Multiphase Polyurethane Composition Having Reduced Foam Development

Abstract

The present invention relates to a two-component polyurethane composition composed of at least one polyol, at least one polyisocyanate, and at least one emulsifier which is not homogeneously miscible with the at least one polyol. The present invention further relates to the use of this polyurethane composition as a binder for producing fiber composites, a method for producing these fiber composites, the fiber composites themselves, and use thereof.

Claims

1. A two-component polyurethane composition for producing fiber composites, comprising at least one polyol having a number average molecular weight of up to 3000 g/mol, at least one polyisocyanate, and at least one emulsifier, wherein the composition contains the at least one polyol and the at least one polyisocyanate in an NCO:OH ratio of 2:1 to 1:2, and the transmittance of a mixture of the at least one emulsifier and the at least one polyol at 860 nm is less than 90%.

2. The two-component polyurethane composition for producing fiber composites according to claim 1, comprising 10 to 80% by weight of the at least one polyol having a number average molecular weight of up to 3000 g/mol, 5 to 70% by weight of the at least one polyisocyanate, and 0.2 to 10% by weight of the at least one emulsifier, wherein the mass fractions relate to the total weight of the two-component polyurethane composition.

3. The two-component polyurethane composition according to claim 1, wherein the emulsifier has an HLB value according to Griffin of less than 5.

4. The two-component polyurethane composition according to claim 1, wherein the at least one polyol has a number average molecular weight of 150 to 400 g/mol.

5. The two-component polyurethane composition according to claim 1, wherein the at least one polyol has a hydroxyl number of preferably 500 to 1200 mg KOH/g.

6. The two-component polyurethane composition according to claim 1, wherein the at least one polyol has an average OH functionality of 3 to 5.

7. The two-component polyurethane composition according to claim 1, wherein the at least one polyol is a polyether polyol or a mixture of polyether polyols.

8. The two-component polyurethane composition according to claim 1, wherein the at least one polyol has a viscosity of 2700 to 4000 mPas, determined with a Brookfield RVT viscometer, using a No. 4 spindle, at 25 C. and 20 rpm.

9. The two-component polyurethane composition according to claim 1, wherein the at least one polyisocyanate has an NCO content of 30 to 50% by weight, based on the weight of the at least one polyisocyanate.

10. The two-component polyurethane composition according to claim 1, wherein less than 3 mol-% of the NCO groups are reacted to form carbodiimide and/or uretonimine groups.

11. The two-component polyurethane composition according to claim 1, wherein the at least one polyisocyanate has a viscosity of 30 to 60 mPas, measured with a Brookfield RVT viscometer, using a No. 3 spindle, at 25 C. and 50 rpm.

12. (canceled)

13. A composite comprising fibers in a matrix of a crosslinked two-component polyurethane composition according to claim 1.

14. (canceled)

15. The composite according to claim 13, wherein the crosslinked two-component polyurethane composition has a glass transition temperature T.sub.G of above 60 C.

16. The fiber composite according to claim 13, wherein the crosslinked two-component polyurethane composition has a modulus of elasticity of greater than 1000 MPa at temperatures between 10 C. and +70 C.

17. The fiber composite according to claim 13, wherein the crosslinked two-component polyurethane composition has a K1C value greater than 0.5 Mpa m.sup.1/2.

18. The fiber composite according to claim 13, wherein the fibers are contained in a volume fraction of greater than 40% by volume, based on the overall composite.

19. An automotive component comprising composite according to claim 13.

20. A method for producing the composites according to claim 13, comprising filling a mold with fiber materials, mixing the two-component polyurethane composition according to claim 1, introducing the mixed two-component polyurethane composition into this mold, under pressure and/or with application of a vacuum, and curing the mixed two-component polyurethane composition in the mold at a temperature of up to 140 C.

21. The two-component polyurethane composition for producing fiber composites according to claim 1, wherein the at least one polyisocyanate is in the first component and the at least one emulsifier and the at least one polyol are in the second component.

22. The two-component polyurethane composition for producing fiber composites according to claim 1, wherein the at least one emulsifier is not homogeneously miscible with the at least one polyol.

Description

EXAMPLES

Raw Materials

[0086] 1. Polyol: polyether triol, hydroxyl number=550 mg KOH/g, viscosity at 25 C.=1800 mPas (Brookfield 25 C., spindle 4, 20 rpm), OH equivalent weight=102 g, number average molecular weight=300 g/mol [0087] 2. Polyisocyanate: isomeric mixture of MDI and higher-functional homologs, NCO content 32% by weight, viscosity at 25 C.=43 (Brookfield 25 C., spindle 3, 50 rpm) [0088] 3. Catalyst: solution of a bicyclic tertiary amine (DABCO) in polyol (30% by weight DABCO, based on the solution) [0089] 4. Emulsifier/release agent: [0090] Emulsifier 1: tetrafunctional polyol esterified with a mixture of a difunctional carboxylic acid (C6) and an unsaturated fatty acid (average C chain length 18) [0091] Emulsifier 2: dipentaerythrite completely esterified with oleic acid [0092] Emulsifier 3: diester of a dimer fatty acid with branched alcohols (average alcohol chain length C8) [0093] Dimer fatty acid [0094] Polyoxyethylene tridecyl ether phosphate

Component A

[0095] Polyol, emulsifier/release agent, and catalyst were combined at 25 C. and agitated with a SpeedMixer (model DAC 600.1 VAC-P, 250-mL SpeedMixer container) at 2100 rpm for 2 min. The mixture was subsequently degassed under vacuum with agitation at 800 rpm for 5 min, while reducing the pressure to approximately 50 mbar by means of a diaphragm pump.

Component B

[0096] The polyisocyanate was used as component B.

2K PU Composition

[0097] Component A and component B were mixed and agitated under vacuum, initially at 800 rpm for 1 min, then at 1250 rpm for 30 s, and finally at 150 rpm for 20 s. Immediately after production, test specimens (4 mm thick) from the samples were poured and cured at 95 C. (45 min) and 130 C. (60 min).

[0098] The results for different emulsifiers are presented in Table 1. The turbidity of the polyol mixture and of the cured 2K PU composition was determined as described above.

[0099] The K1C value was determined in accordance with ISO 13586:2000, using a Zwick Z 020 test apparatus and an effective force of 1 kN.

[0100] For determining the separation effect, a 2K PU composition was produced as above, poured onto a plate heated to 90 C. into a 4 cm4 cm shape (4 mm thick), and cured for 10 min. The mold was subsequently removed, the plate together with the molded body adhered thereto was positioned vertically, and the maximum force necessary for shearing was determined using a Zwick Z 010 test apparatus and converted into a stress (force/surface area, with a surface area of 16 cm.sup.2).

TABLE-US-00001 TABLE 1 Example Comparison 1 2a 2b 3 4 5 6 Polyol [g] 42.5 42.51 42.31 42.51 42.5 42.5 42.5 Polyisocyanate [g] 56.1 56.13 55.9 56.13 56.1 56.1 56.1 Emulsifier/release Emulsifier 1 0.86 agent [g] Emulsifier 2 0.86 1.29 Emulsifier 3 0.86 Dimer fatty acid 0.86 Polyoxyethylene 0.86 tridecyl ether phosphate Catalyst [g] 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Properties of the Turbidity Yes Yes Yes Yes No No No polyol mixture with (not homogeneously emulsifier/release miscible, i.e., agent transmittance < 90%) Properties of the Turbidity Yes Yes Yes Yes No No No cured resin Bubbles No No No No Yes Yes Yes without fibers Separation effect 7.4 4.3 4.1 7.2 48 14.8 14.4 [N/cm.sup.2] K1C [MPa m.sup.1/2] 1.4 1.4 1.6 1.4 1.2