New Copolymer for the Manufacture of Special Membranes

Special membranes are needed wherever materials have to be separated from one another in a particularly gentle way, i.e. without the application of heat or chemicals. With thousands of tiny pores, they cleanse drinking water of bacteria or facilitate the concentration of juices. In dialysis, the special filters free human blood from toxins. The polyvinylpyrrolidone (PVP) Luvitec is an important component in the manufacture of membranes. Now, the new Luvitec VA 6535 P is even better tailored to the requirements of the membrane industry.

Optimal for the food industry

“With its characteristic profile, the new product is particularly well suited to sensitive membrane applications such as food production or medical devices,” said Dr. Stephan Bauer, Technical Marketing Luvitec.

The residual monomer content of Luvitec VA 6535 P is less than 10 ppm (parts per million), thus meeting the European directive on plastic materials in contact with foodstuffs (directive 2007/19/EC), and is proven to be toxicologically harmless. Additionally, on account of its higher water-repellent properties in comparison to other PVP products, the new Luvitec is compatible with plastics such as polysulfone (PSU), polyethersulfone (PES) and polyvinylidene fluoride (PVDF); used in the manufacture of membranes. Luvitec puts the pores in the membrane

Membranes used in dialysis are mostly hollow fiber membranes - a capillary-like fiber. These fibers can be manufactured from a solution of plastic and PVP by means of the so-called wet-spinning process. Subsequently the water-soluble PVP is washed out of the fiber, leaving many thousands of tiny pores and channels. A small proportion of the PVP, some one to two percent, provides for a hydrophilic surface, ensuring the optimal exchange of materials during filtration.

A real all-rounder

But Luvitec VA 6535 P is not only suitable for the production of membranes. On account of its significantly lower glass transition temperature of 115 degrees Celsius, the new product can also be used in the manufacture of water-soluble hot melt adhesives. Applications are, for example in wetness indicator strips for diapers. But there are also many fields of application in the agricultural sector, as a special additive or as a coating polymer for seed coatings.