Filter elements
AssigneeMonsanto Chemicals Limited
InventorsSamuel Baxter, Pushpkumar Dewanmal Changani
Life of this patent
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Abstract
A polyolefin filter for tobacco products and the like was prepared. The extruded element is an open-cell foamed polyethylene or polypropylene having a TPM filtration efficiency greater than 20 percent. The filter rod can be made by extruding polyethylene containing less than 0.2 moles of a volatile blowing agent per 100 grams of resin at a melt temperature between 130.degree.C. and 150.degree.C., the temperature of the die being between 120.degree.C. and 136.degree.C. Higher melt temperature and die temperature are required for polypropylenes.
Claims18
A rod shaped cigarette filter comprised of a polypropylene foam or a foam of high density polyethylene, said foam having a substantially opencell structure wherein more than half of the cells present contain cell walls which are perforated, and wherein the microstructure of said foam is characterized by the presence of numerous fine fibre-like elements having thicknesses within the range of from about 0.1 to 2 microns which bridge across said perforations in the cell walls, said fibre-like elements being interconnected with each other or with the part of the cell wall that forms the boundary of the perforation and thereby being substantially free of loose ends;
- said cigarette filter having a TPM filtration efficiency of from 20 to 60 percent, a .DELTA.P.sub.10 of from about 0.5 to 15 centimeters water gauge, and a hardness of from about 50 to 100 percent, said percent hardness being determined by subjecting a 120 millimeter length sample of said cigarette filter rod of predetermined initial diameter to compression under a 300 gram load for 15 seconds and thereafter measuring the rod diameter to determine the decrease in initial diameter, the percent hardness is then calculated from the equation:
- Percent hardness = [(D - A)/D] .times. 100
- wherein D represents the initial diameter of the rod and A represents the decrease in said initial diameter following 15 seconds under said load.
A rod shaped cigarette filter comprised of a polypropylene foam or a foam of high density polyethylene, said foam having a substantially opencell structure wherein more than half of the cells present contain cell walls which are perforated, and wherein the microstructure of said foam is characterized by the presence of two-dimensional webs of interconnected fibre-like elements which extend across said perforations in the cell walls, said interconnected fibre-like elements having thicknesses within the range of from 0.1 to 2 microns;
- said cigarette filter having a TPM filtration efficiency of from 20 to 60 percent, a.DELTA.P.sub.10 of from about 0.5 to 15 centimeters water gauge, and a hardness of from about 50 to 100 percent, said percent hardness being determined by subjecting a 120 millimeter length sample of said cigarette filter rod of predetermined initial diameter to compression for 15 seconds under a 300 gram load and thereafter measuring the rod diameter to determine the resulting decrease in said initial diameter, the percent hardness is then calculated from the equation:
- Percent hardness = [(D - A)/D] .times. 100
- wherein D represents the initial diameter of the rod and A represents the decrease in said initial diameter following 15 seconds under said load.
Dependencies are inferred from the claim text.