GB/T 22638.9-2016Test methods for aluminium and aluminium alloy foils—Part 9: Determination of hydrophilic property (English PDF)

Foreword

GB/T 22638 Test methods for aluminium and aluminium alloy foils is divided into 10 parts.

-- Part 1: Determination of thickness;

-- Part 2: Determination of pinhole;

-- Part 3: Determination of stickiness;

-- Part 4: Determination of surface wetting tension;

-- Part 5: Determination of wettability;

-- Part 6: Determination of direct current resistance;

-- Part 7: Determination of heat seal strength;

-- Part 8: Determination of cube texture content;

-- Part 9: Determination of hydrophilic property;

-- Part 10: Determination of mass per unit area (surface density) of coatings.

This part is Part 9 of GB/T 22638.

This part was drafted in accordance with the rules given in GB/T 1.1-2009.

This part replaces GB/T 22638.9-2008 Test methods for aluminium and aluminium alloy foils - Part 9: Determination of hydrophilic property. The main technical changes compared to GB/T 22638.9-2008 are as follows.

-- The standard title has been changed to "Test methods for aluminum and aluminum alloy foils - Part 9: Determination of hydrophilic property".

-- The normative references have been added.

-- The requirement for distilled water has been added.

-- The accuracy requirements for the contact angle measuring instrument have been clarified, the temperature fluctuation range of the drying oven has been modified, and the accuracy requirements for the vernier caliper have been clarified.

-- The original sample content has been deleted, and the sample dimensions have been standardized; the content on the preparation of samples for initial Test methods for aluminum and aluminum alloy foils - Part

1 Scope

This part of GB/T 22638 specifies the test method for the hydrophilicity of coated aluminum foil.

This part applies to the testing of the hydrophilicity of coated aluminum foil.

The method using a contact angle measuring instrument specified in this part is an arbitration test method for the hydrophilicity of aluminum foil.

2 Normative references

The following documents are essential for the application of this document. For any dated reference, only the version corresponding to that date applies to this document; for any undated reference, the latest version (including all amendments) applies to this document.

GB/T 6682 Water for analytical laboratory use - Specification and test methods

GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values

3 Method principle

When distilled water is dropped onto the coating surface, the droplet spreads out under the influence of surface tension. This method detects the hydrophilicity of the coating by measuring the contact angle (i.e., the hydrophilic angle) formed between the water droplet and the coating surface.

4 Reagents

4.1 Distilled water, which shall meet the requirements of Grade III laboratory water specified in GB/T 6682.

4.2 No-clean volatile oil.

5 Apparatus

5.1 Contact angle measuring instrument, with a measurement accuracy of 0.1°.

5.2 Forced-air constant temperature drying oven, in which the temperature can be controlled at 150 °C±1 °C.

5.3 Beaker, 500 mL.

5.4 Water tank, with a cross-sectional area of 280 mm×200 mm.

5.5 Micro-syringe, 10 µL.

5.6 Vernier caliper, 0 mm~100 mm, with a resolution of 0.02 mm.

6 Specimen preparation

7 Method using a contact angle measuring instrument

7.1 Turn on the power to the contact angle measuring instrument (5.1) and adjust the contact angle measuring instrument to be horizontal.

7.2 Fix the specimen on the worktable.

7.3 Add distilled water to the droplet regulator, fix the regulator on the main unit, and rotate the micrometer head to form a water droplet on the needle tip with an appropriate amount of water (0.005 mL~0.02 mL). Drop the water droplet onto the specimen surface, one droplet at each of the three different locations on each specimen. Adjust the position of the worktable so that the water droplet is located in the center of the eyepiece.

7.4 When a water droplet is left to stand on the specimen for 40~60 seconds, rotate the crosshairs in the eyepiece to draw the tangent at the point of contact between the water droplet and the coating. The angle between the tangent and the horizontal plane of the specimen is the contact angle, which is also known as the hydrophilic angle. See Figure 1.

7.5 The average value of the hydrophilic angle test results of 3 specimens shall be taken as the hydrophilic angle measurement value. The calculation result shall be accurate to […]

9 Determination of hydrophilic property