3M™ Wind Blade Adhesive W1100 - European Coatings · 3M Products for Wind Energy 3M Renewable Energy Division 3M enables more efficient and more reliable wind turbines, build faster

3M Products for Wind Energy

Advancements in Structural Epoxy Adhesives for Wind Blade Assembly

European Coatings Conference "Adhesives for wind and solar technology" Tony Kremer & Christian Claus 3M Renewable Energy Division


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Founded: 1902 in Two Harbors, USA Today’s Headquarters: St. Paul, Minnesota From its beginnings as a mining company (= Mining), and later including further processing (= Manufacturing), 3M has now developed into a diversified technology company with worldwide operations.

3M Europe and Middle East Headquarters: Brussels Sales: $ 6.3 billion Employees: 18,120 Subsidiaries in more than 30 countries

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3M Renewable Energy Division

3M enables more efficient and more reliable wind turbines, build faster and safer

Leveraging 3M’s core competencies in the field of films, adhesives, tapes, coatings and the inventive power of 40+ additional corporate technology platforms


3M Renewable Energy Division

3M’s Renewable Energy

Reduce cycle time Lower blade costs Faster, more efficient blade

throughput

Blade Processing

Aids

Increase strength, decrease weight Lower blade costs Improve turbine efficiency Enhance mechanical properties Improve laminate quality

Blade Structure

Blade Bonding

Structural Adhesives & Threadlockers

Dry Layup Adhesive

Sealants

Butyl Tape Mold Release

Other Consumable Tapes

Improve resistance to erosion, icing, and fouling Reduce cycle time Improve aerodynamics Reduce interference with radar Easier to maintain

Blade Surface

Erosion Coatings Functional Coatings

Wind Repair Fillers

Hot Melts

Wind Protection Tapes


Important Notes

W1100 = original wind blade adhesive offered by 3M (superseded by W1101) W1101 = current high performance wind blade adhesive from 3M Unless otherwise stated, the results presented for W1100 and W1101 are

based on a 4 hour 70°C cure.

The information presented here should be considered typical or representative only, and should not be used for specification purposes. The data are also based on a limited number of manufacturing runs.

On occasion, 3M does provide internal 3M test data as a service to our customers. 3M does not certify the accuracy or validity of this information and 3M is not responsible for customer’s interpretation of or use or misuse of the provided information. For example, customers should not use this information for business purposes, including but not limited to setting test criteria, developing a specification or evidence of meeting a specification, or as a basis for determining if a product is fit for a particular application or will have particular attributes. Product attribute claims should not be based on this information.

The information provided is made available on an “as is” basis. 3M makes no warranty, express or implied, related to this information. 3M shall not be liable for any incidental, special, or consequential damages relating to the use or inability to use this information, regardless of the legal theory asserted.


Epoxy Adhesives

Structural epoxy adhesives have been successfully used for wind blade assembly for decades Common properties:

High shear strength Outstanding adhesion to common wind blade materials

Excellent mechanical properties High tensile modulus (rigidity) High ultimate tensile strength

Superior elevated temperature properties (onset Tg > 65°C with thermal cure) Moderate exotherm and bond line temperatures Robust mix ratio tolerance Low shrinkage during cure Outstanding environmental resistance


Shear Strength

Cohesive failure

Laminate failure

Laminate failure

Cohesive failure

Failure during lap shear tests on epoxy composite materials mostly occurs

within substrate (interlaminate split)


Shear Strength

GL Requirement

Shear strength > 22 MPa and relatively constant over temperature

range from -40°C to 50°C


Tensile Properties

Relatively constant tensile modulus and rigidity over a wide temperature range =

cured adhesive glass transition well above maximum 50°C

operating temperature

Toughened epoxy formulations (such as 3M W1101) exhibit slightly lower tensile strength but higher elongations at break


Exotherm

3M W1101: Energy release ≈240 J/g

Standard epoxy adhesive: Energy release ≈290 J/g

Differential Scanning Calorimetry 10°C/min ramp rate

Reduced total energy release (exotherm) during cure helps control maximum adhesive

bond line temperatures


Bond Line Temperature

Thick adhesive bond line (20 mm) sandwiched between two plastic slabs

to simulate wind blade assembly

Peak centerline adhesive temperatures ≈ 100°C

Thinner bond lines or lower temperature cures will further reduce the peak temperature


Shrinkage During Cure

Density increase during cure corresponds to:

1.00% volume shrinkage 0.33% linear shrinkage

3M W1101

Mix

Cure


Environmental Resistance

3M W1101

Essentially no reduction in bond strength after 1,000 hours immersion in a wide variety of solvents, high temperature,

high humidity, and other environments


Epoxy Adhesives

Some recent advancements in structural epoxy adhesives for wind blade assembly can provide process improvements and greater final performance Differentiating properties:

Cure speed Strength development Tg development

Pot life Toughness

T-peel Floating roller peel Fracture energy

3M W1101

+ =


Strength Development High temperature lap shear test ensures

adhesive has cured to sufficient Tg

3M W1101 provides 70°C shear strength of 12 MPa after just 2.5 hours of 70°C cure

(4 hours faster than standard epoxy adhesive)


Strength Development

Two-part epoxy adhesives cure slowly at room temperature, but with an improved

curative package, can cure extremely quickly at temperatures of 50°C and higher


Tg Development

3M W1101 provides a midpoint Tg of 70°C after just 2.5 hours of 70°C cure

(at least 4 hours faster than the standard epoxy adhesive)


Tg Development

Regardless of exact cure schedule, epoxy adhesives with an optimized curative package can save hours of mold time

GL Requirement

Minimum onset Tg > 65°C ensures consistent

mechanical properties up to 50°C (and probably to

even higher temperatures)


Pot Life

Despite faster cure speeds, both epoxy adhesives (3M W1100 and

W1101) retain higher % of original bond strength for longer pot life


Toughness (via T-Peel)

GL Requirement

Peel tests force cohesive split of adhesive itself, providing some indication of internal toughness

3M W1101 provides 3.5x higher T-peel strength compared to the standard epoxy adhesive


Toughness (via Floating Roller Peel) Peel tests force cohesive split of adhesive itself, providing some indication of internal toughness

3M W1101 provides 3x higher floating roller peel strength

compared to the standard epoxy adhesive at 22°C, and much greater

increase at cold temperatures


Toughness (via Fracture Energy) Compact tension test measures energy required to propagate a crack through the adhesive, an

excellent indication of toughness

Toughened epoxy adhesives can provide over 2x higher

fracture energy compared to the standard epoxy adhesive


Conclusion

Advancements in structural epoxy adhesives for wind blade assembly can provide: Faster cure speed (approximately 4 hours faster at 70°C)

= mold time savings, manufacture more blades per mold Longer pot life (at least 2 hours at 30°C) Improved mechanical properties Equivalent shear strength 3x peel strength 2x fracture energy = improved crack resistance, fewer repairs, greater performance and durability

= improved performance in more demanding applications (longer blades, segmented or modular construction)


for your attention Thank You

Christian Claus Business Development Manager Wind Energy - Renewable Energy Division 3M Europe, Middle East & Africa E-Mail: [email protected] Tel: +49-2131-144140

More Information www.3M.com/wind

Documents

3M™ Wind Blade Adhesive W1100 - European Coatings · 3M Products for Wind Energy 3M Renewable Energy Division 3M enables more efficient and more reliable wind turbines, build faster