• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.5
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• pp.63-69
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• 2002

A new concept of stock preparation for the increase of bending stiffness in paper and board was proposed. The "stiff" fibers, which were mechanically not treated or treated slightly to remove fiber curls, were combined with extensively refined fibers (ERF) to produce higher stiffness papers than those where the whole fibers were refined. The combination of "stiff" fibers and extensively refined fibers produced higher stiffness at the same tensile strength than the control furnish, in which all the fibers are refined together. In this concept, the fibers from recycled papers could be as much useful as the virgin fibers as long as they are stiff enough or they can produce highly bondable fiber fractions by extensive refining. Use of the concept in real paper mill needs considerations such as increase of refining energy, slower drainage, and added drying burden, but savings of wood fibers, utilization of more recycled fibers, and increase of physical properties may offset the negative concerns. The success of this concept implementation in mills, therefore, depends on the wood fiber market around the mills and the proper decision making for the papermakers about how to apply this concept. apply this concept.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.1
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• pp.48-56
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• 2000

The objective of this study was to investigate the enzymatic deinking technology. Office recycled papers such as computer printed out(CPO) and white ledger(WL) were used in the evaluation of four different deinking conditions ; alkaline deinking , neutral deinking and enzymatic deinking at alkaline and neutral pH. Filltering pads were prepared after flotation deinking to measure brighteness gain and ink removal efficiency. Three different surfactants were also used in the evaluation of deinking efficiency including surface chemical properties by measuring foam height and stability, surface tension and cloud point of views. The results indicated that the neutral deinking method with enzyme and surfactant addition showed highest deinking efficiency of office recycled papers.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06a
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• pp.99-103
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• 2006

Use of recycled fibers in papermaking has been increased for economical and environmental reasons. Recycled panels are major liber resources for brown grades and newsprints. Since the recycled fibers have disadvantageous properties as raw materials for papermaking it is of great importance to optimize the use of these recycled fibers. OCC (Old Corrugated Containers) is the major fiber source for linerboards and corrugating mediums that require diverse specification in strength properties. Many studies have been focused to overcome the problems of strength reduction of brown grades when recycled fibers are used as raw materials. The problem of strength loss for papers made from recycled fibers is closely associated with the increased amount of fines in recycled fibers and hornification of fibers. Fines contained in the recycled fiber resources cause problems not only in paper properties but also in process runnability. This shows that the optimal management and proper use of fines in recycling papermaking system are critical to get most benefits of using recycled fibers. In this study some approaches for optimal use of fiber fines in recycled paper mill have been investigated. Stock samples, prepared in the laboratory and obtained from a recycling plant were used. Fractionation of these samples was made using Sweco screen. And the effect of the addition of polyelectrolytes including cationic PAM and PEI on drainage and retention was evaluated. Different methods of polymer addition were compared to find the most effective ways of treating recycled fiber stocks with polyelectrolytes. Addition of polyelectrolytes to the short fiber fraction was most effective in retention and drainage. The influence of the charge and molecular weight of these two polymers has been examined and discussed.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.3
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• pp.70-78
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• 2012

For evaluating the printing suitability of electronic copying papers in the aspect of climate conditions, 12 samples of copying papers being generally used in Korea and worldwide were collected. The copying papers were controlled by various temperature and humidity options in conditioning equipment in order to simulate the specific circumstances of dry, temperate or tropical climate, and the pre-heating system of photocopying machines during printing. As results, some copying papers showed several physical problems, especially in recycled copying papers and a normal paper with original printing faulty. These problems of copying papers were mostly resulted in extremely high moisture circumstance, and in lower levels of tensile strength and tensile stiffness. The moisture contents of copying papers during passing through the pre-heater system of photocopying machine could be rapidly decreased because paper is exposed to high temperature around the pre-heating zone. The copying paper, for example of XR3 sample, containing low moisture contents below 2% had high exfoliating possibility of toner transfer from copying paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.3
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• pp.20-26
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• 2013

We investigated practical methods of using recycled gypsum board paper in the paper industry. Gypsum board paper is used to produce construction gypsum board, and can be recycled through the recycling process of construction wastes. The experiments were carried out in two ways: One was the substitution of recycled gypsum board papers for KOCC, and the other was the use of recycled gypsum board paper powder. Recycled gypsum board paper was not disintegrated easily, but high temperature and the use of chemicals were able to improve their disintegration. The physical properties of handsheets made of the pulp of recycled gypsum board paper exhibited the same performance level as those made from KOCC except in the parameter of compressive strength. The powder of recycled gypsum board paper was manufactured using a grinder and handsheets were made with the powder and KOCC. The bulk was increased, but the strength properties were decreased by the addition of the powder.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.31-38
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• 1999

Adsorption of polymeric flocculants and dry strength agents onto the surface of papermaking fibers is critical for their effective utilization since the polymeric substances not adsorbed on fibers or fines keep recirculating in the papermaking system to cause various operational difficulties and loss of raw materials. Problems associated with the unadsorbed polymeric substances generate great attention because unprecedent interests in utilization of recycled papers and papermaking system closure. In this study, to understand the effects of recycling on the adsorption propensity of cationic polyacryamide (PAM) dry strength resin onto hardwood bleached kraft pulp fibers and fines a systematic approach was followed. Never dried bleached hardwood kraft pulp was recycled in two different ways. In mode one recycling experiment never dried pulp was beaten then recycled three times by employing simple drying and disintegrating steps. In mode two recycling experiment beating of the recycled pulp was carried out after each recycling step. Adsorption of cationic PAM on fibers and fines was evaluated employing Kjeldahl nitrogen analysis method. The influence of recycling on water retention value, carboxyl content, sheet density and tensile strength of the pulp was examined. As the number of recycling increased, water retention value of the fiber was reduced due to hornification and this in turn caused a decrease in adsorption of cationic PAM. On the other hand, the carboxyl content of the recycled fibers increased because of the oxidation of fibers occurred during drying, and this caused an increase in adsorption of cationic PAM. Because of these two opposing factors the adsorption of the cationic PAM on the recycled fibers decreased and then increased slightly at third recycling step. Increase of PAM adsorption, however, did not provide did not provide and strength improvement for the recycled pulp fibers indicating greater influence of the honification on interfiber bonding.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.281-285
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• 1998

This experiment was carried out to evaluate the effect of recycled paper mulch on weed occurrence and the growth and yield of rice in dry-seeded paddy field. Mulch papers with basis weight of 105, 110, 115g/$m^2$ were fabricated from recycled corrugate container. It took about 80 days after mulching for the mulch papers to reach 50% decomposition, showing no significant differences among types of mulch paper. Paper mulching was very effective in controlling the paddy weeds at early stage of rice growth, but the efficacy of weeds control decreased a little at late season. However the efficacy was still higher than the plot using herbicide. The paper mulch plot showed rice yield similar to the weed control plot using herbicide. It could be concluded that paper mulch can be used as an alternative for non-herbicidal weed control and ensure as high yield as the conventional weed control method using herbicide in dry-seeded rice field.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.3
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• pp.28-36
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• 2014

The kind and the mixing ratio of recovered papers would affect the quality of final recycled paper. In this study, effects of the mixing ratio of various domestic recycled papers (old news print (ONP), old corrugated container (OCC) and coated paper (CP)) on variations in physical properties of paper and its productivity were investigated. When the mixing ratio of CP grade increased, the freeness (CSF) of recycled pulp was increased while paper strength and white water turbidity was decreased. Paper strength was decreased as the percentage of OCC was higher than ONP. When ONP was mixed with OCC, no adverse effect was observed except the increased drainage resistance. It is expected that these results could be utilized as fundamental data to establish regulations for the recovered paper grades according to mixing ratios of different kinds of them.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.2
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• pp.5-12
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• 2016

White waste papers are very important resources in the paper industry, but their use is limited because of the residual of fluorescent whitening agent (FWA). So the removal of FWAs from waste paper is an important task in the recycling process to improve the use of recycled resources. In this study, we focused on the FWAs used for surface treatments and carried out physical and chemical treatments to remove them from white waste papers. The white waste papers were disintegrated with a surfactant in different pH and temperature conditions, and then handsheets were made for the measurement of the fluorescence index, which is proportional to the amount of FWAs on papers. The effect of the flotation process on the removal of FWAs after disintegration was also investigated. The fluorescence index decreased as the disintegration time increased, but over a relatively long time, the fluorescence index increased again, which indicated the readsorption of the FWAs detached from the cellulosic fibers of the white waste papers. The lowest fluorescence index was shown when the waste papers were disintegrated with a 0.3% surfactant addition at pH 10 and at $45^{\circ}C$. However, the flotation treatment was not effective, because the flotation induced contact between the detached FWAs and the cellulosic fibers, and re-adsorption occurred.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.1
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• pp.16-23
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• 2004

Recently the increased concerns about the cost reduction and environmental protection make the paper industry increase the closure level of papermaking system, which results in the buildup of organic and inorganic materials in the papermaking process water. Increase of the system closure causes deterioration of additive performance and provokes diverse problems in papermaking process and product quality. To investigate the effects of process water quality on the physical properties of fine papers handsheets were prepared with process water containing various amounts of inorganic and organic contaminants including calcium or sodium ions and oxidized or cationic starches. Inorgainc and organic materials did not show any significant effect on the physical properties of handsheets. Recycled GCC showed the same trends as inorganic and organic materials. The performance of cationic starch was deteriorated, however, in the recycled white water, which resulted in the reduction of tensile index of handsheets.