Our knowledge about the mechanisms by which retention aids function in wet-end papermaking has been increasing rapidly. Although originally many retention aids were introduced without little understanding of how they act, nowadays a clear scientific understanding is emerging. We can say that the use of retention aids has passed from an art which depended much on experience and intuition, to a science, which involves the principles of colloid and polymer science. Various examples of our increased understanding of PEO-based retention aids, cationic polyelectrolytes and microparticulate retention aid systems are being discussed.

Recycling systems are usually designed with pulp quality targets based on cleanliness, or similar property. Achieving other specific fibre properties is rarely a goal of a recycling system, but fibre properties can be modified to suit specific end uses. Recycling line equipment choices impact n fibre properties, but these effects choices impact on fibre properties, but these effects tend to be less well documented than the effects on cleanliness or brightness.

Investigations were carried out recently in three Canadian newsprint mills where a cationic dual polymer retention chemistry was in use for years. Several enhancer/PEO combinations were evaluated on bench scale to determine any possibility for replacing the exiting retention system for reduced chemical cost and improved machine operating efficiency. The PEO with 10 million molecular weight. New enhancers produced from bisphenol-S, especially Pulfix BL, were much superior to the traditional phenol-formaldehyde resin in promoting PEO retention performance. The effect of stock aging on retention appeared to be stock dependent. The floc induced by the new enhancer/PEO system was somewhat more susceptible to redispersion through hydraulic shear than that from cationic coagulant/cationic polyacrylamide(PAA) flocculant systems but this should be considered to be beneficial to sheet formation. The non-ionic retention chemistry improved stock drainage more than BASF's Polymin SK/cationic emulsified PAA even at much lower dosage levels, as determined with a Vertical Sludge Press. The new enhancer/PEO combination was proved once again to be excellent for pitch removal and was considerably better than that of two cationic dual polymer systems studied.

The present investigation has focused up on the study of the adsorption of three different molecular mass fractions of a polyDiMethylDiAllylAmmoniumChloride (DMDAAC) (8750(LM\ulcorner), 48000(MM\ulcorner) and 1200000(HM\ulcorner)) on bleached chemical fibres. Both kinetics of adsorption and equilibrium adsorption measurements have been conducted and each adsorption has been measured by polyelectrolyte titration. The results show that the LM\ulcorner polymer can reach all of the charges in the fibre wall whereas the MM\ulcorner and HM\ulcorner can only reach the external surfaces of the fibres. It is also shown that the kinetics of adsorption of the LMw polymer is not at all affected by the presence of a saturated layer of HMw polymer on the surface of the fibres. Finally, the results from the investigation show that it is possible to have full coverage of the external surface of the fibres by a high molecular mass polymer and a full coverage of the internal surface of the fibres with a low molecular mass polymer. This is true if the high molecular masspolymer is added first followed by addition of the low molecular masspolymer.

Effectiveness of the microparticle retention systems in improving dramage, retention, formation has been recognized for many years (1, 2, 3, 4, 5). In this study the effectiveness of crosslinked cationic corn starches and silica-based microgels as components of Compozil system has been evaluated. It was shown that improvements in retention and strength could be achieved by employing crosslinked cationic corn starches especially at high conductivity. Silica-based microgels with better performance in retention and dramage than a commercial colloidal silica sol have been made through a reaction of sulfuric acid and sodium silicate solutions.

Sizing development of AKD-sized paper by beta-ketoester formation has been debated until recent years because of absence of its obvious and direct spectroscopic evidence. In this study, reaction between AKD and cellulose was investigated to disclose the possibility of beta-ketoester formation between two components under no catalyzed neutral condition. In absence of water, AKD reacted with cellulose to form beta-ketoester linkage under no catalyzed neutral condition, while, in presence of water, most of AKD was hydrolyzed to a dialkyl ketone or beta-ketoacid. Therefore, the main mechanism of AKD sizing would not be the formation of beta-ketoester between AKD and cellulose in the papermaking process. It could be suggested that the sizing development of AKD-sized paper is obtained by next two mechanisms: 1) formation of a thin-layer of AKD on the fiber surface through melting and spreading of AKD emulsion particles by heat, and 2) the formation of ketone by the hydrolysis of AKD during drying and storage of AKD-sized papers.

In this paper, a series of amphoteric polyacrylamide(PAM) with different molecular weight and charge were synthesized and used as retention and dewatering aids. Better products had been selected and tested under varied conditions. Effects of molecular weight, cationic charge density, degree of hydrolysis and other factors of PAM on retention and dewatering of papermaking were also considered. Finally, synthesized quaternary and tertiary ammonium amphoteric polyacrylamide were practised in paper mill trial.

Contaminants such as fatty acids, triglycerides, resin acids and foam collected from a high yield sulfite weak liquor storage tank lowered the water surface tension and reduced inter-fibre bonding but also tended to benefit sheet opacity. Some common wet end additives such as defoamers and dispersants gave similar results. Lignosulfonate and naphthalene sulfonate showed little if any negative effect on both surface tension and sheet strength properties. Among the natural wood extractives. fatty acids were identified to be most detrimental followed by triglycerides and then resin acids. In order to alleviate the detrimental impact of these contaminants, membrane separation, air floatation and ozone treatment were carried out on paper machine white water samples. The effect of these treatments on removal of fatty and resin acids was quantified by a GC-Mass analysis. Reverse osmosis with a 1000 molecular weight cut off membrane failed to totally reject fatty and resin acids, but markedly reduced losses of sheet properties due to contaminants. Ozone treatment resulted in a significant increase of the surface tension and air floatation was considered to be a practical and useful method for removing fatty and resin acids from the machine white water.

Cationic polymers, such as partly aminated poly (N-vinylformamide). copolymer of trimethylaminoethyl acrylate with acrylamide, polyethyleneimine, polyallylamine, and poly(diallyldimethylammonium chloride) were investigated to elucidate their contributions to neutral-alkaline paper sizing with acid rosin sizes. The sizing results indicated that both amounts of aluminium and rosin size retained in paper were increased by the suitable polymer addition, and that the polymers with amide group in part and with lower charge density were more efficient to the sizing of rosin emulsion size whereas the polymers with higher charge density were effective for rosin soap size. Based on the results of paper sizing with rosin-alum and various polymers, the particle size distribution, and the polyelectrolyte titration of aluminium sulfate-polymer mixture, it was proposed that suitable cationic polymers could form stable complex with rosin size particles through hydrogen bonds or ionic bonds and with aluminium by coordination bonds to prevent from the destructive action of hydroxyl ion so that the good sizing of rosin size-alum can be achieved under neutral-alkaline conditions.

A cationic demand(CD) is a very useful indication for determining the optimum dosage rate of retention aids to the papermaking stock at the wet end. Polyelectrolyte titration has been most often used to determine a CD. Highly accurate results can be obtained by this method when the ionic strength of sample is low. But this is accompanied by the serious errors when the ionic strength is higher than that corresponding to 20 milli molar(mM) monovalent, 2 mM divalent or 0.2 mM trivalent ions because of no occurrence of the end point of titration. Therefore, it is very difficult or almost impossible for the conventional method to be applied to the industrial suspensions such as papermaking stock and industrial waste water. Then a novel method using chromophoric labeled cationic polymer which can be applicable to the sample with high ionic strength has been developed.

Treatment with the enzyme pectinase has been reported to lower the cationic demand of thermomechanical pulp(TMP) bleached with alkaline peroxide in the laboratory. We have extended this discovery to bleached TMP produced industrially, and shown that commercial enzyme preparations can treat pulp within 15 minutes at the at the temperature and pH values prevalent in paper mills. About half of the cationic demand in the bleached pulp can be destroyed by pectinase. Dynamic drainage jar experiments show that the enzyme treatment improves the effectiveness of several cationic polymers to increase retention in the absence of retention aids or with non-ionic polymers, and does not damage the strength properties of the pulp. Pectinase could be easily incorporated into paper machine stock preparation systems to lower the charges of cationic retention aids needed in furnishes containing peroxide-bleached mechanical pulp.

Adsorption behavior of aluminum compounds on pulp fibers at the wet-end was studied in terms of structures of aluminum components using some analytical techniques. Fibrous cellulose powder (CF) and fibrous carboxymethylcellulose powder(FCMC) were used as models of pulp fibers. When de-ionized water was used, alumiunm components originating from alum added to cellulose suspensions were adsorbed on FCMC, probably forming carboxyl group aluminum salts. On the other hand, no interactions occurred between hydroxyl groups of cellulose and aluminum components in the suspensions. Analysis of adsorption behavior of cationic aluminum species on cellulosic fibers using solution-state \ulcornerAl-NMR showed that any cationic aluminum species such as Al\ulcorner, Al\ulcorner and aluminum polymers were adsorbed on FCMC. Again no interactions were recognized between such cationic aluminum species and hydroxyl groups of cellulose in the \ulcornerAl-NMR study. Thus, adsorption and retention behavior of aluminum compounds in paper is greatly influenced by carboxyl contents of pulp fibers used. Mapping analyses revealed that aluminum components were distributed almost homogeneously in the cross sections of each pulp fiber for the handshects prepared with 2% aluminum sulfate or 2% polyhydroxyaluminum chloride(PHAC). Thus, water-soluble aluminum species such as Al\ulcorner ions, Al\ulcorner and aluminum polymers can penetrate into the inside pulp fibers during the handsheet-making process.

Sizing behavior of handsheets, which were prepared from thermomechanical pulp (TMP) with alkylketene dimer (AKD), was studied in terms of conditions of the handsheet-making. AKD content in the TMP handsheets increased with increasing the AKD addition level, and the addition of a polyamideaminecpichlorohydrin resin(PAE) clearly enhanced AKD retention as well as the resultant sizing performance. Although drying of the wet TMP webs at 20$^{\circ}C$ led to no or quite low sizing level, the AKD-sized TMP handsheets had higher sizing degrees with increasing the temperature of heat treatment. Scanning electron microscopic observations of the AKD-sized TMP handsheets showed that AKD emulsion particles were present on pulp fiber surfaces independently without coagulation in the TMP handsheets dried at 20$^{\circ}C$. Heat treatment of the AKD-sized handsheets resulted in disappearance of the AKD emulsion particles by their melting and spreading. The addition of calcium carbonate filler to the TMP suspensions did not influence on AKD content in the TMP handsheets. Nevertheless, their sizing degrees clearly increased by the addition of CaCO$_3$filler. Probably, AKD molecules adsorbed on the CaCO$_3$filler particles contribute to the enhancement of sizing performance. Thus, AKD can give sizing features effectively to the TMP handsheets, when they are made under suitable conditions.

Mechanisms of paper sizing by reactive sizes such as alkylketenc dimers(AKD), alkenylsuccinic anhydrides(ASA) and fatty acid anhydrides(FAA) are revicwed on the basis of the results obtained in our laboratory. Solid-state \ulcornerC-NMR analysis of cellulase-treated residues of handsheets prepared with \ulcornerC-labeled sizes showed that the size componcnts are present primarily as hydrolyzed products, without forming covalent bonds with hydroxyl groups of cellulose in the handsheets. Furthermore, most size components in hansheets were removed by stirring the defibrated handsheets in water with Tween 80 at 70$^{\circ}C$ for 4h. Thus, the hydrolyzed products of size molecules consequently contribute to sizing performance for the reactive size-treated papers. Scanning electron microscopic observations revealed that the chemical structures of reactive sizes are necessary for efficient paper sizing to achieve homogenous distribution of hydrophobic size components on hydrophilic pulp fiber surfaces in the papermaking process, where water is always present. Size reversion is presumably explained in terms of partial introduction of hydrophilic groups into the size molecules by auto-oxidation. Therefore, mechanisms of paper sizing by reactive sizes can be rationalized, without introducing the covalent bond formations, by changes in chemical structures of the size molecules from hydrophilic to hydrophobic by hydrolysis in papermaking process. Model experiments using a cellulose-AKD ester sample also supported these mechanisms.

The deposition kinetics of fines on fibres was studied to elucidate the flocculation mechanism of a PAM/bentonite retention aid. It is shown that polymer-induced co-flocculation is not permanent. This phenomenon is attributed to a stabilising effect of polymer transfer between surfaces. The resulting polymer layers have a reduced bridging ability with naked surfaces. The addition of bentonite increases the bond strength between fibres and fines, and links non-briding layers. These results explain the positive influence of bentonite on fines retention.

During mechanical pulp production and blcaching wood components, such as extractives, carbohydrates and lignin are dissolved and dispersed into the process waters. These components are called dissolved and colloidal substances(DCS). DCS can accumulate during water circulation and can in turn affect paper machine runnability and also the strength and optical properties of the paper. In this work DCS fraction origination from TMP process were treated with enzymes acting on triglycerides. glucomannans, and lignin and the effect of enzymatic treatments on the water composition as well as sheet properies were evaluated. Lipases were found to modify the chemical structure of the extractives resulting in more hydrophilic fibre surface and subsequent improvement in the sheet strength properties. Mannanase treatment, on the other hand, destabilized pitch. As a result, aggregation of pitch to the fibres was observed which in turn resulted in impaired strength properties. Laccase could effectively polymerize lignans and the reaction products seemed to be sorbed onto the fibres.

Dissolved and colloidal substances released from pulps into process waters can accumulate and give detrimental effects on papermaking, especially in paper machine systems with a high degree of water system closure. It has been reported in the literature that beating of chemical pulps in the stock preparation can result in considerable dissolution and dispersion of fibre substances. Three ECF-and four TCF-bleached pulps delivered in dry form to the Sappi Austria AG fine paper mill in Gratkorn, including both softwood and hardwood pulps, were beaten in a Valley laboratory beater. Refiner beating in the mill was investigated by analysis of samples taken before and after the refiners. The dissolved and colloidal substances in the waters were separated from the fibres by centrifugation and were analysed by standard determinations and by GC analysis of carbohydrates and lipophilic extractives(resin). Considerable amounts of organic material was dissolved and dispersed already during slushing of the pulps. During beating in the Valley beater the concentrations increased further by 6-32%. Beating in the paper mill released little organic material from the pulps. The released dissolved and colloidal substances were mainly composed of hemicelluloses, with xylans as the dominant group, both for hardwood and softwood pulps. More lipophilic extractives were released from birch pulps than from eucalypt and softwood pulps. In mill samples, starch was the dominating dissolved material. Starch is used in the mill both in the wet end and as a coating color component. It was concluded that the amounts of dissolved and colloidal substances coming in with chemical pulps to the wet end of papermaking are dependent mainly on the efficiency of pulp washing in the pulp mill. Only some additional fibre material is dissolved or dispersed during beating.

This paper dealt with effect of dual component and micropartical retention system on papermaking. First-pass retention under dynamic drainage condition was studied in neutral and alkaline papermaking system. Cationic starches, amphoteric starches and amphoteric polyacrylamide were added prior to high shear force, then anionic. The system is found to be very useful to inprove filler retention. For mitigating unfavorable effect of interfering sub-stances, anionic trash catcher(ATC) such as p-DADMAC was tested in this study.

In order to manage the wet end chemistry on paper machines, our goal is to control sub-processes through which we can influence the entire wet end operations with maximum effect. The most important sub-processes are: consistency, ash, and chemistry. The management of these three main groups is based on on-line maesurements and automatic control. This paper presents a new wet end management platform, a new analyzer. This new analyzer utilizes a modular structure and modem software. It is part of a new paper machine concept. The controls of this concept are feedback and feedforward solutions that control retention, consistencies, ash, and charge, resulting in a more stable wet end (30...80%), more uniform paper, and better rnnability.

Amphoteric latex has been applied to solve binder migration and ununiform binder distribution of coating layer which are major parameters of surface strength problem and print mottle of coated paper in printing recently. Amphoteric latex copolymerized both anionic functional group and cationic functional group. It gave better rheological movement to coating color above alkaline region of pH and stronger interaction of coating components under acidic region of pH than anionic latex that has only anionic functional group. Coated paper which was prepared with amphoteric latex exhibited better results of coated papers such as paper gloss, surface roughness, and printability than anionic latex.

A new process for deinking of colored offset newsprint, i.e. enzyme treatment in cooperation with ultrasonic wave was developed in the present study. The physical characteristics such as fiber length, coarseness, crystallinity index of the deinked pulps were investigated and the sugar residues released from the treatment were analyzed. It was found that colored offset newsprint could be deinked effectively by cellulase treatment when ultrasonic wave was applied. The brightness increased by 5% ISO over that of control experiment and the pigment content was reduced markedly. Though the ultrasonic wave had little effect on the strength and crystallinity of the pulp, the treatment of enzyme combined with ultrasonic wave reduced the coarseness and fiber length to some extent. It was also found that ultrasonic wave could accelerate the hydrolysis of cellulose and hemicellulose during the cellulase treatment.

Effluent resulting from the de-inking process is difficult to treat because it has a high pH value and contains many anionic constituents such as ink particles, fine suspended solids and surfactants used in the de-inking process. However, as much water is used in this process, it is becoming increasingly more important to recover the effluent and reuse it from viewpoints of both water conservation and quality improvement of de-inked pulp. This article describes the coagulation method, using a polycation instead of alum as a new recovering technology with waste water, can get rid of fine particles and suspended solids which cannot be removed by flotation methods, giving clear recycling water. As a result it has such advantages as high brightness, good strength, and so on.

Model experiments were conducted to investigate the effect of different fillers on the removal of toner ink. Combinations of different papers (commercial photocopy paper and filler-free paper), fillers (calcium carbonate, kaolin clay, and talc), and chemicals(1-octadecanol, stearic acid, oleic acid, and TOFA) and stearic acid were found to be effective in detachment and agglomeration of toner ink. Furthermore, pH had little effect on toner detachment and agglomeration, indicating both protonated fatty acids and their anions are equally effective. In the presence of either kaolin clay or talc, all these agglomerating agents are equally effective, although a slightly higher dosage(1% for clay and 2% for talc as compared with control) is required, presumably due to the adsorption of chemical by the filler. Calcium carbonate filler, on the other hand, has a significant and adverse effect on the fatty acids used but has little effect on 1-octadecanol with the exception of possible adsorption. While stearic acid is not effective, a much higher level of oleic acid or TOFA is needed when calcium carbonate fillers are present as compared to the filler-free case. Fatty acids react with calcium carbonate to form calcium salts. The availability of fatty acid anion for toner detachment and agglomeration is determined by the solubility of calcium salt of a given fatty acid. Calcium oleate is 10 times more soluble in water than calcium stearate.

A new technique for recycling process water was developed in order to reduce the calcium hardness of the closed OCC recycling system. Calcium ions present in the white water were precipitated as calcium carbonate by a reaction with sodium carbonate and the CaCO$_3$precipitates were easily removed from the system by a dissolved air flotation(DAF) method. After the DAF stage, CO$_2$-gas was purged into the water because the pH of Na$_2$CO$_3$-treated white water was reduced to neutral by CO$_2$gas. Since CaCO$_3$precipitate tends to stick onto the fine fiber surface and then is selectively removed from the water, a proper amount of suspended solid in the process water acts as an important factor in deciding the removal efficiency. By the application of Na$_2$CO$_3$addition - DAF - CO$_2$purging to the short circulated white water the calcium hardness was significantly reduced by 92% and more. The removal of calcium ions with fine fibers led to drainage improvement, reduction of fresh water consumption, and enhanced efficiency of wet-end chemicals.

Effect of fiber treatment with cellulase (Liftase A40), and with two refining methods (Valley beating and impact refining) on wood fiber and handsheet properties were investigated at three refining levels (300, 400, and 500ml) for two furnishes (NBKP and LBKP). Part of the treated furnishes were classified by 150 mesh screen into fine-free fiber, and fines. Fiber length analysis, WRV, zero-span strength, and other handsheet mechanical properties were compared. The study showed that Liftase A40 lowered the zero-span and the folding endurance of both furnishes (NBKP much more and LBKP much less). Pretreatment with Liftase A 40 followed by refining significantly lowered the fiber length and refining energy to reach to the target freeness. Impact refining, which is done by hitting the fibers vertically with rod at 20% solid content, kept the fiber length increased WRV, and improved handsheet mechanical properties much more than valley beating. Properties of fines from different sources were compared in detail in the study.

J-intogral at the onset of stable crack growth (Jc) was examined on the double edge notched specimens of machine-glazed paper. comparing with J-integral at the onset of unstable crack growth i.e. at the maximum load point(J\ulcorner). J\ulcorner depends on the specimen width and is considerably larger than Jc. On the other hand, Jc is nearly constant independent of the width and thus is regarded as a material property for evaluating fracture toughness of paper as long as a stable crack grows before the maximum load point. The specimen geometry employed in this study fulfills the condition required for the single specimen method of J-integral determination.

Results are shown on the preparation and characterization of homopolymer of 2-methacryloyloxyethyl isocyanate(MOI) ad copolymers of MOI with styrene synthesized by radical polymerization. The significant effectiveness of the polymers as additives for paper dry and wet strength was found. Dry strength can be increased by 75% and wet strength retention of sheets can reach 30% based on the increased dry strength and about 50% based on the dry strength of untreated sheet. Based on isocyanate group consumption, copolymers containing less isocyanate can give better effect than homopolymer in sheet wet strength improvement. Furthermore, the base paper containing a small amount of polyallylamine hydrochloride was used for polymer treatment and got higher wet strength improvement.

Surface characterization of the rosin sized sheets with five typical polyamines, polyallylamine (PAAm), polyvinylamine (PVAm), polyethyleneimine (PEI), poly(diallyldimethylammonium chloride (PDADMAC), and polydimethylamino ethyl methacrylate) (PDAMAEMA) was carried out using X-ray photoelectron spectroscopy. The results show that the distribution of the binding energies of the polyamines on the outermost surfaces of the sheets was quite different. PAAm and PVAm can combine with a rosin size to form-COO-NH-structures which were related to sizing effectiveness. The polyamines distributed mainly on the surfaces of the fibers. The concentrations of PAAm and PVAm on the surfaces were much larger than those of PEI, PDEMAEM, and PDADMAC. A larger sizing degree was related to a larger C$_1$component (C-C) in the Cls XPS spectra of the sheets sized with a rosin size and the polyamines. But the carbon chains in the polyamines did not contribute to sizing effectiveness.

Versatility of a desk-top flat-bed image scanner with a transparency unit as an image input device for formation analyses was exhibited and discussed. If the scanner output under satisfied prerequisite conditions is calibrated based on a standard film or by comparison to Elrepho type reflectometer, the scanner was found to provede reasonably scaled gray levels. However, there remained some distortion in the output characteristics even after the calibration. So, unlike Elrepho type, optical density squared was almost proportional to the basis weight of paper. Formation of hansheets was quantitatively analyzed with the light transmission images obtained by the scanner. The formation index, the standard deviation of optical density squared correlated better with the subjective ranking than that of optical density or of gray level. Optical density squared divided by the basis weight showed the highest Kendall's coefficient of correlation. Anyway, the standard deviation of gray level was far from propriety as a formation index.

Friction was measured on filter paper sheets impregnated with model compounds representing wood extractives using an apparatus based on the horizontal plane principle. The best lubrication of paper surfaces was achieved when they were completely separated by a densely packed film of saturated long-chain amphophilic molecules, such as fatty acids. The fatty acids adsorbed with their polar ends on the paper surface, causing their hydrocarbon chaine to be orientated perpendicularly to the paper surface. The saturated C18-acid, stearic acid, was an efficient lubricator for paper surfaces. The introduction of a double bond in stearic acid eliminated its lubricating ability. The spatial length of the lubricating fatty acid thereby decreases from 24${\AA}$ to 11${\AA}$. However the transisomer of oleic acid, elidic acid, had the ability to lower friction due to an increased spatial length of the fatty acid. Both the spatial length of the hydrocarbon chain and the number of lubricating chains may be of importance for the paper-to-paper friction caused by wood extractives. A hydrophilic head-graup in the wood extractive and an ordered molecular layer of lubricating molecules seems also to be prerequisites for efficient lubrication. A chemical weak boundary layer between the paper sheets was suggested to cause the low friction when long chain saturated fatty acids were deposited on paper.

In the society of the 21\ulcorner century under multiphase media conditions, the rapidly glowing electronic media will replace the conventional paper media in a variety of areas. However, if human being still has an affinity for paper media and an instinct for hardcopy from electronic-based text or image, the new market will be created for the paper industry. To what extent the consumer choses paper media for output will depend upon the availability of functions of paper media appealing to human senses; i.e., "sensory functions of paper". As a whole, on-demand type personal as well as business communications will increase in the next century and this trend will lead certainly to a rapidly expanding "contents hardcopy market". The technological progress of the paper industry in the 21\ulcorner century depends upon the market needs for higher products quality and higher efficiency of manufacturing process as well as an endeavour to overcome constraints from forest resource, energy, and environmental issues. Under the conditions with above constraints, the paper media will be polarized into two categories; (1)paper for higher image reproduction capability for original image or text and (2)paper for lower reproduction but with higher appeals for human senses. To cope with these trends, psycho-physical analysis and a sensory engineering approach for developing new paper media is vitally required. Also newly emerged roles of paper physics in the multimedia age is pointed out associated with sensory functions of paper that are not well-understood so far.