US005656716A

United States Patent (19) 11 Patent Number: 5,656,716

Schmidt et al. 45) Date of Patent: Aug. 12, 1997
54 TITANIUM-CONTAINING CATALYST AND 56) References Cited
PROCESS FOR THE PRODUCTION OF U.S. PATENT DOCUMENTS
POLYESTER
3,862,087 1/1975 Heller et al. ............................ 528/186
75) Inventors: Wolfgang Schmidt, Heylstrasse; Ulrich 4,031,165 6/1977 Saiki et al. ............................ 525/444
Thiele, Bruchkoebel; Wolf-dieter 4,365,054 12/1982 Stabley, Jr. ............................. 528/.277
Griebler, Moers; Bernd Hirthe, 4,483,970 11/1984 Huntjens et al. ....................... 525/440
Toenisvorst; Elke Hirschberg, Moers, 4,611,049 9/1986 Kuratsuji et al. ....................... 528/279
all of Germany Primary Examiner Terressa Mosley
Attorney, Agent, or Firm-McDonnell Boehnen Hulbert &
(73) Assignees: Zimmer Aktiengesellschaft, Frankfurt; Berghoff
Sachtleben Chemie GmbH, Duisburg, 57 ABSTRACT
both of Germany
21 Appl. No.: 617,562 The present invention comprises a new catalyst for the
production of polyesters consisting essentially of a finely
22 Filed: Mar 19, 1996 dispersed, large surface area titanium compound selected
30 Foreign Application Priority Data from hydrated TiO2 obtained by hydrolysis and having the
composition yTiOzHO and from titanates having the
Apr. 7, 1995 (DE) Germany ........................ 19513 056.1 composition (MeO)(TiO2),(H2O), wherein Me is an
(51) int. Cl. ... C08G 64/00 alkaline earth metal or alkali metal. In addition, the present
52 U.S. Cl. .......................... 528/279; 528/176; 528/193; method comprises a process for the production of polyesters
528/194; 528/272; 502/150; 502/300; 502/349; using this catalyst as an esterification or transesterification
502/350
catalyst and as a polycondensation catalyst, whereby a
58 Field of Search .................................... 528/272, 279,
phosphorous-oxygen-compound is added immediately
before, during, or after the polycondensation.
528/176, 193, 194; 502/300, 349,350,
150 11 Claims, No Drawings
 5,656,716
1. 2
TITANUM-CONTAINING CATALYST AND vapors, which should be recycled within the polyester pro
PROCESS FOR THE PRODUCTION OF cess. The necessity to freshly produce the catalyst immedi
POLYESTER ately before its use, i.e., to have to construct a catalyst plant
in addition to the polyester plant, is disadvantageous in both
BACKGROUND CSS.
1. Field of the Invention The use of various titanium salts, e.g., lithium or sodium
The invention relates to a titanium-containing catalyst titanate is disclosed in U.S. Pat. No.3.965,071. As polyester
with high catalytic activity for the production of polyester, with severe discoloration and very high diethylene glycol
whereby the catalytic activity is not reduced by the water 10
content is otherwise produced, the titanium catalyst must be
formed during esterification. The invention also relates to a completely deactivated after the esterification by addition of
process for the production of thermostable, perfectly colored phosphorous compounds, and the polycondensation contin
polyesters with an ether-content as low as possible by ued in the presence of other catalysts like antimony com
esterification or transesterification and subsequent polycon pounds or the very expensive germanium compounds. U.S.
densation in the presence of this titanium-containing cata Pat. No. 4.365,054 discloses alkali titanates of the formula
lyst. 15
(MO)(TiO), wherein n=0.05 to 25 and M is an alkali
2. Summary of the Related Art metal, as catalyst of esterification as well as catalyst of
Generally, polyesters are produced by reaction of a diol polycondensation for the production of polyester. The high
with a dicarboxylic acid or a lower alkyl ester of a dicar est catalytic activity is achieved with n=3 to 5, but the ether
boxylic acid, e.g., the dimethylester. At first, the correspond content of the polyester is relatively high, for example 1.33
20 wt. 96. for lithium titanate and 2.15 wt.% for sodium
ing dicarboxylic acid diester is formed, which is then
polycondensed at increasing temperature and reduced titanate. The titanates are obtained by melting together alkali
pressure, whereby diol and water are split off. Both reaction carbonate and TiO2. The crystallite size and the particle size
are not disclosed.
steps need catalysts or are at least accelerated by them.
Titanium compounds are suitable catalysts for the 25 SUMMARY OF THE INVENTION
esterification, compounds of Mn, Co or Zn for the
transesterification, and compounds of Sb, Ti, Pb, Ge, Zn or In light of the foregoing, the object of the present inven
Sn for the polycondensation, whereby the compounds are in tion is to improve the known titanium-containing catalysts,
general oxides, alcoholates, acetates, or carboxylates. The so that the previously mentioned disadvantages do not occur
amount of metal in the catalyst ranges mostly between 20 30 or at least occur to a lesser extent. The object of the
and 500 ppm, based on polyester. invention concerns also the production of polyester with
Among these catalysts the titanium compounds are the these improved catalysts.
most effective and the most widely usable because they are These objects are achieved according to the invention by
absolutely non-poisonous and can be used for the esterifi a novel catalyst and process for synthesizing polyester using
cation or transesterification as well as for the polyconden 35 this catalyst. The catalyst consists of a finely dispersed, large
sation. Only for polyethylene terephthalate (PET) is the use surface area titanium compound selected from hydrated
of co-catalysts necessary to avoid discoloring. The use of the titanium dioxide obtained by hydrolysis and having the
titanium as catalyst takes place mainly in the form of composition
alcoholates, but the use of titanium salts is also described. yTiOzHO
However, the frequently used titanium alcoholates are
known to be hydrolyzed during the esterification stage by wherein
the water formed there, and by this to be catalytically y=1, and
inactivated, which makes a further addition of catalyst in the
polycondensation and generally high amounts of catalyst Z=0.01 to 2,
necessary. 45 and from titanates having the composition
There are no definite reports on the catalytic activity of
TiO, but in general it is assumed to be to a large extent
catalytically inactive. TiO2 is used, in addition to usual wherein
catalysts, in large quantities, mostly in the anatase form in Me=Li, Ha, K. Rb, Cs, Mg, Ca, Sr or Ba,
the PET fiber production as a delustering agent and as a 50
n=1 for Me-alkaline earth metal, and
white pigment. The usual concentrations are 0.1 to 3 wt.%
TiO/PET. In the process of U.S. Pat. No. 2,906.737, TiO, n=2 for Me=alkali metal,
is used in the rutile formin quantities of 0.01 to 5 wt.%TiO, x=0.0001 to 6,
as an esterification and polycondensation catalyst. The y=1, and
esterification time of more than 7 hours is a distinct draw 55 z=0.01 to 2,
back of this method, however. According to U.S. Pat. No. having a particle or aggregate size and a specific surface area
3.056,817. a titanium dioxide gel obtained by alkaline within a desired range.
precipitation and consisting of about 5 wt.% TiO, and 95
wt.% water is used in quantities of 0.01 to 10 wt.%, based DETALED DESCRIPTION OF THE
on dicarboxylic acid as catalyst for the esterification stage. PREFERRED EMBODMENTS
However, the catalytic activity of titanium dioxides pro The present invention provides a novel catalyst and
duced in this way is very low. In the process of U.S. Pat. No. process for synthesizing polyester using this catalyst. The
3,463,742, freshly precipitated titanium dioxide hydrate is catalyst consists of a finely dispersed, large surface area
freed from residual water, dispersed in butanol, and the titanium compound selected from hydrated titanium dioxide
suspensioninbutanol (with 2 to 20 wt.%Ti) used as catalyst 65
obtained by hydrolysis and having the composition
for the transesterification and polycondensation of polyester.
Thereafter, however, the butanol contaminates the reaction yTiOzHO
 5,656,716
4
wherein to 100 ppm titanium, based on dicarboxylic acid, can be
y=1, and optionally added at the beginning of the polycondensation.
z=0.01 to 2, preferably 0.15 to 1.0, For polyesters, like polyethylene terephthalate, which can be
and from titanates having the composition esterified without a catalyst, the total amount of the titanium
catalyst alternatively can be added immediately before or at
(MeO).(TiO2)(H2O). the beginning of the polycondensation. In none of these
processes are other additional catalysts required.
wherein A phosphorous-oxygen-compound, like phosphoric acid,
Me=Li, Na, K, Rb, Cs, Mg, Ca, Sr or Ba, esters of phosphoric acid or of phosphorous acid, phospho
n=1 for Me=alkaline earth metal, and 10 nates orphosphonites, is added at any time after the comple
tion of the esterification. This additive has only a negligibly
n=2 for Me=alkali metal, small influence on the catalytic activity of the titanium
x=0.0001 to 6, preferably 0.001 to 0.5, and most prefer catalyst. However, its effect on the oxidative and thermo
ably 0.02 to 0.04. oxidative stability and on the color of the polyester are
y=1, and 15 advantageous.
z=0.01 to 2, preferably 0.3 to 0.7, In comparison to the preceding cited prior art, the
and wherein a large surface area means a crystallite size of improved catalytic activity of the catalyst of the invention
not more than 100 nm, preferably of less than 10 nm, and the distinctly reduced side reactions during polyester
corresponding to a specific surface area of more than 10 production may be due primarily to its extremely finely
m?g, preferably of more than 100 m/g and finely dispersed 20 dispersed and large surface area structure. The water content
means a particle or aggregate size of less than 10 um, of the titanium catalyst and the addition of a phosphorous
preferably of not more than 1 Jum. A large surface can also compound during the polyester production have a certain
mean that the catalysts are amorphous with respect to X-rays, influence, too. In this regard, it is unimportant if the
i.e., that the crystallite size is below the limit of detection by titanium-catalyst is added to the reaction components as a
x-ray diffraction. In the following, this catalyst is generally 25 fine powder or as a suspension in the polyester-forming diol.
called titanium catalyst. Before its use, especially after a longer period of storage, the
In the production of polyesters or co-polyesters by esteri titanium-catalyst suspension may be again finely dispersed
fication of at least one diol with at least one dicarboxylic by means of a mill, e.g., a ball-mill.
acid or transesterification of the diols with the dicarboxylic Titanium compounds having the same chemical formula
acid dialkyl esters, and subsequent single- or multiple-step 30 are known. However, the outstanding catalytic activity in the
polycondensation, the esterification or the transesterification polyester synthesis is new and unexpected and is believed to
is carried out in the presence of a quantity of this titanium result from a unique crystallite structure of the catalyst,
catalyst corresponding to 0 to 1000 ppm, preferably 10 to which, in turn, results from the hydrolysis of TiO(SO)
1000 ppm, most preferably 20 to 300 ppm titanium, based on solely in water. The hydrolysis of other titanium compounds
dicarboxylic acid, and the subsequent polycondensation in 35 with water or alkaline solutions leads to titanium compounds
the presence of a total amount (including the esterification that may have similar overall chemical composition but
catalyst) of this titanium catalyst corresponding to 20 to differin crystallite structure and, therefore, are not suited (or
1000 ppm, preferably 30 to 500 ppm, most preferably 40 to less suited) as polyester catalysts.
400 ppm titanium, based on dicarboxylic acid, whereby These catalysts, which are so excellently suited for poly
immediately before or during or after the polycondensation ester synthesis, are produced by hydrolysis, preferably ther
a phosphorous-oxygen-compound is further added to the mal hydrolysis (exclusively with water) of titanyl sulfate
polycondensation mixture in a quantity corresponding to 10 (TiOSO) and thereafter, depending on the desired alkali or
to 200 ppm, preferably 20 to 100 ppm phosphorus, based on alkaline-earth content, either
dicarboxylic acid. a) removal of excess acid by washing or by neutralization
The diols on which the polyester is based are alkanediols 45 and washing and optionally drying, or
or cycloalkanediols with 2 to 12 carbon-atoms, especially b) reaction with alkalihydroxide or alkaline earth hydrox
ethylene glycol, 1.3 -propanediol, 1,4-butanediol, 14 ide at ambient temperature up to boiling temperature,
cyclohexanedimethanol or mixtures thereof, and the dicar Washing and optionally drying, or
boxylic acids are aryldicarboxylic acids or cycloalkyldicar c) reaction with alkali-hydroxide or alkaline earth hydrox
boxylic acids, like terephthalic acid, isophthalic acid, 50 ide at ambient temperature up to boiling temperature,
naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic washing, partial reaction with mineral acid or carboxy
acid, 14-cyclohexanedicarboxylic acid or mixtures thereof. lic acid, preferably sulfuric acid, again washing and
Terephthalic acid is preferred as a main component. optionally drying.
The polyester is produced at usual conditions of tempera For example, catalytically active hydrated TiO, with an
ture and pressure in conventional reactors. In addition to the 55 extremely low Na-contentis obtained by thermal hydrolysis
titanium catalyst of the invention, the usual additives, like of a solution of titanyl sulfate (corresponding to 200 g
branching agents, delustering agents, coloring agents and TiO/I) with water at 105° C., subsequent washing until a
other agents, can be added to the reaction mixture. residual sulfuric acid content of 7 wt.% is obtained, adjust
Surprisingly the present titanium catalyst, in comparison ing of the suspension to a concentration of about 330 g
to U.S. Pat. No. 4.365,054, resulted in the same or higher TiO2/1, neutralization of the suspension with a 50 wt.%
catalytic activity in polyethylene terephthalate with lower solution of sodium hydroxide with stirring until a constant
ether content and distinctly reduced COOH-end group pH is reached, washing until a conductivity of the suspen
concentration, both properties which are of importance for sion of less than 300 S/cm is obtained, and finally drying.
the thermal stability and the processing ability of the poly Catalytically active sodium titanate with high Na-content
ester. The titanium catalyst is added at the beginning of the 65 is obtained, for example, if the suspension prepared as
esterification or transesterification, and a further quantity of described before (with a residual sulfuric acid content of 7
the catalyst corresponding to 10 to 250 ppm, preferably 30 wt.%) is mixed in a volume ratio of a)250 parts suspension
 5,656,716
5 6
containing 320 gTiO2/1, (b) 200 parts of a 50 wt.% solution each example, 42.5 parts by wt. of this product were
of sodium hydroxide, and (c) 200 parts of water, the mixture rendered molten under a nitrogen atmosphere together with
heated to boiling and kept boiling for 2 hours, the formed a titanium catalyst of the invention in an amount correspond
sodium titanate washed until a residual NaOH content of ing to 105 ppm. Ti/TPA (i.e., Ti based on TPA). In example
less than 3 g/l in the washing water is obtained, and the 6 an antimony triacetate catalyst in an amount of 170 ppm
resulting composition dried. Ti/TPA was used for comparison. As soon as the product was
Catalytically active sodium titanate with intermediary molten, triphenyl phosphate in an amount corresponding to
Na-content is formed, for example, if the titanate with high 76 ppm P/TPA was added (except in examples 6 and 13 to
Na-content described before having a solid content of the 15) and precondensation started at about 270° C. and step
suspension of 10 wt.% is adjusted before drying to a pH 10 wise reduced pressure (200 and 50 mbar). After a residence
value of 3 with 30 wt.% sulfuric acid and readjusted again time of 60 to 70 min the pressure was reduced to <1 mbar
to pH 3 after a dwell time of 30 minutes. The acid-treated and the mixture polycondensed at 275-285°C. for 180 min.
suspension is washed until a conductivity of less than 1000 The results are presented in Table 2.
S/cm in the filtrate is obtained, and it is thereafter dried. As is clear, the catalytic activity of the catalysts of
The shelf life of these titanium catalysts is excellent, the 5 examples 7 to 9 and 12 is distinctly superior to that of the
catalytic activity for polyester synthesis being independent commonly used antimony catalysts: with the same residence
of the duration of storage. time, the titanium catalysts of the invention yielded poly
The following Examples are presented for illustrative ethylene terephthalate with a much higher intrinsic viscosity
purposes only and are not intended, nor should they be and otherwise equal quality. A comparison of examples 12
construed, as limiting in any way. The intrinsic viscosities 20 and 13 shows that at the same residence time the added
given in the following examples were measured at 25°C. on phosphorous compound decreased the intrinsic viscosity of
a solution of 0.5g polyester in 100 ml of a mixture of phenol the polyester, but assured that the desired neutral-white color
and 1,2-dichlorobenzene (3:2 by wt.). The diethylene glycol of the polyester and a reduction of the carboxyl end group
content was determined by gas chromatography of a trans concentration and of the diethylene glycol content was
esterification mixture obtained from 1 g polyester with 30ml 25 obtained. With the catalysts of examples 10 and 11 a
methanol and 50 mg/l zinc acetate in a Carius tube at 200 somewhat lower quantity of the phosphorous stabilizer
C. The COOH-end group concentration has been determined should be used for better evaluation of the catalytic activity.
by photometric titration of a solution of polyester in a
mixture of o-cresol and chloroform (70:30 by wt.) with 0.05 EXAMPLE 16
n-ethanolic potassium hydroxide solution against bromothy 30
mo blue. 299 parts by wt. of terephthalic acid were esterified with
191.8 parts by wt. of 1,3-propanediol in the presence of the
EXAMPLES sodium titanate powder used in examples 1 to 5 (in an
amount corresponding to 150 ppm. Ti/TPA) at 230° C. and
EXAMPLES 1 to 5 35 atmospheric pressure. After esterification, a further amount
of the same catalyst, corresponding to 130 ppm. Ti/TPA was
The esterification of terephthalic acid (TPA) and the added. The precondensation was carried out at 240-260° C.
transesterification of dimethyl terephthalate (DMT) with and stepwise reduced pressure (200 and 100 mbar). After a
different diols was performed in the usual way at atmo residence time of 60-80 minutes the mixture was polycon
spheric pressure without catalyst in comparative example densed for 120 minutes at 265 C. and a pressure of <1 mbar.
1a, in the presence of titanium tetrabutylate in comparative Towards the end of the polycondensation 10 ppm P/TPA as
example 4a, and in the other examples in the presence of triphenyl phosphate were added. The resulting polypropy
different quantities of a sodium titanate powder in accor lene terephthalate had an intrinsic viscosity of 0.801 di?gand
dance with this invention and with about 2 wt.% sodium and a -COOH end group concentration of 23 meq/kg, whereby
about 6 wt.% water, a particle size of about 2 m and a 45 its neutral-white color is clearly superior to the color of
specific surface area of about 300 m/g. The results are polypropylene terephthalate produced with conventional
presented in Table 1. catalysts.
Whereas the esterification of TPA with ethylene glycol EXAMPLE 17
(which proceeds without a catalyst) is not considerably
influenced by the presence of 210 ppm of the titanium 50 249.2 parts by wt terephthalic acid and 259.6 parts by wt.
catalyst (examples 1a/1b), the esterification with 1,3- 1,4-cyclohexane dimethanol were esterified in the presence
propanediol, 1,4-butanediol, or 14-cyclohexane dimethanol of the sodium titanate powder used in examples 1-5 at about
and the transesterification of DMT (both of which require a 220° C. The amount of catalyst corresponded to 47 ppm
catalyst) are very much accelerated by small amounts of the Ti/TPA. After esterification a further amount of the same
titanium catalyst of the invention. In comparison to a con 55 catalyst corresponding to 140 ppm. Ti/TPA was added, and
ventional catalyst, namely titanium tetrabutylate with the the mixture precondensed for 60 minutes at 280° C. under
same amount of Tiper TPA, the same degree of conversion reduced pressure (100 mbar). The subsequent polyconden
is reached after an approximately 20% shorter residence sation was performed at 300° C. under a pressure of <1 mbar
time (examples 4a/4b). for 75 minutes. Towards the end of the polycondensation 10
EXAMPLES 6 to 15 ppm PTPA as triphenyl phosphate were added. The result
ing poly(cyelohexanedimethylene)-terephthalate had an
To demonstrate the influence of the titanium catalyst of intrinsic viscosity of 0.546 di/g and a -COOH end group
the invention on polycondensation, an esterification product concentration of 46 meq/kg.
from terephthalic acid and ethylene glycol produced without EXAMPLE 18
a catalyst (with a degree of conversion of about 98% and a 65
diethylene glycol content of about 1.0 wt.%) was ground 291.3 parts by wt. of dimethyl terephthalate were trans
under liquid nitrogen and used as the initial product. For esterified with 270.4 parts by wt. 1,4-butanediol at 220° C.
 5,656,716
7 8
The sodium titanate powder used in examples 1-5 was used Z=0.01 to 2
as a catalyst in an amount corresponding to 78 ppm. Ti/TPA. and wherein said large surface area means a crystallite size
After transesterification, the same amount of catalyst was of not more than 100 nm and a specific surface area of more
added again, and the mixture precondensed at 235° C. and than 10 m?g, and finely dispersed means a particle or
stepwise reduced pressure (100 and 50 mbar) for 110 aggregate size of less than 10 p.m.
minutes. The polycondensation was carried out at 250° C. 2. A catalyst of claim 1, wherein the crystallite size is less
under apressure of <1 mbarfor 75 minutes.Towards the end than 10 nm, the specific surface area is more than 100 m/g,
of the polycondensation, 10 ppm P/TPA as triphenyl phos and the particle or aggregate size is not more than 1 Jum.
phate were added. The resulting polybutylene terephthalate
3. A catalyst of claim 1, wherein the crystallite size is
below the limit of detection by X-ray diffraction.
had an intrinsic viscosity of 0.903 d1/g and a -COOH end 10 4. A catalyst of claim 1 obtained by hydrolysis of titanyl
group concentration of 20 meq/kg. sulfate, optionally followed by removal of excess acid by
TABLE 1.
Approximate Reaction Degree of
Example Acid Compound Diol Catalyst (a) Temperature time Conversion
No. Kind Parts by wt. Kind Parts by wt. (ppm. TI/TPA) (°C) (min.) (%)
1a TPA 68.5 EG 76.8 m 240 135 89.2
b TPA 68.5 EG 76.8 210 240 135 89.4
2 TPA 100 BD 16.6 533 240 75 98.8
3 TPA 12.0 CHDM 20.8 40 200 80 99.8
4a TPA 30.0 PD 19.3 (b) 240 225 99.0
4b. TPA 16.6 PD 15.2 150 195 185 99.1
5 DMT 29.3 BD 270.4 78 220 180 99.3
EG = ethylene glycol
PD = 1,3-propanediol
BD = 1,4-butanediol
CHDM = 14-cyclohexane dimethanol
(a) = sodium titanate with ca. 2 wt.% Na and ea. 6 wt.% HO
(b) = 150 ppm. TI/TPA as titanium tetrabutylate (without sodium titanate)

TABLE 2
Catalyst(c)
particle spec. Na- water Polyester
Example crystalline crystallite size surface content content LV. COOH DEG
No. form size(m) (um) (m?g) (wt.%) (wt %) (dl/g) (meq/kg) (wt %) Color
6 (d) - -- - - --- 0.483 10 1.20 white
7 amorph. X ca. 2 ca. 300 ca. 2 4.8 0.634 10 1.13 white
8 amorph. X ca. 2 ca. 300 ca. 2 7.4 0.664 10 1.18 white
9 amorph X ca. 2 ca. 300 ca. 2 13.5 0.608 10 1.08 white
10 amorph X ca. 2 ca. 300 ca. 2 8.0 0.46 11 1.01 white
11 Anatase ca. 5 ca. 0.1 ca. 300 ca. 0.008 6.8 0.302 11 1.00 white
12 amorph. X ca. 2 ca. 300 ca. 2 ca. 6 0.612 14 1.05 white
13 amorph. X ca. 2 ca. 300 ca. 2 ca. 6 0.886 20 1.17 yellow
14 Anatase ca. 7 ca. 1.5 ca. 300 ca. 0.004 4.5 0.705 14 0.96 grey
15 amorph. (e) X ca. 2 ca. 300 ca. 2 ca. 6 0.782 21 1.34 yellow
LV. = intrinsic viscosity
amorph. = amorphous
X = below the limit of detection by x-ray diffraction
(c) = Example 7-10, 12-13 and 15 sodium titanate, Example 11 and 14 TiOzHO
(d) = 170 ppm Sb.1 PA as antimony triacetate in ethylene glycol
(e) = as 33% suspension in ethylene glycol

We claim: 55 neutralization, Washing, or both, or by treatment with alka

1. A catalyst for the production of polyesters consisting lihydroxide or alkaline earth hydroxide at a temperature in
essentially of a finely dispersed, large surface area titanate the range of ambient temperature to boiling temperature,
obtained by hydrolysis and having the composition followed by washing, optionally followed by partial reaction
with a mineral acid or a carboxylic acid, followed by
(MeO).(TiO2)-(H,O). washing again, and optionally followed by drying.
wherein
5. A catalyst of claim 4 obtained by thermal hydrolysis of
titanyl sulfate exclusively with water.
Me=Li, Na, K, Rb, Ca, Mg, Ca,Sr or Ba 6. In a process for the production of polyesters or copoly
n=1 for Me=alkaline earth metal and esters by esterification of at least one diol with at least one
n=2 for Me=alkali metal dicarboxylic acid or by transesterification of at least one diol
x=0.0001 to 6
65 with at least one dicarboxylic acid dialkylester, and subse
quent polycondensation, the improvement comprising car
rying out said esterification or transesterification in the
 5,656,716
9 10
presence of the catalyst of claim 1 in a quantity correspond catalyst corresponding to 10 to 250 ppm titanium, based on
ing to 0-1000 ppm titanium, based on dicarboxylic acid, and dicarboxylic acid, is added immediately before or at the
carrying out said polycondensation in the presence of the beginning of said polycondensation.
catalyst of claim 1 in a total amount corresponding to 9. The process of claim 6. in which the total amount of
20-1000 ppm titanium, based on dicarboxylic acid, and said catalystis added immediately before or at the beginning
adding immediately before, during, or after said polycon of said polycondensation.
densation a phosphorous-oxygen-compound in a quantity
corresponding to 10-200 ppm phosphorus, based on dicar 10. The process of claim 6, in which said esterification or
boxylic acid. transesterification is carried out in the presence of a quantity
7. The process of claim 6 in which the total amount of said 10 of said catalyst corresponding to 20-300 ppm titanium,
catalyst is added before or at the beginning of said esteri based on dicarboxylic acid.
fication or transesterification. 11. The process of claim 6 in which said catalyst is added
8. The process of claim 6, in which a first quantity of said as a powder or as a suspension in the polyester-forming diol.
catalyst is added before or at the beginning of said esteri
fication or transesterification, and a second quantity of said