Gaskets are primarily used to seal mechanical joints, with a joint being a place where two things or parts are joined or united. Typically gaskets are used between matched machine parts, flanges, and various joints to prevent the escape of fluids, including liquids and gases, so that the gaskets form a sealing relationship between two parts to prevent the fluids from passing through the junction of the two parts. Generally, gaskets are made from a variety of materials, including rubber and a variety of fibrous cellulose materials, that contain paper, wood pulp, cork, and all types of fillers. Fibrous materials, especially cellulose materials, are used in the construction of gaskets because gaskets made of cellulose will absorb fluids that try to pass through the junction of the matched machine parts or pipes. Often cellulose materials are used to form a gasket because they form a physical barrier and absorb moisture which causes the cellulose material to swell and form a tight seal that does not permit the escape of fluid between joints. In essence cellulose gasket materials seal a joint in two ways by forming a physical barrier between two parts and by absorbing fluids that try to pass between the joint. Thus, cellulose gasket materials are advantageous because a desirable seal is formed between two joined parts.
Gaskets made of cellulose will expand and contract with absorption and desorption of fluids into the cellular structure of the gasket. Desorption of some of the fluids causes the release of some of the moisture absorbed into the gasket to be placed onto the surface of the two joined parts. The surface moisture will catalyze an electrochemical reaction which causes metal parts in contact with the gaskets to rust. Rust is undesirable because it can damage machine parts and creates the necessity of having to disconnect the two parts and remove the rust. Even more problematic is that the electrochemical reaction may cause the gasket to bond onto a metal part, which may result in permanent damage to the part or parts. Another problem associated with absorption and desorption of fluids in the gasket material is that wicking will occur on the exterior outside edges of the gasket. Wicking is a process whereby the gasket is deformed and broken down, which eventually results in the degradation of the seal in the joint.
Other gaskets which do not absorb fluids, such as rubber gaskets, may be used. However, gaskets which do not absorb water still allow for rust formation because moisture will still collect around and near the gasket. The water that collects near the non-cellulose gasket will catalyze the electrochemical reaction similar to the moisture released from a cellulose gasket. Thus, gaskets which allow for the collection of moisture are disadvantageous because rust can form which in turn can damage or ruin various parts and prevent them from being used again.
In response to problems associated with rust formation and wicking different gasket compositions have been tried. It appears, however, that none of the gasket compositions have successfully prevented rust formation and wicking, as these two problems almost always occurs in gasket compositions comprised of cellulose materials. In fact all cellulose gasket materials absorb moisture by various means, with wicking frequently occurring on the exterior outside edges. Thus, it would be desirable to have means which prevents rust formation for an extended period of time between matched machine parts, while still allowing for a seal to occur between the parts. Also, it would be desirable to have a cellulose gasket material that does not suffer from wicking. Preferably the means for preventing rust would release an amount of oil for an extended period of time. The released oil would also prevent wicking from occurring.
USPTO Backgrounds
USPTO Backgrounds