• Journal of the Korean Wood Science and Technology
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• v.16 no.4
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• pp.70-78
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• 1988

To separate and utilize the main components of hardwood (Quercus mongolica) by organosov pulping (ester pulping), chips were cooked at various conditions such as; the solvent ratio (acetic acid: ethylacetate: water, 50:25:25; 33:33:34; 25:50:25), maximum temperature (165, 170, $175^{\circ}C$), and cooking times (2, 2.5, 3 hr). The pulps were bleached by the sequences of CEDED, C/DEDED, PEDED. Lignin, sugars, and acetic acid were separated from black liquor and washing liquors. 1. The selective delignification at optimal pulp yield (43-45%) was obtained by cooking at acetic acid: ethylace tate: water ratio of 33:34:34 for 3 hr at $170^{\circ}C$. But in this case, kappa no. of the pulp was not reduced under 60 points. 2. Kappa no. of the pulp could be dropped by an acetone wash to remove reprecipitated lignin a t cooked pulp. 3. The unbleached pulps had a brightness of 45-50%, whereas the bleached pulps gave at 88-93% brightness. Tensile, burst, and tear strengths of the bleached pulps were lower than those of kraft pulp, especially in tear strength. The pulps which were bleached with CEDED sequence were higher in strengths than another bleaching sequences. 4. Lignin of 90-95%(lignin base on wood)was separated from black liquor and washing liquors, while the purified sugars and recovery of acetic acid were a low. An organic phase composed of acetic acid, ethylacetate, and water was separated to a two-phase system by proper adjustment of the solvent ratios.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.5-12
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• 1998

Exploitation of the papermaking technology to reduce the strength loss that accompanies when using recycled papers as raw materials for papermaking is one of the most important issues imposed upon today's paper industry. Multi-layer sheet forming technology has been suggested as a way that provides some answers to this issue. In this study strength properties of single- and two-layer handsheets formed with recycled fiber and unbleached softwood kraft pulp have been examined to quantify the benefits when using two-layer sheet forming technology rather than a conventional single layer sheet forming precess. Single- and two-layer handsheets were made from 50% of OCC and 50% of Sw-UKP and their strength properties were evaluated. Also the strength properties made from Sw-UKP and OCC sheets were determined. A multihead, which can be attached on the top of hand- sheet former, was used to form two-layer sheets. Maximum strength properties could be obtained in the freeness range of 500∼300mL CSF for Sw-UKP Most of the strength properties was reduced by 30∼35% when 50% OCC was blended with UKP. Decrease of strength properties, however, could be reduced by employing a two-layer sheet forming method. Creator strengths could be obtained when UKP was positioned at the top layer of two layered sheets indicating greater UKP fines retention due to the filtration effect of the OCC layer formed prior to UKP layer contributed the strength improvement. Two-layer sheet showed lower Scott internal bond strength than single layer sheet. By incorporating some of UKP fibers into OCC layer this reduction could be reduced.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.3
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• pp.38-45
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• 1998

Soil and water contamination caused by the abundant use of agricultural chemicals including herbicides and fertilizers draws public concerns since these chemicals may pollute the agricultural lands as well as the food products grown on these lands. As a method to reduce the use of agricultural chemicals mulching with thin plastic film has been commonly practised for many years. Although use of the plastic film for mulching is very effective in preventing the growth of weed, it is almost impossible to remove all of the plastic film from the agricultural land and the remaining film eventually contaminates the soils. Therefore, it is very imperative to develop a mulching material that decomposes completely to prevent soil pollution problems and to enhance the competitive edge of domestic agriculture. Mulch papers are believed to have many positive characteristics in preventing problems caused by the plastic mulch film since it decomposes completely after use. However, the basis weight of mulch papers needs to be reduced to improve its handling properties and to reduce the raw material costs of pulps. In this paper the possibilities of using domestic old corrugated containers in producing mulch papers were examined. Also use of unbleached softwood kraft pulps and dry strength additives were exploited along with two-layered sheet forming technology in decreasing the basis weight of the mulch paper. Results showed that reduction of 20g/$m^2$ of basis weight of mulch paper was possible by the appropriate raw material selection and application of strength resin. To use the mulch papers in paddy fields, however, further research to improve its durability should be pursued.