Granted Patent B2

US 8,110,704 · App. 11/591,779 · Granted Feb 7, 2012

Abstract

Claims (16)

1. A process for the production of a stable NCO prepolymer having an NCO content of from 2.5 to 6 wt. % and a viscosity at 100° C. of 5000 mPas comprising:

a) reacting

(1) a polyisocyanate having a melting point greater than 70° C. with

(2) one or more polyols, having an average molecular weight of 1000 to 3000 g/mol, a viscosity measured at 75° C. of 700 mPas and a functionality of 1.95 to 2.15,

(3) optionally in the presence of auxiliary substances and additives, at a temperature of from 80° C. to 240° C. in a ratio of NCO to OH groups of from 1.55:1 to 2.35:1 to form a prepolymer,

and

b) rapidly cooling the prepolymer formed in a) in a manner such that the residence time of the prepolymer

A) in the temperature range between the temperature at the end of a) to 130° C. does not exceed ½ hour and

B) in the temperature range from the temperature at the end of a) to 110° C. does not exceed 1.5 hours and

C) in the temperature range from the temperature at the end of a) to 90° C. does not exceed 7.5 hours and

D) in the temperature range from the temperature at the end of a) to 70° C. does not exceed 72 hours,

in which unreacted polyisocyanate still present after cooling is not removed and is present in an amount greater than 0.3 wt. % and less than 5 wt. %, based on the weight of the prepolymer.

2. The process of claim 1 in which the polyisocyanate having a melting point greater than 70° C. is 1,5-naphthalene diisocyanate.

3. The process of claim 1 in which the polyol is selected from the group consisting of polyester polyols, poly-ε-caprolactone polyols, polycarbonate polyols, polyether polyols, α-hydro-ω-hydroxypoly(oxytetramethylene) polyols and combinations thereof.

4. The process of claim 1 which is conducted on a continuous basis.

5. The process of claim 1 which is conducted on a batch basis.

Assignments (8)