1、Designation: D 6105 04Standard Practice forApplication of Electrical Discharge Surface Treatment(Activation) of Plastics for Adhesive Bonding1This standard is issued under the fixed designation D 6105; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 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 practice covers various electrical discharge treat-ments to be used to enhance th
3、e ability of polymeric substratesto be adhesively bonded. This practice does not includeadditional information on the preparation of test specimens ortesting conditions as they are covered in the various ASTM testmethods or specifications for specific materials.1.2 The types of discharge phenomena t
4、hat are used forsurface modification of polymers fit into the general categoryof nonequilibrium or non-thermal discharges in which electrontemperature (mean energy) greatly exceeds the gas tempera-ture.1.3 The technologies included in this practice are:Technology SectionGas plasma at reduced pressur
5、e 8Electrical discharges at atmospheric pressure 9AC dielectric barrier discharge 9.1High Frequency Apparatus 9.1.1Suppressed Spark Apparatus 9.1.2Arc Plasma Apparatus 9.2Glow Discharge Apparatus 9.3NOTE 1The term “corona treatment” has been applied sometimes inthe literature to the different electr
6、ical discharge treatment technologiesdescribed in Section 9. This practice defines each electrical dischargetreatment technology at atmospheric pressure presented in Section 9 anddraws the necessary distinctions between them and corona discharge. SeeTest Method D 1868 for “corona discharge.”1.4 The
7、values stated in SI units are to be regarded as thestandard.1.5 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-b
8、ility of regulatory limitations prior to use. Specific hazardstatements appear in Section 6.2. Referenced Documents2.1 ASTM Standards:2D 724 Test Method for Surface Wettability of Paper (Angle-of-Contact Method)D 907 Terminology of AdhesivesD 1868 Test Method for Detection and Measurement ofPartial
9、Discharge (Corona) Pulses in Evaluation of Insu-lation SystemsD 2578 Test Method for Wetting Tension of Polyethyleneand Polypropylene FilmsD 2651 Guide for Preparation of Metal Surfaces for Adhe-sive BondingD 5946 Test Method for Corona-Treated Polymer FilmsUsing Water Contact Angle Measurements3. T
10、erminology3.1 DefinitionsMany terms are defined in TerminologyD 907.3.2 Definitions of Terms Specific to This Standard:3.2.1 AC dielectric barrier discharge, na self-sustainingAC discharge in relatively short gaps with a solid dielectriclayer, where the discharge bridges the entire air gap.3.2.2 con
11、tact angle, nthe angle in degrees between thesubstrate surface and the tangent line drawn to the dropletsurface from the three-phase point.3.2.3 corona, nvisible partial discharges in gases adjacentto a conductor.3.2.4 corona treatment, nsee Note 1.3.2.5 electrical discharge, nany of several types o
12、f elec-trical breakdown of gases, primarily air.3.2.5.1 DiscussionThe type of discharge depends uponseveral controllable factors, such as electrode geometry, gaspressure, power supply impedance, etc. When, at atmospheric1This practice is under the jurisdiction of ASTM Committee D14 on Adhesivesand i
13、s the direct responsibility of Subcommittee D14.40 on Adhesives for Plastics.Current edition approved April 1, 2004. Published April 2004. Originallyapproved in 1997. Last previous edition approved in 1997 as D 6105 97.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact A
14、STM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.pressure, the voltage reach
15、es a certain critical value, the currentincreases very rapidly and a spark results in the establishmentof one of the self-sustaining discharges, such as corona, arc,glow and dielectric barrier discharge. In many electricaldischarges, ionized regions called plasma exist.3.2.6 electrical discharge tre
16、atment, nactivation of apolymer surface using electrical discharges to increase surfaceenergy and create polar functional groups on the polymersurface; nonequilibrium discharges are used primarily forsurface treatment.3.2.7 electric arc, na self-sustaining discharge in the gapbetween two electrodes
17、having a low voltage drop and capableof supporting large currents.3.2.8 gas plasma, nextremely reactive, partially ionizedgas consisting of free electrons, positive ions, free radicals,metastables and other species; plasmas exist over a wide rangeof temperature and pressure and are capable of induci
18、ngchemical modifications on polymer surfaces.3.2.8.1 DiscussionThe positive ions, the electrons, andthe neutral gas atoms of a plasma may or may not be in thermalequilibrium. Since plasma is usually established by an electricfield, the temperature of the positive ions is usually greater thanthe gas
19、temperature, and the electron temperature may be veryhigh.3.2.9 glow, nin electrical discharges, a self-sustainingdischarge in the air gap, where the gas near the sharply curvedelectrode surfaces breaks down at a voltage less than the sparkbreakdown voltage for that gap length.3.2.10 partial dischar
20、ge, nelectric discharge that onlypartially bridges the insulation between conductors.3.2.11 polarity, nin surface chemistry, value that quanti-fies concentration of polar functional groups on the polymersurface and is measured as a polar component of surfaceenergy divided by a sum of polar and non-p
21、olar components.3.2.12 spark breakdown, na sudden transition from the“dark” discharge to one of the several forms of self-sustainingdischarge; this transition consists of a sudden change in thecurrent.3.2.13 surface energy, nfor a given solid, defines molecu-lar forces of its interaction with other
22、interfaces, J/m2.4. Summary of Practice4.1 This practice identifies and defines several electricaldischarge treatment technologies for surface modification ofpolymers. The practice outlines essential technical aspects ofeach technology.5. Significance and Use5.1 Bonding of many polymeric substrates
23、presents a prob-lem due to the low wettability of their surfaces and theirchemical inertness. Adhesive bond formation begins with theestablishment of interfacial molecular contact by wetting.Wettability of a substrate surface depends on its surface energy.The surface activation with electrical disch
24、arges improveswettability of polymers and subsequent adhesive bonding. Thesurface activation with electrical discharges results in additionof polar functional groups on the polymer surface. The higherthe concentration of polar functional groups on the surface themore actively the surface reacts with
25、 the different polarinterfaces.5.2 To achieve a proper adhesive bond the polyolefinsubstrates polar component should be raised from near zero to15 to 20 mJ/m2.5.3 The pre-treated surfaces are ready for application of theadhesive immediately after the treatment.6. Hazards6.1 OzoneOzone is a by-produc
26、t of the electrical dis-charge in atmospheric-pressure air. The ozone produced duringthe treatment can be vented into external atmosphere wheredilution and subsequent breakdown will occur. If the ozonecannot be vented out, the station should be equipped with anexhaust hood and activated carbon filte
27、r or manganese dioxidecatalyst.6.2 Electrical Hazard: WarningThe users of these prac-tices must be aware that there are inherent dangers associatedwith the use of electrical instrumentation and that thesepractices cannot and will not substitute for a practical knowl-edge of the instrument used for a
28、 particular surface preparation.6.3 Radio Frequency: WarningPersons with pacemakersmay be affected by the radio frequency.6.4 Electrical discharge treatments produce no volatile or-ganic compound (VOC) emissions.7. Procedure - General7.1 Surface CleanlinessThe surface must be clean prior tosubmittin
29、g the specimen to any of the treatment processes.Potential surface contaminants include the following: addi-tives, handling residue (fingerprints), mold release, machineoil, and grease.7.1.1 Techniques for Cleaning SurfaceUse a technique forcleaning the surface appropriate for the substrate. If no o
30、thercleaning method is specified, use a solvent wipe with isopropylalcohol and clean, low lint cloth or wipes.7.2 Selection of Appropriate Electrical DischargeTreatmentWhen making a choice the following factors mustbe considered:7.2.1 Necessary treatment level,7.2.2 Treatment speed,7.2.3 Treated par
31、ts shape and size,7.2.4 Process type - continuous, batch, etc, and7.2.5 Economics.Consult the attribute chart in Appendix X1 for comparison.7.3 Procedure for Polymer Surface TreatmentSurfacetreatment with electrical discharges involves, in general, ap-plying the discharge, and the plasma generated i
32、n the dis-charge, to the surface to be treated.7.4 Procedure for Determining Effcacy of Treatment:7.4.1 Water Break Test, Guide D 2651, Section 5.5.4. Awater-break test is a common method used to analyze surfacecleanliness. This test depends on the observation that a cleansurface (one that is chemic
33、ally active or polar) will hold acontinuous film of water, rather than a series of isolateddroplets. This is known as a water-break-free condition. Abreak in the water film indicates a soiled or contaminated area.D6105042Distilled water should be used in the test, and a drainage timeof about 30 s sh
34、ould be allowed.7.4.2 Water Contact Angle Determination, Test MethodD 724 and Test Method D 5946. This is the most precisemethod to evaluate surfaces. The contact angle data can beeasily used for statistical analysis and statistical processcontrol. Perform the test on enough of the treated area to a
35、ssesstreatment uniformity.7.4.3 Dyne Solution Method for Wetting TensionThis testmethod is based on Test Method D 2578. When applied toother materials, or shaped items, it may produce erroneousresults. The results from this method are approximations andshould be used with caution.7.5 Shelf Life of T
36、reated SurfacesShelf life of treatedpolymers is determined by the treatment level decay from thesurface energy level achieved in the treatment below a prede-termined value. Use techniques described in 7.4 to determinethe treatment level decay.7.5.1 In general, surface energy rapidly decreases immedi
37、-ately after the treatment and then stabilizes at a level which ishigher than the initial surface energy. The treatment shelf liferanges from hours to years, depending on the plastic, itsformation, how it was treated, and the ambient environment ofthe storage area. It is recommended to do the adhesi
38、ve bondingoperation of the treated material soon after treatment.8. Plasma Treatment at Reduced Pressure8.1 Plasmas at reduced pressure 13.3 to 133 Pa (0.1 to 1torr) are generated in a plasma reactor chamber. This is apressure vessel designed to support the pressure/flow condi-tions of the plasma. T
39、he material for processing is placed in thechamber and a necessary degree of vacuum is established. Asource of high-frequency energy is coupled to the reactor. Themost common are radio frequency plasmas (13.56 MHz, anFCC assigned frequency) and microwave plasma (2450 Mhz)and less common are lower fr
40、equency range devices (60 Hzand 20 to 100 kHz). The plasma fills the whole chamber,resulting in a three-dimensional treatment of the objects placedinside the chamber.9. Electrical Discharge Treatment at AtmosphericPressure9.1 AC Dielectric Barrier DischargeIn the AC dielectricbarrier discharge appar
41、atus the discharge is generated betweentwo electrodes located on opposite sides of the treated surface.One or both electrodes is insulated. The treated part itself canserve as an insulator. There are two types of the AC dielectricbarrier discharge apparatus, the high frequency apparatus andthe suppr
42、essed spark apparatus.9.1.1 High Frequency ApparatusThe typical apparatusconsists of a high-frequency power generator and high voltagetransformer(s). Each generator/transformer(s) set is capable ofsupporting multiple discharge electrodes.9.1.1.1 Voltage in the 10 000 to 70 000 V range at 20 to 30kHz
43、 is used.9.1.1.2 The treatment width depends on the size of thedischarge electrode and can range from 1 to 1000 mm andmore.9.1.1.3 Small specimens can be treated as they are posi-tioned and continuously moving through the discharge regionbetween the electrodes.9.1.1.4 Larger specimens, such as an au
44、tomotive bodypanel, can be treated by placing it on an electrode fixture whichis formed in the same shape as the inner surface of the part. Thetreated part is then subjected to the discharge from an array ofelectrodes.9.1.1.5 The typical distance between the discharge elec-trode(s) and the treated s
45、urface ranges between 2 to 50 mm,and depends on the applied voltage and electrode geometry.9.1.1.6 The typical treatment speed ranges from 1.7 to 42 3102m/s (1 to 25 m/min), and depends on the number ofelectrodes, their geometry and distance to the treated surface.9.1.1.7 High frequency apparatus ca
46、n be effectively used totreat conductive polymers by using insulated electrodes and thetreated surface as a second electrode.9.1.2 Suppressed Spark ApparatusIn a suppressed arcapparatus discharge is generated between two insulated elec-trodes maintained at a very high potential of 50 to 60 Hz. Thest
47、rong electrical field in the air gap generates a plasma regionwhile a spark breakdown in the air gap is quenched by adielectric insulation on electrode surfaces.9.1.2.1 ApparatusA typical suppressed spark apparatushas a tunnel-type treating area with a pair of metal electrodesmounted one against the
48、 other on each side of the treatingchamber. The conveyor belt made of a dielectric materialtravels at a slow speed 8.3 to 50 3 103m/s (0.5 to 3 m/min)through the treating area.9.1.2.2 Objects to be treated are placed on the conveyor belt.9.1.2.3 Maximum distance between the electrodes is 400mm.9.1.2
49、.4 The treatment width is determined by the distancebetween the electrodes.9.1.2.5 The potential difference between the two electrodesreaches 200 000 V at 60 Hz. This voltage produces an electricfield capable of breaking a large air gap between the electrodes.The electrodes are covered with insulating layers which helpsuppress the spark formation.9.2 Arc Plasma ApparatusA plume of plasma is generatedby blowing air through an electrical arc between two metalelectrodes. This plume is directed onto the surface to betreated.9.2.1 ApparatusA typical appa
