초록 ▼

The process according to the invention for production of an absorbent polymer comprising the following process steps: i) polymerization of an aqueous monomer solution to obtain a polymer gel; ii) comminution of the polymer gel to obtain a gel granulate; and iii) drying of the gel granulate, and is c

The process according to the invention for production of an absorbent polymer comprising the following process steps: i) polymerization of an aqueous monomer solution to obtain a polymer gel; ii) comminution of the polymer gel to obtain a gel granulate; and iii) drying of the gel granulate, and is characterized in that the gel granulate after step ii) has a spread behavior. The production process of an absorbent polymer distinguishes itself by a particularly efficient drying step iii), which enables a particularly gentle and uniform drying of the gel granulate. The obtained absorbent polymers and products and items produced therefrom have a particularly uniform product quality and constant physical-chemical properties.

대표청구항 ▼

What is claimed is: 1. A process for preparation of an absorbent polymer, comprising the steps of: i) polymerizing an aqueous monomer solution to obtain a polymer gel, ii) comminuting the polymer gel to obtain a polymer gel granulate, and iii) obtaining a mechanically loosened polymer gel granulate

What is claimed is: 1. A process for preparation of an absorbent polymer, comprising the steps of: i) polymerizing an aqueous monomer solution to obtain a polymer gel, ii) comminuting the polymer gel to obtain a polymer gel granulate, and iii) obtaining a mechanically loosened polymer gel granulate by loosening the polymer gel after the comminution in step ii), in the form of the polymer gel granulate obtained after the comminution; and iv) drying the polymer gel granulate; wherein the polymer gel granulate after step ii) has a spread including a first compressibility index κ1 of the gel granulate that lies between about 10% and about 40%; and wherein the spread behavior of the gel granulate after step ii) is characterized by at least one of the following features (δ1) a second compressibility index κ2 of the gel granulate lies between about 3·10−5 Pa−1 and about 6·10−5 Pa−1; or (δ2) a first decompressibility index κ1′ of the gel granulate lies between about 3% and about 15%; or (δ3) a second compressibility index κ2′ of the gel granulate lies between about 3·10−5 Pa−1 and about 7·10−5 Pa−1. 2. The process according to claim 1, wherein the spread behavior of the gel granulate or of the loosened gel granulate after step ii) is characterized by a cross section spread index Q of at least about 3 with a load with a total mass of about 1185 g. 3. The process according to claim 1, wherein the spread behavior of the gel granulate or of the loosened gel granulate after step ii) is determined by a spread time constant τ of at least about 2 s with a load with a total mass of about 6185 g. 4. The process according to claim 1, wherein the density of the undried gel granulated after step ii) is less than about 0.7 g/cm3. 5. The process according to claim 1, wherein the gel granulate in step ii) is subjected to an at least three-step comminution with a cutting unit, a ripping unit and a “wolf” grinding unit. 6. The process according to claim 1, wherein the polymer gel granulate comprises at least about 10 wt. %, based on the gel granulate, an absorbent polymer based upon: (α1) from about 0.1 to about 99.999 wt. % of polymerized, ethylenically unsaturated, acidic groups-comprising monomers or salts thereof, or polymerized, ethylenically unsaturated monomers comprising a protonated or a quaternary nitrogen, or mixtures thereof, (α2) from 0 to about 70 wt. % of polymerized, ethylenically unsaturated monomers which can be co-polymerized with (α1), (α3) from about 0.001 to about 10 wt. % of one or more cross-linkers, (α4) from 0 to about 30 wt. % of water-soluble polymers, as well as (α5) from 0 to about 20 wt. % of one or more auxiliaries, respectively based on the dry absorbent polymer, wherein the sum of the component weights (α1) to (α5) amounts to 100 wt. %. 7. The process according to claim 1, wherein the dried gel granulate has at least one of the following properties: (φ1) the maximum absorption of a 0.9 wt. % aqueous NaCl solution lies within a range from about 10 to about 1000 g/g SAP granulate, (φ2) the fraction that can be extracted with a 0.9 wt. % aqueous NaCl solution is less than about 30, based on the SAP granulate, (φ3) the bulk density lies within the range from about 300 to about 1000 g/l, (φ4) the pH value of about 1 g of the SAP granulate in about 1 liter of water is in the range from about 4 to about 10, (φ5) the CRC value lies within the range from about 10 to about 100 g/g, (φ6) the AAP value at a pressure of about 0.3 psi lies within the range from about 10 to about 60 g/g.