IPST Technical Paper Series Number 532 Brightness Reversion of Mechanical Pulps Part 4: A Study on the Action of Thiols and Disulfides on Hardwood BCTMP
نویسندگان
چکیده
Stabilization against thermal and photo-induced brightness reversion of high-brightness BCTMP (bleached chemithermomechanical pulp) by various sulfur compounds was investigated. Ethylene glycol bisthioglycolate and 3mercapto-1,2-propanediol were the most effective additives that provided bleaching action and prevented thermal and light-induced brighmess reversion. The stabilizing activity of thiols is detrimentally influenced by long-term storage, particularly for the mercapto-carboxylic acids. However, the photostabilization effect of disulfides was moderate and can be retained during storage. In addition, the results of sulfur analysis for treated BCTMP handsheets support the occurrence of the Michael-type addition of thiols for photostabilizing mechanical pulps.
منابع مشابه
Using Optical Brightening Agents (OBA) for Improving the Optical Properties of HYP-Containing Paper Sheets
EXPERIMENTAL A softwood (mainly spruce) bleached kraft pulp (SWBKP), and a hardwood (eucalyptus) bleached kraft pulp (HWBKP) were refined in a PFI mill to 470 and 490 ml CSF freeness, respectively. Three grades of commercial aspen high-yield pulp (325/85, 325/83, 250/80) were obtained from Tembec Inc., without further refining treatment. The properties of the pulp samples are listed in Table I....
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