3M VHB Technical Bulletin

March, 2001

3

Technical Bulletin

3MTMVHBTMDurability

Durability of 3M™VHB™Tapes

Summary

This 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 view-points
including chemical composition, resistance to harsh environments, 3M and
independent tests for 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 sensitive adhesive (PSA)
technology for over 35 years. The VHB™ Acrylic Foam and Adhesive Transfer Tapes
represent examples of 3M’s proprietary state-of-the-art in this durable chemistry. 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, however,
additional crosslinking is chemically favored over chain scission (cleavage). This
means that, rather than undergoing 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 diverse 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 unaffected by long-term exposure
to elevated temperatures. Bonds made with VHB™ Tapes can tolerate periodic, short­term exposures to temperatures up to 300°F (150°C) for most Foam Tapes and 500°F
(260°C) for Adhesive Transfer Tapes.

Technical Bulletin

3MTMVHBTMTape 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 cycling 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 below its original performance level, even after exposure of 7000 hours in
the weatherometer under these tests.

200

150

100

50

0

0

2000

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 shows 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

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