How to Solve the Problem of Insufficient Adhesive Adhesion at Low Temperatures: A Practical Guide for Manufacturers

Photo: Owlie Harrington / Unsplash

Manufacturing facilities often face the problem of insufficient adhesive bonding at low temperatures, whether in winter conditions or in cold storage areas. Adhesives based on epoxies, polyurethanes, or acrylates can lose up to 50% of their strength at temperatures below 10 °C, leading to joint failures, increased waste, and downtime. The cause is not always the wrong choice of adhesive—it is often a combination of unsuitable application conditions, inadequate surface preparation, or missing additives. This article provides specific steps to diagnose and resolve the issue through technological adjustments and chemical modifiers.

Why Adhesion Fails at Low Temperatures: Root Causes

Insufficient adhesive adhesion at low temperatures is a common problem in production facilities, especially during winter months or when working in cold warehouses. The main cause is the slowing down of chemical reactions that ensure adhesive curing. Most reactive adhesives (e.g., epoxy, polyurethane, or acrylate systems) require a temperature above 10 °C for optimal polymerization. At temperatures below 5 °C, the reaction rate significantly decreases, leading to insufficient curing and, consequently, weaker adhesion. Another factor is the increased viscosity of adhesives, which impairs surface wetting and prevents uniform adhesive distribution.

In addition to chemical aspects, the physical properties of substrates also play a role. Materials such as metals or plastics contract at low temperatures, which can cause microcracks in the bonded joint. Moisture that condenses on cold surfaces also negatively affects adhesion, particularly in the case of hydrophilic adhesives. The problem often becomes apparent only after several hours or days, when the joint fails under load. Identifying the specific cause is the first step toward an effective solution.

Choosing the Right Adhesive: How to Adapt the Formulation to Conditions

Solving the adhesion problem at low temperatures begins with selecting the appropriate type of adhesive. For cold environments, special "winter" formulations containing curing accelerators or low-temperature catalysts are ideal. For example, some polyurethane adhesives are modified to react even at temperatures around 0 °C. Epoxy systems can be enriched with flexibilizers to compensate for material contraction. It is also important to consider the temperature resistance of the adhesive after curing—some types lose strength during repeated freezing and thawing.

When selecting an adhesive, it is crucial to consult the manufacturers' technical data sheets and verify whether the product is certified for use at low temperatures. Some adhesives require preheating to room temperature before application, which may be impractical under operational conditions. An alternative is two-component adhesives with rapid strength development, allowing handling of bonded parts within minutes. It is always necessary to test the adhesive under real conditions, as laboratory results may differ from operational practice.

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Surface preparation and bonding process optimization

Even the highest-quality adhesive will fail if the surface is not properly prepared. At low temperatures, it is crucial to remove all moisture, grease, and dirt that prevent perfect contact between the adhesive and the substrate. Surfaces should be heated to at least 15 °C before bonding, for example, using hot-air guns or infrared heaters. This improves the wetting properties of the adhesive and accelerates its curing. For metals, it is important to remove oxides and corrosion products, ideally through mechanical sanding or chemical degreasing.

The bonding process should take place in a controlled environment where stable temperature and humidity can be maintained. If this is not possible, portable heating boxes or insulating covers can be used to protect the bonded joint from rapid cooling. It is also important to observe the recommended curing time—at low temperatures, this may be several times longer than under standard conditions. Accelerating the process using elevated temperatures (e.g., 40–50 °C) is possible but must be done carefully to avoid material deformation or the creation of internal stress in the bonded joint.

Practical Solution: A Case Study from Production

One Czech manufacturing plant faced frequent complaints due to failing bonded joints during the winter season. The issue involved the assembly of metal parts using a two-component epoxy adhesive. Analysis revealed that the temperature in the assembly hall dropped below 5 °C, which slowed down the adhesive curing process and impaired adhesion. The solution involved implementing several measures: preheating the bonded parts to 20 °C, using a modified adhesive with a curing accelerator, and installing local heaters in the assembly zone.

After implementing the changes, the number of complaints decreased by more than 80%. The key factor in this success was the systematic testing of the new process—first in the laboratory, then in pilot production. Equally important was the training of staff to follow the new procedure and monitor temperature and humidity during bonding. This case demonstrates that the combination of proper material selection, process optimization, and strict adherence to technological parameters can effectively resolve adhesion issues even in challenging conditions.

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Effect of Temperature on Adhesive Viscosity and Wettability: Key Parameters for Successful Bonding

Low temperatures significantly affect the rheological properties of adhesives, particularly their viscosity and wetting ability. When the temperature drops below 10 °C, the viscosity of most polymer-based adhesives (e.g., epoxies, polyurethanes, or acrylics) increases by up to 50–100 %, which prevents their even distribution across the surface. This reduces the contact area between the adhesive and the substrate, leading to insufficient adhesion. Wetting ability – the adhesive’s capacity to penetrate the surface microstructure – is also limited at low temperatures because the surface tension of liquids increases. This is especially true for metal or plastic surfaces with low surface energy, where the adhesive forms droplets instead of a uniform film.

To compensate for these effects, it is necessary to adjust the application parameters. Before bonding, the adhesive can be preheated to 20–25 °C, which reduces its viscosity and improves wetting. For two-component adhesives, it is critical to maintain the correct mixing ratio even at low temperatures, as slower reaction kinetics can lead to incomplete curing. In some cases, it is advisable to use adhesives with modified rheology that retain their fluidity even at temperatures below 5 °C. It is also important to consider the temperature of the substrate itself – if the material is colder than the adhesive, local solidification and the formation of weak spots in the bonded joint may occur.

Accelerators and Modifiers to Speed Up Curing in Cold Environments

Under low-temperature conditions, the reaction rate of adhesive curing slows down significantly, prolonging the time required to achieve full joint strength. For epoxy adhesives, the curing time at temperatures below 10 °C can be 2–3 times longer than at the standard 23 °C. The solution lies in accelerators – additives that speed up the chemical reaction without negatively affecting the final mechanical properties of the joint. For epoxies, tertiary amines or imidazoles are often used, while for polyurethanes, organotin compounds or amines are employed. The dosage of accelerators ranges from 0.5–3 % of the adhesive’s weight, with the exact amount depending on the type of adhesive and the desired curing speed.

Another option is modifiers that improve flexibility and bond resistance at low temperatures. For example, phthalate- or adipate-based plasticizers reduce the brittleness of cured adhesive, while elastomeric additives (e.g., SBS or SIS copolymers) increase impact resistance. When selecting modifiers, it is important to ensure compatibility with the adhesive and substrate to prevent separation or migration of additives. In practice, a combination of accelerators and modifiers has proven effective, ensuring rapid curing and sufficient bond strength at temperatures below freezing.

Quality Control and Adhesive Testing Under Real-World Conditions: How to Prevent Production Defects

Before deploying an adhesive in production, it is essential to test it under conditions as close as possible to real-world operation. Standard laboratory tests at 23 °C and 50 % relative humidity do not reflect adhesive behavior at low temperatures, so it is necessary to simulate specific operating conditions. A fundamental test is measuring bond strength in tension or shear according to applicable standards, with samples tested after various curing times (e.g., 24, 48, and 72 hours) at temperatures of 5 °C, 0 °C, and -10 °C. It is also important to monitor cohesive and adhesive failures – if the adhesive detaches from the substrate, the issue lies in adhesion, while cracks within the adhesive indicate insufficient cohesion.

In production, it is advisable to implement regular quality control of bonded joints using non-destructive methods such as ultrasonic testing or thermography. These methods detect internal defects such as bubbles, uncured areas, or cracks without destroying the joint. For critical applications, it is recommended to maintain records of temperature, humidity, and curing time for each bonded part, enabling rapid identification of the causes of any defects. In cases of recurring adhesion issues, surface analysis can be performed using scanning electron microscopy (SEM) or X-ray photoelectron spectroscopy (XPS) to identify contaminants or insufficient surface activation.

Need to optimize bonding in challenging conditions?

GCG Group supplies a wide portfolio of additives for adhesives and sealants, including modifiers for low-temperature applications. For each raw material, we provide detailed technical data sheets and safety documentation (SDS) and assist in selecting the right solution for your specific operating conditions. Contact us – or browse our catalog of over 1,300 products right away.