REACTION MIXTURES OF ISOCYANATES AND POLYOLS WITH EXTENDED POT LIFE

Abstract

The invention relates to compounds and methods for extending the pot life of mixtures of isocyanates and isocyanate-reactive compounds when using acidic phosphoric acid ester as a mould release agent.

Claims

1.-14. (canceled)

15. A process for producing a coating composition having an extended pot life which contains at least one isocyanate A1 and an isocyanate-reactive compound C, containing the steps of a) providing a composition containing an isocyanate A and an acidic phosphoric ester B; b) mixing the composition from process step a) with an isocyanate A1; and c) mixing the product from process step b) with at least one isocyanate-reactive compound C.

16. The process as claimed in claim 15, wherein the isocyanate A is an aliphatic, cycloaliphatic, araliphatic or aromatic isocyanate or a mixture thereof.

17. The process as claimed in claim 15, wherein the isocyanate A contains at least one monomeric or oligomeric isocyanate not present in the isocyanate A1.

18. The process as claimed in claim 15, wherein the isocyanate A contains only isocyanates also present in isocyanate A1.

19. The process as claimed in claim 15, wherein the isocyanate-reactive compound C is a polyol, a polyamine or a polythiol.

20. The process as claimed in claim 15, wherein the weight ratio of isocyanate A to acidic phosphoric ester B is not more than 2.0:1.0.

21. The process as claimed in claim 20, wherein the weight ratio of isocyanate A to acidic phosphoric ester B is between 2.0:1.0 and 1.0:8.0.

Description

EXAMPLES

[0092] All percentages are based on weight unless otherwise stated. Unless stated otherwise, all values relate to a temperature of 23° C.

[0093] The different polyisocyanates and the polyols were obtained from Covestro AG (DE); Zelec UN from Stepan (www.stepan.com); the catalyst TIB-Kat VP 13-262 F from TIB Chemicals (DE); the polythiols from Bruno Bock (DE). Zelec UN was employed as obtained.

[0094] Polyol W is a polypropylene oxide polyether based on trimethylolpropane as the starter molecule with an OH number of 550 mg/g and a viscosity of about 1800 mPas. Polyol X is a polypropylene oxide polyether based on glycerol as the starter molecule with an OH number of 570 mg/g and a viscosity of about 660 mPas. Polyol Y is a polythioether with an SH content of about 36% and a viscosity of <10 mPas. Polyol Z is a polyester composed of pentaerythritol and mercaptopropionic acid with an SH content of about 26% and a viscosity of about 400 mPas.

[0095] The masterbatch was produced by mixing the respective diisocyanate with Zelec UN. The mixing apparatus employed was a Speed-Mixer (type DAC 150 FVZ) from Hauschild (DE) (1 min at 3000 rpm). The masterbatch was subsequently left to stand for 24 hours at room temperature.

[0096] To determine pot life the viscosity of the respective mixture was determined with a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) according to DIN EN ISO 3219.

[0097] The reaction mixtures composed of polyisocyanate, polyol, catalyst and masterbatch or Zelec UN were likewise produced in a Speed-Mixer (type DAC 150 FVZ) from Hauschild (DE) (1 min at 3000 rpm).

[0098] The samples for determining the viscosity increase were produced according to the following formulation: [0099] a) Comparative examples: the isocyanate component is admixed with 3.74% by weight (based on the isocyanate component) of Zelec UN. The polyol component, in an NCO:OH ratio of 1.12, and 0.0196% by weight (based on eq NCO groups) of catalyst are subsequently added. The composition is mixed in the speed mixer for 1 minute at 3000 rpm and immediately transferred into the rheometer to determine viscosity. The column “Variant” in table 1 specifies the duration of the wait time from the mixing of the isocyanate component and Zelec UN to the addition of polyol and catalyst. [0100] b) Inventive examples: the isocyanate component is mixed with 7.48% by weight (based on the isocyanate component) of masterbatch and subsequently mixed with the polyol component in an NCO:OH ratio of 1.12. 0.0196% by weight (based on eq NCO groups) of catalyst is subsequently added. The composition is mixed in the speed mixer for 1 minute at 3000 rpm and immediately transferred into the rheometer to determine viscosity. The column “Variant” in tables 1 and 2 specifies the duration of the wait time from the mixing of the isocyanate component and masterbatch to the addition of polyol and catalyst.

TABLE-US-00001 TABLE 1 Viscosity Viscosity Viscosity Viscosity after after after after Variant Isocyanate Polyol 15 min 30 min 45 min 60 min Comp.Ex. 1 immediately HDI W 29 43 78 88 Comp. Ex. 2 immediately H12-MDI W 312 1010 2100 3690 Comp. Ex. 3 immediately XDI W 54 136 356 788 Comp. Ex. 4 immediately IPDI W 347 812 1910 2910 Inv. Ex. 1 immediately HDI W 28 45 56 66 Inv. Ex. 2 immediately H12-MDI W 430 729 1120 1680 Inv. Ex. 3 immediately XDI W 55 96 159 240 Inv. Ex. 4 immediately IPDI W 174 213 252 256 Comp. Ex. 5 after 24 h HDI W 261 773 2220 6010 Comp. Ex. 6 after 24 h H12-MDI W 35 65 104 152 Comp. Ex. 7 after 24 h XDI W 820 3920 13000 solid Comp. Ex. 8 after 24 h IPDI W 68 285 1290 4300 Inv. Ex. 5 after 24 h HDI W 165 195 238 295 Inv. Ex. 6 after 24 h H12-MDI W 33 44 58 72 Inv. Ex. 7 after 24 h XDI W 463 805 1310 2380 Inv. Ex. 8 after 24 h IPDI W 71 151 322 744 Comp. Ex. 9 immediately IPDI/HDI (1:1) W 110 262 463 682 Comp. Ex. 10 immediately IPDI/H12-MDI (1:1) W 346 758 1630 2520 Comp. Ex. 11 immediately IPDI/XDI (1:1) W 171 286 466 623 Inv. Ex. 9 immediately IPDI/HDI (1:1) W 94 95 111 126 Inv. Ex. 10 immediately IPDI/H12-MDI (1:1) W 134 205 226 267 Inv. Ex. 11 immediately IPDI/XDI (1:1) W 114 146 175 216 Comp. Ex. 12 immediately IPDI/N3200 W 366 584 948 1340 Comp. Ex. 13 immediately IPDI/N3600 W 522 1140 2610 4100 Comp. Ex. 14 immediately IPDI/N3900 W 583 963 1620 2360 Inv. Ex. 12 immediately IPDI/N3200 W 235 252 268 328 Inv. Ex. 13 immediately IPDI/N3600 W 279 322 395 462 Inv. Ex. 14 immediately IPDI/N3900 W 308 412 602 777 Inv. Ex. 15 immediately/ HDI W 21 25 18 29 masterbatch 4 weeks old Inv. Ex. 16 immediately/ H12-MDI W 179 248 251 252 masterbatch 4 weeks old Inv. Ex. 17 immediately/ XDI W 49 50 83 144 masterbatch 4 weeks old Inv. Ex. 18 immediately/ IPDI W 109 125 134 155 masterbatch 4 weeks old Comp. Ex. 15 immediately H12-MDI X 206 277 423 640 Comp. Ex. 16 immediately IPDI X 115 158 215 289 Inv. Ex. 19 immediately H12-MDI X 134 154 204 224 Inv. Ex. 20 immediately IPDI X 93 98 105 113 Comp. Ex. 17 immediately H12-MDI Y 34 34 34 35 Comp. Ex. 18 immediately XDI Z 30 32 34 36 Inv. Ex. 21 immediately H12-MDI Y 33 33 33 33 Inv. Ex. 22 immediately XDI Z 29 30 32 33

[0101] Table 1 demonstrates very clearly the effect of a masterbatch. The viscosity of the 2-component mixture increases very much less over the course of the measurements (over 1 hour in each case) than in the case of direct addition of the acidic phosphoric ester to the isocyanate component. This effect is observed not only for monomeric diisocyanates (examples 1-4) and for mixtures of different monomeric diisocyanates (examples 9-11) but also for mixtures of monomeric diisocyanates with different isocyanate derivatives (examples 12-14). It is immaterial whether the procedure comprises adding the masterbatch to the isocyanate component before immediately producing the 2-component mixture and observing its viscosity profile (examples 1-4 and 9-14) or whether it comprises adding the masterbatch to the isocyanate component before allowing said component to undergo a period of maturation (24 h in the examples) and only then producing the 2-component mixture and observing its viscosity profile (examples 5-8).

[0102] The effect of the masterbatch is not limited to a particular polyol but is also apparent for low-viscosity polyols (examples 19-20) and for polythiols (examples 21-22) even if the reduction in viscosity is less pronounced here on account of the low viscosity of the polyols/polythiols.

[0103] Finally, examples 15-18 show that the effect of a masterbatch is not dependent on its age. Here, a 4 week old masterbatch was used to produce the formulation and gave comparable or even lower viscosity values compared to a freshly produced masterbatch (see inventive examples 1-4).

[0104] The use of a masterbatch thus allows for much more economic production of low-viscosity 2-component polyurethane compositions since it allows immediate use of the 2-component mixture with no need to adhere to an incubation time. A masterbatch may moreover be employed over several weeks so that temporal decoupling of the production of the masterbatch and the use thereof is possible.

[0105] The masterbatch composed of acidic phosphoric ester and isocyanate may be varied within wide limits. Table 2 shows the viscosities of various masterbatch mixtures of H12-MDI and Zelec with polyol X obtained immediately after production.

TABLE-US-00002 TABLE 2 H12-MDI: Viscosity after Viscosity after Viscosity after Viscosity after Zelec ratio 15 min 30 min 45 min 60 min Inv. Ex. 23 4:1 213 288 n.d. n.d. Inv. Ex. 24 2:1 157 217 262 337 Inv. Ex. 25 1:2 124 144 158 174 Inv. Ex. 26 1:4 150 183 236 290 n.d.: not determined

[0106] It is apparent here that example 23 comprising the smallest amount of Zelec is at a similar viscosity level to the variant without masterbatch (see comparative example 15). By contrast, from a ratio of isocyanate to acidic phosphoric ester of 2:1 up to greatly elevated concentrations of acidic phosphoric ester a marked reduction in viscosity of the 2-component mixture is apparent.