• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.11-19
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• 2008

The paper established a new method for fast measurement and characterizing of sub-visible dirt of recycled paper which is too small to be seen with naked eye. This method provided a new way for the evaluation of recycled paper that is hard to be characterized by the conventional method. Two effective thresholding algorithms HA and SDA were compared and their applicable conditions were discussed. Results showed that the HA could be used for un-printed paper while SDA is suited for recycled papers. The gloss of paper samples was measured and the relation between gloss and sub-visible dirt was investigated. The significant effect of this method for characterizing and comparing paper was exhibited. The experiment results indicated that sub-visible dirt measuring method could be a complementariness of the conventional methods.

• 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.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.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.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.31 no.2
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• pp.34-41
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• 1999

Adsorption of cationic polyacrylamide dry strength resins onto the surface of papermaking fibers and fines is critical for their effective utilization. Since dry strength resins are frequently employed when recycled fibers containing a great deal of fines are used as a raw material, their adsorption characteristic onto the recycled fiber fines is of great importance. In this study, effects of recycling on adsorption characteristics of cationic polyacrylamide onto primary and secondary fines were examined. Never dried bleached hardwood kraft pulp was beaten and dried for recycling. In each recycling step the adsorption characteristic of a cationic PAM onto primary and secondary fines was evaluated by kjeldahl nitrogen analysis method. The influence of recycling on water retention value and carboxyl content along with the sheet density and tensile strength was examined. Secondary fines of never dried pulp adsorbed twice as much of C-PAM as the primary fines, however, the adsorption capacity of the secondary fines decreased rapidly during the course of recycling and showed lower adsorption capacily than primary fines.

• 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.

• 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.

• Resources Recycling
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• v.19 no.3
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• pp.62-70
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• 2010

As the demand for paper continues to grow and the importance of recycled paper, white ledgar(WL) and old newspaper pulp(ONP), continuously increase. In addition, usage of recycled paper is essential in terms of forest conservation and environmental protection issues. However, optical and mechanical properties of recycled paper have some drawbacks than regular paper's properties that is indispensable. In order to complement these problems of recycled paper, precipitated calcium carbonate (PCC) was synthesized by the In-situ process with a recycled pulp. Depending on the size of PCC is divided into 2 types, $0.01{\mu}m{\sim}0.09{\mu}m$ colloid type ultra-fine particle and $0.1{\mu}m{\sim}0.9{\mu}m$ cubic type particles. In this study, we analyze how the different shape and size of precipitated calcium carbonate affects in the optical and mechanical properties of the recycled paper used as a filler. Furthermore, we mixed with chemical pulp for overcome reduce of mechanical properties, without using other chemicals, when we use PCC as a filler. The results has the possibility to meet in GR excellent recycling certification mark, standard was proposed.

• 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.