Use of carbodiimide-containing compositions for controlling pot life

Abstract

The invention relates to the use of carbodiimide-containing compositions for controlling pot life in the production of polyurethane (PU)-based systems, preferably PU elastomers, PU adhesives, PU casting resins or PU foams.

Claims

1. A method for controlling pot life of polyurethane-based systems having a polyol and a polyisocyanate that when mixed together have a defined polymerization pot life, the method comprising: extending the pot life of the polyurethane-based system by separately mixing at least one of the polyol and the polyisocyanate with at least one carbodimide of the formula (I)
R.sup.1(O)OCHN(RNCN).sub.mRNHCO(O)R.sup.1(I) wherein: m=1 to 40, R is C.sub.6-C.sub.18-alkylene or C.sub.6-C.sub.18-cycoalkylene, and R.sup.1 is C.sub.1-C.sub.4-alkyl or (CH.sub.2).sub.hO[(CH.sub.2).sub.kO].sub.gR.sup.2, where h=1-3, k=1-3, g=5-20, and where R.sup.2 is H or C.sub.1-C.sub.4-alkyl, at least prior to mixing of the polyol and the polyisocyanate to provide a polyurethane-based system having an extended pot life; and controlling the polymerization pot life by mixing the polyol, the polyisocyanate, and the at least one carbodiimide to begin polymerization and polymerizing the components over the extended pot life of at least 420 seconds.

2. The method of claim 1, wherein: m=10-30, R is C.sub.6-C.sub.18-alkylene or C.sub.6-C.sub.18-cycloalkylene, and R.sup.1 is C.sub.1-C.sub.4-alkyl or a (CH.sub.2).sub.hO[(CH.sub.2).sub.kO].sub.gR.sup.2 radical, with h=1-3, k=1-3, g=10-12, and where R.sup.2 is H or C.sub.1-C.sub.4-alkyl.

3. The method of claim 1, wherein the at least one carbodiimide of the formula (I) is a mixture of a plurality of different carbodiimides of the formula (I).

4. The method of claim 1, wherein: R is defined as: ##STR00005## and R.sup.1 is a (CH.sub.2).sub.hO[(CH.sub.2).sub.kO].sub.gR.sup.2 radical, with h=1-3, k=1-3, g=5-20, and R.sup.2 is H or C.sub.1-C.sub.4-alkyl.

5. The method of claim 1, wherein the carbodiimide of the formula (I) is mixed with the polyol prior to mixing the polyol and the polyisocyanate, and the polyol comprises polyester polyols, polyether ester polyols, or a combination thereof.

6. The method of claim 1, further comprising mixing each of the carbodiimide of the formula (I), the polyol, and the diisocyanate to produce a polyurethane mixture.

7. The method of claim 1, further comprising mixing at least one diamine with the carbodiimide of the formula (I) and the at least one of the polyol and the polyisocyanate at least prior to mixing of the polyol and the polyisocyanate.

8. The method of claim 6, wherein the diisocyanate is selected from the group consisting of toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, phenylene diisocyanate, 4,4-diphenylmethane diisocyanate, methylenebis(4-phenyl isocyanate), naphthalene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate, hexamethylene 1,6-diisocyanate, and mixtures thereof.

9. The method of claim 7, wherein the diamine is selected from the group consisting of 2-methylpropyl 3,5-diamino-4-chlorobenzoate, bis(4,4-amino-3-chlorophenyl)methane, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-diethyl-2,4-tolylenediamine, 3,5-diethyl-2,6-tolylenediamine, 4,4-methylenebis(3-chloro-2,6-diethylaniline), 1,3-propanediol bis(4-aminobenzoate), and mixtures thereof.

10. The method of claim 4, wherein: M is 20; and R.sup.1 is a (CH.sub.2).sub.hO[(CH.sub.2).sub.kO].sub.gR.sup.2 radical, with h=2, k=2, g=10-12, and R.sup.2 is CH.sub.3.

11. The method of claim 1, wherein: a ratio of carbodiimide to polyol is 0.1-5:100 parts by weight; and a ratio of diisocyanate to polyol is 20 to 50:100 parts by weight.

12. The method of claim 11, wherein: the carbodiimide of the formula (I) and a diamine are mixed with the polyol prior to mixing of the polyol and the polyisocyanate to form the polyurethane; R is defined as: ##STR00006## and R.sup.1 is a (CH.sub.2).sub.hO[(CH.sub.2).sub.kO].sub.gR.sup.2 radical, with h=1-3, k=1-3, g=5-20, and R.sup.2 is H or C.sub.1-C.sub.4-alkyl; the polyol comprises at least one polyol having a molecular weight of 500 to 1000 g/mol and an OH number of 50 to 115; the diisocyanate is selected from the group consisting of toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, phenylene diisocyanate, 4,4-diphenylmethane diisocyanate, methylenebis(4-phenyl isocyanate), naphthalene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate, hexamethylene 1,6-diisocyanate, and mixtures thereof; and the diamine is selected from the group consisting of 2-methylpropyl 3,5-diamino-4-chlorobenzoate, bis(4,4-amino-3-chlorophenyl)methane, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-dimethylthio-2,4-tolylenediamine, 3,5-diethyl-2,4-tolylenediamine, 3,5-diethyl-2,6-tolylenediamine, 4,4-methylenebis(3-chloro-2,6-diethylaniline), 1,3-propanediol bis(4-aminobenzoate), and mixtures thereof.

13. The method of claim 12, wherein: R is defined as: ##STR00007## R.sup.1 is a (CH.sub.2).sub.hO[(CH.sub.2).sub.kO].sub.gR.sup.2 radical, with h=2, k=2, g=10-12, and R.sup.2 is methyl; the polyol is polyester polyol, polyether ester polyol, or a combination thereof; the diisocyanate is toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, or a combination thereof; the diamine is 2-methylpropyl 3,5-diamino-4-chlorobenzoate; a ratio of the carbodiimide to the polyol is 1 to 3:100 parts by weight; a ratio of the diisocyanate to the polyol is 30:100 parts by weight; and the polyurethane comprises 5-30 wt % of the diamine.

14. The method of claim 1, wherein: the at least one carbodiimide is separately mixed with the at least one of the polyol and the polyisocyanate prior to mixing of the polyol and the polyisocyanate, whereby the polyurethane-based system having an extended pot life comprises a first polyol component separate from a second polyisocyanate component, wherein at least one of the first polyol component and the second polyisocyanate component is mixed with the carbodiimide; and the polymerizing comprises mixing the first polyol component with the second polyisocyanate component.

15. The method of claim 1, wherein: the at least one carbodiimide is mixed with the polyol prior to mixing of the polyol and the polyisocyanate, whereby the polyurethane-based system having an extended pot life comprises the polyisocyanate separate from a polyol component comprising the polyol and the carbodiimide; and the polymerizing comprises mixing the polyol component with the polyisocyanate.

Description

WORKING EXAMPLES

(1) In the examples which follow, the following substances were used:

(2) Desmophen 2000MM, a linear polyester polyol having an OH number of 56 mg KOH/g and an acid number of 0.83 mg KOH/g, from Bayer MaterialScience AG.

(3) A carbodiimide of the formula (I) having an average m of 20, R.sup.1=(CH.sub.2).sub.hO[(CH.sub.2).sub.kO].sub.gR.sup.2 where R.sup.2=methyl, H=2, k=2 and g=10-12.

(4) StabaxolP200, a polymeric aromatic carbodiimide based on tetramethylxylene diisocyanate from Rhein Chemie Rheinau GmbH.

(5) Stabaxol I, a monomeric carbodiimide based on 2,6-diisopropylphenyl isocyanate from Rhein Chemie Rheinau GmbH.

(6) DesmodurT100, a tolylene 2,4-diisocyanate from Bayer Material Science.

(7) Addolink 1604, a 2-methylpropyl 3,5-diamino-4-chlorobenzoate from Rhein Chemie Rheinau GmbH as diamine component.

(8) Carbodilite HMV-8 CA: a polymeric aliphatic carbodiimide from Nisshinbo Industries, INC.

(9) The following mixtures were prepared as follows:

(10) Mixture A (Comparative):

(11) 100 g of Desmophen 2000MZ were melted at 100 C.

(12) Mixture B (Inventive):

(13) 100 g of Desmophen 2000MZ were melted at 100 C. and admixed with 0.6 g of the carbodiimide of the formula (I) having an average m of 20, R.sup.1=(CH.sub.2).sub.hO[(CH.sub.2).sub.kO].sub.gR.sup.2 where R.sup.2=methyl,

(14) ##STR00004##
h=2, k=2 and g=10-12.
Mixture C (Comparative):

(15) 100 g of Desmophen 2000MM were melted at 100 C. and admixed with 0.6 g of monomeric carbodiimide based on 2,6-diisopropylphenyl isocyanate.

(16) Mixture D (Comparative):

(17) 100 g of Desmophen 2000MM were admixed with 0.6 g of Carbodilite HMV-8 CA and stored at 30 C. for 24 h. The two substances are immiscible. Thus, this mixture was unusable for further experiments.

(18) All figures are in parts by weight, unless stated otherwise.

(19) TABLE-US-00001 TABLE 1 Parts/ Mixture Desmodur Addolink no. Mixture A Mixture B Mixture C T100 1604 I (C) 100 21 16.16 II (inv.) 100 21 16.16 III (C) 100 21 16.16 C = comparative example, inv. = inventive

(20) Mixtures A to C were reacted at temperatures of 80 C. with the amounts of Desmodur T 100 specified in table 2 up to an isocyanate content of 5%, and then reacted with the Addolink 1604 chain extender in the with the amount specified in table 2. The pot life of the mixture which is still liquid, gelates after a few minutes and reacts to give a solid elastomer was determined. The pot life is the time between the mixing of a multicomponent substance and the end of processability. The values determined are shown in table 3.

(21) TABLE-US-00002 TABLE 2 Mixture Pot life in seconds I 240 II 420 III 340
Interpretation of the Experimental Results:

(22) It is clearly apparent from the value for mixture II that the mixture comprising the inventive carbodiimide of the formula (I) having an average m of 20, R.sup.1=(CH.sub.2).sub.lO[(CH.sub.2).sub.kO].sub.gR.sup.2 where R.sup.2=methyl, l=2, k=2 and g=10-12, leads to a distinct extension of pot life and hence to an improvement in processability.