1、Designation: D5946 09D5946 17Standard Test Method forCorona-Treated Polymer Films Using Water Contact AngleMeasurements1This standard is issued under the fixed designation D5946; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers measurement of the contact angle of water droplets on corona-treated polymer film sur
3、faces.NOTE 1This test method standard is identical to ISO 15989.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It
4、 is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestab
5、lished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD724 Test Me
6、thod for Surface Wettability of Paper (Angle-of-Contact Method) (Withdrawn 2009)3E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2.2 ISO Standard:4ISO 15989 PlasticsFilm and SheetingMeasurement of Water-Contact Angle of Corona-Treated Films3. Terminol
7、ogy3.1 Definitions of Terms Specific to This Standard:3.1.1 static contact angle, (degrees), nthe angle between the substrate surface and the tangent line drawn to the dropletsurface at the three-phase point, when a liquid drop is resting on a plane solid surface.3.1.1.1 DiscussionContact angle valu
8、es can be determined as follows: (1) by analyzing an image of a droplet using various projection or reflectivedevices and measuring the contact angle directly with a protractor by using tangential alignment of a cursor line or the use ofreference alignment procedures (Test Method D724); or (2) by an
9、alyzing an image of a droplet using various projection orreflective devices and measuring the height and width on the substrate surface to calculate the contact angle as follows:52arctanH/R! (1)where: = contact angle,1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and
10、is the direct responsibility of Subcommittee D20.19 on Film, Sheeting, and MoldedProducts.Current edition approved April 1, 2009May 1, 2017. Published April 2009June 2017. Originally approved in 1996. Last previous edition approved in 20042009 asD5946 - 04.D5946 - 09. DOI: 10.1520/D5946-09.10.1520/D
11、5946-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standa
12、rd is referenced on www.astm.org.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been
13、 made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.
14、*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1H = height of a droplets image, andR = half its width.3.1.1.2 DiscussionInstrumentation is also available that utilizes a
15、n image and directly determines the contact angle based on the calculation shownfor Method (2) of U.S. Patent No. 5,268,733.3.1.1.3 DiscussionMethod (1) may be biased due to the subjective nature of visually finding a tangent to the droplet image at the three-phase point;if Method (1) is to be used,
16、 the bias of each operators measurements shall be determined. Because Method (2) utilizes measureddimensions of the droplet, it would be expected to have less bias. Comparative analyses using these various procedures have notbeen conducted. Therefore, caution is recommended when comparing data obtai
17、ned from these different methods.3.1.1.4 DiscussionMethod (2) may not be applicable in special cases in which the contact angle is greater than 904. Summary of Test Method4.1 In this test method, drops of water are placed on the surface of a film sample, and the contact angle values are measuredand
18、then averaged.5. Significance and Use5.1 The ability of polymer films to retain inks, coatings, adhesives, etc. is primarily dependent on the character of their surfacesand can be improved by one of several surface-treating techniques. The electrical discharge treatment, such as corona treatment,has
19、 been found to increase the wetting tension of a polymer film. The stronger the treatment, the more actively the surface reactswith different polar interfaces. It is therefore possible to relate the contact angle of a polymer film surface to its ability to acceptand retain inks, coatings, adhesives,
20、 etc., if the ink, coating, or adhesive contains the polar functionalities. Contact angle in itselfis not a completely acceptable measure of ink, coating, or adhesive adhesion.5.2 The wetting tension of a polymer film belongs to a group of physical parameters for which no standard of accuracy exists
21、.The wetting tension of a polymer cannot be measured directly because solids do not change shape measurably in reaction to surfaceenergy. Many indirect methods have been proposed.5 Different test methods tend to produce different results on identical samples.Practical determination of a solids surfa
22、ce energy uses this interaction of the solid with test liquids.5.3 Although the level of surface treatment of polymer films has been traditionally defined in the industry in terms of dynes/cm(mN/m), these values are derived from a subjective interpretation of the observed test liquid behavior.5.4 Th
23、e following ranges of water contact angle values can be used as a guide for defining the level of surface treatment ofpolyolefins and many other polymer films with initial low surface energies:5 Wu, S., Polymer Interface and Adhesion, Marcel Dekker, Inc., New York, NY, 1982.D5946 172Marginal or no t
24、reatment 90Low treatment 85 to 90Medium treatment 78 to 84High treatment 71 to 77Very high treatment 715.4.1 The suitability of the test for specification acceptance, manufacturing control, and end use of polymer films will have tobe established through capability studies for each particular film an
25、d treatment.5.5 Almost all materials have variations in contact angle as one moves from point to point. Nonuniform treatment of film withcorona treaters may also add variability to the results. Therefore, multiple measurements are necessary to reflect variation intreatment and surface roughness.6. I
26、nterferences6.1 The wetting tension of a polymer film in contact with a drop of liquid in the presence of air is a function of the surfaceenergies of both the air-film and film-liquid interfaces; any trace of surface-active impurities in the test liquid or on the film mayaffect will potentially effe
27、ct the results. It is therefore important that the portion of the film surface to be tested not be touched orrubbed, that all equipment be scrupulously clean, and that water purity be carefully controlled. Glass apparatus, in particular, islikely to be contaminated with detergents having very low su
28、rface tension, unless specific precautions are taken to ensure theirabsence, such as cleaning with chromic sulfuric acid and rinsing with distilled water.6.2 The presence of slip, antistatic, antiblocking, or other additives can has the potential to change the surface of the film.6.3 Finely embossed
29、 films add more variability to the measurements.6.4 Polymer films often generate static charges when they are processed. Corona treatment usually exacerbates the problems.The film sample for surface measurement may has the potential to carry the static charge generated in processing or may acquirea
30、charge by friction when sliding over the specimen holder surface.6.4.1 The static charges may have the potential to cause errors in contact angle measurements. These errors occur as theelectrostatic field generated by the charged sample pulls the water droplet to the film surface stronger than it wo
31、uld be in theabsence of charges.6.4.2 To prevent measurement errors, the film sample shall be kept free of static buildup before and during measurements byplacing an air ionizer, also known as a static eliminator, in the vicinity of the specimen holder. These devices produce air ions ofpositive and
32、negative polarity. The charged object in the vicinity of the ionizer will attract ions of the opposite polarity and willbe neutralized.6.5 The transfer of a droplet onto the measured surface shall be accomplished following the procedure described in Section 11.An improper transfer technique increase
33、s the variability of measurements.6.6 The contact angle measuring method using tangential alignment of the cursor line of a protractor, as described in 3.1.1.1(1), is biased due to the subjective nature of finding a tangent to the droplet image at the three-phase point. The smaller themeasured conta
34、ct angle, the larger the error. The bias of each operators measurements shall be determined if this method is to beused.7. Apparatus7.1 Contact Angle Meter, or GoniometerThe apparatus for measuring contact angles shall contain the following: (1) a liquiddispenser capable of suspending a precise drop
35、let of the specified volume from the tip of the dispenser, (2) if equipped, with asample holder that can stretch a film sample flat it needs to stretch the film to provide a flat surface without wrinkles and distortions,if unit does not have a sample holder, care needs to be taken to provide a flat
36、surface without wrinkles and distortions, (3)provisions for bringing the sample toward the suspended in contact with the droplet in a controlled manner to accomplish droplettransfer onto the measured surface, and (4) means for projecting a “silhouette” image of the drop with minimal distortions. The
37、apparatus shall have means for direct angle measurements, such as a protractor, or direct measurements of the droplets dimensions,such as a grid or scale, or both, or a suitable charge coupled device sensor and analysis hardware and software appropriate forsubsequent analysis.8. Reagents and Materia
38、ls8.1 Purity of WaterDeionized It is suggested to use deionized ultra filtered water should be used for testing purposes. The testliquid shall be kept in scrupulously clean containers.9. Sampling9.1 The minimum amount of film required for this test is an approximately 25-mm wide and 300-mm long samp
39、le strip. If asample is taken from a roll, the direction of the sample relative to the machine direction of the web shall be noted.9.2 Extreme care shall be taken to prevent the surface of the film sample from being touched or handled in the areas upon whichthe test is to be made.D5946 1739.3 The nu
40、mber of measurements per film sample can be determined using published tables for sampling plans. Complete tablescan be found in most books on quality control. The recommended number of readings per sample is ten.NOTE 2The number of measurements per film sample can be determined using published tabl
41、es for sampling plans. Complete tables can be foundin most books on quality control.69.4 For the purpose of determining the contact angle profile across the width of the roll, one contact angle measurement canbe taken every 25 mm 1 in.(1 in.) across the sample.10. Conditioning10.1 Conditioning is no
42、t generally required for routine quality assurance (QA) or process control measurements sinceconditioning maymeasurements. Conditioning will potentially affect the measured value and misrepresent the actual conditions.10.2 Conditioning is required for interlaboratory measurements intended to compare
43、 the results. Condition the test specimensat 23 6 2C (73.4 6 3.6F) and 50 6 10 % relative humidity for not less than 40 h prior to testing in accordance with ProcedureAof Practice D618 unless otherwise specified by agreement or the relevantASTM material specification. In cases of disagreement,the to
44、lerances shall be 61C (61.8F) and 65 % relative humidity.10.3 Test ConditionsSpecial test conditions are not generally required for routine QA or process control measurements.10.4 Test Conditions for Interlaboratory StudiesConduct tests in the standard laboratory atmosphere of 23 6 2C (73.4 63.6F) a
45、nd 50 6 10 % relative humidity, unless otherwise specified by agreement or the relevant ASTM material specification. Incases of disagreement, the tolerances shall be 61C (61.8F) and 65 % relative humidity.11. Procedure11.1 Place a sample strip onto the specimen holder of the instrument. Make sure th
46、e film sample is lying flat without wrinklesand distortions.11.2 Suspend a 5 to 8-L droplet at the end of a syringe needle. Bring the surface with the mounted sample upward until ittouches the pendant drop. Then lower the surface with the sample to complete the droplet transfer. Do not drop or squir
47、t dropletson the surface. See Fig. 1. Alternatively, the syringe may be lowered to the specimen to release the droplet.11.3 Follow the instrument manufacturers instructions for a maximum time between dropping of the water droplet andmeasurement. Use the measurement techniques listed in 3.1.1.1.11.4
48、Advance the sample to place the next droplet onto a previously untouched area.11.5 Take ten contact angle measurements on the sample.12. Calculation12.1 Calculation:12.1.1 Calculate the average of the ten measurements.12.1.2 Calculate the standard deviation of the measurements.12.1.3 Example:(1) 66
49、(6) 72(2) 72 (7) 72(3) 66 (8) 72(4) 72 (9) 69(5) 73 (10) 69Average contact angle: 70. This result corresponds to the lower end of the very high treatment level. Standard deviation: 2.4.6 Duncan, J. A., Quality Control and Industrial Statistics, 3d Ed., Irwin, Homewood, IL, 1965.FIG. 1 Water Droplet Transfer TechniqueD5946 17413. Report13.1 Report the following information:13.1.1 Instrument used.13.1.2 Number of readings.13.1.3 Average value of the contact angle measurement and standard deviation.13.1.4 Method used for determ
