Method for producing particulate water-absorbing agent composed principally of water-absorbing resin
Provided is a production method for the particulate water-absorbing agent, which can collecting the fine powders generated during the producing process efficiently without worsening working environment, and also the particulate water-absorbing agent produced by the production method thereof. This production method includes (1) a polymerization step for obtaining a polymer gel, (2) a drying step for drying said polymer gel to obtain a particulate water-absorbing resin, (3) a classification step for sieving said particulate water-absorbing resin, (4) a surface cross-linking step for cross-linking the neighborhood of the surface of said particulate water-absorbing resin (5) a packaging step for filling a packaging material container with said particulate water-absorbing agent for packaging and (6) a transportation step for transporting the products produced in each of the steps to the other steps. In this production method, the fine powders contained in gas composed principally of air, in any of the steps, can be collected by use of a trapping material.
1. A method for producing a particulate water-absorbing agent comprising:
a polymerization step for obtaining a polymer gel;
a drying step for drying said polymer gel to obtain a particulate water-absorbing resin;
a classification step for sieving said particulate water-absorbing resin;
a surface cross-linking step for cross-linking the neighborhood of the surface of the particulate water-absorbing resin obtained in the classification step to obtain a particulate water-absorbing agent;
a packaging step for filling a packaging material container with said particulate water-absorbing agent for packaging; and
a transportation step for transporting the products produced in each of the steps to the other steps;
wherein fine powders contained in gas composed principally of air, in any of the steps, are collected by use of a trapping material heated to a temperature at or higher than 60° C.; said trapping material, having a trapping efficiency equal to or higher than 90% for trapping Japanese Industry Standard (JIS) 12-type carbon black with a particle diameter of 0.03 μm to 0.2 μm and being a membrane filter composed of a membrane that captures the fine powders generated from any of the steps at the surface thereof and a substrate that supports the membrane, is provided in a fine powder capturing apparatus in at least one of the steps; and the fine powder capturing apparatus is only connected via a pipeline to, but is not placed within, any of the apparatuses for performing any of the steps.
2. A method for producing a particulate water-absorbing agent comprising:
a polymerization step for obtaining a polymer gel;
a drying step for drying said polymer gel to obtain a particulate water-absorbing resin;
a pulverization step for pulverizing said particulate water-absorbing resin;
a classification step for sieving the particulate water-absorbing resin obtained in the pulverization step;
a surface cross-linking step for cross-linking the neighborhood of the surface of the particulate water-absorbing resin obtained in the classification step to obtain a particulate water-absorbing agent;
a packaging step for filling a packaging material container with said particulate water-absorbing agent for packaging; and
a transportation step for transporting the products produced in each of the steps to the other steps;
wherein fine powders contained in gas composed principally of air, in any of the steps, are collected by use of a trapping material heated to a temperature at or higher than 60° C.; said trapping material, having a trapping efficiency equal to or higher than 90% for trapping JIS 12-type carbon black with a particle diameter of 0.03 μm to 0.2 μm and being a membrane filter composed of a membrane that captures the fine powders generated from any of the steps at the surface thereof and a substrate that supports the membrane, is provided in a fine powder capturing apparatus in at least one of the steps; and the fine powder capturing apparatus is only connected via a pipeline to, but is not placed within, any of the apparatuses for performing any of the steps.
3. A method for producing a particulate water-absorbing agent comprising:
a polymerization step for obtaining a polymer gel;
a drying step for drying said polymer gel to obtain a particulate water-absorbing resin;
a pulverization step for pulverizing said particulate water-absorbing resin;
a classification step for sieving the particulate water-absorbing resin obtained in the pulverization step;
a surface cross-linking step for cross-linking the neighborhood of the surface of the particulate water-absorbing resin obtained in the classification step to obtain a particulate water-absorbing agent;
a cooling step for cooling said particulate water-absorbing agent;
a granule sizing step for sizing the particulate water-absorbing agent obtained in the cooling step;
a packaging step for filling a packaging material container with the particulate water-absorbing agent obtained in the granule sizing step for packaging; and
a transportation step for transporting the products produced in each of the steps to the other steps;
wherein fine powders contained in gas composed principally of air, in any of the steps, are collected by use of a trapping material heated to a temperature at or higher than 60° C.; said trapping material having a trapping efficiency equal to or higher than 90% for JIS 12-type carbon black with a particle diameter of 0.03 μm to 0.2 μm and being a membrane filter composed of a membrane that captures the fine powders generated from any of the steps at the surface thereof and a substrate that supports the membrane, is provided in a fine powder capturing apparatus in at least one of the steps; and the fine powder capturing apparatus is only connected via a pipeline to, but is not placed within, any of the apparatuses for performing any of the steps.
4. A method for producing a particulate water-absorbing agent comprising:
a polymerization step for obtaining a polymer gel;
a drying step for drying said polymer gel to obtain a particulate water-absorbing resin;
a pulverization step for pulverizing said particulate water-absorbing resin;
a classification step for sieving the particulate water-absorbing resin obtained in the pulverization step;
a surface cross-linking step for cross-linking the neighborhood of the surface of the particulate water-absorbing resin obtained in the classification step to obtain a particulate water-absorbing agent;
a granule sizing step for sizing said particulate water-absorbing agent;
a packaging step for filling a packaging material container with the particulate water-absorbing agent obtained in the granule sizing step for packaging;
a transportation step for transporting the products produced in each of the steps to the other steps;
a collection step for collecting fine powders contained in gas composed principally of air, in any of the steps, by use of a trapping material heated to a temperature at or higher than 60° C.; said trapping material having a trapping efficiency equal to or higher than 90% for trapping JIS 12-type carbon black with a particle diameter of 0.03 μm to 0.2 μm, and being a membrane filter composed of a membrane that captures the fine powders generating from any of the steps at the surface thereof and a substrate that supports the membrane; and
a granulation step for granulating the fine powders collected by use of the trapping material, the fine powders classified by the classification step, and the fine powders sized by the granule sizing step, to obtain granulated particles;
wherein said granulated particles is optionally charged to any of the steps other than the granulation step,
wherein said trapping material is provided in a fine powder capturing apparatus in at least one of the steps, and the fine powder capturing apparatus is only connected via a pipeline to, but is not placed within, any of the apparatuses for performing any of the steps.
5. The method for producing the particulate water-absorbing agent according to claim 1 , wherein said membrane is made of polytetrafluoroethylene.
6. The method for producing the particulate water-absorbing agent according to claim 3 , wherein said fine powders comprise those generated in the classification step and/or the pulverization step.
7. The method for producing the particulate water-absorbing agent according to claim 1 , wherein the particle diameter of said fine powders is below 150 μm.
8. The method for producing the particulate water-absorbing agent according to claim 1 , wherein gas having a dew point temperature of from −80° C. to −15° C. is passed in any of the steps.
9. The method for producing the particulate water-absorbing agent according to claim 1 , wherein pressure is reduced to below atmospheric pressure in any of the steps.
10. The method for producing the particulate water-absorbing agent according to claim 1 , wherein pressure is increased over atmospheric pressure in any of the steps.
11. The method for producing the particulate water-absorbing agent according to claim 1 , wherein the particulate water-absorbing agent comprises at least one kind of a polyvalent metal salt, an inorganic particle, and a liquid permeability improver.
12. The method for producing the particulate water-absorbing agent according to claim 1 , wherein the amount of the particulate water-absorbing agent supplied to the packaging step is equal to or more than 500 kg/h.
13. The method for producing the particulate water-absorbing agent according to claim 1 , wherein said particulate water-absorbing resin is an irregular pulverized shaped particle of a polyacrylic acid (salt)-based water-absorbing resin.
14. The method for producing the particulate water-absorbing agent according to claim 1 , wherein the polymerization step is performed by continuous kneader polymerization or continuous belt polymerization.
15. The method for producing the particulate water-absorbing agent according to claim 1 , wherein the surface cross-linking step is performed using a surface cross-linking agent having dehydration esterification reactivity of one or more kinds selected from a group consisting of an oxazolidinone compound, an alkylene carbonate compound, a polyvalent alcohol compound, and an oxetane compound, at a temperature in the range of 150 to 250° C.
16. The method for producing the particulate water-absorbing agent according to claim 1 , wherein the amount of dust (AD) of said particulate water-absorbing agent is equal to or lower than 300 ppm.