The importance of paperboard stiffness

　　Stiffness is a basic performance indicator for cardboard and whiteboard.

　　Paper stiffness is a very important indicator that directly affects the stiffness of the crease (another influencing factor is die-cutting pressure), which affects the finished product. Stiffness is small, the finished product is easy to crush and warp; the stiffness is large, and the finished product is difficult to form.

　　Packaging paper has a requirement for stiffness, different rations of paper stiffness is different, generally proportional to the square of the thickness, the thicker the board is, the higher the stiffness is.

　　Factors that affect bending stiffness

　　There are many factors that affect stiffness. The thickness and elastic modulus of the board are the most basic factors affecting the stiffness of the board or paper. When the thickness is constant, the stiffness increases as the tightness increases. When the weight is constant, it slightly increases with the increase in tightness and then slightly decreases, but the overall trend is a net increase.

　　Stiffness test method for paperboard

　　Stiffness measurement methods are fixed, but also have a non-fixed angle test specimen bending strength, the specimen free bending to measure the strength change. Some test methods have both. The stiffness of the paper is often measured by Clarke or the Grayer method.