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LOCTITE 4861 Flexible Instant Adhesive for Rapid Component Bonding

LOCTITE 4861 Flexible Instant Adhesive is a one-component, high-viscosity cyanoacrylate formulated to create fast yet flexible bond lines. It rapidly bonds metals, plastics, elastomers, and porous materials while helping rubber components maintain their compressibility after assembly. The clear, colorless adhesive requires no mixing or external heating and is particularly suited to disposable medical-device production and other precision industrial applications.

The product uses a combination of ethyl and butyl cyanoacrylate chemistry and cures when atmospheric moisture contacts closely fitted bonding surfaces. Its flexible cured structure makes it useful for assemblies exposed to movement, compression, vibration, or differences in substrate flexibility. Henkel has tested LOCTITE 4861 according to internal protocols based on ISO 10993 biocompatibility standards to assist manufacturers evaluating adhesives for disposable medical devices.

Key Benefits of LOCTITE 4861 Flexible Instant Adhesive

LOCTITE 4861 Flexible Instant Adhesive has a typical viscosity of approximately 3,000–5,500 mPa·s at 25°C and a specific gravity of about 1.05. Its higher viscosity provides better dispensing control than very fluid instant adhesives, helping the material remain around component interfaces, porous substrates, and vertical application areas. Henkel recommends a thin bond gap of approximately 0.05 mm for optimum curing and performance.

Fixture time varies according to the substrate, bond gap, temperature, and humidity. Representative values at 22°C and 50% relative humidity include 7–15 seconds on grit-blasted steel, 10–15 seconds on nitrile rubber, 3–5 seconds on ABS or PVC, 5–10 seconds on polycarbonate, and no more than 15 seconds on paper. Full chemical and solvent resistance continues to develop for at least 24 hours.

After curing for 24 hours at 22°C, the adhesive has a typical Shore A hardness of 80–90, tensile modulus of approximately 280–580 N/mm², and glass-transition temperature of about 60°C. These properties create a more compliant bond than many rigid cyanoacrylates, helping reduce concentrated stress when bonding flexible rubber, plastic, fabric, and mixed-material components.

Published seven-day lap-shear results include approximately 11–17 N/mm² on grit-blasted steel, 8–12 N/mm² on grit-blasted aluminum, 5–9 N/mm² on ABS, 6–8 N/mm² on polycarbonate, and 8–12 N/mm² on epoxy FR4. The product also provides at least 5 N/mm² tensile strength on Buna-N rubber after a 30-second cure under the manufacturer’s test conditions.

Applications for LOCTITE 4861 Flexible Instant Adhesive

LOCTITE 4861 Flexible Instant Adhesive is suitable for disposable medical-device components, flexible tubing assemblies, rubber seals, elastomer parts, plastic housings, metal fittings, electronic components, fabric products, leather, paper, and precision industrial assemblies. The flexible bond line is particularly useful where rubber components must remain compressible rather than becoming rigid at the bonded area.

Compatible substrates include steel, aluminum, ABS, PVC, polycarbonate, nitrile rubber, epoxy FR4, leather, paper, and wood. Difficult low-surface-energy plastics such as polypropylene, polyethylene, and PTFE may be bonded after applying a compatible primer such as LOCTITE SF 7701. Adhesion and material compatibility should always be confirmed using the actual production substrates.

Products of similar composition generally retain bond strength following ethylene-oxide and gamma-radiation sterilization. LOCTITE 4861 also maintains bond strength after one steam-autoclave cycle under the published test conditions. Manufacturers should validate the adhesive after their complete sterilization process, especially when devices undergo multiple cycles.

How to Apply LOCTITE 4861 Flexible Instant Adhesive

Before applying LOCTITE 4861 Flexible Instant Adhesive, ensure that both surfaces are clean, dry, accurately fitted, and free from grease, oil, dust, moisture, release agents, and loose contamination. Apply a small controlled quantity to one surface, assemble the components immediately, and maintain alignment until fixture strength develops.

Excessive adhesive or wide bond gaps can slow curing. Where fixture time becomes unacceptably long, a compatible activator may be evaluated, although an activator can reduce ultimate bond strength. Excess uncured adhesive may be cleaned using an appropriate LOCTITE cleaner, nitromethane, or acetone after confirming compatibility with the surrounding materials.

Storage of LOCTITE 4861 Flexible Instant Adhesive

Store unopened LOCTITE 4861 Flexible Instant Adhesive in a dry location between approximately 2°C and 8°C. Do not return dispensed material to the original container because contamination may affect storage stability and curing performance. Review the current safety data sheet and use appropriate eye protection, gloves, and workplace controls because cyanoacrylate adhesives bond skin and eyes rapidly.

For manufacturers requiring fast fixture, high-viscosity dispensing, flexible curing, and broad substrate compatibility, LOCTITE 4861 Flexible Instant Adhesive provides a dependable solution for medical devices, elastomers, plastics, metals, and porous-material assemblies. Explore our flexible instant adhesives for medical devices, rubber, plastic, metal, leather, fabric, paper, and precision component bonding.

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