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What is the Best Glue to use with Plastic?
October 24, 2019
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From broken toys to home repairs, there are a myriad of reasons you might want to use glue on plastic.
But with so many different types of plastic and so many different types of glue; it can be hard to get the combination right. Getting it wrong can have dire consequences for your project, resulting in bonds that don’t hold or cause damage to the plastic itself.
To save you some time (and possibly some heartache), here’s what you need to know about adhesives and plastics.
Choosing the right glue for plastics
The key to using glue with plastics is finding the right combination. That means first and foremost, you need to know what kind of plastic you’re dealing with.
Typically, the symbol with the three arrows and a number in the centre on packaging (otherwise known as the recycling symbol) is what you need to look for.
Here are the main types of plastic as well as some suggestions on what type of glue is best to use.
Recycling Symbol 1: High Density Polyethylene (HDPE) A more heavy duty and durable plastic– think washing detergent bottles and buckets. What’s the best glue? Epoxy, but surfaces must be prepared first by roughening—for example, try using gritty sandpaper. Recycling Symbol 2: High Density Polyethylene (HDPE) Also known simply as polythene, the high density version has a high strength to density ratio and is commonly used for a wide variety of applications, from milk bottles to toys. What’s the best glue? Plastic cement, cyanoacrylates or epoxies will do the trick, however to ensure you get a strong bond its crucial to ensure you roughen up the surface before application. Recycling Symbol 3: Polyvinyl Chloride (PVC) Soft and flexible, PVC is used to make toys and plastic pipes, even teething rings. What’s the best glue? Plastic cement, cyanoacrylates or epoxies. Recycled Symbol 4: Low Density Polyethylene (LDPE) LDPE is used to make squeezable, less rigid bottles, garment bags and even some clothing and furniture. What’s the best glue? LDPE has a very low surface energy; which basically means it’s very slippery. Glue isn’t recommended. Recycling Symbol 5: Polypropylene (PP) Some of the items made from this type of plastic are bottles caps, drinking straws and pill bottles. What’s the best glue? Similar to LDPE, Polypropylene has a low surface energy. Some industrial adhesives may be effective, however surface preparation will likely be required. Recycling Symbol 6: Polystyrene (PS) Polystyrene is often used to make disposable cups and cutlery and is frequently used in model kits. What’s the best glue? Epoxies and spray adhesives will all work well with polystyrene. Recycling Symbol 7: Others This covers every other known plastic or composite i.e. a mixture of plastics. Includes plastics such as Acrylonitrile Butadiene Styrene (ABS) , Acrylic, Polycarbonates, fiberglass and others. What’s the best glue? This very much depends on the type pf plastic being used. Identifying the plastic type is an important first step and due to the number of different plastics that fall under this category we recommend speaking with our team to help find the perfect adhesive.
Though it may seem a lot to get your head around, it’s important to find the right product for your project. With a little research, you can feel secure in the knowledge that your bond is going to hold.
