Porous, powdery polypropylene

US4379860A · kind A · utility

Assignee

• Akzo N.V. · NL

Inventors

• Walter Fickel · Zell am Harmersbach, DE
• Gerhard Ries · Obernburg, DE

Key dates

• Filing date: Jun 30, 1981
• Grant date: Apr 12, 1983
• Expiry date: Jun 30, 2001

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/2982
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Process for the production of porous, powdery polypropylene, and utilization thereof. Hot solutions of polypropylene in pentaerythrol ester are slowly cooled down to approximately room temperature, forming a solidified mass, after which it is extracted with an extractant in which pentaerythrol is soluble. Before extracting, the size of the solidified mass may be reduced mechanically. After extracting, the pentaerythrol may be removed from the extractant to a high degree. Preferred embodiments include using solutions of polypropylene in pentaerythrol esters of fatty acids, more specifically, of synthetic fatty acids with 8-10 carbon atoms; using ethanol for the extraction; using solutions with a weight ratio of polypropylene to pentaerythrol ester of 30:70 to 10:90; having cooling of the solutions within the range of 260.degree. to 120.degree. C. proceed at an average rate of 1.degree. to 20.degree. C. per minute; using polypropylene with an admixture of up to 10% by weight of polyethylene. The porous, powdery polypropylene is characterized by an apparent density of 0.1 to 0.3 g/cm.sup.3, a particle size of 50-700 .mu.m, and an externally accessible porosity of 70-85%. The product m…