Polyurethane elastomers, process for their production and...

Details Polyurethane elastomers, process for their production and... Polyurethane elastomers, process for their production and...

2002-08-27

2003-07-08

Sergent, Rabon (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

C521S123000, C521S124000, C521S125000, C521S128000, C521S129000, C521S174000, C521S176000, C521S137000, C525S123000, C525S453000, C525S455000, C528S053000, C528S054000, C528S055000, C528S056000, C528S057000, C528S076000, C528S077000, C036S02500A

Reexamination Certificate

active

06590057

ABSTRACT:

FIELD OF THE INVENTION
The invention is directed to polyurethane elastomers (PU elastomers), a process for their production with special catalyst mixtures and uses thereof.
BACKGROUND OF THE INVENTION
PU elastomers have long been known and have already been customized for a wide variety of applications, see for example U.S. Pat. No. 5,952,053. In order to control their polymerization rates, a large number of diverse metal catalysts have been investigated and used. In addition to the widespread use of organotin compounds, it is also known to use organic compounds or organic salts of various other elements, such as lithium, titanium and bismuth.
The use of lithium salts of organic acids has also been described. Mixtures of a lithium carboxylate, namely lithium neodecanoate, lithium octanoate, lithium stearate or lithium naphthenate, and a zinc carboxylate are described in U.S. Pat. No. 4,256,847 as an effective catalyst combination for rigid foam applications. Lithium is known to be highly active. Other publications list lithium as the sole metal catalyst for the catalysis of PU reactions. In U.S. Pat. No. 4,107,069, lithium carboxylates are used as stable gel catalysts for rigid PU foams. U.S. Pat. No. 3,108,975 discloses their use as catalysts for rigid and flexible, as well as, cellular and non-cellular polyurethanes. The use of lithium carboxylates as a trimerization catalyst is likewise known, in fact in U.S. Pat. No. 3,634,345, moisture-insensitive, readily soluble aromatic carboxylates are used for PU resin production. in U.S. Pat. No. 3,940,517 aliphatic lithium carboxylates are used for PU foams and in U.S. Pat. Nos. 6,127,308 and 5,955,609, the controllability of the trimerization reaction is used for PU foams and prepolymer synthesis. The same procedure is used in the production of rigid foams in DE-A 59 101 001. Finally, in U.S. Pat. No. 2,894,919, lithium carboxylates, namely lithium stearate and lithium caprylate, are used as catalysts in order to produce exclusively elastic, flexible PU foams.
Organic titanium compounds have been used since the 1960's as catalysts for the synthesis of polyurethanes, such as those listed in U.S. Pat. No. 5,902,835. Known organic titanium compounds include, titanium carboxylates, as disclosed in U.S. Pat. No. 5,162,382, alkyl titanates, as disclosed in Saunders, J. H.; Frisch, K. C.
Polyurethanes—Chemistry and Technology
(1962) London Part I p. 168, JP 2 001/026 629, JP 5 097 952 and titanium diketonates and titanium &bgr;-keto esters, as disclosed in U.S. Pat. No. 5,902,835, DE-A 19 626 007, WO 98/15585, Chemical Abstract, Vol. 108:56652. Organic titanium compounds are commonly used as expansion and gel catalysts. Their range of applications extends from water-expanded PU foams and mechanically foamed, thermally curing PU foams to PU surface coatings to RIM systems for flexible PU foams.
Organic bismuth compounds are also known to be used as catalysts, see for example, Luo, S.-G.; Tan, H.-M.; Zhang, J.-G.; Wu, Y.-J.;
Pei, F.-K.; Meng, X.-H. J. Appl. Polym. Sci. (1997) 65(6), p. 1217-1225. Of the group of organic bismuth compounds, carboxylates are predominantly used, as disclosed in CA-A 2 049 695, DE-A 19 618 825, U.S. Pat. No. 5,792,811, and WO 2000/47642. In addition, bismuth organothiolates are used as latent catalysts, see for example, WO 95/29007 and U.S. Pat. Nos. 5,910,373, and 6,190,524. The use of bismuth compounds together with organic zinc or tin compounds is also known, see for example WO 96/20967, U.S. Pat. Nos. 5,910,373, 6,001,900, 5,859,165, 6,124,380 and 6,190,524, WO 98/14492 and WO 2000/46306. The field of application for the use of bismuth catalysts mentioned above is mainly in the area of surface coating.
In addition to the combinations of metal catalysts already mentioned, such as e.g. tin and zinc compounds, a number of catalyst combinations comprising organic compounds, of the elements, lithium, titanium or bismuth can also be found in the literature. U.S. Pat. Nos. 5,952,053, 5,952,053 and WO 2000/46306 list combinations of lithium and bismuth compounds and U.S. Pat. No. 5,902,835 discloses that organic titanium compounds can be combined with bismuth compounds, however these metal catalyst combinations display no special effects.
Shoe soles, among other things, are an important application for PU elastomers. The catalyst systems used in their production must provide for good processability of the soles. Specifically, this includes short demolding times and high demolding hardness values, as well as, long cream times, to ensure that every part of the mold is filled. The catalysts must also promote good end properties, such as high final hardness values and low puncture expansion values under repeated flexural stress. Commercial organotin catalysts do not satisfy this list of requirements.
SUMMARY OF THE INVENTION
An object of the present invention is to provide PU elastomers having high final hardness values and low puncture expansion values under repeated flexural stress, as well as a process, in which short demolding times, high demolding hardness values and long cream times are possible.
Surprisingly this object can be achieved with special catalyst combinations containing lithium and titanium compounds or organic lithium, titanium and bismuth compounds. In the case of a three-component mixture, the concentration of catalyst used can also be reduced, in comparison to the two-component mixture, with an otherwise identical effect, giving rise, in addition, to toxicological and economic advantages.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides polyurethane elastomers produced by reacting
a) organic diisocyanates and/or polyisocyanates with
b) at least one polyether polyol having a number-average molecular weight of 800 g/mol to 25,000 g/mol, preferably 800 to 14,000 g/mol, more preferably 2,000 to 9,000 g/mol and having an average functionality of 1.6 to 2.4, preferably 1.8 to 2.4,
c) optionally at least a second polyether polyol differing from b) and having a number-average molecular weight of 800 g/mol to 25,000 g/mol, preferably 800 to 14,000 g/mol, more preferably 2,000 to 9,000 g/mol and having average functionalities of 2.4 to 8, more preferably 2.5 to 3.5,
d) optionally polymer polyols containing 1 to 50 wt. %, preferably 1 to 45 wt. % filler, relative to polymer polyol, and having hydroxyl values of 10 to 149 and average functionalities of 1.8 to 8, preferably 1.8 to 3.5,
e) optionally low-molecular chain extenders having average functionalities of 1.8 to 2.1, preferably 2, and having molecular weights of 750 g/mol and lower, preferably 18 g/mol to 400 g/mol, more preferably 60 g/mol to 300 g/mol, and/or crosslinking agents having average functionalities of 3 to 4, preferably 3, and having molecular weights of up to 750 g/mol, preferably 18 g/mol to 400 g/mol, particularly preferably 60 g/mol to 300 g/mol, in the presence of
f) amine catalysts and a catalyst mixture containing
i) at least one organic titanium and/or zirconium compound,
ii) and at least one organic lithium carboxylate,
iii) optionally additionally at least one organic bismuth carboxylate,
g) optionally blowing agents, and
h) optionally additives,
wherein the ratio of the amount of substance n
Ti
of titanium ions and/or n
Zr
of zirconium ions in component i) to the amount of substance n
Li
of lithium ions in component ii) is 0.2 to 4, preferably 0.43 to 1.5 and if component iii) is used the ratio of the amount of substance n
Bi
of bismuth ions in component iii) to the sum of the amounts of substance n
Ti
and/or n
Zr
and n
Li
is 0.0001 to 0.53, preferably 0.0001 to 0.24, more preferably 0.0001 to 0.15.
The PU elastomers are preferably produced by the prepolymer process, whereby in the first step a polyaddition adduct, having isocyanate groups, is produced from at least a portion of the polyether polyol b) or a mixture thereof, with polyol component c) and at least one diisocyanate or polyisocyanate a). In the second step solid PU elastomers can be produced from prepolymers having such isocyanate groups, by

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