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GB/T 22638 comprises the following parts under the general title Test methods for aluminium and aluminium alloy foils:
——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 is part 9 of GB/T 22638.
This part is developed 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 following main technical changes have been made with respect to GB/T 22638.9-2008:
——the standard name is modified to Test methods for aluminium and aluminium alloy foils - Part 9: Determination of hydrophilic property
——“Normative references” is added;
——requirements are added for distilled water;
——requirements are specified for the precision of the contact angle tester, range is modified for the temperature fluctuation of the oven, and requirements are specified for the precision of the vernier caliper;
——the previous content of the specimen is deleted, the specimen dimension is unified, and the contents are added for preparing specimens of initial hydrophilic angle, process hydrophilic angle, continuous immersion hydrophilic angle, and dry-wet cycle hydrophilic angle;
——the description is modified on the hydrophilic angle in the contact angle tester method, and the schematic diagram is added for contact angle;
——the rule is added to the microsyringe method that “the distance between the needle tip and the surface of hydrophilic foil is about 10 mm”;
——the standing time of water droplets on the specimen in the microsyringe method is modified to "40 s ~ 60 s";
——the determination precision is specified for the maximum and minimum water droplet diameters in the microsyringe method, and the explanation is added that the “calculation result of average water droplet diameter is accurate to one decimal place";
——the contents are deleted on determination of the initial hydrophilic angle, the process hydrophilic angle, the continuous immersion hydrophilic angle, and the dry-wet cycle hydrophilic angle.
This part was proposed by China Nonferrous Metals Industry Association.
This part is under the jurisdiction of National Technical Committee 243 on Nonferrous Metals of Standardization Administration of China.
The previous edition of this part is as follows:
——GB/T 22638.9-2008.
Test methods for aluminium and aluminium alloy foils - Part 9: Determination of hydrophilic property
1 Scope
This part of GB/T 22638 specifies the determination method for hydrophilic property of coated aluminum and aluminium alloy foils.
This part is applicable to the determination of hydrophilic property of coated aluminum and aluminum alloy foils.
The contact angle tester method specified in this part is the arbitration test method for hydrophilic property of aluminium and aluminium alloy foils.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
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 Principle
Drop distilled water droplets on the surface of the coating, and the water droplets will spread under the action of surface tension. In this method, the hydrophilic property of the coating is determined by measuring the contact angle (i.e. hydrophilic angle) formed by the water droplet and coating surface.
4 Reagents
4.1 Distilled water, which shall meet the requirements of Grade 3 water for laboratory use specified in GB/T 6682.
4.2 Cleaning-free volatile oil.
5 Apparatus
5.1 Contact angle tester, with a measurement precision of 0.1°.
5.2 Air blast constant temperature oven, with the temperature controllable at 150℃±1℃.
5.3 Beaker, with a capacity of 500 mL.
5.4 Water tank, with a cross-sectional area of 280 mm×200 mm.
5.5 Microsyringe, 10 μL.
5.6 Vernier caliper, 0 mm to 100 mm, with a resolution of 0.02 mm.
6 Specimen preparation
6.1 Specimens of initial hydrophilic angle
Take 3 clean and flat specimens with the dimension of 100 mm×50 mm
6.2 Specimens of process hydrophilic angle )
Cut the specimens according to 6.1, immerse the specimens in the cleaning-free volatile oil (4.2) for 5 min, and remove the clean-free volatile oil from the surface after taking them out. Bake the specimens in an air blast constant temperature oven (5.2) at a temperature of 150 ℃ for 5 min, then take them out and cool them to room temperature. Immerse them in distilled water (4.1) for 5 min, then place them in an air blast constant temperature oven (5.2) at a temperature of 150 ℃ for 10 min, and cool the specimen for later use. During the whole test, the specimens shall not adhere to each other.
6.3 Specimens of durable hydrophilic angle
6.3.1 Specimens of continuous immersion hydrophilic angle1)
Cut the specimens according to 6.1, fix them on the specimen rack, immerse them in a water tank (5.4) with a water flow rate of 1 L/min to 3 L/min (non-circulating water is used and the water tank is placed horizontally) for 100 h, then take them out and dry them.
6.3.2 Specimens of dry-wet cycle hydrophilic angle1)
Cut the specimens according to 6.1, fix them on the specimen rack and immerse them in the distilled water (4.1) for 2 min in a sealed and clean environment at a temperature of 25℃±5℃ and a humidity of not less than 80%. Take 6 min of natural drying as a cycle, repeat the cycle for 300 times and then dry them. The drying time should not exceed 4 h.
7 Method for determination of contact angle
7.1 Turn on the power supply of the contact angle tester (5.1) and adjust the level of the contact angle tester.
7.2 Fix the specimen on the workbench.
7.3 Add distilled water into the liquid droplet regulator, fix the regulator on the main machine and rotate the micrometer head, so that a proper amount of water (0.005 mL to 0.02 mL) forms water droplets on the needle head which drop on the specimen surface. For each specimen, drop one droplet at three different positions. Adjust the position of the workbench so that the water droplets are located in the center of the eye lens.
7.4 After the water droplet is let stand on the specimen for 40 s to 60 s, rotate the reticle in the eye lens to form the tangent of the contact point of the water droplet and the coating. The included angle formed by the tangent and the horizontal plane of the specimen is the contact angle, and this contact angle is the hydrophilic angle. See Figure 1.
Foreword i
1 Scope
2 Normative references
3 Principle
4 Reagents
5 Apparatus
6 Specimen preparation
7 Method for determination of contact angle
8 Microsyringe method
9 Test report
