Loctite 402

Product Overview

LOCTITE 402 is a single-component, moisture-curing cyanoacrylate adhesive engineered for rapid assembly of small parts where durability and elevated service temperatures are required. It bonds strongly to metals, plastics, rubbers and even more challenging substrates with the use of a primer. This adhesive offers reliable performance under extreme conditions—such as elevated temperatures up to ~135 °C (275 °F) — making it suitable for high-speed production applications and precision repairs.

Key Features & Benefits

• Fast fixture time (~20 seconds on steel) for efficient assembly.

• Medium viscosity (~110 mPa·s) for precise application and controlled flow.

• High temperature resistance (–40 °C to +135 °C) supports thermal cycling environments.

• Strong bonding across metals, plastics, rubbers, and porous materials (wood, leather, paper) when required.

• Meets ISO-10993 biocompatibility standard, making it viable for medical or device assembly contexts.

Application / Use Instructions

Surface Preparation:

• Clean all bonding surfaces thoroughly to remove oil, grease, old adhesive or coatings. Use a suitable cleaner (e.g., LOCTITE® SF 7070).

• For plastics that are difficult to bond (e.g., PP, PE, PTFE), apply a primer such as LOCTITE® SF 770.

Application:

• Apply a small amount of LOCTITE 402 to one of the surfaces. Because the fixture time is very short, ensure accurate part alignment before assembly.

• Assemble parts immediately, and maintain contact or clamping until the adhesive has fixtured (approx. 20 seconds).

Curing / Handling:

• Handling strength is reached quickly; full bond strength develops over time under appropriate ambient conditions.

• Avoid exposing the bond to full loads or critical stress until full cure is achieved.

Disassembly / Repair:

• If removal is required, consult the TDS or SDS for recommended methods; bond may require mechanical separation and/or heat due to high strength and performance.

Tips:

• Because of the rapid cure, part positioning must be done with care.

• Use minimal adhesive to avoid excess flash or stress concentrations.

• Ensure proper gap control to achieve optimal bond strength and avoid failure due to too large a gap.

FAQs

Q1: What makes LOCTITE 402 different from standard instant adhesives?
A1: It offers higher temperature resistance (up to ~135 °C), fast fixture time, and is suitable for a broader range of substrates including some challenging ones.

Q2: Can it bond plastics like PP or PTFE?
A2: Yes — when used with an appropriate primer such as LOCTITE® SF 770, bonding to low-surface-energy plastics is possible.

Q3: How quickly does LOCTITE 402 set?
A3: On steel it typically fixtures in about 20 seconds under standard conditions.

Q4: What is the recommended gap for bonding?
A4: Up to ~0.15 mm gap is recommended for optimal performance—larger gaps may reduce strength or slow cure.

Q5: Is this adhesive suitable for high-temperature applications?
A5: Yes — LOCTITE 402 supports service temperatures up to ~135 °C (275 °F) and is designed for heat­-aging and durability.