| 摘要 |
Milling and bleaching particles (I) of comminuted natural cellulose material using hydrogen peroxide (II) as bleaching agent, comprises that (I) are treated with (II) at a solid content of more than 60 % (preferably more than 75 %) and ground in a high-speed hammer or centrifugal mill during the bleaching. Independent claims are also included for the following: (a) bleached fibers of pine-wood with a fiber length of 50 - 150 micro m, a bulk density of 90 - 130 g/l and a degree of whiteness of 65 - 69 % ISO; (b) bleached pine-wood flour with a 32 micro m sieve residue of less than 5 %, a D50 of 15 - 20 micro m, a bulk density of 220 - 330 g/l and a degree of whiteness of 67 - 72 % ISO; (c) bleached walnut shell flour with a particle size of 300 - 800 micro m, a bulk density of 350 - 500 g/l and a degree of whiteness of 54 - 68 % ISO; (d) bleached alpha -cellulose obtained from hardwood extraction residues, with a degree of whiteness of 78 % ISO at an alpha -cellulose content of more than 90 %; and (e) bleached, partly soluble cereal fibers obtained from optionally extracted, demineralized cereal residues, rice straw or oat husks reacted with nitric, sulfuric and/or other mineral acid.
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