Cleanroom Sticky Mats: 3 Important Adhesive Characteristics

Mats are an important requirement of cleanrooms and other critical environments that demand a high degree of contamination control. These mats have strong adhesive properties which collect dust particles from shoe soles and wheels of the carts passing over the mat. Multi-layered adhesive mats are used to peel off the contaminated layer and reveal a new clean layer to significantly reduce traffic-borne particles. A special kind of Acrylic adhesive is used on these mats which does not sustain any microbial growth.

Use of Mats in Various Applications

Not only in clean rooms and laboratories, matting applications are used in a number of industries to ensure a clean and uncontaminated environment. Some of these industries are:

• Pharmaceutical industry
• Medical/chemical industry
• Operation rooms
• Computer rooms
• Electronic precision industry

Advantages of Sticky Mats

Sticky or adhesive mats are commonly used in various industries for the following advantages:

• Dust particles collected by the mat do not spread.
• A special kind of adhesive is used which does not leave any stain on the floor.
• After a layer is out of use, a new layer can be brought out by peeling the previous one.

Adhesive Characteristics of Cleanroom Mats

The most common characteristics of cleanroom mats are tack level, adhesive thickness and adhesive softness. These characteristics determine the efficiency of the adhesive in removing and holding contaminants from the surfaces before their entry into the cleanroom.

• Tack level: The tack level or level of stickiness of a mat is measured through PSTC-1 test and represented in grams. The right amount of tack level is crucial for maintaining the appropriate balance, which, if exceeded, can be hazardous. Since the purpose of the mat is to remove dirt from the dry adhesive-less surface, it just needs a higher coefficient than the surface attraction. A very low tack level (2-3 ozs) is sufficient for this purpose.
• Adhesive thickness: If the adhesive layer of the mat is extra thin, the dust particles will remain on the surface and shorten the reusability and performance of the mat. The thickness of the adhesive layer is, therefore, vital for the prolonged performance of the mat. When particles from the surface of the shoe sole or wheel come in contact with the mat, they get into the thick layer of the adhesive. It keeps the surface clean of contaminants and the mat continues to be suitable for further use. A washable mat comes with no adhesive coating and needs to be washed every time for removing the particles. Consequently, a shoe comes in contact with the particles shed by the previous shoe and is not perfectly clean. Therefore, adhesive mats are often preferred over the washable ones for entering cleanrooms.
• Adhesive softness: Adhesive softness is highly important for the efficient performance of each layer of the mat. When particles come into contact with the surface of the mat, they need some place to go. The softness of the adhesive layer makes sure that these particles are embedded into the layer instead of remaining on the surface, provided the layer has sufficient thickness to grab the particles.

If the adhesive is hard, this function will not happen and instead the dirt will stay on the surface which will reduce the performance of the mat. However, the adhesive should not have a high tack level, otherwise too soft an adhesive will stick to the surface of the shoe or wheel and contaminate the controlled environment of the cleanroom.

Therefore, the right amount of tack level, adhesive thickness and adhesive softness play a crucial role in the performance of the cleanroom mat application.