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Pre-Mixed and Frozen Resins – The Convenient Choice for Users of Two Component Adhesives

Two component adhesives undoubtedly provide a strong, reliable bond, however some end users may be put off by the hassles of the manual mixing process…

When mixing the two components, the reaction typically begins instantly, meaning that users must work ‘against the clock’ to ensure that the mixed adhesive does not become so viscous that it cannot be applied, and also to avoid decreasing the bond strength due to the diminished wetting of the surface. Special care must also be taken during the mixing process to maintain the prescribed ratio of resin and hardener, since even a small deviation from the specified mix ratio can prevent the adhesive from curing properly. Furthermore, because of the precise mix ratios required, a number of two component systems cannot be accurately proportioned in the small sized batches needed for production. To counter this problem, larger batches must be prepared where only a small percentage of the material is actually utilised, and this results in a considerable amount of waste.

By choosing pre-mixed and frozen resins (PMF), these problems and hassles are completely eliminated as the end user only needs to thaw and dispense the material.

PMF refers to the blending, packaging and freezing of two component resin or catalyst systems, and offers the ultimate in convenience and reliability. Utilising the Pre-mixed & Frozen Resins service available from Ellsworth Adhesives, end users need not worry about human error on their production line – the experts at Ellsworth will mix, degas, weigh and package the two component system, before flash freezing the package and contents at -80C.

Upon receiving the pre mixed frozen product, the customer’s only responsibility is to store the goods in a freezer with temperature no lower than -40C. The PMF product will arrive in an insulated carton and full instructions for handling, thawing and storage are provided.

During the mixing process of PMF packages, it is possible to modify the resin and catalyst systems with the addition of a third or fourth ingredient. Options include precision glass spacer beads, adhesion promoters, pigments, fluorescent indicators and fillers, all of which have the potential to enhance the physical properties of the final material.

Another major perk of using Pre-mixed Frozen resins is increased productivity on the production line. With a regular supply of PMF, production need not be halted or held up while fresh material is dispensed, mixed and distributed. The need for cleaning time is also virtually eliminated since there are no messy containers or sticky bench tops to be considered.

The benefits of Pre-Mixed & Frozen Resins are unquestionable and Ellsworth Adhesives is one of few companies in the global adhesives market offering this unique product and service. To make an enquiry about our PMF services please contact: infoeurope@ellsworth.com.

Enquire about our Pre-Mixed and Frozen Resins service here. 

Few would argue that ‘Cyanoacrylate’ is difficult to pronounce, however the elaborate name given to this adhesive type is in stark contrast to its nature.

Quite simply, cyanoacrylate adhesives are super glues – the most commonly used adhesive in the industry.

This blog post explores cyanoacrylates in depth – from the product’s origins to its key attributes and most typical applications.

If you’d rather skip straight to shopping for cyanoacrylate adhesives, click here. 

History

Discovered less than a century ago, cyanoacrylate adhesives are a relatively new product on the market and like many great innovations, were actually invented by accident!

In 1942 whilst attempting to make clear plastic gun sights for the guns of allied soldiers in World War 2, a gentleman named Dr Harry Coover created a formulation that worked extremely well as a quick bonding adhesive. However, so dedicated was Harry to the invention task at hand, it was 9 years later before he reinvigorated his interest in the cyanoacrylate formulation.

Fast-forward to the present day and you will find many variations of the original cyanoacrylate formula – with each kind optimised for specific application requirements.

Typical Applications

Cyanoacrylate adhesives are considered as ‘general-purpose’ due to the wide range of applications to which they are suited.

From metal and wood to rubber, plastic and ceramics, cyanoacrylates will adhere to a host of substrates – even human skin. Because of this versatility, cyanoacrylate adhesives are widely used in the general consumer market – often to repair everyday items which have broken.

Cyanoacrylate adhesives, do however have their place in the industrial sector – particularly for applications that are not exposed to chemicals or physical agents.

Cyanoacrylate adhesives are commonly used for bonding small pieces together since a very small amount of glue will achieve high level of polymerisation and the fast bonding time, benefits more intricate applications.

Furthermore, cyanoacrylates are used for medical applications thanks to their quick cure and high adhesion to skin – making them perfect for closing wounds.

Selecting a Cyanoacrylate

When deciding which cyanoacrylate adhesive to use, users must consider the following specifications:

Temperature: What is the maximum temperature that the cyanoacrylate can be exposed to before its properties are altered?

Viscosity: How resistant does the material need to be to the flow? Viscosity controls the amount of cyanoacrylate adhesive dispensed onto a substrate.

Set Time: The amount of time an adhesive can be applied and repositioned or removed before curing is a major selection consideration, since it will result in the hardening of the bond.

Gap fill: The spacing or gap between the substrate that the cyanoacrylate adhesive can accommodate and still maintain a functional, full strength bond.

Chemical Composition

In their liquid form, cyanoacrylate adhesives consist of monomers of cyanoacrylate molecules.

There are two main kinds of cyanoacrylate – Polyethyl-2-cyanoacrylate and Polymethyl-2-cyancoacrylate.

The monomers within these compounds bind together in polymer chains through a process entitled polymerization and it is this union that gives the substance the power to hold two materials together.

Benefits of Cyanoacrylates

Cyanoacrylate adhesives are considered to be an economical adhesive solution since the best quality cyanoacrylate bonds are achieved by using a minimal quantity of adhesive (just enough to fill the joint). In fact, the thinner the adhesive film, the faster the cure and stronger the bond!

With no need for measuring or mixing, cyanoacrylate adhesives are simple and easy to use. Strength is another key attribute of cyanoacrylate adhesives – with just a tiny amount of cyanoacrylate, an outstanding mechanical strength can be achieved.

Additionally, cyanoacrylate adhesives are known for their rapid cure time. This adhesive type sets almost instantaneously and achieves handling strength in seconds.

Limitations of Cyanoacrylates

As with most adhesive products, as well as a great number of benefits, there are some limitations of cyanoacrylates.

The most notable limitation of this adhesive type is its short shelf life. Once opened, cyanoacrylate adhesives must be used within 6-12 months. Other constraints of cyanoacrylates include the potential for stress cracking and poor resistance to friction.

It is important to remember that for every limitation a specific adhesive has, a solution can usually be found in another adhesive product. If you find that the limitations of cyanoacrylates make them unsuitable for your application and you are unsure where to turn now, don’t hesitate to Ask The Glue Doctor.

Key Cyanoacrylate Brands and Products

As an adhesives distributor, Ellsworth Adhesives Europe supplies a broad range of cyanoacrylate adhesives from major brands, including Henkel Loctite, Permabond, 3M and Resinlab.

A few key cyanoacrylate adhesives worth checking out are: Loctite 406, Permabond 102 and Robnor Resinlab 6503

Shop our full range of Cyanoacrylate adhesives here.

 

 

Adhesive Matters: The importance of surface preparation for effective adhesion

A surface free from contamination is essential to securing a strong adhesive bond – but how can this be achieved?
The answer, quite simply, is through effective surface preparation. Let us take a look at different surface preparation products and techniques; from cleaners and degreasers – to primers and flux removers.

 

Abrasion

Mechanical abrasion is one of the most commonly used surface preparation methods and is suited to most materials.

The main objective of mechanical abrasion is to remove weak boundary layers, however this approach will also change the topography of the adherent, consequently increasing the bondable surface area. In addition, mechanical abrasion will enhance the adhesive’s ability to fully wet the surface.

Popular abrasion methods include sandblasting, vapour honing and the use of abrasives or cleaning and finishing materials.

Sandblasting with fine sand can only be used on substrates sufficiently thick to prevent distortion while vapour honing is satisfactory when minimum reduction is desired in metal thickness.

 

Cleaners and Degreasers

As the product name would suggest, cleaners and degreasers have been created to remove greases, oils, lubrication fluids, metal cuttings and fines from the surface that is to be bonded.

Cleaners and degreasers are highly effective and are available in both aqueous and solvent-based formulations.

Loctite 7063 is an example of a solvent based formulation. As a final pre-assembly cleaning treatment, this hydrocarbon-based, non-CFC solvent is designed to be used as a spray or in immersion cleaning processes. On the other hand, Microcare MCC-BGA is an aqueous formulation. This stencil cleaner will remove all types of solder paste as well as uncured chip bonder and inks. Safe for use on webbing, frames and misprinted boards, MCC-BGA provides fast and thorough cleaning – even inside stencil apertures.

When choosing a cleaner or degreaser, the major factors to consider are dry time, residue, odour and substrate compatibility. Residue is a particularly important concern because if there is any secondary processing of the part, e.g., painting or bonding, a residue could interfere with that process. Substrate compatibility is another common concern when dealing with plastics and solvent-based cleaners.

For precious metals and jewels, degreasing will generally be entirely satisfactory, with the possible exception of silver where the tarnish should be removed with medium grit emery paper. A stabilised Trichlorethylene vapour phase degreaser is recommended.

 

Primers

Primers are designed to enhance the bonding quality of adhesives. When applied as a surface coating, they will change the base of a surface to enable more effective adhesion.

The requirement for a primer is dependent on the material – for example a primer will be required when adhering to any porous substrate. This is because a pourous substrate will eventually absorb the adhesive that would normally create a long lasting bond. By using a primer, the adhesive’s ability to wet out the surface is significantly increased, thus solving the problem.

Plastic is another material requiring a primer – though the type of primer needed for this material can be very specific. For example, polyolefin requires a special polyolefin primer. Amongst a range of other primers, Henkel manufactures Loctite 770, a primer that has been designed to prepare the surface of difficult to bond plastics just like polyolefin and other low energy surfaces.

Another key priming product is Dow Corning PR-1200. Dispersed in naptha, PR-1200 is a one part primer available in clear or red that can be used on most metals, glass, ceramics and masonry to enhance adhesion. Typically applied in a thin layer, PR-1200 and indeed other Dow Corning primers, are dilute solutions of silane coupling agents and other active ingredients. These products should be applied in a very light, even coat by dipping or spraying and excess material should be wiped off to avoid over application.

 

Accelerators and Activators

Both adhesive accelerators and activators are applied ahead of the adhesive act as catalysts. While both product types are designed to increase cure time, activators also improve the quality of adhesion.

One of the most commonly used adhesive activators is Loctite 7455 – used for applications requiring an increased cure speed. While this activator can be applied before or after the bond, it is particularly suited to post-application on cyanoacrylate adhesives, since it ensures rapid fixture between close fitting parts. Typical applications for activators include securing wires or coils to PCB’s, tamper proofing adjustable components and mounting stand off’s, edge guides and board stiffeners.

Moving onto accelerators, while this product type is used to speed up cure time, users should be aware of the ‘trade off’ in the bond strength. For example, when bonding a very porous material with a cyanoacrylate, the application of an accelerator may increase adhesion by causing the cure before the adhesive is fully absorbed. Where possible it is therefore better to use an activator than an accelerator.

 

Flux Removers (or defluxers as they are sometimes known)

Flux removers are designed to remove flux residues and other contaminants that may be found on printed circuit boards due to rework, repair or manufacture.

Used before the application of an encapsulant or conformal coating, flux removers play a critical part in ensuring reliable circuitry.

Microcare MCC-PW2101 Power Clean is a flux remover that promises to deflux high temperature lead-free solder residues. Fast drying and non-flammable, this PowerClean product will even clean oils and inks.

Another popular Flux Remover is Microcare MCC-UFR107 Universal Flux Remover which is designed to safely remove contamination and soils that can impact the functionality and reliability of electronics. The fast drying and low aroma properties make it ideal for cleaning electronics during rework and repair, spot cleaning or in-field service repairs.

 

Conclusion

Surface preparation is undoubtedly an important process for effective adhesion, however the approach to this process, cannot be considered as ‘one size fits all’.

Important factors to be considered include the application in question, material type and the form of contamination. The key surface preparation products and techniques have been outlined above, along with an explanation of their suitability for certain materials and applications.

If you have any further questions on this topic please don’t hesitate to Ask The Glue Doctor – who will be happy to answer all of your technical questions.