• 펄프종이기술
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• 제48권3호
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• pp.23-29
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• 2016

Effects of cationic polyvinylamine (PVAm) dry strength agent on effectiveness of optical brightening agent (OBA) during fine papermaking and the mechanism for brightness reduction of paper by PVAm was investigated by UV/Vis spectroscopy and turbidity measurement of OBA solution with PVAm. It was shown that PVAm reduced brightness of paper while opacity was not varied and tensile strength of paper was increased. Tetra-type OBA solution showed the peaks around the wavelength of 280 nm and 330 nm and the increase in the OBA concentration increased the UV absorbance in all wavelength. Addition of PVAm into the OBA solution decreased the UV absorbance at 280 nm. Turbidities of OBA and PVAm solutions were close to zero, respectively, while the turbidity value increased for the mixed solution of OBA and PVAm in various mixing ratios and the highest value was obtained when the mixing ratio of PVAm and OBA was 5:5, meaning that cationic PVAm formed complex with anionic OBA. In conclusion, cationic PVAm could form a complex with anionic OBA and that reduced UV absorbance, resulting in the reduced brightness of paper.

• 펄프종이기술
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• 제47권6호
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• pp.66-72
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• 2015

This study was conducted to investigate the effects of optical brightening agents (OBA) on the chemical degradation characteristics of paper cellulose during humid heating aging. Three different types of OBAs were applied to a filter paper by dipping it in OBA solutions whose concentrations were controlled to 1% and 2%. The filter papers with an OBA were artificially aged at $80^{\circ}C$ and 65% RH, and the changes in pH of paper and viscosity of cellulose were evaluated. Their functional groups were also analyzed by ATR-FTIR (at-tenuated total reflectance fourier transform infrared spectroscopy). It was found that OBAs influenced the chemical degradation of paper cellulose during humid heating aging. Higher concentration of OBA solutions accelerated the degradation of paper cellulose. Especially, after aging for 12 days, the paper cellulose treated with the tetra-type OBA were the most significantly aged among the three types of OBAs. It was assumed that pH of OBA solutions affected the aging characteristics.

• 펄프종이기술
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• 제46권6호
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• pp.87-93
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• 2014

Optical brightening agents (OBA) is generally used to improve the optical property of printing paper in the paper industry. However, effects of OBA addition on paper preservability has been not fully understood yet. Therefore, this study was aimed to investigate effects of a OBA on the aging characteristics of paper. The OBA treatment of three different types was performed by dipping a filter paper into each a OBA solutions of different concentrations. The filter papers applied with a OBA were artificially aged at 80oC and 65% RH, and their optical and mechanical properties were evaluated. It was found that application of OBAs influenced the aging characteristics of paper. Especially, after aging, the optical and mechanical properties of the filter paper treated with the tetra-type OBA were more significantly decreased than those of the non-treated filter paper. The more the concentration of the tetra-type OBA increased, the more decreasing rate of optical and mechanical properties of the filter paper. While, in case of di-type OBA and hexa-type OBA, paper optical and mechanical properties were slightly decreased or not changed with a OBA treatment.

• 펄프종이기술
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• 제46권4호
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• pp.54-61
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• 2014

Effects of artificial thermal aging on color variations of various commercial papers (fine paper, coated paper, newsprint and filter paper) were investigated. With thermal aging at $105^{\circ}C$, most of papers showed a special trend in $a^*-b^*$ plane: the $a^*$ (red-green) values of the samples were initially reduced (heading to - $a^*$ side) and after a turning point they increased to +$a^*$ side while the $b^*$(blue-yellow) values were kept increased to +$b^*$ side (yellowing of paper). Different papers had different turning points for $a^*$ value. The filter paper consisted of a pure chemical pulp and the copy paper with OBA (optical brightening agent) showed the latest turing points. In addition, the papers without OBA showed less reduction in brightness compared with that with OBA, suggesting that OBA could adversely influence the brightness stability during thermal aging.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Pre-symposium of the 10th ISWPC Recent Advances in Paper Science and Technology
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• pp.296-301
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• 1999

Different papers such as toilet and towel tissue, newsprint and copy paper made from reclaimed fibres were characterized using UV-VIS reflectance and fluorescence spectroscopy. The emission properties of the extracts of the papers were also evaluated. Photochemical irradiation at ambient temperatures, and thermal aging of the copy papers at 105$^{\circ}C$ and 150$^{\circ}C$ were performed. Post-colour numbers (PC) were calculated from the reflectance values measured from the corresponding UV-VIS reflectance spectra. Light absorption coefficient spectra were calculated before and after irradiation, and the changes in absorption coefficient were related to the content of chromophores in the papers. Photochemical and thermal discolouration of the copy papers, similar to that of virgin fibres, was readily observed. The influence of changes in the concentrations of fluorescent brightening agents and dyes on the spectral properties was also assessed. Photostabilization studies of the copy papers were performed with the use of polymer additives polyethylene glycol (PEG) and polytetrahydrofuran (PTHF).

• 공업화학
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• 제27권2호
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• pp.195-198
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• 2016

DMT 생산과정의 부산물로서 폐기 처리되어 왔던 MFB를 출발 물질로 하여 고급 형광증백제 중의 하나인 4,4'-bis(2-benzoxazolyl)stilbene (BBS) 합성을 4단계를 거쳐 총 수율 73%의 경쟁력 있는 공정개발을 수행하였다. 제시된 합성법은 MFB와 ethyl 4-((diethoxyphosphoryl)methyl)benzoate (1)과 반응시킨 후, coupling 생성물 4,4'-stilbenedicarboxylate (2)를 얻고 이를 4,4'-stilbenedicarbonyl chloride (3)으로 변환 후 BBS 합성의 핵심 단계인 benzoxazole 형성 단계에서 상용화가 가능한 용매와 촉매를 탐구하여 용매로는 1,2,4-trichlorbenzene 촉매로는 boric acid의 사용이 가능한 것을 확인하였다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2011년도 춘계학술발표회 논문집
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• pp.235-241
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• 2011

Effects of thermal aging on color variations of various papers were evaluated. With thermal aging, most of papers showed a special trend in $a^*$-$b^*$ plane: $a^*$ (red-green) values of the samples were reduced at beginning and after a turning point it was increased while $b^*$ (blue-yellow) was kept increased (yellowing of paper). In case of filter paper which consists of chemical pulps, the changes in $a^*$ value was occurred late compared with other samples. In case of the copy paper with optical brightening agent, the turning point in $a^*$ was not observed while a constant increase in $b^*$ was observed. In case of color paper, no specific trends in $a^*$-$b^*$ were found.