Specifications

 

Weight - From the commercial point of view the weight of the paper is probably his most important characteristic. It follows that the user's interest to use cards as light as possible. Therefore, the customer specifies in its order always the nominal weight of the paper, intended as a lightweight unit area, measured in grams per m2.

Thickness - The thickness is the distance between the two sides that surround the sheet. The thickness of the paper is determined, in principle, with a feeler gauge (commonly called micrometer because it measures the micron, or the thousandth part of a millimeter).

Dry Breaking Strength - The tensile strength of paper (or breaking strenght) is the resistance that arises when a strip is being urged to traction, that when applied to its ends is a growing force. This in turn deforms, increasing its length, until the time of breakage. The strain present at that time is called tensile strength, expressed in newtons (or kg). This physical characteristic is important in the automatic changes of the rolls.

Wet tensile strength - For certain applications it is required that the paper retains a considerable strength even when saturated with water (for example during the impregnation when it enters in the resin bath in aqueous solution, or during the printing with inks dispersed in water). The test is the same of the dry tensile strength, but is performed after soaking the central part of the strip in water for thirty seconds. The value obtained is expressed in Newton.

Gurley Porosity – The air permeability decreases with the progress of refining it also reduces due to the effect of smoothing (for crushing) and influence the penetration of the resin during impregnation. The Gurley porosity indicates the time, in seconds, to pass 100 ml of air through a card placed over a hole in a square inch (6.45 cm2) of surface.

Smoothing - The smooth test determines the order and the specularity of the surface of the paper. Better is the smoothing greater the ease and clarity of printing and lowest is the ink consumption. One of the most widely used devices is the Bekk that measures time in seconds needed by the vacuum generated by a column of mercury falls from 380 to 360 mm, the device is designed so that entering in it 10 cm3 of air through a hole of 1 cm2, passing through a flat surface covered with glass and the surface of the paper to be examined, the air will go into the lower amount as the gaps are small, or how the paper surface is smooth.

Absorption Klemm - It 's based on hydrophilic characteristic of fibrous material, where the refining and modification reduces this capacity. The test with the Klemm method indicates the ability of a strip of paper to absorb water by capillary action, after 10 minutes of contact. The value expressed in mm, will be higher than the greater is the absorbency of the sample.

Lightfastness - (only for knowledge) - The light fastness is one of the most important characteristics for the decorative paper. Apply in practice, methods and equipment commonly used for textiles, given that the needs of the tissues are the same as laminates, can you imagine replacing the door of a furniture after some time and realize that the color of the old is haggard and degraded? This is an applied research on all products that come in the papers for laminates, pigments and printing inks. One of the devices used to control the light fastness is the Fade-Ometer ( Xenotest). The apparatus includes, as an essential part, a source of radiation of high power, which produces in a very short time a similar effect to that of sunlight (it is said that simulates the "solar spectrum" of a day of the month of June to 'noon hour in the city of New York). The lamp is in the middle of a test chamber under a special glass case, around that are placed the sample holder and rotate slowly with a constant speed so that all tubes are irradiated in the same way. The exposed samples are half covered and the other half is exposed for a set time: 24, 48, 96, 150, 300 hours or more, after which the samples are removed and evaluate possible damage suffered, by comparing the exposed part and the remaining covered part. The reference used is the "Lana Scale", a color scale consisting of strips of fabric made by mixing increasing proportions two colors blue, one light fastness and one little fastness. This is a fundamental means for the selection of raw materials (titanium dioxide, pigments for paper and for inks).

The other device used is the Xenotest, where as the radiation source is used a xenon lamp power of 1500 W with color temperature between 5500 and 6500 Kelvin.

Color temperature - is specified with a number corresponding to the temperature which should bring a black body emission that causes a sensation of color equal to the illuminant in question and is expressed in Kelvin