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The Story of STACLEAN 




STACLEAN is a special paper for cleanrooms that suppresses dust generation. It was named "STACLEAN" by combining the brand name "STAR" of our company (Sakurai Co., Ltd.) and "CLEAN" of cleanroom paper. Since its release in 1982, it has been supported by many users in the cleanroom industry as a paper-based lint-free paper that has excellent low dust generation, good copy aptitude, and is easy to process. We adopted blue as its basic color to distinguish it from ordinary paper, and created the image of cleanroom paper = blue.

In order for you to understand the features of STACLEAN, let us see its differences from plain and synthetic papers.

Plain Ordinary Paper


plain paper

Why shouldn't plain paper be brought into the cleanroom? First, we will see the composition of this paper.

This  paper is  used for general copier paper and notebooks. It's components are roughly divided into fibers (wood pulp), some chemicals, and pigments.


Short fibers are sometimes used because no special properties are required for the fibers used. If short fibers are used, the fibers will fall off and cause dust generation. In addition, the fibers of recycled paper are damaged during the recycling process, which also causes dust generation.


Also, the word “pigment” may be unfamiliar to you, but it is a white powder that is mixed in to make the paper look white and opaque. It is like making up paper with white powder. Calcium carbonate, titanium, etc. are used for “pigments,” and these “pigments” are said to be the number one cause of dust generation from plain paper.

​This paper contains many factors that generate dust from a few microns to several microns invisible to the human eye. The generated dust can contaminate the cleanliness of cleanrooms used in the semiconductor manufacturing process, and it can lead to a decrease in yield due to an increase in the number of defective products.

​Synthetic (Polypropylene) Paper


synthetic paper

Next, let us talk about synthetic paper.

"Synthetic paper" seems to be a general term for plastic films, but most of them are made of PP(Polypropylene) material.

Before STACLEAN was put on the market, printed synthetic paper was used in cleanrooms because it was considered less dusty than plain paper due to its smooth appearance. There are some synthetic papers that are suitable for cleanroom use, but most of them are of a composition that do not meet the standards of cleanroom paper.

The reason is that pigments are used to color this paper, just like plain paper. As shown in the figure below, if you magnify it using an electron microscope, you can see the pigment grains.


Due to its structure (multiple layers), synthetic paper is easily charged with static electricity, making it difficult to print on. Static electricity can be a big problem in some manufacturing processes.

Synthetic paper micrograph

Electron micrograph of synthetic paper

Synthetic paper micrograph

Electron micrograph of synthetic paper (enlarged)

You can see the particles of the pigment

​Dust-free Paper (STACLEAN)



In the case of cleanroom paper "STACLEAN",

What do you think?

STACLEAN has three features.

1. Unlike plain paper and synthetic paper, STACLEAN does not use pigments for coloring. Liquid dye is used to color it blue or violet. Earlier, it was in The Story of Plain Paper that pigment is the most dust-generating factor but this paper do not use pigment as its feature.

​2. STACLEAN uses long fibers different from fibers used in plain paper. This selected longer fiber is used to make fiber entanglement stronger.

3. STACLEAN is an impregnated paper that is  impregnated with acrylic resin. This acrylic resin prevents fibers from falling off.

STACLEAN has low dust generation, but it is suitable for copying and printing, and it is also excellent for processing such as cutting. In addition, the RC series can be collected and recycled, and can be incinerated in the same way as plain paper after usage.

Clean paper micrograph

Electron micrograph of STACLEAN (200x magnification)

Clean paper micrograph

Electron micrograph of STACLEAN (1000x magnification)

Only long fibers can be seen

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