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| United States Patent |
6,020,454
|
|
Aoyama
, et al.
|
February 1, 2000
|
Polyester polymerization catalyst, a production method thereof, and a
polyester production method using said catalyst
Abstract
The present invention relates to a polyester polymerization catalyst,
comprising a solution containing an aluminum compound and an alkali
compound, with water or an organic solvent or a mixture consisting of
water and an organic solvent as the medium, a production method thereof,
and a polyester production method, in which the product obtained by the
esterification reaction or ester interchange reaction between an aromatic
dicarboxylic acid or any of its ester forming derivative and a diol is
polycondensed, to produce a polyester, comprising the use of said
polymerization catalyst containing an aluminum compound.
The present invention can provide a polyester excellent in processability
and can overcome such problems as spinneret contamination, filtration
pressure rise, filament breaking, film breaking and foreign matter
production in the production process of products such as fibers, films,
resins and bottles.
| Inventors:
|
Aoyama; Masatoshi (Shizuoka, JP);
Tsutsumi; Kenichi (Shizuoka, JP);
Uchida; Minoru (Shizuoka, JP)
|
| Assignee:
|
Toray Industries, Inc. (JP)
|
| Appl. No.:
|
180557 |
| Filed:
|
November 6, 1998 |
| PCT Filed:
|
March 24, 1998
|
| PCT NO:
|
PCT/JP98/01275
|
| 371 Date:
|
November 6, 1998
|
| 102(e) Date:
|
November 6, 1998
|
| PCT PUB.NO.:
|
WO98/42769 |
| PCT PUB. Date:
|
October 1, 1998 |
Foreign Application Priority Data
| Mar 25, 1997[JP] | 9-071870 |
| Jun 04, 1997[JP] | 9-146781 |
| Intern'l Class: |
C08G 063/78; B01J 031/00 |
| Field of Search: |
528/272,274,279,280,282,308,308.6
524/714,724,767,777
502/102,111,117,132,164,170,172
|
References Cited
U.S. Patent Documents
| 3528945 | Sep., 1970 | Stewart et al. | 528/282.
|
| 3528946 | Sep., 1970 | Stewart et al. | 528/282.
|
| 3533973 | Oct., 1970 | Stewart et al. | 528/277.
|
| 4565845 | Jan., 1986 | Inoue et al. | 525/25.
|
| 5391700 | Feb., 1995 | Itoh et al. | 528/297.
|
| 5512340 | Apr., 1996 | Goodley | 428/35.
|
| 5596069 | Jan., 1997 | Goodley | 528/280.
|
| 5693786 | Dec., 1997 | Tanaka et al. | 536/107.
|
| 5719214 | Feb., 1998 | Tanaka et al. | 524/47.
|
Primary Examiner: Acquah; Samuel A.
Attorney, Agent or Firm: Miller; Austin R.
Claims
We claim:
1. A polyester polymerization catalyst, comprising a solution containing an
aluminum compound and an alkali compound, with water or an organic solvent
or a mixture consisting of water and an organic solvent as the medium.
2. A polyester polymerization catalyst, according to claim 1, wherein the
aluminum compound is contained by 0.05 to 20 wt % as aluminum atoms and
the alkali compound is contained by 0.5 to 30 wt %.
3. A polyester polymerization catalyst, according to claim 1 or 2, wherein
the aluminum compound is an aluminum organic compound represented by the
following general formula:
Al[OR.sub.1 ].sub.l [OR.sub.2 ].sub.m [OR.sub.3 ].sub.n [R.sub.4 ].sub.o(
1)
(where R.sub.1, R.sub.2 and R.sub.3 stand for, respectively independently,
an alkyl group, aryl group, acyl group or hydrogen atom, R.sub.4 stands
for an alkyl acetoacetate ion or acetylacetone ion, R.sub.1, R.sub.2 and
R.sub.3 are identical or different, subject to the condition that at least
one of and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 does not stand for a
hydrogen atom; and l, m, n and o stand for, respectively independently, 0
or a positive number, subject to l+m+n+o=3).
4. A polyester polymerization catalyst, according to claim 3, wherein the
aluminum organic compound is at least one selected from a group consisting
of aluminum alcholates and aluminum carboxylates.
5. A polyester polymerization catalyst, according to claim 1 or 2, wherein
the aluminum compound is at least one compound selected from a group
consisting of hydroxides, chlorides and hydroxychlorides of aluminum.
6. A polyester polymerization catalyst, according claim 1, wherein the
alkali compound is a nitrogen-containing compound.
7. A polyester polymerization catalyst, according to claim 6, wherein the
nitrogen-containing compound is a tertiary amine compound or a quaternary
ammonium compound.
8. A method for producing a polyester polymerization catalyst stated in any
one of claims 1 through 7, comprising the steps of letting water or an
organic solvent or a mixture consisting of water and an organic solvent
contain an alkali compound, and adding an aluminum compound to the
mixture.
9. A method for producing a polyester, in which a product obtained by the
esterification reaction or ester interchange reaction between an aromatic
dicarboxylic acid or any of its ester forming derivatives and a diol is
polycondensed to produce a polyester, comprising the step of using the
polymerization catalyst stated claim 1, wherein said amount of the
aluminum compound is 5 to 500 ppm as aluminum atoms based on the amount of
the obtained polyester.
10. A method for producing a polyester, according to claim 9, wherein the
alkali compound is added by 50 to 5000 ppm based on the amount of the
obtained polyester.
11. A method for producing a polyester, according to claim 9 or 10, wherein
the molar ratio of the reaction system at the moment when the aluminum
compound is added (the molar ratio of an aromatic dicarboxylic acid or any
of its ester forming derivatives to a diol) is 1.25 to 2.0.
12. A method for producing a polyester, according to claim 9, wherein the
diol is added by 0.1 to 1.5 times the amount of the aromatic carboxylic
acid or any of its ester forming derivatives, before the aluminum compound
is added.
13. A method for producing a polyester, according to claim 9, wherein a
cobalt compound is added to ensure that the molar ratio of aluminum atoms
to cobalt atoms (Al/Co) is 0.5 to 20.
14. A method for producing a polyester, according to claim 9, wherein a
titanium compound is added by an amount smaller than the amount of
aluminum atoms added, to ensure that the amount of titanium atoms is 50
ppm or less based the amount of the polyester.
15. A method for producing a polyester, according to claim 9, wherein an
antimony compound is added by an amount smaller than the amount of
aluminum atoms added, to ensure that the amount of antimony atoms is 50
ppm or less based on the amount of the polyester.
Description
A polyester polymerization catalyst, a production method thereof, and a
polyester production method using said catalyst
TECHNICAL FIELD
The present invention relates to a polyester polymerization catalyst, a
production method thereof, and a polyester production method using said
catalyst. In more detail, the present invention relates to an polyester
polymerization catalyst for producing a polyester excellent in
pocesssability and color tone, a production method thereof, and a
polyester production method using said catalyst.
BACKGROUND ART
Polyesters are used widely in various fields for fibers, films, resins and
bottles because of their excellent properties. Among them, polyethylene
terephthalate is favorably used since it is excellent in mechanical
strength, chemical properties, dimensional stability, etc.
In general, polyethylene terephthalate is produced from terephthalic acid
or any of its ester forming derivatives and ethylene glycol. In this case,
in commercial processes for producing high molecular polymers, antimony
compounds are widely used as polycondensation catalysts. However, polymers
containing any antimony compound have the following several unpreferable
properties.
For example, when a polyester obtained by using an antimony catalyst is
melt-spun into fibers, it is known that the residue of the antimony
catalyst is deposited around the holes of a spinneret. The reason why the
residue of the antimony catalyst is deposited is considered to be that
antimony exists as antimony glycolate in the polymer and that it is
modified near the spinneret, and partially vaporized and dissipated, while
a component mainly composed of antimony remains at the spinneret. If the
deposit grows, it causes filament breaking, etc. and must be removed from
time to time.
Furthermore, the antimony catalyst residue in the polymer is likely to be
relatively large grains, and acts as a foreign matter, causing such
unpreferable phenomena as filtration pressure rise at the time of
processing, filament breaking at the time of spinning, and film breaking
at the time of film formation.
Because of the above problems, a polyester having very small or zero in
antimony content is being demanded.
To solve the problems, U.S. Pat. No. 5,512,340 and U.S. Pat. No. 5,596,069
propose to use an aluminum compound such as aluminum chloride or aluminum
hydroxychloride and a cobalt compound together. However, in general, an
aluminum compound has such problems that it is unlikely to be dissolved in
a glycol such as ethylene glycol and the polyester reaction system, and if
it is added to the polyester reaction system as a polycondensation
catalyst, an insoluble foreign matter is formed to cause filament breaking
at the time of spinning and film breaking. After all, the problems of
antimony cannot be sufficiently avoided.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a polyester
polymerization catalyst for producing a polyester, which overcomes the
disadvantages of the polyester containing said antimony compound and the
disadvantages caused when an aluminum compound is used as a polymerization
catalyst, and also to provide a production method thereof and a polyester
production method using said catalyst.
The present invention relates to a polyester polymerization catalyst,
comprising a solution containing an aluminum compound and an alkali
compound, with water or an organic solvent or a mixture consisting of
water and an organic solvent as the medium, and also relates to a
production method thereof and a polyester production method using said
catalyst.
THE MOST PREFERRED EMBODIMENTS OF THE INVENTION
The polyester of the present invention is a polymer synthesized from a
dicarboxylic acid or any of its ester forming derivatives and a diol, and
is not especially limited as far as it can be used as such products as
fibers, films and bottles.
The dicarboxylic acids which can be used here include, for example,
dicarboxylic acids such as terephthalic acid, naphthalenedicarboxylic
acid, adipic acid, isophthalic acid, sebacic acid, phthalic acid and
4,4'-diphenyldicarboxylic acid, and their ester forming derivatives such
as dimethyl esters. The diols which can be used here include ethylene
glycol, propylene glycol, butanediol, polyethylene glycol, diethylene
glycol, hexamethylene glycol, cyclohexanedimethanol, neopentyl glycol and
polypropylene glycol.
The polyesters which can be produced from the above include, for example,
polyethylene terephthalate, polytetramethylene terephthalate,
polycyclohexylenedimethylene terephthalate,
polyethylene-2,6-naphthalenedicarboxylate,
polyethylene-1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate and
polypropylene terephthalate. Among them, the present invention is suitable
for the most generally used polyethylene terephthalate or a copolyester
mainly composed of polyethylene terephthalate.
These polyesters can also have another comonomer copolymerized. The
comonomers which can be used here include other dicarboxylic acids such as
adipic acid, isophthalic acid, sebacic acid, phthalic acid and
4,4'-diphenyldicarboxylic acid, and their ester forming derivatives,
dihydroxy compounds such as polyethylene glycol, diethylene glycol,
hexamethylene glycol, neopentyl glycol and polypropylene glycol, other
hydroxycarboxylic acids such as p-(.beta.-hydroxyethoxy)benzoic acid, and
their ester forming derivatives.
The aluminum compound in the present invention is not especially limited.
However, aluminum organic compounds which can be relatively easily
dissolved in a diol such as ethylene glycol used for producing
polyethylene terephthalate, and aluminum compounds which are relatively
high in aluminum atom content and can provide sufficient catalytic
activity with a small amount are preferable.
Examples of the former include the aluminum organic compounds represented
by the following general formula (1):
Al[OR.sub.1 ].sub.l [OR.sub.2 ].sub.m [OR.sub.3 ].sub.n [R.sub.4 ].sub.o(1)
(where R.sub.1, R.sub.2 and R.sub.3 stand for, respectively independently,
an alkyl group, aryl group, acyl group or hydrogen atom, R.sub.4 stands
for an alkyl acetoacetate ion or acetylacetone ion, R.sub.1, R.sub.2 and
R.sub.3 are identical or different, subject to the condition that at least
one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 does not stand for a hydrogen
atom; and l, m, n and o stand for, respectively independently, 0 or a
positive number, subject to l+m+n+o=3.)
Concretely they include carboxylic acid salts such as aluminium acetate,
aluminium benzoate, aluminium lactate, aluminium laurate, aliminium
stearate and aluminum alcholates in which the hydrogen atom of the
hydroxyl group of an alcohol is substituted by aluminum element, such as
aluminum ethylate, aluminum isopropylate, aluminum tri-n-butyrate,
aluminum tri-sec-butyrate, aluminum tri-tert-butyrate and
mono-sec-butoxyaluminum diisopropylate, and aluminum chelates in which the
alkoxy group of an aluminum alcoholate is partially or wholly substituted
by a chelating agent such as an alkyl acetoacetate or acetylacetone, such
as ethyl acetoacetate aluminum diisopropylate, aluminum tris(ethyl
acetate), alkyl acetoacetate aluminum diisopropylate, aluminum
monoacetylacetate bis(ethyl acetoacetate), aluminum tris(acetyl acetate),
aluminum monoisopropoxymonooleoxyethyl acetoacetate and aluminum
acetylacetonate.
Among them, aluminum carboxylates and aluminum alcoholates are especially
preferable.
Examples of the latter include hydroxides, chlorides and hydroxychlorides
of aluminum. Concretely they include aluminum hydroxide, aluminum
chloride, aluminum hydroxychloride, etc. Among them, aluminum hydroxide is
especially preferable since the polymer obtained is good in heat
resistance and color tone since it does not contain any halogen atom. The
aluminum acetate of the present invention can also be generally marketed
so-called basic aluminum acetate.
The alkali compounds which can be used in the present invention refer to
alkali compounds in a wide sense, i.e., the whole of a group consisting of
alkali metal hydroxides, alkaline earth metal hydroxides, and also alkali
metal carbonates, ammonia, amines and their derivatives, for example, as
stated in Dictionary of Physicochemistry (Rikagaku-Jiten in Japanese) (3rd
edition, revised and enlarged, Iwanami Shoten, 1982), etc.
In the present invention, among these alkali compounds, nitrogen-containing
compounds are preferable since the polyester compositions obtained are
especially good in color tone.
Preferable nitrogen-containing compounds of the present invention include,
for example, those represented by the following formulae (2) and (3):
##STR1##
[where R.sub.1, R.sub.2 and R.sub.3 stand for, respectively independently,
a hydrogen atom, alkyl group, aryl group and allyl group.]
##STR2##
[where R.sub.1, R.sub.2, R.sub.3 and R.sub.4 stand for, respectively
independently, a hydrogen atom, alkyl group, aryl group and allyl group.]
Concretely the compounds of formula (2) include ammonia, diethylamine,
trimethylamine, triethylamine, tripropylamine, tributylamine, etc. The
compounds of formula (3) include tetramethylammonium hydroxide,
tetraethylammonium hydroxide, tetrapropylammonium hydroxide,
tetrabutylammonium hydroxide, trimethylbenzylammonium hydroxide, etc.
Other compounds than those represented by the formulae (2) and (3) which
can be used here include derivatives of the compounds represented by the
formulae (2) and (3), ethylenediamine, tetraethylenediamine,
hexamethylenediamine pyridine, quinoline, pyrroline, pyrrolidone,
piperidine, etc.
As the nitrogen-continuing compounds of the present invention, among the
above compounds, tertiary amine compounds and quaternary ammonium
compounds are preferable since the amount of the foreign matter produced
in the polyester composition obtained is especially small. Furthermore,
compounds which are volatilized at 280.degree. C. or lower are preferable
since the amount remaining in the finally obtained polyester composition
is small to improve the color tone of the polyester composition. The
compounds include tertiary amine compounds such as trimethylamine,
triethylamine, tripropylamine and tributylamine, and quaternary ammonium
compounds such as tetramethylammonium hydroxide, tetraethylammonium
hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and
trimethylbenzylammonium hydroxide.
The aluminum compound of the present invention must be mixed with a solvent
containing the alkali compound before it is added to the reaction system
of the polyester. The inventors found that when an aluminum compound
generally likely to form an insoluble foreign matter in the polyester is
used as a polyester polymerization catalyst, if the compound is finely
dispersed in a solvent containing the alkali compound before it is added
to the reaction system, the compound is unlikely to form any insoluble
foreign matter still after it is added to the reaction system. Thus, the
present invention has been completed.
It is especially preferable to mix the alkali compound with water for
making an aqueous solution and then to mix the aluminum compound with the
aqueous solution, since the aluminum compound can be homogeneously
dispersed or dissolved in the aqueous solution, to inhibit the production
of the foreign matter in the polyester. Furthermore, it is preferable to
dilute the aqueous solution containing the aluminum compound by the diol
component of the polyester such as ethylene glycol before the aqueous
solution is added to the reaction system, since the local concentration
due to sudden temperature change is unlikely to occur.
When the aluminum compound is mixed with such a mixture with the alkali
compound contained in water or an organic solvent or a mixture consisting
of water and an organic solvent, it is preferable that the concentration
of the alkali compound is 0.5 to 50 wt %, especially 1 to 40 wt % based on
the amount of the water or the organic solvent or the mixture consisting
of water and an organic solvent, since the aluminum compound added later
can be more easily dispersed or dissolved.
It is preferable that the solution to be added to the polyester reaction
system contains 0.05 to 20 wt %, as aluminum atoms, of the aluminum
compound and 0.05 to 30 wt % of the alkali compound, since the amount of
the foreign matter in the obtained polyester is especially small. If the
alkali compound is a nitrogen-containing compound, it is especially
preferable that the concentration of the nitrogen-containing compound is
0.05 to 20 wt % as nitrogen atoms, since the amount of the foreign matter
in the obtained polyester is small.
The polyester polymerization catalyst used in the present invention can be
used in polycondensing the product obtained by either the esterification
reaction between an aromatic dicarboxylic acid and a diol, or the ester
interchange reaction between an ester forming derivative of an aromatic
dicarboxylic acid and a diol.
It is preferable that the aluminum compound of the present invention is
added to ensure that the weight of aluminum atoms may be 5 to 500 ppm
based on the weight of the obtained polyester. To obtain sufficient
catalytic activity, hence to obtain a polymer with a higher molecular
weight and a product with sufficient strength, it is preferable that the
amount added is 5 ppm or more. Furthermore, to prevent the likelihood to
produce the foreign matter, the remarkable rise of filtration pressure at
the time of processing and the tendency to worsen the polymer color tone,
500 ppm or less is preferable. A more preferable range is 50 to 400 ppm,
and a further more preferable range is 80 to 350 ppm.
It is preferable to add the alkali compound of the present invention by 50
to 5000 ppm based on the weight of the obtained polyester. In view of the
effect to inhibit the production of any foreign matter, 50 ppm or more is
preferable, and to prevent the worsening of the color tone of the obtained
polyester, 5000 or less is preferable. A more preferable range is 70 to
3000 ppm, and an especially preferable range is 80 to 1000 ppm. Among the
alkali compounds which can be used in the present invention, some are
likely to be dissipated during polymerization reaction, and if any of the
compounds is used, the compound is not required to perfectly remain in the
finally obtained polymer.
The polymerization catalyst containing aluminum of the present invention
can be added to the reaction system at any moment when the polyester is
produced, but it is preferable that the molar ratio (the molar ratio of
the aromatic dicarboxylic acid or any of its ester forming derivatives to
the diol) in the reaction system is 1.25 to 2.0 when the catalyst is
added, since the production of the foreign matter can be especially
inhibited.
In the case of ester interchange reaction, a molar ratio of about 2.0 is
usually adopted, and in this case, the polymerization catalyst containing
the aluminum compound can be added as it is, to the reaction system. On
the other hand, in the case of esterification reaction, a molar ratio of
less than 1.25 may be adopted. So, before the aluminum compound is added,
it is preferable to add, for example, a diol by 0.1 to 1.5 times the
amount of the aromatic dicarboxylic acid, for satisfying said condition.
In the present invention, it is preferable to use a cobalt compound
together, since the polycondensation reaction progresses more quickly and
the color tone of the obtained polyester is improved.
The cobalt compound of the present invention is not especially limited, but
can be selected, for example, from cobalt acetate tetrahydrate, cobalt
nitrate, cobalt chloride, cobalt acetylacetonate, cobalt naphthenate, etc.
It is preferable that the amount of the cobalt compound added is 0.5 to 20
as a molar ratio of aluminum atoms to cobalt atoms (Al/Co). If the molar
ratio is in this range, the effects of improving the polymerization
activity and the polymer color tone are high, and the heat resistance can
also be good. A more preferable range is 1 to 15, and a further more
preferable range is 2 to 10.
In the present invention, a polymerization catalyst like a titanium
compound such as tetrabutyl titanate or tetrapropyl titanate or an
antimony compound such as antimony trioxide or antimony acetate can be
used by a small amount together with the aluminum compound as far as the
effects intended in the present invention are not impaired.
If the amount of the titanium compound added is smaller than the amount of
aluminum atoms added and 50 ppm or less as titanium atoms based on the
amount of the polyester, the polymerization time can be shortened, and the
color tone of the obtained polymer is in a permissible range. More
preferable is 20 ppm or less, and further more preferable is 10 ppm or
less.
If the amount of the antimony compound added is smaller than the amount of
aluminum atoms added and 50 ppm or less as. antimony atoms based on the
amount of the polyester, filament breaking at the time of spinning and
film breaking at the time of film formation can be prevented, and in the
case of bottles, etc., the transparency is in a permissible range. More
preferable is 30 ppm or less, and further more preferable is 10 ppm or
less.
The method for producing the polyester of the present invention is
described below for a case of polyethylene terephthalate.
High molecular polyethylene terephthalate used for fibers, films, resins or
bottles, etc. is usually produced according to either of the following
processes; (1) a process comprising the steps of treating terephthalic
acid and ethylene glycol as raw materials at about 240 to 270 C. at
atmospheric pressure or higher pressure for obtaining low molecular
polyethylene terephthalate or oligomer directly by esterification
reaction, and furthermore heating it to about 290.degree. C. while
reducing the pressure of the system to 133 Pa or less for polycondensation
reaction, to obtain the intended high molecular polymer, and (2) a process
comprising the steps of heating a reaction system containing dimethyl
terephthalate (DMT) and ethylene glycol as raw materials from 150.degree.
C. to 240.degree. C. at atmospheric pressure, to obtain a oligomer by
ester interchange reaction, and effecting polycondensation reaction as
described in (1) to obtain the intended high molecular polymer. The
esterification reaction can be effected even without any catalyst, but the
ester interchange reaction is usually effected using a compound of
manganese, calcium, magnesium, zinc or lithium, etc. as a catalyst and
adding a phosphorus compound to inactivate the catalyst used for said
reaction, after substantial completion of ester interchange reaction.
In the production method of the present invention, a specific
polymerization catalyst containing an aluminum compound and an alkali
compound of the present invention is added to the oligomer obtained in the
beginning or former half of the process (1) or (2), and then, the
polycondensation reaction in the latter half is effected to obtain high
molecular polyethylene terephthalate. Furthermore, the reaction can be
effected in batch operation, semi-batch operation or continuous operation.
The methods for measuring and evaluating properties in the present
invention are described below.
(1) Intrinsic viscosity of polymer [.eta.]Measured with orthochlorophenol
as the solvent at 25.degree. C.
(2) Metal content of polymer Obtained according to the fluorescent X-ray
method.
(3) Color tone of polymer
Pellets were used as a polymer sample, and the light reflected from the
sample was measured using a color difference meter (SM Color Computer
Model SM-3) produced by Suga Shikenki K.K. and expressed according to the
Hunter expression method (values L, a and b).
(4) Amount of carboxyl end groups of polymer According to Maurice et al.'s
method [Anal. Chim. Acta, 22, p. 363 (1960)].
(5) Strength and elongation of fibers
An S--S curve was obtained by Tensilon Tensile Tester produced by Toyo
Baldwin at a sample length of 250 mm at a tensile speed of 300 mm/min, to
calculate the strength and elongation.
The present invention is described below concretely in reference to
examples, but is not limited thereto or thereby.
EXAMPLE 1
Ten parts of aluminum hydroxide were added to 100 parts of an aqueous
solution containing 20 wt % of tetraethylammonium hydroxide, and the
mixture was stirred to obtain a homogeneous aqueous solution. The aqueous
solution was diluted by 90 parts of ethylene glycol, to produce a
homogeneous ethylene glycol solution containing tetraethylammonium
hydroxide, water and aluminum hydroxide, as a solution containing 1.7 wt
%, as aluminum atoms, of an aluminum compound and 10 wt % of an alkali
compound.
On the other hand, a polyester was produced from highly pure terephthalic
acid and ethylene glycol according to a conventional method. That is, an
oligomer produced beforehand was molten and stirred at atmospheric
pressure at 250.degree. C., and a slurry consisting of highly pure
terephthalic acid and ethylene glycol was gradually added to the oligomer,
for esterification reaction, to finally obtain an oligomer not containing
a catalyst. To the oligomer, the ethylene glycol solution containing
tetraethylammonium hydroxide, water and aluminum hydroxide produced
beforehand was added to keep the aluminum atom content at 50 ppm in the
finally obtained polyester. The molar ratio of the reaction system in this
case was 1.50. Furthermore, cobalt acetate tetrahydrate was added to keep
the cobalt atom content at 20 ppm. The oligomer mixture was stirred at 30
rpm, while the reaction system was gradually heated from 250 .degree. C.
to 285.degree. C., with the pressure reduced to 40 Pa. Both the time taken
to reach the final temperature and the time taken to reach the final
pressure were 60 minutes. When a predetermined stirring torque was
reached, the reaction system was purged by nitrogen and returned to
atmospheric pressure, to stop the polycondensation reaction. The product
obtained was discharged into cold water as a strand which was immediately
cut to obtain polyester pellets.
The obtained polymer was 0.68 in intrinsic viscosity, 29 equivalents/ton in
the amount of carboxyl end groups and L=59, a=0.6 and b=5.0 in color tone.
The polymer was analyzed by the fluorescent X-ray method, and the aluminum
atom content was found to be 50 ppm.
As stated above, the polymerization reactivity was good and the polyester
pellets to obtained were also good in their properties.
The pellets were dried, supplied into an extruder type spinning machine and
melt-spun at a spinning temperature of 295.degree. C. In this case, a
metallic nonwoven fabric with an absolute filtration accuracy of 10 .mu.m
was used as the filter, and the spinneret used had a round hole with a
diameter of 0.6 mm. The yarn discharged from the spinneret was gradually
cooled in a heating cylinder with a length of 30 cm, an inner diameter of
25 cm and a temperature of 300 .degree. C., and chimney cooling air was
applied to cool and solidify it. It was oiled and taken up at a take-up
speed of 550 m/min. The undrawn yarn was drawn at 95 .degree. C. with the
drawing ratio changed properly to achieve an elongation of 14 to 15% in
the intended drawn yarn. Then, it was heat-treated at 220 .degree. C. at a
relax rate of 2.0%, to obtain a drawn yarn.
In the melt spinning process, little filtration pressure rise was observed
at the time of spinning, and the yarn breaking little occurred at the time
of drawing, to show that the polymer was good in processability. The
results are shown in Table 1.
EXAMPLES 2 TO 12 AND COMPARATIVE EXAMPLES 1 TO 3
Polymers were produced as described in Example 1, except that the kinds and
quantities of the metal compound and the alkali compound were changed, and
melt-spun. The results are shown in Tables 1 and 2.
The polymers of the present invention were good in physical properties and
melt spinning process. However, when a catalyst free from any alkali
compound or antimony trioxide only was used for polymerization, the
filtration pressure rose remarkably in the melt spinning process, and yarn
breaking occurred frequently, to show poor processability.
The filtration pressure rise and yarn breaking in spinning are caused by
various causes, and the foreign matter in the polymer is also one of the
main causes. In the examples, no or little filtration pressure rise during
spinning was expressed as good. In Examples 6 and 7, some filtration
pressure rise was observed, but it was judged to conform to the tolerance
since it did not affect the normal filter exchange period. No or little
yarn breaking in the examples was also expressed as good. The yarn
breaking in Examples 6 and 7 occurred at the upper limit of an acceptable
range, and was judged to be tolerable in view of operation convenience.
TABLE 1
- Metal compounds Properties of polymer
Amount added based Amount of carboxyl Spinnability
on the amount of Polycondensation Intrinsic end groups Value Value
Value Filtration Yarn
Compounds used polymer (ppm) Al/Co reaction time viscosity (equivalents
/ton) L a b pressure breaking
Example 1 Aluminum hydroxide Al = 50 2.5 2:50 0.68 29 59 0.6 5.0 Good
Good
Tetraethylammonium Alkali =
283 hydroxide
Cobalt acetate Co =
20 tetrahydrate
Example 2 Basic aluminum Al = 50 -- 3:00 0.65 23 59 -0.6 9.5
Good Good
acetate
Tetraethylammonium Alkali =
736 hydroxide
Example 3 Aluminum chloride Al = 50 -- 2:50 0.67 40 53 0.8 14.0 Good
Good
Tetraethylammonium Alkali =
1050 hydroxide
Example 4 Aluminum chloride Al = 45 2.3 2:40 0.68 42 51 1.5 12.0 Good
Good
Tetraethylammonium Alkali =
1600 hydroxide
Cobalt acetate Co =
20 tetrahydrate
Example 5 Aluminum hydroxide Al = 70 -- 3:00 0.65 19 61 -0.2 9.0
Good Good
Tetraethylammonium Alkali =
420 hydroxide
Example 6 Basic aluminum Al = 60 -- 2:40 0.70 20 53 -0.5 8.5 a) b)
acetate
Tetraethylammonium Alkali =
1260 hydroxide
Antimony trioxide Sb =
40 Example 7 Aluminum
hydroxide Al =
60 -- 3:00 0.63 21 63 -0.2 7.0 a) b) Triethylamin
e Alkali =
530
a) Filtration pressure rose to some extent, but within tolerance.
b) Some yarn breaking occurred, but within tolerance.
c) The "Alkali" in "Amount added based on the amount of polymer (ppm)"
means an alkali compound.
TABLE 2
- Metal compounds Properties of polymer
Amount added based Amount of carboxyl Spinnability
on the amount of Polycondensation Intrinsic end groups Value Value
Value Filtration Yarn
Compounds used polymer (ppm) Al/Co reaction time viscosity (equivalents
/ton) L a b pressure breaking
Example 8 Aluminum Al = 60 12 3:00 0.62 42 52 0.6 16.0 Good Good
hydroxychloride
Tetraethylammonium Alkali =
6300 hydroxide
Cobalt acetate Co =
5 Example 9 Basic
aluminum acetate Al =
30 0.6 3:00 0.66 40 60 1.0 8.5 Good Good Triethylamine
Alkali =
5300
Cobalt acetate Co =
50 Example 10
Aluminum hydroxide Al =
80 -- 3:00 0.64 21 60 -0.2 9.5 a) a) Sodium hydroxide
Alkali =
50
Example 11 Aluminum Al = 150 -- 2:30 0.69 21 62 -0.1 7.0 Good Good
acetylacetate
Tetraethylammonium Alkali =
740 hydroxide
Example 12 Aluminum isopropoxide Al = 50 -- 2:30 0.70 30 53 -0.1 10.0
Good Good
Tetraethylammonium Alkali =
420 hydroxide
Tetrabutyl titanate
Comparative Aluminum hydroxide Al = 70 -- 3:20 0.59 23 63 -0.3 7.0
Filtration Yarn
Example 1 pressure breaking
remarkably occurred
rose frequently
Comparative Antimony trioxide Sb = 300 -- 3:00 0.66 20 46 -0.6 4.5
Filtration Yarn
Example 2 pressure breaking
remarkably occurred
rose frequently
Comparative Aluminum chloride Al = 60 3 2:40 0.70 43 51 -0.2 10.0
Filtration Yarn
Example 3 Cobalt acetate Co =
20 pressure breaking tetrahydrate
remarkably occurred
rose frequently
a) Filtration pressure rose to some extent, but within tolerance.
b) Some yarn breaking occurred, but within tolerance.
c) The "Alkali" in "Amount added based on the amount of polymer (ppm)"
means an alkali compound.
INDUSTRIAL APPLICABILITY
The polyester obtained by using the polyester polymerization catalyst of
the present invention is excellent in processability, and does not cause
such problems as spinneret contamination, filtration pressure rise,
filament breaking and film breaking when used for producing products such
as fibers, films, bottles and resins for injection molding, etc.
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