Nippon Shokubai Co., Ltd.

Nippon Shokubai Kagaku Kogyo Co., Ltd.

Nippon Shokubai Kagaku, Co., Ltd.

Yorimichi Dairoku

Kunihiko Ishizaki

Yoshio Irie

Shinichi Fujino

Yasuhiro Fujita

Kozo Nogi

Nobuyuki Harada

Kinya Nagasuna

Hirofumi Shibata

Takumi Hatsuda

Yoshifumi Adachi

Yoshiro Mitsukami

Yoshihiko Masuda

Kenji Tada

Yoshihiro Motono

Makoto Nagasawa

Kazuhisa Hitomi

Takashi Azumi

Katsuyuki Wada

Shigeru Sakamoto

Koji Miyake

Katsuhiro Kajikawa

Masazumi Sasabe

Motohiro Imura

Hiroki Inoue

Toshimasa Kitayama

Sumio Okuda

Toshihiro Takaai

Soichi Yamada

Kazushi Torii

Satoshi Matsumoto

Kenji Kadonaga

Hirotama Fujimaru

Sayaka Machida

Taku Iwamura

Hideyuki Tahara

Shin-Ichi Fujino

Teruaki Fujiwara

Takahiro Kitano

Koji Matsumoto

Akito Yano

Shobu Shioji

Makoto Matsumoto

Hiroyuki Ikeuchi

Kazuki Kimura

Yasuhisa Nakashima

Kazumasa Konishi

Syuji Kanzaki

Seiji Kato

Teruyuki Kanto

Toru Yanase

Hiroko Okochi

Noriaki Mizutani

Kazutaka Yano

Shuji Kanzaki

Takanori Murakami

Yoshihiro Kita

Hirotama Lionsmansion Himejinishishikama 902 Fujimaru

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

A water-absorbing resin composition including 100 parts by weight of water-absorbing resin particles and 0.01 to 1 part by weight of additive particles, wherein a percent by weight of the additive particles, (x [%]), based on 100% by weight of the water-absorbing resin particles in the composition, and weight ratio of free additive particles, (y), relative to the percent by weight, (x [%]), satisfy the following formula:0.04()0.2().

Production method for water-absorbing resin composition

A production of a water-absorbent resin by which a particle diameter of the water-absorbent resin can be controlled simply and conveniently, and a content of fine powder can be decreased, without necessity of change of raw materials or expensive facility investment is to be provided. The method is a continuous production method of a polyacrylic acid (salt)-based water-absorbent resin, comprising a polymerization step of an aqueous solution containing acrylic acid (salt), a drying step of the resultant hydrogel-like polymer, a pulverization step of the dried substance, a classification step of the pulverized substance, and optionally a surface cross-linking step of the classified substance, wherein (a) the drying step and the pulverization step are connected via a storage step and a transportation step; and (b) a time of holding the dried substance from a time of completing the drying step to a time of starting the pulverization step is set at 3 minutes or longer.

Method for producing particulate water-absorbent resin

A production method for a water-absorbent resin, comprising a polymerization step for obtaining hydrogel by subjecting a monomer aqueous solution to a polymerization reaction, and a drying step for drying the hydrogel, wherein drying in the drying step is performed using a continuous through-flow belt-type drying machine, the solid content of the hydrogel supplied to the drying step is 35% by weight or more, and thickness variation rate (1) represented by the following EXPRESSION 1 of the hydrogel loaded onto through-flow belt in the continuous through-flow belt, is 1.05 to 5:[MATH. 1]Thickness variation rate (1)=(Maximum thickness of hydrogel in a width direction of the through-flow belt)/(Average thickness of hydrogel in a width direction of the through-flow belt).&#x2003;&#x2003;[EXPRESSION 1]

Production method for water-absorbent resin

A particulate water retaining material for cultivating plant comprising (A) a carboxyl group-containing water-insoluble water absorbent resin and (B) a polyvalent metal compound, by having the compound (B) deposited on the rerin (A), it is made possible to possess an outstanding water absorbing property without impairing the growth of a plant.

Particulate water retaining material for cultivating plant having water absorbent resin as main component

The present invention provides a method for being capable of sufficiently exerting property improvement effect by the addition of additive particles other than water-absorbing resin to water-absorbing resin particles. The problems can be solved by using additive particles having over cohesive particles in an amount equal to or less than a predetermined amount, or by using the additive particles by crushing or classifying in advance, before mixing with water-absorbing resin particles. Alternatively, the problem can be solved by subjecting a mixture of the water-absorbing resin particles and the additive particles to pneumatic transportation processing, in particular, in a heated state, after mixing or at the same time as mixing. Further, the present invention provides a water-absorbing resin composition, which is capable of stably exerting high-level property. The problems can be solved by a water-absorbing resin composition, where the addition amount of additive particles and amount of free additive particles satisfies a predetermined relation.

The present invention provides a production process by which a water-absorbent resin of excellent quality can be obtained at a low cost by reasonable steps in aqueous solution polymerization. The process for producing a water-absorbent resin comprises the step of polymerizing an aqueous solution of water-absorbent resin-forming monomers including acrylic acid and/or its sodium salt as major components, wherein: (1) the aqueous solution has a monomer component concentration of not less than 45 weight %; (2) the polymerization is carried out while water is evaporated so that the ratio (concentration ratio) between a solid component concentration in a hydropolymer as formed by the polymerization and a solid component concentration in the aqueous monomer solution will not be less than 1.10; and (3) the solid component concentration in the hydropolymer as formed by the polymerization is not more than 80 weight %.

Water-absorbent resin, hydropolymer, process for producing them, and uses of them

A production method of a water-absorbent resin includes the steps of: obtaining a hydrogel by supplying monomer liquid to a reaction device so that the monomer liquid is polymerized; and detaching the hydrogel from the reaction device, wherein the reaction device's surface in contact with the monomer liquid at a position where polymerization occurs is made of a fluororesin having a melt viscosity of less than 1&#xd7;10poise at 380&#xb0; C. On this account, it is possible to obtain a water-absorbent resin having less amounts of an extractable content with high productivity and it is possible to carry out continuous production for an extended period of time.

Production method of water-absorbent resin

An object of the present invention is to provide a water absorbent having excellent gel properties and showing excellent properties when used in a water-absorbing material of a sanitary/hygienic material such as paper diaper. Moreover, another object of the present invention is to provide a water absorbent which is safe and excellent in liquid permeability, and in which an amount of liquid permeability improver for improving the liquid permeability is reduced. The water absorbent is made from a water-absorbing resin prepared by a specific polymerization method and having a high degree of cross-linking, a high liquid holding property and a high gel strength (its swelling pressure of gel layer of is 35 kdyne/cm2 or more). This water absorbent is further processed to have a particular particle size distribution (95 wt % or more of its particles are less than 850&fnof;&#xca;m but not less than 106&fnof;&#xca;m, and logarithmic standard deviation (&fnof;&Dstrok;&fnof;&#xc4;) is in a range of 0.25 to 0.45) and then surface cross-linked. After that, a liquid permeability improver is added therein.

Water absorbent and producing method of same

As a characteristic that had not been known conventionally at all, 'permeability potential under pressure (PPUP)' of a particulate water absorbing agent is regulated, and further, 'range of particle size distribution' and &#x201c;coloring&#x201d; are concomitantly regulated. The present invention is directed to a particulate water absorbing agent having the following (a) to (c):

Particulate water absorbing agent including polyacrylic acid (polyacrylate) based water absorbing resin as a principal component, method for production thereof, water-absorbent core and absorbing article in which the particulate water absorbing agent is used

A method for the production of a water-absorbing resin is to be provided which permits enhancement and stabilization of property, for example, liquid permeability, of a water-absorbing resin by a simple and convenient method without requiring change of raw materials or expensive facility investment. The method comprises a polymerization step for polymerizing an aqueous solution of acrylic acid (or salt thereof) to obtain a hydrogel cross-linked polymer; a drying step for drying the hydrogel cross-linked polymer to obtain a water-absorbing resin powder; a classification step for classifying the water-absorbing resin powder; and a surface cross-linking step for surface cross-linking the water-absorbing resin powder before or after the classification step, wherein electricity is eliminated in the classification step.

Production method and method for enhancing liquid permeability of water-absorbing resin

An apparatus () includes a neutralization tank (), a pump (), a heat exchanger (), a line mixer (), a polymerizer (), a first pipe (), a second pipe (), a third pipe (), a fourth pipe (), and a fifth pipe (). Continuously supplied into the neutralization tank () are a monomer aqueous solution and a basic aqueous solution, so as to prepare a mixture solution. The mixture solution is circulated through the first pipe (), the pump (), the second pipe (), the heat exchanger (), and the third pipe (). The mixture solution is supplied to the polymerizer through the fourth pipe (). The apparatus () satisfies a requirement that a value X is not more than 200, which value X is found according to the following expression: 'X=(V/F)&#xb7;A', wherein V is a volume of the mixture solution present in a neutralization system, F is a flow volume of the mixture solution to be supplied to a polymerization system, and A is a contact area of the mixture solution present in the neutralization system with a device(s) and a pipe(s) constituting the neutralization system. With this arrangement, it is possible to provide a water absorbent resin having superior whiteness.

Production method and production apparatus of particulate water absorbing agent containing water absorbent resin as main component

A water absorbent resin is dried in a continuous fluidized bed having a heat transfer tube and at least two drying rooms. Pulverization is performed between a first drying room at not less than 80&#xb0; C. to not more than 200&#xb0; C. and a second or subsequent room at not less than 100&#xb0; C. to not more than 220&#xb0; C. A method for producing a water absorbent resin includes: (1) polymerizing a monomer aqueous solution; (2) drying a hydrogel polymer of step (1); (3) performing particle size control of the dry polymer of the step (2); (5) surface crosslinking the water absorbent resin powder of step (3), and step (4) of performing a second heat drying on the water absorbent resin powder of step (3), preceding step (5). The water absorbent resin has a moisture content of 0 wt % to 3 wt % before the step (5).

Process for producing water-absorbing resin

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

The subject invention provides a hydrophilic polymer (water-absorbing resin) which is superior in performance and productivity. According to the production method of the present invention, a hydrophilichigh-molecular-weight compound is dispersed in an aqueous solution containing a hydrophilic monomer. The dispersed hydrophilic high-molecular-weight compound is dissolved by heat of neutralization (heat of hydration) and/or heat of polymerization generated in the process of producing a hydrophilic polymer.

Production method for hydrophilic polymer

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Himeji, Japan

Yorimichi Dairoku