Methods for producing transparent, thermoplastic polyurethane having high mechanical strength and hardness

Abstract

The present invention relates to thermoplastic polyurethanes obtainable or obtained by reaction of at least one aliphatic polyisocyanate; at least one chain extender; and at least one polyol composition, where the polyol composition comprises a polyol selected from the group consisting of polyetherols and at least one bisphenol derivative selected from the group consisting of bisphenol A derivatives with a molecular weight Mw>315 g/mol and bisphenol S derivatives with a molecular weight Mw>315 g/mol, where at least one of the OH groups of the bisphenol derivative is alkoxylated, and to processes for producing such thermoplastic polyurethanes and to the use of a thermoplastic polyurethane according to the invention for producing extrusion products, films and moldings.

Claims

1. A thermoplastic polyurethane obtained by reaction of at least the components (i) to (iii): (i) at least one aliphatic polyisocyanate; (ii) at least one chain extender; and (iii) at least one polyol composition, wherein the polyol composition comprises both a) and b): a) at least one polyol selected from the group consisting of at least one polyetherol, and b) at least one bisphenol derivative, which is a bisphenol A derivative with a molecular weight Mw>315 g/mol, where at least one OH group of the bisphenol derivative is alkoxylated, wherein the polyetherol is selected from the group consisting of a polyethylene glycol, a polypropylene glycol, a polytetrahydrofuran, and a mixture thereof, wherein the chain extender and the bisphenol derivative are used in a molar ratio of 20:1 to 1:1, and wherein the thermoplastic polyurethane has a transmission at 450 nm of greater than 85% at a path length of 2 mm.

2. The thermoplastic polyurethane according to claim 1, wherein the chain extender is a diol with a molecular weight Mw<220 g/mol.

3. The thermoplastic polyurethane according to claim 1, wherein the at least one bisphenol derivative has only primly OH groups.

4. The thermoplastic polyurethane according to claim 1, wherein the at least one bisphenol derivative has formula (I): ##STR00010## wherein: R1 is in each case independently of the others a methyl group or H, R2 and R3 are a methyl group, X is a C(R1).sub.2, C(R1).sub.2C(R1).sub.2 or C(R1).sub.2C(R1).sub.2C(R1).sub.2 group, p and q independently of one another are an integer from 1 to 4, and n and m independently of one another are an integer >0.

5. The thermoplastic polyurethane according to claim 1, wherein the polyol composition comprises at least one polyol selected from the group consisting of a polytetrahydrofuran with a molecular weight Mn in the range from 600 g/mol to 2500 g/mol.

6. The thermoplastic polyurethane according to claim 1, wherein the aliphatic polyisocyanate is an aliphatic diisocyanate.

7. The thermoplastic polyurethane according to claim 1, wherein the aliphatic polyisocyanate is selected from the group consisting of 4,4-, 2,4- and/or 2,2-methylenedicyclohexyl diisocyanate (H12MDI), hexamethylene diisocyanate (HDI) and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, and a mixture thereof.

8. A process for producing a thermoplastic polyurethane, the process comprising: reacting (i) of at least one aliphatic polyisocyanate; (ii) of at least one chain extender; and (iii) of at least one polyol composition, wherein the polyol composition comprises both a) and b): a) at least one polyol selected from the group consisting of at least one polyetherol and b) at least one bisphenol derivative, which is a bisphenol A derivative with a molecular weight Mw>315 g/mol, where at least one OH group of the bisphenol derivative is alkoxylated, wherein the polyetherol is selected from the group consisting of a polyethylene glycol, a polypropylene glycol, a polytetrahydrofuran, and a mixture thereof, wherein the chain extender and the bisphenol derivative are used in a molar ratio of 20:1 to 1:1, and wherein the thermoplastic polyurethane has a transmission at 450 nm of greater than 85% at a path length of 2 mm.

9. The process according to claim 8, wherein the at least one bisphenol derivative has formula (I): ##STR00011## wherein: R1 is in each case independently of the others a methyl group or H, R2 and R3 are a methyl group, X is a C(R1).sub.2, C(R1).sub.2C(R1).sub.2 or C(R1).sub.2C(R1).sub.2C(R1).sub.2 group, p and q independently of one another are an integer from 1 to 4, and n and m independently of one another are an integer >0.

10. A process of making an extrusion product, a film, or a molding, the process comprising: forming a thermoplastic polyurethane according to claim 1 into an extrusion product, a film, or a molding.

11. The process according to claim 10, wherein said molding is a lens, a screen, a display cover or cover for a headlight or a lamp.

12. The process according to claim 10, where said extrusion product is a transparent body for light guiding, for illumination or for the detection of light.

13. A process of making an extrusion product, a film, or a molding, the process comprising: forming a thermoplastic polyurethane obtained by a process according to claim 8 into an extrusion product, a film, or a molding.

14. The process according to claim 13, wherein said molding is a lens, a screen, a display cover or cover for a headlight or a lamp.

15. The process according to claim 13, where said extrusion product is a transparent body for light guiding, for illumination or for the detection of light.

Description

EXAMPLES

(1) The following feed materials were used: Polyol 1: polyetherpolyol with an OH number of 114.2 and exclusively primary OH groups Polyol 2: bisphenol A-started polyetherpolyol with an OH number of 313 and exclusively primary OH groups Polyol 3: bisphenol A-started polyetherpolyol with an OH number of 239 and exclusively primary OH groups Polyol 4: adipic acid-DEG-TMP-started polyesterpolyol with MW 2390 g/mol and an OH number of 61 g/mol Polyol 5: phthalic anhydride-DEG-started polyesterpolyol, with MW 356 and an OH number of 315 g/mol Polyol 6: aromatic polyesterpolyol with MW 468 g/mol and an OH number of 240 g/mol Isocyanate: aliphatic isocyanate (composition 100% 4,4-methylenedicyclohexyl diisocyanate) CE: 1,4-butanediol Catalyst 1: bismuth neodecanoate Catalyst 2: tinII isooctoate

Examples

(2) The polyols were initially introduced in a container at 80 C. and mixed with the components according to Table 1 with vigorous stirring. The reaction mixture heated up to above 110 C. and was then poured onto a heated, Teflon-coated table. The resulting cast slab was heat-treated at 80 C. for 15 hours, then granulated and processed in injection molding.

(3) The polyols 1, 2, 3, 4, 5 and 6 were reacted with chain extender CE and the isocyanate according to Table 1 below:

(4) TABLE-US-00001 TABLE 1 Example 1 Example 4 Example 7 (parts by Example 2 Example 3 (parts by Example 5 Example 6 (parts by weight) (parts by (parts by weight) (parts by (parts by weight) comparison weight) weight) comparison weight) weight) comparison Polyol 1 39.61 32.51 22.54 31.60 21.00 Polyol 2 5.12 12.42 28.93 Polyol 3 6.53 15.18 32.32 Isocyanate 47.63 49.61 52.28 58.31 49.11 51.06 54.93 CE 12.76 12.76 12.76 12.76 12.76 12.76 12.76 Catalyst 70 ppm 70 ppm 70 ppm 70 ppm 70 ppm 70 ppm 70 ppm Example 11 Example 12 Example 8 Example 9 Example 10 (parts by (parts by (parts by (parts by (parts by weight) weight) weight) weight) weight) comparison comparison Polyol 1 20.23 18.59 17.19 Polyol 3 30.35 27.89 26.48 47.36 40.2 Isocyanate 42.48 45.08 47.29 45.94 50.25 CE 6.93 8.44 9.73 6.69 9.55 Catalyst 2 300 ppm 300 ppm 300 ppm 300 ppm 300 ppm Example 13 Example 14 Example 15 Example 17 (parts by (parts by (parts by Example 16 (parts by weight) weight) weight) (parts by weight) comparison comparison comparison weight) comparison Polyol 1 17.22 16.05 17.22 17.29 Polyol 2 Polyol 3 25.93 40.38 Polyol 4 25.82 Polyol 5 24.07 Polyol 6 25.82 Isocyanate 47.27 50.19 42.27 47.07 50.67 CE 9.69 9.69 9.69 9.72 8.95 Catalyst 2 200 ppm 200 ppm 200 ppm 200 ppm 200 ppm

(5) The following properties of the resulting polyurethanes were determined by the specified processes: Hardness: DIN ISO 7619-1 Tensile strength and elongation at break: DIN 53504 Tear resistance: DIN ISO 34-1, B (b) Yellowing index (reflection without gloss): ASTM E313 Vicat temperature: DIN EN ISO 306 Abrasion measurement: DIN ISO 4649

(6) The results summarized in Table 2 were obtained:

(7) TABLE-US-00002 TABLE 2 Property Dimension Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Hardness [Shore D] 57 67 80 86 65 75 82 Tensile [MPa] 40 28 52 28 45 40 66 strength Elongation [%] 400 380 140 3 370 300 10 at break Tear [kN/m] 119 138 211 87 145 217 105 resistance Yellowing 0.9 1.0 1.1 2.7 1.2 1.2 1.3 index Vicat 10 N/ 44 46.9 60.1 96.8 45.2 53.8 78.2 tem- 120 C./h perature [ C.] Abrasion [mm.sup.3] 90 243 106 146 176 108 106 Property Dimension Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Hardness [Shore D] 72 74 77 83 82 Tensile strength [MPa] 31 35 45 65 70 Elongation at [%] 290 250 190 30 30 break Tear resistance [kN/m] 142 201 233 43 157 Yellowing index 2.0 1.8 1.4 1.6 1.0 Abrasion [mm.sup.3] n.d. n.d. n.d. n.d. n.d. Property Dimension Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Hardness [Shore D] 74 78 61 75 82 Tensile [MPa] 29 33 10 42 62 strength Elongation at [%] 100 20 230 250 70 break Tear [kN/m] 27 24 73 208 133 resistance Yellowing 3.2 2.8 3.1 2.2 1.4 index Abrasion [mm.sup.3] n.d. n.d. n.d. 107 104 n.d.not determinable

(8) Determination of the Transmission/Opacity

(9) The transmission or opacity was measured once using a light trap as background and once using a white tile as background in reflection with the exclusion of gloss using a colorimeter. The lightness values (L value in accordance with DIN 6174) are compared and given as opacity in %.

(10) An UltraScan colorimeter from HunterLab was used. The samples are produced in accordance with AA E-10-132-002. The colorimeter is standardized upon reaching the operating temperature, generally 30 minutes, and run under the following parameters: Mode: RSEX (Reflection Specular Excluded), reflection without gloss, with opening of the gloss trap Area view: large Port size: 25.4 UV filter: out

(11) The total opacity is calculated according to the following formula:
Opacity=(L valueblack/L valuewhite)100%

(12) According to this, an opacity value of 0% means complete transparency (100%) of the sample and a value of 100% opacity means complete nontransparency (transparency=0%).