Retreaded tire

Abstract

Provided is a retreaded tire that uses cushion rubber for retread that is able to further improve the prevention of separation failure while effectively suppressing blowout within the cushion rubber layer. The retreaded tire includes cushion rubber for retread, a base tire, and precured tread rubber formed of at least one rubber layer, and is characterized by: the aforementioned cushion rubber for retreaded tires being formed from a rubber composition containing specific quantities of a highly reinforcing carbon black of at least HAF grade, and natural rubber and/or synthetic polyisoprene rubber; the 100% modulus (A.sub.M) of the rubber layer (A) that comprises the aforementioned cushion rubber for retread being at least 3.0 MPa and less than 6.0 MPa; and the outermost layer (B) of the aforementioned base tire and the innermost layer (C) of the aforementioned precured tread rubber being formed from a rubber composition containing specific quantities of natural rubber and/or synthetic polyisoprene rubber.

Claims

1. A retreaded aircraft tire comprising cushion rubber for retread, a base tire comprising a skeletal carcass member, and precured tread rubber formed of at least one rubber layer, wherein the cushion rubber for retread contains, in 100 mass % of a rubber component, 60 to 100 mass % of natural rubber and/or synthetic polyisoprene rubber, and also contains, based on 100 parts by mass of the rubber component, 30 to 50 parts by mass of a highly reinforcing carbon black of at least HAF grade, wherein the cushion rubber for retread forms a rubber layer (A) having a 100% modulus (A.sub.M) of at least 3.0 MPa and less than 6.0 MPa, and wherein the base tire has an outermost layer (B) located in a depth of 1mm in the inner center direction of the tire from the outermost surface of a buffed surface of the base tire at some distance from the skeletal carcass member and the precured tread rubber has an innermost layer (C), the outermost layer (B) and the inner most layer (C) each being formed of a rubber composition containing, in 100 mass % of a rubber component, 60 to 100 mass % of natural rubber and/or synthetic polyisoprene rubber and wherein the rubber layer (A) formed of the cushion rubber for retread has the 100% modulus (A.sub.M), the outermost layer (B) of the base tire has the 100% modulus (B.sub.M), and the innermost layer (C) of the precured tread rubber has the 100% modulus (C.sub.M), the 100% moduluses (A.sub.M), (B.sub.M) and (C.sub.M) satisfying a relation defined by the following expressions (i) and (ii);
60%A.sub.M/B.sub.M140%(i)
60%A.sub.M/C.sub.M140%(ii) wherein the rubber composition forming the cushion rubber for retread further contains, based on 100 parts by mass of the rubber component, 1.0 to 3.0 parts by mass of a bismaleimide compound represented by the following Formula (III); ##STR00007## in Formula (III), A represents a divalent aromatic group having 6 to 18 carbon atoms, or a divalent alkyl-aryl group having 7 to 24 carbon atoms, and y and z each independently represent an integer of 0 to 3.

2. The retreaded aircraft tire according to claim 1, wherein the rubber composition forming the cushion rubber for retread further contains, based on 100 parts by mass of the rubber component, 0.1 to 4.0 parts by mass of at least one thiuram compound selected from a group consisting of a compound represented by the following Formula (I) and a compound represented by the following Formula (II); ##STR00008## (in Formula (I), R.sup.1 to R.sup.4 each independently represent a benzyl group or an alkyl group having 1 to 18 carbon atoms, and x is 2 to 18 as an average number); ##STR00009## (in Formula (II), R.sup.5 to R.sup.8 each independently represent a benzyl group or an alkyl group having 1 to 18 carbon atoms).

3. The retreaded aircraft tire according to claim 1 comprising a retreaded aircraft tire formed through vulcanization adhesion by means of a precure method.

4. The retreaded aircraft tire according to claim 2 comprising a retreaded aircraft tire formed through vulcanization adhesion by means of a precure method.

5. The retreaded aircraft tire according to claim 1 wherein the cushion rubber for retread contains, in 100 mass % of a rubber component, 80 to 100 mass % of natural rubber and/or synthetic polyisoprene rubber.

Description

EXAMPLES

(1) In the following, the present invention is specifically described with reference to Examples. However, the present invention is no way limited by those Examples.

Examples 1 to 7, Comparative Examples 1 to 8

(2) According to the ingredient formulation shown in Tables 1 to 2, rubber compositions were formed with further addition of based on 100 parts by mass of a rubber component, 3.0 parts by mass of a stearic acid, 5.0 parts by mass of a zinc oxide, 2.0 parts by mass of an antioxidant (NOCRAC 6C manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.), 1.5 to 3.5 parts by mass of sulfur, and a vulcanization accelerator as appropriate and each of the rubber compositions thus formed were applied to the cushion rubber layer (A), the outermost layer (B) of the base tire, and the innermost layer (C) of the precured tread rubber, to thereby manufacture aircraft radial retreaded tires (in a size 308.8 R15 16PR) through cold process. The following evaluations were made on the retreaded tires thus manufactured.

(3) <<Measurement of 100% Modulus>>

(4) Rubber sheets of 0.3 mm in thickness were cut out from each member of the obtained retreaded tires, which were further cut by a DINS3A-type knife edge, to thereby form test samples. The samples were subjected to measurements of the 100% modulus (A.sub.M) of the cushion rubber (A), of the 100% modulus (B.sub.M) of the outermost layer (B) of the base tire, and of the 100% modulus (C.sub.M) of the innermost layer (C) of the precured tread rubber, under the condition of a pulling rate of 100 mm/minute, so as to obtain the modulus contrasts of A.sub.M/B.sub.M and of A.sub.M/C.sub.M. The results are shown in Tables 1 to 2.

(5) <<Drum Durability Test>>

(6) The obtained retreaded tires were each mounted on a rim, to thereby form a rim assembly. The rim assembly thus formed was attached to a drum tester, so as to be tested for one cycle according to TSO-C62 d approved by the U.S. Federal Aviation Administration (FAA), and evaluations were made based on the following criteria. The results are shown in Tables 1 to 2.

(7) No failure: No blowout occurred within the rubber layer (A) and nothing abnormal was detected at any of the interfaces between the rubber layers (A) to (C).

(8) Blowout: Blowout occurred within the rubber layer (A).

(9) Separation: A separation failure occurred in the vicinity of any of the interfaces between the rubber layers (A) to (C).

(10) TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Ingredient Rubber natural rubber*.sup.1 100 100 100 100 80 70 100 Formulation layer (A) SBR*.sup.2 20 30 carbon black (N220) 35 35 carbon black (N330) 48 40 40 40 40 carbon black (N550) thiuram compound*.sup.3 0.5 0.5 0.5 0.5 bismaleimide*.sup.4 2.5 2.5 1.7 1.7 1.7 1.7 Rubber natural rubber*.sup.1 100 100 100 100 80 70 70 layer (B) SBR*.sup.2 20 30 30 Rubber natural rubber*.sup.1 100 100 80 70 70 70 70 layer (C) BR*.sup.5 20 30 30 30 30 100% modulus A.sub.M (MPa) 3.1 5.3 3.1 3.9 3.9 3.9 4.0 A.sub.M/B.sub.M (%) 64 110 64 82 78 85 89 A.sub.M/C.sub.M (%) 71 125 81 96 94 94 98 Results of Drum Durability Test no failure no failure no failure no failure no failure no failure no failure

(11) TABLE-US-00002 TABLE 2 Compar- Compar- Compar- Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative ative ative ative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Ingredient Rubber natural rubber*.sup.1 100 100 50 100 100 100 70 100 Formulation layer (A) SBR*.sup.2 50 30 carbon black (N220) 35 28 carbon black (N330) 55 40 40 40 52 carbon black (N550) 50 thiuram compound*.sup.3 0.5 1.0 0.5 0.5 0.5 0.5 0.5 0.5 bismaleimide*.sup.4 1.0 2.0 1.7 1.7 2.7 2.5 Rubber natural rubber*.sup.1 100 100 100 50 100 100 100 100 layer (B) SBR*.sup.2 50 Rubber natural rubber*.sup.1 100 100 70 100 50 100 100 100 layer (C) BR*.sup.5 30 50 100% modulus A.sub.M (Mpa) 2.8 6.3 3.9 4.0 3.9 5.2 5.9 3.0 A.sub.MM/B.sub.M (%) 59 125 82 90 81 109 122 62 A.sub.M/C.sub.M (%) 65 147 96 94 101 118 137 68 Results of Drum Durability Test blowout separation separation separation separation blowout blowout blowout

(12) *1: RSS#3

(13) *2: tin tetrachloride-modified styrene-butadiene rubber manufactured by JSR Corporation (which contains styrene by 5% and vinyl by 34%).

(14) *3: 1,6-Bis (N,N-diisobutylcarbamoyldithio)hexan

(15) *4: N,N-(4,4-diphenylmethane) bismaleimide

(16) *5: butadiene rubber, BR01, manufactured by JSR Corporation

(17) Tables 1 to 2 show that the retreaded tires of Examples 1 to 7 which use the aforementioned cushion rubber, base tire rubber and precured tread rubber demonstrate more excellent durability as compared to Comparative Examples 1 to 8.