Basic Knowledge of adhesive tape

Basic Knowledge of adhesive tape

News 08 Mar 2021

Duct tape
Adhesive tape is our common daily necessities, take double sided tape as an example, it’s divided into 3 layers, which are substrate, pressure sensitive adhesive and release film. 

1.Substrate is base material on which is coated with adhesive.

2.Pressure sensitive adhesive is a kind of adhesive can be immediately bonded together with smooth surface of any adherend through finger pressure.  

3.Release film is paper or film coated with silicone oil in order to prevent adhesive tape adhering to its backing and protect adhesive tape from contamination.
Double Sided Tape

duct tape

There are also 3 basic properties of adhesive tape, adhesion, cohesion and initial tack.

1.Adhesion is the viscosity strength between the adhesive and adherend

2.Cohesion is the internal strength of adhesive.

3.Initial tack is the contact force between the adhesive and the adherend under no pressure.

Let’s take honey, the most commonly seen sticky material in the world, as an example. According to the definitions above, honey has high adhesion, low cohesion and quite strong initial tack. Does this make sense to help you roughly understand the above 3 meanings? Then, let’s get down to explain each meanings by details.

1st, Adhesion, means the attraction between adhesive and adherend as it shows. It’s also the most important adhesive tape performance index. Bonding force, which is defined by adhesive species, adherend property, pressure extent and time, is created by applying pressure to the bonding surface. It’s also different from initial tack.

2nd, Releasing force, or peeling force, refer to the force required to peel off a piece of tape from a standard test board at a specified velocity and at an angle of 180 degrees.

duct tape

Testing conditions:

1.Testing timing: immediately or after 14 days.

2.Environment: 23±1℃, 50±5% relative humidity.

3.Rolling: 4 Kilograms, 5 times at 10 meters per minute.

4.Enforcement material: Polymer film with 40um thickness.

5.Peeling velocity: 300 meters per minute.

3rd, Initial tack, refers to the contact force generated by the initial contact between the adhesive and the adherend. It means adhesion under the minimum pressure and shortest contact time. Please be aware that initial tack has nothing to do with the adhesion under pressure. The higher initial tack is, the better adhesion to rough surface, and the higher adhesion to the adherend under pressure. The common wrong way to test initial tack is testing with finger.

Initial tack rolling ball testing experiment (ASTM D3121-94) 

The force that the tape grips the surface of the adherend.

duct tape

4th, Cohesion, internal strength of adhesive, or the force holds adhesive tape together in use. (or shearing force) also means stress action parallel to the adhesive surface. Adhesive tape with high cohesion usually have features below.

High temperature resistance.

Relatively low initial peeling force and relatively high final peeling force.

Adhesive has low fluidity.

Low initial tack.

5th, shearing force, the relative sliding resistance when the free end of the adhesive tape is loaded, and the other end is pasted on the designated surface.

Testing conditions:

Pasting measurement: 260mm²

Rolling: 2 kilograms, 2 times, 0.3 meter per hour.

Load: 1 kilogram.

Testing Environment:

23±1℃, 50±5% relative humidity.

40/70℃, Laboratory oven.

Reinforcement material: Aluminium foil.

duct tape

Cohesion and adhesion in tape application

Cohesion (shearing force) and peeling force (adhesion) are 2 forces reversely proportional, so in the adhesive tape application, these 2 forces need to be balanced to ensure good bonding effect.


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