If you want to find out a little bit more about MS polymer adhesives, you are in the right place.

Here at Forgeway, we first started manufacturing Formoa, our MS polymer product range, in the 1990s. We now manufacture over 2500 tonnes every year. So, it’s fair to say we know a thing or two about MS polymer adhesives.

This article will go over what MS polymers actually are, their benefits and drawbacks, and finally, it will discuss how much they will cost you.

You will be able to determine whether MS polymers are the best fit for your bonding or sealing solution.

What are MS polymer adhesives?

First things first, you should know what they actually are. MS polymer adhesives are made up of a hybrid polymer called modified silane. The term ‘MS polymer’ is a registered trademark of Kaneka as they created the hybrid silane polymer formulation. Some people refer to copies of MS polymer as hybrid polymers or silyl modified polymers (among other names) but it all means the same thing. This MS polymer was then used to create an adhesive product that has the strength of polyurethane and the weathering resistance of silicone.

However, MS polymers do not contain any silicone or urethane polymers which is a big deal as silicone is banned by some automotive manufacturers.

There are a wide variety of MS polymer formulations which can be adjusted to increase or decrease a certain property (like strength). These formulations can range from high-strength structural adhesives to low-strength sealants. 

You will rarely find two-part MS polymers as they don’t require a hardener in the curing process. They will almost always be one-part (in a foil pack or cartridge). This is because MS polymers require moisture to cure. 

In the one-part option, they use the moisture levels in the air to cure. Most companies are happy with the cure speed of one-part options. Although, if you want an MS polymer with a faster cure, there are two-part options that increase the moisture levels which then speeds up the cure.

Where can you use MS polymer adhesives?

To begin with, we should explain that MS polymer’s versatility is perhaps not as well known as it should be. You will be able to use MS polymers in pretty much any sealing or bonding situation because adhesive manufacturers can adjust the formulation to suit your requirements. They easily bond to pretty much all surfaces and are fully primerless.

There are, of course, exceptions. If you need an extremely high-strength bond (such as replacing a weld), you would be better off using an epoxy adhesive. You cannot bond low surface energy plastics (like polypropylene composite panels to the side of a caravan) with MS polymers either.

But you should definitely consider using an MS polymer for any bonding or sealing situation, as long as the substrate is compatible and you don’t require a very high-strength bond. 

To give you an idea of who uses MS polymers, I have created a short list of examples:

• A marine manufacturer uses an MS polymer adhesive to bond and seal the windows of their luxury yacht product. They like the weathering resistance and strength that MS polymer adhesives provide. 
• A caravan manufacturer uses an MS polymer adhesive to bond and seal the plastic sides of their caravan product. MS polymer’s structural, flexible, and sealant properties were what made it the best adhesive solution for them.
• A bus manufacturer uses MS polymer to bond the composite flooring to the bus frame. They also used a colour-matched, flexible MS polymer adhesive to match the floor covering and seal it in place

There are plenty more examples of companies that use MS polymers. Nonetheless, these three examples should give you an idea of the variety of situations where you could use an MS polymer adhesive.

Advantages of using MS polymer adhesives

As you will be aware, MS polymers are a very good adhesive and sealant solution. But you will be wanting to know the benefits you will get if you choose to use an MS polymer product. So this section will go over every advantage of using MS polymers.

MS polymers provide a very good seal for bonding and sealing

Some MS polymer formulations can have strengths of up to 5 Mpa, making them a structural adhesive. Other MS polymer adhesives have limited strength. But all MS polymer products have good sealant properties. Whether you intend to use the MS polymer product for bonding or sealing, it will always provide a good seal. This seal is better and more durable than that of other structural adhesives.

MS polymers are very flexible

Some companies look to find the strongest glue possible, but strength isn’t everything. In situations where there is likely to be lots of movement and vibration (such as a vehicle), you need a flexible adhesive to deal with the shock. MS polymers have better flexibility than other structural adhesives such as methyl methacrylates and epoxies. 

You can overpaint most MS polymers

There are a lot of discussions about the difficulty in painting over sealants like silicone. Not only can you purchase colour-matched options to eliminate the need for overpainting, but you can paint over most MS polymers without any problems should you need to. Don’t forget there are many different types of paint, so we’d always recommend testing first.

MS polymers are the safest adhesive for the user and the environment

Most other adhesives and sealants will have some form of health risk to be aware of. Some manufacturing companies have even banned the use of silicones in their factories because of these health risks. You won’t have to worry about this with MS polymers, you won’t experience any health risks. They are not harmful to the environment either.

MS polymers have very good weathering resistance

UV resistance is not the only form of weathering resistance that you should consider. Weathering includes the impact that hot and humid climates could have on the adhesive as well as the effect of UV. MS polymers are able to withstand the effects of weathering.

The above-mentioned advantages are the deal-breakers for most companies when deciding which adhesive to use. There are a few more advantages that you should also consider, such as:

• Long shelf life
• Fire-resistant options
• No bubbling when curing
• No staining on substrates

What are the disadvantages of using MS polymer adhesives?

So you now know that MS polymers are a very competent adhesive and sealant option. But you will be thinking we are biased as we manufacture and supply them here at Forgeway.

But as we have worked with MS polymers for over 25 years, we also know that there are a couple of things that make them an unsuitable option for some companies. We will list some of the things that could make MS polymers an unsuitable option for you.

Cure time can be long and inconsistent

The word ‘long’ is subjective. But in this case, we mean that the cure time is usually no quicker than other structural adhesives. Some might refer to this as having a longer ‘open time’. Adhesive manufacturers can adjust this cure time, but there is no getting away from the fact that MS polymers’ cure time is typically the slowest out of all structural adhesives.

As we mentioned earlier, they also require moisture to cure. Limited moisture (such as lack of airflow) will either reduce the cure time or prevent it from happening at all. There are other factors that can affect the cure time, but moisture will always affect the cure time of MS polymers.

So you should bear this in mind when considering MS polymers as an adhesive or sealant option. Methyl methacrylates have a very fast cure that is much more consistent if that is something that is a big issue for you.

MS polymers aren’t the strongest structural adhesive

We have already mentioned that MS polymers aren’t the strongest, but there are a couple of reasons why this might not work for you. Epoxies are the strongest structural adhesive. So if you are purely looking for high-strength glue, you should go with them. 

But, we have also mentioned flexibility too. Flexibility can be just as important as strength. And epoxies are very brittle. So what can you do?

We would suggest using a polyurethane adhesive if you want something that is strong but also remains flexible.

Sometimes, MS polymers are too strong

Yes, MS polymers can be too strong for certain situations. Companies often compare silicones and MS polymers because they are the two best sealants. However, an MS polymer sealant will always have more strength than a silicone sealant. 

Most people would struggle to see why having more strength is an issue. But it can be. 

The simple reason is on the rare occasion you make a mistake, silicones will be a lot more tolerant. They allow you to remove and replace anything you think should be replaced. MS polymers’ strength will be a lot less forgiving and you will struggle to remove and replace the sealant if you get a poor finish.

It can be more difficult to get a good finish

Silicones are popular for a reason. They always used to be cheaper than MS polymers (now they are about the same price), and they are still a lot easier to work with.

All silicones are easy to work with as you won’t need a significant amount of skill to apply and get a good finish. You won’t always find the same with MS polymers. It can take a lot of skill to apply MS polymer in a way that gets a good finish.

How much do MS polymer adhesives cost?

The question around cost is always difficult to answer. As you will be able to tell, there are so many different types of MS polymer. So it would be impossible for us to give you an answer as to how much they cost.

But, we can break it down into a bit more detail and give you an idea of what the different types might cost.

• Highest strength MS polymer will cost around £13 – £15 per 600ml foil sausage.
• MS polymer with good strength and very good sealant properties will cost around £12 – £13 per 600ml sausage.
• Colour-matched MS polymer for sealing will cost around £13 (aviation customers requiring AS9100 accreditations can expect prices around £18). You will also need to be wary of colour set-up charges which usually cost an additional £100.

How do you know an MS polymer is the best option for you?

The answer ultimately lies with what you want from your glue. However, MS polymer is a very popular adhesive option for a reason. It is good (sometimes great) at most things required of glue, whilst not having as many drawbacks as other structural adhesives. 

We wouldn’t recommend using an MS polymer if you want an adhesive that has extremely high strength, although it depends also on your interpretation of “High Strength”. MS polymers are usually more than strong enough for bonding most structural situations.

However, we definitely recommend at least considering an MS polymer for your bonding or sealing (or both) situation. 

If you are interested in having a look at our range of MS polymer adhesives and sealants, you can browse them on our website. 

If you are still unsure about whether MS polymers will be the best option for you, we recommend having a look at some of the other structural adhesives or getting in touch with an expert.