ASTM D6105-97

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Designation: D 6105 – 97
Standard Practice for
Application of Electrical Discharge Surface Treatment
(Activation) of Plastics for Adhesive Bonding
This standard is issued under the fixed designation D 6105; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 907 Terminology of Adhesives
D 1868 Test Method for Detection and Measurement of
1.1 This practice covers various electrical discharge treat-
Partial Discharge (Corona) Pulses in Evaluation of Insu-
ments to be used to enhance the ability of polymeric substrates
lation Systems
to be adhesively bonded. This practice does not include
D 2578 Test Method for Wetting Tension of Polyethylene
additional information on the preparation of test specimens or
and Polypropylene Films
testing conditions as they are covered in the various ASTM test
D 2651 Guide for Preparation of Metal Surfaces for Adhe-
methods or specifications for specific materials.
sive Bonding
1.2 The types of discharge phenomena that are used for
D 5946 Test Method for Corona-Treated Polymer Films
surface modification of polymers fit into the general category
Using Water Contact Angle Measurements
of nonequilibrium or non-thermal discharges in which electron
E 380 Practice for Use of the International System of Units
temperature (mean energy) greatly exceeds the gas tempera-
(SI)
ture.
1.3 The technologies included in this practice are:
3. Terminology
Technology Section
3.1 Definitions—Many terms are defined in Terminology
Gas plasma at reduced pressure 8
Electrical discharges at atmospheric pressure 9
D 907.
AC dielectric barrier discharge 9.1
3.2 Definitions of Terms Specific to This Standard:
High Frequency Apparatus 9.1.1
3.2.1 AC dielectric barrier discharge, n—a self-sustaining
Suppressed Spark Apparatus 9.1.2
Arc Plasma Apparatus 9.2
AC discharge in relatively short gaps with a solid dielectric
Glow Discharge Apparatus 9.3
layer, where the discharge bridges the entire air gap.
NOTE 1—The term “corona treatment” has been applied sometimes in
3.2.2 contact angle, n—the angle in degrees between the
the literature to the different electrical discharge treatment technologies
substrate surface and the tangent line drawn to the droplet
described in Section 9. This practice defines each electrical discharge
surface from the three-phase point.
treatment technology at atmospheric pressure presented in Section 9 and
3.2.3 corona, n—visible partial discharges in gases adjacent
draws the necessary distinctions between them and corona discharge. See
to a conductor.
Test Method D 1868 for “corona discharge.”
3.2.4 corona treatment, n—see Note 1.
1.4 The values stated in SI units, as detailed in Practice
3.2.5 electrical discharge, n—any of several types of elec-
E 380, are to be regarded as the standard.
trical breakdown of gases, primarily air.
1.5 This standard does not purport to address all of the
3.2.5.1 Discussion—The type of discharge depends upon
safety concerns, if any, associated with its use. It is the
several controllable factors, such as electrode geometry, gas
responsibility of the user of this standard to establish appro-
pressure, power supply impedance, etc. When, at atmospheric
priate safety and health practices and determine the applica-
pressure, the voltage reaches a certain critical value, the current
bility of regulatory limitations prior to use. Specific hazard
increases very rapidly and a spark results in the establishment
statements appear in Section 6.
of one of the self-sustaining discharges, such as corona, arc,
glow and dielectric barrier discharge. In many electrical
2. Referenced Documents
discharges, ionized regions called plasma exist.
2.1 ASTM Standards:
3.2.6 electrical discharge treatment, n—activation of a
D 724 Test Method for Surface Wettability of Paper (Angle-
polymer surface using electrical discharges to increase surface
of-Contact Method)
Annual Book of ASTM Standards, Vol 15.06.
1 4
This practice is under the jurisdiction of ASTM Committee D-14 on Adhesives Annual Book of ASTM Standards, Vol 10.01.
and is the direct responsibility of Subcommittee D14.40 on Adhesives for Plastics. Annual Book of ASTM Standards, Vol 08.02.
Current edition approved March 10, 1997. Published February 1998. Annual Book of ASTM Standards, Vol 08.03.
2 7
Annual Book of ASTM Standards, Vol 15.09. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6105
energy and create polar functional groups on the polymer 6. Hazards
surface; nonequilibrium discharges are used primarily for
6.1 Ozone—Ozone is a by-product of the electrical dis-
surface treatment.
charge in atmospheric-pressure air. The ozone produced during
3.2.7 electric arc, n—a self-sustaining discharge in the gap
the treatment can be vented into external atmosphere where
between two electrodes having a low voltage drop and capable
dilution and subsequent breakdown will occur. If the ozone
of supporting large currents.
cannot be vented out, the station should be equipped with an
3.2.8 gas plasma, n—extremely reactive, partially ionized
exhaust hood and activated carbon filter or manganese dioxide
gas consisting of free electrons, positive ions, free radicals,
catalyst.
metastables and other species; plasmas exist over a wide range
6.2 Electrical Hazard: Warning—The users of these prac-
of temperature and pressure and are capable of inducing
tices must be aware that there are inherent dangers associated
chemical modifications on polymer surfaces.
with the use of electrical instrumentation and that these
3.2.8.1 Discussion—The positive ions, the electrons, and
practices cannot and will not substitute for a practical knowl-
the neutral gas atoms of a plasma may or may not be in thermal
edge of the instrument used for a particular surface preparation.
equilibrium. Since plasma is usually established by an electric
6.3 Radio Frequency: Warning—Persons with pacemakers
field, the temperature of the positive ions is usually greater than
may be affected by the radio frequency.
the gas temperature, and the electron temperature may be very
6.4 Electrical discharge treatments produce no volatile or-
high.
ganic compound (VOC) emissions.
3.2.9 glow, n—in electrical discharges, a self-sustaining
discharge in the air gap, where the gas near the sharply curved
7. Procedure - General
electrode surfaces breaks down at a voltage less than the spark
7.1 Surface Cleanliness—The surface must be clean prior to
breakdown voltage for that gap length.
submitting the specimen to any of the treatment processes.
3.2.10 partial discharge, n—electric discharge that only
Potential surface contaminants include the following: addi-
partially bridges the insulation between conductors.
tives, handling residue (fingerprints), mold release, machine
3.2.11 polarity, n—in surface chemistry, value that quanti-
oil, and grease.
fies concentration of polar functional groups on the polymer
7.1.1 Techniques for Cleaning Surface—Use a technique for
surface and is measured as a polar component of surface
cleaning the surface appropriate for the substrate. If no other
energy divided by a sum of polar and non-polar components.
cleaning method is specified, use a solvent wipe with isopropyl
3.2.12 spark breakdown, n—a sudden transition from the
alcohol and clean, low lint cloth or wipes.
“dark” discharge to one of the several forms of self-sustaining
discharge; this transition consists of a sudden change in the 7.2 Selection of Appropriate Electrical Discharge
Treatment—When making a choice the following factors must
current.
be considered:
3.2.13 surface energy, n—for a given solid, defines molecu-
lar forces of its interaction with other interfaces, J/m . 7.2.1 Necessary treatment level,
7.2.2 Treatment speed,
4. Summary of Practice
7.2.3 Treated parts shape and size,
7.2.4 Process type - continuous, batch, etc, and
4.1 This practice identifies and defines several electrical
discharge treatment technologies for surface modification of 7.2.5 Economics.
polymers. The practice outlines essential technical aspects of
Consult the attribute chart in Appendix X1 for comparison.
each technology.
7.3 Procedure for Polymer Surface Treatment—Surface
treatment with electrical discharges involves, in general, ap-
5. Significance and Use
plying the discharge, and the plasma generated in the dis-
charge, to the surface to be treated.
5.1 Bonding of many polymeric substrates presents a prob-
7.4 Procedure for Determining Effıcacy of Treatment:
lem due to the low wettability of their surfaces and their
chemical inertness. Adhesive bond formation begins with the 7.4.1 Water Break Test, Guide D 2651, Section 5.5.4. A
establishment of interfacial molecular contact by wetting. water-break test is a common method used to analyze surface
cleanliness. This test depends on the observation that a clean
Wettability of a substrate surface depends on its surface energy.
The surface activation with electrical discharges improves surface (one that is chemically active or polar) will hold a
continuous film of water, rather than a series of isolated
wettability of polymers and subsequent adhesive bonding. The
surface activation with electrical discharges results in addition droplets. This is known as a water-break-free condition. A
break in the water film indicates a soiled or contaminated area.
of polar functional groups on the polymer surface. The higher
the concentration of polar functional groups on the surface the Distilled water should be used in the test, and a drainage time
of about 30 s should be allowed.
more actively the surface reacts with the different polar
inte
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