• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.4
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• pp.27-33
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• 2000

A new technique for fractionating pulp stock into a long fiber portion and fines fraction was developed by KRICT in order to enhance the drainage and strength properties of recycled OCC pulp. In order to investigate the effect of fines contents in stock and stages of flotation on fractionation efficiency, flotations were performed at varied fines contents and flotation stages. Based on the result of multi-stage flotation fractionation it could be said that fines smaller than 15${\mu}{\textrm}{m}$ stabilize flotation froth of OCC. Although the amounts and the fines contents of flotation reject could be increased by multi-stage flotation fractionation of OCC, flotation stages more than 3 times were found to be inefficient in terms of fines concentrating degree. In order to satisfy the both conditions of reducing long fiber loss and of increasing flotation reject, several kinds of fractionating promoters were searched and investigated. And high molecular weight cationic polyacrylamide was chosen as a long fiber flocculating and flotation froth-stabilizing agent.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.2
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• pp.24-31
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• 2001

As a novel method to improve strength properties of recycled test liner, Condebelt press drying system was introduced and adopted into Korea. New press drying treatment could enhance the surface and strength properties in accordance with the increase of sheet density. However, Condebelt drying can not increase the density of repeatedly recycled test liner as much as that of virgin UKP and at the same density condition, the strength of Condebelt press dried UKP is greater than that of press dried test liner. In order to increase the strength of test liner, two attempts were tried in this study. First, addition of polyelectrolytes, dry strength agent was investigated with a view to promote the fiber bonding potential of reclaimed corrugated container pulp. Second, blending effect of fines were analyzed in an aims of increasing density and strength of test liner. The results were as follows; Even in the case of test liner densified by Condebelt press dryer, addition of amphoteric PAM as a dry strength agent was effective in increasing strength properties and so the effect of dry strength agent on improving bonding potential of recycled OCC fiber could be confirmed. As an appropriate addition level of amphoteric PAM, below 1% based on dry pulp weight was suggested. Different from virgin UKP, density of recycled test liner can be increased by the blending of OCC fines and strength properties also can be improved. However, excessive blending of OCC fines could result in decreasing of density and serious weakening of test liner. The best blending ration of fines in test liner can be determined as about 30%. Taking into account the fines content in general OCC pulp as 50%, excessive 20% of fines were supposed to be fractionated and removed in order to achieve the best strength of Condebelt press dried test liner.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.3
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• pp.91-98
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• 2016

Linerboards have been produced by recycling recovered paper such as old corrugated containers(OCC). Usually linerboards produced during summer season show weak strength compared with those of produced during winter. In order to cope with the weak strength of linerboards produced during summer, and to confirm uniform quality, it is important to understand the seasonal effect on strength properties. Effect of pulping temperature of the OCC for linearboard production was investigated by controlling pulping temperatures at $18^{\circ}C$ and $51^{\circ}C$. Low pulping temperature ($18^{\circ}C$) caused more generation of fines in stock. Consequently retention and drainage of linerboard defibrated at high pulping temperature ($51^{\circ}C$) were better than those of $18^{\circ}C$. Strength properties of handsheet at low pulping temperature were higher than those of high pulping temperature and it could be confirmed that low pulping temperature during winter is one reason of seasonal variation of recycled linerboard strength. It is considered that surface modification of OCC fibers by harsh pulping action during winter caused increase of paper strength.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.2
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• pp.25-33
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• 1999

A great difference in drainage time was observed from the recycled stocks between corrugated container board and its component papers, liner and medium paper. It could be assumed that the different drainage property should be caused from a starch adhesive present in the corrugated board. Thus, three types of starch such as dried Stein-Hall adhesive, cooked starch solution, and its dried film were added to linerboard stock in order to investigate the mechanism of drainage reduction. The water-swollen starch particles derived from Stein-Hall adhesive were drastically deteriorated the drainage time, even though the amount of starch is very small (2% or below). The drainage time of OCC was improved by 25% when amylase was used a new biological treatment. The results from the lab and mill test showed that the starch-degradable enzymatic treatment improves the drainage property as well as the reduction of calcium hardness.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.367-373
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• 1999

Increasing consumer demand for recycle of most paper products is challenging manufacturers to use lower value raw materials while maintaining high quality. This study was carried out to investigate the composition of old corrugated containers (OCC) and to manufacture printing and writing papers of over 85% (ISO) brightness by ECF and TCF bleaching from OCC. Fiber length of American old corrugated container (AOCC) was longer than that of Korean old corrugated container (KOCC) in fiber length. The former was composed of unbleached kraft pulp (UKP) of about 80 percentage, the latter about 20 percentage. OCC is feasible for manufacturing of pulps i.e., AOCC is for printing and writing papers and KOCC is for whiteboards, in the aspects of brightness and mechanical properties on the other hand, the cost of manufacturing upgraded papers by OCC is high because of bleaching chemicals. Neverthless, considering various aspects, especially environment, there are many advantages in recycling. In case of the treated AOCC pulp, over 85% (ISO) brightness can be achieved through TCF or ECF bleaching step, while the treated KOCC pulp did not allow high brightness through TCF bleaching. The tensile index of the bleached KOCC pulp was lower than that of the bleached AOCC pulp, but the burst and tear index of KOCC was higher than that of AOCC.

• 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.36 no.4 s.107
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• pp.1-8
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• 2004

Linerboards and corrugating mediums are being produced using recycled old corrugated containers (OCC) as major raw materials. The utilization rate of recycled fibers is ex­pected to increase further in the future to reduce raw material cost. Use of recycled fibers as raw materials for linerboard, however, causes many problems for papermakers. As the utilization rate of recycled fiber and number of recycling of fibers increases, quality and process problems including strength reduction and deterioration of machine runn­ability will increase. To overcome the problem of strength reduction associated with the use of recycled fibrous materials for producing quality linerboards, diverse extensive research efforts and new technological approaches have been taken. In this study, disintegration characteristics of aee was evaluated by determining the unslushed contents. The amount of unslushed content of KOCC was lower than AOCC. But contaminants content of KOCC was higher than AOCC. As the consistency in disintegration increased, the amount of unslushed fiber content decreased.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.1 s.109
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• pp.17-24
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• 2005

The increase of using low grade ace, the unsorted mixed grade, as fibrous raw materials for the packaging paper results in the increment of fine screen reject owing to the strong tendency to reduce the slot width. Since the most of screen reject consists of undispersed fiber flake, the suitable treatment of the flake could increase the yield of ace recycling and decrease the amount of solid waste. In this work, the novel method combined the mild mechanical treatment by using Tumbling pulper with the biological treatment was developed and applied to the wet strength flake and the fine screen tail line reject originated from a packaging paper mill. The results showed the new method could provide much better efficiency for the disintegration of undispersed flake and for the recovery of fiber from the rejects. The application of the laboratory scaled-Pack pulper showed the possible separation technique for mill application by fractioning effectively the fiber from the treated solid waste.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.94-102
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• 2014

The physical and chemical properties of recycled fibers from mixed waste paper are more and more deteriorated because of unknown history of recycling times. In order to improve the mechanical properties of liner paper, the recycled fibers from wasted cotton clothes were used in papermaking process, and their applicabilities were evaluated in several points of fiber modification. Thus, two kinds of fiberizing methods from waste cotton clothes were considered by using rotary sandpaper and grinder mill. Finally, the rotary sandpaper method was relatively desirable in preserving longer fiber length and fibrillated fiber surface. The recycled cotton fibers by swelling treatment with NaOH and bleaching with reductive chemicals were mixed with OCC fibers, and the handsheets were prepared to basis weight of $80g/m^2$ and evaluated the mechanical properties of paper. The fibrous properties showed outstanding results in freeness and WRV improvements by alkali treatment and high brightness by reductive bleaching treatment. The physical and mechanical properties of sheet by mixing OCC fibers and recycled cotton fibers were also highly improved in tensile, burst strength and specially folding resistance.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.2
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• pp.15-24
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• 1999

A new technique for recycling of white water was developed in order to reduce the calcium hardness in a closed OCC recycling system. Calcium ions present in the white water were precipitated as calcium carbonate by reacting with sodium carbonate, and the precipitated $CaCO_3$ was removed from the system using a flotation fractionation method, which has been commonly used in deinking process. In the flotation stage, a mixed gas of $CO_2$-air was purged into the flotation cell because the pH of $Na_2CO_3$-treated white water was reduced to neutral by $CO_2$ gas. Since $CaCO_3$ precipitate tends to stick onto fine fiber surface and then selectively removed from the white water, a proper amount of suspended solid in white water acts as an important factor for deciding the removal efficiency. By the application of $Na_2CO_3$ addition-$CO_2$ flotation to the short circulated white water, the calcium hardness was significantly reduced by 87% and more. Removal of calcium ions with fine fibers led to a drainage improvement, reduction of fresh water consumption, and enhanced efficiency of wet-end chemicals.