Polyurethane resins

Details Polyurethane resins Polyurethane resins

1998-09-15

2000-04-04

Sergent, Rabon

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

521172, 521170, 521125, 528 80, 528 81, 528 57, C08G 1842, C08G 1864, C08G 1840

Patent

active

060462981

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to the production of polyurethane materials from polyols based on randomized castor oil and isocyanates. The mechanical properties of the polyurethane materials according to the invention are comparable with those of the materials obtainable from unmodified castor oil, although the gel time of the systems is far longer.
2. Discussion of Related Art
The use of castor oil and/or other hydroxyfunctional triglycerides for the production of polyurethanes has been known for some time. For example, the production of elastomers from castor oil and corresponding isocyanates is described in Saunders, Frisch: "Polyurethanes: Chemistry and Technology, II Technology", Interscience (1964). However, optimal processing of these generally two-component systems involves a long gel time, i.e. the time during which the mixture of the two components can undergo irreversible changes in its external form should be considerable. A long gel time is of advantage above all where two-component (2C) systems are used for the production of coatings because, on the one hand, better flow is guaranteed and, on the other hand, the degassing time available to the system is clearly increased which can contribute towards reducing bubble formation. Overly short gel times can lead to poor processability of the polyurethane systems, for example even in summer or in countries with a generally fairly high ambient temperature.
Whereas the use of catalysts, such as dibutyl tin dilaurate for example, has generally been regarded among experts as the easiest solution to the problem of shortening the gel time, increasing the gel time is far more difficult. An extended gel time was achieved, for example, by incorporation of low molecular weight polyols although this resulted in a possibly unwanted deviation from the originally planned material properties. Accordingly, attempts to extend the short gel time or pot life of the mixtures without affecting material quality have hitherto failed.
Accordingly, the problem addressed by the present invention was to modify oleochemical polyols based on castor oil in such a way that, on the one hand, the polyol component could be processed to materials, such as casting resins or two-component foams for example, having the required mechanical properties while, on the other hand, the gel time of the polyols could be extended as required for their use in two-component systems.
It has now surprisingly been found that randomized castor oil, which is obtainable by heating castor oil at temperatures above 100.degree. C. in the presence of lithium as catalyst, leads to a significant increase in the gel time without adversely affecting the properties of the polyurethane resin.


DESCRIPTION OF THE INVENTION

Accordingly, the present invention relates to a process for extending the gel time of polyurethane resins of isocyanates and a polyol component with an NCO:OH ratio of 10:1 to 1:10, characterized in that castor oil heated for about 0.1 to 15 hours to 100-300.degree. C. in the presence of a basic lithium salt is used in a quantity of 0.1 to 100% by weight as a constituent of the polyol component.
The modification of the castor oil takes place under conditions which are normally used for the transesterification of triglycerides. Thus, the reaction is generally carried out in an inert gas atmosphere, the castor oil being heated to a temperature of at least 100.degree. C. in the presence of the water-free lithium salts. The reaction temperature should generally not exceed 300.degree. C. because otherwise product quality might suffer. Normally, the reaction is carried out at temperatures below that limit, above all for the production of light-colored modified castor oils with low viscosities. Accordingly, it has proved to be of advantage to carry out the reaction at a temperature in the range from about 150 to 280.degree. C. and, more particularly, at a temperature of 200 to 280.degree. C., temperatures in the range from 220 to 260.degree. C. leading

REFERENCES:
patent: 4267081 (1981-05-01), Seneker
patent: 5045590 (1991-09-01), Motomura et al.
Saunders, Frisch: Polyurethanes: Chemistry and Technology, II Technology, Interscience pp. 32-37, 198-199, 778-779 (1964).

Affiliated with

Also associated with

Rating

Polyurethane resins does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Polyurethane resins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyurethane resins will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-366311