1、Designation: D 2578 04aStandard Test Method forWetting Tension of Polyethylene and Polypropylene Films1This standard is issued under the fixed designation D 2578; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the measurement of the wettingtension of a polyethylene or polypropylene film surface incontact with
3、 drops of specific test solutions in the presence ofair.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bilit
4、y of regulatory limitations prior to use. Specific hazardsstatements are given in Section 8.NOTE 1This test method is equivalent to ISO 8296.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingE 691 Practice for Conducting an Interlaboratory Study toDetermi
5、ne the Precision of a Test Method2.2 ISO Standard:ISO 829633. Summary of Test Method3.1 In this test method drops of a series of mixtures offormamide and ethyl Cellosolve4of gradually increasing sur-face tension are applied to the surface of the polyethylene orpolypropylene film until a mixture is f
6、ound that just wets thefilm surface. The wetting tension of the polyethylene orpolypropylene film surface will be approximated by the surfacetension of this particular mixture.4. Significance and Use4.1 When a drop of liquid rests on the surface of a solid, anda gas is in contact with both, the forc
7、es acting at the interfacesmust balance. These forces can be represented by surfaceenergies acting in the direction of the surfaces and it followsthat:gGL cos u5gGS 2gSL (1)where:u = angle of contact of the edge of the drop with thesolid surface,gGL = surface energy of the gas - liquid interface,gGS
8、 = surface energy of the gas - solid interface, andgSL = surface energy of the solid - liquid interface.4.1.1 The right side of the above equation (the differencebetween the surface energies of the gas - solid and solid -liquid interfaces) is defined as the wetting tension of the solidsurface. It is
9、 not a fundamental property of the surface butdepends on interaction between the solid and a particularenvironment.4.1.2 When the gas is air saturated with vapors of the liquid,gGL will be the surface tension of the liquid. If the angle ofcontact is 0 the liquid is said to just wet the surface of th
10、esolid, and in this particular case (since cos u = 1) the wettingtension of the solid will be equal to the surface tension of theliquid.4.2 The ability of polyethylene and polypropylene films toretain inks, coatings, adhesives, etc., is primarily dependentupon the character of their surfaces, and ca
11、n be improved byone of several surface-treating techniques. These same treatingtechniques have been found to increase the wetting tension ofa polyethylene or a polypropylene film surface in contact withmixtures of formamide and ethyl Cellosolve in the presence ofair. It is therefore possible to rela
12、te the wetting tension of apolyethylene or a polypropylene film surface to its ability toaccept and retain inks, coatings, adhesives, etc. The measuredwetting tension of a specific film surface can only be related toacceptable ink, coating, or adhesive retention through experi-ence. Wetting tension
13、in itself is not a completely acceptablemeasure of ink, coating, or adhesive adhesion.NOTE 2A wetting tension of 35 dynes/cm or higher has beengenerally found to reveal a degree of treatment normally regarded asacceptable for tubular film made from Type 1 polyethylene and intendedfor commercial flex
14、ographic printing. It is, however, possible that someother level of wetting tension may be required to indicate the acceptabilityof polyethylene films made by other processes, or from other types ofpolyethylene, or intended for other uses.1This test method is under the jurisdiction of ASTM Committee
15、 D20 on Plasticsand is the direct responsibility of Subcommittee D20.19 on Film and Sheeting.Current edition approved Aug. 1, 2004. Published August 2004. Originallyapproved in 1967. Last previous edition approved in 2004 as D 2578 - 04.2For referenced ASTM standards, visit the ASTM website, www.ast
16、m.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Registered trade
17、mark of Union Carbide Corp. for ethylene glycol monoethylether.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.At the present date, insufficient experience has been ga
18、ined to state agenerally acceptable level of wetting tension for polypropylene films forcommercial flexographic printing.5. Interferences5.1 Since the wetting tension of a polyethylene or polypro-pylene film in contact with a drop of liquid in the presence ofair is a function of the surface energies
19、 of both the air - film andfilm - liquid interfaces, any trace of surface-active impurities inthe liquid reagents or on the film may affect the results. It is,therefore, important that the portion of the film surface to betested not be touched or rubbed, that all equipment bescrupulously clean, and
20、that reagent purity be carefullyguarded. Glass apparatus in particular is likely to be contami-nated with detergents having very strong surface tensionreducing ability unless specific precautions are taken to ensuretheir absence such as cleaning with chromic-sulfuric acid andrinsing with distilled w
21、ater.6. Apparatus6.1 Cotton-Tipped Wooden Applicators, approximately 150mm 6 in. in length.6.2 Burets, two, 50-mL.6.3 Bottles, 100-mL, with caps and labels.7. Reagents and Materials7.1 Prepare mixtures of reagent grade formamide(HCONH2) and reagent grade ethyl Cellosolve(CH3CH2OCH2CH2OH) in the prop
22、ortions shown in Table 1for the integral values of wetting tension in the range overwhich measurements are to be made. For extremely precisework, mixtures for determining fractional values of wettingtension may be made up by interpolating between the concen-trations shown in Table 1.NOTE 3Although t
23、he mixtures of ethyl Cellosolve and formamideused in this test method are relatively stable, exposure to extremes oftemperature or humidity should be avoided.7.2 If desired, add to each of the formamide ethyl Cello-solve mixtures a very small amount of dye of high tinctorialvalue. The dye used shoul
24、d be of such color as to make dropsor thin films of the solutions clearly visible on the surface ofpolyethylene or polypropylene film and must be of suchchemical composition that it will not measurably affect thewetting tension of the solutions in the concentration used.57.3 Fully prepared mixtures
25、of these reagents in varyingconcentrations are available from a number of commercialsources. Pens containing these mixtures are also commerciallyavailable. However, correlations between these options andfreshly prepared solutions have not been established.NOTE 4Care must be taken when handling pens.
26、 Prolonged exposureto the atmosphere, temperature or humidity extremes, exposure tocontaminants, or use beyond the stated expiration date will change theircharacteristics creating a potential for erroneous results.8. Hazards8.1 Formamide may cause skin irritation and is particularlydangerous in dire
27、ct contact with the eyes. Safety gogglesshould be worn when making up new test mixtures.8.2 Ethyl Cellosolve is a highly flammable solvent.8.3 Both ethyl Cellosolve and formamide are toxic and poseexposure risks. Consult the applicable MSDS before use andensure that the appropriate Personal Protecti
28、ve Equipment(PPE) is used, especially when preparing new solutions.8.4 All tests should be performed with adequate ventilation.9. Sampling9.1 The minimum amount of film required for this testdepends upon the skill of the operator. This usually amounts toone sample across the entire width of a roll i
29、n order to obtaina representative value.9.2 Extreme care must be taken to prevent the surface of thefilm sample from being touched or handled in the areas uponwhich the test is to be made.9.3 Usually it will be adequate to make one determination ateach location14 ,12 ,34 of the way across the width
30、of thefilm, to arrive at an average value for the sample or todetermine when treatment is uneven.10. Conditioning10.1 ConditioningCondition the test specimens at 23 62C 73.4 6 3.6F and 50 6 5 % relative humidity for not lessthan 40 h prior to test in accordance with Procedure A ofPractice D 618, for
31、 those tests where conditioning is required.In cases of disagreement, the tolerances shall be 61C61.8F and 62 % relative humidity.10.2 Test ConditionsConduct tests in the standard labora-tory atmosphere of 23 6 2C 73.4 6 3.6F and 50 6 5%5“DuPont Victoria Pure Blue BO” at a maximum concentration of 0
32、.03 % hasbeen found satisfactory.TABLE 1 Concentration of Ethyl CellosolveFormamideMixtures Used in Measuring Wetting Tension ofPolyethylene and Polypropylene FilmsFormamide,Volume %Ethyl Cellosolve,A%Wetting Tension,Bdynes/cm0 100.0 302.5 97.5 3110.5 89.5 3219.0 81.0 3326.5 73.5 3435.0 65.0 3542.5
33、57.5 3648.5 51.5 3754.0 46.0 3859.0 41.0 3963.5 36.5 4067.5 32.5 4171.5 28.5 4274.7 25.3 4378.0 22.0 4480.3 19.7 4583.0 17.0 4687.0 13.0 4890.7 9.3 5093.7 6.3 5296.5 3.5 5499.0 1.0 56ACellosolve is the registered trademark of Union Carbide Corp. for ethyleneglycol monoethyl ether.BMeasured under con
34、ditions of 23 6 2C and 50 6 5 % relative humidity.D 2578 04a2relative humidity, unless otherwise specified in the test meth-ods or in this specification. In cases of disagreement, thetolerances shall be 61C 61.8F and 62 % relative humid-ity.11. Procedure11.1 Wet the very tip of a cotton applicator w
35、ith one of themixtures. Use only a minimum amount of liquid as an excessof reagent can affect the end point of the test.11.2 Spread the liquid lightly over an area of approximately6.5 cm21 in.2 of the test specimen. Do not try to cover alarger area lest there be insufficient liquid to give completec
36、overage.11.3 Note the time required for the continuous film of liquidformed in 11.2 to break up into droplets. If the continuous filmholds for2sormore, proceed to the next higher surfacetension mixture, but if the continuous film breaks into dropletsin less than 2 s, proceed to the next lower surfac
37、e mixture. Aclean, new cotton applicator must be used each time to avoidcontamination of the solutions (even for successive dips intothe same solution).NOTE 5The solution is considered as wetting the test specimen whenit remains intact as a continuous film of liquid for at least 2 s. The“reading” of
38、 the liquid film behavior should be made in the center of theliquid film. Shrinking of the liquid film about its periphery does notindicate lack of wetting. Breaking of the liquid film into droplets within 2s indicates lack of wetting. Severe peripheral shrinkage may be caused bytoo much liquid bein
39、g placed upon the film surface. Experience with thetest will give excellent insight into “reading” the liquid film behavior.11.4 Proceeding in the direction indicated by the results of11.3, continue repeating 11.1 through 11.3 until it is possible toselect the ethyl Cellosolve-formamide mixture that
40、 comesnearest to wetting the film surface for exactly 2 s. The surfacetension of this mixture in dynes per centimetre is called thewetting tension of the polyethylene or polypropylene filmspecimen.NOTE 6Since the surface tension of the formamide/ethyl cellosolvesolutions can change, for example, thr
41、ough evaporation of one or bothcomponents, or through contamination, and is dependent upon tempera-ture, the actual surface tension of the solution that wet the film for exactly2 s should be measured. This can be accomplished very simply with asurface tensiometer.611.5 Experience with this test has
42、shown that on occasionerroneous wetting tension results can be obtained when thefinal wetting tension is determined by working progressively tolower surface tension mixtures when practicing 11.1-11.4.Itisrecommended that the test analyst should check the reportedwetting tension of the film by workin
43、g progressively to highersurface tension mixtures.12. Report12.1 Report the average value of the wetting tension of eachsample to the nearest 0.5 dynes/cm.12.2 If the polyethylene or polypropylene film has beenunevenly treated, it may not be possible to arrive at a singlevalue of wetting tension. In
44、 this case, report the individualvalues whenever the largest value exceeds the smallest by morethan 1 dyne/cm.13. Precision and Bias713.1 Precision:13.1.1 Table 2 is based on an interlaboratory study con-ducted in 1995 in accordance with Practice E 691 involvingthree materials and thirteen laborator
45、ies. Each test result wasthe average of three individual determinations. Each laboratoryobtained three test results for each material on two days.13.1.2 The values of the repeatability standard deviation Sr,reproducibility standard deviation SR, the 95 % repeatabilityand reproducibility limits on th
46、e difference between two testresults, r and R, respectively, for different treatment levels havebeen determined and are shown in Table 2. The resultsdemonstrate that the precision of the results depends on thetreatment level (wetting tension) of the film, the higher thetreatment level, the higher th
47、e variability between single testresults obtained in different laboratories, or the lower theprecision.13.1.3 Definitions:WarningThe following explanations of r and R are onlyintended to present a meaningful way of considering theapproximate precision of this test method. The data in Table 1should n
48、ot be rigorously applied to the acceptance or rejectionof material, as those data are specific to the interlaboratorystudy and may not be representative of other lots, conditions,materials, or laboratories. Users of this test method shouldapply the principles outlined in Practice E 691 to generate d
49、ataspecific to their laboratory and materials, or between specificlaboratories. The principles 13.1.3-13.2 would then be valid forsuch data.13.1.3.1 Sr= the within laboratory standard deviation for theindividual material. It is obtained by pooling the within-laboratory standard deviations of the test results from all of theparticipating laboratories.13.1.3.2 SR= the between-laboratories reproducibility, ex-pressed as standard deviation.6The Fisher Surface Tensiometer, Model 20, has been found satisfactory for thisapplication.7Supporting data are avail
