Nippon Shokubai Co., Ltd.

Makoto Nagasawa

Hiroyuki Ikeuchi

Yorimichi Dairoku

Shinichi Fujino

Kunihiko Ishizaki

Yoshio Irie

Shigeru Sakamoto

Katsuyuki Wada

Hirotama Fujimaru

Yasuhiro Fujita

Kenji Tada

Ryoko Tahara

Kazushi Torii

Kazuhiko Sakamoto

Sayaka Machida

Masatoshi Nakamura

Hiroki Inoue

Toshimasa Kitayama

Hirofumi Shibata

Yasuhisa Nakashima

Kazuhisa Hitomi

Eri Nagasawa

Yoshiki Katada

Jiro Sano

The purpose of the present invention is to provide a process for stably and continuously producing a water-absorbing resin, specifically, a process for stably and continuously producing a water-absorbing resin, the process including a gas absorbing step in which a gas discharged from a step of producing a water-absorbing resin is efficiently and persistently absorbed. A main point of this process for producing a water-absorbing polyacrylic acid (salt) resin further including a step of absorbing a gas discharged from a production step of the water-absorbing polyacrylic acid (salt) resin in water having a pH of 7 to 11 and a polyvalent metal ion content of 100 ppm or less or a step of absorbing the gas in water having a pH of 7 to 11, the pH of the water having been adjusted by mixing a water having an electric conductivity of 500 (&#x3bc;S/cm) or less at 25&#xb0; C. with an alkali compound.

Process for producing water-absorbing polyacrylic acid (salt) resin

The present invention provides a method for producing a water absorbent resin particle, in high productivity, not only in a controlled manner of particle size but also enhancing fundamental property (absorption capacity or absorption capacity against pressure) of a water absorbent resin. A method for producing a water absorbent resin particle having the cross-linking polymerization step for an aqueous solution of an unsaturated monomer; the grain refining step for water-swellable, water-containing gel-like cross-linked polymer (a) obtained in the cross-linking polymerization step; the drying step for grain refined gel; and the crushing step for a dried substance, wherein, in the grain refining step for the water-swellable, water-containing gel-like cross-linked polymer (a), water-swellable, water-containing gel-like cross-linked polymer (b), having solid content or centrifuge retention capacity different from solid content or centrifuge retention capacity of the cross-linked polymer (a) by equal to or larger than 1%, is subjected to coexistence.

Method for producing water absorbent resin particle

To improve the heat retention by diapers and other absorbents, a heat retention indicator 1 of a water-absorbing resin which is defined in the present invention needs be 3.0&#xb0; C./min or less and also that particular requirements need be met to satisfy this condition. If the requirements are met, a water-absorbing resin, absorbent, and absorbent article can be provided which has a heat retention indicator 1 of 0 to 3.0&#xb0; C./min or less and which exhibits excellent heat retention and absorption.

Water-absorbing agent, manufacture method thereof, and absorbent and absorbent article made therefrom

An object of the present invention is to provide a particle-shaped water absorbing agent having a remarkably improved surface color and excellent water-absorbing properties (better water absorption capacity, and lower water soluble content and residual monomer content) at the same time. In order to attain the object, a particle-shaped water absorbing agent according to the present invention is a particle-shaped water absorbing agent whose main component is a polyacrylic acid and/or a salt thereof, the particle-shaped water absorbing agent having a surface color of Hunter b value in a range of &#x2212;5 to 10, and having a cross-linking absorption property index (CPI) in a range of 1 to 100, the CPI defined by the following two equations:=(+17)/Ln (water soluble content);&#x2003;&#x2003;Equation 1:=(/residual monomer content)&#xd7;100&#x2003;&#x2003;Equation 3:

Particle-shaped water absorbing agent and method for producing the same

The application relates to the particulate water absorbing agent of the present invention composed primarily of a polyacrylic acid- or polyacrylate-based water absorbing resin and containing a chelating agent and a phosphorous compound. Accordingly, the particulate water absorbing agent composed primarily of a water absorbing resin achieves both excellent water absorbing properties and anti-coloring effect which would normally be incompatible. A particulate water absorbing agent for absorbent core is provided that is suitable for actual use.

Particulate water absorbing agent and manufacturing method of same

A particulate water absorbing agent includes a polyacrylic acid and/or a salt thereof water absorbent resin as a main component, wherein the water absorbent resin includes &#x3b1;-hydroxycarboxylic acid and/or a salt thereof, and the absorbing agent satisfies a specific particle size distribution and a specific water absorbing performance, thereby solving the conventional problems. Further, a production method of the water absorbing agent is characterized in that &#x3b1;-hydroxycarboxylic acid and/or a salt thereof is added to (a) a monomer aqueous solution whose main component is acrylic acid and/or a salt thereof and which is being cross-linked and polymerized or (b) a hydrogel polymer after the polymerization. As a result, in the particulate water absorbing agent containing the water absorbent resin as a main component, it is possible to realize both excellent water absorbing performance and excellent coloring prevention effect. Further, it is possible to provide an absorbing article particulate water absorbing agent which is suitable for practical use.

Particulate water absorbing agent and production method thereof

An object of the present invention is to provide a method for producing a particulate water-absorbent polymer particle having remarkably improved long-term color stability, without an adverse effect (such as a delay in polymerization) on synthesis of the particulate water-absorbent polymer. The method includes the steps of polymerizing a monomer aqueous solution (B) containing (i) at least one type of monomer (A) that is capable of forming a particulate water-absorbent polymer by polymerization, (ii) at least one type of crosslinking agent, (iii) at least one type of polymerization initiator and (iv) an organophosphorus compound in an amount of not less than 1 but not more than 100 ppm by mass with respect to the monomer (A) so as to form a hydrogel polymer, and drying the hydrogel polymer. The method enables to provide an excellent particulate water-absorbent polymer that realizes (i) long-term color stability and improvement in urine tolerance and (ii) absorbing property, which are in such a trade-off relationship. In this way, the above object is attained.

Particulate water-absorbent polymer and production method thereof

The present invention relates to a method for continuous production of a water-absorbent resin by use of an continuous polymerization device having a charge part of a monomer aqueous solution; an endless belt on which the monomer and a hydropolymer formed are conveyed; and a discharge part of the hydropolymer, wherein the continuous polymerization device has side walls and a ceiling, and the space ratio in the device represented by the equation, 'space ratio in the device=B/A', is in the range of 1.2 to 20. In the equation, A is a maximum cross-sectional area (cm) of the hydropolymer during the polymerization in the width direction of the endless belt, and B is a maximum cross-sectional area (cm) of the space between the endless belt of the continuous polymerization device and the ceiling of the continuous polymerization device in the width direction of the endless belt.

Method for continuous production of water-absorbent resin

An object of the present invention is to make it possible, in order to form the fine powder of the water-absorbent resin into a water-absorbing material having particle diameters favorable for practical use, that a water-absorbing material which has high agglomeration strength and is excellent in the quality performances is obtained at a low cost with good efficiency without causing the problems of the adhesion to such as treatment apparatus. As a means of achieving this object, a process according to the present invention for production of a water-absorbing material is a process for production of a water-absorbing material from a fine powder of a water-absorbent resin wherein the water-absorbing material is a particulate water-absorbing material having particle diameters larger than the fine powder, with the process comprising: a step (a) of adding an aqueous liquid to the fine powder of the water-absorbent resin with such as a high-speed stirring type continuous extrusion mixerso that the overall average water content will be in the range of 20 to 60 weight %, whereby particles of the fine powder are agglomerated to thus obtain a particulate hydrous materialof the water-absorbent resin; and a step (b) of applying a mechanical compression force to the particulate hydrous materialand, at the same time, knead-pulverizing it, with such as a meat chopper apparatus, thereby obtaining particulate agglomeratesof the water-absorbing material.

Process for production of water-absorbing material

There is provided: a production process for a water-absorbing agent having stable properties in a short time; and a water-absorbing agent. The production process comprises the step of blending an acid-group-containing water-absorbent resin powder with a noncrosslinkable water-soluble inorganic base and/or an irreducible alkaline-metal-salt pH buffer and further with a dehydratable crosslinking agent reactable with the acid group, thereby subjecting the resin powder to crosslinking treatment, or comprises the step of blending an acid-group-containing water-absorbent resin powder with the above base and/or pH buffer and further with a crosslinking agent reactable with the acid group, thereby subjecting the resin powder to crosslinking treatment, wherein the resin powder has a weight-average particle diameter of 300 to 600 &#x3bc;m wherein the ratio of fine powders having particle diameters of not larger than 150 &#x3bc;m in the resin powder is not more than 10 weight %.

Water-absorbing agent and production process therefor, and sanitary material

The present invention provides: a production process for a particulate water-absorbent resin with high productivity, which production process is carried out in such a manner that the particulate water-absorbent resin will contain particles with particle diameters of 150 to 850 &#x3bc;m (but excluding 850 &#x3bc;m) in an amount of not smaller than 75 weight % of the particulate water-absorbent resin after the pulverization step or after the pulverization step and the drying step even if the adjustment of the particle diameters is not carried out by the sieving classification procedure; a novel particulate water-absorbent resin having high properties; and a sanitary material comprising this particulate water-absorbent resin. The production process for a particulate water-absorbent resin, according to the present invention, is carried out in such a manner that the particulate water-absorbent resin will contain particles with particle diameters of 150 to 850 &#x3bc;m (but excluding 850 &#x3bc;m) in an amount of not smaller than 75 weight % of the particulate water-absorbent resin after the pulverization step or after the pulverization step and the drying step; with the production process being characterized in that, in the pulverization step, a hydropolymer of a water-absorbent resin having a water content of 10 to 30 weight % is pulverized with a pulverizer.

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Himeji, Japan

Makoto Nagasawa