1、Designation: D 1994 07Standard Test Method forDetermination of Acid Numbers of Hot-Melt Adhesives1This standard is issued under the fixed designation D 1994; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. 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 the determination of acidnumbers of hot-melt adhesives.1.2 This test method is applicable for hot-melt and
3、 hot-melt/acid systems that are soluble under the conditions described.The hot melt must also give light- or medium-colored solutionswhen dissolved. If this is not the case another method must beused.1.3 The values stated in SI units are to be regarded as thestandard. The values in parentheses are f
4、or information only.1.4 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
5、 use. Specific cautionstatements are given in 7.1 and 7.2.2. Referenced Documents2.1 ASTM Standards:2D 907 Terminology of AdhesivesE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsMany of the terms found in this testmethod
6、are defined in Terminology D 907.4. Significance and Use4.1 Acidic hot-melt adhesives are useful in many applica-tions, as the acid functionality can contribute to better substratewetting and better adhesion to polar, nonporous surfaces.4.2 Acidic hot-melt adhesives are also quite corrosive toconven
7、tional iron and steel adhesive application equipment.The acid number determination will tell an equipment manu-facturer if corrosion-resistant equipment for an applicationshould be recommended. The need for corrosion-resistantequipment will vary depending on the acid number of thehot-melt adhesive a
8、nd type of metal that will be bonded.5. Reagents5.1 Potassium Hydrogen PhthalatepH standard, dried andpurified (suitable as an acidimetric standard).5.2 Potassium Hydroxide/Methanol Titrant (0.1 N)Dissolve 6 to7gofpotassium hydroxide (KOH) in methanol,industrial grade, and dilute to 1 L with methano
9、l. This solutionshould be standardized before use (see Section 6).5.3 Phenolphthalein Indicating Solution (2.5 g/L)Dissolve 0.5 g of phenolphthalein in 200 mL of methanol.5.4 TolueneReagent grade.5.5 Deionized Water.6. Calibration and Standardization6.1 Preparation of Standard Acid SolutionDissolve
10、0.25to 0.35 g of potassium hydrogen phthalate in 100 mL ofdeionized water.6.2 Titration of Standard Acid SolutionAdd 2 mL of thephenolphthalein indicating solution and titrate the entire stan-dard acid solution using the methanolic KOH solution preparedin 5.2.6.3 To calculate the normality of the me
11、thanolic KOH, usethe following formula:N KOH 5g of phthalate! 3 1000204.23 mL of KOH solution!5g of phthalatemL of KOH solution3 4.907. Procedure7.1 Dissolve 1.80 to 2.10 g of adhesive in 200 mL oftoluene. (Xylene, reagent grade, may provide a safer alternatesolvent.) Use a thermocouple or thermomet
12、er to monitor thetemperature of the solution, and heat the solution (with stirring)1This test method is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.50 on Hot MeltPressure Sensitive Archive Adhesives.Current edition approved May 1, 200
13、7. Published June 2007. Originallyapproved in 1991. Last previous edition approved in 2000 as D 1994 95 (2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the s
14、tandards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to 80 to 90C (176 to 194F) to accelerate dissolution.(WarningToluene boils at 111C (232F), so monitor thesolution temperature closely a
15、nd do not exceed 90C (194F).)Continue heating and stirring the solution until the sampledissolves in the toluene (15 to 30 min normally).7.2 When the sample is dissolved, turn off the heat andcontinue to stir the solution until it has cooled to 55 to 60C(131 to 140F). (WarningMethanol boils at 65C (
16、149F) sodo not titrate until solution cools to at least 60C (140F).)When the solution has cooled to 55 to 60C titrate immediatelyas in 6.2 until a light pink color remains after 10 s. A whitebackground under the beaker will make the endpoint easier tosee.7.3 If precipitation of the adhesive occurs d
17、uring the titra-tion, reheat the flask.8. Calculation8.1 Calculate the acid number of the sample with thefollowing equation:acid number milligrams KOH/g of sample!5millilitres of KOH solution! 3 KOH normality! 3 56.1grams of adhesive8.2 Duplicate analyses should agree within 65 % of eachother. Dupli
18、cates found to be outside this range suggest at leasta partial insolubility of the adhesive in the solvent or a partialprecipitation of the adhesive during the titration.9. Report9.1 Report the following information:9.1.1 Complete identification of the adhesive used.9.1.2 Conditioning and test condi
19、tions: temperature andrelative humidity.9.1.3 Normality of methanolic KOH.9.1.4 Acid number.10. Precision and Bias10.1 No data currently exists on repeatability or reproduc-ibility for the test method. An interlaboratory study usingPractice E 691 will be conducted to generate data to reviseSection 1
20、0 to bring it into conformance with the Precision andBias section in the ASTM Form and Style Manual.11. Keywords11.1 acid number; hot-melt adhesiveASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users o
21、f this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every fiv
22、e years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical c
23、ommittee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D1994072
