ASTM_D_3121_-_94_1999.pdf

Designation:D 3121 94(Reapproved 1999)Standard Test Method forTack of Pressure-Sensitive Adhesives by Rolling Ball1This standard is issued under the fixed designation D 3121;the number immediately following the designation indicates 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.1.Scope1.1 This test method covers measurement of the compara-tive tack of pressure-sensitive adhesives by a rolling ball and ismost appropriate for low-tack adhesives.This test method isonly one of several available for the measurement of tack.1.1.1 This test method is not recommended for the specifi-cation of end use products.1.2 The values stated in inch-pound units are to be regardedas the standard.The values in the parentheses are given forinformation only.1.3 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-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 907 Terminology of Adhesives2E 171 Specification for Standard Atmospheres for Condi-tioning and Testing Flexible Barrier Materials33.Terminology3.1 DefinitionsSeveral terms in this test method are de-fined in accordance with Terminology D 907.3.2 Description of Term Specific to This Standard:3.2.1 tackthe property of an adhesive that enables it toform a bond of measurable strength immediately after adhesiveand adherend are brought into contact under low pressure.4.Summary of Test Method4.1 In the determination of tack by the rolling-ball method,a steel ball is released at the top of an incline,allowed toaccelerate down the incline and roll on to a horizontal surfacecovered with a pressure-sensitive adhesive.Tack is determinedby measuring the distance that the ball travels across theadhesive before stopping.There are two major retarding forcesapplied by the adhesive to the ball:(1)the adhesion betweenthe ball and the adhesive,often called“grab,”and(2)the“plowing effect”or energy required to push the adhesive out ofthe balls path.4.2 Test results are influenced by(1)adhesive film thick-ness,(2)bond of adhesive to backing,and(3)backing rigidity,so these factors must be carefully controlled for satisfactorycomparisons.5.Significance and Use5.1 The rolling-ball tack test is fast,easy to run,and requireslittle investment in equipment and little operator training.Thistest is intended primarily for quality control use since itdemonstrates good reproducibility within a single laboratoryand ability to detect batch-to-batch variations accurately ifadhesive film thickness is held constant.Rolling ball tack is notintended as an investigative tool since for most pressuresensitive adhesive applications rolling ball tack results do notcorrelate well with application tack requirements.6.Apparatus(Fig.1 and Fig.2)6.1 Inclined Troughequipped with a release lever at thetop4through which the ball gains downhill momentum.Theball is a716-in.(11.1-mm)diameter steel ball unless otherwisespecified.7.Test Specimen7.1 The test specimen is a substrate coated with a pressure-sensitive adhesive.It is generally about 2 in.(51 mm)wide andapproximately 15 in.(381 mm)long.Specific sample dimen-sions can be selected for the adhesive to be tested since thelength need only be sufficient to allow the adhesive to stop theball,and the width need be only wide enough to encompass theball track.8.Conditioning8.1 Before test,store the pressure-sensitive adhesive-coatedsubstrate at the selected test conditions for 24 h.If otherconditions are not specified the storage and test conditions shall1This test method is under the jurisdiction of ASTM Committee D-14 onAdhesives and is the direct responsibility of Subcommittee D14.50 on Hot Melt andPressure Sensitive Adhesives.Current edition approved Dec.15,1994.Published February 1995.Originallypublished as D 3121 73.Last previous edition D 3121 89e1.2Annual Book of ASTM Standards,Vol 15.06.3Annual Book of ASTM Standards,Vol 15.09.4A suitable apparatus is available through the Pressure Sensitive Tape Council,The Breeden Co.,104 Wilmot Rd.,Suite 201,Deerfield,IL 60015.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.be 73 6 4F(23 6 2C)and 50 6 5%relative humidity.Details of these and other conditions are more fully describedin Specification E 171.9.Procedure9.1 Select a hard,horizontal surface of sufficient size toconduct the test.Metal or glass plates have been satisfactorilyused.9.2 Prior to the tests of each lot of adhesive,clean theinclined trough thoroughly with a suitable solvent.Heptane,methyl ethyl ketone,isopropanol,toluene,or methanol areusually satisfactory.9.3 Arrange the specimen to be tested,adhesive side up,inline with the incl