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OBA, fx ts, tmprtr tt tm [10]. Tprs f ts s s C2+ t wt wtr rst OBA rtt. As, r tmprtr r tmf OBA wt pp frs mprv t OBA rtt [10].

T fftvss f OBA t v mt f OBA sr HYP frs ws fft m t prprts s s tr rtss f HYP [13]. OBA s ss fftv twr-rtss HYP. Ts s s t t r-mtt OBA s sr t rts s s pp frs.

T r t HYP rtss, t r t OBA ff.

Incorporating OBA Brightening into the Alkaline PeroxideBleaching Process in HYP ProductionCvt, OBA s s t t wt- f t pprmk- prss. W HYP s ssttt fr HW BKP prt wrt ppr t tk vts f ts k tsttr, t rtss wtss r fft tv t t frr rtss wtss f HYP. Hwvr,t tv fft f HYP rtss wtss mpst fr mr OBA t t wt- [10].

W prps tt OBA t HYP t t pp m,

s t r tmprtr r tt tm mprv

t kr ws t m t st tst rt t TAPPI str mts [11,12].

Fr t smt f pp OBA t t mftrprss f HYP prt, OBA ws tr t t qr r t t pp-srr ftr prx . It ttr s, t pp srr ws mx wt OBA t 5-10%pp sst 80°C fr 20 mts, t jst t

t pH 6 prss t 25% pp sst Bürf. T prss pp ws r-r fr s fr tssqt xprmts (st s t OBA-trt HYP).

W t OBA-trt HYP (r-r) ws s t prt ssttt fr HW BKP, t ws sk wt z wtrvrt, strt wt t SW BKP HW BKPfr 15,000 rvts str strtr t 1.2% ppsst. Fr t -rf xprmts, t OBA-trtHYP ws sk strt wt t HW BKP, trf PFI m t 10% sst fr 2,000 rvts.

T -rf pp ws t strt fr 15,000 rvts m t sts.

Fr t OBA fft xprmts t OBA-trt HYP,t r-r pps wr sk wt z wtr vrt, t strt t t 1.0% pp sst fr 15,000rvts str strtr. T pp ssps wst m t sts fr trm t pt prprts.Fr t t wtr xtrt, t strt pp ssps

ws t wtr t t 50°C fr r fr mksts.

T pt-rvrs f sts ws prfrm ptrtr, wt tt tst f tr 9-10 mW/m2 (pprxmt 53 tms rtr t t tst f rmff t) frst t r 2.7 mW/m2 UV t (wt m wvt f 350 m). A f s st t k f

t ptrtr fr tmprtr tr.

RESULTS AND DISCUSSION

OBA is Effective in Improving the Optical Properties of HYPAs sw T 1, OBA mprv t pt prprts f HYP (Asp 325/85) sft. Wt 1 k/t OBA (TpUP), t rtss rs t 2 ts, t wt-ss 5 ts. T wss (*) rpp frm 5.85 t 4.86.

Wt 4 k/t OBA, t pt prprts f HYP (rtss, wtss, *) r smr t ts f tp rw krft pp. It s rprt tt t rt ff f OBA s trm ts rtt fftvss pp

frs [13,14]. T rtt f OBA s fft t tps f

Pulp OBA dosage, Brightness, % CIE whiteness b*% ISO

HYP 0 84.6 65.7 5.85HYP 0.1 86.4 70.6 4.86HYP 0.2 87.6 74.0 4.14HYP 0.4 88.9 76.6 3.55

HW BKP 0 88.4 76.2 3.84

Other conditions: Di-sulfonic OBA; 1.0% pulp consistency;100ppm Ca2+; pH 6.5; 20 minutes contact time.

TAble I. effct of ObA on th optica proprtis of HYP in

comparison to hw.

OBA dosage 0 0.1 0.2 0.5 1.0

30% SW BKP + 70% HW BKPBrightness (%ISO) 87.63 91.20 92.60 94.66 95.95L* 97.07 97.14 97.19 97.25 97.25a* -0.41 0.56 0.90 1.33 1.59b* 3.70 1.21 0.38 -0.72 -1.35

CIE Whiteness 75.87 87.30 91.17 96.25 99.08Fl. Comp. (%ISO) 0 3.58 4.91 6.97 8.38

10 % OBA-HYP + 30% SW BKP + 60% HW BKPBrightness (%ISO) 90.15 91.40 92.36 93.97 95.16L* 97.05 96.97 96.99 97.05 97.12a* 0.32 0.76 0.96 1.25 1.37b* 1.92 0.90 0.33 -0.52 -0.97CIE Whiteness 83.88 88.25 90.90 94.85 97.08Fl. Comp. (%ISO) 2.95 4.55 5.47 7.10 8.34

15 % OBA-HYP + 30% SW BKP + 55% HW BKPBrightness (%ISO) 90.20 91.55 92.35 93.78 94.87L* 96.90 96.99 97.04 97.08 97.12

a* 0.40 0.70 0.90 1.22 1.29b* 1.71 0.93 0.48 -0.29 -0.75CIE Whiteness 84.42 88.20 90.32 93.92 96.09Fl. Comp. (%ISO) 3.52 4.84 5.62 7.06 8.24

25 % OBA-HYP + 30% SW BKP + 45% HW BKPBrightness (%ISO) 90.75 91.68 92.27 93.41 94.30L* 96.93 96.99 97.01 97.04 97.05a* 0.51 0.73 0.82 1.09 1.21b* 1.43 0.90 0.58 -0.02 -0.41CIE Whiteness 85.78 88.33 89.84 92.60 94.40Fl. Comp. (%ISO) 4.53 5.38 5.97 7.04 8.17

Note: The OBA-HYP had a brightness of 91.7% ISO. Other conditions

for OBA addition to the mixed furnish: Tetra-sulfonic type of OBA; 1.0%pulp consistency; 100ppm Ca2+; pH 6.5; 20 minutes contact time.

TAble II. effct of th sustitution of ObA-tratd HYP for

hardwood bKP on th ObA fficincy at th papr machin.



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OBA rtt ts ts rt ff. If OBA s trfr t t k prx , prxs fft t frst prprts f OBA, t pp-t f OBA vt rprt t t prss. Bs xprmt rsts, w frm tt trs rt tw OBA t prx-t qr r t rm ts. Frtrmr, rxprmt rsts sw tt ffrt vs f prx -trt DCS v fft t rtff f OBA. I t m prt, OBA t t pp wt t qr r t t ttm f t twr wt t t wtr, s sw Fr 1.

T HYP t rtss (.. 85% ISO), strr ts (r prx r, kt tm-prtr) r s , w rs t k t

sttr fft f HYP. If t rtss trt f HYP swr frm 85% ISO t 83% ISO prx , tprt st f HYP w rs sft, w t k t sttr f HYP prsrv. T pt rs t prt st. Fr xmp, fr prx - t rs 83% ISO t 85% ISO, t 2% prxs rqr; fr s OBA t v t sm rtss ,t 0.2% Tp UP s . T st fr t OBA r prx s t $2,000/t $800/t rsptv, tst m ft f s OBA s rtr vt.

Adding OBA to Pulp Furnish Containing OBA-treated HYP

Fr rtss prt wrt ppr rs (>88%

FIG. 1. Proposd addition points for th appication of ObA

to HYP at th pup mi. FIG. 2. Comparison of th adsorption of ObA on HYP and

bKP (Ttra-sufonic ObA, pH 6.5, 2-hour contact tim, room

tmpratur).

FIG. 3. Comparison of th rightning fficincy of ObA

twn two addition mthods with th prsnc of PeI

(30% SW bKP, 20-60% HW, 10-50% HYP (Aspn 325/85),

0.05-0.25% Di-sufonic ObA, 0.2% PeI).

Addition Method A: OBA added to B: OBA added toHYP at the mixed furnish atpulp mill the wet-end

OBA dosage(%, on total furnish) 0.25 0.50 0.25 0.50Brightness, % ISO 90.7 91.9 0.3 91.5

Whiteness 84.1 87.2 3.0 86.5b* 1.97 1.30 2.21 1.38

Note: Furnish composition: 30% SW BKP+ 20% HW BKP + 50% HYP;OBA: Di-sulfonic OBA; wet-end conditions: 1% pulp consistency, pH 6.5,100 ppm Ca2+, 5 minutes of contact time.

TAble III. Comparison of th ObA fficincy twn two

addition mthods.

ISO), OBA s rm t t wt- f t pprmk- prss. W t OBA-trt HYP s prt sstttfr rw BKP, qst rss s t wtr t rtff f OBA t t wt- w ffttv.

W s st f xprmt trs, wr, t r- w BKP ws prt ssttt wt t OBA-trt HYP(Gr 325/90); OBA ws t t t mx frs t 1%pp sst, 100 ppm m trt, pH 6.5. T-

ss ts wr smr t t wt- t f OBA t pprmk prss. Hsts wr t m t tr-m t rtss. Rsts T 2 sw tt fr rtssv p t 92% ISO, t prs f t OBA-trt HYP s fft t f rtss fr t HYP sstttf 15% r wr. Hwvr, t rtss r t 92% ISO(v wt mr OBA), r HYP ssttt rt f rt 15%, st mr OBA t t tr (0% HYP) s t r t sm rtss wtss.

I r, OBA-trt HYP s t rp prt f BKP prt wrt ppr wt fft trtss, wtss wss f ppr prts v w

OBA s s s w t t wt- f t pprmk prss.




peer reviewed T2

OBA. T rsts sw tt t t smHYP ssttt rt OBA s,Mt A ws v r rtss wtss, wr wss (*).

T r OBA ff f MtA s t ss q fft frmPEI. Fr 3 mprs t rtss frm OBA (frst mpt)

f t tw sstms t vrs ts, w mstrts t sprr OBAprfrm w r t HYPmftr prss.

Fr Mt B, OBA s s t t pp frs frst s fr s pssfrm t t pt f PEI t rstr trts. Hwvr, t -s s t v w t tmtrv tw OBA PEI ts

ws p t 60 mts fr Mt B (T5). T mmz t trfr f PEI

mr fftv, OBA w v t sr fx frs. T rprss ftr OBA t t HYPmftr prss m p fx OBAms frs frm mr strr r .

Minimizing the Interference of Metal Ionsin the White Water Mt s s s A3+ F3+ r prs-t t wt wtr sstm, prtrfr t pprmk sstm. Tsmt s rt wt OBA mst frm psts ts rs tOBA ff [6]. Fx OBA m-s t frs OBA t HYPt t pp m r tr rtvt twrs t rmf mt s. I T6, vrs mt f A3+ F3+ s

wr t pp ssps, ttr f OBA t t mt s wsmpr tw t tw t mt-s, wt tr ts .

T rsts sw tt t trfr f mt s s sft ss w OBA

s t HYP t t pp m (MtA), v t stt rrtss, frs mpst

wtss, wr wss.

Decreasing the Color ReversionAtr vt f OBA tHYP t t pp m s tt OBA HYP frs m s t s UV sr ts rs t pt-w(r rvrs) f HYP r sp-p, str ppt [15]. As

sw Fr 4, t pt-rvrs f

HYP frs. As sw T 3, t tsm OBA s, t wt ff f OBA ws st ttr w t ws t HYP t t pp m.

Minimizing the Interference from Cationic Polymers such as PEI It s w kw tt t pmrs mt s v tv ffts t prfrm f OBA [6,14]. PEIs t pmr tt s mm s t rtt sstms t tr-z t tv fft f trs. It

rt wt OBA t frm mpxs r t rt ff f OBA. A pr-srpt f OBA tpp frs fr PEI t m rtr trt, t mprvOBA ff. T 4 mprs tff f tw OBA t mts(A B) t vrs HYP sstttrts OBA ss, t prsf PEI (0.2%). Mt A s sm-t f OBA t HYP t t ppm, Mt B s smt

f t vt wt- t f

Ur rm ts, t ff f OBA t t ppr m rmssmr wtr tr s OBA r HYP frs r t.

Advantages of Adding OBA to HYPdur t HYP Mftr Prss

T vts f OBA t HYPr t HYP mftr prssvr t vt wt- OBA -t r sss w.

Improving the OBA Efficiency

OBA ms sr pp frs frm r wt sfrs. W OBA s t frstt ts t HYP BKP, OBA

w sr prfr BKP frs s t r sst fr f . As sw Fr 2, t t sm OBA trt t q ps, t BKP frs srm mr OBA t t HYP frs.It w f t v mr OBAsr HYP frs. OBA m vrp /trz t ws r f

HYP frs mr fftv w t s

PEI dosage, % HYP % OBA dosage % Brightness % ISO b* CIE whiteness

A: OBA was added to HYP at the pulp mill0.2 10 0.05 87.54 3.38 76.440.2 20 0.10 88.78 2.72 79.660.2 30 0.15 88.72 2.46 80.310.2 50 0.25 89.27 2.67 80.16

0 30 0.15 90.68 2.05 83.70

B: OBA was added to mixed furnish at the wet-end0.2 10 0.05 86.22 3.62 74.350.2 20 0.10 87.05 3.38 75.840.2 30 0.15 87.49 3.42 76.120.2 50 0.25 87.30 3.82 74.51

Furnish: 30% SW BKP, 20-60% HW BKP and 10-50% HYP (Aspen 325/85); OBA type:Di-sulfonic; 0.2% PEI; OBA was added first, followed by the addition of PEI after 2 minutes ofmixing, and a handsheet was made after another 5 minutes of mixing.

TAble IV. Comparison of th ffct of PeI on ObA fficincy twn th two

ObA addition systms.

OBA addition Time interval Brightness Bright. gain b* CIEmethod between OBA and (% ISO) due to OBA whiteness

PEI addition, (min.) (% ISO)

Method B 2 87.51 1.89 3.42 76.12Method B 20 87.79 2.04 3.28 76.83Method B 60 87.68 2.01 3.18 77.11Method A - 88.72 2.75 2.46 80.31

Other conditions: 30% SW BKP + 40% HW BKP + 30% HYP, 0.15% OBA (Di-sulfonic); OBA wasadded to the mixed furnish before the addition of PEI (0.2%).

TAble V. effct of tim intrva twn ObA and PeI addition on ObA fficincy.



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Other Practical ConsiderationsI sm ppr ms, HYP s -rf

wt rw BKP. A qst rsss t wtr t str m fr trt tw HYP BKPfrs r -rf w ms tfts f OBA-trt HYP. T swrts qst, w s tr st

f xprmts s sw T 7. FrMt A, 50% OBA-trt HYP ws-rf wt 50% HW BKP PFIm t 450 m CSF, ws t mt sts r ffrt wt-ts; fr Mt B, 50% rrHYP ws -rf wt 50% HW BKP, t OBA ws . T rsts

T 7 sw tt Mt A s st mttr t Mt B wt rspt t trt ff f OBA. Trfr, tt t fts f t

OBA-trt HYP mtftr t -rf prss.Atr qst s t fft f

OBA HYP frs, t HYP mftr prss. Wtrxtrt t 50°C s smtf t stt ppr m wrt OBA-trt HYP w s t prss. Or rsts sw tt t

wtr xtrt (50°C, 1 r) t pt prprts f t OBA-trtHYP st.

T tst t fft f OBA HYPfrs r sr fr vr-mt, str strtr prtt 3,000 rpm ws s t smt t r-pp, rf pmp prsss ppr m. Rsts sw tt t f t pt prprts f tOBA-trt HYP ws sm, ttt t OBA-trt HYP srvvt tp m trtmts ppr m.

CONCLUSIONS

OBA st-fftv st tmprv t pt prprts f HYP. Aprt ssttt f HW BKP wt tOBA-trt HYP s f- t f ppr rtss

wtss, w w r-mt t mr HYP ppts mrppr rs. Ntr OBA s trfr- t t k prx prss, r t ms t prfrm f OBA. Trfr, tOBA rt prss rp-

rt t t prx prss

mr OBA w st HYP frs tprtt tm frm t rt ts rs t pt-rvrs f tppr. As sw Fr 6, trt rvrs ws srv fr tppr st wt OBA-trt HYP

t f t UV t trtmts.

OBA-trt HYP s m ss t trr HYP w xps t UV r-t r t sm ts.

T sm ft s s w s t OBA-trt HYP tprt f HYP-t ppr. If

OBA s t HYP t t pp m,

Wet-end Brightness Bright. gain due b* CIE Whitenessconditions (% ISO) to OBA (% ISO)

A: OBA was added to HYP at the pulp mill (0.15% Di-sulfonic OBA)Blank A 90.4 3.6 2.5 82.0

Al3+ 2.5ppm 90.3 3.6 2.5 81.7 Al3+ 5.0ppm 90.2 3.6 2.6 81.3 Al3+ 10 ppm 89.6 3.5 2.8 80.2

Al3+ 20 ppm 89.4 3.4 2.9 79.6Fe3+ 0.1ppm 90.1 3.6 2.6 81.4Fe3+ 0.2ppm 90.0 3.5 2.5 81.3Fe3+ 0.4ppm 89.0 3.4 2.5 80.5Fe3+ 0.8ppm 88.2 3.3 2.6 79.3

B: OBA was added to the mixed furnish at the wet-end (0.15% di-sulfonic OBA)Blank B 90.5 3.6 2.5 81.9

Al3+ 2.5 ppm 88.3 2.7 3.4 77.1 Al3+ 5.0 ppm 88.2 2.3 3.5 76.5 Al3+ 10 ppm 88.1 1.9 3.5 76.7 Al3+ 20 ppm 88.0 1.7 3.8 75.7Fe3+ 0.1ppm 87.8 1.4 3.8 75.3Fe3+ 0.2ppm 87.6 1.4 3.9 74.9

Fe3+ 0.4ppm 87.3 1.5 3.7 75.0Fe3+ 0.8ppm 86.4 1.5 3.7 74.1

Other conditions: 30% SW BKP + 30% HYP + 40% HW BKP; pH 4.5; 5 minutes.

TAble VI. effct of mta ions on ObA fficincy.

Wet-end Brightness Bright. gain due b* CIE Whitenessconditions (% ISO) to OBA (% ISO)

A: OBA was added to HYP at the pulp mill (0.25% Di-sulfonic OBA)Blank A, pH 6.5 89.6 4.81 2.83 80.00.2% PEI, PH=6.5 89.2 4.06 2.73 79.7

0.5% PEI, PH=6.5 87.2 3.95 3.65 74.920 ppm Al3+, pH 4.5 88.2 4.21 3.41 76.620 ppm Al3+, PH=6.5 90.1 4.86 2.45 81.61.0 ppm Fe3+, PH=4.5 84.7 4.11 2.79 74.71.0 ppm Fe3+, PH=6.5 85.0 4.26 2.53 76.0

B: OBA was added to mixed furnish at the wet-end (0.25% Di-sulfonic OBA)Blank B, pH 6.5 89.7 3.96 3.18 79.10.2% PEI, PH=6.5 * 86.3 1.67 4.23 72.00.5% PEI, PH=6.5 * 85.2 2.12 4.87 68.80.5% PEI, pH=6.5 ** 85.4 2.72 4.60 70.020 ppm Al3+, pH 4.5 85.7 2.14 4.69 70.220 ppm Al3+, PH=6.5 89.4 4.53 2.55 80.71.0 ppm Fe3+, PH=4.5 83.1 2.45 3.80 69.9

1.0 ppm Fe3+

, PH=6.5 84.9 3.85 2.64 75.6

Furnish: 50% HYP + 50% HW BKP; OBA treated HYP was air-dried to simulate the commercial HYPprocess. Co-refining of HYP and HW BKP: 2000 PFI revolution to about 450 ml CSF. * PEI wasadded before OBA; ** OBA was added before PEI.

TAble VII. Comparison of th two ObA addition mthods with co-rfining of

HYP and bKP.




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Annual Meeting, Feb. 2007, B235-240, Montreal, Canada.14. Crouse, B.W.; Snow, G.H., “Fluorescent Whitening Agent in the Paper Indus-try: Their Chemistry and Measurement”, Tappi J., 64(7): 87-89 (1981).15. Bourgoing, S.; Leclerc, É.; Martin, P.; Robert, S., “Use of Fluorescent Whiten-ing Agents to Inhibit Light-induced Colour Reversion of Unbleached MechanicalPulps”, Journal of Pulp and Paper Science, 27(7): 240-244 (2001).

vt.

A OBA t HYP t t pp m v svr v-ts vr t vt wt- t f OBA. Frst, tq fft OBA t wt- t pmrs ss PEI rs fx OBA HYP frs fr t t pprmk prss. Mrvr, t tvmpt f mt s t wt wtr sstm t OBA pr-frm mmz w OBA s pr-sr fx HYP frs. Frtrmr, t pt-w (r rvr-s) f HYP HYP-t ppr sts rs

w mr OBA s HYP frs t prtt tm frm rmfUV rt. OBA s fft t HYP frs w t s t HYP mftr prss, t rts w

w sjt t wtr xtrt (50°C), strt -rf trtmts.

LITERATURE1. Zhou, Y., “Overview of High Yield Pulps (HYP) in Paper and Board”, PAPTAC90th Annual Meeting, 2004, B143-148, Montreal, Canada.2. Cannell, E.; Cockram, R., “The Future of BCTMP”, Pulp and Paper, 74(5):61-76 (2000).3. Reis, R., “The increased use of hardwood high yield pulps for functional advan-tages in papermaking”, Proceedings of the 2001 Papermakers Conference, 2001,87-108 (Cincinnati, OH, USA) .4. Levlin, J.E., “On the Use of Chemi-mechanical Pulps in Fine Papers”, Paperi jaPuu - Paper and Timber, 72(4): 301-308 (1990).5. Ford, M.; Sharman, P., “Performance of High Yield Hardwood Pulp is Inves-tigated as it should be the Choice of the Future”, Pulp & Paper International,38(10): 29 (1996).6. Neimo, L. (Book Editor), Papermaking Science and Technology, Book 4,Papermaking Chemistry, 1999, Fapet Oy, Helsinki, Finland.7. Ragauskas, A.J.; Allison, L.; Lucia, L.A.; Li, C., “Brightness Reversion of Mechan-ical Pulps XIV: Application of FWAs for High-brightness, High-yield pulps”, Solu-tions!, 84 (11): 55 (2001).8. Bourgoing, S.; Robert, S., “Inhibition of Light Induced Colour Reversion by Diaminostilbene Derivatives Fluorescent Whitening Agents - Molecular SimulationCorrelation”, Proceedings of PAPTAC 87th Annual Meeting, 2001, B47-B54.9. Scheringer, M.; Halder, D.; Hungerbühler, K., “Comparing the Environmen-tal Performance of Fluorescent Whitening Agents with Peroxide Bleaching of Mechanical Pulp”, Journal of Industrial Ecology, 3(4): 77-95 (1999).10. Zhang, H.; Hu, H.; He, Z.; Ni, Y.; Zhou, Y., “Retention of Optical Brightening Agents (OBA) and their Brightening Efficiency on HYP-containing Paper Sheets”, J. Wood Chem. Tech., 27(4): 153 (2007).11. “Forming Handsheets for Reflectance Testing of Pulp (Sheet Machine Proce-dure)”, TAPPI Test Methods T272 (1992).12. “Diffuse Brightness of Pulp (d/0°)”, TAPPI Test Methods, T525 (1992).13. Zhang, H.; He, Z.; Ni, Y.; Hu, H.; Zhou, Y., “Effectiveness of Optical Bright-ening Agent (OBA) on High Yield Pulps (HYP)”, Proceedings of 93rd PAPTAC

FIG. 4. effct of ObA on th accratd photo-rvrsion of

HYP undr intnsiv UV radiation (Photo ractor: 350 nm

nomina wavngth, 2.7 mW/cm2 intnsity).

FIG. 5. Comparison of th UV rvrsion of HYP-containing

papr shts twn th two ObA addition mthods

(50% HYP + 50% HW bKP, 0.25% Tinopa UP; Photo ractor:

350 nm nomina wavngth, 2.7 mW/cm2 intnsity).

Rfrnc: HE, Z., ZHANG, H., NI, Y., ZHOU, Y. Adding OpticalBrightening Agents to High-Yield Pulp at the Pulp Mill. Pulp & Paper Canada March 2009:T19-24. Paper presented at the 94th Annual Meet-ing in Montreal, February 5-7, 2008. Not to be reproduced without per-mission of PAPTAC. Manuscript received December 18, 2007. Revisedmanuscript approved for publication by the Review Panel December29, 2008.

Kywords: BRIGHTNESS, HIGH-YIELD PULP, OPTICAL BRIGHT-ENING AGENT, PEROXIDE BLEACHING, PULP MILL, OBA EFFI-CIENCY, BLEACHING COST.

Résumé: Les agents de blanchiment optique (ABO) peuvent réelle-ment améliorer les propriétés optiques de la pâte à haut rendement(PHR). Nous avons à cette fin mis au point une nouvelle méthode etconstaté que le blanchiment aux agents de blanchiment optique peutsans problème être intégré au blanchiment au peroxyde alcalin. Encombinant le blanchiment au peroxyde à un agent de blanchimentoptique, on peut réduire le coût du blanchiment et obtenir la mêmeblancheur désirée. L’ajout d’un ABO à la PHR à l’usine de pâte com-

porte de nombreux avantages par rapport à l’ajout habituel d’un ABOà la partie humide.

U V e x c l u s i v e b r i g h t n e s s ( % I S O )

B r i g

h t n e s s ( % I S O )

C I E W h i t e n e s s

high yield pulp

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