Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-02-25
2002-07-09
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S275000, C528S282000, C528S283000, C528S285000, C528S286000, C502S063000, C502S064000, C502S100000, C502S103000, C502S105000, C502S109000, C502S111000, C502S155000, C502S400000
Reexamination Certificate
active
06417320
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to the field of catalysts and to methods of making and using them. The catalysts are used in the production of linear polyesters through the esterification or transesterification and polycondensation of multivalent alcohols with multivalent carboxylic acids.
2. Summary of the Related Art
The production of polyesters generally takes place in a manner in which a diol is converted to the corresponding dicarboxylic acid ester with a dicarboxylic acid or a low weight dicarboxylic acid ester, e.g., dimethyl ester, the dicarboxylic acid ester undergoing single or multistage polycondensation with increasing temperatures under decreased pressure. Various catalysts are used for the esterification and/or the interchange of ester radicals and polycondensation depending on the selection of the diols and dicarboxylic acids.
Catalysis in the production of polyester (particularly of the polycondensation reaction to build the polymer chain of linear polyester according to the chemical principle of polyesterification and poly-interchange of ester radicals) takes place as a result of the addition of metals that are capable of forming transition complexes with functional groups, in particular with the hydroxyl end groups. Preferred metal ions are those with three or more free valences, such as Sb
3+
, Pb
4+
, Ti
4+
, Bi3+, As
3+
, Si
4+
, Sn
4+
, Al
3+
and Ge
4+
; these are effective catalysts for polycondensation. In industrial practice, Sb
3+
and Ge
4+
have proven to be preferred for the polycondensation of polyethylene terephthalate (PET), whereby metal concentrations of 150 to 300 ppm Sb and 20 to 120 ppm Ge are effective, depending on the type of polycondensation reactor; Ti
4−
in the form of, for example, its tetra alkoxide has proven useful as a catalyst in the production of polybutylene terephthalate (PBT) and polytrimethylene terephthalate (PTT) and their co-polyester due to its generally high reactivity and high hydrophilicity. For the production of PET there has been much experimentation regarding the use of Ti as a catalyst, primarily because of the possible environmentally damaging effects of Sb as a heavy metal.
Above all, the use of complex-forming ligands such as tartaric acid or citric acid according to DD-A-286 174 and WO 97/47675, or the formation of complex TiO
2
—SiO
2
compounds according to U.S. Pat. No. 5,789,528, or the use of alkali modified titanium oxide according to EP-A-0 826 713, EP-A-0 827 518 and EP-A-0 799 268, or the use of mixed catalysts of Ti with other metals, as these are described in U.S. Pat. No. 5,340,907, DE-A-196 27 591 and EP-A-0 745 630, should, on the one hand, reduce the high sensitivity of the titanium alkoxides to hydrolysis and stop the associated inclination to precipitate, and on the other hand should reduce the formation of colored complex compounds that are brought about by the titanium. In many of these patent publications a concentration range of 5 to 100 ppm Ti, preferably 5 to 30 ppm, is indicated.
The following table (Table 1) lists several patent publications that disclose Ti in combination with various additions as catalysts, whereby the range of yield and the reprocessed, exemplified embodiments are compared.
TABLE 1
Ti
Ti
Patent
concentration
concentration
Publication No.
Ti compound
claimed
in example
modifier
EP 0 826 713
Tetrabutyltitanate
5-30 ppm
15: 30 ppm
Ultranox ® 626; 627A
(U.S. Pat. No. 706 950 A1;
or tetratitanate
U.S. Pat. No. 910 754 A1)
U.S. Pat. No. 5,789,528
TiO
2
/SiO
2
>
5-500 ppm/
95:5/100 ppm
Carbethoxymethyl-diethyl
90:10
10-100 ppm
phosphonate;
(relative to the
di(polyoxy ehtylene) hydroxy-
oxides)
methyl phosphonate
EP 827 518 A1
Titantetrabutylate
0.005-0.05
5 ppm
Trisnonylphenylphosphite,
mmol/mol PTA
phosphoric acid Bi(2
B
4 di-tert-
(2.5-7.5 ppm Ti)
butyl-phenyl)
≦12 ppm active
pentaerytritdiphosphite
substance Ti = P
phosphoric acid
=Co
triphenylphosphate
DE196 27 591
Ti(IV) compound
500-10000 ppm
3.3-59 ppm Ti
Triethyl phosphate
A1
as co-catalyst for
zeolite = Ti
=5000 ppm
zeolite (as
(conc. not
zeolite
synergist)
claimed)
EP 0 799 268A1
S from benzene
sulfur 5-60
Ti = S:
sulfonic acid/benzylsulfonic
sulfonic acid = Ti
ppm = Ti 1-6
4 = 32 ppm;
acid
of titetrais-
ppm
6 = 48 ppm;
propylate
6 = 0 ppm;
80 Sb
2
= 16 ppm
U.S. Pat. No. 5 340 907A1
mixed catalysts
0.75 ppm Mn
1 ppm Ti
P as inhibitor
of Zn, Ti, and
25-100 ppm Zn
(=100 ppm Zn
possibly Mn
0.5-15 ppm Ti
=30 ppm Co)
EP 0745 640 A1
mixed catalysts
metal 5-130
4 ppm Ti
of Sb, Ge and Ti
ppm, of which
(=81 ppm Sb)
Ti 0-20 ppm
The need for a Ti concentration of >20 ppm (as required in practice) is principally evident from the fact that in industrial scale polycondensation, part of the metal catalyst is converted by traces of water to catalytically inactive TiO
2
precipitate. This precipitate leads to increased turbidity and/or shell-like deposits in the polyesters. Moreover, the part of the catalyst metal converted into TiO
2
is unavailable for polycondensation. Aside from that, higher concentrations of titanium cause a yellow color in the polyester, despite inhibition and addition of high concentrations of dye, and result in a polyester that is less brilliant overall and thermally unstable.
It is also known that Sb in the presence of water forms antimony oxide hydrates or, in the presence of phosphoric acid, e.g., forms antimony phosphates. The reduction of Sb to catalytically inactive antimony metal results in a gray color in the polyester.
SUMMARY OF THE INVENTION
The present invention comprises a composition, a method for its production, and the use of the composition for the production of linear polyester having the lowest possible content of catalytically active metal compounds and that may be used, in particular, in the production of bottles, films and other foodstuff packaging, as well as for filaments, threads, and formed bodies. The composition comprises a fine grain, porous carrier into which a catalytically active metal compound has been adsorbed.
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of the invention is a composition of porous, fine grain particles made of a heterogeneous carrier substance containing catalytically active metal compounds adsorbed on the surface of the particles and on the surface within the pores of the particles. This composition affords protection of the catalytically active metal compound in the reaction medium and subsequent diffusion of the catalyst to the site of the reaction.
One advantage of the catalyst of the invention arises from the fact that the carrier substance comprises at least one substance selected from among activated charcoal, diatomaceous earth, zeolites, synthetic and natural silicates, silicone oxides, silicone oxide hydrates, fuller's earth, cross linked polymers and the like, although the principle of action is not limited to the indicated substances. The carrier substance must be able to adsorb the catalytically active metal compounds used in the invention. The particles of the carrier substance of the invention have an average grain size (d
50
) of 0.05 to 2 &mgr;m, preferably 0.1 to 1 &mgr;m, and most preferably 0.2 to 0.5 &mgr;m. In the reaction medium these particles do not agglomerate substantially.
The specific surface area of the particles that form the carrier substance, as determined according to the BET method, is ≧50 m
2
/g, preferably >500 m
2
/g.
Catalytically active metal compounds that can be used with the carrier substance of the invention are metal compounds of one or more of, for example, Ti, Sb, Ge, Sn and Al that supply the polyester reaction mixture with Ti
4+
, Sb
3+
, Ge
4+
, Sn
4+
, and Al
4+
ions, respectively, for reaction with the OH or COOH end groups of the polyester reaction mixture. Suitable catalytically active metal compounds include salts, oxides, and organic
Guo Xiaogang
Otto Brigitta
Thiele Karl Ulrich
Acquah Samuel A.
McDonnell & Boehnen Hulbert & Berghoff
Zimmer Aktiengesellschaft
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