A study on the mechanism of the photo-yellowing of partially acetylated groundwood pulps

Ek, Monica; Lennholm, Helena; Lindblad, Gunnar; Iversen, Tommy

doi:10.3183/npprj-1992-07-03-p108-112

Cited by 10 publications

(11 citation statements)

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“…It was also found that discoloration was accelerated by an increased temperature. Further, the discoloration was not directly proportional to the irradiation time, and most of the chromophore formation occurred rapidly during irradiation Ek et al 1992). The initial phase was followed by a slower, less detrimental phase.…”

Section: Early Reports Of Light-induced Yellowingmentioning

confidence: 90%

Review: Light-Induced Yellowing of Lignocellulosic Pulps – Mechanisms and Preventive Methods

Paulsson¹,

Parkås²

2012

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This review will focus on recent progress regarding the mechanisms of light-induced discoloration of mechanical and chemimechanical pulps and on the proposed preventive treatments. It is evident that the mechanisms behind photoyellowing of lignin-rich pulps are complex and that several types of reaction pathways may coexist. Photoyellowing proceeds via one initial fast phase and a slower following phase. The fast phase has been ascribed to oxidation of free phenolic groups and/or hydroquinones and catechols to photoproducts of mainly quinonoid character. A multitude of reactions involving several lignin subunits are possible. Important intermediates are phenoxyl radicals, and to some extent ketyl radicals. The importance of the phenacyl aryl ether pathway might be more important than previously thought, even though the original content of such groups is low in lignin. Even though many preventive methods against photoyellowing have been suggested, no cost-efficient treatment is available to hinder photoreversion of lignincontaining paper permanently. Suggested methods for stabilization include chemical modification (etherification and esterification), coating the paper product, addition of radical scavengers, excited state quenchers, or ultraviolet absorbing compounds.

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Section: Early Reports Of Light-induced Yellowingmentioning

confidence: 90%

Review: Light-Induced Yellowing of Lignocellulosic Pulps – Mechanisms and Preventive Methods

Paulsson¹,

Parkås²

2012

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“…Chemicals such as NaBH 4 have been used to reduce the α-carbonyl groups in lignin model compounds, milled wood lignins and different types of high-yield pulps (Leary 1968;Lin, Kringstad 1970;Ek et al 1990;Fornier de Violet et al 1989;Francis et al 1991;Schmidt, Heitner 1991;Paulsson et al 1995). Another approach has involved the use of processes such as methylation, acetylation and propionylation to etherify and/or esterify phenolic and benzylic hydroxyl groups (Schmidt, Heitner 1991;Ek et al 1992;Paulsson, Parkås 2000;Paulsson, Simonson 2002). A variety of additives have also been investigated, ranging from UV-absorbing compounds such as benzophenone derivatives to fluorescent whitening agents (FWAs), antioxidants, polymers and quenchers (Kringstad 1969;Janson, Forsskåhl 1989, 1996Agnemo et al 1991;Heitner 1993a;Paulsson, Ragauskas 1998a and references cited therein; Cole et al 2000;Bourgoing et al 2001;Ragauskas et al 2001).…”

mentioning

confidence: 99%

A novel method of studying the ability of a coating layer to retard the photo-yellowing of the base paper

Fjellström

Höglund

Forsberg

et al. 2007

Nordic Pulp &Amp; Paper Research Journal

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SUMMARY:This paper presents a method of studying the reflectance/transmittance properties of thin coating layers in relation to their inhibition of light-induced yellowing. The ability of a coating layer to retard the photo-yellowing of a hydrogen-peroxide-bleached birch chemithermomechanical pulp (CTMP) is exemplified using the developed model system. The repeatability of the method is shown to be excellent, even for coat weights below 10 g/m 2 . Furthermore, transmittance in the UV-region is shown to be strongly correlated with a coating layer's ability to protect birch CTMP against photo-yellowing.

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“…These new groups could form chromophoric groups in combination with metallic ions. Such factors may account for the observed unfavorable effects on optical properties, including brightness reversion (Ek et al 1992). According to Table 1, the highest PC value and the least brightness stability were observed in H 2 O 2 bleaching and complementary bleaching with sodium dithionite.…”

Section: Resultsmentioning

confidence: 99%

“…The specific light scattering (S), light absorption (K) coefficient, K/S ratio, and post color (PC) number were calculated using the Kubelka-Munk theory. The K/S value and PC number were calculated using the following equations (Ek et al 1992;Paullsson et al 2001;Vaysi and Mirshokraie 2007),…”

Section: Irradiation Of Papermentioning

confidence: 99%

“…However, to date, no single approach has become technically or economically feasible to meet all needs of the paper industry (Forsskahl 2000). Ek et al (1992) reported that the quinone structures and quinone precursors such as hydroquinone and catechols are important reactions in the photo-yellowing process in acetylated ground wood pulps. Paullsson et al (2001) investigated the effect of photoyellowing on untreated chemi-thermo-mechanical pulp (CTMP) under argon, ambient, and oxygen atmospheres.…”

Section: Introductionmentioning

confidence: 99%

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The Effects of H2O2 Bleaching and DTPA Spraying on the Brightness Stability of Hornbeam CMP Pulp following Accelerated Irradiation Aging

Vaysi¹,

Kord²

2013

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In this research, hornbeam chips were cooked under chemimechanical pulp (CMP) conditions, and the pulps were prepared at a yield level of 85%. The CMP pulps were separately bleached with hydrogen peroxide and sodium dithionite with and without treatment with DTPA. Then 60 gr/m 2 handsheets were made. The goal was to determine whether complementary bleaching with sodium dithionite improves optical behavior of the handsheets. Following DTPA solution spraying on the surface of hand sheets, brightness, opacity, and yellowness were improved, and the K/S ratio and PC number were decreased. Among different samples and following optical aging, it was found that in longterm aging, DTPA spray has considerable effect on improving the stability of brightness and increasing the paper's durability against optical deterioration.

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A study on the mechanism of the photo-yellowing of partially acetylated groundwood pulps

Cited by 10 publications

References 0 publications

Review: Light-Induced Yellowing of Lignocellulosic Pulps – Mechanisms and Preventive Methods

Review: Light-Induced Yellowing of Lignocellulosic Pulps – Mechanisms and Preventive Methods

A novel method of studying the ability of a coating layer to retard the photo-yellowing of the base paper

The Effects of H2O2 Bleaching and DTPA Spraying on the Brightness Stability of Hornbeam CMP Pulp following Accelerated Irradiation Aging

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