H.B. Fuller U3320

H.B. Fuller U3320 is a one-component, low-viscosity, UV-curable structural adhesive with excellent bonding characteristics on various plastics, especially PET/PETG and polycarbonate. The thin viscosity of U3320 makes it ideal for use in wicking applications, particularly on components with close-fitting tolerances.

Product Type: 1K (1 component) Adhesive, Radiation Curable Adhesive, Structural Adhesive

Application Area: Wicking Applications

Compatible Substrates & Surfaces: Plastics, Polycarbonate (PC), Polyethylene Terephthalate (PET), Polyethylene Terephthalate Glycol (PET-G)

Chemical Family: Acrylics & Acrylates

Features: Low Viscosity

Technical Data Sheet
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Enhanced TDS

Identification & Functionality

Features & Benefits

Ready-to-Use Product Features

Applications & Uses

Application Area
Compatible Substrates & Surfaces
Cure Method
General Instructions

Surfaces to be bonded should be clean and dry. Dispense a drop or drops to one surface only. Apply only enough to leave a thin film layer after compression. Press parts together and expose to UV dose when ready. An adequate bond should develop rapidly, depending on UV dose efficacy, and maximum strength is attained in 24 hours. Wipe off excess adhesive from the top of the container and recap. products, if left uncapped or exposed to sunlight, may deteriorate or cure prematurely.


Physical Form
Typical Properties
ValueUnitsTest Method / Conditions
Specific Gravity1.06--
Cured Properties
ValueUnitsTest Method / Conditions
Flash Pointmin. 95°C-
Set Time (at 395nm)max. 3s-
Full Cure Time24.0h-
Optimum Wavelenath300 - 420nm-
Cured AppearanceColorless solid--
Hardness54.0-ASTM D2240, Shore D
Hardness63.0-ASTM D2240, Shore A
Elongation at Break150.0%ASTM D638
Rheological Properties
ValueUnitsTest Method / Conditions
Viscosity (at 20°C - 25°C)30 - 60cP-

Technical Details & Test Data

Curing Performance

Photoinitiation initiates the curing process. Handling strength is reached in a short time, and will vary based on UV dose efficacy, environmental conditions, bond line gap, and other factors. Product will continue to cure for at least 24 hours before full strength and solvent resistance is developed.

Performance of Cured Adhesive

Substrate N/mm²
Metal 2.8 to 3.4
PETG 10.3 to 14.5
Glass 4.8 to 6.9
PMMA 4.1 to 5.5
PC 20.7 to 26.2

Performance Range, by Substrate

H.B. Fuller U3320 - Curing Performance

Percent Strength Retained at Given Dosage Image

H.B. Fuller U3320 - Percent Strength Retained At Given Dosage Image

Solvent Resistance
Solvent Example Resistance
Alcohol Ethanol, Methanol +++
Ester (aromatic) Ethylacetate ---
Ketone (aromatic) Acetone, Benzophenone ---
Aliphatic hydrocarbon (alkanes) Petrol, Heptanes, Hexane ++-
Aromatic hydrocarbons Benzyl. Toluol, Xylol ++-
Halogenated hydrocarbons Methylenchloride, Chloroform, Chlorobenzol ---
Weak aqueous acid Nitrite, muriatic acid, sulphuric acid, phosphoric acid

+++(--- if concentrated)

Weak aqueous base Sodium hydroxide solution, caustic potash

+++(--- if concentrated)

Packaging & Availability

Regional Availability
  • North America

Storage & Handling

Shelf Life
9 Months

Products should be stored unopened in a cool, dry place out of direct sunlight. Products should be kept at room temperature away from direct light. Protect from extreme heat or cold, do not refrigerate. Store at 8°C to 21°C in darkness.