What is the difference between monomeric, polymeric and cast vinyl?
You can tell a lot by the names given to the two types of calendered vinyl. “Mono-” means one, “poly-” means many and “-meric” means body or unit. Monomeric and Polymeric describe the type of plasticiser used to create the finished vinyl. Cast vinyl is not a calendered vinyl (but uses the same plasticiser as a polymeric vinyl) and the differing manufacturing process for cast creates a more stable and durable vinyl. Calendered vinyls are manufactured differently using a rolling process, which is more stressful and results in less dimensional stability of the material.
What is Vinyl?
Vinyl is made from Poly Vinyl Chloride (PVC) material, which is a synthetic man-made substance. It is a type of plastic that is made from Chlorine (found in salt) and Ethylene (found in crude oil). When processed, the substances combine to form PVC resin – or vinyl.
How is Calendered Vinyl made?
First the ingredients are melted; as they cool, the molten PVC is rolled through calendering rollers to achieve the final width, thickness and surface finish.
Calendered vinyl is cheaper to make than cast vinyl because it does not need solvent to make it, there is no casting (mould) costs and it yields a lower energy cost in its manufacture. As a result the finished product does not have the same resilience that cast vinyl does, but is perfectly adequate for a lot of applications.
How is Cast Vinyl made?
Cast vinyl is produced by turning the ingredients which make up the finished vinyl (PVC resin, plasticiser, colourant if required) into a paint like substance by the use of a solvent. When Matt, semi-gloss or gloss vinyl is required then the mould film will mirror that texture.
The vinyl is then dried and cured at a high temperature to form a flexible film. The temperature involved in creating the vinyl is much higher than that used in any application of the finished product and is also the reason why this type of vinyl is able to withstand the distortion and heat without degradation, degeneration or warping of the finished product.
What is a Plasticiser?
A plasticiser is a substance, which when added to the PVC promotes flexibility and reduces brittleness. Without plasticisers, PVC products are hard and brittle and they would shatter if you were to bend or flex them.
Monomeric vinyl uses the plasticisers with a small molecule size, which has more molecular migration and as a result it has more effect on any adhesives used.
Polymeric vinyl is made using long-chain plasticisers with a large molecule size that bind well into the vinyl. This bond has less molecular migration and also has less effect on any adhesives used.
This is a popular vinyl, due to its price and the fact that it is ideal for flat surfaces, which is perfectly adequate for the large majority of signage requirements. It has a short to medium life span of approx. 2 – 5 years, but it does have a tendency to shrink. Therefore, these vinyls are best for indoor, flat applications. They can also be used for short-term outdoor applications.
Why choose monomeric?
• Ideal for standard, flat applications
• Lower in price
• Short to medium life – enough for most usage applications
Why decide against monomeric?
• Not suitable for uneven surfaces
• Can suffer from shrinkage
Polymeric vinyl is best for both indoor and outdoor applications, including mild curves. It has a medium-term life span of approx. 5 – 7 years, which is longer than monomeric vinyl. Polymeric vinyl is more resistant to shrinkage than monomeric vinyl and is more stable.
Why choose polymeric?
• Longer life span.
• Less shrinkage.
• Ideal for flat and slightly curved applications.
Why decide against polymeric?
• Can be pricey compared to monomeric.
The next time you ask yourself what type of calendered film should you use, remember this:
Cast vinyl is a premium, high quality vinyl with a lifespan of approx. 8 – 10 years. It is soft, thin and flexible, which makes it ideal for vehicle wrapping on cars and vans for instance. Unlike calendered films, cast vinyl will not shrink or pull back to its original form when exposed to heat (such as a heat gun).
Why choose cast?
• Even longer life span.
• Won't pop out of even the most severe recesses.
• Soft, flexible and thin.
Why decide against cast?
• Price can be a factor, but if durability and high conformity is what you need then cast vinyl is the way to go.