A PROCESS OF MANUFACTURING BI-AXIALLY ORIENTED POLYESTER FILM DIRECTLY FROM THE POLYMER MELT
FIELD OF INVENTION
The present invention relates to a process of manufacturing bi-axially oriented polyester film directly from the polymer melt. More particularly, the said process minimises the waste generated in the process and/or to reuse the waste. The present process is capable to produce single or multilayer bi-axially oriented polyester film, having uniform thickness.
BACKGROUND OF INVENTION
Polyesters have been widely used in diverse fields for variety of applications. Globally the growth of polyester usage is expected to remain strong due to continuous demand in various applications. The challenge for meeting the growth is addressed by addition of new capacities and reducing the process times, increasing the productivity and recycling etc.
Stoyko Fakirov in Handbook of Thermoplastic Polyester mentioned that varity of shaped articles are produced from polyester. Amongst them the three principle products are made of polyester are fibres, films and bottles. Which are produced by different process like bottles by injection moulding, film by extrusion, fibres by spinning. The selection of polyester for specific end use requires considerable care and polyester grades vary depending upon requirement. One of the first considerations is molecular weight which is generally reported by Intrinsic Viscosity (I.V). For fibre grade I.V range is from 0.72 -0.98 and polyester should be water clear and colourless. For Film grade I.V range is from 0.60 - 0.70. For carbonated bottles I.V range from 0.78 - 0.85 and polyester should have low aldehyde content which is not required fro film and fibres.
At present, conventional process for shaping the polyester film, of various polyesters and polyesters mixture of varying viscosity, begins by reaction of the monomer(s) to form molten polyester. Molten polyester is passed through a die having number of holes forming strands which are then quenched using water. Such strands are cut into pellets. The pellets are crystallized, dried, and melted in extruder. The pellets are heated above

glass transition temperature (Tg) to crystallize and dried under air/Nitrogen purging or under vacuum. The pellets are dried so that the moisture content is maintained as low as possible preferably below 5 ppm. Extruders may have vent in order to remove volatilities created during the process. The melt is then pumped through the filter to remove the impurities, degraded matter, lumps etc, in order to produce an even melt throughput as it is pushed through the extrusion die. The melt is then passed through the film formation process to form biaxial oriented polyester film.
Various above multistage processes affect the performance of the polyester which is being converted into polyester film. When polyester is extruded, various undesirable side reactions of polyester degradation take place. Polyester degradation imparts the negative effect in different properties such as physical, mechanical, thermal, optical properties of the polyester film. Also multiple stage processes are highly cost and energy intensive as these processes require additional cost and energy of conveying, heating, storage space etc.
Waste handling is a big challenge in the polyester film manufacturing industry. Waste is generated in various processes in the form of trims, purging, and chips formation and many times undesired films. Waste is produced by post consumable goods like crushed bottles, pellets, used shaped films which are posting a big problem to the environment. A big challenge lies in efficiently recycling and reusing the waste in an economical manner to get advantage of cost and energy.
Multilayer polyester films are also now common and are made up of more than one layer. For cases, where composition of the base layer and other layers are different, separate arrangement for polyester pellets crystallization, drying and extrusion has to be made which leads to higher processing cost.
One of the ways to over come the above problem is stated in patent number CH694291 where the branched stream is originated form the base stream and is modified by additives for formation of other layer. But the limitation is that other layers can not be

different from base layer and are modification of base layer where modification is done by addition of additives in base layer melt. This process does not disclose the use of recycled polyester.
Industry is continuously looking for the improvements with optimum energy, high productivity, with better quality and with stable production.
Present invention has capability to overcome the above mentioned problems and also it facilitates to recycle production waste like trims, purging material, undesired film and post consumable wastes like crushed bottles, pellets, used shaped films which are posting a big problem to the environment.
OBJECTIVES OF THE INVENTION
The primary objective of the invention is to provide a continuous manufacturing of the
biaxial oriented polyester film directly from the continuous polyester melt.
Another objective of the invention is to provide a process which minimise the waste
production and to reuse the waste generated in the process.
Another objective of the invention is to provide a process wherein the recycled polyester
is incorporated in the continuous polyester melt.
Another objective of the invention is to provide a process wherein the continuous
polyester melt is branched off into more than one stream.
Another objective of the invention is to provide a process wherein the biaxial oriented
polyester film is capable to produce single or multilayer bi-axially oriented polyester
film, having uniform thickness.
SUMMARY OF THE INVENTION
The present invention relates to continuous manufacturing of biaxial oriented polyester film directly from the reaction melt. The inventive process overcomes all the problems mentioned above. The inventive process provides biaxial oriented polyester film with better mechanical, optical, physical properties etc, where major part of the polyester is not converted to pellets and re-melted through extruder. Hence there is no polyester

degradation. It uses continuous melt directly to form polyester film thus maintaining higher viscosity and better properties. The inventive process provides the better method of recycling the waste generated from various processes like the trims, purging, and chips formation and many times undesired films and waste produced by post consumable goods like crushed bottles, pellets, used shaped films.
BRIEF DESCRIPTION OF THE FIGURES
Fig. A illustrates a block diagram of the system for making polyester film directly from
polyester melt according to an embodiment of present invention
Fig. B illustrates block diagram of making polyester film with recycled polyester from
polyester melt according to an embodiment of present invention
Fig.C ( Fig C1, Fig.C2& Fig.C3) illustrates block diagram of die and co extruder system
for multi layering of the article to get ABC,AAB,ABA according to an embodiment of
present invention
Fig D (Fig Dl & Fig D2) illustrates block diagram of making recycled polyester melt
according to an embodiment of present invention.
DETAILED DESCRIPTION OF THE FIGURES
As defined in figure A, the monomer or the monomer mixtures (100) along with additives like heat stabilizers, hydrolysis stabilizers, catalyst and the like and other additives as known in the state of art, is fed to the intermediate polyester reactor for intermediate polyester formation (101). The intermediate polyester reactor is single reactor or multiple reactors. The intermediate polyester (101) so formed is fed to the continuous polyester reactor for continuous polyester formation (103). The continuous polyester reactor can be single reactor or multiple reactors. The continuous polyester (103) so obtained is passed through the pumps (104) and filters (105) for removing the lumps, foreign matter etc. The continuous polyester (103) is sent to online viscosity measurement. The continuous polyester (103) is branched into one or more than one stream and where branched stream / streams originate from a single position or multiple positions (108). A strict and rigid control of flow and pressure (107,109,111) is maintained in between the branched stream, in between every branch of each branched

stream and in between the branched stream and main stream. The branched stream is sent to polyester film formation die (112) where at least one of the branched streams is sent to the cutter (110) for pellet formation.
Whole process as given in fig A remains the same except the monomer/monomer mixture along with additives like heat stabilizers, hydrolysis stabilizers, catalyst and the like and other additives as known in the state of art, is fed to the intermediate polyester reactor for intermediate and partial continuous polyester formation (102). The partial continuous polyester so formed is fed to continuous reactor for continuous polyester formation(103).
As defined in figure B, the monomer or the monomer mixtures along with additives like heat stabilizers, hydrolysis stabilizers, catalyst and the like and other additives as known in the state of art, is fed to the intermediate polyester reactor for intermediate polyester formation (101) and partial continuous polyester formation (102). The intermediate and partial continuous polyester reactor is single reactor or multiple reactors. The recycled polyester (200) is added just before the continuous polyester formation and after the partial continuous polyester formation.
The partial continuous polyester mixed with recycled polyester is fed to the continuous polyester reactor for continuous polyester formation. The continuous polyester reactor can be single reactor or multiple reactors. The continuous polyester so obtained is passed through the filters (105) and pumps (104) for removing the lumps, degraded matter, foreign matter etc and for obtaining the even throughput. The continuous polyester (103) is sent to online viscosity measurement. The continuous polyester (103) is branched into one or more streams where branched stream / streams originate from a single position or multiple positions. A strict and rigid control (106,107,109,111) is maintained on the flow path and flow rate in between the branched stream and in between the branched stream and main stream. The branched stream is sent to polyester film formation die (112) where at least one of the branched streams is sent to the cutter for continuous polyester pellet formation.
As defined in figure C, the continuous polyester so obtained is sent to polyester film formation die (112) where the continuous polyester forms the base layer and the other

layers are formed by melting of pellets in extruder (300 &301). The pellets are melted and sent to die for other layer formation. As given in figure C1, the different pellets (300 & 301) are used for formation of other layers forming ABC type structure. And as given in figure C2, same pellet is used for formation of other layers i.e. ABA structure. And in Fig C3, AAB type structure is made.
Another aspect as defined in Figure D, the recycled material (200A) as produced from the continuous polyester is added before the continuous polyester reaction.
As given in Figure Dl, the recycled polyester (200A) is melted in extruder (201B) is the melt extruded recycled polyester (201) and is the recycled polyester (200).
As given in Figure D2 the recycled polyester as produced from continuous polyester processing i.e. recycled polyester (200A) melted in extruder (202B) and is mixed with monomer/ monomers mixtures (202C) and/or glycols (202D) in a static mixer (202E) to form the glycolized recycled polyester (202) and which is the recycled continuous polyester (200). The monomer/ monomer mixtures be the same as used for formation of continuous polyester or be fully different. The glycol / glycols mixtures be the same glycols used for formation of continuous polyester or fully different and where glycols be the glycols like MEG, BG, PG, PEG, DEG, CHDM, NPG etc and the like as known in the state of art.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly, the present invention relates to a process of manufacturing bi-axially oriented polyester film directly from the continuous polymer melt comprising the steps of:
a) reacting monomer or monomer mixtures to produce intermediate polymer melt or partial continuous polymer melt,
b) adding recycled continuous polymer melt to the intermediate polymer melt or partial continuous polymer melt of step (a) to obtain continuous polymer,
c) branching continuous polymer melt of step (b) into at least two multiple streams,

d) sending at least one branched stream to the cutter for pellet formation,
e) controlling the pressure and mass flow of continuous polymer melt in each divided stream of each branch streams,
f) allowing the polymer melt of each divided streams of step (e) to a die, quenching and orienting the resultant melt streams in order to obtain the desired bi-axially oriented polyester film.
One aspect of the present invention, wherein the intermediate polymer melt of step (a)
having intrinsic viscosity in the range of 0.05 to 0.15 dl/gm.
Another aspect of the present invention, wherein the partial continuous polymer melt of
step (a) having intrinsic viscosity in the range of 0.20 to 0.35 dl/gm.
Yet another aspect of the present invention,, wherein the continuous polymer melt of step
(b) having intrinsic viscosity in the range of 0.40 to 1.0 dl/gm.
Yet another aspect of the present invention, wherein in step (a) the monomer/ monomer
mixtures is selected from the di-carboxylic acid or glycol or mixture thereof.
Yet another aspect of the present invention, wherein in step (a) & (b) the intermediate or
partial continuous polymer or continuous polymer melt is prepared at a temperature in the
range of 200°C to 300°C.
Yet another aspect of the present invention, wherein in step (f) the quenching is carried
out at a temperature in the range of 20°C to 50°C.
Yet another aspect of the present invention, wherein the dicarboxylic acid is selected
from the group comprising 2, 6-naphthalene dicarboxylic acid, isophthalic acid, and
phthalic acid, aliphatic dicarboxylic acids like adipic acid and or esters of same along
with dimethyl terephthalate or terephthalic acid when used as group of dicarboxylic
acids and mixture thereof.
Yet another aspect of the present invention, wherein the glycols are selected from the
group comprising did ethylene glycol, propylene glycol, butanediol, hexanediol,
neopentyl glycol, trans-1, 4-cyclohexanediol and cis-l,4-cyclohexanediol, CHDM along
with ethylene glycol when used as group of glycols and mixture thereof.
Yet another aspect of the present invention, wherein the di-carboxylic acid and glycol are
mixed in the ratio of 1:0.3 to 1:0.5.

Yet another aspect of the present invention, wherein the monomer are optionally added
with additives such as antiblocking agents, antioxidants, stabilizers etc.
Yet another aspect of the present invention, where intermediate polymer melt formation,
partial continuous polymer melt formation and continuous polymer melt formation is
carried out in a single reactor or single reactor with multiple sections or in multiple
reactors.
Yet another aspect of the present invention, wherein the bi-axial polyester film having
shape and size according to the die design.
Yet another aspect of the present invention, wherein the bi-axial polyester film
comprising at least one base or inner layer (B) and at least one outer or another layer (A
or C) , preferred base layer (B) from continuous polymer melt and other layers being
prepared by polymer melt obtained from pellets of step (d).
Still another aspect of the present invention, wherein recycled continuous polymer melt
contains any of the following melts either
• recycled polyester formed by extrusion melting of recycled polyester in weight upto 1.5 times of continuous polyester, or
• Glycolized recycled polyester formed by mixing of melt extruded recycled polyester with monomer / monomer mixture in weight ratio of 10:1 to 1:10 adding glycolized recycled polyester in weight upto 2 times of continuous polyester.
Still yet another aspect of the present invention, wherein the recycled polymer melt
include the recycled material produced from the continuous polymer processing and / or
waste material obtained form other sources like post consumable recycles.
Yet another aspect of the present invention, where the continuous polymer is branched
either from a single position or multiple positions of branched stream.
Yet another aspect of the present invention, wherein each branched stream having flow
rate controlling means, pressure gauge to maintain strict and rigid control on the flow rate
and pressure between every branched stream of polymer melt.
Yet another aspect of the present invention, wherein another layers is either same as that
of base layer or different from the base layer.

Yet another aspect of the present invention, wherein each branched stream having a
provision of online viscosity measurement.
Yet another aspect of the present invention, wherein orientation of polyester film is
carried out by heating the polyester melt obtained in step (f) and orienting the said film in
biaxial direction, wherein the difference between ΔTMC (the difference in melting
temperature and crystallization temperature of the said film) and TSMD (stretching
temperature in machine direction) is in the range of 0°C to 50°C, and the difference
between ΔTMC (the difference in melting temperature and crystallization temperature of
the said film) and TSTD (stretching temperature in transverse direction) is in the range of -
30°C to 50°C.
Yet another aspect of the present invention, wherein polyester film is optionally provided
with an antistatic coating to get surface resistivity of film less than 10 ohm cm.
Yet another aspect of the present invention, wherein the polyester film is suitable for
coating with SiOx and AlOx.
Yet another aspect of the present invention, wherein the polyester film is optionally
vacuum metallized.
Yet another aspect of the present invention, wherein the polyester film of having other
layer thickness is in the range of 0.5 to 10 micron and base layer thickness range from 2.5
to 300 micron
Yet another aspect of the present invention, wherein bi-axially polyester film having
three layers such as ABC, BBB, ABA and AAB, wherein B is base or inner layer and A
& C are outer layer.
The present process provides biaxial oriented polyester film with better properties etc, where major part of the polyester is not converted to pellets and re-melted through extruder. Hence there is no polyester degradation. It uses continuous melt directly to form polyester film thus maintaining higher viscosity and better properties.
The present process provides the better method of recycling the waste generated from various processes like the trims, purging, and chips formation and many times undesired films and waste produced by post consumable goods like crushed bottles, pellets, used shaped films.

In conventional processes, changing from one product type to other is difficult and leads to regular formation of waste. During the production break, production of melt does not stop and leads to formation of waste materials. One of the objectives of the present invention is to minimise the waste material production and to reuse the wastage generated in the process in such a way to get the best cost benefits.
Another objective of the inventive process is to make the biaxial oriented polyester film which is uniform and even in single as well as in multilayer processing where the variation is possible in at least one of the other layers.
The inventive process of making biaxial oriented polyester film is a process where continuous polyester reactors are used for producing continuous polyester melt. In the process for making continuous polyester melt, continuous polyester reactors are used where continuous polyester reactors are at least one reactor or two or more separate reactors in numbers or a single reactor having multiple sections. The continuous polyester reactors are independent on function from each reactor. The continuous polyester reactors can be partially dependent or fully dependent on the function from each reactor.
The continuous polyester reaction is divided into two stages. At the first stage the reaction between monomer / monomers mixture occur alone or along with additives, forming intermediate polyester melt and at the other stage the intermediate polyester melt is reacted to form the continuous polyester melt. Both the intermediate polyester melts formation and the continuous polyester melt formation usually occurs in separate reactors. In some cases the intermediate polyester melts formation and the continuous polyester melt formation can be in single reactors.
In some cases the continuous polyester reaction is divided into three stages intermediate polyester formation, partial continuous formation and continuous polyester formation. In such cases the intermediate polyester formation and partial continuous co-polyester can occur in single reactor. The partial co-polyester is further reacted in separate reactor to form continuous polyester. In the inventive process the monomer / monomer mixture form intermediate polyester and partial continuous melt in single reactor and the partial

continuous polyester is further reacted in separate reactor to form continuous polyester. The extent of reaction between the monomer / monomer mixtures forming the continuous polyester is checked by Intrinsic Viscosity (I.V) measurement.
The continuous polyester suitable for this purpose are those prepared from ethylene glycol and terephthalic acid (or dimethyl terephthalate) or ethylene glycol and naphthalene dicarboxylic acid or cyclohexane dimethanol and cyclohexane dicarboxylic acid or copolyesters containing upto 50% of other acids or glycols. Besides the above, where appropriate, it may contain units of aromatic dicarboxylic acids like 2, 6-naphthalene dicarboxylic acid, isophthalic acid, phthalic acid, aliphatic di-carboxylic acids like adipic acid, sebacic acid and among cycloaliphatic dicarboxylic acids cyclohexane dicarboxylic acids (in particular cyclohexane 1, 4- dicarboxylic acid) and also other glycols like diethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol, and acyclic diols such as trans-1, 4-cyclohexanediol and cis-1,4-cyclohexanediol, aromatic diols such as hydroquinone, resorcinol, 4, 4'-dioxydiphenol, 2, 6-naphthalenediol.
In the inventive process in step (a) the di-carboxylic acid and glycol are mixed in the ratio of 1:0.3 to 1:0.5 and the known additives like catalyst, antiblocking agents, antioxidants, stabilizers, etc are added.
The monomer / monomer mixtures can be used alone or along with additives like but not limited to heat stabilizers, hydrolysis stabilizers, catalyst, colorants, antioxidants, acetaldehyde scavengers, stabilizers, impact modifiers, polyesterification catalyst deactivators, nucleating agents, organic and inorganic fillers, colorants, plasticizers and the likes and other additives which are known to the state of art. The resulting mixture is fed to the continuous polyester reactor to form continuous polyester melt.
The process of producing the continuous polyester is the reaction product of the mixture of dicarboxylic acid and glycol which produce water as byproduct or its ester which produce alcohols as by product. To increase the reaction rate, many known catalyst like Titanium oxides, Dibutyl tin laurate, Antimony trioxide, antimony triacetate, etc are used alone or in combination with Zinc acetate, manganese acetate, magnesium acetate or

benzoates. The reaction occurs at temperature above the melting point of dicarboxylic acid. The heating may occur at temperature of between 200°C to 350°C. If desired, during heating, pressure is reduced so as to remove the water and/or glycol which are obtained as by product.
The extent of conversion of monomer / monomer mixture to continuous polyester melt is checked by Intrinsic Viscosity. The conversion of monomer / monomer mixture to the continuous polyester leads to a continuous increase of I.V. At the stage of intermediate polyester the I.V is above 0.05 dL/gm at 25°C when tested using 60:40 wt by wt mixture of phenol and tetrachloroethane. More preferably, the I.V may range from 0.05 to 0.15 dL/gm at 25°C. At the stage of partial continuous polyester I.V reaches above 0.20 dL/gm at 25°C. More preferably, I.V may range from 0.20 to 0.35 dL/gm at 25°C. At the stage of continuous polyester may have I.V above 0.4 dL/gm gram at 25°C. More preferably the I.V may range from 0.4 to 1.0 dL/gm and most preferably 0.5 to 0.75 dL/gm.
The reaction between the monomer / monomer mixtures are carried out at temperature above the melting point of dicarboxylic acids and more probably the temperature above the melting point of polyester. For conversion of monomer / monomer mixtures to intermediate polyester the temperature is maintained above the melting point of dicarboxylic acid probably the temperature is maintained above 200°C more probably between 200°C to 325°C. For conversion of intermediate polyester to continuous polyester the temperature is maintained above the melting point of polyester preferably temperature is maintained above 200°C more preferably between 220 to 350°C.
One of the aspect of the inventive process is to add the recycled polyester to the continuous polyester melt. In the process of addition of recycled polyester, the recycled polyester is either converted to melt extruded recycled polyester or glycolized recycled polyester. The recycled polyester is added to the continuous polyester melt as it is or along with additives.
The recycled polyester are the waste material produced from the polyester film processing and also covers waste material obtained form other sources like post

consumable recycles. The waste material produced from film processing includes trims, purging, flakes, chips formation and many times undesired films and the likes. The waste material produced by post consumable goods not only covers post consumable waste of film like used shaped films but also of other articles like crushed bottles, pellets and the likes. The recycled polyester can be added alone or along with additives like but not limited to catalyst, antioxidants, heat stabilizers, and the likes and other additives as known in the state of art.
In the process of addition of recycled material, the waste material is melt extruded in extruder. The melt so produced either can be directly added to the continuous polyester melt as melt extruded recycled polyester or can be mixed with monomer / monomer mixtures to produce glycolized recycled polyester before addition to continuous polyester melt. The monomer / monomer mixtures added are preferably dicarboxylic acid or alkylene glycol or the mixture of dicarboxylic acid and alkylene glycols. Dicarboxylic acid can be used in single or mixture thereof and alkylene glycol can be used in single or mixture thereof. More preferably the monomer / monomer mixtures added is alkylene glycol where alkylene glycol can be added in single or as a mixture thereof.
In the process of addition of recycled polyester, the recycled polyester is extruded at temperature above the melting point of polyester which is preferably above 200°C. More preferably the recycled polyester is extruded between 200 to 350°C and most preferably between 220°C to 350°C. The extruded melt of recycled polyester is added to continuous polyester melt as it is as melt extruded recycled polyester or mixed with monomer / monomer mixtures at temperature of above 180°C more preferably at temperature between 200°C to 300°C before addition to continuous polyester melt. The mixing of recycled polyester with the monomer / monomer mixtures is done at the weight ratio of 10:1 to 1:10, more preferably 7:1 to 1:7, more preferably 4:1 to 1:4 and most preferably 1:4. The addition of recycled polyester to the continuous polyester is done at temperature above the melting point of polyester i.e above 200°C more probably between 220°C to 350°C.

The recycled polyester can be added upto the two times the weight of continuous polyester depending upon the I.V of the recycled polyester. It is found that glycolized polyester can be added upto 2 times the weight of continuous polyester while melt extruded polyester can be added upto 1.5 times the weight of the continuous polyester.
The recycled polyester is added before the formation of continuous polyester melt. More preferably the recycled polyester is added after the formation of Intermediate polyester melt. Most preferably the recycled polyester is added to partial continuous polyester melt. If the recycled material is added before the partial continuous polyester melt, film formation will not occur. If the recycled material is added after the partial continuous melt, the film properties deteriorate.
One of the aspect of the inventive process for making polyester film where necessary pumps are provided for obtaining an even throughput and necessary filters are provided to remove any foreign matter, degraded matter, lumps etc.
Another aspect of the present invention is that the continuous polyester melt is branched off into more than one stream and at least one of the branched streams is sent to cutter for pellets formation. In case of non utilization of polyester film die, the continuous polyester melt is sent to the cutter to minimize the waste formation. Yet another objective is to maintain a strict and rigid control on the flow path and flow rate of the continuous polyester melt is maintained in between the branched streams in order to control the branching and distribution of the continuous polyester melt.
The inventive process where the continuous polyester melt comes out from the continuous polyester reactor is the main stream and is branched into at least two streams or more streams and where each branched streams can further be branched into two or more streams. The branched stream/ streams or branches of the branched streams are sent to die for polyester film formation. The branched stream/ streams may originate from a single position or from multiple positions. The capacity of each branched stream can be the same as continuous polyester reactor. The process, where at least one of the branched stream is sent to cutter for continuous pellet formation.

The process where the continuous polyester melt flow is controlled by the pressure and flow rate and where strict and rigid control on pressure and flow rate is maintained between every branch of each branched stream, in between the branched streams and between the branched streams and the main stream. The control of thickness of the polyester film also depends on the flow control of continuous polyester melt. In case of lower requirement of the continuous polyester melt at the polyester film die the pressure and the flow rate control directs a reduced flow to the die and in turn increases the flow towards the cutter. In case of the full utilization of the continuous polyester at the polyester film die the control directs the continuous polyester to the aforesaid mentioned polyester film die, in turn reduce or stop the flow of continuous polyester flow to the cutter. In case continuous polyester is not required at the polyester film die the control directs the continuous polyester to stop the flow to the aforementioned polyester film die and send the continuous polyester to the cutter.
The continuous polyester melt is passed through necessary pumps for even throughput and also through necessary filters to remove lumps, degraded matter, foreign material etc. The viscosity of the continuous polyester is measured online.
One of the aspect of the inventive process where continuous melt from each branched stream or every branch of each branched stream is sent to the film formation die and where at least one stream is sent to pellet formation die. The polyester film so formed can be of single layer or at least more than one layer. Another objective of the invention is that the other layer can be same or based on or fully different from the base layer where other layer is formed by melting of pellets.
In the inventive process the polyester film so formed consists of a single layer or at least more than one layer. The polyester film formation, where the base layer and the other layer are passed through a common die. The polyester film can be single layer or at least more than one layer which consists of a base layer and at least one other layer where the other layers can be the same or different from each other and where the other layer can be the same as that of the base layer or based on the base layer or different from the base layer. For example, if, base layer is B, the other layer A and/ or C. Hence, in case of three layer structure of final polyester film, possible combination is ABA, BBB, ABC, etc.

In the inventive process where the other layer or layers are produced from separate melt where the melt is produced from melting of the pellets. The other layer can be produced from the melting of pellets of continuous polyester, or can be produced from pellets of continuous polyester along with different polyesters and/or additives and/or recycled material, or can be made from pellets of different polyester. Under such conditions, the other layer can be same as that of the base layer if the pellets of the continuous polyester are used for formation of other layers alone or along with antiblocking agent and/or recycled material obtained from continuous polyester. The other layer can be based on the base layer if the pellets of the continuous polyester are used along with pellets of different polyester and/or additives and/or recycled material. The other layer can be fully different from the base layer if pellets of different polyester are used alone or along with some additives and/or recycled material. The different polyester or pellets of different polyesters are produced from dicarboxylic acid and alkylene glycol where dicarboxylic acid or alkylene glycol or both are not same as that of used in formation of base layer.
The polyester film formed has a base layer and atleast one other layer. The polyester film so formed has atleast one base layer and more than one other layer. The polyester film where both the other layer be different form the base layer and be different form each other i.e. ABC. The polyester film where other layers be different from the base layer and both other layers are same to each other i.e. ABA. The polyester film where one outer layer is different from base layer and second outer layer is same as that of base layer like AAB.
The process where the thickness of the other layer be small in comparison to the thickness of the base layer. The process where the thickness of the other layer varies from 5% to 50% of the weight of the polyester films. The process where the thickness of each other layer may be the same or different from each other. The additives used can contribute upto 50wt% pref. 40wt% of the other layer.
In the process for producing of the polyester film, the continuous polyester along with the other layers are passed through a die and quenched on chilled roll as a normal transparent

amorphous polyester film. This polyester film is reheated and oriented in sequential biaxial orientation or simultaneous biaxial orientation.
The following processing conditions are required in order to achieve the desired biaxial orientation:
With respect to stretching in a longitudinal direction, stretching conditions require 70°C
to 110°C of surface temperature of the heat roll. This temperature hence forth is called
TSMD-
The preferred value of TSMD should be in between TsMDmax and TsMDmin-
Where TsMDmax = Maximum allowable Stretch temperature in MD
TsMDmin-= Minimum allowable stretch temperature in MD
And TsMDmax- and TsMDmin- must satisfy the following conditions
0°C<= ΔTMC-TsMDmax <= 40°C
More preferably 0°C<= ΔTMC-TsMDmax <= 45°C
Most preferably 0°C<= ΔTMC-TSMDmax <= 50°C
And
20°C<= ΔTMC-TsMDmin <= 60°C
More preferably 15°C<= ΔTMC-TSMDmin <= 55 °C
Most preferably 10°C<= ΔTMC-TSMDmin <= 50°C
Stretch ratio in the range of 1.5 to 4.0, determined by a rotation speed ratio of a heated
slow-driving roll (upstream) and heated quick-driving roll (downstream).
With respect to stretching in a transverse direction (TD), stretching conditions require a
stretch ratio of about 3.0-5.0 using a tenter wherein both ends of film are fixed with clips.
This temperature is hence forth called TSTD
The preferred value of TSTD should be in between TSTDmax and TSTDmin
Where TSTDmax = Maximum allowable Stretch temperature in TD
TsTDmin-= Minimum allowable stretch temperature in TD
And TsTDmax and TsxDmin having following conditions:
-20°C<= ΔTMC- TsTDmax <=20°C
More preferably -25°C<= ΔTMC- TSTDmax <= 15°C

Most preferably -30°C<= ΔTMC- TSTDmax <= 10°C
And
0°C<= ΔTMC -TsTDmin <= 40°C
More preferably 5°C<=ΔTMC -TsTDmin <= 45°C
Most preferably 10°C<=ΔTMc -TSTDmin <= 50°C
In the preferred embodiment the thickness of polyester film of the invention is generally in the range of 1 to 150 micron, when above mentioned polyester film processing method is used.
Further- more the polyester film is coated with suitable antistatic compounds as internal use or coatings as external use to get desired film of surface resistivity less than 10 ohm-cm .Antistatic compounds/coatings are well known in the art for example like alkyl sulfonates, glycerol esters, long-chain aliphatic amines and amides, phosphate esters, quaternary ammonium salts, polyethylene glycols, polyethylene glycol esters, and ethoxylated long-chained aliphatic amines neutralized alcohol phosphates etc, .
Further- more the polyester film is suitably given metal vapor deposition for metallized applications, known metals like Aluminum, Silica etc. more preferably with Aluminum. And also used for applications of SiOx, AlOx coatings
The polyester film produced by the aforesaid process is optionally provided with
antistatic coatings having surface resistivity of less than 1014 ohm cm.
Further, the said polyester film is suitable for inorganic coatings with SiOx and AlOx and
is optionally vacuum metalized.
Furthermore, the said polyester is suitable for various organic coatings like vinylidene
chloride copolymers, thermosetting acrylic or methacrylic polymers, polyethyleneimines,
and like materials for improving the adhesion of the film to various polymers, and certain
water dispersible copolyester for laminations and others like polyurethane, acrylic, etc
The advantages of the disclosed invention are thus attained in an economical, practical, and facile manner. While preferred aspects and configurations have been shown and described, it is to be understood that various further modifications and additional

configurations will be apparent to those skilled in the art. It is intended that the specific embodiments and configurations herein disclosed are process illustrations of the preferred and best modes for practicing the invention, and should not be interpreted as limitations on the scope of the invention.
Following test methods and examples were used to characterize the films however the present invention is not limited to these test methods and examples.
Test methods Intrinsic Viscosity:
The Intrinsic Viscosity is measured by taking 0.3 gms of polyester sample in 30 ml of 60:40 wt by wt mixture of phenol and tetrachloroethane. The polyester sample is heated in oven to dissolve the polyester. Take the efflux time of solution and solvent at 25°C. CALCULATION
(Equation Removed)
R.V.= T2/T1
Where Tl = Efflux time of solvent T2 = Efflux time of solution.
COOH Value:
The COOH value is measured by taking 1.5 gms of polyester sample and dissolving it in 30 ml of 40:60 wt by wt mixture of Phenol and Chloroform and tested using KOH.
CALCULATION:
(Equation Removed)
Where N = Normality of KOH solution.
V soln. = ml of KOH soln. consumed for sample.

V blank = ml of KOH soln. consumed for blank.
Color Value 'b':
The color value of the film is tested by using the Hunter ColorQuest.
Example -1:
The slurry of Terephthalic acid and Ethylene glycol is made containing additives like catalyst, heat stabilizer etc. The mixed slurry is reacted in melt phase reactor to prepare Polyester melt having an I.V of 0.625dL/gm. The reaction occurs where intermediate polyester and partial continuous polyester prepared in same reactor and partial continuous polyester is sent to continuous polyester for continuous polyester formation. The polyester is then filtered and pumped to film formation die to form the film. The melts is cooled over the chilled roll and further stretched in machine direction at 90°C by 3 times and in transverse direction at 110°C by 4 times and subjected to heat treatment of 230°C for a period of lOsec. The Biaxial oriented film so prepared is of 23 micron thickness.
Example -2-6:
The polyester film is obtained from example 1 in the same way except melt recycled polyester is added at different ratio to intermediate continuous polyester melt where melt recycled polyester has I.V of 0.52.
Example -7-8:
The polyester film is obtained from example 1 in the same way except melt recycled polyester is added at different I.V of continuous polyester melt where melt recycled polyester has I.V of 0.52.

Example -9-13:
The polyester film is obtained from example 1 in the same way except glycolized recycled polyester is added at different ratio to intermediate continuous polyester melt where glycolized polyester is produced from mixing one weight part of recycled polyester and four weight parts of ethylene glycol.
Example -14-15:
The polyester film is obtained from example 1 in the same way except glycolized recycled polyester is added at different I.V of continuous polyester melt where glycolized polyester is produced from mixing one weight part of recycled polyester and four weight parts of ethylene glycol
Example -16:
The polyester film obtained where base layer is made of polyester as of Ex - 4 and other layers made by melting of polyester having I.V 0.612. The melt if base layer and other layers are passed through a common die. The melt is cooled over the chilled roll and further stretched in machine direction at 90°C by 3 times and in transverse direction at 110°C by 4 times and subjected to heat treatment of 230°C for a period of 10sec. The Biaxial oriented film so prepared is of 25 micron thickness having 23 micron base layer and 1 micron each of other layers Example -17:
The polyester film obtained where base layer is made of polyester as of Ex - 11 and other layers made by melting of polyester having I.V 0.612. The melt if base layer and other layers are passed through a common die. The melt is cooled over the chilled roll and further stretched in machine direction at 90°C by 3 times and in transverse direction at 110°C by 4 times and subjected to heat treatment of 230°C for a period of 10sec. The Biaxial oriented film so prepared is of 25 micron thickness having 23 micron base layer and 1 micron each of other layers

(Table Removed)


In the example 2-6, different amount of melt extruded recycled polyester is added at partial continuous polyester the weight ratio of melt extruded recycled polyester to partial continuous polyester is kept at 10:90, 20:80, 30:70, 40:60 and 50:50. The partial continuous polyester and melt extruded recycled polyester are mixed and sent to continuous polyester reactor for continuous polyester formation. It is observed that with the increase of melt extruded recycled polyester from 10-30wt% there is hardly any change in properties but at amount above 30wt%, the change is fast which is evident with the increase in 'b value' and 'COOH value'.
In the example 7, the melt extruded recycled polyester is added to the intermediate polyester of I.V 0.109. It is observed that no film formation occurs due to continuous breakdown in the production.
In the example 8, the melt extruded recycled polyester is added after partial continuous polyester formation of I.V 0.509. It is observed that mixing of melt extruded recycled polyester and continuous polyester require a high shear which causes the deterioration in properties of the melt.
In the example 9 to 13 different amount of glycolized recycled polyester is added at partial continuous polyester the weight ratio of melt extruded recycled polyester to partial continuous polyester is kept at 10:90, 30:70, 50:50, 60:40 and 70:30. The partial continuous polyester and glycolized recycled polyester are mixed and sent to continuous polyester reactor for continuous polyester formation. It is observed that with the increase of glycolized recycled polyester from 10-50wt% there is hardly any change in properties

but at amount above 50wt%, the change is fast which is evident with the increase in 'b value' and 'COOH value'.
In the example 14, the glycolized recycled polyester is added to the intermediate polyester of I.V 0.110. It is observed that no film formation occurs due to continuous breakdown in the production.
In the example 15, the glycolized recycled polyester is added after partial continuous polyester formation of I.V 0.511. It is observed that mixing of melt extruded recycled polyester and continuous polyester require a high shear which causes the deterioration in properties of the melt.
In example 16, coextruded polyester film is made where outer layers are made by melting of polyester chips of I.V 0.611 and base layer is made as that of example 4. It is observed that polyester film is formed with no change in properties.
In example 17, coextruded polyester film is made where outer layers are made by melting of polyester chips of I.V 0.611 and base layer is made as that of example 11. It is observed that polyester film is formed with no change in properties.
ADVANTAGES OF THE INVENTION
The main advantage of the invention is to provide a continuous manufacturing of the biaxial oriented polyester film directly from the continuous polyester melt, so that it minimise the waste production and to reuse the waste generated in the process. Another advantage of the present invention is to provide a process wherein the recycled polyester is incorporated in the continuous polyester melt.
Another advantage of the present invention provide a process wherein the continuous polyester melt is branched off into more than one stream and can produce single layer polyester film, multilayer polyester film and polyester granules simultaneously.

WE CLAIM
1. A process of manufacturing bi-axially oriented polyester film directly from the
continuous polymer melt comprising the steps of:
a) reacting monomer or monomer mixtures to produce intermediate polymer melt or partial continuous polymer melt,
b) adding recycled continuous polymer melt to the intermediate polymer melt or partial continuous polymer melt of step (a) to obtain continuous polymer,
c) branching continuous polymer melt of step (b) into at least two multiple streams,
d) sending at least one branched stream to the cutter for pellet formation,
e) controlling the pressure and mass flow of continuous polymer melt in each divided stream of each branch streams,
f) allowing the polymer melt of each divided streams of step (e) to a die, quenching and orienting the resultant melt streams in order to obtain the desired bi-axially oriented polyester film.

2. The process as claimed in claim 1, wherein the intermediate polymer melt of step (a) having intrinsic viscosity in the range of 0.05 to 0.15 dl/gm.
3. The process as claimed in claim 1, wherein the partial continuous polymer melt of step (a) having intrinsic viscosity in the range of 0.20 to 0.35 dl/gm.
4. The process as claimed in claim 1, wherein the continuous polymer melt of step (b) having intrinsic viscosity in the range of 0.40 to 1.0 dl/gm.
5. The process as claimed in claim 1, wherein in step (a) the monomer/ monomer mixtures is selected from the di-carboxylic acid or glycol or mixture thereof.
6. The process as claimed in claim 1, wherein in step (a) & (b) the intermediate or partial continuous polymer or continuous polymer melt is prepared at a temperature in the range of 200°C to 300°C.
7. The process as claimed in claim 1, wherein in step (f) the quenching is carried out at a temperature in the range of 20°C to 50°C.

8. The process as claimed in claim 5, wherein the dicarboxylic acid is selected from the group comprising 2, 6-naphthalene dicarboxylic acid, isophthalic acid, and phthalic acid, aliphatic dicarboxylic acids like adipic acid and or esters of same along with dimethyl terephthalate or terephthalic acid when used as group of dicarboxylic acids and mixture thereof.
9. The process as claimed in claim 5, wherein the glycols are selected from the group comprising did ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, trans-1, 4-cyclohexanediol and cis-l,4-cyclohexanediol, CHDM along with ethylene glycol when used as group of glycols and mixture thereof.
10. The process as claimed in claim 5, wherein the di-carboxylic acid and glycol are mixed in the ratio of 1:0.3 to 1:0.5.
11. The process as claimed in claim 5, wherein the monomer are optionally added with additives such as antiblocking agents, antioxidants, stabilizers etc.
12. The process as claimed in claim 1, where intermediate polymer melt formation, partial continuous polymer melt formation and continuous polymer melt formation is carried out in a single reactor or single reactor with multiple sections or in multiple reactors.
13. The process as claimed in claim 1, wherein the bi-axial oriented polyester film having shape and size according to the die design.
14. The process as claimed in claim 1, wherein the bi-axial oriented polyester film comprising at least one base or inner layer (B) and at least one outer or another layer (A or C), preferred base layer (B) from continuous polymer melt and other layers being prepared by polymer melt obtained from pellets.
15. The process as claimed in claim 1, wherein recycled continuous polymer melt contains any of the following melts either

• recycled polyester formed by extrusion melting of recycled polyester in weight upto 1.5 times of continuous polyester, or
• Glycolized recycled polyester formed by mixing of melt extruded recycled polyester with monomer / monomer mixture in weight ratio of 10:1 to 1:10 adding glycolized recycled polyester in weight upto 2 times of continuous polyester.

16. The process as claimed in claims 1, wherein the recycled polymer melt include the recycled material produced from the continuous polymer processing and / or waste material obtained form other sources like post consumable recycles.
17. The process as claimed in claim 1, where the continuous polymer is branched cither from a single position or multiple positions of branched stream.
18. The process as claimed in claim 1, wherein each branched stream having flow rate controlling means, pressure gauge to maintain strict and rigid control on the flow rate and pressure between every branched stream of polymer melt.
19. The process as claimed in claim 13, wherein another layers is either same as that of base layer or different from the base layer.
20. The process as claimed in claim 1, wherein each branched stream having a provision of online viscosity measurement.
21. The process as claimed in claims 1 to 19, wherein orientation of polyester film is carried out by heating the polyester melt obtained in step (f) and orienting the said film in biaxial direction, wherein the difference between ΔTMC (the difference in melting temperature and crystallization temperature of the said film) and TSMD (stretching temperature in machine direction) is in the range of 0 C to 50 C, and the difference between ΔTMC (the difference in melting temperature and crystallization temperature of the said film) and TSTD (stretching temperature in transverse direction) is in the range of -30°C to 50°C.
22. The process as claimed in claim 20, wherein polyester film is optionally provided with an antistatic coating to get surface resistivity of film less than 10 ohm cm.
23. The process as claimed in claim 20, wherein the polyester film is suitable for coating with SiOx and AlOx.
24. The process as claimed in claim 20, wherein the polyester film is optionally vacuum metallized.
25. The process as claimed in claim 20, wherein the polyester film of having other layer thickness is in the range of 0.5 to 10 micron and base layer thickness range from 2.5 to 300 micron
26. The method as claimed in claims 1 to 24, wherein bi-axially polyester film having three layers such as ABC, BBB, ABA and AAB.