U.S. patent application number 09/860998 was filed with the patent office on 2001-10-11 for process of producing polytrimethylene terephthalate (ptt).
Invention is credited to Blackbourn, Robert Lawrence, Kelsey, Donald Ross, Reitz, Hans, Seidel, Eckhard, Tomaskovic, Robert Stephen, Wilhelm, Fritz.
Application Number | 20010029289 09/860998 |
Document ID | / |
Family ID | 24223095 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010029289 |
Kind Code |
A1 |
Kelsey, Donald Ross ; et
al. |
October 11, 2001 |
Process of producing polytrimethylene terephthalate (PTT)
Abstract
Process of producing polytrimethylene terephthalate (PTT) by
esterification of terephthalic acid (TPA) with trimethylene glycol
(TMG) in the presence of a catalytic titanium compound,
precondensation and polycondensation. The esterification is
effected in at least two stages, where in the first stage a molar
ratio of TMG to TPA of 1.15 to 2.5, a content of titanium of 0 to
40 ppm, a temperature of 240 to 275.degree. C., and a pressure of 1
to 3.5 bar are used. In the at least one subsequent stage a content
of titanium is adjusted which is higher than in the initial stage
by 35 to 110 ppm.
Inventors: |
Kelsey, Donald Ross;
(Fulshear, TX) ; Blackbourn, Robert Lawrence;
(Houston, TX) ; Tomaskovic, Robert Stephen;
(Richmond, TX) ; Reitz, Hans; (Rosbach, DE)
; Seidel, Eckhard; (Frankfurt am Main, DE) ;
Wilhelm, Fritz; (Karben, DE) |
Correspondence
Address: |
Donald F. Haas
Shell Oil Company
Legal - Intellectual Property
P.O. Box 2463
Houston
TX
77252-2463
US
|
Family ID: |
24223095 |
Appl. No.: |
09/860998 |
Filed: |
May 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09860998 |
May 18, 2001 |
|
|
|
09556849 |
Apr 21, 2000 |
|
|
|
Current U.S.
Class: |
528/279 ;
528/301; 528/308.6; 528/308.8 |
Current CPC
Class: |
C08G 63/78 20130101;
C08G 63/183 20130101; C08G 63/85 20130101 |
Class at
Publication: |
528/279 ;
528/301; 528/308.6; 528/308.8 |
International
Class: |
C08G 063/183; C08G
063/66; C08G 063/672; C08G 063/85 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 22, 1999 |
EP |
99107370.1 |
Claims
We claim:
1. A process of producing polytrimethylene terephthalate (PTT) with
an intrinsic viscosity of 0.75 up to at least 1.15 dl/g by
esterification of terephthalic acid (TPA) with trimethylene glycol
(TMG) in the presence of a catalytic titanium compound to obtain an
esterification product, precondensation of the esterification
product to obtain a precondensation product and polycondensation of
the precondensation product to obtain PTT, characterized in that a)
the esterification is performed in at least two stages, a first,
initial stage and at least one second subsequent esterification
step, b) a catalyst feed is provided wherein the catalyst is a
compound of a metal which may be titanium or zirconium, c) a major
quantity between 65 and 100 wt % of said catalyst feed containing
35 to 110 ppm metal is introduced into the at least one subsequent
esterification stage, which is operated at a temperature of 240 to
275.degree. C. and a pressure of 0.7 to 1.5 bar, d) a minor
quantity of said catalyst feed containing 0 to 40 ppm metal and up
to 35 wt % of the total catalyst is directly fed to the initial
esterification stage which is operated at a temperature of 240 to
275.degree. C., a total molar TMG to TPA feed ratio of 1.15 to 2.5,
and a pressure of 1 to 3.5 bar, e) the precondensation is performed
at a temperature of 250 to 270.degree. C. under a reduced pressure
between 2 and 200 mbar, and f) the polycondensation is carried out
in the melt phase at a pressure of 0.2 to 2.5 mbar and a
temperature of 250 to 270.degree. C.
2. A process as claimed in claim 1, characterized in that said
catalyst compound is a titanium alkylate.
3. A process as claimed in claim 2, characterized in that said
titanium alkylate is selected from the group consisting of titanium
tetrabutylate, titanium tetraisopropylate,
tetra-(2-ethylhexyl)-titanate, titanium dioxide-silicon dioxide
co-precipitates, hydrated sodium containing titanium dioxide,
titanium salts of organic acids, and titanium complexes with
hydroxycarboxylic acids
4. A process is claimed in claim 1 characterized in that the
catalyst is introduced as liquid catalyst feed and is prepared
having a concentration of less than 5 wt % metal based on TMG in
the form of a titanium or zirconium compound stabilized by an
organic acid.
5. A process as claimed in claim 4, characterized in that said
liquid catalyst feed contains trimethylene glycol in which a
C.sub.4 to C.sub.12 dicarboxylic acid is dissolved below its
saturation concentration.
6. A process as claimed in claim 5, characterized in that the
dicarboxylic acid is terephthalic acid or isophthalic acid.
7. A process as claimed in claim 4, characterized in that said
liquid catalyst feed contains trimethylene glycol in which a C2 to
C.sub.12 monocarboxylic acid is dissolved below its saturation
concentration.
8. A process as claimed in claim 7, characterized in that the
monocarboxylic acid is acetic acid.
9. A process as claimed in claim 1, characterized in that in step
f), the temperature generally increases from the entrance to the
exit of the polycondensation reactor, the polymer is agitated, and
the reaction product forms steadily renewed, large film surfaces
for evaporation of the split products.
10. A process as claimed in claim 9, characterized in that for
generating the vacuum to perform the precondensation and
polycondensation, vapor-jet pumps are used to remove the released
TMG and PTT oligomers and low boilers from the gas phase of the
reactors, the vapor-jet pumps are operated with TMG vapor, the
vapors sucked off and compressed by the vapor-jet pumps, and the
TMG vapors are condensed by spraying them with a liquid which
predominantly consists of TMG.
11. A process as claimed in claim 1, characterized in that the the
process is continuous and the reaction product is withdrawn at any
point between the exit of the subsequent stage of esterification
and the entry to the polycondensation and mixed with the TMG and
TPA by recycling said reaction product to the first initial
esterification stage.
12. A process as claimed in claim 11, characterized in that the
amount of said reaction product which recycled to the initial
esterification stage is in the range of 5 to 40 wt % of the nominal
throughput.
13. A process as claimed in claim 1, characterized in that the
process is a discontinuous process and the initial process cycle
with a transiently heterogeneous reaction mixture and a limited TPA
conversion of below 95% represents said initial stage and the later
reaction cycle in a homogeneous melt phase with a TPA conversion of
at least 97% represents said subsequent stage of the esterification
process to which the major part of the catalyst is fed, and a
portion of the reaction product is kept back at the end of the
precondensation and used for the next discontinuous process in step
d) as catalyst-containing reaction product.
14. A process as claimed in claim 13, characterized in that the
amount of said catalyst containing reaction product recycled to the
initial esterification stage is from 25 to 85 wt % of the nominal
batch size.
15. A process as claimed in claim 1, characterized in that the
first initial stage of esterification is conducted to a degree of
esterification of 90 to 95 wt %, and the subsequent stage of
esterification is conducted to a degree of esterification of 97 to
99 wt %.
16. A process as claimed in claim 10, characterized in that the
condensed vapors are recirculated to the initial stage of the
esterification, optionally to subsequent esterification stages and
optionally after removal of the low boilers from TMG by
distillation.
17. A process as claimed in claim 1, characterized in that the PTT
contains up to 20 wt % comonomer units derived from other
dicarboxylic acids and/or diols.
18. A process as claimed in claim 1, characterized in that said
polycondensation reactor is a disc ring reactor or a cage type
reactor.
19. A process as claimed in claim 1, characterized in that in
keeping with the desire to maintain control of the temperature to
which the polymer is exposed during each stage of the process
including polycondensation, the temperatures of the walls of the
reaction vessels are controlled by using a heat transfer medium
(HMT) be used and that the HMT temperature be not more than
300.degree. C.
20. The product of the process of claim 1.
21. The product of the process of claim 11.
22. The product of the process of claim 13.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a process of producing
polytrimethylene terephthalate (PTT) with an intrinsic viscosity of
at least 0.75 dl/g by esterification of terephthalic acid (TPA)
with trimethylene glycol (TMG; this is also referred to as
1,3-propanediol, PDO) in the presence of a catalytic titanium
compound to obtain an esterification product, precondensation of
the esterification product to obtain a precondensation product, and
polycondensation of the precondensation product to obtain PTT.
BACKGROUND OF THE INVENTION
[0002] Processes of producing PTT are known (U.S. Pat. Nos.
2,456,319; 4,611,049; 5,340,909; 5,459,229; 5,599,900).
[0003] For instance, U.S. Pat. No. 4,611,049 describes the use of a
protonic acid as co-catalyst for accelerating the polycondensation
of TMG and dimethyl terephthalate, where the addition of p-toluene
sulfonic acid in a concentration of 50 mmol % effects an increase
of the maximum achievable intrinsic viscosity of 0.75 dl/g in a
batch process catalyzed with 50 mmol % tetrabutyl titanate to 0.90
dl/g.
[0004] U.S. Pat. No. 5,340,909 proposes to achieve an improvement
of the polycondensation capacity and the color of the
polytrimethylene terephthalate by using a tin catalyst, which
together with titanium can already be present in the
esterification. Statements on the influence of recirculation of the
vapor condensates obtained during the polycondensation on the
polycondensation capacity of the reaction melt cannot be found in
U.S. Pat. No. 5,340,909.
[0005] U.S. Patent No. 5,459,229 proposes to reduce the
concentration of acrolein in the vapors by adding alkalines to the
condensates produced during the esterification of trimethylene
glycol and terephthalic acid U.S. Pat. No. 5,459,229 does not
contain any details concerning the esterification and
polycondensation.
[0006] U.S. Pat. No. 5,599,900 describes a process of producing
polytrimethylene terephthalate, where in the presence of an inert
stripping gas either after the transesterification or after the
esterification a polytrimethylene terephthalate with a degree of
polymerization of 64 is synthesized. Moreover, it is desired to
also adjust higher molecular weights but this is not proven by
experiment.
[0007] WO 97/23543A describes a process of producing
polytrimethylene terephthalate, where it is provided to produce a
preproduct with an intrinsic viscosity of 0.16 dl/g by means of
transesterification. This preproduct is converted to pastilles by
means of dripping, which pastilles directly crystallize at
crystallization temperatures up to 130.degree. C. The actual
polymer is produced subsequently by solid phase condensation. It is
disadvantageous that a high amount of trimethylene glycol and
oligomers gets into the process gas and must be recovered or burnt,
which is expensive.
[0008] U.S. Pat. No. 5,798,433 describes a process of producing PTT
by direct esterification of terephthalic acid with 1,3-propanediol
and subsequent precondensation and polycondensation. The PTT
produced is obtained using a combination of titanium and antimony
catalysts. The quantity of the required catalyst is very high and
causes severe disadvantages in the product quality especially with
regard to the product thermal stability.
[0009] From U.S. Pat. No. 4,011,202 the use of glycol jet pumps is
known. However, the use of TMG jets is not detailed.
[0010] It can be seen that it would be advantageous to create a
melt phase process of producing PTT with an intrinsic viscosity
between 0.75 and 1.15 dl/g and a good thermal stability, and to
achieve at the same time an efficiently long service life of the
filters when the polymer melt is filtered prior to processing the
same to form the end products. The process may be a batch or
continuous process. Additionally, the PTT process should also allow
the recycling of TMG and oligomer byproducts.
SUMMARY OF THE INVENTION
[0011] The characteristic features of this process, which comprises
the catalytic esterification of TPA with TMG, precondensation of
the esterification product and polycondensation of the
precondensation product, are as follows:
[0012] 1) The esterification is performed in at least 2 stages, one
initial stage and at least one second, subsequent stage connected
to a process column.
[0013] 2) The catalyst used for esterification and polycondensation
is a titanium compound, preferably in a stabilized liquid
formulation, which is prepared from a catalytic titanium compound,
an organic acid and TMG as solvent, in such way that the liquid
catalyst feed contains less than 5 percent by weight (wt %)
titanium
[0014] 3) The catalyst used for esterification in the first,
initial stage can be alternatively a Ti containing liquid reaction
product from TPA and TMG with a degree of esterification of at
least 97%, which may be recycled from a later reaction stage and
fed to the initial esterification stage together with the raw
materials.
[0015] 4) A defined quantity of the described liquid catalyst feed
is introduced into the first, initial esterification stage and
separately a second defined quantity of the liquid catalyst feed is
added to the at least one subsequent stage of esterification.
[0016] 5) a major quantity between 65 and 100 wt % of said liquid
catalyst feed containing 35 to 110 ppm titanium may be introduced
into the at least one subsequent esterification stage, which is
operated at a temperature of 245 to 260.degree. C. and a pressure
of 0.7 to 1.5 bar,
[0017] 6) a minor quantity of said liquid catalyst feed containing
0 to 40 ppm titanium and up to 35% of the total catalyst may be
directly fed to the initial esterification stage, which direct
catalyst feed can be partially or completely substituted by the
same quantity of catalyst in a reaction product, which may be
recycled from any further reaction stages and which is mixed with
the raw materials for further reaction in said initial
esterification,
[0018] 7) In the first, initial esterification stage a total molar
feed ratio of TMG/TPA of 1.15 to 2.5, an amount of titanium of 0 to
40 ppm, which is in maximum 35% by weight of the total amount of
catalyst, a temperature of 240 to 275.degree. C. and an absolute
pressure of 1 to 3.5 bar are adjusted, whereby the reaction is
continued until 90 to 95% of the TPA is esterified.
[0019] 8) In the at least one subsequent esterification stage an
additional amount of titanium of 35 to 110 ppm, which is 65 to 100%
by weight of the total amount of catalyst, a temperature of 245 to
260.degree. C. and an absolute pressure of 0.7 to 1.5 bar are
adjusted, whereby the reaction is continued until 97 to 99% of the
TPA is esterified.
[0020] 9) The precondensation is performed at a temperature of 245
to 260.degree. C. under a reduced pressure in the range from 2 to
200 mbar.
[0021] 10) The polycondensation is carried out in the melt phase at
a temperature increasing from the entry to the exit of the
polycondensation reactor from 250 to 270.degree. C. and at an
absolute pressure of 0.2 to 2.5 mbar.
[0022] 11) For generating the vacuum of the precondensation and
polycondensation vapor-jet pumps are used, which are operated with
TMG vapor, and the vapors sucked off and said TMG vapors are
compressed by the vapor jet pumps and condensed by spraying them
with a liquid which predominantly consists of TMG, for example the
condensate from these spray condensers and optionally fresh make-up
TMG.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The feed amount of titanium in the first, initial
esterification stage preferably is in the range from 5 to 25 ppm.
As the catalytic titanium compound to prepare the catalyst liquid
there may preferably be used titanium tetrabutylate or titanium
tetraisopropylate. As advantageous catalytic titanium compounds
there may for instance also be used any catalytic titanium
compound, such as titanium alkylates and their derivatives, like
tetra-(2-ethylhexyl)-titanate, tetrastearyl titanate,
diisopropoxy-bis(acetyl-acetonato)-titanium, di-n-butoxy-bis
(triethanolaminato)-titanium, tributyl monoacetyltitanate,
triisopropyl monoacetyltitanate or tetrabenzoic acid titanate,
titanium complex salts, like alkali titanium oxalates and
malonates, potassium hexafluorotitanate, or titanium complexes with
hydroxycarboxylic acids such as tartaric acid, citric acid or
lactic acid. Also special catalysts as titanium dioxide--silicon
dioxide--co-precipitate or hydrated alkaline containing titanium
dioxide can be used. Equivalent zirconium catalysts could also be
used.
[0024] The solvent which is used in the liquid catalyst feed is
TMG, in which for stabilization reasons a C.sub.4 to C.sub.12
dicarboxylic acid is dissolved in quantities below its saturation
concentration at ambient temperature.
[0025] The organic di-acid which is preferably used for the liquid
catalyst feed is selected from terephthalic acid, isophthalic acid
or another C.sub.4-C.sub.12 aromatic or aliphatic dicarboxylic
acid. Preferably the C.sub.4 to C.sub.12, dicarboxylic acid is
incorporated in the PTT and does not act as chain stopper. A
further embodiment consists of solutions of catalyst in TMG in
which a C.sub.2 to C.sub.12, preferably C.sub.2 to C.sub.8,
monocarboxylic acid is dissolved below its saturation
concentration. The preferred monocarboxylic acid is acetic
acid.
[0026] As further embodiment of the invention the catalyst liquid
can be a Ti containing liquid reaction product from TPA and TMG
with a degree of esterificaiion of at least 97%. This product is
recycled from a later reactor stage and mixed to the first, initial
esterification process together with the raw materials. In the
continuous process the recycled product amounts to 5 to 40 wt %,
more preferably to 10 to 30 wt % of the nominal throughput. In the
case of the batch process the amount of recycled product lies
between 25 and 85 wt %, preferably between 35 and 70 wt % of the
nominal batch size. This option of the invention includes reaction
products which may be withdrawn at any point between the exit from
the second stage of esterification and the entry into
polycondensation, and which are used as liquid catalyst feed for
the first initial esterification stage.
[0027] The second portion of the catalyst may be fed after the
esterification step. An important aspect of the invention consists
in that in the initial stage of esterification a specific
combination of parameters is used.
[0028] The described special catalyst liquid is well proven at
temperatures within the range of 250 to 270.degree. C., an elevated
molar feed ratio of TMG to TPA between 1.15 and 2.5, preferably
between 1.5 and 2.4, and a pressure of 1 to 3.5 bar. Under these
conditions only a minor formation of non-filterable particles
occurs independently whether delustering agents, like TiO.sub.2, or
other additives are used. This is particularly necessary in the
production of fibers.
[0029] In accordance with a further preferred aspect of the
invention, the first initial stage of esterification is conducted
to a TPA conversion of 90 to 95%, and the second stage of
esterification raises the TPA conversion to 97 up to 99%. Late in
the second stage of esterification it has been assured that the
last particles of solid TPA from the paste are completely dissolved
and the melt is clear and bright.
[0030] The catalyst liquid introduced into the second or further
stages of esterification is preferably a clear solution. These
above mentioned conditions enable low filter values of the PTT.
[0031] The process can be a continuous or a batch process. In the
discontinuous process the initial process cycle with a transiently
heterogeneous reaction mixture and a limited TPA conversion of
below 95%. is considered as the first, initial stage of
esterification, while the later reaction cycle in a homogeneous
melt phase at a TPA conversion of at least 97% represents the at
least one subsequent esterification stage. Accordingly the second
part of the liquid catalyst feed is added when the TPA has been
esterified to at least 95%, preferably to more than 97%.
[0032] The precondensation, especially in the continuous process,
is preferably divided into two pressure sections to provide an
optimum condensation process. The first stage of precondensation is
performed between 50 and 200 mbar, the second stage between 2 and
10 mbar.
[0033] It is particularly advantageous when the polycondensation of
the prepolymer melt is performed at a pressure of 0.3 to 0.8
mbar.
[0034] Preferably the polycondensation reactor is a disc ring
reactor or a cage type reactor, which allows the formation of
steadily renewed, large film surfaces of the reaction product and
facilitates by this the evaporation of the volatile products. Under
these conditions, increased intrinsic viscosities in the range from
0.75 to 1.15 dl/g are possible.
[0035] In keeping with the desire to maintain control of the
temperature to which the oligomer or polymer is exposed during each
stage of the process including polycondensation, the temperatures
of the walls of the reaction vessels are controlled, as contact of
the polymer with excessively hot vessel walls is a potential cause
of polymer degradation. It is preferred that a heat transfer medium
(HMT) be used to control the temperature of the reactor walls and
that the HMT temperature be not more than 300.degree. C.,
preferably not more than 290.degree. C.
[0036] It is surprisingly found out that in accordance with the
inventive process very advantageous filter values of 0 to 40
bar-cm.sup.2/kg can be realized (for the determination of filter
value, see below).
[0037] In accordance with a further object of the invention it is
provided that the condensates of the spray condensers, optionally
after the distillation of low boilers, are recirculated into the
first initial and possibly further stages of esterification. In
this way, a substantial reduction of the losses in raw materials is
achieved.
[0038] In accordance with a further preferred embodiment of the
invention it is provided that the PTT contains up to 20 wt %
comonomer units derived from other dicarboxylic acids and/or diols.
As other dicarboxylic acid there may for instance be used adipic
acid, isophthalic acid or naphthalene dicarboxylic acid. As diols
there may for instance be used ethylene glycol, diethylene glycol,
triethylene glycol, butylene glycol, polyglycols, as well as
cyclohexane dimethanol. In this way, the end product can be adapted
to the respective application relatively easily.
[0039] A further embodiment of the invention consists in that at
any point before the end of the polycondensation in the melt phase
usual additives such as delustering agents and/or color agents
and/or branching agents and/or stabilizers can be added. By means
of this measure, the number of the applications of the end product
will be increased in connection with a particular viscosity
adjustment.
[0040] In accordance with the invention, a polyester-soluble cobalt
compound, for instance cobalt acetate, and/or polyester soluble
organic dyes can be used as color agent or blue toner. As
stabilizer a phosphorus compound is added with up to 20 ppm
phosphorus, based on PTT, in connection with the cobalt compound
and up to 10 ppm phosphorus without any addition of cobalt. By this
amounts of phosphorus the catalysis of the thermal degradation of
the PTT melt by ions of heavy metals including of the cobalt is
stopped because of the formation of neutral phosphorus salts. In
special cases the addition of phosphorus may be omitted completely;
this depends on the quality of the raw materials, the construction
materials of the equipment as well as on the final product
application.
[0041] Other stabilizers include hindered phenolic esters such as
those selected from the group consisting of
methyl(3-(3,5-di-t-butyl-4-hydroxyp- henyl)propionate, octadecyl
3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, tetrakis(methylene
-3,5-di-t-butyl-4-hydroxyphenyl) propionate))methane,
1,6-hexamethylene bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)
ropionate), triethyleneglycol
bis(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate) and
1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H-
,5H)-trione.
[0042] Also, there may be used as stabilizers aromatic
organophosphites including those selected from the group consisting
of tris(2,4-di-t-butylphenyl)phosphite,
bis(2,4-di-t-butylphenyl)pentaerythr- itol diphosphite and
2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo
[d,f][1,3,2]-dioxaphosphepin-6-yl]oxy]-N,N-bis[2-[[2,4,8,10-tetrakis(1,1--
dimethylethyl)dibenzo[d,f][1,3,2]
dioxaphosphepin-6-yl]oxy]-ethyl]ethanami- ne.
[0043] A further optional aspect of the invention is that
carboxylic acids with three or more COOH groups, polyfunctional
acid anhydrides, or polyfunctional alcohols with three or more OH
groups, or carboxyphosphonic acids or the esters thereof in
concentrations below 5000 ppm can be incorporated into the polymer
as branching agents. For polycarboxylic acids and polyalcohols
concentrations below 1000 ppm are sufficient in most cases. These
compounds can particularly be used for adjusting or raising the
intrinsic viscosity.
[0044] The PTT can be directly processed to fibers, films or other
molded materials. In accordance with a further embodiment of the
invention is provided that after the polycondensation in the melt
phase the PTT is granulated and crystallized. The resulting
granulate can also be thermally treated in the solid state for
further IV build up or for devolatilizing low molecular organic
products such as acrolein, allyl alcohol, and water. The PTT
granulate can then be processed to fibers, filaments, films or
molded articles.
[0045] The processed products, i.e. fibers, filaments, films,
molded articles or chips, are characterized by an IV of 0.8 to 1.1
dl/g, a filterability of <40 bar-cm.sup.2/kg and a thermal
stability (as defined below) of >80
EXAMPLES
[0046] In examples 1-8, the intrinsic viscosities (IV) were
determined with a solution of 0.5 g polyester in 100 ml of a
mixture of phenol and 1.2-dichlorobenzene (DCB) (3:2 parts by
weight) at 25.degree. C. In examples 9-18, tetrachloroethane (TCE)
was used with phenol as described below. These tests give virtually
the same IV results and are related as follows: IV(DCB)=0.963
IV(TCE)+0.036. The COOH terminal group concentration is determined
by photometric titration with 0.05 N ethanolic potassium hydroxide
solution against bromothymol blue of a solution of polyester in a
mixture of o-cresol and chloroform (70:30 parts by weight). The
measurement of the polymer color values is made on crystallized
polyester granules (crystallization at 150.+-.5.degree. C./1 h) in
a tristimulus colorimeter containing three photoelectric cells with
a red, green, or blue filter. The color values were calculated from
the parameters X, and Z according to CIELAB.
[0047] The filtration behavior of the product melts is determined
as follows: PTT dried for 13 hours at 130.degree. C. and a reduced
pressure of <1 mbar is melted in a laboratory extruder and
metered through a disc filter with a mesh size of 15 .mu.m and a
filter area of 2.83 cm.sup.2 by means of a gear pump at a
temperature of 260.degree. C. The increase.in pressure before the
filter is recorded in relation to the amount of melt conveyed and
the filterability is calculated as filter value (FV):
[0048] FV=filter pressure[bar]-filter area [cm.sup.2]/amount of
melt[kg]
[0049] The thermal stability (TS) of the PTT melt is determined by
measuring the intrinsic viscosity of the PTT chips dried for 13
hours at 130.degree. C. and a reduced pressure of <1 mbar as
IV.sub.O before and as IV.sub.T after tempering of the dried chips
over one hour at a reference temperature of 255.degree. C. in a
closed tube under nitrogen.
TS[%]=100-IV.sub.T/ IV.sub.O
[0050] The stated concentrations of the catalysts and additives
used in the following examples are defined as parts per million
(ppm) referring to the TPA feed.
[0051] The catalyst solutions used in the examples according to the
invention were prepared as follows:
Catalyst preparation A
[0052] (TPA-stabilized TMG solution)
[0053] Because of the hygroscopic properties of TMG, the catalyst
solutions were preferably prepared and stored under nitrogen
atmosphere. TMG is preheated to 80.degree. C. 50 mg TPA per kg TMG
were added while stirring, and stirring is continued until a clear
solution is obtained after 20 minutes. The TMG/TPA solution is
cooled to about 30.degree. C.
[0054] The titanium tetrabutylate is metered with a dropping funnel
to the cold, clear acidified TMG solution while stirring. There is
thus produced a solution of 2 wt %. titanium tetrabutylate in
acidified TMG, which is used in this form. When the first drops of
titanium tetrabutylate were added, the TMG solution turned light
yellow.
[0055] Remarkably, this color did not change anymore during the
further addition of titanium tetrabutylate.
Catalyst preparation B
[0056] (IPA-stabilized TMG solution)
[0057] The TMG is preheated to about 60.degree. C. Then a clear
solution of 500 mg isophthalic acid (IPA) per kg TMG is produced by
stirring. This concen trated solution is cooled to about 30.degree.
C. Before adding the titanium tetrabutylate the cooled solution is
diluted with fresh TMG in a ratio of 1:4. Thus, the concentration
of IPA in the finished solution is 100 mg IPA per kg TMG. The
addition of the titanium tetrabutylate to the TMG/IPA solution is
performed in the same way as for preparation A.
Preparation of Catalyst C
[0058] Titanium tetrabutoxide (100 parts) was added slowly with
stirring to about 35 to about 100 parts glacial acetic acid under
nitrogen atmosphere. 1,3-Propanediol was then added gradually to
this solution to adjust the concentration of titanium to about 1 wt
% (7% titanium tetrabutoxide). The catalyst solution was clear,
water-white and stable for several days at ambient temperatures
with no evidence of precipitates.
[0059] The invention is illustrated in the following examples. The
results of the examples are summarized together with the fed
concentrations of catalyst and additives in the table. Examples 1,
2, and 4 are comparative examples.
Examples 1 to 3 (Batch process)
[0060] In this batchwise production of PTT a part of prepolymer
from a preceding, prepolymer batch in a quantity of about 42 wt %
of the nominal batch size is kept back in the esterification
reactor for the next reaction cycle for stirring the esterification
product and for feeding and heating the raw materials TMG and TPA
as a paste including the esterification catalyst and optionally
cobalt acetate as color agent. The molar TMG to TPA feed ratio of
the paste is listed in the table.
[0061] The quantity of TPA fed into the esterification reactor is
180 kg. The feeding time is 130 minutes. The total cycle time of
esterification in examples 1 and 2 is 160 minutes at a temperature
of 265.degree. C. and a pressure of 1000 mbar (abs.). A column
disposed subsequent to the esterification reactor is used for
separating the low-boiling compounds, mainly process water, from
the trimethylene glycol in the vapors from the esterification, and
for the recirculation of the distilled TMG to the process all the
time of esterification. The precondensation is carried out in 30
minutes at a simultaneous pressure reduction to 50 mbar (abs.).
Thereafter, the prepolymer melt is transferred to a disc ring
reactor, and the polycondensation is started by agitating defined
by a standard program of speed control and further reducing the
pressure within 45 minutes to 0.5 mbar as final pressure. The
polycondensation temperature in examples 1 and 2 increased from 260
to 268.degree. C. The total duration of polycondensation indicated
in the table corresponded to the maximum viscosity of the polymer
possible under the selected conditions, i.e., if the
polycondensation is further continued, the intrinsic viscosity of
the polymer decreased again due to the predominance of the thermal
degradation reactions. Upon reaching the viscosity maximum, the
polycondensation is stopped. At an applied pressure of 55 to 60 bar
the polymer melt is discharged from the reactor and granulated.
Special feed conditions within example 1 (comparative)
[0062] In example 1, titanium dioxide/silicon dioxide
co-precipitate containing 80 mole % TiO.sub.2 with 50 ppm Ti is fed
to the paste as esterification catalyst. In addition, cobalt
acetate with 40 ppm Co is added to the paste. Before starting of
the precondensation, phosphoric acid with 40 ppm P is added to the
melt and after further 2 minutes antimony triacetate with 250 ppm
Sb is added as polycondensation catalyst.
Special feed conditions within example 2 (comparative)
[0063] In example 2, titanium tetrabutylate with 75 ppm Ti is fed
to the paste as esterification catalyst. Before start of the
precondensation reaction in the esterification reactor, antimony
triacetate with 200 ppm Sb is added as polycondensation
catalyst.
[0064] Selected process conditions and quality values of the
polytrimethylene terephthalate obtained are listed in the following
table. In the comparative process very high amounts of catalyst up
to 300 ppm were required. In the following inventive examples 80
ppm Ti were sufficient at comparable process times. The process
results of the Comparative examples show a deficit with regard to
the possible IV build-up, the thermostability, and the
filterability.
Special conditions within example 3 (inventive)
[0065] According to example 3, TMG and commercially available TPA
in a molar ratio of 1.3 were continuously fed into a paste mixer.
Additionally 15 ppm titanium were added via a catalyst liquid of
titanium tetrabutylate in TMG containing TPA according to catalyst
preparation A. The resulting paste is fed into the esterification
reactor over 130 minutes and reacted batchwise (similar to example
1 and 2). The reaction is performed at an increased pressure of
2000 mbar and at a temperature of 255.degree. C. during a cycle
time of 160 minutes. The column of the esterification is operated
at a molar recycling ratio of TMG to TPA of 0.1 to 0.9, which ratio
passed through a maximum during the esterification time. The
average total molar feed ratio of TMG to TPA in the esterification
reactor is about 1.8.
[0066] For completion of the esterification, the reactor pressure
is reduced to 1000 mbar within 15 minutes and the esterification is
continued in the later stage while stirring at 1000 mbar for 30
minutes. At 5 minutes before starting the vacuum program 65 ppm
titanium are added to the esterification product as
polycondensation catalyst via the catalyst liquid of preparation A
at steady stirring of the product mixture. The subsequent
precondensation is carried out during 30 minutes at a temperature
of 255.degree. C. and a simultaneous reduction of the pressure to
100 mbar. Subsequently, the melt is transferred to a disc ring
reactor, where it is polycondensated at an increasing temperature
of 251-262.degree. C. at a dwell time of 165 minutes and a final
pressure of 0.5 mbar. Thereafter the melt is discharged and
granulated to PTT chips.
[0067] This example clearly illustrates according to the table that
under batch conditions, when using the conditions described in the
present invention, a stable PTT with an IV of 1.1 dl/g and a filter
value of 27 bar-cm.sup.2/kg is produced. The relatively low
concentration of carboxyl endgroups in the PTT indicates that no
remarkable polymer degradation during discharge of the PTT occurrs.
The thermal stability of the PTT enables a problem-free extrusion
and spinning or molding to obtain high quality PTT products.
Examples 4 to 8 (continuous process)
[0068] Example 4 (comparative)
[0069] TMG and commercially available TPA in a molar ratio of 1.16
is continuously fed to a paste mixer, and a paste is produced. The
catalyst concentration in the paste is 15 ppm titanium. As catalyst
titanium tetrabutylate is used as a 10 wt % mixture with TMG. The
paste is continuously fed into the initial esterification reactor
and reacted at a pressure of 1000 mbar and a temperature of
255.degree. C. for a mean dwell time of 172 minutes under stirring
and steady TMG reflux from the esterification column. Into the
transfer line to a subsequent stirred esterification stage, a
second portion of the catalyst (10 wt % titanium tetrabutylate in
TMG) with 65 ppm Ti is added, and the product is further esterified
in the subsequent esterification stage at a pressure of 1000 mbar,
a temperature of 255.degree. C. with a mean dwell time of 60
minutes. The esterification product is transferred into a third
reaction stage also equipped with a stirrer for precondensation at
100 mbar and 255.degree. C. within 30 minutes.
[0070] Likewise the precondensation is completed in a further stage
at 7 mbar, 257.degree. C. within 35 minutes. The precondensate,
showing an IV of 0.26 dl/g is transferred to a disc ring reactor by
means of a gear-type metering pump for the final polycondensation
at a vacuum of 0.5 mbar, a mean dwell time of 150 minutes, an
increasing temperature profile of 258-264.degree. C., and an
agitator speed of 5.5 rpm. From the disc ring reactor, the melt is
discharged and granulated.
[0071] The PTT thus produced has an intrinsic viscosity of 0.92
dl/g and a filter value of 143 bar-cm.sup.2/kg. The higher
concentration of carboxyl endgroups in the PTT indicated another
different (from the invention) polymer formation, whereas the
thermal properties of the products are similar. Polymers with such
high filter values entail to a short service life of the filter in
the spinning process, and are not suitable for the production of
fibers and filaments.
Example 5
[0072] In example 5, the conditions for the production of PTT
corresponds to example 4 with following exceptions. The molar ratio
TMG:TPA in the paste is raised to 1.3 and the catalyst
concentration in the paste is 15 ppm titanium. As catalyst liquid,
catalyst preparation B is used. The paste is continuously fed into
the first initial esterification reactor and reacted while stirring
at a pressure of 2000 mbar and a temperature of 255.degree. C. for
a mean dwell time of 172 minutes. The molar reflux from the column
of the esterification amounted to 0.8 moles TMG per TPA. Thus, a
total molar ratio of TMG to TPA of 2.1 is present. After the
continuous transfer to a second subsequent esterification stage, a
further amount of catalyst of 65 ppm Ti is added into the mixed
esterification product in form of the catalyst preparation B. The
esterification in the second stage, the precondensation, and the
polycondensation are performed at conditions identical to those in
example 4.
[0073] The PTT thus produced had an intrinsic viscosity of 0.93
dl/g and a filter value of 5 bar-cm.sup.2/kg. The good filter value
of the intermediate prepolymer sample of 8 bar-cm.sup.2/kg,
indicates a good filterability of the melt. In the PTT production
process and in the production of fibers and filaments this offers
great economic advantages due to a long service life of the
filter.
Example 6
[0074] Similar to example 5, TMG and TPA are continuously fed into
the paste mixer in a molar ratio of 1.25. Thereby 70 wt % of the
TMG used consisted of recycled TMG collected from the vapor
condensers of different stages. The concentration of solids (a
mixture of PTT oligomers) in the recycled TMG is 2.5 wt %. In
addition, 15 ppm titanium as catalyst solution, preparation B, and
20 ppm Co as cobalt acetate are added to the raw material paste,
and the paste is pumped to the initial esterification stage. The
total molar TMG to TPA feed ratio including the TMG reflux from the
column is 1.9. All other process conditions in esterification,
precondensation, and polycondensation are selected in accordance
with example 4. According to example 5, additional 65 ppm Ti
are.added into the mixed esterification product of the subsequent
second esterification stage. As catalyst liquid feed is used
preparation B. Additionally 20 ppm P (as solution of phosphoric
acid in TMG) are dosed into the transfer line of the esterification
product to the first precondensation stage. The granulated PTT had
a viscosity of 0.918 dl/g and a filter value of 7
bar-cm.sup.2/kg.
Example 7
[0075] Example 7 is performed in a similar way as example 6, and
for the production of paste there is likewise used recycled TMG.
The molar ratio TMG to TPA is 1.25. 46 wt % of the TMG present in
the feed paste are recycled TMG with a content of oligomeric solids
of 2.2 wt %. Different from example 6, 10 ppm Co as cobalt acetate
and 5 ppm P as phosphoric acid are added to the paste. The catalyst
feed into the paste is 15 ppm Ti as catalyst liquid preparation A.
The polycondensation catalyst is added in an amount of 65 ppm Ti,
as catalyst liquid preparation A to the melt of the subsequent
second esterification stage. The other process conditions are as
following:
1 Total TMG/TPA - mol ratio = 1.9 1st Esterification stage:
249.degree. C. 2000 mbar 230 min 2nd Esterification stage:
248.degree. C. 1000 mbar 30 min 1st Prepolycond. stage: 247.degree.
C. 80 mbar 37 min 2nd Prepolycond. stage: 247.degree. C. 8 mbar 41
min Polycondensation stage: 247-260.degree. C. 0.3 mbar 220 min
[0076] Under these process conditions a PTT is obtained with an IV
of 0.93 dl/g, a high thermal stability, and a good
filterability.
Example 8
[0077] (continuous process with recirculation of the melt from
esterification 2 to esterification 1)
[0078] TMG and TPA are continuously fed into the paste mixer in a
molar ratio of 1.25. Thereby, 58 wt % of the TMG used consists of
recycled TMG with 2 wt % of oligomeric solids. After achieving
stationary flow conditions the TMG/TPA feed paste without any
catalyst is transferred to the first, initial stirred
esterification stage. At the same time a separate partial recycling
stream of 19 wt % of the product from the subsequent second
esterification stage is directed to the first initial stage
containing the catalyst as a diluted solution in a prereacted
homogenous product mixture with an increased degree of
esterification of about 97.5%.
[0079] The actual catalyst addition to the second esterification
stage is carried out with 80 ppm Ti (based on PTT) as liquid
catalyst preparation B. As a consequence of the partial product
recycling from the second subsequent esterification stage into the
initial esterification stage the relative throughput per 100 wt %.
product is in both esterification stages increased to 119 wt % and
the average residence times are decreased to 135 and 48 minutes.
The total molar TMG to TPA feed ratio to the esterification is 2.0.
Further conditions are:
[0080] 1st esterification stage: 255.degree. C 1800 mbar
[0081] 2nd esterification stage: 255.degree. C 1000 mbar
[0082] The process conditions in the precondensation and
polycondensation are the same as in example 4. The final PTT
product shows an IV of 0.913 dl/g, a good thermal stability, and a
good filterability, in accordance with the invention.
2TABLE A Selected feed parameters, process parameters, and product
properties of the examples 1-8 TMG in paste Pre- Polytrimethylene
terephthalate (mol) Esterfication Color polymer Polycondensation
Duration of Filter per Catalyst agent H.sub.2PO.sub.4 Filler
Catalyst Polyconden COOH value 1 mol Ti Co P value bar Sb sation
I.V. TS meq/ bar Run TPA) Type (ppm) (ppm) (ppm) cm.sup.2/kg Type
(ppm) Ti (min) (Dl/g) (%) kg) cm.sup.2/kg 1 (comp) 1.25
TiO.sub.2:SiO.sub.2 50 40 40 52 SbAc.sub.3 250 -- 171 0.916 72.1 14
68 2 (comp) 1.3 Ti(OBu).sub.4 75 -- -- 45 SbAc.sub.3 200 -- 80
0.892 71.6 12 42 3 (inv) 1.3 Ti(OBu).sub.4 15 -- -- 4 Ti(OBu).sub.4
-- 65 165 1.101 80.2 10 27 4 (comp) 1.16 Ti(OBu).sub.4 15 -- -- 189
Ti(OBu).sub.4 -- 65 150 0.922 82.9 19 143 5 (inv) 1.3 Ti(OBu).sub.4
15 -- -- 8 Ti(OBu).sub.4 -- 65 150 0.930 83.7 10 5 6 (inv) 1.25
Ti(OBU).sub.4 15 20 20 2 Ti(OBu).sub.4 -- 65 150 0.932 83.6 11 7 7
(inv) 1.25 Ti(OBu).sub.4 15 10 5 31 Ti(OBu).sub.4 -- 65 220 0.921
84.0 12 29 8 (inv) 1.25 Ti(OBu).sub.4 15* -- -- 22 Ti(OBU).sub.4 --
80 150 0.913 84.2 11 18 *Catalyst feed by partial product recycling
from the second esterification stage (comp): Comparative example
(inv): Example according to the invention I.V.: Intrinsic Viscosity
of PTT, determined with 0.5 g sample in 100 mL of 3:2 (wt.)
phenol:1,2-dichlorobenzene at 25.degree. C. TS: Thermal stability
of PTT (255.degree. C./N.sub.2/lb) COOH: Carboxyl terminal groups
of PTT, determined by photometric titration with 0.05n ethanolic
potassium hydroxide solution against bromothymol blue of a solution
of polyester in 70:30 (wt) O-cresol:chloroform.
TiO.sub.2:SiO.sub.2: Titanium dioxide - silicon dioxide -
co-precipitate with 80 mol % TiO.sub.2, supplier; Akzo (DE)
Ti(OBu).sub.4: Titanium tetrabutylate SbAc.sub.3: Antimony
triacetate Color agent Co: Cobalt-II-acetate
Example 9
[0083] Effect of Excessive Wall Heat on Allyl Endgroup Content of
Polytrimethylene Terephthalate (Comparative)
[0084] The reactor used for these runs was electrically heated by
several heating rods imbedded in the reactor wall. The stirrer was
a helical ribbon with close tolerance (~1 mm) to the side walls,
which provides efficient mixing. A temperature-controlled column
allowed distillation of water and PDO. The reactor can be run under
pressure and high vacuum. Because of the electrical heating, the
wall temperatures were as high as 320.degree. C. in the first
trial. For the second trial, the wall temperatures were lowered to
285.degree. C.
[0085] For the first trial, three esterification products were made
as follows. The reactor was charged with 2417 gm TPA and 387 gm PDO
and heated to an internal temperature of 240.degree. C. (wall
temperature to 320.degree. C.) over a period of 1.5 hours. A total
of an additional 996 gm PDO was added in three portions over 4
hours at an internal temperature between about 256-266.degree. C.
and wall temperatures of 291-317.degree. C. and under nitrogen
pressure up to about 1 bar (column temperature 103-139.degree. C).
After a total of about 7 hours from initial heatup, about half of
the oligomer was discharged and the reactor cooled (water jacket).
The following day, 1200 gm TPA was charged to the oligomer in the
reactor and a total of 687 gm PDO was added in three portions over
about 2.5 hrs. Heat-up to 228.degree. C. (wall temperature
320.degree. C.) took about 1.5 hrs, and the reaction temperature
was about 266.degree. C. (wall temperature 294-305.degree. C.)
Total reaction time was about 4 hours. A third esterification
similar to the second was run the next day.
[0086] The resulting oligomer was polymerized as follows. Titanium
butoxide catalyst (1.3 gm, 80 ppm Ti) was charged to the cold
oligomer and the reactor was heated to 237.degree. C. internal
temperature (wall temperature up to 320.degree. C.) over about 1.5
hrs. Vacuum was applied over the next 30 minutes to reach 1.2 mbar,
and the reaction mixture was heated at 260-266.degree. C. (wall
temperature 286-308.degree. C., typically about 293-299.degree. C.)
for the next 5.7 hrs. under 0.3-1.0 mbar. Over the first 4 hrs.
under full vacuum, the power on the stirrer increased from about
1.23 to about 1.30 and then decreased to about 1.25 during the last
hour. The polymeric product was discharged from the reactor through
a die into a water bath but did not form a strand.
[0087] In the second trial, esterification was conducted similarly
to the first trial except that reactor wall temperature was limited
to 285.degree. C. The initial heatup to 240.degree. C. (wall
280.degree. C.) took about 2.3 hrs. and the reaction temperature
was about 244-256.degree. C. (wall 285.degree. C.) for the next 5.3
hrs. and then about 266.degree. C. for an additional 2 hrs. The
total reaction time from initial heatup was about 9.7 hrs. The next
day the second esterification was conducted similarly at a reaction
temperature of about 258-267.degree. C. (wall 281-285.degree. C). A
third esterification was not run for the second trial.
[0088] The polymerization was conducted similarly to that of the
first trial, except that the amount of oligomer was about 25% more
(to increase stirrer load), catalyst level was increased from 80 to
100 ppm (as Ti), and the wall temperature was again limited to
285.degree. C. The reaction was heated to about 256.degree. C.
(wall 285.degree. C.) over about 2.7 hrs at which time the vacuum
was 1.3 mbar. The reaction was continued at about 285-266.degree.
C. (wall 285.degree. C.) at between 0.2 and 1.2 mbar for an
additional 4.2 hrs. During this time the stirrer power (amps)
increased from about 1.25 to about 1.37 and declined to 1.33 during
the last hour. This time the product from the reactor was stranded
and pelletized. During the discharge, the reactor temperature was
lowered to about 240.degree. C.
[0089] The control polymer is typical PTT prepared similarly to the
procedure of Example 10 below in an oil-heated reactor at oil
temperatures of about 270.degree. C. or below and reaction
temperatures of about 245-265.degree. C. Compared to the control,
the polymers made using relatively high wall temperatures had lower
molecular weight (IV), very high carboxylic acid endgroups and very
high allyl endgroups (see Table B below).
[0090] The allyl endgroups are the result of thermal degradation of
the polymer. The relatively high levels of ally endgroups in the
polymers prepared in the electrically-heated reactor show that
extensive degradation occurred even though the bulk of the polymer
was generally at about 266.degree. C. or below. Less degradation
occurred when the wall temperature was reduced to 285.degree. C.,
but was still extensive.
3 TABLE B Allyl mole % COOH equiv./ton IV First trial Oligomer #1
0.6 363 #2 0.7 250 #3 0.6 243 Polymer 3.7 374 0.24 Second trial
Oligomer #1 1.0 386 #2 0.9 298 Polymer 1.7 55 0.58-0.63 Control
Polymer 0.6-0.8 10-20 0.65-0.68
Example 10
[0091] Melt Polymerization of High-I.V. Polytrimethylene
Terephthalate. (Comparative)
[0092] An oil-heated stainless steel reactor was charged with about
11.5 lbs 1,3-propanediol and about 19.3 lbs terephthalic acid, and
heated to about 260-265.degree. C. by means of a hot oil jacket
temperature of about 269.degree. C. under 10-60 psig nitrogen. The
aqueous distillate was removed over about 4 hours. To the
oligomeric product was added about 9.6 lbs 1,3-propanediol and
about 16.1 lbs terephthalic acid. The reaction was continued under
similar conditions for typically less than 3 hours to form a higher
molecular weight oligomer.
[0093] About half of this product was transferred to a second
reactor which has a dual spiral impeller arrangement. For
subsequent batches, 1,3-propanediol (9.6 lbs) and terephthalic acid
(16.1 lbs) were added to the oligomer remaining in the first
reactor and the oligomerization under pressure was repeated.
Titanium tetrabutoxide catalyst (100 ppm Ti based on final polymer)
was added as a solution in PDO/HOAc (catalyst preparation C) to the
second reactor, the reaction mixture was heated at 234.degree. C.
at an oil jacket temperature of about 250.degree. C., the pressure
was reduced to 0.2 mm Hg over about an hour to remove the excess
1,3-propanediol. After about 2 hours at full vacuum and 246.degree.
C. (260.degree. C. oil temperature), the molten polymer was
discharged from the reactor as strands, cooled and pelletized
(typically 17-19 lbs product). The melting point of the polymer was
227.8.degree. C., the carboxyl content was 17 eq/ton and the
intrinsic viscosity was 0.89.
[0094] Four additional batches prepared under similar conditions
produced polymers with maximum I.V.'s of about 0.86-0.87.
[0095] A similar preparation using 60 ppm Ti and temperatures of
263.degree. C. (oil 269.degree. C.) for esterification, 242.degree.
C. (oil 254.degree. C.) for vacuum pulldown and 252.degree. C. (oil
265.degree. C.) for polycondensation for 1.5 hrs gave polymer
maximum I.V. of 0.81.
[0096] Similar preparations with 40 ppm Ti under similar conditions
(with smaller charge to improve stirring) gave polymers with
maximum I.V.'s of 0.83, 0.86 and 0.87. Increasing the catalyst to
80 ppm gave maximum I.V.'s of 0.93 and 0.87 after about 1 hour of
polycondensation.
Example 11
[0097] Preparation of Polytrimethylene Terephthalate in the Melt
using a Disk Ring Autoclave
[0098] In the course of several batch polymerizations, a paste
consisting of about 99 kg PDO, 180 kg TPA, 14.4 g hindered phenol
stabilizer (80 ppm based on final polymer), 64.6 g neat (thus,
dilute liquid catalyst is not absolutely required) titanium
tetrabutoxide catalyst (50 ppm based on TPA), and 20 ppm Co (based
on TPA) as cobalt acetate bluing agent was added gradually over a
period of about 2 hours to 76 kg of stirred PTT oligomer ("heel")
that had been prepared essentially in the same manner as described
herein. The temperature of the oligomer heel was 281.degree. C.
(hot oil 297.degree. C.) at the beginning of the paste addition,
266.degree. C. after 30 minutes, and 245.degree. C. at the end of
the paste feed (oil 267.degree. C). The reaction pressure was
essentially atmospheric. After an additional reaction time of about
30 minutes of esterification, after which the temperature was
254.degree. C., 133.9 g phosphoric acid (25 ppm based on TPA) was
added to react with the cobalt agent and then 32.3 g neat titanium
tetrabutoxide catalyst (25 ppm) was added.
[0099] After this esterification step, a prepolymerization step was
conducted in which the pressure of the reactor was lowered from
about atmospheric to about 40 mbar and the reaction temperature was
about 256.degree. C. (oil 260.degree. C.) over about 30
minutes.
[0100] Samples of the esterification product and prepolymerization
product from a batch in this series showed about 0.2 mole % allyl
groups.
[0101] After the prepolymerization step, the oligomer was
transferred to a disk-ring, high surface area, reactor for
polycondensation. The pressure in this reactor was ramped down from
about 300 mbar to a final pressure of about 1 mbar over about 1
hour and then reduced further to about 0.5 mbar. The initial
reaction temperature was about 266.degree. C. and the final
temperature was about 264.degree. C. (oil temperature 255.degree.
C). After about 3 hours from the beginning of the vacuum reduction,
the polymer had reached the desired molecular weight and was
discharged and pelletized to yield about 225 kg product. Product
i.v. was 0.93. Allyl endgroup content was 0.4 mole %.
Example 12
[0102] Melt Polymerization
[0103] The polymerization of Example 11 was repeated except that a
titanium silicate catalyst (titanium dioxide/silicon dioxide
co-precipitate containing 80 mole % TiO.sub.2 was incorporated into
the PDO/TPA paste feed--50 ppm Ti, based on TPA--as the
esterification catalyst) was used for the esterification (50 ppm
Ti) and for polycondensation (80 ppm Ti). The reaction time for
polycondensation was about 3.5 hours. The product i.v. was 0.97 at
the beginning of discharge and 0.93 at the end of discharge.
Example 13
[0104] Melt Polymerization
[0105] The polymerization of Example 11 was repeated using neat
(thus, dilute liquid catalyst is not absolutely required) titanium
butoxide catalyst for esterification (50 ppm Ti) and after
esterification (80 ppm Ti). The hot oil temperature at the start of
esterification and addition of the TPA/PDO paste feed was reduced
to about 270.degree. C. compared to the higher initial hot oil
temperature used in Example 11, and the final temperature of the
esterification product was about 246.degree. C.; product
temperatures for the prepolymerization and polycondensation steps
were about 247 and 255-263.degree. C., respectively. The
polycondensation step was about 4 hours and the product i.v. was
about 1.10.
[0106] Similar polymerizations gave polymers of i.v. about 1.02,
1.05 and 1.05. Typical allyl endgroups in the polymer were 0.3 mole
%. Compared to Example 11, the lower melt temperature used in this
example produced polymer with higher molecular weight (i.v.).
Example 14
[0107] Melt Polymerization
[0108] Polymerization was conducted as in Example 13, except for: a
PDO/TPA mole paste feed ratio of about 1.3, 35 ppm Ti (titanium
butoxide) catalyst (as a solution in PDO with terephthalic acid;
catalyst preparation A) for esterification at about 2 bar pressure
absolute and 65 ppm Ti catalyst for polycondensation, 10 ppm Co,
about 260.degree. C. at the start of the feed for esterification
and final temperature of about 246.degree. C., 243-245.degree. C.
during prepolymerization and about 248-268.degree. C. during
polycondensation. The final product i.v. was about 1.07.
Filterability tests on the final product showed pressure rise of
about 108 bar-cm2/kg and filterability on prepolymer product
prepared in the subsequent batch prepared in essentially the same
manner was 148 bar-cm2/kg, both of which indicate some formation of
particles larger than about 20 microns.
Example 15
[0109] Melt Polymerization
[0110] Polymerization was conducted as in Example 14 using 15 ppm
Ti catalyst (catalyst preparation A) and higher reaction
temperatures during esterification, starting at 265.degree. C.,
keeping the reaction at or above about 253.degree. C. and ending at
about 260.degree. C., about 255-259.degree. C. for
prepolymerization and about 251-267.degree. C. for polycondensation
to form a product with i.v. of about 1.07. Filterability of the
prepolymerization and final products were about 6 and 45
bar-cm2/kg, respectively, indicating reduced formation of
particles.
[0111] Subsequent batches conducted essentially as in Example 14
showed prepolymer and final product filterabilities as low as about
2 and 8 bar-cm2/kg, respectively. Using titanium butoxide catalyst
formulation in PDO/isophthalic acid (catalyst preparation B) or in
PDO/acetic acid (catalyst preparation C) also gave good (low)
filterability values, often below about 10 bar-cm2/kg. Typical
allyl endgroup contents were 0.2-0.4 mole percent, and dipropylene
glycol units ranged from about 1.1 to about 1.7 mole percent
(0.6-0.9 weight percent).
Example 16
[0112] Examples 16-18 were prepared essentially as follows: in the
course of several batch polymerizations, a paste consisting of
about 99 kg PDO, 180 kg TPA (molar paste feed ratio about 1.3),
toner (in Example 17 - 15.2 gm cobalt acetate; 20 ppm Co based on
TPA; as 2% solution in PDO), 0.09 gm antifoam agent (0.5 ppm based
on polymer), and 19.8 gm titanium butoxide catalyst (15 ppm Ti
based on TPA; added as 2% solution in PDO/TPA or 7.3% solution in
PDO/acetic acid) was added gradually over a period of about 2 hours
to about 76 kg of stirred PTT oligomer ("heel") that had been
prepared essentially in the same manner as described herein. The
temperature of the oligomer heel was about 265.degree. C. at the
beginning of the paste addition and about 253.degree. C. at the end
of the paste feed. The reaction pressure was about 2 bar (absolute)
and about 50 minutes after the end of the paste feeding, the
pressure was reduced step-wise to about 1.8 bar over about 5
minutes, then to about 1.4 bar over about 5 minutes, and then to
about atmospheric pressure (1.0 bar) over about 5 minutes. After an
additional esterification time of about 1.3 to 1.5 hours after the
end of the paste feeding, after which the temperature was about 258
to 260.degree. C., 85.7 gm titanium butoxide catalyst (65 ppm Ti;
as solution in PDO/TPA or PDO/acetic acid) was added.
[0113] After this esterification step, a prepolymerization step was
conducted in which the pressure of the reactor was lowered from
about atmospheric to about 50 to 65 mbar and the reaction
temperature was about 255 to 257.degree. C. over about 30
minutes.
[0114] After the prepolymerization step, the oligomer was
transferred to a disk-ring, high surface area reactor for
polycondensation. The pressure in this reactor was ramped down from
about 300 mbar to a final pressure of less than 1 mbar over about
45 to 60 minutes. The reaction temperature was about 251 to
263.degree. C. After about 3 hours, the polymer had reached the
desired molecular weight and was discharged and pelletized to yield
about 210 to 230 kg product.
[0115] For Examples 16 and 18, the Co toner was replaced by blue (1
ppm based on polymer) and red (0.3 ppm) toners (Estafil),
respectively. For Examples 17 and 18, 14.4 gm of hindered phenol
stabilizer, methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (as
10% suspension in PDO; about 64 ppm based on final polymer or about
0.22 mmol/Kg), was added to the paste feed.
[0116] Endgroup analyses showed about 10 to 11 mequiv/Kg carboxyl
(COOH) endgroups for Examples 16-18. Allyl endgroups were about 0.3
mole.
Example 19
[0117] In Example 19, PTT was prepared similar to Examples 16-18
using a paste feed of about 99 kg PDO, 180 kg TPA, 144 gm of 10%
suspension of the hindered phenol stabilizer used in Example 17
(14.4 gm; about 64 ppm based on final polymer), 64.6 gm titanium
butoxide catalyst (50 ppm based on TPA), and 20 ppm Co (based on
TPA) as cobalt acetate toner added over about 2 hours to the
stirred PTT oligomer heel. The temperature of the heel was about
281.degree. C. at the beginning of the paste addition, 266.degree.
C. after 30 minutes, and 245.degree. C. at the end of the paste
feed. The reaction pressure was essentially atmospheric pressure.
After an additional esterification time of about 30 minutes, after
which the temperature was 254.degree. C., 133.9 gm phosphoric acid
(25 ppm based on TPA) was added to react with the cobalt toner and
then 32.3 gm titanium butoxide catalyst (25 ppm Ti based on TPA)
was added.
[0118] In the prepolymerization step, the pressure was lowered from
about atmospheric to about 40 mbar and the reaction temperature was
about 256.degree. C. over about 30 minutes. The polycondensation
was conducted at about 255 to 266.degree. C. to produce the desired
molecular weight and the product was discharged and pelletized to
yield about 225 kg.
Polymer Characteristics
[0119] The following study was undertaken to prepare PTT using DMT
according to literature conditions having very low DPG content. We
then compared the dyeability of these compositions to the all-melt
PTT composition and to the PTT composition made by conventional
technology with solid state polymerization. We also compared the
acrolein formation in aging experiments.
[0120] The results show that the all-melt PTT composition with
about 0.6 up to about 2 mole % DPG units is an optimum composition
range with better dyeing than the DMT-based products and,
surprisingly, equal to or better than the conventionally made TPA
PTT product having higher DPG. The results also show that acrolein
formation from the all-melt composition is less than from the
conventionally made TPA PTT composition with higher DPG content,
but the DMT-based products with very low DPG content show even less
acrolein.
[0121] Therefore, the structure of the all-melt PTT is an overall
or global optimum composition, having less acrolein formation than
the higher DPG compositions but still retaining very good
dyeability, which is compromised by the very low DPG compositions
made from DMT.
[0122] DPG content in the polymer was measured by proton NMR
(nuclear magnetic resonance) on polymer dissolved in a 50/50 by
volume mixture of deuterated trifluoroacetic acid and chloroform;
the methylene next to the ether oxygen of the DPG units has a
charateric triplet resonance at 3.9 ppm. The absolute mole percent
of DPG units in the polymer was determined using the integrated
value of the 3.9 ppm resonance compared to the integrated NMR
signals for the PDO and allyl units. The estimated precision was
+/-0.04 mole % (absolute). I.V. was measured in a solution of 0.4 g
polymer in 100 ml of a 60:40 solution of phenol:tetrachloroethan- e
at 30.degree. C. (or as a dilute solution in another solvent such
as hexafluoroisopropanol, and converted by known correlation to the
corresponding IV in 60:40 phenol:tetrachloroethane).
[0123] The following table summarizes the Examples and Comparative
Examples in this study:
4TABLE 1 Stab- IV DPG, mol % Example Lot # ilizer (R-100) (NMR) 16
P1242-5 no 0.89 1.64 17 P1214-14 yes 0.90 1.70 18 P1214- yes 0.92
1.30 See 39/40 discussion A 10ZPB002 yes 0.92 2.4 SSP product B
4-3B1-44-1 no 0.92 3.0 SSP product T-1 P1240-10 no 0.92 0.51 T-2
P1240-11 yes 0.91 0.48 T-3 P1240-14 no 1.08 0.55 High IV H-1
P1240-15 no 0.91 0.50 H-2 P1240-16 yes 0.91 0.21 H-3 P1240-12 no
0.91 0.22 50 ppm Ti H-4 P1240-13A yes 0.91 0.35 50 ppm Ti H-5
P1240-13 yes 0.92 0.11 50 ppm Ti; lower temp.
[0124] Example 18 is included in the data here for completeness but
considerable evidence suggests that this was an abnormal sample,
particularly with regard to spinning and dyeing. This sample had
been in storage for over a year. Tenacity data for this polymer
suggests that it spun abnormally. Unlike the other examples,
spinning of this material was difficult and only about 3 minute (or
less) bobbins could be made because of breaks in the fibers. An
extrusion film test of this material showed over 15,000 defects
compared to generally <7,000 defects for normal polymer samples,
indicating contamination of unknown origin. We believe that the
dyeing data for Example 18 is suspect.
[0125] Comparative Example A is the composition containing higher
DPG content prepared in a small commercial-scale plant under
conditions similar to Example C. It contained 0.025% Irganox 1076
(octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) which is
equivalent to about 138 ppm of the stabilizer used in Example 17
(or about 0.47 millimole/Kg). Note the higher level of stabilizer
compared to the other Examples. Allyl groups were about 0.3 mole
%.
[0126] Comparative Example B is a solid stated sample made in a
benchscale reactor without any hindered phenol stabilizer. This
sample was used in the aging studies only and was not spun or
dyed.
[0127] Comparative Example C is a typical preparation of high DPG
PTT. An oil-heated stainless steel reactor was charged with about
11.5 lbs. of 1,3-propanediol and about 19.3 lbs. of terephthalic
acid and heated to about 250 to 260.degree. C. at an oil jacket
temperature set point of about 265.degree. C. under 10 to 60 psig
nitrogen. The aqueous distillate was removed as the reaction
continued over about 4 hours. To the resulting oligomeric product
was added about 9.6 lbs. PDO and about 16.1 lbs. TPA, and the
reaction was continued under similar conditions for less than about
3 hours to form an oligomer with an average degree of
polymerization of about 4 to 8.
[0128] Approximately half of the oligomer was transferred to a
second reactor. For subsequent batches, PDO (9.6 lbs.) and
terephthalic acid (16.1 lbs.) were added rapidly to the oligomer
remaining in the first reactor and the oligomerization under
pressure was repeated. Titanium butoxide (Ti(OBu).sub.4) was added
as a solution in PDO/HOAc to the second reactor, the reaction
mixture was heated at about 231 to 235.degree. C. at an oil jacket
temperature set point of about 250.degree. C., the pressure was
reduced to less than 2 mm Hg, and the excess PDO was distilled off
over about 1 to 2 hours at full vacuum and about 240 to 250.degree.
C. (oil about 260.degree. C.) until the desired molecular weight
was achieved (i.v.=0.65 to 0.70). The molten polymer (about 20 lbs.
product) was discharged from the reactor as strands, cooled, and
pelletized. The polymers were advanced to higher molecular weight
(i.v. =0.90 to 0.94) by solid state polymerization by heating at
about 210 to 220.degree. C. under vacuum for about 4 to 5 hours or
more. The final polymer in this example contained about 3.7 mole %
DPG (by proton NMR).
[0129] Examples T-1, T-2 and T-3 were made in the same reactor as
Examples 16 and 17 using dimethyl terephthalate (DMT) using
conditions as close as practical to those described in Japanese
patent application 51-142097, filed Dec. 7, 1976, using about 2.2
molar feed ratio of PDO/DMT, and 100 ppm Ti catalyst (720 ppm
titanium tetrabutoxide added as solution in PDO/acetic acid). The
blue/red toners were also used, as in Example 16. Thus, for
Examples T-1 and T-2, the first reactor was charged with about 164
liters of 1,3-propanediol and the catalyst and heated to about
160.degree. C. Melted dimethyl terephthalate (DMT; about 200 Kg)
was added to the stirred mixture over about 90 minutes while
heating the mixture to about 177.degree. C. The esterification
reaction was continued for about 2 more hours while the temperature
was increased to about 217 to 222.degree. C. and methanol was
distilled overhead. Vacuum was applied to reduce the pressure to
about 60 to 70 mbar over about 1 hour and the reaction temperature
at the end of this period was about 242 to 249.degree. C. The
reactor contents were transferred to the high surface area reactor
and heated at about 244 to 255.degree. C. melt temperature (oil set
point 245.degree. C.) under vacuum (<1 mbar at the end of the
polycondensation) for about 4 to 4.5 hours to provide polymer with
the desired IV of about 0.92 for spinning. The polycondensation
time for T-3 was about 5.5 hours and because the IV was so high,
this sample was not spun. The hindered phenol stabilizer (17 gm;
about 80 ppm based on final polymer) was added to T-2 and T-3 as in
Example 2.
[0130] Examples H-1 and H-2 were made in the same reactor using
PDO/DMT feed ratio of about 1.4 under conditions as close as
practical to those described in U.S. Pat. No. 5,340,909 using 14
ppm Ti catalyst (100 ppm titanium tetrabutoxide added as a solution
in PDO/acetic acid) for the esterification step, and 450 ppm
butylstannoic acid (Fascat 4100) for the polycondensation step. The
catalyst amounts are based on DMT. Blue/red toners were used for
all the "H" examples. Example H-2 used hindered phenol stabilizer
as in Example T-2. Thus, the first reactor was charged with about
105 liters of 1,3-propanediol and the Ti catalyst and heated to
about 180 to 184.degree. C. Molten DMT (about 200 Kg) was added to
the stirred reactor over about 90 minutes and the esterification
reaction was continued for an additional time of about 2.5 to 3
hours while increasing the temperature to about 225.degree. C. and
distilling methanol overhead. The pressure was reduced to about 50
to 60 mbar over about 1 hour at a reaction temperature starting
about 228 to 237.degree. C. and raised to about 250 to 253.degree.
C. The tin catalyst was added to the oligomeric product and the
reactor contents transferred to the high surface area reactor.
Polycondensation was conducted at about 241 to 253.degree. C.
(final pressure of <1 mbar) for a total of about 3 hours to
reach the desired IV of about 0.92 for spinning. The
polycondensation times were determined by the time needed to
achieve 0.92 IV product rather than the times given in the
patent.
[0131] Examples H-3 and H-4 were run under modified conditions
similar to H-1 and H-2 but using 50 ppm Ti catalyst instead of 14
ppm in the esterification step. The reaction temperatures and times
were about 182 to 236.degree. C. over 3.3 to 4.5 hours (including
DMT feed) for the esterification, about 237 to 244.degree. C. and
about 30 minutes for the vacuum pulldown, and about 236 to
250.degree. C. (oil set point 245.degree. C.) and about 2.7 to 3
hours for polycondensa-tion to reach about 0.92 IV. Example H-5 was
conducted similar to H-3 and H-4 but using a lower temperature in
the esterification step (181 to 187.degree. C. for about 2.3 hours.
The temperature was then raised to about 220.degree. C. during the
vacuum pulldown and polycondensation was conducted at about 245 to
250.degree. C. for about 2.3 hours.
Spinning
[0132] The dried polymer chips were extruded and spun to make 80
and 150 denier partially oriented yarns (POY) using a 50-hole,
0.25/0.50 mm spinnerette and 245 to 255.degree. C. extruder zone
temperatures, 1500 to 1700 psi outlet pressure, 2.4 cc/rev melt
pump at about 12 rpm and 23 rpm (for 80 and 150 denier,
respectively), top and bottom godets at 4570 to 4580 m/min, type
SW4 winder at 4500 m/min, interlacer at 4 bar and 60 psi, quench
temperature 15.degree. C., and Lurol PT 7087 spin finish.
Generally, 10 and 30 minute bobbins were prepared at each
denier.
[0133] Samples of the POYs were drawn using 9 wraps at 280 m/min on
the first godet heated at 50.degree. C., 14 wraps at 400 m/min on
the second godet heated at 100.degree. C., and a 400 m/min
winder.
Dyeing procedure
[0134] The dyes were C.I. Disperse Blue 56 and 79. Disperse Blue 56
is a low energy dye with a small anthraquinone structure and a
molecular weight of 305 g/mole. Disperse Blue 79 is a high energy
monoazo dye with larger molecular size than Disperse Blue 56 and a
molecular weight of 639 g/mole. The POY samples were dyed in one
set of experiments and the drawn yarns were dyed separately in
another set of experiments.
[0135] Yarns from each example were single knit to form fabrics
using a Lawson-Hemphill Model FAK sample knitting machine. All
fabrics (POY or drawn) from different examples with the same denier
were dyed together. The competitive dyeing was performed with 0.5%
owf (on weight of fabric) of either Disperse Blue 56 or Blue 79 at
20:1 liquor ratio using an AATCC Standard Atlas Launder-Ometer.
Dyebath temperature was raised at 2.degree. C./min from ambient to
100.degree. C. and held for 45 minutes. The dyed fabrics were water
rinsed and air dried.
[0136] After dyeing, the dye uptake was evaluated and compared by
their K/S values at the wavelength with maximum absorbance, which
is broadly used as a description of shade depth and is directly
proportional to dye concentration on the fiber if the shade depth
is not too high. Color differences between the yarns were measured
by their CIELab values. To describe the differences of K/S and
CIELab values among the yarns, % K/S and Delta E values were
calculated using the yarn with the highest shade depth, i.e.,
Example 16 for both deniers, as the standard. Color measurement
used a BYK Gardner Model TCS spectrophotometer. Generally, a Delta
E larger than 0.5 or a % K/S difference larger than 5% indicated a
visual color difference.
[0137] Comparing the K/S values between yarns with different
denier, 150 denier was dyed darker than 80 denier, probably due to
the larger diameter of the fiber and yarn of the 150 denier
materials.
[0138] Delta E (.DELTA.E) is the overall color difference (see T. L
Vigo, "Textile Processing and Properties," Elsevier, 1994, p.
330-331) between Example 16 and the compared sample and is
calculated as
[(L*s-L*r).sup.2+(a*s-a*r).sup.2+(b*s-b*r).sup.2].sup.1/2, where
L*, a* and b* are the measured Cielab color values and s and r are
the sample and the reference (Example 1), respectively. The larger
the value of .DELTA.E, the larger the difference in color compared
to the reference sample, viz. higher .DELTA.E values indicate less
dye uptake than Example 16.
[0139] K/S or "shade depth" is a measure of the opacity and
reflectance (see Vigo) and is defined as (1-R).sup.2/2R, where R is
the reflectance and S is the scattering coefficient. For Blue 56,
the reflectance measurement was made at 630 nm and for Blue 79 the
measurement was made at 610 nm. % K/S is the relative magnitude
compared to the reference sample (Example 16).
Dyeing results for drawn yarns
[0140]
5TABLE 2 80 Denier With Blue 56 Example Denier L* a* b* Delta E K/S
630 nm % K/S Process % DPG 16 82 48.34 -6.95 -32.65 0.00 5.815 100%
TPA melt 1.64 17 77 47.88 -6.76 -32.69 0.50 5.961 103% TPA melt 1.7
A 78 48 -6.85 -33.7 1.11 6.157 106% TPA SSP 2.4 T-1 78 49.43 -9.45
-28.64 4.85 5.264 91% DMT 0.51 T-2 82 48.93 -9.72 -28.63 4.92 5.511
95% DMT 0.48 H-1 82 50.61 -5.87 -34.61 3.19 5.013 86% DMT 0.5 H-2
80 50.8 -5.59 -34.87 3.58 4.934 85% DMT 0.21 H-3 82 48.9 -6.11
-34.31 1.94 5.71 98% DMT 0.22 H-4 82 52.05 -7.04 -32.7 3.71 4.457
77% DMT 0.35 H-5 82 51.92 -7.14 -32.51 3.59 4.487 77% DMT 0.11
[0141] Table 2 shows the dyeing results for 80 denier drawn yarns
with Blue 56 dye. Example 16 and 17 were the darkest (.DELTA.E 0.0
and 0.5, respectively). Based on .DELTA.E, all the other fibers,
including Example A, did not dye as well. Based on % K/S, Examples
16, 17 and A were similar and all the DMT-based polymers were
lighter, although H-3 was almost as high as Ex. 16.
[0142] Table 3 shows similar results for Blue 79 dye. Again,
Example 16 is darkest overall (.DELTA.E=0.0) compared to the
others, including Example 17 and A. In terms of % K/S, Example 16
and 17 are the best, Example A is next best, and all the other
samples are not as good.
6TABLE 3 80 Denier With Blue 79 Example Denier L* a* b* Delta E K/S
610 nm % K/S Process % DPG 16 82 42.16 -5.56 -23.71 0.00 5.997 100
TPA melt 1.64 17 77 44.83 -6.42 -23.69 2.81 5.132 85.6 TPA melt 1.7
A 78 46.13 -6.56 -24.13 4.12 4.741 79.1 TPA SSP 2.4 T-1 78 45.19
-6.42 -23.3 3.18 4.944 82.4 DMT 0.51 T-2 82 47.26 -6.58 -23.1 5.24
4.261 71.1 DMT 0.48 H-1 82 46.63 -6.38 -23.05 4.59 4.417 73.7 DMT
0.5 H-2 80 47.1 -6.41 -22.89 5.08 4.256 71 DMT 0.21 H-3 82 47.04
-6.32 -23.12 4.97 4.28 71.4 DMT 0.22 H-4 82 47.78 -6.53 -23.17 5.73
4.112 68.6 DMT 0.35 H-5 82 47.87 -6.5 -23.05 5.82 4.07 67.9 DMT
0.11
[0143] The results at 150 denier appear to be generally similar
although somewhat less definitive results in that occasionally a
DMT-based sample gives % K/S similar to or higher than Example 16.
However, Example 16 is still the darkest based on .DELTA.E. See
Tables 4 and 5.
7TABLE 4 150 Denier With Blue 56 Example Denier L* a* b* Delta E
K/S 630 nm % K/S Process % DPG 16 152 42.6 -5.49 -33.54 0.00 8.889
100% TPA melt 1.64 17 140 42.58 -5.61 -33.61 0.14 8.96 100.8% TPA
melt 1.7 3 150 42.96 -6.05 -32.79 1.00 8.614 96.9% TPA melt 1.3 A
152 43.58 -5.4 -34.52 1.39 8.491 95.5% TPA SSP 2.4 T-1 152 41.72
-8.01 -29.75 4.64 9.31 104.7% DMT 0.51 T-2 152 42.73 -8.07 -29.7
4.63 8.58 96.5% DMT 0.48 H-1 151 43.84 -3.74 -35.88 3.17 8.117
91.3% DMT 0.5 H-2 152 44.53 -3.67 -35.89 3.54 7.656 86.1% DMT 0.21
H-3 153 43.48 -4.41 -34.82 1.89 8.268 93.0% DMT 0.22 H-4 152 44.33
-4.67 -35.01 2.41 7.865 88.5% DMT 0.35 H-5 152 44.3 -4.69 -34.6
2.16 7.764 87.3% DMT 0.11
[0144]
8TABLE 5 150 Denier With Blue 79 Example Denier L* a* /b* Delta E
K/S 610 nm % K/S DPG 16 152 40.97 -5.54 -24.54 0.00 6.751 100 TPA
melt 1.64 17 140 41.2 -5.52 -24.84 0.38 6.686 99 TPA melt 1.7 3 150
42.89 -5.8 -24.7 1.94 5.93 87.8 TPA melt 1.3 A 152 43.38 -5.74
-25.43 2.58 5.812 86.1 TPA SSP 2.4 T-1 152 40.17 -5.37 -24.93 0.91
7.214 106.9 DMT 0.51 T-2 152 40.97 -5.52 -24.75 0.21 6.785 100.5
DMT 0.48 H-1 151 43.26 -5.76 -24.34 2.31 5.697 84.4 DMT 0.5 H-2 152
43.46 -5.76 -24.22 2.52 5.59 82.8 DMT 0.21 H-3 153 42.35 -5.63
-23.92 1.52 5.996 88.8 DMT 0.22 H-4 152 43.31 -5.75 -24.25 2.37
5.648 83.7 DMT 0.35 H-5 152 43.89 -5.76 -24.15 2.95 5.406 80.1 DMT
0.11
[0145] Generally, the data shows that not only does the composition
of the Invention (Examples 16 and 17) dye better than the DMT-based
polymers with low DPG content, but also the Invention composition
dyes better than the TPA-based polymer with higher DPG content.
Thus, the Invention compositions with about 0.6 to about 1.9 mole %
DPG, represent optimum compositions in terms of dyeability.
Results on POY yarns
[0146] Tables 6 to 9 show the data for POY samples. Overall, the
results are similar to the drawn samples. In every case, Example 16
has the lowest .DELTA.E and generally the highest % K/S compared to
the DMT-based polymers and compared to the current SSP product.
Note that data for Example 18 is included, although we believe this
is not representative of the properties of the polymer of the
invention for reasons previously stated.
9TABLE 6 80 Denier POY With Blue 56 Example L* a* b* Delta E K/S
630 nm % K/S Process % DPG 16 42.04 -5.03 -34.33 0.00 9.486 100 TPA
melt 1.64 18 44.04 -3.44 -37.13 3.79 8.373 88.3 TPA melt 1.3 A
43.55 -5.83 -33.79 1.79 8.511 89.7 TPA SSP 2.4 T-1 44.04 -3.4
-37.01 3.72 8.339 87.9 DMT 0.51 T-2 44.46 -8.13 -30.61 5.41 7.75
81.7 DMT 0.48 H-1 45.3 -4.69 -35.75 3.57 7.56 79.7 DMT 0.5 H-2
44.55 -4.49 -36.09 3.11 8.078 85.2 DMT 0.21 H-3 42.99 -5.46 -35.17
1.34 9.293 98 DMT 0.22 H-4 44.83 -4.71 -35.48 3.03 7.764 81.8 DMT
0.35 H-5 44.34 -8.25 -30.51 5.50 7.861 82.9 DMT 0.11
[0147]
10TABLE 7 80 Denier POY With Blue 79 Example L* a* b* Delta E K/S
610 nm % K/S Process % DPG 16 41.24 -6.17 -24.11 0.00 6.759 100 TPA
melt 1.64 18 42.78 -5.73 -23.95 1.61 5.876 87 TPA melt 1.3 A 43.16
-6.39 -24.79 2.05 6.015 89 TPA SSP 2.4 T-1 43.92 -5.71 -23.09 2.90
5.286 78.2 DMT 0.51 T-2 42.31 -6.41 -24.6 1.20 6.377 94.3 DMT 0.48
H-1 44.02 -5.57 -23.36 2.94 5.259 77.8 DMT 0.5 H-2 43.39 -5.6
-23.62 2.28 5.545 82 DMT 0.21 H-3 42.84 -6.42 -25.14 1.92 6.242
92.4 DMT 0.22 H-4 44 -5.84 -23.67 2.81 5.349 79.1 DMT 0.35 H-5
42.57 -6.41 -24.5 1.41 6.233 92.2 DMT 0.11
[0148]
11TABLE 8 150 Denier POY With Blue 79 Example L* a* b* Delta E K/S
630 nm % K/S Process % DPG 16 38.75 -3.64 -35.11 0.00 12.085 100%
TPA melt 1.64 18 40.88 -4.88 -34.22 2.62 10.224 84.6% TPA melt 1.3
A 40.86 -3.76 -36.62 2.60 10.798 89.4% TPA SSP 2.4 T-1 41.33 -7.29
-31.25 5.91 9.822 81.3% DMT 0.51 T-2 39.2 -6.66 -31.33 4.86 11.377
94.1% DMT 0.48 H-1 40.15 -1.38 -38.56 4.36 11.237 93.0% DMT 0.5 H-2
43.04 -2.59 -38.11 5.34 9.122 75.5% DMT 0.21 H-3 41.31 -3.08 -36.73
3.08 10.152 84.0% DMT 0.22 H-4 41.91 -3.09 -37.13 3.79 9.784 81.0%
DMT 0.35 H-5 43.11 -3.39 -37.27 4.87 9.043 74.8% DMT 0.11
[0149]
12TABLE 9 150 Denier POY With Blue 79 Example L* a* b* Delta E K/S
630 nm % K/S Process % DPG 16 38.9 -5.49 -24.82 0.00 8.039 100.0%
TPA melt 1.64 18 39.98 -5.67 -25.11 1.13 7.486 93.1% TPA meIt 1.3 A
42.93 -5.95 -26.44 4.37 6.289 78.2% TPA SSP 2.4 T-1 41.21 -5.78
-24.66 2.33 6.76 84.1% DMT 0.51 T-2 41.94 -5.88 -24.9 3.07 6.459
80.3% DMT 0.48 H-1 41.61 -5.36 -24.59 2.72 6.436 80.1% DMT 0.5 H-2
42.85 -5.59 -24.34 3.98 5.873 73.1% DMT 0.21 H-3 42.4 -5.5 -24.24
3.55 6.037 75.1% DMT 0.22 H-4 39.72 -5.14 -24.13 1.13 7.31 90.9%
DMT 0.35 H-5 42.93 -5.47 -24 4.11 5.775 71.8% DMT 0.11
Acrolein generation--aging study
[0150] Aging experiments were conducted to determine the stability
of the polymer. Four-gram polymer pellets were placed in a
forced-air drying oven and the temperature was set at 170.degree.
C. (independently checked by pyrometer). The tests were done at
170.degree. C. to accelerate the test. At normal temperatures, the
acrolein formation would be much slower. Periodically, a sample was
removed after the aging time specified in Table 13 and analyzed.
The acrolein was measured by headspace gas chromatography on
pellets after heating the sample under air at 200.degree. C. for 40
minutes. Results are reported as ppm based on polymer weight.
[0151] Intrinsic viscosity was measured in hexafluoro-isopropanol
and converted by known correlation to the corresponding values for
60/40 phenol/tetrachloroethane solvent at 30.degree. C. The DPG
content was measured by proton NMR (nuclear magnetic resonance) on
polymer dissolved in a 50/50 volume mixture of deuterated
trifluoroacetic acid and chloroform. The methylene next to the
ether oxygen shows a characteristic resonance at 3.9 ppm and is
reported as mole % of total PDO plus DPG units and wt % of
polymer.
[0152] Table 10 shows the results for the samples made without
hindered phenol stabilizer. It is clear that the polymers with low
DPG content produce less acrolein. The polymer with the highest DPG
(Example B) shows the highest acrolein generation early in the
aging. The DMT-based polymers with very low DPG show very low
acrolein generation even after 27 days, again showing that the
acrolein generation is related to DPG level. The polymers of the
Invention (Example 16) with moderate DPG level show somewhat higher
acrolein formation than the DMT-based polymers.
[0153] The compositions of this Invention should thus require less
stabilizer to suppress acrolein formation compared to compositions
with higher initial DPG content.
13TABLE 10 Acrolein Formation (ppm) After Acting at 170.degree. C.
(no stabilizer) Days 16 B T-1 H-1 H-3 1 170 188 17 7 6 3 192 205 16
27 16 8 159 150 24 28 19 12 157 148 25 30 21 17 113 92 20 28 15 21
94 65 22 27 16 27 89 58 20 25 12 Initial DPG (%) 1.6 3 0.51 0.5
0.22
[0154] Table 11 shows the change in DPG content as the polymers
were aged at 170.degree. C. The decrease in DPG, which is due to
oxidation of DPG to acrolein, is highest for the polymers with the
highest initial DPG content. Thus, the decrease in DPG for Example
B is almost 1% (from 3 to 2%) compared to about 0.66% loss for
Example 16.
14TABLE 11 Change in DPG (mole %) 1 3 8 12 17 21 27 Overall Example
stabilizer unaged day days days days days days days change 16 no
1.64 1.61 1.56 1.27 1.06 0.97 0.94 0.98 -0.66 B no 3 3.2 2.92 2.52
2.14 2.48 2.28 2.03 -0.97 T-1 no 0.51 0.46 0.54 0.52 0.44 0.44 0.43
0.48 -0.03 H-1 no 0.5 0.42 0.52 0.5 0.43 0.41 0.42 0.39 -0.11 H-3
no 0.22 0.22 0.24 0.25 0.19 0.25 0.19 0.19 -0.03
[0155] Table 12 shows the change in IV during the aging study. Note
that the DMT-based examples show less IV change, even without
stabilizer. In some cases, the change is near the potential error
of the IV measurements, so the effect of stabilizer at these low
DPG levels is very small, at best. Overall, the results are
completely consistent with generation of acrolein by oxidation of
DPG units, which results in chain cleavage and lower IV.
15TABLE 12 IV Data on Aged Samples Example Stabilizer Initial IV IV
@ 27 days Change* 16 No 0.89 0.63 0.26 18 Yes 0.92 0.81 0.11 A Yes
0.92 0.81 0.11 B No 0.92 0.74 0.18 T-1 No 0.92 0.87 0.05 T-2 Yes
0.91 0.89 0.02 H-1 No 0.91 0.84 0.07 H-2 Yes 0.91 0.83 0.08 H-3 No
0.91 0.87 0.04 H-4 Yes 0.91 0.86 0.05 H-5 yes 0.92 0.86 0.06 *Total
error can be +/- 0.04 because error for each IV measurement is +/-
0.01.
[0156]
16TABLE 13 Acrolein Generation (ppm) after Aging at 170.degree. C.
(with hindered phenol stabilizer) Days Example 17 Example 19 1 13 9
3 13 8 8 72 13 12 242 22 17 171 28 21 126 38 27 102 12-30 Initial
DPG (%) 1.7 0.6
* * * * *