• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.3
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• pp.11-20
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• 2011

The conditions to which pulp fibers are exposed during paper production, converting, storage, use, and recycling can induce various changes in fiber morphology, surface characteristics, and suitability for paper production by recycled fibers. Most of those changes can be described by hornification. Paper has highly hygroscopic properties which affect dimensional change by relative humidity variation of surrounding condition. The purpose of this study was to investigate the dimensional stability, moisture contents and dip elongation of handsheets at different relative humidity conditions of recycled kraft pulp and BCTMP. By using recycled fibers, dimensional stability was increased because hygroscopic properties of fibers decreased with repeated recycling treatment. Dip elongation of recycled pulp was higher than that of virgin pulp because of its weak fiber-to-fiber bonding. By recycling pulp, the relative bonded area was decreased because fiber could not swell more than virgin pulp. Dimensional stability largely depended on the equilibrium moisture contents of paper, the fiber-to-fiber bonding strength, and the relative bonded area.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.4 s.112
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• pp.18-25
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• 2005

The mechanical strength is the prime requisite for linerboard and corrugating mediums. Repeatedly recycled OCC fibers show less suitable property for papermaking mostly due to hornification and reduced fiber length. To overcome these problems many researches including fractionation, enzymatic treatment, and chemical or mechanical treatments of fibers have been carried out. In this study, the effect of mechanical treatment by high consistency pulping on the characteristics of recycled fibers as well as mechanical properties of sheets were investigated. Results on the strength properties of handsheets made of recycled fibers that were treated to same freeness level by beating and high consistency pulping, respectively, showed that beating treatment was more efficient in improving strength. Drainage and recycling potential of the fibers treated by high consistency pulping, however, were expected to be superior to beating because fines content and fiber length didn't change significantly.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.11a
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• pp.183-199
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• 2001

Alternative way of shaping fibers suitable for papermaking was introduced. Impact refining, which was done simply by hitting wet fibers with a metal weight vertically, was intended to keep the fibers from shortening and to cause mostly internal fibrillation. Virgin chemical pulp, its recycled one and OCC were used in the experiment. It was noticed from the experiment that impact refining on virgin chemical pulp kept the fiber length and Increased bonding properties greatly, However, in the recycled fibers from the chemical pulp, fiber length and bonding properties were decreased. In OCC, which seems to contain fractions of semi-chemical pulp and mechanical pulp (GP), and which is recycled pulp from corrugated boxes, fiber length and bonding properties were decreased disastrously. We believe recycled cellulosic fibers (recycled chemical pulp and OCC in this case), which went through hornification, were less resistant to the mechanical impact than virgin chemical pulp. For virgin chemical pulp, impact refining allowed no significant fiber length shortening, high WRV, and high mechanical strength.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.1
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• pp.45-52
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• 2001

Recycling of wastepaper is very important for the environmental protection. However inferior strength and slower drainage characteristic that are brought by the hornification and the increase of fines respectively limited the increase of wastepaper recycling. The purpose of this study is to obtain some fundamental information that is helpful to develop the technologies which can improve the characteristics of recycled fibers. Softwood bleached kraft pulp was curlated with Hobart mixer at several different consistency. The curlation of fibers can cause the internal fibrillation and decreasing the crystallinity without serious damage of fiber surface. Curl index, kink index, freeness and WRV were increased, but crystallinity was decreased with the increase of curlation consistency.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.1
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• pp.1-6
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• 2003

This study was carried out to investigate the effect of internal fibrillation on the pulp and paper properties. The internal fibrillation was introduced into the SwBKP and recycled SwBKP by the mechanical treatment with Hobart mixer. WRV and physical properties of SwBKP were improved by the internal fibrillation. However the mechanical treatment of recycled SwBKP resulted in the decrease of strength properties of paper except for the tear index, although it was observed that WRV was somewhat increased by the mechanical treatment. The decrease of strength properties of recycled SwBKP might be caused by the hornification of fiber and the decrease of fiber strength.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.2
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• pp.12-17
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• 2003

The effects of wet pressing and drying conditions on the disintegration and physical properties of paper were investigated in order to get the basic information on the resistance of paper for aqueous solution during converting processes. Wet pressing of unbeaten bleached softwood kraft pulp increased WRV at the range of grammage investigated. The increase of WRV with grammage at low wet pressing pressure(50 psi) was obvious, while it was not significant at higher wet pressing pressure(110 psi). The changes of WRV by drying were affected by the grammage and wet pressing pressure. The poorer disintegration of sheet, the higher wet pressing pressure and drying temperature. Although the strength properties were increased with the grammage, wet pressing pressure and drying temperature, results showed different trend from those of beaten pulp.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.3
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• pp.7-14
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• 1998

It is well known that the recycling of pulp generates a lot of fines, and cause the hornification of fiber. Both phenomena have been contributed to a limited use of recycled fiber. Among several means which can improve the properties of recycled fiber, enzymatic treatments are considered as an effective means. Thus the effects of xylanase on the properties of recycled pulp were investigated in this study Xylanase treatment showed some refining effect at a small dosage while the fines and fibrils were reduced at higher dosage as shown in the treatment with cellulase-hemicellulase. The interesting finding is that the WRV of recycled fiber treated with xylanase was higher than that treated with the mixture of cellulase and hemicellulase. Breaking length and tear index of recycled fiber treated with xylanase were also higher.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.1
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• pp.24-29
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• 2001

The base paper of corrugated board is mainly produced from Korean old corrugated container (KOCC), and thus the recycling rate of KOCC is very high. However, there is a problem that the pulp quality is very low while the recycling rate of OCC is high. The fines content in KOCC, the main source of the corrugated board, amounts to nearly the half of the total stock, and its formation increases as recycling process repeats due to the hornification of fiber. There have been attempts to improve the drainage property of OCC by increasing the headbox concentration of the paper machine or by applying drainage-promoting polymer additives. However, these conventional methods have problems of weakened paper strength and lowered converting fitness caused by paper formation hindrance. The strength of linerboard could not be increased in case KOCC is used, because hornified OCC pulp can-not be sufficiently refined due to the lowered drainage property caused by fines formation. We studied about a new technique consisting of froth-flotation for fractionating pulp stock into a long fiber portion and fines fraction. This study will be developed in order to enhance the drainage and strength properties of a recycled OCC pulp by selective treatment of flocculant on fractionated OCC Fines.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.5
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• pp.56-62
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• 2002

Alternative way of shaping fibers suitable for papermaking was introduced. Impact refining, which was done simply by hitting wet fibers with a metal weight vertically, was intended to keep the fibers from shortening and to cause mostly internal fibrillation. Virgin chemical pulp, its recycled one and OCC were used in the experiment. It was noticed from the experiment that impact refining on virgin chemical pulp kept the fiber length and increased bonding properties greatly. However, in the recycled fibers from the chemical pulp, fiber length and bonding properties were decreased. In OCC, which seems to contain fractions of semi-chemical pulp and mechanical pulp (GP), and which is recycled pulp from corrugated boxes, fiber length and bonding properties were decreased disastrously. We believe recycled cellulosic fibers (recycled chemical pulp and OCC in this case), which went through hornification, were less resistant to the mechanical impact than virgin chemical pulp. For virgin chemical pulp, impact refining allowed no significant fiber length shortening, high WRV, and high mechanical strength.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.3
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• pp.21-29
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• 2011

Recently, the use of recycled fibers was increased in order to replace the virgin pulp for low production cost and forest conservation. However, the recycled fibers decreases drainage rate, papermaking efficiency and product quality by short fibers and low wettability because of hornification. To overcome the limitation of low drainage rate, the technology of organic fillers were applied. Wooden fillers gave high bulk and stiffness of paper, but they reduced the strength of paper. In order to improve strength properties 4 types of strength additives were added and analyzed. Cationic starch, branched strength additive, linear wet strength additive, and linear dry strength additive were used. The drainage rate and paper properties such as bulk, air permeability and tensile strength were measured. As results of analysis, addition of branch type of strength agent such as C-starch was effective than linear type of strength agent in the drainage rate. Nevertheless there was no effect on the drainage rate by adding the pretreated wooden fillers. By adding the pretreated wooden fillers, bulk, air permeability and tensile strength of handsheets were improved with low dosage than non-pretreated fillers.