A: The biggest difference is that OPC's WBPU (Water-Based PU) and PPU (Prepolymer PU) have eliminated a large part of the organic solvents and non-environmental / harmful substances which have been used in traditional solvent-based PU manufacturing. This, in turn, leads to new manufacturing technologies that reduce our energy consumption, lower our CO2 emission, and increase production efficiency. It also eliminates the pungent smell of DMF and ensures the health of our employees, customers, and product users.(OPC PU Comparison Chart)
(OPC PU Comparison Chart)
In WBPU, water is the medium that disperses PU resin particles, so it's eco-friendly and harmless to the human body. For PPU (prepolymer PU), we synthesize PU prepolymers then process them without adding DMF or water, so PPU is also eco-friendly and harmless. However, PPU is firmer, more durable, and more rebound resilient, suitable for products requiring these physical properties. Meanwhile, WBPU is softer and more breathable, so it can be applied to more lightweight product types. However, with our R&D experience, both can be adjusted to satisfy various applications and physical strengths requirements.
Traditional PU polymerization involves organic solvents like DMF, dimethylformamide, to control PU viscosity so that the PU can be easily processed and coated. DMF is a colorless moisture-absorbing liquid with a pungent odor and high boiling point, soluble in water, alcohol, and acetone. Organic solvents emitted during traditional PU processing would eventually become greenhouse gases, solvent elimination consumes a lot of energy, and the traditional process cannot completely eliminate DMF from the product. Sometimes, residual solvents might induce respiratory disturbances in patients with a weak respiratory system (like asthmatic patients). EU and other nations have listed DMF as a restricted toxic substance. Various renowned European sellers have demanded that the products be DMF-free, which we (Ocean Plastics) can achieve. Note: DMF is also sometimes referred to as DMFA.
DMFu is "dimethyl fumarate." Unlike DMF (dimethylformamide--a solvent used in traditional PU synthetic leather processes), DMFu (dimethyl fumarate) is more of an anti-fungal chemical people place in their sofas or leather products to prevent mold from growing. Ocean Plastics' PU products do not use DMFu; they're DMFu-free, and we've made our products DMF-free as well.
Our eco-friendly PU product lines can replace all the products traditional PU leather can be applied on: balls, footwear, furniture, massage chairs, apparel, etc. There is NO limit on what type of product can make use of our eco-friendly PU leather.
Ocean Plastics Co., Ltd. (OPC) initiated R&D in Water-Based PU Synthetic Leather in 1998 and began producing Water-Based PU Synthetic Leather in 2001. Moreover, we actually decided, very early on, to synthesize our own Water-Based PU Resin to control to our synthetic leather’s quality. Therefore, we were able to overcome technical hurdles and defy the stereotype that Water-Based PU had weak physical strengths and properties. In fact, we have been delivering our products for sporting goods that require strong physical performance properties, like balls and hockey skates, etc. We can adjust our PU’s physical properties according to our clients’ needs, providing Water-Based PU products with physical properties equal to or even better in strength than traditional solvent-based PU.
PU material is affected by moisture in the air, so PU leather would crack and break down into small flakes that peel off the leather after a time period--this is called "hydrolysis." Our hydrolysis resistance lasts for about 4~5 years, which means that under normal circumstances, it will not break down until after 4~5 years. "Yellowing" refers to the phenomenon where white or light-color PU leather turns yellowish under the effect of sunlight or sources of UV rays in the surrounding environment; our material will pass the non-yellowing test with grade level 4~5 out of 5. "NOx" are chemicals that turn PU reddish brown; our material is resistant to that for a degree as well.
This is a bit technical. Hopefully, the below information gives you a basic picture of the differences and similarities:
(A) “Waterborne PU” is just another word for “Water-Based PU,” where the raw material PU resin particles are dispersed in mostly water. To make synthetic leather, we coat this resin onto a substrate (e.g. release paper), and dry the resin with heat to form a soft, solid PU layer on the substrate. This is how we at Ocean Plastics (OPC) make our PU synthetic leather.
(B) “Wet-Process PU” refers to the traditional solvent-based PU, where the PU resin particles are dissolved in dimethylformamide (DMF), an organic solvent. To make synthetic leather, the manufacturer coats a layer of this solvent-based PU resin on a textile substrate and immerse the coated textile into tanks of water to coagulate the PU resin into a similar soft, solid PU layer on the substrate. Because of this water-tank process, people call this the “Wet Process,” so solvent-based PU with this process is called “Wet-Process PU.” However, during this process, more energy is consumed than the Water-Based system above, and the DMF would migrate from the PU resin to the water in the water tanks, creating chemical waste water problems. Meanwhile, DMF also vaporizes into the air as harmful VOCs for the human body and the environment. We do not use this method.
(C) Sometimes, we hear of “Wet-Process Water-Based PU.” How can water-based and solvent-based PU vocabulary be put together in the same phrase? Well, it’s the production process of synthetic leather again. Some manufacturers use water-based PU resin to make synthetic leather by coating the water-based PU resin on a textile substrate, then immersing the coated substrate into tanks of water filled with acids. Since the water-based PU resin is slightly alkaline, the acid in the water coagulates the PU resin into the soft, solid PU layer. Because water tanks are used again, but the raw material PU resin is water-based, people sometimes call this “Wet-Process Water-Based PU.” However, this process creates salt compounds left in the water, and the water becomes industrial waste water, creating a similar waste water problem like the traditional solvent-based Wet Process. The process also requires more energy consumption than the Water-Based PU without wet process. We do not use this method
As with any products, in time with enough R&D, you can overcome technical hurdles. Ocean Plastics Co., Ltd. (OPC) initiated R&D in Water-Based PU in 1998, and we began producing Water-Based PU Synthetic Leather in 2001. We synthesize our own raw material—Water-Based PU Resin—to control the synthetic leather’s texture, strength, and chemical make-up. Therefore, we have made technical headways defying the stereotype that Water-Based PU feels more rigid. With years of experience, we can manufacture Water-Based PU Synthetic Leather whose hand feel, texture, and physical strength properties span from the very soft to the very hard / firm end of the spectrum. For instance, manipulating our Water-Based PU’s softness and creating different degrees of draping, for years, we have successfully delivered very soft Water-Based PU Synthetic Leather for headphone ear covers (hydrolysis-resistant 5+ years) and very firm / strong materials for hockey skates.