WET-END APPLICATIONS OF NFC

Transcription

1 WET-END APPLICATIONS OF NFC Lutz Hamann, Papiertechnische Stiftung SUNPAP Workshop

2 Content Wet end applications of NFC Purpose Used samples and methods Preparation, dosage strategy, retention Influence to dewatering Improvement of paper properties Conclusion 2

3 Purpose of using NFC in bulk application paper sheet photo, no NFC distribution of pulp fibers paper sheet model, contact points of fibers paper sheet model, improved fiber contact by NFC application in bulk NFC bulk applications in wet-end are expected to positively impact the paper strength properties preserving the paper sheets density better than refining saving of wood fibers by a new way to reduce the paper grammage the efficiency of functional paper additive performance 3

4 Possible applications of NFC in wet end NFC is bridging the distances between the fibers & close the pores in the network 4

5 Materials Pulps: Used samples and methods hardwood (HW); SRE 0 / 40 / 80 kwh/t softwood (SW); SRE 0 / 70 / 140 kwh/t CTMP (board middle layer) NFC: standard NFC sample NFC-CTP/VTT Retention aid: Polymin 1530 (C-PAM) Starch: cationic potato starch, cooked together with NFC in micro wave Methods and analysis Retention : gravimetric by weighting the sheets at medium NFC dosages Dewatering: Schopper Riegler dewatering resistance Sheet forming: RAPID Köthen sheet former Paper testing: tensile index, E modulus, Scott Bond z-strength, 5

6 NFC preparation before sheet forming dosage strategy retention 6

7 Schopper Riegler value [SR] Preparation of NFC before sheet forming 60 5 % NFC-CTP/VTT dispermat ultraturrax 0 HW_UR HW_1.RP HW_2.RP Dispermat Ultraturrax Dispermat+Ultraturrax highest dewatering resistance indicates best NFC dispersion better results when using also ultraturrax standard procedure in all trials (NFC concentration 2 g/l): dispermat 10 min / 1,400 rpm + ultraturrax 4.5 min / 7,500 rpm 7

8 E (SR) [ SR], Tensile index [Nm/g] NFC in wet end: dosage strategy Pulping RA Refiner PTS-pilotplant Dewatering Disintegrator Desintegrator Mixer Sheetforming E (SR) Tensile Index NFC NFC NFC Measurement Disintegrator (5 % NFC) Mixer (5 % NFC) Sheet former (5 % NFC) no NFC place of NFC dosage In order to avoid unwanted NFC agglomaration the reaction time of NFC and pulp should be minimized Used standard in all further trials: NFC dosage sheet wise directly before sheet forming 8

9 retention of NFC-CTP/VTT [%] Retention of NFC in lab sheets R 2 = 0, grammage [g/m²] 10 % NFC-CTP/VTT was used roughly 50 % NFC retention in unrefined hardwood pulp standard sheets increased NFC retention at higher grammage 9

10 NFC influence to dewatering 10

11 dewatering resistance SR [ SR] Influence of NFC to dewatering resistance (hardwood) R 2 = 0,96 R 2 = 1,00 R 2 = 0, dosage NFC-CTP/VTT [%] HW_UR HW_1. RP HW_2. RP significant increase in dewatering resistance by NFC 10 % (5 % retained) NFC in HW_UR meets the SR level of 2. RP approx. increase of 2 SR for 1 % dosage of NFC-CTP/VTT effect is not so dominant by adding NFC to CTMP or softwood 11

12 dewatering resistance SR [ SR] Options for reducing dewatering resistence - comparision of NFC effect and refining HW_UR 10 % NFC-CTP/VTT + RA only refining + RA ,015 0,03 0,06 0,12 0 0,015 0,03 0,06 0,012 dosage retention aid [%] retention aid reduced the unwanted effect of increase in SR both samples (10 % NFC & refined stock without NFC) nearly reached basic SR level at 16 12

13 NFC improvement of paper properties 13

14 tensile strength [N] Effect of grammage reduction R 2 = 1,00 R 2 = 0, grammage [g/m²] with 10 % NFC-CTP no NFC 3 sheet grammages tested 80, 60, 40 g/m² significant grammage reduction by NFC possible (concerning to tensile) example: 60 g/m² without NFC gave same tensile like 41 g/m² with NFC 14

15 E modulus DMA [MPa] Effect of NFC retention to strength properties grammage [g/m²] Veracell pulp Veracell 10 % NFC-CTP/VTT E modulus is a material constant so E modulus without NFC is nearly undependent from grammage increased E modulus at increased NFC retention 15

16 TENSILE Index [Nm/g] Tensile index - hardwood chemical pulp comparision of NFC, refining and starch effect unrefined pulp (hardwood) refined pulp (40 kwh/t) refined pulp (80 kwh/t) no/with ,5st 1,0st ,5st 1,0st ,5st 1,0st dosage NFC-CTP/VTT or starch (st) [%] increase of 60 % in tensile strength at 10 % NFC (5 % NFC retained) nearly the same effect of 3% NFC as with 0,5% starch please remember: NFC retention is 50 % of the dosage (complete starch retention & effect only in very clean water systems) 16

17 TENSILE Index [Nm/g] Tensile index - CTMP mechanical pulp CTMP unrefined starch effect R 2 = 0, NFC-CTP/VTT NFC-CTP/VTT 2% Starch dosage NFC [%] unrefined CTMP: very strong increase (56 %) of tensile by 6 (3) % NFC tensile increase was higher in comparison to hardwood pulp NFC and starch action to tensile was effective together 17

18 SCOTT BOND z-strength [J/m²] Scott Bond hardwood chemical pulp unrefined pulp (hardwood) refined pulp (40 kwh/t) refined pulp (80 kwh/t) no/with dosage NFC-CTP/VTT [%] generally significant increase in Scott Bond z-strength by NFC-CTP/VTT 18

19 dewatering resistance SR [ SR] Tensile index [Nm/g] Comparision of the pulp samples R 2 = 0,96 R 2 = 0,98 R 2 = 1, R 2 = 0,96 R 2 = 0,99 R 2 = 1, dosage NFC-CTP/VTT dosage NFC-CTP/VTT HW_UR CTMP SW_UR HW_UR + RA HW_UR CTMP SW_UR HW_UR + RA lowest dewatering resistence increase at softwood pulp highest tensile increase at CTMP pulp How to compare the samples in a best suitable way? 19

20 Comparision of the pulp samples NFC, refining and retention aid effects to tensile How to evaluate the effects observed on different pulps and the influence on paper making? Significant increase in strength properties, but at the same time unwanted loss in dewatering speed should be reached. Balancing of the positve strength effect and negative dewatering loss Δ tensile index [%] Δ SR [%] 20

21 tensile increase [%] by 1 % SR increase estimation from Literature estimation from Literature Comparision of the pulp samples NFC, refining and retention aid effects to tensile 5,0 4,5 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 0,0 HW-UR CTMP SW-UR NFC effect refining effect to 2. RP refining effect to 1.RP NFC + RA effect hardwood: softwood and CTMP: refining better than NFC NFC significantly better than refining 21

22 z-strength increase [%] by 1 % SR increase estimation from Literature estimation from Literature Comparision of the pulp samples NFC, refining and retention aid effects to z-strength 5,0 4,5 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 0,0 18,5 HW-UR CTMP SW-UR NFC effect refining effect to 1.RP refining effect to 2. RP NFC + RA effect hardwood and CTMP: softwood: refining better than NFC NFC significantly better than refining 22

23 Conclusion Use of NFC in bulk application before use NFC should be well dispersed the NFC retention in standard lab sheets is approx % (depending on the grammage) Dewatering behaviour NFC increased the dewatering resistance significantly dewatering speed loss depends from the used pulp there are sucessfull options to restore dewatering speed Paper properties generelly very strong improvement in tensile- and z-strength by NFC tensile hardwood: 5 % NFC-VTT comparable to refining with 40 kwh/t also significant increase of air flow resistance (stronger than refining) best results on unrefined softwood and CTMP pulp 23

24 Acknowledgment The research leading to these results received funding from the European Community s Seventh Framework Programme under Grant Agreement No Contact: Lutz Hamann Tel: Fax: Lutz Hamann@ptspaper.de Papiertechnische Stiftung (PTS) Pirnaer Str Heidenau Homepage: 24