You must be asking yourself what is a starch adhesive for, and why so many businesses and industries use it. Starch adhesives are commonly used for paper products such as corrugated boxes and board, paper bags, tube winding (such as the inside of toilet rolls and paper towel), labeling and envelopes, as well as wallpaper paste and laminating.
The reason starch adhesives are so ideal for these products is because they are thicker (more viscous) than many other adhesives, and can be formulated into a paste if required. They can be used at ambient conditions or, depending on the intended application, can be heated to up to 140oF. They also have quicker tack and better fluid properties, which make for easy clean up, and are generally a more economical choice.
The paper and corrugated industry is continually striving to improve its machine speeds and board quality, and therefore insists that starch adhesives should be of the highest possible standard. To help achieve this, significant improvements have been made in the way in which starch is mixed.
The Importance of the Right Starch Mixing System
Because so much starch adhesive is used in the corrugating industry, corn starch is delivered as a dry powder that is then stored in huge silos until needed. When it is drawn from the silo, the dry starch is mixed with water and other chemicals, before being pumped into the corrugator.
Your starch mixing system plays a critically important role in the process, since the adhesive paste is too thin (in other words, it has low viscosity) and the water tends to “wick” into the medium. This means the pearl starch may not gelatinize properly, resulting in the board that comes off the corrugator being dry and brittle.
If the adhesive paste is too thick or heavy (high viscosity), it tends to penetrate the medium and glue line very slowly, as it sits on top of the flute tip. This results in soft, wet board coming out of the corrugator. Printing is very difficult on wet board, and it is hard to convert in the finishing department. Thick adhesive also increases the consumption of starch and reduces flow in the glue pans, allowing heat to build up and causing gelling problems.
The Future of Starch Adhesive
RapidBond is proud to introduce the Flexamix, the only truly sustainable starch mixing system in North America capable of mixing the perfect adhesive formulation for any type of paper. Visit rapidbond.net for more information.
