External mix spray urethane process and nozzle used therefor
View Patent ↗A method of forming a polyurethane article wherein first and second components of a polyurethane system are sprayed into an unconfined space above a mold. The first and second components are sprayed together to mix initially in the space above the mold and then are deposited in the mold on an in-mold coating that was previously applied to the mold. The two components of the polyurethane system and in-mold coating are subsequently removed from the mold as a flexible polyurethane skin. The skin may then be placed in a second mold along with a reinforcement. Structural polyurethane foam may then be injected to the second mold where it bonds to the reinforcement and the skin to form a finished polyurethane article having a flexible skin adhered to its surface. A post-mix spray nozzle assembly is provided with a central nozzle forming a first hollow conical spray pattern and a coaxially aligned annular nozzle forming a second hollow conical spray pattern. The first and second hollow conical spray patterns intersect in space remote from the nozzle and form a hollow circular spray pattern.
1. A method of forming an article, comprising:
applying a mold release agent onto a mold;
applying an in-mold coating onto the mold;
spraying a first component of a polyurethane system into the space above the mold; and
spraying a second component of the polyurethane system into the space above the mold separately from the first component while the first component thereof is sprayed so that the first and second components mix initially in the space above the mold and are then deposited in the mold onto the in-mold coating.
2. The method of forming an article of claim 1 wherein the first component is a isocyanate and the second component is a polyol.
3. The method of forming an article of claim 1 wherein the steps of spraying the first and second components are performed by spraying through separate nozzles that each produce a fan spray.
4. The method of forming an article of claim 1 wherein the steps of spraying the first and second components are performed by spraying through a first and a second separate nozzles wherein the first nozzle sprays in a substantially conical pattern and the second nozzle sprays in a substantially cylindrical spray pattern that intersects the substantially conical spray pattern of the first nozzle.
5. The method of claim 4 wherein the first composition is an isocyanate composition and the second composition is a polyol.