Loctite 2701 Threadlocker

LOCTITE 2701 is a one-component anaerobic acrylic adhesive based on dimethacrylate ester technology and designed specifically for high strength threadlocking applications. The uncured material appears as a green liquid and exhibits positive fluorescence under UV light for inspection purposes. It requires no mixing and cures when confined between close fitting metal surfaces in the absence of air. The product has low viscosity and can be used with an activator as a secondary cure system when faster curing is required, especially on inactive substrates. It is particularly suited for permanent locking and sealing of threaded fasteners where maximum resistance to hot oil and harsh operating environments is necessary.

The uncured adhesive has a specific gravity of 1.08 at 25°C. Brookfield viscosity measured at 25°C using RVT spindle 2 at 20 rpm ranges between 500 and 900 mPa·s (cP). Cure performance depends on substrate type, bondline gap, temperature, and activator usage. Shear strength development tested according to ISO 10123 on steel pins and collars demonstrates that steel provides the fastest cure, followed by brass, zinc dichromate, and stainless steel. Smaller bond gaps such as 0.05 mm cure faster than larger gaps such as 0.15 mm. Cure speed increases at elevated temperatures such as 40°C compared to 22°C and 5°C. When cure speed is insufficient or large gaps are present, application of Activator SF 7471™ or Activator SF 7649™ significantly accelerates strength development compared to no activator.

After 24 hours curing at 22°C, LOCTITE 2701 exhibits high mechanical performance. Breakaway torque tested according to ISO 10964 on M10 black oxide steel nuts and bolts ranges from 26 to 50 N·m (230 to 440 lb·in). Prevail torque on the same assemblies is ≥15 N·m (≥132 lb·in). For fasteners pre-torqued to 5 N·m, breakloose torque ranges from 30 to 60 N·m (265 to 530 lb·in), and maximum prevail torque ranges from 36 to 60 N·m (320 to 530 lb·in). Compressive shear strength measured according to ISO 10123 on steel pins and collars ranges from 18 to 30 N/mm² (2,610 to 4,350 psi). Torque augmentation testing shows that breakloose torque of an uncoated fastener is typically 15 to 30 percent lower than the on-torque, and the use of LOCTITE 2701 significantly increases breakloose torque compared to untreated fasteners.

Physical properties of the cured adhesive include a coefficient of thermal expansion of 100 × 10⁻⁶ K⁻¹ according to ISO 11359-2, thermal conductivity of 0.1 W/(m·K) according to ISO 8302, and specific heat of 0.3 kJ/(kg·K). Environmental resistance testing after curing for one week at 22°C demonstrates strong durability under heat aging conditions. Exposure at 120°C and 150°C followed by testing at 22°C shows good retention of strength over extended time periods. Chemical and solvent resistance testing indicates excellent performance after 100, 500, and 1000 hours exposure. In motor oil at 125°C, strength retention ranges from 95% to 110%. In gasoline at 22°C, retention ranges from 100% to 115%. Brake fluid at 22°C maintains 100% to 105% strength. Ethanol exposure maintains approximately 95% strength retention. Acetone and 1,1,1 trichloroethane exposure show 100% to 110% retention. Water/glycol 50/50 mixture at 87°C maintains 100% strength retention.

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

For assembly, all external and internal surfaces should be cleaned using a LOCTITE cleaning solvent and allowed to dry. If the material is inactive or cure speed is slow, apply primer to all threads and allow to dry. To prevent nozzle clogging, avoid contact between the dispensing tip and metal surfaces. For through holes, apply several drops to the bolt at the nut engagement area. For blind holes, apply several drops down the internal threads to the bottom of the hole. For sealing applications, apply a 360° bead of product to the leading threads of the male fitting while leaving the first thread free, ensuring thorough filling of voids. Larger threads and gaps may require additional product application on both male and female threads before assembly and tightening.

For disassembly, apply localized heat to the nut or bolt to approximately 250°C and disassemble while hot. Cured adhesive can be removed by soaking in a LOCTITE solvent followed by 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. Material removed from the original container may become contaminated and should not be returned. Technical data represent typical laboratory values and are provided for guidance only; users should perform their own testing to confirm suitability for specific applications.