Characteristic Test（Chemical Characteristic）
In this test, the influence of moisture and oil on sheets and the various properties of water resistance, water absorbability, and water repellency are investigated.
Water resistance test
In this test, the strength of a sheet when soaked in water is investigated. The tensile strength is measured after a sheet is soaked in water for a certain period of time. The water temperature may change depending on the type of sheet. Since paper is generally weak when exposed to water, it is made to withstand impregnation, coating, and use in water by employing water-resistant material, adding chemicals, or processing to provide water resistance to sheets.
Water absorption test
In this test, sheets are soaked in water for a certain period of time and then the penetration of water is measured to determine the water absorption level.
Water repellency test
Water repellency is a property related to surface wettability. There are two ways of evaluating water repellency: a method where liquid is dropped on an inclined sheet to see how the liquid drops run off and a method where the angle of the contact surface between the sheet and water (contact angle) is measured. To provide water repellency to sheets, the surface is coated with a water-repelling agent or a water-repellent material is used.
Water-resistant dimension stability test
In this test, a change in the dimension of a sheet is measured after the sheet is soaked in water for a certain period of time. Sheets expand or shrink when exposed to water and moisture. Sheets that show little change have superior water-resistant dimension stability. This physical property is necessary for materials for which the influence of water or moisture is important, such as building materials.
In this test, the wettability of the sheet surface is investigated by measuring the surface tension of the sheet for a liquid. Wettability is an important physical property for taking ink well for printing and retaining coating solutions and adhesives.
Oil resistant test
This is a test to determine the resistance of a sheet to oil by measuring the tensile and bursting strength of the sheet after soaking in oil for a certain period of time. Depending on the intended use of the sheet, resistance to hot oil may be investigated by increasing the oil temperature.
Oil absorption test
In this test, the oil absorption level of a sheet is investigated by measuring the weight of oil absorbed by a sheet of a certain size. This test relates to the consideration of the impregnation of a solvent-based liquid and the printability.