Production method for water-absorbing resin powder, and production device for same

Abstract

This production method includes: a gel pulverization step in which a hydrous gel-like crosslinked polymer is pulverized to obtain a particulate hydrous gel-like crosslinked polymer; a heating and drying step in which a continuous agitation dryer is used to obtain a granular dried substance from the particulate hydrous gel-like crosslinked polymer; a post-crosslinking step in which the particulatehydrous gel-like crosslinked polymer or the granular dried substance is post-crosslinked; and a granulation step in which the grain size of the granular dried substance or the post-crosslinked granular dried substance is adjusted to obtain a water-absorbing resin powder. The particulate hydrous gel-like crosslinked polymer includes a gel plasticizer. The gel temperature of the particulate hydrousgel-like crosslinked polymer including the gel plasticizer is 50 DEG C or higher as measured using a contact thermometer. In this production method, the granular dried substance or the post-crosslinked granular dried substance is force cooled before the granulation step.

Description

technical field [0001] The present invention relates to a method for producing water-absorbent resin powder and an apparatus for producing the same. More specifically, it relates to a method for producing water-absorbent resin powder and an apparatus for producing water-absorbent resin powder in which the production process is simplified and compacted, and the amount of fine powder generated in the production process is reduced, compared with conventional production methods for water-absorbent resin. Background technique [0002] Water-absorbent resin (SAP / Super Absorbent Polymer) is a water-swellable and water-insoluble polymer gelling agent, which is mostly used in absorbent articles such as disposable diapers and sanitary napkins, water-retaining agents for agriculture and gardening, and industrial water-stopping agents and other fields. [0003] The above-mentioned water-absorbent resins use many monomers and hydrophilic polymers as their raw materials. However, from th...

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Problems solved by technology

[0012] Furthermore, as a problem other than the generation of fine powder in the continuous air belt dryer 100, there is the following problem: for the hydrogel polymer 104 laminated on the belt 102, if Figure 10 As shown by the arrow 106, air is ventilated in the up and down direction, so the drying speed is different in the thickness direction of the hydrogel 104

In addition, uneven ventilation occurs depending on the location, so the drying state becomes uneven in the upper, lower, left, and right sides of the hydrogel 104, and problems such as degradation of physical properties and generation of undried matter are likely to occur.

Furthermore, there are the following problems: the drying efficiency is reduced due to the gap between the two ends of the belt dryer 100 due to the shrinkage of the gel during drying (Patent Document 20); (Patent Documents 17 to 19); drop, scattering, and clogging of the dried material of the punched metal and metal mesh used as the drying belt 102, and the drying material at the outlet of the dryer is difficult to peel off from the drying belt 102. The crushing of objects is troublesome (patent documents 22, 23), etc.

[0014] However, the hydrogel-like polymer has low fluidity due to high adhesiveness and aggregation, so it is necessary to add a large amount of gel fluidizer (surfactant) when stirring and drying, which is also unfavorable in terms of cost. Surfactant (surfactant) residue may be accompanied by deterioration of water-absorbent resin performance

In addition, the stirring of the hydrogel requires a large stirring power, and the dried product may deteriorate due to such mechanical damage.

Furthermore, in agitation drying and fluidized bed drying, even if small-scale, especially batch drying at the laboratory level can be carried out, adhesion of the hydrogel to the inner surface of the device and separation of the hydrogel will occur during long-term continuous operation. It is difficult to achieve long-term continuous drying by agitation drying due to problems such as aggregation between

In addition, in the fluidized bed dryer, there is a problem that a large amount of air volume is required to fluidize the hydrogel, and it cannot be applied to other than specific hydrogels with high fluidity (for example, hydrogels with high solid content). Wait

However, micronization and foaming polymerization of hydrogel before drying to increase the water absorption rate may be accompanied by generation of fine powder including process damage and increase in residual monomers

Furthermore, when the method of finely pulverizing the hydrogel is used, there is a tendency that the problems caused by the ventilated belt dryer (dried matter falling from the drying belt, scattering, and clogging of the belt) tend to become more significant.

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