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...
Utility Patent
1999-09-13
2001-01-02
Seidleck, James J. (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...
C524S752000, C524S714000, C524S875000, C521S130000
Utility Patent
active
06169157
ABSTRACT:
This invention relates to a process for producing polyester-polyurethane compositions, and to the stabilisation thereof in relation to hydrolytic ageing phenomena by an active ingredient combination comprising compounds containing carbodiimides with lactone derivatives, to mouldings produced therefrom and to the use thereof for semi-rigid, solid and/or cellular mouldings.
Semi-rigid, elastic polyurethane mouldings of solid or cellular, i.e. slightly foamed, structure are often synthesised based on polyester-polyurethane compositions. The addition of carbodiimides has for a long time proved useful in order to improve the resistance of these materials in a moist environment, i.e. under conditions which cause hydrolysis (Kunststoff Handbuch, Volume VII, Polyurethanes, 1994 by Dr. G. Oertel, Carl-Hanser-Verlag, Munich), wherein other classes of substances, such as 2-phenylimino-oxazolidines or hydroxyethylureas for example, are also effective (FR-PS 1 450 919, U.S. Pat. No. 3,795,638).
This treatment of the material with carbodiimides is unsatisfactory, however, when manufacturing relatively soft mouldings with a hardness <90 Shore A, which in addition are synthesised so that chemically they are very linear and which possibly contain high activator/catalyst contents in order to speed up the polyurethane synthesis reaction. In this situation, for example, an increase in the proportion of carbodiimide, even above the customary and generally recommended content of about 2% by weight in the polyurethane composition, no longer results in the moulding having a lasting stability in relation to hydrolytic attack.
It has now been found that the stabilising effect of carbodiimides can be considerably increased when lactones are present simultaneously. Since lactones have no effect when used in the absence of carbodiimides, there is clearly a combination effect here. Furthermore, it is surprising that this active ingredient combination has a stabilising effect which is greater than that of a carbodiimide content alone, even if the latter content is increased many times.
The present invention therefore relates to a process for producing solid transparent, as well as cellular, foamed PUR mouldings by the polyisocyanate addition polymerisation method, with a hardness of 40 to 90 Shore A, by the reaction of
a) organic and/or modified organic polyisocyanates with
b) at least one higher molecular weight compound containing at least two reactive hydrogens, and with
c) low molecular weight chain extenders and/or crosslinking agents in the presence of
d) catalysts and
e) the active ingredient mixture according to the invention, comprising carbodiimides and lactones, as well as
f) auxiliary agents and additives,
characterised in that component e) is contained in the reaction mass with 0.50 to 20% by weight of a lactone or lactone mixture and with 0.2 to 4.0% by weight of a carbodiimide or carbodiimide mixture.
In detail, the following can be stated with regard to the mouldings produced according to the invention and their starting components a) to f):
a) Aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyvalent isocyanates are suitable as the organic polyisocyanates (a). The following are particularly suitable: alkylene diisocyanates containing 4 to 12 carbon atoms in their alkylene radical, such as 1,12-dodecane diisocyanate, 2-ethyl-tetramethylene 1,4-diisocyanate, 2-methyl-pentamethylene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate, and preferably hexamethylene 1,6-diisocyanate; cycloaliphatic diisocyanates such as cyclohexane 1,3- and 1,4-diisocyanate, as well as any mixtures of these isomers; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate), 2,4- and 2,6-hexahydrotoluylene diisocyanate, as well as the corresponding mixtures of isomers, 4,4′-, 2,2′- and 2,4′-dicyclohexylmethane diisocyanate as well as the corresponding mixtures of isomers; araliphatic diisocyanates, such as 1,4-xylylene diisocyanate and mixtures of xylylene diisocyanate isomers, and preferably aromatic di- and polyisocyanates, such as toluene 2,4- and 2,6-diisocyanate and the corresponding mixtures of isomers; naphthalene 1,5-diisocyanate (NDI), 4,4′-, 2,4′- and 2,2′-diphenylmethane diisocyanate (MDI) and the corresponding mixtures of isomers, mixtures of 4,4′- and 2,4′-diphenylmethane diisocyanates, polyphenyl-polymethylene polyisocyanates, mixtures of 4,4′-, 2,4′- and 2,2′-diphenylmethane diisocyanates and polyphenyl-polymethylene polyisocyanates (crude MDI) and mixtures of crude MDI and toluene diisocyanates. The organic di- and polyisocyanates may be used singly or in the form of mixtures.
What are termed modified polyvalent isocyanates are also frequently used, i.e. products which are obtained by the chemical reaction of organic di- and/or polyisocyanates. Examples include di- and/or polyisocyanates containing ester, urea, biuret, allophanate, carbodiimide, isocyanurate, uretdione, uretonimine and/or urethane groups. Particular examples include the following: organic, preferably aromatic, polyisocyanates which contain urethane groups and which have NCO contents of 33.6 to 15% by weight, preferably 31 to 21% by weight, with respect to their total weight, for example 4,4′-diphenylmethane diisocyanate modified with low molecular weight diols, dialkylene glycols, trialkylene glycols or polyoxyalkylene glycols with molecular weights up to 6000, and mixtures of 4,4′- and 2,4′-diphenylmethane diisocyanates or toluene 2,4- or 2,6-diisocyanate, wherein the following are cited as examples of di- or polyoxyalkylene glycols which can be used singly or as mixtures: diethylene-, dipropylene-, polyoxyethylene-, polyoxypropylene- and polyoxypropylene-polyoxyethylene glycols. Compounds which are also suitable include prepolymers which contain NCO groups and which have NCO contents of 25 to 3.5% by weight, preferably 23 to 13% by weight, with respect to their total weight, which are produced from the polyether- and/or preferably polyester polyols described below and 4,4′-diphenylmethane diisocyanate, mixtures of 2,4′- and 4,4′-diphenylmethane diisocyanate, toluene 2,4- and/or 2,6-diisocyanates, as well as NDI or crude MDI. Liquid polyisocyanates which contain carbodiimide groups and/or isocyanurate rings and which have NCO contents of 33.6 to 15% by weight, preferably 31 to 21% by weight, with respect to their total weight, have also proved useful, e.g. those based on 4,4′-, 2,4′- and/or 2,2′-diphenylmethane diisocyanate and/or on toluene 2,4- and/or 2,6-diisocyanate.
These modified polyisocyanates may optionally be mixed with each other or with unmodified polyisocyanates, such as 2,4′-, or 4,4′-diphenylmethane diisocyanate, crude MDI, or toluene 2,4- and/or 2,6-diisocyanate. Examples of mixtures which are very suitable are those comprising diphenylmethane diisocyanates and/or toluene diisocyanates and/or crude MDI which are modified with urethane groups, and diphenylmethane diisocyanates and/or toluene diisocyanates and/or crude MDI which are optionally unmodified.
Organic polyisocyanates have proved particularly useful, and the following are therefore preferably employed for producing the polyurethane mouldings according to the invention: polyisocyanates containing aromatically bonded isocyanate groups and with an average NCO functionality of 2 to 3. Polyisocyanates which are particularly preferred comprise polyisocyanates or polyisocyanate mixtures of the diphenylmethane series which are liquid at room temperature, i.e. mixtures of 4,4′-diphenylmethane diisocyanate with 2,4′-diphenylmethane diisocyanates which are liquid at room temperature, carbodiimide- or uretonimine-modified derivatives of these isocyanates which are liquid at room temperature, and reaction products of these isocyanates with polyols, which products are liquid at room temperature. These semi-prepolymers are reaction products which have an NCO/OH equivalent ratio of 2.2
Dick Hans-Norbert
Michels Erhard
Pleiss Klaus
Bagwell Melanie
Bayer Aktiengesellschaft
Brown N. Denise
Gil Joseph C.
Seidleck James J.
LandOfFree
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