# US 2014/0150943 A1 · Method for producing a tire comprising an improved tread with a foamed material

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- Number: US 2014/0150943 A1
- Document ID: US20140150943A1
- Status: Published application
- Kind: A1
- Application number: 14/114,521
- Filed: 2012-04-27
- Published: 2014-06-05
- Earliest claimed: 2011-04-28
- Assignees: Michelin Recherche et Technique S.A.; Compagnie Generale Des Etablissements Michelin
- Inventors: José Merino Lopez; Didier Vasseur
- Web page: https://patentgrep.com/patent/US20140150943A1

## CPC

- B29D 30/0662: {Accessories, details or auxiliary operations}
- B29D 30/0606: {Vulcanising moulds not integral with vulcanising presses (for solid tyres B29D30/02)}
- B29D 30/66: Moulding treads on to tyre casings, e.g. non-skid treads with spikes
- B60C 11/032: {Patterns comprising isolated recesses}
- B60C 11/0323: {tread comprising channels under the tread surface, e.g. for draining water}
- B60C 11/11: in which the raised area of the pattern consists only of isolated elements, e.g. blocks (B60C11/12, B60C11/13 take precedence)
- B29D 2030/0612: {Means for forming recesses or protrusions in the tyres, e.g. grooves or ribs, to create the tread or sidewalls patterns}
- B29D 2030/0613: {Means, e.g. sipes or blade-like elements, for forming narrow recesses in the tyres, e.g. cuts or incisions for winter tyres}
- B60C 2011/147: {Foamed rubber or sponge rubber on the tread band}
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES

## Abstract

A layer of cellular material forms a running layer (14A) of a tread (14) in which tread pattern elements (20, 22, 26) are made. In order to form the cellular material, an uncured blank is provided with a mass of material comprising p,p′-oxybis(benzenesulphonyl hydrazide) that forms a pore-forming agent. The uncured blank is placed in a vulcanization mold (28) comprising molding elements (30, 32, 34). At least 95% of the molding elements (30, 32, 34) each satisfy the following two conditions: a) the molding element (30, 32, 34) is separated from at least one other molding element (30, 32, 34) by a distance, expressed in millimetres, of less than or equal to DM=6.85+0.0065 T3, T, greater than or equal to 3 phr, being the amount of p,p′-oxybis(benzenesulphonyl hydrazide) in the mass of material intended to form the cellular material, b) the molding element (30, 32, 34) is intended to form a tread pattern element (20, 22, 26) having a depth at least equal to 80% of the thickness of the running layer (14A).

## Claims

### Claim 1

A process for manufacturing a tire in which an uncured blank of the tire is vulcanized in a mold,
this tire comprising a layer of cellular material that forms a running layer of a tread of the tire in which hollow tread pattern elements are made,
the running layer having
a thickness E, and
a degree of expansion of greater than or equal to 50%,
wherein:
the uncured blank is provided with a mass of material, comprising p,p′-oxybis(benzenesulphonyl hydrazide) that forms a pore-forming agent, this material comprising the pore-forming agent being intended to form the cellular material,
the uncured blank is placed in a vulcanization mold comprising molding elements for molding the hollow tread pattern elements,
the mold being such that at least 95% of the molding elements each satisfy the following two conditions a) and b):
a) the molding element is separated from at least one other molding element by a separation distance, expressed in millimetres, of less than or equal to
DM=6.85+0.0065 T3,
T being the amount of p,p′-oxybis(benzenesulphonyl hydrazide) in the mass of material intended to form the cellular material, and T being greater than or equal to 3 phr,
the separation distance between two molding elements being the shortest distance between these two molding elements travelled between these molding elements,
b) the molding element is intended to form a hollow tread pattern element having a depth at least equal to 80% of the thickness E of the running layer.

### Claim 2 (depends on 1)

The process according to claim 1, in which DM=5.9 +0.005 T3.

### Claim 3 (depends on 1, 2)

The process according to claim 1 or 2, in which the molding elements that satisfy the conditions a) and b) also satisfy the following condition: the molding element is intended to form a hollow tread pattern element chosen from
water evacuation channels that delimit, in the running layer, blocks of cellular material, and
blind holes made in these blocks so as to open radially.

### Claim 4 (depends on 1, 2)

A tire manufactured by implementing the process according to claims 1 or 2.