# US 10,766,703 B2 · Conveyor belt pulley cover combining low rolling resistance with enhanced ozone resistance

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- Number: US 10,766,703 B2
- Document ID: US10766703B2
- Status: Granted
- Kind: B2
- Application number: 16/373,700
- Filed: 2019-04-03
- Published: 2019-07-25
- Granted: 2020-09-08
- Earliest claimed: 2016-06-29
- Assignees: ContiTech USA, Inc.
- Applicants: ContiTech USA, Inc.
- Inventors: Heng-Huey Yang; Thomas George Burrowes; Guangzhuo Rong
- Web page: https://patentgrep.com/patent/US10766703B2

## CPC

- B32B 25/10: next to a fibrous or filamentary layer
- B65G 15/32: made of rubber or plastics
- B29D 29/06: Conveyor belts
- B32B 3/08: characterised by added members at particular parts {(layer formed of separate pieces of material which are juxtaposed side-by-side B32B3/14, B32B3/18)}
- B32B 5/02: characterised by structural features of a {fibrous or filamentary} layer {(layer formed of metallic wires B32B15/02; layer formed of natural mineral fibres B32B19/02; layer formed of wood fibres B32B21/02)}
- B32B 25/02: with fibres or particles {being present as additives in the layer}
- B32B 25/04: comprising rubber as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a layer of a particular substance B32B9/043; next to a bituminous or tarry layer B32B11/044; next to a water setting substance layer B32B13/042; next to a metal layer B32B15/06; next to a glass layer B32B17/063; next to a layer formed of natural mineral fibres or particles B32B19/043; next to a wood layer B32B21/045; next to a cellulosic plastic layer B32B23/046)}
- B32B 25/12: comprising natural rubber
- B32B 25/16: comprising polydienes {homopolymers} or poly-halodienes {homopolymers (B32B25/12 takes precedence)}
- B65G 15/00: Conveyors having endless load-conveying surfaces, i.e. belts and like continuous members, to which tractive effort is transmitted by means other than endless driving elements of similar configuration (having load-conveying surfaces formed by interconnected longitudinal links B65G17/06)
- B65G 15/34: with reinforcing layers, e.g. of fabric
- C08L 7/00: Compositions of natural rubber
- C08L 9/00: Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
- B32B 2250/03: 3 layers
- B32B 2264/108: Carbon, e.g. graphite particles
- B32B 2270/00: Resin or rubber layer containing a blend of at least two different polymers
- B32B 2307/536: Hardness
- B32B 2307/54: Yield strength; Tensile strength
- B32B 2307/546: Flexural strength; Flexion stiffness
- B32B 2307/5825: Tear resistant
- B32B 2307/584: Scratch resistance
- B32B 2433/02: Conveyor belts
- C08L 2205/03: containing three or more polymers in a blend
- C08L 2205/035: containing four or more polymers in a blend
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B65G: TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS (packaging B65B; handling thin or filamentary materials, e.g. paper sheets or thread, B65H; cranes B66C; portable mobile or lifting or hauling appliances, e.g. hoists, B66D; devices for lifting or lowering goods for loading or unloading purposes, e.g. fork-lift trucks, B66F9/00; emptying bottles, jars, casks, barrels or similar containers, not otherwise provided for, B67C9/00; delivering or transferring liquids B67D; filling or discharging vessels for liquefied, solidified or compressed gases F17C; pipe-line systems for fluids F17D)
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## Abstract

Conveyor belts having an outer cover layer, an opposing inner cover layer, and a carcass disposed between the outer and inner cover layers. The outer cover layer includes a sulfur cured rubber formulation formed from a blend including from about 20 phr to about 40 phr of an EPDM elastomer, from about 1 phr to about 40 phr of a polybutadiene rubber, and from about 30 phr to about 80 phr of a natural rubber. The sulfur cured rubber formulation may include a sulfur curative in an amount of from about 1.0 phr to about 4.0 phr. The sulfur cured rubber formulation may exhibits no cracking under dynamic ozone testing conditions of 50 pphm ozone, 25% strain, and 40 deg C., at 168 hours, in accordance with ASTM D1149, and may have a rolling resistance factor value of from 0.05 to 0.06 at a temperature of 25 deg C.

## Claims

### Claim 1

A conveyor belt comprising an outer cover layer, an opposing inner cover layer, and a carcass layer disposed between the outer cover layer and the inner cover layer, wherein the outer cover layer comprises a sulfur cured rubber formulation comprising a blend of from 20 phr to 40 phr of an EPDM elastomer, from 1 phr to 40 phr of a polybutadiene rubber, from 30 phr to 80 phr of a natural rubber, and at least one of N330 carbon black or N220 carbon black incorporated in an amount of from 45 phr to 50 phr, and wherein after curing, the curable rubber formulation has a dynamic ozone resistance failure time of from 96 hours to 168 hours after exposure to conditions of 50 pphm ozone, 25% strain, and 104° F.

### Claim 2 (depends on 1)

The conveyor belt according to claim 1, wherein the sulfur cured rubber formulation comprises a blend of from 25 phr to 35 phr of the EPDM elastomer, from 20 phr to 30 phr of the polybutadiene rubber, and from 40 phr to 50 phr of the natural rubber.

### Claim 3 (depends on 1)

The conveyor belt according to claim 1, wherein the sulfur cured rubber formulation comprises a sulfur curative in an amount of from 1.0 phr to 4.0 phr.

### Claim 4 (depends on 1)

The conveyor belt according to claim 1, wherein the sulfur cured rubber formulation comprises the sulfur curative in an amount of from 1.0 phr to 2.0 phr.

### Claim 5 (depends on 1)

The conveyor belt according to claim 1, wherein the sulfur cured rubber formulation further comprises paraffinic wax in an amount of from 0.75 phr to 1.5 phr.

### Claim 6 (depends on 1)

The conveyor belt according to claim 1, wherein the sulfur cured rubber formulation has a rolling resistance factor value of from 0.05 to 0.06 at a temperature of 25 deg C.

### Claim 7 (depends on 1)

The conveyor belt according to claim 1, wherein the conveyor belt is a pipe conveyor belt.

### Claim 8

A pipe conveyor belt comprising an outer cover layer, an opposing inner cover layer, and a carcass layer disposed between the outer cover layer and the inner cover layer, wherein the outer cover layer comprises a sulfur cured rubber formulation comprising a blend of from 25 phr to 35 phr of an EPDM elastomer, from 10 phr to 30 phr of a polybutadiene rubber, from 40 phr to 50 phr of a natural rubber, and at least one of N330 carbon black or N220 carbon black incorporated in an amount of from 45 phr to 50 phr, wherein the sulfur cured rubber formulation exhibits no cracking under dynamic ozone testing conditions of 50 pphm ozone, 25% strain, and 40 deg C., in accordance with ASTM D1149, wherein the sulfur cured rubber formulation has a rolling resistance factor value of from 0.05 to 0.06 at a temperature of 25 deg C. and wherein after curing, the curable rubber formulation has a dynamic ozone resistance failure time of from 96 hours to 168 hours after exposure to conditions of 50 pphm ozone, 25% strain, and 104° F.

### Claim 9 (depends on 8)

The pipe conveyor belt according to claim 8, wherein the sulfur cured rubber formulation comprises a sulfur curative in an amount of from 1.0 phr to 4.0 phr.

### Claim 10 (depends on 9)

The pipe conveyor belt according to claim 9, wherein the sulfur cured rubber formulation comprises the sulfur curative in an amount of from 1.0 phr to 2.0 phr.

### Claim 11 (depends on 8)

The pipe conveyor belt according to claim 8, wherein the sulfur cured rubber formulation further comprises paraffinic wax in an amount of from 0.75 phr to 1.5 phr.

### Claim 12

A curable rubber formulation comprising a blend of from 20 phr to 40 phr of an EPDM elastomer, from 10 phr to 40 phr of a polybutadiene rubber, from 30 phr to 60 phr of a natural rubber, a sulfur curative, and at least one of N330 carbon black or N220 carbon black incorporated in an amount of from 45 phr to 50 phr, wherein after curing, the curable rubber formulation has a dynamic ozone resistance failure time of from 96 hours to 168 hours after exposure to conditions of 50 pphm ozone, 25% strain, and 104° F.

### Claim 13 (depends on 12)

The curable rubber formulation according to claim 12, wherein the formulation comprises a blend of from 25 phr to 35 phr of the EPDM elastomer, from 20 phr to 30 phr of the polybutadiene rubber, and from 40 phr to 50 phr of the natural rubber.

### Claim 14 (depends on 12)

The curable rubber formulation according to claim 12, wherein the formulation comprises the sulfur curative in an amount of from 1.0 phr to 4.0 phr.

### Claim 15 (depends on 12)

The curable rubber formulation according to claim 12, wherein the formulation further comprises paraffinic wax in an amount of from 0.75 phr to 1.5 phr.

### Claim 16 (depends on 12)

The curable rubber formulation according to claim 12, wherein after being cured, the cured rubber formulation has a rolling resistance factor value of from 0.05 to 0.06 at a temperature of 25 deg C.

### Claim 17 (depends on 12)

The curable rubber formulation according to claim 12, wherein the sulfur curative is comprised of a sulfur donor/accelerator.

### Claim 18 (depends on 12)

The curable rubber formulation according to claim 12, wherein the sulfur curative is comprised of free sulfur.