Paper and board roughness determination

1 , subject content and scope of application

This standard specifies the method of measuring the roughness of paper and board with a constant pressure air flow.

This standard applies to paper and paperboard with a roughness of approximately 500 to 1 200 mL/min . It does not apply to softness.

Paper, highly breathable paper, or uneven paper.

2 , reference standards

GB 450 paper and cardboard samples taken

Standard atmosphere for GB 10739 pulp, paper and paperboard sample handling and testing

3 , Terms

Bentetz roughness: Under the specified conditions and operating pressure, through the probe's ring surface and the air between the paper and or cardboard

Flow, expressed in mL/min .

4 , principle

The sample is in contact with the metal ring under a certain pressure. The air in the ring is filled with a certain pressure. The measurement is made from the sample surface and the metal ring.

The amount of air flow passing between the faces. The higher the measured value, the coarser the paper and board.

5 , 5.1

instrument

The special biometer consists of a compressor, a pressure buffer vessel, a rotameter with a pressure-regulating valve and a measuring head. See the figure below.

The special life instrument should meet the following requirements, and its maintenance rules are shown in Appendix A ( Supplement )

 

5.1.1 Measuring head

    Quality 267 ± 2g , metal measuring ring width 0.150 ± 0.002mm , inner diameter 31.5 ± 0.2mm . Measuring head and flow

The meter is connected with a rubber tube or plastic tube with an inner diameter of 5 to 6 mm and a length of not more than 600 mm .

5.1.2 Flowmeter

    10 to 150 mL/min , 50 to 500 mL/min, and some instruments 300 to 3 000 mL/min , respectively.

2 mL/min , 5 mL/min, and 20 mL/min .

5.1.3 Regulator

     The inlet of the flowmeter is controlled by a pressure-stabilizing valve and the pressures of the air flow are 0.74 ± 0.01kPa , 1.47 ± 0.02kPa , respectively.

2.20 ± 0.03 kPa , of which 1.47 kPa is the standard operating pressure.

5.1.4 When a gas pressure of 1.47 ± 0.02 kPa and a measuring head with a mass of 267 ± 2 g are used, a metal ring is applied to the sample.

The contact pressure is 98kPa , and then 600g pressure helium is added to the measuring head. At this time, the contact pressure applied to the sample is 490kPa .

5.1.5 Plane Glass Plate

    There should be sufficient flatness, within the working area, should not make visible changes in the rotor of the flowmeter.

5.2 Compressors

    It should be ensured that the air pressure before the pressure regulation is 127kPa .

5.3 pressure buffer bottle

    About 10L glass bottles.

6 , 6.1

Instrument calibration

    The level of the instrument

   Should be placed in a place without vibration and calibrated to a good level.

6.2 Instrument Sealing

   First place a smooth and soft rubber blanket on the plane glass plate and put the measuring head on it to start the instrument

Flow, and then put the 1.47kPa regulator valve on the shaft to make it turn. The instrument range is connected to the flow meter at 10 to 150 mL/min .

Observe whether the rotor of the flowmeter is zero. If it does not rise, it can be dialed to 50 ~ 500mL/min and 30 ~ 3 000mL/min flowmeter

Department. If the indication is zero, it means that the seal is good. If the rotor has a rising phenomenon, it means there is a leak between the flowmeter and the measuring head.

Check each connector and connecting tube.

6.3 Check whether the pressure ring of the measuring head is even

   If the instrument is well sealed, place the measuring head on a clean glass plate, turn on the instrument and place the pressure-regulating valve on the shaft.

Its rotation, the instrument is connected to the low-range flowmeter, at this time the flowmeter rotor should not rise, that is, zero, indicating that the pressure ring is flat.

If the pressure ring is not cleaned with a suitable solvent ( such as carbon tetrachloride ) at zero, check whether the pressure ring is defective with an optical microscope.

To detect a large change, replace the new measuring head or manually grind it. When grinding, be careful not to affect the area of ​​the pressure ring.

Law to check.

6.4 Calibration of the flow meter

   Correct with a soap bubble meter or directly with a corrected capillary (see Appendix B ( Supplement ) ).

 

7 , sample preparation and processing

At least 10 specimens of 100mm × 100mm specimens shall be taken from each test surface. The positive and negative surfaces shall be marked and the specimens shall be flat. Test surface should not

There are creases, wrinkles, eyelets, watermarks or other defects and should not touch the test area. Sample according to GB 450 , GB 10739

The treatment was performed and measured under the warm and humid conditions.

8 , test steps

8.1 Start the instrument first, and then place the 1.47kPa regulator valve on the shaft to check the seal of the instrument and the flatness of the probe.

8.2 Place the test piece on the flat glass with the test side facing up. Turn the vent valve, select the appropriate range of flow meter, will test

Gently place the tip on the test piece and keep the ring parallel to the surface of the sample. No other pressure can be applied to the measuring head, otherwise

The value is low. After 5s , read the indicator of the flowmeter rotor, which is the roughness of the test (mL/min) . The indication value should be

In the flowmeter scale value 10% ~ 90% range. It is recommended not to use air flow greater than 1 200 mL/min .

8.3 After reading the indication value, test another test piece. Only one measurement ( positive or negative ) can be measured in each test piece.

Use the same flow meter.

8.4 Test is completed, first remove the regulator valve, then turn off the instrument, so as to avoid the valve wear.

8.5 Determination of Compressibility and Elasticity

   If after testing the roughness, add pressure helium to the measurement so that the contact pressure is 490kPa . Read the flowmeter instructions.

The value, the percentage of the ratio of the reading to the roughness, indicates the compressibility of the sample. After removing the pressure, read the indicator of the flowmeter.

Indicated as a percentage of the ratio of the reading to the roughness expressed as the elasticity of the sample.

9 , test report

The test report should include the following:

a. The standard number;

b. Test temperature and relative humidity;

c. The number of test pieces;

d. The arithmetic average of test results, accurate to three significant figures;

e. If required, report the arithmetic average of the respective test results on the positive and negative sides;

f. If no standard pressure is used, it should be stated in the report;

g. Test result standard deviation or coefficient of variation;

h. Abnormalities during the test or different operations from this standard.

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