• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.215-225
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• 2006

Today's requirements for print-press runnability and print quality demand an optimised absorption and adhesion of printing ink on the paper surface. Modern coating concepts for high glossing offset grades use ultra fine pigments, whereas binder level has continuously been decreased to a minimum in recent years to achieve the highest possible sheet gloss development and for economical reasons. Both the ultra fine pigments and the reduced binder levels lead in many cases to a faster ink setting rate. On the other hand, matt paper grades use relatively coarse pigments leading to a slow ink setting compared to the high glossing papers. Both too fast and too slow ink setting properties implicate drawbacks in print quality and print press runnability. The mechanisms behind the interactions between ink and coating have been presented in many previous publications. The purpose of this study was to determine and quantify how the ink setting rate is influenced by pigment system (GCC and GCC/clay blends), latex level and latex properties in the topcoat of double coated sheet fed offset paper. The roles of binder level and type in the precoat were also assessed. The effect of calendering (temperature and pressure) was studied with one formulation. The resulting ink setting characteristics were tested using three different laboratory testing instruments. The correlation amongst the different laboratory testing methods is discussed. The results show that by varying the latex properties, the pigment system and/or latex addition level, the ink tack development of ink applied to a topcoat pigment system can be significantly influenced. It can be slowed down as often desired with ultra fine pigments or speeded up in the case of coarse pigments. There was no visible effect on the ink setting rate by using different binder systems in the precoat..

• 한국콘텐츠학회논문지
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• 제15권1호
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• pp.74-85
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• 2015

RGB기반의 사진이미지를 오프셋 인쇄로 출력할 때 색역의 차이에 의한 색 손실이 발생하는 것은 상식이다. 따라서 사진가는 사진을 인쇄의뢰 할 때 일정정도의 색 손실을 감안하고 인쇄를 시행해야 한다. 이때 원본과 최대한 가까운 결과를 얻기 위해 시행하는 작업이 교정이다. 이러한 교정은 디지털기술이 도입되면서 관리가 용이해졌다. 즉 교정에 디지털장비를 사용하게 되어 교정의 질을 일정하게 유지 관리할 수 있게 되었다. 본 연구는 이러한 교정에 관한 연구이다. 기존에도 교정에 관한 연구가 있었지만 이는 인쇄분야에서 시행한 연구로 인쇄소 시스템을 기반으로 하고 있다. 즉 사진가가 거의 사용하지 않는 인쇄용 립(RIP)과 고가의 인쇄전용 장비를 필요로 하는 연구이다. 따라서 사진가 스스로 자신의 기준에 맞춘 교정을 시행하기 어려운 실정이다. 본 연구에서는 사진가가 직접 사진용 시스템을 이용하여 교정 작업을 시행할 수 있는 방안을 모색하기 위해 시행하였다. 즉 사진가가 주로 사용하는 포토샵 프로그램과 사진용 잉크젯 프린터 그리고 사진용지를 이용한 교정에 관한 연구이다.

• 펄프종이기술
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• 제34권5호
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• pp.1-17
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• 2002

The immobilization and consolidation of the model coatings based on the plastic pigment and latex binder of known particle sizes were theoretically Studied in terms of the dense random packing of binary spheres and varying extent of latex film shrinkage. The porosity of the model coatings was calculated based on three proposed latex shrinkage models: Maximum, Minimum, and Linearly Decreasing Latex Shrinkage. The increasing extent of latex shrinkage was calculated up to the critical pigment volume concentration(CPVC) as a function of plastic pigment volume fractions, and the maximum latex shrinkage was estimated from the CPVC. Also, the number of pores and the average equivalent spherical pore diameters were calculated based on those proposed models. The opacity and gloss of the model coatings on polyester films were measured and their porosity was also determined by a simple coat weight-thickness method. As expected, various coating structure-property-composition relationships, such as opacity, gloss, porosity, etc., were shown to exhibit sharp transitions near the CPVC. The CPVC values determined by the opacity, gloss, and porosity vs. PVC relationships, respectively, agreed very well with each other. Especially, the CPVC's determined by the opacity and porosity vs. PVC curves were identical. The comparison between the theoretically calculated and experimental porosity values showed that the intermediate value between the maximum and minimum latex shrinkage would best fit the experimental porosity data. The effect of plastic pigment particle size on the optical properties and porosity of model coatings was also studied and it was observed that the coating opacity and porosity increased with increasing plastic pigment particle size, but the gloss decreased. The ink gloss of the uncalendered model coatings applied onto commercial sheet offset coated papers was shown to be affected by both the coating gloss and porosity: the higher the coating gloss, the higher the ink gloss, but the higher the coating porosity, the lower the ink gloss. Their printability was also studied in terms of the number of passes-to-fail and the rate of ink setting as a function of both plastic pigment volume fractions and plastic pigment particle sizes. A minimum crack-free temperature(MCR) of latex-bound coatings was proposed to better predict the behaviors of latexes as coating binders. The wet state of model coating dispersions, the surfaces of consolidated model coatings, and their internal structure were examined by both electron and atomic force microscopy, and their micrographs were found to be consistent with our immobilization and consolidation models.