Essential for sealing performance! Different Materials and Characteristics of Rubber Gaskets

Gaskets are widely used to seal the stainless steel container. To use the container safely and correctly, compatibility with the gasket is very important, too.

In this article, we will introduce the materials used in the gaskets of stainless steel container.

For those who want to know the chemical compatibility of different gaskets This article illustrated the compatibility of chemicals and characteristics of each gasket material. If you want to learn more about what kind of gasket you should use, please read this article.

Main materials of gasket

Silicone rubber (Q)

Silicon rubber gasket has characteristics such as weather resistance, chemical resistance, non-adhesiveness, and ozone resistance. Also, it has excellent flame resistance, water repellency, electrical insulation, etc.

Not only for industrial purposes, the silicon rubber is also used for household products.

This is a standard gasket material for Nitto Kinzoku's stainless steel sealed container.

Operating temperature range: -70 ° C to + 200 ° C

Weather Resistance
- It is highly stable against oxygen, ozone and UV. And its properties hardly change even when exposed to UV or wind and rain for long period.
Water Repellency
- It is less likely to get wet than other rubbers, and is also used as a waterproof seal material.
Flame Retardance
- It does not burn easily when flames are brought close to it, and it generates almost no smoke or toxic gas when ignited.
Non-Adhesive and Non-Corrosive
- It has excellent mold release properties and is also used as a mold release agent. In addition, it is chemically inert and does not corrode other substances.
Transparency and Colorability
- Excellent transparency of silicone. It also can be colored.
  Even if it is has been colored, the basic performance as a sealant does not change.

Weak to strong acids.
Due to its non-adhesiveness, it is highly unlikely to be adhered by normal organic adhesives.
It can be vulnerable in some external mechanical factors such as tensile strength, tear strength, and wear resistance.
Because of its high gas permeability, it can easily allow gas to pass through. (However, water and water vapor have different molecular densities, so there is no ill effect in waterproofness.)

THE GASKET WILL BECOME SLOPPY!? Depending on the compatibility of the gaskets/o-rings and the liquid, the gasket/o-ring may absorb the liquid and swell and become sloppier than before. This is called "rubber swelling". This is because the liquid enters and fill between the rubber molecules of the rubber. In addition, there may be cracks and other deterioration of the gasket/o-ring depending on the operating environment and compatibility with the liquid, so it is necessary to select the gasket/o-ring that is most suitable for the operating environment and the liquid.

When should I change the gasket? The standard silicon gasket for Nitto's stainless sealed containers is a consumable item and requires timely replacement. Then, when should I change it?
Please refer the essay by clicking the button below, where you can find more details about it.

Fluorocarbon rubber (FKM)

Fluororubber on the market today generally refers to vinylidene fluoride fluororubber (FKM).

Fluororubber has the highest heat resistance among rubber materials, excellent oil resistance, fuel resistance and chemical resistance. Therefore, it is used in a wide range of fields, including automotive parts and chemical plants.

Heat Resistance
- Operating temperature range: -10 ° C to + 230 ° C
  Compared with silicone rubber, it can maintain sealing performance for a long time, so it is used for sealing high-temperature parts.
Oil Resistance
- With the exception of some phosphate-esters based hydraulic oils, FKM can withstand most mineral oils even in high temperatures.

Polychloroprene rubber (CR)

It is a kind of synthetic rubber that has been used for a long time. It has excellent mechanical strength and weather resistance, and is widely used for other properties because it is average and well-balanced. It is flame-resistant, has strong adhesive strength (When using rubber glue.), and has low gas permeability. This material is also used in wet suits.

Operating temperature range: -35 ° C to + 110 ° C

Nitrile butadiene rubber (NBR)

Synthetic rubber excellent in oil resistance, abrasion resistance and aging resistance. Especially excellent in oil resistance.
Also, it is excellent in compression set, tensile strength and abrasion resistance. So it is can be used in various fields such as sealing materials, glove materials and automotive parts.

Operating temperature range: -10 ° C to + 120 ° C

Why are tires black? We often see black color rubber products such as tires, wet suits, and of course, gaskets. The image of black tires is especially strong. The main reason for this is that black carbon particles called "carbon black" are added to the rubber to improve its strength and wear resistance. However, many rubber products now use white carbon instead of carbon black, which is white silica, as a reinforcing agent. Thus, the number of rubber products other than black is increasing.

Ethylene propylen diene monomer rubber (EPDM)

EPDM is a synthetic rubber with excellent chemical resistance, cold resistance, ozone resistance and aging resistance. In addition, it has the smallest specific gravity in all of commercially available rubber. Because it is resistant to ozone and does not age easily, it is also used for automobile parts and track in athletic fields.

Operating temperature range: -40 ° C to + 140 ° C

Polytetrafluoroethylene plastics (PTFE)

Also called “fluororesin”, it has excellent chemical resistance, ozone resistance, weather resistance, and the least friction (PLASTIC). It is not rubber like other materials. It has high-insulating properties and is also used as an excellent material for electrical insulation.
As it is non-adhesive and has low friction (slippery), it is also used as a sliding material. It is very famous for coating the frying pans. Because of its excellent characteristics, it is used in various fields.

Chemical Resistance
- Stable against any acid, alkali, or organic chemicals, it does not absorb moisture and water, and does not swell. Hardly affected by the environment.
Heat Resistance
- Operating temperature range: -100 ° C to + 260 ° C
  It can be used for long time over a wide temperature range.

High price
Mass production is not possible because each product needs to be machined out.
The sealability as a gasket is inferior due to its resin characteristics.
Inferior in abrasion resistance.
It is nonadhesive and cannot be bonded with any adhesive.

Perfluoroelastomer (FFKM) Although PTFE has excellent chemical resistance, but it has a drawback, which is its poor sealing performance. So, for pursuing both chemical resistance and sealability, we can use Perfluoroelastomer. Perfluoroelastomer is also a kind of fluororubber. This product has the best chemical resistance and heat resistance among rubber gaskets. It is very expensive because of its high performance and limited demand.

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