78
Film 4
(10%/80%/10%) 6.4-6.9 2700-2710 0.4% Poor Poor 76-77
Film 5
(10%/80%/10%) 7.5-8.2 2650-2700 0.3% Poor Poor 75-77
Film 6
(10%/80%/10%) 5.5-6.5 2600-2650 0.52% OK OK 76-77
Film 7
(5%/90%/5%) 5.2-5.6 2605-2715 0.64% OK OK 77-78
Film 7a
(10%/80%/10%) 6.5-7.2 2645-2750 0.57% OK OK 77-78
Film 7b
(15%/70%/15%) 7.5-8.2 2665-2705 0.50% OK OK 77-78

[95] Example 4 (Present disclosure):
[96] A film 10, having 45 microns thickness, was co-extruded using 10% of the first layer 11 (Resin 3), 80% of the second layer 13 (Resin 6) and 10% of the third layer 15 (Resin 3) obtained from the above examples and evaluated for their composition and properties:

Composition
(First layer 11/Second layer 13/Third layer 15)
PTA (M%) MEG
(M%) NPG
(M%) DEG
(M%) SILICA (PPM) SODIUM BENZOATE (PPM) Johncryl ADR-4300 (ppm)
100 86.68 11.75 1.57 425 550 800








Properties

Tc ½ (min) Tm (°C) – by capillary method I.V. (dl/g)
NO PEAK 206 0.66

[97] Example 5 (Present disclosure):
[98] The film 10 (first layer 11 and third layer 15 is prepared by resin 3 and second layer 13 is prepared by resin 6) having a thickness of 45 microns of the present disclosure was prepared by adding regrind polymers to the second layer 13 (resin 6) obtained above and evaluated for their respective properties:
Sample
(Film 10) Composition
PTA (M%) MEG(M%) NPG(M%) DEG(M%) SILICA (PPM) SODIUM BENZOATE (PPM) Johncryl ADR-4300 (ppm)
Resin-6 + 30% regrind polymers 100 86.44 11.71 1.85 425 165 940
Resin-6 + 40% regrind polymers 100 86.48 11.72 1.81 425 220 920
Resin-6 + 50% regrind polymers 100 86.51 11.72 1.77 425 275 900

Sample
(Film 10) Properties
Shrinkage% in shrink direction at 98°C/30 sec. I.V. (dl/g) Clumping ratio (as per APR PET S-08 2022)
Haze (%)
Resin-6 + 30% regrind polymers 77-78 0.66 0.46% 5.4
Resin-6 + 40% regrind polymers 76-77 0.655 0.49% 5.9
Resin-6 + 50% regrind polymers 76-77 0.65 0.52% 6.2

[99] Example 6 (Present disclosure):
[100] A film 10, having 45 microns thickness, was co-extruded using 5% of the first layer 11 (Resin 3b), 90% of the second layer 13 (Resin 7) and 5% of the third layer 15 (Resin 3b) obtained from the above examples and evaluated for their composition and properties:
Composition
(First layer 11/Second layer 13/Third layer 15)
PTA (M%) MEG
(M%) NPG
(M%) DEG
(M%) SILICA (PPM) SODIUM BENZOATE (PPM) Johncryl ADR-4468 (ppm)
100 82.43 15.77 1.80 425 275 180








Properties

Tc ½ (min) Tm (°C) – by capillary method I.V. (dl/g)
NO PEAK 202 0.66

[101] Example 7 (Present disclosure):
[102] The film 10 (first layer 11 and third layer 15 is prepared by resin 3b and second layer 13 is prepared by resin 7) having a thickness of 45 microns of the present disclosure was prepared by adding regrind polymers to the second layer 13 (resin 7) obtained above and evaluated for their respective properties:
Sample
(Film 10) Composition
PTA (M%) MEG(M%) NPG(M%) DEG(M%) SILICA (PPM) SODIUM BENZOATE (PPM) Johncryl ADR-4460 (ppm)
Resin-7 + 30% regrind polymers 100 82.13 15.91 1.94 425 82.5 194
Resin-7 + 40% regrind polymers 100 82.18 15.89 1.92 425 110 192
Resin-7 + 50% regrind polymers 100 82.22 15.87 1.90 425 137.5 190

Sample
(Film 10) Properties
Shrinkage% in shrink direction at 98°C/30 sec. I.V. (dl/g) Clumping ratio (as per APR PET S-08 2022)

Haze (%)
Resin-7 + 30% regrind polymers 76-77 0.662 0.52% 6
Resin-7 + 40% regrind polymers 77-78 0.657 0.47% 6.2
Resin-7 + 50% regrind polymers 75-76 0.650 0.51% 6.5
[103] Example 8 (Present disclosure):
[104] A film 10, having 45 microns thickness, was co-extruded using 10% of the first layer 11 (Resin 3b), 80% of the second layer 13 (Resin 7) and 10% of the third layer 15 (Resin 3b) obtained from the above examples and evaluated for their composition and properties:
Composition
(First layer 11/Second layer 13/Third layer 15)
PTA (M%) MEG
(M%) NPG
(M%) DEG
(M%) SILICA (PPM) SODIUM BENZOATE (PPM) Johncryl ADR-4468 (ppm)
100 82.50 15.51 1.59 425 275 160








Properties

Tc ½ (min) Tm (°C) – by capillary method I.V. (dl/g)
NO PEAK 203 0.658

[105] Example 9 (Present disclosure):
[106] The film 10 (first layer 11 and third layer 15 is prepared by resin 3b and second layer 13 is prepared by resin 7) having a thickness of 45 microns of the present disclosure was prepared by adding regrind polymers to the second layer 13 (resin 7) obtained above and evaluated for their respective properties:
Sample
(Film 10) Composition
PTA (M%) MEG(M%) NPG(M%) DEG(M%) SILICA (PPM) SODIUM BENZOATE (PPM) Johncryl ADR-4460 (ppm)
Resin-7 + 30% regrind polymers 100 82.16 15.83 1.42 425 165 188
Resin-7 + 40% regrind polymers 100 82.21 15.78 1.84 425 220 184
Resin-7 + 50% regrind polymers 100 82.26 15.74 1.80 425 275 180

Sample
(Film 10) Properties
Shrinkage% in shrink direction at 98°C/30 sec. I.V. (dl/g) Clumping ratio (as per APR PET S-08 2022)
Haze (%)
Resin-7 + 30% regrind polymers 76-77 0.662 0.58% 7.5
Resin-7 + 40% regrind polymers 77-78 0.657 0.53% 7.8
Resin-7 + 50% regrind polymers 75-76 0.650 0.48% 7.9
[107] Example 10 (Present disclosure):
[108] A film 10, having 45 microns thickness, was co-extruded using 15% of the first layer 11 (Resin 3b), 70% of the second layer 13 (Resin 7) and 15% of the third layer 15 (Resin 3b) obtained from the above examples and evaluated for their composition and properties:
Composition
(First layer 11/Second layer 13/Third layer 15)
PTA (M%) MEG
(M%) NPG
(M%) DEG
(M%) SILICA (PPM) SODIUM BENZOATE (PPM) Johncryl ADR-4468 (ppm)
100 83.23 15.38 1.40 425 825 140








Properties

Tc ½ (min) Tm (°C) – by capillary method I.V. (dl/g)
NO PEAK 203 0.658

[109] Example 11 (Present disclosure):
[110] The film 10 (first layer 11 and third layer 15 is prepared by resin 3b and second layer 13 is prepared by resin 7) having a thickness of 45 microns of the present disclosure was prepared by adding regrind polymers to the second layer 13 (resin 7) obtained above and evaluated for their respective properties:
Sample
(Film 10) Composition
PTA (M%) MEG(M%) NPG(M%) DEG(M%) SILICA (PPM) SODIUM BENZOATE (PPM) Johncryl ADR-4460 (ppm)
Resin-7 + 30% regrind polymers 100 82.4 15.8 1.82 425 247.5 182
Resin-7 + 40% regrind polymers 100 82.5 15.7 1.76 425 330 176
Resin-7 + 50% regrind polymers 100 82.6 15.7 1.70 425 412.5 170

Sample
(Film 10) Properties
Shrinkage% in shrink direction at 98°C/30 sec. I.V. (dl/g) Clumping ratio (as per APR PET S-08 2022)
Haze (%)
Resin-7 + 30% regrind polymers 76-78 0.658 0.55% 8
Resin-7 + 40% regrind polymers 76-77 0.655 0.5% 8.2
Resin-7 + 50% regrind polymers 75-76 0.653 0.46% 8.4

[111] The scope of the invention is only limited by the appended patent claims. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. ,CLAIMS:WE CLAIM,
1. A multi-layer heat-shrink film (10), comprising:
a. a first layer (11) made of at least one first co-polyester resin and one or more additives;
b. a third layer (15) made of at least one third co-polyester resin and one or more additives; and
c. a second layer (13) disposed between the first layer (11) and the third layer (15), made of at least one second co-polyester resin and one or more additives;
wherein, at least one of the first layer (11) and the third layer (15) is relatively more crystalline than the second layer (13).
2. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the multi-layer heat-shrink film (10) has a clumping ratio of less than 1% when evaluated as per APR PET S-08 2022 guidelines.
3. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the multi-layer heat-shrink film (10) has a shrinkage of 72% or more in a transverse direction (TD) when subjected to 98 °C for 30 seconds.
4. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the multi-layer heat-shrink film (10) has an intrinsic viscosity ranging from 0.6dl/g to 1.2dl/g.
5. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the multi-layer heat-shrink film (10) has a melting temperature (Tm) ranging from 190 °C to 215 °C.
6. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the multi-layer heat-shrink film (10) has a thickness ‘x’ ranging from 30 microns (µm) to 65 microns (µm).
7. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the thickness of the first layer (11), and the third layer (15), respectively, ranges from 5% to 15% of the total thickness ‘x’ of the multi-layer heat-shrink film (10).
8. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the thickness of the second layer (13) ranges from 70% to 90% of the total thickness ‘x’ of the multi-layer heat-shrink film (10).
9. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein at least one of the first layer (11), and the third layer (15) has a crystallization time (Tc½) ranging from 5 minutes to 30 minutes when measured at 160°C.
10. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the crystallization time (Tc½) of the second layer (13) is not observed.
11. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein at least one of the first layer (11) or the third layer (15) is provided with a layer of coating selected from an acrylic coating, a co-polymer base coating, an anti-static coating or a combination thereof.
12. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the first co-polyester resin, the second co-polyester resin, and the third co-polyester resin includes one or more dibasic acid components copolymerized with one or more diol components.
13. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the first co-polyester resin, the second co-polyester resin, and the third co-polyester resin includes one or more dibasic acid components selected from a group of terephthalic acid, isophthalic acid, adipic acid, orthophthalic acid, sebacic acid, naphthalene dicarboxylic acid, azalaic acid, succinic acid or a combination thereof.
14. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the first co-polyester resin, and the third co-polyester resin includes one or more diol components selected from a group of ethylene glycol, diethylene glycol, triethylene glycol, butane diol, neopentyl glycol (NPG), monoethylene glycol (MEG), cyclohexane dimethanol, 2-methyl-1,3-propanediol or a combination thereof.
15. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the first co-polyester resin, and the third co-polyester resin includes 80 mol% to 90 mol% monoethylene glycol (MEG), and 10 mol% to 20 mol% neopentyl glycol (NPG) as diol components for every 100 mol% of purified terephthalic acid (PTA) as a dibasic acid component.
16. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the second co-polyester resin includes one or more diol components selected from a group of ethylene glycol, diethylene glycol (DEG), triethylene glycol, butane diol, neopentyl glycol (NPG), monoethylene glycol (MEG), cyclohexane dimethanol, 2-methyl-1,3-propanediol or a combination thereof.
17. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the second co-polyester resin includes 80 mol% to 90 mol% monoethylene glycol (MEG), 5 mol% to 20 mol% neopentyl glycol (NPG), and 1 mol% to 10 mol% of diethylene glycol (DEG) as diol components for every 100 mol% of purified terephthalic acid (PTA) as a dibasic acid component.
18. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the one or more additives of the first co-polyester resin, and the third co-polyester resin includes at least one nucleating agent in the range of 1500 ppm to 4500 ppm, at least one anti-blocking agent in the range of 100 ppm to 1000 ppm, and at least one antioxidant in the range of 0.05% (w/w) to 0.2% (w/w).
19. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the one or more additives of the second co-polyester resin includes at least one melt strengthening agent in the range of 100 ppm to 1000 ppm, at least one anti-blocking agent in the range of 100 ppm to 1000 ppm, at least one antioxidant in the range of 0.05% (w/w) to 0.2% (w/w), and at least one chain extender in the range of 0.01% (w/w) to 0.10% (w/w).
20. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the one or more additives of the first co-polyester resin, and the third co-polyester resin includes at least one nucleating agent selected from a group of sodium benzoate, talc or a combination thereof.
21. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the one or more additives of the first co-polyester resin, the second co-polyester resin, and the third co-polyester resin includes at least one anti-blocking agent selected from a group of silica, silicon dioxide, calcium carbonate, talc, kaolin or a combination thereof.
22. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the one or more additives of the first co-polyester resin, the second co-polyester resin, and the third co-polyester resin includes Irganox-1010 as an antioxidant.
23. The multi-layer heat-shrink film (10) as claimed in claim 1, wherein the one or more additives of the second co-polyester resin includes at least one chain extender selected from a group of Johncryl ADR-4300, Johncryl ADR-4468 or a combination thereof.
24. A method (200) to prepare a multi-layer heat-shrink film (10) comprising:
a. preparing a first co-polyester resin with one or more dibasic acid components, one or more diol components, at least one nucleating agent, and at least one anti-blocking agent;
b. preparing a second co-polyester resin with one or more dibasic acid components, one or more diol components, at least one melt strengthening agent, and at least one anti-blocking agent;
c. preparing a third co-polyester resin with one or more dibasic acid components, one or more diol components, at least one nucleating agent, and at least one anti-blocking agent;
d. mixing the first co-polyester resin and the third co-polyester resin with at least one respective antioxidant separately to obtain a first mixture and a third mixture;
e. mixing the second co-polyester resin with at least one antioxidant and at least one chain extender to obtain a second mixture;
f. extruding the first mixture, the second mixture and the third mixture using an extruder to obtain a first melt, a second melt and a third melt;
g. co-extruding the first melt, the second melt and the third melt to obtain a first layer (11), a second layer (13), and a third layer (15) of a multi-layer heat-shrink film (10);
h. cooling the first melt, the second melt and the third melt to obtain the multi-layer heat-shrink film (10); and
i. orienting the multi-layer heat-shrink film (10).
25. The method (200) as claimed in claim 24, wherein the step of preparing the first co-polyester resin includes preparing the first co-polyester resin with the one or more dibasic acid components, the one or more diol components, 1500 ppm to 4500 ppm of the nucleating agent, and 100 ppm to 1000 ppm of the anti-blocking agent.
26. The method (200) as claimed in claim 24, wherein the step of preparing the first co-polyester resin includes preparing the first co-polyester resin with 80 mol% to 90 mol% monoethylene glycol (MEG), and 10 mol% to 20 mol% neopentyl glycol (NPG) as the diol components for every 100 mol% of purified terephthalic acid (PTA) as the dibasic acid component.
27. The method (200) as claimed in claim 24, wherein the step of preparing the second co-polyester resin includes preparing the second co-polyester resin with the one or more dibasic acid components, the one or more diol components, 100 ppm to 1000 ppm of the melt strengthening agent, and 100 ppm to 1000 ppm of the anti-blocking agent.
28. The method (200) as claimed in claim 24, wherein the step of preparing the second co-polyester resin includes preparing the second co-polyester resin with 80 mol% to 90 mol% monoethylene glycol (MEG), 5 mol% to 20 mol% neopentyl glycol (NPG), and 1 mol% to 10 mol% of diethylene glycol (DEG) as the diol components for every 100 mol% of purified terephthalic acid (PTA) as the dibasic acid component.
29. The method (200) as claimed in claim 24, wherein the step of preparing the third co-polyester resin includes preparing first co-polyester resin with the one or more dibasic acid components, the one or more diol components, 1500 ppm to 4500 ppm of the nucleating agent, and 100 ppm to 1000 ppm of the anti-blocking agent.
30. The method (200) as claimed in claim 24, wherein the step of preparing the third co-polyester resin includes preparing first co-polyester resin with 80 mol% to 90 mol% monoethylene glycol (MEG), and 10 mol% to 20 mol% neopentyl glycol (NPG) as the diol components for every 100 mol% of purified terephthalic acid (PTA) as the dibasic acid component.
31. The method (200) as claimed in claim 24, wherein the step of mixing the first co-polyester resin and the third co-polyester resin with at least one antioxidant includes mixing the first co-polyester resin and the third co-polyester resin with 0.05% (w/w) and 0.2% (w/w) of Irganox-1010 as the antioxidant.
32. The method (200) as claimed in claim 24, wherein the step of mixing the second co-polyester resin with at least one antioxidant and at least one chain extender includes mixing the first co-polyester resin and the third co-polyester resin with 0.05% (w/w) and 0.2% (w/w) of Irganox-1010 as the antioxidant and 0.01% (w/w) and 0.10% (w/w) of Johncryl ADR-4300, Johncryl ADR-4468, or a combination thereof as the chain extenders.
33. The method (200) as claimed in claim 24, wherein the step of mixing the second co-polyester resin with at least one antioxidant and at least one chain extender includes mixing the second co-polyester resin with 0% to 50% of a regrind polyester.
34. The method (200) as claimed in claim 24, wherein before the step of extruding the first mixture, the second mixture and the third mixture, the method (200) includes pre-heating the first mixture, the second mixture and the third mixture at a pre-defined temperature ranging from 40 °C to 60 °C for 1 hour to 8 hours.
35. The method (200) as claimed in claim 24, wherein the step of extruding the first mixture, the second mixture and the third mixture includes setting the extruder at a pre-defined temperature ranging from 240 °C to 275 °C under a predefined pressure ranging from 5 mmHg to 20 mmHg.
36. The method (200) as claimed in claim 24, wherein the step of cooling the first melt, the second melt and the third melt includes cooling the first melt, the second melt and the third melt to a pre-defined temperature ranging from 25 °C to 35 °C.
37. The method (200) as claimed in claim 24, wherein the step of orienting the multi-layer heat-shrink film (10) includes passing the multi-layer heat-shrink film (10) through a machine direction (MDO) set at a first pre-defined temperature ranging from 80 °C to 120 °C.
38. The method (200) as claimed in claim 24, wherein the step of orienting the multi-layer heat-shrink film (10) includes stretching the multi-layer heat-shrink film (10) at a second pre-defined temperature ranging from 80 °C to 120 °C to 4 to 6 times in a transverse direction (TD) of the multi-layer heat-shrink film (10).
39. The method (200) as claimed in claim 24, wherein the step of orienting the multi-layer heat-shrink film (10) includes applying one or more layers of coating selected from an acrylic coating, a co-polymer base coating, an anti-static coating or a combination thereof on at least one of the first layer (11) or the third layer (15) of the multi-layer heat-shrink film (10).
40. The method (200) as claimed in claim 24, wherein the step of orienting the multi-layer heat-shrink film (10) includes subjecting the multi-layer heat-shrink film (10) to heat setting at a fourth pre-defined temperature ranging from 70 °C to 55 °C.
41. The method (200) as claimed in claim 24, wherein the step of orienting the multi-layer heat-shrink film (10) includes stretching the multi-layer heat-shrink film (10) at a fifth pre-defined temperature ranging from 85 °C to 90 °C to 2.5 to 7 times in a transverse direction (TD) of the multi-layer heat-shrink film (10).
42. The method (200) as claimed in claim 24, wherein after the step of orienting the multi-layer heat-shrink film (10) the method (200) includes passing the multi-layer heat-shrink film (10) between a group of rollers maintained at a third pre-defined temperature ranging from 20 °C to 30 °C.