Composite element having improved properties

Abstract

The disclosure provides a composite element having a layer structure with 2 mm to 20 mm of metal, 10 mm to 100 mm of compact polyurethane formulation and another 2 mm to 20 mm of metal, a method of using thereof and corresponding production process therefor. The polyurethane formulation is obtainable by reacting (a) a compound having at least two isocyanate groups with (b) polyether polyol and the polyether polyol (b) is a mixture including at least the constituents of polyether polyol (b1) and polyether polyol (b2).

Claims

1. A composite element having the following layer structure: (i) 2 mm to 20 mm of metal, (ii) 10 mm to 100 mm of compact polyurethane formulation, said polyurethane formulation being obtainable by reacting (a) a compound having at least two isocyanate groups with (b) polyether polyol, optionally in the presence of (c) catalyst and/or (d) auxiliaries and/or additives, (e) chain extenders (iii) 2 mm to 20 mm of metal, wherein the compound (a) having at least two isocyanate groups has an NCO content of 20% to 50% and the polyether polyol (b) is a mixture comprising polyether polyol (b1) and polyether polyol (b2), wherein the polyether polyol (b1) has a number-average molecular weight between 3.0×10.sup.3 g/mol and 7.0×10.sup.3 g/mol and an average functionality of 2.2 to 2.7, the polyether polyol (b2) has a number-average molecular weight between 0.15×10.sup.3 g/mol and 2.0×10.sup.3 g/mol and an average functionality of 2.5 to 3.5, and wherein the polyether polyol (b1) is present in the mixture at 50% by weight to 95% by weight and the polyether polyol (b2) is present in the mixture at 5% by weight to 50% by weight.

2. The composite element according to claim 1, wherein the polyether polyol (b1) has an average functionality of 2.4 to 2.6.

3. The composite element according to claim 1, wherein the polyether polyol (b2) has an average functionality of 2.9 to 3.1.

4. The composite element according to claim 1, wherein weight percentages for the polyether polyols (b1) and (b2) are based on a total weight of the mixture consisting of the polyether polyol (b1) and (b2).

5. The composite element according to claim 1, wherein a difference in the number-average molecular weight of the polyether polyols (b1) and (b2) is at least 0.5×10.sup.3 g/mol.

6. The composite element according to claim 5, wherein the difference in the number-average molecular weight of the polyether polyols (b1) and (b2) is at least 1.0 ×10.sup.3 g/mol.

7. The composite element according to claim 5, wherein the difference in the number-average molecular weight of the polyether polyols (b1) and (b2) is at least 2.0 ×10.sup.3 g/mol.

8. The composite element according to claim 1, wherein a chain extender is present.

9. The composite element according to claim 8, wherein the chain extender comprises a mixture of diols having 2 to 8 carbon atoms.

10. The composite element according to claim 1, wherein the compound a) having at least two isocyanate groups comprises the isocyanate diphenylmethane 2,4′-, 2,2′- and/or 4,4′-diisocyanate (MDI) and/or polyphenylpolymethylene polyisocyanate.

11. The composite element according to claim 1, wherein the polyurethane formulation has a hardness of more than 45 Shore D measured to DIN 53505.

12. A process for producing composite elements according to claim 1, which comprises mixing (a) the compound comprising at least two isocyanate groups with (b) polyether polyol, where the polyether polyol (b) is a mixture comprising at least the constituents of polyether polyol (b1) and polyether polyol (b2), optionally in the presence of (c) catalyst and/or (d) auxiliaries and/or additives and/or (e) chain extenders and allowing a mixture of (a)-(e) to cure in contact with the metal layers.

13. The process according to claim 12, wherein the compound a) having at least two isocyanate groups has an NCO content of 20% to 40%.

14. The process according to claim 12, wherein the mixture optionally comprising (c) catalyst, (d) auxiliaries and/or additives and/or chain extenders (e) has a viscosity of less than 6.0×10.sup.3 mPas, measured to DIN 53019-1 at 23° C.

15. The process according to claim 14, wherein the compound (a) having at least two isocyanate groups is an addition product of diisocyanate and a polyol having a molecular weight of 0.076 to 2×10.sup.3 g/mol.

16. A method of using composite elements, the method comprising: incorporating the composite elements according to claim 1 into vehicles, ships, aircraft or built structures.

17. A vehicle, ship, aircraft or built structure comprising composite elements according to claim 1.

18. The composite element according to claim 1, wherein the compound (a) having at least two isocyanate groups comprises the isocyanate diphenylmethane 2,4′-, 2,2′- and/or 4,4′-diisocyanate (MDI) and/or polyphenylpolymethylene polyisocyanate, the polyether polyol (b1) has a number-average molecular weight between 4.0×10.sup.3 g/mol and 6.0×10.sup.3 g/mol and an average functionality of 2.2 to 2.7, and the polyether polyol (b2) has a number-average molecular weight between 0.15×10.sup.3 g/mol and 1.0×10.sup.3 g/mol and an average functionality of 2.5 to 3.5.

19. The composite element according to claim 18, wherein the polyether polyol (b1) has an average functionality of 2.4 to 2.6, and the polyether polyol (b2) has an average functionality of 2.9 to 3.1.

Description

EXAMPLES

Feedstocks

(1) Poly 1: polyetherol prepared by alkoxylation of propylene glycol with propylene oxide and ethylene oxide having a functionality of 1.76 and a molecular weight of 3350 g/mol and an OH number of 29.5 mg KOH/g

(2) Poly 2: polyetherol prepared by alkoxylation of sucrose, glycerol with propylene oxide and ethylene oxide having a functionality of 4.15 and a molecular weight of 5250 g/mol and an OH number of 44 mg KOH/g

(3) Poly 3: polyetherol prepared by alkoxylation of ethylenediamine with propylene oxide having a functionality of 4 and a molecular weight of 300 g/mol and an OH number of 750 mg KOH/g

(4) Poly 4: polyetherol prepared by alkoxylation of glycerol with propylene oxide and ethylene oxide having a functionality of 2.49 and a molecular weight of 5170 g/mol and an OH number of 27 mg KOH/g

(5) Poly 5: polyetherol prepared by alkoxylation of toluenediamine with propylene oxide having a functionality of 3.9 and a molecular weight of 550 g/mol and an OH number of 398 mg KOH/g

(6) Poly 6: polyetherol prepared by alkoxylation of trimethylolpropane with propylene oxide having a functionality of 3.0 and a molecular weight of 200 g/mol and an OH number of 860 mg KOH/g

(7) KV 1: dipropylene glycol

(8) KV 2: butane-1,4-diol

(9) Zeo: zeolite paste, 50% in castor oil

(10) DF: AF 9000 defoamer/antifoam

(11) ISO1: Lupranat MP 102 from BASF Polyurethanes GmbH (prepolymer based on 4,4′MDI prepolymer with polyether polyol having an NCO content of 23% and a viscosity of 650 mPas at 25° C.)

(12) ISO2: Lupranat M20S from BASF Polyurethanes GmbH (polymer MDI having an NCO content of 31.5% and a viscosity of 210 mPas at 25° C.)

(13) ISO3: Lupranat MP 105 from BASF Polyurethanes GmbH (prepolymer based on 4,4′-MDI, PMDI and polyether polyol having an NCO content of 28.5% and a viscosity of 120 mPas at 25° C.) ISO4: ISO 136/26 from BASF Polyurethanes GmbH (prepolymer based on 4,4′MDI and polyether polyol having an NCO content of 18% and a viscosity of 1200 mPas at 25° C.)

(14) ISO5: ISO 137/28 from BASF Polyurethanes GmbH (prepolymer based on 4,4′MDI and polyether polyol having an NCO content of 18% and a viscosity of 750 mPas at 25° C.)

(15) ISO6: ISO 136/94 (prepolymer based on 4,4″MDI and polyetherol) from BASF Polyurethanes GmbH having an NCO content of 5.8% and a viscosity of 5500 mPas at 50° C.

(16) ISO7: mixture of 48.5% ISO4 and 51.5% ISO5

(17) For preparation of the polyol mixture, the constituents of the polyol component (polyols, additives etc.) were first mixed. Subsequently, the polyol component was reacted with the isocyanate specified in the mixing ratio specified in the table. The mixing ratio was chosen such that the equivalents ratio of NCO groups in the isocyanates to the sum total of the reactive hydrogen atoms in the compounds reactive toward isocyanates is 1.09:1. In order to determine the hardness or storage modulus, test specimens having a thickness of 1 cm or test sheets having a thickness of 2 mm were produced. The production was effected as follows:

(18) The temperature of the polyol mixture and of the isocyanate component was room temperature (25° C.). The only exception was isocyanate component ISO 136/94. This was processed at a temperature of 50° C. In order to produce the test specimens, an appropriate amount of polyol component was initially charged and the appropriate amount of isocyanate component was added. The reactive mixture was then mixed at 800 rpm for 5 sec. and then at 1800 rpm for 55 sec. by means of a Speedmixer™ from Hauschild. The homogeneously mixed reaction mixture was then introduced into molds preheated correspondingly to 100° C. After 1 h at 100° C., the test specimens were demolded.

(19) The hardness of the material was determined on the 1 cm-thick sheets. For this purpose, the sheets were first conditioned at room temperature for 7 days. The hardness was measured analogously to DIN 53505. In order to determine the hardness at 50° C. and 100° C., the materials were stored at the appropriate temperature in a corresponding oven for 3 h. The hardness was then measured directly in the oven at the appropriate temperature in order to avoid cooling of the material.

(20) The examples which follow in table 1 are intended to illustrate the effect of the composition of the invention.

(21) TABLE-US-00001 TABLE 1 V1 V2 V3 V4 B1 Poly 1 90 98 Poly 2 10 Poly 3 2 52.35 Poly 4 45.00 57.50 57.50 Poly 5 40.00 40.00 Zeo 2.50 2.35 2.35 DF 0.15 0.15 0.15 Iso 2 X X X Iso 6 X X Mixing ratio 8.8 12.1 578 255 46.9 100 polyol:X iso Viscosity of polyol 920 944 5500 3400 3400 mixture [mPas] Hardness at RT 13 A 27 A 72 A 62 A 68 D Hardness at 50° C. 72 A 61 A 64 D Hardness at 100° C. 72 A 65 A 55 D Storage modulus [G'] n.d. n.d. n.d. n.d. 570 from DMA at −40° C. Modulus of elasticity n.d. n.d. n.d. n.d. 1600 calculated from DMA at −40° C. Storage modulus [G'] n.d. n.d. n.d. n.d. 237 from DMA at +50° C. Modulus of elasticity n.d. n.d. n.d. n.d. 660 calculated from DMA at +50° C. n.d. = not determined since the shore hardness of the material at room temperature (RT) is too low

(22) As apparent from comparative examples V1 to V4,

(23) As apparent from Example B1, a polyurethane having the desired properties and a modulus of elasticity of >275 MPa in the range from −45° to +50° C. is obtained. The polyurethanes obtained in V1 to V4 have low hardness and hence a low modulus of elasticity well below 275 MPa at 50° C. The specific combination of an isocyanate (a) having an NCO content of >20% by weight with an appropriate polyol mixture (b) gives an appropriate polyurethane. This is illustrated in examples B2 to B4 in relation to comparative examples V5 and V6.

(24) TABLE-US-00002 B2 B3 B4 V5 V6 Poly 4 63.41 63.41 63.41 63.41 63.41 Poly 6 15.31 15.31 15.31 15.31 15.31 KV 1 12.90 12.90 12.90 12.90 12.90 KV 2 5.45 5.45 5.45 5.45 5.45 Zeo 2.89 2.89 2.89 2.89 2.89 DF 0.04 0.04 0.04 0.04 0.04 Iso 1 X Iso 2 X Iso 3 X Iso 6 X Iso 7 X Mixing ratio 85.6 94.1 116 150 462 100 polyol:X iso Viscosity of polyol 1500 1500 1500 1500 1500 mixture [mPas] Hardness at RT 69 D 69 D 73 D 45 D 60 A Hardness at 50° C. 66 D 65 D 68 D 27 D 57 A Hardness at 100° C. 55 D 48 D 52 D 15 D 55 A Storage modulus [G'] 726 904 1219 990 85 from DMA at −40° C. [MPa] Modulus of elasticity 2030 2530 3400 2770 238 calculated from DMA at −40° C. [MPa] Storage modulus [G'] 302 213 237 7.2 2.5 from DMA at +50° C. [MPa] Modulus of elasticity 840 600 660 20 7 calculated from DMA at +50° C. [MPa]