GB/T 8942-2002 English PDF (GBT8942-2002)

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GB/T 8942-2002: Paper -- Determination of softness
GB/T 8942-2002
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 85.060
Y 30
Replacing GB/T 8942-1988
Paper – Determination of Softness
ISSUED ON: SEPTEMBER 06, 2002
IMPLEMENTED ON: JANUARY 01, 2003
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine
Replaced
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms ... 4
4 Instrument ... 4
5 Sample Taken ... 6
6 Sample Processing ... 6
7 Sample Preparation ... 6
8 Test Procedures ... 6
9 Calculation of Results ... 7
10 Test Report ... 7
Appendix A (Suggestive) Inspection of Instrument Parameters ... 8
Paper – Determination of Softness
1 Scope
This Standard specifies the method of using the hand-feeling softness tester to
determine the softness of paper.
This Standard is applicable to various wrinkle toilet paper, tissue paper and its
derivatives, as well as other papers that require softness.
2 Normative References
The following standards contain provisions which, through reference in this Standard,
constitute provisions of this Standard. At the time of publication, the editions indicated
are valid. All standards are subject to revision. The parties who are using this Standard
shall explore the possibility of using the latest version of the following standards.
GB/T 450-2002 Paper and Board--Sampling for Testing (eqv ISO 186:1994)
GB/T 10739-2002 Paper, Board and Pulps - Standard Atmosphere for
Conditioning and Testing (eqv ISO 187:1990)
3 Terms
For the purpose of this Standard, the following terms apply.
3.1 Softness
Under the specified conditions, when the plate-shaped probe presses the sample
into the slit to a certain depth (about 8mm), the sum BETWEEN bending resistance
force of the sample itself AND the maximum vector of the friction force of sample and
the slit; it is expressed by millinewtons; the smaller the softness value is, the softer the
paper is.
4 Instrument
The instrument shall adopt the hand-feeling softness tester shown in Figure 1.
4.7 Instrument accuracy
4.7.1 Maximum range of the instrument: 1000mN.
4.7.2 Load accuracy: ±1%.
4.7.3 Repeatability: less than 3%.
5 Sample Taken
The average sample shall be taken as stipulated in GB/T 450.
6 Sample Processing
The sample shall be subjected to temperature and humidity treatment according to
GB/T 10739; and prepared and measured under these conditions.
7 Sample Preparation
According to the number of layers specified in the product standard, cut the sample
from the sample taken into the size of 100mm×100mm; mark the longitudinal, lateral,
front and rear sides, respectively. The size deviation shall not exceed ±0.5mm.
Whether the embossed or un-embossed sample, after uncovering the layer of the
sample, then overlap for the test of softness.
8 Test Procedures
8.1 After starting and preheating according to the instrument manual, adjust the
instrument zero point; adjust the slit width according to the provisions of product
standard. Meanwhile, check the width error and parallelism according to A1 in
Appendix A; so that they meet the requirements of 4.1 and 4.5.
8.2 Place the sample on the test bench; and make it as symmetrical as possible to the
slit. The multilayer sample shall be stacked up and down. Turn the instrument peak
value/tracking switch is turned to peak value position, press the test button, the plate-
shaped probe of the instrument begins to move. After the probe completes the whole
process, read the measurement value from the display; then test the next sample. 10
data shall be tested in the longitudinal and lateral directions, respectively.
Appendix A
(Suggestive)
Inspection of Instrument Parameters
A1 Inspection of slit width, width error and parallelism
Use a Vernier caliper (with scale of 0.02mm) to measure the width on the two ends
and middle of the slit; the average value of the measured values at the three positions
is the actual slit width; its difference with nominal width of the slit shall not exceed
±0.05mm; the difference between the maximum and minimum values of the three
measured values shall be the parallelism error.
A2 Inspection of average running speed and total stroke of the probe
A2.1 Firstly, turn the probe to the highest position of the stroke; use the height gauge
to measure the height, h1, from the upper end to the bench surface. Then drop the
probe to the lowest position of the stroke; measure the height, h2, from the upper end
to the bench surface. Calculate the total stroke, H, (in mm) as per the Formula (A1):
A2.2 Use the stopwatch to measure the time, expressed by t, for the probe travelling
from the highest to the lowest position, accurate to 0.01s; then calculate the average
running speed, V, (in mm/s) as per the Formula (A2):
A3 Inspection of pressing depth into slit
Use a Vernier caliper to measure the height, B, of plate-shaped probe itself; then
calculate the pressing depth, K, (in mm) as per the Formula (A3):
A4 Inspection of instrument accuracy
Adjust the instrument to zero point; install the special pulley frame according to Figure
A1; hang the 400mN balancing weight. Then successively equip with 100mN, 200mN,
400mN, 600mN, 800mN balancing weights; or directly add the balancing weight to the
plate-shaped probe. Repeat the above procedures for three times to obtain three sets