Sika Technology Ag

Tina Voci

Jan Olaf Schulenburg

Christian Krüger

David Hofstetter

Steffen Kelch

Michael Schlumpf

A two-component polyurethane composition includes a first component, including at least one polybutadiene polyol P1 having an average molecular weight of 2,000 to 10,000 g/mol and an average OH functionality of 2.1 to 4, and a second component, including at least one polyisocyanate and optionally at least one isocyanate-terminated polyurethane prepolymer. The composition also contains at least one hydrophobic diol P2 having an average molecular weight of 500 to 5,000 g/mol, selected from polybutadiene diols, polyester diols, polycarbonate diols, polyether diols having a repeat unit having at least 4 C atoms, and/or at least one hydrophobic compound P3, which is terminated with amino groups and has an average molecular weight in the range of 200 to 2,000 g/mol. The ratio of the number of hydroxyl groups from P1 to the number of hydroxyl and primary and secondary amino groups from P2 and P3 is 2:1 to 16:1.

Hydrophobic and highly elastic two-component polyurethane composition having mechanical properties and adhesive properties not dependent on temperature

An epoxy group-terminated impact modifier is described, comprising the reaction product of a) two or more polyols, b) one or more polyisocyanates, and c) at least one epoxy resin comprising a primary or secondary hydroxy group-containing epoxy compound, wherein the polyols comprise a1) at least one polyether polyol and a2) at least one OH-terminated rubber, wherein the weight ratio of polyether polyol to OH-terminated rubber is in the range from 7:3 to 2:8; an isocyanate-terminated prepolymer as possible intermediate product is described; furthermore a method for producing same is described. The products obtained are suitable for improving the impact resistance of epoxy resin compositions, in particular of 1K or 2K epoxy resin adhesives.

Impact modifiers for epoxy-based adhesives

A method is described for producing liquid rubber containing an impact-resistance modifier terminated by epoxy groups, the method including the reaction of an isocyanate-terminated prepolymer with an epoxy resin, which includes an epoxy compound including a primary or secondary hydroxyl group, in the presence of a compound selected from anhydrides, ketones and aldehydes as glycol scavengers, wherein the isocyanate-terminated prepolymer, the epoxy resin and the glycol scavenger are mixed with one another, or the epoxy resin is reacted with the glycol scavenger, before they are mixed with the isocyanate-terminated prepolymer. Gelling in the reaction mixture is avoided by the method. The resulting products are suitable for improving the impact resistance of epoxy resin compositions, particularly one-component or two-component epoxy resin adhesives.

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Zurich, Switzerland

Tina Voci