Process for making urethane-isocyanates

Abstract

Polyisocyanurate or polyurethane-isocyanurate polymers are made by curing an aromatic polyisocyanate or a mixture of at least one aromatic polyisocyanate and at least one polyol having a hydroxyl equivalent weight of up to 200 in which the isocyanate index is at least 2.00, in the presence of at least one isocyanate trimerization catalyst, to form a polyisocyanurate or polyurethane-isocyanurate polymer having a glass transition temperature of at least 100° C., and then exposing the polyisocyanurate or polyurethane-isocyanurate polymer formed step a) to water under superatmospheric pressure at a temperature of at least 70° C.

Claims

1. A method for making an isocyanurate or polyurethane-isocyanurate polymer, comprising a) curing an aromatic polyisocyanate or a mixture of at least one aromatic polyisocyanate and at least one polyol having a hydroxyl equivalent weight of up to 200 in which the isocyanate index is at least 2.00, in the presence of at least one isocyanate trimerization catalyst, to form a polyisocyanurate or polyurethane-isocyanurate polymer having a glass transition temperature of at least 100° C., and b) exposing the polyisocyanurate or polyurethane-isocyanurate polymer formed step a) to water in that is at least partly in the form of a liquid at a temperature of 70° C. to 140° C. and a pressure of 150 kPa to 5000 kPa.

2. The method of claim 1 wherein step a) is performed in the absence of a blowing agent to produce a polyisocyanurate or polyurethane-isocyanurate polymer having a density of at least 750 kg/m.sup.3.

3. The method of claim 2 wherein step a) is performed in the absence of a blowing agent to produce a polyisocyanurate or polyurethane-isocyanurate polymer having a density of at least 950 kg/m.sup.3.

4. The method of claim 1 wherein after step b) the polyisocyanurate or polyurethane-isocyanurate polymer has a density of at least 750 kg/m.sup.3.

5. The method of claim 4 wherein after step b) the polyisocyanurate or polyurethane-isocyanurate polymer has a density of at least 950 kg/m.sup.3.

6. The method of claim 1 wherein in step a) a mixture of at least one aromatic polyisocyanate and at least one polyol having a hydroxyl equivalent weight of up to 2.0 is cured, in the presence of at least one isocyanate trimerization catalyst and at least one urethane catalyst to form a polyurethane-isocyanurate polymer.

7. The method of claim 6 wherein the isocyanate index is 2.5 to 6.

8. The method of claim 7, wherein the glass transition temperature of the polyisocyanurate or polyurethane-isocyanurate polymer obtained in step a) is 150 to 225° C.

9. The method of claim 1, wherein step a) is performed by coating the aromatic polyisocyanate or the mixture of at least one aromatic polyisocyanate and at least one polyol onto the surface of a substrate, and curing the aromatic polyisocyanate or the mixture on the surface of the substrate to form a coating thereon.

10. The method of claim 1, wherein step a) is performed by is applying the polyisocyanurate or the mixture of at least one aromatic polyisocyanate and at least one polyol to a fibrous reinforcement and then curing the polyisocyanate or the mixture in the presence of the reinforcement to form a fiber-reinforced composite that includes a fiber phase that includes the fibrous reinforcement embedded in and bound together by the polyisocyanurate or polyurethane-isocyanurate polymer.

11. The method of claim 1 wherein the temperature in step b) is 100 to 130° C.

12. The method of claim 1 wherein step b) is performed for a period of time sufficient to increase the glass transition temperature of the polyisocyanurate or polyurethane-isocyanurate polymer by at least 5° C.

13. The method of claim 1, wherein step b) is performed during the use of the polyisocyanurate or polyurethane-isocyanurate polymer in its intended application.

14. The method of claim 1, wherein step b) is performed as a separate manufacturing step apart from use of the polyisocyanurate or polyurethane-isocyanurate polymer in its intended application.

Description

EXAMPLES

(1) Polyisocyanurate (Ex. 9) and polyisocyanurate-polyurethane polymers are prepared in the following general process:

(2) For step a): the polyol (if any) is charged into the mixing cup of a high-speed laboratory mixer (FlackTek SpeedMixer). The catalyst(s) are then added and mixed thoroughly into the polyol at 800 rpm for 5 seconds, followed by 2000 rpm for 10 seconds. The polyisocyanate is then added into the mixing cup and mixed with the other components at the same mixing condition. The resulting reaction mixture is emptied onto a circular steel mold 14 cm in diameter and 0.5 cm deep, which has been previously sprayed with a mold release agent (STONER E236 mold release). The amount of reaction mixture in each case is about 50 grams. The reaction mixture is allowed to cure without applied heat until it has cured enough to demold. The resulting molding is then in each case postcured under air under conditions of time and temperature was indicated below.

(3) Samples are cut from each molding. Some of the samples are taken to dynamic mechanical thermal analysis (DMTA). DMTA measurements are taken using an oscillation frequency of 1 sec.sup.−1 and a heating rate of 3° C./minute. The glass transition temperature is taken in each case as the peak of the tan delta curve. The storage modulus is measured at 50° C. and 121° C.

(4) Step b) is performed on samples cut from the moldings made in step a). The samples are immersed in deionized water in a Parr reactor. The headspace is charged to 500 psi (3450 kPa) with nitrogen and released three times to purge out residual oxygen. The headspace is then charged again to 500 psi (3450 kPa) with nitrogen and sealed. The sealed reactor is then heated to 121° C. for seven days. The reactor contents are allowed to come to room temperature. The samples are then removed and submerged in deionized water in a 50° C. oven until taken for DMTA analysis as before. Samples are removed from the 50° C. water bath immediately before DMTA analysis. Glass transition temperature is measured, as is the storage modulus G′ at both 50° C. and 121° C.

(5) The materials used in the following examples are as follows: POLYOL A is a poly(propylene oxide) triol having a hydroxyl equivalent weight of 85. POLYOL B is 1,4-butane diol. POLYOL C is glycerin. POLYOL D is trimethylolpropane. POLYISOCYANATE A is a polymeric MDI having an isocyanate equivalent weight of 136.5 and a nominal isocyanate functionality of 3.0. POLYISOCYANATE B is a polymeric MDI having an isocyanate equivalent weight of 131.5 and a nominal isocyanate functionality of 2.3. POLYISOCYANATE C is a polymeric MDI having an isocyanate equivalent weight of 134 and a nominal isocyanate functionality of 2.7. Trimerization Catalyst A is a (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate salt solution in ethylene glycol, available from Air Products and Chemicals as DABCO® TMR catalyst. Trimerization Catalyst B is a solution of potassium acetate in ethylene glycol. It is available from Air Products and Chemicals as Polycat® 46 catalyst. Trimerization Catalyst C is a blend of trimerization catalysts, available from Ele Corporation as PEL-CAT 9887-E. Trimerization Catalyst D is a blend of trimerization catalysts, available from Ele Corporation as PEL-CAT 9887-G. Urethane Catalyst A is a dibutyltin dilaurate catalyst sold by Air Products and Chemicals as DABCO® T-12. Urethane Catalyst B is a 33% by weight solution of triethylendiamine in dipropylene glycol. The Epoxy Resin is a diglycidyl ether of bisphenol A having an epoxy equivalent weight of 180.

Example 1 and Comparative Samples A, B and C

(6) The formulations and test results for Example 1 and Comparative Samples A, B and C are given in Table 1.

(7) TABLE-US-00001 TABLE 1 Comp. Ex. Comp. Ex. Comp. Ex. A B C 1 Parts by Weight Formulation Polyol A 18 16 14 10 Polyisocyanate A 28.9 29.6 33.7 48.2 Trimerization Catalyst A 0 0 0 0.10 Urethane Catalyst A 0.05 0.04 0.02 0.04 Isocyanate Index 1.0 1.15 1.5 3.0 Postcure temperature 154/63 147/33 147/180 147/180 (° C.)/time (min) Properties T.sub.g after postcure (° C.) 164 162 166 136 121° C. G′ on 6.5 6.6 6.2 4.7 postcured sample (10.sup.8 Pa) T.sub.g after humid 115 128 143 203 aging (° C.) 121° C. G′ on 0.072 0.23 1.8 6.5 humid aged sample (10.sup.8 Pa)

(8) Comparative Samples A, B and C show the effect of varying isocyanate index without trimerization catalyst. As can be seen, the variations in isocyanate index have little effect on the glass temperature of the postcured sample. In each case, the glass transition temperature falls within a small range of 162-166° C., despite significant differences in the postcuring times and smaller differences in postcuring temperatures. The high glass transition temperature of Comparative Sample B (it being comparable to Comparative Samples A and C) indicates that the relatively mild postcuring conditions used in Comparative Sample B are adequate to achieve nearly full cure.

(9) The effects of humid aging are indicated by the changes in G′ at 121° C. and in the glass transition temperature. In the best of the Comparative Samples (C), the glass transition drops to below 150° C. (a loss of 23° C.), and the G′ is reduced by about 70%. The performance of Comparative Samples A and B is even worse.

(10) Example 1 performs much differently. After humid aging, the glass transition temperature of Example 1 material actually increases, very substantially, to 203° C. This value is much higher than any of the other samples, even before humid aging. 121° C. G′ also increases, which is contrary to the behavior of the Comparative Samples.

Examples 2-9 and Comparative Sample D

(11) The formulations and test results for Examples 2-9 and Comparative Sample D are given in Table 2.

(12) TABLE-US-00002 TABLE 2 D* 2 3 4 5 6 7 8 9 Formulation Parts by Weight Polyol A 14.7 10 7.6 7.6 7.6 7.6 10 10 0 Polyisocyanate A 35.4 40.1 42.7 42.7 42.7 42.7 40.1 40.1 15 Trimerization 0.15 0.15 0.25 0.25 0.05 0.05 0.15 0.15 0 Catalyst A Urethane Catalyst A 0.05 0.10 0.08 0.08 0.08 0.08 0.05 0.05 0.6 Isocyanate Index 1.5 2.5 3.5 3.5 3.5 3.5 2.5 2.5 N/A Postcure 160/ 120/ 80/ 160/ 160/ 80/ 160/ 80/ 80/ temperature 60 65 70 60 60 70 60 60 25 (° C.)/time (min) Properties T.sub.g after postcure 184 167 163 165 147 153 184 178 244 (° C.) 121° C. G′ on 7.2 10.6 10 8.4 10.7 2.3 8.2 8.2 2.8 postcured sample (10.sup.8 Pa) T.sub.g after humid 134 190 203 197 198 187 201 180 225 aging (° C.) 121° C. G′ on humid 0.36 2.6 4.8 10 3.4 2.3 5.2 6.1 3.0 aged sample (10.sup.8 Pa) *Not an example of the invention.

(13) Comparative Sample D is made at a 1.50 index, and in the presence of a trimerization catalyst. At this index, a large loss of glass transition temperature and 121° C. G′ is seen after humid aging. By contrast, in each of Examples 2-8, glass transition temperature increases after the humid aging. The 121° G′ values of these examples in some instances is higher and other instances is lower than those of the corresponding postcured samples. However, in all cases, they are much higher than Comparative Sample D, usually by almost an order of magnitude if not more. Example 9 differs from the others in being a polyisocyanurate rather than a polyisocyanurate-urethane. This one develops an especially high glass transition temperature after postcuring. After humid aging, some loss of glass transition temperature is seen, but the glass transition temperature nonetheless remains higher than any of the other samples.

Examples 10-14

(14) The formulations and test results for Examples 10-14 are given in Table 3.

(15) TABLE-US-00003 TABLE 3 10 11 12 13 14 Parts by Weight Formulation Polyol A 8.7 6.8 8.9 7.0 8.9 Polyisocyanate B 0 0 41.1 43.0 41.1 Polyisocyanate C 41.3 43.2 0 0 0 Trimerization Catalyst A 0.25 0.25 0.25 0.25 0.25 Urethane Catalyst A 0.09 0.09 0.09 0.09 0.09 Isocyanate Index 3.00 4.00 3.00 4.00 3.00 Postcure temperature 120/60 120/60 120/60 120/60 120/60 (° C.)/time (min) Properties T.sub.g after postcure (° C.) 166 181 201 205 198 121° C. G′ on 8.2 5.8 4.8 3.5 4.5 postcured sample (10.sup.8 Pa) T.sub.g after humid 195 208 214 217 218 aging (° C.) 121° C. G′ on 3.8 4.8 1.0 3.9 1.2 humid aged sample (10.sup.8 Pa)

(16) As with previous examples, the glass transition temperature increases after the humid aging step, with relatively small decreases in G′. G′ actually increases for Example 13.

Examples 15-19

(17) The formulations and test results for Examples 10-14 are given in Table 3.

(18) TABLE-US-00004 TABLE 3 15 16 17 18 19 Parts by Weight Formulation 1,4-butanediol 4.3 3.5 3.5 0 0 Trimethylolpropane 0 0 0 3.5 0 Glycerin 0 0 0 0 2.1 Polyisocyanate A 45.7 36.6 36.6 36.8 27.9 Epoxy Resin 0 0 10 10 7 Trimerization Catalyst A 0.15 0.15 0.15 0.15 0.10 Urethane Catalyst A 0.01 0.01 0.01 0.01 0.03 Isocyanate Index 3.5 3.5 3.5 3.5 3.0 Postcure temperature 160/60 120/60 160/60 160/60 120/60 (° C.)/time (min) Properties T.sub.g after postcure (° C.) 218 159 224 223 179 121° C. G′ on 1.5 1.9 2.8 2.4 3.9 postcured sample (10.sup.8 Pa) T.sub.g after humid 215 208 241 248 233 aging (° C.) 121° C. G′ on 5.6 6.3 6.2 1.6 4.7 humid aged sample (10.sup.8 Pa)

(19) The glass transition temperature increases after the humid aging step in each case except Example 15. These sample show an increase in G′.