TEMPO Oxidized Thermomechanical Pulp Used as a Paper Reinforcement

Transcription

1 TEMPO Oxidized Thermomechanical Pulp Used as a Paper Reinforcement David Myja 12, Eric Loranger 1, Estelle Léonard 3, Christophe Len 3, and Robert Lanouette 1 1 Lignocellulosic material research Centre, Université du Québec à Trois-Rivières, P.O. Box 500, Trois-Rivières, Québec, Canada, G9A 5H7 2 Ecole supérieure de chimie organique et minérale, 1 allée du réseau Jean-Marie Buckmaster, Compiègne, France 3 Sorbonne Universités, Université de Technologie de Compiègne, Ecole Supérieure de Chimie Organique et Minérale, EA 4297 Transformations Intégrées de la Matière Renouvelable, Centre de Recherche Royallieu, F Compiègne Cedex, France. ABSTRACT Thermomechanical pulp (TMP) was oxidized with 4-acetamido-TEMPO to a content of 400 mmol/kg in carboxylic groups in order to increase interfibers bonding potential. A fiber classification shows that the long fibers papers are twice stronger after oxidation. With an industrial fractionation process, two main fractions are produced, long R48 and short P48. Oxidized R48 mix with untreated P48 have better strength than the whole oxidized pulp. To investigate Kraft replacement in a TMP based paper grade with oxidized TMP, the Kraft pulp was replaced up to 30% without changing the proportion of non-oxidized TMP (70%). Two-thirds of the Kraft can be replace with low impact on the paper strength (loss of 20 to 30% in tear and tensile). The TEMPO oxidation can also achieve high carboxylic groups content (1500 mmol/kg) which when is mixed with low oxidized pulp to replace the whole Kraft, as shown a decrease of strength between 15 and 30%. In addition, a mineral filler retention analysis was done between two pulp: one with 70% of non-oxidized and 30% of highly oxidized TMP, the second with 100% non-oxidized TMP. The results showed a twice better retention for the mixed pulp, thus showing another potential benefit of TEMPO oxidized TMP in common mechanical grade papers. INTRODUCTION Cellulose fibers oxidation increase the interfiber bonding potential by forming aldehyde or carboxylic groups at the surface of the fibers. The 4-acetamido-(2,2,6,6-tetramethylpiperidine-1yl)oxyl (TEMPO) is an oxidant well known to produce carboxylic groups at the fibers surface[1, 2]. In the TEMPO oxidation cycle, sodium bromide and sodium hypochlorite are co-oxidants used to regenerate the TEMPO during the reaction at ph The TEMPO oxidation of native cellulose transforms selectively the primary alcohol of the cellulose into carboxylic groups[3]. A research on thermomechanical pulp with TEMPO oxidation shows that the optimum value of carboxylic groups per kilogram of dry pulp (mmol/kg) is around 400 mmol/kg in paper reinforcement [4].As the carboxylic groups content is further increased through TEMPO oxidation, the repulsion among the fibers increase due to the negatives charges concentration of the carboxylic groups. This highly oxidized pulp cannot be use directly for paper production because mechanical shearing will lead to the production of nanosized material [5, 6] who present many papermaking challenge. However, an addition of this highly oxidized pulp to a non-oxidized pulp can be beneficial for paper strength [7]. In Canada, more particularly in Quebec, papers industries produce mostly thermomechanical pulp. However, this pulp is not only composed of cellulose but also of hemicelluloses and lignin, which cause time related deterioration and weaker paper strength. In order to increase the TMP pulp strength, TEMPO oxidation seem interesting. The lignin presence may however, change the effect of the oxidation [8, 9, 10]. The TEMPO oxidation may not only oxidize the primary alcohol of the cellulose but also degrade the lignin in the pulp. In this preliminary study, we will explore the effect of TEMPO oxidized TMP in order to investigate a possible Kraft paper replacement or at least his replacement in some paper grade. A second objective would be to find a new way to valorise the TMP long fibers which have poor bonding capacity and then low strength properties [11, 12].

2 MATERIAL & METHODS Material To investigate the TEMPO oxidation of lignocellulosic pulp, the reaction is carried on primary and secondary thermomechanical pulp. Primary and secondary unbleached softwood thermomechanical were from Kruger paper mill in Trois-Rivières, Québec, Canada. The freeness of this two pulp are respectively 636 ml and 284 ml. A bleached softwood Kraft pulp was also used from Produits Forestiers Resolu in Saint-Félicien and at a freeness of 500 ml. The TEMPO and NaBr were purchased from Sigma Aldrich, the NaOCl and hydrogen peroxide from Fisher Scientific and the polymers (poly diallyldimethylammonium chloride (polydadmac) and polyacrylamide) from BASF. The clay used as filler for the mineral filler retention analysis came from Kruger Wayagamac in Trois-Rivières. Methods Bauer McNett classification A fiber classification relatively to their sized was made with a Bauer McNett with 14, 28, 48, 100 and 200 meshes screens. The fractionation enable this study to determine the impact of the TEMPO oxidation on each length range of TMP fibers. The fiber suspension was added into the first reactor then the fibers passed through the screens for 35 min. At the end of the operation, 6 fractions are recovered. The fractions are named with the letter P, follow by the number of a mesh which mean than the fibers passed through this screen, and/or the letter R, follow by the mesh number, which means the fibers were collected before this mesh. In order to get closer to possible industrial fractionation conditions, some fractions are recombined together to have two main fraction with the long fibers in one side and shorts in the other. The fractions R14, P14/R28 and P28/R48 are mixed together after the Bauer classification to have the fraction R48 with the longest fibers. The same is made with the smaller fiber fractions (P48/R100, P100/R200 and P200) to have the fractions P48/R200 (without the fraction P200) or P48 (with P200). TEMPO-mediated oxidation The TEMPO-mediated oxidation is conducted in a 5 L glass reactor at room temperature. First, 30 g of dry pulp are disintegrated in 2 L of deionized water. The required mass of TEMPO and NaBr were then diluted in 200 ml of water. For the low oxidation, 0.05 mmol of TEMPO per gram of dry pulp (mmol/g) and 0.30 mmol/g of sodium bromide are used. For the high oxidation, TEMPO and NaBr quantities are increased at respectively, 0.30 mmol/g and 1.80 mmol/g. 800 ml of water were finally added to adjust volume to 3 L. The ph maintain at 10.5 and controlled during the reaction with sodium hydroxide and hydrogen chloride at 0.1M. The reaction starts by the addition of the sodium hypochlorite. 3.1 mmol/g of NaOCl is added for the low oxidation and 18.6 mmol/g for the high. The sodium hypochlorite is gradually added during 30 min to easily maintain the ph at 10 and to limit any side reaction such as bleaching or peeling reaction. After the first 30 min, the suspension is continuously stirred during 1h to get a total reaction time of 90 min. The reaction is then stopped by an addition of 100 ml of hydrogen peroxide at 3%. Finally, the suspension is filtered, the dryness of the pulp measured, then stocked at 6 C until further use. This protocol is the usual technique for TEMPO oxidation [4, 8] with reagents adjusted for the thermomechanical pulp used. Handsheet preparation and test All the Bauer McNett fractions were used to make handsheets. Every handsheets were fabricated according to the TAPPI Standard Method T205. Two mechanical tests, to measure tensile and tear index, were made on the handsheets according to TAPPI Standard Method T220. Retention analysis Mineral filler (clay) retention for a mix of high TEMPO oxidized TMP with non-oxidized (respectively 30%/70%) was compared to a non-oxidized TMP. The mineral filler retention analysis compared the capacity to retain clay while making handsheets. The usual pulp suspension is prepared then, a given amount of clay is added to the suspension. Before making the handsheets, the coagulant (polydadmac) then the flocculent (polyacrylamide) are added to the volume of suspension needed to make one sheet. For each polymer, a dosage of 1 kg per ton of dry pulp was used. The suspension containing the pulp, the clay and polymers is finally poured in a British handsheet former to make one sheet. The technique is repeated until having enough handsheets for mechanical testing. To measure the ash content of the paper, few grams of paper are first putted in an oven a 105 C for 12 h to determine the dry weight of paper. Then the paper is left at 500 C for 12 h which enable the ash weight measurement, thus giving the ash content of the sheet.

3 RESULTS AND DISCUSSION TEMPO oxidation effect on tensile and tear index When the TEMPO oxidation is carried on every pulp sample, an increase of the tensile and the tear indices are observed (Figure 1 and 2). Fiber bonding has the most effect on the tensile index. As the carboxylic groups, increase the bonding potential of the fibers, improved paper cohesion should be observed. From our results, the tensile strength (Fig. 1) was indeed improved with the TEMPO oxidation. Moreover, the short fibers have already a good tensile strength without the oxidation and according to the results, it looks interesting to investigate the oxidation on the long fibers for a paper reinforcement usage. Even if the short fibers can be improved, for a better strength the real improvement can be obtained from the long fiber treatment. The tear index results confirm this observation (Fig. 2). Indeed, the best improvements are on the long fibers too. The tear strength is not only affected by the cohesion between the fibers but by the fibers intrinsic strength too. The increase of the carboxylic groups content can then improve the bonding potential between the fibers and the intrinsic strength of fibers or at least improve the cohesion without a decrease of intrinsic strength. The secondary pulp, which was under a second refining stage, has more free microfibrils at the fibers surface. Even without the oxidation, this microfibrils gives better properties to the paper. After the TEMPO oxidation, the carboxylic groups on the microfibrils enable to improve even more the bonding potential between fibers and microfibrils and then, get a better strength. Figure 1 : Tensile Index of each fraction without and with TEMPO oxidation (WP : whole pulp) Figure 2 : Tear Index of each fraction without and with TEMPO oxidation (WP : whole pulp) According to those first tests, the TEMPO oxidation seems to be more effective on the long fibers which is interesting for the second objective of the research. One hypothesis is the various chemical composition between fractions. It seems that lignin is more concentrate in short fibers fraction after the classification that is why the long fibers, with more exposed cellulose, has a better response to the oxidation. Moreover, the secondary pulp with microfibrils on fibers surface gives better strength and are more reactive with the TEMPO oxidation. From our results, the secondary

4 pulp seems to be more effective with the TEMPO oxidation than the primary pulp. Even then, the primary pulp will still be use in further experiments for comparison purpose. Partial pulp oxidation According to the previous results, oxidation in this part of the study will be carried out on the whole pulp (WP) or long fibers fractions (R48, a mix of R14, P14/R28 and P28/R48) of primary and secondary pulp. The oxidized pulp is then mix back with the non-oxidized short fibers following the original proportion to compare different pulp oxidation strategies. The same experiment was made without the oxidation to isolate the washing effect who might occur during fractionation. This two pulps, partially oxidized (PO) and recomposed non oxidized (RNO), are compared to the whole non-oxidized pulp (NO) and totally oxidized (O) in Figure 3. Figure 3 : Tensile and tear index for primary and secondary TMP NO (non oxidized), RNO (recomposed non oxidized), PO (partially oxidized) and O (oxidized) On figure 3, the tensile and tear indexes of the partially oxidized pulp are usually better than the whole oxidized pulp. Focusing the oxidation on the long fiber seems to be more effective because, as shown previously, the long fibers papers initial strengths are weak but they are improved with the oxidation. However, a comparison of the non-oxidized pulp and the recomposed non oxidized pulp put forward a washing effect. During the Bauer McNett classification, a part of free lignin can be lost which explain an improvement of the strength without the oxidation. One more time, the same observation as before could be made between the primary and secondary TMP, the surfaces microfibrils enable better mechanical strength. Kraft replacement in paper grade The main objective of studying TEMPO oxidation on TMP was to produce a pulp which could be compared to a Kraft pulp in strength. It is common knowledge that physical properties of TMP handsheets are clearly lower than Kraft paper alone. However, some grades of pulp are mostly composed of TMP and an addition of Kraft pulp. The objective is then to replace as much Kraft as possible in a base mix (70% of secondary non oxidized TMP and 30% of Kraft pulp) by different oxidized TMP, with the smallest compromise on physical strength. To replace the Kraft pulp, the oxidized secondary whole pulp (Sec WP) and the oxidized secondary long fibers (Sec R48) are used. As shown before, the secondary pulp is more interesting for a TEMPO treatment. The fractions are choose according to the previous results and to further evaluate the potential valorisation of the TMP long fibers with the TEMPO oxidation. Different amount of the Kraft was replaced: 1/3 of the Kraft (10% in the whole mix), 2/3 of the Kraft (20% in the whole mix), 100% of the Kraft (30% in the whole mix) and their effect on tensile and tear indexes shown in Figure 4.

5 Figure 4 : Tensile and tear index of different mixes for Kraft replacement Results on Figure 4 shows that even a small amount of Kraft replacement decreases the handsheets strengths. None of the sample has the same properties as the Kraft pulp. However, one third of the Kraft pulp could be replaced with a relatively small decrease of the tensile ( -12%) and tear indexes ( -7%). A higher amount of the Kraft can be replaced too but a higher decrease (-20 to -30%) of strengths will be observed. We can also see that using the whole pulp or only the long fibers don t have a real impact on the mechanical resistance when a small amount of Kraft is in the mix. In that case, the short fibers could be removed for other application thanks to the improvement of the long fibers. According to this observation, the oxidized TMP with carboxylic groups at 400 mmol/kg could not efficiency replace the Kraft in this grade. The worst decrease is for tensile strength so the fibers cohesion is really affected by the Kraft replacement. In order to counterbalance this phenomenon and to reduce this effect on a thermomechanical pulp, a highly oxidized secondary pulp (with carboxylic groups at 1500 mmol/kg) could be considered. A mechanical treatment, in a domestic blender, will reduce fibers length and as shown in the first part of this study, short fibers are better for fibers cohesion. So, additionally to the high content of carboxylic groups which increase the potential bonding between the fibers, it is another benefits to add short fibers. Following this hypothesis, the Kraft replacement is then further investigated with highly oxidized secondary TMP as Kraft replacement (Fig. 5). In this figure, the Kraft pulp is completely removed and replaced by different amount of secondary whole pulp with low oxidation level (Sec LO WP) and secondary highly oxidized whole pulp (Sec HO WP). The amount of secondary non oxidized TMP is still the same (70%) in the mix. Figure 5 : Tear index of different mix (LO : low oxidation level, HO : high oxidation level) According to the figure 5, using a high oxidation level on the pulp does not achieve the same properties as a 70% Sec NO WP / 30% Kraft mix. However, the mix with 70% Sec NO WP / 20% Sec LO WP / 10 Sec HO WP has globally the same strength than the mix with 70% Sec NO WP / 10% Kraft / 20% Sec LO WP shown in Figure 4. Thus, the replacement of this small amount of Kraft seems to be possible with the highly oxidized TMP pulp. Increasing the amount of highly oxidized pulp in the mix increase the tensile index of the sheets. The fibers of this pulp are smaller, because of the mechanical treatment, and highly charged, because of the oxidation, so the cohesion in the pulp is better. However, a high amount of highly oxidized pulp in a paper could be a problem because of the high surface charge which will have a repulsive effect between the fibers. This high content of negative charge has repulsive effect

6 between the surfaces microfibrils, which decreases the intrinsic strength of the fiber and then the tear strength of the paper. The use of highly oxidized pulp seems to be interesting for Kraft replacement as reinforcement pulp. However, we could not replace the Kraft without losses in some strength but the proportion of non-oxidized pulp was not changed during the tests. A decrease of this fraction with an increase of low and highly oxidized pulp may be able to get the same strength than a mix with Kraft. Further investigation should be made to evaluate the efficiency of oxidized TMP for Kraft replacement. This tests shows at least an interesting effect of the highly oxidized thermomechanical pulp for paper reinforcement. The high content of charge could also have other properties on the paper. One interesting analysis is the filler retention capacity. Filler retention analysis For this study, two pulp are compared: a whole secondary non-oxidized pulp (Sec NO WP) and a mix of 70% of the whole secondary non-oxidized pulp and 30% of the whole secondary highly oxidized pulp (Sec NO WP / Sec HO WP). Different amount of clay (the mineral filler used) are added to the pulp then mechanicals properties and ash content are measured. The first retention pass is then calculated according the added clay and the ash content. Results are then reported in Table 1. The most important result of the Table 1 is the increasing first retention pass with the highly oxidized pulp. Twice more clay remain in the pulp and the first pass retention can go almost 90%. The highly oxidized pulps charge content seems to really affect the filler retention ability of the pulp. The behavior of the mixed pulp with the coagulant and the flocculent are better, thanks to the charge of the pulp, and can explain the high increase of clay retention. The filler content is undeniably higher, but physical testing was done to see any detrimental effect that could arise from this situation. Table 1 : Physical properties of paper with different clay content First retention Tensile index Tear index Pulp Added clay (%) Ash content (%) pass (%) (N.m/g) (mn.m 2 /g) N.A Sec WP NO N.A Sec WP NO / Sec WP HO (70/30) According to the mechanical properties in Figure 6 or table 1, the clay seem to reduce the final mechanical strength. The tensile index decrease in the same way with and without the highly oxidized pulp when the clay content increases. However, as seen previously, the highly oxidized pulp improves the cohesion in the sheet and then a low increase of the tensile index in comparison to the whole non-oxidized pulp can be observed. For the tear index, the strength without clay is better for the non-oxidized pulp but when a certain content of clay is retained, the tear strength is better for the mix with the highly oxidized pulp. With a low filler content, the non-oxidized pulp has a better tear strength because of the long fibers good intrinsic strength. When the amount of filler increase, the clay interferes negatively the fibers cohesion which explain the tear strength evolution. This phenomenon is less pronounced for the mixed pulp because of the high charge and short length of the highly oxidized fraction which enable to have a more stable cohesion in the paper. e

7 Figure 6 : Tensile and Tear indices evolution with ash content Other tests should be made to better understand the different effect of the highly oxidized pulp for filler retention but this quick study shows a real potential of using this kind of pulp for pigment retention. In general, the decreasing trend slope are the same but tensile is increased by about 25% at the same filler content while tear seem to be relatively independent on the highly oxidized pulps. CONCLUSION The TEMPO oxidation, with NaBr/NaOCl at ph , of thermomechanical pulp give interesting properties to the paper. Firstly, the pulp at 400 mmol/kg of carboxylic groups increase the strength of the paper. The benefits are better for the long fibers that is why an oxidation of the long fibers followed by a recombination with the shorts, give even better strength to the paper. A valorisation of the TMP long fibers is then possible with the TEMPO oxidation. Secondly, in order to replace Kraft pulp in some paper grade, a mix of low (400 mmol/kg) and high (1500 mmol/kg) oxidation levels on TMP could be effective if a small loss of strength is acceptable. This loss can probably be reduced or minimized by an optimisation of the proportion of each fraction (non oxidized, low oxidation and high oxidation levels). Finally, the analysis of mineral filler retention has highlighted the fact that the highly oxidized pulp give a much better retention property of the pulp in addition to improving the tensile at the same filler content. Other experiments should be made to determine the full potential of the highly oxidized pulp for paper reinforcement but our study as clearly show that oxidized TMP has a great potential. ACKNOWLEDMENTS The authors you like to thank the National Sciences and Engineering Council of Canada (NSERC) for their financial support and M. Alain Marchand for his involvement in this project. REFERENCES 1 T. Saito and A. Isogai, TEMPO-Mediated Oxidation of Native Cellulose. The Effect of Oxidation Conditions on Chemical and Crystal Structures of the Water-Insuluble Fractions, Biomacromolecules 2004, 5, A. E. J. d. Nooy, A. E. Besemer and H. v. Bekkum, Highly selective nitrixyl radical-mediated oxidation of primary alcohol groups in water-soluble glucans, Carbohydrate research 1995, T. Saito, Y. Okita, T. T. Nge, J. Sugiyama and A. Isogai, TEMPO-mediated oxidation of native cellulose: Microscopic analysis of fibrous fractions in the oxidized products, Carbohydrate Polymers 2006, 65, L. Mao, K. Law, C. Daneault and F. Brouillette, Effects of Carbonyl Content on the Characteristics of TMP Long Fibers, Industrial Enggineering Chemistry Research 2008, 47, A. Isogai, T. Saito and H. Fukuzumi, TEMPO-oxidized cellulose nanofibers, Nanoscale 2011, 3, R. Kuramae, T. Saito and A. Isogai, TEMPO-oxidized cellulose nanofibrils prepared from various plant holocelluloses, Reactive and Functional Polymers 2014, 85,

8 7 I. Kajanto and M. Kosonen, The potential use of micro- and nano-fibrillated cellulose as a reinforcing element in paper, Journal of Science & Technology for Forest Products and Processes 2012, 2, Y. Okita, T. Saito and A. Isogai, TEMPO-mediated oxidation of softwood thermomechanical pulp, Holzforschung 2009, 63, P. Ma, S. Fu, H. Zhai, K. Law and C. Daneault, Influence of TEMPO-mediated oxidation on the lignin of thermomechanical pulp, Bioresource Technology 2012, 118, J. L. Roux, C. Daneault and B. Chabot, Acidic groups in TMP oxidized fibres by TEMPO to improve paper strength properties, Pulp and Paper Canada 2006, 107, K. N. Law, Revisiting the Properties of Thermomechanical Pulp, Revue ATIP 2004, 58, K. N. Law, An Autopsy of Refiner Mechanical Pulp, Pulp and Paper Canada 2005, 106, 37.

9 TEMPO OXIDIZED THERMOMECHANICAL PULP USED AS A PAPER REINFORCEMENT PRESENTED BY : DAVID MYJA PH.D. STUDENT UNIVERSITÉ DU QUÉBEC À TROIS-RIVIÈRES CO-AUTHORS : ÉRIC LORANGER, ESTELLE LÉONARD, CHRISTOPHE LEN, ROBERT LANOUETTE 1

10 OUTLINE Objectives Material : thermomechanical pulp properties Pulp treatment : Bauer McNett classification 4-acetamido-TEMPO oxidation Results : TEMPO oxidation effect on TMP fractions TEMPO oxidized pulp in different paper grades Other properties with TEMPO oxidized fibers Conclusions 2

11 OBJECTIVES 1. Improve thermomechanical pulp (TMP) properties to replace Kraft Increase tensile and tear resistance Improve other pulp properties 2. Valorise TMP long fibers with low bonding capacity and low strength properties 3

12 THERMOMECHANICAL PULP PROPERTIES Primary unbleached TMP Secondary unbleached TMP Bleached Kraft 1 Bleached Kraft 2 Bleached Kraft 3 Freeness (ml) Freeness (ml) Tensile index (N.m/g) 9,1 26,4 Tensile index (N.m/g) 107,2 103,4 93,5 Tear index (mn.m 2 /g) 4,3 8,2 Tear index (mn.m 2 /g) 9,8 10,5 11,3 4

13 BAUER MCNETT CLASSIFICATION STUDIED FRACTION Whole pulp (WP) P200 P100/R200 P48/R100 P28/R48 P14/R28 R14 Short fibers Long fibers P14/R28 P28/R48 P48/R200 (P48/R100 + P100/R200) R48 (R14 + P14/R28 + P28/R48) 5

14 CELLULOSE OXIDATION BY 4-ACETAMIDO-TEMPO 4-acetamido-TEMPO 6

15 EFFECT OF TEMPO OXIDATION ON FIBERS BONDING COO OH COO OH OH OH COO - COO OH COO OH COO OH COO OH COO OH OH COO OH COO OH OH COO OH COO OH COO OH OH COO OH COO OH OH COO OH COO OH COO OH COO OH 400 mmol High of carboxylic oxidation groups at 1500 per mmol/kg of dry pulp* * L. Mao, K. Law, C. Daneault and F. Brouillette, Effects of Carbonyl Content on the Characteristics of TMP Long Fibers, Ind. Eng. Chem. Res. 2008, 47,

16 HANDSHEETS AND MECHANICAL TESTS PROCEDURES Handsheets were made according to the TAPPI Standard Method T205. Mechanical tests were made following the TAPPI Standard Method T220 8

17 TEMPO OXIDATION EFFECT ON TMP FRACTIONS Initial pulp Bauer McNett classification TEMPO oxidation : Prim Sec WP P14/R28 P28/R48 P48/R200 Handsheets & tests 9

18 TEMPO OXIDATION EFFECT ON TMP FRACTIONS TENSILE INDEX Tensile index (N.m/g) % Prim WP % Prim P14/R28 +86% Prim P28/R48 +41% Prim P48/R200 +6% 26.4 Sec WP % Sec P14/R28 +89% Sec P28/R48 +23% Sec P48/R200 Without oxidation With oxidation Kraft reference : N.m/g 10

19 TEMPO OXIDATION EFFECT ON TMP FRACTIONS TEAR INDEX Tear index (mn.m 2 /g) % 4.3 Prim WP % Prim P14/R % Prim P28/R48 +20% Prim P48/R % Sec WP % Sec P14/R28 +85% 4.1 Sec P28/R48 +9% Sec P48/R200 Without oxidation Kraft reference : 10.5 mn.m 2 /g With oxidation 11

20 TEMPO OXIDATION EFFECT ON TMP FRACTIONS - RESULTS Oxidation more effective on the long fibers Better effect of TEMPO oxidation on secondary pulp for tensile index but still a weaker strength compared to Kraft pulp 12

21 TEMPO OXIDATION OF THE LONG FIBERS Initial pulp TEMPO oxidation : Prim Sec R48 Recombination of the pulp Pulp partially oxidized (PO) Bauer McNett classification R48 and P48 separation then recombination Handsheets & tests 13

22 TEMPO OXIDATION OF THE LONG FIBERS TENSILE & TEAR INDEX Tensile index (N.m/g) Prim NO 13.1 Prim RNO Prim PO Prim O Sec NO Sec RNO 32.0 Sec PO Sec O Tear index (mn.m 2 /g) Kraft reference : - tensile : N.m/g - tear : 10.5 mn.m 2 /g Tensile Tear 14

23 TEMPO OXIDATION OF THE LONG FIBERS RESULTS Better resistance when focusing oxidation on long fibers Washing effect during the Bauer McNett classification Free lignin loss Resistances lower than Kraft 15

24 TEMPO OXIDATION OF PULP FOR PAPER GRADES Initial pulp Secondary non oxidized whole pulp (Sec WP NO) Kraft Bauer McNett classification TEMPO oxidation : Sec WP R48 Pulp mixing Handsheets & tests 16

25 TEMPO OXIDATION OF PULP FOR PAPER GRADES Tensile index (N.m/g) NO (70%) Kraft (20%) WP (10%) NO (70%) Kraft (20%) R48 (10%) NO (70%) Kraft (10%) WP (20%) Tensile NO (70%) Kraft (10%) R48 (20%) Tear 24.6 NO (70%) WP (30%) NO (70%) R48 (30%) Tear index (mn.m 2 /g) Reference mix : Sec WP NO (70%) / Kraft (30%) 17

26 LOW & HIGH TEMPO OXIDATION OF PULP FOR PAPER GRADES Initial pulp Secondary non oxidized whole pulp (NO) Pulp mixing Bauer McNett classification TEMPO oxidation : Low oxidation (LO) : 400 mmol/kg High oxidation (HO) : 1500 mmol/kg Sec WP Handsheets & tests 18

27 Tensile index (N.m/g) LOW & HIGH TEMPO OXIDATION OF PULP FOR PAPER GRADES NO (70%) LO (30%) 9.8 Tensile Tear NO (70%) LO (25%) HO (5%) Sec WP NO (70%) Sec WP LO (20%) Kraft (10%) NO (70%) LO (20%) HO (10%) NO (70%) HO (30%) Tear index (mn.m 2 /g) Reference mix : Sec WP NO (70%) / Kraft (30%) 19

28 TEMPO OXIDATION OF PULP FOR PAPER GRADES - RESULTS Any Kraft replacement will induce lower strength Using the whole pulp or the long fibers make no difference in the sheet Possible valorization of the long fibers when short ones are used in other applications 20

29 TEMPO OXIDATION OF PULP FOR PAPER GRADES - RESULTS At a low Kraft content, a replacement by highly oxidized pulp is possible Sec WP NO (70%) / Kraft (10%) / Sec R48 LO (20%) and Sec WP NO (70%) / SecWPHO(10%)/ Sec WP LO (20%) An increase of oxidized pulp by an optimisation of proportion could enable a better Kraft replacement and get better strength with only TMP in this grade 21

30 OTHER PROPERTIES WITH TEMPO OXIDIZED FIBERS Initial pulp Secondary non oxidized whole pulp (Sec WP NO) Mineral filler : clay Handsheets & tests TEMPO oxidation : High oxidation (HO) : 1500 mmol/kg Sec WP Pulp mixing Polymers addition : Coagulant Flocculant *Polymers : Coagulant : polydadmac / Flocculant : polyacrylamide 22

31 OTHER PROPERTIES WITH TEMPO OXIDIZED FIBERS Pulp Sec WP NO Added clay (%) Ash content (%) Filler first pass retention (%) 0 0,44 N.A. 21,6 8,50 39,4 41,0 17,07 41,6 56,1 28,36 50,6 0 2,10 N.A. Sec WP NO (70%) Sec WP HO (30%) 21,5 29,25 89,5 41,0 32,95 80,4 56,2 44,56 79,3 23

32 35.0 OTHER PROPERTIES WITH TEMPO OXIDIZED FIBERS Tensile Sec WP NO Tensile Sec WP NO / Sec WP HO 24.0 Tensile Index (N.m/g) N.m/g 12 % Tear Sec WP NO Tear Sec WP NO / Sec WP HO Tear Index (mn.m 2 /g) Ash content (%)

33 OTHER PROPERTIES WITH TEMPO OXIDIZED FIBERS -RESULTS At a given filler addition, twice more clay can be retained with the highly oxidized fraction Until 90% of filler retention At a given ash content, tensile resistance is about 6 N.m/g stronger Highly oxidized fraction give better strength 25

34 CONCLUSIONS TEMPO oxidation effect on TMP fractions : Global strength improvement with the TEMPO oxidation Oxidation more effective on long fibers TEMPO Oxidation of the long fibers : Resistances is too low to replace paper with Kraft pulp 26

35 CONCLUSIONS Used of TEMPO oxidized pulp in paper grades : Enable a low Kraft content replacement in paper grades Possibly the same strength with an optimisation of the pulps ratio Long fibers or whole pulp make no difference in a paper grades Other properties with TEMPO oxidized fibers : Better filler retention For the same filler addition, twice better retention compared to mix without oxidized pulp (Up to 90 %) Better tensile resistance at a given ash content 27

36 THANK YOU PRESENTED BY DAVID MYJA PH.D. STUDENT UNIVERSITÉ DU QUÉBEC À TROIS RIVIÈRES 28