Rubber composition for tires and tire using same

Abstract

To solve such a problem that recently in a pneumatic tire for heavy duty or construction vehicle, the case where silica is blended in a naturel rubber increases, but it is extremely difficult to obtain favorable dispersion of silica in the natural rubber, and it is difficult to obtain a desired dispersibility even if for example, a silane coupling agent is used.SOLUTION: The above problem is solved by providing a rubber composition for tire prepared by blending 0.1-20 pts.mass of specific acetylene-based compound, 20-120 pts.mass of silica and 1-15 pts.mass of silane coupling agent based on 100 pts.mass of diene-based rubber including natural rubber of 50 pts.mass or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a rubber composition for tires and a tire using the same, and more particularly to a rubber composition for tires that has excellent abrasion resistance, improved modulus, and low heat build-up even when natural rubber is blended therein, and a tire using the same. [Background technology]

[0002] In recent years, there has been an increase in the use of silica in natural rubber in pneumatic tires for heavy loads or construction vehicles (see, for example, Patent Document 1). However, it is extremely difficult to disperse silica well in natural rubber, and even if a silane coupling agent is used, it is difficult to obtain the desired dispersibility. On the other hand, rubber compositions for tires are required to have a high modulus and also to have low heat build-up from the viewpoint of achieving low rolling resistance and reducing the environmental load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-59826 A Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, an object of the present invention is to provide a rubber composition for tires which has excellent abrasion resistance, improved modulus and low heat build-up even when natural rubber is blended therein, and a tire using the same. [Means for solving the problem]

[0005] As a result of extensive research, the inventors have discovered that the above-mentioned problems can be solved by a rubber composition containing specific amounts of natural rubber, silica and a silane coupling agent, as well as a specific amount of an acetylene-based compound having a specific structure, and have thus completed the present invention.

[0006] That is, the present invention provides a composition comprising the following components for 100 parts by mass of diene rubber containing 50 parts by mass or more of natural rubber: 0.1 to 20 parts by mass of an acetylene compound represented by the following formula (1), Silica, 20 to 120 parts by mass; 1 to 15 parts by mass of a silane coupling agent The present invention provides a rubber composition for tires, which is characterized by being obtained by compounding the above-mentioned components.

[0007] [ka]

[0008] (In formula (1), m+n is 0 to 20.) Effect of the Invention

[0009] The rubber composition of the present invention contains specific amounts of natural rubber, silica, and a silane coupling agent, as well as a specific amount of an acetylene-based compound having the specific structure represented by formula (1) above. This makes it possible to provide a rubber composition for tires that has excellent abrasion resistance, improved modulus, and low heat build-up, and a tire using the same. It is generally known that natural rubber and carbon black have an affinity. On the other hand, the acetylene compound represented by the formula (1) in the present invention can increase the affinity between carbon black and silica, and as a result, the silica can be well dispersed in the natural rubber. Thus, when the rubber composition of the present invention contains carbon black, it can exert an excellent effect. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will now be described in further detail. (Diene rubber) The diene rubber used in the present invention contains natural rubber (NR) as an essential component. The amount of NR is preferably 50 parts by mass or more, and more preferably 70 parts by mass or more, based on 100 parts by mass of the total diene rubber. From the viewpoint of improving the effects of the present invention, it is preferable that, in 100 parts by mass of diene rubber, natural rubber accounts for 70 parts by mass or more, and the remainder is one or more types selected from styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR) and synthetic isoprene rubber (IR). In addition, the diene rubber used in the present invention may be any diene rubber that can be blended in a rubber composition, such as acrylonitrile-butadiene copolymer rubber (NBR) or ethylene-propylene-diene terpolymer (EPDM). These may be used alone or in combination of two or more. There are no particular limitations on the molecular weight or microstructure, and the diene rubber may be terminally modified with amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl, or the like, or may be epoxidized.

[0011] (Acetylene compounds) The acetylene compound used in the present invention is represented by the following formula (1).

[0012] [ka]

[0013] In formula (1), m+n is 0 to 20, preferably 1 to 20, and more preferably 2 to 12. An acetylene compound in which m+n is 1 or more, i.e., an ethylene oxide group is contained, can further improve the dispersibility of silica. The acetylene compound used in the present invention may be a commercially available product, for example, Acetylenol (trade name) manufactured by Kawaken Fine Chemicals Co., Ltd., Surfynol (trade name) manufactured by Evonik Industries Ltd., and the like.

[0014] (silica) From the viewpoint of improving the effect of the present invention, the silica used in the present invention has a CTAB adsorption specific surface area of ​​100 to 240 m 2 / g, and 120 to 220 m 2 It is even more preferred that the weight ratio is / g. The CTAB adsorption specific surface area is a value obtained by measuring the amount of n-hexadecyltrimethylammonium bromide adsorbed on the silica surface in accordance with JIS K6217-3:2001 "Part 3: Determination of specific surface area - CTAB adsorption method."

[0015] (Silane coupling agent) The silane coupling agent used in the present invention is not particularly limited, but is preferably a sulfur-containing silane coupling agent, such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, etc. Silane coupling agents may be used alone or in combination of two or more.

[0016] (Carbon Black) The rubber composition of the present invention may contain carbon black. From the viewpoint of improving the effects of the present invention, the carbon black should have a nitrogen adsorption specific surface area (N2SA) of 30 to 180 m 2 / g, and 40 to 140m 2 It is even more preferred that the weight ratio is / g. The nitrogen adsorption specific surface area (N2SA) is a value measured in accordance with JIS K 6217-2:2001 "Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0017] (Rubber composition blend ratio) The rubber composition of the present invention is characterized in that it is obtained by compounding 0.1 to 20 parts by mass of the acetylene compound represented by the formula (1), 20 to 120 parts by mass of silica, and 1 to 15 parts by mass of a silane coupling agent with respect to 100 parts by mass of diene rubber. If the amount of the acetylene-based compound is less than 0.1 parts by mass per 100 parts by mass of diene-based rubber, the amount is too small to achieve the effects of the present invention, and conversely, if it exceeds 20 parts by mass, the abrasion resistance will deteriorate. If the amount of silica is less than 20 parts by mass, the mechanical properties and abrasion resistance of the rubber composition deteriorate, whereas if it exceeds 120 parts by mass, the breaking properties deteriorate. If the amount of the silane coupling agent is less than 1 part by mass, the amount is too small to achieve the effects of the present invention, whereas if it exceeds 15 parts by mass, the breaking properties deteriorate.

[0018] The amount of the acetylene compound is preferably 0.5 to 15 parts by mass, and more preferably 1 to 10 parts by mass, based on 100 parts by mass of the diene rubber. The compounding amount of silica is preferably 40 to 80 parts by mass based on 100 parts by mass of the diene rubber. The amount of the silane coupling agent blended is preferably 1 to 10 parts by mass based on 100 parts by mass of the diene rubber. When carbon black is compounded, the compounding amount is preferably from 5 to 60 parts by mass, and more preferably from 10 to 50 parts by mass, based on 100 parts by mass of the diene rubber.

[0019] (Other ingredients) In addition to the above-mentioned components, the rubber composition of the present invention may contain various additives that are generally incorporated in rubber compositions, such as vulcanizing or crosslinking agents, vulcanizing or crosslinking accelerators, zinc oxide, antioxidants, and plasticizers, and these additives may be kneaded in a general manner to form a composition, which can be used for vulcanization or crosslinking. The amounts of these additives may be conventional amounts, provided that they do not violate the object of the present invention.

[0020] The tire of the present invention can be prepared using the rubber composition of the present invention, and is preferably a pneumatic tire, which can be filled with air, inert gas such as nitrogen, and other gases. The tire of the present invention is preferably applied to a tread, particularly a cap tread of a tire for heavy loads or construction vehicles. EXAMPLES

[0021] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0022] Examples 1 to 15, Comparative Examples 1 to 2 In the formulation (parts by mass) shown in Tables 1 and 2, the components other than the vulcanization system (vulcanization accelerator, sulfur) and the curing agent were mixed in a 1.7-liter closed Banbury mixer for 5 minutes, then discharged from the mixer and cooled at room temperature. The composition was then placed back into the Banbury mixer, and the vulcanization system was added and mixed to obtain a rubber composition. The rubber composition obtained was press-vulcanized at 160°C for 20 minutes, and its physical properties were measured using the test methods shown below.

[0023] Heat generation: Using a viscoelasticity spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd., tan δ (60°C) was measured under the conditions of initial strain = 10%, amplitude = ±2%, and frequency = 20 Hz, and the heat generation was evaluated based on this value. The results were expressed as an index, with the value of Comparative Example 1 or 2 being 100. The smaller the index, the lower the heat generation. 100% modulus (M100): A tensile test was carried out at 23° C. according to JIS K6251 to measure the tensile stress at 100% elongation. The results are expressed as an index, with Comparative Example 1 or 2 being 100. A larger index indicates a higher modulus. Abrasion resistance: According to JIS K6264-2, a Lambourn abrasion tester manufactured by Iwamoto Seisakusho was used, and measurements were taken under conditions of a load of 49 N, a slip rate of 25%, a time of 4 minutes, and room temperature. The results were expressed as an index, with the value of Comparative Example 1 or 2 being 100. A higher index indicates better abrasion resistance. The results are shown in Tables 1 and 2. Comparative Example 1 is compared with Examples 1 to 7, and Comparative Example 2 is compared with Examples 8 to 15.

[0024] [Table 1]

[0025] [Table 2]

[0026] *1:NR(STR20) *2: SBR (Nipol 1502 manufactured by Zeon Corporation) *3: Silica (ULTRASIL VN-3G manufactured by UNITED SILICA INDUSTRIAL, CTAB specific surface area = 147 m 2 / g) *4: Carbon black (Tokai Carbon Co., Ltd., Seast KH, N2SA=92m 2 / g) *5: Zinc oxide (Zinc oxide type 3 manufactured by Seido Chemical Industry Co., Ltd.) *6: Stearic acid (bead stearic acid manufactured by NOF Corp.) *7: Anti-aging agent (Flexis Santoflex 6PPD) *8: Silane coupling agent (Si69 manufactured by Evonik Degussa Japan) *9: Sulfur (Mu-Cron OT-20 manufactured by Shikoku Chemical Industries Co., Ltd.) *10: Vulcanization accelerator (Noccela CZ-G manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) *11: Acetylene-based compound 1 (product name Acetylenol E60 manufactured by Kawaken Fine Chemicals Co., Ltd., an acetylene-based compound represented by formula (1) in which m = 3 and n = 3) *12: Acetylene-based compound 2 (product name Acetylenol E100 manufactured by Kawaken Fine Chemicals Co., Ltd., an acetylene-based compound represented by formula (1) in which m = 5 and n = 5) *13: Acetylene-based compound 3 (product name Acetylenol E00 manufactured by Kawaken Fine Chemical Co., Ltd., an acetylene-based compound represented by formula (1) in which m = 0 and n = 0)

[0027] The results in Tables 1 and 2 show that the rubber composition of each Example is prepared by compounding 100 parts by mass of diene rubber containing 50 parts by mass or more of natural rubber with 0.1 to 20 parts by mass of the acetylene compound represented by formula (1), 20 to 120 parts by mass of silica, and 1 to 15 parts by mass of a silane coupling agent, and therefore has superior abrasion resistance, improved modulus, and low heat build-up properties compared to Comparative Examples 1 and 2. Comparative Examples 1 and 2 are examples in which the acetylene compound represented by the formula (1) was not blended.

Claims

1. For 100 parts by mass of diene rubber containing 50 parts by mass or more of natural rubber, 0.1 to 20 parts by mass of an acetylene-based compound represented by the following formula (1), 20 to 120 parts by weight of silica, and 1 to 15 parts by weight of a silane coupling agent A rubber composition for tires comprising: The rubber composition for tires further comprises carbon black. 【Chemistry 1】 (In formula (1), m+n is 0 to 20.)

2. 2. The rubber composition for tires according to claim 1, characterized in that 5 to 60 parts by mass of carbon black is blended with respect to 100 parts by mass of the diene rubber.

3. 3. The rubber composition for tires according to claim 1, wherein, based on 100 parts by mass of the diene rubber, natural rubber accounts for 70 parts by mass or more, and the remainder is one or more types selected from a styrene-butadiene copolymer rubber, a butadiene rubber, and a synthetic isoprene rubber.

4. 4. The rubber composition for tires according to claim 1, wherein, in the acetylene compound represented by formula (1), m+n is 1 to 20.

5. A tire using the rubber composition according to any one of claims 1 to 4.

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