Shenzhen Puyun Electronics ***PY-E635 dust degree tester is suitable for the determination of paper or cardboard dust degree, under any angle of irradiation on the paper surface, we can see the fiber bundles and other impurities that are different from the color of the paper, we call dust. In the QS certification of paper packaging, it is suitable for: food parchment paper, translucent paper, product packaging paper, food packaging cardboard.
GB T1541-2013 "Determination of dust degree of paper and cardboard".
Impurity: Any unwanted small piece of material embedded in the pulp that exceeds the specified minimum size and exhibits a noticeable opacity relative to the surface of the sheet.
Dust degree: the number of impurities with a certain area on paper and cardboard per square meter area, or the equivalent area (square millimeter) of impurities on paper or cardboard per square meter of area.
The dust degree measuring table shall meet the following requirements:
1. Lighting device: The irradiation angle of 20W fluorescent lamp should be 60°.
2. Rotatable test sample: milky white glass plate or translucent plastic plate, the test sample area is 270mm 270mm.
3. Standard dust comparison chart: a series of dust with different areas and shapes printed on a transparent film, the same horizontal row is arranged with dust with the same area but not shape, and the same vertical column is arranged with dust with similar shape but different area.
Sampling method: take samples according to GB T 450, and cut at least four samples of 250mm and 250mm.
1. Put a cut sample on the rotatable test plate, press it with the four corner pliers on the board, check the dust visible to the naked eye on the surface of the paper and cardboard under the fluorescent lamp, and the photopic distance when observing with the eyes is 250mm-300 mm, and circle the dust in different areas with different marks. Compare the area size of the dust on the paper with the standard dust;It is also possible to record the number of dust in the same area according to the size of different areas.
2. Then rotate the sample by 90°, and mark the newly discovered dust after each rotation. Until you return to the original position, then check the other side of the specimen as above.
3. Determine the remaining 3 samples according to the above steps.
If the paper used on one side is only measured on the dust of the use surface, the four samples are combined and calculated, and then converted into the number of dust per square meter, and the calculation result is taken as an integer.
The formula for calculating impurity-dust degree: nd=16m n
The degree of dust is calculated by equation (1) and is expressed by : where:
nd—dust degree, the unit is per square meter (pcs);
m— the total number of dust on the front and back of all samples;
n— The number of specimens on which the dust was measured.
Note: If the same dust penetrates the sheet so that both sides are visible, it should be counted as two dust.