1、Designation:D 2690 98Standard Test Method forIsophthalic Acid in Alkyd and Polyester Resins1This standard is issued under the fixed designation D 2690;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number
2、 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 gravimetric determinationof the isophthalic acid content of alkyd resins and polyesters.There is no interference fro
3、m styrene monomer or polymer orfrom other dicarboxylic acids except terephthalic acid.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
4、determine the applica-bility of regulatory limitations prior to use.For a specifichazard statement,see Section 7.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water23.Summary of Test Method3.1 The resin is saponified with alcoholic potassium hydrox-ide and benzene to prec
5、ipitate entirely the potassium salt of thephthalic acid isomer.Since the salt contains entrained impuri-ties,it is dissolved in water and diluted to volume.An aliquotportion is acidified under conditions that release the insolubleacid in filterable form.It is then isolated,weighed,andcorrected for i
6、ts slight solubility in water.4.Significance and Use4.1 This test method is used to determine the amount ofisophthalic acid contained in alkyd and polyester resins.Use ofthis test method provides a means whereby the relativeapplicability of the alkyd or polyester resin to the particular enduse may b
7、e estimated by the buyer and the seller.5.Apparatus5.1 Flask and CondenserA 250-mL Erlenmeyer flaskfitted with an air-cooled glass reflux condenser 30 in.(760 mm)in length.The connection between the flask and condensershould be a standard-taper 24/40 ground joint.5.2 Heat Source:5.2.1 Combination Ho
8、t Plate and Magnetic Stirrer,or5.2.2 Heating Mantle and Magnetic Stirrer Base and Bar.5.3 Bchner Funnel,fritted glass,medium porosity,150-mLcapacity.5.4 Volumetric Flask,100-mL volume.5.5 Fritted-Glass Filter Crucible,medium porosity,30-mLcapacity.6.Reagents6.1 Purity of ReagentsReagent grade chemic
9、als shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused,provided it is first ascertained tha
10、t the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedby Type II of Specification D 1193.6.3 Alcohol-Benzene Wash Solution(2
11、+3)Mix absoluteethyl alcohol(Note 1)with benzene in the proportion of 2volumes of alcohol to 3 volumes of benzene.NOTE1The alcohol may be denatured Formula 2-B,but must beanhydrous.6.4 Alcoholic Potassium Hydroxide Solution(0.5 N)Dissolve 33 g of KOH in 1 L of absolute ethyl alcohol(Note1)by reflux
12、or by standing overnight.Protect against carbondioxide absorption.Filter just before use.6.5 Benzene(anhydrous).6.6 Ether(anhydrous).6.7 Hydrochloric Acid(sp gr 1.19)Concentrated hydro-chloric acid(HCl).6.8 Methyl Purple Indicator Solution.7.Hazards7.1 The reagents and samples used in this test meth
13、od may,under some conditions,be hazardous.Refer to the manufac-turers material safety data sheets for specific handling andsafety precautions.Safe laboratory handling procedures and all1This test method is under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings,Materials,and Applic
14、ations and is the direct responsibility ofSubcommittee D01.33 on Polymers and Resins.Current edition approved June 10,1998.Published August 1998.Originallypublished as D 2690 68.Last previous edition D 2690 89(l996)1.2Annual Book of ASTM Standards,Vol 11.01.3Reagent Chemicals,American Chemical Socie
15、ty Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical Society,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaand National Formulary,U.S.Pharmacopeial Convention
16、,Inc.(USPC),Rockville,MD.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMapplicable OSHA regulations are to be followed.8.Procedure8.1 Weigh a portion of resin containing about 400 mg ofisophthalic acid(usually 1 to 3 g of vehicle)into a 250-mLErlenmeyer flask and dissolve in 10 mL of benzene.Add 100mL of freshly filtered 0.5 N alcoholic KOH solution and inserta magnet stirrer bar.Attach the a
