Power transmission belt and method

1. A process for reducing the angular vibration of a camshaft in relation to a crankshaft in an internal combustion engine wherein the camshaft is driven by a toothed belt comprising a cured elastomer belt body portion and a tensile member formed of a helically spiraled cord embedded therein; a cord treatment composition comprising an elastomer latex coating at least a portion of said cord, and characterized in that said process comprises the steps of:

a. selecting for said cord at least one yarn comprising a carbon fiber;

b. incorporating in said cord treatment composition a resorcinol-formaldehyde reaction product;

c. selecting the elastic modulus of said cord treatment composition at a temperature of 20° C. to be within the range of from about 1.0×10 7 dynes/cm 2 to about 5.0×10 8 dynes/cm 2 , and at a temperature of 100° C. to be within the range of from about 5.0×10 6 dynes/cm 2 to about 4.0×10 8 dynes/cm 2

d. applying said cord treatment composition to the cord to form a treated cord;

e. incorporating the treated cord into an un-cured elastomer composition to form an assembly; and

f. curing the assembly to form said toothed belt.

2. The process of claim 1 further comprising the step of selecting the tensile modulus of the cord to be in the range of from about 100 to about 300 GPa.

3. The process of claim 1 further comprising the step of selecting the tensile modulus of the cord to be in the range of from about 150 to about 275 GPa.

4. The process of claim 1 wherein the cured elastomer belt body portion comprises at least one elastomer selected from:

a. hydrogenated acrylonitrile butadiene elastomer;

b. polychloroprene;

c. acrylonitrile butadiene rubber;

d. styrene-butadiene rubber;

e. alkylated chlorosulfonated polyethylene;

f. epichlorohydrin,

g. butadiene rubber,

h. polyisoprene; and

i. ethylene alpha olefin elastomer.

5. The process of claim 4 wherein said elastomer belt body portion further comprises from about 0.5 to about 20 parts per hundred weight of elastomer of fibers.

6. The process of claim 1 wherein said elastomer latex of said cord treatment composition is at least one selected from:

a. hydrogenated acrylonitrile butadiene rubber latex;

b. acrylonitrile butadiene rubber latex;

c. carboxylated hydrogenated acrylonitrile butadiene rubber latex;

d. carboxylated acrylonitrile butadiene rubber latex

e. vinyl pyridine/styrene butadiene rubber latex;

f. carboxylated vinyl pyridine/styrene butadiene rubber latex;

g. styrene butadiene rubber latex;

h. chlorosulfonated polyethylene rubber latex; and

i. ethylene alpha olefin rubber latex.

7. The process of claim 1 further comprising the step of exposing said treated cord to a condition sufficient to bring the water content of said cord treatment to less than about 50% by weight based on said weight of said treated cord, to form a processed treated cord.

8. The process of claim 7 wherein said condition comprises a temperature and an exposure period to said temperature and said water content is brought to less than about 30% by weight.

9. The process of claim 7 wherein said water content is brought to a level in the range of from about 1% to about 25% by weight.

10. The process of claim 1 wherein said cord treatment is applied to said carbon fiber to achieve a cord treatment pick-up level on said carbon fiber in the range of from about 5.5% to about 30% based on the final dry fabric weight.

11. The process of claim 1 further comprising the step of applying an overcoat comprising a rubber-textile adhesive to said treated cord.

12. The process of claim 1 further comprising the steps of selecting said carbon fiber yarn to have a filament count in the range of from about 1000 to about 24000; and selecting said cord to possess a filament count in the range of from about 5000 to about 24000.

13. The process of claim 1 wherein said belt further comprises a fabric cover element disposed along at least one of a belt back surface and a belt toothed surface.