JP2017101208A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire capable of suppressing snow clogging without depending on a shape of a lateral groove while maintaining handling response performance on a dry road surface, so as to satisfy a demand for improving on-snow grip performance since suppressing snow clogging by only a shape of a lateral groove has a limit, and to solve such problems that since a shape of a lateral groove is restricted to a shape capable of suppressing snow clogging, flexibility of shape design is decreased and wear resistance or wet grip performance are sacrificed.SOLUTION: The tire has a tread constituted from a rubber composition for a tread containing 0.05 to 3.0 parts by mass of a fatty acid amide with respect to 100 parts by mass of a rubber component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire having a tread composed of a rubber composition for tread containing a predetermined amount of fatty acid amide.

  Conventionally, as a method of improving the grip performance on snow of a tire, by reducing the hardness (Hs) of the rubber composition for tread, the elastic modulus (modulus) at low temperature is lowered (low temperature characteristics are improved), and adhesive friction is reduced. There are known a method of improving, a method of obtaining a grip force by providing a deep lateral groove on the tread surface, compressing snow by the lateral groove, and traveling so as to grip the compressed snow.

  The snow gripped in the lateral groove is drained until the tire makes one round and the lateral groove comes into contact with the snow on the road surface again. Thereby, the lateral groove can exhibit the grip force repeatedly. However, if a “snow clog” occurs, which makes it impossible to remove snow, there is a problem that the lateral grooves cannot grip the snow, that is, the grip performance on the snow that is inherent cannot be exhibited. In order to solve this problem, an attempt has been made to suppress the occurrence of snow clogging by designing the lateral groove into a predetermined shape (for example, Patent Document 1).

JP 2014-80050 A

  When the hardness of the tread rubber composition is too low, there is a problem that handling response performance on a dry road surface is deteriorated. Moreover, there is a limit to the suppression of snow clogging only by the lateral groove shape, and further improvement of the grip performance on snow is demanded. In addition, since the shape of the lateral groove is constrained to a shape that can suppress snow clogging, the degree of freedom in shape design is reduced, and there is a problem that wear resistance, wet grip performance, and the like are sacrificed.

  An object of the present invention is to provide a tire that maintains handling response performance on a dry road surface and can suppress snow clogging without depending on the shape of a lateral groove.

  The present invention relates to a tire having a tread composed of a rubber composition for a tread containing 0.05 to 3.0 parts by mass of a fatty acid amide with respect to 100 parts by mass of a rubber component.

  A lateral groove extending in a direction inclined with respect to the tire circumferential direction is provided on the tread surface, the lateral groove has a groove wall A and a groove wall B on the other side, and an angle θa of the groove wall A with respect to the tire radial direction is 5 to 40 It is preferable that the angle θb of the groove wall B with respect to the tire radial direction is 5 to 40 °.

  According to the tire having a tread composed of the rubber composition for a tread containing the predetermined amount of fatty acid amide according to the present invention, a tire in which snow clogging is suppressed without depending on the shape of the lateral groove can be provided.

It is the schematic which shows the grounding part of the tire which concerns on one Embodiment of this invention.

  The tire of the present invention has a tread composed of a rubber composition for a tread containing a predetermined amount of fatty acid amide with respect to a rubber component.

  It does not specifically limit as said rubber component, It can be set as the rubber component currently used for the rubber composition for tread of a tire. For example, at least one diene rubber component selected from the group consisting of natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR) and styrene butadiene rubber (SBR) can be used. Among them, it is preferable to contain NR and BR for the reason of excellent low-temperature characteristics, and it is preferable to contain SBR for the reason of excellent grip performance and wear resistance, and a rubber using NR, BR and SBR in combination. The component is more preferable, and a rubber component consisting only of NR, BR and SBR is more preferable.

  The NR is not particularly limited, and those commonly used in the tire industry can be used. Examples thereof include SIR20, RSS # 3, and TSR20. Further, as the IR, those generally used in the tire industry can be used.

  The content when NR and / or IR is contained in the rubber component is preferably 10% by mass or more, and more preferably 20% by mass or more, from the viewpoint of excellent rubber kneading processability and extrusion processability. Further, the content of NR and / or IR is preferably 80% by mass or less, and more preferably 70% by mass or less from the viewpoint of excellent low-temperature characteristics.

  The SBR is not particularly limited, and unmodified solution polymerization SBR (S-SBR), unmodified emulsion polymerization SBR (E-SBR), and these modified SBRs (modified S-SBR, modified E-SBR), and the like Is mentioned. Examples of the modified SBR include modified SBR having a terminal and / or main chain modified, modified SBR coupled with tin, a silicon compound, or the like (condensate, one having a branched structure, or the like). Among these SBRs, S-SBR and modified S-SBR are preferable because the grip performance and wear resistance can be improved in a balanced manner.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more from the viewpoint of grip performance and rubber strength. Further, the styrene content of SBR is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less from the viewpoint of low fuel consumption. In addition, the styrene content of SBR in the present specification is a value calculated by ¹ H-NMR measurement.

The vinyl bond amount of SBR is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more from the viewpoints of dry grip performance, wet grip performance and rubber strength. Further, the vinyl bond amount of SBR is preferably 65 mol% or less, more preferably 60 mol% or less from the viewpoint of low fuel consumption. In addition, the vinyl bond amount of SBR in this specification shows the vinyl bond amount of a butadiene part, and is a value computed by < ¹ > H-NMR measurement.

  The content when SBR is contained in the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more from the viewpoint of grip performance. Moreover, 90 mass% or less is preferable from a wear-resistant viewpoint, and, as for content of SBR, 80 mass% or less is more preferable.

  As the BR, various BR such as high-cis 1,4-polybutadiene rubber (high-cis BR), butadiene rubber containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), modified butadiene rubber (modified BR), and the like are used. Can do.

  The high cis BR is a butadiene rubber having a cis 1,4 bond content of 90% by weight or more. Examples of such high-sis BR include BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., and BR150B. By containing the high cis BR, low temperature characteristics and wear resistance can be improved.

  Examples of the SPB-containing BR include those in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR but are dispersed after being chemically bonded to BR. Examples of such SPB-containing BR include VCR-303, VCR-412 and VCR-617 manufactured by Ube Industries.

  The modified BR is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further the terminal of the modified BR molecule is bonded with a tin-carbon bond. Is mentioned. Examples of such modified BR include BR1250H (tin modified) manufactured by Nippon Zeon Co., Ltd., S modified polymer (modified for silica) manufactured by Sumitomo Chemical Co., Ltd., and the like.

  Among these various BRs, it is preferable to use a high cis BR from the viewpoint of excellent low-temperature characteristics and wear resistance.

  In the case where BR is contained in the rubber component, the content is preferably 20% by mass or more, and more preferably 30% by mass or more, from the viewpoint of low temperature characteristics and wear resistance. Moreover, 90 mass% or less is preferable from the point of preventing the deterioration of the workability of rubber | gum, and, as for content of the said various BR, 80 mass% or less is more preferable.

  Examples of the diene rubber component include acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM) in addition to the NR, IR, BR and SBR. From these, one or more can be selected and used in combination with at least one selected from the group consisting of NR, BR and SBR. However, these rubber components have low temperature characteristics. It is preferable not to include it for the reason that it falls significantly.

  In addition to the diene rubber component, the rubber component contains a rubber component such as butyl rubber (IIR), halogenated butyl rubber (X-IIR), and a halide of a copolymer of isomonoolefin and paraalkylstyrene. However, it is preferable not to include these rubber components because the low-temperature characteristics are greatly lowered.

  The fatty acid amide (fatty acid amide) is a compound having a fatty acid group and an amide group, and when contained in the rubber composition, it bleeds to the surface and exhibits a surface modification effect. Among these, by containing a fatty acid amide that forms a water-repellent surface film, a rubber composition for a tread having excellent snow discharge properties can be obtained.

  Examples of such fatty acid amides include monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, and erucic acid amide; N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid Substituted amides such as amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide; methylene bis stearic acid amide, ethylene bis stearic acid amide, ethylene bishydroxy acid amide, ethylene bisbehenic acid amide, hexamethylene bis stearic acid amide , Hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N, N′-distearyl adipic acid amide, N, N′-distearyl sebashi Bisamides such as acid amides; Aromatic bisamides such as m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N, N′-cysteallyl isophthalic acid amide; Methylol amides such as methylol stearic acid amide Fatty acid ester amides such as stearoamidoethyl stearate;

  Among these, it is preferable to use monoamide, substituted amide, methylol amide, or bisamide because a water-repellent surface film can be formed by blooming and snow clogging can be more effectively suppressed. From the viewpoint of dispersibility and film formation, it is more preferable to use monoamide or substituted amide.

  Content with respect to 100 mass parts of rubber components of fatty acid amide is 0.05 mass part or more, and 0.10 mass part or more is preferable. When the amount is less than 0.05 parts by mass, the effect of containing the fatty acid amide tends to be insufficient. Moreover, content of fatty acid amide is 3.0 mass parts or less, and 1.0 mass part or less is preferable. When it exceeds 3.0 parts by mass, the rubber hardness becomes too low, and the handling response performance on the dry road surface tends to be lowered.

  The rubber composition for a tread according to the present invention is a compounding agent or additive conventionally used in the tire industry, for example, various reinforcing fillers, coupling agents, zinc oxide, various oils, in addition to the rubber component and the fatty acid amide. , Softeners, waxes, various anti-aging agents, vulcanizing agents such as stearic acid and sulfur, various vulcanization accelerators and the like can be appropriately contained as necessary.

  The various reinforcing fillers can be arbitrarily selected from those conventionally used in tire rubber compositions, but carbon black and silica are mainly preferred.

  Examples of carbon black include furnace black, acetylene black, thermal black, channel black, graphite, and the like. These carbon blacks may be used alone or in combination of two or more. Among these, furnace black is preferable because it can improve the low temperature characteristics and wear performance in a well-balanced manner.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 m ² / g or more, more preferably 90 m ² / g or more, from the viewpoint that sufficient reinforcement and wear resistance can be obtained. Also, N ₂ SA of carbon black is excellent in dispersibility, from the viewpoint that it is difficult to heat generation, preferably 300 meters ² / g or less, more preferably 250m ² / g. In this specification, N ₂ SA of carbon black is measured according to JIS K 6217-2 “Basic characteristics of carbon black for rubber—Part 2: Determination of specific surface area—Nitrogen adsorption method—Single point method” Value.

  When the carbon black is contained, the content with respect to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more. When the amount is less than 5 parts by mass, sufficient reinforcing properties tend not to be obtained. The carbon black content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and still more preferably 60 parts by mass or less. When it exceeds 200 mass parts, there exists a tendency for workability to deteriorate, the tendency to generate | occur | produce heat easily, and a tendency for abrasion resistance to fall.

  The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid), and the like, but wet process silica is preferable because of its large number of silanol groups.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 80 m ² / g or more, more preferably 100 m ² / g or more, from the viewpoint of durability and elongation at break. The N ₂ SA of the silica, from the viewpoint of fuel economy and workability, preferably 250 meters ² / g or less, more preferably 220 m ² / g. In this specification, N ₂ SA of silica is a value measured according to ASTM D3037-93.

  The content with respect to 100 parts by mass of the rubber component in the case of containing silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more from the viewpoint of durability and elongation at break. Further, the content of silica is 200 parts by mass from the viewpoint of improving dispersibility at the time of kneading, and suppressing reduction of workability due to re-aggregation of silica during heating during rolling and storage after rolling. The following is preferable, and 150 parts by mass or less is more preferable.

  When silica is contained, it is preferable to use a silane coupling agent in combination. As the silane coupling agent, any silane coupling agent conventionally used in combination with silica can be used in the rubber industry. For example, Si75, Si266 (bis (3-triethoxysilyl) manufactured by Evonik Degussa Co., Ltd. Propyl) disulfide), sulfides such as Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by the same company, 3-mercaptopropyltrimethoxysilane, NXT-Z100, NXT-Z45, NXT manufactured by Momentive, etc. Mercapto-based (silane coupling agent having a mercapto group), vinyl-based such as vinyltriethoxysilane, amino-based such as 3-aminopropyltriethoxysilane, glycidoxy-based such as γ-glycidoxypropyltriethoxysilane, 3- Nitropropi Nitro-based, such as trimethoxysilane, 3-chloropropyl-chloro system such as trimethoxysilane. These may be used alone or in combination of two or more. Of these, sulfide type and mercapto type are preferable from the viewpoints of strong bonding strength with silica and excellent low heat build-up.

  In the case of containing a silane coupling agent, the content with respect to 100 parts by mass of silica is preferably 2 parts by mass or more, and more preferably 3 parts by mass or more. When content of a silane coupling agent is less than 2 mass parts, there exists a tendency for the silica dispersibility improvement effect not to be fully acquired. Further, the content of the silane coupling agent is preferably 25 parts by mass or less, and more preferably 20 parts by mass or less. When content of a silane coupling agent exceeds 25 mass parts, there exists a tendency for the effect corresponding to cost not to be acquired.

  The pneumatic tire of the present invention can be produced by a normal method using the tread rubber composition. That is, if necessary, the rubber composition for a tread in which the compounding agent and the additive are blended is extruded in accordance with the shape of the tire tread at an unvulcanized stage, and another tire member is formed on a tire molding machine. The unvulcanized tire is formed by pasting together and molding by a normal method. The pneumatic tire of the present invention can be obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

  The tire of the present invention is preferably a tire having a lateral groove extending in a direction inclined with respect to the tire circumferential direction on the tread surface from the viewpoint that the effects of the present invention can be more effectively exhibited. The lateral groove includes a groove called a lug groove or a lug pattern, and transmits braking force or driving force by the tire to the ground contact surface. In particular, in winter tires such as studless tires, snow is compressed by the lateral grooves, and a grip force on snow is generated by running so as to grip the compressed snow.

  However, when snow clogging occurs and the snow drainage function of the lateral grooves is lost, the gripping force on the snow is reduced, and the original function of the tire cannot be exhibited. In view of this, solutions have been implemented by making the shape of the lateral grooves easy to remove snow. However, with this method alone, the shape of the lateral groove needs to be specialized for the snow removal function, and snow drainage performance is sacrificed at the expense of dry grip, wet grip, durability, etc. obtained by the lateral groove. There is a need to improve. On the other hand, in the tire of the present invention, the snow drainage performance can be improved by surface modification with the fatty acid amide regardless of the shape of the lateral groove, so that the grip strength and durability are not sacrificed.

  When the tire of the present invention has a lateral groove on the tread surface, the shape of the lateral groove is not particularly limited, and a conventionally used lateral groove pattern can be appropriately designed according to the performance required for the tire.

  A lateral groove of a tire according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of a ground contact portion of a tire T having a lateral groove in a cross section parallel to the tire rotation direction R and perpendicular to the road surface E. Moreover, the enlarged view of the horizontal groove which is earth | grounding is shown. The transverse groove has a groove wall A and a groove wall B on the other side as shown in FIG. Here, the groove wall A is a side to be grounded after the groove wall B, and the other groove wall B is a side to be grounded first.

  In the lateral groove, the angle θa of the groove wall A with respect to the tire radial direction is 5 to 40 °, and the angle θb of the groove wall B with respect to the tire radial direction is 5 to 40 °. This is preferable because it is excellent in traction. Further, since traction is applied to A, the angle θa is preferably smaller than the angle θb.

  The tire of the present invention is a tire that can maintain snow handling response performance on a dry road surface and can suppress snow clogging without depending on the shape of a lateral groove, and is therefore suitably used as a winter tire such as a studless tire. . Moreover, it is used suitably as a tire for passenger cars.

  The present invention will be described based on examples, but the present invention is not limited to the examples.

Hereinafter, various chemicals used in Examples and Comparative Examples are shown together.
NR: TSR20
SBR: HPR355 manufactured by JSR Corporation (modified S-SBR, styrene content: 28% by mass, vinyl bond content: 56 mol%, coupled with alkoxysilane, introduced at the end)
BR: BR150B manufactured by Ube Industries, Ltd. (High cis BR, cis 1,4 bond content: 97% by mass)
Carbon black: Seast N220 manufactured by Mitsubishi Chemical Corporation (N ₂ SA: 114 m ² / g)
Silica: ULTRASIL VN3 (N ₂ SA: 175 m ² / g) manufactured by Evonik Degussa
Silane coupling agent: Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa
Zinc oxide: Zinc Hana No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Stearic acid “Kashiwa” manufactured by NOF Corporation
Aroma oil: X-140 manufactured by Japan Energy Co., Ltd.
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (6PPD)) manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. 1: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide (TBBS)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Noxeller D (1,3-diphenylguanidine, DPG) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Fatty acid amide 1: Amide AP-1 (stearic acid amide) manufactured by Nippon Kasei Co., Ltd.
Fatty acid amide 2: Diamond O-200 (oleic acid amide) manufactured by Nippon Kasei Co., Ltd.
Fatty acid amide 3: Diamond L-200 (erucic acid amide) manufactured by Nippon Kasei Co., Ltd.
Fatty acid amide 4: Nikka Amide S (N-stearyl stearate amide) manufactured by Nippon Kasei Co., Ltd.
Fatty acid amide 5: Nikka Amide OP (N-oleyl palmitic acid amide) manufactured by Nippon Kasei Co., Ltd.

Examples and Comparative Examples According to the formulation shown in Table 1, using a 1.7 L closed Banbury mixer, kneading chemicals other than sulfur and vulcanization accelerator for 3 to 5 minutes until reaching 150 ° C., mixing A kneaded paste was obtained. Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 2 minutes at 70 ° C. to obtain an unvulcanized rubber composition. Furthermore, the obtained unvulcanized rubber composition was press vulcanized for 12 minutes under the condition of 170 ° C. to obtain a rubber composition for each test.

  Further, the unvulcanized rubber composition is extruded into a tire tread shape by an extruder equipped with a predetermined-shaped die, and is bonded together with other tire members to form an unvulcanized tire. A test tire (size: 195 / 65R15, studless tire) was produced by press vulcanization for 12 minutes.

<Rubber hardness (Hs)>
In accordance with JIS K6253, using a durometer type A, the Shore hardness (Hs) at a temperature of 23 ° C. of each rubber composition for test was measured.

<Viscoelasticity test>
Loss tangent (tan δ) and complex elasticity of each rubber composition for testing under the conditions of 30 ° C., initial strain 10%, dynamic strain 2%, frequency 10 Hz, using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. The rate (E *) was measured. A result is shown with the index | exponent which sets the result of the comparative example 1 to 100 with the following formula. The higher the low exothermic index, the smaller the heat generation, and the better the low exothermic property, and the higher the complex elastic index, the harder and the better the durability.
(Tan δ index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100
(E * index) = (E * of Comparative Example 1) / (E * of each formulation) × 100

<Abrasion resistance test>
Each test tire was mounted on all wheels of a test vehicle (domestic FR vehicle, displacement: 2000 cc), and the test track was driven on the actual vehicle, and the reduction in pattern groove depth after running about 20000 km was measured. A result is shown with the index | exponent which sets the result of the comparative example 1 to 100 with the following formula. The larger the wear resistance index, the better the wear resistance.
(Abrasion resistance index) = (Reduction amount of Comparative Example 1) / (Reduction amount of each formulation) × 100

<Snow performance and snow clogging>
Each test tire was mounted on all wheels of a test vehicle (domestic FR vehicle, displacement: 2000 cc), and the vehicle was run on snow and the performance on snow was evaluated according to the following criteria. In addition, snow clogging in the lateral grooves of each test tire after running was visually observed and evaluated according to the following criteria. The test was conducted at the Hokkaido Nayoro Test Course of Sumitomo Rubber Industries, Ltd., and the temperature on ice and snow was -1 to -6 ° C, and the temperature on snow was -2 to -10 ° C.
Evaluation criteria on snow ○: Good △: Normal ×: Evaluation criteria for inferior snow clogs ○: Almost no clogging △: Snow clogging occurs in 5-30% of grooves ×: Snow clogging occurs in more than 30% of grooves

<Handling response performance on dry road>
A test vehicle equipped with each test tire was run on a dry road surface, and the responsiveness when the steering wheel was turned was evaluated by sensory evaluation of the test driver. Evaluation was performed according to the following criteria.
○: Responds normally ×: Slow response

  From the results of Table 2, by using a tire having a tread composed of a rubber composition for a tread containing a fatty acid amide, handling response performance on a dry road surface is maintained, and snow clogging can be achieved without depending on the shape of a lateral groove. It turns out that the tire which can be suppressed is obtained.

T tire R tire rotation direction E road surface G transverse groove A, B groove wall θa, θb groove wall angle

Claims (2)

The tire which has a tread comprised with the rubber composition for treads containing 0.05-3.0 mass parts fatty acid amide with respect to 100 mass parts of rubber components. The tread surface has a lateral groove extending in a direction inclined with respect to the tire circumferential direction,
The lateral groove has a groove wall A and a groove wall B on the other side;
The angle θa of the groove wall A with respect to the tire radial direction is 5 to 40 °,
The tire according to claim 1, wherein an angle θb of the groove wall B with respect to the tire radial direction is 5 to 40 °.

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