Application of DSA to improve strength of thermomechanical pulp blended paper

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Cheol Woo Lee ◽  
Jeong Yong Ryu
Keyword(s):  
Kraft Pulp ◽  
High Strength ◽  
Thermomechanical Pulp ◽  
Paper Strength ◽  
Bleached Kraft Pulp ◽  
Degree Of Refining ◽  
Strength Improvement

Abstract A more efficient application of a dry strength agent (DSA) was investigated to improve the strength of thermomechanical pulp (TMP) blended paper. Strength improvement by DSA application was more effective for hardwood bleached kraft pulp (Hw-BKP) than TMP. The degree of strength improvement of DSA further increased with the increasing degree of refining of Hw-BKP. The strength of the paper was decreased by the fines fractionation of TMP, but the strength improvement efficiency of DSA for the fines fractionated TMP increased. In order to increase the strength of TMP mixed paper using DSA, it is expected that DSA should be adsorbed only to Hw-BKP with high strength improvement efficiency, not TMP fines. When the DSA was mixed with Hw-BKP before contact with other stocks, it was confirmed that the effect of improving the strength by the DSA is the best. The strength improving effect increased as TMP fines were removed. Therefore, to improve the strength of the paper containing TMP in Hw-BKP by adding a DSA, it is preferable to selective apply the DSA to Hw-BKP while blending only the fibers of TMP by fractionation.

Paper dry strength improvement by xyloglucan addition: Wet-end application, spray coating and synergism with borate

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Lage Ahrenstedt ◽  
Antti Oksanen ◽  
Kristian Salminen ◽  
Harry Brumer
Keyword(s):  
Kraft Pulp ◽  
Spray Coating ◽  
Fibre Surface ◽  
Thermomechanical Pulp ◽  
Paper Strength ◽  
Paper Properties ◽  
Chemical Pulps ◽  
Spray Solution ◽  
Cross Links ◽  
Strength Improvement

Abstract The polysaccharide xyloglucan as a wet-end additive improves paper properties. In the present study, paper strength improvement was analysed for dry handsheets made from chemical, mechanical and recycled pulps coated with xyloglucan in a spray application. Results are compared with sheets made from the same pulps treated with xyloglucan in the wet-end. Kraft pulp handsheets of bleached hardwood and softwood showed significant improvements of tensile, tear and Z-strength by xyloglucan spray treatment versus wet-end application, whereas handsheets of de-inked and thermomechanical pulp were improved only slightly. In both wet-end and spray applications, the effect of xyloglucan addition was intimately related to the presence of non-cellulosic components on the fibre surface. Further strength improvements were obtained for chemical pulps by addition of borax to the spray solution, which were likely to be due to the formation of borate-mediated xyloglucan cross-links. Spray coating of xyloglucan, with or without borax, thus represents a potential new application of this polysaccharide to increase paper dry strength.

scholarly journals High strength paper from high yield pulps by means of hot-pressing

2020 ◽  
Vol 35 (2) ◽  
pp. 195-204
Author(s):  
Tove Joelsson ◽  
Gunilla Pettersson ◽  
Sven Norgren ◽  
Anna Svedberg ◽  
Hans Höglund ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Hot Pressing ◽  
Kraft Pulp ◽  
High Strength ◽  
Strength Properties ◽  
High Yield ◽  
Thermomechanical Pulp ◽  
Wet Strength ◽  
Chemical Pulp ◽  
Bleached Kraft Pulp

AbstractThe hypothesis is that it should be possible to modify papermaking conditions in line with the softening properties of high yield pulp fibres and achieve similar strength properties to conventional chemical pulp based paper. We therefore investigated the rheological and physical properties of high yield pulp based papers during hot-pressing. Our results confirm that increased temperature combined with sufficient pressure enables permanent densification by softening of lignin, producing very high tensile strength. This treatment also significantly improved the wet tensile strength in comparison to bleached kraft pulp without using wet strength agents. The high yield pulps used here were spruce based thermomechanical pulp, chemi-thermomechanical pulp, and high temperature chemi-thermomechanical pulp, and birch-aspen based neutral sulphite semi chemical pulp, with spruce-pine based bleached kraft pulp as reference. Rapid Köhten sheets of 150\hspace{0.1667em}\text{g}/{\text{m}^{2}} and 50 % dryness were hot-pressed in a cylinder-press at 20–200 °C, 7 MPa, and 1 m/min. The mechanical properties showed great improvements in these high yield pulp papers, with tensile index increased to 75 kNm/kg and compression strength index to 45 kNm/kg; levels close to and better than bleached kraft. Wet strength increased to 16 Nm/g compared to 5 Nm/g for bleached kraft.

scholarly journals Paper strength improvement by inclusion of nano-lignocellulose to Chemi-thermomechanical pulp

2014 ◽  
Vol 29 (2) ◽  
pp. 309-316 ◽  
Author(s):  
Sinke H. Osong ◽  
Sven Norgren ◽  
Per Engstrand
Keyword(s):  
Strength Properties ◽  
Thermomechanical Pulp ◽  
Paper Strength ◽  
Chemical Pulp ◽  
Bleached Kraft Pulp ◽  
Tear Index ◽  
Air Resistance ◽  
Thermomechanical Pulping ◽  
Pulp Fibres ◽  
Sheet Density

Abstract So far, chemical pulp fibres have been utilized as conventional stock materials for nanocellulose production. The main aim of this work is to use stock materials from mechanical or chemi-thermomechanical pulping process to produce lignin containing nanofibres, which are referred to as nano-ligno-cellulose (NLC) in this study. The present study shows the influence on handsheets of chemi-thermomechanical pulp (CTMP) fibres blended with NLC. For comparison reasons, nanocellulose (NC) from bleached kraft pulp (BKP) was produced in a similar approach as NLC. Both the NLC and the NC were blended with their respective pulp fibres and their corresponding handsheets properties were evaluated with respect to sheet density. It was found that the handsheets of pulp fibres blended with NLC/NC improved the mechanical properties of handsheets with only a slight effect in relation to the sheet density. Improvements in strength properties of handsheets such as z-strength, tensile index, tear index, burst index, Emodulus, strain at break, tensile stiffness, air resistance were observed.

Selective addition of C-PVAm to improve dry strength of TMP mixed tissue paper

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jin Ho Seo ◽  
Kwang Seob Lee ◽  
Tae Joo Lee ◽  
Jeong Yong Ryu
Keyword(s):  
Kraft Pulp ◽  
Reaction Rate ◽  
Thermomechanical Pulp ◽  
Centrifugal Forces ◽  
Physical Strength ◽  
Tissue Paper ◽  
Tensile Index ◽  
Bleached Kraft Pulp ◽  
Selective Addition ◽  
High Reaction Rate

AbstractDuring the manufacture of low basis weight tissue paper, it is difficult to efficiently use the dry strength agent (DSA) because a large amount of DSA adsorbed fines releases in forming roll by centrifugal forces. In this study, cationic polyvinylamine (C-PVAm) was used as a DSA in an environment where the retention of fines was weak. Addition of C-PVAm to the thermomechanical pulp (TMP) or TMP mixed with softwood bleached kraft pulp (SwBKP) improved the turbidity of filtrate from sheet former, however, the strength of handsheet paper was similar to that without C-PVAm. When C-PVAm was selectively added to SwBKP as much as 4 %, the tensile index could be improved by approximately 10.6 % without changing the retention of fines. In addition, C-PVAm added before the beating of SwBKP showed better results than C-PVAm added after the beating in terms of fines retention, tensile index, and formation. In particular, the tensile index was improved about 7.7 % by adding of C-PVAm 4 % as is before beating of SwBKP. Consequently, it was found that C-PVAm with a high reaction rate can be added before beating of SwBKP to improve the physical strength.

Novel blend of biorenewable wet-end paper agents

TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 41-48 ◽  
Author(s):  
CHEN GONG ◽  
ASIF HASAN ◽  
BILJANA M. BUJANOVIC ◽  
THOMAS E. AMIDON
Keyword(s):  
Tensile Strength ◽  
Kraft Pulp ◽  
Sugar Maple ◽  
Lignin Content ◽  
Weight Ratio ◽  
Hot Water ◽  
Thermomechanical Pulp ◽  
Cationic Starch ◽  
Wet Strength ◽  
Bleached Kraft Pulp

Recent studies have shown potential for a designed biorefinery product, polylactic acid (PLA), to increase the strength-to-weight ratio of paper produced from conventional kraft pulp and kraft pulp made from hot-water extracted hardwoods (biorefinery pulp). These results indicated that, after surface-treatment with 2 % PLA (per ovendry [o.d.] fiber basis), paper made from sugar maple biorefinery pulp could be equivalent to or even greater in strength than paper made from sugar maple conventional kraft pulp, while retaining its higher bulk. In the current study, we present the results of reinforcement of the pulps with PLA applied in the wet-end in combination with a known environmentally friendly dry strength agent, cationic starch. The preliminary results obtained with amylopectin-based starch of relatively high nitrogen content (starch B) were encouraging since strength, including wet strength and stretch, of paper reinforced with a blend of 0.5% starch B and 0.5% PLA was higher than strength of paper reinforced with 1% starch B. Moreover, based on the compatible strengths of paper reinforced with 0.6 % PLA-starch B blend (1/5) and of paper reinforced with 1% starch B, we hypothesize that there is a synergistic effect of PLA and starch B on tensile strength of paper. The hypothesis was tested using pulps of different lignin content (Norway spruce thermomechanical pulp [TMP], hardwood unbleached kraft pulp, and softwood bleached kraft pulp). Tensile strength increased for papers made from these pulps. The effect was pronounced in the case of lignin-rich pulps, where tensile strength in the presence of 0.6% PLA-starch blend (1/5) exceeded that in the presence of 1% starch B. This result is in accordance with a higher attraction of lignin-rich fibers to hydrophobic PLA and indicates a promising approach in increasing strength-to-weight ratio of paper made from relatively hydrophobic pulps like TMP or unbleached kraft pulp. Accordingly, paper made from unbleached hardwood kraft pulp with 0.6% PLA-starch B blend (1/5) exhibited an improved resistance to water penetration.

Application of Advanced Wet-End System Using Carboxymethyl Cellulose to Mixed Pulp Slurries for Wood-Containing Paper Production

TAPPI Journal ◽  
2009 ◽  
Vol 8 (5) ◽  
pp. 32-37
Author(s):  
TOMOHISA GONDO ◽  
MASASUKE WATANABE ◽  
OSAMU KITAO ◽  
AKIRA ISOGAI
Keyword(s):  
Carboxymethyl Cellulose ◽  
Kraft Pulp ◽  
Structural Changes ◽  
Aluminum Sulfate ◽  
Negative Charge ◽  
Thermomechanical Pulp ◽  
Pulp Fibers ◽  
Anionic Sites ◽  
Bleached Kraft Pulp ◽  
Modification Technique

A pulp modification technique using carboxymethyl cellulose (CMC) at the wet end was applied to mixed pulp slurries containing softwood bleached kraft pulp (SBKP), deinked pulp (DIP), and hydrogen peroxide-bleached thermomechanical pulp (TMP). Introduction of anionic sites by adsorption of the added CMC molecules on the fibers was confirmed by an increase in negative charge of the mixed pulp fibers. Sizing degree of the handsheets prepared with 2% aluminum sulfate and 0.2% rosin dispersion size was clearly improved by 0.1% CMC addition. On the other hand, we observed no significant differences in rosin size content between the handsheets prepared with and without CMC. These results indicate that some mechanisms other than enhancement of rosin size retention may have brought about the clear improvement of sizing performance by the CMC addition. Changes in distribution of rosin size components or some structural changes of rosin size components in the handsheets by the CMC addition may be candidates for sizing development. The CMC addition technique at the wet end is, therefore, also applicable to mixed pulps containing DIP and TMP.

A novel predictive method for filler coflocculation with cellulose microfibrils

TAPPI Journal ◽  
2019 ◽  
Vol 18 (11) ◽  
pp. 653-664
Author(s):  
IGNACIO DE SAN PIO ◽  
KLAS G. JOHANSSON ◽  
PAUL KROCHAK
Keyword(s):  
Negative Impact ◽  
High Strength ◽  
Strength Properties ◽  
Cellulose Microfibrils ◽  
Paper Strength ◽  
Flow Loop ◽  
Cationic Starch ◽  
Reflectance Measurement ◽  
Drainage Rate ◽  
Complete Study

Different strategies aimed at reducing the negative impact of fillers on paper strength have been the objective of many studies during the past few decades. Some new strategies have even been patented or commercialized, yet a complete study on the behavior of the filler flocs and their effect on retention, drainage, and formation has not been found in literature. This type of research on fillers is often limited by difficulties in simulating high levels of shear at laboratory scale similar to those at mill scale. To address this challenge, a combination of techniques was used to compare preflocculation (i.e., filler is flocculated before addition to the pulp) with coflocculation strategies (i.e., filler is mixed with a binder and flocculated before addition to the pulp). The effect on filler and fiber flocs size was studied in a pilot flow loop using focal beam reflectance measurement (FBRM) and image analysis. Flocs obtained with cationic polyacrylamide (CPAM) and bentonite were shown to have similar shear resistance with both strategies, whereas cationic starch (CS) was clearly more advantageous when coflocculation strategy was used. The effect of flocculation strategy on drainage rate, STFI formation, ash retention, and standard strength properties was measured. Coflocculation of filler with CPAM plus bentonite or CS showed promising results and produced sheets with high strength but had a negative impact on wire dewatering, opening a door for further optimization.

Desorption of Cationic Polyacrylamide from Bleached Kraft Pulp Fibers

1987 ◽  
Vol 19 (5-6) ◽  
pp. 939-951 ◽  
Author(s):  
Clifton F. Warren ◽  
R. Gehr
Keyword(s):  
Adsorption Isotherm ◽  
Total Nitrogen ◽  
Kraft Pulp ◽  
Detection System ◽  
Cationic Polyelectrolyte ◽  
Chemiluminescence Detection ◽  
Pulp Fibers ◽  
Paper Manufacturing ◽  
Bleached Kraft Pulp ◽  
Receiving Water

The adsorption and desorption behaviour of a cationic polyelectrolyte contacted with wood pulp fibers was determined by total nitrogen analysis using a pyrolysis/chemiluminescence detection system. Dialysed polymer generated an adsorption isotherm of higher affinity than did non-dialysed polymer. Capacity adsorption was maximized at pH 7, but decreased in the presence of alum depending on the dosage. Desorption of non-dialysed polymer was caused by changes in pH above or below 7.0 as well as by addition of alum. However for the alum doses typically encountered in paper manufacturing, significant desorption is unlikely. Nevertheless, the contaminants in non-dialysed polymers do hinder adsorption, and effluents from those processes using both alum and polymer may contain quantities of unadsorbed or desorbed polyelectrolytes which could be damaging to receiving water bodies.

Characterization of odorous compounds from bleached kraft pulp mill effluent

1995 ◽  
Vol 31 (11) ◽  
pp. 35-40 ◽  
Author(s):  
B. G. Brownlee ◽  
S. L. Kenefick ◽  
G. A. MacInnis ◽  
S. E. Hrudey
Keyword(s):  
Gas Chromatography ◽  
Kraft Pulp ◽  
Pulp Mill ◽  
Dimethyl Disulfide ◽  
Gas Chromatography Mass Spectrometry ◽  
Pulp Mill Effluent ◽  
Kraft Pulp Mill ◽  
Bleached Kraft Pulp ◽  
Methyl Phenyl Sulfide ◽  
Library Spectrum

Odour compounds in extracts of bleached kraft pulp mill effluent (BKME) have been characterized by olfactory gas chromatography (OGC) and gas chromatography-mass spectrometry. A variety of sulfury odours was detected by OGC in addition to woody and pulp mill-like odours. Three sulfur compounds were identified by comparison of retention times and partial mass spectra with authentic standards: dimethyl disulfide, 3-methylthiophene and thioanisole (methyl phenyl sulfide). Typical concentrations in BKME were 1, 0.05, and 0.5 μg/l, respectively. Their odour intensity is relatively low and they were not detected by OGC. Dimethyl trisulfide was tentatively identified by comparison of its partial mass spectrum with a literature (library) spectrum. Its concentration in BKME was estimated at 0.5-2 μg/l. It corresponded to a skunky odour in the OGC profiles. Efforts to identify another odour peak, eluting just after 3-methylthiophene, with a pronounced alkyl sulfide odour were unsuccessful.

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