COMPOSITE COMPONENTS ON THE BASIS OF HYDROPHOBIC POLYOLS

Abstract

The present invention relates to the use of hydrophopic polyols for producing fiber composite components on the basis of a polyurethane/polyisocyanurate reaction mixture, to a method for producing composite components and to the composite components as such. The method according to the invention is particularly economical in terms of saving material and time costs and the composite components obtained are characterized by excellent visual and material properties.

Claims

1. A fiber composite component comprising: a fiber layer comprising polyurethane/polyisocyanurate, wherein the polyurethane/polyisocyanurate comprises a reaction product of a reaction mixture comprising: A) an isocyanate component; B) a polyol component; wherein the polyol component B) comprises at least one hydrophobic polyol.

2. The fiber composite component as claimed in claim 1, wherein the at least one hydrophobic polyol is a polyether ester polyol.

3. The fiber composite component as claimed in claim 2, wherein the polyether ester polyol comprises a base-catalyzed reaction product of reactants comprising: starter compounds having Zerewitinoff-active hydrogen atoms; and alkylene oxides in the presence of fatty acid esters.

4. The fiber composite component as claimed in claim 3, wherein the polyether ester polyol comprises fatty acid ester residues having no free OH groups.

5. The fiber composite component as claimed in claim 2, wherein the polyether ester polyol has a content of fatty acid residues of 5% to 85% by weight, based on the total weight of the polyether ester polyol.

6. A method for producing composite components, comprising: a) providing a laminar structure comprising a core, and a fiber fabric; b) contacting the laminar structure with a reaction mixture comprising: A) an isocyanate component, B) a polyol component; and c) curing the reaction mixture; wherein the polyol component comprises at least one hydrophobic polyol.

7. The method for producing composite components as claimed in claim 6, wherein the hydrophobic polyol is a polyether ester polyol.

8. The method for producing composite components as claimed in claim 6, wherein the reaction mixture is at a constant temperature of 25 C., 60 minutes after mixing, and has a viscosity of 50 to 500 mPas.

9. The method for producing composite components as claimed in claim 6, wherein the NCO index is from 1.10 to 10.00.

10. The method for producing composite components as claimed in claim 6, wherein the core, at least in sections, directly adjoins the fiber fabric layer including polyurethane/polyisocyanurate, wherein the core comprises a core material selected from the group consisting of wood, polyvinyl chloride (PVC) foam, polyester (PET) foam, and polyurethane (PUR) foam, and wherein the core has a water content of 0.5% by weight to 30% by weight.

11. The method for producing composite components as claimed in claim 6, wherein step b) is conducted by a vacuum infusion method.

12. A reaction mixture for production of core composite components by vacuum infusion, based on a polyurethane/polyisocyanurate reaction mixture comprising: A) an isocyanate component; and B) a polyol component; wherein the reaction mixture comprises a hydrophobic polyol, in a proportion of 10% to 40% by weight, based on the total weight of the reaction mixture.

13. A process for the production of polyurethane/polyisocyanurate composite materials comprising infusing a core composite component with the reaction mixture of claim 12.

14. A rotor blade for wind turbines comprising a laminar structure having the following layers: a core layer; and a fiber layer comprising the fiber composite component as claimed in claim 1.

15. The fiber composite component as claimed in claim 1, further comprising a core layer.

16. The fiber composite component as claimed in claim 1, wherein the at least one hydrophobic polyol of polyol component B) comprises an oleochemical polyol.

17. The fiber composite component as claimed in claim 1, wherein the reaction mixture further comprises: C) additives.

18. The method for producing composite components as claimed in claim 6, wherein the laminar structure comprises a flow aid.

19. The method for producing composite components as claimed in claim 6, wherein the at least one hydrophobic polyol comprises an oleochemical polyol.

20. The reaction mixture of claim 12, wherein the hydrophobic polyol of the reaction mixture comprises an oleochemical polyether ester polyol.

Description

[0089] The present invention is further elucidated by the figures and examples which follow, but without being limited thereto. The figures show:

[0090] FIG. 1 Drying curves of balsa wood under reduced pressure

[0091] FIG. 2 Increases in weight of dried balsa wood as a result of air humidity

[0092] FIG. 3 The evolution of temperature within an infusion structure over time

[0093] FIG. 1 shows the decrease in weight of balsa wood samples resulting from drying under reduced pressure. The temperature at which the drying was conducted was 23 C. Curve 1 describes the profile at a reduced pressure of 50 mbar, curve 2 the profile at a reduced pressure of 20 mbar. These experiments make clear how much water balsa wood can contain.

[0094] FIG. 2 shows the absorption of moisture from the air by previously dried balsa wood samples. Curve 3 relates to a sample previously dried at 20 mbar, curve 4 to a sample previously dried at 50 mbar. These curves show that it is insufficient to dry balsa wood cores just once in order to keep them permanently free of water. They will absorb moisture again from the ambient air.

[0095] FIG. 3 shows the evolution of temperature within an infusion structure over time. After the infusion, the infusion structure was positioned in a heating cabinet that was not heated at first. The heating cabinet was then heated at a heating rate of 1 C./min. Curve 5 shows the oven temperature, and curve 6 the temperature of the infusion structure. It can be seen that the exothermicity that arises allows the temperature of the structure to rise to slightly above 80 C.

[0096] The invention is to be illustrated in detail by the examples which follow.

EXAMPLES

[0097] Starting Compounds:

[0098] Polyether Ester Polyol 1: Preparation Method

[0099] 197.0 g of glycerol and 7.793 g of a 46.44% by weight aqueous KOH solution were dewatered in a 2 L laboratory autoclave at 110 C., a stirrer speed of 200 rpm (cross-beam stirrer) and applied vacuum with simultaneous introduction of 50 mL of nitrogen per minute over a period of 3.0 h. In the course of this, towards the end of the dewatering period, a pressure of 100-120 mbar was established. Thereafter, the mixture was cooled down to 50 C., and 620.7 g of soybean oil were added. After the filling stub had been sealed, oxygen was removed by charging the apparatus with 3.0 bar of nitrogen and then releasing the elevated pressure to atmospheric pressure three times each. After heating up again to 110 C., 383 g of propylene oxide were metered into the autoclave at a stirrer speed of 800 rpm over a period of 3.0 h. The metered addition was started at a pressure of 0.05 bar, toward the end of the metering phase, the reactor pressure reached 2.35 bar. After a further reaction time of 9 h, the product was heated at 105 C. under reduced pressure for 0.5 h; after cooling down to 40 C., 146.054 g of a 2.161% by weight aqueous sulfuric acid solution were added and the mixture was stirred for 0.5 h. The product was then dewatered in a water-jet vacuum at 40 C. and filtered through a depth filter (T 750, from Seitz). The filtrate was then heated at 110 C. and 1 mbar for another 3 h. Finally, 0.5808 g of Irganox 1076 was added at 80 C. The OH number of the product was 291 mg KOH/g and the viscosity at 25 C. was 181 mPas.

[0100] Polyether polyol A: glycerol-started polypropylene oxide polyol having a functionality of 3 and an OH number of 400 mg KOH/g and a viscosity of 375 mPas (at 25 C.).

[0101] Polycat SA 1/10: product from Air Products. Phenol salt of 1,8-diazabicyclo[5.4.0]undec-7-ene in dipropylene glycol. The OH number was 83 mg KOH/g.

[0102] Isocyanate: MDI blend, mixture of diphenylmethane 4,4-diisocyanate (MDI) with isomers and higher-functionality homologs, containing 0.1% by weight of acetylacetone and an NCO content of 32.8% by weight; viscosity at 25 C.: 20 mPas. The mixture contains about 66% by weight of diphenylmethane 4,4-diisocyanate, 21% by weight of diphenylmethane 2,4-diisocyanate, 2% by weight of diphenylmethane 2,2-diisocyanate and 11% by weight of higher-functionality homologs of MDI.

[0103] Production of the Shaped Bodies

[0104] In order to determine the matrix properties, shaped bodies (sheets) were produced from various PUR/PIR systems and compared. The polyol mixtures comprising the trimerization catalyst were degassed at a pressure of 1 mbar for 60 minutes and then the isocyanate was added. This blend was degassed at a pressure of 1 mbar for about 5 minutes and then poured into sheet molds. The sheets were cast at room temperature and subjected to heat treatment in a drying cabinet heated to 80 C. overnight. The thickness of the sheets was 4 mm. Optically transparent sheets were obtained. The amounts and properties can be found in table 1.

[0105] The sheets were used to produce specimens for a tensile test according to DIN EN ISO 527, and the modulus of elasticity and strength was determined.

[0106] The heat distortion resistance (heat deflection temperatureHDT) was determined in accordance with DIN EN ISO 75 1/75 2004Method A with a flexural stress of 1.8 N/mm.sup.2 and a heating rate of 120 K/h.

[0107] OH number and viscosity: The OH number was determined according to the method of DIN 53240. The viscosity was determined by means of a rotary viscometer (Physica MCR 51, manufacturer: Anton Paar) by the method of DIN 53019 (spindle type CC27, shear rate range 16-128 l/s).

[0108] The viscosity of the reaction mixture was determined directly after the mixing and 60 minutes after the mixing of the components at a constant temperature of 25 C. with a rotary viscometer at a shear rate of 60/s.

[0109] All amounts in the following table are in parts by weight.

TABLE-US-00001 TABLE 1 Example Example Example Comparative Comparative Comparative 1 2 3 example 4 example 5 example 6 Polyether 26 13 19.5 ester polyol 1 Polyether 13 6.5 26 26 26 polyol A Polycat SA 0.5 0.5 0.5 0.5 0.5 0.5 1/10 Isocyanate 73.5 73.5 73.5 83.4 100.8 73.5 NCO index 5.81 3.57 3.87 3.50 4.23 3.08 Properties HDT [ C.] 111.1 96.1 87.8 76.5 73.1 73.1 Viscosity 80 55 52 47 44 58 directly after mixing at 25 C. [mPas] Viscosity 60 391 253 237 274 255 441 min after mixing at 25 C. [mPas] Tensile test: 2609 2820 2686 3140 2949 3117 Modulus of elasticity [MPa] Tensile test: 75 78.4 74.4 40.7 47.5 76 Strength [MPa] Tensile test: 5.8 5.0 5.7 1.4 1.8 4.6 Elongation at break [%]

[0110] The inventive examples in table 1 show a slow rise in viscosity, which is advantageous for the production of large components, since it is considered to be an indicator of a long processing window. Compact and optically transparent components were obtained with good mechanical properties such as a modulus of elasticity exceeding 2600 MPa, a strength exceeding 74 MPa and the elongation at break exceeding 5%. Surprisingly, the shaped bodies produced according to examples 1 to 3, in spite of a lower OH number of the polyols/polyol mixtures used, have much higher heat distortion resistances (HDT values) than the specimens produced according to comparative examples 4 to 6.

[0111] The compositions according to example 1 and comparative example 4 were used to produce glass fiber-reinforced PUR/PIR materials by the vacuum infusion methods.

[0112] For this purpose, two laminas of a UD glass scrim (basis weight of glass 1040 g/m.sup.2 per lamina), then a piece of balsa wood (dried under reduced pressure at 105 C. overnight), two more laminas of a UD glass scrim (basis weight of glass 1040 g/m.sup.2 per lamina) and a green mesh as flow aid were applied to a mold, sealed with a vacuum film and evacuated. Then the composition from example 1 which had been degassed for about 5 minutes beforehand was sucked in. Once the mold had been filled, the component was heat-treated at 80 C. overnight.

[0113] A compact and optically transparent component was obtained.

[0114] Table 2 shows that bubble formation, which can arise as a result of the reaction of moisture with the isocyanate, in an experiment with the composition from example 1 is lower than in an experiment with the composition from comparative example 6 under the same processing conditions.

TABLE-US-00002 TABLE 2 Comparative Example 7 example 8 Polyether ester 1 26 Polyether polyol A 26 Polycat SA 1/10 0.5 0.5 MDI blend 73.5 73.5 Visual impression little bubble formation bubble formation

[0115] The simple addition of different proportions of soybean oil to the polyol component leads to phase separation in the polyol formulation (see table 3). Such hydrophobized polyols are therefore unsuitable for use as a reaction mixture for VARTM.

TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Comparative example 9 example 10 example 11 example 12 Polyether 30 20 40 55 polyol A Soybean oil 30 40 20 5 Phase stability no no no no