Ok, let’s talk about the different coating options used nowadays to increase the quality level of fabrics.
As you well know, most fabrics are hydrophilic – fabrics love water – except for those exceptional cases where the material is treated with artificial coating solutions.
For us, the outdoorsy folks, it is essential to make sure the backcountry clothing we wear is waterproofed or at the least weatherproofed.
In the same vein, ensure your gears’ carry-on, your backpacks, and even tents are all able to keep moisture at bay.
If not, you’d find yourself drenched to the bone when caught in the wrong weather environment.
I’m guessing here that in a bid to find that perfect water resisting apparel, rainwear, pack covers, and or parka, you’ve come across the term “PU coating”.
Don’t worry if you haven’t heard about it yet.
In this article, you’ll learn what PU Coating is, you’ll see how it compares with other coating processes such as TPU and PVC, and you’ll also learn about its applications.
PU Coating Explained
Commonly known as Poly coating, PU coating is the application of polyurethane – a type of polymer – to the surface of fabrics with the aim to strengthen and protect the material.
Now, if you’re wondering what a polymer is – it is a synthetic compound made from petroleum residue.
It often occurs when fabrics such as polyester, nylon, cotton, and even leather are layered with the synthetic compound on one side then treated to stick the compound to the base material permanently.
Often, this protective film of polyurethane is applied only on one side of the material or on both sides and the processes are called single-coated and respectively, multi-coated.
Once, the fabric goes through the PU coating, it becomes more lightweight, water resistant, and more flexible than before.
So, now that you know what polyurethane means, let’s take a look at how it compares to the new and similar technologies as well: TPU and PVC coatings.
So, What’s TPU?
Think of Thermoplastic Polyurethane (TPU) as the tie between rubber and plastic.
The TPU material is a group of thermoplastic elastomers – now that’s like having components that behave like elastic plastics – that exhibits a high-level of elasticity (just as I said earlier) and are incredibly resistant to stresses such as abrasion and stains.
Things start getting really interesting when you consider the internal structure of a Thermoplastic Polyurethane material. Its structure is made of soft and hard segments.
When viewed under the microscope you’d notice an alternation between the soft and hard segments – something like soft-hard; soft-hard; repeat – all linked together in some sort of a chain.
The importance of this kind of segmentation is that the thermoplastic polyurethane can be manipulated to change the number and nature of the segments to produce a different thermoplastic polyurethane material with varying hardness and or softness.
Isn’t that interesting, huh?
For this reason, TPU coating has found application in a multitude of industries including but not limited to engineering tough rubber and plastics and also used as an additive to strengthen other materials.
Plus, it can be manufactured with different base material components – read: coated with three base materials.
Now, that’s pretty much an exciting material to have around.
The next process on the block is the use of PVC. If you’ve spent a considerable amount of time shopping around for coated fabrics or perhaps, in search of a material to strengthen your apparel, then it is very likely you have come across the term PVC coating.
The question, however, is…
What exactly is PVC coating?
Polyvinylchloride (PVC) also often referred to as Vinyl is at its core a plastic made from PVC resin, polyester scrim as fillers, and additives to form a very versatile, flame resistant fabric.
The additives such as plasticizers are used to manipulate its softness – making it a bit malleable – to influence its colors – that’s why you can find different colors of PVC on the market – and to control its texture.
Once the PVC is ready, it is then used to coat one side of a woven fabric to create a durable, fire retardant, impervious to water surface that is suited for harsh, rugged situations like high-traffic hospitals, marine, and commercial environments.
Ok, now you know what each of the terms – PU, TPU, and PVC coating – mean. Let’s look at how they compare against each other.
PU VS TPU VS PVC Coating
So, here’s how we’re going to do this; we’ll compare each of the processes against a set of parameters that I believe are essential markers to how effective they’re as coating agents.
Weight is an important factor to consider especially if you’re an outdoorsy kind of – you don’t want to be bogged down by an extra weight when out and about in the open.
So, how does each of the coating compare here?
PU coating is often applied to non-knitted fabrics like polyester, nylon, leather, and cotton with the intention to keep the textile material lightweight.
Considering that this PU coating is only on one side of the fabric usually on the backside, it also plays a role in how heavy the material becomes.
However, a downer to this is that since the outer part of the fabric is uncoated, it will absorb moisture which will then get trapped under.
The added “wet weight” may prove disadvantageous.
TPU and PVC coating it seems are not different. Both are lightweight on their part without any significant change in the weight or volume-ness of fabric so coated.
So, for this parameter, it is a close call with no clear winner. This means, whether your fabric is coated with PU, TPU or PVC it’d come out without any change in weight.
Often materials are coated to protect them from the degrading effects of moisture, oil stains, grease, and other solvents.
Generally speaking, fabrics such as Nylon, Leather, and Polyester on their own are not waterproof.
However, to make them water resistant, they are often coated with special agents either through laminating, layering or applying the waterproof film.
PU, TPU, and PVC are excellent materials for fabrics, though, due to the high costs of producing TPU and Vinyl coated fabrics, PU is often used for this purpose.
However, since PU offers greater breathability than PVC and TPU – remember a fabric’s breathability is its ability to allow water vapors pass through it – it can be argued that both TPU and PVC offer greater water resistance than PU.
Now, this is not to say that material breathability is not desirable in a fabric. It merely means that if a piece of fabric is expected to be strictly waterproof then PU might not be the best possible option.
PVC and TPU provide better protection against wet conditions. Between PVC and TPU, go for PVC if you’re constrained by cost.
3. UV Resistance
Usually, PU coating is often applied on the back side of the fabric. So it’s not exposed to the elements.
You know why?
Well, the thing is, PU coating is not resistant to the damaging effects of UV radiation.
The UV light, electromagnetic radiation that forms 10 percent of sunlight with a short wavelength reacts with the molecules of the coating film and in the process, breaks down the polymer chains of the coating agent.
However, to work around this, most product manufacturers apply DWR(durable water repellent) on the outer surface of their products, or they add anti-UV chemicals that stabilize the coating agent by absorbing and dissipating the UV light as heat.
TPU, on the other hand, offers solid protection against the damaging impacts of the UV rays. So, it’s not uncommon to find the coating on the exposed sides of fabrics.
I’m guessing you don’t want a coated fabric that within a short time would begin to lose its coating either by peeling off, washing off or worst, getting all cracked and unsightly, huh?
So, between PU, TPU and PVC, which one offers a better deal? Which of these technologies is more durable?
First, you should not forget that more often than not, there are a number of factors which directly influence the life of the material, such as: how often the fabric is used, the prevailing conditions in which it is used, how well you care for it, and storage.
Now, let’s assume the material is reasonably being cared for, is stored well, and the usage is nothing unusual – which of the coating would last longer?
TPU undoubtedly beats every of the other material. Both PVC and TPU are abrasion resistant though with TPU exhibiting higher abrasion resistant power.
PVC is inherently fire resistant, unlike PU that requires the addition of flammable retardants.
Also, TPU is stronger, less prone to cracks and flexible than PU coating. However, all three materials provide strong resistance to chemicals, they prevent corrosion and provide smooth surface finishing.
Each of the materials has a use which they are most suitable for. Take, for instance, PU, which is used in a variety of consumer products like automobile interiors, PU coated polyester and nylon, carpets, footwear, straps, and bands and so on.
PVC materials are used in the production of pipes and cables, kids’ toys, handles, and flooring, while TPU is applied in many areas including mobile phone cases, medical devices, tubing, and inflatable rafts.
PU, TPU, and PVC are thermoplastic materials that depending on a multitude of factors(ex: temperature, the type of plasticizer used, and chemical compatibility) perform better than the other in a given situation. So, as a manufacturer, the choice of coated fabrics depends on your needs and preference.
As a consumer, the more high-end and expensive a product is, it’s probably coated.