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, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Opaque polyethylene terephthalate composition for packaging
APPLICANTS
Reliance Industries Limited, Reliance Technology Group, Reliance Corporate Park, 7B Ground Floor, Thane Belapur Road, Ghansoli, Navi Mumbai-400701, Maharashtra India, an Indian Company
INVENTORS
Ayodhya Srinivasacharya Ramacharya, Upadhye Kuldip Suryaprakash, Jadimath Shivamurthy Padadayya, Limaye Chetan Vijay, Bhangale Vikas Kadu and, all of Reliance Industries Limited, Reliance Technology Group (RTG), B-4 MIDC Industrial Area, Patalganga 410220, District Raigad, Maharashtra, India, all Indian nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to an opaque polyethylene terephthalate composition for packaging.
This invention also relates to a method of making an opaque polyethylene terephthalate composition for packaging.
BACKGROUND OF THE INVENTION
Thermoplastic polyesters such as polyethylene terephthalate (PET) are used in large quantities in the manufacture of packaging, especially packagings for food articles. PET packagings like bottles have good chemical resistance and mechanical strength and barrier properties against gases like oxygen or carbon dioxide. Specific grades of PET packagings are also ideal for hot filling applications. PET as such also has excellent stretch blow moulding properties. However, they are transparent to visible UV radiation that can be detrimental to the stability of the packaged articles susceptible to the radiation, especially food articles. Because of the desirable properties and characteristics of PET as explained above, in order to render PET ideal for use in packaging applications of articles susceptible to visible UV radiation, opacity is imparted in PET usually by the addition of pigments such as titanium dioxide in quantities ranging from 2 to 7%. Because of the abrasive nature of the pigments, they cause wear and tear to the machinery used for making the packagings. Further, while blow moulding the packagings with PET containing pigments such as titanium dioxide, the outer surface of preforms are heated up more as compared to the inner surface thereof due to the scattering effect of infrared radiation by the TiO2 resulting in occasional bursting of packagings during manufacturing. Packagings made with Ti02

pigment incorporated PET also look dull thereby affecting the aesthetic look of the packaging. Additionally, use of TiO2 pigments limit stretchability of PET during blow moulding and necessitates changes in preforms design of the packaging as the preforms containing TiO2 pigments cannot be consistently and uniformly blow moulded under identical stretch conditions.
OBJECTS OF THE INVENTION
An object of the invention is to provide an opaque polyethylene terephthalate (PET) composition for packaging, which composition, besides being opaque, retains and improves all the desirable properties and characteristics of PET and at the same time is not abrasive so that wear and tear to the machinery used for making the packaging is prevented.
Another object of the invention is to provide an opaque polyethylene terephthalate composition for packaging, which composition prevents differential temperature development or temperature gradient across the inner and outer surfaces of the packaging and prevents damage to the packaging while being manufactured and which composition gives savings in energy during the making of the packaging.
Another object of the invention is to provide an opaque polyethylene terephthalate composition for packaging, which composition imparts a glossy finish to the packaging.
Another object of the invention is to provide an opaque polyethylene terephthalate composition for packaging, which composition has excellent stretch ratio and stretchability and avoids the necessity of making changes in the preform designs of the packaging.

Another object of the invention is to provide a method of making an opaque packaging, which packaging, besides being opaque, retains and improves all the desirable properties and characteristics of PET and at the same time is not abrasive so that wear and tear to the machinery used for making the packaging is prevented.
Another object of the invention is to provide a method of making an opaque packaging, which prevents development of temperature gradient or differential temperature across the inner and outer surfaces of the packaging and prevents damage to the packaging while being manufactured and which method saves energy during the making of the packaging.
Another object of the invention is to provide a method of making an opaque packaging, which packaging has an excellent stretch ratio and stretchability and avoids the necessity of making changes in the preforms design of the packaging.
Another object of the invention is to provide a method of making an opaque packaging, which packaging has a glossy finish.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided an opaque polyethylene terephthalate (PET) composition for packaging having less than 10% light transmission in the 8Q0nm region, the composition comprising 90 to 99% by weight of polyethylene terephpthalate (PET) as a matrix and 10 to 1% by weight of a polyolefin dispersed in the PET matrix in the presence of 100 to 700 ppm of an inorganic nucleating agent.

According to the invention there is also provided a method of making an opaque PET composition for packaging having less than 10% light transmission in the 800nm region, the method comprising compounding or dry mixing 90 to 99% by weight of polyethylene terephpthalate (PET) and 10 to 1% by weight of a polyolefin in the presence of 100 to 700 ppm of an inorganic nucleating agent.
The term "packaging" as used in the specification includes bottle, jar, can, tray or film especially for food articles.
Preferably, 95 to 97% by weight of the PET and 5 to 3% by weight of the polyolefin are compounded or dry mixed to prepare the composition. Preferably, the opaque PET composition comprises 200 to 300ppm of the inorganic nucleating agent. Preferably, the PET has an IV of 0.7 to 0.9 dl/g.and the polyolefin has MFl of 0.2 to 20. The polyolefin is selected from High Density Polyethylene, Low Density Polyethylene, Low Linear Density Polyethylene, Very Low Density Polyethylene, Polypropylene or Ethylene vinyl acetate, and is preferably High Density Polyethylene. The inorganic nucleating agent is selected from silica, calcium carbonate, talc, mica, kaolin, barium sulphate or titanium dioxide.
According to an embodiment of the invention, the composition comprises 0.1 to 1% by weight of a compatibilizer compounded or dry mixed with the PET, the polyolefin and the nucleating agent. Preferably, the compatibiliser is selected from maleic anhydride graft polyolefin, acrylic acid graft polyolefin or ethylene vinyl acetate or a functionalized derivative thereof, wherein the polyolefin is polyethylene, polypropylene or a copolymer of ethylene and propylene.

The composition can comprise 0.02 to 0.20% by weight of additive and colouring agent which can be compounded or dry mixed with the PET, polyolefin and nucleating agent and compatibiliser, if any. The additive and colouring agent are those generally commonly used in polymer industry.
According to another embodiment of the invention, the nucleating agent and the polyolefin are compounded to obtain a masterbatch and thereafter the masterbatch is dry blended with PET. The advantage of preparing a masterbatch is in the fact that PET is not exposed to heat during blending. Also, use of the masterbatch substantially increases the ease of operation.
The opaque PET composition prepared by the above method can be extruded into a sheet or film to obtain a flexible packaging. The sheet or film can also then be thermoformed to obtain a thermoformed packaging. The invention also provides opaque flexible packaging obtained by the method. The invention also provides opaque thermoformed packaging obtained by the method.
The opaque PET composition can also be injection moulded into a preform and the preform can be stretch blow moulded into a packaging. The invention also provides opaque stretch blow moulded packaging obtained by the method.
According to the invention there is provided an opaque composition comprising two immiscible polymers namely PET and HDPE, a method of making opaque PET composition for packaging, methods of making opaque stretch blow moulded, flexible and

thermoformed packagings and opaque stretch blow moulded, flexible and thermoformed packagings obtained with the PET composition. The titanium dioxide which may be used in the composition, is used in a very small amount ie in 100 to 700 ppm, preferably 200 to 300ppm as a nucleating agent and not as a pigment. The light transmission of the composition in the 800 nm region is less than 10% and the composition has excellent opacity. It retains and improves all the desirable properties and characteristics of PET. It has good chemical resistance and mechanical strength and barrier properties against gases like oxygen or carbon dioxide. It can be stretch blow moulded into packagings under identical stretch ratios which are normally used for PET. Hence there will not be any need to change the preforms design of the packaging. It is ideal for hot filling applications and food packing applications, especially milk, juices, edible oils, or jams. It gives good storage life to food articles and articles susceptible to visible UV radiation because of its opaque nature. It eliminates the use of abrasive titanium dioxide which is generally used in significantly higher amounts ie 2 to7% as a pigment. Hence, wear and tear to the machinery used for making the packaging is avoided. It prevents differential temperature development across the packaging thickness and damage to the packaging while being made and results in energy saving while making the packaging. Further it has excellent glossy finish and there is consistency in the bottle production in that there is no occurrence of bottle bursting.
The following experimental examples are illustrative of the invention but not limitative of the scope thereof:
Example 1
Polyethylene terephthalate (PET) and high density polyethylene (HDPE) in the weight ratio

of 97:3 and 300 ppm of TiO2 were compounded ie melt mixed and subsequently injection . moulded into 48 gm CSD (carbonated soft drinks) preforms and stretch blow moulded into two hundred 1.5L CSD bottles at a biaxial stretch ratio of 11 as per the conditions in Tables 1 and 2 below.
Example 2
PET:HDPE:maleic anhydride grafted HDPE in the weight ratio 96:3:1 and 300 ppm of Ti02 were compounded and subsequently injection moulded into 48 gm CSD preforms and stretch blow moulded into two hundred 1.5L CSD bottles at a biaxial stretch ratio of 11 as per the conditions in Tables 1 and 2 below.
Example 3
A masterbatch of 1% TiC"2 in HDPE was first prepared and this masterbatch was then dry blended with PET in a weight ratio of 3:97 and then directly injection moulded into 48 gm CSD preforms and stretch blow moulded into two hundred 3.5L CSD bottles at a biaxial
i
stretch ratio of 11 as per the conditions in Tables 1 and 2 below.
Example 4
PET:HDPE:acrylic acid grafted HDPE in the weight ratio 96:3:1 and 300 ppm of TiO2 were compounded and subsequently injection moulded into 48 gm CSD preforms and stretch blow moulded into two hundred I.5L CSD bottles at a biaxial stretch ratio of 11 as per the conditions in Tables 1 and 2 below.

PET used in the above examples was hot fill bottle grade (H7761) and had an intrinsic viscosity of 0.76 dl/g and melting point (MP) of 250°C. HDPE used in the above examples was B56003 grade and had a melt flow index (MFI) of 0.3 and MP of 120°C. Drying protocol for all the materials of the blends was 105°C for 8hrs. The dew point obtained at the end of drying time was - 30°C. Control was PET having IV 0.76 dl/g hot fill bottle grade (H7761). Cycle time was the same for all the compositions. For Examples 1 to 4, the temperature profile during moulding was maintained in the range of 275 to 285°C in the four zones of the moulding machine. The process parameters for the composition of the invention and the control remained the same. Table 1 below shows the injection moulding conditions in terms of injection pressures to which the control and the compositions prepared according to Examples I to 4 were subjected. Further, Table 2 below Illustrates the stretch blow moulding conditions and physical properties of bottles obtained thereby.

Table 1
Example
No Injection Pressure (bar)
Control 458
1 358
2 400
3 420
4 361

Table 2
Physical Properties Units or Specification
s Average result
Control Example 1 Example
2 Example
3 Example 4
Energy
Consumption
AL+ % 87 82 70 73 73
Height (mm) 320.41+/- 1.5 320.7 320.6 320.6 320.7 320.7
Brimful Volume (ml) 1540.6+/- 10 1542 1540 1540 1543 1541
Fill height Volume (ml) 1510+/-10 1512 1510 1513 1512 1512
Base depth (mm) 3.2 3.3 3.3 3.2 3.2
Shoulder diameter (mm) 88.5 +/- 0.8 88.5 88.5 88.6 88.5 88.5
Body diameter (mm) 86.7 +/- 0.8 87.0 87.0 87.0 87.0 87.0
Base diameter (mm) 88.5 +/- 0.8 88.8 88.8 88.8 88.8 88.8
Burst Test (Bar) >10 13.6 13.1 13.8 13.6 12.2
Top load (kgf) >32 43.0 44.0 39.0 45.0 41.0
Shoulder (g) -200mm 16.5+/-0.5 16 16.5 16.4 16.6 16.6
Body(g) 20.0+/-1 21.5 20.2 20.4 20.5 20.5
Base (g) -36mm 11+/-0.5 10.8 11.1 11.0 10.9 10.9

None of the bottles burst during moulding. This established and confirmed the consistency of the opaque PET composition and preforms. The energy required for preparing the opaque compositions of Examples 1 to 4 were lower as compared to the control thereby giving energy savings. Physical properties of the bottles obtained by the recipes of Examples 1 to 4 were comparable to the control.
Oxygen Transmission Rate (OTR) properties or barrier properties of the polymer blends of Examples 1 to 4 were studied and compared with control and the results were as in Table 3 below: Table 3

Example No OTR in cc/m2.day
Set 1 Set 2
Control 6.5 6.5
1 5.9 6.2
2 6.1 6.6
3 5.5 5.5
4 6.2 6.1
It is seen from Table 3 that in all the composition recipes of the Examples 1 to 4, OTR was relatively lower as compared to the control. The barrier performance of the compositions of the Examples I to 4 on an average improved by 5 to 15%. Generally HDPE has poor barrier properties as compared with PET. But the barrier properties of the compositions of the Examples 1 to 4 showed improvement over control PET.

Gloss data of the bottles with the composition of Example 3 was compared with TiO2 containing conventional bottles and the study results were as shown in the Table 4 below:

Table 4
Bottle Type Gloss data @ 60° angle
Conventional bottles containing 0.5 %Ti02 57
Bottle of Example 3 119
It is seen from Table 5 that the bottles of Example 3 had excellent and much higher glossy finish.
31.5 gm preforms of all the recipes of Examples 1 to 4 were stretch blow moulded into 0.5L hotfill bottles with heat-set. 200 bottles of each recipe was stretch blown continuously without a single bottle bursting while blowing. The energy required for all the opaque recipes were lower as compared to control. Stretch blow moulding and physical properties of bottles obtained by the composition of the invention we studied and compared with the control and the results were as shown in the following Table 5.

Table 5
Properties Units or Specifications Average results
Control Example 3
Top load Kgf 39 40
Vacuum Torr 220 230
Filling temperature °C 87 89
Reheat value sec 45 42

Table 5 shows that the composition of the invention has consistency and saves energy during preparation of the packaging. The energy saving can be expressed in terms of reheat value. Lower value for opaque bottle is indicative of the increase in processing speed/productivity. Bottle mechanical properties were comparable to control. The filling temperature was raised from 87 °C to 89 oC. Also the top load and ability to withstand vacuum were found to be marginally higher for Example 3 as compared to the control.
Visible UV spectrum of bottles of 0.3 mm thickness of Example 3 was studied with control and the results were as shown in the graph of Fig 1 of the accompanying drawings. In Figure 1 the curve related to control is marked 1 and the curve related to bottles of the invention as prepared by Examp/e 3 is marked 2. It is seen from the graph that bottles of Example 3 showed less than 10% light transmission in the 200 to 800 nm region whereas the control showed around 40% transmittance in the 320nm region and around 90%transmittance in the 400 to 800nm region. This clearly establishes the opaque nature of the bottles prepared by the method of the invention.
The above examples are non-limiting. The invention is defined by the claims that follow.

We Claim;
1. An opaque polyethylene terephthalate (PET) composition for packaging having less
than 10% light transmission in the 800nm region, the composition comprising 90 to 99%
by weight of polyethylene terephpthalate (PET) as a matrix and 10 to 1% by weight of a
polyolefin dispersed in the PET matrix in the presence of 100 to 700 ppm of an inorganic
. nucleating agent.
2. The opaque PET composition as claimed in claim 1 comprising 95 to 97% by weight of the PET and 5 to 3% by weight of the polyolefin.
3. The opaque PET composition as claimed in claim 1 or 2, which comprises 200 to 300ppm of the inorganic nucleating agent.

4. The opaque (PET) composition for packaging as claimed in any one of claims 1 to 3 wherein the PET has an IV of 0.7 to 0.9 dl/g.
5. The opaque (PET) composition for packaging as claimed in any one of claims 1 to 4 wherein the polyolefin has MFI of 0.2 to 20.
6. The opaque PET composition as claimed in any one of claims 1 to 5, wherein the
polyolefin is High Density Polyethylene, Low Density Polyethylene, Low Linear Density

Polyethylene, Very Low Density Polyethylene, Polypropylene or Ethylene vinyl acetate, preferably High Density Polyethylene.
7. The opaque PET composition as claimed in any one of claims 1 to 6, wherein the inorganic nucleating agent is selected from silica, calcium carbonate, talc, mica, kaolin, barium sulphate or titanium dioxide.
8. The opaque PET composition as claimed in any one of claims 1 to 7, which comprises 0.1 to 1% by weight of a compatibilizer compounded or dry mixed with the PET, the polyolefm and the nucleating agent.
9. The opaque PET composition as claimed in claim 8, wherein the compatibiliser is selected from maleic anhydride graft polyoiefin, acrylic acid graft polyolefm or ethylene vinyl acetate or a functionalized derivative thereof, wherein the polyoiefin is polyethylene, polypropylene or a copolymer of ethylene and propylene.
10. The opaque PET composition as claimed in any one of claims 1 to 9, which comprises 0.02 to 0.20% by weight of additive and colouring agent.
11 A method of making an opaque PET composition for packaging having less than 10% light transmission in the 800nm region, the method comprising compounding or dry mixing 90 to 99% by weight of polyethylene terephpthalate (PET) and 10 to 1% by weight of a polyoiefin in the presence of 100 to 700 ppm of an inorganic nucleating agent.

12 The method as claimed in claim 11, which comprises compounding or dry mixing 95 to 97% by weight of the PET and 5 to 3% by weight of the polyolefin.
13. The method as claimed in claim 11 or 12, wherein the inorganic nucleating agent is
present in an amount of 200 to 300ppm.
14. The method as claimed in any one of claims 11 to 13, wherein the PET has an IV of 0.7 to 0.9 dl/g.
15. The method as claimed in any one of claims 11 to 14, wherein the polyolefin has MFI of0.2 to 20.

16. The method as claimed in any one of claims 11 to 15 , wherein the polyolefin is High Density Polyethylene, Low Density Polyethylene, Low Linear Density Polyethylene, Very Low Density Polyethylene, Polypropylene or Ethylene vinyl acetate, preferably High Density Polyethylene.
17. The method as claimed in any one of claims 11 to 16, wherein the inorganic nucleating agent is selected from silica, mica, talc, kaolin, barium sulphate, calcium carbonate or titanium dioxide.
18. The method as claimed in any one of claims 11 to 16 which comprises compounding or dry mixing 0.1 to 1% by weight of a compatibilizer with the PET, the polyolefin and the nucleating agent.

19. The method as claimed in claim 18, wherein the compatibiliser is selected from maleic anhydride graft polyolefin, acrylic acid graft polyolefin or ethylene vinyl acetate or a functionalized derivative thereof, wherein the polyolefin is polyethylene, polypropylene or a copolymer of ethylene and propylene.
20. The method as claimed in any one of claims 11 to 19, which comprises compounding or dry mixing 0.02 to 0.20% by weight of additive and colouring agent with the PET, the polyolefin and the nucleating agent, and compatibilizer, if any.
21. The method as claimed in any one of claims 11 to 20, which comprises compounding the nucleating agent and the polyolefin to obtain a masterbatch and thereafter dry blending the masterbatch with PET.
22. The method as claimed in any one of claims 11 to 21, wherein the opaque PET composition is injection moulded into a preform and the preform is stretch blow moulded into a packaging.
23. The method as claimed in any one of claims 11 to 21, wherein the opaque PET composition is extruded into a sheet or film to obtain a flexible packaging.
24. The method as claimed in claim 23, wherein the sheet or film is thermoformed to obtain a thermoformed packaging.

25. Opaque stretch blow moulded packaging obtained by the method as claimed in claim 22.
26. Opaque flexible packaging obtained by the method as claimed in claim 23.
27. Opaque thermoformed packaging obtained by the method as claimed in claim 24.