Solventless, Electron Beam-Cured Acrylate Coating Formulations for Flexible Magnetic Media ManufactureEPA Grant Number: R826728
Title: Solventless, Electron Beam-Cured Acrylate Coating Formulations for Flexible Magnetic Media Manufacture
Investigators: Nikles, David E.
Institution: University of Alabama at Birmingham
EPA Project Officer: Richards, April
Project Period: October 1, 1998 through September 30, 2001
Project Amount: $285,000
RFA: Technology for a Sustainable Environment (1998) RFA Text | Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development
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 acrylate 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 acrylates polymerize 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 solventless coating process.
Approach:To realize a solventless, 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 acrylate monomers and oligomers must be identified that upon electron beam irradiation undergoes a free radical polymerization to give a binder polymer with the requisite mechanical properties. The acrylate monomers will be mixtures of commercial monoacrylates, diacrylates and triacrylates. The oligomers will be acrylate terminated urethanes. The magnetic particles will be treated with silane or titanate coupling agents. The coupling agents will contain acrylate or methacrylate functional groups that can participate in the free radical polymerization, thereby mechanically coupling the binder to the magnetic particles. The particles will therefore act as a reinforcing filler, strengthening the binder. New branched, acrylate-functionalized silane coupling agents will be synthesized and covalently bonded to the particle surface. The surface treatment will also aid in dispersing the particles in the acrylate monomers and give coating fluids with the proper rheological properties.
Expected Results:This project will provide new acrylate formulations for magnetic tape or floppy disk manufacture that will enable a solventless manufacturing process. Furthermore we will demonstrate the feasibility of using these formulations in the solventless manufacturing process. We will solve the particle dispersion and coating fluid rheology problem by covalently attaching methacrylate-functionalized silane coupling agents to the surface of the magnetic particles.
The solvents used in magnetic tape manufacture 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 solventless 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. The Internet has led to explosive growth in demand for digital data storage. Magnetic tape has filled the role of providing back-up storage for servers and electronic libraries. This new process will allow the domestic tape industry to maintain competitiveness, while also meeting the obligation to environmentally conscious manufacturing.