종이기록물 복원을 위한 Leaf-casting 펄프의 원료별 인공열화 특성에 관한 연구 = A Study on the Accelerated aging Characteristics of Leaf-casting pulp materials for Restoration of Paper Records

국문 초록 (Abstract)

종이 기록물의 열화에 의해 훼손과 손실이 전근대 공공 기록물 및 문화유산적 가치가 높은 소중한 양지 기록물에서 전체적으로 진행되고 있다.
기록물 복원은 주로 수작업 복원 방식에 국한되어 진행되어 왔으며 문화재 수리 측면으로 접근되어왔다.

본 연구는 종이 기록물의 복원방법을 제지원리와 과학적 방법에 기반한 기계적 복원방식인 리프캐스팅 기술을 제시하고 원료 펄프별 특성을 인공열화 후 물리성 측정과 기기분석을 통해 장단점을 규명하였다.

결론으로는 종이 기록물의 보존복원시 상태평가와 복원 대상물의 규모에 따라 수작업 복원과 기계적 복원인 리프캐스팅을 병행하는 방안을 최적의 모델로 제시한다.

양지 기록물의 복원시 원료 배합은 침엽수 펄프 30~40%, 활엽수 펄프 30~40%, 면 펄프 20~30% 수준 내에서 예비시험을 거쳐 적정비율을 선정해야 한다.

리프캐스팅 복원은 열화된 종이 기록물을 원본지의 제조공정과 동일하게 복원하는 방법으로 수작업 복원의 한계를 극복할 수 있는 대안으로 기록물을 생기있게 재 탄생시키는 매직같은 기술이다.
본 논문이 리프캐스팅 복원에 관한 연구와 실용화 확대를 위해 가이드 역할을 할수 있을 것으로 사료된다.

다국어 초록 (Multilingual Abstract)

This study analyzed the physical properties of each pulp through
durability tests such as tensile strength, folding endurance, formation,
and brightness, which are important physical items during leaf casting
restoration, using Soft&Hard wood pulp and cotton non-wood pulp.
which are used in the restoration method using a leaf casting device,
which is a mechanical restoration treatment method.
1. Formation is a basic item for determining the characteristics of paper,
and it is important in that it allows you to visually judge the
characteristics of fibers. It is a criterion for judging the degree to which
fibers are evenly distributed. If the paper basis weight is uneven in
each part, the standard deviation of the basis weight will be large and- 99
the formation will be poor. In general, if the length of the fibers is long,
the fibers will form a flux, which will worsen the formation. If a lot of
short-fiber hardwood pulp is used, the formation will be good, but the
strength characteristics may be weak. Therefore, in order to satisfy both
the formation and strength characteristics, softwood pulp and hardwood
pulp should be mixed and used in an appropriate ratio. The formation
index(LT) indicates that the formation is better the lower the value.
Before deterioration, the formation of hardwood pulp was excellent at 58
for softwood pulp, 65 for cotton pulp, and 46 for hardwood pulp, and
there was no change in the bonding after 3 weeks of deterioration. The
average bonding index of copy papers generally used in the market is
about 52. In the case of cotton pulp, it is necessary to induce single
fibers through sufficient refining to improve formation characteristics,
and in the case of coniferous wood, both strength characteristics and
formation characteristics can be satisfied through refining.
2. The optical characteristics are yellow series (b*) values. Positive
values ​
are yellow. Negative values ​
are blue. As the paper deteriorates,
yellowing occurs. It is an important quality item for optically measuring
and predicting preservation characteristics. In the case of coniferous
pulp, the yellowing increased significantly after 2 weeks of artificial
deterioration. After 3 weeks of artificial deterioration, it increased by
20.7% compared to the initial value. In the case of hardwood pulp, the
yellowing increased significantly after 1 week, and after 21 days, it
increased by a large amount of 55%. In the case of cotton pulp, it was
stable without yellowing and the increase was slightly increased by
4.5%.- 100
3. Tensile strength is the strength that resists when a certain width of
test paper is pulled, and it is determined by the degree of fiber
resolution, fiber-to-fiber bonding area, and fiber length. It is a quality
item representing the strength properties of paper, and it was found that
all samples decreased as artificial deterioration progressed due to
structural changes such as hydrolysis of cellulose. Cotton fibers were
shown to be superior compared to conifers and broadleaf trees because
they have a long fiber length and a large specific surface area for
hydrogen bonding between fibers. The strength reduction rate after 1
week of artificial aging was-4.6%, after 2 weeks-16.2%, and after 3
weeks-21.2%. In the case of coniferous pulp, the decreases were-10.2%,-22.3%, and-27.9%, respectively, and in the case of broadleaf
pulp, the decreases were-14.9%,-26.6%, and-44.8%, respectively,
showing that the strength significantly decreased after 1 week of
artificial aging.
4. Folding endurance is the most complex mechanism among the items
measuring the durability of paper. The fold strength test is very
complex because it specifies a combination of tensile strength,
elongation, compression resistance, and various shear stresses and
deformations. Since the tensile strength changes greatly as deterioration
progresses, it is also used as an indicator of deterioration because it
measures the strength to resist folding that occurs over a long period of
time. The decrease in tensile strength after deterioration was-2.8%
after 1 week of deterioration,-8.9% after 2 weeks, and-17.0% after 3
weeks for cotton pulp. In the case of softwood pulp, it decreased by-19.3%,-32.3%, and-39.6%, respectively. In the case of hardwood pulp,- 101 it was measured to decrease by-40.3%,-52.8%, and-65.3%,
respectively. Since cotton pulp has long fibers, it was confirmed that it
has strong tensile strength even when artificially deteriorated, and the
decrease in strength of hardwood pulp was greater after 2 weeks of
artificial deterioration than that of softwood pulp. The length of
hardwood fibers is 1~2mm, and since the fibers are short and weak, the
decrease in strength due to deterioration was greater than that of other pulps.
5. Soft-wood fibers are 3~5mm long, the width of cells is generally
30~50μm, which is 1/100 of the fiber length, and the length/width ratio
is about 50~100. The hollow space inside the cell is called the lumen,
and it is characterized by having a duct cell with a tapered tip. When
examined under a microscope, it looks like a flat, wide ribbon. Softwood
fibers have excellent strength characteristics because they have a long
fiber length and a large specific surface area that can be bonded
between fibers. Because hardwoods have a more complex anatomy than
softwoods, there are more different cell types in the pulp. Commonly
observed cell types include duct elements, fibrous organs, arched fibers,
longitudinal parenchymal cells, and radiating cells. The fiber length of
hardwood wood fibers is about 1~2mm, which is much shorter than that
of coniferous woods, and the cell lumen is also narrower. Therefore, the rigidity
of fibers is higher than that of conifers, which is
disadvantageous for the formation of bonds between fibers, and the
strength characteristics are also weaker than those of conifers. Cotton
pulp has a fiber length of 1~8mm and a fiber width of 17~25μm.
Because of its general nature, cotton is easily distinguishable from other- 102
fibers. It is a long single-celled fiber in the shape of a ribbon, with a
large continuous lumen present throughout its length and slightly
thickened at the edges. The noodles are twisted at irregular intervals.
6. Thermal analysis (TGA) characteristics were measured after 3 weeks
of artificial deterioration. The advantage of the thermogravimetric
analysis used in this experiment is that it can reduce subjective errors
by using a small sample in a short period of time through an isothermal
method, and can compare and analyze the change in decomposition
temperature by pulp type. It can analyze the thermal characteristics of
each sample by obtaining a kinetic value from the relationship between
weight change and temperature. All samples showed a gradual weight
loss change due to moisture evaporation from room temperature to 11
5℃, but in the case of coniferous pulp, a rapid thermal decomposition
phenomenon was observed around 271℃, and when heated to a higher
temperature, a weight loss of 77.4% occurred at around 465℃. After
that, a gradual weight loss of 14.8% occurred as the temperature was
increased to 600℃. The remaining amount was 0.77%. The hardwood
pulp showed a weight loss of 6.0% when heated to 205℃, a rapid
decrease occurred until about 420℃, and an 85.5% weight loss occurred
when heated to 600℃. The thermal decomposition characteristics of
cotton pulp showed a gradual weight loss of 6.5% until 277℃, a rapid
weight loss occurred until about 430℃, and an 85% weight loss
occurred when heated to 600℃. Since the thermal decomposition
temperature of cotton pulp was higher than that of needle and hardwood
pulp, it was proven to be strong in terms of thermal stability.- 103
7. The changes in the cellulose structure before and after artificial
thermal decomposition were identified through infrared spectroscopy
(FT-IR). The softwood pulp was characterized by 19 absorption bands
before thermal decomposition and 17 after thermal decomposition. In the
case of hardwood pulp, the elongation and bending peaks were measured
as 17 absorption bands before artificial deterioration and 16 after
deterioration. In the case of cotton fiber, 18 absorption bands appeared
before artificial deterioration and 18 remained unchanged after
deterioration, which means that the cellulose structure was maintained
without any change. From these results, it was proven that cotton fiber
had excellent deterioration stability.
8. Atomic force microscopy (AFM) detects the force acting between the
atoms of the experimental sample and the probe to obtain an image. In
the case of softwood pulp, the fiber arrangement before deterioration
was evenly distributed and showed a three-dimensional structure due to
the irregular arrangement of the amorphous region and the crystalline
region; it is judged that this is because the amorphous region contained
moisture. After 3 weeks of deterioration, the cellulose layer began to be
subdivided, and the cellulose, which showed an irregular multilayer
structure, gradually clumped together as deterioration progressed.
Hardwood pulp shows a multilayer structure with large fibers arranged
irregularly like the pure cellulose surface before deterioration, but after 3
weeks of deterioration, the cellulose that showed an irregular multilayer
structure gradually clumped together as deterioration progressed,
showing a similar trend to softwood pulp. In the case of cotton pulp,
the multilayer structure before deterioration was separated into several- 104
forms and formed distinct layers, and the phenomenon of the multilayer
structure clumping together after deterioration was clearly shown
compared to other wood pulps. Therefore, the phenomenon of the
multilayer block that was arranged irregularly before deterioration
clumping together after deterioration was the same, and cotton pulp
showed it more clearly.
9. Scanning electron microscope(SEM) observation was performed by
taking 1,000x magnification images of samples before and after
deterioration and analyzing them. In the case of softwood pulp, it
separated from the leaf-cast original paper after 18 days of artificial
deterioration. Before deterioration, the fibers were relatively long and
smooth, but the photos taken at the time of detachment showed that the
fibers had shrunk overall and were split at the edges. It is believed that
the bond between the fibers has also become loose. The SEM photos of
hardwood pulp showed that the fiber width was small and the fiber
length was short before deterioration, and that the bond between the
fibers was good. After 14 days of artificial deterioration, it was
separated from the original leaf-casting paper. The photos after
deterioration show that the fibers were severely damaged and were torn
and crushed. Severe damage to microfibrils directly affects the
deterioration of physical properties related to strength and durability.
There is no significant difference when observing the photos of cotton
pulp before and after artificial deterioration. Although some shrinkage
and splitting of the fibers were observed, the fibers themselves were
maintained intact. Therefore, it was confirmed that cotton pulp showed
excellent preservability among leaf-casting pulp raw materials.- 105
In conclusion, the optimal model for the preservation and restoration
of paper records is proposed as a combination of manual restoration and
mechanical restoration, such as leaf casting, depending on the condition
assessment during preservation and restoration and the quantity of items
to be restored. Key basic factors in leaf casting restoration include
properly adjusting the pulp blend ratio, degree of freeness, drainage,
formation, and drying(final moisture content). For the pulp blend ratio, it
is necessary to conduct preliminary tests to select an appropriate ratio,
typically using 30-40% UKP pulp, 30-40% LBKP pulp, and 20-30%
cotton pulp for original
paper records like newspaper and
newspaper-grade paper. In the disintegration process, the three pulps are
mixed, water is added, and the mixture is pre-treated with a
disintegrator, then further processed with a beater under controlled
conditions for about one hour to produce restoration pulp with a
consistency of 1% and a degree of disintegration of 400–450mlCSF. If
the records to be restored have color, natural dyes can be added to the
pulp suspension to match aesthetic qualities. During the paper forming
process using a leaf caster, the pulp concentration is diluted to 0.5% to
maintain good bonding.
Leaf casting restoration is a method of restoring degraded paper records
in the same way as the original paper manufacturing process, serving
as an alternative to overcome the limitations of manual restoration. It is
a technique that can breathe new life into paper records. This paper
aims to provide guidelines for research and the practical expansion of
leaf casting restoration.

목차 (Table of Contents)

• List of Tables ⅳ
• List of Figures ⅴ
• Ⅰ. 서 론 1
• Ⅱ. 연구의 이론적 고찰 7
• 1. 종이 기록물의 열화 7
• 1.1 종이 제조과정의 산성 7
• 1.2 잉크, 접착제의 산성 9
• 1.3 온도와 상대습도 10
• 1.4 공기오염 12
• 1.5 빛 12
• 1.6 기록물의 생물학적 열화 13
• 2. 종이 기록물의 복원 15
• 2.1 복원 기록물 선별을 위한 상태평가 15
• 2.2 종이 기록물의 복원 과정 17
• 2.3 탈산 처리 19
• 3. 리프캐스팅(Leaf-casting) 26
• 3.1 개요 및 원리 26
• 3.2 리프캐스팅 방법 27
• 3.3 리프캐스팅 국가별 사례 32
• 4. 펄프 및 종이 종류별 특성 38
• 4.1 목재 펄프 38
• 4.2 비 목재 펄프 39
• 4.3 펄프의 고해 40
• 4.4 종이 지종별 산성지 및 중성지 특성 41
• Ⅲ. 실험재료 및 방법 42
• 1. 실험재료 42
• 1.1 공시재료 42
• 1.2 목재펄프 및 비목재 펄프의 섬유형태 구조분석 43
• 1.2.1 C-Stain 시약 제조 및 섬유분석 43
• 2 실험 방법 44
• 2.1 펄프 고해 44
• 2.2 리프캐스팅 44
• 2.2.1 리프캐스팅 장비 45
• 2.3 리프캐스팅 제작 46
• 2.3.1 리프캐스팅에 의한 공시재료 제작 46
• 2.3.2 리프캐스팅 수초지 제작 48
• 2.4 인공열화 방법 49
• 2.5 물리적 특성 측정 방법 49
• Ⅳ. 결과 및 고찰 54
• 1. 인공열화에 의한 기본적 물성 변화 54
• 1.1 지합 54
• 1.2 인공열화 시간에 따른 광학적 특성 결과 55
• 2 인공열화 후 강도적 특성 변화 58
• 2.1 인장강도(Tensile Strength) 58
• 2.2 내절강도(Folding endurance) 59
• 3. 펄프 종류별 섬유특성 분석 60
• 3.1 침엽수 펄프, UKP(Unbleached Kraft Pulp) 60
• 3.2 활엽수 펄프, LBKP(Leaf Bleached Kraft Pulp) 62
• 3.3 면 펄프, Cotton Pulp 63
• 4 리프캐스팅 시료의 인공열화 특성 결과 64
• 4.1 열분석(TGA) 특성 비교 64
• 4.1.1 침엽수 펄프의 열분해 특성 64
• 4.1.2 활엽수 펄프의 열분해 특성 66
• 4.1.3 면 펄프의 열분해 특성 67
• 4.2 적외선 분광분석(FT-IR) 68
• 4.2.1 침엽수 펄프의 적외선 분광분석 특성 69
• 4.2.2 활엽수 펄프의 적외선 분광분석 특성 71
• 4.2.3 면 펄프의 적외선 분광분석 특성 73
• 4.3 원자간력 현미경(AFM)의 열화특성 시험 결과 75
• 4.3.1 침엽수 펄프의 원자간력 현미경 특성 76
• 4.3.2 활엽수 펄프의 원자간력 현미경 특성 78
• 4.3.3 면 펄프의 원자간력 현미경 특성 80
• 4.4 주사전자 현미경 관찰(SEM) 82
• 4.4.1 침엽수 펄프의 주사전자 현미경 특성 82
• 4.4.2 활엽수 펄프의 주사전자 현미경 특성 84
• 4.4.3 면 펄프의 주사전자 현미경 특성 86
• Ⅴ. 결론88
• 참고문헌94
• Abstract 99