POLYURETHANE COMPOSITION HAVING A LOW CONTENT OF MONOMERIC DIISOCYANTES

Abstract

A blocked amine as curing aid for polymers containing isocyanate groups and having a low monomeric diisocyanate content, obtained from the reaction of at least one monomeric diisocyanate with at least one polyol in an NCO/OH ratio of at least 3/1, followed by removal of a majority of the monomeric diisocyanates by means of a suitable separation method, and to the moisture-curing polyurethane compositions obtained from this use. The use enables storage-stable, moisture-curing polyurethane compositions which can be safely handled even without special safety precautions and can be sold without hazard labeling in many countries, have good processibility and cure reliably and rapidly at ambient temperatures to give a material of high strength, elasticity and extensibility, and high stability to weathering influences. Such moisture-curing polyurethane compositions are particularly suitable as elastic sealants, adhesives or coatings, especially also for exposed outdoor applications.

Claims

1. A method for curing of polymers containing isocyanate groups, comprising: adding a blocked amine as a curing aid to polymers containing isocyanate groups and having a low monomeric diisocyanate content, the polymers containing isocyanate groups having been obtained from the reaction of at least one monomeric diisocyanate with at least one polyol in an NCO/OH ratio of at least 3/1, followed by removal of a majority of the residual monomeric diisocyanates by means of a separation method, wherein the polymer containing isocyanate groups has a monomeric diisocyanate content of not more than 0.5% by weight, based on the polymer containing isocyanate groups after removal of the residual monomeric diisocyanates.

2. The method as claimed in claim 1, wherein the monomeric diisocyanate content is not more than 0.3% by weight, based on the polymer containing isocyanate groups after removal of the residual monomeric diisocyanates.

3. The method as claimed in claim 1, wherein the polymer containing isocyanate groups has an NCO content in the range from 0.5% to 10% by weight.

4. The method as claimed in claim 1, wherein the monomeric diisocyanate is a sterically hindered diisocyanate.

5. The method as claimed in claim 1, wherein the polyol is a diol or triol having an OH number in the range from 8 to 185 mg KOH/g.

6. The method as claimed in claim 1, wherein the polyol is a polyether polyol and the polymer containing isocyanate groups that is obtained therefrom is a polyetherurethane polymer containing isocyanate groups.

7. The method as claimed in claim 1, wherein the blocked amine has at least one aldimino group or oxazolidino group.

8. The method as claimed in claim 1, wherein the blocked amine has at least one aldimino group of the formula (IIa) or (IIb) ##STR00009## where .sup.1and R.sup.2 are each independently a monovalent hydrocarbyl radical having 1 to 12 carbon atoms, or together are a divalent hydrocarbyl radical having 4 to 12 carbon atoms which is part of an optionally substituted carbocyclic ring having 5 to 8 carbon atoms, Y is a monovalent organic radical having 1 to 25 carbon atoms, and Z is an optionally substituted aryl or heteroaryl radical having 5 to 26 carbon atoms.

9. The method as claimed in 1, wherein the blocked amine is selected from aldimines of the formula (IIIa), (IIIb) and (IIIc) ##STR00010## where n is 2 or 3, A is an n-valent aliphatic, cycloaliphatic or arylaliphatic hydrocarbyl radical optionally including ether oxygen and having a molecular weight in the range from 28 to 6000 g/mol, R.sup.3 is a hydrogen radical or is a linear or branched alkyl, aralkyl or alkoxycarbonyl radical having 1 to 12 carbon atoms, R.sup.4 is a hydrogen radical or a monovalent hydrocarbyl radical which has 1 to 18 carbon atoms and optionally contains ether, carbonyl or ester groups, R.sup.5 and R.sup.6 are each independently a linear or branched alkyl, cycloalkyl or aralkyl radical optionally having ether groups, or together are a divalent hydrocarbyl radical which has 4 to 12 carbon atoms and is part of a 5- to 8-membered heterocyclic ring which, in addition to the nitrogen atom, optionally contains an ether, thioether or tertiary amino group, and R.sup.7 is a hydrogen radical or a linear or branched alkyl or alkoxy radical having 1 to 20 carbon atoms

10. The method as claimed in claim 9, wherein R.sup.1 and R.sup.2 are each methyl, R.sup.3 is a hydrogen radical, and either R.sup.4 is a radical selected from methyl and undecyl, or R.sup.5 and R.sup.6 together are 3-oxa-1,5-pentylene, or R.sup.7 is an optionally branched alkyl radical having 10 to 14 carbon atoms in the para position.

11. A moisture-curing polyurethane composition comprising at least one polymer containing isocyanate groups and having a low monomeric diisocyanate content, and at least one blocked amine wherein the moisture-curing polyurethane composition has a monomeric diisocyanate content of less than 0.1% by weight, based on the overall composition.

12. The moisture-curing polyurethane composition as claimed in claim 11, further comprising at least one constituent selected from oligomeric isocyanates, catalysts, fillers and plasticizers.

13. A method of bonding or sealing, comprising the steps of (i) applying the moisture-curing polyurethane composition as claimed in claim 11 to a first substrate and contacting the composition with a second substrate within the open time of the composition, or to a first and to a second substrate and joining the two substrates within the open time of the composition, or between two substrates, (ii) curing the composition by contact with moisture.

14. A method of coating or sealing, comprising the steps of (i) applying the moisture-curing polyurethane composition as claimed in claim 11 to a substrate, (ii) curing the composition by contact with moisture.

15. An article obtained from the method as claimed in claim 13.

Description

EXAMPLES

[0195] Working examples are presented hereinbelow, which are intended to further elucidate the invention described. The invention is of course not limited to these described working examples.

[0196] “Standard climatic conditions” (“SCC”) refer to a temperature of 23±1° C. and a relative air humidity of 50±5%.

[0197] Unless stated otherwise, the chemicals used were from Sigma-Aldrich.

Preparation of Polymers Containing Isocyanate Groups

[0198] The viscosity was measured with a thermostated Rheotec RC30 cone-plate viscometer (cone diameter 25 mm, cone angle 1°, cone tip-plate distance 0.05 mm, shear rate 10 s.sup.−1).

[0199] Monomeric diisocyanate content was determined by means of HPLC (detection via photodiode array; 0.04 M sodium acetate/acetonitrile as mobile phase) after prior derivation by means of N-propyl-4-nitrobenzylamine.

Polymer P-1

[0200] 780.0 g of Desmophen® 5031 BT (glycerol-started ethylene oxide-terminated polyoxypropylene triol, OH number 28.0 mg KOH/g, OH functionality about 2.3; from Covestro) and 220 g of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (Vestanat® IPDI, from Evonik) were converted in the presence of 0.01 g of dibutyltin dilaurate by a known method at 80° C. to a polyetherurethane polymer having an NCO content of 6.4% by weight, a viscosity of 4.1 Pa.Math.s at 20° C. and a monomeric IPDI content of about 12% by weight.

[0201] Subsequently, the volatile constituents, especially the majority of the monomeric IPDI, were removed by distillation in a short-path evaporator (jacket temperature 160° C., pressure 0.1 to 0.005 mbar). The polyetherurethane polymer thus obtained had an NCO content of 1.9% by weight, a viscosity of 8.2 Pa.Math.s at 20° C. and a monomeric IPDI content of 0.02% by weight.

Polymer P-2

[0202] 725 g of Desmophen® 5031 BT (glycerol-started ethylene oxide-terminated polyoxypropylene triol, OH number 28.0 mg KOH/g, OH functionality about 2.3; from Covestro) and 275 g of diphenylmethane 4,4diisocyanate (Desmodur® 44 MC L, from Covestro) were converted by a known method at 80° C. to a polyetherurethane polymer having an NCO content of 7.6% by weight, a viscosity of 6.5 Pa.Math.s at 20° C. and a monomeric diphenylmethane 4,4diisocyanate content of about 20% by weight.

[0203] Subsequently, the volatile constituents, especially the majority of the monomeric diphenylmethane 4,4iisocyanate, were removed by distillation in a short-path evaporator (jacket temperature 180° C., pressure 0.1 to 0.005 mbar, condensation temperature 47° C.). The polyetherurethane polymer thus obtained had an NCO content of 1.7% by weight, a viscosity of 19 Pa.Math.s at 20° C. and a monomeric diphenylmethane 4,4diisocyanate content of 0.04% by weight.

Polymer R-1

[0204] 894.5 g of Desmophen® 5031 BT (glycerol-started ethylene oxide-terminated polyoxypropylene triol, OH number 28.0 mg KOH/g, OH functionality about 2.3; from Covestro) and 105.0 g of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (Vestanat® IPDI, from Evonik) were converted in the presence of 0.01 g of dibutyltin dilaurate by a known method at 80° C. to a polyetherurethane polymer having an NCO content of 1.9% by weight and a monomeric IPDI content of about 1.4% by weight.

Polymer R-2

[0205] 685 g of Voranol® CP 4755 (glycerol-started ethylene oxide-terminated polyoxypropylene triol, OH number 35.0 mg KOH/g, OH functionality about 2.4; from Dow), 115 g of diphenylmethane 4,4diisocyanate (Desmodur® 44 MC L, from Covestro) and 200 g of diisodecyl phthalate were converted by a known method at 80° C. to a polyetherurethane polymer having an NCO content of 1.9% by weight and a monomeric diphenylmethane 4,4diisocyanate content of about 2.1% by weight.

[0206] Polymers P-1 and P-2 are inventive polymers containing isocyanate groups and having a low monomeric diisocyanate content. Polymers R-1 and R-2 are conventionally prepared polymers containing isocyanate groups and having a much higher monomeric diisocyanate content, and serve for comparison.

Preparation of Blocked Amines

[0207] Amine value (including aldimino and oxazolidino groups) was determined by means of titration (with 0.1N HClO.sub.4 in acetic acid versus crystal violet).

[0208] Aldimine A1: N,NBis(2,2-dimethyl-3-lauroyloxypropylidene)-3-aminomethyl-3,5,5-trimethylcyclohexylamine

[0209] 100.0 g (0.35 mol) of 2,2-dimethyl-3-lauroyloxypropanal was initially charged in a round-bottom flask under a nitrogen atmosphere. Then 27.9 g (0.16 mol) of 3-aminomethyl-3,5,5-trimethylcyclohexylamine (Vestamin® IPD, from Evonik) was added with good stirring and then the volatile constituents were removed at 80° C. and a reduced pressure of 10 mbar. What was obtained was a colorless liquid having an amine value of 153 mg KOH/g, corresponding to a calculated aldimine equivalent weight of 367 g/mol.

Aldimine A2

[0210] 100.00 g of a fractionated reaction mixture containing mainly branched 4-(C.sub.10-14-alkyl)benzaldehydes (obtained from formylation, catalyzed by means of HF-BF.sub.3, of C.sub.10-14-alkylbenzene, average aldehyde equivalent weight 290 g/eq) was initially charged in a round-bottom flask under a nitrogen atmosphere. 27.86 g of 3-aminomethyl-3,5,5-trimethylcyclohexylam ine (Vestamin® IPD, from Evonik) was added while stirring, and then the volatile constituents were removed at 80° C. and a reduced pressure of 10 mbar. What was obtained was a pale yellow, odorless liquid having an amine value of 150 mg KOH/g, corresponding to a calculated aldimine equivalent weight of 374 g/mol.

[0211] Aldimine A3: N,NBis(2,2-dimethyl-3-(N-morpholino)propylidene)-3-aminomethyl-3,5,5-trimethylcyclohexylamine

[0212] 100.0 g (0.58 mol) of 2,2-dimethyl-3-(N-morpholino)propanal was initially charged in a round-bottom flask under a nitrogen atmosphere. Then 47.4 g (0.28 mol) of 3-aminomethyl-3,5,5-trimethylcyclohexylamine (Vestamin® IPD, from Evonik) was added with good stirring and then the volatile constituents were removed at 80° C. and a reduced pressure of 10 mbar. What was obtained was a colorless liquid having an amine value of 227 mg KOH/g, corresponding to a calculated aldimine equivalent weight of 247 g/mol.

[0213] Aldimine A4: N,NBis(2,2-dimethyl-3-acetoxypropylidene)-3-aminomethyl-3,5,5-trimethylcyclohexylamine

[0214] 100.0 g (0.69 mol) of 2,2-dimethyl-3-acetoxypropanal was initially charged in a round-bottom flask under a nitrogen atmosphere. Then 56.2 g (0.33 mol) of 3-aminomethyl-3,5,5-trimethylcyclohexylamine (Vestamin® IPD, from Evonik) was added with good stirring, and then the volatile constituents were removed at 80° C. and a reduced pressure of 10 mbar. What was obtained was a colorless liquid having an amine value of 263 mg KOH/g, corresponding to a calculated aldimine equivalent weight of 213 g/mol.

Aldimine A5: N,NBis(2,2-dimethyl-3-lauroyloxypropylidene)hexylene-1,6-diamine

[0215] 100.0 g (0.35 mol) of 2,2-dimethyl-3-lauroyloxypropanal was initially charged in a round-bottom flask under a nitrogen atmosphere. Then 26.5 g (0.16 mol) of hexane-1,6-diamine solution (70% by weight in water) was added with good stirring, and then the volatile constituents were removed at 80° C. and a reduced pressure of 10 mbar. What was obtained was a colorless liquid having an amine value of 160 mg KOH/g, corresponding to a calculated aldimine equivalent weight of 351 g/mol.

Oxazolidine A6: Bisoxazolidine

[0216] To an initial charge of 63.09 g (0.6 mol) of diethanolamine in a round-bottom flask was added 178.09 g of a fractionated reaction mixture containing mainly branched 4-(C.sub.10-14-alkyl)benzaldehydes (obtained from formylation, catalyzed by means of HF-BF.sub.3, of C.sub.10-14-alkylbenzene, average aldehyde equivalent weight 290 g/eq) and 0.50 g of salicylic acid, and the reaction mixture was stirred at 80° C. under reduced pressure until all the water had been removed. A yellowish liquid having an amine value of 141.6 mg KOH/g was obtained. (=hydroxyl-functional monooxazolidine, intermediate)

[0217] 37.80 g of the hydroxyl-functional monooxazolidine thus obtained was initially charged in a round-bottom flask under a nitrogen atmosphere and heated up. At 80° C., 8.33 g of hexane 1,6-diisocyanate was added dropwise and then the mixture was stirred at 80° C. until no isocyanate groups were detectable any longer by means of IR spectroscopy. A highly viscous yellow oil that was liquid at room temperature and had an amine value of 116.4 mg KOH/g was obtained, which corresponds to a calculated equivalent weight for the oxazolidino groups of 482 g/mol.

Moisture-Curing Polyurethane Compositions

[0218] Compositions C-1 to C-10:

[0219] For each composition, the ingredients specified in table 1 were well mixed in the amounts specified (in parts by weight) by means of a planetary mixer under reduced pressure and with exclusion of moisture, and stored with exclusion of moisture.

[0220] The thickener paste was produced by gently heating an initial charge of 300 g of diisodecyl phthalate and 48 g of diphenylmethane 4,4diisocyanate (Desmodur® 44 MC L, from Covestro) in a vacuum mixer and then slowly adding 27 g of monobutylamine dropwise while stirring vigorously. The resultant paste was stirred for a further hour under reduced pressure while cooling.

[0221] Each composition was tested as follows:

[0222] Odor was assessed by smelling by nose at a distance of 2 cm from the freshly produced films. “Yes” means that an odor was clearly perceptible. “No” means that no odor was perceptible.

[0223] A measure determined for the processing time (open time) was the skin time (ST). For this purpose, a few grams of the composition were applied to cardboard in a layer thickness of about 2 mm and, under standard climatic conditions, the time until, when the surface of the composition was gently tapped by means of an LDPE pipette, there were for the first time no residues remaining any longer on the pipette was determined. “No cure” means that no skin had formed within 3 days.

[0224] Shore A hardness was determined to DIN 53505 on test specimens cured under standard climatic conditions for 3 d, 7 d, 11 d, 14 d, 21 d and 28 d.

[0225] Surface tack was assessed on the Shore A test specimens that had been cured under standard climatic conditions for 7 days.

[0226] For determination of mechanical properties, each composition was pressed between two wax-coated transfer printing papers to give a film of thickness 2 mm and stored under standard climatic conditions for 7 days. After the wax papers had been removed, some dumbbells having a length of 75 mm with a bar length of 30 mm and a bar width of 4 mm were punched out of the film, and these were tested to DIN EN 53504 at a strain rate of 200 mm/min for tensile strength (“TS”), elongation at break (“EaB”) and modulus of elasticity (“MoE”; at 0.5-5% elongation).

[0227] To determine the strength of an adhesive bond, lap shear strength (LSS) was determined on glass. For this purpose, test specimens were produced by bonding two glass plates that had been degreased with isopropanol and pretreated with Sika® Aktivator 100 (from Sika Schweiz) in such a way that the overlapping adhesive bond had dimensions of 12×25 mm and a thickness of 4 mm and the glass plates protruded at the top ends. After the composite bodies had been stored under standard climatic conditions for 7 d, lap shear strength was tested to DIN EN 1465 at a strain rate of 20 mm/min.

[0228] The results are reported in table 1.

[0229] The examples labeled (Ref.) are comparative examples.

TABLE-US-00001 TABLE 1 Composition and properties of C-1 to C-10. C-1 C-2 C-3 C-7 Composition (Ref.) (Ref.) (Ref.) C-4 C-5 C-6 (Ref.) Polymer P-1 30.0 30.0 — 30.0 30.0 30.0 — Polymer R-1 — — 30.0 — — — 30.0 Thickener paste 25.0 25.0 25.0 25.0 25.0 25.0 25.0 Chalk.sup.1 38.0 38.0 38.0 38.0 38.0 38.0 38.0 DIDP.sup.2 6.6 5.0 5.0 2.2 2.6 4.0 3.85 Aldimine — — — A1 A2 A3 A3 4.3 3.9 2.5 2.65 Oxazolidine A6 — — — — — — — SA solution.sup.3 — — 0.5 0.5 0.5 0.5 0.5 DBTDL soln..sup.4 — 2.0 2.0 — — — — Odor no no no no no no no ST no cure 40 h 10 h 2.5 h 8 h 1.5 h 1 h Shore A 3 d SCC n.d. 14 20 10 <10 15 31 31 36 18 18 21 36 33 36 23 23 25 41 33 36 25 25 27 42 33 36 28 27 31 43 33 36 31 28 31 44 Surface n.d. slightly nontacky nontacky nontacky nontacky nontacky tacky TS [MPa] n.d. 1.2 1.4 2.1 2.7 2.3 2.9 EaB [%] 555 623 1025 969 921 842 MoE [MPa] 1.4 1.7 1.1 1.2 1.1 2.3 LSS [MPa] n.d. 0.7 0.9 0.7 1.1 0.9 1.5 Composition C-8 C-9 C-10 Polymer P-1 30.0 30.0 30.0 Polymer R-1 — — — Thickener paste 25.0 25.0 25.0 Chalk.sup.1 38.0 38.0 38.0 DIDP.sup.2 4.3 2.4 1.5 Aldimine A4 A5 — 2.2 4.1 Oxazolidine A6 — — 5.0 SA solution.sup.3 0.5 0.5 0.5 DBTDL soln..sup.4 — — — Odor yes no no ST 2.5 h 1.5 h 1 h Shore A  3 d SCC 12 10 20  7 d SCC 24 15 21 11 d SCC 24 19 26 14 d SCC 27 21 29 21 d SCC 30 25 32 28 d SCC 32 27 35 Surface nontacky nontacky nontacky Tensile strength [MPa] 2.2 1.5 1.6 Elongation at break [%] 961 998 656 MoE [MPa] 1.1 0.7 0.6 LSS [MPa] 1.4 0.8 0.9 “n.d.” stands for “not determined” (no curing) .sup.1Omyacarb ® 5 GU (from Omya) .sup.2diisodecyl phthalate .sup.35% by weight of salicylic acid in dioctyl adipate .sup.44% by weight of dibutyltin dilaurate in diisodecyl phthalate

[0230] Table 1 shows the properties of isophorone diisocyanate-based compositions, which have very high light stability. In the case of these systems, because isophorone diisocyanate is sterically hindered, aliphatic and hence comparatively slow to react, the challenge is to achieve reliable curing to give a material having a tack-free surface and good mechanical properties. The comparison of reference compositions C-2 (low monomeric diisocyanate content, no blocked amine) and C-3 (high monomeric diisocyanate content, no blocked amine) shows that C-2, because of the lack of monomeric diisocyanates, exhibits significantly slower curing again and a tacky surface. In contrast, the comparison of inventive composition C-6 (low monomeric diisocyanate content, aldimine A-3) with reference composition C-7 (high monomeric diisocyanate content, aldimine A-3) shows that the inventive composition C-6 cures almost equally rapidly to give a nontacky material. Thus, the inventive use enables very light-stable compositions having no labeling obligation that, owing to high light stability and the tack-free surface, are particularly suitable for use in particularly exposed outdoor applications, for example on ships.

[0231] For determination of heat stability, some of the dumbbells punched out as described above were stored in an air circulation oven at 80° C. or 90° C. or 100° C. for 7 days, then cooled down to room temperature and tested as described above for tensile strength, elongation at break and modulus of elasticity. The results are given the addition “7d 80° C.” or “7d 90° C.” or “7d 100° C.”.

[0232] These results are reported in table 2.

[0233] The example labeled with (Ref.) is a comparative example.

TABLE-US-00002 TABLE 2 Heat stability of C-2 (Ref.), C-5, C-8 and C-10. C-2 Composition (Ref.) C-5 C-8 C-10 7 d 80° C.: Tensile strength [MPa] 1.6 2.8 3.3 1.5 Elongation at break[%] 786 805 833 256 MoE [MPa] 1.7 2.6 2.8 4.5 7 d 90° C.: Tensile strength [MPa] liquid 3.1 3.2 1.4 Elongation at break[%] 900 845 307 MoE [MPa] 1.5 1.7 3.6 7 d 100° C.: Tensile strength [MPa] liquid 1.0 not 1.2 Elongation at break[%] 990 determined 367 MoE [MPa] 1.0 2.7

[0234] Table 2 shows the limited heat stability of reference composition C-2, probably because of the high tin catalyst content.

[0235] Compositions C-11 to C-14:

[0236] For each composition, the ingredients specified in table 3 were well mixed in the amounts specified (in parts by weight) by means of a planetary mixer under reduced pressure and with exclusion of moisture, and stored with exclusion of moisture.

[0237] The thickener paste was produced as described for C-1.

[0238] Each composition was tested as follows:

[0239] As a measure of storage stability, the expression force of the composition after storage was determined by storing one closed cartridge in each case at room temperature for 7 days or at 60° C. in an air circulation oven for 7 days, and then measuring the expression force by means of an expression device (Zwick/Roell Z005). For this purpose, the cartridge, after being conditioned under standard climatic conditions for 12 hours, was opened, a nozzle of internal diameter 3 mm was screwed on to the cartridge and then the force required to express the composition through the nozzle at an expression rate of 60 mm/min was measured. The value reported is the average of the forces that were measured after an expression distance of 22 mm, 24 mm, 26 mm and 28 mm. The results are given the addition “7d RT” or “7d 60° C.” according to the manner of storage of the closed cartridge.

[0240] As a measure of processing time (open time), skin time was determined as described for composition C-1.

[0241] Shore A hardness was determined according to DIN 53505 on test specimens cured under standard climatic conditions for 1 d, 2 d and 7 d.

[0242] For determination of tensile strength, elongation at break, modulus of elasticity 0.5-50% elongation (“MoE 50%”) and tear propagation resistance, test specimens were produced and tested as described for composition C-1. For determination of the strength of adhesive bond, lap shear strength (LSS) was determined on glass after storage of the composite specimens under standard climatic conditions for 14 d, as described for composition C1. As a measure of the heat and hydrolysis stability of the bond, further composite specimens were additionally stored in an air circulation oven at 90° C. for 7 days or at 70° C./100% relative humidity for 7 days, cooled down under standard climatic conditions and tested in the same way. The results are given the addition “14d SCC” or “7d 90° C.” or “7d 70/100”.

[0243] 60% tensile stress (at 60% elongation) and 100% tensile stress (at 100% elongation) were determined with concrete test specimens (pretreated with Sika® Primer 3N, from Sika Schweiz) at 23° C. to DIN EN 28339, Method A.

[0244] The results are reported in table 3.

[0245] The examples labeled (Ref.) are comparative examples.

TABLE-US-00003 TABLE 3 Composition (in parts by weight) and properties of C-11 to C-14. C-12 C-13 C-14 Composition C-11 (Ref.) (Ref.) (Ref.) Polymer P-2 25.00 25.00 — — Polymer R-2 — — 25.00 25.00 Aldimine A1 0.90 — 1.0 — Thickener paste 23.00 23.00 23.00 23.00 Chalk.sup.1 40.00 40.00 42.50 42.50 Titanium dioxide 5.00 5.00 5.00 5.00 Diisodecyl phthalate 4.00 6.40 1.40 3.90 Epoxysilane.sup.2 0.50 0.50 0.50 0.50 Salicylic acid solution.sup.3 1.50 — 1.50 — Dibutyltin dilaurate 0.01 0.01 0.01 0.01 p-Toluenesulfonyl isocyanate 0.10 0.10 0.10 0.10 Expression force [N] 7 d RT 640 665 1111 1174 (3 mm nozzle) 7 d 60° C. 815 1205 1930 1925 Skin time [min] 80 65 65 40 Shore A 1 d SCC 30 35 36 49 2 d SCC 37 40 45 52 7 d SCC 38 42 46 53 Tensile strength [MPa] 1.62 1.57 1.86 1.80 Elongation at break [%] 620 560 530 380 Modulus of elasticity 50% [MPa] 1.13 1.46 1.69 2.16 Tear propagation resistance 7.1 7.2 7.4 7.6 [N/mm] LSS [MPa] 14 d SCC 0.84 0.94 1.12 1.19 7 d 90° C. 0.98 0.94 1.15 1.29 7 d 70/100 0.84 0.94 1.05 1.19 Tensile stress 60% 0.65 0.83 0.94 1.22 [MPa] 100% 0.72 0.84 0.97 tears .sup.1Omya BSH ® - OM (from Omya) .sup.23-Glycidoxypropyltrimethoxysilane .sup.35% by weight of salicylic acid in dioctyl adipate

[0246] Table 3 shows the properties of diphenylmethane 4,4diisocyanate-based compositions that have rapid curing because of its high reactivity. The challenge here is nevertheless to achieve good storage stability and processibility. The inventive composition C-11 (low monomeric diisocyanate content, aldimine A1) shows excellent storage stability coupled with very good processibility (small rise in expression force after 7d 60° C. coupled with low expression force value), whereas reference compositions C-12 (low monomeric diisocyanate content, no blocked amine), C-13 (high monomeric diisocyanate content, aldimine A1) and C-14 (high monomeric diisocyanate content, no blocked amine) all show a large rise in expression force after storage at 60° C. for 7 days and hence distinctly worse storage stability.