| abstract |
(57) [Summary] [Problem] To provide a low-density mat board paper having a high rice tsubo, a reduced amount of vegetable fiber, and dimensional stability, sufficient stiffness, strength, and good workability. A surface layer / inner layer or a surface layer / inner layer / A low-density mat board paper obtained by making a multilayer comprising a surface layer, wherein the surface layer has a density of 0.65 to 0.9. 0 g / cm 3 , and the inner layer portion contains heat-expandable particles and has a density of 0.2 to 0.5 g / cm 3 , a temperature of 23 ° C., and a longitudinal direction when the humidity is changed from 20% to 80%. Are prepared so as to exhibit a dimensional change of 0.3% or less in elongation and 1.0% or less in lateral direction. |