Patent ID: 7942992

Claim:
A process of producing a bulky sheet material having three-dimensional protrusions comprising a first fiber layer and a second fiber layer provided on at least one side of said first fiber layer, said first fiber layer containing thermally shrunken heat-shrinkable fibers, said second fiber layer comprising heat non-shrinkable fibers, said first fiber layer and said second fiber layer being partly joined together at a large number of joints formed by fusion bonding, said joints being formed by melting and solidification of a heat fusible resin having a higher melting point than the shrinkage starting temperature of said heat shrinkable fiber, said second fiber layer forming a large number of protrusions between said joints by the heat shrinkage of the first fiber layer, and said joints forming depressions, wherein said process comprises the steps of: partly fusion bonding a first fiber layer-forming material containing said heat shrinkable fibers and a second fiber layer-forming material comprising said heat non-shrinkable fibers provided on at least one side of said fiber layer-forming material with a heat embossing machine at or above the shrinkage starting temperature of said heat shrinkable fiber of said first fiber layer-forming material while applying tension to both said first fiber layer-forming material and said second fiber layer-forming material to form said joints, continuing applying said tension to both said first fiber layer-forming material and said second fiber layer-forming material which have passed through the heat embossing machine until the temperature of said heat shrinkable fibers contained in said first fiber layer-forming material reduces lower than the shrinkage starting temperature of said heat shrinkable fiber, releasing said tension and heating said first fiber layer-forming material and said second fiber layer-forming material at or above the shrinkage starting temperature of said heat shrinkable fiber to shrink said heat shrinkable fibers and to raise said second fiber layer-forming material between said joints thereby to form a large number of said protrusions.