Nippon Shokubai Co., Ltd.

Takahiro Kitano

Katsuyuki Wada

Kozo Nogi

Hiroyuki Ikeuchi

Yoshifumi Adachi

Kunihiko Ishizaki

Kazushi Torii

Yorimichi Dairoku

Hirotama Fujimaru

Taku Iwamura

Motohiro Imura

Sumio Okuda

Yoshitaka Ikeuchi

Manabu Ueda

Shinichi Fujino

Koji Miyake

Sayaka Machida

Kazuki Kimura

Hiroko Ueda

Taishi Kobayashi

Daisuke Takagi

Hidenori Wada

Taku Fujimoto

Takaaki Kawano

Mariko Tamaki

Hiroki Kawada

Tatsushi Hirauchi

Yasuhisa Nakajima

Hiroyuki Goto

Yuichiro Horimoto

Mai Wada

Ryuichi Hiraoka

Kazushi Horie

Yuika Noda

The purpose of the present invention is to provide a particulate water absorbing agent having both a high water absorption multiplying factor and a high water absorption rate and a method for manufacturing the same. The present invention is a particulate water absorbing agent for which CRC is 30 to 50 g/g, wherein the weight average particulate diameter (D50) is 200-600 &#x3bc;m, and the DRC index given by the following formula is a specific value (for example, 43, 30, or 20) or less: DRC index=(49&#x2212;DRC5min [g/g])/(D50 [&#x3bc;m]/1000).

Particulate water absorbing agent

A water absorbent resin (water absorbing agent) and method for producing it are provided which improve, in a water absorbent article (in particular, a diaper) including a water absorbent resin as a water absorbing agent, the absolute absorption amount (g), liquid absorbing times (in particular, liquid absorbing times at the second instance and later), re-wet (g), and diffusion distance (%) of the water absorbent article. A particulate water absorbing agent of the present invention has a CRC, a proportion of particles with sizes of 600 &#x3bc;m to 150 &#x3bc;m as defined through a standard-sieve classification, an SST, and the value of the difference between an FST and the SST each within a predetermined range.

Particulate water absorbing agent and water absorbent article

Particulate water absorbing agent and method for manufacturing same

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

Disclosed is a method for producing a water absorbent resin, by which a surface-crosslinked water absorbent resin having excellent physical properties can be efficiently obtained at low cost, while assuring high productivity. When the production scale is increased to a continuous production at 1 t/hr or more, the physical properties are improved and stabilized (for example, standard deviation of the physical properties is reduced) by a surface-crosslinking treatment, and the absorption against pressure (AAP) and liquid permeability (SFC) are further improved. Specifically disclosed is a method for producing a water absorbent resin, which is characterized in that the stirring shaft of the continuous mixing apparatus for the surface-crosslinking agent is heated during the mixing step of the surface-crosslinking agent or that the continuous mixing apparatus for the surface-crosslinking agent is operated at a pressure that is reduced relative to the ambient pressure and a gas flow is passed through the mixing apparatus during the mixing of the surface-crosslinking agent so that the gas flow in the mixing apparatus is 40&#xb0; C. or more (when defined with respect to the gas temperature at the exit).

Polyacrylic acid (salt)-type water absorbent resin and method for producing of same

A particulate water-absorbent agent containing a polyacrylate salt-type water-absorbent resin. The agent has an absorption capacity without load of 28 g/g or higher and has a diffusion absorption index of 1.40 to 10.0 g/g min. The amount of water-soluble components in the agent, with stirring, is 15-60% by mass. The difference between this amount and the amount of water-soluble components, without stirring, is 15-50% by mass. Also disclosed is a method of making the above-identified agent.

Particular water-absorbent agent 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.

A method of producing a particle-shape water-absorbing resin material is realized. With this method, it is possible to prevent deterioration of properties of the particle-shape water-absorbing resin material, and reduces damages onto surfaces thereof. This method is arranged such that (a) water-absorbing resin particles are surface-treated by using a crossing agent so that surfaces of the particles are cross-linked, (b) an additive for giving a function to the particles is added to the particles, (c) and a step of mixing the particles and the additive is carried out in a step of performing particle-size regulating treatment for the particles which includes agglomerated particles.

Method of producing particle-shape water-absorbing resin material

The production method of a water absorbent resin composition including a particulate water absorbent resin, wherein: 95 wt % or more of particles whose particle diameter is less than 850 &#x3bc;m and not less, than 106 &#x3bc;m are contained, and a weight average particle diameter of the particles is less than 500 &#x3bc;m and not less than 300 &#x3bc;m and a logarithmic standard deviation (&#x3c3;&#x3be;) of a particle size distribution is 0.45 or less, and a water-soluble component of the water absorbent composition is 35 wt % or less, and a multivalent metal component is contained, and an extraction rate of the multivalent metal component is 5.0 wt % or more and less than 100 wt %, thereby providing the water absorbent resin composition, free from any coagulation of particles in high humidity, which has superior absorbent property in terms of an absorbency and a diffusing absorbency under pressure.

Water absorbent resin composition and production method thereof

The present invention provides a particulate water absorbing agent for a thin type absorbing substrate suitable for actual use. A particulate water absorbing agent having irregularly pulverized shape, characterized by comprising, a surface crosslinked water-absorbing resin obtained by crosslinking polymerization of an unsaturated monomer with an acid group and/or salts thereof, which absorbing agent contains agglomerated particles therein and further satisfies (i) centrifuge retention capacity (CRC) in a physiological saline solution of not lower than 32 g/g, (ii) mass median particle size (D50) of 200 to 400 &#x3bc;m, and (iii) particles smaller than 600 &#x3bc;m and not smaller than 150 &#x3bc;m of 95 to 100% by weight. By using the particulate water absorbing agent, such absorbing articles can be obtained as have few rugged surface after water absorption, excellent liquid permeation property.

Particulate water absorbing agent with irregularly pulverized shape

A particulate water absorbent contains a water absorbent resin as a main component, the water absorbent resin being a crosslinked polymer of a water-soluble unsaturated monomer. The water absorbent resin is particular in shape and contains particles of a particle size in a range of not less than 106 &#x3bc;m and less than 850 &#x3bc;m in an amount of not less than 90 mass percent with respect to the total mass of the water absorbent resin contained in the particulate water absorbent. The particulate water absorbent has a first salt concentration absorption index of not less than 0.60 as measured by a formula below when ion exchange water is used as an aqueous solution of a constant salt concentration: (salt concentration absorption index)=(absorbency against a pressure of 4.83 kPa with respect to the aqueous solution of a constant salt concentration)/(absorbency against no pressure with respect to the aqueous solution of a constant salt concentration).

Particulate water absorbent containing water absorbent resin as a main component

The particulate water absorbent has a cross-linking structure therein, and contains (i) a particulate water absorbent resin having a cross-linking structure on a surface therof and (ii) not less than 0.001 mass % and less than 10 mass % of anorganic acid multivalent metal salt whose molecule contains not less than seven carbon atoms. Futher, the particulate water absorbent contains 90 mass % of particles, whose particle diameter is not less than 106 &#x3bc;m and 850 &#x3bc;m, with respect to the particulate water absorbent.

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Himeji, Japan

Takahiro Kitano