Porosity forming technology is a technology for causing polymer substances to foam and develop multiple pores. Nitto Denko has developed porosity forming technology for a diverse range of materials. With particularly highly developed technologies in the areas of membrane-formation and substance modification, Nitto Denko manufactures products with separation and air permeation functions, such as water treatment membranes and air filters.
The foam materials used in cars, electrical components, and other products, which also owe their creation to porosity-forming technology, have functions such as cushioning, waterproofing, and sealing.
Separation Membrane Technology
The manufacturing methods for ultrafiltration (UF) membranes, microfiltration (MF) membranes, and other polymer separation membranes include approaches based on phase separation, orientation, and etching. Nitto Denko manufactures polysulfone UF membranes through a type of phase separation known as non-solvent-induced phase separation (NIPS). As illustrated in the diagram below, phase separation occurs when a non-solvent is used to set a membrane-forming solution of polysulfone and a solvent, causing the formation of a multiporous structure.
When subjected to foaming, polymers can be endowed with a wide range of properties and functions, including flexibility, shock absorption, heat insulation, soundproofing and soundblocking, and light weight. Normally, a range of foaming agents is used and foaming is performed by introducing gas mechanically or by chemical decomposition of a foaming agent.
By altering the foaming agent and the foaming method, it is possible to control the size and volume of the air bubbles and also the structure.
Fluoroplastic Porous Film Technology
Fluoroplastics (e.g. PTFE), which are the raw material of multiporous substances, are characterized by ready fibrinization, with application of a small amount of shear stress sufficient to cause formation of fibrils (slender fibers). When these fibers coalesce and intertwine, a multiporous structure (membrane) is formed.
Normally, fluoroplastic multiporous membranes are formed using a method known as orientation to allow cleaving and drawing of fibers. One technology for creating pores from fibers is biaxial orientation of the fluoroplastic in the longitudinal and latitudinal directions at a high rate of magnification, which allows precise creation of pores in the microscopic fibers.