A color copy may exhibit more severe curl than a black-and-white
copy due to profound shrinkage difference between
multiple toner layers and the base paper after the fusing process.
An untreated curled copy may cause paper handling problems and it
is unacceptable to customers.
This paper analyzes factors contributing to copy curl
developed after the fusing process with an emphasis on the
stiffenss and shrinkage interactions between the toner layer and
the paper. Specifically, a bi—material curl model of toner—
paper composite is formulated in terms of ratios of toner/paper
thickness, modulus of elasticity and expansion coefficient. The
curl model regards the temperature and moisture changes as the
driving forces for the curling of a fused copy.
Besides predicting away—from—image and toward—image curls,
the model can be used to determine requirements of toner
modulus,layer thickness and fusing temperature to meet specified
curl limits of fused copies.