You want to find out everything there is to know about methyl methacrylate adhesives (AKA acrylic adhesives). The good, the bad, and the ugly; you want to know it all.
We’ve got you covered. As adhesive specialists here at Forgeway, we know everything there is to know about MMAs. We manufacture and supply over one hundred tonnes of methyl methacrylate adhesives every year.
We wrote this article to educate you on some of the things that you need to know before choosing to use MMAs. By the end of the article, you will know whether methyl methacrylates will be the best adhesive solution for you.
What are methyl methacrylate adhesives (commonly known as plexus adhesives)?
Methyl methacrylate adhesives are relatively new in the adhesive industry. MMAs are known as ‘structural adhesives. However, people often refer to them as ‘Plexus® adhesives’ because Plexus are the most widely-known manufacturer and supplier of MMAs.
MMAs are usually two-component adhesives. They are acrylic and will usually come with the resin and the hardener in two separate compartments of the cartridge. The ratio of resin to hardener can either be 1:1 or 10:1. The 10:1 variant is often for situations where the end-user requires greater flexibility. We’ll cover flexibility in more detail later.
You can get one-component options too, but this option requires UV to cure and isn’t very common.
What can you use methyl methacrylates for?
You can use a methyl methacrylate adhesive for pretty-much any situation that requires bonding. We typically supply our MMAs to the transportation, automotive, and solid surface (countertop/worktop) industries. However, MMA’s increasing popularity means that more-and-more industries are cottoning onto their benefits and using them.
It’s difficult for us to list out every situation where you can use MMAs. I will list out a few examples of where our customers used an MMA product, and where you might be able to use an MMA.
- Minivan manufacturer – They used an MMA to bond a composite flooring to a wood floor.
- Solid-surface manufacturer – They supply MMAs with their worktops/countertops for their customers to bond the two parts.
- Construction company – They used an MMA to bond the aluminium composite panels to the building.
- Low surface energy (LSE) plastics – One of our MMA products can bond to plastics with very low surface energy. Polypropylene, polyethylene, and Teflon are typical examples of LSE plastics. It has been traditionally difficult to bond these plastics.
What are the advantages of using methyl methacrylate adhesives?
There are several reasons why MMAs are increasing in popularity. We wrote this section to give you an overview of why MMAs could be a good option for you.
MMAs have a quick and consistent cure time
Methyl methacrylates are best known for their cure time. Not only is the cure time quick (as quick as 15 minutes), the temperature and other external factors do not affect this cure time. This consistent cure time is very different from other structural adhesives.
Methyl methacrylates are the only structural adhesive to have this consistent ‘snap cure’.
Methyl methacrylates are known for their strength
People often compare epoxy-based adhesives and MMAs because they both have high strength. Even though MMAs don’t have as high strength as epoxies (epoxies have strengths of up to 60 Mpa), they can achieve strengths of more than 20 Mpa.
20 Mpa is by no means ‘low strength’ though. In fact, they are the second strongest structural adhesive, so strength is definitely an advantage of MMAs.
You won’t need to extensively prepare the surface before applying MMAs
They require minimal surface preparation due to their unique ability to ‘cut through’ any contamination. It’s a unique ability because the other structural adhesive will need extensive surface preparation to ensure a strong bond. This factor, coupled with the fast cure time, can be a decision-maker for some people.
There are fewer health risks associated with MMAs
Methyl methacrylates pose fewer health threats than epoxies too. MMAs do not have isocyanates in the base chemistry unlike epoxies and polyurethanes (another structural adhesive). This means the potential health risks are a lot lower than if you were to use either of the other two options.
There is a strong smell when using MMAs though. And when we say strong, trust us when we say it can become unpleasant. Adequate ventilation, PPE and proper care will help reduce health threats.
The adhesive supplier will show any health risks on the product itself, and in the safety data sheet.
Methyl methacrylates are very versatile
The final advantage that we are going to touch on is methyl methacrylate’s versatility. As we were saying earlier, you can bond most types of substrates with MMAs. As we mentioned above, at Forgeway we’ve developed an MMA product that can bond low surface energy plastics like polypropylene and Teflon.
So you can probably tell, you can use MMAs pretty much anywhere to bond most surfaces.
What are the disadvantages of using methyl methacrylate
It may all seem like a bed of roses with MMAs. And yes they are a brilliant structural adhesive, but there are a few things you should be aware of first.
Methyl methacrylate adhesives have a very high exotherm
To begin with, they have a very high exotherm. This may not seem like a problem, but the temperature of this exotherm can reach heights of 160℃. You read that right, 160℃.
This exotherm presents even more of a problem when you are using the MMA in large quantities. At the very least, you will see ‘witnessing/read-through’ from the exotherm. In worst cases, the exotherm can even damage the integrity of the bond due to the heat evaporating some parts of the adhesive as it cures.
There are still some health risks involved with using MMAs
We mentioned fewer health risks earlier, but fewer doesn’t mean ‘non-existent. As we were saying, the smell alone can cause irritation, and we thoroughly advise you have adequate ventilation whenever applying MMAs.
Methyl methacrylates can have poor flexibility
We recommend you consider “how strong is too strong?” It may seem counterintuitive and a bit pointless. Why wouldn’t you want a strong glue? There is a good reason you should consider this.
The strength of glue is one thing, but flexibility is also very important. This is particularly the case if you are bonding a moving structure (like a vehicle). Methyl methacrylates are much like epoxies in that they are very strong but not especially flexible.
This lack of flexibility and high strength means it is likely to cause substrate failure for some materials like GRP (GRP is just an example). Although as we mentioned earlier, 10:1 ratios offer greater flexibility.
Some formulations of methyl methacrylate adhesives can acheive very high flexibility. But you will often find that the higher the strength, the lower the flexibility.
You will have to choose which characteristic is more important for your application. Strength or flexibility.
How much do methyl methacrylate adhesives cost?
After reading the above sections, you may be sold on the idea of methyl methacrylate adhesives. But, you’re still going to be considering the price at some point (if you haven’t already!).
So here you go, here are the average prices of methyl methacrylate adhesives:
- A 1:1 cartridge will typically cost £30 for a 400ml cartridge.
- A 10:1 cartridge will usually cost £50 for a 490ml cartridge.
Obviously, these are for guidance, so many things can affect the price and it is difficult to say for sure this will be the cost.
How do you know methyl methacrylate adhesives are the best option for you?
Only you can answer that question. It all depends on what is most important to you and what you want from your adhesive.
A methyl methacrylate adhesive solution is a good fit for you if you need a strong adhesive with a quick and consistent cure time that requires minimal surface preparation.
However, if you need to use the adhesive in large quantities and the structure you are bonding is likely to move, MMAs might not be the best option for you.
This article will have given you a greater insight into the reasons other companies have chosen to use MMAs for their bonding situations. Nonetheless, you may still be struggling.
You can reach out to one of our experts if you feel as though you need assistance.
If methyl methacrylate adhesives have piqued your interest and you want to find out more, the article below on the advantages and disadvantages of methyl methacrylates will help you come to a decision on whether they are a good fit for you.