Roofing materials having engineered coatings
An asphalt-based roofing material includes a coating having a top portion containing a mixture of asphalt and igneous and/or metamorphic rock particles, while the mat portion of the coating contains a mixture of asphalt and a filler which contains less than 10% igneous and/or metamorphic rock particles. In other embodiments, the top portion but not the bottom portion of the coating meets or exceeds a pliability standard, passes a weathering performance test, or has a high solar reflectance. In another embodiment relating to a laminated roofing material, the top portion but not the bottom portion has viscoelastic properties effective to prevent the coating from sticking to an adjacent shingle in a bundle. The invention also relates to a continuous process of applying first and second coatings to a mat for manufacturing a roofing material. In a first coating operation, a first asphalt-based coating is continuously applied to a first surface of the mat so that the first coating saturates the mat and forms a layer on the first surface. In a second coating operation, a second asphalt-based coating is continuously applied to a second surface of the mat so that the second coating forms a layer on the second surface. The second coating has different properties from the first coating.
1. An asphalt-based roofing material comprising:
a mat saturated and coated with an asphalt-based coating, the coating including a top portion covering the top of the mat, a mat portion saturating the mat, and a bottom portion covering the bottom of the mat;
wherein the top portion of the coating comprises a mixture of asphalt and a filler, the filler comprising rock particles selected from the group consisting of igneous rock particles, metamorphic rock particles, and mixtures thereof; and
wherein the mat portion of the coating comprises a mixture of asphalt and filler, the filler containing no more than about 10% rock particles selected from the group consisting of igneous rock particles, metamorphic rock particles, and mixtures thereof, by weight of the filler.
2. A roofing material according to claim 1 wherein the filler in the mat portion of the coating comprises rock particles.
3. A roofing material according to claim 2 wherein the rock particles comprise sedimentary rock particles.
4. A roofing material according to claim 1 wherein the filler in the top portion of the coating comprises trap rock particles, and the filler in the mat portion of the coating comprises limestone particles.
5. A roofing material according to claim 1 wherein the bottom portion of the coating comprises a mixture of asphalt and filler, the filler containing no more than about 10% rock particles selected from the group consisting of igneous rock particles, metamorphic rock particles, and mixtures thereof, by weight of the filler.