The measurement of softness refers to the situation where, under a certain test gap width, a plate-shaped probe moving up and down presses the sample into a certain depth of the gap. The vector sum of the sample's own resistance to bending force and the frictional force between the sample and the gap is measured. This value represents the softness of the paper.
This method is applicable to various types of wrinkle-resistant toilet paper and its derivative products, as well as other paper products with softness requirements. It is not applicable to napkins, facial tissues that have been folded or embossed, or paper with a higher stiffness.
1. Definition
Softness refers to the vector sum of the bending resistance of the sample itself and the friction force between the sample and the gap when a plate-shaped measuring probe is pressed into the gap of a certain width and length to a certain depth under the conditions specified by the standard (the unit of force is mN). The smaller this value is, the softer the sample is.
2.Instruments
The instrument adopts the YYP-1000 softness tester, also known as the microcomputer paper softness measuring instrument.
The instrument should be installed on a level and stable table, and it should not be subject to vibrations caused by external conditions. The basic parameters of the instrument should meet the following requirements.
3. Instrument parameters and inspection
3.1 Slit Width
(1) The range of slit width for instrument testing should be divided into four grades: 5.0 mm, 6.35 mm, 10.0 mm, and 20.0 mm. The width error should not exceed ±0.05 mm.
(2) The slit width and width error, as well as the parallelism check between the two sides, are measured using a vernier caliper (with a graduation of 0.02 mm). The average value of the widths at the two ends and the middle of the slit is the actual slit width. The difference between it and the nominal slit width should be less than ±0.05 mm. The difference between the maximum and minimum values among the three measurements is the parallelism error value.
3.2 Shape of the plate-shaped probe
Length: 225 mm; Thickness: 2 mm; Arc radius of the cutting edge: 1 mm.
3.3 Average travel speed of the probe and total travel distance
(1) Range of average travel speed and total travel distance of the probe, average travel speed: (1.2 ± 0.24) mm/s; total travel distance: (12 ± 0.5) nm.
(2) Inspection of total travel distance and average travel speed of the measuring head
① First, set the probe to the highest position of the travel range, measure the height h1 from the upper surface to the tabletop using a height gauge, then lower the probe to the lowest position of the travel range, measure the height h2 between the upper surface and the tabletop, then the total travel distance (in mm) is: H=h1-h2
② Use a stopwatch to measure the time it takes for the probe to move from the highest position to the lowest position, with an accuracy of 0.01 seconds. Let this time be denoted as t. Then the average moving speed (mm/s) is: V=H/t
3.4 Depth of Insertion into Slot
① The insertion depth should be 8mm.
② Inspection of insertion depth into slot. Using a vernier caliper, measure the height B of the plate-shaped probe itself. The insertion depth is: K=H-(h1-B)
4. Sample Collection, Preparation and Processing
① Take the samples according to the standard method, process the samples, and test them under standard conditions.
② Cut the samples into 100 mm × 100 mm square pieces according to the layer count specified in the product standard, and mark the longitudinal and transverse directions. The size deviation in each direction should be ±0.5 mm.
③ Connect the power supply according to the manual of the PY-H613 softness tester, preheat for the specified time, then adjust the zero point of the instrument, and adjust the slit width according to the requirements of the product catalogue.
④ Place the samples on the softness testing machine platform, and make them as symmetrical as possible to the slit. For multi-layer samples, stack them up in an upper-lower manner. Set the peak tracking switch of the instrument to the peak position, press the start button, and the plate-shaped probe of the instrument starts to move. After it has moved the entire distance, read the measurement value from the display, and then measure the next sample. Measure 10 data points in the longitudinal and transverse directions respectively, but do not repeat the measurement for the same sample.
Post time: Jun-03-2025