Power transmission belt

1. A belt comprising: a body and tensile members running in a longitudinal direction, the body having a pulley engaging region having a molded profile; the molded profile consisting of a surface layer around the profile, a main body portion comprising a first vulcanized elastomeric material, and a subsurface layer in between the surface layer and the main body portion; the subsurface layer consisting of a second vulcanized elastomeric material having a friction modifying agent; said first elastomeric material free of said friction modifying agent; and wherein the surface layer comprises a fibrous nonwoven fabric material co-mingled with the second elastomeric material; and wherein the friction modifying agent is a particulate solid or a non-blooming liquid.

2. The belt of claim 1 , wherein the friction modifying agent is at least one selected from the group consisting of waxes, oils, graphite, molybdenum disulfide, fluoropolymer, metal salt of carboxylic acid, boron nitride, mica, and talc.

3. The belt of claim 1 , wherein the friction modifying agent comprises a fluoropolymer selected from the group consisting of PTFE, PFA, and FEP; and said first elastomeric material does not comprise said friction modifying agent.

4. The belt of claim 1 , wherein the friction modifying agent is PTFE powder.

5. The belt of claim 1 , wherein the first elastomeric material comprises a fiber loading in the range of about 0.01 to about 20 parts per hundred parts elastomer, and wherein the second elastomeric material has no fiber loading.

6. The belt of claim 5 , wherein the fiber loading is in the range of 0.01 to 5 parts per hundred parts elastomer.

7. The belt of claim 6 , wherein fiber loading fibers are selected from the group consisting of aramid, acrylic, carbon, polyester, polyolefin, acrylic, polyimide, PVA, rayon, fiberglass, and nylon or two or more of the foregoing.

8. The belt of claim 1 , wherein the pulley engaging region has a thickness of from about 0.025 mm to about 3.0 mm.

9. The belt of claim 1 , wherein the pulley engaging region has a thickness of from about 0.025 mm to about 0.6 mm.

10. The belt of claim 1 , wherein the nonwoven material comprises a combination of softwood pulp and hardwood pulp.

11. The belt of claim 1 , wherein the nonwoven material comprises a combination of cellulosic fiber and synthetic fiber.

12. The belt of claim 11 , wherein the synthetic fiber comprises one of polyamide, acrylic, rayon, fiberglass, polyolefin, polyester, carbon, aramid, and a combination of two or more of the foregoing.

13. The belt of claim 12 wherein the synthetic fiber comprises from 50% to 100% by weight of the fibers of the nonwoven material.

14. The belt of claim 1 , wherein the surface layer comprises at least two layers of the fibrous nonwoven fabric material.

15. The belt of claim 1 , wherein the molded profile is a multi-v-ribbed profile.

16. The belt of claim 1 , wherein the molded profile is a v-belt profile.

17. A method of manufacturing a belt comprising the steps of:

laying up a first elastomeric and/or textile layer of a belt build on a mandrel;

laying up tensile cords on the first elastomeric and/or textile layer;

laying up a second elastomeric layer on the tensile cords;

laying up a third elastomeric layer comprising a friction-modifying agent directly on the second elastomeric layer, wherein the second elastomeric layer is free of said friction-modifying agent;

laying up a fibrous nonwoven fabric material on the third elastomeric layer;

curing the belt build in a profile-forming mold whereby said third elastomer layer forms a sub-surface layer comprising said friction-modifying agent along said profile between the nonwoven fabric material and the second elastomeric layer; and

cutting the belt build to predetermined belt widths.

18. The method of claim 17

wherein said curing further results in co-mingling of said third elastomer and said fibrous nonwoven fabric in said surface layer and further results in said second elastomer forming a main body portion of said belt with said third elastomer forming a subsurface layer in between said surface layer and said main body portion.

19. The method of claim 17 wherein the thickness of the third elastomeric layer is from about one fourth to about twice the thickness of the second elastomeric layer.

20. The method of claim 18 wherein the combined thickness of the third elastomeric layer plus the nonwoven material is from about one fourth to about twice the thickness of the second elastomeric layer.

21. The method of claim 18 wherein the friction-modifying agent is at least one selected from the group consisting of waxes, oils, graphite, carbon fiber, molybdenum disulfide, fluoropolymer, metal salt of carboxylic acid, boron nitride, mica, and talc.

22. The method of claim 18 wherein the friction-modifying agent is fluoropolymer, and the second elastomeric material is free of said friction-modifying agent.

23. A frictional power transmission belt comprising:

a body comprising tensile members and at least one rib running in a longitudinal direction;

said rib having an integrally molded, pulley engaging profile;

said rib consisting of:

a surface layer around the profile of the rib,

a rib material comprising a first vulcanized elastomeric material and forming the bulk of the rib, and

a subsurface layer in between the surface layer and the rib material;

the subsurface layer consisting of a second vulcanized elastomeric material having a friction modifying agent;

said second elastomeric material distinct from said first elastomeric material; and

wherein the surface layer comprises a fibrous nonwoven fabric material co-mingled with the second elastomeric material; and wherein the friction modifying agent is a fluoropolymer powder.

24. The belt of claim 23 comprising a plurality of said ribs, and wherein said profile is a multi-v-ribbed profile and said first elastomeric material is free of said friction modifying agent.