RUBBER COMPOSITION FOR CUSHION RUBBER FOR REHABILITATED TIRES, AND A REHABILITATED TIRE USING THE SAME

Abstract

The present invention provides a rubber composition for cushion rubber for rehabilitated tire having a vulcanized speed being fast and a scorch resistance property being superior while being adaptable to environmental issues, as well as provides a rehabilitated tire having a durability. This rehabilitated tire may include a rubber composition for cushion rubber for rehabilitated tire which includes at least a rubber component comprising a diene rubber, di-2-benzothiazolyl disulfide and 1,3-diphenylguanidine, and a cushion rubber formed by vulcanizing the rubber composition for cushion rubber for rehabilitated tire.

Claims

1: A rubber composition for cushion rubber for rehabilitated tires, comprising: a rubber component comprising a diene rubber, di-2-benzothiazolyl disulfide and 1,3-diphenylguanidine.

2: The rubber composition for cushion rubber for rehabilitated tires according to claim 1, wherein assuming that a blending amount of the 1,3-diphenylguanidine is W(D) and a blending amount of the di-2-benzothiazolyl disulfide is W(DM), the rubber composition for a cushion rubber for a rehabilitated tire satisfy 0.2≤W(D)/W (DM)≤2.0.

3: A rehabilitated tire, comprising a cushion rubber formed by vulcanizing the rubber composition for cushion rubber for rehabilitated tire according to claim 1.

4: A rehabilitated tire, comprising a cushion rubber formed by vulcanizing the rubber composition for cushion rubber for rehabilitated tire according to claim 2.

Description

EXAMPLES

[0024] Hereinafter, the examples are explained.

(1) Maximum Torque (MH) and Vulcanization Speed (T90) in a Vulcanization Behavior Measurement Test of an Unvulcanized Rubber Composition by Means of a Rheometer:

[0025] In accordance with JIS K6300-2: 2013, a maximum torque (MH) and a vulcanization speed (T90) were measured in a vulcanization behavior measurement test of an unvulcanized rubber composition. T90 is a time (minute) from the start of the measurement to reach a torque of 90% of (MH-ML), assuming that the maximum value of the torque is MH and the minimum value thereof is ML, in a vulcanization behavior measurement experiment test of an unvulcanized rubber composition by means of a rheometer. In each evaluation, it is expressed by an index evaluation when Comparative Example 1 is assumed to be 100. As the index of MH is higher, it means that the torque is larger. As the index of T90 is smaller, it means that the vulcanization speed is faster.

(2) Scorch Resistance Property (Scorch Time t5)

[0026] In accordance with JIS K6300, a rotorless Mooney measurement machine manufactured by Toyo Seiki Manufacturing Co. Ltd. was used to measure a time t5 to increase a 5 Mooney unit from the lowest viscosity Vm after preheating an unvulcanized rubber composition at 125° C. for one minute. Assuming that a value of Comparative Example 1 is 100, and those of Comparative Example 2 and Example 1 were expressed by an index. As the value becomes bigger, it means that the scorch time becomes longer and it is superior in the scorch resistance property.

(3) Break Strength

[0027] A rubber sample was prepared by vulcanizing an unvulcanized rubber sheet of the Examples and the Comparative Examples at 120° C. for 30 minutes. In accordance with JIS K6251, a tensile test (Dumbbell Type No. 3) was carried out to measure a tensile strength of the rubber sample. The evaluation results of the break strength were expressed by an index, assuming that the values of the tensile strength of Comparative Examples 1 and 2 are 100. As its value becomes larger, it means that it was superior in the break strength.

[0028] Preparation of Rubber Composition

[0029] In accordance with the blending prescription shown in Table 1, each of the rubber compositions of Example 1 and Comparative Examples 1-2 were provided. Using a Banbury Mixer for kneading, the rubber compositions were prepared. Each of the agents described in Table 1 are explained below. In Table 1, the blending amount of each agent is based on parts by mass with respect to 100 parts by mass of the rubber component.

a) The natural rubber (NR) is RSS #3;
b) The styrene butadiene rubber (SBR) is NIPOL 1502 manufactured by Zeon Corporation;
c) The butadiene rubber (BR) is UBEPOL BR150B manufactured by Ube Industries Corporation;
d) The carbon black 1 is Show Black N326 manufactured by Cabot Japan Corporation;
e) The carbon black 2 is Show Black N330T manufactured by Cabot Japan Corporation;
f) The stearic acid is stearic acid manufactured by NOF Corp.;
g) The zinc oxide is the second type of zinc oxide manufactured by Mitsui Mining And Smelting Company;
h) The antioxidant is NOCRAC 6C manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.;
i) The oil is Process P200 manufactured by JX Nippon Oil & Energy Co., Ltd.;
j) The adhesion addition agent is ESCOLETS 1102 manufactured by Exxon Mobil Corp.;
k) The sulfur is powdery sulfur manufactured by Tsurumi Chemical Industry Co., ltd.;
l) Vulcanization accelerator DM (di-2-benzothiazolyl disulfide) is NOCCELER DM manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.;
m) Vulcanization accelerator M (2-mercaptobenzothiazole) is NOCCELER M manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.:
n) Vulcanization accelerator DPG (1,3-diphenylguanidine) is NOCCELER D manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.:
o) Vulcanization accelerator PZ (dimethyl dithiocarbamic acid zinc) is NOCCELER PZ manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.;
p) Vulcanization accelerator ZTC (dibenzyl dithiocarbamic acid zinc) is NOCCELER ZTC manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.; and
q) VULKALENT is VULKALENT E/C manufactured by Lanxess Corporation.

TABLE-US-00001 TABLE 1 Comp 1 Comp 2 Ex. 1 Ex. 2 First NR 100 100 100 100 blend SBR — — — — BR — — — — Carbon 25 25 25 25 Black 1 Carbon 15 15 15 15 Black 2 stearic acid 2 2 2 2 zinc oxide 3 3 3 3 antioxidant 3 3 3 3 oil 15 15 15 15 adhesion 5 5 5 5 addition agent DPG — 0.3 — — Final sulfur 3 3 3 3 blend D (DPG) 0.3 — 0.7 0.5 DM — — 0.5 0.7 M 0.5 0.5 — — PZ 0.4 — — — ZTC — 0.8 — — VULKALENT 0.1 0.1 0.1 0.1 W(D)/W(DM) — — 1.4 0.7 Evaluated MH 100 100 105 101 property Evaluated Scorch time 100 110 110 109 property t5 Evaluated T90 100 89 87 90 property Evaluated Break 100 100 107 103 property strength Ex. 3 Ex. 4 Ex. 5 Ex. 6 First NR 100 80 80 80 blend SBR — 20 — 10 BR — — 20 10 Carbon 25 25 25 25 Black 1 Carbon 15 15 15 15 Black 2 stearic acid 2 2 2 2 zinc oxide 3 3 3 3 antioxidant 3 3 3 3 oil 15 15 15 15 adhesion 5 5 5 5 addition agent DPG — — — — Final sulfur 3 3 3 3 blend D (DPG) 0.8 0.7 0.7 0.7 DM 0.4 0.5 0.5 0.5 M — — — — PZ — — — — ZTC — — — — VULKALENT 0.1 0.1 0.1 0.1 W(D)/W(DM) 2 1.4 1.4 1.4 Evaluated MH 102 102 104 103 property Evaluated Scorch time 106 113 111 112 property t5 Evaluated T90 93 91 89 90 property Evaluated Break 102 103 105 104 property strength

[0030] The results in Table 1 show that the rubber composition of Example 1 had a vulcanization speed being fast and was superior in the scorch resistance property. In addition, its vulcanized rubber had a high torque and a high break strength, finding that it was superior in the durability.

[0031] It is preferable that the MH of the rubber composition of the present invention is higher than that of Comparative Example 1 (i.e., MH=100), and is more preferable in a range of 101 and 120 from, and yet more preferable in a range of 101 and 105. As shown in Table 1, the MH of the rubber composition of the Examples is higher than that of Comparative Example 1, thereby meaning that it had a large torque.

[0032] The T90 of the rubber composition of the present invention is preferably smaller than that of Comparative Example 1 (i.e., T90=100), and more preferably in a range of 99 or less, and yet more preferably in a range of 70 to 90, and furthermore preferably in a range of 87 to 93. As shown in Table 1, T90 of the rubber compositions of the Examples were smaller than that of Comparative Example 1, meaning that it had a vulcanized speed being fast.