Production process of hydrophilic crosslinked polymer

A production process for a hydrophilic crosslinked polymer, comprising the steps of:

• a) polymerizing an aqueous solution including a hydrophilic monomer and a crosslinking agent to obtain a hydrogel crosslinked polymer, and drying the hydrogel crosslinked polymer, thus obtaining the hydrophilic crosslinked polymer,
• (b) with the step of drying the hydrogel crosslinked polymer comprising the steps of:
• i) drying the hydrogel crosslinked polymer in a static state until it becomes possible to disintegrate an aggregate of the hydrogel crosslinked polymer, wherein the step of drying in a static state is carried out by a drying method in which the hydrogel crosslinked polymer is brought into contact with a hot gaseous current, wherein the step of drying in a static state is carried out until the water content of the hydrogel crosslinked polymer is 25 weight % or less;
• then
• ii) disintegrating the dried hydrogel crosslinked polymer into a particle size of 20 mm or less;
• and then
• iii) drying the disintegrated hydrogel crosslinked polymer in a stirred state, wherein the step of drying in a stirred state is carried out by a drying method in which the hydrogel crosslinked polymer is dried while stirred by rotation of a rotor.

A production process for a hydrophilic crosslinked polymer, comprising the steps of:

• a) polymerizing an aqueous solution including a hydrophilic monomer and a crosslinking agent to obtain a hydrogel crosslinked polymer, and drying the hydrogel crosslinked polymer, thus obtaining the hydrophilic crosslinked polymer,
• (b) with the step of drying the hydrogel crosslinked polymer comprising the steps of:
• i) drying the hydrogel crosslinked polymer in a static state until it becomes possible to disintegrate an aggregate of the hydrogel crosslinked polymer, wherein the step of drying in a static state is carried out by a drying method in which the hydrogel crosslinked polymer is brought into contact with a hot gaseous current, wherein the step of drying in a static state is carried out until the water content of the hydrogel crosslinked polymer is 25 weight % or less;
• then
• ii) disintegrating the dried hydrogel crosslinked polymer into a particle size of 20 nm or less;
• and then
• iii) drying the disintegrated hydrogel crosslinked polymer in a fluidized state, wherein the step of drying in a fluidized state is carried out using a fluidized bed.