Duct tape is a cloth tape coated with a poly-ethylene resin on one side and
very sticky rubber-based adhesive on the other. The fabric backing gives duct
tape strength yet allows it to be easily torn.
Used for Household Repair Jobs:
Consumers have found a broad range of uses for this popular product. It can be
used for household repair jobs, and in car maintenance. Snow mobilers have even
been known to apply duct tape to their noses to thwart frost-bite and sunburn. The
Duct Tape Book describes how to use duct tape to make aprons and trampoline covers.
Cotton mesh: Cotton mesh forms the backbone
of duct tape. It provides tensile strength and allows the tape to be tom in both
directions. Cloth that has a tighter weave and higher thread count is of a
higher quality, provides greater strength, and gives a cleaner tear. A premium
quality tape can have a thread count of 44 x 28 threads per square inch. Tape
made with this fabric is more expensive. The cotton fabric is called a "web"
when it is spread across the coating machinery.
Polyethylene coating: The cotton fabric
is coated with polyethylene, a plastic material that protects it from moisture
and abrasion. This plastic coating is flexible and allows the tape to adhere
better to irregular surfaces.
The polyethylene is melted:
And applied to the fabric in a preliminary coating operation. The coated fabric
is then stored on rolls until the manufacturer is ready to apply the adhesive.
Adhesive compound: Adhesive itself is
formulated with rubber compounds that ensure long-term bonding. Adhesive is
applied to the substrate in a much thicker coating than those used on cellophane
or masking tapes. This too serves to increase the adhesive properties of the tape.
The Manufacturing Process:
Adhesive compounding: The rubber-based
adhesive used in duct tape is prepared in a multi-step process. In the first
step the adhesive is compounded in a mixer known as a Branbury-type mixer
consisting of a stainless steel tank equipped with a steam jacket to heat
the compound and a high torque mixer. The rubber compounds are introduced
in pellet form, then heated and mixed until they are melted and homogenous.
Other ingredients are added to the blend tank:
These include tackifying agents, viscosity modifiers, antioxidants, and other
adjuncts. The final mixture is thick but smooth enough to be pumped to a
holding tank connected to the coating equipment.
Packaging operations: In this final stage the
rolls of duct tape are packaged for sale. They are typically shrink wrapped,
either singularly or in packages of two or three. These packages are then
boxed and marketed for shipping.
Depending on the manufacturer, the steps described above can be combined through
automation into fewer steps. Permacell uses a self-contained apparatus which
mixes, heats, and fastens the adhesive onto the backing. This method allows
the glue to be prepared without pollution-causing solvents.
Quality Control: Adhesive strength and
cohesive strength. Standardized stainless steel plate, and then measuring
the force required to rip it off. The plate is then examined to determine
how much, adhesive residue is left behind. The adhesive coating itself is
monitored to evaluate how well it sticks to its backing. Adhesive leaves
a residue is known as creeping, crazing, oozing and bleeding.
Companies may measure the duct tape's breaking point:
Others evaluate the "scrunch" sound of the tape as it unwinds because consumers
believe a noisy rip off the roll is a sign of strength. Other tests are designed
to measure quick stick. By shooting ping-pong balls at tape strips with the
sticky side up to measure how far they roll before they are stopped by the tape.
Wishing you all the best,