1、Designation: D6105 04 (Reapproved 2012)Standard Practice forApplication of Electrical Discharge Surface Treatment(Activation) of Plastics for Adhesive Bonding1This standard is issued under the fixed designation D6105; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers various electrical discharge treat-ments to be use
3、d to enhance the 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 variousASTM testmethods or specifications for specific materials.1.2 The types of dischar
4、ge phenomena that 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 r
5、educed pressure 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 di
6、fferent electrical 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 D1868 for “corona discha
7、rge.”1.4 The 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
8、the applica-bility of regulatory limitations prior to use. Specific hazardstatements appear in Section 6.2. Referenced Documents2.1 ASTM Standards:2D724 Test Method for Surface Wettability of Paper (Angle-of-Contact Method)3D907 Terminology of AdhesivesD1868 Test Method for Detection and Measurement
9、 ofPartial Discharge (Corona) Pulses in Evaluation of Insu-lation SystemsD2578 Test Method for Wetting Tension of Polyethyleneand Polypropylene FilmsD2651 Guide for Preparation of Metal Surfaces for Adhe-sive BondingD5946 Test Method for Corona-Treated Polymer FilmsUsing Water Contact Angle Measurem
10、ents3. Terminology3.1 DefinitionsMany terms are defined in TerminologyD907.3.2 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.
11、2.2 contact 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
12、types of 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 Adhesiv
13、esand is the direct responsibility of Subcommittee D14.40 on Adhesives for Plastics.Current edition approved May 1, 2012. Published May 2012. Originallyapproved in 1997. Last previous edition approved in 2004 as D6105 97 (2004).DOI: 10.1520/D6105-04R12.2For referenced ASTM standards, visit the ASTM
14、website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright AS
15、TM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.pressure, the voltage reaches 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 a
16、nd dielectric barrier discharge. In many electricaldischarges, ionized regions called plasma exist.3.2.6 electrical discharge treatment, nactivation of apolymer surface using electrical discharges to increase surfaceenergy and create polar functional groups on the polymersurface; nonequilibrium disc
17、harges are used primarily forsurface treatment.3.2.7 electric arc, na self-sustaining discharge in the gapbetween two electrodes 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,
18、free radicals,metastables and other species; plasmas exist over a wide rangeof temperature and pressure and are capable of inducingchemical 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 thermalequilibri
19、um. Since plasma is usually established by an electricfield, the temperature of the positive ions is usually greater thanthe gas 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
20、curvedelectrode surfaces breaks down at a voltage less than the sparkbreakdown voltage for that gap length.3.2.10 partial discharge, nelectric discharge that onlypartially bridges the insulation between conductors.3.2.11 polarity, nin surface chemistry, value that quanti-fies concentration of polar
21、functional groups on the polymersurface and is measured as a polar component of surfaceenergy divided by a sum of polar and non-polar 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
22、a sudden change in thecurrent.3.2.13 surface energy, nfor a given solid, defines molecu-lar forces of its interaction with other interfaces, J/m2.4. Summary of Practice4.1 This practice identifies and defines several electricaldischarge treatment technologies for surface modification ofpolymers. The
23、 practice outlines essential technical aspects ofeach technology.5. Significance and Use5.1 Bonding of many polymeric substrates presents a prob-lem due to the low wettability of their surfaces and theirchemical inertness. Adhesive bond formation begins with theestablishment of interfacial molecular
24、 contact by wetting.Wettability of a substrate surface depends on its surface energy.The surface activation with electrical discharges improveswettability of polymers and subsequent adhesive bonding. Thesurface activation with electrical discharges results in additionof polar functional groups on th
25、e polymer surface. The higherthe concentration of polar functional groups on the surface themore actively the surface reacts with 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-
26、treated surfaces are ready for application of theadhesive immediately after the treatment.6. Hazards6.1 OzoneOzone is a by-product of the electrical dis-charge in atmospheric-pressure air. The ozone produced duringthe treatment can be vented into external atmosphere wheredilution and subsequent brea
27、kdown will occur. If the ozonecannot be vented out, the station should be equipped with anexhaust hood and activated carbon filter 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 electric
28、al instrumentation and that thesepractices cannot and will not substitute for a practical knowl-edge of the instrument used for a particular surface preparation.6.3 Radio Frequency: WarningPersons with pacemakersmay be affected by the radio frequency.6.4 Electrical discharge treatments produce no vo
29、latile or-ganic compound (VOC) emissions.7. Procedure - General7.1 Surface CleanlinessThe surface must be clean prior tosubmitting the specimen to any of the treatment processes.Potential surface contaminants include the following: addi-tives, handling residue (fingerprints), mold release, machineoi
30、l, and grease.7.1.1 Techniques for Cleaning SurfaceUse a technique forcleaning the surface appropriate for the substrate. If no othercleaning method is specified, use a solvent wipe with isopropylalcohol and clean, low lint cloth or wipes.7.2 Selection of Appropriate Electrical DischargeTreatmentWhe
31、n making a choice the following factors mustbe considered:7.2.1 Necessary treatment level,7.2.2 Treatment speed,7.2.3 Treated parts 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 Surfa
32、ce TreatmentSurfacetreatment with electrical discharges involves, in general, ap-plying the discharge, and the plasma generated in the dis-charge, to the surface to be treated.7.4 Procedure for Determining Effcacy of Treatment:7.4.1 Water Break Test, Guide D2651, Section 5.5.4. Awater-break test is
33、a common method used to analyze surfacecleanliness. This test depends on the observation that a cleansurface (one that is chemically 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
34、 indicates a soiled or contaminated area.D6105 04 (2012)2Distilled water should be used in the test, and a drainage timeof about 30 s should be allowed.7.4.2 Water Contact Angle Determination, Test MethodD724 and Test Method D5946. This is the most precise methodto evaluate surfaces. The contact ang
35、le data can be easily usedfor statistical analysis and statistical process control. Performthe test on enough of the treated area to assess treatmentuniformity.7.4.3 Dyne Solution Method for Wetting TensionThis testmethod is based on Test Method D2578. When applied to othermaterials, or shaped items
36、, it may produce erroneous results.The results from this method are approximations and should beused with caution.7.5 Shelf Life of Treated SurfacesShelf life of treatedpolymers is determined by the treatment level decay from thesurface energy level achieved in the treatment below a prede-termined v
37、alue. Use techniques described in 7.4 to determinethe treatment level decay.7.5.1 In general, surface energy rapidly decreases immedi-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
38、 on the plastic, itsformation, how it was treated, and the ambient environment ofthe storage area. It is recommended to do the adhesive 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) a
39、re generated in a plasma reactor chamber. This is apressure vessel designed to support the pressure/flow condi-tions of the plasma. The 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
40、 common are radio frequency plasmas (13.56 MHz, anFCC assigned frequency) and microwave plasma (2450 Mhz)and less common are lower frequency 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
41、. Electrical Discharge Treatment at AtmosphericPressure9.1 AC Dielectric Barrier DischargeIn the AC dielectricbarrier discharge apparatus the discharge is generated betweentwo electrodes located on opposite sides of the treated surface.One or both electrodes is insulated. The treated part itself can
42、serve as an insulator. There are two types of the AC dielectricbarrier discharge apparatus, the high frequency apparatus andthe suppressed spark apparatus.9.1.1 High Frequency ApparatusThe typical apparatusconsists of a high-frequency power generator and high voltagetransformer(s). Each generator/tr
43、ansformer(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 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 th
44、ey are posi-tioned and continuously moving through the discharge regionbetween the electrodes.9.1.1.4 Larger specimens, such as an automotive 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 sub
45、jected to the discharge from an array ofelectrodes.9.1.1.5 The typical distance between the discharge elec-trode(s) and the treated surface 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
46、/min), and depends on the number ofelectrodes, their geometry and distance to the treated surface.9.1.1.7 High frequency apparatus can be effectively used totreat conductive polymers by using insulated electrodes and thetreated surface as a second electrode.9.1.2 Suppressed Spark ApparatusIn a suppr
47、essed arcapparatus discharge is generated between two insulated elec-trodes maintained at a very high potential of 50 to 60 Hz. Thestrong 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.
48、1 ApparatusA typical suppressed spark apparatushas a tunnel-type treating area with a pair of metal electrodesmounted one against the 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 treat
49、ing 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.9.1.2.4 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 ApparatusAplume of plasma is generatedby blowing air thro
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