Loctite E-120HP two-component epoxy structural adhesive

LOCTITE® EA E-120HP Epoxy Adhesive - Assembtek Process-Ready Version

Two-Component Epoxy · High Viscosity · Room Temperature Curing · High Impact/Peel Resistance | Suitable for multi-substrate bonding in aerospace and general industry, adapting to low-stress assembly scenarios, balancing structural strength and process flexibility, and compatible with mass automated production lines.

Assembtek Process-Verified Version | Designed specifically for high-demand structural bonding, it adopts a combination of epoxy resin and polyamide curing agent. After room temperature curing, it forms a tough amber adhesive layer with excellent thermal shock resistance, mechanical properties and chemical resistance, making it the preferred solution for multi-substrate bonding under complex working conditions.

Module 1: The Hero Specs

Assembtek Process Summary:

LOCTITE® EA E-120HP is not an ordinary industrial epoxy adhesive, but a cost-effective structural bonding solution that balances strength and process flexibility. Its two-component precise ratio design is compatible with automated production, the long working life reduces operational difficulty, and the room temperature curing feature reduces energy consumption input. At the same time, it has excellent mechanical properties and environmental tolerance, which can be widely used in aerospace, general industry and other fields. It perfectly balances production efficiency, product quality and cost control, and is the core choice for complex multi-substrate structural bonding.

Module 2: Technical Data & Performance Curves

Typical Properties of Uncured Material (Tested According to TDS)

Typical Properties of Cured Material

Performance Curve Insights

📈 Relationship Between Curing Speed and Temperature

Curing speed is positively correlated with ambient temperature: at room temperature (25℃), a certain shear strength can be achieved in 30 minutes, and complete curing can be achieved in 24 hours; when cured by heating at 65℃, nearly complete curing strength can be achieved in 2 hours, and the shear strength reaches the peak after curing for 12 hours. The curing method can be flexibly selected according to the production rhythm.

📉 Relationship Between Shear Strength, Substrate and Curing Conditions

The shear strength varies significantly with different substrates, and curing conditions have a great impact on the strength: the shear strength of etched and ground aluminum can reach 33N/mm² (the highest) after curing at 65℃ for 12 hours; stainless steel and glass are the next; nylon and acrylic are the lowest; at the same time, when the bonding gap is controlled at 0.1-0.2mm, the shear strength is optimal. If the gap is too large (exceeding 0.5mm), the strength will decrease by more than 30%.

Selection Insight: For high-demand structural bonding (such as aerospace components), it is recommended to use heating curing at 65℃ for 12 hours to ensure the strength reaches the peak; for conventional industrial assembly, room temperature curing can be selected to balance efficiency and cost; the bonding gap must be strictly controlled at 0.1-0.2mm, and surface treatment should be selected according to the substrate type (metal substrates are preferably degreased and etched) to further improve the bonding strength.

Module 3: Applications & Substrates

Typical Application Scenarios

Substrate Compatibility Recommendation

Process Tips: Before bonding, ensure the substrate surface is clean, oil-free and dust-free. Metal substrates can be treated with degreasing agent, and acid etching or sandblasting can be further performed for high-demand scenarios; when mixing the adhesive, ensure the ratio is precise (2:1 by volume / 100:46 by weight) and mix evenly until the color is consistent; excess uncured adhesive can be removed with organic solvents such as acetone, and the cured adhesive layer must be removed by mechanical means.

Module 4: Process Engineering Insight

Mass Production Cost and Efficiency Optimization Tips

💰 Cost Reduction Tip 1: Optimize Mixing and Dispensing Methods to Reduce Adhesive Waste

Traditional Method: Manual mixing of adhesive leads to large ratio errors and uneven mixing, which easily causes adhesive failure. At the same time, manual dispensing is prone to overflow and uneven dispensing, resulting in adhesive waste and increased cleaning costs.

Assembtek Solution: Adopt two-component automatic mixing and dispensing equipment to precisely control the ratio of resin and curing agent (2:1 by volume), ensuring uniform mixing and no waste; adjust the dispensing volume according to the bonding gap. For 0.1-0.2mm gap, the dispensing volume per point is controlled at 0.01-0.02mL. Utilize the high viscosity to achieve uniform gap filling, which can reduce adhesive waste by more than 40%, and save manual mixing and excess cleaning processes.

💰 Cost Reduction Tip 2: Flexibly Select Curing Methods to Reduce Energy Consumption

Traditional Method: Regardless of the production rhythm, heating curing is adopted, resulting in high energy consumption and increased production costs.

Assembtek Solution: Flexibly select curing methods according to the production rhythm: room temperature curing (complete curing in 24 hours) is adopted for small-batch and slow-rhythm production, no heating is required, reducing energy consumption; heating curing at 65℃ (complete curing in 12 hours) is adopted for large-batch and fast-rhythm production, improving production efficiency and balancing efficiency and energy consumption costs; tests show that reasonable selection of curing methods can reduce energy consumption by more than 30%.

⚙️ Verified Automated Dispensing and Mixing Parameters

💡 Mass Production Process Tips

•         Mixing Control: It is strictly prohibited to mix more than 4kg to avoid excessive heat generated during mixing leading to premature curing of the adhesive; after mixing, it must be used up within the 120-minute working life. Unused mixed adhesive is strictly prohibited to be poured back into the original bottle to avoid contamination.

•         Substrate Treatment: Metal substrates are preferably degreased and etched/sandblasted, which can improve the bonding strength by more than 30%; plastic substrates (such as PC) do not need special treatment, just clean the surface; wood substrates need to be dried in advance, and the moisture content is controlled below 10%.

•         Bonding Gap: Strictly control at 0.1-0.2mm. Too large a gap will easily lead to adhesive layer shrinkage and strength reduction, and too small a gap will not achieve uniform gap filling, affecting the bonding effect; positioning tools can be used to control the gap.

•         Post-Curing Treatment: After curing, if there is excess cured adhesive layer, it can be removed by mechanical grinding. Avoid using strong solvents to prevent damage to the substrate and adhesive layer; after curing, the bonded parts need to stand for 2 hours before subsequent processing or testing.

🧊 Storage and Service Life Optimization (Core Cost Reduction Point)

•         Optimal Storage Conditions: Dry environment at 8-21℃, strictly prohibited below 8℃ or above 28℃, otherwise it will affect the adhesive performance (such as viscosity change, abnormal curing speed); it must be sealed during storage to avoid premature contact between resin and curing agent, and kept away from fire sources and oxidants.

•         Production Line Management: Resin and curing agent are stored separately and mixed in proportion before use; opened resin and curing agent must be sealed and stored, and it is recommended to use them up within 7 days to avoid adhesive failure caused by moisture absorption or oxidation; mix the adhesive on demand to avoid waste caused by excessive mixing.

•         Shelf Life Management: The shelf life of unopened products under optimal storage conditions is 12 months. It is strictly prohibited to use expired products to avoid bonding failure caused by reduced adhesive performance, which increases rework costs and material waste.

Module 5: Compliance & Quality

•         Material Specification Certification: Complies with Henkel LOCTITE® Material Specification (LMS, Version April 10, 2006). Each batch of products is provided with a Certificate of Analysis (COA), which is traceable to ensure product consistency and stability.

•         Test Standards: All mechanical and thermal performance data are tested in accordance with international standards, including ISO 4587 (Shear Strength), ISO 527-2/3 (Tensile Strength, Elongation at Break), ISO 868 (Shore Hardness), ASTM E 1640 (Glass Transition Temperature).

•         Environmental Compliance: The product meets industrial adhesive environmental protection standards, no harmful volatile substances exceed the standard. During use, strictly follow the SDS safe operation specifications, and it can be safely used in various industrial production scenarios.

•         Usage Restrictions: Strictly prohibited for use in pure oxygen or oxygen-enriched environments, and shall not be used as a sealant for chlorine or other strong oxidizing substances to avoid safety hazards; not suitable for bonding scenarios that are long-term immersed in strong acid or strong alkali environments.

•         Environmental Tolerance: Passed 1000-hour thermal aging test at 87℃, as well as environmental tests such as 22℃ water, 38℃ 95% humidity, 10W30 engine oil, and unleaded gasoline. The maximum bonding strength retention rate can reach 125%, suitable for complex industrial environments.

•         Assembtek Process Verification: Passed 1000-hour thermal aging, damp-heat aging tests and various chemical environment tests, and the bonding strength retention rate meets industry standards; at the same time, the stability of automated dispensing and mixing parameters has been verified, which can be directly connected to the mass production line to ensure mass production quality.

Module 6: FAQ

Q1: Is LOCTITE EA E-120HP required to be cured by heating? How is the effect of room temperature curing?

A: Heating curing is not mandatory; it supports both room temperature curing and heating curing. At room temperature (25℃), complete curing can be achieved in 24 hours, and the shear strength can reach more than 85% of that of heating curing, meeting the needs of conventional industrial assembly; heating curing (65℃, 12 hours) can make the strength reach the peak, suitable for high-demand structural bonding scenarios such as aerospace, and can be flexibly selected according to production needs.

Q2: The working life of the mixed adhesive is 120 minutes. Can it be used continuously if not used up?

A: It is not recommended to use it continuously. 120 minutes is the optimal operable time of the adhesive. After exceeding this time, the adhesive will gradually cure and the viscosity will increase, making dispensing more difficult, and the performance of the cured adhesive layer will decrease significantly (strength decreases by 20%-30%), which is likely to cause bonding failure; unused mixed adhesive must be discarded in time and strictly prohibited to be poured back into the original resin or curing agent bottle to avoid contamination.

Q3: Is a primer needed when bonding different substrates?

A: A primer is not needed for most substrates: for metals (aluminum, steel), PC, glass, wood and other substrates, they can be directly bonded only by cleaning the surface (degreasing, dust removal); for low surface energy plastics such as nylon, it is recommended to use LOCTITE special primer or plasma treatment, which can improve the bonding strength by 3-5 times and avoid bonding detachment; PE/PP substrates are not recommended to use this product, as the bonding effect is poor.

Q4: What is the chemical resistance of the adhesive layer? Can it be used in scenarios contacting engine oil and gasoline?

A: Excellent chemical resistance, can be used in scenarios contacting engine oil and gasoline. Tests show that after soaking in 10W30 engine oil at 87℃ for 1000 hours, the bonding strength retention rate is 120%; when soaked in unleaded gasoline, the strength retention rate is 105%; it can also withstand organic solvents such as acetone and isopropanol, suitable for bonding scenarios of industrial equipment, auto parts and other contact chemical media.

Q5: What is the impact of bonding gap on the adhesive layer strength? How to control the gap?

A: The bonding gap has a significant impact on the strength: the optimal gap is 0.1-0.2mm, at this time the adhesive layer is uniform and the force is reasonable, and the strength reaches the peak; if the gap exceeds 0.5mm, the shrinkage of the adhesive layer increases, which is prone to cracks, and the strength decreases by more than 30%; if the gap is less than 0.1mm, uniform gap filling cannot be achieved, which is prone to lack of adhesive and virtual bonding. Positioning tools, gaskets and other tools can be used to control the gap to ensure bonding quality.

Q6: What impact will improper storage temperature have on the adhesive performance?

A: If the storage temperature is lower than 8℃, the viscosity of the resin will increase, the activity of the curing agent will decrease, the curing speed will slow down after mixing, and even incomplete curing may occur; if the storage temperature is higher than 28℃, the aging of the adhesive will be accelerated, the shelf life will be shortened, and the resin and curing agent may react in advance, leading to adhesive failure; it is recommended to store strictly according to the optimal condition of 8-21℃ to ensure stable adhesive performance.

Q7: Can the cured adhesive layer withstand high temperature environment? What is the upper limit of long-term service temperature?

A: The cured adhesive layer has good high temperature resistance, the glass transition temperature is 90℃, and the upper limit of long-term service temperature is 87℃. After long-term aging at 87℃ for 1000 hours, the strength retention rate is still 100%; it can withstand high temperature of 100℃ in the short term. After exceeding 100℃, the adhesive layer will gradually soften and the strength will decrease. It is not recommended to use it in long-term high temperature (exceeding 87℃) scenarios.

Module 7: Resources & CTA

Optimize your production process with in-depth technical data:

📄 [Download LOCTITE® EA E-120HP TDS Technical Data Sheet]

Obtain detailed curing energy curves, modulus data, shear strength reports of different substrates and complete process parameter guidance.

🧪 [Download Complete SDS/MSDS Safety Data Package]

Review key safety information on flash point, chemical stability, safe operation specifications and environmental compliance.

👉 [Button: Consult Application Engineer] Our laboratory can provide free substrate bonding tests, mixing and dispensing parameter optimization and post-curing strength verification services.