Polyvinyl alcohol (PVOH) was first synthesised in the early 1920’s but was largely replaced by polyethylene, polypropylene and PET because it is very difficult to process in blown film and extrusion. There are a number of global manufacturers of PVOH but a high percentage of the material is used only as an intermediate to produce other polymers. Most PVOH used in packaging applications has a lower hydrolysis level, which makes it react to water at temperatures of around 30℃. As a result, it is used principally for applications where its water-solubility is the most important factor, such as in detergent pods, and it is processed using solution-casting, which is slow and expensive.
The PVOH is processed predominantly in the form of a flake, which makes it less stable in thermo-processing and in storage. Hydropol™ has been formulated using PVOH polymers with a high hydrolysis level, which gives much greater resistance to solubility in water. The film produced using Hydropol™ reacts to water at controlled temperatures typically between 40℃ and 70℃, which makes it far more robust in ambient temperatures and therefore functional in packaging applications. Its formulated pelletised form also makes it easier to extrude in standard thermo-processes and so it can be turned more easily into a blown film, can be co-extruded or laminated onto traditional plastics, bioplastics or paper, extrusion coated onto film or paper or even injection moulded into a rigid form. Hence it can be used in a much wider range of applications than cold water-soluble flake.