Asphalt coated polyester glass mats
The present invention is based on the discovery that in order for polyester fibers to be used in a polyester/glass mat, which will have superior tear properties after being coated with bitumen, they need to have a single filament toughness of greater than about 140. Toughness being defined as the product of tenacity (in units of cN/tex) and the cube root of the breaking elongation (as a % of elongation). Specifically, the mat has polyester and glass fibers bound together with a binder, and the bound fibers are coated with asphalt. The invention also describes a process by which the web is dried and cured into a mat at a temperature of greater than about 200° C. The polyester is at least about 5 wt. % of the fibers in the coated mat.
1 ) a polyester/glass asphalt shingle having a higher tear strength compared to a glass shingle of the same basis weight.
2 ) A polyester/glass asphalt shingle, containing at least about 10 wt-% polyester of the fiber content, having a higher tear strength compared to a glass shingle of the same basis weight.
3 ) A polyester/glass asphalt shingle in which the polyester fiber has a toughness greater than about 140.
4 ) A method of preparing a polyester/glass mat comprising: uniformly blending polyester and glass fibers in an aqueous slurry; pouring said slurry on a drum or screen; de-watering said wet laid mat; coating said dried mat with a binder; curing said mat at a temperature above 200° C., and coating with asphalt.
5 ) A roofing shingle comprising: a uniform blend of polyester and glass fibers, and a binder, said fibers and binder coated with asphalt thereby forming a shingle.
6 ) The roofing shingle of claim 5 , wherein said fibers are from about 5 to about 50 wt. % polyester fibers and from about 95 to about 50 wt. % glass fibers.
7 ) The roofing shingle of claim 6 , wherein said polyester/glass fibers have a length in the range of about 5 to about 50 mm.
8 ) The roofing shingle of claim 6 , wherein said polyester/glass fibers have a mean diameter of about 7 to 50 microns, for a linear density of about 0.5 to 10 dtex.
9 ) The roofing shingle of claim 5 , wherein said binder is urea-formaldehyde resin.
10 ) The roofing shingle of claim 9 , wherein said binder is from about 15 to about 30% by weight of said blend of fibers.
11 ) The roofing shingle of claim 5 , wherein said polyester fiber has a toughness greater than about 140.