FIELD OF THE INVENTION:
The present disclosure relates to a process for producing bi-axially oriented
polyester film from the Recycled Polyethylene Terephthalate (RPET) granules.
Particularly the disclosure relates to the RPET granules produced by
5 depolymerisation (chemical recycling) of the PET bottle flakes, amorphous PET
(A-PET), crystalline PET (C-PET), polyester film and post-consumer recycled
PET (PCR PET). The impurities from the granules are removed by the filtration
process and decolourisation of the granules done by clay beds. More particularly,
the said process minimizes the waste generation in the process and/or to use the
10 waste. The present process is capable to produce single or multilayer bi-axially
oriented polyester film having uniform thickness. The RPET film product having
similar quality and properties like virgin PET Films. The BOPET film of present
disclosure meets the requirement of various food packaging
compliance/standards like food and drug administration (FDA) and European
15 food safety authority (EFSA). The present disclosure also relates to an apparatus
for producing the bi-axially oriented polyester film from the post consumer
Recycled Polyethylene Terephthalate (RPET) granules.
BACKGROUND OF THE INVENTION:
20 Poly ethylene Terephthalate (PET) products are widely used, as beverage bottles,
film, laminates, straps, high-grade sheet, fibers etc., and in medical supplies,
especially syringes and containers. BOPET (biaxially-oriented polyethylene
terephthalate) is a polyester film made from stretched polyethylene terephthalate
(PET). The BOPET and is used for its properties of high tensile strength,
25 chemical and dimensional stability, transparency, reflectivity, gas and aroma
barrier properties, and electrical insulation.
The current commercially employed methods allow the use of (Post consumer
recyclate (PCR) PET recycle only in low end applications . Where higher quality
3
processing required as in the manufacture of biaxially oriented polyester films the
recycling is restricted due to productivity and quality issues. PET products are
widely used, as beverage bottles, for high-grade sheet and fibers, and in medical
supplies, especially syringes and containers for instance. Attempts have been
5 made to include the material in the recycling process as far as possible, but so far
without avail in that it has been impossible to entirely decompose residual
contaminants in the product. The current commercially employed methods allow
the use of post consumer PET recyclate only in applications with low-grade
demands. Where higher quality is require as in the manufacture of biaxially
10 oriented polyester films.
The BOPET film has application in various fields such as flexible packaging and
food contact applications, insulating material, printing mediums, electronic and
acoustic applications etc.
The BOPET are used in flexible packaging and food application as
15 • Laminates containing metallized BOPET film;
• White BOPET web substrate is used as lidding for dairy goods;
• Clear BOPET web substrate is used as lidding for fresh or frozen ready
meals;
• Roasting bags;
20 • Metallised films;
• Laminated sheet metal (aluminum or steel) used in the manufacture of
cans;
• BOPET sheets, straps, film etc.
One of the main requirements of the packaging material in food packaging
25 application is that must follow the food packaging compliance/standards. One of
the main issue is migration of the chemicals and contaminants/foreign particles
4
from packaging material to the food should never happen. Inventive BOPET film
as per design of the manufacturing – RPET used in cap layer, there is no
migration of chemicals and contaminants/foreign particles, it allows that
inventive BOPET film meet the requirement of various food packaging
5 compliance/standards. If the migration of chemicals and contaminants/foreign
particles takes place, then the BOPET does not follow the food
compliance/standards. Brand owners and customers are increasingly recognizing
the urgency of recycling PET into food grade packaging
The current technology uses very high amount of the virgin PET polymer and
10 very less amount of the recycled PET in order to achieve the desired food
compliance/standards. The current BOPET (in food applications) overcomes the
problem of migration by increasing the amount of the virgin PET polymer used.
Attempts have been made to include the material in the recycling process as far
as possible, but so far without avail in that it has been impossible to entirely
15 decompose residual contaminants in the product.
The problem associated with the current technology is that they use less recycled
PET. Hence, the current processes are not environment friendly. Secondly the
current technology needs virgin polymer to be used i.e. extra raw materials is
needed.
20 Reference is made of US patent document US4571363, wherein the biaxially
oriented polyester is produced. However, this document requires at least from
30% to 95% by weight of fresh polyester. Hence, to obtain the final biaxially
oriented polyester a large amount of fresh or virgin polyester is required. This has
impact on the environment and the cost is also very high.
25 Further reference is made to WO2001019694A1, wherein a polyester-based lowmelting-point sealant layer is used in the food packaging. The packing has a
complete layer, contacting the food, to be of virgin polyester. This document
mandates to the layer contacting the food to be of fresh polyesters. Hence, there
5
is a need to develop a process where in maximum possible recycled polyester can
be used and to reduce the use of virgin polyester in BOPET film.
In view of the above, the inventors of the present disclosure felt a need to develop
a process which overcomes all the problems of the prior arts and is cost effective.
5 Particularly there is a need to increase the recycled PET in the reactant and
reduce the virgin PET, to produce a BOPET which comply with the food safety
standards. The process of the invention not only gives economic benefit but also
addresses the environmental aspect. The present disclosure overcomes the
problems of the current technology by the claimed process. The present
10 disclosure BOPET can be produced from even up to 90% RPET granules and
also comply with the food compliance/ standards.
It is the aim of the inventors to manufacturer a bi-axially oriented polyester film
having recycled PET granules (RPET) as much as possible, up to 90% for food
and pharma packaging application.
15 Another objective of the present invention is to manufacture a bi-axially oriented
polyester film having, up to 100 % RPET granules, applicable for industrial
application. Further, the present invention leads to recycle and up-cycle of postconsumer plastic waste.
In another objective, the present invention produces the RPET granules using the
20 PET bottle flakes, PET film, along with Ethylene glycol (EG), terephthalic acid
and other additives in esterification process.
In another objective, the present invention prevents the migration of the
chemicals and contaminants/foreign particles on the film surface by filtration and
de-colourisation.
25 Another objective of the present invention is to produce the food grade BOPET
film from up to 90% recycled PCR PET.
6
Another objective of the present invention is to increase recycling of the PET for
reducing the environmental impact.
Another objective of the present invention is to produce BOPET form an ecofriendly and cost-effective process.
5 Yet another objective of the present invention is to manufacturer a bi-axially
oriented polyester film having, up to 100 % RPET granules, applicable for
industrial application.
Yet another objective of the present invention is to consume the post consumer
PET plastic waste
10 Yet another objective of the present invention is to up-cycling of the post
consumer plastic waste
Yet another objective of the present invention is to produce the RPET granules
using the PCR PET bottle flakes along with Ethylene glycol (EG) and other
additives in Depolymerization process.
15 Yet another objective of the present invention is to remove the contaminants by
filtration and de-colouration by using clay beds
Yet another objective of the present invention is to prevent the migration of the
chemicals and contaminants/foreign particles on the film surface by filtration and
di-colouration.
20 SUMMARY OF THE INVENTION:
The present invention concerns, first, a method of producing polyethyleneterephthalate (PET) recyclate granules (RPET) from PCR PET bottle flake, and,
second, manufacturing bi-axially oriented polyester film using the prepared
RPET granules. The impurities from the granules are removed by the filtration
25 process and decolourisation of the granules done by clay beds. More particularly,
the said process minimizes the waste generation in the process and/or to use the
7
waste. The present process is capable to produce single or multilayer bi-axially
oriented polyester film having uniform thickness. The RPET film product having
similar quality like virgin PET Films. The BOPET film of present disclosure
meets the requirement of various food packaging compliance/standards like FDA
5 and EFSA.
In another aspect of the invention the present disclosure relates to an apparatus
for producing the bi-axially oriented polyester film from the PCR Polyethylene
Terephthalate (RPET) granules. Further, the present invention leads to recycle
and up-cycle of post-consumer PET plastic waste.
10 BRIEF DESCRIPTION OF THE DRAWINGS:
Figure 1 illustrates a flow chart of the process, according to the invention;
The drawings referred to in this description are not to be understood as being
drawn to scale except if specifically noted, and such drawings are only exemplary
in nature.
15 DETAILED DESCRIPTION:
While the invention is susceptible to various modifications and alternative forms,
an embodiment thereof has been shown by way of example in the drawings and
will be described here below. It should be understood, however that it is not
intended to limit the invention to the particular forms disclosed, but on the
20 contrary, the invention is to cover all modifications, equivalents, and alternative
falling within the spirit and the scope of the invention.
The terms “comprises”, “comprising”, or any other variations thereof, are
intended to cover a non-exclusive inclusion, such that a setup, structure or
25 method that comprises a list of components or steps does not include only those
components or steps but may include other components or steps not expressly
listed or inherent to such setup or structure or method. In other words, one or
more elements in a system or apparatus proceeded by “comprises… a” does not,
8
without more constraints, preclude the existence of other elements or additional
elements in the system or apparatus.
For the better understanding of this invention, reference would now be made to
the embodiment illustrated in the accompanying Figures and description here
5 below.
Furthermore, it is to be understood that the invention is not limited to the details
of construction or process steps set forth in the following description. The
invention is capable of other embodiments and of being practiced or being carried
out in various ways.
10 Expressions “a”, “an”, “the”, when used to define a term, include both the plural
and singular forms of the term.
One aspect of the invention relates to a process for preparing biaxially oriented
polyethylene terephthalate (BOPET) film comprising, the steps of
- preparing a recycled polyethylene terephthalate (RPET) granules, comprises
15 • depolymerization and glycolysis of the pre cleaned PCR PET products to
produce monomers,
• polycondensation of the monomers in a polycondensation reactor or an
autoclave to produce recycled PET granules.
- preparing the biaxially oriented polyethylene terephthalate film, comprises
20 • charging RPET granules optionally along with a virgin granules, to obtain
a molten polyethylene terephthalate,
• extruding the molten polyethylene terephthalate through a die,
• quenching the extruded polyethylene terephthalate on chilled rollers and
stretching to obtain biaxially oriented polyethylene terephthalate film.
25 characterized in that, the esterification reaction is conducted in a glycoliser
reactor by addition of glycol, at a temperature of 245-255oC and at a pressure of
0.5-1 bar, and
the RPET granules are up to 90% in the mixture of the RPET and virgin PET
granules, charged to the extruder.
9
One embodiment of the invention involves a process wherein a biaxially oriented
polyethylene terephthalate obtained three layer configuration.
5 Yet another embodiment of the invention involves a process wherein the
biaxially oriented polyethylene terephthalate is an A/B/A or A/B/C configuration,
the B layer comprises biaxially oriented polyethylene terephthalate film made
from the recycled PET (RPET) and cap layers A and/or C, comprises contains
biaxially oriented polyethylene terephthalate film, made from virgin PET
10 granules, along with inorganic filler.
Another embodiment of the invention involves a process, wherein the step of film
preparation comprises up to 90 % of the recycled PET granules.
15 Yet another embodiment of the invention involves a process, wherein the step of
film preparation comprises up to 100 % of the recycled PET granules.
Yet another embodiment of the invention involves a process, wherein the step of
pre cleaning of PET flakes comprises the followings steps,
20 -primary washing of PET products by solvent to remove contamination, non PET
metals such as poly propylene, poly ethylene, poly vinyl chloride.
-de brushing the washed for removal of dust and unwanted materials,
-de- stoning for the removal of the stones to obtain cleaned PET flakes.
25 Yet another embodiment of the invention involves a process, wherein the step of
preparing the recycled polyethylene terephthalate (RPET) is followed by
filtration for foreign particles removal and di-coloration, before the film
preparation step.
30 Yet another embodiment of the invention involves a process, wherein the PET
products are selected from one or more films, sheets, laminate, bottles and flakes.
10
amorphous PET (A-PET), crystalline PET (C-PET), polyester film and postconsumer recycled PET (PCR PCT)
Yet another embodiment of the invention involves a process, wherein the
autoclave is 275-295o
5 C and batch time of 3-4 hrs.
Yet another embodiment of the invention involves a process, wherein the
autoclave reactor is maintained at vacuum and catalyst is added.
10 Yet another embodiment of the invention involves a process, wherein the
stretching involves
-machine direction stretching with stretch ratio of 3 - 3.5, and
-transverse direction stretching with stretch ratio of 3.8–4.2.
15 Yet another embodiment of the invention involves a process, wherein the
autoclave reactor is added with additives to prevent the color of melt from turning
yellow.
Yet another embodiment of the invention involves a process, wherein the
20 biaxially oriented polyethylene terephthalate (BOPET) is a food grade packaging
film.
Yet another embodiment of the invention involves a process, wherein the RPET
granules is 30% in the mixture of the RPET and virgin PET granules, charged to
25 the extruder.
Yet another embodiment of the invention involves a process, wherein the RPET
granules is 70% in the mixture of the RPET and virgin PET granules, charged to
the extruder.
30
11
Another embodiment of the invention involves an apparatus for producing
biaxially oriented polyethylene terephthalate (BOPET) film comprises,
- cleaning apparatus for pre cleaning PET products to be recycled,
- esterification reactor for converting the pre cleaned PET flakes to a monomer,
- autoclave reactor operated at temperature of 275-295o
5 C and at vacuum pressure,
for polycondensation of the monomers to obtain a recycled PET granules,
- extruders for extruding the recycled PET granules and optionally a virgin PET
granules to obtain the molten polyethylene terephthalate (PET),
- chilled rollers for quenching the molten PET and stretching to obtain biaxially
10 oriented polyethylene terephthalate,
characterized in that, the esterification reactor involves glycoliser reaction by
addition of glycol, at a temperature of 245-255oC and at a pressure of 0.5-1 bar,
and
the RPET granules are up to 90% in the mixture of the RPET and virgin PET
15 charged to the extruder.
Yet another embodiment of the invention involves an apparatus, wherein the
cleaning apparatus comprises
- pre cleaning machine for washing, removing contamination and non-PET
20 metals such as poly propylene, poly ethylene, poly vinyl chloride from the
PET flakes,
- de brushing apparatus for removal of dust and unwanted materials,
- de stoning apparatus for the removal of the stones to obtain cleaned PET
flakes.
25 - magnetic separator for removal of iron and other metal particles.
.
The present invention removes the dust from RPET granules by filtration and
decolourisation by using clay beds. In another objective, the present invention
prevents the migration of the RPET on the film surface by filtration and de30 colourisation.
12
The use of recycled PET in place of virgin resin typically results environmental
impact and carbon footprint.
The present disclosure relates to a process of manufacturing bi-axially oriented
polyester (BOPET) film from the Recycled Polyethylene Terephthalate (RPET)
5 granules. Particularly, the disclosure relates to the RPET granules produced by
depolymerisation of the PET bottle flakes, PET film. The BOPET is
manufactured with RPET as a raw material. The BOPET film has recycled PET
granules (RPET) as much as possible, up to 90% for food and pharma packaging
application and up to 100 % RPET granules applicable for industrial application.
10 The BOPET film of the present disclosure overcomes the problem of migration,
on the film surface and manufactured film applicable for food packaging
application, produced from up to 90% RPET granules. The RPET granules are
produced by depolymerization of flakes in monomer in presence of ethylene
glycol in esterified – glycolysis process and produce the granules after
15 polycondensation. Further, the properties of granules are improved by filtration
and decolourisation which prevent from the migration of the chemicals and
contaminants/foreign particles.
Extruding the said molten polyester through a die and quenching the same on
chilled rollers in order to obtain transparent polyester film.
20 PET bottle flakes charge in estrification reactor through feeding tank, under
heating and in presence of Ethylene Glycol (EG) get depolymerised, form the
100% monomer batch in reactor and with time, pressure and temperature,
additives are added- get polymerised and produce the granules after
polycondensation.
25 These granules go under filtration for dust removal and di-colouration for colour
improvements.
RPET GRANULES PREPARATION:
13
PET Bottled flake collected through vendors is fed into a tank through a jumbo
bag. The flake then passes into feeding tank through which the flake passes to an
esterification reactor -maintained the pressure and temperature i.e. the PET bottle
flakes are charged in esterification reactor through feeding tank, under heating.
5 Pure Purified terephthalic acid (PTA) is added to flake in the esterification
reactor. The reactor has an agitator that runs at high rpm during the process. The
process condition for the esterification reactor is disclosed in Table 1. This
reaction leads to depolymerised of PET bottle flakes and produce 100% monomer
batch in the reactor. From the esterification reactor, the batch (monomer) passes
10 to an autoclave reactor, in which polycondensation reaction takes place. The
autoclave reactor is maintained at vacuum and additives is added to it. Additives
are added to autoclave to prevent the colour of melt from turning yellow, under
stirring of agitator. As the polycondensation reaction progresses the RPM of
agitator is reduced, and the autoclave is pressurized with nitrogen to take out
15 polymer melt. The polymer melt (RPET) is sent to cutting and drying. The RPET
granules thus formed is tested for various properties namely ash content, IV, end
group and haze which were found to be comparable with virgin PET.
Table 1: Process Parameter of Esterification Reactor
Esterification Reactor Parameter
Virgin
PET
R PET
Temperature ( ° C) 245- 255 245-255
Pressure ( bar) 0.5-1 0.5-1
RPM 800-1200 800-1200
Autoclave reactor temperature ( ° C) 275-295 275-295
Batch time ( hrs) 3-4 3-4
20
.
14
Table -2 PET flakes properties
S
No. Parameter Unit Values/Results
1 Intrinsic viscosity dl/gm 0.7-1.0
2 Melting point ◦C 240-255
3 PVC ppm <50
4 Moisture % <1
5 Bulk density Kg/m3 250-350
6 Wrong colors ppm <50
7 Other contamination ppm <20
8 Al/metal ppm <25
9 Paper/lable/floatable/PE/PP ppm <20
5
Filtration and De-coloration:
A filter used on the process to remove any impurities and ensure consistently
high quality RPET granules. It improves the granules quality and improved the
productivity .
10 Clay is used extensively for decolourisation purposes in the production of RPET
granules. Clay used in a granular form in a fixed bed adsorber. The RPET
granules are passed through the clay in the fixed bed absorber, which adsorbes
the colourants from the RPET granules. Surface area and good porosity of clay
material make them useful adsorbent. The clay used in the process is Mineral
15 clay like Bentonite which has good surface area and porosity.
15
BOPET FILM PREPARATION:
The present disclosure relates to a process for preparing the bi-axially oriented
5 polyester film, said process comprising the steps of charging of RPET granules
produced, in main extruder and virgin granules in side extruder to obtain molten
polyester, extruding, quenching and stretching the film to obtain the BOPET film.
The film comprises three layers (e.g. an A/B/A or A/B/C) configuration. One
and/or two layers in films comprise the silica.
10 The bi-axially oriented polyester film in particular include a multilayer structure
such as A/B/A and/or A/B/C wherein the B-layer (core-layer) comprises
polyethylene terephthalate layers of the film and contains recycled PET (RPET)
and cap layers (A and/or C) comprises polyethylene terephthalate layers of the
film and contains virgin PET granules with inorganic filler.
15 In the present disclosure, up to 90% RPET or even 100% uses to manufacturer
the film applicable for food and pharma packaging application.
Presently disclosed bi-axially oriented polyester film is made of using 100%
RPET granules i.e. core as well as cap layer made of RPET granules, applicable
for the industrial applications.
20 Film Processing Parameter:-
Film Grade MDO
Stretching
Temperature
(◦C)
MDO
Draw
Ratio
TDO
stretching
Temperature
(◦C)
TDO
crystallizing
Temperature
(◦C)
TDO
Draw
Ratio
RPET Film
(A/B/A
80-85 3 - 3.5 90-100 225-240 3.8–4.2
16
Layer)
In one embodiment of the invention the film comprises three layers (e.g. an
A/B/A or A/B/C) configuration. One and/or two layers in films comprise the
silica.
5 The bi-axially oriented polyester film in particular include a multilayer structure
such as A/B/A and/or A/B/C wherein the B-layer (core-layer) comprises
polyethylene terephthalate layers of the film and contains recycled PET (RPET)
and cap layers (A and/or C) comprises polyethylene terephthalate layers of the
film and contains virgin PET granules with inorganic filler.
10 In the present invention, up to 90% RPET uses to manufacturer the film
applicable for food and pharma packaging application
Presently disclosed bi-axially oriented polyester film is made of using 100%
RPET granules i.e. core as well as cap layer made of RPET granules, applicable
for the industrial applications.
15 Environmental benefits from producing RPET
Producing the RPET film from the PET post consumer waste has the various
environment benefits compare to virgin PET film. It reducing the carbon
footprint and reducing the energy consumption in manufacturing of film, also
reducing the usage of fossil feedstocks. It has the Life cycle analysis (LCA)
20 advantage over virgin PET film, recycling 1 tonnes of plastic bottles saves 1.5
tonnes of CO2 in reference to landfill or incineration. It also reduces the green
house gases (GHG) and energy use compare to virgin PET film. Land and ocean
pollution
The said bi-axially oriented polyester film has good elongation, mechanical and
25 thermal properties and useful in high end food and pharma packaging and
industrial applications.
17
The invention itself, together with further features and attended advantages, will
become apparent from consideration of the following detailed description, taken
in conjunction with the accompanying drawings. One or more embodiments of
the present invention are now described, by way of example only wherein like
5 reference numerals represent like elements and in which
Examples:
Examples 1:
Various batches of RPET produced by the method of the present disclosure are
analyzed for the properties like IV, COOH, Ash and DEG. The properties of
10 RPET are comparable to the virgin PET. Hence, up to 90% RPET can be used to
manufacturer the film applicable for food or pharma packaging application.
Test Results:
RPET IV COOH ASH DEG
Virgin
PET
IV COOH ASH DEG
1 0.643 23.64 0.057 1.691 1 0.631 27.6 0.006 1.094
2 0.643 25.5 0.022 1.924 2 0.64 26.5 0.016 1.16
3 0.646 24.74 0.021 1.172 3 0.628 31.6 0.024 1.04
4 0.642 23.93 0.014 1.72 4 0.623 28.31 0.01 1.208
5 0.639 23.5 0.018 1.827 5 0.626 32.58 0.022 1.036
Average 0.6426 24.262 0.0264 1.6668 Average 0.6296 29.318 0.0156 1.1076
Example 2:
15 Comparison between virgin and RPET film properties:
The biaxially oriented PET film produced by the process of the invention
(involving recycled PET) is compared with the biaxially oriented PET film
produced from the virgin PET. Mechanical properties like tensile strength,
elongation at break of rPET films are similar to virgin PET film. Similarly
18
optical, surface properties and performances are also comparable with virgin PET
film. The results are summarized in the below table.
Properties Test Method Unit Standard
PET
70%
rPET 90% rPET
Nominal Thickness Standard
Method
Micron 12+0.5 12+0.5 12+0.5
Gauge 48+2 48+2 48+2
Yield Standard
Method
m2/kg 60+5 60+5 60+5
in2/lb 42000 42000 42000
Tensile Stregth –
MD
ASTM D882
kg/cm2 2200+500 2200+500 2200+500
kpsi 31.3 31.2 31.2
Tensile Stregth –
TD
ASTM D882
kg/cm2 2300+500 2300+500 2300+500
kpsi 32.7 32.5 32.5
Elongation at Break
– MD
ASTM D882 % 130+25 130+25 130+25
Elongation at Break
– TD
ASTM D882 % 125+25 125+25 125+25
Heat Shrinkage (At 150 Degree C for 30 mins)
MD ASTM D1204 % 2+0.5 2+0.5 2+0.5
TD ASTM D1204 % 0.2+0.5 0.2+0.5 0.2+0.5
Co-efficient of Friction, A/B
Static ASTM D1894 0.52+0.5 0.52+0.5 0.52+0.5
Dynamic ASTM D1894 0.42+0.5 0.42+0.5 0.42+0.5
Surface Tension
Plain Side ASTM D2578 44+4 44+4 44+4
Corona Side ASTM D2578 56+4 56+4 56+4
Optical Properties
Haze ASTM D1003 % 2.3+0.5 2.3+0.5 2.3+0.5
19
Mechanical properties like tensile strength, elongation at break of RPET films are
similar to virgin PET film. Similarly, optical, surface properties and
performances are also compararable with virgin PET film. Hence, the process of
the present invention makes the usage of rPET up to 90% to produce a food grade
5 biaxially oriented PET.
Advantages:
The BOPET disclosed in the present disclosure provide the following advantages:
• Upto 90% RPET is used in the film manufacturing in core layer and
10 virgin PET in cap (top and bottom layer- along with inorganic filler)
• No issue of the migration of the contaminants/dust on the film surface
• Remove the impurities by filtration and de-colouration by clay beds
• Uses more recycled PET and less or no virgin PET
• Environment friendly
15 • Economical process

We Claim:

1. A process for preparing biaxially oriented polyethylene terephthalate (BOPET)
5 film comprising, the steps of
- preparing a recycled polyethylene terephthalate (RPET) granules, comprises
• depolymerization and esterification of the pre cleaned PCR PET products
to produce monomers,
• polycondensation of the monomers in a polycondensation reactor or an
10 autoclave to produce recycled PET granules.
- preparing the biaxially oriented polyethylene terephthalate film, comprises
• charging RPET granules optionally along with a virgin granules, to obtain
a molten polyethylene terephthalate,
• extruding the molten polyethylene terephthalate through a die,
15 • quenching the extruded polyethylene terephthalate on chilled rollers and
stretching to obtain biaxially oriented polyethylene terephthalate film.
characterized in that, the esterification reaction is conducted in a glycoliser
reactor by addition of glycol, at a temperature of 245-255oC and at a pressure of
0.5-1 bar, and
20 the RPET granules are up to 90% in the mixture of the RPET and virgin PET
granules, charged to the extruder.
2. The process as claimed in claim 1, wherein the biaxially oriented polyethylene
terephthalate obtained has atleast three layer configuration.
25
3. The process as claimed in claim 1 or 2, wherein the biaxially oriented
polyethylene terephthalate is an A/B/A or A/B/C configuration,
the B layer comprises biaxially oriented polyethylene terephthalate film made
from the recycled PET (RPET) and cap layers A and/or C, comprises contains
30 biaxially oriented polyethylene terephthalate film, made from virgin PET
granules, along with inorganic filler.
21
4. The process as claimed in claim 1, wherein the step of film preparation
comprises up to 90 % of the recycled PET granules.
5 5. The process as claimed in claims 1 or 4, wherein the step of film preparation
comprises up to 100 % of the recycled PET granules.
6. The process as claimed in claim 1, wherein the step of pre cleaning of PET
flakes comprises the followings steps,
10 -primary washing of PET products by solvent to remove contamination, non PET
metals such as poly propylene, poly ethylene, poly vinyl chloride.
-de brushing the washed for removal of dust and unwanted materials,
-de- stoning for the removal of the stones to obtain cleaned PET flakes.
15 7. The process as claimed in any claims 1 to 6, wherein the step of preparing the
recycled polyethylene terephthalate (RPET) is followed by filtration for foreign
particles removal and di-coloration, before the film preparation step.
8. The process as claimed in claim 1, wherein the PET products are selected from
20 one or more films, sheets, laminate, bottles and flakes. amorphous PET (A-PET),
crystalline PET (C-PET), polyester film and post-consumer recycled PET (PCR
PCT)
9. The process as claimed in claims 1 or 8, wherein the autoclave is 275-295oC
25 and batch time of 3-4 hrs.
10. The process as claimed in claims 1, 8 or 9, wherein the autoclave reactor is
maintained at vacuum and catalyst is added.
30 11. The process as claimed in claim 1, wherein the stretching involves
-machine direction stretching with stretch ratio of 3 - 3.5, and
22
-transverse direction stretching with stretch ratio of 3.8–4.2.
12. The process as claimed in claims 1, 8, 10 or 11, wherein the autoclave reactor
is added with additives to prevent the color of melt from turning yellow.
5
13. The process as claimed in any claims 1 to 11, wherein the biaxially oriented
polyethylene terephthalate (BOPET) is a food grade packaging film.
14. The process as claimed in claim 1, wherein the RPET granules is 30% in the
10 mixture of the RPET and virgin PET granules, charged to the extruder.
15. The process as claimed in claim 1, wherein the RPET granules is 70% in the
mixture of the RPET and virgin PET granules, charged to the extruder.
15 16. An apparatus for producing biaxially oriented polyethylene terephthalate
(BOPET) film comprises,
- cleaning apparatus for pre cleaning PET products to be recycled,
- esterification reactor for converting the pre cleaned PET flakes to a monomer,
- autoclave reactor operated at temperature of 275-295oC and at vacuum pressure,
20 for polycondensation of the monomers to obtain a recycled PET granules,
- extruders for extruding the recycled PET granules and optionally a virgin PET
granules to obtain the molten polyethylene terephthalate (PET),
- chilled rollers for quenching the molten PET and stretching to obtain biaxially
oriented polyethylene terephthalate,
25 characterized in that, the esterification reactor involves glycoliser reaction by
addition of glycol, at a temperature of 245-255oC and at a pressure of 0.5-1 bar,
and
the RPET granules are up to 90% in the mixture of the RPET and virgin PET
charged to the extruder.
30
23
17. The apparatus as claimed in claim 14, wherein the cleaning apparatus
comprises
- pre cleaning machine for washing, removing contamination and non-PET
metals such as poly propylene, poly ethylene, poly vinyl chloride from the
5 PET flakes,
- de brushing apparatus for removal of dust and unwanted materials,
- de stoning apparatus for the removal of the stones to obtain cleaned PET
flakes.
- magnetic separator for removal of iron and other metal particles.