Nippon Shokubai Co., Ltd.

Hirofumi Shibata

Kazushi Torii

Yoshio Irie

Yorimichi Dairoku

Kazuki Kimura

Kozo Nogi

Yasuhiro Fujita

Sayaka Machida

Taku Iwamura

Masatoshi Nakamura

Kenji Tada

Kunihiko Ishizaki

Katsuyuki Wada

Satoshi Matsumoto

Shinichi Fujino

Koji Miyake

Yoshiro Mitsukami

Motohiro Imura

Yusuke Watanabe

Hiroko Ueda

Yasuhisa Nakashima

Reiko Nakatsuru

Koji Honda

Kenji Kadonaga

Hiroki Inoue

Makoto Nagasawa

From a view pint of decreasing an out of spec product after surface crosslinking, particularly, when an alkylene carbonate compound is used as a surface crosslinking agent, influence due to an air temperature is great, and it is necessary to reduce ethylene glycol which is produced as a byproduct. There is provided a process for producing a polyacrylic acid (salt)-based water absorbent resin powder, comprising storing a non-polymerized organic compound being a raw material (modified raw material) of a water absorbent resin powder in a heated state, thereafter, mixing the non-polymerized organic compound with other compound at a predetermined ratio and, further, mixing the mixture into a water absorbent resin powder.

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

From a view point of reduction in an out of spec product after surface crosslinking, particularly, when an alkylene carbonate compound is used as a surface crosslinking agent, influence by an air temperature is great, and it is necessary to reduce ethylene glycol which is produced as a byproduct, and there is provided a process for producing a polyacrylic acid (salt)-based water absorbent resin powder, comprising

A water absorbing agent of the present invention has an internal crosslinking structure obtained by polymerization of a water-soluble unsaturated monomer. The agent satisfies conditions (a) to (d): (a) the agent contains water-insoluble inorganic particles at an amount of from 10 ppm to 1,900 ppm inclusive; (b) the agent contains 5 mass % or less particles which have such a size that they can pass through a sieve having a mesh opening size of 150 &#x3bc;m; (c) the agent has an absorbency against a pressure of 4.83 kPa (AAP) of 18 g/g or more; and (d) the water-insoluble inorganic particles reside on a surface of the water absorbing resin or near the surface.

Water absorbing agent, water absorbent core using the agent, and manufacturing method for water absorbing agent

A water absorbing agent and a method for producing the water absorbing agent are disclosed. Water absorbent resin particles having an internal cross-linked structure obtained by polymerizing a water-soluble unsaturated monomer, organic acid, and water-soluble multivalent metal salt are mixed, so that it is possible to provide a water absorbing agent which suppresses permeation of metal components into the water absorbent resin particles and enables the metal components to evenly adhere to an entire surface of the water absorbent resin in a dot manner.

Water absorbing agent and production method thereof

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

According to the present invention, the manufacturing method for the water absorbing resin involves the step of polymerizing a water-soluble unsaturated monomer, 0.06 of 5 mol % of which is composed of an internal crosslinking agent; and the step of drying a water-containing gel which has a thermally decomposing radical initiator content index of 40 to 100 at 100 to 250&#xb0; C. The water absorbing resin of the present invention contains a water-soluble unsaturated monomer as a repeat unit for a major chain, 90 mol % of the monomer being composed of an acrylic acid and/or salt thereof, the resin having an internal crosslinking structure and exhibiting a weight-average molecular weight Mw of 360,000 to 1,000,000 daltons and an intrinsic viscosity IV of 2.1 to 6.0 dL/g where the weight-average molecular weight Mw and the intrinsic viscosity IV are measured after treatment under set 2 of hydrolysis conditions.

Water absorbing resin with improved internal structure and manufacturing method therefor

The present invention provides a method for manufacturing a particulate water-absorbing agent which has excellent liquid diffusibility and liquid permeability, and whose amount of residual monomers is reduced. The method for manufacturing the particulate water-absorbing agent of the present invention includes a step of surface-crosslinking, in the presence of an organic crosslinking agent, water-absorbing resin particles obtained through at least a step of polymerizing an aqueous solution of unsaturated monomers, and in or after the polymerizing step, a reaction system is mixed with peroxide. Thus, it is possible to obtain the particulate water-absorbing agent which has excellent liquid diffusibility and liquid permeability and whose amount of residual monomers is small, that is, it is possible to obtain the particulate water-absorbing agent which is highly functional and highly safe.

Method for manufacturing particulate water-absorbing agent and particulate water-absorbing agent

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

A method for disintegrating a hydrate polymer characterized by disintegrating a hydrate polymer having a solid content in the range of 50-70 wt. % with a screw extruder while supplying 0.1-30 parts by weight of water per 100 parts by weight of the polymer to the extruder. Since the product of disintegration is prevented from inducing mutual adhesion, it does not form masses of conglomeration when it is dried.

Method for disintegrating hydrate polymer and method for production of water-absorbent resin

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

There is disclosed a process to uniformly and rapidly carry out the mixing of a monomer liquid and a polymerization initiator and thus for the resulting polymer not to adhere to the inner surface of the piping or the inside of the apparatus in an art of producing a water-absorbent resin by continuously mixing the monomer liquid and the polymerization initiator together and thereby carrying out polymerization. This process comprises the steps of: (a) continuously supplying a monomer liquidto such as a supply pipeto continuously stir the monomer liquidin the supply pipewith such as a stirring apparatus; (b) causing a polymerization initiatorto join into a flow of the monomer liquidbeing in a stirred state, thereby obtaining a mixed liquidof the monomer liquidand the polymerization initiator; and (c) continuously supplying the mixed liquidfrom the supply pipe lineto a polymerization apparatus to cause the mixed liquidto run a polymerization reaction.

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Himeji, Japan

Hirofumi Shibata