ISO 22970:2019 pdf free.Paints and varnishes – Test method for evaluation of adhesion of elastic adhesives on coatings by peel test, peel strength test and tensile lap-shear strength test with additional stress by condensation test or cataplasm storage.
4 Principle
4.1 Adhesive strength test method A — Peel adhesion
It describes the peel adhesion test of adhesives on coatings. This method is suitable where a qualitative, i.e. visual, evaluation ofan adhesive’s behaviour is sufficient or when testing large and voluminous parts.
The adhesive is applied to the test panel in form of a (round or triangular) bead, dried and peeled off the coating using a cutter knife and, if required, pliers. This is followed by a visual evaluation of the failure pattern.
4.2 Adhesive strength test method B — Peel strength
It describes the adhesive strength testing of adhesives by determination of the peel force. This method enhances the range of results obtained using method A by additional quantitative measurement values and enables a statement as to which forces are transmitted to the adherend.
The adhesive is applied to the test panel to be bonded in form of a (round or triangular) bead, pressed to the required thickness using a suitable thin plate and cured. A tensile force is applied to the plate thereby peeling it off the bond in a defined angle. The reported result is the maximum force measured for each bond width (see Figure 20).
4.3 Adhesive strength test method C — Tensile lap-shear strength
It describes the adhesive strength testing of adhesives on coatings by determination of the tensile lap- shear strength. This method yields both qualitative and quantitative results. It is suitable for testing complete bonded assemblies as later used in practice. This also includes the use of original adherends.
The tensile lap-shear strength of overlap specimens is determined by stressing in shear of an overlap joint between rigid adherends by applying to the adherends a tensile force which is parallel to the bond area and to the major axis of the specimen. The reported result is the maximum force or maximum tensile shear stress measured for each bond width.
4.4 Conduction of the test
After complete curing of the adhesive, testing is conducted according to adhesive strength test method A, B or C, either immediately or following subsequent climatic exposure (exposure method 1 or 2).
5 Apparatus and test media
Normal laboratory equipment together with the following.
5.1 Adhesive strength test method A — Peel adhesion
5.1.1 Test panel, e.g. coated plates having dimensions of approximately 200 mm x 100 mm and a thickness of 0,7 mm to 1,2 mm or coated plastic or coated glass (float glass) having a thickness of approximately 4 mm. The thickness shall be sufficient to prevent deformation or fracture of the test panel in combination with the specimen grip under the expected tensile load when peeling off the bead.Specimen preparation, coating and drying/curing shall be indicated in the test report.
The response time of the testing machine shall be sufficiently short to prevent influences on the accuracy when measuring the force at failure. The recorded force shall not deviate from the actually required force by more than 1 %. The testing machine shall be capable of applying the required tensile force increasing at a steady rate. It shall be provided with a pair of suitable self-aligning grips to hold the specimen. The grips and attachments shall be constructed such as to move into alignment with the specimen as soon as the force is applied, so that the longitudinal axis of the specimen will coincide with the direction of the required force through the centre line of the grip assembly to avoid bending moment. Grips that operate by bolting through the adherends shall not be used since tearing of the bolting holes is to be expected.ISO 22970 pdf download.