Fiber mat, method of making the fiber mat, and bituminous roofing product

1. A fiber mat comprises:

a nonwoven assembly of chopped fibers comprising a minority portion and a majority portion, the minority portion forming a first layer, the minority portion comprising a set of chopped polymer fibers and a majority portion forming a second layer, the majority portion comprising a set of chopped fibers different than the minority portion, wherein the minority portion is less than 10 weight % of a total composition of the fiber mat and wherein the majority portion is greater than 90 weight % of a total composition of the fiber mat; and

a binder comprising an organic resin, wherein an air permeability of said fiber mat is not substantially different from an equivalent weight fiber mat containing a homogenous mat structure being homogenous in fiber distribution throughout the entirety of the mat, the homogenous mat structure comprising a homogenous blend of the chopped fibers of the minority portion and the chopped fibers of the majority portion and wherein the fiber mat provides at least a 5% increase in tear strength when placed in a bituminous roofing product compared to an equivalent bituminous roofing product made with the equivalent weight fiber mat containing the homogenous mat structure as measured by ASTM D1922; and

at least one coating of asphalt.

2. The fiber mat of claim 1 , wherein the fiber mat has an air permeability of at least 750 CFM/ft 2 .

3. The fiber mat of claim 1 , wherein the polymer fibers have a melting temperature (T m ) greater than about 200° C.

4. The fiber mat of claim 3 , wherein the polymer fibers comprise polyester, polyethylene terephthalate, polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyether ether ketone (PEEK), polyether ketone (PEK), polyacrylonitrile, polystyrene, nylon, polymethyl methacrylate (PMMA), polybenzimidazole (PBI), polyimide, polyether imide (PEI), polyamide-imide (PAI), polyether sulfone (PES), polyphenyl sulfone (PPSU), polyphenylsulfide (PPS), liquid crystal polymer (LCP), ethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), a blend, or combination thereof.

5. The fiber mat of claim 4 , wherein the polymer fibers comprise polyethylene terephthalate.

6. The fiber mat of claim 1 , wherein the polymer fibers are present at an amount of about 0.5 weight % to about 10 weight % —of the total weight of the assembly of fibers.

7. The fiber mat of claim 1 , wherein the minority portion is directly in contact with the majority portion at an interface, wherein the interface has a substantially distinct segregation between the minority portion and the majority portion.

8. The fiber mat of claim 1 , wherein a center plane of the minority portion is closer in distance to one surface of the fiber mat.

9. The fiber mat of claim 1 , wherein a center plane of the minority portion is approximately coincident to a center plane of the fiber mat.

10. The fiber mat of claim 1 , wherein the minority portion comprises a substantially random orientation of chopped fibers.

11. The fiber mat of claim 1 , wherein the majority portion comprises a substantially random orientation of chopped fibers.

12. The fiber mat of claim 1 , wherein the set of fibers of the majority portion comprises a glass fiber, a polymer fiber, a basalt fiber, a mineral fiber, or combination thereof.

13. The fiber mat of claim 1 , wherein the binder is substantially uniformly distributed throughout the fiber mat.

14. The fiber mat of claim 1 , wherein the fiber mat has a tensile strength at least 80% of a value of tensile strength of a fiber mat of equivalent weight containing the homogenous mat structure.

15. The fiber mat of claim 1 , wherein the fiber mat has a tensile strength at least 80% of a value of tensile strength of a higher caliper fiber mat having the homogenous mat structure.

16. The fiber mat of claim 1 , wherein a bituminous roofing product comprising the fiber mat has a tear strength at least 80% of a value of tear strength of an equivalent bituminous roofing product comprising a higher caliper fiber mat having a homogenous mat structure.

17. A bituminous roofing product comprises a fiber mat comprising a nonwoven assembly of chopped fibers comprising a minority portion and a majority portion, the minority portion forming a first layer, the minority portion comprising a set of chopped polymer fibers and a majority portion forming a second layer, the majority portion comprising a set of chopped fibers different than the minority portion, wherein the minority portion is less than 10 weight % of a total composition of the fiber mat and wherein the majority portion is greater than 90 weight % of a total composition of the fiber mat; and

a binder comprising an organic resin, wherein an air permeability of said fiber mat is not substantially different from an equivalent weight fiber mat containing a homogenous mat structure being homogenous in fiber distribution throughout the entirety of the mat, the homogenous mat structure comprising a homogenous blend of the chopped fibers of the minority portion and the chopped fibers of the majority portion and wherein the fiber mat provides at least a 5% increase in tear strength when placed in a bituminous roofing product compared to an equivalent bituminous roofing product made with the equivalent weight fiber mat containing the homogenous mat structure as measured by ASTM D1922; and

at least one coating of asphalt.

18. The bituminous roofing product of claim 17 , wherein the asphalt substantially impregnates a plurality of interstices between the assembly of fibers.