FIELD OF THE INVENTION:
The present invention generally relates to polyester products and improved
performance thereof. More particularly, the present invention relates to a process for
the preparation of copolymers of polybutylene naphthalate and products thereof for
use in applications wherein improved thermal, mechanical, barrier and optical
properties are achieved.
BACKGROUND OF THE INVENTION:
Polybutylene Naphthalate (PBN) is a polyester of the naphthalate polyester family. It
has excellent wear resistance, sliding characteristics, hydrolysis resistance, and
chemical resistance. Compared to its analogous polyester, it has superior gas barrier
properties, excellent chemical and hydrolysis resistance, excellent sliding
performance, high deflection temperature under load and faster crystallization
making it superior over other polyesters such as polybutylene terphthalate,
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polyethylene naphthalate, polyethylene terphthalate, and Aolyethylene terephthalate
glycol-modified VET-G).
PBN polyester has been used in a variety of applications because Qf its better wear
properties than Polyphenylene Sulfide (PPS) and polyacetal in addition to excellent
chemical resistance, superior barrier properties, and superior sliding characteristics.
When meshing of gears made from the same material is undesirable, PBN is used and
its current commercial application include components in gear-change levers. Due to
its superior gas-barrier properties. It is utilized as backsheet material for solar battery
chargers where a service life of less than 10 years would be anticipated and the
charger would typically be used indoors. Backsheets are normally comprised of
multilayer structures. PBN can further be used to make fuel tanks, hose and fuel
transporters.
The applications of PBN in packaging are very limited so far because of its fast
crystallization characteristic that results in opaque container, but at the same time its
superior gas barrier properties makes it one of the most preferable polyester for
containers, hoses, fuel storage and transporter.
Amorphous polymer can be crystallized by thermal crystallization while cooling from
the melt and heating solidified polymer above ambient temperature, and mechanical
stretching (Strain induced crystallization). Crystallization affects optical, mechanical,
thermal and chemical properties of polymers depending upon the size of crystals. The
degree of crystallinity is estimated by different analytical methods and it typically
ranges between 10% and 80%, thus crystallized polymers are often called
"semicrystalline" materials.
The properties of semicrystalline polyesters are determined not only by the degree of
4
crystallinity, but also by the size and orientation of the molecular chains. i
It is therefore desirable to achieve the proper crystallization of polybutylene
naphthalate polyester to improve their optical, barrier, mechaniqal, and thermal
properties. Semicrystalline polymers usually appear opaque because of light
scattering on the numerous boundaries between the crystalline and amorphous
regions. The rate of crystallization is estimated by the half time crystallization
method. The half time crystallization (T112) is the half time required to achieve the
crystallization of melt polymer while stretching or heating. The more value of the Tin
means slow rate of crystallizationand vice-versa. TIi2 for polyethylene terephthalate
(PET) is 18 seconds, for polyethylene naphthalate (PEN) is 11 5 seconds, for PBT is 3
seconds and for PBN is 1 second. Thus, due to fastest rate of crystallization,
polybutylene naphthalate (PBN) is always found opaque in appearance which makes
it undesirable for use in manufacturing transparent containers.
It is desirable to design and produce a modified polybutylene naphthalate polyester
by controlling its crystal size and rate of crystallization , as the controlled
crystallization of polybutylene naphthalate further enhances its transparency.
There has been a disclosure of the process of suppressing the crystallization rate of
polybutylene naphthalate. Reference is made to US patent 6,451,966 wherein a
process to suppress the rate of crystallization of polyesters such as PET, PBT, PEN,
PBN in Solid State Polymerization (SSP) is disclosed. In this process, the
incorporation of low concentration of isophthalaic acid and ethylene glycol has been
disclosed to suppress the rate of crystallization during SSP process so as to achieve
better SSP rate. The patent '966' does not disclose any increase in crystallinity and
transparency of polybutylene naphthalate and limits its effect to transparency of
product made of polybutylene naphthalate polyester. It does not provide solution of
removing haziness in container made of polybutylene naphthalate copolymer.
Reference may be made to US Patent 5,612,423. which suggest a process to prepare
crystallizable copolymers such as PET, PBN, with high molecular yeights and high
melting points. Here, the Solid State Polymerization (SSP) is continued until the
Intrinsic Viscosity (I.V.) of the polymer reaches any desired level. Thus, the claimed
process controls the rate of crystallization on the basis of I.V. characteristics. Further,
it does not disclose the use of isophthalaic acid, monoethylene glycol or diethylene
glycol or cyclohexanedimethano1 (CHDM) as comonomer. The said process,
however, does not teach about the transparency and improved barrier properties of
the final product. In said patent, there is no reference of transparency and barrier
properties of polybutylene naphthalate while making container.
However, there are not many reports which specifically described a modified
polybutylene naphthalate. Hence, there is an urgent need to produce modified
polybutylene naphthalate polyester with enhanced transparency and improved
properties. The present invention overcomes the problem of loss of transparency in
polybutylene naphthalate due to its fast crystallization of polybutylene naphthalate by
achieving the proper crystallization of polybutylene naphthalate.
The crystallization rate and growth of crystal size is controlled by slightly retarding
the rate of crystallization. The slight retardation in the rate of crystallization promotes
the requisite growth of nucleation thereby limiting the size of the crystallites and
ensures transparency along with increase crystallinity making themusable in
packaging application for transparent containers in both monolayer as well as
multilayer containers.
OBJECT OF THE INVENTION:
An object of the present invention is to modify polybutylene naphthalate polyester for
achieving excellent transparency, high barrier properties and use thereof in
manufacturing containers.
Yet, another object of the present invention is to provide transparent polybutylene
naphthalate polyester having excellent chemical resistance, excellent hydrolysis
resistance, excellent sliding performance, high deflection temperature under load and
fast but controlled crystallization.
Further, the object of the present invention is to provide a process for preparing
transparent polybutylene naphthalate polyester with improved optical properties, such
as high clarity and excellent transparency.
Still further, the object of the present invention is to provide packaging containers
made of polyester and capable of withstandig high temperature without undergoing
any deformation and shrinkage and has improved shelf life due to its superior harrier
properties.
Another object of the present invention is to provide a process for preparing
transparent containers comprising modified polybutylene naphthalate (clear or
transparent polybutylene naphthalate (PBN)) having superior barriers properties.
Further, the object of the present invention is to prepare containers using copolymers
of polybutylene naphthalate 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
polybutylene naphthalate. I
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 relates to products made of the modified polybutylene
naphthalate polyester, comprising: at least one naphthalate dicarboxylic acid or ester
thereof; butane diol; at least one comonomer selected from the group of alkylene diol,
cyclic diol aliphatic acid, aromatic acid, polyester in an amount of 1 to 20 wt%.; at
least one agent selected from the group consisting of liquid plasticizer in an amount
of 0.5 to 2 &%; at least one nucleating agent in an amount of 10 ppm to 2000 ppm; at
least one branching agent in an amount of 10 ppm to2000 ppm; at least one antioxidizing
agent in an amount ranging from 0.1 to 5 &%; at least one stabilizing
agent; at least one additive and optionally, at least one end capped oligomer in an
amount of 1 to 20 &%, wherein, said poiybutylene naphthalate polyester is
characterized, wherein said polyester exhibits one or more properties as follows:
color L* range is greater than 50 (>50); color b* ranges from 1 to 15; monoethylene
content of less than 10%; glass transition temperature in the range of 60 OC to 85 OC;
and haze value < 7 NTU.
In one embodiment, the present invention relates to a transparent polybutylene
naphthalate polyester for use in monolayer and multilayer container manufacturing,
the polyester product exhibiting at least one of: a polyethylene terephthalate
equivalent internal viscosity of > 0.50 dLIg; an oligomer content of less than 1.5
wt%.; a diethylene content of less than 10 wt%; a carboxylic end groups of less than
100 meqlkg; haze value < 7 NTU, wherein said polybutylene naphthalate polyester is
used to improve the barrier performance and maintain transparency;of polyethylene
terephthalate polyester and products made thereof.
In accordance to one embodiment, the present invention relates to a process for
preparing transparent polybutylene naphthalate polyester, for improving barrier
performance of polyesters used in making of monolayer or multilayer containers,
comprising steps of: mixing butane diol with polymerization catalysts, monoethylene
glycol, color toner, and at least one crystallization suppressing agent in an amount
ranging from 1 to 20 wt.% based on total weight of the polyester, wherein said
crystallization suppressing agent controls the rate of crystallization so as to control
size and shape of crystals to ensure transparency; reacting said mixture with
naphthalene dicarboxylic acid or ester thereof to obtain oligomerized product via
esterification or ester interchange; polymerizing said oligomer using at least one
polymerization catalyst to obtain amorphous polybutylene naphthalate polyester
chips; crystallizing said polybutylene naphthalate polyester chips; and subjecting said
polyester chips to solid state polymerization to upgrade the intrinsic viscosity (I.V.)
up to more than 0.40 dVgm.
In an embodiment of the present invention, the comonomer (hereinafter known as
"crystallization suppressing agent" or "crystallization control agent") used for
suppressing the rate of crystallization, is at least one selected from the group of
alkylene diol, cyclic diol, aliphatic or aromatic acid or polyester or combination
thereof. 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.
In yet another embodiment of the present invention, the alkylene diol used as
crystallization suppressing agent is selected from the group consisting of
monoethylene glycol, diethylene glycol, propanediol, butanediol, hexane diol, and the
like.
In yet another embodiment of the present invention, the cyclic diol used as
crystallization suppressing agent is selected from the group consisting of
cyclohexane dimethanol, and the like.
The carboxylic acid used as crystallization suppressing agent 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, fiunaric 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 aromatic acid used as crystallization suppressing agent is an isophthalic acid.
The polyester used as crystallization suppressing agent is selected from the group
consisting of polyethylene terphthalate (PET), polyethylene terphthalate glycolmodified
(PET-G), polyethylene naphthalene (PEN).
(The polybutylene naphthalate polyester obtained in accordance with the process of
1
the present invention can be used in packaging applications such as preparing
transparent monolayer and multilayer containers or products thereof. The material or
container obtained from the polyester of the present invention has comparatively
excellent transparency and superior mechanical, thermal, gas barkier, and optical
properties.
The present invention relates to polybutylene naphthalate polyester used for making
the transparent and gas barrier containers 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, including normal
blow moulding, and heat set blowing process.
These and other features, aspects, and advantages of the present subject matter will
become better understood with reference to the following description and added
claims. This summary is provided to introduce a selection of concepts in a simplified
form. This summary is not intended to identify the key features or essential features
of the claimed subject matter, nor intended to be nsed to limit the scope of the
claimed subject matter.
DETAILED DESCRIPTION OF THE INVENTION:
The present inventors has found that the use of selected crystallization suppressing
agents such as aliphatic or cyclic glycol, aliphatic or aromatic acid, and polyesters,
retards or decrease the rate of crystallization of the polybutylene naphthalate
polyester promoting the requisite growth of the crystallites while reducing their size.
Such slight suppression of the rate of crystallization of polybutylene naphthalate
polyester results in its improved mechanical, thermal, optical and barrier properties.
It has also been found that the use of some preferred comonomer improves
transparency and ga9 barrier properties of the polybutylene naphthalate copolyester
1
while still achieving the requisite higher crystallinity and glass transition temperature.
The comonomers used in the process of the present invention also known as
crystallization suppressing agents that control the crystallization bf the modified
polybutylene naphthalate thereby achieving good transparency and barrier properties
thereof.
The present invention provides modified polybutylene naphthalate polyester that can
be nsed in packaging to produce transparent container. A packaging container, a
packaging material or a preform prepared from the modified polybutylene
naphthalate polyester provides excellent transparency, superior barrier properties,
good mechanical and thermal properties.
The present invention provides a polybutylene naphthalate polyester having excellent
transparency and high barrier properties comprising: naphthalate dicarboxylic acid or
ester thereof; butane diol; crystallization suppressing agent; agent selected from the
group consisting of liquid plasticizer; nucleating agent; branchmg agent; antioxidizing
agent; stabilizing agent; additive and optionally, end capped oligomer,
wherein said polyester exhibits one or more properties as follows: color L* range is
greater than 50 (>50); color b* ranges from 1 to 15; monoethylene content of less
than 10%; glass transition temperature in the range of 60 'C to 85 OC; and haze value
< 7 NTU.
The present invention also relates to products made of transparent polybutylene
naphthalate polyester, comprising: one naphthalate dicarboxylic acid or ester thereof;
butane diol; one comonomer selected from the group of alkylene diol, cyclic diol
aliphatic acid, aromatic acid, polyester Qn an amount of 1 to 20 wt%.; agent selected
1
from the group consisting of liquid plasticizer in an amount of 0.5 to 2 wt%;
nucleating agent in an amount of 10 ppm to 2000 ppm; branching agent in an amount
of 10 ppm to 2000 ppm; anti-oxidizing agent in an amount ranging from 0.1 to 5
wt%; stabilizing agent; additive and optionally, end capped oligomeriin an amount of
1 to 20 wt%.
The polyester of the present invention exhibits one or more properties of color L*
ranges from 58 to 73 %, color b* ranges from 1 to 15; monoethylene content of less
than 6.5 %; glass transition temperature in the range of 60 OC to 85 OC; haze value is
> 5 NTU.
The polyester is obtained from the esterification of naphthalene dicarboxylic acid
(NDA) or 2, 6-dimethyl naphthalene dicarboxylate (NDC) 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.
The present invention provides a process wherein the alkylene diol used as
comonomer is selected from the group consisting of monoethylene glycol, diethylene
glycol, propanediol, butanediol, hexane diol and the like.
The present invention relates to a process wherein the cyclic diol used as comonomer
is selected from the group consisting of cyclohexane dimethanol, and the like.
i
1
The carhoxylic acid used as comonomer is selected from the group consisting of
oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acv, pimelic acid,
suberic caid, azelaic acid, sebacic acid, hrassidic caid, thapsic acid, maleic acid,
fumaric acid, glutaconic acid, alpha-hydromuconic acid, beta-hydromuconic acid,
alpha-butyl, alpha-ethylglutaric acid, alpha-beta-diethyl succinic acid, isophthalic
acid, terepbthalic acid, hemimellitic acid and 1,4-cyclohexanedicarboxylic acids.
The polyester used as comonomer is selected from the group consisting of
polyethylene terphthalate (PET), polyethylene terphthalate glycol modified (PET-G),
polyethylene naphthalene (PEN).
The word "comonomer" and "crystallization suppressing agent" can interchangeably
used throughout the specification without affecting their original intention or
technical contribution to the present invention.
Examples of the comonomer useful for the purpose of the present invention is at
least one selected from the group consisting of monoethylene glycol, diethylene
glycol, isophthalaic acid, polyethylene naphthaate, polyethylene terphthalate,
polyethylene terphthalate glycol-modified (PET-G) and 1,4-cyfilohexane dimethanol
in an amount upto 5%., nucleating agent in an amount of (10 ppm to 2000 ppm) and
liquid plasticizer in an amount of (0.5 to 2 wt% based on polyester weight),at least
one stabilizing agent and at least one anti-oxidizing agent in an amount ranging from
( 0.1 to 5 wt. % based on polyester weights). Other agents useful for the purpose of
the present invention include at least one end capped oligomer in an amount from 1 to
20 wt% based on the total weight of the polyester.
4
1
The branching agent useful for the purpose of the present invention includes but is
not limited to 1,2,4-benzenetricarboxylic acid (trimellitic acid); trimethyl-1,2,4-
benzenetricarboxylate; 1,2,4-benzenetricarboxylic anhydride (trimellitic anhydride);
1,3,5-benzenetricarboxylic acid; 1,2,4, 5-benzenetetracarboxylic acid (pyromellitic
acid); 1,2,4,S-benzenetetracarboxylic dianhydride (pyrornellitic anhydride); 3,3',4,4'-
benzophenonetetracarboxylic dianhydride; 1.4,5,8-naphthalenetetracarboxylic
dianhydride; citric acid; tetrahydrofuran-2,3, 4,5-tetracarboxylic acid; 1,3,5-
cyclohexanetricarboxylic acid;pentaerythritol, 2-(hydroxymethy1)-l,3-propanediol;
2,2-bis(hydroxymethy1) propionic acid; sorbitol; glycerol and combinations thereof.
Particularly, branching agents such as pentaerythritol, trimellitic acid, trimellitic
anhydride, pyromellitic acid, pyromellitic anhydride and sorbitol are used.
The branching agent present in the polyester of the present invention is in an amount
of I0 ppm to 2000 ppm.
The nucleating agent improves the crystallinity and increases heat deformation
temperature of the polyester product. The nucleating agent can be organic or
inorganic. The inorganic nucleating agent useful for the purpose of the present
invention includes but is 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 and 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 invention.
Examples of organic nucleating agent includes hut is 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 lsjurate, potassium
laurate, sodium myristate, potassium myristate, calcium myristate, sodium
octacosanoate, calcium octacosanoate, sodium stearate, potassium stearale, 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 cyclohexane 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, pahitic acid amide,
hydroxystearic acid amide, erucic acid amide and tris(t-hutylamide) 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-butylpheny1)sodium.
Tne nucleating agent present in the polyester of the present invention is in an amount
of 10 ppm to 2000 ppm.
Examples of liquid plasticizer useful for the purpose of the present invention includes
but is not limited to N-isopropyl benzene sulfonamide, N-text-butyl benzene
sulfonamide, N-pentyl benzene sulfonamide, N-hexyl benzene sulfonamide, N-noctyl
benzene sulfonamide, N-methyl-N-butyl benzene sulfonamide, N-methyl-Nethyl
benzene sulfonamide, N-methyl-N-propyl benzene sulfonamide, N-ethyl-Npropyl
benzene sulfonamide, N-ethyl p-ethylbenzenesulfonamide, N-ethyl p-(tbuty1)
benzene sulfonamide, N-butyl p-butyl benzene sulfonamide, N-butyl toluene
sulfonamide, N-t-octyl toluene sulfonamide, N-ethyl-N-2-ethylhexyl toluene
sulfonamide, N-ethyl-N-t-octyl toluene sulfonamide and tri-octyltrimellitate.
Examples of anti-oxidizing agent includes but is not limited to irganox 1010, irganox
1076, irgafos 126 and irgafos 168.
The anti-oxidizing agent present in the polyester of the present invention is antioxidizing
agent in an amount of 0.1 wt% to 5 wt%.
Examples of stabilizing agent includes but is not limited to ortho-phosphoric
acid,trimethylphosphate (TMP), triphynylphosphate (TPP) and Triethyl phosphono
acetate (TEPA). Preferably ortho-phosphoric acid is used as stabilizing agent.
Examples of end capped oligomer includes but is not limited to oligomers of
polyethylene terephthalate, polybutylene terephthalate, polytrimethylene
terephthalate, polytreimethylenenaphthalate and polybutylenenaphthalate.
The end-capped oligomer present in the polyester of the present invention is in an
amount of 1 to 20 wt%.
The polyester product of the present invention additionally may comprise additives
which include but are not limited to pigments; thermal stabilizers, ultraviolet light
stabilizers processing aids; impact modifiers.
I In one embodiment , the present invention relates to a process for preparing transparent
polybutylene naphthalate polyester, for improving barrier performance of polyesters used in
making of monolayer or muttilayer containers, comprising steps of: mixing butane diol
with polymerization catalysts, monoethylene glycol, color toner, and at least one
crystallization suppressing agent wherein said crystallization suppressing agent
controls the rate of crystallization so as to control size and shape of crystals to ensure
transparency; reacting said mixture with naphthalene dicarboxylic acid or ester
thereof to obtain oligomerized product via esterification or ester interchange;
polymerizing said oligomer using at least one polymerization catalyst to obtain
amorphous polybutylene naphthalate polyester chips; crystallizing said polybutylene
naphthalate polyester chips; and subjecting said polyester chips to solid state
polymerization to upgrade the intrinsic viscosity (I.V.) up to more than 0.40 dllgm.
In one another embodiment transparent polybutylene naphthalate polyester can be
made by a process comprising: obtaining prepolymers by reacting dicarboxylic acid
or ester made thereof, and butane diol with crystallization suppressing agent in
presence of catalysts, crystallization suppressing agent or comonomer, color tonner,
and other other additives essential for the process, wherein the esterification is carried
out at about 150 "C to 202'C of product temperature and about 220 "C to 240 "C of
HTM temperature under atmospheric pressure for about 4 to 5 hours, the byproduct is
removed from the reactor after about 2.5 hours and subsequently at the end of the
esterification; polymerizing the prepolymers so obtained in a polycondensation
reactor at temperature about 195 "C to 250 "C (product temperature) and about 260
"C to 270 OC (HTM temp) under ambient pressure; melt extruding the copoiyester,
and cutting under chilled water into amorphous chips; solid state pblymerizing the
chips to achieve the required 1.V.of the polyester.
In one of the embodiments the present invention relates to a transparent polybutylene
naphthalate polyester for use in monolayer and multilayer container manufacturing,
the polyester product exhibiting at least one of: a polyethylene terephthalate
equivalent internal viscosity of > 0.50 dLIg; an oligomer content of less than 1.5
wt%.; a diethylene content of less than 10 wt%; a carboxylic end groups of less than
100 meqkg; haze value < 7 NTU, wherein said polybutylene naphthalate polyester is
used to improve the barrier performance and maintain transparency of polyethylene
terephthalate polyester and products made thereof.
In one embodiment of the present invention the dicarboxylic acid used in the
aforementioned process includes but is not limited to oxalic acid, malonic acid,
succinic acid, gIutaric acid, adipic acid, pimelic acid, suberic caid, azelaic acid,
sebacic acid, brassidic caid, thapsic acid, maleic acid, fumaric acid, glutaconic acid,
alpha-hydromuconic acid, beta-hydromuconic acid, alpha-butyl, alpha-ethylglutaric
acid, alpha-beta-diethyl succinic acid, isophthalic acid, terephthalic acid, hemimellitic
acid, 1, 4-cyclohexanedicarboxylic acids, and naphthalate dicarboxylic acid. In one
embodiment of the present invention the dicarboxylic acid used is selected from the
group consisting of terephthalic acid; isophthalic acid; 2, 6 naphthalene dicarboxylic
acid and combinations thereof. In a preferred embodiment of the present invention
the dicarboxylic acid used in the process is 2,6-naphthalene dicarboxylic acid or ester
thereof. In one embodiment the preferred dicarboxylic acid is 2, 6-naphthalene
dicarboxylic acid.
I
In an embodiment of the present invention, the crystallization suppressing agent is at
least one selected Dom the group of alkylene diol, cyclic diol, aliphatic or aromatic
acid or polyester. The suppressing agent used in the process controls the required rate
of crystallization of polybutylene naphthalate during the process, thus the suppressing
agent acts as a crystallization suppressing or retarding agent or quenching agent
during thelmal crystallization while cooling from the melt phase.
In one embodiment of the present invention the clystallization suppressing agent is at
least one selected from the group consisting of monoethylene glycol, diethylene
glycol, isophthalic acid, cyclohexane dimethanol, or combination thereof.
In one embodiment of the present invention the polyester is at least one selected from
the group consisting of polyethylene terphthalate (PET), polyethylene terphthalate
glycol modified (PET-G), polyethylene naphthalene @EN) or combimation thereof.
In one embodiment of the present invention the crystallization suppressing agent is
used in an amount ranging from about 1 to 20 wt. % based on the polymer weight.
In one embodiment the ester of the aromatic dicarboxylic acid is selected from the
group consisting of dimethyl terephthalate; dimethyl isophthalate; dimethyl-2, 6-
naphthalene dicarboxylate, and combinations thereof.
In one embodiment where cycloaliphatic diol such as (cis, trans) 1, 3-cyclohexane
dimethanol and (cis, trans) 1,4 cyclohexane dimethanol is used it is supplemented
4 , with at least one additional cyclic or branched diol.
The suppressing agent is reacted with at least one aromatic dicarboxylic acid or ester
thereof at 200 to 260 OC to obtain prepolymer after esterification or transesterification.
The reaction is catalyzed by catalysts such as the 'acetate or other
alkanoate salts of Co(11) and Sb(III), oxides of Sb(1II) and Ge(lV), and Ti(0R)d
(where R is an alkyl group having 2 to 12 carbon atoms). Glycol solubilized oxides of
these metal salts such as n-butylstannoic acid can also be used.
In one preferred embodiment catalysts include but are not limited to antimony
trioxide, germanium dioxide, tetraisopropyltitanate. The esterified or trans-esterified
product is simultaneously converted into oligomerized product. The oligomerized
product can he used for coating normal polyester chips and then processed for solid
state polymerization to increase the viscosity of polyester to get improved Tg and
mechanical properties,
Examples of alkylene aryl dicarhoxylate include hut are not limited to ethylene
terephthalate; ethylene isophthalate; ethylene-2,6-naphthalate; ethylene-3,4'-diphenyl
ether dicarboxylate; ethylene hexahydrophthalate; ethylene-2,7-naphthalate; ethylene
phthalate and ethylene-4,4'-methylenebis(benzoate).
The polymerization reaction is carried out by a process known to a person skilled in
the art which includes process steps such as polycondensation and solid state
polymerization reactions to obtain modified polybutylene naphthalate with excellent
transparency. The polyester manufactured in polymerization reaction is crystallized in
any convention crystallizer and subsequently processed in batch or continuous solid
state polymerization (SSP) to get the desired intrinsic viscosity (IV). The batch SSP
may be pursed with nitrogen to expedite the reaction. In continuous SSP the
circulatingnitrogen gas is used as a carrier of by- products.
The polymerization reaction is carried out using at least one agent selected from the
4
group consisting of branching agent, nucleating agent and liquid plasiticizer.
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; flame retardant additives such as decabr~modiihene~tlh er and
triarylphosphates, such as triphenylphosphate; reinforcing agents such as glass fibers;
thermal stabilizers; ultraviolet light stabilizers processing aids, impact modifiers, flow
enhancing additives, ionomers, liquid crystal polymers, fluoropolymers, olefins
including cyclic olefms, polyamides and ethylene vinyl acetate copolymers.
After reaching at a required degree of polymerization in the melt phase of
polycondensation reaction the copolymer of polybutylene naphthalate is granulated
into chips.
The polymerization reaction is carried out using at least one agent selected from the
group consisting of branching agent or chain extending agent, nucleating agent and
liquid plasticizers.
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 modified polybutylene naphthalate is extrnded and granulated using underwater
cutter to obtain chips which are transparent. The chips are dried, injection molded to
preform by processing at temperqure above its melting point. The preforms are
further processed into containers by IBM (Injection Blow Moulding); ISBM
(Injection Stretch Blow Moulding). These containers are transparent and can be
monolayer or multilayer. I
The present invention also provides a packaging product comprising the polyester
obtained according the present disclosure. The packaging product can be a preform or
a packaging material or a packaging container.
The modified polyhutylene naphthalate obtained in accordance with the present
invention imparts improved barrier properties and transparency [haze value below 7
Nephelometric Turbidity Units o]and imp,roves th e gas barrier properties of the
polyester in which it is added without any adverse effect on haze. The PBN prepared
in accordance with the present invention can be used to manufacture 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.
Containers can be monolayer or multilayer.
Another embodiment of the present invention would be the polybutylene naphthalate
having haze value of less than 5 NTU.
Further, the polybutylene naphthalate of the present invention is having haze value of
less than 3 NTU.
4 .
The polybutylene naphthalate polyester of the preseqt rnvention is used for making
the transparent packaging containers and products thereof.
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 polyester of the present invention exhibits one or more properties of intrinsic
viscosity greater than 0.48 dllgm, color L* value is greater than 50 %, preferebaly
less than 0.58 dl?gm; color b* ranges from 1.0 to 15.0; monoethylene glycol content
of less than 10 %, glass transition temperature in the range of 60 to 85 'C; haze value
is less than 7 NTU, preferably less than 3 NTU. Said properties are used as quality
parameters of the final finished product.
The quality parameters of the polyester in accordance to the present invention, 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 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) 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 endothelm
4
temperatures and heats of fusion for all materials.
EXAMPLES
The following non-limiting examples are intended to illustrate, but not to limit, the
scope of the present invention.
Example 1: Preparation of clearltransparent Polybutylene Naphthalate by
incorporation of monoethylene glycol (MEG) as Comonomer
In a 250 L reactor equipped with stirrer, condenser, pressuring and vacuum system,
9.43 kg of naphthalene dicarboxylic acidand 2.09 kg of 1,4-butane diol in molar ratio
of 1: 1.6 for 10 Kg of PBN batch size were made into paste and fed into the
esterification reactor. Further 1.48 gm (25 ppm as Ti) of polymerization catalysts
TiT, which can be prepared by mixing TiPT with 200 ml of BDO, is added to the
reactor. Other chemicals, such as 1.44 kg (0.60 ppm as MEG) of monoethylene
glycol (MEG) added while charging with BDO. Further 0.003 kg (0.3 ppm as BT) of
BT prepared by mixing BT with 100 ml of MEG, 0.70 kg (0.20 ppm as BDO) of
BDO are added at various stages of the esterification.
Esterification was carried out at 150 OC to 202'C of product temperature and 220 "C
to 240 "C of HTM temperature under atmospheric pressure for 300 minutes. During
the esterification 1.97 kg and 2.47 kg of MeOH is collected as by product at after 150
minutes and at the end of the esterification.
Thereafter, the prepolymer along with all additives are transferred into poly
condensation reactor and polymerization is conducted at 195 OC to 250 "C (product
temperature) and 260 "C to 270 OC (HTM temp) under pressure. The
polycondensation reaction was monitored based on reactor agitator power
consumption and reaction was terminated to get Intrinsic Viscosity (I.V.) of about
0.58~0.01dLlg and the polybutylene naphthalate copolyester melt was extruded out
1
and cut under water and collected as $hips.
These chips can be further upgraded to required I.V. in solid state polymerization
reaction.
Example 2: Preparation of Clear or transparent Polybutylene Naphthalate by
incorporation of II'A as Cornonorner
In a 250 L reactor equipped with stirrer, condenser, pressuring and vacuum system,
initially 4.7 kg of 1, 4-butane diol is heated to a temperature of 150 to 180 OC, and it
is then reacted with 8 kg of 2,6-dimethyl naphthalene dicarboxylate and 4.1 kg of
isophthalaic acid in presence of 2.45 gm (35 ppm as Ti) of polymerization catalysts
TnBT catalyst, which can be prepared by mixing it with 200 ml of 1,4-butane diol, at
temperature of 170 to 200 'C and atmospheric pressure for two to three hours. The
catalysts and isophthalaic acid can be added at various stages of the esterification
reaction. The esterification reaction was carried out at temperature of 150 "C to
21O0Cunder atmospheric pressure for 3 to 4 hours. During the esterification reaction,
methanol (MEOH) is collected as by product.
After the esterification reaction was completed, the oligomers along with all additives
were transferred into poly condensation reactor and polymerization is conducted at
195 OC to 280 "C under vacuum. The polycondensation reaction was monitored based
on reactor agitator power consumption and reaction was terminated to get I.V. of
about 0.52 to .60 dL/g and fmally the polybutylene naphthalate polyester melt was
extruded out and granulated to the polyester chips.These chips can further be
upgraded to required I.V. in solid state polymerization reaction.
Example 3: Preparation of Clear Polybutylene Naphthalate by incorporation of
PET as Comonomer
4
In a 250 L reactor equipped with stirrer, condenser, pressuring and vacuum system,
2.9 kg of 1, 4-butane diol is heated to a temperature of 140 to 190 "C, and it is then
reacted with 7.06 kg of 2,6-dimethyl naphthalene dicarboxylate in presence of 2.06
gm (35 ppm as Ti) of polymerization catalysts TnPT catalyst, whichcan be prepared
by mixing TnPT with 200 ml of 1,4-butane diol for each dose, at temperature of 170
to 200 OC and atmospheric pressure for three to four hows. The catalysts can be
added at various stages of the esterification reaction. The esterification reaction was
carried out at temperature of 150 "C to 210°C under atmospheric pressure for 3 to 4
hours. Dwing the esterification reaction, methanol (MEOH) is collected as by
product.
After the esterification reaction was completed, the oligomers along with all additives
were transferred into poly condensation reactor and polymerization is conducted at
195 "C to 280 "C under vacuum. Further, 3.00 kg polyethylene terphthalate was
added to the polyester at the end of the polymerization at a constant temperature
selected in a range of 240 to 260 'C. The preferred temperature is 255 "C
temperature. The polycondensation reaction was monitored based on reactor agitator
power consumption and reaction was terminated to get I.V. of about 0.52 to .GO dL/g.
At the end of the process, the polybutylene naphthalate polyester melt was extruded
out and granulated to the polyester chips. These chips can further be upgraded to
required I.V. in solid state polymerization reaction.
Example 4: Preparation of Clear Polybutylene Naphthalate by incorporation of
PEN as Comonomer
In a esterification reactor, 2.9 kg of 1,4-butane diol is heated to a temperature of 140
to 190 OC, and then it is reacted with 7.06 kg of 2,6-dimethyl naphthalene
dicarboxylate in presence of 2.06 gm (35 ppm as Ti) of polymerization catalysts
TnPT catalyst, which can be prepared by mixing TnPT with 200 ml of 1,4-butane diol
1
for each dose, at temperature of 170 to 200 "C and atmospheric pressure for three to
four hours. The catalysts can be added at various stages of the esterification reaction.
The esterification reaction was carried out at temperature from 150 "C to 210°C
under atmospheric pressure for 3 to 4 hours. During the esterigcation reaction,
methanol (MEOH) is collected as by product.
After the esterification reaction was completed, the oligomers along with all additives
were transferred in to polycondensation reactor and polymerization is conducted at
195 "C to 280 OC under vacuum. Further, 3.00 kg polyethylene naphthalate was
added to the polyester at the end of the polymerization at a constant temperature
selected in a range of 240 to 260 "C. The preferred temperature is 255 "C
temperature. The polycondensation reaction was monitored based on reactor agitator
power consumption and reaction was terminated to get I.V. of about 0.52 to .60 dL/g.
At the end of the process, the polybutylene naphthalate polyester melt was extruded
out and further granulated to the polyester chips. These chips can further be upgraded
to required I.V. in solid state polymerization reaction.
The above examples are one of such methods by which modified polybutylene
naphthalate can be prepared. The objectives of the invention can be achieved by using
comonomer as crystallization suppressing agents selected from the group consisting
of inonoethylene glycol, dieethylene glycol, propanediol, butanediol,
cyclohexanedimethanol, hexane diol and the like, 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, alphahydromuconic
acid, beta-hydromuconic acid, alpha-butyl, alpha-ethylglutaric acid,
alpha-beta-diethyl succinic acid, isophthalic acid, terephthalic acid, hemimellitic acid
and 1,4-cyclohexanedicarboxylic acids, polyethylene naphthalene (PEN) and the like.
Different samples of the modified polybutylene polyester were synthesized by using
the similar procedure disposed above in Example-1 by using formulation mentioned
in the Table 1. The quantity of the raw materials mentioned in the table is in weight
percentage with respect to the polymer. The melting, crystallizatiqn and the glass
transition temperatures of the polyester were measures using DSC and the results are
summarized in table 2.
Table 1: Tabulation of raw materials employed and results obtained in Examples 1,
Example 4
7.06
Raw Materials
NDC
Example 2
8
Example 3
7.06
Unit
Kg
Example 1
9.43
Analysis report for Amorphous Sample
DEGcontent
Glass transition
Temp.(Tg2)
Melting Point (Tml) OC 210 192 185 185
Tch2 OC 97 149 69.8 69.8
OC 80 68 65.4 65.4
Example 5: Manufacture of monolayer containers using modidified
polyhntylene naphthalate polyester by Injection Moulding (IM) Method
The polymer from Example 1 was used on IM machine to manufacture containers.
Prior to that the chips were dried at required temperature for a fixed duration of time.
The mold was cooled with chilled water of 6°C. The melt flow was satisfactory. The
containers of 350p wall thickness were manufactured. The containers were of good
color & transparency with superior barrier properties
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 unnecessqrily 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 & to practice the
embodimenh herein. Accordingly, the examples should not be constrned 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 and/or 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.
While considerable emphasis has been placed herein on the particular features of this
invention, it will be appreciated that various modifications can be made, and that
many changes can be made in the preferred embodiments without departing from the
principles of the disclosure. These and other modifications in the nature of the
invention 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 process for preparing transparent polybutylene naphthalate polyester, for improving
barrier performance of polyesters used in making of monolayer or multilayer
containers, comprising steps of:
a) mixing butane diol with polymerization catalysts, monoethylene glycol, color
toner, and at least one crystallization suppressing agent, wherein said
crystallization suppressing agent controls the rate of crystallization so as to control
size and shape of crystals to ensure transparency;
b) reacting said mixture with naphthalene dicarboxylic acid or ester thereof to obtain
oligomerized product via esterification or ester interchange;
c) polymerizing said oligomer using at least one polymerization catalyst to obtain
amorphous polybutylene naphthalate polyester chips;
d) crystallizing said polybutylene naphthalate polyester chips; and
e) subjecting said polyester chips to solid state polymerization to upgrade the
intrinsic viscosity (I.V.) up to more than 0.40 dVgm.
4
I 2. The process as claimed in claim 1, wherein the said suppressing agent is used in an
amount ranging from 1 to 20 wt. %based on total weight of the polyester.
3. The process as claimed in claim 1, wherein the suppressing agey~t is at least one
selected from the group consisting of alkylene diol, cyclic diol, aliphatic or aromatic
acid, polyester, or combination thereof.
4. The process as claimed in claim 3, wherein the said alkylene diol is selected from the
group consisting of monoethylene glycol, diethylene glycol, propanediol, butanediol,
hexane diol and the like.
5. The process as claimed in claim 3, wherein the said cyclic diol is selected from the
group consisting of cyclohexane dimethanol, and the like.
6. The process as claimed in claim 3, wherein the said aromatic acid is isophthalic acid.
7. The process as claimed in claim 3, wherein the said polyester is selected from the
group consisting of polyethylene terphthalate, polyethylene terphthalate glycol
modified, polyethylene naphthalene.
8. The polybutylene naphthalate polyester as and when prepared by the process as claimed
in claims 1 to 7.
9. A polybutylene naphthalate polyester having excellent transparency and high barrier
properties comprising:
naphthalate dicarboxylic acid or ester thereof; butane diol; crystallization
suppressing agent; agent selected from the group consisting of liquid
plasticizer; nucleating agent; branching agent; anti-oxidizing agent; stabilizing
agent;
additive and optionally, end capped oligomer, wherein said polyester exhibits
one or more properties as follows:
color L* range is greater than 50 (>50);
color b* ranges from 1 to 15;
4 monoethylene content of less than 10%;
1
glass transition temperature in the range of 60 OC to 85 OC; and
haze value < 7 NTU.
10. The polyester as claimed in claim 9 wherein said liquid plasticizer ih in an amount of
0.5 wt.% to 2 wl.%.
11. The polyester as claimed in claim 9, wherein the nucleating agent used is at least one
1, 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.
12. The polyester as claimed in Claim 9, wherein the nucleating agent in an amount of 10
ppm to 2000 ppm.
13. The polyester as claimed in Claim 9, wherein the branching agent in an amount of 10
ppm to 2000 ppm.
14. The polyester as claimed in Claim 9, wherein the said anti-oxidizing agent is in an'
amount of 0.1 wt% to 5 wt%.
15. The polyester as claimed in Claim 9, wherein the said end-capped oligomer is in an
amount of 1 to 20 wt%.
16. The polyester as claimed in claim 9, wherein the haze value of the polyester is less
than 5 NTU.
, . , . . ,
17. The polyester as .cl'airrie&in claim 9, wherein the haze value of the polyester is less
than 3 NTU.
. ,
18. A transparent polybutylene naphthalate polyester for use in monolayer and
multilayer container manufacturing, the polyester product exhibiting at least one of:
a polyethylene terephthalate equivalent internal viscosity of > 0.50 dL/g;
an oligomer content of less than 1.5 wt%.;
a diethylene content of less th+ 10 wt%;
a carboxylic~endg roups of less than 100 meqkg;
haze value 2 7 NTU.
Wherein said polybutylene naphthalate polyester is used to improve the barrier
performance and maintain transparency of polyethylene terephthalate
1 polyester and products made thereof.
I
19. The polybutylene naphthalate polyester as clair.ed in any of the preceding claims, as
, .
, .
and when used in packaging applications such as preparing transparent containers or
products thereof by injection moulding (TM), injection blow moulding, injection stretch
blow moulding (ISBM), or extrusion blow mouldmg.