FIELD OF THE INVENTION
The present invention relates to modified copolyester with improved performance
suitable for use in making packaging containers. More particularly, the invention
relates to a process for the preparation of polyethylene terphthalate (PET)
copolyester and products made thereof with improved thermal, mechanical, optical,
and superior barrier properties.
BACKGROUND OF THE INVENTION
Due to growing demand of reducing the logistic costs in food packaging industry,
glass and metal packaging materials have been replaced by plastic materials in recent
few years. The advantage of using plastic material are manifold such as reductions in
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weight and cost, and lower risk of breakage, however the barrier properties of these
materials are invariably different from glass and metal packaging materials, that
further impacts the shelf stability of the product.
A major concern for many products, and particularly for beverages like beer, is
oxidation degradation by oxygen ingress causing taste changes and darkening of the
beer, flattening of taste by carbon dioxide loss and damage due to W light. Over the
planned shelf life of a bottle about 1 ppm oxygen maximum ingress into the bottle is
acceptable. The egress of carbon dioxide from the beverage through the bottle walls
also has to be attenuated to a minimum. For successful conversion from glass to
plastic it is very essential to consider oxygen, carbon dioxide, water vapor and flavor
scalping as they affect the quality of the products particularly when stored over
extended periods of time.
Polyethylene terephthalate polyesters are widely used for fabricating various
components such as fibers, sheets, tubes and container owing to their superior
mechanical, thermal and gas barrier properties, chemical resistance, flavor-retaining
property, transparency, hygienic property, easy of processability, recyclability, and
suitability for food contact applications etc.
Polyethylene terphthalate, because of its comparatively better thermal, mechanical,
optical and barrier properties, is preferred over other polyesters in packaging
applications e.g. use of PET in making beverage container, beer keg, etc. Therefore,
Polyethylene terphthalate resins are widely used in the food packaging industry to
manufacture bottles and films. PET bottles are used for the carbonated soft drink,
fruit juice and mineral water. These products have a shelf life of 8-12 weeks and over
this period the gas permeability properties of PET are considered sufficient.
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However, alcoholic beverages like beer are much more sensitive to oxygen and
carbon dioxide diffusion either into or out of the bottle. When this sensitivity to
migrating gases is combined with the need for a longer shclf life, it is necessary to
improve on the gas permeability properties of PET.
Replacing the glass and metal packaging by polyethylene terephthalate based material
is very tedious task that requires maintaining good barrier, optical, thermal and
mechanical properties of the bottle so as to improve the shelf life of the food products
being packaged.
Various technologies as to making of PET based containers for food packaging exists
in the market. Containers can be made from non-PET polyesters as well with lower
gas permeability, such as polyethylene naphthalate (PEN). However, there are
difficulties in stretch blow molding these bottles and the technology has achieved
limited success due to erratic behavior and haze in injection molding with
conventional technology. Further difficulties are encountered in bottle blowing of
PEN polymer or its alloy/blends with PET. On the whole, PEN containers are also
very expensive.
Mono layer polyethylene terephthalate bottles made fiom PET blended or
compounded with naphthalates and isophthalates, such as terpolymer or TIN
polymer, have also been attempted with no significant success.
A few patents viz. US8124202, US6355738, and US200602446245 disclose use of
PET in combination of other polyesters or additives to make monolayers or
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multilayers containers with good barrier properties and thermal properties. 1
US20060182911 patent application discloses blends of barrier resins consisting of a
composition of Polyethylene terephthalate and polytrimethylene naphthalate, or
polyethylene terephthalate and polybutylene naphthalate exclusively for packaging
beverages like beer in a monolayer bottle outperforming the existing other barrier
multi-layer bottles is described. The blends of PETIPTN and PETJPBN are produced
by using in situ polymerization or melt blending the two polymers or compounding
the two polymers to get the PTN and PBN in a PET polymer matrix. The composition
of PET blends with PTN and PBN additionally contains other barrier improving
additives.
However, the polybutylene naphthalate (PBN) used above is a normal PBN that does
not reflect required optical properties to achieve excellent transparency of bottles or
containers made from blend thereof as PBN has opaque nature. Therefore when
normal PBN is used as such in manufacturing polyester containers, it creates haze in
the containers. In order to overcome this problem there is a need to use modified PBN
having excellent transparency to avoid haze in the containers.
There is still need to modify polyethylene terphthalate by using modified
polybutylene naphthalate to achieve excellent transparency and improved barrier
properties of the polyester materials.
The present invention overcomes the foregoing problem by providing a modified
polyethylene terphthalate for use in making containers both in monolayer and
multilayer construction with improved thermal, mechanical, optical and superior
barrier properties.
Thus, modified copolyester becomes usable in packaging application for making
containers with enhanced gas barrier properties, longer shelf life and and further
recycled in PET stream.
OBJECT OF THE INVENTION:
An object of the present invention is to provide a modified copolyester with
improved thermal, mechanical, optical and superior barrier properties.
Another object of the present invention is to provide a copolyester for use in making
transparent packaging containers with improved gas barrier properties.
Yet, another object of the present invention is to provide modified copolyester for
use in making containers with lower Oxygen Transfer Rate (OTR), Water Vapour
Transfer Rate (WVTR), and Carbon Dioxide Transfer Rate (C02 TR) which are
suitable for food contact applications.
Yet, another object of the present invention is to provide modified polyethylene
terphthalate copolyester having improved thermal, mechanical, optical, and barrier
properties.
Further object of the present invention is to provide a process for preparing the
modified copolyester with excellent transparency and barrier properties.
Still further object of the present invention is to provide a packaging material, a
packaging container or a preform which is capable of withstanding high temperature
without undergoing any visual deformation and shrinkage beyond acceptable limits
and has improved shelf life due to its superior barrier properties.
Further object of the present invention is to provide a process for preparing clear to
transparent containers comprising modified polyethylene terphthalate polyester and
naphthalate polyester with superior barriers properties.
Further object of the present invention is to prepare containers using the modified
copolyester of polyethylene terphthalate through Injection Blow Moulding (IBM),
Injection Stretch Blow Moulding (ISBM), and Extrusion Blow Moulding (EBM) and
the like methods by avoiding thermal haze occurring due to faster crystallization of
normal polybutylene naphthalate.
Other objects and advantages of the present invention will be more apparent from the
following description which is not intended to limit the scope of the present
disclosure.
SUMMARY OF THE INVENTION:
The present invention provides a process for preparing a copolyester composition
having improved barrier properties, the process comprising: contacting a
terephthalate copolyester composition of modified transparent polybutylene
naphthalate and other essential additives in presence required reaction conditions and
suitable polymerizatiori catalysts.
In one embodiment of the present invention, a copolyester having intrinsic viscosity
greater than 0.50 dLIgm, for manufacture of containers that can withstand an ambient
temperature of about 70 O C, comprises: at least one terephthalate polyester
composition; and a modified transparent polybutylene naphthalate, wherein the
modified polybutylene naphthalate comprises naphthalene dicarboxylic acid, 1,4-
butane diol, and isophthalic acid or monoethylene glycol or diethylene glycol or
cyclohexane dimethanol or polyethylene naphthalate, at least one nucleating agent,
and a modified nanoclay.
In one aspect of the invention, the terephthalate polyester composition comprises of
polyethylene terphthalate (PET), and polyethylene naphthalate (PEN) or polyethylene
isosorbide terephthalate (PEIT), or combination thereof.
In another aspect of the invention, the polyethylene naphthalate (PEN) in the
terephthalate polymer composition is used in an amount up to 10 wt. % based on total
weight of the copolyester and polyethylene isosorbide terephthalate (PEIT) is used in
an amount up to 10 wt.% based on total weight of the polyester.
In another preferred aspect of the invention the claimed copolyester is modified
polyethylene terphthalate polyester having improved thermal, mechanical, optical,
barrier properties, and excellent transparency.
In another aspect the copolyester of the invention is used in packaging applications
such as preparing transparent containers for beer packaging, and other beverage
applications.
Yet another aspect of the invention is that the packaging application of the coplyester
may be a packaging material, a packaging container, or a preform capable of
withstanding high temperature up to 75 OC without undergoing any visual
deformation and shrinkage beyond acceptable limit which is 2.5%, preferably 1.5%.
In another aspect, the packaging material of the claimed polyester may he transparent
containers for applications in beer and other beverage and food packaging.
In one preferred embodiment of the present invention, the copolyester used in the
process of the present invention comprises of polyethylene terphthalate (PET), and
polyethylene naphthalate (PEN) or polyethylene isosorbide terephthalate (PEIT), or
combination thereof; and copolymer of the polybutylene naphthalate comprising
naphthalene dicarboxylic acid, 1,4-butane diol, and isophthalic acid or monoethylene
glycol or diethylene glycol or cyclohexane dimethanol or polyethylene naphthalate
polyester.
A process of preparing a copolyester having intrinsic viscosity greater than 0.50
dL/gm, for manufacture of containers that can withstand an ambient temperature of
about 75 O C, comprises steps of reacting terephthalic acid or ester thereof with
monoethylene glycol and other diols, monomers, a nucleating agent, and a modified
nanoclay at temperature about 150 "C to 270 OC in presence of catalysts under
atmospheric pressure to obtain pre-polymers; mixing polyethylene naphthalate and
modified transparent polybutylene naphthalate in the melt to obtain uniform reaction
mixture consisting of said prepolymer; polymerizing said reaction mixture at
temperature at about 270°C and 295°C under pressure below 1 mili bar to obtain melt
polymer of the required degree of polymerization; extruding the melt polymer to
obtain amorphous granules of intrinsic viscosity >0.40 dL/gm followed by
crystallization thereof under atmospheric pressure and temperature at about 120°C
and 140°C; and solid state polymerizing the crystalized polymer to upgrade the
intrinsic viscosity to above 0.50 dL/gm.
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I
In one embodiment of the present invention, the terephthalate copolyester used in the
process of the present invention comprises dicarboxylic acid, diol, at least one
additional comonomer, polymer catalysts, and at least one agent.
In an embodiment, the copolyester used in the process can alternatively be obtained
by mechanical or chemical recycling of recycled polyethylene terephthalate (RPET)
flakes.
In one aspect, the modified polyethylene terphthalate is obtained by incorporating at
least one comonomers and/or polymer viz. modified transparent polybutylene
naphthalate (PBN), before or during or after the esterification or polycondensation or
polymerization. In one another aspect, the modified polybutylene naphthalate
copolymer can be inducted in extruder while blending the copolyester and modified
polybutylene naphthalate copolymer.
The induction of the comonomers and/or copolyester as per the process of the present
invention results in the desired barrier polymer with enhanced barrier properties and
excellent transparency.
In an embodiment of the present invention, the copolyester composition can be
prepared by reacting polyethylene terphthalate with polyethylene naphthalate or
polyethylene isosorbide naphthalate, and modified polybutylene naphthalate.
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4
In an embodiment of the present invention, the modified polyethylene terphthalate
can be prepared by reacting polyethylene terphthalate with isosorbide and modified
polybutylene naphthalate.
In an embodiment of the present invention, the modified polyethylene terphthalate
copolyester can be prepared by esterification and subsequent polymerization of
terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid or 2,6-dimethyl
carboxylate, monoethylene glycol, butane diol and at least one agent in presence of
polymer catalysts. The esterification is carried out at temperature kom about 220 to
705 "C and the polymerization is carried out at temperature range fiom about 270 to
290 O C .
In an embodiment, the polyester used in the process can be manufactured from
method comprising recycling recycled polyethylene terephthalate flakes by its
glycolysis and subsequent polymerization to yield PET; and further adding
isophthalic acid, polyethylene naphthalate and polybutylene naphthalate with or
without its modification.
In another embodiment, the modified polybutylene naphthalate can alternately be
blended with the copolyester after completion of the polycondensation reaction to
obtain the modified copolyester and products thereof.
In one aspect of the invention, the present invention relates to products comprising
the modified copolyester, modified or unmodified polybutylene naphthalate and at
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least one essential additive. !
The modified copolyester obtained in accordance with the process of the present
invention can be used in packaging applications such as preparing transparent
containers, beer keg or products thereof. The material or container obtained from the
copolyester of the present disclosure has comparatively improved thermal,
mechanical and optical and barrier properties. More specifically the products have
lower oxygen transfer rate (oxygen ingress), Carbon dioxide transfer rate, water
vapor transfer rate and inert gas transfer rate while achieving better transparency and
good thermal and mechanical properties. In one aspect of the present invention, the
copolyester can be used in making dish washable containers, aerosol containers, and
other containers capable of undergoing process pasteurization process for packaging
food items as well as no food products.
The present invention relates to modified copolyester used for making transparent
and gas barrier containers, monolayer or multilayers, by using at least one moulding
process selected from the group consisting of injection blow moulding (IBM),
injection stretch blow moulding (ISBM), extrusion blow moulding (EBM), heat set
blowing process, and other blow moulding techniques.
The present invention relates to modified copolyester used for making the transparent
beer keg with better barrier, thermal, mechanical and optical properties by using at
least one moulding process selected from the group consisting of IBM, ISBM, EBM,
and EMB including normal blow moulding and heat set blowing process.
The modified copolyester used for making containers can be polyethylene isosorbide
1
terphthalate butylene naphthalate (PEITBN), polyethylene terphthalate butylene
naphthalate (PETBN).
Other objects, features and advantages of the product , its composition, method and
uses described herein will become apparent kom the following description . It should
be understood , however, that the detailed description and the specific example ,
while indicating specific embodiments, are given by way of illustration only, since
various changes and modifications within the spirit and scope of the disclosure will
become apparent to those skilled in the art from the deatiled description.
DETAILED DESCRIPTION OF THE INVENTION:
Various embodiments are described hereinafter. It should be noted that the specific
embodiments are not intended as an exhaustive description or as a limitation to the
broader aspects discussed herein. One aspect described in conjunction with a
particular embodiment is not necessarily limited to that embodiment and can be
practiced with any other embodiment(s).
As used herein, "about" will be understood by persons of ordinary skill in the art and
will vary to some extent depending upon the context in which it is used. If there are
uses of the term which are not clear to persons of ordinary skill in the art, given the
context in which it is used, "about" will mean up to plus or minus 10% of the
particular term.
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The use of the terms "a" and "an" and "the" and similar referents in the context of
describing the elements (especially in the context of the following claims) are to be
construed to cover both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. Recitation of ranges of values herein are merely
intended to serve as a shorthand method of referring individually to each separate
value falling within the range, unless otherwise indicated herein, and each separate
value is incorporated into the specification as if it were individually recited herein.
All methods described herein can be performed in any suitable order unless otherwise
indicated herein or otherwise clearly contradicted by context. The use of any and all
examples, or exemplary language (e.g., "such as") provided herein, is intended
merely to better illuminate the embodiments and does not pose a limitation on the
scope of the claims unless otherwise stated. No language in the specification should
be construed as indicating any non-claimed element as essential.
In general, "substituted" refers to an alkyl, alkenyl, alkynyl, aryl, or ether group, as
defined below (e.g., an alkyl group) in which one or more bonds to a hydrogen atom
contained therein are replaced by a bond to non-hydrogen or non-carbon atoms.
Substituted groups also include groups in which one or more bonds to a carbon(s) or
hydrogen(s) atom are replaced by one or more bonds, including double or triple
bonds, to a heteroatom. Thus, a substituted group will be substituted with one or
more substituents, unless otherwise specified. Iu some embodiments, a substituted
group is substituted with 1,2,3,4, 5, or 6 substituents. Examples of substituent
groups include: halogens (i.e., F, CI, Br, and I); hydroxyls; alkoxy, alkenoxy,
alkynoxy, aryloxy, aralkyloxy, heterocyclyloxy, and beterocyclylalkoxy groups;
carbonyls (0x0); carboxyls; esters; urethanes; oximes; hydroxylamines;
alkoxyamines; aralkoxyamines; thiols; sulfides; sulfoxides; sulfones; sulfonyls;
sulfonamides; amines; N-oxides; hydrazines; hydrazides; hydrazones; azides; amides;
ureas; amidines; guanidines; enamines; imides; isocyanates; isothiocyanates;
cyanates; thiocyanates; imines; nitro groups; nitriles (i.e., CN); and the like.
As used herein, C,-C,, such as Cl-C12, Cl-Cs, or Cl-Cs when used before a group
refers to that group containing m to n carbon atoms
As used herein, "alkyl" groups include straight chain and branched alkyl groups
having from 1 to about 20 carbon atoms (i.e., C1-Czo alkyl), and typically from 1 to
12 carbon atoms (i.e., Cl-Cl2 alkyl) or, in some embodiments, from 1 to 8 carbon
atoms (i.e., Cl-Cs alkyl). As employed herein, "alkyl groups" include cycloalkyl
groups as defined below. Alkyl groups may be substituted or unsubstituted. This
term includes, by way of example, linear and branched hydrocarbyl groups such as
methyl (CH3-), ethyl (CH3CH2-), n-propyl (CH3CH2CH2-), isopropyl ((CH3)2CH-),
n-butyl (CH~CHZCH~CHi~s-o)b,u tyl ((CH3)zCHCHz-), see-butyl
((CH~)(CH~CHZ)CH-t-)b, utyl ((CH3)3C-), n-pentyl (CH~CH~CHZCHZCH,-a)n,d
neopentyl ((CH3)3CCH2-). Representative substituted alkyl groups may be
substituted one or more times with, for example, amino, thio, hydroxy, cyano, alkoxy,
and/or halo groups such as F, C1, Br, and I groups. As used herein the term haloalkyl
is an alkyl group having one or more halo groups. In some embodiments, haloalkyl
refers to a per-haloalkyl group.
Cycloalkyl groups are cyclic alkyl groups such as, but not limited to, cyclopropyl,
cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. In some
embodiments, the cycloalkyl group has 3 to 8 ring members, whereas in other
embodiments the number of ring carbon atoms range from 3 to 5, 6, or 7. Cycloalkyl
groups may be substituted or unsubstituted. Cycloalkyl groups further include
polycyclic cycloalkyl groups such as, but not limited to, norbornyl, adamantyl,
bomyl, camphenyl, isocamphenyl, and carenyl groups, and fused rings such as, but
not limited to, decalinyl, and the like. Cycloalkyl groups also include rings that are
substituted with straight or branched chain alkyl groups as defined above.
Representative substituted cycloalkyl groups may be mono-substituted or substituted
more than once, such as, but not limited to: 2,2-; 2,3-; 2,4-; 2,5-; or 2,6-disubstituted
cyclohexyl groups or mono-, di-, or tri-substituted norbornyl or cycloheptyl groups,
which may be substituted with, for example, alkyl, alkoxy, amino, thio, hydroxy,
cyano, and/or halo groups.
As used herein, "aryl", or "aromatic," groups are cyclic aromatic hydrocarbons that
do not contain heteroatoms. Alyl groups include monocyclic, bicyclic and polycyclic
ring systems. Thus, aryl groups include, but are not limited to, phenyl, azulenyl,
heptalenyl, biphenylenyl, indacenyl, fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl,
naphthacenyl, chrysenyl, biphenyl, anthracenyl, indenyl, indanyl, pentalenyl, and
naphthyl groups. In some embodiments, aryl groups contain 6-14 carbons, and in
others from 6 to 12 or even 6-10 carbon atoms in the ring portions of the groups. The
phrase "aryl groups" includes groups containing fused rings, such as fused aromaticaliphatic
ring systems (e.g., indanyl, tetrahydronaphthyl, and the like). Aryl groups
may be substituted or unsubstituted.
The term "including" is used to mean "including but not limited to." "Including" and
"including but not limited to" are used interchangeably.
The term "degree of polymerization" (DP) is an art recognized term referring to the
number of monomer units in a polymer
The term "prepolymer" refers to a molecule of intermediate relative molecular mass,
the structure of which essentially comprises a small plurality of units derived,
actually or conceptually, from molecules of lower relative molecular mass.
The term "transparent PBN" refers to a modified Polybutylene naphthalate that can
achieve excellent transparency and improved barrier properties.
The term "diethylene content" refers to residue of diethylene glycol (DEG) present in
the final product and is determined by the method described in the example section of
the present disclosure.
The term "carboxylic end group content" refers to XOOH end group present at the
end of polymer chains and is determined by the method described in the example
section of the present disclosure.
The polyester obtained in accordance with the method of the present invention is
herein also referred as "modified polyethylene terephthalate" or "Modified
Copolyester" or "modified PET" or "modified polymer".
The term "intrinsic viscosity" (I.V.) as used herein is a measure of the molecular mass
of the polymer and is measured by dilute solution using a Ubbelohde viscometer. All
intrinsic viscosities are measured in a 60:40 mixture of phenol and stetrachloroethane
with 0.5 % concentration.
Ratios, concentrations, amounts, and other numerical data may be presented herein in
a range format. It is to be understood that such range format is used merely for
convenience and brevity and should be interpreted flexibly to include not only the
numerical values explicitly recited as the limits of the range, but also to include all
the individual numerical values or sub-ranges encompassed within that range as if
each numerical value and sub-range is explicitly recited. For example, 5 to 40 mole
% should be interpreted to include not only the explicitly recited limits of 5 to 40
mole %, but also to include sub-ranges, such as 10 mole % to 30 mole %, 7 mole %
to 25 mole %, and so forth, as well as individual amounts, including fractional
amounts, within the specified ranges, such as 15.5 mole %, 29.1 mole %, and 12.9
mole %, for example.
In one aspect, the present inventors have found that the incorporation of additional
copolymers and/or comonomers into polyethylene terphthalate (PET) results in a
modified copolyester with new set of properties useful for making packaging
containers. The modified copolyester so obtained shows improved, thermal,
mechanical and barrier properties.
In one aspect is provided a process of preparing a copolyester having intrinsic
viscosity greater than 0.50 dL/gm, for manufacture of containers that can withstand
an ambient temperature of about 75 O C, comprising:reacting terephthalic acid or ester
thereof with monoethylene glycol and other diols, monomers, a nucleating agent, and
a modified nanoclay at temperature about 150 "C to 270 "C in presence of catalysts
under atmospheric pressure to obtain pre-polymers; mixing polyethylene naphthalate
and modified transparent polybutylene naphthalate in the melt to obtain uniform
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1 reaction mixture consisting of said prepolymer; polymerizing said reaction mixture at
temperature at about 270°C and 295°C under pressure below 1 mili bar to obtain melt
polymer of the required degree of polymerization; extruding the melt polymer to
obtain amorphous granules of intrinsic viscosity >0.40 dL/gm followed by
crystallization thereof under atmospheric pressure and temperature at about 120°C
and 140°C; and solid state polymerizing the crystalized polymer to upgrade the
intrinsic viscosity to above 0.50 dL/gm.
The prepolymers of the process are obtained esterification reaction is carried out at
temperature about 220°C and 270°C, and ester interchange reaction is carried out at
temperature about 150 "C to 200 OC.
In an aspect of the invention, the modified polybutylene naphthalate is used in the
process in an amount of up to 30 wt. % based on total weight of the copolyester.
In some embodiments modified transparent polybutylene naphthalate comprises
naphthalene dicarboxylic acid, 1,4 butane diol, and isophthalic acid or monoethylene
glycol or diethylene glycol or cyclohexane dimethanol or polyethylene naphthalate,
and at least one nucleating agent and modified clay.
In some embodiments, the nanoclay used in the process is at least one selected from
the group consisting of calcium silicate, nano silica powder, talc, microtalc, aclyn,
kaolinite, montmorillonite, synthetic mica, calcium sulfide, boron nitride, barium
sulfate, aluminum oxide, neodymium oxide and a metal salt of phenyl phosphonate.
4
In one aspect, a process ofpreparing the modified copolyester is provided wherein
the crystalised modified copolyester exhibits an intrinsic viscosity greater than about
0.75 dL1g. In some embodiments, the LV. is greater than about 0.5 dL/g. In some
embodiments, the I.V. is greater than about 0.3 dL/g. In some embodiments, the LV.
is greater than about 0.25 dL1g. In some embodiments, the I.V. is greater than about
0.2 dL/g. In some embodiments, the LV. is greater than about 0.15 dLlg. In some
ernbodimcnts, the I.V. is greater than about 0.10 dL1g. The crystalized modified
copolyester made from the process of the present invention may exhibit an intrinsic
viscosity fiom about 0.1 dLlg to about 1 dL1g. This may include an LV. from about
0.2 dL/g to about 1 dLIg, from about 0.3 dLlg to about 0.75 dL/g, or from about 0.4
dLlg to about 0.5 dLlg, and ranges between and including any two of these values. In
some emboditnents, the crystallized modified copolyester exhibits an intrinsic
viscosity greater than 0.40 dL/g.In one aspect, a process of preparing a crystallized
modified co-polyester is provided wherein the crystallized crystallized modified copolyester
comprises polyethylene naphthalate content of greater than or equal to
about 1 wt%. This may include a polyethylene naphthalate content of greater than or
equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to
about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about
25 wt%, or greater than or equal to about 50 wt%. The crystallized modified PET
copolyester may comprise a polyethylene naphthalate content from about 0.1 wt% to
about 80 wt%, from about 5 wt% to about 50 wt%, from about 10 wt% to about 45
wt%, from about 13 wt% to about 40 wt%, from about 15 wt% to about 40 wt%, or
from about 20 wt% to about 30 wt%, and ranges between and including any two of
these values. In some prefened embodiments, the crystallized modified PET
copolyester may comprise a polyethylene naphthalate content of up to 10 wt%.
In one aspect, a process ofpreparing a crystallized modified co-polyester is provided
wherein the crystallized modified co~polyesterc omprises polyethylene isosorbide
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terephthalate (PEIT) content of greater than or equal to about 1 wt%. This may
include a polyethylene isosorbide terephthalate (PEIT) content of greater than or
equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to
about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about
25 wt%, or greater than or equal to about 50 wt%. The crystallized modified PET
copolyester may comprise a polyethylene isosorbide terephthalate (PEIT) content
from about 0.1 wt% to about 80 wt%, from about 5 wt% to about 50 wt%, from about
10 wt% to about 45 wt%, from about 13 wt% to about 40 wt%, from about 15 wt% to
about 40 wt%, or from about 20 wt% to about 30 wt%, and ranges between and
including any two of these values. In some preferred embodiments, the crystallized
modified PET copolyester may comprise a polyethylene isosorbide terephthalate
(PEIT) content of up to 10 wt%.
In one aspect, a process of preparing a crystallized modified co-polyester is provided
wherein the crystallized modified co-polyester comprises modified transparent
polybutylene naphthalate content of greater than or equal to about 1 wt%. This may
include a modified transparent polybutylene naphthalate content of greater than or
equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to
about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about
25 wt%, or greater than or equal to about 50 wt%. The crystallized modified PET
copolyester may comprise a modified transparent polybutylene naphthalate content
from about 0.1 wt% to about 80 wt%, from about 5 wt% to about 50 wt%, from about
10 wt% to about 45 wt%, from about 13 wt% to about 40 wt'Yo, from about 15 wt% to
about 40 wt%, or from about 20 wt% to about 30 wt%, and ranges between and
including any two of these values. In some preferred embodiments, the crystallized
modified PET copolyester may comprise modified transparent polybutylene
naphthalate content of up to 30 wt%.
1
4
The process further includes subjecting the crystallized copoylester to solid state
polymerization (SSP). The SSP leads to an increase in the molecular weight andlor
intrinsic viscosity of the co-polyester product and reduction in oligomer contents.
In another aspect of the invention, the solid state polymerization reaction is carried
out in batch SSP unit under pressure below 2 mili bar, or in continuation SSP in
presence of nitrogen gas.
In another aspect, provided is a process of preparing a sulfonated co-polyester which
involves used of modified transparent polybutylene terephthalate. The modified
transparent polybutylene terephthalate polyester helps to obtain transparent PET
copolyester with improved barrier properties.
The prepolymers can be prepared from two or more dicarboxylic acid residues. The
dicarboxylic acid residue may be derived from a aliphatic dicarboxylic acid, an
aliphatic dicarboxylate, a cycloaliphatic dicarboxylic acid, a cycloaliphatic
dicarboxylate, an aromatic dicarboxylic acid, or an aromatic dicarboxylate or a
combination of any two or more thereof. Examples of aromatic dicarboxylic diacids
include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, and
ester derivatives thereof. Examples of aliphatic diacids include adipic acid, glutaric
acid, succinic acid, azelaic acid, or ester derivatives thereof.
The dicarboxylic acid residue may be from terephthalic acid, dimethyl terephthalate,
dimethyl isophthalate, dimethyl-2,6-naphthalate, 2,7-naphthalenedicarboxylic acid,
dimethyl-2,7-naphthalate, 3,4'-diphenyl ether dicarboxylic acid, dimethyl-3,4'-
diphenyl ether dicarboxylate, 4,4'-diphenyl ether dicarboxylic acid, dimethyl-4,4-
I
diphenyl ether dicarboxylate, 3,4'-diphenyl sulfide dicarboxylic acid, dimethyl3,lt'-
diphenyl sulfide dicarboxylate, 4,4'-diphenyl sulfide dicarboxylic acid, dimethyl-4,4'-
diphenyl sulfide dicarboxylate, 3,4'-diphenyl sulfone dicarboxylic acid, dimethyl-3,4'-
diphenyl sulfone dicarboxylate, 4,4'-diphenyl sulfone dicarboxylic acid, dimethyl-
4,4'-diphenyl sulfone dicarboxylate, 3,4'-benzophenonedicarboxylic acid, dimethyl-
3,4'-benzophenonedicarboxylate, 4,4'-benzophenonedicarboxylic acid, dimethyl-4,4'-
benzophenonedicarboxylate, 1,4-naphthalene dicarboxylic acid, dimethyl-1,4-
naphthalate, 4,4'-methylene bis(benzoic acid), dimethyl-4,4'-methylenebis(benzoate),
dimethyl oxalate, malonic acid, dimethyl malonate, dimethyl succinate,
methylsuccinic acid, 2-methylglutaric acid, 3-methylglutaric acid, dimethyl adipate,
3-methyladipic acid, dimethyl azelate, sebacic acid, 1,ll-undecanedicarboxylic acid,
I ,lo-decanedicarboxylic acid, undecanedioic acid, 1,12-dodecanedicarboxylic acid,
hexadecanedioic acid, docosanedioic acid, tetracosanedioic acid, dimer acid,
dimethyl-1,4-cyclohexanedicarboxylate,d imethyl-1,3-cyclohexanedicarboxylate,1 ,lcyclohexanediacetic
acid, metal salts of 5-sulfo-dimethylisophthalate, maleic
anhydride, or a combination of any two or more thereof.
Some non-limiting examples of dicarboxylic acid residue are isophthalic acid, 2,6-
naphthalene dicarboxylic acid, oxalic acid, maleic acid, succinic acid, glutaric acid,
dimethyl glutarate, adipic acid, 2,2,5,5-tetramethylhexanedioic acid, pimelic acid,
suberic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-
cyclohexanedicarboxylic acid, 1,l-cyclohexanediacetic acid, fumaric acid, maleic
acid, hexahydrophthalic acid, and phthalic acid.
The prepolymer can be prepared using suitable methods known in the art. For
example, the dicarboxylic acid or ester thereof can be reacted with an alkylene diol at
4
a suitable temperature and pressure for a sufficient amount of time to obtain the pre- I
polymer. Suitable esterification conditions can be employed for the preparation of
the prepolymer. For example, the reaction can be conducted at a temperature of
about 300 "C or below, about 200 "C or below, about 100 "C or below, at about 80
"C or below, at about 50 "C or below, at about 45 OC or below, at about 40 "C or
below, at about 35 "C or below, at about 30 "C or below, at about 25 OC or below or
at about 20 O C or below, and ranges between and including any two of these values.
The reaction can be conducted at a pressure of about 1 bar to about 30 bars, about 2
bars to about 20 bars, about 3 bars to about 10 bars, about 4 bars to about 5 bars, and
ranges between and including any two of these values. In some embodiments, the
reaction pressure is up to about 20 bars, up to about 10 bars, up to about 5 bars, up to
about 3 bars, up to about 2 bars, up to about 1 bar, and ranges between and including
any two of these values. The reaction can be conducted for a period of about 1 min to
about 60 min, about 1 h to about 5 h, about 5 h to about 8 h, about 8 h to about 15 h,
about 15 h to about 25 h, about 25 h to about 40 h, and ranges between and including
any two of these values. In some embodiments, the reaction of dicarboxylic acid or
ester thereof with an alkylene diol is conducted at a temperature of about 240 OC to
about 260 OC and at a pressure of up to about 4 bars for about 2 h to about 3 h.
In some embodiment, the prepolymer used in the process may be prepared by
processes known in the art, such as for example, DMT or PTA route using
PTAlDMT and MEG. It can also be produced using clean PCR (F'ost-consumer
recycled) PET flakes in place of PTAIJIMT and MEG. In some embodiments, batch
or continuous polymerization methods can be used.
The pre-polymer may be added to the polyethylene naphthalate (PEN) or
polyethylene isosorbide terephthalate (PEIT), and modified transparent polybutylene
naphthalate composition at various amounts. In some embodiments, the prepolymer
is added in an amount ranging from about 0.01 % to about 99 % by weight of the
total weight of the sulfonated co-polyester. This includes embodiments in which the ,
amount ranges from about 10 %to about 99 %, from about 20 % to about 95 %, from
about 30% to about 92 %, from about 40% to about 90 %, from about 50 %to about
80 % and from about 60% to about 75 % of the total weight of the co-polyester
composition, and ranges between any two of these values or less than any one of
these values. In some embodiments, the pre-polymer may constitute from about 0.01
wt%, about 10 wt%, about 20 wt%, about 30 wt%, about 40 wt%, about 50 wt%,
about 60 wt%, about 70 wt%, about 80 wt%, about 90.0 wt%, about 95.0 wt%, about
99.0 wt%, and ranges between any two of these values or less than any one of these
values. However, other amounts are possible. The particular amount depends upon
the desired properties of the co-polyester composition. In some embodiments, the
polyethylene naphthalate (PEN) or polyethylene isosorbide terephthalate (PEIT)
includes up to about 10 wt% of the copolyester. In some embodiments, the modified
transparent polybutylene naphthalate includes up to about 30 wt% of the copolyester.
The diols may include suitable diols known in the art. For example, the alkylene diol
may include glycols that have 2 to 20 carbon atoms. The diols may be un-substituted
or substituted; straight chain, branched, cyclic aliphatic diol, aliphatic-aromatic diol,
aromatic diol, or a combination of any two or more thereof. The diol can also be poly
(alkylene ether) glycols with molecular weights between about 250 to about 4,000.
Examples of dihydric alcohols include ethylene glycol, 1,3-propanediol, 1,4-
butanediol, 1,6-hexanediol, and poly (ethylene ether) glycols. The branched diols
include C4-C16 aliphatic branched diols. The branched diol may have 4-12 carbon
atoms. In some embodiments, the branched diol may have 4-10 carbon atoms. In
other embodiments, the branched diol may have 4-8 carbon atoms.
In some embodiments, the alkylene diols include C4-Cs branched aliphatic diols.
Examples of branched diols include, but are not limited to, 2-methyl-1, 3-
propanediol, 2,2-dimethyl-I, 3-propanediol, 2-butyl-2-ethyl-l,3-propanediol,
trimethylpentanediol, and the like. The diol may be a cycloaliphatic diol having
between 6-20 carbon atoms, with the proviso that if a cyclohexane diol is used, it is
included with at least one additional cyclic or branched diol. For example, isosorbide
or a mixture of (cis, trans) 1, 3-cyclohexanedimethanol and (cis, trans) 1, 4
cyclohexanedimethano1 may be used. Examples of aromatic diol may include xylene
glycol, and hydroquinone. In one embodiment the diol may be 1,3-propanediol, 1,4-
butauediol, 1,6-hexanediol, 1,8-octanediol, ],lo-decanediol, 1,12-dodecanediol, 1,14-
tetradecanediol, 1,16-hexadecanediol, dimer diol, 1,4-cyclohexanedimethanol,
di(ethy1ene glycol), tri(ethy1ene glycol), poly(ethylene ether) glycols, poly(buty1ene
ether) glycols, 2-methyl-l,3-propanediol,2, 2-dimethyl-l,3-propanediol,2 -butyl-2-
ethyl-l,3-propanediol, trimethylpentanediol, isosorbide or a mixture of (cis, trans)
1,3-cyclohexanedimethanol and (cis, trans) 1,4 cyclohexanedimethano1, xylene
glycol, or hydroquinone.
The alkylene diol can be a straight chain or a branched diol having 3 to 12 carbon
atoms per molecule. Examples of suitable diols include, but are not limited to,
ethylene glycol, propanediol, butanediol, cyclohexanedimethano1, hexane diol,
octanediol, decanediol, dodecanediol, or a Combination of any two or more thereof.
/
In some embodiments, the alkylene diol is ethylene glycol.
Examples of suitable diols include, but are not limited to, ethylene glycol,
propanediol, butanediol, cyclohexanedimethanoI, hexane diol, octanediol, decanediol,
dodecanediol, or a combination of any two or more thereof.
The modified copolyester may be produced by suitable polymerization techniques
known in the art. For example, the inform polymer mixture may be polymerized
using suitable polycondensation techniques known in the art. In some embodiments,
the modified copolyester is produced by any of the conventional melt or solid state
polycondensation techniques. The melt polycondensation method can be carried out
in either batch, semi-continuous or continuous mode. The method is best carried out
in a reactor equipped with a distillation column and a stirrer or other means for
agitation. The distillation column separates the volatile product of reaction (water
andlor alkanol) from volatile reactants (e.g., ethylene glycol). Use of a distillation
column allows for operation at a lower molar ratio of ethylene glycol to terephthalic
acid, which serves to suppress the formation of DEG. Melt polycondensation can be
carried out in conventional method like PTA, DMT and PCR PET glycolysis. When
terephthalic acid is used in the polymerization method, the volatile reaction product
will be water; when an ester such as dimethyl terephthalate is used, the volatile
reaction product will be the corresponding alkanol (such as methanol), together with
smaller amounts of water. Continuous polymerization method may be used to
prepare polyesters.
In one aspect, the method further includes crystallizing the amorphous granules of
the modified copolyester. Suitable crystallization techniques known in the art may he
used to produce the crystallized modified co-polyester. The crystallization reaction
can be conducted by heating the amorphous copolyester at a suitable temperature for
a suitable period of time. For example, the crystallization can be conducted at a
temperature of about 10 OC to about 300 "C, about 30 "C to about 200 "C, about 50
"C to about 250 O C about 80 "C to about 200 "C and about 100 "C to about 150 "C,
and ranges between and including any two of these values. In some embodiments,
the amorphous copolyester is crystallized at a temperature in the range of about 120
OC to about 140 OC to produce a crystallized modified co-polyester.
The reaction of producing the prepolymer may further include addition of one or
more additives. In some embodiments, the additive is a nucleating agent, branching
agent, chain extender, antioxidant, plasticizers, stabilizing agent, a coloring agent, or
other additives. Additives may also be added before or during or after the
polymerization reaction to impart requisite property to the resulting co-polyester.
Such additives include but are not limited to dyes; pigments; flame retardant additives
such as decabromodiphenyl ether and triarylphosphates, such as triphenylphosphate;
reinforcing agents such as glass fibers; thermal stahilizers; ultraviolet light stahilizers
methoding aids, impact modifiers, flow enhancing additives, ionomers, liquid c~ystal
polymers, fluoropolymers, olefins including cyclic olefins, polyamides and ethylene
vinyl acetate copolymers.
The additives described herein, for example, the plasticizer, anti-oxidizing agent,
stabilizing agent, and end-capped oligomer, if present, can be incorporated for
example, at a concentration of about 0.001 wt%, about 0.01 wt%, about 0.02 wt%,
about 0.05 wt%, about 0.1 wt%, about 0.5 wt%, about 1.0 wt%, about 2 wt%, about 5
wt%, about 10.0 wt%, about 15.0 wt%, about 20.0 wt%, about 30.0 wt%, and ranges
between any two of these values or less than any one of these values. Other
additives, such as for example, nucleating agent and the branching agent, if present,
can be incorporated for example, at a concentration from about 0.1 pprn to about
10,000 ppm, about 2 pprn to about 5000 ppm, about 5 pprn to about 7500 ppm, about
10 pprn to about 2000 ppm, about 20 pprn to about 1000 ppm, or about 50 pprn to
about 500 ppm, and ranges between any two of these values or less than any one of
these values.
Examples of additives include, but are not limited to, a liquid plasticizer, a nucleating
4
agent, a branching agent, an anti-oxidizing agent, a stabilizing agent, and an endcapped
oligomer. In some embodiments, the additive may be a branching agent in an
amount of 10 pprn to 2000 ppm, a nucleating agent in an amount of 10 pprn to 2000
ppm, a liquid plasticizer in an amount of 0.5 to 2 wt%, and at least one anti-oxidizing
agent in an amount ranging from 0.1 to 5 %. Other agents useful for the purpose of
the present disclosure include at least one end-capped oligomer in an amount from 1
to 20 wt%.
The branching agent may be, but is not limited to, 1,2,4-benzenetricarboxylic acid
(trimellitic acid); trimethyl-l,2,4-benzenetricarboxylate; 1,2,4-benzenetricarboxylic
anhydride (trimellitic anhydride); 1,3,5-benzenetricarb~x~laicci d; 1,2,4,5-
benzenetetracarboxylic acid (pyromellitic acid); 1,2,4,5-benzenetetracarboxylic
dianhydride (pyromellitic anhydride); 3,3',4,4'-benzophenonetetracarboxylic
dianhydride; 1,4,5,8-naphthalenetetracarboxylic dianhydride; citric acid;
tetrahydrofuran-2,3,4,5-tetracarboxylica cid; 1,3,5-cyclohexanetricarboxylic acid;
pentaerythritol, 2-(hydroxymethy1)-l,3-propanediol; 2,2-bis(hydroxymethy1)
propionic acid; sorbitol; glycerol; or a combination of any two or more thereof.
Particularly, branching agents may include pentaerythritol, trimellitic acid, trimellitic
anhydride, pyromellitic acid, pyromellitic anhydride and sorbitol.
It is believed that the nucleating agent improves the crystallinity and increases heat
deformation temperature of the polyester product. The nucleating agent can be
organic or inorganic. Examples of inorganic nucleating agent include, but are not
limited to, calcium silicate, nano silica powder, talc, microtalc, aclyn, kaolinite,
montmorillonite, synthetic mica, calcium sulfide, boron nitride, barium sulfate,
aluminum oxide, neodymium oxide, or a metal salt of phenyl phosphonate. The
inorganic nucleating agent can be modified by an organic material to improve its
dispersibility in the polyester product of the present disclosure.
4
Examples of organic nucleating agent include, but are not limited to, carboxylic acid
metal salts such as sodium benzoate, potassium benzoate, lithium benzoate, calcium
benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium
terephthalate, potassium terephthalate, calcium oxalate, sodium laurate, potassium
laurate, sodium myristate, potassium myristate, calcium myristate, sodium
octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium
stearate, calcium stearate, magnesium stearate, barium stearate, sodium montanate,
calcium montanate, sodium toluoylate, sodium salicylate, potassium salicylate, zinc
salicylate, aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium
P-naphthalate and sodium cyclobexane carboxylate; organic sulfonates such as
sodium p-toluene sulfonate and sodium sulfoisophthalate; carboxylic acid amides
such as stearic acid amide, ethylene his-lauric acid amide, palmitic acid amide,
hydroxystearic acid amide, erucic acid amide and tris(t-butylamide) trimesate;
phosphoric compound metal salts such as benzylidene sorbitol and derivatives
thereof, sodium-2,2'-methylenebis(4,6-di-t-butylphenyl)phosphate, and 2,2-
methylbis(4,6-di-t-butylphenyl)sodium, and the like, or a combination of any two or
more thereof.
Examples of liquid plasticizers include, but are not limited to, N-isopropyl benzene
sulfonamide, N-tert-butyl benzene sulfonamide, N-pentyl benzene sulfonamide, Nhexyl
benzene sulfonamide, N-n-octyl benzene sulfonamide, N-methyl-N-butyl
benzene sulfonamide, N-methyl-N-ethyl benzene sulfonamide, N-methyl-N-propyl
benzene sulfonamide, N-ethyl-N-propyl benzene sulfonamide, N-ethyl-pethylbenzenesulfonamide,
N-ethyl-p-(t-buty1)benzene sulfonamide, N-butyl-p-butyl
benzene sulfonamide, N-butyl toluene sulfonamide, N-t-octyl toluene sulfonamide,
N-etbyl-N-2-ethylhexyl toluene sulfonamide, N-ethyl-N-t-octyl toluene sulfonamide
and tri-octyltrimellitate, and the like, or a combination of any two or more thereof.
Examples of anti-oxidizing agent include, but are not limited to, IrganoxB 1010,
1
IrganoxB 1076, IrgafosB 126 and IrgafosB 168. Similarly, copper nitrate(up to 150
ppm) along with potassium iodide, potassium bromides (up to 1000 ppm ), or any
other Light & UV Stabilizers which can be added to enhance weatherability of the
polymers.
Examples of stabilizing agent include, but are not limited to, ostho-phosphoric acid,
trimethylphosphate (TMF'), triphynylphosphate (TPP), or triethylphosphono acetate
(TEPA). In some embodiments, an ortho-phosphoric acid is used as stabilizing agent.
Examples of end-capped oligomers include, but are not limited to, oligomers of
polyethylene terephthalate, polybutylene terephthalate, polytrimethylene
terephthalate, polytrimethylenenaphthalate and polybutylenenaphthalate, and the like,
or a combination of any two or more thereof.
The processes s and products described herein may include other suitable additives
known in the art such as, but not limited to, pigments, flame retardant additives such
as decabromodiphenyl ether and triarylphosphates, such as triphenylphosphate,
reinforcing agents such as glass fibers, thermal stabilizers, ultraviolet light stabilizers
methoding aids, impact modifiers, flow enhancing additives, ionomers, liquid crystal
polymers, fluoropolymers, olefins including cyclic olefins, polyamides, and ethylene
vinyl acetate copolymers.
In one embodiment, the processes also include subjecting the crystallized modified
copolyester to solid state polymerization conditions. Such action increases the
molecular weight and the intrinsic viscosity of the co-polymer. The solid state
. polymerization is conducted under a vacuum or in the presence of a stream of an inert
gas. Suitable inert gases include, but are not limited to, nitrogen, carbon dioxide,
helium, argon, neon, krypton, xenon, and the like. Suitable solid state polymerization
4
temperatures can range from a temperature at or above the polymerization reaction
temperature up to a temperature below their melting point. For example, the solid
state polymerization reaction can be conducted at a temperature of about 400 "C or
below, about 300 "C or below, about 200 "C or below, about 100 "C or below, at
about 80 "C or below, at about 50 O C or below, at about 45 "C or below, at about 40
"C or below, at about 35 "C or below, at about 30 "C or below, at about 25 "C or
below or at about 20 "C or below, and ranges between and including any two of these
values. In some embodiments, the solid state polymerization is conducted at a
temperature of about 50 "C to about 400 OC, about 80 "C to about 350 OC, about 100
"C to about 300 OC, about 150 "C to about 250 "C, about 180 "C to about 200 "C, and
ranges between and including any two of these values. The copolyester can be solid
state polymerized for a time sufficient to increase its molecular weight or IV to the
desired value. For example, the solid state polymerization reaction can be conducted
for a period of about 1 min to about 60 min, about 1 h to about 5 h, about 5 h to about
8 h, about 8 h to about 15 h, about 15 h to about 25 h, about 25 h to about 40 h, and
ranges between and including any two of these values.
In one embodiment, the crystallized modified copolyester is subjected to solid state
polymerization by placing the pelletized or pulverized polymer into a tumble drier of
an inert gas, such as nitrogen, or under a vacuum of 1 ton; at an elevated temperature,
above 150 "C but below the melting temperature, for a period of about 4 to about 16
hours. In some embodiments, the solid state polymerization is carried out at a
temperature of about 180°C to about 200 "C which results in an increase in inherent
viscosity to more than 0.5 dug.
The prepolymer can be prepared by treating equal molar proportions of dicarboxylic
acid residues (100 mole %) and diol residues (100 mole %) to form repeating units
(100 mole %).
In one aspect, provided are a modified PETcopolyester and products thereof, wherein
the copolyester includes: at least one terephthalatepolyester composition; and a
modified transparent polybutylene naphthalate, wherein the modified polybutylene
naphthalate comprises naphthalene dicarboxylic acid, 1,4-butane diol, and isophthalic
acid or monoethylene glycol or diethylene glycol or cyclohexane dimethanol or
polyetl~ylenen aphthalate, at least one nucleating agent, and a modified nanoclay.
In one aspect, provided are modified PET copolyesters which can be used in beverage
or food packaging applications. The modified PET copolyester includes at least one
terephthalate polyester composition; and a modified transparent polybutylene
naphtbalate.The products made by use of polyester terephthalate composition and
modified polybutylene naphthalate (transparent PBN) have comparatively longer
shelf lifetgood barrier properties, while achieving the superior light transmittance
and enhanced thermal and mechanical properties of the products.
A copolyester having intrinsic viscosity greater than 0.50 dL/gm, for manufacture of
containers that can withstand an ambient temperature of about 70 C, comprises: at
least one terephthalate polyester composition; and a modified transparent
polybutylene naphthalate, wherein the modified polybutylene naphthalate comprises
naphthalene dicarboxylic acid, 1,4-butane diol, and isophthalic acid or monoethylene
glycol or diethylene glycol or cyclohexane dimethanol or polyethylene naphthalate, at
least one nucleating agent, and a modified nanoclay.
The copolyester used in the process are at least one selected from the group
consisting of polybutylene naphthalate (also known as modified PBN "MPBN),
polyethylene naphthalate (PEN), polyethylene isosorbide terephthalate (PEIT) and
the comonomers used in the process are at least one selected from the group of
isophthalaic acid, isosorbide, diethylene glycol (DEG), monoethylene glycol (MEG),
cyclohexane dimethanol (CHDM) and the like.
The present invention provides a process to prepare the copolyester comprising:
recycling RPET flakes by its glycolysis to yield PET; and further adding isophthalic
acid, polyethylene naphthalate and polybutylene naphthalate with or without its
modification.
The copolyester used in the process of the present disclosure comprises dicarboxylic
acid, diol at least one additional comonomer, polymer catalysts and at least one
agent. The co-monomer preferably is isophthalic acid.
In an embodiment, the copolyester used in the process can alternatively be obtained
by mechanical or chemical recycling of WET flakes or by employing ester
interchange between DMT, MEG and DMlP and subsequent polymerization.
The present invention provides a modified copolyester that can be used in packaging
applications. More specifically, the present invention provides the modified
copolyester that can be used in packaging to produce clear container. A packaging
container, a packaging material or a preform prepared from the polyethylene
terphthalate polyester provides improved barrier properties, thermal, mechanical and
optical properties.The modified copolyester of the present disclosure comprises a
copolyester, a naphthalate polyester, polybutylene naphthalate with or without its
modification and at least one agent.
In an embodiment of the present invention, the modified polyethylene terphthalate
(PET) copolyester,can be prepared by reacting polyethylene terphthalate (PET) with
polyethylene naphthalate (PEN), PBN and modified polybutylene naphthalate
(transparent PBN).
In an embodiment of the present invention, the modified polyethylene terphthalate
(PET) copolyester can be prepared by reacting polyethylene terphthalate (PET) with
polyethylene naphthalate (PEN), isosorbide, polybutylene naphthalate, and modified
polybutylene naphthalate (transparent PBN).
In an embodiment of the present invention, the modified polyethylene terphthalate
(PET) copolyester can be prepared by reacting polyethylene terphthalate (PET) with
isosorbide, polybutylene naphthalate, and modified polybutylene naphthalate
(transparent PBN).
In an embodiment of the present invention, the modified polyethylene terphthalate
(PET) can be prepared by esterification and subsequent polymerization of
terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid or 2,6-dimethyl
carboxylate, monoethylene glycol, butane diol, and at least crystallization suppressing
agent agent in presence of polymer catalysts. The Esterification is carried out at
temperature from 150 to 265 "C and the polymerization is carried out at temperature
range from 250 to 290 OC.
In an embodiment, the copolyester is prepared by addition of polyethylene
naphthalate (PEN) and polybutylene naphthalate (PBN) with or without its
modification during the process of manufacturing of polyethylene terphthalate.
In one embodiment, the modified polybutylene naphthalate can alternately be blended
with the copolyester after the polycondensation reaction to obtain the modified
copolyester and products thereof.
In one aspect of the disclosure, the present invention relates to products comprising
the modified copolyester, modified or unmodified polybutylene naphthalate and at
least one essential additive.
The copolyester used in the process of the present invention is obtained from the
polymerization reaction of at least one aromatic dicarboxylic acid or ester thereof and
alkylene glycol and further addition of at least one comonomer selected from the
group of isophthalaic acid, isosorbide, polyethylene naphthalate at various stages of
polymerization reaction. For example the the comonomer can be added before or
after the esterification or polycondensation reaction.
In an embodiment, the polyester used in the process of the present invention can be
obtained by recycling of WET flakes. The recycling of WET is done either by
mechanical or chemical methods. The mechanical recyclingcomprising the steps of
washing RPET flakes; melting the flakes; and extruding the molten PET to
amorphous state. The amorphous PET is further solid state polymerized to achieve
the crystalline PET.
Alternatively, hydrolysis or methanolysis or glycolysis of RPET flakes yields
monomers of polyester used in the process of the present disclosure e.g. terephthalic
acid or dimethyl terphthalate or BHET or DGT and monoethylene glycol or water.
The modified polybutylene naphthalate (MF'BN) is obtained from the esterification of
naphthalene dicarboxylic acid or 2,6-dimethyl naphthalene dicarboxylate and 1,4-
butane diol; and subsequent polymerization of the prepolymer obtained from the
esterification in presence of at least one comonomer selected from the group
consisting of alkylene diol, cyclic diol, aliphatic or aromatic acid or polyester. The
comonomer used in the process controls the required rate of crystallization of
polybutylene naphthalate, thus the comonomer acts as a crystallization suppressing or
retarding agent or quenching agent during thermal crystallization while cooling from
the melt phase and results in clear polybutylene naphthalate.
The alkylene diol used as co-monomer to prepare clear PBN is selected from the
group consisting of monoethylene glycol, diethylene glycol, propanediol, butanediol,
hexane diol and the like.
The cyclic diol used as comonomer to prepare clear PBN is selected from the group
4
consisting of cyclohexanedimethanol, and the like.
The carboxylic acid used as comonomer to prepare clear PBN is selected from the
group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid,
pimelic acid, suberic caid, azelaic acid, sebacic acid, brassidic caid, thapsic acid,
maleic acid, fumaric acid, glutaconic acid, alpha-hydromuconic acid, betahydromuconic
acid, alpha-butyl, alpha-ethylglutaric acid, alpha-beta-diethyl succinic
acid, isophthalic acid, terephthalic acid, hemimellitic acid and 1, 4-
cyclohexanedicarboxylic acids.
The polyester used as comonomer to prepare clear PBN is selected from the group
consisting of polyethylene terphthalate, polyethylene terphthalate glycol modified
(PET-G), polyethylene naphthalene.
Additives may also be added before or during or after the polymerization reaction to
impart requisite property to the resulting polyester. Such additives include but are not
limited to pigments; thermal stabilizers; ultraviolet light stabilizers processing aids
and impact modifiers.
Examples of agents useful for the purpose of the invention are described herein
before.
The disclosure of the present invention relates to products made of the modified
modified copolyester , thaproduct comprising:modified polybutylene naphthalate in
4 an amount of 5 to 30 wt% and polyethylene terphthalate or polyethylene terphthalate
naphthalate in a an amount of 70 to 95 wt%; at least one agent selected from the
group consisting of liquid plasticizer; at least one nucleating agent; at least one
branching agent; at least one anti-oxidizing agent; at least one stabilizing agent; at
least one additive and optionally, at least one end capped oligomer.
In an embodiment, the products of the present invention can directly be manufactured
by moulding the melt comprising polyethylene terphthalate (PET), polyethylene
naphthalate (PEN) and polybutylene naphthalate (PBN) with or without its
modification.
In an embodiment, polyethylene terphthalate (PET), polyethylene naphthalate (PEN)
and polybutylene naphthalate (PBN) are directly melt blended while moulding.
In an embodiment, polyethylene terphthalate PET), polyethylene naphthalate (PEN)
and polybutylene naphthalate (PBN) are first melt blended and then extruded to
collect amorphous chips, the amorphous chips are further solid state crystallized to
crystalline modified polyethylene terphthalate.
The modified copolyester obtained in accordance with the process of the present
disclosure can be used in packaging applications such as preparing transparent
containers, beer keg or products thereof.
4
I
The material or container obtained from the modified copolyester of the present
disclosure has comparatively improved thermal, mechanical and optical ind barrier
properties. More specifically the products have lower oxygen transfer rate (oxygen
ingress), Carbon dioxide transfer rate, water vapor transfer rate and inert gas transfer
rate while achieving better transparency and good thermal and mechanical properties.
The modified copolyester is extruded and granulated using underwater cutter to
obtain chips which are transparent with better barrier properties. The chips are dried
and then injection molded to preform by processing at temperatureabove its melting
point. The preforms are further processed in to container by TBM (Injection Blow
Moulding); ISBM (Injection Stretch Blow Moulding) including other methods. These
containers are transparent and can be monolayer or multilayer.
The present invention also provides a packaging product comprising a modified
copolyester product of the present disclosure. The packaging product can be a
preform or a packaging material or a packaging container.
The modified copolyester produced in accordance with the present disclosure imparts
improved barrier properties and transparency (haze value below 5 NTU) due to
presence of polybutylene naphthalate. The modified copolyester prepared in
accordance with the present disclosure can be used to manufacture monolayer or
multilayer containers by normal ISBM, IBM, IM, EBM processes,with or without
heat set blow molding process for applications in various beverages, sport drinks,
sauces, jams etc.
The modified copolyester of the present invention is used for making transparent
packaging containers and products thereof with improved shelf 1ife.The modified
copolyester of the present disclosure can be used for making the transparent beer keg.
The modified copolyester of the present invention is further described in light of the
following examples which are set forth for illustration purpose only and not to be
construed for limiting the scope of the disclosure.
QUALITY PARAMETERS AND ANALYTICAL METHODS:
The modified copolyester of the present disclosure exhibits one or more properties of
intrinsic viscosity greater than 0.5 at 25 OC, color L* ranges fiom 50 to 62 %; color
b* ranges from -3.0 to 10; diethylene content of less than 1.4 %;glass transition
temperature in the range of 74 to 90°C and others such properties. These properties
are used as quality parameters of the final finished product. The quality parameters of
the modified copolyester in accordance to the present disclosure, has been measured
by various well known analytical methods. Such analytical methods which have been
used for the measurement of the physical parameters of the polyester of the present
disclosure are: Billmeyer equation used for measuring the intrinsic viscosity;
HunterLabColorFlex Model No 4510, serial No. CX 0969for knowing the value of
color indicators such as L*, a* and b*; Haze Gard Plus (BYK Gardner) is used to
know haze value as % haze per mm of sample thickness;Gas Chromatography (GC)
to determine the DEG content of the polymer;DSC analysis to monitor thermal
properties of all polymers samples at heating and cooling rates of 10°C per minute.
DSC is used to know glass transition temperatures (Tg), crystallization exotherm
peak temperatures and heats of crystallization (AH), as well as peak endotherm
4
temperatures and heats of fusion for all materials. 1
EXAMPLES:
The following non-limiting examples are intended to illustrate, but not to limit, the
scope of the present invention.
Example 1: Preparation of modified polyethylene terphthalate by incorporation
of the modified polybutylene naphthalate at the end of Esterification in presence
of isosorbide
57.96 kg of pure terephthalic acid and 25.74 kg of monoethylene glycol are taken in
an esterification reactor, in 1:1.16 molar ratio. To this, sodium acetate 50 ppm (4 g) is
added after charging PTA slurry and 2.00 kg of isosorbide is added to the reactor
after charging sodium acetate and 2.80 kg of isophthalaic acid is further added after
charging the isosorbide. Polymerization catalyst antimony trioxide 200 pprn as Sb
(19.13 g), germanium oxide 20 ppm as Ge (2.31 g), colorants cobalt acetate 30 ppm
as Co (10.14 g), blue toner 0.3 pprn (0.16 g) are added to the above mixture. The
esterification reaction is carried out at 150 - 265 "C temperature for three to four
hours. At the end of esterification reaction 14.37 gm (50 ppm) ortho phosphoric acid
is further mixed in the reactor. The esterified pre-polymer is then transferred to the
polycondensation reactor.
The polymerization is conducted at a temperature of 250 -290 "C under 760 to 1 ton
for two to three hours. At the end of esterification, 8.00 kg of modified polybutylene
naphthalate (10%) is added to the polycondensation reactor and the mixture is hold
up for 20 minutes. After the required torque is reached, the molten amorphous
polymer is extruded under nitrogen pressure and collected as pellets. The resulting
amorphous polymer with I.V. - 0.6 dL/g is hrther solid state polymerized to achieve
the crystallized polymer. The solidified polymer so obtained is made into a preform
by injection molding and analyzed for their characteristics. Subsequently the quality
parameters were measured for amorphous and SSP crystalline copolyester, and the
corresponding results are produced herein the Table 1.
Example 2: Preparation of modified polyethylene terphthalate by incorporation
ofthe modified polybutylene naphthalate at the end of Esterification in presence
of PEN chips
59.5 kg of pure terephthalic acid and 25.8 kg of monoethylene glycol are taken in an
esterification reactor , in 1:1.16 molar ratio. To this, sodium acetate 75 pprn (6 g) is
added after charging PTA slurry, nanoclay (I%), and 2.00 kg of isophthalaic acid is
added after charging sodium acetate. Polymerization catalyst antimony trioxide 200
ppm as Sb (19.13 g), germanium oxide 20 ppm as Ge (2.31 g), colorants cobalt
acetate 35 ppm as Co (11.82 g), blue toner 0.3 ppm (0.024 g) and 3.20 kg (4%) of
polyethylene naphthalate chips are as such added to the above mixture. The
esterification reaction is carried out at 150 - 265 OC temperature for three to four
hours. At the end of esterification reaction 14.37 gm (10%) ortho-phosphoric acid is
further mixed in the vessel. The esterified pre-polymer is then transferred to the
polycondensation reactor.
At the end of esterification, 8.00 kg of modified polybutylene naphthalate is added to
the polycondensation reactor. The polymerization is conducted at a temperature of
250 -290 'C under 760 to ltorr for two to three hours. After the required torque is
reached, the molten amorphous polymer is extruded under nitrogen pressure and
collected as pellets. The resulting amorphous polymer with I.V. - 0.6 dL/g is further
solid state polymerized to achieve the crystallized polymer. The solidified polymer so
obtained is made into a preform by injection molding and analyzed for their
characteristics.
Subsequently the quality parameters were measured for amorphous and SSP
crystalline copolyester, and the corresponding results are produced herein the Table
1.
Example 3: Preparation of modified polyethylene terphthalate by incorporation
of the modified polybutylene naphthalate at the end of polycondensation in
presence of isosorbide
In this example, all procedural steps and the quantity of the chemical used for the
process remained same as were used in Example 1 explained above. The modified
polybutylene naphthalate (MPBN) however were added to the reactor at the end of
the polycondensation reaction. Subsequently the quality parameters were measured
for amorphous and SSP crystalline copolyester, and the corresponding results are
produced herein the Table 1.
Example 4: Preparation of modified polyethylene terphthalate by incorporation
of the modified polybutylene naphthalate at the end of polyeondensation in
presence of PEN chips
In this example, all procedural steps and the quantity of the chemical used for the
process remained same as were used in Example 2 explained above. The modified
polybutylene naphthalate (MPBN) however were added to the reactor at the end of
the polycondensation reaction. Subsequently the quality parameters were measured
for amorphous and SSP crystalline copolyester, and the corresponding results are
produced herein the Table 1.
Table 1: Quality Parameters of the Modified Copolyester
I I I MPBN Added at the End of EI I MPBN Added at the End of PC

Example 5: Incorporation of modified polybutylene naphthalate (MPBN) into
COPET by direct blending in extruder
The copolyester of polyethylene naphthalate (PET) were separately prepared in
accordance to the Example 1 and 2. Thereafter, the copolyester so obtained from the
Example 1 and 2 were directly blended with modified polybutylene naphthalate
(MPBN) in extruder separately and two samples were prepared separately. The
extruded polymer so obtained were further quenched to get amorphous chips and
further soli state polymerized to get the crystalline chips. The samples were further
analyzed for their characteristics provided in Table 2 below.
Flexural
Strength
Impact
(Notch)
Impact (Unnotch)
MFI at 280
Kflcm2
J/M
%
gms/lOmin
840.3
55.8
lOO%NB
19.6
862
56.7
100 % NB
18.6
844.2
58.2
100 %NB
20.1
851.79
59
lOO%NB
19.3
Table 2: Quality Parameters of the Modified Copolyester Obtained by Direct
Blending of MPBN
Example 5: Direct Blended of MPBN in Extruder
or Clear PBN
Tchl
Tml
Tg2
Tch2
Tm2
% of
crystallinity
SSP sample Analysis
"C
OC
O C
"C
OC
Tg 2
Tch 2
Tm 2
Tensile
Strength
%
I I I I
152.8
240.7
80.7
154.2
240.0
OC
OC
U~
KgUcm2
Elongation
Tensile
Modulus
38.8
I I I I
156.9
242.8
80.3
159.2
241.3
81.0
169.3
238.9
586.77
%
G P ~
Flexural I KgfIcm2 I 828.33
101.7
201.5
84.1
101.1
198.1
33.8 ---
81.3
167.5
240.5
599.19
110.33
1.72
890.52
83.9
101.6
197.9
542.67
813.16
330.25
1.97
20.88
1.69
The above examples are one of such methods by which modified
polyethyleneterphthalate can be prepared. The objectives of the invention can be
achieved by use of at least one selected from the group consisting clear PBN,
polyethylene naphthalate, isophthalaic acid, isosorbide and the like.
Strength
-
Impact (Notch)
Impact (Unnotch)
MFI at 280
Different samples of the modified polybutylene copolyester were synthesized by
using the similar procedure disposed above in Examples 1 to 5 by using formulation
mentioned in the table 1. Raw material quantities mentioned in the said table is in
4
weight percentage with respect to the pblymer. The melting, crystallization and the
glass transition temperatures of the polyester were measures using DSC and other
testing equipments.
Example 6: Manufacture of thin walled containers by IM
JIM
%
gms/lOmin
The resin from Example 1 to 2 was used on IM machine to manufacture containers.
Prior to that the chips were dried at 160°C for 7 hours. The mold was cooled with
chilled water at f 6OC. The melt flow was satisfactory. The containers of 350p wall
thickness were manufactured. The containers were of good color &transparency and
could be filled at 82OC temperature.
Example 7: Manufacture of 20 liter container by 2 Stage ISBM
53.75
100 %NB
18.3
58.56
lOO%NB
20.2
21.25
57%NB
79.5
The copolyester from Example 1 to 2 was used to manufacture 20 liter water
container. The chips were dried at 170°C temperature for 6 hours. On a single caring
injection molding machine the perform were made. The extruder temperatures were
+
in the range 275-285'C.The preforms were subsequently blow at 30 bar pressure after
heating at 120°C on single caring blowing machines. The 20 liter containers
manufactured could be washed at 72 "C.
The embodiments herein and the various features and advantageous details thereof
are explained with reference to the non-limiting embodiments in the description.
Descriptions of well-known components and processing techniques are omitted so as
to not unnecessarily obscure the embodiments herein. The examples used herein are
intended merely to facilitate an understanding of ways in which the embodiments
herein may be practiced and to further enable those of skill in the art to practice the
1
embodiments herein. Accordingly, the examples should not be construed as limiting
the scope of the embodiments herein.
The foregoing description of the specific embodiments will so fully reveal the general
nature of the embodiments herein that others can, by applying current knowledge,
readily modify andlor adapt for various applications such specific embodiments
without departing from the generic concept, and, therefore, such adaptations and
modifications should and are intended to be comprehended within the meaning and
range of equivalents of the disclosed embodiments. It is to be understood that the
phraseology or terminology employed herein is for the purpose of description and not
of limitation. Therefore, while the embodiments herein have been described in terms
of preferred embodiments, those skilled in the art will recognize that the
embodiments herein can be practiced with modification within the spirit and scope of
the embodiments as described herein.
The use of the expression "at least" or "at least one" suggests the use of one or more
elements or ingredients or quantities, as the use may be in the embodiment of the
disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles and the like that has
been included in this specification is solely for the purpose of providing a context for
the disclosure. It is not to be taken as an admission that any or all of these matters
form a part of the prior art base or were common general knowledge in the field
relevant to the disclosure as it existed anywhere before the priority date of this
application.
1
1
While considerable emphasis has been placed herein on the particular features of this
disclosure, it will be appreciated that various modifications can be made, and that
many changes can be made in the preferred embodiments without departing fkom the
principles of the disclosure. These and other modifications in the nature of the
disclosure or the preferred embodiments will be apparent to those skilled in the art
from the disclosure herein, whereby it is to be distinctly understood that the foregoing
descriptive matter is to be interpreted merely as illustrative of the disclosure and not
as a limitation.

We Claim:
1. A copolyester having intrinsic viscosity greater than 0.50 dLIgm, comprises:
terephthalate polyester composition; and
a modified transparent polybutylene naphthalate, wherein the modified
polybutylene naphthalate comprises naphthalene dicarboxylic acid, 1,4-butane
diol, and isophthalic acid or monoethylene glycol or diethylene glycol or
cyclohexane dimethanol or polyethylene naphthalate, nucleating agent, and a
modified nanoclay.
2. The copolyester as claimed in claim 1 wherein said terephthalate polyester
composition comprises of polyethylene terphthalate (PET), and polyethylene
naphthalate (PEN) or polyethylene isosorbide terephthalate (PEIT), or combination
thereof.
3. The copolyester as claimed in claim 2 wherein said polyethylene naphthalate (PEN) is
in an amount up to 10 wt. % based on total weight of the copolyester and
polyethylene isosorbide terephthalate (P~ITi)s in an amount up to 10 wt.% based on
total weight of the polyester.
4. The copolyester as claimed in claim 1, wherein said copolyester is modified
polyethylene terphthalate polyester having improved thermal, mechanical, optical,
banier properties, and excellent transparency.
5. A process of preparing a copolyester having intrinsic viscosity greater than 0.50
dLIgm, for manufacture of containers that can withstand an ambient temperature of
about 70 C, comprising:
- reacting terephthalic acid or ester thereof with monoethylene glycol and other
diols, monomers, a nucleating agent, and a modified nanoclay at temperature
about 150 OC to 270 O C in presence of catalysts under atmospheric pressure to
obtain pre-polymers;
- mixing polyethylene naphthalate and modified transparent polybutylene
naphthalate in the melt to obtain uniform reaction mixture consisting of said
prepolymer;
- polymerizing said reaction mixture at temperature at about 270°C and 295°C
under pressure below 1 mili bar to obtain melt polymer of the required degree
of polymerization;
- extruding the melt polymer to obtain amorphous granules of intrinsic
viscosity >0.40 dLIgm followed by crystallization thereof under atmospheric
pressure and temperature at about 120°C and 140°C; and
- solid state polymerizing the crystalized polymer to upgrade the intrinsic
viscosity to above 0.50 dWgm.
6. The process as claimed in claim 6, wherein the pre-poly4 mers are obtained in
esterification reaction carried out at temperature about 220°C and 270°C, and ester
interchange reaction carried out at temperature about 150 "C to 200 OC.
7. The process as claimed in claim 6, wherein the modified polybutylene naphthalate is
in an amount of up to 30 wt. % based on total weight of the copolyester.
8. The process as claimed in claim 6, wherein the nanoclay is selected from the group
consisting of calcium silicate, nano silica powder, talc, microtalc, aclyn, kaolinite,
montmorillonite, synthetic mica, calcium sulfide, boron nitride, barium sulfate,
aluminum oxide, neodymium oxide and a metal salt of phenyl phosphonate.
9. The process as claimed in claim 6, wherein the modified transparent polybutylene
naphthalate comprises naphthalene dicarboxylic acid, 1,4 butane diol, and isophthalic
acid or monoethylene glycol or diethylene glycol or cyclohexane dimethanol or
polyethylene naphthalate, and at least one nucleating agent and modified clay.
10. The process as claimed in claim 6, wherein solid state polymerization ryaction is
carried out in batch SSP unit under pressure below 2 mili bar, or in continuation SSP
in presence of nitrogen gas.
11. The copolyester as claimed in any of the preceding claim as and when used in
injection blow moulding, injection moulding, injection stretched blow moulding, dish
washable containers, aerosol containers, xtrusion blow moulding to manufacture
containers for applications in beer packaging, and other beverages, and containers
capable of undergoing process pasteurization process for packaging food items as
we11 as no food products, or a preform capable of withstanding high temperature up to
: I . .
75 OC without undergoing any visual deformation and shrinkage beyond acceptable
limit which is 2.5%, preferably 1.5%.