Nippon Shokubai Co., Ltd.

Other

Hirotama Fujimaru

Kunihiko Ishizaki

Kenji Kadonaga

Kinya Nagasuna

Nobuyuki Harada

Masazumi Sasabe

Kazutomo Takahashi

Katsuyuki Wada

Kozo Nogi

Sei Nakahara

Hiroyuki Ikeuchi

Yoshifumi Adachi

Hiroki Inoue

Kenji Minami

Masuji Izubayashi

Koichi Yonemura

Akiko Mitsuhashi

Kazuhiko Sakamoto

Yorimichi Dairoku

Katsuhiro Kajikawa

Takahiro Kitano

Makoto Nagasawa

Toru Nishioka

Ryoko Tahara

Hiroshi Yamazaki

Kazushi Torii

Shigeru Sakamoto

Kazuki Kimura

Motohiro Imura

Masatoshi Nakamura

Masatoshi Yoshida

Hiroko Ueda

Toshimasa Kitayama

Shin-Ichi Fujino

Yasuhisa Nakashima

Katsuhiko Sakamoto

Teruyuki Kanto

Toru Yanase

Takaaki Kawano

Atsushi Motoyama

Eri Nagasawa

Eri Goto

Naoko Ikushima

Kazuki; Kimura

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

An embodiment of the present invention allows for the production, with a high productivity, of a water-absorbent resin having an improved relationship between absorption capacity and water-soluble polymer, which are conflicting properties of the water-absorbent resin, being easily controlled for polymerization reaction, being of no odor, being less colored, and being of high absorption properties (high absorption capacity under load and high PPUP). In one embodiment of the present invention, a process for producing a water-absorbent resin by polymerizing an acrylic acid composition including acrylic acid and/or its salt, the process includes: (a) the step of carrying out radical polymerization of the acrylic acid composition to form a hydrogel crosslinked polymer; and (b) the step of drying the hydrogel crosslinked polymer by application of heat, the acrylic acid composition having an unpolymerizable organic compound content of 1 to 1000 ppm by weight, wherein the unpolymerizable organic compound has a solubility parameter of (1.0 to 2.5)&#xd7;10(Jm).

Polyacrylic acid (salt) water-absorbent resin, production process thereof, and acrylic acid used in polymerization for production of water-absorbent resin

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

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

An embodiment of the present invention allows for production, with a high productivity, of a water-absorbent resin including an improved relationship between absorption capacity and water-soluble polymer which are conflicting properties of the water-absorbent resin, being easily controlled for polymerization reaction, being of no odor, being less colored, and being of high absorption properties. In one embodiment of the present invention, acrylic acid composition is neutralized with a basic composition including an iron content of 0.2 to 5 ppm by weight (relative to a basic compound exclusive of a solvent); and then polymerizing a resultant neutralized product, the acrylic acid composition including: (i) a methoxyphenol content of 10 to 200 ppm by weight relative to the weight of acrylic acid; and (ii) at least one compound content of which is 0 to 10 ppm by weight relative to the weight of acrylic acid, the compound being selected from the group consisting of protoanemonin and furfural.

Production process of polyacrylic acid (salt) water-absorbent resin

A method of producing a water-absorbent resin of the present invention reduces amounts of a residual cross-linking agent and a residual surfactant, achieves high productivity, and improves physical properties of the resultant water-absorbent, such as absorption capacity, extractable polymer content, powder friction, and gel crushability. The method includes the steps of: polymerizing an aqueous monomer solution containing as a major component an acrylic acid monomer in the presence of a cross-linking agent; and drying the resultant polymer by heating, in which the cross-linking agent is a multifunctional (meth)acrylate cross-linking agent having polyethylene glycol structural units including a total of 6 to 200 ethylene oxide repeating units, and the aqueous monomer solution includes a mono(meth)acrylate compound having polyethylene glycol structural units in an amount of 0.1 to 30% by weight relative to an amount of the multifunctional (meth)acrylate cross-linking agent.

Method of producing polyacrylic acid (salt) water-absorbent resin

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 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.

A water-absorbent resin composition excelling in an absorption capacity under pressure, a first transition of initial absorption, and the small amount of rewet is provided. It comprises a water-absorbent resin obtained by aqueous solution polymerization and by reversed-phase suspension or reversed-phase emulsion polymerization and shows a CSF of not less than 20 g/g or an AAP of not less than 20 g/g or an SFC of not less than 10 (unit: 10&#xd7;cm&#xd7;s&#xd7;g). The gaps among resin particles owing to the difference in shape form optimum gap widths for the sake of capillarity. The resin composition consequently formed, therefore, manifests such excellent properties without the influences of a surfactant or an emulsifier.

Water-absorbent resin composition

In order to produce inexpensively with high productivity a water-absorbent resin of which: the residual monomer content and the water-extractable content are both low, and the properties are high, and the colorability is low; there is provided a process for producing a water-absorbent resin, which is a process for producing a crosslinked water-absorbent resin by polymerizing a monomer component including acrylic acid and/or its salt in a major proportion wherein the acrylic acid is a product obtained by catalytic gas phase oxidation of propylene and/or propane, with the process being characterized by comprising the steps of: preparing the monomer component from an acrylic acid composition that includes the unneutralized acrylic acid and a methoxyphenol and has a methoxyphenol content of 10 to 160 ppm by weight (based on the unneutralized acrylic acid); and then carrying out radical and/or ultraviolet polymerization of the resultant monomer component.

Acrylic acid composition and its production process, and process for producing water-absorbent resin using this acrylic acid composition, and water-absorbent resin

A method for producing a porous material excelling in stability of preservation is produced. A method for the production of a porous material comprising a step for obtaining a porous polymer by polymerizing an HIPE containing a polymerizable monomer is disclosed, which method comprises a step for adding a compound capable of reacting with a polymerization initiator and/or a compound capable of reacting with an unsaturated double bond to said emulsion, said porous polymer and/or said porous material having a conversion of not less than 70%. According to this invention, it is made possible to produce a porous material excelling in stability in storage and to decrease the polymerization initiator and the residual monomer very simply.

Method for production of porous material

A method of production is provided which is capable of efficiently producing in a very short period of time a porous polymer possessing a uniform foam structure and truly excelling in absorption properties and physical properties. It is a method for the production of a porous polymer, characterized by comprising (a) an emulsifying step for forming a water-in-oil type high internal phase emulsion (HIPE) by mixing and stirring an oil phase containing a polymerizing monomer component and a surfactant as essential components, (b) a shaping step for shaping the HIPE in a specific form, and (c) a polymerizing step for polymerizing the shaped HIPE and controlling the temperatures of the emulsion at the component steps (a)-(c) so that they may not produce a change exceeding 10&deg; C. or controlling all the component steps so that they may proceed at temperatures of not lower than 80&deg; C.

Process for producing porous polymer

A method for the production of a porous cross-linked polymer material by the polymerization of an HIPE containing a cross-linking agent, characterized by the fact at least one species of the cross-linking agent is a compound having a double bond equivalent f not less than 120 g/mol. The cross-linking agent is preferred to be a compound possessed of an alkylene oxide moiety or a vinyl polymer containing not less than two polymerizing double bonds in the molecular unit. Thus, it is made possible to produce a porous cross-linked polymer material excellent in absorbency and flexibility, permit the HIPE to be polymerized in a short time, and therefore improve the efficiency of production.

Method for production of porous cross-linked polymer material

A surface-modified water-absorbent resin powder is produced continuously with high productivity in a state where the particle diameter distribution is narrow and where the properties are high by a process comprising a polymerizing step, a drying step, a pulverizing step, a classifying step, and a surface-modifying step, and further, conveying steps of connecting them, wherein the conveying steps include at least two hoppers for storing the water-absorbent resin powder. A powder surface detector used favorably for this process includes a float hung down by a hanging line.

Continuous production process for water-absorbent resin powder and powder surface detector used therefor

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Himeji, Japan

Hirotama Fujimaru