POLYURETHANE AND PROCESS FOR MAKING

Abstract

Polyurethanes are made by reacting, in one or more reaction steps, a) at least one organic polyisocyanate, b-1) one or more polyols having a hydroxyl equivalent weight of greater than 250 g/mol and a nominal hydroxyl functionality of 2 to 4 and b-2) at least one alkoxylated Mannich base to produce a polyurethane polymer having a density of at least 750 kg/m3 and a hard segment content of 20 to 80% by weight.

Claims

1. A polyurethane polymer having a density of at least 750 kg/m.sup.3 that is the reaction product of reactants that comprise: a) at least one organic polyisocyanate and b) polyols comprising b-1) one or more polyols having a hydroxyl equivalent weight of greater than 250 g/mol and a nominal hydroxyl functionality of 2 to 4 and b-2) one or more polyols having a hydroxyl equivalent weight of up to 250, wherein at least 50% by weight of b-2) is at least one alkoxylated Mannich base has an average hydroxyl functionality of 3 to 7; wherein the hard segment content of the polyurethane polymer is 20 to 80% by weight of the polyurethane polymer.

2. The polyurethane polymer of claim 1 wherein the alkoxylated Mannich base is represented by the structure: ##STR00002## wherein each R is independently hydrogen, linear or branched alkyl having 1 to 18 carbon atoms or linear or branched alkenyl having 1 to 18 carbon atoms, m is a number from 0 to 2, each R.sup.1 is independently hydrogen or linear or branched alkyl having 1 to 6 carbon atoms, each n is a number such that the hydroxyl equivalent weight is up to 250, x is a number from 1 to 2, R.sup.2 is hydrogen, alkyl having 1 to 6 carbon atoms, or phenyl, o is a number from 1 to 4 and p is 0 or 1.

3. The polyurethane polymer of claim 1, which contains no more than 10 ppm of zinc, tin and mercury combined and, except for the alkoxylated Mannich base, no more than 0.05 weight percent of amine group-containing compounds that have molecular weights below 350, based on the weight of the reaction mixture.

4. The polyurethane polymer of claim 1, which contains no more than 20 ppm of metals and in addition contains no more than 0.05 weight percent of amine group-containing compounds that have molecular weights of below 350 except for the alkoxylated Mannich base.

5. The polyurethane polymer of claim 1 wherein polyol b-1) has a hydroxyl equivalent weight of at least 400.

6. A process for making a polyurethane polymer comprising reacting, in one or more steps that include a final curing step in which the isocyanate index is 90 to 150, reactants comprising a) at least one organic polyisocyanate; and b) polyols comprising b-1) at least one polyol having a hydroxyl equivalent weight of greater than 250 g/mol, and b-2) one or more polyols having a hydroxyl equivalent weight of up to 250, wherein at least 50% by weight of b-2) is at least one alkoxylated Mannich base having an average hydroxyl functionality of 3 to 7; wherein the hard segment content of the polyurethane polymer is 20 to 80% by weight of the polyurethane polymer and the density of the polyurethane polymer is at least 750 kg/m.sup.3.

7. The process of claim 6 wherein the alkoxylated Mannich base is represented by the structure: ##STR00003## wherein each R is independently hydrogen, linear or branched alkyl having 1 to 18 carbon atoms or linear or branched alkenyl having 1 to 18 carbon atoms, m is a number from 0 to 2, each R.sup.1 is independently hydrogen or linear or branched alkyl having 1 to 6 carbon atoms, each n is a number such that the hydroxyl equivalent weight is up to 250, x is a number from 1 to 2, R.sup.2 is hydrogen, alkyl having 1 to 6 carbon atoms, or phenyl, o is a number from 1 to 4 and p is 0 or 1.

8. The process of any claim 6 wherein the final curing step is performed in the presence of no more than 10 ppm of zinc, tin and mercury combined and, except for the alkoxylated Mannich base, no more than 0.05 part by weight of amine group-containing compounds that have molecular weights below 350.

9. The process of claim 6 wherein the final curing step is performed in the presence of no more than 20 ppm of metals and no more than 0.05 weight percent of amine group-containing compounds that have molecular weights of below 350 except for the alkoxylated Mannich base.

10. The process of claim 6 wherein component a) is reacted with at least a portion of component b-1) to form a prepolymer or quasi-prepolymer having an isocyanate content of 1 to 20 percent by weight and in the final curing step, the prepolymer or quasi-prepolymer is reacted with polyol b-2) and any remaining portion of polyol b-1) at an isocyanate index of 90 to 150 to produce the polyurethane.

11. The process of claim 10 wherein the step of reacting component a) with at least a portion of component b-1) to form a prepolymer or quasi-prepolymer is performed in the presence of no more than 20 ppm of metals and, except for the alkoxylated Mannich base, no more than 0.05 weight percent of amine group-containing compounds that have molecular weights of below 350.

12. The process of claim 6 wherein component b-1) has a hydroxyl equivalent weight of at least 400.

13. A coating, adhesive, sealant or elastomer comprising the polyurethane polymer of claim 1.

14. A two-component sealant or adhesive composition comprising I. a prepolymer component comprising an isocyanate-terminated prepolymer or quasi-prepolymer having an isocyanate content of 1 to 20 percent by weight, the prepolymer or quasi-prepolymer being a reaction product of a) at least one organic polyisocyanate having an isocyanate equivalent weight of 80 to 250 and b-1) one or more polyols having a hydroxyl equivalent weight of greater than 250 g/mol and a nominal hydroxyl functionality of 2 to 4; and II. a separately packaged a curative component comprising b-2) one or more polyols having a hydroxyl equivalent weight of up to 250, wherein at least 50% by weight of b-2) is at least one alkoxylated Mannich base has an average hydroxyl functionality of 3 to 7.

15. A sealant or adhesive formed by combining components I and II of the two-component sealant or adhesive composition of claim 14 at a ratio that produces an isocyanate index of 90 to 150 to form a reaction mixture and curing the reaction mixture to form a sealant or adhesive that includes a polyurethane polymer corresponding to the reaction product of components I and II, the polyurethane polymer having a hard segment content of 20 to 80% by weight.

Description

EXAMPLES 1-4 AND COMPARATIVE SAMPLES A-D

[0058] Examples 1-4 are made by mixing, at room temperature, the prepolymer indicated in Table 1 with an alkoxylated Mannich base having a hydroxyl equivalent weight of 119 and a hydroxyl functionality of 3.5, to which has been added 0.65% benzoyl chloride. The alkoxylated Mannich base is made by alkoxylating a Mannich reaction product of nonyl phenol, formaldehyde and diethanolamine with propylene oxide and ethylene oxide. No catalyst (other than the alkoxylated Mannich base product) is present in the reaction mixture. The reaction mixture contains less than 20 ppm of metals and no amine compounds except for the alkoxylated Mannich base product. The isocyanate index is about 101. After thorough mixing, the reaction mixture is poured into a 6 in×6 in×0.015 in (15.24 cm×15.24 cm×0.38 mm) chase positioned upon a 0.38 mm aluminum plate that is coated with a mold release agent. A second aluminum plate is positioned over the filled chase. The assembly is cured for 2 hours at 60° C. in a molding press under pressure. The cured samples are allowed to sit at ambient conditions (23±3° C.) for one week prior to physical property testing.

[0059] Comparative Samples A-D are made in same manner, substituting a 450 number average molecular weight poly(propylene oxide) triol for the alkoxylated Mannich base and adding 0.05 parts by weight (based on combined weight of prepolymer and chain extender) of an organotin catalyst.

[0060] Tensile testing is performed according to ASTM D-1708. Water aged tensile testing is performed in the same manner after immersing a pre-weighed sample in deionized water at room temperature for 7 days, removing surface water and re-weighing the sample. Results are as indicated in Table 2 for the dry samples and Table 3 for the water-aged samples.

[0061] Thermal properties of Examples 1-3 and Comparative Samples A-D are evaluated by dynamic mechanical analysis using a TA Instruments ARES G2 Rheometer operated in torsion mode at 1 Hz and a heating rate of 3° C./minute. Glass transition temperature is taken as the peak of the tan delta curve, and is reported in Table 2.

TABLE-US-00002 TABLE 2 Dry Sample Properties Properties Hard Tensile Tensile Pre- Chain Segment Str., psi Modulus, psi T.sub.g, Sample polymer Extender Content, % (kPa) Elong., % (kPa) ° C. 1 PP-1 Mannich.sup.1 41.6 1078 261 1120 −6 A* PP-1 Triol 44.1 745 248 431 −10 2 PP-2 Mannich 53.4 2649 211 1344 16 B* PP-2 Triol 56.7 1986 266 597 8 3 PP-3 Mannich 63.8 3569 142 22354 37 C* PP-3 Triol 71.1 3267 219 1681 22 4 PP-4 Mannich 72.9 4207 87 82427 55 D* PP-4 Triol 77.0 3834 163 24080 32 .sup.1In this and subsequent tables, “Mannich” refers to the alkoxylated Mannich base.

TABLE-US-00003 TABLE 3 Water-Aged Sample Properties Properties Tensile Tensile Pre- Chain H.sub.2O Str., psi Modulus, psi Sample polymer Extender Absorption, % (kPa) Elong., % (kPa) 1 PP-1 Mannich 1.8 734 204 458 A* PP-1 Triol 2.3 507 184 435 2 PP-2 Mannich 1.8 1011 145 815 B* PP-2 Triol 2.1 885 181 579 3 PP-3 Mannich 1.8 2272 130 6967 C* PP-3 Triol 2.2 1061 157 713 4 PP-4 Mannich 1.9 3311 96 42123 D* PP-4 Triol 2.2 1898 153 2913

[0062] As the data in Tables 2 and 3 show, replacing the triol chain extender with the alkoxylated Mannich base leads to decreases in water absorption, and increases in tensile strength and modulus at equivalent or higher elongation. These results are achieved despite the absence of a separate urethane catalyst in the examples of the invention.

[0063] The storage modulus (G′) is measured for each of Examples 1-3 and Comparative Samples A-C by DMA at 150° C., 175° C. and 200° C. Results are as indicated in Table 4.

TABLE-US-00004 TABLE 4 Sam- Pre- Chain G′, Pa × 10.sup.7 ple polymer Extender 150 ± 1° C. 175 ± 1° C. 200 ± 1° C. 1 PP-1 Mannich 9.03 9.00 7.59 A* PP-1 Polyol 6.17 2.22 <<1 2 PP-2 Mannich 9.39 9.54 8.42 B* PP-2 Polyol 6.38 5.11 1.62 3 PP-3 Mannich 10.6 10.6 9.92 C* PP-3 Polyol 10.1 8.5 4.26

[0064] All of the Comparative Samples show a large decrease in storage modulus at temperatures above 150° C. Comparative Sample A loses over 85% of its storage modulus when heated from 150 to 200° C. Comparative Samples B and C lose about 75% and about 60% of their storage modulus over the same temperature range.

[0065] In contrast, Examples 1-3 not only have higher storage moduli at equivalent temperature (compared to Comparative Samples A-C, respectively), but also exhibit much less storage modulus loss at 175° C. and 200° C. Example 1 loses only about 17% of its 150° C. storage modulus when heated to 200° C.; Examples 2 and 3 demonstrate even smaller losses.

[0066] These results imply improved performance and stability when articles made using the elastomers of the invention in high-temperature applications.

[0067] Lap shear testing is performed using Example 1 and Comparative Sample A. 1″×6″×0.2″ (2.54×15.24×0.51 cm) glass coupons are cleaned with acetone and air-dried. A glass coupon is marked 2.0 inches (5.08 cm) from the end. The marked area is coating with freshly mixed reaction mixture (Ex. 1 or Comp. Sample A), together with 10 mil (0.254 mm) glass spacer beads. A second glass coupon is applied over the reaction mixture and secured with a metal clip. Edges are cleaned. Samples are allowed to cure at room temperature for one hour. The clip is removed, the samples are placed flat in a 60° C. oven for 2 hours and are then held at ambient room temperature conditions for 7 days. Samples are tested according to ASTM 1002-01. The lap shear strength of Example 1 is 101 psi (696 kPa), whereas that of Comp. Sample A is only 64.5 psi (445 kPa)

EXAMPLES 5-7 AND COMPARATIVE SAMPLES E AND F

[0068] Examples 5-7 and Comparative Samples E and F are made in the same general manner as Examples 1-4 and A-D, respectively. In each of Examples 5-7, the reaction mixture contains less than 20 ppm of metals and no amine compounds except for the alkoxylated Mannich base product. Physical property testing is performed as described with respect to the earlier examples. Results are as indicated in Tables 5 and 6.

TABLE-US-00005 TABLE 5 Dry Sample Properties Properties Hard Tensile Tensile Pre- Chain Segment Str., psi Modulus, psi T.sub.g, Sample polymer Extender Content, % (kPa) Elong., % (kPa) ° C. 5 PP-5 Mannich 23.7 352 252 211 −43 E* PP-5 Triol 25.3 294 170 290 −38 6 PP-6 Mannich 37.6 894 190 909 −37 7 PP-7 Mannich 50.2 2242 154 3906 −38 F* PP-7 Triol 53.8 1950 240 890 −44

TABLE-US-00006 TABLE 6 Water-Aged Sample Properties Properties Tensile Tensile Pre- Chain H.sub.2O Str., psi Modulus, psi Sample polymer Extender Absorption, % (kPa) Elong., % (kPa) 5 PP-5 Mannich 1.7 315 233 252 E* PP-5 Triol 1.8 263 142 350 6 PP-6 Mannich 1.9 708 175 494 7 PP-7 Mannich 1.5 1444 127 2758 F* PP-7 Triol 1.9 849 177 612

[0069] As before, tensile strength is increased and moisture absorption is decreased by substituting the alkoxylated Mannich base for the polyether triol chain extender at equivalent index.

EXAMPLES 8-12

[0070] Examples 8-12 are made in the same general manner as Examples 1-4. In each case, the reaction mixture contains less than 20 ppm of metals and no amine compounds except for the alkoxylated Mannich base product. Physical property testing is performed as described with respect to the earlier examples. Results are as indicated in Tables 7 and 8.

TABLE-US-00007 TABLE 7 Dry Sample Properties Properties Hard Tensile Tensile Pre- Chain Segment Str., psi Modulus, psi T.sub.g, Sample polymer Extender Content, % (kPa) Elong., % (kPa) ° C. 8 PP-8 Mannich 37.5 1067 217 1113 −47 9 PP-9 Mannich 48.1 2386 286 2606 14 10 PP-10 Mannich 41.6 1160 197 1238 −5 11 PP-11 Mannich 35.5 822 209 818 −52 12 PP-12 Mannich 41.6 1150 213 602 −8

TABLE-US-00008 TABLE 8 Water-Aged Sample Properties Properties Tensile Tensile Pre- Chain H.sub.2O Str., psi Modulus, psi Sample polymer Extender Absorption, % (kPa) Elong., % (kPa) 8 PP-8 Mannich 2.8 546 152 456 9 PP-9 Mannich 2.0 1157 227 524 10 PP-10 Mannich 1.7 759 156 593 11 PP-11 Mannich 1.6 1066 245 388 12 PP-12 Mannich 0.5 722 164 504

Comparative Samples G and H

[0071] Following the general procedure described in the preceding examples, Comparative Samples G and H are prepared by reacting PP-1 with a 700 molecular weight, trifunctional, aliphatic poly(propylene oxide) (Comp. G) and a pp 195 equivalent weight, 3.3-functional, epoxy novolac-initiated polyether polyol (Comp. H) in the presence of an organotin catalyst at a 101 index.

[0072] Comparative Sample H has a somewhat higher tensile strength (2.9 MPa vs. 1.95 MPa), elongation (143% vs. 112) and tensile modulus (3.3 MPa vs. 2.8 MPa) than Comparative Sample G, showing the effect of substituting an aromatic-based curative for an aliphatic curative. However, unlike the examples of the invention, Comparative Sample H exhibits a loss of at least 80% of its storage modulus when heated from about 120° C. to 150° C. Storage modulus for Comparative Sample H is only about 1×10.sup.6 Pa at 150° C. These results indicate that the excellent thermal properties of the invention are not due merely to the presence of aromatic groups in the alkoxylated Mannich base.