Pulp&Paper Technology •

纸业技术

如：锐线和斑纹，这些缺陷在狭缝涂布方式中可以观测到，例如，

刮刀涂布机和狭缝冲模涂布机。

在造纸工业领域，帘式涂布可能会很陌生和稀奇，但是自20世

纪70年代以来，在照相行业单层和多层结构产品生产方面，帘式涂

布已经被证明是最有价值方法。

帘式涂布也正被造纸工业的一些特殊应用领域所采用。原则

上，该技术也适合于印刷纸或纸板包装材料的涂布，现在正在对这

方面的运用进行测试。

就像所有其他涂布方式一样，帘式涂布不是万能的，也具有自

身的应用范围。表1列出了技术方面的应用限制包括：纸幅速度、

湿/干薄膜厚度、粘度、表面张力、比流动速率和涂布层数。表中所

列数据仅仅是一些概括性数据，更详细的数据必须考虑将来的变量

多少。

参数

最小值

最大值

纸幅运行速度(m/s)

< 1

> 35

湿膜厚度(整体)(

µm)

> 10

–

干膜厚度(单个)(

µm)

< 1

–

粘度(Pas)

0.010

层数(-)

> 10

–

表面张力(mN/m)

–

< 40

比流动速率(cm3/cm*s)

> 1

–

在纸幅运行速度一定的情况下，要想获得稳定的加工过程和生

产出非常薄的薄膜厚度，比流动速率是一个非常重要的参数。例

如，在高纸幅速度条件下，能够获得由低到高的不同涂布量；但是

在低纸幅速度条件下，常常会由于落帘稳定性不够而导致薄涂层形

成失败。这个限制对落帘总体流动速率也起作用。在多层结构中，

可以获得非常薄的单个涂层。

多层涂布

对于多层帘式涂布，通常采用滑动式结构，示意图见图1。在滑

动式冲模上，用于形成多层结构的不同涂料出口从上到下按一定顺

序排列，每种涂料都独自具有计量狭槽。

–

Film thickness accuracy in CD is determined mainly by

the design, dimensions and manufacturing tolerances of dies

–

No excess coating liquid

–

Short product changeover time is possible

–

Contactless application process

–

Multiple layer coating possible within just one pass

–

Possibilities for two-component applications, for

example, coating colour and cross-linking agent

In the premetered category, curtain coating is a

particularly attractive coating method. Because it applies
a contour coating, the process also creates an even coating
on uneven substrates. In addition, there is a virtual absence
of  coating  defects,  such  as  the  sharp  lines  and  streaks
which  can  be  observed  with  coating  methods  that  use
narrow  gaps.  The  latter  includes  blade  coaters  and  slot
die coaters.

Curtain coating may be rather unknown and new in the

paper industry, but it has been a proven and valuable method for
coating single and multiple layer products in the photographic
industry since the 1970s.

Curtain coating is also being used in several speciality

applications in the paper industry. This technology in
principle is also suitable for the coating of printing papers
or cardboard packaging materials, applications which are
currently being tested.

Just like all other coating methods, curtain coating has

its own window of application. Table 1 shows the application
limits of the technology in terms of: web speed; wet and
dry film thickness; viscosity, surface tension, specific flow
rate and the number of layers which can be applied.
The values in the table are just ballpark figures, more
detailed figures are necessary to consider a multitude of
further variables.

Parameter

Minimum Maximum

Web speed [m/s]

< 1

> 35

Wet film thickness (total) [µm]

> 10

–

Dry film thickness (single layer)

[µm]

< 1

–

Viscosity [Pas]

0.010

No. of layers [-]

> 10

–

Surface tension [mN/m]

–

< 40

Specific flow rate [cm3/cm*s]

> 1

–

The specific flow rate is an important parameter for

achieving a stable process and the production of a minimum
film thickness at a given web speed. For example, it is possible
to achieve low to high coat weights at high speeds. But, at
low speeds, thin layers often fail due to insufficient curtain
stability. This limit is valid for the total flow rate necessary in

图1：滑动结构的多层帘式涂布冲模

Figure l: Dies in slide configuration for multilayer curtain coating

表1：帘式涂布应用方面的限制

Table 1: Application limits for curtain coating