Rubber is an elastic polymer composed primarily of isoprene (C5H8) units. The molecular structure of rubber gives it unique properties such as elasticity and flexibility. However, the chemical composition and surface characteristics of rubber can present some challenges for effective adhesion when bonding rubber.
Successful and effective bonding of rubber is critical to ensuring durable and long-lasting bonds on a variety of projects. This guide explores advanced techniques and highlights the most effective adhesives to help you achieve professional results in your rubber bonding or repair projects.
1. Types of Rubber & Rubber Adhesives
The choice of the right adhesive is crucial to ensure an effective and durable bond. Each individual adhesive has specific characteristics that make it more or less suitable for the task at hand depending upon the substrate, application, and environmental conditions. Below, we review the most common types of adhesives used when bonding rubber materials, highlighting their advantages and ideal applications.
- Cyanoacrylate Adhesives: Known for their ability to quickly bond different materials, including rubber, cyanoacrylate adhesives are ideal for quick and precise repairs due to their fact cure time and high initial strength.
- Silicone Adhesives: Recommended for applications that face extreme conditions such as high temperatures, humidity, or exposure to chemicals. They guarantee a durable and flexible bond.
- Polyurethane Adhesives: Flexible and able to withstand movement and vibration, these adhesives are ideal for industrial and automotive applications where durability is paramount.
- Epoxy Adhesives: Due to their high strength, durability, and resistance to chemicals, solvents, and temperature extremes, epoxy adhesives are ideal for applications requiring a strong structural bond.
- Acrylic Adhesives: Fast drying, easy to apply, and offer good adhesion to porous materials, they are particularly effective in applications where fast curing and good weather resistance are needed.
- Contact Adhesives: Perfect for large, flexible surfaces such as shoe soles or hoses, contact adhesives require application to both surfaces and a drying time before bonding the parts together.
2. Selecting the Right Adhesive
The choice of adhesive depends both on the type of rubber and the environment in which it will be applied. Consider the following factors:
- Specific type of rubber: The chemical composition of the material may affect compatibility with certain adhesives.
- Conditions of use, i.e. temperature, humidity, and chemical exposure.
- Cure time required: Some more complex projects may require adhesives with longer working times.
- Flexibility needed in bonding: Some applications require some flexibility in bonding to be maintained.
3. Surface Preparation
- Clean surfaces thoroughly with isopropyl alcohol to remove grease, dust, or other contaminants.
- Avoid using acetone, as it may damage certain types of rubber.
- Consider lightly sanding the surface to increase the contact area, especially on harder rubbers.
4. Advanced Application Techniques
- Use fine application tools to evenly distribute the adhesive.
- For cyanoacrylates, a small drop is usually sufficient.
- In the case of contact adhesives, apply to both surfaces and wait until dry before bonding.
- Some elastomeric formulations may require the incorporation of a primer compatible with the chosen system prior to adhesive application.
5. Curing Process
- Follow the manufacturer’s instructions for drying time.
- Apply adequate pressure during curing using presses, clamps, or weights as required.
- Maintain the recommended temperature and humidity conditions to ensure optimum curing.
6. Recommended Products
Permabond is an internationally recognised brand providing high-quality adhesives for a wide range of material bonding, including rubber. Below, we discuss some highlights from the Permabond range.
- Permabond ET5429: Two-component structural adhesive for vulcanised rubber and elastomers.
- Permabond 105: Fast-curing cyanoacrylate for instant repairs.
- Permabond 130UV: UV curable cyanoacrylate for applications requiring fast cure.
- Permabond TA4611: Structural adhesive for low surface energy substrates.
Example – Nitrile rubber
(NBR or XNBR): Nitrile rubber is a widely used synthetic rubber due to its flexibility and versatility, including its low surface energy and low cohesive strength. Nitrile rubber is commonly used in hoses, gaskets, O-rings, conveyor belts, automotive belts, disposable gloves, cable sheathing, and printing rollers. For this material it is recommended to use a cyanoacrylate adhesive, such as Permabond 105.
7. Expert Tips & Tricks
- Always test small areas before final application.
- For fast drying adhesives such as cyanoacrylates, it works quickly and accurately.
- In case of excess adhesive, wipe it off immediately according to the manufacturer’s recommendations.
8. Safety & Precautions
- Always work in well-ventilated areas.
- Use personal protective equipment according to the manufacturer’s recommendations.
- Always follow the manufacturer’s instructions for use and storage.
9. Troubleshooting
- If the bond fails, check the cleanliness of the surface and the compatibility of the adhesive with the specific type of rubber substrate.
- Be sure to apply sufficient pressure during curing.
- Check that the environmental conditions — temperature or humidity — are suitable for the adhesive used.
Antala: Your Trusted Advisor
Successful rubber-to-rubber bonding depends on selecting the right adhesive, meticulously preparing the surfaces, and applying advanced techniques with precision. For more information about Permabond products and the best bonding techniques for rubber applications, visit our website or contact our technical team on +44 161 494 1345, where your local expert will offer specialised advice.