Birch Vale, UK -- Screen printing quality is critically affected by the performance of the squeegee-blade that controls the flow of ink over the substrate, according to Dow Hyperlast, which has recently developed a special polyurethane elastomer system for the purpose with exceptional resistance to swelling in solvents.
The working life of these blades can be drastically shortened by the quality of solvents that they operate in, the company points out. Responding to the requirements of printing industry supplier BMP Europe Ltd, Dow Hyperlast, part of Dow Polyurethanes, introduced Diprane 31 to provide the sector with an elastomer with higher resistance to solvent-based inks, which at the same time offers excellent mechanical properties.
Trials showed that this new material gives significantly lower swell than any other type of polyurethane elastomer, Dow Hyperlast claims. Solvent exposure tests in toluene, ethyl acetate, MEK and cyclohexanone demonstrated that Diprane 31 beats most existing and rival products, and promotes even longer product life, the company added.
BMP specialises in transforming engineered textiles and elastomers into finished products for specific applications, said Dow Hyperlast. The company makes a range of squeegee blades with minimal swelling that retaining hardness, resilience and abrasion resistance throughout their working lives.
In use, the squeegee blades control the flow of solvent-based printing inks through a tightly meshed screen on to substrate, which could be paper, cardboard, vinyl, glass or other material.
BMP's Viper range, based on Diprane 31, provides a more resilient product for the printing industry.
Dow Hyperlast said it is now also examining the potential for using the PU elastomer to make rollers for the printing industry. As well as promoting a longer product life, Diprane 31 can be processed at lower temperatures and is available in a range of hardnesses as a three-component blend.