Abstract: Provided is a production method for a water-absorbing resin in which an absorption capacity without pressure of the resulting water-absorbing resin is high and a water-absorbing resin can be efficiently obtained. The production method for a water-absorbing resin including a polymerization step of polymerizing a monomer composition containing an internal crosslinking agent and a monomer to obtain a crosslinked hydrogel polymer, and a drying step of drying the crosslinked hydrogel polymer to obtain a dry polymer, in which the crosslinked hydrogel polymer to be subjected to the drying step contains 50 ppm or more of hydrogen peroxide with respect to the solid content mass of the crosslinked hydrogel polymer, and the crosslinked hydrogel polymer is heated during the drying step so that a maximum reaching temperature of the crosslinked hydrogel polymer exceeds 160° C., and/or the dry polymer is heated after the drying step so that a maximum reaching temperature of the dry polymer exceeds 160° C.

Abstract: The production method includes a drying step of drying a particulate crosslinked hydrogel polymer obtained by polymerizing a monomer, which is a material of a water-absorbent resin, using a heating device to obtain dried particles. The heating device includes: a rotary container that contains the particulate crosslinked hydrogel polymer therein and rotates; and a plurality of heating tubes that are located within the rotary container, extend in an axial direction of the rotary container, and rotate together with the rotary container. A gel temperature of the particulate crosslinked hydrogel polymer to be subjected to the drying step, the gel temperature being measured by a contact thermometer, is not lower than 50° C.

Abstract: The production method includes: a gel-crushing step of grinding a crosslinked hydrogel polymer to obtain a particulate crosslinked hydrogel polymer; a heating drying step of obtaining dried particles from the particulate crosslinked hydrogel polymer by using a continuous stirring drying machine; a post-crosslinking step of post-crosslinking the particulate crosslinked hydrogel polymer or the dried particles; and a sizing step of adjusting a particle size of the dried particles or the post-crosslinked dried particles to obtain water-absorbent resin powder. The particulate crosslinked hydrogel polymer contains a gel fluidizer. A gel temperature of the particulate crosslinked hydrogel polymer containing the gel fluidizer, the gel temperature being measured by a contact thermometer, is not lower than 50° C. In the production method, the dried particles or the post-crosslinked dried particles is forcedly cooled before the sizing step.

Abstract: The production method includes: a gel-crushing step of grinding a crosslinked hydrogel polymer to obtain a particulate crosslinked hydrogel polymer; a heating drying step of obtaining dried particles from the particulate crosslinked hydrogel polymer by using a continuous stirring drying machine; a post-crosslinking step of post-crosslinking the particulate crosslinked hydrogel polymer or the dried particles; and a sizing step of adjusting a particle size of the dried particles or the post-crosslinked dried particles to obtain water-absorbent resin powder. The particulate crosslinked hydrogel polymer contains a gel fluidizer. A gel temperature of the particulate crosslinked hydrogel polymer containing the gel fluidizer, the gel temperature being measured by a contact thermometer, is not lower than 50° C. In the production method, the dried particles or the post-crosslinked dried particles is forcedly cooled before the sizing step.

Abstract: The production method includes a drying step of drying a particulate crosslinked hydrogel polymer obtained by polymerizing a monomer, which is a material of a water-absorbent resin, using a heating device to obtain dried particles. The heating device includes: a rotary container that contains the particulate crosslinked hydrogel polymer therein and rotates; and a plurality of heating tubes that are located within the rotary container, extend in an axial direction of the rotary container, and rotate together with the rotary container. A gel temperature of the particulate crosslinked hydrogel polymer to be subjected to the drying step, the gel temperature being measured by a contact thermometer, is not lower than 50° C.

Abstract: The invention provides a retardation film, composed primarily of an acrylic polymer, with transparency, heat resistance, and large retardation. The retardation film of the present invention is composed primarily of an acrylic polymer. The film has an in-plane retardation of from 130 nm to 500 nm, inclusive, per 100 ?m thickness at a wavelength of 589 nm. The film has a total light transmittance of not less than 85%. The retardation film has a glass transition temperature of preferably from 110° C. to 200° C., inclusive. The acrylic polymer, which is the primary component, preferably has a lactone ring structure.

Abstract: The invention provides a retardation film, composed primarily of an acrylic polymer, with transparency, heat resistance, and large retardation. The retardation film of the present invention is composed primarily of an acrylic polymer. The film has an in-plane retardation of from 130 nm to 500 nm, inclusive, per 100 ?m thickness at a wavelength of 589 nm. The film has a total light transmittance of not less than 85%. The retardation film has a glass transition temperature of preferably from 110° C. to 200° C., inclusive. The acrylic polymer, which is the primary component, preferably has a lactone ring structure.