FEATURE


FASTENINGS & ADHESIVES


Your cYanoacrYlate adhesive questions answered Cyanoacrylate adhesives (CAs) have been


around since the 1950s, becoming a common household product in the 1970s, and are


typically known as superglue. Peter Swanson, managing director of adhesives specialist


Intertronics, explains how the cyanoacrylate adhesives landscape is changing and how historic compromises have been overcome


which represents a huge step forward. Born2Bond materials are manufactured


using a new ‘crackless’ process, which means it is possible to overcome many of the issues associated with methoxyethyl cyanoacrylates, while retaining the benefits of ECA products.


can You give me an overview of the Born2Bond range?


This new range of patented CA products overcome the speed issues of a traditional MECA product, but still offer the stability and strength of an ECA product – which means fewer compromises for manufacturers. Some implications for production include


C


yanoacrylate adhesives (CAs) provide fast curing and high-strength bonding to various substrates without the need for


a separate heat or energy source. Today, manufacturers rely on them to bond plastic, metal, ceramic, rubber, wood and other substrates in many types of assemblies.


what compromises are tYpicallY associated with cYanoacrYlates and how has this limited their use?


While all adhesive selection is about trade-offs to some extent, cyanoacrylates have historically come with a whole host of compromises – including brittleness, limited temperature and moisture resistance, and other physical disadvantages. There are multiple monomers used to


formulate CAs with different properties. The most common is ethyl (ECA), but ECAs are prone to blooming – an unwanted chalky white residue on the surface of a part. ECAs also typically have a harsh odour, can be an irritant, and require ventilation. While adhesives based on methoxyethyl (MECA) monomers are less volatile than those based on ECAs, they often compare poorly in cure speed, strength and costs. Due to the downsides, manufacturers of


high-technology products and those in highly- regulated markets may not have considered CAs for their more demanding structural bonding applications.


2


what is Blooming and whY does it occur?


CAs cure very rapidly, achieving fixture strength in seconds and full cure in around 24 hours. The chemistry is quite volatile; blooming is a side effect of this. It occurs when energy from the curing reaction promotes the release of unreacted cyanoacrylate monomers into the air, which condense and fall onto the surface as white crystals or flakes. The resulting by-product is known as blooming, frosting or blushing. While blooming does not affect bond


integrity, it is undesirable if aesthetics are important, such as with jewellery, or if the presence of blooming might imply a quality problem to the customer – for example, when making medical devices, instrumentation or consumer electronics. Cyanoacrylate adhesives based on


methoxyethyl (MECA) monomers are often marketed as ‘low odour, low bloom’ formulations. However, they can compare poorly in terms of cure speed, strength and cost, and so their use involves compromises.


can You explain how the market has changed to tackle the compromises You mentioned aBove?


In the last 15 years, there has been little innovation in cyanoacrylate chemistry. That is, until the launch of the Born2Bond range,


3 DESIGN SOLUTIONS NOVEMBER 2021


higher adhesive strength, the ability to gap fill, and operating temperatures of up to 120°C. There are low odour, low bloom, formulations without performance compromise, fast cure and low irritability. High impact resistance and toughness feature, and one product is flexible with >200% elongation. The range features safer products, with fewer or no label hazard symbols. The full product range includes three lines:


• Born2Bond Ultra, which is low blooming, low odour, fast curing, non-irritant and offers increased flexibility and instant adhesion on multiple surfaces.


• Born2Bond Light Lock, a dual cure product type that cures very fast with either UV light for visible or exposed bondlines, or interfacially as normal. It offers low bloom and odour, is non-irritant, and tack free. It is ISO 10993 tested and suitable for consideration in the assembly of medical devices.


• Born2Bond 2K products come in a two-part cartridge and include: Structural, which offers a short fixture time,


gap filling, high toughness, temperature resistance of up to 120°C and a significantly longer open time than alternative products. Repair, has high bond strength, offers gap


fill and is significantly faster than alternative products, which means it is sandable or paintable in a few minutes And, finally, Flex, which offers elasticity and instant bonding.


Intertronics T: 01865 842842 www.intertronics.co.uk


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