C - Chemistry – Metallurgy – 08 – L
Patent
C - Chemistry, Metallurgy
08
L
C08L 95/00 (2006.01) E04D 11/02 (2006.01)
Patent
CA 2277648
-19- Improved coal tar compositions are described which are prepared from a blend comprising: (A) from about 80 parts to about 98 parts by weight of coal tar having an overall float test of from about 50 seconds to about 220 seconds, (B) from about 2 parts to about 20 parts by weight of coal tar pitch having a softening point of from about 140°C to about 160°C, and (C) from about 1 % to about 20% by weight, based on the total weight of the composition, of an acrylonitrile-butadiene copolymer. In one embodiment up to 35 parts by weight of the coal tar (A) is replaced with a coal tar selected from coal tars having softening points of from about 52°C - 60°C, and from about 56°C - 64°C. The coal tar compositions are not emulsion, and generally will not contain any significant amount of water (e.g., less than 0.5% by weight). The invention also relates to a process for preparing the coal tar compositions which comprises the steps of: (A) preparing at an elevated temperature, a first mixture comprising (A-1) from about 80 parts to about 98 parts by weight of coal tar having an overall float test of from about 50 seconds to about 220 seconds, and (A-2) from about 2 parts to about 20 parts by weight of coal tar pitch having a softening point of from about 140°C to about 160°C, (B) maintaining the first mixture at a temperature of at least about 170°C, (C) adding to the first mixture, from about 1 % to about 20% by weight, based on the total weight of the composition, of an acrylonitrile-butadiene copolymer to form a second mixture and (D) mixing the copolymer into the second mixture. The coat tar compositions of the present invention are useful particularly as roofing, waterproofing and maintenance materials. More particularly, the coal tar compositions are useful in built-up roofing (BUR) applications. The -20- coatings formed from the coal tar compositions of the invention exhibit improved tensile, elongation and recovery characteristics, improved fatigue resistance, improved adhesive qualities, and improved cold temperature performance.
Brzozowski Kenneth J.
Chernotowich Ken
Gowling Lafleur Henderson Llp
W.p. Hickman Systems Inc.
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