Page 171 - Handbook of Adhesives and Sealants

Standard Test Methods 141

Tackiness is generally determined with a tensile testing machine
and test blocks. The blocks are pulled apart immediately after the
adhesive is applied and the blocks are joined. The result is reported
in force required per square inch of bonded area (psi) to separate the
blocks. Various instruments have also been developed to measure tack
for specific applications. Table 4.3 lists and compares various test
methods that have been used.
Other important characteristics related to tack and commonly mea-
sured are:

Dry tack—a property of certain adhesives to stick to one another
even though they seem dry to the touch
Tack range—the time that an adhesive will remain in a tacky con-
dition

4.3.1.5 Cure rate. Structural adhesives usually require curing by ei-
ther the application of heat, the addition of a catalyst, the addition of
pressure, or a combination of the three. The strength developed in the
adhesive joint at various times during the curing process may be mea-
sured by lap shear tensile specimens. This test is commonly used to
determine when an adhesive or sealant is fully cured or when the
system reaches a ‘‘handling’’ strength so that the assembled product
can be moved with moderate care.

TABLE 4.3 Comparison of Test Methods to Determine Tack of an Adhesive 2
Organization Method Common name Notes
ASTM D 2979 Probe Tack
ASTM D 3121 Rolling Ball Tack 1
TLMI LIB 1 Loop Tack 2
TLMI LIB 2 Loop Tack 3
PSTC 5 Quick Stick 4
PSTC 6 Rolling Ball Tack 1
FINAT FTM 9 Loop Tack 5
AFERA 4015 Quick Stick 4
NOTES:
1-The methods described in ASTM D 3121 and PSTC 6 are virtually identical.
2-This method describes Loop Tack measurement using a specially designed piece of test
equipment.
3-This method describes Loop Tack measurement using an adapted tensile tester.
4-PSTC 5 and AFERA 4015 describe nearly the same testing technique. The AFERA method
describes the use of a lightweight (25 grams) roller to apply the test specimen to the panel,
whereas the PSTC method uses only the weight of the test strip to accomplish lamination.
5-The FINAT method is similar to the TLMI method for Loop Tack, except that the FINAT
method uses glass rather than stainless steel as the test surface.
6-ASTM (American Society for Testing and Materials)
TLMI (Tag and Label Manufacturers Institute)
PSTC (Pressure Sensitive Tape Council)
FINAT (European Assn. for the Self Adhesive, Labeling Industry)
AFERA (Association des Fabricants Europeens de Rubans, Auto-Adhesifs)