Fundamentals of BCTMP Brightness Stability

ragauskas@hotmail.com

Fundamentals of BCTMP Fundamentals of BCTMP Brightness Stability Brightness Stability

Art J. Ragauskas

Research Objective:– Investigate mechanisms of brightness

reversion– Develop photostabilization technologies

l Project Goal:– Increase the usefulness of high-yield fibers

Fundamentals of Brightness StabilityFundamentals of Brightness Stability

Fundamentals of Brightness Stability Fundamentals of Brightness Stability Past AccomplishmentsPast Accomplishments

l Developed new UV screens for high brightness mechanical pulps

l Demonstrated that additive combinations are more effective at retarding brightness reversion than individual agents

l Discovered use of FWA as brightness reversion mitigators

Fundamentals of Brightness Stability Fundamentals of Brightness Stability Past AccomplishmentsPast Accomplishments

7577798183858789919395

-1 4 9 14 Period of Irradiation/days

i Brig

75% Kraft 25%BCTMPkraft

0.1% Blankopher

1.0% Phorwite UW

1% Phorwite P

0.1% Tinopal

75% Kraft/25% BCTMP

FWA FWA PhotostabilizationPhotostabilization Effects Effects IntroductionIntroductionl Historical Notes

– FWA employed in P&P industry– Muller reported potential economic

benefits for use of FWA for high-brightness CTMPs

– Doshi found no effect for groundwood» nature of surface lignin may be important

FWA FWA PhotostabilizationPhotostabilization Effects Effects --IntroductionIntroduction

NHH3C CH3

NHSO3Na

Chemical structure of FWA: Tinopal.

absorbs 300-400 nm hν re-emits > 410 nm

TinopalTinopal PhotostabilizationPhotostabilization EffectsEffects

l Tinopal application maintains +85 Tappi Brightness for 8 - 12 days of continuous light exposure

l Use of radical scavenger, ZnO/TiO2, or carrier molecule (PEG or PVA) extends photostabilization effect

l UV-absorber are antagonist

FWA FWA PhotostabilizationPhotostabilization EffectsEffects

l Study thermal reversion properties of FWA treated BCTMP/kraft handsheets

l Optical characterization of BCTMP/kraft handsheets with FWA with natural & office lighting

l Study the effects of light-dark cycling on photoreversion of FWA treated BCTMP/kraft testsheets

FWA FWA PhotostabilizationPhotostabilization EffectsEffects

l Determine photostabilization effects of carrier molecules (PVA, PEG, Polyvinylpyrrolidone, commercial surfactants) with Phorwite P & UW

l Study failure mechanism(s) of FWA

General Experimental MethodGeneral Experimental Method

MonitorOptical Properties

Photo &/or thermalaging

Control Treated with Water

MonitorOptical Properties

Photo &/or thermalaging

Aqueous AdditiveApplied

Hardwood BCTMPor

HW BCTMP + Kraft

Results: Results: PhotoreversionPhotoreversion of Kraft/BCTMP of Kraft/BCTMP -- Effects of Effects of PhorwitePhorwite UWUW

l Employed 1.25 gr handsheetsl Applied 0.1% Phorwite UWl Mixtures of Kraft/BCTMP used

– 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60,– 30:70, 20:80, 10:90, 0:100

l Examined Tappi Brightness with & without fluorescence

Results: Results: PhotoreversionPhotoreversion of Kraft/BCTMP of Kraft/BCTMP Effects of Effects of PhorwitePhorwite 0.1% UW0.1% UW

Period Irradiation/day

-1 0 3 6 9 12 15 18 21 30 36 42 54 66 90

I Brig

UV 95% Kraft 95%Kraft UW 90%Kraft UW 90KraftUW 85%Kraft 85% Kraft UW 80%Kraft 80% KraftUW 70%Kraft 70% kraft

PhotoreversionPhotoreversion of Kraft/BCTMP of Kraft/BCTMP Effects of 0.1% Effects of 0.1% PhorwitePhorwite UWUW

119Period Irradiation/days

-1 19 39 59 79 99

I Brig

UW 60% Kraft

UW 50% Kraft

UW 40% Kraft

UW 30% Kraft

UW BCTMP

UW/KraftKraft

60% Kraft

50% Kraft

40% Kraft

30% Kraft

Results: Results: PhotoreversionPhotoreversion of Kraft/BCTMP of Kraft/BCTMP Effects of Effects of PhorwitePhorwite UW Excluding FluorescenceUW Excluding Fluorescence

-1 19 39 59 79 99 119

Period Irradiation/days

I Brig

1%UW KraftKraft1% UW 90%Kraft/BCTMP90%Kraft/BCTMP1% UW 80%Kraft/BCTMP80%Kraft/BCTMP1%UW 70%Kraft/BCTMP70%Kraft/BCTMP1%UW 60% Kraft/BCTMP60% Kraft

Results: Thermal Reversion Studies Results: Thermal Reversion Studies For FWA Treated Kraft and BCTMPFor FWA Treated Kraft and BCTMP

l Employed 1.25 gr handsheetsl Applied 1% Phorwite UWl Handsheets stored at 28oC

Results: Thermal Reversion Studies for Results: Thermal Reversion Studies for 75% Kraft/BCTMP 75% Kraft/BCTMP TestsheetsTestsheets

-1 1 3 5 7 9 11 13Storage Period/wk

TAPPI Brightness

Control1% Phorwite P1% Phorwite UW1% Tinopal

No accelerated reversion occurring!

PhotoreversionPhotoreversion of BCTMP, Kraft, & of BCTMP, Kraft, & BCTMP/Kraft BCTMP/Kraft -- Effects of Effects of PhorwitePhorwite UWUW

l Examined 3 types of handsheets– 100% kraft, 100% BCTMP, 75%

Kraft/25%BCTMPl Varied Phorwite UW

– 0.1%, 1.0%, 1.5%, 2.0%, 3.0%, 4.0%l Examined use of carrier compound

– 0% & 1.0% PEGl Examined TAPPI brightness, with/without

fluorescence, L*a*b*, abs./scatt. coeff.

Results: Results: PhotoreversionPhotoreversion of BCTMP, Kraft, & of BCTMP, Kraft, & BCTMP/Kraft BCTMP/Kraft -- Effects of Effects of PhorwitePhorwite UWUW

-1 0 1 2 3 4 5 7 9 11Period Irradiation/wk

I Brig

1% UW BCTMPBCTMP1% UW KraftKraft1% UW 75% Kraft/BCTMP75%Kraft/BCTMP

Kraft/BCTMP

Results: Results: PhotoreversionPhotoreversion of 100%Kraft of 100%Kraft Effects of FWAEffects of FWA

-1 19 39 59 79 99

I Brig

Kraft 0.1% uw 1% uw1.5% uw 2% uw 3% uw4% uw

Results with Phorwite UW & PEG were similar, suggesting that loss of FWA contributes to brightness loss in BCTMP

Results: Results: PhotoreversionPhotoreversion of HW BCTMP of HW BCTMP Effects of FWA + Carrier moleculeEffects of FWA + Carrier molecule

TAPPI Brightness

-1 9 19 29 39 49 59

Period Irradiation/wk

BCTMP0.1% UW1% UW1.5% UW0.1%uUW1%PEG1%UW/1%PEG1.5%UW/1%PEG

Results: Results: PhotoreversionPhotoreversion of HW BCTMP of HW BCTMP Effects of FWA + Carrier moleculeEffects of FWA + Carrier molecule

-1 9 19 29 39 49 59

TAPPI BrightnessControl2% UW3% UW4% UW2%UW/1%PEG3%UW/1%PEG4%UW/1%PEG

-at charges < 2% PEG carrier molecule is effective at higher values effect diminishes

Results: Results: PhotoreversionPhotoreversion of 75%Kraft/25%BCTMP of 75%Kraft/25%BCTMP Effects of FWA + Carrier moleculeEffects of FWA + Carrier molecule

- 1 1 9 3 9 5 9 7 9

P e r io d Ir r a d ia t io n

I Brig

7 5 /2 5 c o n tr o l 0 .1 % u w

1 % u w 1 .5 % u w

2 % u w 3 % u w

4 % u w 0 .1 u w /1 p e g

3 u w /1 p e g 4 u w /1 p e g

-carrier effect diminished for Phorwite UW on 75kraft/25 BCTMP

Results: Results: PhotoreversionPhotoreversion of HW BCTMP of HW BCTMP Effects of FWA without FluorescenceEffects of FWA without Fluorescence

-1 0 6 12 18 24 30 36 54 60

I Brig

Control 0.1% uw

1% uw 1.5% uw

2% uw 3% uw

FWA functions more on latter stages of reversion

Note: Phorwite UW/PEG were also examined and demonstrated similar trends

Results: Results: PhotoreversionPhotoreversion of 75% Kraft/25% BCTMP of 75% Kraft/25% BCTMP Effects of FWA without FluorescenceEffects of FWA without Fluorescence

-1 0 6 12 18 24 30 36 42 60 72 84

I Brig

75/25 control 0.1%UW/1%PEG1%UW/1%PEG 1.5%UW/1%PEG2%UW/1%PEG 3%UW/1%PEG4%UW/1%PEG

Comparable trends observed with PEG

Note: FWA appears to influence reversion rates earlier than 100% BCTMP handsheets

Results: Solar Results: Solar PhotoreversionPhotoreversion of BCTMP, Kraft, of BCTMP, Kraft, & BCTMP/Kraft & BCTMP/Kraft -- Effects of Effects of PhorwitePhorwite UWUW

l Examined solar aging of BCTMP, Kraft, & 75% Kraft-25%BCTMP handsheets

l With & without Phorwite UWl Measured Brightness with/without

fluorescence, L*a*b*, abs/scatt. coeff.

Results: Solar Results: Solar PhotoreversionPhotoreversion of BCTMP, of BCTMP, Kraft, & BCTMP/Kraft Kraft, & BCTMP/Kraft -- Effects of Effects of PhorwitePhorwite UWUW

50556065707580859095

-1 1 3 5 7 9 11

I Brig

1% UW 75% Kraft

1% UW BCTMP

1% UW Kraft

75% Kraft

8788899091929394959697

-1 1 3 5 7 9 11

1% UW BCTMP BCTMP 1% UW KraftKraft 1% UW 75% Kraft 75% Kraft

-1 1 3 5 7 9 11

1% UW BCTMP BCTMP 1% UW Kraft Kraft 1% UW 75% Kraft 75% Kraft

-1 1 3 5 7 9 11

1% UW BCTMP BCTMP 1% UW Kraft Kraft 1% UW 75% Kraft 75% Kraft

Results: Effects of Light Cycling on Results: Effects of Light Cycling on PhorwitePhorwite UW Treated HandsheetsUW Treated Handsheets

l Employed kraft, BCTMP, & 75% kraft-25% BCTMP handsheets

l Exposed to fluorescent light x h then stored for x h.

l Measured TAPPI brightness values

Results: Effects of Light Cycling on Results: Effects of Light Cycling on PhorwitePhorwite UW UW Treated HandsheetsTreated Handsheets

initial 0day

1wlight

2wdark

3wlight

4wdark

5wlight

6wdark

7wlight

8wdark

9wlight

10wdark

11wlight

12wdark

Time Period

I Brig

1% UW/BCTMP BCTMP1%UW Kraft Kraft1% UW(75% Kraft/25% BCTMP) 75%Kraft/25%BCTMP

75%Kraft/BCTMP

1% UW/kraft

1% UW BCTMP

Results: Effects of Light Cycling on Results: Effects of Light Cycling on PhorwitePhorwite UW UW Treated HandsheetsTreated Handsheets

initial 0 day 1wlight

2wdark

3wlight

4wdark

5wlight

6wdark

7wlight

8wdark

9wlight

10wdark

11wlight

12wdark

Time Period

I Brig

1%UW BCTMPBCTMP1% UW KraftKraft1% UW (75%Kraft/BCTMP)75% Kraft/25% BCTMP

1% UW Kraft

Kraft/BCTMP

Note: excluding fluorescent component UW sheets perform better

ConclusionsConclusions

l FWA technology for BCTMP is a technology that works

l Effective at retarding solar/office lighting effects

l Thermal reversion appears not to be an issue

Fundamentals of BCTMP Brightness Stability

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