MECA-based Cyanoacrylates: a strong bond with negligible-blooming bonding

Sep 21, 2020 | Fasteners & adhesives

For many years, blooming has been a key point of discussion for those who use traditional, cyanoacrylate-based, instant engineering adhesives in the manufacturing industry. The term “blooming” refers to the white staining of parts near where the adhesive is applied. This staining occurs when certain fast-reacting cyanoacrylate adhesives, comprised of volatile ingredients, create significant vapor pressure and cause the volatile ingredients to condense on part surfaces and stain them. In time, these blooming stains can detract from the overall appearance of the assembled parts. In some cases, blooming is not an issue, as the assembled part may be subsequently painted or finished. However, when manufacturing high-end goods, such as lipstick cases, mobile electronics, lenses, perfume bottles and glass covers, product aesthetics play a crucial role in determining consumer appeal and a product’s success. The white staining from blooming, which is particularly noticeable on black or shiny parts, can prove detrimental to the end-use product’s perceived quality and taint the brand’s image.

This article takes a close look into blooming as well as other key disadvantages to commonly-used, cyanoacrylate-based, instant engineering adhesives and details why a new solution is best.
ECA-Based Cyanoacrylates
Ethyl Cyanoacrylate (ECA)-based instant engineering adhesives have become the mainstay of the instant adhesives industry and have been well accepted and well utilized for many years. In addition to providing strong, instant bonds to many substrates, they are considered cost effective to produce. However, ECA-based adhesives are volatile and are susceptible to blooming.
What Causes ECA-Based Adhesives to Bloom?
Not all ECA-based instant adhesives cure within the same timeframe. Cure rate, i.e., the time it takes for the adhesive to go from a liquid to a solid, is dependent on the adhesive’s formulation type and the nature of the materials being assembled. However, this cure rate directly impacts the extent of blooming that occurs, which can be difficult to regulate. For example, ECA-based adhesives that are formulated with an increased amount of volatile ingredients are susceptible to blooming more than others simply due to the nature of their formulation. Further, ECA-based adhesives that take longer to cure than others inevitably generate more blooming. Manufacturers can address the extent of blooming by using accelerants or additional agents, such as spray-on primers. However, these tactics increase complexity among other issues.
Even when manufacturers work to regulate the blooming, ECA-based adhesives will still bloom to some extent as the adhesive unavoidably gets compressed during product assembly. This issue becomes especially hard to manage when bonding small, delicate parts, such as miniature camera pieces and mobile electronics.
This difficulty is compounded by the fact that these instant engineering adhesives require a delicate balance of adhesive volume used and the accuracy with which they are dispensed and applied in order to achieve the ideal bond, regardless of blooming. Manufacturers need to use special, high-accurate dispensing equipment systems with ECA-based adhesives. Further, ECA-based adhesives also yield an acrid odor, which can pose more challenges for workers.
Therefore, while these adhesives have been the traditionally-used technology for instant engineering adhesives, it’s important for the industry to understand the value in switching to Methoxyethyl Cyanoacrylate (MECA)-based instant engineering adhesives.
MECA-Based Cyanoacrylates
Like ECA-based cyanoacrylates, MECA-based cyanoacrylates offer rapid, strong bonds on most materials. Cost competitive, they also overcome key disadvantages inherent with ECA-based technology.
In particular, these innovative instant engineering adhesives offer manufacturers a negligible-blooming bonding option. Diminished product aesthetics and perceived quality are no longer an issue. This is because MECA-based adhesives possess significantly reduced volitively in their formulation when compared to ECA-based solutions.
Additionally, MECA-based adhesives eliminate the need for special, high-accuracy dispensing equipment. They are easy to apply and enable manufacturers to seamlessly address the balance of adhesive volume and application accuracy. Further, MECA-based adhesives are odorless, which eliminate worker safety and challenges.
Bostik’s innovative line of MECA-based, instant engineering adhesives, Born2Bond, make it easy for manufacturers of high-end goods to quickly assemble parts without compromising on quality and aesthetics. Available in a range of formulations, they facilitate faster, smarter production processes while also prioritizing worker safety and overall sustainability.


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