Solvent-less, Electron Beam-Cured Vinyl Ether Coating Formulations for Flexible Magnetic Media ManufactureEPA Grant Number: R827121
Title: Solvent-less, Electron Beam-Cured Vinyl Ether Coating Formulations for Flexible Magnetic Media Manufacture
Investigators: Nikles, David E.
Institution: University of Alabama - Tuscaloosa
EPA Project Officer: Shapiro, Paul
Project Period: October 1, 1998 through September 30, 2001
Project Amount: $328,209
RFA: Exploratory Research - Environmental Engineering (1998) RFA Text | Recipients Lists
Research Category: Engineering and Environmental Chemistry , Sustainability , Land and Waste Management
Description:The objective of our research program is to lead the flexible magnetic media industry into the 21st century by providing new tape and floppy disk manufacturing processes that prevent air pollution. Our approach is to replace the organic solvents used in the coating process with a mixture of liquid vinyl ether monomers. The monomers serve as the solvent to disperse the magnetic pigments and dissolve any other ingredients, rendering fluidity and coatability to the formulation. Upon electron beam irradiation, the monomers will undergo a cationic polymerization to give a solid binder with the requisite mechanical properties. The object of this research project is to identify the binder materials package that enables the solvent-less coating process.
Approach:To realize a solvent-less, electron beam-cured manufacturing process a number of materials problems must be solved. We will focus on a magnetic tape manufacturing process with the assumption that any successes can be adapted for use in floppy disk manufacture. A mixture of vinyl ether monomers and oligomers must be identified that upon electron beam irradiation undergoes a cationic polymerization to give a binder polymer with the requisite mechanical properties. The vinyl ether monomers will be mixtures of commercial monovinyl ethers, and divinyl ethers. The oligomers will be vinyl ether terminated urethanes. The magnetic particles will be treated with vinyl ether-terminated amine-quinone urethane oligomers. The amine-quinone oligomers will protect the iron particles against corrosion and provide vinyl ether groups that can react with the binder. The particles will therefore act as a reinforcing filler, strengthening the binder. The surface treatment will also aid in dispersing the particles in the vinyl ether monomers and give coating fluids with the proper rheological properties.
This project will provide new vinyl ether formulations for magnetic tape or floppy disk manufacture that will enable a solvent-less manufacturing process. Furthermore we will demonstrate the feasibility of using these formulations in the solvent-less manufacturing process. We will solve the particle dispersion and coating fluid rheology problem by chemi-sorbing vinyl ether-terminated amine-quinone urethane oligomers to the surface of the magnetic particles. We have previously shown that commercial coupling agents dramatically improve the dispersability of the particles, giving acrylate coating formulations with rherological properties similar to conventional, solvent-based formulations.
The solvents used in magnetic tape manufacture include MEK, MIBK and toluene, which are on the EPA's list of 189 hazardous air pollutants. A magnetic tape coating line can use more than 600 kg of organic solvents per hour and even with modern pollution controls can release more than 150 metric tons of solvent vapor to the environment per year. This solvent-less manufacturing process will reduce the emissions to zero. Furthermore, this process will lower the manufacturing costs by eliminating the organic solvents, eliminating the energy costs associated with drying, solvent recovery and recycle, and eliminating the costs of complying with the Clean Air Act Amendments, RCRA and TSCA.