1、Designation: D 4441 04Standard Specification forAqueous Dispersions of Polytetrafluoroethylene1This standard is issued under the fixed designation D 4441; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 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 specification covers aqueous dispersions of poly-tetrafluoroethylene (PTFE) resins. These resins are homopoly-mers of tetrafluo
3、roethylene, or in some cases modified ho-mopolymers containing not more than 1 % by weight of otherfluoromonomers.1.1.1 The dispersion is usually stabilized by one or moresurfactants. Other non-PTFE materials may be present in totalat 5 % or less by weight for special purposes.1.1.2 This specificati
4、on is for virgin material only and doesnot address recycled material as it is not appropriate fordispersions.1.2 This specification is used to determine if a shipment, lot,or container of PTFE dispersion is suitable for its intended use.It covers only aqueous dispersions of polytetrafluoroethylene.I
5、t does not cover PTFE copolymers or filled dispersions. Thisspecification includes test methods for both aqueous dispersionand the PTFE in the dispersion.NOTE 1Uses for the PTFE dispersion covered by this specificationinclude, but are not limited to, casting of their films, impregnation ofmechanical
6、 packings and other materials, surface coatings on varioussubstrates, combined impregnation and coating of fibrous materials, andco-coagulation with other materials for subsequent processing into films,sheets, rods, and tubes.NOTE 2Information in this specification is technically equivalent torelate
7、d information in ISO 12086-1 and ISO 12086-2.1.3 The values stated in SI units as detailed in IEEE/ASTMSI-10 are to be regarded as standard. The values given inbrackets are for information only.1.4 The following precautionary caveat pertains only to thetest method portions of this specification. Thi
8、s standard doesnot purport to address all of the safety concerns, if any,associated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations priorto use. Specific precautionary inf
9、ormation is given in Notes 5and 6.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 3892 Practice for Packaging/Packing of PlasticsD 4464 Test Method for Particle Size Distribution of Cata-lytic Material by Laser Light ScatteringD 4591 Test Method for Determining Tem
10、peratures andHeats of Transitions of Fluoropolymers by DifferentialScanning CalorimetryD 4894 Specification for Polytetrafluoroethylene (PTFE)Granular Molding and Ram Extrusion Materials3D 4895 Specification for Polytetrafluoroethylene (PTFE)Resins Produced from Dispersion3E 70 Test Method for pH of
11、 Aqueous Solutions with theGlass ElectrodeIEEE/ASTM SI-10 Use of the International System of Units(SI): The Modern Metric System2.2 ISO Standards:4ISO 12086-1 Plastics Fluoropolymer Dispersions andMolding and Extrusion MaterialsPart 1: Designationand SpecificationISO 12086-2 Plastics Fluoropolymer D
12、ispersions andMolding and Extrusion MaterialsPart 2: Preparation ofTest Specimens and Determination of Properties3. Terminology3.1 Definitions:3.1.1 GeneralThe terminology given in TerminologyD 883 is applicable to this specification.3.2 Definitions of Terms Specific to This Standard:3.2.1 dispersio
13、n, na two phase system of which one phaseconsists of finely divided particles distributed throughout abulk substance, the particles being the disperse phase and thebulk phase being the continuous phase.1This specification is under the jurisdiction of ASTM Committee D20 onPlastics and is the direct r
14、esponsibility of Subcommittee D20.15 on ThermoplasticMaterials (Section D20.15.12).Current edition approved June 1, 2004. Published June 2004. Originallyapproved in 1984. Last previous edition approved in 1998 as D 4441 - 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon
15、tact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Specifications for other forms of polytetrafluoroethylene may be found inSpecifications D 4894 and D 4895.4Available from American Nati
16、onal Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*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.3.2.2 dispersion particle sizea particle
17、size measured inthe presence of added surfactant.3.2.3 raw dispersion particle sizea particle size measuredin the absence of added surfactant (except for the small amountused in polymerization).3.2.4 lot, none production run or a uniform blend of twoor more production runs.3.2.5 sintering, nas it ap
18、plies to PTFE, a thermal treat-ment during which the PTFE is melted and recrystallized bycooling with coalescence occurring during the treatment.3.2.6 standard specific gravity (SSG), nthe specific grav-ity of a specimen of PTFE material molded as described in thisspecification and sintered using th
19、e appropriate sinteringschedule given in this specification.4. Classification4.1 This specification covers four types of virgin PTFEdispersions classified into those equal to or below 40 % PTFEand those above 40 % PTFE, and those containing addedsurfactant and those not containing added surfactant.
20、Thedispersions are classified into 13 grades depending on the levelof added surfactant. Three classes of Surfactant ToleranceLevel are provided to further differentiate the dispersionvariability needed.NOTE 3The surfactant content is weight percent and is based on thesolid, dry PTFE.4.2 A line callo
21、ut system is used to specify materials in thisspecification. The system uses predefined cells to refer tospecific aspects of this specification, illustrated as follows:SpecificationStandard Number Block:Type Grade ClassSpecialNotesExample: Specification D 4441 - XX, II 3 AFor this example, the line
22、callout would be Specification D4441 XX, II3A and would specify a virgin PTFE dispersionthat has all the properties listed for that type, grade, and classin the appropriate specified tables. A comma is used as theseparator between the standard number and the type and class.Separators are not needed
23、between the type, grade, and class.5Provision for special notes is included so that other informationcan be provided when required.5. Ordering Information5.1 Orders for material under this specification shall containthe following information:5.1.1 Quantity, Grade, Class,5.1.2 Name of material (Aqueo
24、us dispersion of PTFE),5.1.3 ASTM designation and year,5.1.4 Type,5.1.5 Additions to the specification and supplementary re-quirements, if required.6. Other Requirements6.1 SignificanceIn addition to tests on the dispersion andthe polymer, the following requirements apply:6.2 The dispersion shall be
25、 free of contamination, dirt,mold, etc. It shall be of uniform composition. The expectedlevel of coagulated polymer shall be specified.7. Sampling7.1 PTFE solids in the dispersion tend to settle uponstanding. Therefore, the dispersion shall be homogenized bygentle mixing before sampling. Gentle mixi
26、ng includes rollinga drum for 5 min at 3 to 4 rpm, by stirring with a smooth rodfor 3- to 4-min, or by other types of gentle agitation.WarningVigorous agitation will coagulate the dispersion.7.2 After blending, take the sample by removing an aliquot.A suitable method is by inserting a clean, smooth,
27、 dry glasstube, open at both ends, until it reaches the bottom of thecontainer. An internal diameter of 6 or 7 mm 0.25 in. issuitable. Smooth the ends of the tube to prevent injury. Closethe upper end of the tube, remove the tube from the container,and transfer the contents to a clean dry glass jar.
28、 Repeat untilthe desired sample size is reached.7.3 When samples are drawn from several containers, theindividual samples shall be combined and thoroughly mixed bygentle stirring when the samples are combined and againbefore the combined sample is tested.8. Test Methods for Dispersions8.1 ScopeThe s
29、pecification contains test methods to de-fine characteristics of the polymer and of the dispersion of thepolymer. This section defines tests on the dispersion of thepolymer.8.2 pH ValueThe test method shall be in accordance withTest Method E 70. Some buyers or sellers attach importance tothe pH of t
30、he PTFE dispersion. The pH value is not specifiedin this ASTM Standard.NOTE 4If the PTFE dispersion coats the electrode, clean the electrodethoroughly using a soft cloth wet with either toluene or concentratedsurfactant.65See the ASTM Form and Style Manual available from ASTM Headquarters.6Examples
31、of a suitable surfactant are “Glim” detergent, B. J. Babbitt, Inc.,“Joy” detergent, Proctor and Gamble, Inc., and “Triton” X-100, Rohm and Haas Co.TABLE 1 PTFE Level, Surfactant Level, and Tolerance LevelRequirementsType % PTFE GradeNominal %Added SurfactantClassSurfactantToleranceLevelI #40 0 040 2
32、 $240 with 0 % addedsurfactant9 $91010 $101111 $111212 $1213D 4441 042NOTE 5Warning: Toluene is hazardous. Consult appropriate safetyinformation on the material Safety Data Sheet before using.8.3 Solid Content and Surfactant Content by GravimetricWeight Loss:8.3.1 SignificanceDetermine the percent P
33、TFE solids andthe percent surfactant by successive evaporations of water andsurfactant. The percent surfactant is based on the weight of thePTFE. All percentages are based on weight.8.3.2 ApparatusAn aluminum weighing dish, an ovencapable of reaching 120 6 5C 248 6 9F, and an ovencapable of reaching
34、 380 6 10C 716 6 18F. Balance ca-pable of weighing down to 0.0001 g.8.3.3 ProcedureWeigh the aluminum weighing dish to0.0001 g (WA). Add 10 g of PTFE dispersion and weighimmediately to 0.0001 g (WB). Dry the sample for2hat120 6 5C. Weigh the sample to 0.0001 g (WC) after cooling toroom temperature i
35、n a desiccator. After weighing, evaporatethe surfactant by placing the sample in an oven at 380 6 5C716 6 9F for 35 6 1 min. Allow the sample to cool in adesiccator to room temperature and weigh to 0.0001 g (WD).8.3.4 CalculationsFor surfactants that are completelyvolatile use the following:PTFE, %5
36、WD2WA!WB2WA!3100surfactant, %5WC2WD!WD2WA!31008.3.4.1 For surfactants that are not completely volatile usethe following:PTFE, %5WC2WA!2WC2WD!311k!#WB2WA!3100surfactant, %5WC2WD!311k!WC2WA!2WC2WD!311k!#3100where:k = weight of nonvolatile portion of the surfactant/weightof volatile portion of the surf
37、actant.NOTE 6Upon request, the supplier shall inform the user whether thesurfactant can be completely removed by the procedures of this specifi-cation; and if not, shall define the surfactant or the volatile and nonvolatileportions of the surfactant.8.3.5 Precision and BiasNo information can be pres
38、entedon the precision and bias because of insufficient participation inthe investigation.8.3.6 The results of these tests on solids contents andsurfactant shall conform to one of the types of dispersion listedin 4.1.8.4 Solids Content by Hydrometer:8.4.1 SignificanceAn approximate solids content in
39、adispersion is commonly determined from the specific gravity ofthe dispersion. The hydrometer reading is a function of thesolids content, the surfactant content, and other parameters ofthe dispersion. Therefore, any single conversion table hasinherent error and cannot be universally applicable. A ta
40、bleshould be obtained from the supplier.8.4.2 ApparatusA hydrometer or set of hydrometers ca-pable of measuring specific gravity from 1.000 to 1.500.Accuracy of the hydrometer shall be 60.001. A graduatedcylinder large enough to hold the hydrometer.8.4.3 ProcedureFill the graduated cylinder with PTF
41、Edispersion to float the hydrometer. Place the hydrometer intothe cylinder. Add dispersion until the cylinder is full and themeniscus is slightly convex. Read the hydrometer at the top ofthe dispersion. The reading shall be accurate to 0.001. Trans-late the hydrometer reading to solids content using
42、 the table.8.4.4 Precision and BiasNo information can be presentedon the precision and bias because of insufficient participation inthe investigation.NOTE 7Some of the additives permitted in accordance with 1.1.1 mayincrease the viscosity of the dispersion so much that it is unlikely that thehydrome
43、ter procedure will be used to determine the density in a reliablemanner.8.5 Test for Coagulated Polymer:8.5.1 SignificancePolymer that has coagulated may not beuseful to the purchaser. This test will determine the percent ofcoagulated polymer.8.5.2 ApparatusA tared beaker to hold 1000 6 1gofdispersi
44、on; a filter screen, 80 mesh; a funnel, an oven capableof operating at 120 6 5C 248 6 9F desiccator; balancecapable of 1 mg.8.5.3 MaterialsDistilled water PTFE dispersion.8.5.4 ProcedureWeigh a 1000 6 1 g of dispersion (WD)into the tared beaker. Weigh the screen to 1.0 mg and record theweight (WS).
45、Secure the screen to the funnel and filter thedispersion through the screen. Rinse the beaker with 25 mL ofdistilled water and use this rinse water to wash the coagulumon the screen. Gently wash the coagulated polymer on thescreen with 25 mL of distilled water from a wash bottle.Carefully remove the
46、 screen from the funnel and dry at120 6 5C 248 6 9F for 2 h. Weigh the screen and coagu-lum to 1 mg after allowing it to cool to room temperature in adesiccator. Record the weight as WC.8.5.5 CalculationCalculate the coagulum content as fol-lows:coagulum content, %5WC2WS!WD3PTFE content, %!3100where
47、:WD= mass of dispersion sample, g,WS= mass of screen, g,WC= mass of screen and coagulated polymer, g, and PTFEcontent, %, = PTFE, % in the dispersion as deter-mined in 8.3. It is to be expressed as a decimalfraction.9. Methods for Tests on PTFE in the Dispersion9.1 ScopeThe specification contains te
48、st methods to de-fine characteristics for the dispersion and for the PTFE in thedispersion. This section specifies tests that will define thesolids in the dispersion to be PTFE and to characterize thePTFE.9.2 Standard Specific GravityThe test method for stan-dard specific gravity is the same as give
49、n in SpecificationD 4895. However, it is necessary to remove all of the surfactantbefore sintering in order to obtain meaningful results.D 4441 0439.2.1 ApparatusA 475-mL 16-oz widemouth bottle withsealable top. A 5-in. Buchner funnel; 100-mL graduate cylin-der, watchglass or aluminum pan. A vacuum oven capable ofoperating at 150C 362F and an absolute pressure of 48 mm1.9 in. of mercury (26 in. of water); desiccator, balance.9.2.2 MaterialsMethanol, acetone, cheesecloth, PTFEdispersion, and
