1、Designation: D 5725 99 (Reapproved 2003)An American National StandardStandard Test Method forSurface Wettability and Absorbency of Sheeted MaterialsUsing an Automated Contact Angle Tester1This standard is issued under the fixed designation D 5725; the number immediately following the designation ind
2、icates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe property of a liquid to adhere to, o
3、r “wet”, a sheeted surface, or to be absorbed by that surface,or both, is important in many aspects of paper manufacturing and converting, as well as in the end-useapplications of many converted paper products.Examples include, but are not limited to, the absorption of water or other liquid by an ab
4、sorbentstructure (such as an absorbent tissue or wipe); the adhesion of an ink to a polymer film or a coatedor uncoated paper (such as a packaging or wrapping material); the adherence of a polymer film orsizing material to a paper substrate in a laminate or coated structure; the adhesion of a pressu
5、resensitive tape to a release paper; the adhesion of a film to a paper substrate in a composite structure(such as a diaper or other composite structure); and the non-wetting or non-absorbency, or both, of abarrier paper.The wetting or sorptive behavior between a liquid and a particular sheeted subst
6、rate is dependent,at least in part, upon the relationship of the surface energy (tension) of the liquid and the surfaceenergy of the substrate. The theoretical relationship of these energies is complex, and the differentmathematical models which have been proposed for adhesion, wettability, and sorp
7、tion are beyond thescope of this test method, but may be found in standard texts in these areas. In many cases, however,the contact angle of the fluid which will be in contact with the substrate, or the contact angle of a liquidof known surface tension, when placed in contact with a substrate of int
8、erest, is used to understandor predict in-process or end-use results of a particular printing, adhesion, or sorptive application.Contact angle measurements as described in Test Method D 724 or Canadian Pulp and PaperAssociation CPPA F.3H have been used to study and define the printability relationsh
9、ip between an(aqueous) ink and a paper at the water/paper interface. TAPPI T 552 and Test Method D 2578 use asomewhat different, semi-quantitative approach to provide information regarding the energy relation-ship between a polymer film and a nonaqueous liquid, the test end-point being the place whe
10、re thecontact angle between a liquid of known surface tension and the test specimen approaches zero underthe conditions of the test.The procedure presented in this test method is a simple, completely automated approach to contactangle measurement applicable to a wide range of sheeted materials and l
11、iquids where interfacialcontact angles range from near zero to near 180 degrees. The automated procedure shows increasedprecision and greater ease in use than manual procedures.1. Scope1.1 This test method measures the contact angle of a testliquid in contact with a flat specimen of a film or a pape
12、rsubstrate under specified test conditions. This test method maybe used with any liquid of interest which is compatible with theequipment used, particularly with regard to liquid viscosity,tackiness, and vapor pressure (evaporation). This test methodmay be used with any substrate of interest, which
13、can be cut todimensions compatible with the equipment used.1.2 For materials which sorb the test liquid under thespecified test conditions, the rate of change of the contact angleas a function of time may be significant, and may be deter-mined using procedures described in this test method. It is al
14、sopossible to evaluate the sorptive properties of a surface, as the1This test method is under the jurisdiction of ASTM Committee D06 on Paperand Paper Products and is the direct responsibility of Subcommittee D06.92 on TestMethods.Current edition approved March 10, 1999. Published May 1999. Orginall
15、ypublished as D 5725-95. Last previous edition D 5725-97.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.remaining liquid volume on top of the specimen surface ismeasured as a function of time.1.3 The conditions required in this test
16、 method specifyreagent water as the test liquid when testing papers designed tobe absorbent, such as absorbent tissue grades.1.4 Conditions are specified for the testing of a wide rangeof papers considered to be of low absorbance or nonabsorbent,including release papers, sized, coated, or unsized pa
17、persdesigned for printing, writing, wrapping, and similar taskswhere the paper surface interaction with aqueous or solventbased inks or other aqueous or nonaqueous liquids is impor-tant. In such cases, test liquids other than reagent water,including writing and printing inks, or organic liquids ormi
18、xtures of organic liquids may be used as the test liquid uponprior agreement of those involved in the testing, provided theliquid is compatible with the equipment used. Where testliquids other than reagent water are used, the actual liquid usedis reported.1.5 Conditions are also specified for the te
19、sting of polymerfilms, polymer-coated papers, paper laminates, felt, textiles andnon-wovens, using water or other fluids compatible with theequipment and important to the end-use applications of thematerials tested, including gluing and printing.1.6 This standard does not purport to address all of t
20、hesafety 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-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 528 Test Method for Mach
21、ine Direction of Paper andPaperboardD 585 Practice for Sampling and Accepting a Single Lot ofPaper, Paperboard, Fiberboard, and Related ProductD 685 Practice for Conditioning Paper and Paper Productsfor TestingD 724 Test Method for Surface Wettability of Paper(Angle-of Contact Method)D 1193 Specific
22、ation for Reagent WaterD 1968 Terminology Relating to Paper and Paper ProductsD 2578 Test Method for Wetting Tension of Polyethyleneand Polypropylene FilmsD 5039 Test Methods for Identification of Wire Side ofPaperE 122 Practice for Choice of Sample Size to Estimate aMeasure of Quality for a Lot or
23、ProcessE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 TAPPI Standard:T 552 Determination of Wetting Tension of PolyolefinFilms and Coated Surfaces via the Mayer Rod Technique33. Terminology3.1 Definitions: For definitions used in this test method
24、,refer to Terminology D 1968 or the Dictionary of Paper.43.2 Definitions of Terms Specific to This Standard:3.2.1 contact time, nthe length of time the droplet hasbeen in contact with the specimen surface.3.2.2 droplet diameter, n diameter of the surface ofcontact between the specimen surface and th
25、e droplet, shownas distance “D” in Fig. 1.3.2.3 droplet height, nheight of the droplet in contact withthe specimen surface, shown as distance “H” in Fig. 1.3.2.4 drop motion time, nthe time it takes for the dropletto reach the specimen surface after the drop application hasbeen triggered.4. Summary
26、of Test Method4.1 A drop of a specified volume of water or another agreedupon test liquid is applied to a test specimen surface using aliquid delivery system and specified deposition parameters.Images of the drop in contact with the substrate are captured bya video camera at specified time intervals
27、 following deposition.4.2 At a specified time after drop deposition, which is variedbased upon the sorptive or barrier properties of the substrate/liquid interface, the test is terminated. The contact anglebetween the drop and the substrate at various time intervalsfollowing drop deposition are dete
28、rmined by image analysistechniques on the captured images, and the contact angle atspecified time(s), the rate of change of the contact angle changeas a function of time, and changes in droplet height anddiameter, as well as other test variables are analyzed, based onspecific information requirement
29、s for the materials beingtested.4.3 The test method is divided into two parts, Procedures Aand B, which vary only in certain procedural aspects and allowthe use of the procedure over the wide range of sample typesdescribed in the Introduction and Section 1.2For referenced ASTM standards, visit the A
30、STM website, www.astm.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 the Technical Association of the Pulp and Paper Industry(TAPPI), P.O. Box 105113, Atlant
31、a, GA 30348-5113.4Available from TAPPI.NOTE 1For materials exhibiting sorptive properties with respect tothe test liquid used, the values for contact angle, droplet diameter, anddroplet height may vary as a function of time following drop deposition onthe material substrate.FIG. 1 Principle of Measu
32、rementD 5725 99 (2003)24.4 To identify the applicable procedure, a drop of thestandardized size is formed at the tip of the liquid deliverysystem. The drop is then slowly lowered towards the specimensurface until contact is initiated between the liquid and thespecimen. Use Procedure A if the drop re
33、leases immediatelyfrom the tip on contact with the specimen surface. UseProcedure B if the drop remains attached to the tip on contactwith the specimen surface.4.5 In order to measure the highest contact angle possible,the drop should be applied as gently as possible. WithProcedure A, the drop may b
34、e applied with a very short stroke,as the drop will release from the liquid delivery system tipimmediately upon contact with the specimen surface. There-fore, Procedure A should be tried as the first option.4.6 Procedure A gives specific conditions for the testing ofsheeted materials having contact
35、angles with water less thanabout 100. Materials of this type are generally sorbent papers.4.7 Procedure B gives specific conditions for testing ofsheeted materials having contact angles with water above about100. Procedure B is applicable when the drop is not immedi-ately released from the liquid de
36、livery system tip upon contactwith the specimen surface.4.8 In cases where a liquid other than water is used, thespecific procedure applied will depend on the contact anglebetween the liquid and the specimen substrate. For example,where the film side of a paper-film laminate, or a polymer filmitself
37、, is tested with a liquid whose surface tension is approxi-mately equal to or below that of the film, the contact angle atthe liquid/substrate will approach zero, and Procedure A wouldbe used. If the same film were tested with water as the liquid,Procedure B might be appropriate. The procedure is ch
38、osenbased on the resulting interfacial wetting properties, not theidentity of the liquid or specimen substrate.5. Significance and Use5.1 Contact angle measurements may be used to study therelative sorbtive rates of uncoated sorbent papers, or therelative printing or writing characteristics of coate
39、d or sizedprinting and writing papers.5.2 The complex interaction between a liquid and a surfacemay be looked upon as a combination of three differentprocesses of wetting, absorption, and adsorption. Wetting isbest explained with a drop of water on a plastic film. The liquidvolume remains the same,
40、the drop base diameter will increase,and the contact angle will decrease as a function of time. Whenthe liquid volume is reduced as a function of time, the basediameter of the drop is studied. When this diameter remainsconstant, the absorption is dominating. When the drop isspreading across the surf
41、ace (increasing base diameter), theinteraction is based on adsorption.5.3 For sized papers, an increase in feathering is likely asthe rate of change in the contact angle with time increases,indicating a relative increased degree of liquid transport orpenetration (absorption) into the paper.5.4 For s
42、orbent papers, the change in contact angle withtime may be very rapid, with those papers showing the greaterrelative change per unit time having the fastest rate of sorption.5.5 For hard sized papers, little change in contact angle withtime may be seen, and for laminates or polymer coated andbarrier
43、 papers, release papers, or other similar specialty grades,there may be no change in contact angle over the time intervalof a typical test.5.6 It is generally found that papers having contact angleswith water-based inks in the range 90 to 110 work best inprinting and writing applications. Feathering
44、 may be expectedfor contact angles less than 90. Breaks in the flow of ink ontothe paper may occur for contact angles greater than 110.5.7 Because of the wide range of paper coating possibilitiesand ink compositions, further generalizations are difficult.However, contact angle is a precise empirical
45、 tool for use instudying specific liquid/substrate combinations for product andprocess improvements.5.8 In addition, contact angle measurements on films areused to determine printing and gluing characteristics of filmswith specific printing inks or adhesives. In such applications,the procedure may u
46、se a constant film substrate with varioustest liquids of significance to a specific end-use application. Bymeasuring substrate surface free energy and then monitoringand controlling any surface treatment of the material usingcontact angle measurements, improved end-use performance ingluing or printi
47、ng applications is possible.6. Apparatus6.1 Automated Contact Angle Tester5, consisting of thefollowing components, each of which are described in detail: alight source, a video camera, a specimen stage, a liquiddelivery system consisting of a pump and micro-syringe and acomputer and associated soft
48、ware suitable for video imagecapture, image analysis, and reporting.6.1.1 Light Source:6.1.1.1 Halogen Lamp, sealed in a separate lamp housingwith its own ventilating fan. Room temperature air is circulatedinside the lamp housing and the warm air is then returnedoutside the instrument so it cannot r
49、each the test specimen orthe test liquid.6.1.1.2 Other designs are possible, using heat dissipatingfilters or similar equipment to eliminate heating of the speci-men or test liquid.6.1.2 Video Camera:6.1.2.1 The video camera is equipped with a lens to achievean image view of about 10 by 7.5 mm and an electronic shutter.The shutter is set for a 1-ms exposure time for purposes of thistest method.6.1.2.2 The video camera will, depending on the videostandard used, send out video images continuously at a rate of50 (CCIR) or 60 (EIA) images per second. Hence, the timebetween two co
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