Earticle

The rheological characteristics of an ink relate to its performance on the press and to the printing quality such as ink stability, transfer characteristics, mottle, squash, misting, dot gain, and so on. For lithographic print, the emulsification of ink is an important factor to determine the product. And also the rheological characteristics of the emulsified ink should be investigated. Thus, in this study, the effects of the changing molecular weight of rosin modified phenolic resin on the water-pickup ratio of neat inks were studied. And then rheological properties of neat inks and emulsified inks with changing molecular weight of rosin modified phenolic resin were analyzed by using rotational rheometer.

We investigated the effects of the enzyme treatment of fiber for printability of coated paper. The results could summarized as follows, 1. The samples with enzyme treatment (average 87.8%) have higher ink gloss than the blank (85.6%). Printed density showed same trends with the ink gloss. However, the β-Glucosidase treated sample showed the lowest printed density (2.14 %) due to the lowest thickness of the ink layer, which is influenced by coated weight and surface smoothness. 2. The samples whose base paper was Xylanase and β-Glucosidase treated showed higher surface strength (4.2% and 4.0%, respectively) than the blank while the samples with the Hernicellulase and β-Glucuronidase treatment showed lower surface strength (3.2%and 3.7%, respectively) due to the influence of air permeability. 3. Hemicellulase and β-Glucuronidase treated base paper, which have relatively low air permeability, showed better ink repellence (4.3 and 4.4 %, respectively) than the blank (3.8 %). 4. The blank and the Xylanase treated base paper showed high set-off, which is the last category of printability.

Color reproduction is one of the most important expression factors in digital printing. In this paper, an experiment was done where the characteristics of color reproduction in digital printing. The results could summarized as follows. The printing used device profile showed a color difference of less than printing used default value in digital printing. As a result of weighting color difference, a difference between color gamut of digital original and color gamut of printing, when transforming the RGB color space to CMY color space, a exclusion the gray revision. The solution is to optimize the color transformation by gamut mapping and gray revision.

본 연구에서는 PCB에 진공인쇄 방식이 적용된 스크린 인쇄방법을 이용하여 Pattern 및 Hole충전의 신뢰성을 향상시킬 수 있는 기술을 적용하였다. 새로운 dry process 기술인 직접회로 인쇄 기술은 일반적으로 사용되고 있는 wet process 중 도금, 에칭, 박리 등의 공정을 줄일 수 있어 제조원가, 공정 리드타임 감소, 폐기물 감소로 환경 친화적 공정이라고 할 수 있다. 직접회로 인쇄는 진공도 100 Pa, 인쇄압력 0.45 MPa, 인쇄 속도 30 mm/sec, 인쇄각도 85도, 스크린 마스크와 기판 사이의 Gap 2 mm에서 인쇄될 때 가장 좋은 결과를 보였다. 직접회로 인쇄에 사용된 인쇄기는 일반 PCB공정에서 사용되는 동일한 형태에 진공조건을 유지시킬 수 있도록 개선하여 사용하였다.

Offset lithography is the most widely used printing process in domestic printing industry, but there are no industry-wide specifications for press control to assure consistent quality across printing plants. As printing becomes more of a commodity and less of an art, it is necessary to develop a print quality specification standard suitable for Korea offset printing field. This study aims to contribute to improving the quality of domestic offset color prints by comparative study on color reproduction properties of 2 kinds of domestic process color ink composed of C(cyan), M(magenta), Y(yellow) and K(black) and of 3 kinds of domestic coated paper, using colorimetric color measurement method.

We studied on the effects of the enzyme treatment of pulp fiber on physical properties of coated paper were elucidated using four types of enzymes. The results of this study showed that the blank in which enzyme was not treated showed the highest Stӧckigt and Hurcules sizing degrees. And when the enzyme treated base paper was used for coating, the coated paper has average 5.7 % higher gloss and whiteness than when untreated base paper was used. Brightness showed 0.12 % higher results with the enzyme treated base papers than the blank while it is considered to show similar trends. Whiteness of coated paper was not influenced by the enzyme treatments but by the properties of coating color. Coated paper whose base paper was enzyme treated showed improved roughness while smoothness of those samples except the β-Glucosidase treated one was relatively low due to the high fines content. Also the coated paper whose base paper was not enzyme treated showed high porosity.

Measuring ink penetration is one of the best ways to know paper printability. Ink penetration was effected by physical properties of newspapers. This study was carried out for the purpose of improvement printability with ink penetration of Korean newspapers. The samples were prepared by means of 7 Newspaper manufacture company in Korea, and were tested by IGT printability tester. The results of this experiments showed that the rate of ink penetration, roughness and porosity are proportioned. While, ink penetration, paper formation, ash content and smoothness of paper are in inverse proportioned.