Nippon Shokubai Co., Ltd.

Nippon Shokubai Kagaku Kogyo Co., Ltd.

Other

Nippon Shokubai Kagaku Kabushiki Kaisha

Kenji Kadonaga

Masazumi Sasabe

Kinya Nagasuna

Kozo Nogi

Hirotama Fujimaru

Koji Miyake

Akiko Mitsuhashi

Kenji Minami

Kazutomo Takahashi

Tadao Shimomura

Motohiro Imura

Kazumasa Kimura

Seiji Kato

Shigeru Sakamoto

Sayaka Machida

Kazuki Kimura

Hiroki Inoue

Kenji Tada

Masuji Izubayashi

Takashi Namba

Yoshio Irie

Kazushi Torii

Yorimichi Dairoku

Satoshi Matsumoto

Shinichi Fujino

Taku Iwamura

Yoshihiko Masuda

Yusuke Watanabe

Shin-Ichi Fujino

Katsuhiko Sakamoto

Kazumasa Konishi

Taku Fujimoto

Kunihiko Ishizaki

Hiroshi Yamazaki

Makoto Matsumoto

Yoshifumi Adachi

Yoshiro Mitsukami

Hideyuki Tahara

Masatoshi Nakamura

Masatoshi Yoshida

Toshimasa Kitayama

Hiroko Ueda

Hirofumi Shibata

Ryota Wakabayashi

Koji Honda

Tsunemasa Ueno

Koichi Yonemura

Hiroko Okochi

Yohei Murakami

Atsushi Tachibana

Akira Hattori

Shigeru Oka

Yoshiki Katada

Kouichi Okamoto

The present invention addresses the problem of reducing the undried residue when recycling a fine powder of water-absorbing resin. The present invention is a method for producing a water-absorbing resin, wherein: a fine powder recycling step includes vi-1) a granulation step for obtaining a granulated gel, vi-2) a granulated gel addition step, and vi-3) a gel mixing step; the solids content of the granulated gel in the granulated gel addition step is 50-90% by mass; and the temperature of the granulated gel and the temperature of the water-containing gel-like crosslinked polymer is 50-100° C.

Method for producing water-absorbent resin

[Object] To provide a method for stably producing a water-absorbent resin in powder form or particle form, which has excellent physical properties such as water absorption performance and the like, without any production trouble. [Solution] A method for producing a water-absorbent resin includes mixing a monomer composition, which contains at least a monomer and a pyrolytic polymerization initiator, with an organic solvent, a temperature of the organic solvent is not lower than 70&#xb0; C. at time of mixing, and when a mass per unit time of the monomer in the monomer composition to be mixed with the organic solvent is expressed as an amount per unit volume of the organic solvent, a lower limit is 0.01 g/ml/min, and an upper limit is 0.2 g/ml/min.

A particulate water absorbent resin is obtained by polymerizing an unsaturated monomer so as to form a cross-linked polymer hydrogel and drying and pulverizing the cross-linked polymer hydrogel, and plural classification steps different from each other are carried out so as to remove fine powder. In this manner, the present invention provides the method for classification of particulate water absorbent resin which method allows particulate water absorbent resin having a desired particle diameter range to be efficiently obtained at low cost while securing the high productivity even in case where a larger production equipment is used.

Classification method of particulate water absorbent resin

The present invention relates to an absorbent suitable for use in a thin sanitary material/absorbent article having a high absorbent content and not prone to gel blocking, the absorbent having excellent liquid diffusibility (e.g. SFC) and minimal decrease in absorption ratio under pressure (e.g., AAP or PUP) even when a liquid permeation enhancer is added, and to a method for manufacturing the high-performance absorbent stably during actual production. The method is a method for manufacturing a polyacrylic acid (salt)-based absorbent, having a surface-crosslinking agent addition step for adding a solution of a surface-crosslinking agent, and a liquid permeation enhancer addition step for adding a liquid permeation enhancer, the liquid permeation enhancer addition step being performed after and/or at the same time as the surface-crosslinking agent addition step, the method characterized in that a surface crosslinking step for performing heat treatment in an atmosphere having a dew point of 45&#xb0; C. to 100&#xb0; C. is performed after or at the same time as the surface-crosslinking agent addition step.

Method for producing polyacrylic acid (salt)-based water absorbing agent, and water absorbing agent

The present invention is a method for producing a water absorbent resin which method is a method for producing surface cross-linked water absorbent resin particles, the method including the successive steps of: (a) adding a surface cross-linking agent and water to a particulate water absorbent resin in a mixer; and (b) reacting the resulting water absorbent resin mixture taken out from the mixer with the surface cross-linking agent in a reactor by heating or active energy ray irradiation, water vapor being used as part or all of the water added in the mixer. This makes it possible to provide a method for producing a water absorbent resin in which method a surface cross-linked water absorbent resin that has excellent properties can be obtained efficiently at low cost with high productivity.

Method for producing water absorbent resin

An object of the present invention is to provide a simple method for improving and stabilizing the physical properties (for example, liquid permeability) of a water absorbent resin, without requiring investment in expensive facilities or modification of raw materials. In particular, the object is to provide a method which is useful in the large-scale production of a water absorbent resin. The method for producing polyacrylic acid (salt)-based water absorbent resin of the present invention includes, in order, a step in which an acrylic acid (salt)-based monomer aqueous solution is polymerized, a step in which the water-containing gel-like crosslinked polymer obtained in the polymerization step is dried, a step in which the dried polymer obtained in the drying step is pulverized, and a classification step which takes place after the drying step or after the pulverizing step, wherein, at the time of providing the dried polymer to the roll mill used in the pulverizing step, the dried polymer is provided in a dispersed state in the axial direction of the roll of the roll mill.

Method for producing polyacrylic acid (salt)-based water absorbent resin

Aqueous liquid and moisture vapor are added to water absorbent resin powder so that particles of the water absorbent resin powder are bound. Supplying the aqueous liquid and moisture vapor to the water absorbent resin powder reduces the amount of particles that remain unbound (ungranulated) and increases the concentration of the water absorbent resin bound particles to provide improved drying efficiency and to obtain particulate water absorbent resin having excellent properties even when the bound particles are highly concentrated. The present invention provides (i) a method for binding water absorbent resin and (ii) a method for producing particulate water absorbent resin including the step of binding particles of water absorbent resin powder.

Binding method of water absorbent resin

An object of the present invention is to provide a waste solution solidifying agent which can solidify a waste solution, particularly, a waste solution containing blood or body fluid at a low cost, uniformly, and in a short time; in particular, to provide a waste solution solidifying agent which can solidify a waste solution uniformly and in a short time in a vertically oriented waste solution equipment. As a means of achieving this object, a waste solution solidifying agent of the present invention is a particulate treating agent used in a method of treating a waste solution which solidifies a waste solution into a gel by placing a treating agent in a waste solution, and is characterized in that said agent contains, as an essential component, a water-absorbent resin having a crosslinked structure obtained by polymerizing a water-soluble ethylenic unsaturated monomer and, when flowing-placed at once into a 0.90 mass % aqueous sodium chloride solution, 20 to 95 mass % of the agent is floated, and 80 to 5 mass % is settled. And a process for preparing a waste solution solidifying agent of the present invention is a process for preparing a particulate waste solution solidifying agent containing, as an essential component, a water-absorbent resin having a crosslinked structure obtained by polymerizing a water-soluble ethylenic unsaturated monomer, and comprises a step of mixing a hydrophobic substance having a methanol index of 20 or more after polymerization.

Waste solution solidifying agent, process for preparing the same and use of the same

A homogeneously surface cross-linked water absorbent resin and a method for the production thereof are provided. The water absorbent material is formed of a surface cross-linked water absorbent resin resulting from granular irregularly pulverized shaped surface cross-linking the product of partial neutralization or whole neutralization of a water absorbent resin having acrylic acid or a metal salt thereof as a main component, which water absorbent material shows a metal atom concentration on the surface of the water absorbent material in the range of 0-10% within 0 second of polishing and 2-35% at 10 seconds value of polishing as determined by subjecting the water absorbent material to Ar ion discharge polishing under a voltage of 500 &#x212b;. The surface cross-linked water absorbent resin to be used herein can be produced by surface cross-linking a water absorbent resin having a specific particle diameter with a surface cross-linking agent having a water concentration in a specific range.

Water absorbent material, method for production of surface cross-linked water absorbent resin, and method for evaluation of water absorbent material

The present invention provides: an absorbent structure and an absorbent article, which are excellent in both liquid diffusion ability and liquid storage ability, and which are excellent in the dry feeling and the amount of wet back of the aqueous liquid, and which can realize the thinning and lightening more; and a water-absorbent resin fitly usable for the above absorbent structure and absorbent article. The absorbent structure, according to the present invention, comprises a liquid-diffusing member and a water-absorbent resin, with the absorbent structure being characterized in that when the capillary absorption index of the liquid-diffusing member at a height of 40 cm is referred to as A (A&#x2267;0.10), the capillary absorption index B of the water-absorbent resin at a height of 40 cm satisfies the following equation: B/A&#x2267;0.7 (equation 1).

Absorbent structure, absorbent article, water-absorbent resin, and its production process and evaluation method

There are disclosed a water-absorbent resin composition and its production process, wherein the water-absorbent resin composition causes little gel-blocking and is excellent in the liquid permeability and liquid diffusibility and is high also in the absorption performances and further is strong also against the physical damage; and there are further disclosed a water-absorbent resin composition and its production process, wherein the water-absorbent resin composition has the following further advantages, in addition to the above, of involving little segregation of the metal compound and further having a dust prevention effect. One of water-absorbent resin compositions according to the present invention is a water-absorbent resin composition comprising water-absorbent resin particles obtained by polymerizing a monomer including acrylic acid and/or its salt, with the composition having a mass-average particle diameter of 100 to 600 &#x3bc;m and comprising water-soluble polyvalent metal salt particles and the water-absorbent resin particles that have been surface-crosslinked.

Water-absorbent resin composition and its production process

A method for surface crosslinking water-absorbing resin of the present invention includes a step (1) of obtaining a wet mixture, a step (2) of obtaining a dried particulate composition, and a step (3) of carrying out a surface crosslinking reaction. With this, since a processing time of each step becomes short, it is possible to mass produce the water-absorbing resin having excellent physical properties. Moreover, a method for manufacturing the water-absorbing resin of the present invention includes a modifying step and a cooling step. The modifying step and/or the cooling step are/is carried out by using stirring means including a rotation axis having a plurality of stirring boards, and the stirring means includes the stirring board having a specific thickness and/or a scraping blade having a specific shape. With this, it is possible to suppress the generation of the fine powder in the modifying step and/or the cooling step.

Method for surface crosslinking water-absorbing resin and method for manufacturing water-absorbing resin

A water-absorbing agent according to the present invention includes water-absorbent resin particles having an internal cross-linked structure, wherein a vicinity of a surface of the water-absorbent resin particle is cross-linked with a surface cross-linking agent, and the water-absorbent resin particle has therein a sea-island structure having (i) part containing a first water-soluble multivalent metal salt such as aluminum sulfate and (ii) part not containing the first water-soluble multivalent metal salt. With this arrangement, it is possible to provide a water-absorbing agent having less water-soluble component content, more excellent liquid permeability, and more excellent water retention under pressure than the conventional water-absorbing agent.

Water-absorbing agent and its production process

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Kakogawa, Japan

Kenji Kadonaga