02_3 硬压光原理

Structure of calendered paper 压光纸的结构
• Base paper • 原纸 • Hard nip
calender
• 硬压光 • Soft nip
calender
• 软压光 • Metal belt
calender
• 金属带压光
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Calendering process variables压光工艺变量
Learn the target values of your products
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Paper surface smoothness and roughness 纸面光滑度和粗糙度
Examples 例子
Image: KCL
Base paper 原纸
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Coated paper 涂布纸
Material transferred from the hills to the valleys. Plastic deformation or particles getting loose 物质从山顶转移到山谷。塑化 变形或颗粒变松
Gloss光泽度
• Orientation 定向
Oblong and flat particles are settled along the surface 椭圆和平的颗粒沿着表面分布
coating method涂布方法 Pigment 颜料 Sizer 施胶机 Binder胶黏剂 coat weight 涂布量
surface roughness 辊面粗糙度 fluid temperature 热油温度 surface temperature 辊面温度
web speed 纸幅速度 Steaming 蒸汽 Moisturizing 润湿
软压光：硬辊和聚合物包覆层的软辊压在一起⇒ 停留时间长⇒压力低
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Pressure压力, MPa
hard nip 硬压区
25 20 15 10 5 0 0 5 10 15 20
Nip length压区长度 , mm
soft nip软压区
Nip between two rolls 两辊之间的压区
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Temperature 温度 Moisture 水分 Etc. 其它
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Paper surface smoothness and roughness 纸张表面平滑度和粗糙度
How to reduce macroroughness?如何降低微观粗糙度
• Reducing macro roughness improves surface smoothness • 降低宏观粗糙度可以提高表面平滑度 • Macro roughness is dependent on: 宏观粗糙度取决于：
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+++ --------- (+)
Calendering mechanisms 压光机理
Smoothness平滑度
• Compression of the web纸幅的压缩
Paper hills are compressed more than valleys 更多山顶被压平
• Transferring and polishing 转移和抛光
THERMO ROLL
热辊
OTHERS
其他
SIZING / COATING 施胶/涂布
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Calendering process variables 压光工艺变量
Linear load and specific pressure 线压力和比压
q [kN/m] Linear load线压力 Specific pressure 比压[MPa]
• Reproduction
复现
Surface pattern of the roll is reproduces to the paper 辊子的表面形式在纸面复现
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Paper surface smoothness and roughness 纸张表面平滑度和粗糙度
Microroughness and macroroughness 微观和宏观粗糙度
Collapse of deeper fibers 深层纤维的皱缩 Macro roughness is restored in paper after the nip 大粗糙在压区后保留 High temperature influences gloss more 更高的温度对光泽度影响大 Develops best with mechanical pressing 通过机械压力改善
压区停留时间
• nip length 压区长度 • number of nips 压区数目
-
roll properties 压光辊特性
• Paper properties on the
thermo roll side are better than on colder roll side
与热辊接触的纸张性能优于冷辊
Coated and calendered paper 涂布和压光纸
Calendering parameters 压光参数
NIP MECHANICS
PAPER / BOARD纸/纸板
Moisture 水分 Temperature温度 Wet end 湿部 Furnish 浆料 Formation 匀度
Summary 总结
• Mechanical variables 机械变量
Operator may change these parameters
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Linear load (nip pressure) 线压力（ 线压力（压区压力） 压区压力） Soft roll cover material 软压光辊面材质 Roll dimensions 辊子尺寸 Number of nips 压区数目 Web speed 纸幅速度 Temperature 温度 Moisture 水分 Paper properties 纸幅特性
Calendering process 压光工艺
OptiHard 1-nip calender 单压区硬压光 ValSoft heating system 软压光 NDPM3R
Calendering 压光
Main targets 主要目的
• Improvement of paper surface
1.
Micro- and macrorough paper 微粗糙和大的粗糙纸张
2.
Microroughness is removed but macroroughness remains 微粗糙被除去但大的粗糙依然存在
3.
Micro- and macroroughness removed微粗糙和大的粗糙均被除去
• With coated grades control of
roughness and porosity before coating 在给纸张涂布前控制粗糙度和透气度
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Calendering process 压光工艺
• Calendering results are build
with压光结果取决于： - pressure (~ linear load) 线压力 - Heat 温度 - moisture 水分 - calendering dwell time
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Effects of the calendering process 压光对纸张的影响
Wanted changes 目标变化
• Smoothness光滑性 • Gloss 光泽度 • Air porosity 透气度 • Oil absorption 油墨吸水性 • Two-sidedness 两面性
操作工可以控制 的参数
• Plasticizing variables 塑化变量
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压区机械方面
number of nips 压区数目 linear load 线压力 roll dimensions 辊子尺寸 Modulus模量 soft cover 软辊面 surface roughness表面粗糙镀 max. specific pressure 最大比压(Mpa) nip length 压区长度
s [mm]
Nip width 压区宽度
Fra Baidu bibliotek
Specific pressure (δ max ) = Linear load (q) Nip width (s)
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Specific pressure and nip length 比压和压区长度
Hard nip and soft nip calendering 硬压光和软压光
properties for printing requirements改 善纸张的表面性能和印刷需求 ⇒ Surface smoothness and gloss 表面光滑和光泽度
• Control of thickness profile
控制横幅厚度 ⇒ Paper caliper control 纸幅厚度控制
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Paper surface smoothness and roughness 纸张表面平滑度和粗糙度
How to reduce microroughness? 如何降低微观粗糙度
• Reducing micro roughness improves gloss • 降低微观粗糙度可以提高光泽度 • Micro roughness can be reduced fast with plasticizing factors • 通过塑性因素可以快速降低微观粗糙度
Roughness 粗糙度 Oil absorption 油墨吸收性
+++ +++ -------
+ = increases 增加 - = decreases 降低
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Effects of the calendering process 压光对纸张的影响
Unwanted changes 不想要的指标变化
•
•
Hard nip: Two hard rolls are pressed together ⇒ short nip ⇒ high pressure
硬压光：两个硬辊压在一起⇒ 停留时间短⇒压力高
•
•
Soft nip: Hard roll and polymer covered roll are pressed together ⇒ longer nip ⇒ lower pressure
• Density 紧度 • Thickness 厚度 • Stiffness 挺度 • Compressibility 压缩性 • Opacity 不透明度 • Brightness 白度 • Tear strength 撕裂度 • Tensile strength 抗张强度
+ = increases增加 - = decreases 降低