Stiffness is the compute of force requisite to bend a paper throughout a specified slant. Stiffness is a vital asset for box boards, corrugating standard and to firm degree for printing papers also. A limpy and feeble paper can be source for feeding and delivery problems in larger sheet presses. A sheet that is excessively stiff will cause problems in copier machines where it must pass through over, under, and around feed rollers. Bond papers also necessitate assured stiffness to be flat in typewriters etc.
A measure of flexural rigidity, Stiffness is the bending moment (g-cm or mNm) required to repel the free end of a 1.5 inch wide vertically clamped sample 150 from its middle line when weight is applied 50 mm away from the clamp. It is measured in MD &CD.
Droop Rigidity: Droop rigidity measures the stiffness of the paper or board, more often applied to lighter mass grades. CD refers to cross direction, and MD to machine direction, Droop rigidity is high in the machine direction. The higher the value the stiffer the paper
Goodrich Agrochem’s Coating & Laminating Binder products provide solutions to improve the stiffness in paper.
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