Title of Invention

A PROCESS FOR RECYCLING A RECOVERED POLYCONDENSATION POLYMER

Abstract A process for recycling a recovered polycondensation polymer, comprising: supplying the recovered polycondensation polymer in a molten state to a polymerization vessel having a porous plate, ejecting the polymer, such as herein described, through pores of the porous plate, and increasing the polymerization degree of the polycondensation polymer under reduced pressure or in an inert gas such as herein described atmosphere under reduced pressure while dropping the polymer along a support.
Full Text DESCRIPTION
METHOD FOR RECYCLING RECOVERED
POLYCONDENSATION POLYMER
TECHNICAL FIELD
[0001]
The present invention relates to a process
for recycling a recovered polycondensation polymer.
BACKGROUND ART
[0002]
A polycondensation polymer represented by
polyethylene terephthalate resin (hereinafter sometimes
referred to as "PET resin"), has excellent features
such as heat resistance, weather resistance, mechanical
resistance, and transparency. Using such features, PET
resin has been widely used in fibers and magnetic tapes
as well as beverage containers, preforms for
manufacturing beverage containers, injection molded
articles for various uses, and extrusion molded
articles such as package films and sheets.
However, in molding such a polycondensation
polymer, a large amount of debris is produced. For
example, defective parts, which are not used as molded
articles, obtained during a molding step such as burr
of a molded article, runner and sprue generated in
injection molding, deckle edge generated in molding

sheet and film; and defective parts, which are not used
as products, obtained in a manufacturing step of a
molded article, such as alternative products in the
middle of replacing existing products with the
alternative products, defective bottles such as pinhole
bottles, nonstandard products, purge products until the
quality is stable, and resin pellets. Furthermore, in
producing a polycondensation polymer, a large amount of
a defective polycondensation polymer that is not used
as a product is generated. Examples of such a
defective polymer include alternative products in the
middle of replacing existing products with the
alternative products, nonstandard products, and purge
products. Moreover, molded articles on market are
recovered as recyclable products. It has been desired
to develop a process for recycling these recovered
products from a recent environmental protection point
of view.
For example, attempts have been made to reuse
a recovered resin by compounding a new polyester and a
scrap polyester at a point of time during a polyester
production step and returning the scrap component to a
flow of the polyester production step (for example, see
Patent Document 1).
[0003]
However, a polycondensation polymer such as
PET resin has a problem in that its polymer chain is
cleaved once heat is applied thereto, decreasing in

molecular weight. Also, a recovered resin decreases in
molecular weight and thus low in physical properties.
Therefore, it is not preferable to employ it again for
its original use. For this reason, the resin thus
recovered is merely used for food trays, which may be
made of a relatively low-molecular weight material and
requires less physical properties.
As one of techniques for continuous melt
polymerization of esters, a method of conducting
polymerization while dropping a prepolymer by gravity
from the top of a polymerization reactor. For example,
as a process for producing polyesters, there is a
technique to supply a PET oligomer having an average
degree of polymerization of 8 to 12 (corresponding to a
limiting viscosity of 0.1 dl/g or less) at 285°C, drop
it by gravity along a cylindrical metal net put
perpendicular inside the reactor and conduct
polymerization with a reduced pressure inside the
reactor (see Patent Document 2) and as a process for
producing polyamides or polyesters, there is a
technique to conduct polymerization while dropping a
polymer along a linear support put perpendicular inside
a reactor (see Patent Document 3). See Patent
Documents 4 to 7. However, according to the present
inventors' study, it is revealed that even if the above
techniques are used as such, it is not possible to
obtain polyesters having a high degree of
polymerization. Further, there is a problem that since

oligomers ejected from a porous plate or the like are
vigorously foamed to foul the surface of the porous
plate or the inner walls of the reactor, so that the
fouling is decomposed and modified to be mixed with the
polymer during a long time operation and so
deteriorates the quality of polyester products. Even
if the scrap component having a quality lowered through
a thermal history is returned to the flow during the
polymerization step by these techniques, it is
impossible to obtain polyesters having a high degree of
polymerization and also the resulting polyesters are
not practically applicable at all because of remarkably
deteriorated hue of the product.
Furthermore, attempts have been made to reuse
a recovered resin as a raw material by completely
decomposing the resin into monomer units (for example,
see Patent Document 8). However, the depolymerization
of a resin into monomer units must be performed in
supercritical conditions in an organic solvent and also
requires a purification step of the crystallization
solvent on recovered monomers. Therefore, cost
inevitably increases.
In the circumstances, it has been desired to
develop a simple and inexpensive recycling process for
a recovered polycondensation polymer by increasing the
molecular weight of the polymer.
[Patent Document 1] JP-B-63-46089
[Patent Document 2] JP-B-58-8355

[Patent Document 3] JP-A-53-17569
[Patent Document 4] US Patent No. 3110547
[Patent Document 5] JP-B-4-58806
[Patent Document 6] WO 99/65970 A
[Patent Document 7] JP-A-58-96627
[Patent Document 8] JP-A-2003-147121
DISCLOSURE OF THE INVENTION
[0004]
An object of the present invention is to
provide a process for recycling a recovered
polycondensation polymer by polymerizing the polymer
with high productivity at a low cost while keeping high
quality.
The present inventors have conducted
intensive studies with view toward solving the
aforementioned problems. As a result, surprisingly,
they have found that the aforementioned problems can be
solved by polymerizing a recovered polycondensation
polymer in appropriate conditions while dropping the
resin along a support. Based on the finding, the
present invention has been completed.
[0005]
More specifically, the present invention is
as follows.
(1) A process for recycling a recovered
polycondensation polymer, comprising supplying the
recovered polycondensation polymer in a molten state to

a polymerization vessel having a porous plate, ejecting
the polymer through pores of the porous plate, and
increasing the polymerization degree of the
polycondensation polymer under reduced pressure or in
an inert gas atmosphere under reduced pressure while
dropping the polymer along a support.
(2) The process according to item (1), wherein
the recovered polycondensation polymer is ejected from
the pores of the porous plate together with an unused
polycondensation polymer and/or an intermediate
polymer.
(3) The process according to item (1) or (2),
wherein the recovered polycondensation polymer with an
improved polymerization degree has a number average
molecular weight of 20,000 to 100,000.
(4) The process according to any one of items (1)
to (3), comprising continuously measuring the melt
viscosity of the recovered polycondensation polymer or
a mixture of the recovered polycondensation polymer
with the unused polycondensation polymer and/or the
intermediate polymer to be supplied to the
polymerization vessel, and continuously adjusting the
pressure reduction degree of the polymerization vessel,
based on measurement results of the melt viscosity.
[0006]
(5) The process according to any one of items (1)
to (4), comprising a step of reacting the recovered
polycondensation polymer or the mixture of the

recovered polycondensation polymer with the unused
polycondensation polymer and/or the intermediate
polymer, with any amount of a molecular weight
adjuster, prior to supplying the recovered
polycondensation polymer or the mixture to the
polymerization vessel.
(6) The process according to any one of items (1)
to (5), wherein the recovered polycondensation polymer
is a recovered polyethylene terephthalate resin and
ejected from the pores of the porous plate at a
temperature ranging from "a crystal melting temperature
- 10°C" to "the crystal melting temperature + 60°C".
(7) A process for producing a molded article
characterized by comprising transferring the polymer
recycled by the process according to any one of items 1
to 6 to a molding machine in a molten state and molding
the polymer.
According to the process for recycling a
recovered polycondensation polymer of the present
invention, it is possible to increase the
polymerization degree of a recovered polycondensation
polymer with good productivity at a low cost while
maintaining high quality.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0065]
Fig. 1 is a schematic view of a
polymerization vessel and molding machine used in the

present invention; and
Fig. 2 is a schematic view of another
polymerization vessel and molding machine used in the
present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0007]
The polycondensation polymer of the present
invention refers to a polymer composed of at least one
type of monomer having not less than two condensable
r
functional groups, the monomers being bound via the
binding of the functional groups. The monomers may be
composed of an aliphatic hydrocarbon to which the
functional groups are directly bound or composed of an
aromatic hydrocarbon to which the functional groups are
directly bound.
[0008]
Examples of such a polycondensation resin
(polymer) include
polymers having a structure in which
aliphatic hydrocarbon groups are bonded via the
functional groups, such as an aliphatic polyester,
aliphatic polyamide and aliphatic polycarbonate;
polymers having a structure in which an
aliphatic hydrocarbon group and an aromatic hydrocarbon
group are bonded via the functional groups, such as an
aliphatic/aromatic polyester, an aliphatic/aromatic
polyamide, and an aliphatic/aromatic polycarbonate; and

polymers having a structure in which aromatic
hydrocarbon groups are bonded via the functional
groups, such as an aromatic polyester and an aromatic
polyamide.
The polycondensation resin mentioned above
may be a homopolymer or a copolymer, or alternatively,
a copolymer having different bonds such as an ester
bond, amide bond, and carbonate bond arranged at random
or en bloc. Examples of such a copolymer include
polyester carbonates and polyester amides.
[0009]
Examples of aliphatic/aromatic polyester
include a PET resin. The PET resin used in the present
invention is preferably composed of ethylene
terephthalate repeating units in a content of no less
than 50% by mole. In other words, the PET resin may be
composed of one or more other copolymer components in a
content of less than 50% by mole.
Examples of such a copolymer component
include
monomers capable of forming an ester such as
5-sodium sulfoisophthalic acid, 3,5-dicarboxylic acid
benzenesulfonate tetramethyl phosphonium salt, 2,6-
nephthalene dicarboxylic acid,
1,3-butanediol, 1,4-butandiol, neopentyl
glycol, 1,6-hexamethylene glycol, 1,4-cyclcohexane
diol, 1,4-cyclohexane dimethanol,
isophthalic acid, oxalic acid, succinic acid,

adipic acid, dodecanoic diacid, fumaric acid, maleic
acid, and 1,4-cyclohexane dicarboxylic acid; and
polyethylene glycol; polypropylene glycol;
polytetramethylene glycol; and copolymers thereof.
The PET resin of the present invention may
contain, other than, the PET resin, a ring-form or
linear oligomer, a monomer such as dimethyl
terephthalate (hereinafter simply referred to as
"DMT"), terephthalic acid (hereinafter simply referred
to as "TPA") and ethylene glycohol (sometimes simply
referred to as "EG"); various types of additives; and
other resins.
[0010]
The present invention is directed to a
process for producing a high-quality polycondensation
polymer by supplying a recovered polycondensation
polymer in a molten state to a polymerization vessel,
thereby increasing a polymerization degree.
The recovered polycondensation polymer used
herein refers to defective products including
alternative products in the middle of replacing
existing products with the alternative products and
resin pellets generated in a polymerization step;
burr, runner, gate, sheet and film edge
generated in a molding step of a polycondensation
polymer;
a massive resin generated in a step from
start-up to a stabilized state, and nonstandard molded

articles generated;
defective products such as pinhole bottles
generated in a production step;
containers recovered for recycling such as
used PET bottle waste; and
recycling flakes of used PET bottle waste
produced by sorting, washing and shattering used PET
bottle waste.
Since a polycondensation polymer such as PET
resin is depolymerized by application of heat and
reduced in molecular weight, a recovered resin product
cannot be reused for its original purpose even if it is
melted again. However, if a recovered polycondensation
polymer reduced in molecular weight is polymerized to
increase the molecular weight, the polymer thus
obtained can be used as a product. In addition, this
attempt is preferable from both economic and
environmental points of view.
The present inventors have conducted studies
under the aforementioned circumstances and found that a
polycondensation polymer of a high polymerization
degree can be obtained by supplying a recovered
polycondensation polymer in a molten state to a
polymerization vessel having a porous plate, ejecting
the molten polymer from the pores of the porous plate,
increasing a polymerization degree of the
polycondensation polymer under reduced pressure or in
an inert gas atmosphere under reduced pressure while

dropping it along a support, and continuously taking
out the resultant polymer from the polymerization
vessel.
[0011]
The temperature during polymerization
performed in a polymerization vessel according to the
present invention preferably ranges from "the crystal
melting point of a recovered polycondensation polymer -
10°C" to "the crystal melting point + 60°C".
In the case of recovered PET resin, the PET
resin of a high polymerization degree can be obtained
by supplying recovered PET resin to a polymerization
vessel in a molten state, ejecting it from the pores of
the porous plate at a temperature ranging from "the
crystal melting point of the resin - 10°C" to "the
crystal melting point + 60°C", preferably from "the
crystal melting point - 5°C" to "the crystal melting
point + 40°C", and further preferably, from "the crystal
melting point + 1°C" to "the crystal melting point +
30°C", increasing the polymerization degree of the resin
under reduced pressure, while dropping along a support,
and continuously taking out from the polymerization
vessel.
[0012]
In the present invention, when a recovered
polycondensation polymer is introduced into a
polymerization vessel, it is preferable that the
polymer is sorted if necessary, shattered, washed,

dried, melted and introduced into the polymerization
vessel of the present invention. It is also preferable
that the recovered polymer is crystallized before dried
to avoid melt-solidification. To attain this, if
necessary, an extruder and/or a preparatory melting
vessel may be arranged upstream of the polymerization
vessel of the present invention with a crystallization
apparatus, sorting apparatus, shattering apparatus,
washing apparatus, and dryer interposed between them.
As the extruder, use may be preferably made of the one
that melts and supplies a resin. An extruder may be
appropriately chosen from those having a single screw,
double screw, a rotatable screw in the same direction,
and a rotatable screw different directions. As the
dryer, use is preferably made of the one that can be
removed a moisture content as much as possible to avoid
a decrease of the polymerization degree in melting.
More specifically, use may be preferably made of a
dryer using hot-air flow or inert gas flow, or a vacuum
dryer. As the temperature of a dryer, any temperature
is acceptable as long as oxidation and heat
deterioration can be avoided, and preferably 180°C or
less.
In particular, a low crystalline state of a
recovered PET resin is developed by abruptly cooling
when a molded article or a molten resin is taken out in
some cases. In other cases, melt solidification of
resin pieces is developed by abruptly heating when it

is dried. When melt-fusion takes place, feeding of a
resin by an extruder is inhibited. Therefore, the
resin is preferably crystallized in advance by heating
it to the melting temperature or less.
[0013]
A recovered polycondensation polymer is
supplied in a molten state from a preparatory melting
vessel and/or an extruder to a polymerization vessel
according to the present invention. If necessary, it
may be supplied via a filter.
A recovered polycondensation polymer may be
supplied singly to a polymerization vessel according to
the present invention for recycling. Alternatively, a
recovered polycondensation polymer may be supplied
together with an unused polycondensation polymer and/or
an intermediate polymer to a polymerization vessel
according to the present invention, for recycling. The
unused polycondensation polymer used herein refers to
unused resin pellets that have not been used for
molding since they were produced, or an unused
polycondensation polymer in a molten state produced and
taken out from a molten polymerization vessel.
Furthermore, the intermediate polymer used herein
refers to a polymer of the initial polymerization stage
having a low polymerization degree compared to the
polycondensation polymer used as a product, and may
contain an oligomer and a monomer. A recovered
polycondensation polymer can be mixed with these unused

polymerization condensation polymer and/or an
intermediate polymer, supplied to the preparatory
melting vessel and/or extruder, and introduced into a
polymerization vessel according to the present
invention in a molten state.
Alternatively, use may be preferably made of
a process for improving handleability and controlling
the polymerization degree and productivity of a
recycled product by reacting a recovered
polycondensation polymer or a mixture of a recovered
polycondensation polymer and an unused polycondensation
polymer and/or an polymer intermediate polymer, with
any amount of a molecular weight adjuster, in any step
before supplying the recovered polycondensation polymer
or the mixture to a polymerization vessel according to
the present invention.
[0014]
Next, a step of polymerizing a recovered
polycondensation polymer in a polymerization vessel
according to the present invention will be explained.
The polymerization degree of a recovered
polycondensation polymer or a mixture of a recovered
polycondensation polymer and an unused polycondensation
polymer and/or an intermediate polymer suitable for
supplying to a polymerization vessel according to the
present invention can be defined by a melt viscosity
when the viscosity is evaluated at a temperature of
polymerization carried out in the polymerization vessel

of the present invention, at a shear rate of 1000
(sec-1) . The melt viscosity preferably ranges from 60
to 100,000 poises. When the melt viscosity is set at
60 poises or more, it is possible to suppress vigorous
foaming and scattering of an intermediate polymer
ejected from pores of a porous plate of the
polymerization vessel. When the melt viscosity is set
at 100,000 poises or less, a reaction side-product can
be efficiently removed out of the system, facilitating
polymerization without a problem. More preferably, the
melt viscosity ranges from 100 to 50,000 (poise),
further preferably, 200 to 10,000 poise, and most
preferably, 300 to 5,000 (poise). In the present
invention, it is preferable that an intermediate
polymer has such a relatively high viscosity. This is
because a resin can be polymerized while containing a
large amount of foams, with the result that the
polymerization rate can be greatly increased.
When a recovered polycondensation polymer is
PET resin, a polymerization degree preferably falls
within the range of 0.40 to 1.20 dl/g in terms of an
intrinsic viscosity [T|] , which is used generally for
expressing viscosity.
[0015]
In the present invention, to manufacture a
recycled product in high quality, it is important to
suppress a molten-state of the recovered
polycondensation resin ejected from the pores of a

porous plate from vigorous foaming and scattering in a
polymerization vessel according to the present
invention. When the recovered polycondensation polymer
is ejected at the aforementioned temperature,
scattering of the recovered polycondensation polymer
caused by vigorous foaming can be suppressed and a
polymerization reaction side produce is removed outside
the system, with the result that a polycondensation
reaction can be performed efficiently.
When the resin ejected from the pores of a
porous plate is vigorously foamed and scattered, the
scattered resin is adhered to and smears the mouth ring
surface and wall surfaces of the porous plate for
ejection. The attached resin, if it retains for a long
time, is decomposed with heat and produces a colored
low molecular weight material or a degradation product.
If a desired resin is contaminated with such a
material, the resin decreases in quality and fails to
acquire a desired polymerization degree.
[0016]
To prevent scattering of a resin (PET resin)
caused by vigorous foaming, it is preferable that the
intrinsic viscosity [η] of a recovered polymer that is
to be supplied to a polymerization vessel according to
the present invention, is adjusted to not less than
0.40 dl/g. On the other hand, to remove efficiently a
polycondensation reaction side-product such as EG from
the system and to drop the resin while maintaining

proper foaming for improving the polymerization degree,
it is desirable to reduce the intrinsic viscosity of
the recovered resin. The intrinsic viscosity of the
recovered resin is preferably 1.20 or less, further
preferably 0.50 to 1.00 dl/g, and more preferably 0.60
to 0.90 dl/g.
[0017]
To obtain high-quality PET while suppressing
foaming by imparting an appropriate viscosity and while
preventing coloration due to heat decomposition, it is
preferable that the ejection temperature of the
recovered PET resin is set at not more than "a crystal
melting point + 60°C". On the other hand, to uniformly
eject the molten resin from a porous plate and drop the
resin along a support while maintaining a uniform
molten state, the ejection temperature is preferably
set at not less than "a crystal melting point of the
recovered resin - 10°C", more preferably, from "the
crystal melting point - 5°C" to "the crystal melting
point + 40°C", and further preferably from "the crystal
melting point + 1°C" to "the crystal melting point +
30°C". Generally, the crystal solidifying point of a
polymer is considerably lower than the crystal melting
point. In particular, the crystal solidifying point of
a resin having a low crystallinity falls over several
ten degrees. Since a polyethylene terephthalate resin
does not have good crystallinity, it can be handled at
a temperature lower by 10°C from the crystal melting

point.
Note that the crystal melting point is
defined by a peak endothermic temperature due to
melting of a crystal measured by an input compensation
type differential calorimeter, Pyris 1 DSC ((trade
name, manufactured by Perkin Elmer Inc.) in the
following conditions. The peak temperature was
determined by use of the analysis software attached
thereto.
Measuring temperature: 0 to 300°C
Temperature raising rate: 10°C/min.
The ejection temperature is preferably from
"a crystal melting point - 10°C" to "the crystal melting
point + 60°C", more preferably, from "the crystal
melting point - 5°C" to "the crystal melting point +
40°C", and further preferably, from "the crystal melting
point + 1°C" to "the crystal melting point + 30°C". In
particular, to reduce the content of impurities such as
acetoaldehyde, polymerization is desirably performed at
as a low temperature as possible.
[0018]
The porous plate for use in ejecting a
recovered polycondensation polymer is a plate-form
member having a plurality of through-holes. The
thickness of the porous plate is not particularly
limited; however, generally ranges from 0.1 to 300 mm,
preferably 1 to 200 mm, and further preferably, 5 to
150 mm. The porous plate must withstand the pressure

given by a recovered polymer supply chamber containing
molten-state polymer; at the same time, have a strength
for supporting the weight of a support and recovered
polymer that falls along the support, in the case where
the support of a polymerization chamber is immobilized
to the porous plate. It is also preferable that the
porous plate is reinforced by a rib or the like.
[0019]
The shape of pores of the porous plate may be
selected generally from circular, ellipsoidal,
triangular, slit-form, polygonal, and star shapes. The
sectional area of a pore generally falls within the
range of 0.01 to 100 cm2, preferably 0.05 to 10 cm2, and
particularly preferably 0.1 to 5 cm2. The porous plate
may have a nozzle or the like connected to the pore(s).
The interval between pores falls generally within the
range of 1 to 500 mm, and preferably 25 to 100 mm in
terms of the distance between the centers of pores.
The pores of the porous plate may be through-holes or
tubes attached thereto, and alternatively, a tapered
form. It is preferable to set the size and shape of
pores such that a pressure loss of a molten recovered
PET resin, when it passes through the porous plate,
falls within the range of 0.1 to 50 kg/cm2.
The material of the porous plate is generally
and preferably a metallic material such as stainless
steel, carbon steel, hastelloy, nickel, titanium,
chromium and other alloys.

Furthermore, it is preferable to set a filter
in a channel for a molten-state recovered polymer at
the upstream side of the porous plate. Foreign matter
clogging the pores of the porous plate can be removed
by the filter. The type of filter is appropriately set
so as to remove foreign matter equal to and larger than
pore sizes of the porous plate and so as not to be
broken by a recovered polymer passing therethrough.
[0020]
Examples of a process for ejecting a
recovered polymer through such a porous plate, include
a process for dropping a recovered polymer by use of a
liquid head or its own gravity, and a process for
pressurizing and extruding a polymer by a pump. Use
may be preferably made of a process for extruding a
polymer by a pump such as a measurable gear-pump in
order to suppress quantitative variation of a falling
recovered polymer.
The number of pores of the porous plate is
not particularly limited and may be varied depending
upon the conditions such as reaction temperature and
pressure, the amount of a catalyst and the molecular
weight range of the polymer to be polymerized.
Generally, when a polymer is produced in an amount of,
for example, 100 kg/hr, 5 to 105 pores are required.
[0021]
The recovered polymer ejected from the pores
of the porous plate must be polymerized under reduced

pressure while dropping it along a support. At this
time, it is preferable that there is a portion where
foams are generated without being burst immediately
upon generation. More specifically, foams are
desirably generated at the place on which the resin
falling along a support is landed. As Examples of such
a support include a wire-form, chain-form or a lattice
(grid)-form made of wire materials in combination, a
cubic lattice-form made of wire material in the shape
of a jungle gym, a flat or curved thin-film, a porous
plate, and a tower formed by stacking regular fillers
or irregular fillers.
[0022]
To efficiently extract a polycondensation
reaction side-product such as EG and also reduce the
content of impurities such as acetaldehyde in a
recycled polymer, it is preferable that the resin drops
have a large surface area. For this reason, the
support preferably has a wire-form, chain-form,
lattice-form or cubic lattice form. To more
efficiently extract a polycondensation reaction side-
product such as EG, thereby increasing a polymerization
rate, and further reduce the content of acetaldehyde in
a recycled polymer, other than increasing the surface
area, it is particularly preferable that a recovered
polymer is dropped along a support having projections
and depressions on the way on which a recovered polymer
falls. This is because the polymer is actively stirred

by the projections and depressions, thereby renewing
the surface of the polymer. For this reason, the
structure of the support is particularly preferably a
chain form, cubic lattice form, and wire form having
projections and depressions, that is, structural
obstacles inhibiting the drop of a resin, on the way on
which a resin falls. As a matter of course, it is one
of the preferable approaches that these supports are
used in combination.
[0023]
The wire form used herein refers to a solid
material having an extremely large ratio of the
sectional area based (calculated from) on an average
length of outer circumference of the section to the
length in perpendicular to the sectional area. The
sectional area is not particularly limited; however
generally ranges from 10~3 to 102 cm2, preferably from
10~2 to 101 cm2, and particularly preferably, 10_1 to 1
cm2. The shape of the section is not particularly
limited; however, generally selected from circular,
ellipsoidal, triangular, square, polygonal, star shape
and others. The shape of the section may or may not
change lengthwise. The wire may be a hollow body.
The wire may be made of a single filament or
a plurality of filaments combined, for example, by
twisting. The surface of the wire may be smooth, rough
and bumpy in part. The material of wire is not
particularly limited; however generally selected from

stainless steel, carbon steel, hastelloy, titanium and
the like. Various surface treatments such as plating,
lining, passive-state processing, and acid washing may
be applied to the wire, if necessary.
[0024]
The lattice (grid) form used herein refers to
a solid material made of wire-like filaments in the
form of a lattice. The wire filaments used in
combination may be straight or curved. The wire
filaments may be mutually crossed at any angle. In a
projection view of the lattice (grid) form material
obtained by vertically projecting light to the lattice
plane, the area ratio of the solid material and the
space is not particularly limited; however generally
falls within the range of 1:0.5 to 1:1,000, preferably
1:1 to 1:500, and particularly preferably, 1:5 to
1:100. The area ratio in the horizontal direction is
preferably equal; however, that of the vertical
direction is preferably equal or preferably the ratio
of the space increases toward the bottom.
[0025]
The chain-form used herein refers to a solid
material formed by sequentially connecting the wire
rings. The shape of the wire ring may be circular,
ellipsoidal, rectangular and square. Wire rings may be
connected one dimensionally, two-dimensionally, and
three-dimensionally.
The cubic lattice form used herein refers to

a solid material having a three-dimensional lattice
form, such as a jungle gym, formed of wire-like
filaments. The wire filaments may be straight or
curved and mutually crossed at any angle.
[0026]
The "wire form having projections and
depression on the way on which resin falls" refers to a
wire filament having rods having a circular or
polygonal sectional shape attached in perpendicular to
the wire filament or a wire filament having disk-form
or circular form solid materials attached thereto. The
difference between projections and depressions is
preferably 5 mm or more. Specific examples of such a
wire include a wire filament having disks attached at
intervals of 1 to 500 mm such that the wire filament
passes through the center of the disks each of which
has a diameter larger by 5 mm than that of the wire
filament and less than or equal to 100 mm and a
thickness of 1 to 50 mm.
[0027]
In a chain-form support, a cubic lattice form
support and a wire form support having projections and
depressions formed in a perpendicular direction to the
way on and along which the polymer drops, the volume
ratio of the solid portion and space of the support to
be combined is not particularly limited; however,
generally falls within the range of 1:0.5 to 1:107,
preferably 1:10 to 1:106, and particularly preferably

1:102 to 1:105. The volume ratio in the horizontal
direction is preferably equal, whereas the volume ratio
in the vertical direction is preferably equal or the
ratio of the space increases toward the bottom.
The number of supports, whether or not a
single or plural, may be appropriately chosen depending
upon the shape of the support. In the cases of a wire
form and linearly extending chain form, the number of
supports generally ranges from 1 to 100,000, and
preferably 3 to 10000. In the case of lattice form, a
two-dimensional structure such as a two dimensional
chain-form, thin-film form, and porous plate form, the
number of supports generally ranges from 1 to 1,000,
and preferably 2 to 100. In the case of a three-
dimensional structure such as a three-dimensional chain
form, cubic lattice form, and a filler tower, the
number of supports may be single or plural. In this
case, whether a single support or a plurality of
supports (by splitting) are used can be appropriately
determined in consideration of the size of an apparatus
and installation space, etc.
In the case of a plurality of supports, the
supports are preferably arranged with an appropriate
spacer interposed between them to avoid mutual contact
of supports.
[0028]
In the present invention, a recovered polymer
is generally supplied from at least one pore of the

porous plate to a single support. The number of pores
can be appropriately selected depending upon the shape
of the support. Alternatively, a recovered polymer
passed through a single pore can be dropped along a
plurality of supports. However, to obtain a resin
having uniform quality by rendering the dropping
conditions uniform, the number of supports along which
the resin is dropped is preferably as small as
possible. For this reason, most preferably, a
recovered polymer is supplied from a single pore to a
single support along which the resin (polymer) drops.
The position of a support is not particularly
limited as long as a recovered polymer can drop along
the support. The method of fitting a support to a
porous plate is appropriately selected from the two
cases: one is where a support is arranged to thread
through a pore of the porous plate. The other is where
a support is not arranged to thread through a pore but
arranged to below a pore of the porous plate.
The recovered polymer passed through a pore
can be dropped along a support. The falling of the
polymer may start from a height ranging from preferably
0.5 to 50 m, further preferably, 1 to 20 m and more
preferably, 2 to 10 m.
[0029]
The flow rate of a recovered polymer to be
passed through a pore is preferably 10-2 to 102 L/hr per
pore, and particularly preferably, 0.1 to 50 L/hr. If

the flow rate falls within the range, the cases where
the polymerization rate and productivity significantly
decrease are successfully avoided.
The average time required until completion of
dropping of a recovered polymer along a support
preferably falls within the range of 10 seconds to 100
hours, more preferably 1 minute to 10 hours, further
preferably 5 minutes to 5 hours, and particularly
preferably 20 minutes to 3 hours.
[0030]
In the present invention, it is necessary to
perform polymerization under reduced pressure while a
recovered polymer is dropped along a support. This is
because a polycondensation reaction side-product such
as EG generated with the progress of the reaction is
efficiently removed from the reaction system, thereby
facilitating polymerization. The reduced pressure used
herein refers to a pressure lower than the atmospheric
pressure. Generally, the reduced pressure is
preferably 50,000 Pa or less, more preferably 10,000 Pa
or less, further preferably 1,000 Pa or less, and
particularly preferably, 100 Pa or less. The lowermost
limit is not particularly limited; however, desirably
0.1 Pa or more, in consideration of the size (capacity)
of an apparatus for use in reducing the pressure of the
system.
Alternatively, as one of the preferably
approaches, a small amount of inert gas having no

adverse effect upon the reaction may be introduced to
remove EG and volatile substances, such as
acetaldehyde, generated in the system, by carrying them
on the inert gas under reduced pressure.
[0031]
The recovered polymer for use in the process
for recycling a polymer according to the present
invention may be a mixture of resins having different
polymerization degrees in some cases. When the
polymerization degree of the starting recovered polymer
mixture is extremely one-sided, if the polymerization
of the recovered polymers is continued in predetermined
constant conditions, the polymerization degree of the
resultant recycled product may vary depending upon the
polymerization degrees of the starting recovered
polymers. For this reason, to obtain a resin having
uniform quality, it is preferable to change
polymerization conditions employed for a polymerization
vessel depending upon the polymerization degree of the
starting material to be introduced into the
polymerization vessel.
The polymerization conditions having an
effect upon the polymerization degree of a recycled
product include polymerization temperature, the
reduction degree of pressure, and the feed rate of a
recovered polycondensation polymer to a polymerization
vessel. Of them, the reduction degree of pressure can
be most preferably varied depending upon the introduced

resin.
The polymerization degree of a molten resin
to be supplied is desirably evaluated based on the melt
viscosity thereof immediately upstream of a
polymerization vessel. The melt viscosity is most
preferably evaluated based on the voltage of a gear
pump for feeding the resin in a molten state.
Alternatively, a viscometer may be preferably installed
immediately upstream of the polymerization vessel. It
is desirable to control the reduction degree of
pressure of a polymerization system to change it
quickly depending upon the viscosity thus measured.
[0032]
Furthermore, polymerization is preferably '.
performed in an inert gas atmosphere under reduced
pressure.
It has been conventionally considered that
introduction of an inert gas into a polymerization
vessel is performed to advantageously facilitate a
polymerization reaction by reducing the partial
pressure of a side-product generated during a
polycondensation reaction, thereby shifting the
equilibrium. However, since the amount of the inert
gas to be introduced in the present invention may be
extremely small, the effect of improving a
polymerization rate due to the reduction of partial
pressure is rarely expected. Therefore, conventional
interpretation cannot fit for explaining the role of

such an inert gas. Based on investigation, the present
inventors surprisingly found, by observation, that the
foaming phenomenon of a molten polymer on the support
vigorously takes place by introduction of an inert gas
into a polymerization vessel, dramatically increasing
the surface area of the molten polymer and extremely
improving the surface renewal state. Based on an
unknown theory, it is estimated that the change of the
inner state and surface state of the molten resin is a
cause increasing a polymerization rate.
[0033]
As an inert gas to be introduced, mention may
be made of a gas having no effect upon a resin, such as
coloration, degradation and decomposition. Preferable
examples of such an inert gas include nitrogen, argon,
helium, carbon dioxide and lower hydrocarbon gas, of
course, including a gas mixture thereof. As an inert
gas, nitrogen, argon, helium or carbon dioxide is more
preferable. Of them, nitrogen is particularly
preferable in view of availability.
The amount of an inert gas to be introduced
in the present invention may be extremely small, and
preferably fall within the range of 0.05 to 100 mg per
gram of a resin taken from a polymerization vessel.
When the amount of an inert gas is 0.05 mg or more per
gram of a resin taken from a polymerization vessel, a
sufficient foaming state can be obtained. As a result,
a polymerization degree effectively increases. On the

other hand, when the amount is 100 mg or less, the
reduction degree of pressure can be more easily
increased. The amount of an inert gas is more
preferable set at 0.1 to 50 mg and particularly
preferably 0.2 to 10 mg per gram of a resin taken from
a polymerization vessel.
[0034]
Examples of a process for introducing an
inert gas include a process for directly introducing it
into a polymerization vessel; a process for absorbing
and/or incorporating an inert gas into a recovered
polycondensation polymer in advance and then allowing
the inert gas absorbed and/or incorporated to release
from the recovered polycondensation polymer under
reduced pressure, thereby introducing it into a
polymerization vessel; and a process using these
processes in combination.
Note that, the "absorbed" used herein refers
to a state in which an inert gas is dissolved in a
resin and not present in a gaseous state, whereas the
"incorporated" used herein refers to a state of an
inert gas present in the form of air bubbles. When an
inert gas is present in the form of air bubbles, the
smaller the air bubbles, the more preferable. More
specifically, air bubbles preferably have an average
size of 5 mm or less and more preferably 2 mm or less.
The site of a polymerization vessel through
which an inert gas is directly introduced is desirably

away from a porous plate and near a port from which a
resin is taken out. Furthermore, it is desirable that
the site is away from an exhausting line for a reduced
pressure.
[0035]
On the other hand, as a process for absorbing
and/or incorporating an inert gas into a recovered
polycondensation polymer in advance, mention may be
made of a process using a known absorption apparatus
such as a filler-tower form absorption apparatus,
stacked-stage form absorption apparatus, and spray
tower absorption apparatus, as is described in for
example "chemical apparatus design/operation series"
No. 2, revised, gas absorption, pages 49-54, (published
by Kagaku Kogyosha Inc. on March 15, 1981); and a
process for introducing an inert gas under pressure
into a feed pipe for a recovered polycondensation
polymer in a molten state.
What is the most preferable is a process
using an apparatus for absorbing an inert gas into a
recovered polycondensation polymer melted under an
inert gas atmosphere while the molten polymer is
dropped along a support. In this process, an inert gas
having a higher pressure than the inner pressure of a
polymerization vessel is introduced into an apparatus
for adsorbing the inert gas. The pressure of an inert
gas is preferably 0.01 to 1 MPa, more preferably 0.05
to 0.5 MPa, and further preferably 0.1 to 0.2 Pa.

In either case, it is preferable that there
is a portion at which foaming takes place when a resin
is dropped along a support. More specifically, foams
are desirably generated at the place on which the
polymer (resin) falling along a support is landed. The
state of foaming used herein refers to both states
where bubbles burst and immediately disappear and where
bubbles are maintained.
[0036]
The temperature for polymerizing a recovered
polycondensation polymer while dropping along a support
ranges from "the crystal melting point of the
polycondensation polymer - 10°C" to "the crystal melting
point + 60°C". In the case where PET resin is used as
the recovered polycondensation polymer, the temperature
ranges more preferably from "the crystal melting point
- 5°C" to "the crystal melting point + 40°C", further
preferably, "the crystal melting point + 1°C" to "the
crystal melting point + 30°C". When the temperature is
"the crystal melting point - 10°C" or more, the resin
can easily and stably fall without significantly
increasing the viscosity of the resin or solidifying on
the way on which the resin falls. On the other hand,
when the temperature is "the crystal melting point +
60°C" or less, a recycled product having high quality
can be easily obtained while suppressing coloration due
to heat decomposition. The temperature of a resin in
dropping, preferably falls within the range mentioned

above and differs within 20°C from the temperature of
the resin (polymer) ejected from a porous plate. The
difference is more preferably within 10°C, particularly
preferably within 5°C, and most preferably zero,
indicating the same temperature as the ejection
temperature. Such a temperature can be attained by
accurately controlling the temperature of a heater or
jacket arranged on the wall of a polymerization vessel
covering a support and/or a heater or a hot medium
added to the interior of a support.
[0037]
In the present invention, mention may be made
of a process comprising supplying a recovered
polycondensation polymer continuously, in a molten
state, from a raw material supply port to a
polymerization vessel, performing polymerization while
dropping the molten polymer ejected from pores of a
porous plate along a support, and taking out the whole
amount of the resin landed continuously from the
polymerization vessel; and a process comprising
circulating part of the landed polymer and returning
again to a step of polymerizing the resin while
dropping the resin along the support. Of them, the
process comprising the step of taking out the whole
amount of resin landed is rather preferable. In the
process comprising a step of circulating the landed
resin and back again to a step of polymerizing the
resin while dropping the resin along the support, heat

decomposition must be avoid in a liquid storage portion
for storing the landed resin and a circulation line.
Therefore, the time and temperature of the resin
retaining in these places are preferably reduced.
[0038]
The number average molecular weight of a
recycled product improved in polymerization degree and
produced from a recovered polycondensation polymer by a
recycling method according to the present invention is
preferably 20,000 or more in view of mechanical
properties of a molded body formed from the recycled
product, preferably 100,000 or less in view of
processability in molding, particularly preferably
22,000 to 50,000, and more particularly 24,000 to
45,000 in view of quality of a recycled product such as
mechanical properties, hue and impurity content.
Furthermore, difference in polymerization
degree of resin products is preferably small.
In a starting material for forming a molded
article having stable quality, a value of Mw/Mn of the
resin mixture, which is prepared by taking the same
amount of 10 samples from one lot of products at
random, is preferably 2.6 or less, further preferably
2.4 or less, and most preferably 2.2 or less.
[0039]
A recovered polycondensation polymer
increased in polymerization degree can be used directly
in a molten state or once formed into pellets and then

melted again for use in molding.
In the case of pellets, the pellets are
desirably formed with a slight loss and extruded
uniformly by an extruder. To obtain such pellets, the
molten polymer taken out from a polymerization vessel
is preferably extruded in strand form or sheet form,
placed into a cool medium such as water to cool, and
thereafter cut into pellets. The temperature of the
cool medium is preferably 60°C or less, more preferably
50°C or less, and further preferably 40°C or less. As a
cool medium, water is preferably in view of economy and
handling convenience. From this, the temperature of
the cool medium is 0°C or more. Cutting of the resin
into pellets is preferably performed within 120 seconds
after the resin is extruded and after the temperature
is cooled to 100°C or less.
[0040]
A recycling process by a molten
polymerization process according to the present
invention is advantageous over a process for recycling
a recovered polymer by increasing polymerization degree
by solid phase polymerization. This is because not
only a step of forming pellets from a recovered
polycondensation polymer is omitted but also time and
energy required for polymerization can be reduced.
Furthermore, a recycled product has numerous advantages
over the one obtained by the solid phase polymerization
process. For example, the amounts of contaminants such

as unfused substances during a modeling step and fine
powder called fisheye causing a molding failure, are
low. The obtained pellets have a low degree of
crystallinity compared to those recycled by the solid
phase polymerization process, so that the deterioration
of polymerization degree due to heat generation caused
by shearing during a molding step and the amount of
heat decomposition product such as acetaldehyde are
low. On the other hand, it is extremely difficult to
increase the polymerization degree of the recovered
polycondensation polymer and quality such as hue of the
polymer decreases in the conventional molten
polymerization technique. Therefore, it has been
difficult to produce a recycled polymer excellent in
quality like in the present invention.
[0041]
A recycled polymer increased in
polymerization degree by a polymerization process
according to the present invention is used for molding.
At this time, it is important to perform molding while
suppressing a decrease of polymerization, coloration
due to heat decomposition, and generation of volatile
low molecular weight impurities. To attain this, it is
preferable that a recycled polymer is transferred in a
molten state from a polymerization vessel to a molding
machine without solidifying and then subjected to melt
molding. The "molten state" refers to a melt and
flowable state of a resin attained by heat application.

At this state, the viscosity of the resin is
approximately 500,000 Pa-s or less.
[0042]
In the present invention, a recycled polymer
excellent in quality can be manufactured by the
polymerization process mentioned above. In addition, a
high-quality molded article, which is an object of the
present invention, can be manufactured with high
productivity by molding the recycled polymer while
maintaining the excellent equality without solidifying.
Combination of a recycling process by a melt-
polymerization process according to the present
invention with a process for molding a recycled polymer
without solidifying at any moment is advantageous over
a process of recycling a polymer increased in
polymerization degree by a solid-phase polymerization
process, since not only a step of palletizing a
recycled product can be omitted, but also time and
energy required for polymerization can be reduced. In
addition, a step of drying pellets before molding and a
step of melting the pellets again for molding are not
required. As a result, energy can be saved and
decomposition of a resin can be prevented.
[0043]
When the temperature during transferring and
molding of a resin is not less than a crystal melting
temperature - 10°C, a resin can be easily and stably
transferred and molded without a significant increase

of viscosity and solidification. On the other hand,
when the upper limit of the temperature is a
temperature higher by 60°C than a crystal melting
temperature, it is easy to obtain a high quality PET
molding product while suppressing coloration due to
heat decomposition and generation of low molecular
weight volatile impurity. The temperature is
preferable higher by 1 to 40°C, more preferably higher
by 5 to 30°C, and particularly preferably higher by 10
to 20°C than the crystal melting point of a recycle
polymer. Such a temperature can be attained by
appropriately controlling the temperature of a heater
or jacket covering a transfer pipe, a transfer pump,
and a molding machine.
Furthermore, the time is preferably within 40
minutes, more preferably within 20 minutes, and
particularly preferable within 10 minutes. The shorter
the time, the more preferable. Note that, the "time"
used herein refers to a period from discharge of a
molten resin from the discharge pump of a
polymerization vessel to cooling of the molten resin to
a crystal melting temperature of the resin or less in a
molding machine or outside the molding machine. When a
resin is continuously circulated through a pipe or the
like, an average time calculated from the volume of a
pipe and the flow rate of the resin can be employed.
In the case where the time changes, the operation can
be performed within the aforementioned time.

[0044]
The present invention includes the case where
additives such as a stabilizing agent, (crystal)
nucleating agent, pigment are added if necessary by a
single screw or double screw kneader placed between a
polymerization vessel and a molding machine in the
conditions of the aforementioned temperature and time.
The present invention includes the case where
various types of additives such as a delustering agent,
thermostabilizer, flame retardant, antistatistic agent,
defoaming agent, color adjuster, antioxidant, UV-ray
absorbing agent, crystal nucleating agent, whitener,
and impurity trapping agent may be copolymerized or
added if necessary. These additives may be added at
any time.
In particular, a stabilizer is preferably
added in the present invention. In the case of a
recovered polycondensation polymer is PET resin, a
penta valent and/or tri valent phosphorus compound and
hindered phenolic compound are preferable. The
addition amount of such a phosphorus compound is
preferably 2 to 50 ppm and more preferably 10 to 200
ppm in terms of a weight ratio of phosphorus element
contained in PET. As an example of such a phosphorus
compound, use may be preferably made of trimethyl
phosphite, phosphate, and phosphorous acid. Such a
phosphorus compound is preferably used since it
suppresses coloration of PET resin and has the effect

of a crystal-nucleating agent.
[0045]
The hindered phenolic compound is a phenolic
derivative having a sterically hindered substituent at
a position in the vicinity of a phenolic hydroxide
group, in other words, a compound having one or more
intramolecular ester bonds. The addition amount of
such a hindered phenolic compound is preferably 0.001
to 1 % by weight, and more preferably, 0.01 to 0.2 % by
weight relative to the PET resin obtained.
Examples of such a hindered phenolic compound
include pentaerythritol tetrakis (3-(3,5-di-tert-butyl-
4-hydroxyphenyl)propionate), 1,1,3-tris(2-methyl-4-
hydroxy-5-tert-butylphenyl)butane, Octadecyl-3-(3,5-di-
tert-butyl-4-hydroxyphenyl)propionate, and N,N-
hexamethylene bis(3,5-tert-butyl-4-
hydroxyhydrocinamide). As a matter of course, a
stabilizer for these compounds may be preferably used.
The stabilizer may be added in any stage from
the beginning to a molding step. A phosphorus compound
is preferably added in the beginning of a
polycondensation reaction and a hindered phenolic
compound is added in the beginning of a
polycondensation reaction or after a polymerized resin
is taken out from a polymerization vessel.
[0046]
In the present invention, it is further
preferable to add a crystal-nucleating agent. As an

example of such a nucleating agent, use may be
preferably made of a phosphorus compound, an organic
acid metal salt, and a powder of a resin such as PET
and others. The addition amount of a nucleating agent
to PET is preferably 2 to 1,000 ppm, and more
preferably, 10 to 500 ppm. Specific examples include
phosphates such as sodium 2,2'-methylene bis(4,6-di-t-
butylphenyl)phosphate, and sodium bis (4-t-butylphenyl)
phosphate, sorbitols such as bis(p-
methylbenzylidene)sorbitol, and metal element
containing compounds such as bis(4-t-butyl benzoic
acid)hydroxyl-aluminium. Particularly, in
manufacturing a preform of a bottle formed by thermal
crystallization of the mouth portion with heat, a
crystal-nucleating agent is preferably used since it
accelerates crystallization, thereby reducing the
temperature of thermal crystallization.
[0047]
In one of preferable methods of the present
invention, a trapping agent for low molecular weight
volatile impurities is added. As the trapping agent,
use may be made of a polymer or an oligomer of a
polyamide and polyester amide, a low molecular weight
compound having an amide group and an amine group.
Specific examples include polymers such as polyamides,
for example, nylon 6.6, nylon 6, and nylon 4.6 and
polyethylene imines; a reaction product between N-
phenyl benzene amine and 2,4,4-trimethyl pentene; and

Irganox 1098 and Irganox 565 (registered trademark)
manufactured by Ciba Speciality Chemicals Inc. These
trapping agents are preferably added in the stage where
a resin is taken out from a polymerization vessel and
transferred to a molding machine.
When a resin taken from a polymerization
vessel is transferred to a molding machine through a
pipe, heating the pipe by a heater or jacket and
maintaining the pipe warm are preferable in view of
transferring a molten resin. The temperature for
heating and maintaining the pipe is preferable 230 to
300°C and further preferably 240 to 280°C.
[0048]
Next, a preferable polymerization vessel used
in the present invention will be exemplified and
explained with reference to the accompany drawings.
Fig. 1 shows a polymerization vessel for
carrying out a method according to the present
invention. A recovered polycondensation polymer R such
as PET resin is fed in a molten state from a raw
material supply port 3 into a polymerization vessel 1
by way of a transfer pump 2, introduced into the
interior of the polymerization vessel through a porous
plate 4 and falls along a support 6 (a falling resin is
also shown). A viscometer is arranged upstream of the
raw material supply port 3. The interior of the
polymerization vessel is controlled at a reduced
pressure corresponding to the viscosity measured by the

viscometer. A gas such as EG distillated from a
recovered PET resin and an inert gas such as nitrogen
optionally introduced from a gas supply port 7 are
exhausted from an exhausting port 8 for reducing
pressure. The polymer produced is discharged from a
discharge port by a discharge pump 9. The
polymerization vessel 1 is heated and maintained warm
by a heater or a jacket.
[0049]
The interior of the polymerization vessel is
controlled at a predetermined reduced pressure. A gas
such as EG distilled from a recovered PET resin and an
inert gas introduced are discharged from exhausting
port 8 for reducing pressure. The polymer produced is
continuously discharged from the discharge port by the
discharge pump 9, fed through a transfer pipe and a
distributor 10 to injection molding machines A, B, C
(11, 12, 13), in which the polymer is molded. The
transfer pump 2, polymerization vessel 1, discharge
pump 9, transfer pipe and distributor 10 are heated and
maintained warm by the heater or the jacket.
[0050]
Fig. 2 shows a polymerization vessel for
carrying out a method according to the present
invention in the case where an inert gas absorption
apparatus is used. A recovered polycondensation
polymer R such as a recovered PET resin is fed from a
raw material supply port N2 to an inert gas absorption

apparatus N10 via a transfer pump N1, passed through a
porous plate N3, introduced into the interior of the
inert gas absorption apparatus N10, and falls along a
support N5 (a falling resin is also shown). The
interior of the inert gas absorption apparatus is
controlled at a predetermined reduced pressure by an
exhausting port N7 for reducing pressure. The
recovered PET resin absorbs an inert gas such as
nitrogen gas introduced from an inert gas introduction
port N6 while falling, supplied to the polymerization
vessel 1 from the raw material supply port 3 by way of
a discharge/transfer pump N8, and introduced into the
interior of the polymerization vessel through the
porous plate 4 and falls along the support 6 (a falling
resin is also shown). The interior of the
polymerization vessel is controlled at a predetermined
reduced pressure. EG produced as a side-product is
exhausted from the exhausting port 8 for reducing
pressure. The polymer produced is discharged from a
discharge port by the discharge pump 9. The
polymerization vessel 1 is heated and maintained warm
by the heater or the jacket.
A polymer resin is continuously discharged by
the discharge pump 9, fed through a transfer pipe and a
branch switching valve 10 to molding machines A, B, C
(11, 12, 13), in which the polymer is molded. Three or
more molding machines may be connected.
[0051]

In either method, the resin falling along a
support and landing at the lower portion of the
polymerization vessel is discharged from the discharge
port by the discharge pump. At this time, the amount
of the resin accumulated at the lower portion of the
polymerization vessel is preferably as small and
constant as possible. In this manner, the coloration
and decrease in polymerization degree due to heat
decomposition can be suppressed and gualitative
variation of the obtained resin can be easily
suppressed. The accumulation amount of a resin can be
controlled by adjusting a liquid amount fed by the
transfer pump 2 and discharged by the discharge pump 9
by monitoring the accumulation amount through an
observation window 5 or monitoring the accumulation
amount by a level meter of a capacitance type.
The polymerization vessel used in the present
invention may have, but not particularly require, a
stirrer at the bottom. Accordingly, a rotation driving
part may be removed from the polymerization vessel,
with the result that polymerization can be performed in
the airtight conditions under high vacuum. Since the
rotation driving part of the discharge pump is covered
with the resin to be discharged, the polymerization
vessel is significantly excellent in sealing effect
compared to that having a rotation driving part.
The process of the present invention can be
performed in a single polymerization vessel and may be

performed in two or more polymerization vessels.
Furthermore, a single polymerization vessel
is longitudinally or laterally divided into multiple
portions and used as a multiple stage polymerization
vessel.
[0052]
In the present invention, a step of
increasing the molecular weight of a recovered
polycondensation polymer such as a recovered PET resin
so as to acquire a desired high polymerization degree
may be performed exclusively by a polymerization
process while dropping the resin passed through the
pores of a porous plate, along a support; however may
be preferably carried out in combination with other
polymerization processes performed, for example, in a
stirred polymerization vessel and a transverse stirred
polymerization vessel. Furthermore, in the case where
a recovered polycondensation polymer is supplied
together with an unused polycondensation polymer and/or
an intermediate polymer to the polymerization vessel of
the present invention to form a recycle product, the
unused polycondensation polymer and/or the intermediate
polymer may be produced by another polymerization
process using, for example, a stirred polymerization
vessel or a transverse stirred polymerization vessel.
Examples of the transverse stirred
polymerization vessel include polymerization vessels
having a screw, independent vane, single screw, and

double screw, more specifically, a polymerization
vessel described in "Research Report from Research
Group of Reaction Engineering: Reactive processing Part
2", chapter 4. (published by the Society of Polymer
Science, Japan, 1992).
As the stirred polymerization vessel, use may
be made of any one of the stirring vessels described
in, for example Chemical Apparatus Handbook, chapter 11
(edited by the Society of Chemical Engineers, Japan,
1989). The shape of the vessel is not particularly
limited and vertical and transverse cylindrical vessels
may be used in general. The shape of a stirring vane
is not particularly limited and a paddle shape, anchor
shape, turbine shape, screw shape, ribbon shape, and
double vanes may be employed.
[0053]
A step of producing an unused
polycondensation polymer and an intermediate polymer
from a raw material may be performed in a batch system
or a continuous system. In the batch system, the whole
amounts of raw materials and reacting substances are
placed in a reaction vessel. After a reaction is
performed for a predetermined time, the whole amount of
the reaction mixture is transferred to a next reaction
vessel. On the other hand, in the continuous system,
raw materials and reacting substances are continuously
supplied to each of the reaction vessels and a reaction
product is continuously discharged. The continuous

system is preferable to obtain a large amount of a
recycled polymer uniform in quality.
A material for a polymerization vessel used
in the present invention is not particularly limited
* and generally selected from stainless steel, nickel,
and glass lining, etc.
[0054]
A process for transferring a recycled polymer
obtained through polymerization to a molding machine is
not particularly limited; however, generally, a means
such as a gear pump and an extruder is used. The
transfer of the polymer to the molding machine may be
continuously or intermittently performed. In either
case, transfer and molding must be performed within the
predetermined time as mentioned above. In the case of
intermittent transfer, discharge of a polymer from a
polymerization vessel can be intermittently performed.
However, as shown in Fig. 1, a resin is discharged
continuously from a polymerization vessel and
intermittently transferred to two or more molding
machines (three machines in the figure) by sequentially
switching transfer pipes in combination with a
distributor 10 arranged between the polymerization
vessel and the molding machines. Besides these, known
apparatuses such as an apparatus composed of a
reservoir and a piston, and a machine called an
accumulator for temporarily storing a resin may be
preferably arranged.

[0055]
The molding machine used in the present
invention refers to an apparatus for forming a molten
resin into a predetermined shape. Examples of such a
molding machine include an extruder, injection-molding
machine, and blow-molding machine. Examples of a
molded article formed by such a molding machine include
bottles, preforms of bottles, films, sheets, tubes,
rods, fibers and injection molded articles of various
shapes. Of them, the present invention is suitably
applied to form preforms of beverage bottles. This is
because a beverage bottle needs to have excellent
strength and transparency, and, in the case where a
recovered polycondensation polymer is PET, such a
bottle is strongly demanded to be produced with reduced
low molecular weight volatile impurities, which are
represented by acetaldehyde and may have an adverse
effect upon taste and odor of the content of the
bottle, and with high productivity.
[Examples]
[0056]
The present invention will be explained by
way of Examples.
Major measurement values shown in Examples
were determined as follows.

(1) Intrinsic viscosity [η]
Intrinsic viscosity [η] was measured by

Ostwald viscometer. More specifically, intrinsic
viscosity was obtained by extrapolating the ratio of
specific viscosity ηsp (in o-chloro phenol at 35°C) to
concentration C (g/100 mL) , ηsp/C, to concentration of
Zero in accordance with the following equation:
[Formula 1]

(2) Crystal melting point
The crystal melting point was measured by an
input compensation type differential calorimeter (trade
name: Pyris 1 DSC, manufactured by Perkin Elmer Inc.)
in the following conditions. The value of an
endothermic peak derived from melting of a crystal was
specified as a crystal melting point. The peak value
was determined by use of the analysis software attached
thereto.
Measuring temperature: 0 to 300°C
Temperature raising rate: 10°C/min.
(3) The amount of carboxyl group at polymer end
A sample (1 g) was dissolved in 25 ml of
benzyl alcohol. Thereafter, 25 ml of chloroform was
added to the resultant mixture, and subjected to
titration with a solution of 1/50N potassium hydroxide
in benzyl alcohol. The amount of a carboxyl group was
obtained by assigning a titration value VA (ml) and a
value V0 of a blank where no PET is used, to the

following equation:
The amount of carboxyl group (meq/kg) = (VA-
Vo) x 20.
[0057]
(4) Acetaldehyde content (water extraction method)
Samples cut into small pieces was subjected
to frost shattering under cooling by liquid nitrogen in
a 6700 freezer mill (trade name, a frost shattering
machine manufactured by SPEX) for 3 to 10 minutes to
prepare a powder having grain sizes of 850 to 1,000 µm.
The powder (1 g) , was added together with 2 ml of water
to a glass ample tube. After the air of the tube was
replaced with nitrogen, the tube was sealed tight and
heated at 130°C for 90 minutes to extract impurities
such as acetaldehyde. After cooling, the ample tube
was opened and subjected to gas chromatographic
analysis by use of GC-14B (trade name, Gas
Chromatograph) manufactured by Shimadzu Corporation in
the following conditions:
Column: VOCOL (60 m x 0.25 mmΦ x film
thickness 1.5 µm)
Temperature conditions: maintain at 35°C for
10 minutes, increase temperature to 100°C at a rate of
5°C/minute, and thereafter increase to 100 to 220°C at a
rate of 20°C/minute
Temperature of inlet: 220°C
Injection method: Sprit method (sprit ratio =
1:30) , inject 1.5 µl

Measurement method: FID method
(5) Hue (L value, b value) of a resin evaluated in the
form of solution
A sample (1.5 g) was dissolved in 10 g of
1,1,1,3,3,3,-hexafluoro-2-propanol and subjected to
analysis in accordance with the permeability method
using UV-2500PC (trade name, UV ray-visible light
spectrophotometer) manufactured by Shimazu Corporation.
The results were evaluated by use of the analysis
software attached thereto.
[0058]
(6) Molecular weight distribution
To evaluate variation of the polymerization
degree of a resin product with time, a sample was taken
every 30 minutes and dissolved in an eluent,
1,1,1,3,3,3,-hexafluoro-2-propanol (in which 5 mmol of
sodium trifluoro acetate is dissolved) in a
concentration of 1.0 mg/ml to prepare a solution. In
Examples and Comparative Examples below, polymerization
was respectively continuously performed for 5 hours or
more. Of the sample solutions prepared as mentioned
above, 10 solutions were arbitrarily chosen and mixed
to prepare a solution mixture, which was subjected to
analysis using IILC-8020GPC (Gel permeation
chromatography) manufactured by Tosoh Corporation in
the following conditions. The analysis results were
evaluated by use of the analysis software attached
thereto.

Column: HFIP-606M + HFIP-603 manufactured by
Shodex
Column temperature: 40°C
Injection amount: 30 µl
Measurement method: RI detector, PMMA
conversion

In Examples, molding was performed as
follows.
Molding machine: SBIII-100H-15, double screw
stretch bottle molding machine manufactured by Aoki
Technical Laboratory, Inc.
Temperature of cylinder: 280°C
Temperature of hot runner nozzle: 290°C
Injection pressure: 140 kg/cm2
Temperature of mold: water cool
Weight of preform: 24 g
Content of bottle: 500 mL

A bottle molded article made of PET was
washed, shattered by a shattering machine, and dried by
a hot-air dryer at 120°C for 12 hours. The shattered
material was then transferred to a vacuum dryer,
replaced with nitrogen, and crystallized at 180°C for 6
hours.
vessel>
A single screw extruder was attached to an

inlet for recovered PET of the polymerization vessel
shown in Fig. 1 so as to introduce the molten resin
extruded from the extruder into the polymerization
vessel by way of a pipe.
[0059]
(Example 1)
Used bottles were recovered, washed and
shattered. A molten resin of the shattered bottles
having an intrinsic viscosity [η] of 0.65 dl/g and a
crystal melting point of 255°C was supplied to the
polymerization vessel 1 from the raw material supply
port 3 by the extruder. The molten resin while
maintaining the molten state at 260°C was ejected from
the pores of the porous plate 4 at a rate of 20g/minute
per pore. The resultant resin was polymerized under
reduced pressure of 105 Pa while dropping the resin
along the support 6 in the atmosphere whose temperature
was adjusted equal to the ejection temperature.
Thereafter, the resin was discharged by the discharge
pump 9, fed through the transport pipe and the
distributor 10, to a double screw stretch blow molding
machine. As a result, a hollow product was obtained.
The porous plate used herein had a thickness of 50 mm
and 1 mm-diameter pores linearly arranged at 25 mm
intervals in 4 lines. The support 6 was a metal grid
prepared by attaching wire filaments (2 mm in diameter
and 8 m in length) each to a portion of the porous
plate in a close proximity of each pore so as to

vertically hang down, and then arranging wire filaments
(2 mm in diameter and 100 mm in length) at 15 mm
intervals so as to cross with the wire filaments
mentioned above at right angles. As the material of
the support 6, stainless steel was used. The discharge
pump 9 was operated while monitoring the resin through
the observation window 5 so as to accumulate little or
nothing of the resin on the bottom of the
polymerization vessel. The retaining time of the resin
in this case was 60 minutes. Note that the retaining
time was calculated by dividing the amount of the resin
present inside the polymerization vessel by the supply
amount of the resin. In this Example, as a molding
machine, a double screw stretch blow-molding machine
manufactured by AOKI Technical Laboratory, Inc. was
used alone without other molding machines and the resin
was discharged. A preform formation step to a hollow
product formation step were continuously performed in
the molding conditions: the temperature of a resin:
280°C, the temperature of a mold: 90°C at a core side,
130°C at the upper side near a cavity, 50°C at the lower
side, the injection time: 7 seconds, the cooling time:3
seconds, and the time required for one cycle: 18
seconds. The results are shown in Table 1. A
prepolymer was appropriately foamed in the
polymerization vessel. The obtained molded article
exhibited a high polymerization degree, good color
tone, and a less acetaldehyde content. Hence, a high-

quality hollow product made of PET with a high
polymerization degree was obtained.
[0060]
(Example 2)
Polymerization and molding were performed in
the same manner as in Example 1 except that EG was
introduced at a rate of 5 ml/min from a liquid addition
apparatus of the extruder and the conditions shown in
Table 1 were employed. The results are shown in Table
1. The prepolymer in the polymerization vessel was
appropriately foamed. The obtained molded article
exhibited a high polymerization degree, good color
tone, and a less acetaldehyde content. Hence, a high-
quality hollow product made of PET with a high
polymerization degree was obtained.
(Examples 3 to 5)
Polymerization and molding were performed in
the same manner as in Example 1 except that support
structures shown in Table 2 were employed. The results
are shown in Table 1. The obtained molded article
exhibited a high polymerization degree, good color
tone, and a less acetaldehyde content. Hence, a high-
quality hollow product made of PET with a high
polymerization degree was obtained.
(Example 6)
Polymerization was performed in the same
manner as in Example 1 except that the conditions shown
in Table 1 were employed.

A strand was stretched through water and
palletized by a pelletizer to obtain pellets. The
results were shown in Table 1. The obtained pellets
exhibited a higher polymerization degree than the
recovered product, better color tone, and a less
acetaldehyde content. Hence, a high-quality PET resin
pellets were obtained.
(Examples 7 and 8)
Polymerization and palletizing were performed
in the same manner as in Example 6 except that nitrogen
was introduced as shown in Table 1. The results are
shown in Table 1. In this case, a high-viscosity PET
resin pellets were obtained with good color tone and in
a less acetaldehyde content.
[0061]
(Comparative Example 1)
Bottles were washed, shattered, dried and
crystallized and thereafter, directly subjected to
double screw stretch blow molding. The results are
shown in Table 1. In Comparative Example 1, it was
difficult to mold a bottle since the drawdown of a
preform was significant due to a reduction of molecular
weight.
(Comparative Example 2)
Polymerization and molding were performed in
the same manner as in Example 1 except that transverse
double screw polymerization vessel having a disk-form
stirring vanes was used as a polymerization vessel and

the polymerization was performed at 290°C. Note that
the resin retaining time in the polymerization vessel
was 2 hours. The results are shown in Table 1. It was
difficult to obtain a recycled polymer having a high
polymerization degree. The obtained hollow molded
article was colored yellow and had a large acetaldehyde
content.
(Comparative Examples 3 to 5)
Bottles were washed, shattered and subjected
to polymerization performed in the same manner as in
Example 1 except that the conditions shown in Table 1
were employed. The results are shown in Table 1. In
Comparative Example 3, the molded article was colored
yellow since the polymerization temperature was
excessively high and showed a high acetaldehyde
content. In Comparative Example 4, the resin was
solidified since the polymerization temperature was
excessively low, and thus no polymerization was
performed. In Comparative Example 5, polymerization
failed to proceed and decomposition took place. As a
result, the viscosity of a resin decreased.







INDUSTRIAL APPLICABILITY
[0064]
According to the present invention, it is
possible to increase polymerization degree of a
recovered polycondensation polymer with good
productivity at low cost while maintaining high
quality. Therefore, the present invention can be
suitably applied as a material recycling technique.

WE CLAIM:
1. A process for recycling a recovered polycondensation polymer,
comprising:
supplying the recovered polycondensation polymer in a molten state
to a polymerization vessel having a porous plate, ejecting the polymer,
such as herein described, through pores of the porous plate, and
increasing the polymerization degree of the polycondensation polymer
under reduced pressure or in an inert gas such as herein described
atmosphere under reduced pressure while dropping the polymer along
a support.
2. The process as claimed in claim 1, wherein the recovered
polycondensation polymer is ejected from the pores of the porous
plate together with
(i) an unused polycondensation polymer and an intermediate
polymer, or
(ii) an unused polycondensation polymer, or an intermediate
polymer.

3. The process as claimed in claim 1 or 2, wherein the recovered
polycondensation polymer with an improved polymerization degree
has a number average molecular weight of 20,000 to 100,000.
4. The process as claimed in any one of claims 1 to 3, comprising
continuously measuring the melt viscosity of
(i) the recovered polycondensation polymer or
(ii) a mixture of the recovered polycondensation polymer with the
unused polycondensation polymer or
(iii) a mixture of the recovered polycondensation polymer with the
intermediate polymer, or
(iv) the mixture of the recovered polycondensation polymer with
the unused polycondensation polymer and the intermediate
polymer,
to be supplied to the polymerization vessel, and continuously
adjusting the pressure reduction degree of the polymerization
vessel, based on measurement results of the melt viscosity.

5. The process as claimed in any one of claims 1 to 4, comprising a step
of reacting
(i) the recovered polycondensation polymer or
(ii) the mixture of the recovered polycondensation polymer with the
unused polycondensation polymer or
(iii) the mixture of the recovered polycondensation polymer with the
intermediate polymer, or
(iv) the mixture of the recovered polycondensation polymer with the
unused polycondensation polymer and the intermediate polymer,
with a molecular weight adjuster, prior to supplying the
recovered product or the mixture to the polymerization vessel.
6. The process as claimed in any one of claims 1 to 5, wherein the
recovered polycondensation polymer is a recovered polyethylene
terephthalate resin and ejected from the pores of the porous plate at a
temperature ranging from "a crystal melting temperature -10°C" to
"the crystal melting temperature + 60°C".

7. A process for producing a molded article, characterized by comprising
transferring the polymer recycled by the process as claimed in any one
of claims 1 to 6 to a molding machine in a molten state and molding
the polymer.


A process for recycling a recovered polycondensation polymer, comprising:
supplying the recovered polycondensation polymer in a molten state to a
polymerization vessel having a porous plate, ejecting the polymer, such as
herein described, through pores of the porous plate, and increasing the
polymerization degree of the polycondensation polymer under reduced
pressure or in an inert gas such as herein described atmosphere under
reduced pressure while dropping the polymer along a support.

Documents:

01491-kolnp-2007-abstract.pdf

01491-kolnp-2007-claims.pdf

01491-kolnp-2007-correspondence others 1.1.pdf

01491-kolnp-2007-correspondence others 1.2.pdf

01491-kolnp-2007-correspondence others 1.3.pdf

01491-kolnp-2007-correspondence others 1.4.pdf

01491-kolnp-2007-correspondence others.pdf

01491-kolnp-2007-description complete.pdf

01491-kolnp-2007-drawings.pdf

01491-kolnp-2007-form 1.pdf

01491-kolnp-2007-form 18.pdf

01491-kolnp-2007-form 2.pdf

01491-kolnp-2007-form 3.pdf

01491-kolnp-2007-form 5.pdf

01491-kolnp-2007-internation publication.pdf

01491-kolnp-2007-international search report.pdf

01491-kolnp-2007-priority document 1.1.pdf

01491-kolnp-2007-priority document 1.2.pdf

01491-kolnp-2007-priority document.pdf

1491-kolnp-2007-abstract-1.1.pdf

1491-KOLNP-2007-ABSTRACT.pdf

1491-kolnp-2007-amanded pages of specification.pdf

1491-KOLNP-2007-CANCELLED PAGES.pdf

1491-kolnp-2007-claims.-1.1.pdf

1491-KOLNP-2007-CLAIMS.pdf

1491-kolnp-2007-correspondence.pdf

1491-kolnp-2007-description (complete).-1.1.pdf

1491-KOLNP-2007-DESCRIPTION (COMPLETE).pdf

1491-kolnp-2007-drawings.pdf

1491-kolnp-2007-examination report reply recieved.pdf

1491-kolnp-2007-examination report.pdf

1491-kolnp-2007-form 1.-1.1.pdf

1491-KOLNP-2007-FORM 1.pdf

1491-kolnp-2007-form 18.pdf

1491-kolnp-2007-form 2.-1.1.pdf

1491-KOLNP-2007-FORM 2.pdf

1491-kolnp-2007-form 3.-1.1.pdf

1491-KOLNP-2007-FORM 3.pdf

1491-KOLNP-2007-FORM 5.pdf

1491-KOLNP-2007-FORM-27.pdf

1491-kolnp-2007-gpa.pdf

1491-kolnp-2007-granted-abstract.pdf

1491-kolnp-2007-granted-claims.pdf

1491-kolnp-2007-granted-description (complete).pdf

1491-kolnp-2007-granted-drawings.pdf

1491-kolnp-2007-granted-form 1.1.pdf

1491-kolnp-2007-granted-form 1.pdf

1491-kolnp-2007-granted-form 2.1.pdf

1491-kolnp-2007-granted-form 2.pdf

1491-kolnp-2007-granted-specification.pdf

1491-kolnp-2007-others-1.2.pdf

1491-kolnp-2007-others.-1.1.pdf

1491-KOLNP-2007-OTHERS.pdf

1491-KOLNP-2007-PA.pdf

1491-KOLNP-2007-PCT IPER.pdf

1491-KOLNP-2007-PETITION UNDER RULE 137.pdf

1491-kolnp-2007-reply to examination report-1.1.pdf

1491-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

1491-kolnp-2007-translated copy of priority document.pdf


Patent Number 248561
Indian Patent Application Number 1491/KOLNP/2007
PG Journal Number 30/2011
Publication Date 29-Jul-2011
Grant Date 25-Jul-2011
Date of Filing 26-Apr-2007
Name of Patentee ASAHI KASEI CHEMICALS CORPORATION
Applicant Address 1-2, YURAKU-CHO 1-CHOME, CHIYODA-KU, TOKYO
Inventors:
# Inventor's Name Inventor's Address
1 YOKOYAMA, HIROSHI C/O. ASAHI KASEI KABUSHIKI KAISHA 1-2, YURAKU-CHO,1-CHOME, CHIYODA-KU, TOKYO, 100-8440
2 SOMEYA KEN C/O. ASAHI KASEI KABUSHIKI KAISHA 1-2, YURAKU-CHO,1-CHOME, CHIYODA-KU, TOKYO, 100-8440
3 AMINAKA, MUNEAKI C/O. ASAHI KASEI KABUSHIKI KAISHA 1-2, YURAKU-CHO,1-CHOME, CHIYODA-KU, TOKYO, 100-8440
PCT International Classification Number C08G 85/00 , C08G 63/88
PCT International Application Number PCT/JP2005/023275
PCT International Filing date 2005-12-19
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2004-369397 2004-12-21 Japan
2 2005-235816 2005-08-16 Japan