Title of Invention

POLYESTER COMPOSITION HAVING IMPROVED HEAT STABILITY

Abstract The present invention provides modified polyester composition of Polyethylene terephthalate (PET) (Hot PET resin) comprising metal salts of alkali and alkaline earth metal containing nucleating agents to provide a resin with high crystallization rates and yielding bottles with higher percentage crystallinty. The present invention also provides a process for the preparation of said composition and a method of making the modified PET resin with an increased glass transition temperature suitable for Hot Fill applications up to 88 °C and without the need for neck crystallization prior to hot filling. The hot fill containers made from this modified resin show no significant change in the shape or other characteristics of the bottle and show a shrinkage of < 1 % when compared to standard PET bottle.
Full Text Abstract
The present invention provides modified polyester composition of Polyethylene terephthalate (PET) (Hot PET resin) comprising metal salts of alkali and alkaline earth metal containing nucleating agents to provide a resin with high crystallization rates and yielding bottles with higher percentage crystallinty. The present invention also provides a process for the preparation of said composition and a method of making the modified PET resin with an increased glass transition temperature suitable for Hot Fill applications up to 88 °C and without the need for neck crystallization prior to hot filling. The hot fill containers made from this modified resin show no significant change in the shape or other characteristics of the bottle and show a shrinkage of
FORM-2 THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE
Specification
(See section 10 and rule 13)
POLYESTER COMPOSITION HAVING IMPROVED HEAT STABILITY
FUTURA POLYESTERS LIMITED
an Indian Company
of Paragon Condominium, 3rd 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.

FIELD OF THE INVENTION
The present invention relates generally to crystallized polyester compositions for manufacturing heat set containers, typically PET bottles for hot fill applications.
BACKGROUND OF THE INVENTION
PET bottles are widely used for food and beverages, and also for non-food materials. The preference for PET amongst the other plastics is mainly due to its optically clear appearance, chemical and thermal stability and ease of stretch blow molding. But one of the disadvantages is its non suitability for hot fill applications as the maximum fill temperature for the normal bottle grade resins having a glass transition temperature (Tg) of- 70°C is generally about 60 to 65°C only.
Advantageously, Polyethylene Naphthalate (PEN) polyester may be used for hot fill application due to its higher Tg, but in addition to the polymer being expensive it requires special designing of the preforms as the axial/hoop stretch ratios are different. Though lower cost blends of PET and PEN were tried the results were not satisfactory due to the undesired yellowness associated with the bottles.
PET is a semi-crystalline thermoplastic, which softens at ~ 70°C, its Tg. Above this temperature, the material becomes elastic, and can be formed, a property utilized effectively in the stretch blow-molding process. Due to its Tg at 70°C, PET is initially unsuitable as a bottle material for a hot filling process above this temperature, since deformations may occur: firstly, the bottles shrink, since they "remember" their previous shape (namely the perform), and secondly they collapse under internal pressure, a typical phenomenon during the cool-down period after hot filling. For this reason, the hot-fill PET bottles feature what are called vacuum panels, which compensate for the under pressure produced during the cool down period without the bottle collapsing.
During the stretching part of the production process for PET bottles, the material crystallizes due to stretch-induced crystallization. In the standard process, the material is frozen in this state at the mould wall, which is chilled. Inner stresses are then retained, and lead to shrinkage, particularly at heat-up. If, however, the material is heated still further after being stretched, it undergoes thermally induced crystallization. The stresses
2

in the material are also decreased, thus reducing the tendency towards shrinkage. The increased crystallinity gives the material significantly enhanced thermal stability. The glass transition temperature and the rigidity increase. This process is referred to as "heat-setting".
This improvement in PET's properties is utilized to make a resin suitable for the production of hot-fill PET bottles. To enable the bottles thus obtained to be removed from the hot moulds, however, they have to be cooled. For this purpose, compressed air is blown through bores in the tubular-shaped stretching rod, which cools the bottle from the inside. These additional steps in the process (crystallisation and cooling) mean that significantly more time is needed in the blow molding station under the heat-set process.
In the heat-set process, the bottle's characteristics depend even more closely on the process settings and the choice of preform than is the case in the standard process. In particular, the temperature of the product during filling and the time during which this temperature has to be maintained, are crucial factors. The higher the thermal stress, the higher the degree of crystallinity required. In order to obtain a very high degree of crystallinity, a long crystallisation time in the blowing mold is needed. Consequently, the higher the crystallinity required, the lower the machine's output will be. The heat set process can be of normal type where the bottle is blown against a mold held at a temperature of 100 -160 °C for up to 3 - 7 seconds resulting in crystallinity values of around 30%. Such bottles are suitable for hot fill up to 85 °C. The process can be of double blow process with multiple mold system resulting in crystallinity values of 40 -45%. In all these methods the body of the bottle only is subjected to heat setting and the amorphous threaded neck (finish) is left undisturbed as otherwise it will get distorted and lead to leakage after capping. Hence these heat set bottles require a separate neck crystallization treatment in order to make the bottles suitable for hot fill. Neck crystallization calls for investment on machinery and also the crystallized neck being white and opaque does not have an aesthetic appeal.
Prior Art
US 4497855 and 4665682 describe a collapse resistant polyester container for hot fill applications which withstands up to ~ 87.8°C stating that the containers do not exhibit

excess thermal distortion or vacuum induced pressure distortion upon hot filling. The heat set containers are reported to have crystallinity from about 28% to 32%.
US 4550043, 4936473 deal with multilayer preforms and containers with internal layers of barrier material and thermally stable polymers. These co injected multilayer bottles are suitable for hot filling and pasteurization.
US 4618515 relates to wide mouth polyester containers with oriented crystallized thread finish for hot fill applications. The neck finish having a higher density than the other portions of the bottle makes it more resistant to shrinkage during hot filling. Here the oriented transparent region of the bottle has a crystallinity of 22% while the crystallized neck region has a crystallinity above 30%.
US 5067622 describes an improved PET container specially designed for hot fill applications. These bottles are designed to withstand distortions due to uneven vacuum distribution occurring in the radial and longitudinal directions while hot filling. In addition to reinforcing the threaded neck portion a bulbous vacuum deformation area is provided adjacent to the container mouth.
Similar bottle design changes for hot fill applications are described in US 4318882, 4717525 and 4665682.
US 5251424 describes a process for hot filling in PET bottles wherein after filling at ~ 88°C liquid nitrogen is introduced and the bottle is sealed. This prevents distortions in the bottle by developing a positive pressure while the bottle is cooled to the ambient temperature.
Disclosures in a number of patents like US 4219526, 4233022 and 4711624 provide information of heat setting of the bottles while molding to increase crystallinity of the bottle which increases the heat distortion resistance of the hot filled bottles. However these heat set bottles require the process of neck crystallization prior to hot filling. Heat set bottles with modified polyester are described in a few patents but it is not clear from these patents whether neck crystallization can be avoided.

CA 2529283 deals with a PET copolymer comprising Diethylene Glycol (DEG) and minor amounts of Naphthalene Dicarboxylic acid (NDA).
TW562835 describes hot fill bottles manufactured from PET containing Barium Sulfate and black Ferric Oxide of micron sizes to promote crystallization rate while heat setting.
US 5250333 uses PET modified with alkoxylated polyol and NDC for containers having hot fill applications.
Information from the prior art leads to the conclusion that most of the earlier studies on PET bottles for hot fill applications deal with heat setting with modified design of the bottles or utilizing multi layer structures followed by neck crystallization but very little on modifying the PET resin with additives to control the shrinkage and increase the crystallinity of the final blown bottles suitable for hot filling without the neck crystallization.
The present invention primarily has the object of modifying the base resin with appropriate additives, heat setting the blown bottles and avoiding neck crystallization prior to hot filling which is hitherto unknown.
Objects of the present invention
The primary object of the present invention is to provide polyester compositions that can be used to form heat set blown bottles in which neck crystallization is avoided prior to hot filling.
Another object of the present invention is to provide a PET resin with improved crystallinity and glass transition temperature and which can be used to form a container that resists any significant change in shape.
Another object of the present invention is to provide a process for the preparation said polyester composition of PET.
Another object of the present invention is to provide a method of making containers with increased crystallinity and glass transition temperature.

Yet another object of this invention is to provide a resin such that in the process of making containers, typically, bottles with necks, normal thickness of the amorphous neck will be sufficient to withstand the higher temperature, up to 88°C hot filling and a separate step of crystallisation of neck is not needed, which calls for additional investment as well increased operational cost.
This is mainly because of the presence of a combination of nucleating agents in the resin which imparts a minimal crystallization in the neck thereby avoiding deformation while hot filling.
Summary of the invention
Accordingly, the present invention provides a polyester resin composition of Polyethylene terephthalate (PET) having a high crystallization rate comprising an intimate homogenous mixture of
(i) PET base resin,
(ii) 10 to 700 ppm of crystallization nucleating agents in the form of metal salts
of alkali and alkaline earth metals, salts of aliphatic and aromatic
monocarboxylic acids or a combination thereof;
(iii) 1 to 400 ppm of polycondensation catalysts selected from antimony (100 to
400 ppm) and titanium (1 to 20 ppm) based compounds,
(iv) 1500 to 3000 ppm of barrier improving and UV light protecting additives
selected from naphthalate compounds, typically naphthalene dicarboxylate
(NDC); and
(v) 1 to 60 ppm of color improving additives selected from a combination of
cobalt based compounds (1 to 60 ppm) and organic red and blue toners (1 to
10 ppm) and
(vi) 1 to 200 ppm of optional additives being in the nature of fast reheat additives
and nano sized silica particles (20 to 1000 nm size) as co nucleating agents.
Typically, the nucleating agents are selected from a group of compounds consisting of Sodium Acetate, Sodium Benzoate, Sodium Salicylate, Sodium or Potassium stearates, inorganic additives like talc, calcium carbonate, alumina, and titanium dioxide.

The present invention also provides a process for the preparation of said composition and a method of making the PET containers with an increased glass transition temperature. The hot filled containers made of polyester resin of the present invention is suitable for hot filling up to a temperature of about 88°C and without any significant change in the shape of the container.
More specifically, polyester compositions of Polyethylene terephthalate (PET) of the present invention comprise metal salts of alkali and alkaline earth metal containing nucleating agents which provide high crystallization rates. The present invention also provides a process for the preparation of said composition and a method of making the PET containers with an increased glass transition temperature suitable for hot fill application without the need for neck crystallization.
DESCRIPTION OF THE INVENTION
Accordingly, the present invention provides a polyester composition of Polyethylene terephthalate (PET) comprising metal salts of alkali and alkaline earth metal containing nucleating agents which provide high crystallization rates.
Therefore, the present invention provides a PET composition which by Injection Stretch Blow molding (ISBM) and heat setting converted to bottles for Hot Fill applications.
The metal salts of the present polyester composition are selected from a group of compounds consisting of sodium salts of alkali and alkaline earth metals, salts of aliphatic and aromatic monocarboxylic acids and a combination thereof.
The alkali and alkaline earth metal salts comprise Sodium Acetate, Sodium Benzoate, Sodium Salicylate, similar salts of Potassium, Sodium or Potassium stearates etc. generally added in the level of 10 to 700 ppm but preferably between 10 and 500 ppm.
The Polyester resin composition of the present invention may further optionally comprise Fast Reheat (FRH) additives to provide good clarity, high crystallinity and low shrinkage with fast heat pickup properties which are the prerequisites for the hot fill application.

In the present invention, the polycondensation catalyst is selected from antimony and titanium based compounds.
The resin composition of the present invention also comprises color improving additives selected from a combination of cobalt based compounds and organic red and blue toners.
The resin composition of the present invention also comprises naphthalate based additives like Naphthalene Dicarboxylate (NDC) for improving the barrier property as well as give protection to the bottles made there of from the UV light.
The resin composition of the present invention further comprises heat stabilizer viz. triethylphosphono acetate (TEPA) or Orthophosphoric Acid or a combination of both.
The present invention also provides a process for the preparation of said composition and a method of making the PET containers with an increased glass temperature.
(a) Preparation of the HotPET hot fill resin of the present invention: Example 1:
Hot PET resin is prepared with a recipe consisting of a paste of PTA (8.5 kg) and MEG (3.71 kg) in the ratio 70:30. The paste contained the additives viz. 100 to 400 ppm of antimony (Sb) as Sb2C>3 and preferably between 150 and 360 ppm as Sb (2.87 g Sb2C«3 or 240 ppm as Sb); 1 to 20 ppm of titanium (Ti) as Potassium Titanium Oxide Oxalate (PTOO) and preferably between 3 and 12 ppm as Ti (0.37 g PTOO or 5 ppm Ti) where Sb and Ti are catalysts for poly condensation; Cobalt 1 to 60 ppm as Co and preferably between 3 and 30 ppm (0.847 g Cobalt acetate or 25 ppm Co); Red and Blue color toners RT & BT at 1 to 15 ppm preferably between 1.0 to 10 ppm (0.015 g each or 1.5 ppm each) where Co and RT/BT are the color improving additives; special additives viz.sodium stearate 10 to 100 ppm preferably between 20 and 70 ppm (3.38 g or 25 ppm), sodium salycilate at 5 to 50 ppm preferably between 10 and 40 ppm(1.38 g or 20 ppm); sodium acetate at 50 to 300 ppm preferably between 50 and 200 ppm (5.62 g or 95 ppm); and Naphthalene Dicarboxylic Acid (NDC) 1000 to 5000 ppm preferably between 1500 and 3000 ppm (25 g or 2000 ppm).

The PTA-MEG paste containing these additives is esterified in the usual procedure in the esterification reactor. The esterified prepolymer is then polymerized in the polycondensation reactor and the phosphorous based heat stabilizer Triethyl Phosphono acetate (TEPA) is added such that its level as Phosphorous is 5 to 75 ppm preferably between 5 and 40 ppm (1.35 g or 20 ppm). After the poly condensation the polymer melt is taken out and converted to granules / chips of amorphous material by the normal casting procedure with IV between 0.5 to 0.65 dl/g. These amorphous chips are then increased in their IV by performing a Solid State Polymerization (SSP) to get a higher IVof0.75to0.80.
The primary function of the nucleating agents is to promote crystallization in the resin which is a prerequisite for the hot fill bottle application.
(b) A method of preparing containers made of PET resin of the present invention:
The SSP HotPET resin of I.V. ~ 0.75 is dried at a temperature of about 145 - 185°C for a period of about 6-7 hours. The moisture content of the resin is thus controlled between 25 - 50 ppm. This resin is then used for making preforms (34g, 28 PCO neck typical) in a Husky injection molding machine. The preforms are then heated followed by stretch blow molding to convert them to 500 ml bottles. After stretch blow molding the blown bottles are heat set in the mold followed by cooling before the bottles are taken out of the mold. During heat setting the mold temperature is maintained as follows: the body temperature between 90 and 140°C and the base temperature between 50 and 90°C. The characteristics of the hot fill bottles when they are subjected to hot filling at temperatures of 83, 85 and 88°C are given in Table-2.
Example 2:
8.5 kg of Pure Terephthalic acid (PTA) and 3.71 kg of Monoethylene glycol (MEG) are fed into the esterification vessel. To this, polymerization catalyst like Antimony trioxide (1.87 g) and Potassium Titanium Oxide Oxalate (PTOO) (0.27 g): colorants like, cobalt acetate (0.647 g), 0.01 gm each of red and blue toners are added. Nucleating agents like sodium acetate (3.25 g), sodium salicylate (1.08 g) and nano sized silica particles (2.3 g) are fed to the vessel. UV barrier additive Naphthalene Dicarboxylic acid (20 g) is also added to the esterification vessel. The esterification reaction takes place at a temperature of 240 - 270 °C for 140 minutes. The esterified pre-polymer is transferred to the polycondensation reactor.

To the polycondensation reactor, heat stabilizer Triethylphosphono acetate (TEPA) (2.4 g), and clear fast reheat additive Tungsten Trioxide (0.05 g) are added. The polymerization temperature is increased from 270 - 290 °C at 5-15 mbar pressure. The total time taken for this reaction is about 160 minutes. After polymerization the polymer is taken out and converted to granules/chips. The Intrinsic viscosity (IV) of these amorphous chips is increased by performing solid state polymerization. Containers are made from this resin as mentioned in Example 1(b).
Example 3:
This example describes a recipe free of antimony for hot fill resin. 8.5 kg of Pure Terephthalic acid (PTA) and 3.71 kg of Monoethylene glycol (MEG) are fed into the esterification vessel. Polycondensation catalyst Potassium Titanium Oxide Oxalate (PTOO) (0.75 g), colorants cobalt acetate (0.19 g), red and blue toners (0.01 g each), nucleating agents Sodium acetate (3.25 g) and nano sized silica particles (2 g) are added to the above said paste. The esterification is conducted at a temperature of 240 -270 °C for a time period of 200 minutes. The esterified pre-polymer is transferred to the polycondensation reactor.
To the polycondensation reactor, Triethylphosphono acetate (TEPA) (0.524 g), and clear fast reheat additive Tungsten trioxide (0.05 g) are added to the melt. For polymerization the temperature is increased from 270 - 290 °C and the pressure is reduced to 5-15 mbar. The total time taken for this process is around 180 minutes. After polymerization the polymer is taken out and converted to chips. The IV of these amorphous chips is increased by performing solid state polymerization. Containers are made from this resin as mentioned in Example 1(b).
Example 4:
This example is a recipe for a non hot fill bottle, typically used for carbonated soft
drinks (CSD) and does not contain the nucleating additives and has the normal carbon
black based FRH additive. This example is for comparison with the resin for hot fill
applications.
8.5 kg of Pure Terephthalic acid (PTA) and 3.71 kg of Monoethylene glycol (MEG) are
fed into the esterification vessel. 3.56 g of Antimony trioxide, 0.99 g of cobalt acetate,
0.047 g of red toner and 0.042 g of blue toner are added to the paste. The esterification

temperature is 240 - 265 °C and the time taken for this reaction to complete is around 160 minutes. The esterified pre-polymer is transferred to the polycondensation reactor. Before commencing polymerization, orthophosphoric acid (OPA, 0.96 g), Triethylphosphono acetate (TEPA) (0.524 g), fast reheat additive carbon black (0.02 g) and Ul additive (0.04 g) are added. The temperature is increased to 265-280 °C and pressure reduced to 5-15 mbar. The time taken for this process is around 160 minutes. After polymerization the polymer is taken out and converted to chips. The IV of these amorphous chips is increased by performing solid state polymerization. Containers are made from this resin as mentioned in Example 1(b).
Table -1: Resin Composition in the Examples

Ingredients Example 1 Example 2 Example 3 Example 4
PTA & MEG 70:30 70:30 70:30 70:30
Sb203 2.87 g 1.87 g - 3.56 g
as Sb, ppm 240 156 - 300
Ti Catalyst(PTOO) 0.37 g 0.27 g 0.75 g -
as Ti, ppm 5.0 3.5 10.0 -
Cobalt Acetate 0.847 g 0.647 g 0.19 g 0.99 g
as Co, ppm 20 15 4 22
RT/BT 0.015 g each 0.01 g each 0.01 g each 0.047 g/0.042 g
RT / BT, ppm 1.5 1.0 1.0 4.7/4.2
Sodium stearate 3.38 g - - -
as Na, ppm 25 - - -
Sodium salicylate 1.38 g 1.08 g - -
as Na, ppm 20 15 - -
Sodium acetate 5.62 g 3.25 g 3.25 g -
as Na, ppm 95 55 55 -
Nano sized silica particles - 2.33 g 2g -
Nano sized silica,ppm - 233 200 -
NDC 25 g 20 g - -
NDC, ppm 2500 2000 - -
TEPA /OPA 1.35 g 2.4 g 0.524 g 1.484 g
as P, ppm 18 32 7 7/26
CFRH (Clear Fast Reheat Additive) - 0.05 g 0.05 g -
CFRH, ppm - 5 5 -
FRH (Fast Reheat Additive) Carbon black -0.02 g, Ul additive - 0.04 g
FRH, ppm - - - 2/4

Table - II: Summarizes the important characteristics of the amorphous Hot PET

Examples IVdL/g Carboxylnumbermeq/kg DEGwt% L* CIE a* CIE b* CIE Tg °C Tm °C Tch°C
1. 0.56 25 0.95 69.5 -1.4 -4.5 79.5 252.5 148.1
2. 0.56 20 1.10 69.5 -1 -6.3 79.9 253.5 142.1
3. 0.61 16 1.07 74 -2.9 -2.5 80.5 252.5 144.4
4. 0.58 30 1.33 65.5 -1.1 -5.6 77.5 246.5 142.1
Where Carboxyl number meq/kg stands for the -COOH end groups present in the polymer
DEG wt % means the residual Diethylene Glycol present in the polymer
Table - III: Summarizes the important characteristics of the SSP Hot PET

Examples IVdL/g % Crystallization L* CIE a* CIE b* CIE Tg °C Tm °C Tch°C
1. 0.76 59.5 76.8 -1.7 -1 80.7 251.7 151.3
2. 0.77 58.8 75.1 -2 -3.4 80.5 252.5 145.7
3. 0.78 58.2 79.6 -2.2 -2.4 81.2 252.7 145.7
4. 0.81 50.1 74.0 -1.3 -1.6 78.4 245.4 147.9
From Tables II & III it is clear that Hot PET resin has a higher Glass Transition Temperature (Tg), higher % crystallization and a better color (compare Example 4 with Examples 1,2 &3). The clear fast reheat additive (CFRH) gives a better color as reflected in the L* values which are higher in spite of the variety of additives in the hot fill resin.
Nucleating agents containing salts of Sodium has a limitation in terms of clarity of the containers when added in large quantities. To overcome this, these additives can be added in optimum level, without affecting much the required crystallinity level of the bottle. Therefore to acquire a balance between the required crystallinity and clarity, nano sized silica particles are added. This additive increases the crystallinty without affecting the clarity.

Table - IV: UV Barrier properties of sample made from Examples 1 & 2 in comparison with Example 3

Wavelength, nm % Transmittance
With NDC Without NDC
400 78.85 89.21
390 65.51 79.51
380 35.12 62.52
370 1.132 32.78
360 0.308 1.858
350 0.177 0.231
340 0.171 0.139
330 0.103 0.095
320 0.231 0.161
310 0.149 0.174
From table IV, it is clear that NDC has increased Ultraviolet light (UV) barrier properties when compared to samples without NDC. Because of the enhanced UV light barrier, the container of this invention preserves the quality of food or beverage in the container and prevents off-taste in such food or beverage.
TABLE - V: Hot-fill Bottle Characteristics
(a) Bottle weight 34.0 g, 500 ml and 28mm PCO made from the resin of Example -1

Brimful Volume, ml Shrinkage, % Vacuum Test, Inches of Hg Top Load (kg)
83°C 85°C 88°C
Minimum 525 0.00 0.00 0.00 -15 >20
Maximum 543 0.56 0.60 0.75 -11 >20
Average 534 0.23 0.28 0.37 -14 >20
% Crystallinity 34.1 35.6 36.8

(b) Bottle weight 30.0 g, 600 ml and 28mm PCO made from the resin of Example -2

Brimful Volume, ml Shrinkage, % Vacuum Test, Inches of Hg Top Load (kg)
83°C 85°C 88°C
Minimum 616 0.13 0.14 0.60 -4.5 20.20
Maximum 617 0.20 0.23 0.72 -5.2 20.94
Average 618 0.16 0.18 0.65 -5.0 21.80
% Crystallinity - 34.7 35.3 36.4 - -
( c) Bottle weight-48.0g, 1200 ml and 28mm PCO made from resin of Example-3

Brimful Volume, ml Shrinkage, % Vacuum Test, Inches of Hg Top Load (kg)
83°C 85°C 88°C
Minimum 1235 0.31 0.65 1.29 -11 >20
Maximum 1240 0.33 0.96 1.45 -13.5 >20
Average 1238 0.32 0.81 1.37 -12 >20
% Crystallinity 35.2 35.8 36.7
(d) Bottle weight-48.0g, 1200 ml and 28mm PCO made from resin of Example - 4

Mold Temp°C Brimfu1Volume,ml Shrinkage, % Vacuum Test, Inches of Hg Top Load (kg)
80°c 83°c 85°c 88°c
75/110 1028 0.19 - - - -7.20 15
75/110 1024 - 0.69 - -6.70 18
75/110 1023 - - 1.48 - -7.30 17
75/110 1028 - - - 2.85 -6.80 16
% Crystalinity 31.1 31.6 31.4 31.5

All the bottles after hot filling at the different temperatures are also tested as per the
normal tests practiced in bottle testing viz. brimful volume, height, wall thickness, outer
dia., inner dia. neck deformation and any shape changes in the bottles before and after
hot filling.
These bottle parameters showed insignificant variations for hot fill resin Bottles and
shape change was observed only above 88 Deg C.
But in the case of hot fill bottles made out of CSD Resin the shrinkage and other
parameters showed more significant changes. Also the bottle shape got deformed even
at a low temperature of 75 °C.
It is seen from Table-V (a) and (b) the % shrinkage of the bottles filled at various temperatures are less than 1% which is one of the requirements for a hot fill bottle. This is mainly because of the sufficiently high % crystallinity (34 to 36) build up in the bottle. The vacuum testing is to make sure that the hot fill bottles do not buckle after the fill bottles are brought back to ambient temperature. Top load test is to ensure that the hot fill process has not weakened the bottle and it can withstand top loads similar to a normal bottle. In fact the hot fill bottles made from the invented recipe shows a better top load performance when compared to an ordinary CSD bottle.
Table - VI: Bottle hot filled at 85°C - Neck Dimensions in comparison with
specifications
a) Bottle weight 30.0g, 600 ml and 28mm PCO made from resin of Example - 2

Description Specification Minimum Maximum Average
Thread diameter mm 27.43 ± 0.25 27.43 27.49 27.45
Thread root diameter mm 24.51 +.0.20 24.63 24.69 24.66
Thread Depth mm 1.25 ±0.25 1.45 1.49 1.47
Inner bore diameter mm 20.60 ± 0.20 20.56 20.59 20.58
The test results show that the values are well within the specified range clearly indicating insignificant changes and no deformation of the neck. The bottles of this invention can be hot-filled till 88°C, without having to crystallize the neck to prevent deformation. A similar test with the resin from Example - 4, which does not contain the nucleating agents, showed significant deformations in the neck after hot filling

confirming its non suitability for hot filling applications. These results are given in Table-VII
Table - VII: Neck Deformation Details of Normal Bottles during Heat Setting

Description Specification Minimum Maximum Average
Thread diameter mm 27.43 ± 0.25 27.19 27.41 27.29
Thread root diameter mm 24.51 ±_0.20 24.15 24.09 24.22
Thread Depth mm 1.25 ±0.25 2.62 2.75 2.69
Inner bore diameter mm 20.60 ± 0.20 21.24 21.48 21.37
Table - VIII: Fast Reheat Value of Hot Fill Resin

Resin Temp, °C Time, min
CFRH / FRH (Example 2 ,3 &4) no 13 min 50 sec
Non FRH (Example 1) no 14 min 30 sec
The time taken for the resin containing nucleating agents and fast reheat additives to reach 110°C is lesser when compared to the resin containing all the nucleating agents and no fast reheat additive.
Advantages:
1. The crystallinity of the containers of Hot PET resin of the present invention is not less than about 34 %.
2. The shrinkage rate of the containers of Hot PET resin of the present invention when hot filled up to temperatures of 88°C shows a shrinkage of 3. There is no neck deformation in the bottles made from the resin of this invention after hot filling to a temperature of 88 °C
4. Compared to the known practice of neck crystallization prior to hot filling with the heat set bottles the hot fill resin of this invention does not require this additional process of neck crystallization.

We Claim:
[1] A polyester resin composition of Polyethylene terephthalate (PET) having a high crystallization rate comprising an intimate homogenous mixture of
(i) PET base resin,
(ii) 10 to 700 ppm of nucleating agents in the form of metal salts of alkali and
alkaline earth metals, salts of aliphatic and aromatic monocarboxylic acids or
a combination thereof;
(iii) 150 to 360 ppm of polycondensation catalysts selected from antimony and
titanium based compounds;
(iv) 1500 to 3000 ppm of barrier improving / UV light protecting additives;
(v) 3 to 30 ppm of color improving additives selected from a combination of
cobalt based compounds and 1 to 10 ppm of organic red and blue toners;
(vi) 5 to 75 ppm of a heat stabilizer additive; and
(vii) 1 to 200 ppm of optional additives being in the nature of nano sized silica
particles, and fast reheat additives.
[2] A polyester resin composition as claimed in claim 1, in which the polycondensation catalysts are selected from a group of compounds consisting of antimony trioxide, antimony triacetate, antimony glycol oxide, germanium dioxide, and potassium titanium oxide oxalate.
[3] A polyester resin composition as claimed in claim 1, in which the polycondensation catalysts are selected from a combination of antimony compounds and titanium compounds wherein the antimony level is in the range of 100 to 400 ppm and preferably between 150 and 360 ppm and the titanium is in the range of 1 to 20 ppm and preferably between 3 and 12 ppm.
[4] A polyester resin composition as claimed in claim 1, in which the Titanium based polycondensation catalyst is Potassium Titanium Oxide Oxalate (PTOO).
[5] A polyester resin composition as claimed in claim 1, in which there is no antimony based polycondensation catalyst and the resin is free of antimony and only

a titanium based polycondensation catalyst is used in the range of 1 to 20 ppm and preferably between 3 and 12 ppm.
[6] A polyester resin composition as claimed in claim 1, in which the UV light protecting / barrier additives are selected from a group of compounds containing the naphthalate group, typically, naphthalene dicarboxylate (NDC), polyethylene naphthalate, di(2-ethylhexyl)-2,6-naphthalene dicarboxylate, HNDA - hydrolyzed 2,6-naphthalene dicarboxylic acid, NDA - 2,6-naphthalene dicarboxylic acid, PET/I/N - polyethylene terephthalate-isophthalate-naphthalate co polyesters, PETNx - terephthalate-naphthalate polyester copolymers (x=% of naphthalate).
[7] A polyester resin composition as claimed in claim 1, in which the nucleating agent is at least one compound selected from a group of compounds consisting of Sodium Acetate, Sodium Benzoate, Sodium Salicylate, Sodium or Potassium stearate, and from a group of inorganic additives like talc, calcium carbonate, alumina, and titanium dioxide.
[8] A polyester resin composition as claimed in claim 1, in which the color improving additives are selected from a group of compounds consisting of cobalt compounds and red and blue toners.
[9] A polyester resin composition as claimed in claim 1, in which the optional additives are selected from a group of compounds consisting of fast reheat additives like carbon black and metallic oxides and compounds consisting of nano sized particles of silica, carbon, metals and earth metals, Cerium (IV) oxide, Cerium dioxide, Erbium oxide, Ferric oxide, Lanthanum oxide, Praseodymiumoxide, Yttrium(III) oxide, Aluminium oxide, Alumina, Magnesium oxide, Silicon Oxide, Titanium Oxide, Zinc oxide, Zirconium dioxide and Zirconium(IV) oxide.
[10] A polyester resin composition as claimed in claim 8, wherein the optional nano sized compounds have a particle size in the range of 20 to 1000 nm.
[11] A polyester resin composition as claimed in claim 1, in which heat stabilizer additive is phosphorus based.

[12] A polyester resin composition as claimed in claim 1, in which heat stabilizer additive are selected from a group of compounds consisting of phosphoric acid, phosphates, monophosphate, diphosphate, triphosphate, calcium phosphate, ammonium phosphate, trisodium phosphate, disodium phosphate, acid phosphates, e.g., those of calcium, magnesium, and sodium, sodium ammonium phosphate and phosphonates of 1 -Hydroxyethane( 1,1 -diylbisphosphonic acid).
[13] A polyester resin composition as claimed in claim 1, in which heat stabilizer additive is selected from Triethyl Phosphono acetate and Ortho Phosphoric acid and a combination of both.
[14] A polyester resin composition as claimed in claim 1, in which the fast reheat additive is selected from a group of compounds consisting of tungsten oxide, tungsten carbide, carbon black, metallic Antimony, Copper and Iron oxide.
[15] A process for making a polyester resin as claimed in claim 1 comprising the following steps:
i. preparing a paste of terephthalic acid and monethylene glycol in a typical
ratio 70:30;
ii. adding 150 to 360 ppm of polycondensation catalysts selected from
antimony and titanium based compounds to the paste;
iii. adding 5 to 250 ppm of at least one nucleating agent to the paste;
iv adding 1 to 60 ppm of color improving additives selected from a combination
of cobalt based compounds (1 to 60 ppm) and organic red and blue toners (1 to
10 ppm) to the paste;
v. adding 10 to 700 ppm of nucleating agents in the form of metal salts of alkali
and alkaline earth metals, salts of aliphatic and aromatic monocarboxylic acids
or a combination thereof to the paste;
vi. adding 1500 to 3000 ppm of UV barrier / light protecting additives to the
paste;
vii. esterifying the paste with additives in an esterification reactor to obtain a
prepolymer;
viii. polymerizing the prepolymer in a polycondensation reactor after addition
of 5 to 75 ppm of a heat stabilizer additive to obtain a polymer melt ; and

ix. converting the polymer melt into the polyester resin in the form of amorphous chips.
[16] A process for making a polyester resin as claimed in claim 15, in which a phosphorus based heat stabilizer additive is added in the polycondensation reactor, such that the level of Phosphorous is 5 to 75 ppm preferably between 5 and 40 ppm.
[17] A process for making a polyester resin as claimed in claim 15, in which the polycondensation catalysts are selected from antimony compounds and titanium compounds, preferably Potassium Titanium Oxide Oxalate (PTOO) such that the level of antimony in the final resin mass is 100 to 400 ppm of antimony and preferably between 150 and 360 ppm and that of titanium is 1 to 20 ppm of titanium (Ti) and preferably between 3 and 12 ppm as Ti.
[18] A process for making a polyester resin as claimed in claim 15, which includes the step of adding a fast reheat additive to the paste.
Dated this 21st day of June, 2006.
MOHAN DEWAN
OF R. K. DEWAN & COMPANY
APPLICANTS' PATENT ATTORNEY

Documents:

981-MUM-2006-ABSTRACT(11-5-2009).pdf

981-mum-2006-abstract(granted)-(15-9-2009).pdf

981-mum-2006-abstract.doc

981-mum-2006-abstract.pdf

981-mum-2006-cancelled page(31-3-2010).pdf

981-MUM-2006-CANCELLED PAGES(11-5-2009).pdf

981-MUM-2006-CLAIMS(11-5-2009).pdf

981-mum-2006-claims(granted)-(15-9-2009).pdf

981-mum-2006-claims.doc

981-mum-2006-claims.pdf

981-mum-2006-correspondance-received.pdf

981-MUM-2006-CORRESPONDENCE(11-5-2009).pdf

981-mum-2006-correspondence(18-3-2010).pdf

981-mum-2006-correspondence(ipo)-(1-4-2010).pdf

981-mum-2006-description (complete).pdf

981-MUM-2006-DESCRIPTION(COMPLETE)-(11-5-2009).pdf

981-mum-2006-description(granted)-(15-9-2009).pdf

981-MUM-2006-FORM 1(22-6-2006).pdf

981-mum-2006-form 18(2-7-2007).pdf

981-mum-2006-form 2(11-5-2009).pdf

981-mum-2006-form 2(granted)-(15-9-2009).pdf

981-MUM-2006-FORM 2(TITLE PAGE)-(11-5-2009).pdf

981-mum-2006-form 2(title page)-(granted)-(15-9-2009).pdf

981-MUM-2006-FORM 3(11-5-2009).pdf

981-mum-2006-form-1.pdf

981-mum-2006-form-2.doc

981-mum-2006-form-2.pdf

981-mum-2006-form-26.pdf

981-mum-2006-form-3.pdf

981-mum-2006-specification(amanded)-(11-5-2009).pdf


Patent Number 236014
Indian Patent Application Number 981/MUM/2006
PG Journal Number 38/2009
Publication Date 18-Sep-2009
Grant Date 15-Sep-2009
Date of Filing 22-Jun-2006
Name of Patentee FUTURA POLYESTERS LIMITED
Applicant Address PARAGON CONDOMINIUM, 3RD FLOOR, PANDURANG BUDHKAR MARG, MUMBAI 400013,
Inventors:
# Inventor's Name Inventor's Address
1 KULKARNI SANJAY TAMMAJI NO.1,KAMARAJAR SALAI,MANALI,CHENNAI 600 068,TAMIL NADU,INDIA,
2 VELURI RAMAKRISHNA No.1,Kamarajar Salai,Manali,Chennai 600 068,Tamil Nadu,India
3 BADAKUPPAM RAJA MOHAN No.1,Kamarajar Salai,Manali,Chennai 600 068,Tamil Nadu,India
PCT International Classification Number C08L62/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA