March, 2001
3
Technical Bulletin
3MTM VHBTM Durability
Durability of 3M™VHB™Tapes
SummaryThis bulletin addresses the long-term durability of VHB™ Acrylic Foam and
Adhesive Transfer Tape products and their ability to perform in certain types of
demanding environments. This will be addressed from a variety of vie w-points
including chemical composition, resistance to harsh environments, 3M and
independent tests f or product durability, and certain applications where VHB™ Tape
products have demonstrated excellent ability to perform in demanding applications.
Test results on moisture resistance, UL durability, accelerated weathering, outdoor
weathering, thermal cycling and fatigue resistance will be discussed.
Composition 3M has been a technological leader in acrylate pressure sensiti ve adhesive (PSA)
technology for over 35 years. The VHB™ Acrylic Foam and Adhesi ve Transfer Tapes
represent examples of 3M’s proprietary state-of-the-art in this durable c hemistry. The
long-term aging resistance lies in the polymer comprising VHB ™Adhesive Transfer
and Foam Tapes. The chemical bonds that make up the polymer chains consist of
carbon-carbon single bonds that are highly resistant to energy in the form of heat or
ultraviolet light, as well as chemical attack. In less durable foams or adhesives, such
conditions could lead to cleaving of the polymer backbone and thus a weakening of
mechanical properties. In the case of acrylic adhesives and foams, ho wever,
additional crosslinking is chemically favored over chain scission (cleavage). This
means that, rather than under going a process of decomposition, the acrylate materials
will tend to build modulus very slightly over extended exposures. This translates to a
stronger, long lasting bond.
Durability Testing Temperature Exposure
Because of the demanding and di verse applications users have for VHB™ tapes,
durability has always been a key interest in the performance of these products. One of
the first issues for tapes is retention of tack and adhesion after exposure to elevated
temperatures. The VHB™Adhesive Transfer Tape F-9473PC yielded 92% retention
of peel adhesion after the roll was aged for more than 5 years at 150°F (65°C). The
initial tack and liner release properties were still excellent. The difference in peel
values suggests that a roll of this tape is relatively unaf fected by long-term exposure
to ele vated temperatures. Bonds made with VHB™ Tapes can tolerate periodic, short-
term exposures to temperatures up to 300°F (150°C) for most Foam Tapes and 500°F
(260°C) for Adhesive Transfer Tapes.
Technical Bulletin
3MTM VHBTM Tape Durability
Accelerated
Weathering Certain other accelerated aging tests have been conducted in weatherometers which
subject a bond to heat, humidity and concentrated ultraviolet light exposure. These
tests were performed in dynamic shear by making a stainless steel overlap bond with
VHB™ tape 4950 and then subjecting the samples to c ycling heat, humidity and
carbon and arc lamp exposure. Small samples provided an increased amount of edge
exposure to UV radiation. Figure 1 indicates that the bond strength does not
deteriorate belo w its original performance level, even after exposure of 7000 hours in
the weatherometer under these tests.
200
150
100
50
002000 4000 7000
Figure 1
Weatherometer Testing of 4950 VHB Tape
Hours of Exposure
% Strength Retention
Outdoor Weathering Outdoor weathering decks in Arizona, Florida and other locations around the world
are also used to collect data on the long-term performance of the VHB™ tape family.
These tests typically demonstrate about 100% bond strength retention in certain
VHB™ Tapes after 2 to 5 years aging cycles in the hot, humid climate of Florida, the
hot, dry and very sunny climate of Arizona and the cold to hot extremes of Minnesota
on bonds to aluminum, glass, PVC and painted metal. Figure 2 sho ws the constant
performance of VHB™ tapes 4950, 4951 and 4952 after 5 years of outdoor aging in
Minnesota. Similar results have been obtained in 5 year tests conducted in Japan on
the VHB™ tapes.
150
100
50
0
Figure 2
VHB™ Tape (5 Year Outdoor Aging, Minnesota)
% Strength Retention: Tensile
0 Yr
1 Yr
2 Yr
5 Yr
4950 4951 4952
VHB™ Tape
- 2 -
Technical Bulletin
3MTM VHBTM Tape Durability
UL Listing and
Durability Testing Both transfer tape and foam representatives of the VHB™ Tape family have UL
746C listings which involve stringent qualif ication tests and periodic monitoring by
Underwriter’s Laboratories. Qualif ication for this listing requires high-strength retention
after extended e xposure to high temperatures, humidity, cold, and cyclic conditions.
The table below details VHB™ Tapes with the UL 746C listing, and substrate
combinations, as well as the maximum listed temperature for each combination.
Moisture and
Solvent Resistance Adhesion tests have been performed on VHB™ Tape 4945 bonds of aluminum to
aluminum that were subjected to o ver 10 years of submersion in 5% salt water and
ordinary tap water. After testing, bright clean aluminum surfaces were observed
underneath the adhesive bond. A combination of adhesi ve and cohesive failure modes
were observed when the bond was broken which indicated very high performance
levels. Long-term exposure to high humidity or water submersion can have the effect of
making a polymer more resilient and tolerant of high elongation. A subsequent lowering
in peak force is also measured after many days of exposure, usually on the order of
40%. This ef fect is typical as it parallels the increase in resilience and is the same tr end
often seen with structural silicone materials which are also recognized for their
durability. Drying of the VHB™ Tape bond , which occurs in a normal environmental
cycle, will show that this effect is reversible and that the bond will return to the original
dry strength.
After splashes or incidental contact with solvents such as fuels, alcohols, adhesive
removers like MEK, and e ven weak acids or bases, no affect is measured on the bond
performance. Only after continuous submersion in harsh fuels or solvents is softening
of the adhesi ve/foam experienced. Note: While VHB™ Tape products may withstand
occasional contact with these types of chemicals, continuous exposure is not
recommended.
110°C
90°C
75°C
Product Families Substrates Temp Rating
VHB™ Foam Tapes
4950, 4930, 4920 Aluminum, Stainless Steel, Galvanized Steel,
Enameled Steel, Glass/Epoxy, Ceramic
PBT
Polycarbonate, ABS, unplasticized PVC
Conformable VHB™
Foam Tapes 4956,
4941, 4936, 4926
Ceramic
Aluminum, Stainless Steel, Galvanized Steel,
Enameled Steel, Polycarbonate, unplasticized
PVC, Glass/Epoxy, PBT
ABS
110°C
90°C
75°C
VHB™ Foam Tape
4945 Phenolic, Aluminum, Galvanized Steel, Alkyd
Enamel
Polyamide (Nylon), Polycarbonate, ABS
Unplasticized PVC
110°C
90°C
75°C
VHB™ Adhesive
Transfer Tapes
F-9473PC,
F-9469PC,
F-9460PC
Stainless, Steel, Glass/Epoxy, Enameled
Steel, Ceramic, Phenolic; Nickel Plated Steel
(9469 only)
ABS, Polycarbonate, Aluminum Galvanized
Steel
Unplasticized PVC
110°C
90°C
75°C
3M™ VHB™ Tapes
UL746C Listings - File MH 17478
Category QOQW2 Component - P olymeric Adhesive Systems, Electrical Equipment
- 3 -
Technical Bulletin
3MTM VHBTM Tape Durability
15
10
5
0
Figure 3
MIL STD 883 Exposure Tests
VHB™ Tape F-9460 PC: Polyimide to Aluminum
Peel Adhesion (lbs/inch)
Control: 72 hr RT 1000 @ 90°F/90% RH 1000 T. Shock 1000 @ 150°C
*Thermal shock: -50°C to 150°C hourly
Exposure Time (hours) and Condition
Clarity Since the introduction of the clear VHB™ Acrylic Tapes 4910 and 4905, the
additional issue of long-ter m clarity and appearance consistency is commonly asked.
Tests have been run for 3000 hours in an accelerated weathering machine which
exposes bonds to high temperatures and intense ultraviolet (UV) light. To measure
clarity, 3 mm float glass plates were bonded together with VHB™ Tape 4910, the
0.040" thick transparent VHB™ Tape. The percent transmittance was monitored
periodically during the exposure cycle, beginning at 88.2% and f inishing a t 87.3%.
After this long, harsh exposure, only a 1% change in transmittance was observed. In
high humidity environments, however, the VHB™ Tapes 4910 and 4905 may take on
a hazy appearance due to slight absorption of water molecules. Because the same
acrylic polymers are used throughout the VHB™ Tape family, these results suggest
inherent stability of the w hole family.
Thermal ShockThe VHB™ Tapes have also performed well in tests, similar to MILSTD 883, which
are commonly used to qualify durable products for the electronics industry. Under
this testing, protocol bonds are subjected to 1000 hours at 150°C, 1000 hours at 85°C
and 85% relative humidity, and 1000 hours of thermal shock which cycles hourly
from -50°C to 150°C. Figure 3 sho ws the e xcellent performance of the VHB™
Adhesive Transfer Tape F-9460PC in similar testing which involved bonding
polyimide to aluminum. Typically the bond strength increases with time due to the
high performance PSA’s more complete wet out of the surfaces.
Fatigue Another durability issue is f atigue resistance. Many types of adhesi ve tests are run in
a short-term peel, shear or tensile mode where the sample is broken in a matter of a
few seconds. These tests are convenient for quick characterization of the peak force
holding capability, but do not of fer any information about a product’s ability to
tolerate vibration or repetitive strains. Because users have used VHB™ Tapes in
many applications which require fatigue resistance, such as trucks or tr ailers, signs
and building panels, a test has been designed by 3M to characterize this property.
- 4 -
Application Examples
of Durability While positive test results are always encouraging, some of the best examples of
VHB™ Tape’s durability are existing applications in the field. VHB™Adhesive
Transfer Tapes have been used since the mid 1970’s and VHB™ Acrylic F oam Tapes
have applications dating back to 1980.
One of the oldest and most visible applications for the VHB™ Foam Tapes is on
ambulance bodies. The aluminum panels comprising the body of an ambulance can
be bonded onto the frame with VHB™ Tape. These applications require durability in
harsh conditions on rugged vehicles that are in service f or man y years.
Another example of durable applications with excellent performance have been
curtain wall constructions such as the Singapore Treasury Building. Here the exterior
panels are stif fened against wind loads by attaching unseen stiffeners to the inner
surface. These bonds must sustain wind loads, daily thermal expansion and
contraction cycles, and elevated temperatures. Similar curtain wall and facade
applications e xist around the w orld. Architectural signs and traffic signs using
VHB™ Tapes have also been standing up to constant weathering, buffering winds,
and occasional storms since the early 1980’s.
Technical Bulletin
3MTM VHBTM Tape Durability
106
105
104
103
102
Figure 4
Dynamic Tension Fatigue VHB™ Tape 4950
Load (PSI)
Cycles to Failure
15 25 35 45 55 65
Fatigue
(continued) In a constant stress machine, tension samples were cyclically loaded over a range of
stresses. The loads were chosen so that bond failures would occur over a broad range
of times. As the load decreases, the specimens will survive more and more cycles and
this trend can be plotted semi-log as in Figure 4. The semi-log plot yields a straight
line which can be used to help predict longer term performance at lower stresses not
practical to measure. Given a product lifetime estimate for cyclic loading, the data can
be extrapolated to estimate the maximum tolerable design stress. F or Acrylic F oam
Tapes, this is typically about 20 psi for one million cycles of full reversal loading.
VHB™ Tapes tend to perform well in these types of tests because of their inherent
viscoelasticity. The acrylic foam and adhesive absorb energy and relax stresses
internally, thus helping protect the adhesive bond on the substrate.
- 5 -
Technical Bulletin
3MTM VHBTM Tape Durability
3
Bonding Systems Division
3M Center, Building 220-7E-01
St. Paul, MN 55144-1000 Printed in U.S.A.
©3M IPC 2000 70-0709-3862-9
Recycle, Neg
Recycled Paper
40% pre-consumer
10% post-consumer
3M warrants for 24 months from the date of sales or delivery, whichever occurs first, that 3M brand VHB™ Tape will
be free of def ects in material and manufacture. 3M MAKES NO OTHER WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE. This Limited Warranty does not cover damage resulting from the use or inability to use
3M brand VHB™ Tape due to misuse, workmanship in application, or application or storage not in accordance with
3M recommended procedures.
Limited
Warranty
Application
Examples of
Durability
(continued)
Another example of VHB™ Tape durability has been generated at the Bendix Automotive
Proving Grounds in Indiana. A full size semi-truck with sleeper cab was constructed with
all exterior panels and doors taped to an underlying frame with VHB™ Tape 4950. After
approximately 300,000 simulated miles on the harsh Durability T rack, the VHB™ Tape
bonds remained completely intact. This is particularly impressive in light of the fact that
some mechanically joined and welded parts experienced failures and required repairs for
the test to continue.
One of the most demanding applications for VHB™ Tape has been on aircraft exteriors.
Several commercial aircraft models ha ve incorporated stainless steel anti-chafing strips
bonded to the aluminum wing flaps. These panels help prevent abrasion and chafing
between the flap and underside of the wing during movement of the flaps for take offs,
landings, and in-flight vibration. VHB™Adhesive Transfer Tape 9473 continues to be a
means for bonding these panels into place. This application has been in use since 1984.
Durability is particularly key in this application since the bond can be subjected to high
skin temperatures in direct sunlight on the ground and -65°F (-54°C) at high altitudes.
In addition, this cycle can be repeated several times per day.
To request additional product inf ormation or to arr ange for sales assistance, call toll free 1-800-362-3550 or visit
www.3M.com/bonding. Address correspondence to: 3M Bonding Systems Division, 3M Center, Building 220-7E-01,
St. Paul, MN 55144-1000. Our fax number is 651-733-9175. In Canada, phone: 1-800-364-3577. In Puerto Rico,
phone: 1-809-750-3000. In Mexico, phone: 5-728-2180.
For Additional
Information
3M MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. User is responsible for
determining whether the 3M product is fit for a particular purpose and suitable for user’s method of application.
Please remember that many factors can affect the use and performance of a 3M product in a particular application.
The materials to be bonded with the product, the surface preparation of those materials, the product selected for
use, the conditions in which the product is used, and the time and environmental conditions in which the product is
expected to perform are among the many factors that can affect the use and performance of a 3M product. Giv en
the variety of factors that can affect the use and performance of a 3M product, some of which are uniquely within
the user’s knowledge and control, it is essential that the user evaluate the 3M product to determine whether it is fit
for a particular purpose and suitable for the user’s method of application.
Important Notice
MSDS: 3M has not prepared a MSDS for these products which are not subject to the MSDS requirements of the
Occupational Safety and Health Administration’s Hazard Communication Standard, 29 C.F.R.1910.1200(b)(6)(v).
When used under reasonable conditions or in accordance with the 3M directions for use, these products should
not present a health and safety hazard. However, use or processing of the products in a manner not in accordance
with the directions for use may affect their performance and present potential health and safety hazards.
TSCA: These products are defined as articles under the Toxic Substances Control Act and therefore, are exempt
from inventory listing requirements.
Recognition/
Certification
If the 3M product is proved to be defective, THE EXCLUSIVE REMEDY, AT 3M’S OPTION, SHALL BE TO
REFUND THE PURCHASE PRICE OF OR TO REPAIR OR REPLACE THE DEFECTIVE 3M PRODUCT. 3M shall
not otherwise be liable for loss or damages, whether direct, indirect, special, incidental, or consequential,
regardless of the legal theory asserted, including, but not limited to, contract, negligence, warranty, or strict liability.
Limitation of
Remedies and
Liability
This Bonding Systems Division product w as manufactured under a 3M quality system registered to ISO 9002 standards .
ISO 9002
- 6 -
