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Defect spots degrade paper quality and often cause sheet breaks and other problems in the subsequent coating process. We encountered sporadic surges of defect spots on paper from a paper machine producing printing and writing grades of paper. We found that white or light-colored filler spots and waxy, translucent, elliptical spots accounted for 27.3 and 34.4% of these defects, respectively, and that both types of defect contained unhydrolyzed AKD as a major component. Paper machine’s wet-end deposits, however, did not contain unhydrolyzed AKD as a deposit component. We hypothesized that the colloidal stability of AKD was the main factor causing the increase in spot defects, and we verified this by deposit testing experiments. Among the papermaking additives tested, bentonite caused the most significant increase in AKD deposition during testing, which was attributed to its causing the electrostatic coagulation of cationically charged AKD emulsion particles. In contrast, anionically charged AKD emulsions showed improved stability and less deposit formation in the presence of bentonite.

Mottling within print-through and show-through is caused by the variability of the local optical properties of the sheet. This mottling is visually disturbing and a mark of poor paper quality. The ability to predict print-through mottle of printed paper by measuring show-through mottle on the unprinted sheet would be a valuable asset for paper machine control. We examined the relationship between print-through mottle and show-through mottle. We worked with nine samples of 60 lb. uncoated fine paper (90 g/m2), from various North American paper companies, that were printed on an offset press, 400K (400% Black), on both sides. A show-through mottle instrumental determination technique was developed using an existing Fast Fourier Transform-based algorithm. The nine samples examined were ranked similarly by the visual evaluation of print-through mottle and by the instrumental determination of show-through mottle. We thus established that show-through on the unprinted sheet can be used as a reliable predictor of print-through, therefore saving time and money for papermakers. We also found a significant two-sidedness in show-through for some of the samples.

This article focuses on the properties of paper samples made using foam-laid technology. The effects of three surfactants, namely sodium dodecyl sulphate (SDS), sodium alkyl ether sulphate (SAES), and linear chain alkyl polyglucoside (C8/C10-Gluc), on properties of foam formed paper samples were studied, using chemithermo-mechanical (CTMP) spruce pulp and bleached kraft pulp. The results show that the type of surfactant used in foam forming has significant effects on the mechanical properties and quality of paper. In the presence of ionic polymers, the charge of surfactant has a significant effect on the formation of the paper sample. It was also shown that at AKD dosages ≥ 3 kg/t, the water absorbency of water formed paper samples was greater than that of foam-formed samples made using C8/C10-Gluc. Foam-forming also produced greater dryness after forming and wet-pressing than the water forming method. The type and dosage of surfactant had a significant impact on dewatering. Filler retention of foam-formed samples was significantly higher when using a non-ionic surfactant instead of an anionic surfactant. The effect of the strength additive (cationic starch) in increasing the strength of foam-formed samples was less in the presence of anionic surfactants than with non-ionic surfactants.

In this work the strength enhancing capabilities of microfibrillated cellulose (MFC) in highly filled papers was studied. Both the MFC production and the paper making were done in pilot scale under ...

Effects of artificial thermal aging on color variations of various commercial papers (fine paper, coated paper, newsprint and filter paper) were investigated. With thermal aging at 105 o C, most of papers showed a special trend in a * -b * plane: the a * (red-green) values of the samples were initially reduced (heading to a * side) and after a turning point they increased to +a * side while the b * (blue-yellow) values were kept increased to +b * side (yellowing of paper). Different papers had different turning points for a * value. The filter paper consisted of a pure chemical pulp and the copy paper with OBA (optical brightening agent) showed the latest turing points. In addition, the papers without OBA showed less reduction in brightness compared with that with OBA, suggesting that OBA could adversely influence the brightness stability during thermal aging. Keywords: Thermal aging, brightness, optical brightening agent, color differences, CIE L * a * b * 1. 서 론 종이가 제조된 후, 시간의 흐름에 따라 종이의 노화가 발생한다. 종이가 노화됨에 따라 종이의 물리적, 화학적 성질이 어떻게 변화하는지는, 종이의 보존 측면에서 또는 종이를 재생하는 측면에서 여러 연구자들에 의해서 연구되어져 왔다.

In order to explore new applications of recovered waste paper, we prepared electrically conductive fibers by plating waste newspaper pulp (WNP) fibers. Further, we mixed them with unplated WNP fibers and filtered the mixture to obtain a conductive pulp fiber sheet, which was to be used for electromagnetic compatibility (EMC) purposes. For the plating of WNP fibers, we used an electroless nickel plating method. We also plated pulp fibers recovered from fine paper, pulp fibers recovered from milk carton, and bleached softwood kraft pulp fibers, which were used for comparison with the plated WNP fibers. All of the four types of plated, recovered waste paper pulp fibers had high conductivity, i.e., an electrical conductivity of 0.1 S/m or more and a conductance of 0.02 S or more. The conductive pulp fiber sheet made of WNP fibers had an electric field shielding effect of 30 dB or more at 10–1000 MHz, provided that the ratio of the plated WNP fibers in the sheet was 40 % or more. Therefore, our conductive WNP fiber sheet is effective in EMC.

The aim of the study was to explain the transportation of liquid (fountain solution) during transfer to coated paper in the heatset offset printing process, together with the subsequent drying of the printed paper, by using statistical and experimental methods.A coating dispersion, applied as a single coating onto a fine paper substrate, was formulated using a narrow fine particle size distribution natural ground calcium carbonate pigment and a styrene acrylic binder. The moisture variation in the paper during printing was monitored by using online multipoint sensors based on near-infrared diffuse reflectance spectroscopy. Based on the results, a simulation model was created to determine the transfer of liquid thin films in the printing units, the evaporation in the printing units, followed by liquid absorption and evaporation in the heatset offset drying process. An accurate simulation depends on precise determination of the different process parameters that influence these factors.The absolute liquid/moisture amount transferred to the paper showed an increased trend as the paper passed through the application nips, though the proportion varied due to limited capillary absorption capacity properties of the paper. The background evaporation in the printing nips was evaluated with the simulation model as well as the drying stages in the dryer including surface and bulk condensation followed by rapid evaporation and cooling.

Silica is commonly used as an ingredient in the coatings of inkjet papers because of its capability to provide a coating layer structure combining a high pore volume, into which all the applied inkjet ink can transfer, and a suitable pore size distribution for very quick ink absorption. Nowadays, the production of silica pigment is quite expensive, and therefore, it would be advantageous to find a cheaper raw material source. In this study, the raw material was Greek olivine from magnesite mine sidestreams. The silica pigment was produced at laboratory scale by using nitric acid as a solvent. The target of this work was to clarify how this produced silica pigment is suited for inkjet coating pigments. The coating colors were applied by a laboratory rod coater on fine base paper and white-top kraftliner, and the coated surfaces were printed with a home and office area inkjet printer. The results showed that the produced olivine-based silica pigment has a potential in matt inkjet coatings. The coating of the produced silica pigment increased the print density, decreased the print-through, and diminished the bleeding of fine paper and white-top kraftliner board. However, further development work is needed to improve the pigment brightness to a more acceptable level, and to control the particle size at the nitric acid dissolution.

The efficiency of optical brightening agents (OBAs), also known as fluorescent whitening agents (FWAs), has long been of interest in the production of uncoated fine paper, particularly in uncoated fine paper grades containing high-yield pulp (HYP). The increasing levels of whiteness and also the increasing HYP substitution in fine papers has made OBA efficiency an important issue. This paper summarizes recent research findings in understanding and enhancing OBA efficiency in fine papers containing HYP, with focus on the main factors affecting OBA efficiency in both wet end and size press application. These factors include the base sheet brightness and whiteness of the pulp, UV competitors, OBA retention, quenching effects, and OBA migration at the size press. Some new technologies to improve OBA efficiency are discussed.

In recent years there has been an increasing interest in using high-yield pulp (HYP) as a partial replacement for hardwood bleached kraft pulp (HWBKP) in the production of high-quality fine papers as a cost-effective way of improving the product performance. This study investigated the substitution of HYP for HWBKP and its effect on the Alkenyl Succinic Anhydride (ASA) sizing performance. The results showed that the substitution of an aspen HYP for HWBKP can increase the ASA sizing performance at a HYP substitution as high as 15 to 20%. The ASA addition sequence has an influence on the ASA sizing performance and first adding ASA to the HYP followed by mixing with kraft pulps was the preferred method. Using precipitated calcium carbonate (PCC) as a paper filler at a dosage of less than 20% can increase the ASA sizing performance due to the contribution of the calcium soap of the hydrolysed ASA. A PCC dosage greater than 20% resulted in a negative impact on the sizing performance. It was also found that different PCC loading sequences can also affect the ASA sizing performance.

Increase of filler content in paper improves quality of the final product and reduces raw material costs. However, this is often accompanied by deterioration of paper machine runnability. In this paper the effects of stratifying PCC (precipitated calcium carbonate) and TMP on fine paper quality and the mechanical properties of dry and wet paper were studied. In addition, a new method was introduced for evaluating the layer purity of pulp and filler stratifying by measuring the fibre length distribution in the thickness direction of the paper. The filler addition reduced the mechanical properties of paper more with chemical than mechanical pulps, with similar dry tensile indices. Stratifying filler onto paper surfaces gave higher dry tensile strength properties than samples with mixed structures, whereas only a small positive effect was detected for wet tensile and relaxation properties as a result of stratifying. Stratifying fillers only had a small negative effect on the internal bond strength. Stratifying or mixing TMP with a chemical pulp blend was shown to enable an increase in the filler content of 10% without significant changes in the residual tension (tension after 0.475 s of relaxation) or tensile index of wet samples. Based on layer purity analysis, stratifying TMP and filler was found to be successful in these trials.

Eco-friendly high-yield pulps (HYP) are becoming increasingly used to product high value-added fine paper that is traditionally produced exclusively with chemical pulps. However, due to the presence of a large quantity of photosensitive lignin in the HYP pulp to more effectively utilize woods resources, there is a concern on the long term brightness stability of HYP containing paper. In this research, various TiO2was added to coating colors to improve the light fastness properties of HYP containing coated paper. The effect on the stability of optical properties of coated paper including brightness, opacity, color difference and the degree of brightness reversion before and after accelerated aging were studied. It was shown that the brightness stability of the HYP containing coated paper increased with increased addition of TiO2. Rutile TiO2was especially more effective than other types of TiO2on yellowing inhibition of coated paper. At a dosage of 3 parts of rutile TiO2, the brightness stability of coated paper containing 20% of HYP was found to be even better than paper made of 100% chemical pulp coated with conventional coating color.

Liquid transfer in a heatset printing process to coated papers has been evaluated online. The porous coatings, applied in various combinations of single coating onto a fine paper substrate, together with selective particle size distributions containing calcium carbonate pigments were calendered under different conditions to establish a range of porosities and pore structures while keeping the formulation and hence the surface chemistry constant. The transfer of fountain solution to the papers was analyzed from unprinted areas (nonimage) at six different positions along the printing line, namely, between each printing unit and after the dryer section, using near-infrared absorption reflectometry. In this way, real-time analysis of the amount of fountain solution (defined as water content) transferred to the paper per printing unit as a function of physical paper surface characteristics has been achieved. The role of printing speed and fountain solution dosage level on water uptake by the various coated paper substrates has been investigated. It was concluded that the higher the speed, firstly, there is less compression of the surface roughness and, secondly, less time for the liquid to respond with respect to capillary forces, resulting in less liquid transfer.

High water consumption is a major environmental problem that the pulp and paper industry is facing. Ultrafiltration (UF) can be used to remove the dissolved and colloidal substances (DCS) concentrated during the recycling of white water (the process water) to facilitate the reuse of white water and reduce fresh water consumption. However, membrane fouling limits the application of UF in this industry. In this study, super-clear filtrate obtained from a fine paper mill was purified with a polyethersulfone (PES) ultrafiltration membrane to evaluate the reuse performance of the ultrafiltrate. The membrane foulants were characterized by scanning electron microscopy, energy-dispersive spectrophotometry, attenuated total reflection-fourier transform infrared spectroscopy, and gas chromatography-mass spectrometry. The results indicate that the retention rate of stock and the strength properties of paper increased when the ultrafiltrate was reused in the papermaking process compared to when super-clear filtrate was used. The reversible membrane foulants during ultrafiltration accounted for 85.52% of the total foulants and primarily originated from retention aids, drainage aids, and wet strength resins, while the irreversible adsorptive foulants accounted for 14.48% and mostly came from sizing agents, coating chemicals, and others. Moreover, the presence of dissolved multivalent metal ions, especially Ca2+, accelerated membrane fouling.

Compozil system is a multifunctional wet-end chemical system developed by Eka Chemicals AB in Sweden, and this system has been well accepted worldwide.Previously we referred this system as “microparticle system” because of the colloidal spherical silica particles in Compozil system, however, in reality they are much smaller “nanoparticles”. Because of this we now refer this system as “nanoparticle system”. The Compozil system has been improved to meet the latest market requirements such as the increase of recycled fiber, higher filler level, and higher machine speed.Compozil Select System is the latest novel retention/dewatering system composed of the new type of colloidal silica, cationic polymer, and anionic trash catcher. This system can be used not only for acid and alkaline fine paper but also for the liner and board, and wood containing and recycled fiber.

Increasing bulk is the first step toward resource-lean papermaking. Increasing the bulk tends to reduce strength and increase porosity and roughness; however, loss in strength could be compensated for via an increase in the specific strength of bonds. The increase in total surface area can have a positive influence on the porosity and smoothness of the paper. Results suggest that the bulk of fine paper can be increased by 20% and the critical paper properties maintained through selection of the kraft fibre type, control of the degree of hornification, addition of xyloglucan, and use of fines-rich mechanical pulp. In general, the results reported on here suggest that increasing bulk or reducing grammage is a challenging task but can be accomplished through simultaneous application of several unconventional measures.

Cationized birch xylan was prepared and its use as a papermaking chemical was evaluated. The focus was on studying the effects of cationized birch xylan on the wet and dry strength of fine paper. The results of the laboratory experiments show that the addition of 3 percent of cationized birch xylan to birch kraft pulp improved the initial wet strength of the web by 30 percent compared to base stock at a solids content of 55%. Furthermore, the tensile stiffness of the wet web increased by approximately a third and the dry tensile strength improved by 26%, while the dry elastic modulus was not changed. The improvements in the strength properties were clear when compared to the base stock, but not as high as achieved with conventionally used cationized starch. The difference between the xylan and starch is most likely due to the shorter polymer chain length of the cationized xylan.

In this work the application of polyelectrolyte complexes (PEC) to different pulps, to improve the strength of papers produced from them, is compared with conventional pulp beating. The pulps chosen for the investigation were a fully bleached chemical hardwood pulp (HBK), a fully bleached chemical softwood pulp (SBK), and a peroxide-bleached chemi-thermomechanical pulp (BCTMP). The polyelectrolytes used were a polyamideamine epichlorohydrine condensate (PAE), traditionally used as a wet-strength additive, and carboxymethylcellulose. Since the complexes prepared from these chemicals bear an anionic charge, they can only be used after fibre pre-treatment with the cationic PAE. Results indicate that the addition of 2% PAE and 2% PEC can improve all the measured tensile strength properties of the sheets as much as is commonly achieved by mechanically beating the pulps. In fact, for the chemical pulps, PEC addition at the chosen level produced better results than did traditional beating, since the improved tensile index and tensile energy absorption could be achieved without any significant deterioration in the light scattering coefficient of the papers produced. However, with the BCTMP a significant decrease in light scattering could be detected, especially following the addition of PEC. Adding the chemicals (especially the PEC) increased the sheet density, so chemical treatment left the bending stiffness of the sheets unaffected. However, based on the results, it was suggested that a combination of unbeaten HBK and BCTMP treated with PAE and PEC should be used as the fibre components of a typical fine paper furnish.

The z-directional penetration of starch was determined through an image analysis on 16 iodine stained cross-sectional images. The numerical penetration information was processed to represent a starch distribution (Simulated Starch Content distribution, SSC) and a dimensionless starch penetration number Q.

Sample sheets of five kinds of papers (fine paper, newspaper paper, copy paper, semi-fine paper, and straw paper in 'hanshi' size) were each fixed on copper plates with acrylic resin paste or placed on copper plates or silicone rubber. In the case of both the fixed papers and the papers placed on silicone rubber under application of a certain load onto the sensor, the quartz-crystal tuning-fork impedance change decreased in the order listed above when the sensor's base was brought into contact with the papers. These results have been found to correspond with the ratio of pulp to recycled paper ingredient. This sensor functions as a paper-quality sensor capable of sensing the mixing ratio of pulp to recycled paper ingredient.

A new harvesting system and the fibre properties of reed canary grass (Phalaris arundinacea L.) makes this grass an interesting new raw material source for the pulp and paper industry in the Nordic countries. Pilot scale tests in Finland shows that high quality fine paper can successfully be produced from delayed harvested reed canary grass. Birch pulp can be replaced with reed canary grass pulp in fine paper furnish without any significant differences in the functional properties of paper. To achieve good pulp and paper properties the raw material has to be pre-treated (removal of leaves and sheaths by fractionation) before pulping. Fractionating produces a “chip” fraction of mainly internodes for pulp production and a meal fraction of leaves and sheaths that can be used as biofuel. Fractionation improves the homogeneity of the raw material and the pulp properties. Silica and other minerals, which are considered as a problem in alkaline pulping processes, are concentrated in the meal fraction. Fine material that causes poor drainage of the pulp is also removed in the fractionation process. In this work, different degrees of fractionation have been studied. Pulping conditions and fibre properties for totally unfractionated raw material up to best available raw material (manually fractionated) are compared.

As the meaning of dictionary terminology, scum refers to a layer of impurities that accumulates at the surface of a liquid. In papermaking process, scum indicates the floated solid waste generated by a flotation process during the primary wastewater treatment. In this study, different kinds of stocks and scums collected from newspaper, liner, tissue and fine paper were analysed in details. The purpose of this study was firstly to demonstrate the composition characteristics of different sources of scum, secondly the analysis of environmental hazardous materials, and thirdly the evaluation of reutilization ability of fibrous materials from collected scum. As mentioned the meaning of solid waste, scum was actually differ from the waste sludge in sources, compositions and recycling abilities. In the same manner of waste paper, the sludge which is generated within onsite of papermaking processes would be reused as a raw material. The general compositions of scum from waste water were mainly inorganic ash materials, fine fibre fractions, recycled fibre debries, and ink particles. If the scum is able to reuse as fibrous additives in papermaking process, it could contribute to the savings of running costs in both the subsidiaries of fibrous material and the solid waste treatment with even small quantity.

The paper introduces a new continuous retention monitoritoring system capable to measure the first-pass retention of fibers or total solids and filler separately. The system consists of optical sensors installed in the headbox and white water lines and a central unit where the calculations are carried out. Both filler and total consistencies in each line as well as the corresponding first-pass retention values are available for further processing.

Using the simplified version of the computer model in Part I of the series, the heat and mass transfer, and resulting web drying in a dryer section are simulated quantitatively with several actual mill operating conditions. Then, assuming some parameters several hypothetical values, their influences are further estimated in quantity.1. The drying seems to proceed in three phases, rapid heating up in the first several cylinders, followed by nearly constant water removal per cylinder almost throughout a dryer section and a sudden decrease in drying rate at the last few cylinders.2. Taking closer looks at the constant drying rate cylinders, followings are summarized. When some cylinder has a higher surface temperature, the heat transfered to a web increases sensitively, which results in the almost proportional increase of a water removal at that cylinder. In a cylinder pocket, which shows a lower absolute humidity, the evaporation at a free run is inversely larger.3. Focusing more on web drying at a cylinder as a basic unit, two typical patterns are classified depending on an absolute humidity of a cylinder pocket.By reducing a humidity there, i.e. from 0.3 g/g dry air to 0.2 g/g dry air, the evaporation at a free run increases dramatically, some of which is compensated by the decrease of the evaporation to a hood, and the overall water removal at the cylinder increases about ten percent.4. The higher absolute humidity in a hood retards overall drying rate.The effect is simulated in the case of a fine paper machine. It is equivalent to one extra cylinder unit.5. The heat transfer coefficient between a cylinder surface and a web varies to a large extent, depending on the grades of products. The higher value is expected with a fine paper machine than with a magazine printing machine.6. Regarding the heat balance of a whole dryer section, about eighty five percent of the heat conveyed to cylinder shells is used for the water evaporation.

(Research Institute of Oji Paper Co., Ltd., Tokyo) New pulping methods of hard wood have been studied eagerly in Japan, because soft wood has become scarce by overfelling.Characteristics of hard wood pulp depend on the properties of the fiber, that is, short and slender shape and rich content of pentosan.Blending the hard wood pulp in various papers, the printability of the papers are improved and such properties as formation, smoothness, opacities rise.(1) Bleached kraft pulp of hard wood are used in fine paper, and owing to blending, the printability of the paper is improved considerably. But viscous printing ink sometimes takes away the vessels from paper surface during offset printing.(2) Semichemical pulp and chemi-ground pulp are used in news print and photogravure paper.Properties of chemi-ground pulp are similar to ground wood of soft wood, but lower opacity.(3) Ground wood of hard wood has high opacity, and is used in news print.

Multiple studies have considered the nanosilica-cationic starch system to be a retention/drainage aid; however its potential to improve strength has previously been neglected. This research focused on the effect of both nanosilica and cationic starch on certain crucial physical and mechanical properties of fine paper compared with a paper sheet containing no additives to evaluate how this system can compensate for using more filler in fine paper. In previous studies, it was suggested that the cationic starch-nanosilica system induces much tinier flocs and thus possibly results in better strength properties. In this respect, results revealed that cationic starch did, however, improve tensile index; this effect weakened at higher filler levels. Cationic starch and nanoparticles both improved internal bonding, while cationic starches’ effect was more prominent. With more filler, tear index suffered. Although addition of cationic starch partly compensated this negative effect with filled papers, nanoparticles did not seem to have an obvious effect. Therefore, cationic starch provided the limited potential of using more filler and nanoparticles may do it indirectly.