FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE
Specification
(See section 10 and rule 13)
BARRIER RESINS
FUTURA POLYESTERS LIMITED
an Indian Company
of Paragon Condominium, 3 rd floor, Pandurang Budhkar Marg,
Mumbai 400 013, Maharashtra, India
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

This invention relates to barrier resins.
This invention envisages naphthalate based barrier resins comprising (i) Polytrimethylene Naphthalate (PTN) or Polypropylene Naphthalate (PPN), (ii) Polytetramethylene Naphthalate or Polybutylene Naphthalate (PBN), (iii) the copolyesters and alloys / blends with PTN and (iv) the copolyesters and alloys / blends with PBN.
In particular, this invention relates to a process for manufacturing barrier resins.
This invention envisages processes for manufacturing barrier resins containing Polytrimethylene Naphthalate (PTN) or Polypropylene Naphthalate (PPN), Polybutylene Naphthalate (PBN) and their copolyesters and alloys / blends with PBT, IPA and the like having nil acrolein or tetrahydrofuran (THF) content resulting in excellent Global Migration compliance of final products such as films or containers made from the resin.
Further this invention envisages processes which apart from several other advantages in down stream processing also has advantages in packaging end use.
PET resins are widely used in the food packaging industry, and their applications in bottles and films are well known. PET bottles have a large market share in the carbonated soft drink (CSD), fruit juice and bottled water sectors. These products have a shelf life of 8-12 weeks, and over this period the gas permeability properties of PET are sufficient. However, there has also been an ever increasing demand from CSD and sparkling water producers for shelf life in the range of 18-24 weeks. For the alcoholic beverages like beer and oxygen sensitive juices are much more vulnerable to oxygen and carbon dioxide diffusion either into or out of the bottle.
When this sensitivity to migrating gases is combined with the need for a longer shelf life, it is necessary to improve on the gas permeability properties of PET. To overcome the excessive gas ingress the bottle industry manufacturers have several options. One of the options is that the bottles can be made from a polyester with lower gas permeability, such as polyethylene naphthalate (PEN) but these are considered commercially unviable. In most cases when PEN is combined with PET, these materials do not reduce the gas permeability sufficiently. Developments are
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continuously taking place to overcome these problems in a cost effective manner. Advances in multi-layer and surface-coating technologies are well known apart from the utilization of recently emerging nano composite technology.
The simplest and cost effective route to a barrier PET bottle for applications like beer or long shelf life CSD / Sparkling water is a monolayer polyester structure. This approach would require blending a barrier additive or Oxygen Scavenger or both, with PET. Converting beer from glass to PET is a daunting challenge, requiring tunnel pasteurizability, apart from a barrier against carbon dioxide egress and oxygen ingress, and retaining clarity and strength. This methodology stands to benefit from promising new barrier materials such as nylon-based nanocomposites and "passive-active" barrier systems. The latter are dual-acting formulations of a passive barrier material and an active oxygen scavenger that blocks O2 entry and also absorbs O2 from the head space and contents. PEN, a cousin of PET, typically delivers a five-fold improvement in both C02 and 02 barrier versus monolayer PET, along with higher heat resistance and good clarity. PEN has a Tg of 122 C, far exceeding that for PET, thereby allowing PEN blend monolayer bottles to be pasteurized. Though PEN as such is far more effective as a passive barrier compared to PET, due to its high cost and processing limitations, other polyester blends with PET are utilized in demanding applications where its performance needs improvement.
Other closely related polyesters to PEN are PTN and PBN whose permeability coefficients for O2 and CO2 are far superior and the transmission rates of these gases are considerably less when compared to the conventional packaging films. Based on this PTN or PBN as such or at lower blend levels with PET or other polyesters are found to have excellent passive barrier properties for specialized applications with cost effectiveness. It is also possible now to substitute PTN with some percentage of PBN or PBT or vice versa and use the blend to derive similar or superior benefits as these PTN and PBN alloys will have excellent barrier property towards gases.
While manufacturing PTN, due to the usage of PDO as one of the raw materials, acrolein is always generated in the process. The formation of
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acrolein is due to the dehydration of PDO similar to DEG formation from EG in the PET processing.
Acrolein is considered to be a contaminant and it negatively affects the application of PTN while processing their melt at high temperatures particularly in containers for sensitive beverages like beer, fruit juices etc., like what acetaldehyde is with water or even worse. It would therefore be desirable to produce PTN with an inherent stability against acrolein generation by a process wherein its formation is minimized by specific additives.
The presence of -COOH end groups also favors the formation of acrolein. This can be minimized by reducing the -COOH end groups by using appropriate special additives. In a similar way the formation of tetrahydrofuran (THF), in addition to acrolein, during the synthesis of PBN also suffers from limitation in application as above; like PTN, this also can be suppressed to a great extent by the special additives.
As of now there is no known commercial production of this PTN and PBN polymer resin and only articles of compounded polyesters are reported in the market mostly for non food uses. There are a few references available wherein PTN, PBN and / or its copolyesters have been used for making fiber and films and fuel hoses but no information is reported on the acrolein or THF content in the patents / prior art.
Patent GB1115767 deals with several block copolyesters consisting of a crystallizable polyester and a rubbery polyester and PTN is one of the many crystallizable polyesters utilized.
Patent GB1165312 deals with helically crimpable composite staple fibres comprising two polymeric components. Of the several polyester components PTN also find a place.
U.S.Patent 6525165 B1 is on laminated aromatic polyester films wherein PTN is one of the constituents. Only laboratory scale preparation of PTN has been given as an example and no details are available about the physical properties of the polymer.
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However there is a mention about their color in terms of the expression that 65 < L-b and b < 10 where L and b are color values by Lab method which indicates the polymer color is not in the satisfactory range. This could be because of the exclusive usage of titanium tetrabutoxide as the catalyst. There is mention about the permeabilities of oxygen and moisture - PTN film is ~ 6 times less permeable to moisture and oxygen when compared to PET film. There is no mention about acrolein, thermal stability, tunnel pasteurizability and recyclability of the multiplayer products.
U.S.Patent Application 20030143397 describes copolyester fiber having resistance to both hydrolysis and fatigue from flexing and capable of withstanding long term continuous usage at high temperature and humidity. One of the components used in the copolyester is PTN. No information is given about the process of making PTN. Japanese Patent 2003320522 provides a method for producing PTN composition which uniformly disperses inert particles which gives surface smoothness for film application.
U.S.Patent 6740402 is on Polyester fiber comprising a copolyester of PET and PEN along with 1,4-Cyclohexanedimethanol (CHDM) as a glycol modifier. Limited information is given for the laboratory preparation of PTN and its copolyesters and no details on the physical properties of the polymer.
Though there are number of Japanese patents on the application of PBN, primarily for under the hood automotive fuel hoses, there is hardly any information on the synthesis of PBN.
Objects of the Invention:
One of the objects of this invention is to establish a manufacturing process for producing a more efficient passive barrier resin viz. PTN and PBN or their alloy/ blend with PBT, IPA or their other copolyesters meeting the requirements of food contact applications for film and container packagings, with the latter suitable for hotfill and tunnel pasteurization.
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Another object of this invention is to carry out the process in a batch plant, comprising two or three reactors, and get the amorphous polymer with I.V. in the range of 0.40 to 0.70.
Another object of this invention is to make use of catalysts as such or a combination
of catalysts comprising antimony compounds, calcium, zinc, manganese or cobalt compounds and titanium or tin based compounds.
One more object of the invention is to optimize the composition of the catalysts to get good color of the polymer as measured by the CIE 'L', 'a', and 'b' values.
Yet another object of the invention is to improve the color of the polymer by using a combination of Cobalt compounds and toners.
Another object of this invention is to use a specific phosphorous based heat stabilizer which will reduce the extent of thermal degradation possible in this polymer.
Yet another object of this invention is to produce the PTN and PBN resin with appropriate additives which will reduce the generation of acrolein or THF in the resin during its subsequent processing.
One more object of this invention is to use specific additives like alkylene carbonates, methoxides and phosphates which will reduce the -COOH end group content in the PTN or PBN resin which also will facilitate in reducing the formation of acrolein or THF. The lower -COOH end groups also ensures high thermal and hydrolytic stability of the resin.
Another object of this invention is to establish a solid state polymerization process by which the amorphous polymer of I.V. 0.40 to 0.70 can be increased to 0.60 to 1.0.
Yet another object of this invention is to produce the SSP resin of PTN or PBN having acrolein or THF content below the detectable limit.
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Another object of this invention is to produce the PTN and PBN based barrier resins with added fast reheat additive which helps in productivity increase when the resins are used for blowing bottles.
One more object of this invention is to produce the PTN or PBN based barrier resins with superior barrier performance by incorporating nanocompounds or otherwise.
Yet another object of this invention is to produce the PTN or PBN based barrier resins and enhance the barrier property by the addition of nucleating agents.
In the case of PBN the invention is the enhancement of the crystallinity rate beyond PTN and yet control it to deliver clarity and transparency in the film / container free from haze.
In this invention thermal stabilizers, antioxidants and special additives are used while making PTN, PBN or its blends to reduce the formation of acrolein and THF. The special additive also helps in reducing the specific consumption of PDO or BDO and also increases the thermal stability of the resins. Thermal stabilizers used are phosphorous based compounds like the thermally stable organic base types from the group consisting of tetraalkyl phosphonium hydroxides, tetraorganophosphonium carboxylic acid salts or a mixture of these. The antioxidants comprise compounds like hindered phenols. The special additives include monovalent aromatic hydroxy compounds and their haloformates, monovalent carboxylic acids and their halide derivatives, carbonic acid derivatives like ethylene carbonate, and compounds of aromatic anhydrides and dianhydrides.
What is envisaged in accordance with this invention is a barrier process and a manufacturing process in a batch reactor to produce Polytrimethylene Naphthalate (PTN) or Polypropylene Naphthalate (PPN), Polybutylene Naphthalate ( PBN) or other copolyesters by reacting a paste of Naphthalene Dicarboxylic Acid (NDC) in Propylene glycol or 1,3-Propane Diol (PDO) and Butylene Glycol or 1,4-Butane Diol(BDO) at appropriate molar ratios to produce esterification compounds comprising bis (beta-hydroxypropyl) naphthalate and bis(beta-hydroxybutyl) naphthalate or low molecular weight polymers thereof and polycondensing the said resultant esterification compounds to produce polypropylene or polybutylene
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naphthalate polymers. Apart from the PTN and PBN homopolymers the resin composition for example can be of (i) 85% PTN and the balance 15 % is a composite of PBN/IPA/PET/PBT or (ii) 85% PBN and the balance is a composite of PTN/IPA/PET/PBT.
The esterification and polycondensation are, typically, carried out in the presence of a at least one catalyst selected from a group of catalysts consisting of Calcium, Zinc, Manganese or Cobalt compounds, Antimony, Titanium , and Tin based compounds. Tin based compounds are preferred as they give advantages in lowering the specific consumption of PDO and improve the mechanical properties of the products.
Advantageously, Phosphorous based heat stabilizers, special additives and color improving agents like Cobalt compounds and toners are also be added in the reaction at an appropriate stage. The resulting polymer resin has an I.V. in the range of 0.4 to 0.7 with good color values as measured by CIE 'L' 'a' and 'b' values.
To improve the barrier property of the resin special nanocompounds like nanoclays and nanosilica are included in the resin. Inclusion of nanaocompounds also help in increasing the mechanical properties. Incorporation of fast reheat additives like tungsten oxide as a cocatalyst is advantageous when the resin is used for molding containers as the fast reheat additive reduces the reheat time of the preforms prior to blowing. In addition to the fast reheat property this cocatalyst enables better quality containers in terms of clarity, crystallinity and mechanical properties. The fast reheat additive also increases the polycondensation rate during SSP resulting in increased productivity and resin with improved properties.
If required additional nucleating agents such as sodium based organic compounds like sodium benzoate or sodium salicylate or copolymer blocks of PBT (upto 12 mole %) are included to further improve the barrier property brought out by the enhanced crystallinity of the resin.
To improve the melt strength multifunctional diols such as pentaerythritol, dipentaerythritol, trimellitic anhydride, pyromellitic anhydride etc. can be incorporated upto a maximum of 5000 ppm.
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In accordance with a preferred embodiment of the invention suitable Oxygen Scavengers are incorporated in the resin depending on its use for containers meant for storing beverages like beer and juices.
The process of the present invention allows for the preparation of PTN and its other blends, preferably, in a batch process and to maximize the manufacturing efficiency. Ultimately, it is possible to increase the productivity of the PTN polymers and their blends and to obtain high quality PTN with reduced generation of acrolein since the method of the present invention has an effect of minimizing side products of polymerization by reducing the amount of propylene glycol considerably, utilizing a combination of catalysts, using Cobalt compounds and toners to improve the polymer color, a phosphorous based heat stabilizer, a special additive and shortening the reaction time of the esterification and polycondensation reaction.
Description of the Invention:
The present invention provides a manufacturing process for producing amorphous PTN, PBN and its blends of I.V. in the range of 0.04 to 0.05 using a batch reactor "consisting of two or three reactors. Appropriate quantities of NDC, PDO and BDO, the required amount of special additives and cobalt compound and toners as well as the required other additives like nanocompounds, fast reheat additive, nucleating agents etc. are charged to the batch reactor while maintaining the specific mole ratio of NDC:PDO and BDO. Esterification is carried out in the Esterfier at 190 to 250 °C, preferably at 220°C, in presence of catalysts like calcium, zinc, or manganese compounds and the by product methanol is removed by distillation. Other known conventional process utilizes esterification temperatures upto 250°C. In this invention with lower processing temperatures, superior thermal stability is achieved as evidently seen also by lower -COOH end groups i.e. ~ 3 instead of the normal high of ~ 15 meq/kg. At the end of the esterification low molecular weight oligomers of bis (betahydroxypropyl) or bis(betahydroxybutyl) naphthalates are formed. This low molecular weight melt is transferred to a poly reactor, in the case of a two reactor system, via a 20 micron filter and polymerization catalysts consisting of antimony, titanium or tin compounds either alone or as a combination and phosphorous based heat stabilizer are added. In the case of a three reactor system the low molecular weight melt is transferred to a second pre-poly reactor where the residual
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esterification and the initial poly-condensation takes place. Subsequently the pre-polymer melt is transferred to the poly-condensation reactor via a 20 micron filter. The polycondensation is carried out in the temperature range of 230 to 265 °C, but preferably at 240°C, under low pressure. Here again other conventional processes use a maximum of 280°C which is not desirable for a good quality resin of good color. After the desired I.V. is reached the amorphous polymer melt is extruded under nitrogen pressure and converted into pellets. The amorphous polymer of I.V. 0.40 to 0.50 is converted to I.V. of 0.50 to 1’.0 by pre-crystallization followed by Solid State Polymerization.
Example: 1 - Process of Making Barrier Improved PTN and PBN
Process of Making Barrier Improved PTN and PBN
About 9.5 kg of NDC and 4.2 kg of PDO or BDO are charged into an esterification reactor keeping the mole ratio NDC:PDO or BDO between 1:143. 1.8 g Manganese acetate (40 ppm as Mn) and 1.7 g Cobalt acetate (40 ppm as Co) are added as esterification catalysts. 0.1 g (10 ppm) of the clear fast reheat additive, 100 g (10000 ppm) of nano clay (particle size 50 to 350 nm) and 2 g of Sodium Benzoate (200 ppm) of the nucleating agent are added as needed. The esterification is carried out at 220°C, for a period of ~ 6 hours and methanol is collected as the byproduct. The prepolymer formed is transferred to a poly reactor through a 20 micron filter. 4.2 g polymerization catalyst consisting of a Tin compound viz. dibutyl tin oxide is added such that its ppm is 200 and subsequently phosphorous based heat stabilizers . 0.7 g Orthophosphoric acid (OPA) and 1.4 g Triethylphosphonoacetate (TEPA) are added such that the combined phosphorous content is 40 ppm. [By using the organic tin based compounds, instead of the conventional Sb, Ti, etc., superior color is obtained in the resin.] The polymerization is conducted at very low pressure ( < 1mm Hg absolute) at 240°C, with a process time of about 4 hours. After reaching the required kilowatt of the reactor agitator 0.5 g Tetrabutylphosphonium Acetate (about 50 ppm) is added as a thermal stabilizer, along with Ethylene Carbonate 50 g (about 0.5%) the special additive for acrolein suppression are added and allowed to interact thoroughly with the melt. The amorphous polymer melt is extruded under nitrogen pressure and collected as pellets.
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Example 1A The process is the same as example 1 except that [ 40 ] ppm Triethylphosphonoacetate (TEPA) is added as the heat stabilizer.
Example IB The process is the same as example 1 except that- [ 10000 ] ppm nanosilica (particle size 60 to 80 nm) is added as the nucleating agent.
Example 1C The process is the same as example 1 except that [ 7000 ] ppm of Sodium Phosphate is added as the THF suppressing agent.
Example ID The process is the same as example 1 except that [ 7000 ] ppm or 70 g of Sodium Methoxide or Phosphate (about 0.7%) is added for THF suppression,
Table - I summarizes the important characteristics of the amorphous PTN and PBN polymer.
TABLE-I : Properties of Amorphous PTN & PBN

Sl.No. PARAMETER UNIT VALUE
PTN PBN
1. Intrinsic Viscosity d/g 0.38 0.73
2. Carboxyl Number meq/kg 2 5
3. Dipropylene Glycol Wt.% 0.08 -
4. Acrolein or THF ppm 3.5 5.1
5. L* amorphous/crystalline CIE 55/81 80/82
6. a* CIE -1.0/-1.7 -2.4/ -1.5
7. b* CIE -1.8/-1.1 -0.9/ -0.1
8. Tg °C 80.7 -
9. Tm °C 205 241
10. TCh °c 167 -
Note: Tg - Glass transition temperature
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Tm - Melting point
TCh - Cold crystallization temperature in the second heating cycle
(The above three parameters are from DSC thermal analysis
measurements)
The amorphous PTN and PBN are upgraded to higher I.V. by solid state polymerization (SSP) which involves a procedure specially developed and very different from the usual procedure followed for PET SSP. The amorphous resin is precrystallised at 140°C in a fluid bed precrystallizer. The cooled precrystallized PTN or PBN chips are transferred to a tumbling dryer and the chips temperature increased to 80°C with nitrogen bleeding on and maintained for 2 hours at this temperature. Subsequently the temperature is increased to 150°C and pressurized with nitrogen at 1.0 bar g and maintained for 2 hours under this condition. Then the pressure is released and the dryer is evacuated to a pressure level of 1.0 mbar and simultaneously the chips temperature is increased to 185°C and maintained at this temperature till the desired I.V. is reached. Details of the SSP studies are given in Table - II and table -HI
TABLE-II - PTN SSP PROPERTIES

PTN I.V. dl/g Acrolein, ppm L* a* b* Tg Tm
Amorphous 0.432 3.4 57 -0.8 -1.6 80.7 205.9
Feed Resin
Final SSP 0.590 Nil 73 -1.5 -1.0 79.3 202.5
resin (Belowdetectablelimit)
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TABLE-III - PBN SSP PROPERTIES

PBN LV. dl/g THF, ppm L* a* b* Tg°C Tm °C
Amorphous Feed Resin 0.734 5.2 81.8 -2.4 -0.9 241
Final SSP resin 0.840 <.01 82.3 -1.5 -0.1 241
Similar results are obtained when PTN or PBN are partly substituted by PBT or other polyesters and their copolyesters.
The PTN or PBN and their blends can be used for mono layer and multi layer container applications. The containers are tunnel pasteurisable due to the built in thermal stability and recyclable by conventional methods. The resin gives a wider processing window during injection stretch blow molding. In the multi layer containers no tie layer is required and there is no delamination of layers due to the 'all polyester' composition of the container.
Example: 2 - Barrier Improved PTN in Multilayer Container Application
Barrier improved PTN as synthesized per recipe in Example 1 is used for injection molding 20.0 g multilayer preforms with PCO 28 neck finish. Barrier improved PTN is used as the core/middle layer at 3% level on the overall weight of the preform. The outer and inner layers consists of the normal PET of LV. ~ 0.84 dl/g. The performs are preheated between 98 and 115°C and stretch blow molded in a Sidel SBOl stretch blow molding machine. The resulting 20 g, 300 ml container has excellent clarity and resists delamination. The CO2 loss from these multiplayer containers are checked using a GMS equipment and compared with a similar container made from PET alone (monolayer) without the middle barrier improved PTN layer. The time for 10% loss of CO2 from its initial 4 Vol. is established for these containers. Table IV gives the details
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TABLE - IV CQ2 Loss % in Multilayer Containers

SERIAL No. CONTAINER DETAILS No. OF WEEKS BEFORE 10% LOSS OF co2
1. Monolayer PET Bottle 5
2. Monolayer PEN Bottle 22
3. Multilayer PET/MxD6 (10%) 15
4. Multilayer PET/EVOH (10%) 20
5. Multilayer PET/PTN 3%/PET 18
Expressing it differently the monolayer PET bottle has a CO2 egress of 1.60 ml/day and the PET/PTN/PET multilayer bottle has an egress of only 0.5 ml/day.
The O2 permeation through these barrier improved PTN multiplayer bottles also shows a similar decreased trend in permeation like CO2. The O2 ingress in ml/day for a monolayer PET bottle is 0.025 whereas the multilayered bottle with barrier improved PTN shows an O2 ingress of only 0.0003 ml/day.
The above results are from one typical example. The thickness of the barrier layer can be controlled to produce the desired shelf life in different of applications like tomato products, juices, flavored beverages etc.
The purpose of the barrier resin is to increase the gas barrier property when compared to PET. Small containers (eg.for CSD) typically require a shelf life increase by a factor of 2 to 4 times that of similarly sized monolayer PET containers.
A higher level of performance enhancement can be achieved by co-injecting a material that has both gas barrier property and oxygen scavenging characteristics.
Similar results are observed when PTN is substituted in Serial No.5 of Table IV with barrier improved PBN.
Example 3: - Barrier Improved PTN in Monolayer Container Application
While multilayer technology is still the most common method of extending the barrier properties, it has the disadvantage of being more expensive to manufacture.
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Multilayer containers of dissimilar polymers make recycling more difficult. Shielding the high barrier layer is a must as many times they are not suitable for food contact. Also delamination can occur between different layers. These limitations are overcome by the development of alternative packaging systems based on monolayers. These barrier improved resins can be processed standard monolayer PET equipments and are very cost effective.
A typical normal PET monolayer bottle of 400 ml with an initial CO2 Gas Volume (GV) of 4.2 will lose 10% of C02 in about 3 weeks time.
The Example 3 here is similar to Example 2, except that the injection molded preform and stretch blow molded bottle is monolayer comprising the barrier improved PTN instead of the multilayer. 20 g preforms are converted to 300 ml bottles. The preforms are preheated to 100°C and the bottle mold is kept at room temperature. The monolayer bottles are having good clarity with color values L* = 92.5, 'b' = 2.6 and Haze % ~ 2.6. The following table gives the CO2 permeation rates of the normal PET bottle vs. the monolayer bottles made with the barrier improved PTN.
TABLE - V CO2 Permeation Rates in Monolayer Containers

SERIAL CONTAINER C02 LOSS C02 C02 BIF
No. DETAILS RATE PERMEATION PERMEATION
(%/WEEK) ml/day/bar/bottle ml/day/bar/cm2 x 10-3
1. PETMonolayerBottle 2.58 1.88 4.23 1
2. BarrierImproved PTN Monolayer Bottle 0.91 0.66 1.49 2.84
Measurements are carried out in a GMS equipment. The results clearly indicate the good barrier property of improved PTN resin in monolayer applications.
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Similar results are observed when PTN is substituted in Serial No.2 of Table V with barrier improved PBN.
The PTN, PBN resin and their copolyester combinations are found to be acceptable in
the trials of (i) injection / coinjection molding to mono and multi layer preforms (ii) stretch blow molding of mono and multi layer containers (iii) extrusion / coextrusion of mono and multi layer films.
Thus the present invention provides a process in a batch reactor, comprising two or three reactors, for producing polytrimethylene or polypropylene naphthalate (PTN or PPN) and Polybutylene Naphthalate (PBN) polymers or their blends with other polyesters like PBT,PTT etc. with reduced presence of acrolein and THF by esterifying Naphthalene Dicarboxylic Acid Dimethyl Ester (NDC) or derivatives thereof with Propylene Glycol or 1,3-Propane Diol (PDO) and Butylene Glycol or 1,4-Butane Diol (BDO) in presence of catalysts.
Following are the uniqueness in our invention of making the naphthalate barrier resins comprising PTN, PBN, Copolyester alloy / blends with PTN or PBN:
• Synthesis of the resins by Tin based catalyst resulting in better color
• Crystalline, Clear , Fast reheat resins with below detectable limits of Acrolein and THF resulting in excellent compliance of global migration in the containers
• The resins have superior thermal stability and excellent barrier property due to the enhanced crystalline nature brought by special additives
• The high crystallinity in these resins make them suitable for hot filling and tunnel pasteurization of the containers
• The morphological changes brought out by the additives results in a wider and flexible operating window in film extrusion / coextrusion, extrusion blow molding, and injection / coinjection stretch blow molding viz. 85 to 120°C
• Recyclability of the containers by known conventional methods.
While considerable emphasis has been placed herein on the reactions and the interrelationships between the ingredients of the composition of the preferred system,
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it will be appreciated that many systems can be made and that many changes can be made in the preferred system without departing from the principles of the invention. These and, other changes in the preferred system as well as other systems in accordance with this 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.
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We Claim:
[1] A barrier resin comprising at least one naphthalate based first resin selected from a group of resins consisting of Polytrimethylene Naphthalate (PTN) or Polypropylene Naphthalate (PPN), Polytetramethylene Naphthalate or Polybutylene Naphthalate (PBN), and the copolyesters and alloys thereof, and at least one compound selected from a second group consisting Polytrimethylene Naphthalate (PTN) or Polypropylene Naphthalate (PPN), Polytetramethylene Naphthalate or Polybutylene Naphthalate (PBN), IP A, PET and PBT, not being a resin occurring as the first resin; said barrier resin being devoid of acrolein or tetrahydrofuran (THF); and having a global migration compliance with additive < 7000 ppm, the ratio of the two resins in the final composition ranging from 50:50 to 1:99 and preferably 85:15 ; said barrier resin having an intrinsic viscosity ranging between 0.60 to 1.00.
[2] A barrier resin as claimed in claim 1, which includes at least one esterification catalyst and one polycondensation catalyst selected from a group of catalysts consisting of antimony compounds, calcium, zinc, manganese or cobalt compounds, titanium and tin based compounds and the quantity of catalyst is in the range of 30 ppm to 300 ppm as metals.
[3] A barrier resin as claimed in claim 1, in the resin includes Cobalt compounds (20 to 60 ppm as Co) and toners (0.1 to 3 ppm).
[4] A barrier resin as claimed in claim 1, which includes a fast reheat additive in the range of 5 ppm to 20 ppm.
[5] A barrier resin as claimed in claim 1, which includes a heat stabilizer in the range of 20 ppm to 60 ppm as Phosphorous
[6] A barrier resin as claimed in claim 5, in which the heat stabilizer is phosphorous based.
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[7] A barrier resin as claimed in claim 5, in which the heat stabilizer is phosphoric acid, tetraalkyl phosphonium hydroxide or a tetraorganophosphonium carboxylic acid salt or a mixture of these.
[8] A barrier resin as claimed in any one of the preceding claims, which includes particles typically nanoclay particles and/or nano silica particles ranging from 5000 ppm to 15000 ppm and having a particle size ranging form 40 nm to 500 nm.
[9] A barrier resin as claimed in any one of the preceding claims, which includes nucleating agents.
[10] A barrier resin as claimed in any one of the preceding claims, which includes antioxidants.
[11] A barrier resin as claimed in claim 10 in which the anti oxidant is at least one hindered phenol.
[12] A barrier resin as claimed in any one of the preceding claims, which includes at least one special additive , selected from a group of additives consisting of monovalent aromatic hydroxy compounds and their haloformates, monovalent carboxylic acids and their halide derivatives, carbonic acid derivatives like ethylene carbonate, and compounds of aromatic anhydrides and dianhydrides.
[13] A process for making a barrier resin as claimed in any one of the preceding claims, which includes the steps of:
[i] mixing appropriate quantities of NDC, PDO or BDO in an esterifier;
[ii] adding the required amounts of esterification catalyst, special additives, cobalt compounds and/or toners, nano particles, fast reheat additive and nucleating agents;
[iii] the above composition is subjected to esterification between 200 and 245°C, but preferably at 220°C for a period of ~ 6 hours.
[iv] the prepolymer formed is transferred to a polycondensation reactor;
[v] appropriate quantities of the polycondensation catalyst is added followed by the required quantity of phosphorous based heat stabilizer;
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[vi] polycondensation is conducted at very low pressure (< 1mm Hg absolute) in the temperature range of 230 to 270°C, but preferably at 240°C, with a process time of ~ 4 hours;
[vii] after reaching the required melt I.V., the thermal stabilizer and the special additives for acrolein and THF suppression are added and allowed to interact with the melt;
[viii] the amorphous polymer melt formed is extruded under nitrogen pressure and collected as pellets; and
[ix] the dried amorphous pellets are subjected to solid state polymerization (SSP) to increase the I.V. to a predetermined level.
[14] A process for making a barrier resin as claimed in claim 13, in which the prepolymer formed is transferred to a polycondensation reactor via a 20 micron filter.
Dated this 22nd day of January 2007.

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ABSTRACT
A barrier resin comprising at least one naphthalate based first resin selected from a group of resins consisting of Polytrimethylene Naphthalate (PTN) or Polypropylene Naphthalate (PPN), Polytetramethylene Naphthalate or Polybutylene Naphthalate (PBN), and the copolyesters and alloys thereof, and at least one compound selected from a second group consisting Polytrimethylene Naphthalate (PTN) or Polypropylene Naphthalate (PPN), Polytetramethylene Naphthalate or Polybutylene Naphthalate (PBN), IPA, PET and PBT, not being a resin occurring as the first resin; said barrier resin being devoid of acrolein or tetrahydrofuran (THF); and having a global migration compliance with additive < 7000 ppm, the ratio of the two resins in the final composition ranging from 50:50 to 1:99 and preferably 85:15 ; said barrier resin having an intrinsic viscosity ranging between 0.60 to 1.00.