Ddp Specialty Electronic Materials US, LLC

Dow Global Technolgoies LLC

Irene Maeder

Andreas Lutz

Daniel Schneider

Marcel Aschwanden

Christof Braendli

Michael Ras

Benjamin Alexander Haag

The invention is an epoxy resin system useful as an adhesive for high temperature applications. The system is a combination of a diglycidyl ether a bisphenol epoxy resin(s), at amounts of 30-70% by weight, with 1-10% by weight of an epoxy novolac resin 10-30% by weight of a polyurethane toughener which preferably has the terminal isocyanate functional group blocked, 1-8% by weight of a hardener, 0.1-% by weight of a cure accelerator, preferably a latent urea cure accelerator, provides the desired balance of mechanical strength and elastic modulus. The epoxy novolac resin is characterized by at least one of the following features: (i) having a viscosity at 25 degrees C. of less than 3000 mPa-s according to ASTM D-445, (ii) an average number of epoxide groups per molecule of more than 2 but less than 3.7, and (iii) a molecular weight of less than 750 g/mol.

High temperature epoxy adhesive formulations

Adhesive bonds are applied by mixing two adhesives with different properties and dispensing them to form bondlines between substrate pairs. The adhesives are then thermally cured and cooled. Varying the mix ratio permits one to vary the properties of the adhesive mixture so formed for use in bonding many different substrate pairs. The process allows potentially infinite variations of adhesive properties between those of the respective starting adhesives, simply by varying the mix ratio. The invention is especially adapted for use in manufacturing settings in which adhesives are to be applied in multiple places, but differing adhesive properties are needed among the various bonding areas.

Method for bonding using one-component epoxy adhesive mixtures

Structural adhesives are prepared from a chain extended elastomeric toughener that contains urethane and/or urea groups, and have terminal isocyanate groups that are capped with a phenol, a polyphenol or an aminophenol compound. The adhesives have very good storage stability and cure to form cured adhesives that have good lap shear and impact peel strengths.

Structural epoxy resin adhesives containing chain-extended elastomeric tougheners capped with phenol, polyphenol or aminophenol compounds

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Freienbach, Switzerland

Irene Maeder