משמעות ושימוש
5.1 Hot melt adhesives usually need to be used at higher temperatures to make the viscosity of the adhesive low enough that it can be easily handled in typical hot melt equipment. Adhesive changes caused by exposure to the harsh environment required for hot melt processing can disrupt the adhesive application process and may affect the quality of the adhesive bond. Changes in adhesive viscosity may affect the amount of adhesive dispensed by the sizing machine. Phase separation or changes in viscosity and color may indicate changes occurring in the adhesive that may affect the quality of the adhesive joint. Skin that forms on the adhesive may eventually block the applicator nozzle or mold.
5.2 The data generated in this test procedure is comparable. The results can be used to observe batch to batch variation or relative thermal stability of alternative adhesive formulations. The results are also useful for selecting coating equipment and establishing operating conditions to satisfactorily handle specific hot melt adhesives.
5.3 Cyclic testing shows that the repeatability of this test method depends to a large extent on the characteristics of the adhesive being tested. The results show that for specific adhesives tested in the cycle, this test method is well suited for testing the thermal stability of adhesives based on EVA copolymers, polyolefins and polyamides. למרות זאת, due to poor reproducibility, this test method is not suitable for evaluating the thermal stability of adhesives based on block copolymers. The accuracy of this test method is discussed in Section 11.
שלב 1: תְחוּם
1.1 This test method covers the evaluation of changes in the properties of hot melt adhesives as they age in the molten state during hot melt. The properties of the melt monitored are viscosity, צֶבַע, skin formation and phase separation.
1.2 Values expressed in SI units shall be considered standard.
1.3 This standard is not intended to address all safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health measures prior to use and to determine the applicability of regulatory restrictions.
ASTM D4499-2015 Standard Test Method for Thermal Stability of Hot Melt Adhesives
2. Refer to the file
ASTM standard
D907 adhesive terms
D1544 Test method for color of transparent liquids (Gardner Color scale)
D3236 Test method for apparent viscosity of hot melt adhesives and coatings
E691 Practice of conducting inter-laboratory studies to determine the accuracy of test methods