Loctite 222 Low Strength Threadlocker

LOCTITE 222 is a single-component anaerobic acrylic adhesive based on dimethacrylate ester chemistry and designed for low strength threadlocking applications. The uncured product appears as a purple liquid and exhibits positive fluorescence under UV light for inspection control. It features low viscosity with thixotropic properties, helping to reduce dripping and migration after application. The adhesive cures when confined between close fitting metal surfaces in the absence of air and can be used with Activator SF 7471™ or SF 7649™ as a secondary cure system when faster cure is required. It is classified as a low strength threadlocker, allowing convenient disassembly with standard hand tools.

The product has a specific gravity of 1.05 at 25°C. Brookfield viscosity measured at 25°C using RVT with spindle 3 at 2.5 rpm is ≥3,500 mPa·s (cP), and at 20 rpm ranges from 900 to 1,500 mPa·s (cP). According to EN 12092 testing at 25°C after 180 seconds, viscosity at a shear rate of 277 s⁻¹ is 135 mPa·s (cP). Cure performance depends on substrate material, bond gap, temperature, and activator use. Breakaway strength development tested on M10 steel nuts and bolts according to ISO 10964 shows faster curing on steel and brass compared to stainless steel and zinc dichromate surfaces. Larger bond gaps influence cure speed, with controlled gaps of 0.05 mm, 0.15 mm, and 0.25 mm affecting shear strength development as tested under ISO 10123 conditions. Cure rate increases at elevated temperatures such as 40°C compared to 22°C or 5°C. When cure speed is slow or larger gaps are present, applying Activator SF 7471™ or SF 7649™ improves curing performance significantly.

After 24 hours at 22°C, breakaway torque on M10 steel nuts and bolts tested according to ISO 10964 is approximately 6 N·m (50 lb·in), with prevail torque of 4 N·m (35 lb·in). Breakloose torque for M10 steel nuts and bolts pre-torqued to 5 N·m measures 14 N·m (120 lb·in), and maximum prevail torque under the same pre-torque condition is also 14 N·m (120 lb·in). Compressive shear strength tested on steel pins and collars according to ISO 10123 is ≥2.5 N/mm² (≥360 psi).

Physical properties of the cured adhesive include a coefficient of thermal expansion of 80 × 10⁻⁶ K⁻¹ (ISO 11359-2), thermal conductivity of 0.1 W/(m·K) as per ISO 8302, and specific heat of 0.3 kJ/(kg·K). Environmental resistance testing performed after curing for one week at 22°C shows stable performance under elevated temperatures up to 150°C. Heat aging studies conducted at 120°C and 150°C for exposure periods up to 5000 hours indicate gradual strength retention over time. Chemical and solvent resistance testing demonstrates strength retention of 85% after 5000 hours in motor oil (MIL-L-46152) at 125°C, 95% retention in leaded petrol at 22°C, 90% retention in brake fluid at 22°C, and consistent 80% retention in water/glycol 50/50 mixture at 87°C. Acetone exposure retains 90% strength after long-term aging, and ethanol retains approximately 90% after 5000 hours.

This product is not recommended for use in pure oxygen or oxygen-rich systems and should not be used as a sealant for chlorine or other strong oxidizing materials. It is generally not recommended for plastics, especially thermoplastics where stress cracking may occur, and compatibility testing is advised before use on such materials.

For assembly, all threaded surfaces should be cleaned using a LOCTITE cleaning solvent and allowed to dry. If bonding inactive metals or when faster cure is needed, Activator SF 7471™ or SF 7649™ should be sprayed onto threads and allowed to dry before adhesive application. The product should be shaken thoroughly before use, and care should be taken to prevent nozzle clogging by avoiding contact with metal surfaces. For through holes, several drops should be applied onto the bolt at the nut engagement area. For blind holes, several drops should be applied into the internal threads down to the bottom of the hole. For sealing applications, a 360° bead should be applied to the leading threads of the male fitting, leaving the first thread free and forcing the material into the threads to fully fill voids. Assembly and tightening should be completed as required.

Disassembly can normally be carried out using standard hand tools. In rare cases where removal is difficult due to excessive engagement length, localized heating to approximately 250°C is recommended before disassembling while hot. Cured adhesive residue may be removed using LOCTITE solvent combined with mechanical abrasion such as wire brushing.

The product should be stored in unopened containers in a dry location. Optimal storage temperature is between 8°C and 21°C. Storage below 8°C or above 28°C may adversely affect product properties. Contaminated material should not be returned to the original container. The technical data provided represent typical values and are intended for reference purposes only. Users are advised to conduct their own testing to confirm suitability for specific applications and operating conditions.