In the early 1990’s, a lot of work was focused on extending the kraft cook to a low lignin content (low kappa number). The driving force was the need to further reduce the environmental impact of the bleaching, as less delignification work would be needed there. However, the delignification during the residual phase of a kraft cook is very slow and, due to its poor selectivity, it is a limiting factor for the lignin removal. If the amount of lignin reacting according to the residual phase could be reduced, it would be possible to improve the selectivity of the kraft cook. In the work described in this thesis, special attention has been given to the activation energy of the slowly reacting residual phase of a kraft cook on softwood raw material and to the influence of different cooking parameters on the amount of the residual phase lignin. The activation energy of the residual phase delignification of the kraft cook was shown to be higher than that of the bulk phase delignification. In order to decrease the amount of residual phase lignin, it was essential to have a high concentration of hydrogen sulphide ions when cooking with a low hydroxide concentration. It was also important to avoid a high sodium ion concentration when cooking with low hydroxide and low hydrogen sulphide ion concentrations. Furthermore, it was demonstrated that dissolved wood components had a positive effect on the delignification rate in the bulk phase of a kraft cook. The influence of different cooking parameters in the extended softwood kraft process on the bleachability (i.e. the ease with which the pulps can be bleached to a target brightness) of the manufactured pulp was also investigated. If variations in bleachability were seen, an attempt would also be made to find chemical reasons to explain the differences. It was difficult to establish clear relationships between the chemical structures of the residual lignin and the bleachability of the pulp. However, it was seen that the higher the content of β-aryl ether structures in the residual lignin after cooking, the better was the QPQP*-bleachability. In the middle/end of the 1990’s, the focus moved from extended cooking to efficient utilisation of the wood raw material, e.g. by interrupting the kraft cook at higher kappa number levels and choosing appropriate cooking conditions to maximise the cooking yield. A high cooking yield often leads to a somewhat higher hexenuronic acid (HexA) content of the pulp at a given kappa number. Therefore additional attention was devoted to how the HexA content and carbohydrate composition were affected, e.g. by a set of cooking parameters. Performing these studies it was also important to investigate the effects of a low HexA (after cooking) strategy on such vital factors as the cooking yield, the bleachability and the yellowing characteristics of the pulp obtained. It proved to be difficult to significantly reduce the HexA content in a kraft pulp by altering the cooking conditions for both softwood and the hardwood Eucalyptus Globulus. A reduction in HexA content can be achieved by extending the cook to lower kappa numbers, or by using a high hydroxide concentration, a low hydrogen sulphide concentration or a high sodium ion concentration. However, neither of these strategies is attractive for industrial implementation since they would result in an extensive loss of yield, viscosity and strength. / <p>QC 20100825</p>

<p>Detta examensarbete genomfördes från begäran av två företag, Pöyry Sweden AB, Karlstad och Kiram AB. Arbetet var uppdelat i två delar, en litteraturstudie samt en experimentell del. I litteraturstudien kartlades olika processer för framställning av dissolvingmassa och olika processer för beredning av viskosfiber. Utöver det sammanställdes även några av de ledande aktörerna av joniska vätskor samt applikationer för cellulosabaserade produkter. Fokus genom hela arbetet har legat på svavelfria processer som t.ex. användandet av joniska vätskor för upplösning av cellulosa. I den experimentella delen undersöktes det om man via en förhydrolys följt av ett soda-AQ kok, en svavelfri process, kunde producera dissolvingmassa. Utöver produktion av dissolvingmassa undersöktes också filtratet som drogs av efter förhydrolysen.</p><p>Under den experimentella delen varierades olika parametrar för att se hur det påverkade kvaliteten av massan. De parametrar som varierades vid förhydrolysförsöken var tid och antrakinon (AQ), för soda-AQ koket varierades tid, AQ och effektiv alkali (EA) halt. För ett förhydrolysförsök varierades även vätske/vedförhållandet. Vilka betingelser som skulle användas samt de mål som skulle uppnås fick man fram under litteraturstudien.</p><p>För att nå målet med ett utbyte på ca 85 % efter förhydrolysen krävdes en temperatur på 160°C och tid på 1 timme för en förhydrolys med enbart vatten. Hypotesen om att en AQ tillsats redan vid förhydrolysen skulle sänka utbytet visades inte stämma, man fick då istället ett ökat utbyte. Målet för massorna efter soda-AQ koket var ett utbyte på ca 40 %, ett kappatal runt 30 och en viskositet > 1000 ml/g. Utförde man en förhydrolys som beskrivits ovan följt av ett soda-AQ kok med dessa betingelser: temperatur 160°C, tid ≥ 2 h, EA sats > 21 % och en AQ halt ≥ 1 kg/ton, fick man en dissolvingmassa som uppfyllde kraven.</p><p>Kolhydratanalysen på filtratet visade att mestadels glukomannan brutits ner och lösts ut under förhydrolysen. Däremot skedde det ingen nedbrytning av cellulosa. Utförde man förhydrolysen på ett sådant sätt som beskrivits ovan bröt man ner en hemicellulosa mängd på ca 72 kg/ton flis. Det får ses som en ganska rejäl mängd eftersom man enbart använder vatten under förhydrolysen.</p> / <p>This project was carried out on a request from two companies, Pöyry Sweden AB, Karlstad and Kiram AB. The work was divided in two parts, one literature study and one experimental part. In the literature study different processes for production of dissolving pulp and different processes for viscose preparation were identified. Besides that, some of the lending companies of ionic liquids and some applications of cellulose based products were compiled. The main focus throughout this work has been on processes without sulfur, for an example the use of ionic liquids for dissolving cellulose. In the experimental part, dissolving pulp production by a prehydrolysis followed by a soda-AQ cooking was investigated. The filtrate gained from the prehydrolysis was also examined.</p><p>In the dissolving pulp production different parameters for the prehydrolysis and cooking stage were alternated. For the prehydrolysis the following parameters were varied: time and concentration of anthraquinone and for the cooking stage the parameters time, EA and concentration of anthraquinone. In one experiment the liquid to wood ratio was varied. The conditions that would be used and the target of the experimental work were received from the literature study.</p><p>To reach the target yield of approximately 85 % after an prehydrolysis, with water, the following conditions were required, a temperature of 160°C and a time of 1 hour. The hypothesis that an AQ additive, already in the prehydrolysis, should lowered the yield proved to be wrong. The target for the dissolving pulps after a soda-AQ cooking were a yield of ~ 40 %, a kappa number around 30 and finally a viscosity > 1000 ml/g. A soda-AQ cooking with these conditions: temperature 160°C, time ≥ 2 h, EA > 21 % and an AQ conc. ≥ 1 kg/ton, after a prehydrolysis, mentioned above, resulted in a pulp which achieved the targets.</p><p>The carbohydrate analysis on the filtrate showed that mostly glucomannan was settled out during the prehydrolysis. It also showed that no cellulose was settled out. A result after a prehydrolysis like the one mentioned above was that the amount of hemicellulose was reduced with ~ 72 kg/ton wood.</p>

This thesis is focused on the novel wood chip refining process called AdvancedThermomechanical Pulp (ATMP) refining. ATMP consists of mechanical pretreatmentof chips in Impressafiner and Fiberizer prior to first stage refining atincreased intensity. Process chemicals (this study was concentrated on hydrogenperoxide and magnesium hydroxide) are introduced into the first stage refiner.It is known that the use of chemicals in TMP process and first stage refining atelevated intensity can reduce the energy demands of refining. The downside is thatthey also alter the character of the produced pulp. Reductions in fibre length andtear index are usually the consequences of refining at elevated intensity. Additionof chemicals usually leads to reduction of the light scattering coefficient. Usingstatistical methods it was shown that it is possible to maintain the TMP character ofthe pulp using the ATMP process. This is explained by a separation of thedefibration and the fibre development phases in refining. This separation allowsdefibration of chips to fibres and fibre bundles without addition of chemicals orincrease in refining intensity. Chemicals are applied in the fibre developmentphase only (first stage refiner). The energy demand in refining to reach tensileindex of 25 Nm/g was reduced by up to 1.1 MWh/odt (42 %) using the ATMPprocess on Loblolly pine. The energy demand in refining of White spruce, requiredto reach tensile index of 30 Nm/g, was reduced by 0.65 MWh/odt (37%).Characterizations of individual fibre properties, properties of sheets made fromlong fibre fractions and model fibre sheets with different fines fractions werecarried out. It was established that both the process equipment configuration (i.e.the mechanical pre‐treatment and the elevated refining intensity) and the additionof process chemicals in the ATMP process influence fibre properties such as external and internal fibrillation as well as the amount of split fibres. Improvementof these properties translated into improved properties of sheets, made from thelong fibre fractions of the studied pulps. The quality of the fines fraction alsoimproved. However, the mechanisms of improvement in the fines quality seem tobe different for fines, generated using improved process configuration andaddition of process chemicals. The first type of fines contributed to better bondingof model long fibre sheets through the densification of the structure. Fines whichhave been influenced by the addition of the process chemicals seemed in additionto improve bonding between long fibres by enhancing the specific bond strength.The improved fibre and fines properties also translated into better airpermeability and surface roughness of paper sheets, properties which areespecially important for supercalendered (SC) printing paper. The magnitude offibre roughening after moistening was mainly influenced by the processequipment configuration while the addition of process chemicals yielded lowestfinal surface roughness due to the lowest initial surface roughness. There was nodifference in how fines fractions from the studied processes influenced the fibreroughening. However, fines with better bonding yielded model fibre sheets withhigher PPS, probably due to their consolidation around fibre joints. Hence, thedecrease in PPS can probably be attributed to the improvements in the long fibrefraction properties while the improvement of fines quality contributed to thereduction of air permeability.The process chemicals, utilized in the ATMP process (Mg(OH)2 and H2O2) alsoproved to be an effective bleaching system. Comparable increases in brightnesscould be reached using the ATMP process and conventional tower bleaching.Maximum brightness of the pulp was reached after approximately 10 minutes ofhigh‐consistency storage after refining or 40 minutes of conventional bleaching.This study was conducted using a pilot scale refiner system operated as a batchprocess. Most of the experiments were performed using White spruce (Piceaglauca). In Paper I, Loblolly pine (Pinus taeda) was used. It is believed that theresults presented in this thesis are valid for other softwood raw materials as well,but this limitation should be considered.

A large part of the world paper manufacturing consists of production of corrugated board components, kraftliner and fluting, that are used in many different types of corrugated boxes. Because these boxes are stored and transported, they are often subjected to changes in relative humidity. These changes together with mechanical loads will increase the deformation of the boxes compared to the case where the same loads are applied in a static environment. This enlarged creep due to the changes in relative humidity is called mechano-sorptive or accelerated creep. Mechano-sorptive creep forces producers to use high safety factors when designing boxes, and therefore, this is one of the key properties of kraftliner boards.   Different strategies to decrease mechano-sorptive creep, and to simultaneously gain more knowledge about the causes for this phenomenon in paper, are the aim of this work. Derivatised and underivatised black liquor lignins, a by-product produced in pulp mills in large quantities, have been used together with biomimetic methods, to modify the properties of kraftliner pulp. Furthermore, the properties of kraftliner pulp have been compared to other pulps in order to evaluate the influence of fibre morphological factors, such as fibre width and shape factor, on the mechano-sorptive creep. In addition the influence of the chemical composition of the kraftliner pulp has been evaluated both by means of treating a kraftliner pulp with chlorite and xylanase and by producing pulps with different chemical composition.   By using lignin and biomimetic methods, to create radical coupling reactions, it has been shown that it is possible to increase the wet strength of kraftliner pulp sheets. This method of treating the pulp showed, however, no significant effects on the mechano-sorptive creep. The addition of an apolar suberin-like lignin derivative, which has been shown to be possible to produce from natural resources, did show a positive effect on mechano-sorptive creep properties, but at the expense of stiffness properties in constant climate. Different pulps were compared with a kraftliner pulp and it was observed that the ratio between tensile stiffness and hygroexpansion can be used to estimate the mechano-sorptive creep properties. The hardwood kraft pulps investigated had lower hygroexpansion, probably due to more slender and straighter fibres, and higher tensile stiffness, probably due to lower lignin content. As the lignin content was varied by different methods in kraft pulps, it was observed that increased lignin content gives an increased hygroexpansion and decreased tensile stiffness as well as an increased mechano-sorptive creep. There were also indications of increased mechano-sorptive creep due to higher xylan content. / En stor del av världens papperstillverkning utgörs av produktion av wellpappkomponenter, kraftliner och fluting, som används i en uppsjö av olika wellpapplådor. När dessa lådor lagras och transporteras utsätts de ofta för förändringar i relativa luftfuktigheten. Dessa förändringar tillsammans med mekanisk belastning ökar lådornas deformation jämfört med om samma belastning skulle ha applicerats vid ett statiskt klimat. Denna förhöjda krypning på grund av förändringarna i relativ luftfuktighet kallas mekanosorptiv- eller accelererad krypning. Mekanosorptiv krypning tvingar producenterna att ha höga säkerhetsmarginaler vid dimensioneringar av lådor och är därför en av nyckelegenskaperna för kraftliner.   Olika strategier för att minska denna effekt, och på samma gång erövra mer kunskap om orsakerna till detta fenomen, har varit syftet med arbetet. Derivatiserade och oderivatiserade svartlutslignin, en biprodukt möjlig att få ut i stora kvantiteter från massabruk, har används tillsammans med biomimetriska metoder, för att modifiera kraftlinermassas egenskaper. Dessutom har kraftlinermassans egenskaper jämförts med andra massors egenskaper för att utvärdera inverkan av fibermorfologiska faktorer, såsom fiberbredd och fibreform på det mekanosorptiva krypet. Också inverkan av den kemiska sammansättningen av kraftliner massan har undersökts både genom behandling med klorit och xylanas och genom att producera massor med olika kemiska sammansättningar.   Genom att använda lignin och biomimetriska metoder för att skapa radikal-kopplingsreaktioner har det visats på möjligheten att öka våtstyrkan i massa-ark. Det här sättet att behandla massa visade dessvärre inga signifikanta effekter på det mekanosorptiva krypet. Tillsatts av ett apolärt suberin-liknande ligninderivat, som visats möjligt att producera ur naturliga råmaterial, visade en positiv effekt på det mekanosorptiva krypegenskaperna även om det var på bekostnad av styvheten vid konstant klimat. Olika massor jämfördes med en kraftlinermassa och det observerades att relationen mellan dragstyvhet och hygroexpansion kan användas för att uppskatta de mekanosorptiva krypegenskaperna. Lövvedssulfatmassorna som undersöktes hade lägre hygroexpansion, antagligen beroende på smalare och rakare fibrer, och högre dragstyvhet, troligen beroende på en lägre ligninhalt. När ligninhalten varierades i sulfatmassor med olika metoder observerades att ökad ligninhalt ger en ökad hygroexpansion och minskad dragstyvhet liksom en ökad mekanosorptiv krypning. Dessutom fanns indikationer på en ökad mekanosorptiv krypning till följd av högre xylaninnehåll. / QC 20100629

The surface charges of cellulosic fibers contribute to several papermaking operations that influence the manufacture and final properties of paper. This thesis investigates the effect of the surface charges on wet-end chemistry, e.g. through the interaction of cationic polyelectrolytes with the fiber surface charges, and on the network strength of pulp suspensions. The polyelectrolyte titration method was used to investigate the interaction of the fiber charges with cationic polyelectrolytes. Techniques were developed to fluorescent label the adsorbing cationic polyelectrolyte in order to visualize the adsorption behavior. Fluorescent confocal laser scanning microscopy (CLSM) was used to determine the extent to which the cationic polyelectrolyte adsorbs into the porous fiber wall. It was shown that the polyelectrolyte charge density limits the adsorption to the surface under electrolyte-free conditions. Adsorption into the fiber wall only occurs for two conditions: 1) if the molecular mass is sufficiently low or 2) the electrolyte concentration is high enough to screen the charges along the polyelectrolyte backbone but not the interactions between the polyelectrolyte and the fiber charges. Aside from the polyelectrolyte properties, the fiber charge density contributes to the adsorption behavior of cationic polyelectrolytes. The fiber charge profile was altered by bulk and surface carboxymethylation. The electrolyte concentration at which a deviation from 1:1 stoichiometry occurs was shown to be dependent on the amount of surface charges, such that the deviation in stoichiometry occurs at a higher electrolyte concentration for pulps having a higher surface charge. A hypothesis was developed to test the conditions at which the deviation in adsorption stoichiometry occurs, which was defined as the critical electrolyte concentration (CEC). It was found that the CEC corresponded to the electrolyte concentration at which the distance between the fiber charges was on the order of the Debye length. Electron spectroscopy for chemical analysis (ESCA) was used as an independent calibration procedure to validate for which a 1:1 stoichiometry occurs. The analysis with ESCA agreed well with the polyelectrolyte titration method for measurement of fiber surface charges. When measured under appropriate conditions, i.e. electrolyte concentration and molecular properties, the fiber surface charge can accurately be measured by the polyelectrolyte titration method. The charge profiles of various pulp types and treatments were also examined. Having been established as a valid technique, the polyelectrolyte titration method was again used to measure the surface charge while conductometric titration was used to measure the total charge content. The amount of bulk and surface charges vary depending on the pulping method and type of wood, although the ratio between the bulk and surface charge (i.e. the charge ratio) is similar for chemical pulps. The mechanical pulp has a higher charge ratio because it contains more fines material than chemical pulp. Bleaching of the chemical pulp decreases the amount of bulk and surface charges, although the charge ratio remains essentially constant. However, methods such as beating or carboxymethyl cellulose (CMC) grafting are available to increase the charge ratio. The effect of the charge profile on fiber-fiber interactions was studied on both a microscopic and macroscopic level. Colloidal probe microscopy (CPM) was used to investigate the microscopic interactions between two cellulose surfaces. Cellulose surfaces, prepared by spin-coating a dissolving pulp onto silica, were used to model the fiber surface, which is too rough for surface force measurements. The charge density of the model surface was increased by CMC grafting. Results showed that increasing the surface charge density created large electrosteric repulsions, due to CMC the chains protruding out from the surface. These interactions on the microscopic scale affect the fiber network strength, which was measured with a parallel plate rheometer. When the repulsion is increased between the fibers, caused by the increase in the surface charge, fiber flocs break apart more easily due to a reduced friction between the fiber surfaces. The forces acting on the fiber network can also be mechanical in origin. The fiber length and flexibility were altered in order to study the influence of mechanical surface linking and elastic fiber bending on the fiber network strength. Using the storage modulus (G’0) as a measure of fiber network strength, longer fibers were found to create a stronger network due to an increased amount of fiber contacts. Flexible fibers have a lower network strength than stiff fibers because the fibers come to rest in a less strained position such that the the influence of elastic fiber bending on the fiber network strength is predominant. / QC 20100831

After cooking, kraft pulps always contain not only residual lignin but also significant amounts of hexenuronic acid and other non-lignin structures oxidizable by permanganate under the standard kappa number determination conditions. These here referred to as false lignin. Like ordinary lignin, the false lignin also consumes bleaching chemicals, thus increasing both the production costs and the environmental impact of bleach plant effluents. The false lignin also has an effect on pulp properties such as brightness stability. This necessitates the development of efficient experimental routines for the determination of false lignin in different types of unbleached and bleached kraft pulps, together with studies of its formation, chemical behaviour, and ultimate fate. The main aim of this work has been to establish a method for the quantification of various types of oxidizable structures in bleached kraft pulps and to study their impact on pulp quality, particularly, on the brightness stability of pulps bleached in elemental-chlorine-free (ECF) and a totally-chlorine-free (TCF) processes. Part of this research deals with the relationship between the kappa number and the lignin content in the case of partly oxidized lignins. Spruce and birch kraft pulps processed according to the ODEQP and OQ(OP)Q(PO) bleaching sequences, respectively, have been analyzed. It has been found that the oxidation equivalent of the residual lignin decreases with increasing degree of oxidation along each bleaching sequence. This finding has been further supported by experiments with a number of model compounds. The Ox-Dem kappa number method has been shown to be an accurate means of determining the residual lignin content and of monitoring the efficiency of lignin removal along different bleaching sequences. It has been demonstrated that the kappa number can always be fractioned into partial contributions, the first of which comes from the residual lignin and is measured by the Ox-Dem kappa number, and the second from the false lignin and is given by the difference between the standard kappa number and the Ox-Dem kappa number. The effect of false lignin on the pulp kappa number is most pronounced in unbleached and oxygen-delignified kraft pulps. The extractability of residual and false lignin in different solvents has been investigated. The changes that occurred in the kappa number following different extraction steps have been compared with corresponding changes in the chemical composition and the conclusion has been drawn that the hemicellulose component of a kraft pulp is a major sourse of non-lignin structures contributing to the kappa number. The influence on the brightness stability of various oxidizable structures, viz.: residual lignin, hexenuronic acid and other non-lignin structures, in spruce, birch and eucalyptus kraft pulps bleached in ECF and TCF type processes was studied. It was demonstrated that the selective removal of all false lignin structures significantly improves the brightness stability. The degree of yellowing was found to be proportional to the content of HexA groups in pulps. It has been shown that 2-furancarboxylic acid, 5-formyl-2furancarboxylic acid and reductic acid are formed during the course of thermal yellowing. The influence of two bleaching sequences, D0(EP)D1 (ECF-type) and Q1(OP)Q2(PO) (TCF)-type, on the content of different oxidizable structures in eucalyptus kraft pulp was studied in relation to the brightness stability of the pulp. It was shown by kappa number fractionation that pulp bleached to full brightness with ECF- and TCF-type sequences contains different amounts of HexA. The most significant discoloration was observed in the case of TCF-bleached pulp having an especially high content of HexA. The mechanism of the moist (8 % moisture) thermal yellowing of fully bleached kraft pulps was further studied using dissolving pulp impregnated with a set of model compounds representing the most likely HexA degradation products, viz. as 2-furancarboxylic acid (FA), 5-formyl-2-furancarboxylic acid (FFA) and reductic acid (RA), either alone or in combination with Fe(II) or Fe(III) ions. It was found that the latter two acids take part in reactions leading to colour formation whereas 2-furancarboxylic acid does not. The effect of iron ions on the colour formation appears to vary with their oxidation state. The brightness loss caused by either FFA or RA, present in an amounts similar to the content of HexA in industrial pulps, was of the same order of magnitude as that observed in industrial pulps aged under the same conditions. Based on these findings, it is suggested that the overall mechanism of moist thermal yellowing involves several stages, including the degradation of hexenuronic acid and the formation of reactive precursors, such as 5-formyl-2-furancarboxylic acid and reductic acid. The presence of ferrous ions further enhances the discoloration. / QC 20101005

Variable data will play a decisive role in the future of packaging and product promotion. Variable data printing (VDP) is a technique whereby certain information can be altered in an otherwise static layout with the help of a digital printing system, and in the packaging industry a wide range of applications is possible. Inkjet printing, due to its non-impact printing (NIP) principle, is the most suitable technology to use when applying variable data on packaging and to offer customized and even personalized prints for the industry and the end-consumer (van Daele, 2005). The aim of the work described in this thesis was to evaluate the practicability of attaining high quality variable data print (VDP) at high speed. The thesis is divided into three major parts. Part one focussed on the surface topography of corrugated board and applicable analytical methods to describe the printability of the substrate. In the second part the performance of inkjet on corrugated board liners printed at high speed was investigated and how to achieve maximum printing resolution. The final part of the thesis is devoted to a market survey of variable data printing on the North American and European markets. Part 1 concentrated on corrugated board as substrate and its pre-conditions regarding surface topography before the printing operation. Most critical for the quality are print defects such as mottling, gloss and stripiness, all of which occur in the printing of corrugated board. Stripiness is especially critical because it is one of the most disturbing print defects on corrugated board since it is periodical and more easily perceived than random print defects (Netz, 1996). Part 1 revealed that there is a difference in surface micro-roughness between the regions on the peak line of the fluting and the regions in the valley between two peaks of the corrugation which leads to glossy lines on the peak areas. The aim of the second part was to assess the practicability of attaining high quality VDP at high speed on a variety of liners for corrugated board production. The trial was conducted on a Kodak Versamark DP5240 press in Örnsköldsvik, Sweden, in cooperation with the Mid-Sweden University - Digital Printing Centre (DPC). Nine different substrates were printed at speeds between 0.5 and 5 m/s. The results revealed that the paper type rather than the printing speed has the greatest influence on the print quality. Speed, however, is the most important technical factor for inline implementation of inkjet. To obtain a picture of the industries’ view of variable data print on fibre-based packaging, a market survey was initiated and was addressed to people in the development, marketing and decision-making sectors of the packaging and printing industry, including manufacturers of machinery, producers of packaging and prints, and print buyers. The goal was to draw an overview map covering the people’s view of their market, trends in their fields and how they envision the future of VDP on fibre-based packaging. The conclusion was that inkjet technology has to prove itself first and to increase its technical capability, and the printing industry will then start investing more in this technology and in applications such as VDP. / QC 20101206

Detta examensarbete genomfördes från begäran av två företag, Pöyry Sweden AB, Karlstad och Kiram AB. Arbetet var uppdelat i två delar, en litteraturstudie samt en experimentell del. I litteraturstudien kartlades olika processer för framställning av dissolvingmassa och olika processer för beredning av viskosfiber. Utöver det sammanställdes även några av de ledande aktörerna av joniska vätskor samt applikationer för cellulosabaserade produkter. Fokus genom hela arbetet har legat på svavelfria processer som t.ex. användandet av joniska vätskor för upplösning av cellulosa. I den experimentella delen undersöktes det om man via en förhydrolys följt av ett soda-AQ kok, en svavelfri process, kunde producera dissolvingmassa. Utöver produktion av dissolvingmassa undersöktes också filtratet som drogs av efter förhydrolysen. Under den experimentella delen varierades olika parametrar för att se hur det påverkade kvaliteten av massan. De parametrar som varierades vid förhydrolysförsöken var tid och antrakinon (AQ), för soda-AQ koket varierades tid, AQ och effektiv alkali (EA) halt. För ett förhydrolysförsök varierades även vätske/vedförhållandet. Vilka betingelser som skulle användas samt de mål som skulle uppnås fick man fram under litteraturstudien. För att nå målet med ett utbyte på ca 85 % efter förhydrolysen krävdes en temperatur på 160°C och tid på 1 timme för en förhydrolys med enbart vatten. Hypotesen om att en AQ tillsats redan vid förhydrolysen skulle sänka utbytet visades inte stämma, man fick då istället ett ökat utbyte. Målet för massorna efter soda-AQ koket var ett utbyte på ca 40 %, ett kappatal runt 30 och en viskositet &gt; 1000 ml/g. Utförde man en förhydrolys som beskrivits ovan följt av ett soda-AQ kok med dessa betingelser: temperatur 160°C, tid ≥ 2 h, EA sats &gt; 21 % och en AQ halt ≥ 1 kg/ton, fick man en dissolvingmassa som uppfyllde kraven. Kolhydratanalysen på filtratet visade att mestadels glukomannan brutits ner och lösts ut under förhydrolysen. Däremot skedde det ingen nedbrytning av cellulosa. Utförde man förhydrolysen på ett sådant sätt som beskrivits ovan bröt man ner en hemicellulosa mängd på ca 72 kg/ton flis. Det får ses som en ganska rejäl mängd eftersom man enbart använder vatten under förhydrolysen. / This project was carried out on a request from two companies, Pöyry Sweden AB, Karlstad and Kiram AB. The work was divided in two parts, one literature study and one experimental part. In the literature study different processes for production of dissolving pulp and different processes for viscose preparation were identified. Besides that, some of the lending companies of ionic liquids and some applications of cellulose based products were compiled. The main focus throughout this work has been on processes without sulfur, for an example the use of ionic liquids for dissolving cellulose. In the experimental part, dissolving pulp production by a prehydrolysis followed by a soda-AQ cooking was investigated. The filtrate gained from the prehydrolysis was also examined. In the dissolving pulp production different parameters for the prehydrolysis and cooking stage were alternated. For the prehydrolysis the following parameters were varied: time and concentration of anthraquinone and for the cooking stage the parameters time, EA and concentration of anthraquinone. In one experiment the liquid to wood ratio was varied. The conditions that would be used and the target of the experimental work were received from the literature study. To reach the target yield of approximately 85 % after an prehydrolysis, with water, the following conditions were required, a temperature of 160°C and a time of 1 hour. The hypothesis that an AQ additive, already in the prehydrolysis, should lowered the yield proved to be wrong. The target for the dissolving pulps after a soda-AQ cooking were a yield of ~ 40 %, a kappa number around 30 and finally a viscosity &gt; 1000 ml/g. A soda-AQ cooking with these conditions: temperature 160°C, time ≥ 2 h, EA &gt; 21 % and an AQ conc. ≥ 1 kg/ton, after a prehydrolysis, mentioned above, resulted in a pulp which achieved the targets. The carbohydrate analysis on the filtrate showed that mostly glucomannan was settled out during the prehydrolysis. It also showed that no cellulose was settled out. A result after a prehydrolysis like the one mentioned above was that the amount of hemicellulose was reduced with ~ 72 kg/ton wood.

Wood consists not only of cellulose, lignin and hemicellulose but also of so called extractives which includes fats and acids and these components are separated in the mill from the black liquor. These extractives are in the mill denoted as tall oil soap. Tall oil has a large field of applications like chemicals and fuel and as it is produced to the atmosphere if it can replace oil and thus reduce the oil consumption. Tall oil soap is separated from the black liquor in a skimmer and the focus of this thesis was to examine the effect of air injection and the soap layer thickness on the soap separation efficiency in a skimmer. The work was focused on in analyzing the soap content of the inlet and outlet black liquor flow of the skimmer and to detect if an enhancement has been achieved with the two mentioned methods. The reason for the pulp mill to improve the soap separation efficiency was to decrease the risk of foaming and fouling in the evaporator but also to be able to increase the production of tall oil. The air injection gave a 41% improvement of the soap separation efficiency and further improvements are probably possible to achieve. The air injection flow was about 7 l air /m3 liquor in the black liquor feed. The airflow lowers the density of soap, creating a greater difference in density between soap and black liquor and this improves the separation efficiency. A thicker soap layer could increase the likelihood for soap drops to raise and reach the soap-liquor interface, because the soap drops have the tendency to bind with each other and will be separated from the liquor instead of following with the skimmed liquor outlet (fig. i.2). However, this study shows no indication of improvement with thicknesses that exceeds 0,75- 3,5 m which also endanger the skimmer due to overflow from the skimmer or create a short circuit between the in- and the outlet black liquor flow.

Nordic Paper Åmotfors tillverkar elektrotekniskt papper som används till att isolera lindningarna i transformatorer. Det är viktigt att bibehålla papprets egenskaper under en mycket lång tid då en transformators livlängd är lång. Syftet med detta examensarbete var att undersöka huruvida tillsats av en kemikalie bestående av dicyandiamid kan fördröja åldrandet av de papper som Nordic Paper tillverkar. Förhoppningen var att deras papper därefter skulle klara de krav-parametrar som finns för papper som åldrats i olja. Kemikalien som användes var Cartafix® WE liquid. Försök utfördes där olika kemikaliedoseringar tillsattes i mälden. Pappersark tillverkades och kvävehalten mättes därefter för att verifiera att kemikalien fastnat i de färdiga papprena. Pappers-arken åldrades sedan endera i olja eller i luft, och den kvarvarande polymerisationsgraden (DP) mättes. Sprängstyrke- och konduktivitetstester utfördes också. Papper som Nordic Paper tillverkat beströks med olika kemikaliedoseringar och samma tester utfördes även på dessa. Resultaten visade att retentionen av kemikalien var låg. Kvävehalten blev inte högre än 1 % och detta skedde vid 10-20 % kemikalietillsats. Efter åldring i olja minskade DP relativt mycket, vilket medförde att papprena inte uppnådde de uppsatta kraven (maximalt 50 % minskning). Tillsats av kemikalien förbättrade dock papprets åldringsegenskaper med nästan 45 % om icke-modifierat papper jämförs med det modifierade pappret som hade högst DP (10 % kemikalietillsats, vilket motsvarade 1 % kvävehalt). Papper som modifierats med kemikalietillsats i mälden gav lägre DP då åldringen skett i luft jämfört med icke-modifierat papper. DP minskade avsevärt efter åldring för papper som bestrukits med kemikalien. Kemikalietillsats försämrade både sprängstyrkan och konduktivteten. / Nordic Paper Åmotfors manufactures electro technical paper that is used to isolate the windings in transformers. It is important to maintain the properties of the paper during a long period of time because the life of a transformer is extensive. The purpose of this thesis was to investigate whether or not addition by a chemical consisting of dicyandiamide could delay the ageing of the papers that Nordic Paper manufactures. The aspiration was that their paper would then fulfil the requirements that are applicable to papers that have been aged in oil. The chemical that was utilised is called Cartafix® WE liquid. Experiments were conducted where different dosages of the chemical were added to the stock. Sheets of paper were manufactured and the nitrogen level was then measured in order to verify that the chemical had been fused in the finished paper. The paper sheets were then aged in either oil or air and the remaining degree of polymerisation was measured. Bursting strength and conductivity were also evaluated. Papers that Nordic Paper had manufactured were coated with different dosages of the chemical and then investigated in the same manner. The results showed that the retention of the chemical was relatively low. The nitrogen level did not exceed 1 %, which occurred at 10-20 % addition of the chemical. After ageing in oil, the degree of polymerisation was significantly reduced, which meant that the papers did not fulfil the requirement of a maximum of 50 % reduction. The addition of the chemical did however improve the ageing resistance with nearly 45 % if the unmodified paper is compared to the modified paper with the highest degree of polymerisation (10 % addition, equivalent to 1 % nitrogen). Papers that had been modified by addition of chemicals in the stock and had been aged in air exhibited lower degree of polymerisation than unmodified paper. The degree of polymerisation was significantly reduced for papers that had been coated and aged in air. Addition of chemicals resulted in both lower bursting strength and lower conductivity.