STRUCTURAL ADHESIVE

Product Features

① Bearing and Stress Distribution: Unlike ordinary adhesives, structural adhesives are specifically designed to form bearing joints, which can evenly distribute stress across the entire bonding surface, thereby reducing stress concentration and enhancing the fatigue resistance and long-term reliability of the joint.

② Alternative to Traditional Connections: In many designs, the strength of structural adhesives is sufficient to replace or strengthen rivets, bolts, and welding, while avoiding the stress concentration and material damage caused by drilling.

③ Skilled in Connecting Different Materials: It can reliably bond metals, composites, plastics, glass, and other substrates, solving the problem of difficult handling of different material combinations in traditional welding.

④ Formula Can Be Optimized Specifically: Different chemical systems have their own focuses - epoxy types pursue the highest strength and temperature and chemical resistance; acrylic types focus on rapid curing and impact resistance; polyurethane types achieve a balance between flexibility and adaptability to different materials.

⑤Lightweight and Design Flexibility: Without fasteners and drilling, it helps reduce structural weight and provides greater freedom for design.

Usage and Installation (Precautions)

The final performance of the structural adhesive is highly dependent on the construction specifications. The key steps are as follows:

① Surface Treatment is the Key to Success: The surface to be bonded must be clean, dry, and free of oil. It is recommended to clean with acetone or isopropyl alcohol and perform appropriate roughening; if necessary, use the corresponding accelerator to accelerate curing.

② Strict Control of Glue Layer Thickness: The glue layer thickness should typically be controlled between 0.03 mm and 0.075 mm. Too thick or too thin will affect the final strength.

③ Two-component Needs Proportional Mixing: For two-component products, it is necessary to strictly follow the specified mass ratio or volume ratio (such as 1:1, 4:1, etc.) to mix evenly. Inconsistent mixing will result in incomplete curing.

④ Assembly and Curing: After applying the glue, it should be closely adhered and appropriately clamped until the initial positioning is achieved. Complete curing usually takes 24 hours at room temperature to reach maximum strength. Heating can also be used to accelerate curing (such as 80°C for 2 hours).

⑤Environmental and Operating Restrictions: The construction environment should be controlled at 5°C–35°C, avoiding rain, strong winds, and direct sunlight; when the temperature is low, choose low-temperature curing models or preheat the adhesive appropriately. Unmixed excess glue must be sealed and stored.

How is the Structural Adhesive Manufactured?

The essence of the manufacturing of structural adhesives is formula design and precise mixing, especially for two-component products, where the active components must be strictly isolated and mixed proportionally at the time of use.

A/B Components Prepared Separately: Taking acrylic-based two-component structural adhesives as an example, the A component usually contains acrylic monomers, toughening agents (such as SBS rubber, nitrile rubber), stabilizers, etc.; the B component contains epoxy resins, oxidants (such as peroxydiphenylformaldehyde), plasticizers, etc. Both components must be prepared separately in independent containers.

Step-by-step Ingredient Addition and Temperature Control Mixing: During preparation, add the raw materials to the reaction vessel in sequence and strictly control the temperature and mixing time. For example, the A component may be first dissolved in 70°C to mix the rubber-based toughening agent, then cooled to 40°C to add the active monomers and other additives; the B component may be mixed at a lower temperature (15°C–30°C) to avoid premature decomposition of the peroxide.

Vacuum Defoaming and Filling: After the mixture is uniform, it is usually subjected to vacuum defoaming treatment to remove the air bubbles introduced during mixing, ensuring the density of the adhesive layer. The final product is then filled separately and mixed proportionally at the time of use.

Quality and Assurance: Backed by verifiable "Conservative Design Criteria"

The core risk of the structural adhesive is not "whether it can stick well", but "whether it will fail in long-term bearing". Our quality logic is based on a key benchmark: the design allows stress to reach 1/20 of the standard strength, which is the most conservative design criterion for structural adhesives in the EU ETAG 002. This means that we reserved sufficient safety margins during the product development process, rather than presenting the laboratory peak strength as a selling point.

In terms of durability, we verified three hard indicators according to the framework of ETAG 002: the tensile shear strength decreased by no more than 50% at three temperature points of 23°C, 80°C, and -20°C; the bonding strength retention rate after water immersion for 7 days was not lower than 75%; and the gel did not become brittle or powder-like after 2000 hours of xenon lamp aging. These are not "optional tests", but preconditions for product release. For the purchaser, this means that the performance of the delivered product on the customer's production line is supported by traceable accelerated aging data, rather than relying on "it seems fine based on experience".

Differences from other products: Not selling "universal glue", but "predictable trade-offs"

The most common misleading practice in the structural adhesive market is packaging the advantages of a certain chemical system as universal advantages. Our positioning is exactly the opposite: clearly defining the performance boundaries of each system and allowing customers to make choices based on their knowledge.

Using actual performance data of the three major systems of epoxy, acrylate, and polyurethane as a reference:

• Indicator Epoxy Acrylate Polyurethane

• Tensile strength 47 N/mm² 20 N/mm² 4.5 N/mm²

• Break elongation 3.3% (rigid, brittle) 17% 35% (high flexibility)

• Elastic modulus 2312 N/mm² 900 N/mm² 25 N/mm²

Epoxy provides the highest bearing strength, but has a low break elongation, and is prone to accumulate interface stress in joints between dissimilar materials with thermal expansion mismatch; Acrylate achieves a compromise between strength and toughness, but has weaker vibration and extreme temperature resistance than epoxy, and has more obvious curing shrinkage; Polyurethane has the best flexibility, suitable for scenarios that require absorbing deformation or bonding low surface energy substrates, but has the lowest absolute strength.

Application scenarios:

We suggest that customers lock in the product series based on the consequences of joint failure:

• Safety-critical joints (gluing curtain wall glass to metal, building structure reinforcement): Failure in these scenarios could lead to falls or structural damage. Such scenarios can only use products that have been verified according to ETAG 002 or EN 1504 series and have a complete ETA assessment or CE mark, and are subject to batch sampling inspection with on-site stripping tests (Hg test).

• Fatigue and dynamic load joints (automotive components, vibration parts of industrial equipment): Prioritize break elongation and impact resistance. Polyurethane or modified epoxy is more suitable than standard epoxy; although acrylate cures quickly at initial stage, its fatigue performance under continuous vibration needs to be carefully evaluated.

• Joints between dissimilar materials and thermal expansion mismatch (metal-plastic, composite-metal, electronic device packaging): The polyurethane system with low modulus and high break elongation is usually better at absorbing interface thermal stress than rigid epoxy. The adaptability of acrylate to oily metal surfaces is its differentiation advantage in automotive and general industrial applications.

• Fast-paced production lines: The epoxy and polyurethane systems have a rhythm of 5 minutes initial curing, reaching a higher strength in 30 minutes, and complete solidification in 24 hours, suitable for assembly scenarios with hard requirements for online production speed; acrylate is more suitable for applications that prioritize final strength or flexibility.

Packaging and logistics: Make "compliance with dangerous goods regulations" part of the certainty of delivery

Structural adhesives contain flammable solvents or reactive components, and the vast majority are classified as dangerous goods in international transportation. The UN number is commonly UN 3082 (environmentally harmful liquid) or classified as Class 3 flammable liquid based on flash point. This is not a gray area that can be "handled as general cargo" - the inspection by customs at the destination port and airlines will not release the goods simply because the freight forwarder says "it's fine".

FAQs

Q1: Will the curing time be shortened or ineffective due to high temperatures during sea transportation?

Structural adhesives have shelf life and curing behavior that are sensitive to heat history. If the product experiences high-temperature dry compartments during sea transportation, there may be viscosity changes or partial pre-polymerization. Our response: For heat-sensitive product lines, we default recommend a temperature control plan and mark the storage conditions and recommended re-inspection items for this batch in the COA. After the customer receives the product, they can first conduct a small sample curing comparison and then put it into the production line.

Q2: What is the level of your strength data compared to the competitors?

The data we provide is comparable data corresponding to the standard, not isolated maximum values. For example, in the acrylate system, the shear strength can reach over 20 MPa, with initial curing in 5 minutes and complete curing in 24 hours. However, we will also explain the corresponding substrate, test standard, and temperature conditions for this data to avoid customers mistakenly using the peak value under one condition to another situation.

Q3: Are the surface treatment requirements more stringent than those of the competitors?

Not more stringent, but more explicit. The final strength of the structural adhesive highly depends on the surface condition. Our technical materials will clearly state: cleaning (acetone/isopropyl alcohol), roughening by grinding, and using the corresponding primer when necessary, rather than simply saying "a clean surface is fine". Stating the requirements upfront is much cheaper than tracing costs after problems occur on the customer's production line.

Q4: Can you provide the hazardous materials documents required for customs clearance at the destination port?

OK. The standard accompanying documents package includes MSDS (containing flash point, UN number, transportation classification), dangerous goods certificate, and sample of dangerous goods labels. We can also provide additional declarations or coordinate with customs clearance agents in accordance with the requirements of the destination country.

Q5: How are the minimum order quantity and delivery time controlled?

This depends on the specific system and packaging specifications. For two-component products, since the A/B components need to be separately packaged, the MOQ is usually higher than that of single-component products. Regarding the delivery time, for regular systems, the production scheduling is usually locked after receiving the confirmation of the packaging plan and dangerous goods declaration materials; for custom formulations or orders with special certification requirements, additional time for type inspection or supplementary testing needs to be reserved. It is recommended to clarify the target market, substrate combination, and whether specific certifications are required during the inquiry stage. Based on this, we can provide a committed delivery time range instead of first reporting a "reference delivery time" and repeatedly postponing it.