Pneumatic tire including cap layer and base layer
First Claim
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1. A pneumatic tire comprising a tread which is capable of contacting a road surface, a carcass which is a reinforcing component, and bead cores around which end parts of the carcass are folded to fix the end parts in place and which define the inner dimension of the pneumatic tire,wherein the tread comprises two layers which are a cap layer disposed at the outside in a radial direction of the tire and a base layer disposed inside the cap layer in the radial direction;
- the base layer comprises a rubber composition which comprises a rubber component composed of 70% by weight or more of a copolymer of a conjugated diene and a vinyl aromatic hydrocarbon and a remaining amount of another synthetic rubber and/or natural rubber, at least one reinforcing filler selected from the group consisting of carbon black and silica, and at least one vulcanization accelerator represented by one of the following general formulas;
##STR2## wherein R1 and R2 each independently represents a hydrogen atom, an alkyl group or an aryl group, excluding the case in which each of R1 and R2 simultaneously represents a hydrogen atom;
wherein the cap layer comprises a rubber composition and the rubber composition of the cap layer is different from that of the base layer;
an upper end of the base layer is disposed at a height from a bottom of a groove adjacent a block in a range of 40% to 80% of the distance from the bottom of the groove to a top of the block;
a storage modulus (E'"'"' value) of the base layer is 95 to 80 as expressed in terms of an index based on an E'"'"' value of the cap layer which is set as an index of 100; and
an internal loss (tan δ
) of the base layer is 105 or more as expressed in terms of an index based on a tan δ
of the cap layer which is set as an index of 100, which tan δ
is measured at 0°
C. at 50 Hz and a dynamic strain of 1%.
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Abstract
A pneumatic tire comprising a tread which contacts a road surface and comprises a rubber composition which contains a rubber component composed of 70% by weight or more of a copolymer of a conjugated diene and a vinyl aromatic hydrocarbon and a remaining amount of another synthetic rubber and/or natural rubber, at least one reinforcing filler selected from a group consisting of carbon black and silica, and at least one type of vulcanization accelerator, such as bis(4-methylbenzothiazolyl-2)-disulfide, bis(5-methylbenzothiazolyl-2)-disulfide, mercapto-4-methylbenzothiazole, and mercapto-5-methylbenzothiazole, an amount of the reinforcing filler being 45 to 120 parts by weight and an amount of the vulcanization accelerator being 0.5 to 5.0 parts by weight per 100 parts by weight of the rubber component. Decrease in chipping resistance during tire use is suppressed, and both abrasion resistance and controllability on wet roads after use of the tire are improved.
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Citations
18 Claims
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1. A pneumatic tire comprising a tread which is capable of contacting a road surface, a carcass which is a reinforcing component, and bead cores around which end parts of the carcass are folded to fix the end parts in place and which define the inner dimension of the pneumatic tire,
wherein the tread comprises two layers which are a cap layer disposed at the outside in a radial direction of the tire and a base layer disposed inside the cap layer in the radial direction; -
the base layer comprises a rubber composition which comprises a rubber component composed of 70% by weight or more of a copolymer of a conjugated diene and a vinyl aromatic hydrocarbon and a remaining amount of another synthetic rubber and/or natural rubber, at least one reinforcing filler selected from the group consisting of carbon black and silica, and at least one vulcanization accelerator represented by one of the following general formulas;
##STR2## wherein R1 and R2 each independently represents a hydrogen atom, an alkyl group or an aryl group, excluding the case in which each of R1 and R2 simultaneously represents a hydrogen atom;wherein the cap layer comprises a rubber composition and the rubber composition of the cap layer is different from that of the base layer; an upper end of the base layer is disposed at a height from a bottom of a groove adjacent a block in a range of 40% to 80% of the distance from the bottom of the groove to a top of the block; a storage modulus (E'"'"' value) of the base layer is 95 to 80 as expressed in terms of an index based on an E'"'"' value of the cap layer which is set as an index of 100; and an internal loss (tan δ
) of the base layer is 105 or more as expressed in terms of an index based on a tan δ
of the cap layer which is set as an index of 100, which tan δ
is measured at 0°
C. at 50 Hz and a dynamic strain of 1%. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A pneumatic tire comprising a tread which is capable of contacting a road surface, a carcass which is a reinforcing component, and bead cores around which end parts of the carcass are folded to fix the end parts in place and which define the inner dimension of the pneumatic tire,
wherein the tread comprises two layers which are a cap layer disposed at the outside in a radial direction of the tire and a base layer dispersed inside the cap layer in the radial direction, the base layer comprises a rubber composition which comprises a rubber component composed of 70% by weight or more of a copolymer of a conjugated diene and a vinyl aromatic hydrocarbon and a remaining amount of another synthetic rubber and/or natural rubber, a reinforcing filler comprising silica, and at least one vulcanization accelerator represented by one of the following general formulas: - ##STR3## wherein R1 and R2 each independently represents a hydrogen atom, an alkyl group, or an aryl group, excluding a case in which each of R1 and R2 simultaneously represents a hydrogen atom, the amount of the reinforcing filler being 45 to 120 parts by weight per 100 parts by weight of the rubber component and the amount of the vulcanization accelerator being 0.5 to 5.0 parts by weight per 100 parts by weight of the rubber component,
the cap layer comprises a rubber composition and the rubber composition of the cap layer is different from that of the base layer, an upper end of the rubber base layer is disposed at a height from a bottom of a groove adjacent a block in a range of 40% to 80% of the distance from the bottom of the groove to a top of the block, a storage modulus (E'"'"' value) of the base layer is 95 to 80 as expressed in terms of an index based on an E'"'"' value of the cap layer which is set as an index of 100, and an internal loss (tan δ
) of the base layer is 105 or more as expressed in terms of an index based on a tan δ
of the cap layer which is set as an index of 100 which tan δ
is measured at 0°
C. at 50 Hz and a dynamic strain of 1%.
- ##STR3## wherein R1 and R2 each independently represents a hydrogen atom, an alkyl group, or an aryl group, excluding a case in which each of R1 and R2 simultaneously represents a hydrogen atom, the amount of the reinforcing filler being 45 to 120 parts by weight per 100 parts by weight of the rubber component and the amount of the vulcanization accelerator being 0.5 to 5.0 parts by weight per 100 parts by weight of the rubber component,
Specification
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Current AssigneeBridgestone Corporation
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Original AssigneeBridgestone Corporation
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InventorsNakamura, Eiji, Sasaka, Naohiro, Ohashi, Masayuki
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Primary Examiner(s)Maki, Steven D.
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Application NumberUS08/890,753Time in Patent Office1,117 DaysField of Search152/209 R, 152/209.5, 152/905, 152/902, 152/209.18, 524/492, 524/493, 524/495, 524/496US Class Current152/209.5CPC Class CodesB60C 1/0016 Compositions of the treadB60C 11/005 with cap and base layersC08K 5/47 ThiazolesC08L 21/00 Compositions of unspecified...Y10S 152/905 Tread composition
