loctite 406

Loctite 406

Application method:Dispense system; Manual
Applications:Bonding elastomerics; Bonding plastic
Color:Clear
Cure type:Moisture cure
Fixture time, Steel:30.0 sec.
Gap fill:0.12 mm
Key characteristics:Fixture: fast fixture; Viscosity: low viscosity
Operating temperature:-40.0 °C – 120.0 °C (40.0 °F – 250.0 °F)
Physical form:Liquid
Recommended for use with:Elastomer; Plastic; Rubber
Resin: Viscosity:20.0 mPa·s (cP)
Shear strength, Mild Steel (grit blasted):15.5 N/mm² (2250.0 psi)

Overview

Loctite 406 is a clear, very low-viscosity cyanoacrylate instant adhesive designed especially for fast bonding of plastics and elastomers. It flows almost like water, quickly wicking into tight, close-fitting joints and fine gaps, giving strong bonds in seconds on:

  • Many engineering plastics

  • Rubbers and elastomers

  • Metals and other common substrates (especially when used with a suitable primer)

In production, Loctite 406 is often paired with a polyolefin primer for bonding low-surface-energy plastics like PP, PE and PTFE, which are otherwise hard to glue.

Key Features & Benefits

  • Specialized for plastics & rubber
    Formulated to give strong, reliable bonds on a wide range of plastics and elastomers, where general-purpose instant adhesives can be inconsistent.

  • Very low viscosity for wicking
    Almost water-thin, so it can penetrate tight joints, hairline cracks and porous edges, ideal for capillary bonding and pre-assembled parts.

  • Fast fixture in seconds
    Reaches handling strength very quickly, helping shorten assembly cycles and enabling fast MRO repairs.

  • Clear, nearly invisible bond line
    Cures to a colorless, transparent joint, suitable for visible plastic housings, clear components and small precision parts.

  • Single-component, room-temperature cure
    No mixing, no ovens: just apply, assemble and hold. Cures with ambient moisture.

  • Compatible with primers for difficult plastics
    When used with primers such as a polyolefin surface primer, Loctite 406 can bond PP, PE, PTFE and other low-energy plastics.

Typical Applications

Loctite 406 is widely used in electronics, consumer devices, automotive, medical equipment (non-invasive parts) and general industrial assembly:

  • Plastic part bonding

    • Joining ABS, PVC, PC and other engineering plastics in housings, covers and clips

    • Securing small plastic guides, spacers, nameplates and labels

  • Rubber & elastomer bonding

    • Bonding O-rings, seals, grommets and rubber pads to plastic or metal

    • Attaching soft feet, bumpers and grips to tools and devices

  • Fine, close-fitting assemblies

    • Wicking into tight plastic-to-plastic or plastic-to-metal joints

    • Bonding small components where access is limited and only a tiny amount of adhesive is needed

  • MRO and quick repairs

    • Repairing cracked plastic housings and broken clips

    • Re-attaching rubber trims, seals and small decorative parts

How to Use Loctite 406

Always follow the latest Henkel Technical Data Sheet (TDS) and your own process instructions. The steps below are a practical summary.

Step 1 – Surface preparation

  1. Make sure all surfaces are clean, dry and free from oil, dust and release agents.

  2. Clean plastics, rubbers and metals with a suitable solvent or industrial cleaner; allow to dry fully.

  3. For tough plastics (PP, PE, PTFE and some TPEs), apply a polyolefin primer, let it flash off, then use Loctite 406.

Step 2 – Adhesive application

  1. Apply a small amount of Loctite 406 to one of the bonding surfaces.

  2. Because the adhesive is very low viscosity, use minimal drops or a fine bead to avoid flooding the joint.

  3. For pre-assembled or tight joints, place the adhesive at the edge of the joint and let it wick in by capillary action.

Step 3 – Assembly

  1. Immediately bring parts together (if not already assembled), align correctly and apply firm, even pressure.

  2. Hold for several seconds until the joint reaches handling strength; exact fixture time depends on material, gap, humidity and temperature.

  3. Avoid sliding or peeling the joint during the first moments of cure.

Step 4 – Full cure & finishing

  1. Although fixture happens quickly, allow up to 24 hours at room temperature for full cure and maximum strength.

  2. Wipe away any fresh squeeze-out immediately with a cloth and appropriate cleaner.

  3. Once fully cured, excess adhesive is best removed by mechanical means (scraping, careful cutting) or a cyanoacrylate debonder.

Safety & Handling

Loctite 406 is a cyanoacrylate instant adhesive and should be handled with care:

  • Bonds skin and eyes in seconds – avoid contact; do not forcibly pull apart bonded skin.

  • Use in a well-ventilated area; vapors can irritate eyes and respiratory system.

  • Wear safety glasses and suitable chemical-resistant gloves (often nitrile) during regular use.

  • Store in a cool, dry place, tightly closed, away from heat and direct sunlight to maintain shelf life.

  • Prevent uncured adhesive from entering drains or waterways; dispose of waste according to local regulations.

Always review the current Safety Data Sheet (SDS) and Technical Data Sheet (TDS) before production use.

FAQs

Q1: What is Loctite 406 mainly used for?
Loctite 406 is mainly used for fast, high-strength bonding of plastics and elastomers, especially close-fitting parts where a very low-viscosity adhesive can wick into the joint.

Q2: How is Loctite 406 different from general-purpose instant adhesives?
Compared with general-purpose cyanoacrylates, Loctite 406 is optimized for plastics and rubbers and has very low viscosity, giving better capillary action and more consistent results on these substrates.

Q3: Which materials does it bond best?
It bonds many engineering plastics (ABS, PVC, PC, etc.), rubber and elastomers, and metals. With a suitable primer, it can also bond polyolefins like PP and PE and PTFE, which are normally difficult to glue.

Q4: How fast does Loctite 406 cure?
On active materials and tight joints, Loctite 406 usually reaches handling strength in seconds. Full strength and maximum chemical resistance develop over several hours, typically up to 24 hours.

Q5: Can Loctite 406 fill large gaps?
No. It is designed for very small gaps and close-fitting parts. For wider gaps or noticeably uneven joints, a higher-viscosity CA, structural acrylic or epoxy may be more suitable.

Q6: Is the cured adhesive flexible?
Loctite 406 cures to a rigid thermoplastic, typical of cyanoacrylates. It works well on small joints, including rubber and plastic parts, but it is not a soft, rubbery adhesive.

Q7: Can parts bonded with Loctite 406 be disassembled?
Cyanoacrylate bonds are generally intended to be permanent. Disassembly typically requires mechanical force and/or a debonder, and often damages at least one part. Design bonded joints assuming limited rework.

Q8: Is Loctite 406 suitable for medical or food-contact applications?
Any use in regulated applications (medical, food, potable water, etc.) must be checked against the relevant standards and confirmed with Henkel and your regulatory team. Loctite 406 is not automatically approved for those uses.

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