FORM 2 THE PATENTS ACT, 1970
(39 of 1970) As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Oxygen Scavenging Polyester Composition
APPLICANTS
Name : Reliance Industries Limited
Address : CIPT - Reliance Technology Group, Reliance Industries Limited, Reliance Corporate Park, 7B, Ground Floor. Thane-Belapur Road, Qhansoli,
NaviMumbai-400 701.
Nationality : Indian company incorporated under the Companies Act 1956
INVENTORS
Name : Agarwal Uday Shankar
Address : 501, Safal Aangan, Plot No 3 and 4, Union Park, Chembur, Mumbai -400071
Maharashtra India Nationality : Indian
Name : B.V.Venkatakrishnan
Address : No. 15/9 Kumaran Nagar, Kaladipet, 600 019. Chennai India Nationality : Indian

Name : Rajesh .JaIan
Address : 7678. S.S. Road, Sabzi-Mandi, Clock Tower, Delhi -110007 Delhi - India Nationality : Indian
Name : Sreekumar Thaliyil Veedu
Address : Chittothidom, Aduthila P O Payangadi, Kannur s 670303 Kerala- India Nationality : Indian
Name : Ayodhya Srinivasacharya Ramacharya
Address : FlatNo. 7 , Phoenix Co-operative Housing Society, Plot No. 23, Sector 9A , Vashi, Navi Mumbai 400 703 Maharashtra India Nationality : Indian
Name : Jain Ashwin Kumar
Address : FlatNo. B-301, Riddhi Siddhi Residency, Plot No. 53 & 53A, Sector-3, New Panvel (E), Navi Mumbai - 410 206. Maharashtra India Nationality : Indian
Name : Jadimath Shivamurthy Padadayya
Address : Madhihal,Shirstedhar galli,Dharwad-580006
KarnatakaJndia
Nationality : Indian
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed

Field of invention
The invention relates to polyester resin composition for oxygen barrier, a process for preparing such composition and articles manufactured thereof.
The invention generally relates to packaging oxygen-sensitive substances, especially food and beverage (F&B). The invention is directed towards the so-called active oxygen-scavenger type formulations rather than passive, physical gas barrier. The materials of composition are primarily condensation polymer or copolymeric substances, preferably polyesters, copolyesters and polyamides, which can be used for manufacturing packaging materials and articles, bottles for an example or any other format of packaging, in single layer or as one (or more) Iayer(s) of a multilayer packaging. These compositions have an ability to consume an amount of oxygen and thereby deplete the level of the same from the immediate atmosphere surrounding the packaged content and at ambient temperatures.
Background
Packaging in whatever form - rigid or flexible - not only serves to contain the substance inside, but is also required to prevent inward transmission of harmful substances, if any, from the outside environment. Atmospheric oxygen is one such harmful substance that reduces shelf life of the package product by promoting quicker degradation or denaturation, especially as far as packaged F&B products are concerned.
Compared with glass, the traditional packaging material for food & beverage, polymeric packaging has the advantage of lighter weight, less breakability, less consumption of packaging material for unit packaged substance and hence reduced cost. But packaging made of polymeric material generally lacks the barrier that glass could provide against inward and outward flow of gases, particularly water, carbon dioxide and oxygen. This disadvantage has greatly restricted the use of polymeric material in packaging foodstuff.
Polyethylene terephthalate (PET) is a highly used packaging material, especially for substances including but not limited to carbonated beverages and beer. It provides nearly glass-like clarity and is about 10 times as impermeant to oxygen as polypropylene, another potential choice of material in this regard. PET can also serve for almost absolute oxygen barrier for practically large lengths of shelf life, given sufficient wall thickness. However, there is always a need to reduce the cost to packaging relative to the cost of the packaged substance, wherein wall thickness reduction can contribute substantially. Wall thickness reduction, on the other hand, deteriorates effective oxygen barrier of PET and reduces shelf life of packaged product significantly, hence the need of an added oxygen barrier substance with the generic PET.
Although there are these extremely impermeable polymers like ethylene-vinyl alcohol copolymers and vinylidene-vinyl chloride copolymers available, they are not the choices of the processor as single polymer solutions for making bottles or other packages because of high cost factors. Neither are they effective as barrier when blended with PET as they are only passive, physical barriers of oxygen and can lead to leakage of barrier to oxygen through those locations in the blend morphology where the respective phase is not present. Therefore, these materials cannot be efficiently incorporated in single-layer packaging solutions. The more common solution employing of these passive barrier

materials is multiple layer packaging, where the layer of barrier is composed of a homogeneous phase of anyone of the above copolymers and the other layers are made of any other generic polymer like PET or polypropylene, which still remain less cost-effective propositions. Packages made out of multilayered structures utilizing such barrier copolymers in the core layer also need to be hermetically sealed as any inadvertently introduced oxygen would remain inside and degrade or denature the packaged product before the shelf life.
On the other hand US5300572A, US6083585A, US7049359B2, US20060202161AI, US20070088133A1, WO2005023530A1, WO2006063032A2 and WO2006132671A1 teach us the use of alternative barrier materials, called the "active oxygen barrier", which deplete oxygen by consuming it, i.e. by themselves getting oxidized by the atmospheric oxygen. The biggest advantage is that any inadvertently introduced oxygen inside the packaged environment is also consumed by the package itself, when made of packaging materials comprising these active oxygen barrier substances. US5300572A, US6083585A and US20060202161A1 disclose that unsaturated olefin copolymers, oligomers or such blocks in copolyester can act as active oxygen barrier in presence of transition metal catalysts. A transition metal in its positive oxidation state catalyzes the oxidation of the unsaturated olefin oligomer or copolymer block in presence of UV or visible light. US7049359B2, US20070088133A1, WO2005023530A1, WO2006063032A2 and WO2006132671A1 disclose that partially aromatic polyamides also act similarly as "active oxygen barriers" and their oxidation is similarly catalyzed by transition metals. One example of such polyamide - as disclosed in US7049359B2 - is a copolymer of m-xylenediamine and adipic acid (MXD6). Whether the active oxygen barrier material is the olefin oligomeric block in copolyester or the polyamide, such a material is blended with generic packaging polyester like polyethylene terephthalate (PET) to provide the final packaging solution. The resultant blend is a processable resin, which is generally referred to as the "oxygen scavenging composition". The scavenging resin forms the barrier layer, which can be employed either as a single layer packaging or as one or more layers in a multi-layer packaging where the other layers are made of generic polyester or polyolefin, e.g. PET or polypropylene (PP). US7049359B2 discloses that MXD6 is employed in 1-7 wt% in the whole formulation. Generally, the active oxygen barrier material is present in less than 10 wt% of the total scavenging resin formulation, thus providing resultant barrier polyester at a minimal cost addition to that of the generic polyester.
Whether the active oxygen barrier material inside the scavenging resin is an unsaturated olefin copolymer or an unsaturated oligomeric olefin block in a copolyester resin or a partially aromatic polyamide copolymer, a sulphonated polyester copolymer where the sulphonate pendant is having an alkali metal as counter cation has generally been employed as a compatibilizer in the prior art, for making a blend of the above with a generic polyester or copolyester, like the polyethylene terephthalate (PET).
Although WO2006132671A1 teaches that the transition metal for employing in the catalysis of the oxidation of the active oxygen barrier can be any metal from Group 3, 4, 13, or 14, the most frequently used transition metal for this purpose has been found to be cobalt (Co). Other metals like Zn have also been employed. It has been generally found that the Co metal in its positive oxidation state has been employed. US20060202161A1

discloses use of Co salt of various long chain organic carboxylic acids (or, fatty acids) for this purpose. Other Co-salts have also been disclosed. WO2006063032A2 states that even virgin Co or Zn metal can also be employed in the scavenging resin. WO2006132671AI also discloses that the same Co-salt that can be used for the condensation polymerization to synthesize the polyester can also be used afterwards for oxidation catalysis in the scavenging resin formulation.
Catalytic metals compounds have been described as oxidation catalyst in the prior art. Among the suggested compounds, metals salts of long chain fatty acids are preferred (WO 2005/023530). Cobalt-octoate is one such example. However, these long fatty acids and their metal salts are not soluble in ethylene glycol or water which are the common carriers employed for additives during polyester polymerization. For example, cobalt octoate can be sourced from market as solution in hydrocarbon solvents that are flammable. These solutions offers the possibility of incorporating cobalt octoate in polyester either by coating on polyester chips prior to extrusion while devolatilizing the solvents which demands special equipment, or by addition during commercial polymerization where the devolatilization would contaminate the recycling monomer and condensates, thus demanding additional separation process/equipment. Even if solvent free cobalt octoate or some other Co salt or oxide can be sourced, its addition during polymerization would not lead to uniform distribution in polymer as it is known in the art of polyester polymerization that salts and catalysts etc. are best added as solutions in the monomer ethylene glycol (e.g. US 2002/0169273) or in polymerization product water.
An object of the present invention is to avoid adding the transition metal catalyst that is Co or some other transition metal salt or oxide, as a separate solid powder or with an extra hydrocarbon solvent as carrier.
Prior art (US7049359) indicates that the oxygen scavenging capacity may appear only after ageing of the blend, as the oxidation catalyst may be embedded in the wrong phase, i.e. away from the scavenger polymer phase. By building the oxidation catalyst in the polar polyester copolymer, the present invention increases the possibility of contact between the catalyst therein and the scavenger polymer, because it is known in prior art that the copolyester provides the compatibilizing action by migrating towards the dispersed phase, which in the present invention would be the scavenger polymer, and resting at the interface (Polymer 2005; 46: 6706), while also reducing the dispersion size (J Appl Polym Sci 2005; 97: 1361), thus increasing available surface area of interaction between the catalyst and the oxidizable polymer.
As the oxidation catalyzing metal in the present invention is present as a chemical compound with the copolyester, it can be anticipated that the compound as a whole would not leach undesirably from the package wall into the contained F&B.

Summary of the Invention
An object of the invention is to add in the oxygen scavenging resin composition a copolyester component comprising sulphonated comonomers that are neutralized either fully by the transition metal cation or by a combination of the transition metal and alkali metal cations, instead of full neutralization by alkali metal cations alone. The said copolyester thus comprising comonomers that are suiphonate salt of the transition metal, therefore, enable incorporation of the transition metal catalyst for oxidation of the oxidizable organic polymer in a polymer-bound catalyst form instead of a small molecule form of a fatty acid salt or any other small carboxylic acid salt. The said sulphonated copolyester, along with carrying the oxidation catalyst in polymer-bound form as described, can also continue to perform as a compatibilizer for the polyethylene terephthalate and the oxidizable organic polymer if they are present as two different, incompatible phases in the formulation and requiring compatibilization by a third polymer. This also enables greater proximity of the oxidation catalyst and the oxidizable organic polymer phase as the polymer-bound catalyst becomes available at the interface.
Also disclosed is a method for preparing the sulphonated polyester copolymer in the transition metal salt form by addition of a transition metal sulfonate comonomer (carrying at least one reactive functional group for incorporation in the polyester chain) during polymerization of the polyester.
Another object of the invention is a method comprising either blending of all components or optionally copolymerizing some and blending the rest of the components in the oxygen scavenging resin composition, the final blending of components being carried out in an extrusion mixing process to formulate the active oxygen scavenging resin composition.
Another object of the invention is to prepare plastic bottles with appropriate oxygen impermeability, where the said active oxygen scavenging resin has been deployed in the construction of the wall of the bottle. All other appropriate packaging articles, like semi¬rigid and flexible packages, including bottles, cans, boxes, pouches and wraps, for preventing access of atmospheric oxygen to the product contained therein are also disclosed.
Also disclosed are methods to protect food and beverage items from degradation or degeneration by contact with atmospheric oxygen by enclosing in plastic bottles or other appropriate plastic packaging, the walls of which are made by deploying the said oxygen scavenging compositions in a single layer or in one or more layers of a multi-layer film of which the other layers are made of generic plastic materials like polyethylene terephthalate (PET), other polyester or copolyester or polypropylene (PP), polyethylene (PE) or other polyolefln polymers or copolymers.
Detailed Description of Invention
Accordingly, the present invention provides an active oxygen scavenging composition comprising following polycondensate components:
(A) a generic polyester component, including but not limited to polyethylene terephthalate (PET), made by copolymerizing:

(i) at least one member selected from the group of aromatic dicarboxylic acids comprising terephthalic acid, isophthalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, naphthalene dicarboxylic acid and cyclohexane dicarboxylic acid or the corresponding diester with a lower alcohol and their ester forming derivatives, or combinations thereof; and
(ii) at least one member selected from the group of aliphatic diols comprising ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexane diol, 8-octane diol, 1.10 decanediol, 2,2-dimethyl-l,3-propanedioI, 1,4-cyclohexane dimethanol, 1,4-cyclohexane diol, cyclobutanediol, cyclobutane dimethanol, tetramethane cyclobutanediol, diethylene glycol, polyethylene glycol, polypropylene glycol or polytetramethyiene glycol and their ester forming derivatives, or combinations thereof;
(B) an oxidizable organic polycondensate component which can be anyone or (a combination of) more of the following:
(i) a partially aromatic oligo- or poly-amide condensate capable of oxygen scavenging, including but not limited to a copolymer of m-xylenediamine and adipic acid commonly called MXD6, comprising those containing repeating units of the generic formula NH-CH2-arylene-CH2-NH-CO-alkylene-CO- wherein the preferred arylene groups are of phenylene type, particular m-phenylene, which may be substituted with alkyl groups and/or condensed with other substituted or unsubstituted aromatic rings and the preferred alkylene moieties are composed of between 1 and 10 carbon atoms, preferably n-butylene, wherein the relative viscosity of such polyamides are in the range of 1.5 to 4.5, preferably 2.0 to 3.6 (measured for solutions in 95% aqueous sulphuric acid containing 1 g of polymer in 100 cm3 solution);
(ii) a fully aliphatic oligo- or poly-amide condensate capable of oxygen scavenging, comprising those containing repeating units of the general formula -CO(CH2)nCONH(CH2)mNH- or (CH2)pCONH- or combinations thereof wherein any of n, m or p can be integers between 3 and 7, preferably between 4 and 6;
(iii) an oligo- or poly-condensate, including but not limited to a copolyester, derived from hydroxyl- or carboxyl-terminated monomeric, oligomen'c or polymeric olefin or olefin oxide segments capable of oxygen scavenging, constituted by at least one member selected from the group comprising a dicarboxylic, hydroxy-carboxylic or dihydroxy compound comprising at least one oleffmic unsaturation, wherein the number average molecular weight of such olefin-containing condensate segment is between 100 and 50,000, preferably between 500 and 5000 and most preferably between 1000 to 3000;
AND
(C) a polar co-polyester component having a certain average number of sulphonated comonomers on the backbone, wherein at least a portion of the anionic sulphonate groups are neutralized by counter-cations derived from at least one transition metal or at least one metal from Groups I-B, VII and VII-B of the periodic table, preferably including but not limited to Cu, Mn, Al. Ag, Co and Fe while the rest, if any, of the anionic

sulphonate groups are neutralized by alkali metal cations, the polar copolyester being synthesized by copolymerizing:
(i) at least one member selected from the group of aromatic dicarboxylic acids comprising terephthalic acid, isophthalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, naphthalene dicarboxylic acid and cyclohexane dicarboxylic acid or the corresponding diester with a lower alcohol and their ester forming derivatives, or combinations thereof;
(ii) at least one member selected from the group of aliphatic diols comprising ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanedioi, 1,6-hexane diol, 8-octane diol, 1,10 decanediol, 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexane dimethanol, 1,4-cyclohexane diol, cyclobutanediol, cyclobutane dimethanol, tetramethane cyclobutanediol, diethylene glycol, polyethylene glycol, polypropylene glycol or polytetramethylene glycol and their ester forming derivatives, or combinations thereof; and
(iii) either a small amount of a sulphonated monomer having at least one functional group capable of reacting with the aforesaid monomers and the polyester thereof and represented by the general formula (R)j-(S03)/ (M)m (L)n ; wherein j, /, m is an integer from 1 to 6, n is an integer from 0 to 6, M is a metal selected from Groups I-B, VII and VII-B of the periodic table, preferably including but not limited to Cu, Mn, Al, Ag, Co and Fe, L is a nitrogen , phosphorus or sulphur containing ligand selected from ammonia, an amine, pyridine, imidazole, pyrazole, triaryl phosphine, trialkyl phosphine, triaryl phosphate, trialkyl phosphate or a thiol, R is a linear or branched unsubstituted or substituted alkyl or alkenyl, an aryl or a substituted aryl carrying at least one reactive functional group;
wherein either the components (A) and (B) are optionally copolymerized while the component (C) is blended to the said copolymer, or all the components of (A), (B) and (C) are blended together, in the final composition.
The scavenging resin composition is designed in such a way that A is present in the range from 99 to 85 wt%, B from 0 to 5 wt% and C from 1 to 10 wt%, relatively to the total weight of A, B and C together.
While the polyester matrix component A comprises predominantly of a homopolymeric condensate of polyethylene terephthalate (optionally containing < 2.5% ethylene isophthalate), the active oxygen scavenging component B is a polycondensate essentially comprising an oxygen scavenging moiety that is either the partially aromatic polyamide segment or the monomeric, oligomerc or polymeric olefin-containing segment as defined above and optionally containing other condensates essentially joined together through copolymeric linkages and optionally distributed in a random fashion along the copolymeric backbone, wherein the total amount of the oxygen scavenging moiety is between 0.5 and 10 wt% relative to the total weight of A, B and C when the scavenging moiety is the partially aromatic polyamide and between 0.2 and 5 wt% when the scavenging moiety is the olefin-containing segment.
Similarly, the oxidation catalyst-bearing component C is derived from a polar, ester forming condensate essentially comprising a condensate of ethylene terephthalate and a

neutralized sulphonated monomer and optionally containing any other ester forming condensate, joined together through copolymeric linkages and optionally distributed in a random fashion along the backbone of the copolymer, vhrein the total amount of the neutralized sulphonated monomer component is from 0.01 to 1 wt% relative to the total weight of A, B and C and also wherein from 0.1 to 1 m0Ie fraction of the neutralized, sulphonated monomers are neutralized by cations derived at least one transition metal or metal from Groups I-B, VII and VII-B of the periodic table.
In a preferred embodiment, the transition metal is present between 10 and 1000 ppm -preferably 20 and 500 ppm - compared to the total weight of (A), (B) and (C) of the scavenging formulation and calculated as ppm of the metal atom.
In another embodiment of the scavenging composition, the organic oxidizable polymeric component is poly(m-xylene adipamide).
In another embodiment of the scavenging composition, the organic oxidizable polymeric component is derived from a copolyester comprising dicrboxylic acid or dihydroxy or hydroxyl-caboxylic acid comonomers or combinations thereof, the said comonomers essentially comprising at least one olefinic unsaturation.
in another pre ferred embodiment, the olefinic tmsatwation containing co-monomer of the organic oxidizable copolyester component is derived from (taconic acid.
In another embodiment of the scavenging composition, the sulphonated copolyester is a copolymer of terephthalic acid (or dimethyl terephthalate), ethylene glycol and Co-bis(5-sulfoisophthalic acid) (or the corresponding dimethyl ester), hereinafter commonly represented as Co-SIPA, wherein the pendant anionic sulphonate group is neutralized by a Co metal in its positive oxidation state (Co2+)
In a preferred embodiment, the intrinsic viscosity (IV) of the generic polyester (A) is between 0.6 and 1.0 - preferably between 0.7 and 0.85.
In a preferred embodiment, the intrinsic viscosity (IV) 0f the sulphonated polyester copolymer (C) is between 0.2 and 1.2 - preferably between 0.4 and 0.85.
Although the transition metal is introduced as counter-Qation to the anionic pendant sulphonate groups of the sulphonated polyester copolymer in the formulation of the scavenging resin composition, the said metal can be present in any form including but not limited to a metal in any positive oxidation state as the counter-cation of the anionic pendant sulphonate group, , a metal oxide, sub-oxide or Super-oxide, or a virgin metal atom (as part of Co++ may precipitate as Co metal) or combinations thereof, in the as prepared composition.
The polymer compositions of the invention can further comprise polymer(s)/copolyrner(s) which include, but are not limited to polyester, polycarbonate, polystyrene, polyolefln.
The copolymer or compositions of the invention can contain one or more conventional additives which include, but are not limited to, a colorant including a dye or a pigment, a mold release agent, an antioxidant, a flame retardant, an Antimicrobial agent, a filler, a reinforcing agent, a UV protective agent, a plasticizer, a water transporting/absorbing agent or cationic dyeability agents.

The copolymer or compositions of the invention can contain one or more conventional additives which include, but are not limited to, a colorant including a dye or a pigment, a mold release agent, an antioxidant, a flame retardant, an antimicrobial agent, a filler, a reinforcing agent, a UV protective agent, a plasticizer, a water transporting/absorbing agent or cationic dyeability agents.
According to the invention there is provided an efficient process for production of sulfonated polyester resin having I.V. of about 0.2 dl/g to about 1.2 dl/g, the process comprising:
a) esterifying and melt polymerizing at least one dicarboxylic acid or mono-esters thereof or di-ester thereof or anhydrides thereof and at least one polyol at temperature in the range of 250°C to 290°C, while adding at the beginning or during the polymerization, a sulfonated monomeric agent containing reactive functional groups capable of participating in the polymerization reaction
b) forming the solid copolyesters particles from the molten polymer there using a suitable from the melt by a known by a particle forming process such as underwater pelletizer, optionally followed by a crystallization process and a solid state polymerization process to increase the I.V.
Thus sulfonated polyester copolymer is synthesized by addition during polymerization a sulfonated monomeric agent containing reactive functional groups capable of participating in the polymerization reaction. The reactive functional group is selected from alkenyl, OH, OR, CH2OH, NH2) CHO, COC1 or COOR5 where R5 is as defined herein. During polymerization, the monomeric agent reacts with compound(s) selected from the group consisting of carboxylic acids, their salts, acid chlorides, acid anhydrides, alcohols, esters, alkenes, alkenyl benzenes in the presence of a polymerization catalyst. The polymerization catalyst is a metal or non-metal based catalyst conventionally used for polymerization reactions. In certain polymerization reactions, the compatibilizing agent can also provide the necessary catalytic activity and thus reduce or eliminate the requirement of using a separate polymerization catalyst. The polymerization reaction is carried out either as a batch process or as a continuous process. One or more comonomer, differing in the type of metal or differing in the organic part of the molecule, can be used simultaneously in the polymerization reactions. Moreover, the comonomer can be added to the polymerization mixture at any stage during the polymerization, i.e. the comonomer can be added at the beginning of the polymerization, during the polymerization or towards the end of polymerization. The comonomer can be mixed with the polymerization mixture in the solid, molten or dissolved form. A post polymerization step, such as solid state polymerization (SSP), may be required to increase the polymer molecular weight and viscosity suitable for the application such as injection molding and stretch blow molding. The comonomer can also be blended in an additional step following the polymerization. If the addition of comonomer leads to decrease in the polymer molecular weight, the molecular weight is increased by further polymerization, for example by addition of chain extenders or by polymerization in the solid state.
Concentrated master batches of the compositions may be prepared and subsequently blended (e.g. during injection molding), as portions, to additional quantities of base polymer to achieve the final desired composition. Alternatively, the blended melt of the

copolymer with other polymers is extruded to obtain polymer strands or fast quenched and then converted to chips.
The composition of the invention can optionally blended with other polymers and additives can be formed into various beverages and foods packages having oxygen barrier activity. One or more of the processes such as chips-drying, injection molding, stretch blow molding, extrusion blowing etc. can be employed for making these packages.
The oxygen transmission rate (OTR) of the articles made by the said resin of oxygen scavenging composition of the invention have values less than 1.0 cc.m~~.day"-1. preferably less than 0.2 cc.nT~.day"1 at 0.36 mm thickness of the wall of the packaging article.
Examples
The invention is further illustrated by way of the following non limiting examples. In the examples and the results that follow, the metal content of the samples was calculated from the amount added during polymerization and from the loading of the copolymerization product during injection molding. Similarly, MXD6 content of the samples was calculated from the loading of the MXD6 chips during injection molding. Intrinsic viscosity (IV) was obtained according to ASTM D4603-03 using 0.5 g/cc solution of the polymer in phenol-tetrachloroethane solvent (60:40 wt ratio, 30°C). Oxygen transmission rate (OTR) was determined for the 0.36 mm thick film cut out from the bottle using Mocon Ox-Tran 2/21 modular system at 23 C and at 752 mmHg pressure. A mixture of 98% nitrogen and 2% hydrogen was used as carrier gas and 100% oxygen was used as the test gas.
Example 1: Synthesis of comonomer
128.9 g of 5, sulfo dimethylisophthalate (having the structure: H4SO3 - C6H304,) was dissolved in 2222.7 g ethylene glycol (EG). 58.58 g of Cobalt acetate (CoAc2.4H20) was added and heated for I hr from 20 to I40°C while employing a condenser to collect the by product acetic acid, leaving cobalt sulphonate of dimethylisophthalate (CoDMS2) solution in EG. The completion of the reaction was indicated from an increase in pH.

Example 2: Preparation of copolymer product
Slurry of purified terephthalic acid (6 kg) in ethylene glycol (4.5 kg) was esterified for 3.5 hrs up to 260 C at 2 bar nitrogen pressure. The C0-DMS2 solution of Example 1 (containing 13.88 g Co) was dissolved in ethylene glycol and added to the molten esteriflcation product. After an interval of 20 minutes, antimony trioxide catalyst (300 ppm Sb in PET) dissolved in ethylene glycol 250 ml was added. The mixture temperature was increased to ~ 285 C, while gradually reducing the pressure over 45 minutes to 1 mm of Hg to obtain the polymeric product.
Example 3: Preparation of sulfonated copolymer
The copolymer product obtained in example 2 was extruded out of the reactor in the form of a strand, quenched in a water bath and sliced into chips containing 2000 ppm of cobalt. The intrinsic viscosity of the polymer was determined as 0.42 (ASTM D4603). The copolymer chips were crystallized at 140 °C in air oven, and then subjected to SSP at 200 °C for 32 hr to raise the intrinsic viscosity to 0.70.
Example 4: Manufacture of barrier polyester bottles with 200 ppm Co
0.8 kg of the sulfonated copolymer chips of example 3, and 0.4 kg of MXD6 chips and 6.8 kg of base polyester (poly(ethylene terephthalate-co-ethylene isophthalate), IV = 0.80 dL/g) were tumble mixed, dried at 150 °C for 6 hr, and injection molded using 2 cavity Arburg injection molding machine (Model Allrounder 420C) operated at cylinder temperature of 275-280 °C and runner temperature of 290-287 °C, into 48 g perform. These performs were blown into bottles of 1.5 L volume using SIDEL SB01 single cavity blow molding machine.
Example 5: Manufacture of polyester bottles with MXD6
0.4 kg of MXD6 chips and 7.6 kg of base polyester (poly(ethylene terephthalate-co-ethylene isophthalate), IV = 0.80 dL/g) were tumble mixed, dried at 150 °C for 6 hr, and injection molded using 2 cavity Arburg injection molding machine (Model Allrounder 420C) operated at cylinder temperature of 275-280 °C and runner temperature of 290-287 °C, into 48 g perform. These performs were blown into bottles of 1.5 L volume using SIDEL SB01 single cavity blow molding machine.
Example 6: Manufacture of'control' polyester bottles without Co and MXD6
8 kg of base polyester (poly(ethylene terephthalate-co-ethylene isophthalate), IV = 0.80 dL/g) were dried at 150 °C for 6 hr, and injection molded using 2 cavity Arburg injection molding machine (Model Allrounder 420C) operated at cylinder temperature of 275-280 °C and runner temperature of 290-287 °C, into 48 g perform. These performs were blown into bottles of 1.5 L volume using SIDEL SB01 single cavity blow molding machine. The OTR value was found to be 0.034 cm3.m"2.day"1 measured for film thickness of 0.36 mm.