- •Recovered Paper and Recycled Fibers
- •Isbn: 3-527-30999-3
- •Introduction
- •Isbn: 3-527-30999-3
- •Isbn: 3-527-30999-3
- •2006, Isbn 3-527-30997-7
- •Volume 1
- •Isbn: 3-527-30999-3
- •4.1 Introduction 109
- •4.2.5.1 Introduction 185
- •4.3.1 Introduction 392
- •5.1 Introduction 511
- •6.1 Introduction 561
- •6.2.1 Introduction 563
- •6.4.1 Introduction 579
- •Volume 2
- •7.3.1 Introduction 628
- •7.4.1 Introduction 734
- •7.5.1 Introduction 777
- •7.6.1 Introduction 849
- •7.10.1 Introduction 887
- •8.1 Introduction 933
- •1 Introduction 1071
- •5 Processing of Mechanical Pulp and Reject Handling: Screening and
- •1 Introduction 1149
- •Isbn: 3-527-30999-3
- •Isbn: 3-527-30999-3
- •Isbn: 3-527-30999-3
- •Isbn: 3-527-30999-3
- •Introduction
- •Introduction
- •Isbn: 3-527-30999-3
- •1 Introduction
- •1 Introduction
- •1 Introduction
- •1 Introduction
- •1 Introduction
- •1 Introduction
- •150.000 Annual Fiber Flow[kt]
- •1 Introduction
- •1 Introduction
- •Introduction
- •Isbn: 3-527-30999-3
- •Void volume
- •Void volume fraction
- •Xylan and Fiber Morphology
- •Initial bulk residual
- •4.2.5.1 Introduction
- •In (Ai) Model concept Reference
- •Initial value
- •Validation and Application of the Kinetic Model
- •Inititial
- •Viscosity
- •Influence on Bleachability
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Impregnation
- •Introduction
- •International
- •Impregnation
- •Influence of Substituents on the Rate of Hydrolysis
- •140 116 Total so2
- •Xylonic
- •Viscosity Brightness
- •Xyl Man Glu Ara Furf hoAc XyLa
- •Initial NaOh charge [% of total charge]:
- •Introduction
- •Isbn: 3-527-30999-3
- •Introduction
- •Isbn: 3-527-30999-3
- •Introduction
- •Introduction
- •Isbn: 3-527-30999-3
- •In 1950, about 50% of the global paper production was produced. This proportion
- •4.0% Worldwide; 4.2% for the cepi countries; and 4.8% for Germany.
- •1150 1 Introduction
- •1 Introduction
- •1 Introduction
- •Virgin fibers
- •74.4 % Mixed grades
- •Indonesia
- •Virgin fibers
- •Inhomogeneous sample Homogeneous sample
- •Variance of sampling Variance of measurement
- •1.Quartile
- •3.Quartile
- •Insoluble
- •Insoluble
- •Insoluble
- •Integral
- •In Newtonion liquid
- •Velocity
- •Increasing dp
- •2Α filter
- •0 Reaction time
- •Increasing interaction of probe and cellulose
- •Increasing hydrodynamic size
- •Vessel cell of beech
- •Initial elastic range
- •Internal flow
- •Intact structure
- •Viscosity 457
- •Isbn: 3-527-30999-3
- •1292 Index
- •Visbatch® pulp 354
- •Index 1293
- •1294 Index
- •Impregnation 153
- •Viscosity–extinction 433
- •Index 1295
- •1296 Index
- •Index 1297
- •Inhibitor 789
- •1298 Index
- •Index 1299
- •Impregnation liquor 290–293
- •1300 Index
- •Industries
- •Index 1301
- •1302 Index
- •Index 1303
- •Xylose 463
- •1304 Index
- •Index 1305
- •1306 Index
- •Index 1307
- •1308 Index
- •In conventional kraft cooking 232
- •Visbatch® pulp 358
- •Index 1309
- •In prehydrolysis-kraft process 351
- •Visbatch® cook 349–350
- •1310 Index
- •Index 1311
- •1312 Index
- •Viscosity 456
- •Index 1313
- •Viscosity 459
- •Interactions 327
- •1314 Index
- •Index 1315
- •Viscosity 459
- •1316 Index
- •Index 1317
- •Xylose 461
- •Index 1319
- •Visbatch® pulp 355
- •Impregnation 151–158
- •1320 Index
- •Index 1321
- •1322 Index
- •Xylan water prehydrolysis 333
- •Index 1323
- •1324 Index
- •Viscosity 459
- •Index 1325
- •Xylose 940
- •1326 Index
- •Index 1327
- •In selected kinetics model 228–229
- •4OMeGlcA 940
- •1328 Index
- •Index 1329
- •Intermediate molecule 164–165
- •1330 Index
- •Viscosity 456
- •Index 1331
- •1332 Index
- •Impregnation liquor 290–293
- •Index 1333
- •1334 Index
- •Index 1335
- •1336 Index
- •Impregnation 153
- •Index 1337
- •1338 Index
- •Viscose process 7
- •Index 1339
- •Volumetric reject ratio 590
- •1340 Index
- •Index 1341
- •1342 Index
- •Index 1343
- •1344 Index
- •Index 1345
- •Initiator 788
- •Xylose 463
- •1346 Index
- •Index 1347
- •Vessel 385
- •Index 1349
- •1350 Index
- •Xylan 834
- •1352 Index
1 Introduction
1990 1992 1994 1996 1998 2000 2002
0
20
40
60
80
Millions of Tonnes
Conventional ECF TCF
Fig. 1.1 World bleached chemical pulp production: 1990–2002 [29].
products during the 1980s caused a rapid development of alternative, environmentally
benign bleaching processes [27]. The initial intention was the complete
replacement of all chlorine-containing compounds, resulting in Totally Chlorine
Free (TCF) bleaching sequences. This could be easily accomplished with sulfite
pulps due to their good bleachability. Kraft pulp mills have been converted dominantly
to Elemental Chlorine Free (ECF) bleaching rather than to TCF bleaching,
because the latter, by using ozone or peracids to yield high brightness, deteriorates
pulp quality. ECF bleaching, comprising chlorine dioxide (D) -containing bleaching
sequences, such as DEOpDEpD, is acknowledged as a core component of the
best Available Technology (BAT), since numerous field studies have shown that
ECF bleaching is virtually free of dioxin and persistent bioaccumulative toxic substances
[28]. ECF pulp, bleached with chlorine dioxide, continues to dominate the
world bleached chemical pulp market. In 2002, ECF production reached more
than 64 million tonnes (Fig. 1.1) [29]. Market data show that ECF production grew
by 17% in 2001, whereas TCF pulp production remained constant, maintaining a
small niche market at just over 5% of world bleached chemical pulp production.
The transition to ECF is essentially complete in Europe, the United States and
Canada, with ECF production now representing more than 96% of the whole
bleached chemical pulp production.
Dissolving pulps represent specialty pulps within the chemical pulp segment.
They are chemically refined bleached pulps composed of more than 90% pure cellulose
(a-cellulose). As mentioned above, two basic processes are used to produce
dissolving pulp. The sulfite process produces pulp with an a-cellulose content of
90–92%, whereas the PHK process typically produces pulp with an a-cellulose
content of 94–96%. Special alkaline purification treatments can yield even higher
10
1.3 Technology, End-uses, and the Market Situation
cellulose levels of up to 96% for the sulfite and up to 98% for the PHK processes.
The low-level a-cellulose pulps are predominantly used to manufacture viscose
staple fibers, whereas the high-level a-cellulose pulps are converted to viscose
yarn for industrial products such as tire cord, high-purity cellulose ethers, various
cellulose acetates and other specialty products.
Although world production of dissolving pulp has been reduced constantly
since the mid-1970s, the developments of the past two years have signaled a slight
change in this trend. With an annual global production averaging 3.65 million
tonnes in 2003, dissolving pulp accounted for only 2.8% of the total wood pulp
production. However, the high demands for cellulose purity and reactivity, as well
as its manifold routes of utilization, are the main reasons for the advanced state of
technology within the pulp industry.
Viscose staple fibers and viscose filaments (both textile and technical) had the
lion’s share of the total production, at 2.2 million tonnes (60%), while 0.53 million
tonnes (15%) stemmed from the manufacture of a variety of cellulose acetate
products (cigarette filters, filaments, plastics, etc.). The remaining 25% were
accounted for by the production of cellulose ethers, cellophane, microcrystalline
cellulose (MCC), specialty papers and nitrocellulose (Tab. 1.3).
Tab. 1.3 World production of dissolving pulp by end-use in 2003 [30].
Cellulose product End-use Mio t
Regenerated fibers Staple, filaments 2.20
Cellophane Incl. sponges, casings 0.10
Cellulose acetate Tow, filament, plastic 0.53
Cellulose ether Non-ionic, ionic (CMC) 0.47
MCC Incl. moulding powder 0.09
Others Nitrocellulose, speciality papers 0.26
Total 3.65
Unlike paper-grade pulping the acid sulfite process is the dominant process for
the production of dissolving pulps, and accounted for 60–63% of the total production,
while 22–25% originated from PHK process in 2003. The remaining 12–16%
was produced from cotton linters which, for purification and viscosity control, is
treated by alkaline cooking and subsequent hypochlorite bleaching. Purified cotton
linters represents the dissolving pulp of highest cellulose purity particularly
used for manufacturing acetate plastics and high-viscosity cellulose ethers. However,
in China cotton linters is used as a raw material for the manufacture of viscose
fibers, both staple and filaments.
11