Method for minimizing emissions while forming a polyurethane foam

摘要

A method minimizes emissions while spraying a mixture of a resin composition and a polyisocyanate onto a surface. The resin composition has a hydroxyl content of at least 400 mg KOH/g and includes a blowing agent that is a liquid under pressure, a first polyol, at least one additional polyol other than the first polyol, and optionally a catalyst, surfactant, and water. The mixture is sprayed onto the surface to form a polyurethane foam having a closed cell content of at least 90 percent. The mixture is also sprayed through a spray nozzle at a spray angle corresponding to a control spray angle of from 15 to 125 degrees measured at a pressure of from 10 to 40 psi using water as a standard. The step of spraying produces less than 50 parts of the polyisocyanate per one billion parts of air according to OSHA Method 47.

主权项

1. A polyurethane spraying system used to minimize emissions of a polyisocyanate while spraying a mixture of a polyisocyanate and a resin composition onto a surface, said system comprising:
A. a first reactant supply tank comprising the resin composition having a hydroxyl content of at least 400 mg potassium hydroxide per gram (KOH/g) and comprising:
(i) a blowing agent that is a liquid at room temperature under a pressure greater than atmospheric pressure;(ii) a first polyol selected from the group of a Mannich polyol, an autocatalytic polyol, and combinations thereof;(iii) at least one additional polyol other than the first polyol;(iv) an optional catalyst;(v) an optional surfactant, and(vi) optionally water, wherein said resin composition has no other blowing agents; B. a second reactant supply tank comprising the polyisocyanate; C. a source of a gaseous propellant that is coupled with said first and second reactant supply tanks; D. a mixing apparatus that is coupled with said first and second reactant supply tanks for mixing the resin composition and the polyisocyanate prior to spraying; E. a spray nozzle that is coupled with said mixing apparatus and that produces less than 50 parts of the polyisocyanate per one billion parts of air according to Occupational Safety & Health Administration Method 47 while spraying the mixture onto the surface at a rate of 5 to 30 lbs/min to form a polyurethane foam having a closed cell content of at least 90 percent, said spray nozzle comprising:
(i) a nozzle body having a longitudinal axis, upstream and downstream ends opposite each other, and a passage defined by said nozzle body and in fluid communication with said upstream and downstream ends along said longitudinal axis for receiving the mixture; and(ii) a circular spraying orifice having a radius of from 0.01 to 0.25 inches and defined by said nozzle body and disposed at said downstream end of said nozzle body transverse to said longitudinal axis for spraying the mixture at a spray angle corresponding to a control spray angle of from 15 to 125 degrees measured at a pressure of from 10 to 40 psi using water as a standard.