LOCTITE® AA 3921 LC is a low-viscosity, UV/visible-light curing acrylic adhesive that bonds plastics, glass, ceramics and metals. It cures in seconds under the right light intensity and is qualified to ISO 10993 for medical device applications.
Appearance: Clear, translucent liquid before cure
Viscosity: 80 – 220 mPa·s (Brookfield RVT @ 25 °C)
Specific gravity @ 25 °C: 1.03
Cure method: UV / visible-light exposure for surface cure; light-curing acrylic adhesive
Depth of cure: >13 mm under suitable light intensity
Fixture time: approx. 3 seconds under optimal light conditions
Cure substrates: Plastics, glass, metals, ceramics — suitable for stress-sensitive plastics and metal/glass/ceramic bonding
Primary Chemistry:
Acrylic ester, light-cure adhesive
LOCTITE® AA 3921 LC is designed for high-speed, high-precision assembly where gentle handling of stress-sensitive plastics or mixed materials is required. Its low viscosity allows easy dispersion into narrow joints or wells, making it ideal for small components or assemblies such as syringes, lancets, medical instruments or plastic housings. Once exposed to UV or visible light, the adhesive cures rapidly — fixture can be achieved in as little as three seconds under optimal light conditions. The cured bond delivers strong adhesion to glass, plastic, metal and ceramic substrates. The LC low-chlorine variant is suitable for sensitive applications where ionic contamination must be minimised, such as medical, electronics or device manufacturing.
Appearance: Clear, translucent liquid before cure
Viscosity: 80 – 220 mPa·s (Brookfield RVT @ 25 °C)
Specific gravity @ 25 °C: 1.03
Cure method: UV / visible-light exposure for surface cure; light-curing acrylic adhesive
Depth of cure: >13 mm under suitable light intensity
Fixture time: approx. 3 seconds under optimal light conditions
Cure substrates: Plastics, glass, metals, ceramics — suitable for stress-sensitive plastics and metal/glass/ceramic bonding
Primary Chemistry:
Acrylic ester, light-cure adhesive
Eliminates slow curing delays or the need for long post-cure periods in high-volume production
Prevents damage to stress-sensitive plastics by offering a low-viscosity, low-stress adhesive system
Reduces risk of bond failure in mixed-material assemblies due to unmatched adhesives
Avoids contamination issues in sensitive environments by using a low-chlorine, medical-rated adhesive
Supports consistent, reliable bonding across multiple substrate types — reduces need for multiple adhesive products
Use LOCTITE® AA 3921 LC for bonding stress-sensitive plastics, metal, glass or ceramic components in medical devices, disposable instruments, small assemblies, or transparent housings. Apply a thin layer to clean, dry surfaces. After assembly, expose the joint to UV or visible light with sufficient intensity to initiate cure. The low viscosity ensures the adhesive flows into narrow joints or wells — particularly useful when bonding cannulae, syringes or luer fittings. Once cured, the bond is strong and remains flexible enough to tolerate handling, yet durable under stress and autoclave conditions if required.
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