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 method for producing a composite of fibers in a matrix of a crosslinked two-component polyurethane composition, comprising (i) providing a mold; (ii) providing fibers; (iii) providing a mixed two-component polyurethane composition, the two-component polyurethane composition comprising 10 to 80% by weight of at least one polyol having a number average molecular weight of 104 to 3000 g/mol, wherein the polyol is a polyether polyol, 5 to 70% by weight of at least one polyisocyanate selected from the group consisting of MDI, higher-functional homologs, and combinations thereof, and 0.2 to 1.29% by weight of at least one emulsifier selected from a group consisting of: a tetrafunctional polyol esterified with a mixture of a difunctional carboxylic acid and an unsaturated fatty acid having an average C atom chain length of 18; dipentaerythritol completely esterified with oleic acid; diester of a dimer fatty acid with branched alcohols having an average C atom chain length of 8; and combinations thereof, wherein the composition is free of low molecular weight polyols having an OH functionality of 2 and a molecular weight of 100 or less and 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%; and wherein the % by weight relate to the total weight of the two-component polyurethane composition, (iv) disposing the fibers in the mold; (v) closing the mold around the fibers; (vi) introducing the mixed two-component polyurethane composition into the closed mold under pressure and/or vacuum; (vii) curing the fibers and mixed two-component polyurethane composition in the mold to form the composite; and (viii) removing the composite from the mold.

2. The method according to claim 1, wherein the at least one polyol has an average OH functionality of 3 to 5.

3. The method 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.

4. The method according to claim 1, wherein less than 3 mol-% of the NCO groups are reacted to form carbodiimide and/or uretonimine groups.

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

6. The composite according to claim 5, wherein the crosslinked two-component polyurethane composition has a glass transition temperature T.sub.G of above 60 C.

7. The composite according to claim 5, 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.

8. The composite according to claim 5, wherein the fibers are contained in a volume fraction of greater than 40% by volume, based on the overall composite.

9. An automotive component comprising the composite according to claim 5.

10. The method according to claim 1, wherein the at least one emulsifier is not homogeneously miscible with the at least one polyol.

11. The method of claim 1 being resin transfer molding (RTM).

12. The method of claim 1 wherein the cured composite is free of bubbles.

13. A method for producing a composite of fibers in a matrix of a crosslinked two-component polyurethane composition, comprising: (i) providing a mold; (ii) providing fibers; (iii) providing a mixed two-component polyurethane composition, the two-component polyurethane composition consisting of 10 to 80% by weight of at least one polyol having a number average molecular weight of 150 to 3000 g/mol, wherein the polyol is a polyether triol or polyether diol or mixture thereof, 40 to 70% by weight of at least one polyisocyanate, wherein the polyisocyanate is selected from the group consisting of MDI, higher-functional homologs, and combinations thereof, and 0.5 to 6% by weight of at least one emulsifier selected from the group consisting of: a tetrafunctional polyol esterified with a mixture of a difunctional carboxylic acid and an unsaturated fatty acid having an average C atom chain length of 18; dipentaerythritol completely esterified with oleic acid; diester of a dimer fatty acid with branched alcohols having an average C atom chain length of 8; and combinations thereof, and at least one additive selected from the group consisting of leveling agent, wetting gent, catalyst, age inhibitor, drying agent, resin, wax, stabilizer, plasticizer, pigment, drying agent and combinations thereof, wherein the composition is free of low molecular weight polyols having an OH functionality of 2 and a molecular weight of 100 or less and 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%; (iv) disposing the fibers in the mold; (v) closing the mold around the fibers; (vi) introducing the mixed two-component polyurethane composition into the closed mold under pressure and/or vacuum; (vii) curing the fibers and mixed two-component polyurethane composition in the mold to form the composite; and (viii) removing the composite from the mold.

14. The method according to claim 13, wherein the at least one emulsifier consists of diester of a dimer fatty acid with branched alcohols having an average C atom chain length of 8.

15. The method according to claim 13, wherein the at least one emulsifier consists of tetrafunctional polyol esterified with a mixture of a difunctional carboxylic acid and an unsaturated fatty acid having an average C atom chain length of 18.

16. The method according to claim 13, wherein the at least one emulsifier consists of dipentaerythritol completely esterified with oleic acid.

17. The method according to claim 13, wherein polyether polyol is a polyether diol.

18. The method according to claim 13, wherein polyether polyol is a polyether triol.

19. The method according to claim 1, wherein the mixed two-component polyurethane composition comprises 0.86 to 1.29% by weight of the at least one emulsifier.

Description

EXAMPLES

Raw Materials

(1) 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 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) 3. Catalyst: solution of a bicyclic tertiary amine (DABCO) in polyol (30% by weight DABCO, based on the solution) 4. Emulsifier/release agent: Emulsifier 1: tetrafunctional polyol esterified with a mixture of a difunctional carboxylic acid (C6) and an unsaturated fatty acid (average C chain length 18) Emulsifier 2: dipentaerythrite completely esterified with oleic acid Emulsifier 3: diester of a dimer fatty acid with branched alcohols (average alcohol chain length C8) Dimer fatty acid Polyoxyethylene tridecyl ether phosphate

Component A

(2) 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

(3) The polyisocyanate was used as component B.

2K PU Composition

(4) 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).

(5) 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.

(6) 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.

(7) 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).

(8) 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