Polyurethane material with a high temperature resistance

Abstract

Described herein is a process for preparing a polyurethane-type fiber composite material, said process including (a) di- and/or polyisocyanates, (b) compounds having isocyanate-reactive hydrogen atoms, (c) compounds including at least one carbon-carbon double bond, (d) optionally a catalyst to hasten a urethane reaction, (e) optionally a free-radical initiator, and (f) optionally further auxiliary and added-substance materials, being mixed into a reaction mixturewith concomitant wetting of a fiber materialand cured. Also described herein is a polyurethane-type fiber composite material obtainable by a process described herein and also to a method of using the polyurethane-type fiber composite material as a structural component part.

Claims

1. A process for preparing a polyurethane material, said process consisting of forming a reaction mixture consisting of: a) di- and/or polyisocyanates, b) compounds having isocyanate-reactive hydrogen atoms, c) compounds comprising at least one terminal carbon-carbon double bond, d) optionally a catalyst to hasten a urethane reaction, e) optionally a free-radical initiator, and f) optionally further auxiliary and added-substance materials, curing the reaction mixture to obtain the polyurethane material, and optionally free-radical polymerizing the compounds (c) comprising at least one terminal carbon-carbon double bond, wherein: the compounds (b) having isocyanate-reactive hydrogen atoms contain on average not less than 1.5 isocyanate-reactive hydrogen groups per molecule, a double bond density of the compounds (c) is not less than 21% and the compounds (c) have no isocyanate-reactive groups, wherein the double bond density is calculated by dividing a molecular mass of the at least one terminal carbon-carbon double bond (as determined by a molecular formula CHCH.sub.2) by a total molecular mass of the compounds (c), a double bond functionality of the compounds (c) is greater than 1, and an equivalence ratio between isocyanate groups of the di- and/or polyisocyanates (a) and the isocyanate-reactive hydrogen atoms of the compounds (b) is in the range from 0.8 to 2.

2. The process according to claim 1 wherein the compounds (b) having isocyanate-reactive hydrogen atoms comprise polymeric compounds having isocyanate-reactive hydrogen atoms and optionally chain extenders and/or crosslinking agents, wherein the polymeric compounds having isocyanate-reactive hydrogen atoms have a molecular weight of 300 g/mol or above and the chain extenders and crosslinking agents have a molecular weight of less than 300 g/mol.

3. The process according to claim 2 wherein the polymeric compounds having isocyanate-reactive hydrogen atoms have an average hydrogen functionality of 2 to 4 and a proportion of secondary OH groups of not less than 50% based on the total number of OH groups.

4. The process according to claim 1 wherein the compounds (b) having isocyanate-reactive hydrogen atoms comprise at least one hydroxyl-functional compound having hydrophobic groups.

5. The process according to claim 1 wherein said di- or polyisocyanates (a) comprise 2,4-MDI, 4,4-MDI, polymeric MDI or mixtures of two or more thereof.

6. The process according to claim 1 wherein a proportion of the compounds (c) comprising at least one terminal carbon-carbon double bond is in the range from 10 to 70 wt %, based on a combined weight of components (a) to (f).

7. The process according to claim 1 wherein the compounds (c) comprising at least one terminal carbon-carbon double bond are free-radically polymerized during a polyurethane reaction of components (a) and (b).

8. The process according to claim 1 wherein the free-radical polymerization of the compounds (c) comprising at least one terminal carbon-carbon double bond is initiated via free-radical initiator, irradiation with high-energy radiation or thermally at temperatures above 150 C.

9. The process according to claim 1, wherein the di- or polyisocyanates (a) are polymeric MDI and the compounds (c) are trimethylolpropane triacrylate or dipropylene glycol diacrylate.

10. A polyurethane material obtained by the process according to claim 9.

11. A structural component part comprising the polyurethane material according to claim 10.

12. An adhesive comprising the polyurethane material according to claim 10.

Description

(1) The examples which follow illustrate the invention.

(2) Materials Used:

(3) polyol 1: castor oil polyol 2: glycerol-started polypropylene oxide having a functionality of 3.0 and an OH number of 805 mg KOH/g polyol 3: sucrose and diethylene glycol co-started polypropylene oxide/polyethylene oxide with propylene oxide cap having a functionality of 4.5 and an OH number of 400 mg KOH/g TMPTA: trimethylolpropane triacrylate, double bond density 26.35 polyol 5: dipropylene glycol DPGDA: dipropylene glycol diacrylate, double bond density 21.5 iso 1: polymeric MDI

(4) Test plaques 2 mm in thickness were cast at an isocyanate index of 120 in accordance with Table 1. Its entries are all parts by weight unless otherwise stated. DSC was subsequently used to determine the glass transition temperature of the samples. To this end, the sample was twice heated from room temperature to 300 C. at a rate of 20 K/min. The glass transition temperature was determined from the data of the second heating.

(5) TABLE-US-00001 TABLE 1 polyol 1 44.8 26.7 26.7 polyol 2 25 15 15 polyol 3 25 15 15 drier 5 3 3 defoamer 0.2 0.2 0.2 TMPTA 40 DPGDA 40 iso iso 1 100 100 100 Tg in C. ; DSC 2.sup.nd heating 95 179 123 temperature of deflection in 70 150 not measured C. under a load of 0.45 MPa (to DIN EN ISO 75-1)

(6) The polyurethanes of the present invention display a distinctly raised glass transition temperature and improved heat resistance for the polyurethane material of the present invention versus the comparative material without carbon-carbon double bond compound. The table further shows that a high double bond density versus DPGDA leads to distinctly raised glass transition temperatures.