• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2006.06b
• /
• pp.325-329
• /
• 2006

Nippon Paper Industries, Co., Ltd. declared conversion of all the bleaching process to ECF, and most of the production had converted by now. To reduce ECF bleaching cost, we found that depending on electricity supply condition of the mill, utilization of ozone bleaching could be very effective. In addition, hot acid treatment of unbleached pulp also seemed to be effective for hardwood. In this study, several conditions for each technology were examined with the pulps from our own mills to reduce bleaching cost and to keep fiber quality acceptable level. In hot acid treatment study, with mild conditions (temperature lower than $90^{\circ}C$), sufficient reduction in Kappa number and hexenuronic acids content of the pulp were observed, while pulp viscosity was maintained. Moreover, to maintain strength of bleached pulp that subjected both to ozone bleaching and hot acid treatment, recommended Kappa number after ozone bleaching was more than 3. Based on these findings, two of our mills had installed medium-consistency ozone bleaching facilities and three mills installed hot acid treatment. Especially in Yatsushiro mill, both were installed in one bleaching line (A-ZD-E/P-D sequence), and running successfully.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.23 no.6
• /
• pp.954-958
• /
• 1994

The bleaching effect of chlorophyll a by two lipoxygenase isoenzymes (LOX-1, LOX-2) isolated from potato tuber(variety DEinma ) was studied. In the presence of LOX-1 or LOX0-2 with linoleic acid chlorophyll a bleaching occurred during two isoenzymes-mediated oxidation of linoleic acid. Chlorophyll a bleaching porceeded with decreasing in the formation of conjugated dienes form linoleic acidyb LOX-1 and LOX-2 . In the presence of chlorophyll a, LOX-2 showed a markable decrease inproduction of conjugated dienes from linoleic acid and a higher chlorophyll a bleaching activity. compared with LOX-1. These results suggest chlorophyll-bleaching reaction required intermediates formed during the peroxidation of linoleic acid by lipoxygenase isoenzymes, thus preventing formation of conjugated dienes.

• Fashion & Textile Research Journal
• /
• v.6 no.4
• /
• pp.511-514
• /
• 2004

We studied on the bleaching properties of silk fabric by vapor type ozone processing using ozone's strong oxidation instead of 28% $H_2O_2$ chemical treatment. When vapor type ozone processing was directly treated to fabrics retaining water to 50~70% pick up ratio, high concentration ozone was generated 14,000ppm(168 mg/h) approximately and finally its bleaching improved. The fabric's bleaching effect was improved because vapor type ozone generated the highest decomposition to oxidation of surface and inter molecules. The experiment revealed that fabric's bleaching was improved by change of the pick-up ratio of vapor type ozone processing. However, tensile strength and elongation were reduced by increase of time, and the time that was assumed as the most optimized time to minimize the reduction of fabric's tensile strength and elongation as well as maximizing the fabric's bleaching was 30 minutes.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.44 no.3
• /
• pp.79-85
• /
• 2012

In this study, purified cellulose was prepared from rice husk which is one of the major agricultural residues in Korea. The various bleaching processes such as ozone bleaching, $ClO_2$ bleaching and $H_2O_2$ bleaching were applied to remove residual lignin and impurities. In order to increase the contents of ${\alpha}$-cellulose contents, the effects of acid and alkali treatments were evaluated. Although the multi stages of the bleaching processes resulted in less than 0.5 % residual lignin contents, the application of ozone leaded to the decrease in DP(degree in Polymerization) and ${\alpha}$-cellulose contents. The alkali treatment after bleaching processes resulted in pure cellulose which showed more than 98% of ${\alpha}$-cellulose contents.

• Journal of the Korean Academy of Esthetic Dentistry
• /
• v.9 no.1
• /
• pp.74-81
• /
• 2000

• Korean Journal of Human Ecology
• /
• v.14 no.3
• /
• pp.433-439
• /
• 2005

In this study, we investigated the morphological and physical changes of hair after bleaching treatments with different concentration of hydrogen peroxide in bleaching agent (3, 6, 9, or 12%) and various treatment time (10, 30, or 60 minutes). Tresses of virgin black hair were bleached using a commercial ammonium persulfate-hydrogen peroxide solution. The tensile strength of virgin hair treated with a bleaching agent depended on the concentration of hydrogen peroxide and the treatment time. As the concentration of hydrogen peroxide in bleaching agent went high and the treatment time increased, the tensile strength of the hair increased but the extension degree decreased. The virgin hairs which were not treated by bleaching agent showed morphologically healthy cuticle, whereas the bleached hairs showed swelled and damaged cuticle patterns. The swelling of the hair and the breaks of the cuticles increased positively by the concentration of hydrogen peroxide and the treatment time. These results suggest that exposure to more concentrated hydrogen peroxide with other bleaching components may lead to more severe hair damage.

• International Journal of Oral Biology
• /
• v.39 no.4
• /
• pp.187-192
• /
• 2014

Nonthermal atmospheric pressure plasma has attracted great interest for biomedical applications. The plasma consists of charged particles, radicals, and a strong electric field as the fourth state of matter. This study evaluated the change in the surface roughness after tooth bleaching by plasma in combination with a low concentration (15%) of carbamide peroxide, specifically whether the application of plasma produced detriments, such as demineralization and structural change, with the goal of efficient and safe tooth bleaching. After being combined with plasma and 15% carbamide peroxide, the hydroxyapatite surface was significantly smoother with a low roughness average value. Tooth bleaching with 15% carbamide peroxide alone produced an irregular surface and increased the surface roughness with high roughness average value. Tooth bleaching with plasma resulted in no significant variations in hydroxyapatite in terms of change in surface roughness and surface topography. The application of tooth bleaching with plasma is not deleterious to dental hard tissue, implicating it as a safe tooth bleaching technique.

• Restorative Dentistry and Endodontics
• /
• v.20 no.2
• /
• pp.802-811
• /
• 1995

The purpose of this in vitro study was to compare the bleaching effect and the surface change according to three bleaching agents (Rembrandt, Natural White, Hi-Lite). Teeth were stained by artificial food colorants for 6 weeks and bleached for 4 weeks. The teeth were evaluated with spectrophotometer after bleaching on the 1st week and on the 4th week. The surface change of enamel was evaluated under SEM after exposure to 3 agents for 1 and 24 hours. The results were as follows : 1. All groups showed increased Lightness difference after bleaching. 2. After 1 week, only Rembrandt group showed significant bleaching effect compared to control group. 3. After 4 weeks, Rembrandt group and Hi-Lite group showed significant bleaching effect compared to control group. 4. SEM evaluation revealed that enamel surface underwent considerable change after 24 hours. Scratch disappeared and smooth surface was shown.

• The korean journal of orthodontics
• /
• v.48 no.6
• /
• pp.377-383
• /
• 2018

Objective: This study was performed to investigate the effects of external tooth bleaching with flouridation on the appearance of white spot lesions (WSLs) in vitro. Methods: In total, 125 bracket-bonded bovine incisor enamel blocks with artificial WSLs were randomly divided into a control group and four treatment groups (home bleaching, home bleaching + fluoridation, in-office bleaching, and in-office bleaching + fluoridation). A spectroradiometer (SR) and digital images (DIs) were used to evaluate colorimetric parameters (Commission Internationale l'Eclairage $L^*a^*b^*$) for all specimens. Color measurements were obtained before WSL formation (T1), after WSL formation (T2), and after completion of the external tooth bleaching treatment (T3). Results: The SRbased color change after bleaching was significantly greater in the treatment groups than in the control group (p < 0.05). SR-based lightness ($L^*$) and redgreen ($a^*$) values were significantly higher at T2 than at T1 (p < 0.001), with no significant changes in yellow-blue ($b^*$) values. At T3, SR-based $L^*$ values had increased while $a^*$ and $b^*$ values had decreased in the treatment groups (p < 0.001). The DI-based color difference between the sound enamel and WSL areas (DE*DI) increased significantly from T1 to T2 in all groups (p < 0.001) and significantly decreased from T2 to T3 in the treatment groups (p < 0.001). No significant differences in ${\Delta}E^*DI$ at T3 were shown between the four treatment groups (p > 0.05). Conclusions: The findings of this study suggested that external tooth bleaching with fluoridation can alleviate the conspicuity of WSLs.

• Restorative Dentistry and Endodontics
• /
• v.26 no.5
• /
• pp.399-408
• /
• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.