Starches in spray application improve strength characteristics, especially Z-strength and Scott bond value, of the ready paper/board.
A starch slurry (uncooked) is sprayed between layers during board manufacture or in the wet section at fluting production. The starch granules swell/gelatinise when the paper/board comes to the drying section. The swollen granules provide a glue effect and increase the contact surfaces between fibres, fine material and filler and results in higher strength properties. The gelatinisation temperature is affected by the type of starch and modification. It is important to find a starch with the proper characteristic for your system; a too low gelatinisation temperature can result in bad runnability and deposits in the wire section while a too high gelatinisation temperature will results in no gelatinisation and no strength increase. It is also important that there is sufficient water left when the paper/board reaches the drying section to enable the starch granules to swell. If the water content is too low, the granules will not swell and the glue effect is not achieved. Dry content after press section and temperature profile in the drying section are important parameters to control to achieve maximum benefits of a spray starch.
Our application lab can investigate the gelatinisation temperature for different starches and modifications.
Solam has a broad product portfolio of spray starches. The brand name for Solam spray starches are Solspray.
The Solam team is ready to assist you in selecting an optimum starch for your spray application.