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Water-absorbable polyacrylic acid (salt) resin and process for production thereof

A polyacrylate and manufacturing method technology, applied in absorbent pads, medical science, bandages, etc., can solve the problems of poor color of water-absorbent resin, reduced physical properties of water-absorbent resin, poor whiteness, etc., and achieve the effect of improving whiteness

Active Publication Date: 2011-04-13
NIPPON SHOKUBAI CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] That is, in order to prevent the coloring of the water-absorbing resin, when reducing the polymerization inhibitor or adding other anti-coloring agents to the monomer, although the coloring of the water-absorbing resin was improved to a certain extent (increased whiteness), it was found that the water-absorbing resin The physical properties of the permanent resin are lowered, or the stability of the monomer is lowered.
Especially in the case of industrial-scale polymerization (for example, 1Mt / hr), or in the case of starting polymerization at high temperature and high concentration polymerization, a small amount of gel will accumulate in the monomer tank and piping, and there will be formation due to regular cleaning. The problem of reduced productivity caused by the by-product gel, etc.
[0010] In addition, in recent years, for water-absorbent resins that are consumed and discarded in large quantities in diapers, etc., there are demands for non-fossil raw materials (natural products), sustainable (Sustainable) and renewable (Renewable) water-absorbent resins. trend, but the color (whiteness) of natural-based water-absorbent resin is poor
In addition, water-absorbent resins using acrylic acid (described later) obtained from natural products such as glycerin as a raw material have also been unexpectedly proposed, but it has been found that these, like acrylic acid, have poor whiteness.

Method used

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  • Water-absorbable polyacrylic acid (salt) resin and process for production thereof
  • Water-absorbable polyacrylic acid (salt) resin and process for production thereof
  • Water-absorbable polyacrylic acid (salt) resin and process for production thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0184] (Evaluation of physical properties)

[0185] (a) Initial coloring

[0186] The measurement was performed using a spectroscopic color difference meter SZ-Σ80 COLOR MEASURING SYSTEM manufactured by Nippon Denshoku Industries Co., Ltd. The setting conditions for the measurement are selective reflectance measurement, use the attached container for powder and paste with an inner diameter of 30mm and a height of 12mm, use the standard round white board No.2 for powder and paste as the standard, and use a 30Φ lighting tube. About 5 g of water-absorbent resin is filled into the prepared powder and paste containers.

[0187] (b) Coloring over time

[0188] After leaving the water absorbent resin under high temperature and high humidity, the color was measured by the method of (1) above.

[0189] (c) Other physical properties

[0190] According to the ERT of EDANA or the specification of US Patent Application Publication No. 2006 / 204755, the unloaded water absorption capacity...

manufacture example 1

[0192] Acrylic acid containing no phenol and hydroxyacetone and containing 60 mass ppm of p-methoxyphenol polymerization inhibitor was prepared by distillation and crystallization. The amount of dimer was adjusted to be 100 mass ppm or less, furfural and protopulsatin were adjusted to be 1 mass ppm or less respectively, and the total amount of acetic acid and propionic acid was adjusted to 500 mass ppm (among which acetic acid was 400 ppm).

[0193] Moreover, 75 mol% of neutralization was performed by adding the said acrylic acid to the NaOH aqueous solution obtained from the sodium hydroxide containing 0.2 mass ppm of iron under cooling (liquid temperature 35 degreeC). Since acrylic acid and iron in water were below the detection limit, the amount of Fe in the monomer was calculated to be about 0.07 mass ppm.

Embodiment A

[0195] By dissolving 0.05 mol % of polyethylene glycol diacrylate (relative to monomer ) to obtain the monomer (1). 350 g of the monomer (1) was added to a cylindrical container with a volume of 1 L, and nitrogen gas was bubbled at 2 L / min to deaerate for 20 minutes. Next, an aqueous solution of 0.12 g / mol (with respect to the monomer) of sodium persulfate and 0.005 g / mol (with respect to the monomer) of L-ascorbic acid was added while stirring with a stirring bar, and polymerization was started. Stirring was stopped after the start of polymerization, and static aqueous solution polymerization was performed. The temperature of the monomer (1) showed a peak polymerization temperature of 108° C. after about 15 minutes (polymerization peak time), and then it was allowed to carry out polymerization for 30 minutes. Thereafter, it was taken out from the polymerization vessel to obtain a hydrogel-like crosslinked polymer (1).

[0196] The obtained water-containing gel-like crossli...

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Abstract

The object aims to provide a water-absorbable resin which is prevented from the occurrence of gelatinization of a monomer before polymerization, hardly causes discoloration over time, has a remarkably improved surface color, and also has excellent absorption properties. For achieving the object, provided is a process for producing a water-absorbable polyacrylic acid resin, which comprises: a step of preparing a monomer by using acrylic acid having a hydroxyacetone content of 300 ppm by mass or less; a polymerization step of polymerizing the monomer to produce a hydrogel; and a drying step of drying the hydrogel. Also provided is a process for producing a water-absorbable polyacrylic acid resin, which comprises: a step of preparing a monomer by using acrylic acid; a step of polymerizing the monomer in the presence of phenol to produce a hydrogel; and a drying step of drying the hydrogel.

Description

technical field [0001] The present invention relates to a polyacrylic acid (salt)-based water-absorbing resin and a manufacturing method thereof. More specifically, the present invention relates to a water-absorbent resin that is substantially white and has excellent stability during polymerization, and a method for producing the same. Background technique [0002] Water-absorbent resin (SAP / Super Absorbent Polymer) is a water-swellable and water-insoluble polymer gelling agent, which is mainly used for absorbent articles such as diapers and sanitary napkins, and then used as a humectant for agriculture and gardening , industrial water-stop materials, etc., are mainly used for one-time use. As such water-absorbent resins, a variety of monomers and hydrophilic polymers have been proposed as raw materials. In particular, polyacrylic acid (salt)-based water-absorbent resins using acrylic acid and / or salts thereof as monomers have been proposed. It has good water absorption pe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F2/44A61F13/49A61F13/53C08F6/00C08K3/00C08K5/05C08K5/09C08L33/02
CPCC08J3/128A61L15/60C08F6/10C08F6/008C08J3/245C08J3/126C08F220/06A61L15/22A61F2013/530481C08J2333/02C08L33/02
Inventor 藤野真一长泽江利石崎邦彦春日洋人
Owner NIPPON SHOKUBAI CO LTD
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