Perfluoralkylsilan Beschichtungen für Formen und Werkzeuge in der Kunststofftechnik

Translated title of the contribution: Perfluoroalkyl Silane Coatings of Molds and Dies for Polymer Processing

Baris Kaynak

Research output: ThesisDoctoral Thesis

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Abstract

In this PhD thesis new coatings with anti-adhesive properties have been devel-oped for injection molding tools. Through the synthesis of dipodal organosilanes with perfluorinated carbon units, coatings with anti-adhesive properties and also with high thermal and mechanical stability were produced. Corona discharge, nitric acid treatment or deposition of zinc oxide nanostructures were used to activate the surface of stainless steel in order to increase the number of hydroxyl groups on the steel surface, which are required for the surface modification with organosilanes. Furthermore, the activation methods also served as a cleaning process for the steel surface and during the activation of the stainless steel the organic and inorganic contaminations were removed from the surface. After the activation of the steel samples, the surfaces were modified with com-mercially available monopodal organosilanes from an ethanol/water or toluene solution. The organosilane modification of stainless steel led to a significant decrease in the surface tension and adhesion forces on the steel surface. The organosilane layers with perfluorinated units also exhibited a temperature stability up to >300 °C. Furthermore, dipodal organosilanes with perfluorinated carbon units were synthesized by means of hydrosilylation. The activated stainless steel surfaces were modified with the synthesized dipodal organosilanes and characterized thoroughly. Compared to monopodal organosilane layers, dipodal organosilane layers showed significantly higher thermal and mechanical resistance. Dipodal perfluoroalkyl organosilane modification of stainless steel leads to a significant reduction of the adhesion force on the steel surface and to an increase of the water contact angle on the surface. Additionally, for increasing the thermal stability of the organosilane coatings, “truly perfluorinated organosilanes” were synthesized by a Grignard reaction. The layers of the “truly perfluorinated organosilanes” on the stainless steel surfaces also exhibited anti-adhesive properties. Finally, coatings were developed by combining the monopodal organosilanes with the synthesized dipodal organosilane. These coatings proved resistant against mechanical and thermal stress during the injection molding process. Through the organosilane based coatings the required forces for the demoulding of plastic components were reduced by >25% compared to uncoated tools. The new Organosilane based coatings were also tested for other industrial applications.
Translated title of the contributionPerfluoroalkyl Silane Coatings of Molds and Dies for Polymer Processing
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Kern, Wolfgang, Assessor A (internal)
  • Ribitsch, Volker, Assessor B (external), External person
Publication statusPublished - 2017

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