INVESTIGATION OF THE EFFECT OF A TOPICALLY APPLIED TACKIFIER IN REDUCING PARTICLE BOUNCE IN A MELT-BLOWN AIR FILTER

Many commercially available indoor air filters are currently being mar keted with tackifier filter adhesives applied to the surface of the fi bres or to the face of the filters, However, little information is ava ilable in the literature concerning the application of these tackifier s, and their effectiveness in reducing particle penetration through fi lters. It is of scientific value to investigate the efficacy of such t ackifiers, especially in the light of increasing concern for indoor ai r quality, The paper presents the ongoing results of an investigation in which polypropylene melt-blown media were manufactured under a vari ety of operating conditions, to produce media which might be suitable for use in indoor air quality filters, The filter media were prepared at the Textiles & Nonwovens Development Center (TANDEC), and tested fo r filtration efficiency in the Air Quality Laboratory housed in the De partment of Civil & Environmental Engineering at the University of Ten nessee, Knoxville, Efficiencies were determined using both cold, polyd ispersed dioctylpthalate (DOP), as well as monodispersed latex particl es (0.6 to 3.0 mu) using an ASTM 1215 filtration test stand. The objec tives of the research were to determine the initial efficiency of the media at velocities ranging from 3 to 375 cm/s, and to compare the mea sured results with filtration theory, At the higher velocities, typica l of those used in indoor air filters, the experimental efficiencies u sing dry particles were significantly less than both the DOP and theor etical efficiencies, because of the kinetic energy of the particles, w hich resulted in particle bounce. Empirical corrections were developed as a function of the kinetic energy to account for the decreased effi ciency resulting from particle bounce, and are presented. Tests were a lso conducted on a melt-blown medium in which the fibres were coated w ith various loadings of a tackifier, referred to here as being 'topica lly' applied, The results showed that the efficiencies at high velocit ies were improved as a result of the reduction in particle bounce, whi le the efficiencies at low velocities were unchanged even though large r effective fibre diameters resulted from application of the tackifier .