Of chemical paper pulps, including TCF and ECF variants for both softwood

Kraft and sulfite pulps and two representatives of hardwood kraft pulps, on the

Basis of extended chemical characterization, is provided in Tab. 11.1.

Tab. 11.1 Comprehensive chemical characterization of a

representative selection of commercial paper-grade pulps [17].

Parameter Pine Spruce Eucalyptus Beech Spruce Spruce Beech

Kraft Kraft Sulfite Sulfite

ECF TCF ECF ECF TCF ECF TCF

Basic characteristics

Kappa number – 0.5 0.5 0.5 0.8 2.7 0.3 6.2

Brightness % ISO 89.0 90.7 89.7 87.6 85.9 92.7 90.3

Viscosity mL g–1 793 635 833 802 1020 868 1123

Extractives

DCM % od pulp 0.03 0.03 0.12 0.17 0.15 0.10 0.15

Acetone % od pulp 0.05 0.02 0.16 0.18 0.12 0.12 0.18

Alkali resistancies

R10 content % od pulp 87.0 87.2 91.9 90.0 87.7 87.4 84.6

R18 content % od pulp 87.1 88.0 94.6 93.6 89.8 90.5 87.6

Carbohydrates

Glucose % od pulp 84.7 86.1 80.4 73.3 89.7 91.6 84.9

Mannose % od pulp 6.6 5.8 0.3 0.2 5.2 5.0 1.2

Galactose % od pulp 0.2 0.2 0.1 0.1 0.0 0.0 0.0

Xylose % od pulp 7.3 6.9 18.4 25.5 4.1 2.7 12.2

Arabinose % od pulp 0.5 0.5 0.0 0.0 0.0 0.0 0.0

Pulp Properties and Applications

Tab. 11.1 Continued.

Parameter Pine Spruce Eucalyptus Beech Spruce Spruce Beech

Kraft Kraft Sulfite Sulfite

ECF TCF ECF ECF TCF ECF TCF

Hexenuronic acid (HexA) lmol g–1 1.1 1.5 1.4 1.1 0.7 0.7 0.6

Organochloric compounds ppm 130 33 203 n.d. <6 61 <6

Functional groups

Copper number % 0.3 0.2 0.8 0.5 1.0 1.3 1.4

Carbonyl groups (CCOA) lmol g–1 15 9 12 57 37

Carboxyl groups lmol g–1 37 46 84 131 54 40 70

Inorganic Compounds

Total ash % 0.33 0.19 0.19 0.34 0.30 0.20 0.23

Ca ppm 199 130 175 1208 655 453 916

Mg ppm 404 195 70 319 550 130 237

Si ppm 293 50 59 73 115 63 10

Fe ppm 49 11 6 16 25 4 2

Mn ppm 1.7 2.0 2.3 2.7 4.1 < 0.2 0.4

Water retention value (WRV) % 83.7 80.6 78.3 92.8 76.2 81.2 84.3

Zero-Span tensile index

dry Nm g–1 130.8 133.7 147.1 n.d. 113.1 103.6 98.8

rewetted Nm g–1 116.2 109.4 n.d. n.d. 96.5 82.9 84.4

The residual lignin content of all ECF- and the TCF-bleached softwood kraft

Pulps is far below 1, indicating a low tendency of light-induced yellowing. The

Two TCF-bleached sulfite pulps reveal slightly elevated kappa numbers, which

May be attributed to the applied bleaching concept, namely sequential alkaline

Oxidative bleachings step comprising oxygen delignification and hydrogen peroxide

Bleaching.

There are also some noticeable differences in pulp viscosity ranging from low

Level in the case of TCF-bleached softwood kraft pulp to generally high levels in

The case of the TCF-bleached sulfite pulps. The high bleaching selectivity of the

Latter is reflected in the high viscosity at a given brightness level.

Paper-Grade Pulp

The extractives content of a fully bleached commercial pulp depends on many

Different parameters, with the wood species, pulping, and bleaching processes

Being the most important influencing factors. The data in Tab. 11.1 confirm the

Predominant influence of the cooking process on the extractives content when

Comparing sulfite and kraft pulps based on spruce wood. The bleaching sequence,

However, seems not to exhibit a major influence on the extractives content. TCFand

ECF-bleached spruce sulfite pulps reveal similar resin contents. A further significant

Decrease in the extractives content due to bleaching operations may only

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