摘要:
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-crosslinldng 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°C or more (when defined with respect to the gas temperature at the exit).
摘要:
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 µm and not less, than 106 µm are contained, and a weight average particle diameter of the particles is less than 500 µm and not less than 300 µ m and a logarith mic standard deviation (σξ) 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 superiror absorbent property in terms of an absorbency and a diffusing absorbency under pressure.
摘要:
Provided is a convenient, safe, and highly precise method for measuring a content of a water-absorbing resin in a hygienic material or an absorbent article. In a method for measuring a content of a water-absorbing resin, which has a water-soluble cation in the form of an ion-dissociating group, included in a hygienic material, an absorbent article, or an intermediate product in a manufacturing process thereof, A) a step for measuring an amount of a predetermined water-soluble cation in a reference sample including a known amount of the water-absorbing resin and creating a calibration curve indicating a relation between the amount of the water-absorbing resin and the amount of the predetermined water-soluble cation in the reference sample on the basis of the obtained measurement result; B) a step for measuring an amount of the predetermined water-soluble cation in a measurement sample, which includes a portion including the water-absorbing resin, of the hygienic material, the absorbent article, or the intermediate product in the manufacturing process thereof; and C) a step for calculating an amount of the water-absorbing resin in the measurement sample by the calibration curve created in the step A) from the amount of the predetermined water-soluble cation measured in the step B) are performed. The step A) and the step B) include measuring the amount of the predetermined water-soluble cation using an ion selective electrode method and include the following steps M1) and M2): M1) a step for immersing a sample in an aqueous solution including a total ionic strength adjusting agent (pre-processing step); and M2) a step for measuring the amount of the predetermined water-soluble cation in a pre-processed supernatant liquid obtained in the step M1).
摘要:
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 µm to 150 µm 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.
摘要:
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 µm and not less, than 106 µm are contained, and a weight average particle diameter of the particles is less than 500 µm and not less than 300 µ m and a logarith mic standard deviation (σξ) 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 superiror absorbent property in terms of an absorbency and a diffusing absorbency under pressure.
摘要:
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 an organic 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 106µm and 850µm, with respect to the particulate water absorbent.
摘要:
Provided is a particulate water absorbent with which an absorbent body having an excellent speed of incorporating liquid and enabling reduction in release amount can be produced. The particulate water absorbent contains poly(meth)acrylic acid (salt)-based water-absorbing resin particles as a main component, and the particulate water absorbent includes a cavity that is a space connecting to outside and a void that is a closed space not connecting to outside, in which a cavity ratio to a total volume is 10% by volume or more, and a void ratio to a total volume is 0.5% by volume or less.
摘要:
It is an object of the present invention to provide a novel water-absorbing sheet that can meaningfully reduce the return amount even when introduction of a liquid occurs intermittently for several times (particularly, three or more times) under a situation with no load, and the amount of introduction of the liquid becomes large. Disclosed is a water-absorbing sheet having a first base material, a second base material, and a water-absorbing layer positioned between the first base material and the second base material, wherein the first base material is a water-permeable sheet positioned on a side where a liquid to be absorbed is introduced, the water-absorbing layer has a first particulate water absorbent localized on a side of asurfaceof the firstbase material, the surface being arranged to face the second base material; and a second particulate water absorbent localized on a side of a surface of the second base material, the surface being arranged to face the first base material, an overall absorption amount of the second particulate water absorbent as represented by the following formula: CRC g / g + 0.44 × AAP 2.1 kPa g / g is 48 g/g or more, and a water absorption time determined according to a vortex method is 35 seconds or more.