Polyester-modified polybutadienols for producing polyurethane elastomers and thermoplastic polyurethanes

Abstract

The invention relates to polyurethanes obtainable by reaction of (a) polyisocyanates A selected from modified or unmodified 4,4′-methanediphenyl diisocyanate, higher nuclear homologs of 4,4′-methanediphenyl diisocyanate, isocyanated groups containing prepolymers based on 4,4′-methanediphenyl diisocyanate, and mixtures thereof, with (b) compounds having at least two isocyanate-reactive hydrogen atoms, comprising (b1) block copolymers formed from a polybutadienol and a cyclic ester as component B1, and (b2) low molecular weight extenders or crosslinkers each having a molecular weight of 62 to 500 g/mol as component B2.

Claims

1. A polyurethane obtainable by reaction of: a) 30 to 150 parts by weight of polyisocyanates A selected from the group consisting of modified 4,4′-methanediphenyl diisocyanate, unmodified 4,4′-methanediphenyl diisocyanate, higher nuclear homologs of 4,4′-methanediphenyl diisocyanate, isocyanate groups containing prepolymers based on 4,4′-methanediphenyl diisocyanate and polyetherols, and mixtures thereof, b1) 100 parts by weight of block copolymers formed from a polybutadienol and a cyclic ester as component B1, b2) 4 to 15 parts by weight of at least one of diols as low molecular weight extenders and triols as crosslinkers, each having a molecular weight of 62 to 500 g/mol as component B2, c) 0 to 100 parts by weight of polymeric compounds C having at least 2 isocyanate-reactive hydrogen atoms, selected from the group consisting of polyetherols, polycarbonate, polyols and polyesterols having a molecular weight of 500 to 12,000 g/mol and an average functionality of 2 to 6, d) 0 to 5 parts by weight of catalysts D, e) 0 to 3 parts by weight of water E, f) 0 to 10 parts by weight of physical blowing agents F, and g) 0 to 100 parts by weight of auxiliaries, added-substance materials, and mixtures thereof as component G, selected from the group consisting of surface-active substances, foam stabilizers, cell regulators, release agents, fillers, dyes, pigments, hydrolysis control agents, flame retardants, odor-absorbent substances, fungistatically active substances and bacteriostatically active substances; wherein the polyisocyanates A are reacted with a mixture of components b1), b2) and optionally one or more of components c), d), e), f), and g), wherein the polyol component B1 has a number average molecular weight in the range from 600 to 15,000 g/mol, an ε-caprolactone fraction of from 10 to 50 wt. %, and an OH functionality of 1.5 to 2.2, and wherein the extender of component B2 is 1,4-butanediol.

2. The polyurethane according to claim 1, wherein the cyclic ester is selected from the group consisting of ε-caprolactone, 1,6-dioxacyclododecane-7,12-dione and oxacyclodecan-2-one.

3. The polyurethane according to claim 1, wherein the crosslinker of component B2 is selected from the group consisting of ethoxylated glycerol, propoxylated glycerol, mixtures thereof, and trimethylolpropane.

4. The polyurethane according to claim 1, wherein a) includes 30 to 150 parts by weight of polyisocyanates A selected from the group consisting of modified 4,4′-methane diphenyldiisocyanate, unmodified 4,4′-methanediphenyl diisocyanate, higher nuclear homologs of 4,4′-methanediphenyl diisocyanate and mixtures thereof.

Description

EXAMPLES

(1) Table 1 shows an overview of possible polyols based on polybutadiene. Polyol 4 is a post-functionalized polybutadiene. Table 1 further lists a purely polycaprolactone polyester (Capa® 2200, Perstorp Holding, Perstorp, Sweden) as polyol 5.

Example 1

Preparation of Polyol 4

(2) In a conical 10 L steel reactor, 680 g of Lithene® PM4 (from Synthomer, Essex, UK) were dissolved in 3850 g of toluene and heated to 60° C. Following addition of 59.5 g of 98 wt % formic acid the contents were intimately mixed at 400 rpm. Hydrogen peroxide was added at a weight of 40 mL/h continuously over 7.5 hours. The reaction mixture was then washed twice with saturated sodium bicarbonate solution and once with saturated sodium chloride solution.

(3) The organic phase was dried with sodium sulfate and the solvent was removed at 60° C. under reduced pressure.

(4) Conversion of double bonds: 6.9%; epoxy value after Jung & Kleeberg: 0.104 mol of epoxy/100 g of polymer; color: pale yellow; viscosity: 0.687 Pa.Math.s (40° C.)

(5) In a 6 L glass reactor, 520 g of the epoxidized Lithene® PM4 were dispersed in 2080 g of 1-propanol and heated to 65° C. Following addition of 1.56 mL of a 10 wt % solution of trifluoromethanesulfonic acid in 1-propanol (100 ppm), the contents were stirred for 6 hours. The mixture was neutralized in sodium bicarbonate, cooled down and filtered. The propanol was removed from the filtrate at up to 95° C. under reduced pressure.

(6) OH number: 52.11; color: pale yellow; viscosity: 1.09 Pa.Math.s (40° C.)

(7) Further polyols used are described in Table 1.

(8) TABLE-US-00001 TABLE 1 hydroxyl-functionalized polybutadienes Designation Polyol 1 Polyol 2 Polyol 3 Polyol 4 Polyol 5 Polybutadienol Krasol ® LBH Krasol ® LBH PolyBD R45 Hydroxylated (Capa ® P2000 P3000 HTLO Lithene ® PM4 2200) Molar mass Mn 1978 2975 2800 2600 2000 (manufacturer data) Functionality >1.9 >1.9 2.4-2.6 2.4 2 (manufacturer data) ε-Caprolactone 0 0 0 0 100 [wt %] OH number 53.82 34.98 52.49 52.11 54-58 η [Pa .Math. s] 2.75 4.62 1.31 1.09 0.48 (at temperature) (40° C.) (40° C.) (60° C.) (40° C.) (60° C.) Tm [° C.] amorphous amorphous amorphous amorphous 40-50 Krasol ® and PolyBD polyols are manufactured by Cray Valley, an affiliate of Total, France.

(9) Preparation of polyester-modified polyol components

(10) ε-Caprolactone was dried over CaH.sub.2 and then distilled at 130° C. under reduced pressure, stored at −30° C. under argon and used within 14 days. Titanium tetrabutoxide was dissolved in dry toluene at 50% by volume, and the solution was stored under argon.

Example 2

Preparation of Polyols 6 to 10

(11) The polybutadiene used was dried at 95° C. in vacuo for 20 hours and stored under argon before use. A 250 mL glass reactor was filled with 164 g of polyol 1 (157 mmol of OH groups) and 36 g of ε-caprolactone (315 mmol) and flushed with argon. The components were stirred homogeneous, heated to 120° C. and finally admixed with 43 μL of titanium tetrabutoxide solution (15 ppm of titanium) before the reactor was sealed. Following 2 hours of stirring at 120° C., the product was discharged.

(12) Polyols 7 to 10 in Table 2a were prepared similarly to polyol 6. Initial weight differences and related product properties are summarized in Table 2a.

(13) TABLE-US-00002 TABLE 2a Preparation of ester-modified polyol components Designation Polyol 6 Polyol 7 Polyol 8 Polyol 9 Polyol 10 Polybutadienol Polyol 1 Polyol 1 Polyol 2 Polyol 2 Polyol 4 Monomer/OH 2 5 2 5 2.4 Proportion of 18 35 13 26 20 ε-caprolactone [wt %] Polybutadiene [g] 164.1 129.2 175.1 147.5 175.9 ε-Caprolactone [g] 35.9 70.8 24.9 52.5 132.0 Ti [ppm] 15 30 11 22 150 Reaction temperature 120 120 120 120 150 [° C.] Reaction time [h] 2 2 2 2 8 OH number 44.84 35.41 33.26 28.38 40.77 η [Pa .Math. s] at 40° C. 2.33 2.62 4.4 4.97 1.03 Tm [° C.] amorphous amorphous amorphous 22.7 48.3

Example 3

Preparation of Polyols 11 to 13

(14) In a 5 L steel reactor, 1367.4 g of polyol 3 (1.28 mol of OH groups) were dried at 100° C. in vacuo for 3 hours and admixed with 462.7 g of ε-caprolactone (4.06 mol) under nitrogen. The components were stirred homogeneous at 250 rpm and 150° C. before 0.40 ml of titanium tetrabutoxide solution (15 ppm of titanium) was admixed and the reactor was sealed. Following 4 hours of stirring at 150° C., the product was discharged.

(15) Polyols 12 and 13 in Table 2b were prepared similarly to polyol 11. Initial weight differences and related product properties are summarized in Table 2b.

(16) TABLE-US-00003 TABLE 2b Preparation of ester-modified polyol components Designation Polyol 11 Polyol 12 Polyol 13 Polybutadienol Polyol 3 Polyol 3 Polyol 1 Monomer/OH 1.6 3.20 4 Proportion of ε-caprolactone 15 25 30 [wt %] Polybutadiene [g] 1700 1367.4 2454.6 ε-Caprolactone [g] 287.5 462.7 1058.2 Ti [ppm] 15 15 3 Reaction temperature [° C.] 150 150 120 Reaction time [h] 4 4 4 OHv 41 38 34 Visco [Pa .Math. s] at 60° C. 1.54 1.87 10.94 Tm [° C.] amorphous 14.9 amorphous

(17) Production of Polyurethane Elastomers

(18) Polyol component and isocyanates were temperature controlled to 45° C. and/or 60° C. for processing into polyurethanes. The temperature depended on the melting temperature of the polyol component. The polyol component aside from the polybutadiene polyol comprised 1,4-butanediol as extender, mercury salt as catalyst and a defoamer (Antifoam MSA, from Dow Corning). The B component used was a mixture formed from equal parts of a commercially available 4,4′-MDI-based prepolymer having an NCO value of 23% (MP102 from BASF) and a commercially available uretoneimine-modified 4,4′-MDI (MM103 from BASF). The formulations for the polyurethane elastomers were all adjusted to an NCO index of 100. One mixing pass involved the components being mixed in a Speedmixer from Hausschild at 2000 rpm for one minute.

Example 4

Production of Elastomers 1 to 11

(19) Instancing the production of elastomer 2, 90.07 g of polyol 6 (95.2% of the polyol component) were weighed into a beaker for the polyol component together with 3.79 g of 1,4-butanediol (4.0% of the polyol component), 0.47 g of catalyst (0.5% of the polyol component) and 0.28 g of defoamer (0.3% of the polyol component) and temperature controlled for 30 minutes to 45° C. (processing temperature). This component was mixed in a Speedmixer for 2 minutes until bubble free. The isocyanate component was then admixed for one minute in the Speedmixer. The mixture was poured out into a 150×200×2 mm.sup.3 mold temperature controlled to 80° C. and smoothed down with a plastics rod. After 30 minutes the cast elastomer was demolded and conditioned at 80° C. for 4 hours. The polyurethane elastomer was stored for at least 7 days at 23° C. and 50% relative humidity before characterization.

(20) Elastomers 1 and 3 to 11 were obtained similarly to elastomer 2. Initial weight differences and related product properties of the elastomers obtained on the basis of other HTPB polyols are summarized in Tables 3a and 3b according to the processing temperature.

(21) TABLE-US-00004 TABLE 3a Production of polyurethane elastomers from unmodified polyols at processing temperature of 45° C. Designation Elastomer 1 Elastomer 2 Elastomer 3 Elastomer 4 Elastomer 5 Elastomer 6 Polybutadiene type Polyol 1 Polyol 6 Polyol 7 Polyol 2 Polyol 8 Polyol 9 ε-Caprolactone in 0 18 35 0 13 26 polyol [wt %] Polyol [%] 95.2 95.2 95.2 95.2 95.2 95.2 Butanediol [%] 4 4 4 4 4 4 Defoamer [%] 0.3 0.3 0.3 0.3 0.3 0.3 Catalyst [%] 0.5 0.5 0.5 0.5 0.5 0.5 Shore A 58 70 69 61 70 69 Elongation at break [%] 409 550 641 322 379 497 Tensile strength [MPa] 11.1 25.0 23.6 6.31 14.2 16.2 Degree of swelling [%] 0.29 0.35 0.42 0.26 0.27 0.30

(22) TABLE-US-00005 TABLE 3b Production of polyurethane elastomers from ester-modified polyols at processing temperature of 60° C. Designation Elastomer 7 Elastomer 8 Elastomer 9 Elastomer 10 Elastomer 11 Polyol Polyol 3 Polyol 11 Polyol12 Polyol 4 Polyol 10 ε-Caprolactone in polyol 0 15 25 0 20 [wt %] Polyol [%] 93.6 93.6 93.6 95.6 95.6 Butanediol [%] 6 6 6 4 4 Defoamer [%] 0.3 0.3 0.3 0.3 0.3 Catalyst [%] 0.1 0.1 0.1 0.1 0.1 Shore A 72 71 78 42 39 Elongation at break [%] 95.6 232.6 257.9 81 104 Tensile strength [MPa] 4.057 11.32 11.62 1.5 2.5 Degree of swelling [%] 0.46 0.41 0.39 0.64 0.4

Comparative Example 1

Production of Elastomer 12

(23) A polyurethane elastomer was formed from a purely polycaprolactone polyol (polyol 5 in Table 1) in accordance with Example 4 for comparison. Table 4 summarizes the elastomer's formulation and mechanical properties.

(24) TABLE-US-00006 TABLE 4 Production of polyurethane elastomer from purely polycaprolactone at processing temperature of 60° C. Designation Elastomer 12 Polyol Polyol 5 ε-Caprolactone in polyol [wt %] 100 Polyol [%] 95.6 Butanediol [%] 4 Defoamer [%] 0.3 Catalyst [%] 0.1 Shore A 58 Elongation at break [%] 470 Tensile strength [MPa] 30 Degree of swelling [%] 1.39

(25) The examples provided show that the grafting of polybutadienols with blocks of polycaprolactone leads to a distinct improvement in mechanical properties. The degrees of swelling of the polyurethane elastomers in water are further very low, the modification with caprolactone notwithstanding.

Example 5

Production of TPU 1

(26) Polyol component 13 and the isocyanate were temperature controlled to 70° C. and 45° C., respectively, for processing into a thermoplastic polyurethane (TPU). The polyol component aside from the polybutadiene polyol comprises 1,4-butanediol as extender. The isocyanate component used was 4,4-MDI. The formulation was adjusted to an NCO index of 100.

(27) Mixing was performed with an overhead stirrer from Heidolph at 220 rpm.

(28) The polyol component was provided by weighing 1420.11 g of polyol 13 (91.27% of the polyol component) into a tub together with 124.48 g of 1,4-butanediol (8.0% of the polyol component) followed by storage at 70° C. for 2 hours. This was followed by the addition of 444.06 g of pure 4,4′-MDI. The components were mixed until the reaction mixture had reached 80° C. The material was then poured into an aluminum shell temperature controlled to 80° C. After altogether 10 minutes, the TPU was conditioned at 80° C. for 15 hours.

(29) Preparation of Test Specimens

(30) The TPU obtained was cut into pieces about 15×10 cm.sup.2 in size, which were cooled with liquid nitrogen. The cooled samples were comminuted with a Condux chopper into pellets. The pellets were used on the Babyplast (model 6/10) from Christmann Kunststofftechnik GmbH to form test specimens 3 cm×7 cm in size by injection molding (plastification 211° C., crosshead chamber 215° C., die 210° C., mold 64° C.). S2 shoulder bars were subsequently cut out. The mechanical properties are summarized in Table 5.

(31) TABLE-US-00007 TABLE 5 Production of TPU from ester-modified polyol Designation TPU 1 Polyol Polyol 13 ε-Caprolactone in polyol [wt %] 30 Polyol [%] 91.27 Butanediol [%] 8 Shore A 75 Elongation at break [%] 471.7 Tensile strength [MPa] 13.3 Degree of swelling [%] 0.45

Comparative Example 2

Producing a TPU from an Unmodified Polybutadienediol

(32) An experiment similar to Example 5 with an unmodified polybutadienediol, polyol 1, lead to a material of very low strength. The material was not further processed.

(33) Characterization

(34) Conversions of double bonds in the epoxidation of polybutadienes were determined by .sup.1H NMR spectroscopy in d-chloroform. EP values of epoxidized polybutadienes were determined by a method of Jung & Kleeberg [Fres. J. Anal. Chem. 1962, 387].

(35) OH numbers of polyols were determined to DIN 53240-2 by potentiometric titration.

(36) Dynamic shear viscosities were determined with an AR-G2 rheometer from TA Instruments. The measurements were carried out at the stated temperature in the steady state mode at shear frequencies between 0.1 and 1000 Hz using a cone-plate geometry (diameter: 40 mm or 60 mm, angle: 2°).

(37) Melting temperatures were determined by DSC. The sample was heated from room temperature to 150° C. at a rate of 20° C./min. The temperature was maintained for 3 min. The temperature was finally cooled down to −120° C. at a rate of 10° C./min before heating after a delay time of 3 min to 220° C. at 10° C./min. The melting points were determined during the second heating phase. The temperature was again maintained for 3 min before finally cooling down to room temperature.

(38) Tensile tests were carried out to DIN 53504 before S2 shoulder bars with optical path tracking.

(39) Shore hardnesses were determined to DIN 53505.

(40) Water imbibition was determined on PU plaques about 3×4 cm.sup.2 in size, cut to fit slide frames. The samples were placed in 100° C. water for 5 hours. The samples were finally dabbed dry before the degree of swelling was computed from the weight difference.