Rubber composition and tire

Abstract

Provided is a rubber composition having satisfactory low heat buildup properties and excellent wear resistance. The rubber composition comprises a rubber ingredient and carbon blacks, and is characterized in that the rubber ingredient comprises natural rubber and butadiene rubber, the proportion of the natural rubber being less than 80 mass%, the carbon blacks are contained in an amount of 40-100 parts by mass per 100 parts by mass of the rubber ingredient, and if carbon blacks A, B, and C are defined by given conditions, then said carbon blacks comprise carbon black A and carbon black B and the content of carbon black C therein is zero or is the least of the contents of the carbon blacks A to C.

Description

[Technical field]

[0001] The present invention relates to a rubber composition and a tire. [Background technology]

[0002] In rubber articles such as tires, the demand for wear resistance is increasing year by year. As a method for improving wear resistance, for example, blending a large amount of carbon black into the rubber composition used in the rubber article or reducing the particle size of the carbon black blended into the rubber composition has been studied.

[0003] However, the above-mentioned methods have a problem in that they deteriorate the low heat generation property. Since wear resistance and low heat generation property are generally in a trade-off relationship, there is a need to develop a technology that can achieve both of these properties at a high level.

[0004] For example, Patent Document 1 discloses that by using two types of carbon black and setting the nitrogen adsorption specific surface area, compressed dibutyl phthalate absorption amount, iodine adsorption amount, and the like within predetermined ranges, it is possible to improve low heat generation while maintaining excellent abrasion resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-164985 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, it is difficult to say that the technology described in Patent Document 1 above provides sufficient performance, and there is still a demand for achieving both low heat generation and wear resistance at an even higher level.

[0007] Therefore, an object of the present invention is to provide a rubber composition having good low heat buildup properties and excellent abrasion resistance, and also to provide a tire having low heat buildup properties and excellent abrasion resistance. [Means for solving the problem]

[0008] The gist of the present invention for solving the above problems is as follows.

[0009] The rubber composition of the present invention is a rubber composition containing a rubber component and carbon black, The rubber component contains natural rubber and butadiene rubber, and the proportion of the natural rubber is less than 80% by mass, The amount of the carbon black is 40 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component, Here, the nitrogen adsorption specific surface area is 125 m 2 / g or more 200m 2 / g or less and a toluene coloring transmittance of 80% or more is defined as carbon black A. Nitrogen adsorption specific surface area is 90m 2 / g or more 124m 2 / g or less is designated as carbon black B, When carbon black other than carbon black A and carbon black B is carbon black C, The carbon black is characterized in that it contains at least the carbon black A and the carbon black B, and the content of the carbon black C is 0 or is the smallest among the carbon blacks A to C.

[0010] The tire of the present invention is characterized by using the above-mentioned rubber composition. Effect of the Invention

[0011] According to the present invention, it is possible to provide a rubber composition having good low heat buildup properties and excellent abrasion resistance. Also, according to the present invention, it is possible to provide a tire having low heat buildup properties and excellent abrasion resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The rubber composition and tire of the present invention will be described in detail below with reference to examples based on embodiments thereof.

[0013] <Rubber composition> A rubber composition according to one embodiment of the present invention (hereinafter sometimes referred to as "rubber composition according to this embodiment") contains a rubber component and carbon black. The rubber component in the rubber composition according to this embodiment contains natural rubber and butadiene rubber, and the proportion of the natural rubber is less than 80 mass %. The rubber composition according to this embodiment contains the carbon black in an amount of 40 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component.

[0014] Furthermore, in the rubber composition of this embodiment, the nitrogen adsorption specific surface area (N2SA) is 125 m 2 / g or more 200m 2 Carbon black having a specific surface area of ​​90 m 2 / g or more 124m 2 / g or less is defined as carbon black B, and carbon black other than carbon black A and carbon black B is defined as carbon black C. The carbon black contains at least carbon black A and carbon black B, and the content of carbon black C is either 0 or the smallest among carbon blacks A to C.

[0015] In the rubber composition of the present embodiment, the rubber component and at least two types of carbon black are optimized as described above, and therefore the rubber composition has excellent low heat buildup properties and excellent abrasion resistance.

[0016] In this specification, the nitrogen adsorption specific surface area of ​​carbon black is measured in accordance with JIS K6217-2. In this specification, the toluene coloring transmittance of carbon black is measured in accordance with JIS K6218-4.

[0017] The rubber composition of the present embodiment does not contain a wet master batch, a coated filler, or the like.

[0018] (Rubber component) The rubber component in the rubber composition of the present embodiment must contain at least natural rubber (NR) and butadiene rubber (BR), which can improve the abrasion resistance of the rubber composition of the present embodiment.

[0019] The proportion of natural rubber in the rubber component is less than 80% by mass. If the proportion of natural rubber is 80% by mass or more, there is a risk of the abrasion resistance being deteriorated. From the same viewpoint, the proportion of natural rubber in the rubber component is preferably 75% by mass or less, and more preferably 70% by mass or less.

[0020] The proportion of butadiene rubber in the rubber component is more than 20% by mass. If the proportion of butadiene rubber is 20% by mass or less, the effect of improving abrasion resistance cannot be sufficiently obtained. From the same viewpoint, the proportion of butadiene rubber in the rubber component is preferably 25% by mass or more, and more preferably 30% by mass or more.

[0021] The rubber component in the rubber composition of the present embodiment may contain a rubber component other than natural rubber and butadiene rubber. Examples of rubber components other than natural rubber and butadiene rubber include isoprene rubber (IR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, and acrylonitrile-butadiene rubber (NBR). These rubber components may be used alone or in combination of two or more. However, from the viewpoint of improving abrasion resistance and low heat generation in a well-balanced manner, it is preferable that the rubber component is composed of only natural rubber and butadiene rubber.

[0022] (Carbon Black) As described above, the rubber composition of the present embodiment contains carbon black A, i.e., carbon black having a nitrogen adsorption specific surface area of ​​125 m 2 / g or more 200m 2 The rubber composition of the present embodiment contains, as an essential component, carbon black having a viscosity of 100 / g or less and a toluene color transmittance of 80% or more. In other words, the carbon black in the rubber composition of the present embodiment contains at least carbon black A. Carbon black A may be used alone or in combination of two or more types.

[0023] Here, the nitrogen adsorption specific surface area of ​​carbon black A is 125 m 2 The reason why the specific surface area of ​​carbon black A is set to 200 m / g or more is to effectively improve the abrasion resistance of the rubber composition of the present embodiment by using the carbon black B described later in combination. 2 The reason why the specific surface area is set to 130 m / g or less is to maintain the low heat buildup property of the rubber composition of the present embodiment. From the same viewpoint, the nitrogen adsorption specific surface area of ​​the carbon black corresponding to carbon black A used in the present embodiment is set to 130 m 2 / g or more, and 2 / g or less, and 2 It is more preferable that the molecular weight is not more than 1 / g.

[0024] Furthermore, the reason why the toluene color transmission of carbon black A is set to 80% or more is to effectively improve the abrasion resistance while maintaining the low heat buildup property of the rubber composition of this embodiment by using it in combination with carbon black B described later. From the same viewpoint, the toluene color transmission of the carbon black corresponding to carbon black A used in this embodiment is preferably 83% or more, more preferably 85% or more, and even more preferably 90% or more.

[0025] As described above, the rubber composition of the present embodiment contains carbon black B, i.e., carbon black having a nitrogen adsorption specific surface area of ​​90 m 2 / g or more 124m 2 / g or less as an essential component. In other words, the carbon black in the rubber composition of the present embodiment includes at least carbon black B. Carbon black B may be used alone or in combination of two or more types.

[0026] Here, the nitrogen adsorption specific surface area of ​​carbon black B is 90 m 2 The reason why the nitrogen adsorption specific surface area of ​​carbon black B is set to 124 m / g or more is to effectively improve the abrasion resistance of the rubber composition of the present embodiment by using the carbon black B in combination with the above-mentioned carbon black A. 2 / g or less is set in order to maintain the low heat buildup property of the rubber composition of the present embodiment. From the same viewpoint, the nitrogen adsorption specific surface area of ​​the carbon black corresponding to carbon black B used in the present embodiment is set to 100 m 2 / g or more, and 2 It is preferable that the molecular weight is not more than 1 / g.

[0027] The toluene coloring transmittance of the carbon black corresponding to carbon black B used in this embodiment is not particularly limited, but is preferably 70% or more from the viewpoint of further improving abrasion resistance.

[0028] In the rubber composition of the present embodiment, the ratio of the content of carbon black A in the total content of carbon black A and carbon black B is preferably 30% by mass or more and 70% by mass or less. When the ratio is 30% by mass or more, the abrasion resistance can be further improved. Furthermore, when the ratio is 70% by mass or less, the deterioration of the low heat buildup property can be more effectively suppressed. From the same viewpoint, as well as from the viewpoint of improving the reinforcing property and dispersibility of the polymer and carbon black, the ratio of the content of carbon black A in the total content of carbon black A and carbon black B is more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 55% by mass or more, and more preferably 60% by mass or less.

[0029] Furthermore, the rubber composition of the present embodiment may or may not contain carbon black other than the above-mentioned carbon black A and carbon black B, i.e., carbon black C (the content may be 0). Carbon black C is, for example, 2 / g carbon black with a nitrogen adsorption specific surface area of ​​90m 2 / g, and the nitrogen adsorption specific surface area is 125m 2 / g or more 200m 2 / g or less but has a toluene coloring transmittance of less than 80%.

[0030] When the rubber composition of the present embodiment contains carbon black C, the content of carbon black C must be the smallest among carbon blacks A to C. In other words, when the rubber composition of the present embodiment contains carbon black C, the content of carbon black C must be less than the content of carbon black A and less than the content of carbon black B. This is to ensure the effect of using carbon black A and carbon black B in combination. From the same viewpoint, it is preferable that the rubber composition of the present embodiment does not contain carbon black C (i.e., the carbon black consists only of carbon black A and carbon black B).

[0031] In the rubber composition of this embodiment, the carbon black content (i.e., the total content of carbon black A, carbon black B, and optional carbon black C) is 40 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component. If the content is less than 40 parts by mass, the effect of using carbon black A and carbon black B in combination is not fully exhibited, and low heat build-up properties and abrasion resistance cannot be improved in a balanced manner. If the content exceeds 100 parts by mass, low heat build-up properties deteriorate. In addition, from the viewpoint of improving low heat build-up properties and abrasion resistance in a more balanced manner, the carbon black content in the rubber composition of this embodiment is preferably 50 parts by mass or more and 65 parts by mass or less.

[0032] (Other Ingredients) In addition to the above, the rubber composition of the present embodiment may appropriately contain various compounding agents such as fillers other than carbon black, vulcanizing agents such as sulfur, vulcanization aids such as stearic acid, vulcanization accelerators, vulcanization accelerator aids such as zinc oxide, antioxidants, softeners, plasticizers, processability improvers, etc. However, from the viewpoint of improving low heat generation and abrasion resistance in a well-balanced manner, the content of the softener and plasticizer is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and further preferably substantially none is contained.

[0033] The method for preparing the rubber composition of the present embodiment is not particularly limited, and for example, the rubber composition of the present embodiment can be obtained by blending and kneading the above-mentioned rubber component and each component including carbon black according to a conventional method. In blending and kneading, all the components may be blended and kneaded at once, or each component may be blended and kneaded in multiple stages such as two or three stages. In addition, a kneading machine such as a roll, an internal mixer, or a Banbury rotor can be used for kneading. In addition, the rubber composition of the present embodiment can be made into a crosslinked product (vulcanized product).

[0034] <Tires> A tire according to one embodiment of the present invention (hereinafter, sometimes referred to as "the tire according to the present embodiment") is characterized by using the above-mentioned rubber composition. In other words, the tire according to the present embodiment is characterized by comprising the above-mentioned rubber composition. Since the tire according to the present embodiment comprises the above-mentioned rubber composition, it has excellent low heat build-up properties and wear resistance.

[0035] In one embodiment, a tire includes a tread, a base tread, a sidewall, a side reinforcing rubber, a bead filler, etc. The above-mentioned rubber composition can be used in at least any of the above-mentioned tire parts, and is preferably used in the tread, which is particularly required to have both low heat build-up and abrasion resistance.

[0036] Since the tire of the present embodiment has excellent low heat generation properties and wear resistance as described above, it can be preferably used as a pneumatic tire, in particular a heavy-duty tire, a tire for a small truck, and the like.

[0037] The tire of the present embodiment is not particularly limited except for using the above-mentioned rubber composition, and can be manufactured according to a conventional method. As the gas to be filled in the tire of the present embodiment, in addition to normal air or air with an adjusted oxygen partial pressure, an inert gas such as nitrogen, argon, or helium can be used. EXAMPLES

[0038] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0039] (Preparation of Rubber Composition) According to the compounding recipe shown in Table 1, a rubber composition was prepared by performing a primary kneading (non-professional kneading, NR) and then a secondary kneading (professional kneading, P). The rubber composition was vulcanized at 145°C for 33 minutes, and the low heat generation property of the obtained vulcanized rubber composition sample was evaluated according to the following procedure. In addition, the prepared rubber composition was used to evaluate the abrasion resistance according to the following procedure.

[0040] <Low heat generation> For samples of the vulcanized rubber composition, tan δ was measured at 50° C. with a frequency of 15 Hz and a strain of 1% using a viscoelasticity measuring device (manufactured by GABO). The measured value of tan δ in Comparative Example 4 was set to 100, and the measured values ​​of tan δ in each example were indexed. The results are shown in Table 1. The smaller the index value, the more excellent the low heat build-up property.

[0041] <Wear resistance> The prepared rubber composition is applied to the tread to prepare a test tire (size: 195 / 85R16) according to a conventional method. A vehicle equipped with the test tire is driven 10,000 km on a paved road surface, and the remaining groove depth is measured. The remaining groove depth measurement value in each example is indexed, with the remaining groove depth index value of Comparative Example 4 being set to 100. The results are shown in Table 1. A higher index value indicates better wear resistance.

[0042] [Table 1]

[0043] *1 Butadiene rubber: "UBEPOL BR150L" manufactured by Ube Industries, Ltd. *2 CB1: Cabot Corporation, "N234", N2SA=117m 2 / g, Toluene color transmittance: 80% or more *3 CB2: Asahi Carbon Co., Ltd., N2SA=139m 2 / g, Toluene color transmittance: 90% *4 CB3: Cabot Corporation, "Shaw Black S118", N2SA=144m 2 / g, Toluene color transmittance: 75% *5 Anti-aging agent: "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd., N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine *6 Vulcanization accelerator: Ouchi Shinko Chemical Industry Co., Ltd., "Noccela CZ-G", N-cyclohexyl-2-benzothiazolyl sulfenamide

[0044] From Table 1, it can be seen that the rubber compositions of the examples, which contain a rubber component containing a specified ratio of natural rubber and butadiene rubber, and specified amounts of carbon black A and carbon black B, have a well-balanced improvement in both low heat build-up and abrasion resistance compared to the rubber compositions of the comparative examples.

[0045] In addition, CB3 in Table 1 has a nitrogen adsorption specific surface area of ​​125 m 2 / g or more 200m 2 / g or less, the toluene coloring transmittance is less than 80%. Also, from Table 1, it can be seen that even if CB3 is used as one of the main raw materials, it does not contribute to a balanced improvement in low heat generation property and abrasion resistance. [Industrial Applicability]

[0046] According to the present invention, it is possible to provide a rubber composition having good low heat buildup properties and excellent abrasion resistance. Also, according to the present invention, it is possible to provide a tire having low heat buildup properties and excellent abrasion resistance.

Claims

1. A rubber composition containing a rubber component and carbon black, The rubber component contains natural rubber and butadiene rubber, and the proportion of the natural rubber is less than 80% by mass, The amount of the carbon black is 46 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rubber component, Here, the nitrogen adsorption specific surface area is 125 m ２ / g or more 200m ２ / g or less and a toluene coloring transmittance of 80% or more is defined as carbon black A, Nitrogen adsorption specific surface area is 90m ２ / g or more 124m ２ / g or less is designated as carbon black B, When the carbon black other than carbon black A and carbon black B is carbon black C, The rubber composition is characterized in that the carbon black contains at least the carbon black A and the carbon black B, and the content of the carbon black C is 0 or is the smallest among the carbon blacks A to C.

2. The rubber composition according to claim 1, wherein the amount of the carbon black is 65 parts by mass or less based on 100 parts by mass of the rubber component.

3. 3. The rubber composition according to claim 1, wherein a ratio of a content of the carbon black A to a total content of the carbon black A and the carbon black B is 30% by mass or more and 70% by mass or less.

4. A tire comprising the rubber composition according to any one of claims 1 to 3.

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