This leaflet describes how the Dynes Test Pen can be used to measure the surface energy of films and other non-absorbent substrates. This method is parallel to ASTM Std. D2578¹, which covers the testing of polyethylene (PE) and polypropylene (PP) films through the application of formamide/ethyl cellosolve* solutions. The fluids used in DYNE  Test Pens are based on the fluids specified in ASTM D2578; The main difference between this test and the ASTM technique is the way the liquid is applied to the test specimen.

 

In general, the ability of inks, coatings, or adhesives to adhere to a substrate is directly related to its surface energy. If the substrate surface energy does not exceed the surface tension of the fluid it is to cover, wetting will be inhibited and a poor bond will result. Clearly, the surface energy must be assessed before printing, coating, or laminating is attempted.

 

The unit of measurement of surface energy is dyne pens. It can also be expressed in mN/m. dyne = unit of force, equal to the force that accelerates a mass of 1 gram by 1cm/sec/sec. 1 dyne = 0.00001 newton

 

Typical Surface Energy of Base Material

Required Surface Energy for Adhesion with:

PTFE <20 mN/m(Dyne)

UV Ink 48 – 56 mN/m(Dyne)

Silicone <20 mN/m(Dyne)

Waterbased Ink 50 – 56 mN/m(Dyne)

PP 30 mN/m(Dyne)

Coatings 46 – 52 mN/m(Dyne)

PE 32 mN/m(Dyne) 

UV Adhesive 44 – 50 mN/m(Dyne)

PS 34 mN/m(Dyne)

Waterbased Adhesive 48 – 56 mN/m(Dyne)

PC 34 mN/m(Dyne)

 

ABS 34 mN/m(Dyne)

 

 

DYNE Test pens perform well on most non-absorbent materials. It is important that the test fluid does not change the surface properties of the substrate. For example, if the test fluid penetrates a fiber substrate (such as paper) and causes swelling, the results will indicate unrealistically easy wetting. A chemical reaction between the test fluid and the substrate will completely invalidate the results.

 

To ensure the repeatability of this test, material preparation and testing techniques must be standardized. ASTM Std. The D618² documents suggested conditioning methods. Unfortunately, this standard-treated film is unstable for testing; The conditioning time ranges from 24 to 96 hours. Such stringent controls may be important for R&D, but much shorter conditioning times should be used for general QC testing. Standardization of ambient, substrate, and test solution temperatures is important, as is the inspection method. Have an instructor instruct all testers to reduce variability. relative humidity should not be excessive; Higher RH increases data variability. Finally, the elapsed time between tests for extrusion or coating (or tests for printing, etc.) must be controlled.

 

Surface energy is critically important for many conversion operations. Unfortunately, it is not the sole determinant of product suitability. Other factors such as surface topography, coating rheology, and chemical incompatibilities must also be considered. That's why broad-based communication with vendors and customers is so important. But at least by systematically measuring the substrate surface energy, you'll have a sound starting point from which to solve other problems that may arise.

Testing ProcessImportant Safety Information: The liquids contained in DYNE Test pens are considered hazardous substances.Avoid contact with skin. Use with adequate ventilation. Avoid getting into the eyes.Pregnant women should not get this test done. See product MSDS for more details.The following four points are absolutely essential and must be followed for the results of this test to be meaningful.Do not touch or contaminate the surface to be tested in any way. Dirty surfaces lose their wetness.Do not use contaminated or old DYNE Test pens.Do not test the same spot on a specimen twice; Proceed with the sample, or pull up a new one.Store and use DYNE Test pens at room temperature.1.0 Materials/Equipment Required:dyne Test Pen, Subject Material, Clean, Level Test Area and Thermometer, and Hygrometer2.0 Method2.1 Take out the test specimen. Be sure to make a good sample; Surface aberration causes poor results. for extrudedMovie, a complete web cross-section should suffice. Don't touch the surface.2.2 Place the specimen on a clean, flat surface. Iron the edges, if necessary, to avoid curling or other distortion.2.3 Record the ambient temperature and relative humidity. If the sample temperature is different from ambient, let it beStable.2.4 Test at least three points in the whole sample; ¼, ½ and ¾ in the film section. good practice forTest the outer edges as well. For non-film materials, test locations must be determined in-house.2.5 Determination of moisture2.5.1 Choose a Dyne test pen of a Dyne level that you think is slightly less than the test specimen.2.5.2 Press the applicator tip firmly onto the subject material until the tip is saturated with ink.2.5.3 Use a light touch to drag the pen over the test specimen in two or three parallel passes. defyfirst pass(es); to remove any contamination from the tip, and to ensure that the layer of test fluid is thinEvaluate only the last pass, sufficient for accurate measurement.2.5.4 If the ink strip on the test specimen remains wet for three seconds or longer, repeat steps 2.5.2 and 2.5.3 with the next higher dyne level pen. If the last layer of ink lifts, cracks or shrinks. Repeat steps 2.5.2 and 2.5.3 with the next lower dyne level in the thin line of one second or less. pen. If the ink plaque lasts for one to three seconds before losing its integrity, the pen's dyne level closely matches that of the sample.

 

It is a relatively accurate surface energy measurement technique; Used in standard 2 dyne/cm increments, DYNE Test pens can typically give results with an accuracy of ± 2.0 dyne/cm. Repeated use of the dyne test pen should enable testers to estimate surface energy to within ±1.0 dyne/cm.

 

To investigate discrepancies between the obtained and expected results, a more accurate measurement method should be considered; the Use of DYNE  Technology Surface Tension Test Ink or drawdown rod is recommended. Alternatively, if the results are questionable, repeat the test with a set of unused pens. it is tested

and proven itself on a wide variety of substrates; however, it is theoretically more prone to contamination than some other techniques. For this reason, even in the absence of unexpected results, you should establish a quality assurance plan that requires regular audits during the step-by-step use of the dyne Test Pen. effect of all changes

Transitions from one substrate to another should be monitored especially closely. Slips and other additives bloom on the surface of extruded sheets and films; The transfer of surface-active additives from one material to another can have a profound effect on surface energy measurements. In general, once you demonstrate that the substrate switches from A

Substrate B has no effect, it is relatively safe to assume that a future change from A to B will act similarly.

 

Surface energy is critically important for many conversion operations. Unfortunately, this is not the only determining factor in product suitability. Other factors such as surface topography, coating rheology, chemical incompatibilities, etc. must also be considered. Properly stored and used Dyne Test Pens will give you a good indication of surface energy on many materials, however, you should always verify your results by sample manufacture.

 

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