Method of making a foam injection molded article
AssigneeEnron Chemical Company
InventorsRobert M. Lapierre, Nicholas J. Leonardi
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Abstract
A method of making a foam injection molded article is disclosed wherein corrosion of the mold element is significantly reduced or substantially eliminated. The method comprises dispersing effective amounts of a primary chemical blowing agent of sodium borohydride and an activation system of sodium bicarbonate/citric acid mix into a polymer resin to form a mixture. The mixture is then heated whereby the activation system releases water and the sodium borohydride reacts with the water to produce hydrogen gas. The mixture is subsequently injected into a mold to obtain expansion of the polymer resin to form the foam article. The invention also comprehends a corresponding chemical blowing agent composition.
Claims28
A method of making a foam injection molded article, said method comprising the steps of:
- dispersing into a polymer resin (a) an effective amount of a primary chemical blowing agent comprising sodium borohydride and (b) an activation system comprising a first mixture of effective amounts of sodium bicarbonate and citric acid, to form a second mixture of said resin, primary chemical blowing agent and activation system, said sodium borohydride and said activation system being isolated from direct contact with each other until gas production is desired;
- heating said second mixture whereby said activation system releases water and said sodium borohydride reacts with said water to produce hydrogen gas;
- and
- subsequently injecting said second mixture into a mold obtaining expansion of said polymer resin into a molded foam article.
A method of making a foam injection molded article, said method comprising the steps of:
- dispersing into a polymer resin to be foamed (a) an effective amount of a primary chemical blowing agent consisting essentially of sodium borohydride and (b) no more than about 8 parts by weight, per part by weight of said sodium borohydride, of an activation system comprising a first mixture of effective amounts of sodium bicarbonate and citric acid, to form a second mixture of said resin, sodium borohydride and activation system with said sodium borohydride comprising about 0.01-5 weight percent of said second mixture, said sodium borohydride and said activation system being isolated from direct contact with each other until gas production is desired;
- heating said second mixture whereby said activation system releases water and said sodium borohydride reacts with said water to produce hydrogen gas;
- and
- subsequently injecting said second mixture into a mold obtaining expansion of said polymer resin into a molded foam article.
Dependencies are inferred from the claim text.