When mixing two-component adhesives, the reaction typically begins instantly, meaning that users must work ‘against the clock’ to ensure that the mixed adhesive does not become so viscous that it cannot be applied, and also to avoid decreasing the bond strength due to the diminished wetting of the surface. Special care must also be taken during the mixing process to maintain the prescribed ratio of resin and hardener, since even a small deviation from the specified mix ratio can prevent the adhesive from curing properly.
Furthermore, because of the precise mix ratios required, a number of two component systems cannot be accurately proportioned in the small sized batches needed for production. To counter this problem, larger batches must be prepared where only a small percentage of the material is actually utilised and this results in a considerable amount of waste.
By choosing pre-mixed and frozen resins (PMF), these problems and hassles are eliminated, as the end user only needs to thaw and dispense the material.
PMF, for the record, refers to the blending, packaging and freezing of two component resin or catalyst systems, and offers convenience and reliability. Utilising the Pre-mixed Frozen service available from Ellsworth Adhesives, end users can remove the human error factor on their production line – as the company’s experts will mix, degas, weigh and package the two-component system, before flash freezing the package and contents at -80C.
Upon receiving the pre-mixed frozen product, the customer’s only responsibility is to store the goods in a freezer with temperature no lower than -40C. The PMF product will arrive in an insulated carton, and full instructions for handling, thawing and storage are provided.
During the mixing process of PMF packages, it is possible to modify the resin and catalyst systems with the addition of a third or fourth ingredient. Options include precision glass spacer beads, adhesion promoters, pigments, fluorescent indicators and fillers, all of which have the potential to enhance the physical properties of the final material.
Another major perk of using Pre-mixed Frozen resins, according to Ellsworth, is increased productivity on the production line, as a regular supply of PMF ensures, it states, that “production need not be halted or held up while fresh material is dispensed, mixed and distributed. The need for cleaning time is also virtually eliminated, since there are no messy containers or sticky bench tops to be considered”.
