종이 내수성 자동측정시스템의 신뢰성 분석

다국어 초록 (Multilingual Abstract)

Except tissue papers and sanitary papers, most kinds of papers made through paper-making process are vulnerable to water, so they need to have water repellency. To give water repellency to papers mainly composed with cellulose which has hydrophilic –OH components, it is necessary to do sizing by adding rosin acid sizing agent or neutral agents such as Alkyl Ketene Dimer (AKD) and Alkenyl Succinic Anhydride (ASA). Adding sizing agents in the process of material making is called internal sizing, while applying sizing agent on dry surface of web is called surface sizing.
Papers have various properties according to their final purposes, so it is impossible to measure sizing degree of all kinds of papers with one measurement. About 50 methods are currently used to measure sizing degree, and they can be divided into three groups: (1) measuring absorption time, (2) measuring amount of liquid absorption, and (3) measuring surface. Most widely used methods are Cobb test, Stӧckigt test, and contact angle test. The three methods, however, have both advantages and disadvantages as a way of measuring.
Stӧckigt test can be used anywhere with liquid for testing, but the test is not so reliable because in the way the measurers can be easily subjective, bringing out various results depending on experimenters. With Cobb testing, a measurer cannot check differences of sizing over specific Manual measuring is less reliable and hard to quantify, while auto measuring devices are not affordable due to high prices.
Given the situation, the author designed automatic Stӧckigt sizing test using an automatic recognition principle of color expression, with which a measurer can check contact angle at the same time. To discharge a certain amount of liquid, it is equipped with automatic liquid dispenser, and is using a hue value, which is closer to the color perceived by human eyes rather than that of RGB value. During test, the program measures the time taken to reach a specific color value and contact angle of liquid.
Among existing ways to measure sizing degree, Stӧckigt testing is found to be less reliable in particular. The testing’s unreliability proceeds from the fact that its time to recognize the end pint varies depending on a measurer, a measuring angle, and the amount of dropped FeCl3 (II). Cobb testing was more reliable than Stӧckigt testing, but its measuring process is inconvenient and it does not show significance when measuring specimen handle more than a certain sizing.
The author analyzed reliability and strengths and weaknesses of existing sizing testing methods to quantify water repellency of papers and developed an automatic measuring system to measure penetration property and surface property at the same time.
To calculate the repeatability and reproducibility of the new system for measuring water repellency behavior of papers, four testers measured the same specimens using existing testing methods and the automatic system. The measurement was carried out in two places, inter and intra, and the reliability analysis was based on TAPPI T1200.
With Cobb sizing, specimens without AKD and those with small amount of AKD of 0.2% and 0.4% concentration were found to absorb a lot of distilled water for a specific time, but among specimens with AKD over 0.4% concentration, it was not possible to find differences according to the amount of AKD. Repeatability and reproducibility were 21% and 23.2% each. With contact angle sizing test, it was hard to measure specimens added no AKD and those added 0.2% AKD because dropped distilled water was absorbed in papers immediately, and it was found that the more amount of AKD was added, the smaller differences of values were there. Repeatability and reproducibility were 22.21% and 31.59% each. With Stӧkigt sizing test, it was able to find clear differences among specimens with different concentration of AKD, but values were far different according to measurers and testing places. Furthermore, repeatability was 74.57%, which implies it is least reliable, and reproducibility was 27.38%.
Automatic sizing system showed more stable performance than the existing sizing tests, and with this method, value differences according to testing places were not significant compared to the existing sizing tests. Different from Stӧkigt sizing test which brought different values according to basis weights, automatic sizing system did not show significant difference according to basis weights and had highly reliable repeatability and reproducibility, average 0.7% and 0.3% each. Through these results, the author could find that using automatic sizing system can exclude measurers’ subjectivity, improve objectivity with automatic measurement and automatic finishing of test, and finally achieve highly reliable repeatability and reproducibility.

목차 (Table of Contents)

• 목 차
• List of Tables ⅲ
• List of Figures ⅴ
• Abstract ⅷ
• Ⅰ. 서론 1
• Ⅱ. 연구사 4
• Ⅲ. 재료 및 방법 8
• 2.1. 공시재료 8
• 2.2. 실험 방법 8
• 2.2.1 지료 조성 8
• 2.2.2 전분 호화 8
• 2.2.3 수초지 제작 8
• 2.3. 기존의 사이즈도 측정 9
• 2.3.1 Cobb 사이즈도 측정 9
• 2.3.2 Stöckigt 사이즈도 측정 10
• 2.3.3 접촉각 측정 10
• 2.4. 종이 내수성 자동측정시스템 12
• 2.4.1 종이 내수성 자동측정시스템의 하드웨어 구성 12
• 2.4.2 종이 내수성 자동측정시스템의 소프트웨어 구성 14
• 2.5. 신뢰성분석 15
• 2.5.1 시험 변수 조정 15
• 2.5.2 반복성 분석 16
• 2.5.3 재현성 분석 17
• Ⅳ. 결과 및 고찰 18
• 3.1 기존 시험법에 따른 사이즈도 측정 18
• 3.1.1 Cobb 사이즈도 측정 19
• 3.1.2 Stöckigt 사이즈도 측정 22
• 3.1.3 접촉각 26
• 3.2 기존 시험법의 신뢰성 분석 30
• 3.2.1 기존 시험법의 반복성 및 재현성 분석 30
• 3.3 종이내수성 자동측정시스템에 따른 사이즈도 측정 35
• 3.4 종이내수성 자동측정시스템의 신뢰성 분석 43
• 3.4.1 종이내수성 자동측정시스템의 반복성 및 재현성 분석 43
• Ⅴ. 결론 53
• Ⅵ. 인용문헌 55