Increasing demand for reactive hot melt adhesives PUR and POR in automotive industry
The need for reactive hot melt adhesives has never been greater thanks to their extraordinary strength and versatility. The reactive hot melts refer to polyurethane (PUR) hot melts and silane modified polyolefin (POR) adhesives. Both of the reactive hot melt adhesive types are used throughout industries including automotive, electronics and construction. In this article we focus on the automotive industry including assembly and repairs.
Two-stage curing in reactive adhesive technology
Reactive hot melt adhesives are also known as moisture curing hot melts. This means that the adhesives reach their final cure as they react with moisture in the air and the substrate. These adhesives have a two-stage curing profile which divides the process into physical and chemical curing.
- Physical setting: shortly after the adhesive has been applied the physical setting takes place. This allows the adhesive to reach a stage of hardness which allows for further processing and transport.
- Chemical crosslinking: the second stage of curing may take from hours to days depending on the adhesive type and the moisture present in the environment. During chemical crosslinking the hot melt adhesives lose their thermoplastic properties and become thermosets, which means that high heat does not affect them.
The unique curing process makes PUR and POR adhesives a desired solution for many applications within the automotive industry. They can be used for example in making the seats, gluing carpets, bonding foam based materials, fixing cables, attaching door sill protectors as well as bonding emblems and gear knobs. These are not the only applications for reactive hot melt adhesives: the range of possibilities is nearly limitless. Contact us to discover whether PUR or POR is the solution for your application.
Benefits of reactive hot melt adhesives in vehicle assembly
The reactive hot melt adhesives are not the most inexpensive, but they are versatile in use and deliver high quality bonds even on substrates that have been considered “un-glue-able”. The adhesives are rather light, which contributes to the weight reduction of vehicles. They also bond lightweight materials that are crucial in lighter weight vehicles. The application of these adhesives is also rather easy as long as the right type of hot melt dispenser is used.
The two types, polyurethane and silane modified polyolefin based systems, both have their own unique advantages.
What makes PUR hot melt adhesives special
Polyurethane hot melt adhesives have several benefits which combined make up a very unique adhesive. The beneficial properties include the following.
- Heat resistance: crucial for both finished products and further processing, PUR hot melts are heat resistant once they have reached the final cure. Heat resistance is not a common property for hot melt adhesives.
- Low temperature flexibility: common for polyurethane adhesives, also the reactive hot melts remain flexible in low temperatures. Depending on the application this can be a great advantage.
- Extraordinary strength: of all the hot melt adhesives, PUR is the one that forms the strongest bonds.
- Excellent adhesion: PUR hot melt adhesives adhere well to a wide range of substrates including lightweight materials that are increasingly used in vehicle assembly.
- Solvent resistance: polyurethane hot melt adhesives are known for their excellent solvent resistance which opens up more application possibilities.
Share your specifications with us and find out whether PUR hot melt solves your bonding problems.
When to use POR adhesives
PUR hot melt adhesives are versatile and have a unique set of characteristics which fits many applications. However, some applications that require reactive hot melt adhesives cannot be realized with PUR: this is when POR comes into picture. The silane modified polyolefin based adhesives share many advantages with polyurethane but they also adhere to the surfaces that are a challenge for PUR. Untreated and non-polar surfaces such as polypropylene (PP), which is common in vehicle assembly, can be easily bonded with POR adhesives.
Additionally, even though the POR hot melts do not reach the strength of PUR, they form very durable bonds which can be considered more environmentally friendly than those made with other reactive hot melt adhesives. Typical for modified silane based adhesives, POR does not contain isocyanates. This also means that the adhesives are not labelled as hazardous goods. In some cases this may be the deciding factor when choosing a hot melt adhesive.
Looking for POR or PUR hot melt adhesives?
In case you need any assistance in deciding about reactive hot melt adhesives or are looking for adhesive systems for specific applications, contact us! Our experts are determined to find you the most fitting adhesive solution.
Get connected with a reactive hot melt adhesive manufacturer with a proven track record of high quality bonding solutions and matching application equipment. Additional benefits offered by the manufacturer include:
- Laboratory testing of adhesives and equipment
- On site advice and fast product delivery
- Support in case of malfunction and repair services by well trained technicians
- Support in further development towards better bonding
- Multilingual service