| 摘要 |
PURPOSE:To obtain a water-absorbing material being excellent in a swelling rate and a swelling speed, by extruding a mixture of an ethylene-vinyl acetate copolymer, resin of high water absorption and calcium stearate under specific conditions. CONSTITUTION:0-2% calcium stearate and 0-2% pigment are added to the 100pts. total of 75+ or -20pts. ethylene-vinyl acetate copolymer containing 40+ or -20% vinyl acetate and having 700% or more extensibility or resin such as acrylic rubber and natural rubber having 700% or more extensibility, and fine powder of resin of high water absorption such as starch polyacrylate having a water absorbing power of 700g/g and a particle size of 50 meshes. A material thus prepared is mixed by a mixer 1 and thereby a composition is obtained. Next, this composition is supplied to the hopper 2 of an extruder and extruded in the shape of a sheet from a die 5 of the extruder 3 provided with a continuous roll with two shafts in the rotation ratio of 1:1-1.1 or extrusion ports arranged in one transverse line at the end, under the conditions of 50- 90 deg.C and 80r.p.m. or below. Then, the composition formed in a sheet is cut by a cutting blade 7 of a continuous cutter 6, and thereby pellets 8 whose swelling rate is 80 times or more in volume and whose swelling speed gets maximum within 12hr are obtained. |
