Materials may be used for their various properties. For example, materials, such as a polyurethane, polyacrylic, 1,3 propaneiol terephthalte (DuPont 3GT™ or DuPont Sorona™), and polyactide made from lactic acid (DOW Cargill Ingeo™) films, may be used for their water-proof and breathable properties. These materials provide moisture vapor transfer while preventing penetration of liquid. Such materials may be used, for example, in apparel (e.g., rain gear, jackets, gloves, boots, and pants). It is worth noting that a water-proof breathable membrane is different from a water-resistant breathable membrane. Under standard atmospheric pressure, a water-proof breathable membrane does not allow liquid to transverse the membrane, whereas a water-resistant membrane may permit traversal of liquid. A measurement known as hydrostatic head may be used to determine whether a membrane is waterproof or not. This measurement determines the pressure at which a membrane starts to leak water. A membrane is generally considered to be waterproof if it does not leak when subjected to a pressure of 1000 mbar.
Water-proof membranes may be advantageously used in materials to prevent or minimize moisture penetration into the material. Examples of such uses include use in garments, such as rain coats, where it is desirable to prevent the wearer of the garment from getting wet. Although water-proof membranes are superior to water-resistant membranes in their capacity to prevent or minimize moisture penetration, water-proof materials that are non-breathable exhibit limited capacity for moisture transport, when compared to water-resistant membranes. As result, a garment made from water-proof non-breathable materials (e.g., rubber) may seem “hot and humid” to the wearer because it does not permit moisture vapor to escape from within the garment to the outside environment.
Therefore, there is a need for a breathable membrane (e.g., water-proof membrane) having improved moisture transport properties.
Yet another important property of materials relates to the material's anti-static capacity. Anti-static materials may be advantageously used in, for example, protective packaging materials to protect sensitive electronic components from static electrical charge. The problem with packaging electronic components and units so as to avoid the effects of electrostatic discharge has become increasingly acute as smaller and smaller dimensions are achieved in integrated circuits, making the devices more vulnerable to accidental discharge by relatively small voltage levels. There is therefore a need to produce anti-static materials with improved anti-static capabilities without losing other properties, such as flexibility and transparency, that are also desirable for the various uses of these materials.
Yet another often desirable property of materials is the stealth property of the material. Materials with stealth properties may be used to eliminate unwanted infra-red signatures during experiments. In military applications, stealth materials may be employed to enable aircrafts, soldiers, ships, and planes to operate while remaining less visible to radar, infra-red and other detection mechanisms. There is therefore a need to produce materials with improved stealth capabilities without losing other properties, such as flexibility and “hand and feel,” that are also desirable for the various uses of these materials.
USPTO Backgrounds
USPTO Backgrounds