Title of Invention	A POLYESTER GAS BARRIER RESIN AND A PROCESS THEREOF
Abstract	A perform resin composition, is disclosed, comprising PET resin and a suspension of 50 to 5000 ppm, with respect to the resin, of nano clay having particle size of particle siz ranging between 10 and 100 nm ultrasonically dispersed in a suspension medium, such as DMF. A method of making the perform resin is also disclosed.

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FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 PROVISIONAL Specification (See section 10 and rule 13) A POLYESTER GAS BARRIER RESIN AND A PROCESS THEREOF FUTURA POLYESTERS LTD., an Indian Company of Paragon Condominium, 3 rd floor, Pandurang Budhkar Marg, Mumbai 400 013, Maharashtra, India THE FOLLOWING SPEC IFICATION DESCRIBES THE INVENTION. Technical Field The present invention is in the field of polymer-based gas barrier resin. The present invention also relates to a process for the preparation of said resin composition. Background of the invention Barrier properties of a polymer container involve the ability of the polymer to slow down or stop the passage of a gas through its wall thickness. Barrier property is quantified by measuring the polymer's permeability, the rate at which a given gas will pass through the polymer under a given set of conditions. Permeability is quantified by a material property called the diffusion coefficient or diffusivity constant, D. This constant is a measure of how easily the gas passes through a material. Low permeability means that the gas has difficulty to pass through a substance, typically over an extended period of time, and sometimes under elevated pressures. Polymers with low permeability are referred to as barrier materials in the packaging industry. They are responsible for helping to prevent CO2, O2 and other gases such as N2 escaping from the polymer container as well as retaining the flavor and minimizing 02 ingress. PET bottles for storing carbonated soft drinks (CSD) in small sizes where high surface area relative to volume call for a relatively modest CO2 barrier improvement. This is primarily due to the fact that small containers have more surface area, for a given volume of product, than large containers and they lose C02 easily in hot climatic conditions. Enhancing wall thickness as a barrier enhancement is not economically feasible. As a result, there is a 2 nead for a monolayer smaller volume container having enhanced barrier property, to offset the loss due to the large surface area. In large volume containers enhanced barrier properties, gives an opportunity to reduce the wall thickness or weight without compromising the shelf life of the product. One of the three fundamental ways to build C02 barrier into PET bottles is to design a multi-layer structure sandwiching PET structural layers around a core layer or layers containing barrier enhancement materials. This approach stands to benefit from promising new barrier materials such as nylon-based nanocomposites and "passive-active" barrier systems. However, multilayer extrusion technology is more complex compared to the monolayer extrusion to bottles. US 2006286349 deals with multilayer films for high oxygen barrier. The film includes an inner layer made of PET and outer layers made of CoPET and Poly(m-xylene-adipamide). JP 200296593 also describes a polyester multilayer sheet with upgraded gas barrier properties. The multilayer is formed by one or more layers of polyethylene terephthalate and polytrimethylene naphthalate. Surface-coating technologies apply a super-thin barrier to outer surface of a monolayer PET bottle. This again involves additional coating machinery. KR 20010062265 describes a film with gas barrier coating composition on a polyester substrate. The coating composition comprises polyvinyl alcohol, an amino group, glycidyl ether and fiber. An example which combines both the above said technologies is reported in KR 20040067972 for a gas barrier film. The inner layer is of polyester and 3 poly(m-xylene-adipamide) with a barrier coating and the barrier layer is made of copolymer blend of maleic acid and acrylic acid. The "ideal" route to a barrier PET bottle is a monolayer polyester structure. This approach would require alloying or blending or co-polymerizing a barrier resin with PET. Multi-layer or coating equipment would not be needed, and bottle design freedom would remain unfettered. CN 1786043 describes the preparation of PET composite material by compounding PET and nano oxides to increase the barrier property in monolayer structures. KR 20020078719 deals with a method of producing a film with excellent gas-screening property and transparency. The film is produced by forming a gas-screening layer which is obtained by mixing and dispersing clay in a dispersing medium, on the surface of polymer film like PET, Nylon etc. US 5972448 disclose a container made of polymer material integrated with nano clay, preferably montmorillonite. This nano-composite polymer container substantially decreases the permeability of various gases. The latest in the packaging industry is polyester with nano additives. These nano additives can be used to enhance properties of polymers such as mechanical properties, flavor retention, gas barrier and flame retardancy. Since the size of particle is of nanometer scale, the clarity of the blown containers made from the nanocomposite resin is comparable to pristine polyester resin. The nano additives can be incorporated into polyester resin by in-situ polymerization, melt blending, solution blending etc. Alternatively, these additives can be incorporated into the resin through a dosing equipment while making the preforms. In the present investigation the latter approach is followed. The advantages of this approach are that the nano 4 additives are subjected to high temperature for a shorter duration of time, precise control of the amount of nano additive and better dispersion. Objects of the present invention The primary object of the present invention is to provide a gas barrier polyester resin composition with enhanced the barrier properties. Another object of the present invention is to provide a process for the preparation of polyester gas barrier resin composition. Another object of the present invention is to provide a polyester gas barrier resin composition suitable for carbonated soft drink (CSD) containers even in smaller volumes (200-500 ml) in normal injection stretch blow molding (ISBM) machine by heat set or cold set blowing condition. It is also an object of the present invention to provide a polyester gas barrier resin composition to enhance the barrier property of a polyester resin for gases such as carbon dioxide, oxygen, nitrogen and water vapor as well as retention of flavor. Another object of the present invention is to induct additives which improve barrier properties at an advantageous stage of converting the polymer to a container. Another object of the invention is to form improved preforms which impart gas barrier properties to the containers made therefrom. 5 Summary of the invention The present invention envisages a polyester gas barrier resin composition comprising Polyethylene terephthalate (PET), and/or Polyethylene naphthalate (PEN) and/or Polytrimethylene naphthalate (PTN) and/or Polybutylene naphthalate (PBN) and/or Polytrimethylene terephthalate (PTT) and or Polybutylene terephthalate (PBT) and/or other glycol modified terephthalates like Polyethylene terephthalate modified with cyclohexanedimethanol (PETG) and (PCTG) etc., along with nano additives. The present invention also provides a process which includes the induction of nano additives into the resin during preform making by injection molding. Preparation of said resin by modifying the PET resin with nano additives to form amorphous PET pellets by melt polymerization. The PET is alloyed or dry blended with PEN or PTN or PBN in the desired ratios to obtain preforms. The preforms are further blown into containers with gas barrier properties. Description of the Invention Accordingly, the present invention provides a polyester gas barrier resin composition of Polyethylene terephthalate (PET), and/or Polyethylene naphthalate (PEN), and/or Polytrimethylene naphthalate (PTN) and/or Polybutylene naphthalate (PBN) and/or Polytrimethylene terephthalate (PTT) and/or Polybutylene terephthalate (PBT) and/or other glycol modified terephthalates like PETG, PCTG etc. along with nano additives. The alloy blend barrier resin of Polyethylene terephthalate (PET) and/or Polyethylene naphthalate (PEN) with Polytrimethylene naphthalate (PTN) and/or Polybutylene naphthalate (PBN) and/or Polytrimethylene terephthalate (PTT) 6 and or Polybutylene terephthalate (PBT) and/or other glycol modified terephthalates like PETG, PCTG etc. is in the ratio of 75:25 to 100:0. The nano additives are nano particles / nano clay and are otherwise known as passive barrier additive. The other passive barrier additives are nucleating agents, and branching agents. The nano additives of the present invention can be added to the polyester in the following stages, a) during esterification or b) melt polymerization or c) extrusion or d) blending with PET and/or PET -PTN/PBN/PEN/PTT/PBT etc. or e) as a master batch of the nano additives in a polyester carrier comprising PET and/or PEN/PTN/PBN/PTT/PBT and the like. The present invention also provides a process for the preparation of said resin by melt blending, alloying, copolymerizing or dry blending of the PET resin with PEN or PTN or PBN or PTT or PBT etc. in the desired ratios. The nano additives are incorporated into the alloy / blend / copolyester resin while making the preform in injection molding machine using the dosing system. The alloy blend PET/PEN or PTN or PBN or PTT or PBT and the like.polyesters containing the nano additives of the present invention can be formed into variety of articles including small volume (200-500 ml) CSD bottles in the normal injection stretch blow molding (ISBM) machine by cold set or heat set blowing condition. The improved resin composition of the present invention provides an enhanced improvement of barrier properties for gases especially carbon dioxide, oxygen, nitrogen and water vapor as well as flavor retention. In the present invention, the alloy blend PET/PEN or PTN or PBN or PTT or PBT resin is modified with nucleating agents , typically but not limited to sodium acetate, sodium salicylate, sodium sorbitol, nano additives typically 7 but not limited to nano silica and nano clay, along with micronized nucleating agent selected from the list of sodium benzoate, potassium benzoate and talc and chain branching agents like pyromellitic dianhydride (PMDA), trimellitic anhydride (TMA), pentaerythritol and the like. In the process of the present invention, the selected additives or monomers are added to the paste of pure terephthalic acid (PTA) and mono ethylene glycol (MEG) in the ratio of about 70:30 and the paste is charged into an esterifier. The paste also comprises a polycondensation catalyst, preferably of antimony (Sb) and Titanium (Ti) based along with suitable fast reheat (FRH) additives and clear fast reheat (CFRH) additives (optional as required) like, carbon, oxides of iron, oxides and carbides of transition metals. The paste also comprises colorants like cobalt acetate and organic toners like 8,9,10,1 l-tetrachloro-12H-phthaloperin-12-one (Red Toner) and 1,4-bis(mesitylamino)anthraquinone (Blue Toner). After the esterification process, the product is pre-polymerized in a pre-polymerization reactor and transferred to the polycondensation reactor. Prior to this transfer, heat stabilizers like phosphorous acid or phosphoric acid or triethyl phosphonoacetate are added to the prepolymer melt. After reaching the required intrinsic viscosity (I.V.) the amorphous PET chips are subjected to solid state polymerization (SSP) to increase the I.V. In a similar manner, Polyethylene naphthalate resins (PEN) or Polytrimethylene naphthalte (PTN) or Polybutylene naphthalte (PBN) are made by reacting NDC with monoethylene glycol (MEG), 1,3-Propylene diol (PDO) or 1,4-Butane diol (BDO) respectively. Similarly PTT is made by reacting PTA and PDO and PBT is made by reacting PTA and BDO. PET can also be alloyed with PTN or PBN or PEN or PTT or PBT etc. in the following ratio 75:25 to 100:0. Before reaching the required IV, say 20-40 minutes before completion of 8 polycondensation, PEN or PTN or PBN or PTT or PBT chips are added to the PET melt and further polymerized. After reaching the required intrinsic viscosity (I.V.) the molten polymer is extruded into amorphous PET chips and subjected to solid state polymerization (SSP) to increase the IV. Similarly the earlier produced homopolymer of PET is dry blended with PTN or PBN or PEN or PTT or PBT in the ratio of 75:25 to 100:0. The SSP resin and blend resin can be used for injection molding of the preforms and are then stretch blow molded with or without heat setting to make CSD bottles. These bottles are then characterized for their clarity, crystallinity, gas barrier properties and the like. In an embodiment of the present invention, nano additives are used up to 1000 ppm. The nano additives can be added during esterification or polymerization or extrusion or blending or induction during preform making or as a master batch of nano additive. Nano additives are selected from nanosilica, nanoclay, nanotubes, nanocubes etc. In another embodiment of the present invention the PET resin composition having nucleating agents, nano and micronized particles, branching agents and colorants are blended with PTN at about 0 -25 % levels. In yet another embodiment of the present invention, the PET resin wherein PBN is used in place of PTN at about 0-25 % levels. In yet another embodiment of the present invention, the PET resin wherein PEN is used in place of PTN at about 0-25 % levels. In yet another embodiment of the present invention, the PET resin wherein PTT is used in place of PTN at about 0-25 % levels. 9 In yet another embodiment of the present invention, the PET resin wherein PBT is used in place of PTN at about 0-25 % levels. It is also an embodiment of the present invention, the PET resin wherein the nucleating agents are selected from sodium stearate, sodium benzoate, potassium stearate and benzoate, silica sol, nano clays, sorbitol based chemicals and micornized sodium or potassium benzoates and stearates as well as talc. In yet another embodiment of the present invention, the PET resin wherein the chain branching agent is selected from ployfunctional alcohols having three or more hydroxyl functional groups, pentaerythritol, polycarboxylates and their acid precursors and anhydrides, trimethylolpropane ethoxylate. In yet another embodiment of the present invention, the PET resin wherein fast reheat (FRH) additives and clear fast reheat additives (CFRH) are selected from carbon black, oxides of iron, oxides and carbide of transition metal. In a further embodiment of the present invention, the PET resin wherein the base PET resin's I.V. is in the range of 0.70 - 0.86 dL/g. The invention is further explained in the form of following examples. However, these examples should not be considered as limiting the scope of the present invention. 10 Example 1 10.38 kg of pure terephthalic acid and 4.46 kg of monoethylene glycol are taken in an esterification vessel, in 1:1.4 molar ratio. To this, nucleating agent, sodium benzoate 50 ppm (0.6 g) is added. Polymerization catalyst antimony trioxide 240 ppm as Sb (3.44 g), colorants cobalt acetate 20 ppm as Co (1.01 g), red toner 1.5 ppm (0.018 g) and blue toner 1.2 ppm (0.014 g) are further added to the above mixture. The esterification reaction is carried out at 240 - 265 °C temperature for 190 minutes. The esterified pre-polymer is transferred to the polycondensation reactor. Before commencing polymerization, triethyl phosphonoacetate 50 ppm as P (TEPA, 4.34 g) and CFRH additive viz. oxide of transition metal 10 ppm (0.12 g) are added. The polymerization is conducted at a temperature of 265 -290 °C under 5-15 mbar for 180 minutes. After the required torque is reached, the molten amorphous polymer is extruded under nitrogen pressure and collected as pellets. The resulting amorphous polymer with I.V. ~ 0.6 dL/g is solid state polymerized to I.V.~ >0.77 dL/g, made into a preform by injection molding and analyzed for their characteristics. Example 2 In this example towards the end of polymerization 0.5 kg of PEN or PTN or PBN or PTT or PBT chips are added and the polymer melt is kept under agitation for a period of 20 minutes before the amorphous alloyed polyester melt is extruded. Except for the above mentioned additional additives the resin composition and process conditions are followed as mentioned in Example 1. Here the nano additive, as nano clay, at 50 ppm is incorporated into the resin during preform making. 11 Example 3 The resin composition of Example 3 is similar to Example 2 but with an increased quantity of nano additive viz.500 ppm. The results of the various trials in Examples 1 to 3 are summarized in Table-1. Table 1 PARAMETER UNIT Example-1 Example-2 Example-3 Resin Preform Resin Preform Resin Preform Weight g - 20.5 - 20.5 - 20.5 Quantity Amorphous Resin kg 12 12 12 PTN or PBN or PEN or PTT or PBT kg - - 0.5 - 0.5 - Sodium benzoate ppm 50 - 50 - 50 - Nano Clay(added duringpreform making) ppm - - 50 - 500 - Sb203, as Sb ppm 240 - 240 - 240 - CFRH additive ppm 10 - 10 - 10 - Cobalt acetate, as Co ppm 20 - 20 - 20 - RT/BT ppm 1.5/1.2 1.5/1.2 1.5/1.2 TEPA, as Phosphorous ppm 50 - 50 50 - 12 UNIT Example-1 Example-2 ExampIe-3 PARAMETER Resin Preform Resin Preform Resin Preform IV (SSP Resin) dL/g 0.760 0.730 0.762 0.732 0.764 0.735 L* CIELab 72.3 94.5 71.7 93.5 70.5 93.5 a* CIELab -0.3 -0.2 -1.2 -0.3 -1.4 -0.3 b* CIELab -2 1.7 -2.3 1.4 -2.8 1.4 DEG wt.% 1.95 - 2.19 - 2.23 - COOH meq/kg 18 14 - 14 - Glass Transition Temperature, Tg * °C 80 - 83 - 84 - Peak Crystallization Temperature, Tch* °C 147 - 143 - 142 - Melting Point, Tm* °c 254 - 264 - 264 - Haze(Optical) CIELab - 1.4 - 1.9 - 2.1 Crystallinity bydensityGradient % - 25.7 - 28.4 - 28.6 * Values are from DSC measurements. Tch is measured during second heating cycle. The values obtained for the various parameters in the three examples leads to the following inferences. 13 1. The CIE color values viz. L* and b* of the base PET resin are good and not getting affected by the various additives used to improve the barrier. 2. This is also reflected in the low haze values of the preforms indicating that the clarity is satisfactory. The preforms are further blown into 250mL CSD bottles. To assess the barrier resistance to carbon dioxide of these bottles the gas volume (GV) measurement is made. These bottles were filled with 250 ml of water (brimful volume is 280 ml) and required amount of citric acid and sodium bicarbonate were dissolved and closed with 28 mm PCO caps (plastic closures). C02 was generated in-situ in the container. Gas-volume was measured for the headspace by puncturing the PCO cap using Zahm New Style Air Tester, series 7000 supplied by Zahm and Nagel, Newyork, USA. This was taken as the initial value. These bottles were stored at 23°C, 50% RH. Two bottles were tested for GV every week and the average of these two values are given in Table - 2. Table 2 Resin usedfor thebottle Zeroth day GAS VOLUME 1st week(% Loss) 2nd week(% Loss) 3rd week(% Loss) Cold Set Example 1 4 3.25(18) 3.20 (20) 3.15(21) Example 2 4 3.75 (6) 3.65 (9) 3.60(10) Example 3 4 4(0) 3.95(1) 3.95(1) Heat Set Example 1 4 3.65 (9) 3.60(10) 3.60(10) Example 2 4 3.95(1) 3.95(1) 3.90(2) Example 3 4 4(0) 3.95(1) 3.95(1) 14 For carbonated soft drinks (CSD) in PET bottles of 500 mL and above the shelf life is determined by the % loss in CO2 during storage and the number of weeks, wherein the % loss of CO2 Table -2 clearly indicates that the resin without the nano additive and PTN or PBN or PEN (Example 1) fails to retain C02 and looses > 17% within one week particularly in cold set bottles. In heat set bottles their performance is better though not as good as Examples 2 & 3. Resins from Example 2 & 3 containing nano additives and PTN or PBN or PEN show a very favorable trend of minimum loss of CO2 in 2 weeks storage and more so with higher quantity of nano additive as seen in Example 3. The bottles made from the resin containing nano additives perform better than the one prepared from resin without nano additives. Similarly, bottles made by heat set blow molding perform better than cold set bottles. Advantages: 1. The polyesters of the present invention can be formed into variety of articles including small volume (200-500 350 mL) CSD bottles in the normal injection stretch blow molding (ISBM) machine by cold set or heat set blow molding and high barrier films by extrusion. 2. The improved resin composition of the present invention provides an enhanced improvement of barrier properties, for gases especially carbon dioxide, oxygen, nitrogen, water vapor and flavor retention. 15 3. The improved resin is suitable for monolayer high barrier PET bottle and film for packaging applications. While considerable emphasis has been placed herein on the specific resin composition and processes for making it by the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention 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 invention and not as a limitation. of R. K. Dewan & Co Applicants' Patent Attorneys 16

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