JP2023025131A - Tire rubber composition and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire rubber composition, which is a rubber composition containing silica, the composition having excellent fuel economy and fracture strength and also satisfying both of moldability (ensured molding time) and a vulcanization rate (shortened vulcanization time), and a tire having a tire member composed of the rubber composition.

SOLUTION: A tire rubber composition contains, based on 100 pts.mass of a rubber component containing styrene-butadiene rubber 50 mass% or more, silica 80 pts.mass or more, a plasticizer 30 pts.mass or more, and aminoguanidine weak acid salt.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a tire rubber composition and a tire having a tire member composed of the tire rubber composition.

In recent years, the characteristics required for automobile tires have become diverse, and among them, the demand for low fuel consumption has been increasing for the purpose of saving fuel consumption of automobiles in accordance with the social demand for energy saving.

Techniques for compounding silica or the like into rubber compositions for tires are known to improve fuel efficiency, but the compounding of silica causes problems such as a decrease in vulcanization speed (delayed vulcanization) and deterioration of silica dispersibility. occurs.

In order to suppress vulcanization delay, it is known to add a predetermined amine addition salt or the like (Patent Document 1).

Japanese Patent Application Laid-Open No. 2001-139727

However, the addition of an amine addition salt or the like in Patent Document 1 has a problem that the scorch time is shortened and the moldability is deteriorated.

The present invention relates to a rubber composition containing silica, which is excellent in fuel efficiency and breaking strength, and has both molding processability (ensuring molding time) and vulcanization speed (shortening vulcanization time). An object of the present invention is to provide a product, and to provide a tire having a tire member made of this rubber composition.

As a result of intensive studies, the present inventors have found that a rubber composition containing at least predetermined amounts of silica and a plasticizer with respect to a rubber component containing at least 50% by mass of styrene-butadiene rubber further contains an aminoguanidine weak acid salt, The inventors have found that the above problems can be solved, and have completed the present invention through further studies.

That is, the present invention
[1] With respect to 100 parts by mass of a rubber component containing 50% by mass or more of styrene-butadiene rubber,
80 parts by mass or more of silica,
30 parts by mass or more of a plasticizer, and
A rubber composition for tires comprising an aminoguanidine weak acid salt,
[2] The rubber composition for tires according to [1] above, wherein the aminoguanidine weak acid salt is at least one selected from the group consisting of aminoguanidine bicarbonate and aminoguanidine phosphate;
[3] The rubber composition for tires according to [1] or [2] above, wherein the content of the aminoguanidine weak acid salt is 0.01 to 10 parts by mass;
[4] Any one of the above [1] to [3], wherein the plasticizer contains a resin and an oil, and the resin content is 5 parts by mass or more and the oil content is 5 parts by mass or more. The rubber composition for tires according to
[5] The rubber composition for tires according to any one of [1] to [4] above, wherein the rubber component further contains at least one selected from the group consisting of natural rubber and butadiene rubber;
[6] A tire having a tire member composed of the tire rubber composition according to any one of [1] to [5] above,
Regarding.

According to the present invention, to provide a rubber composition for tires which is excellent in fuel efficiency and breaking strength, and which is compatible with molding processability (securing molding time) and vulcanization speed (shortening vulcanization time). Also, a tire having a tire member made of this rubber composition can be provided.

One of the present embodiments is a tire rubber comprising 80 parts by mass or more of silica, 30 parts by mass or more of a plasticizer, and aminoguanidine weak acid salt with respect to 100 parts by mass of a rubber component containing 50% by mass or more of styrene-butadiene rubber. composition.

Another embodiment of the present invention is a tire having a tire member composed of the rubber composition for a tire.

Although not intending to be bound by theory, the following can be considered as a mechanism by which a predetermined effect is obtained in this embodiment. That is, silica can improve fuel economy and breaking strength, but on the other hand, its silanol groups adsorb vulcanization accelerators, so the vulcanization time tends to be too long. However, the addition of aminoguanidine weak acid salts (carbonates, phosphates) suppresses the increase in vulcanization time even when a large amount of silica is blended, resulting in fuel efficiency, breaking strength, and moldability. (securing molding time) and vulcanization speed (reduction of vulcanization time) are considered to improve in a well-balanced manner. In addition, due to its strong polarity, aminoguanidine not only assists the dispersion of silica, but also assists the hydrolysis reaction of the coupling agent, resulting in high reactivity between silica and polymer. It is presumed that improved dispersibility of silica is achieved and low fuel consumption is realized. Furthermore, when the rubber component contains rubber other than styrene-butadiene rubber, such as natural rubber and butadiene rubber, the improvement of reactivity between silica and polymer by aminoguanidine can reinforce the interface between styrene-butadiene rubber and other rubbers. It is also connected to the strength, so it is thought that the strength will be further improved.

<Rubber component>
In this embodiment, the rubber component contains 50% by mass or more of styrene-butadiene rubber (SBR). The rubber other than SBR constituting the rubber component is not particularly limited, and any one conventionally used in the tire industry can be suitably used. Examples of rubber components include isoprene rubber including natural rubber (NR) and polyisoprene rubber (IR), butadiene rubber (BR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR ), acrylonitrile butadiene rubber (NBR), and halogenated rubbers including butyl rubber (IIR), brominated butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR) and fluorinated butyl rubber (F-IIR). Butyl-based rubber such as butyl rubber can be mentioned. These rubber components may be used singly or in combination of two or more as long as they contain 50% by mass or more of SBR. Among them, it is preferable to contain at least one of NR and BR in addition to SBR for the reason that the effects of the present embodiment can be more effectively exhibited, or NR and BR in addition to SBR. It is preferable to include only at least one.

(Styrene-butadiene rubber)
The SBR is not particularly limited, and examples include unmodified emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), modified emulsion-polymerized styrene-butadiene rubber (modified E-SBR ) and modified SBR such as modified solution-polymerized styrene-butadiene rubber (modified S-SBR). Examples of the modified SBR include modified SBR whose terminal and/or main chain is modified, and modified SBR (condensate, branched structure, etc.) coupled with tin, a silicon compound, or the like. As SBR, there are an oil-extended type in which flexibility is adjusted by adding extender oil and a non-oil-extended type in which extender oil is not added, and both of these types can be used. For example, those manufactured by JSR Corporation, those manufactured by Asahi Kasei Chemicals Corporation, those manufactured by Nippon Zeon Co., Ltd., and the like can be used.

SBR preferably has a styrene content of 15.0% to 40.0% by mass. From the viewpoint of rubber strength and grip performance, the styrene content is preferably 20.0% by mass or more, more preferably 25.0% by mass or more, still more preferably 30.0% by mass or more, and further preferably 35.0% by mass or more. preferable. Moreover, the styrene content of SBR is preferably 39.0% by mass or less from the viewpoint of fuel efficiency. The styrene content of SBR is a value calculated by ¹ H-NMR measurement.

The vinyl content (1,2-bonded butadiene unit amount) of SBR is preferably 10.0 to 30.0%. From the viewpoint of rubber strength and grip performance, the vinyl content is preferably 13.0% or more, more preferably 15.0% or more. Also, the vinyl content is preferably 25.0% or less, more preferably 20.0% or less, from the viewpoint of fuel efficiency. The vinyl content of SBR is a value measured by infrared absorption spectrometry.

The content of SBR in the rubber component is preferably within a more limited range, preferably 51% by mass or more, and preferably 52% by mass or more, for the reason that the effects of the present embodiment can be better exhibited. , is preferably 53% by mass or more, preferably 54% by mass or more, and more preferably 55% by mass or more. Furthermore, the SBR content may be 56% by mass or more, 57% by mass or more, 58% by mass or more, 59% by mass or more, or 60% by mass or more. % by mass or more. In addition, there is no particular upper limit for the content of SBR, and although it may be 100% by mass, it may be a predetermined value or less. 85% by mass or less is more preferable, 80% by mass or less is more preferable, 75% by mass or less is more preferable, and 70% by mass or less is even more preferable. When oil-extended SBR is used as SBR, the content of SBR itself as a solid content contained in the oil-extended SBR is defined as the content of SBR in the rubber component.

(natural rubber)
The NR is not particularly limited, and for example, those commonly used in the tire industry (unmodified NR) such as SIR20, RSS#3, and TSR20 can be used, as well as epoxidized natural rubber (ENR), hydrogenated Modified natural rubbers such as natural rubber (HNR), grafted natural rubber, deproteinized natural rubber (DPNR), highly purified natural rubber, and the like can also be used.

When NR is contained, the content in the rubber component is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 7% by mass or more, from the viewpoint of moldability, reinforcement, and fuel economy. Preferably, 10% by mass or more is more preferable. Moreover, from the viewpoint of fuel economy, the content is preferably 35% by mass or less, more preferably 30% by mass or less, more preferably 28% by mass or less, and even more preferably 25% by mass or less.

(butadiene rubber)
BR is not particularly limited, and any one commonly used in this field can be suitably used. For example, high-cis-1,4-polybutadiene rubber (high-cis BR), rare earth-based butadiene rubber synthesized using a rare earth-based catalyst (rare-earth-based BR), butadiene rubber containing 1,2-syndiotactic polybutadiene crystals (SPB Various BR such as BR (containing BR) and modified butadiene rubber (modified BR) can be used. As such BR, for example, those manufactured by Ube Industries, Ltd., those manufactured by Nippon Zeon, and those manufactured by Lanxess can be suitably used.

Hi-cis BR is a butadiene rubber having a cis-1,4 bond content of 90% by mass or more. Among them, the cis-1,4 bond content is preferably 95% by mass or more, more preferably 96% by mass or more, still more preferably 97% by mass or more, and 98% by mass or more. is more preferred. By containing high-cis BR, low-temperature properties and wear resistance can be improved. The cis-1,4 bond content in BR is a value calculated by infrared absorption spectroscopy.

The rare earth-based BR is synthesized using a rare-earth element-based catalyst and has a vinyl content (1,2-bonded butadiene unit amount) of 1.8% by mass or less, preferably 1.0% by mass or less, more preferably 0.8. % by mass or less and a cis content (cis-1,4 bond content) of 90 mass % or more, preferably 93 mass % or more, more preferably 95 mass % or more can be suitably used. When the vinyl content and the cis-1,4 bond content are within the above ranges, the resulting rubber composition has the effect of being excellent in elongation at break and abrasion resistance. The vinyl content and cis content of the rare earth BR are values measured by infrared absorption spectrometry.

As the rare earth element-based catalyst used in the synthesis of the rare earth-based BR, a known one can be used, for example, a lanthanum-series rare earth element compound, an organoaluminum compound, an aluminoxane, a halogen-containing compound, and a catalyst containing a Lewis base as necessary. is given.

SPB-containing BR includes not only 1,2-syndiotactic polybutadiene crystals dispersed in BR but also those in which BR is chemically bonded and dispersed. The complex elastic modulus tends to improve because the crystals are chemically bonded to the rubber component and then dispersed.

Examples of modified BR include modified BR whose terminal and/or main chain is modified, tin, modified BR coupled with a silicon compound (condensate, branched structure, etc.), functional group interacting with silica Modified BR whose terminal and/or main chain is modified with, particularly modified BR having at least one selected from the group consisting of silyl groups, amino groups, amido groups, hydroxyl groups, and epoxy groups. By using the modified BR, it is possible to obtain the effect of making the interaction with the filler stronger and improving the fuel efficiency.

When BR is contained, the content in the rubber component is preferably 1% by mass or more, more preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of abrasion resistance. . From the viewpoint of moldability, the BR content is preferably 35% by mass or less, more preferably 30% by mass or less, more preferably 28% by mass or less, and even more preferably 25% by mass or less.

<Silica>
The rubber composition for tires according to the present embodiment is characterized by containing silica as a filler. By containing silica, the effect of improving fuel efficiency can be suitably obtained, and high reinforcing properties can be obtained.

Silica is generally difficult to disperse in a rubber composition, but according to the rubber composition containing the aminoguanidine weak acid salt of the present embodiment, it can be dispersed well, and excellent rubber performance is balanced. It can be expressed well.

The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), and the like commonly used in the tire industry can be used. Among them, hydrous silica prepared by a wet method is preferable because it contains many silanol groups. Silica may be used individually by 1 type, and may be used in combination of 2 or more types.

The N ₂ SA of silica is preferably 70 m ² /g or more, more preferably 80 m ² /g or more, and even more preferably 90 m ² /g or more. The upper limit of N ₂ SA is not particularly limited, but from the viewpoint of ease of handling, for example, it is preferably 500 m ² /g or less, more preferably 400 m ² /g or less, and 300 m ² /g or less. It is more preferably 280 m ² /g or less, more preferably 250 m ² /g or less, even more preferably 230 m ² /g or less. By using silica having N ₂ SA within the above range, it is possible to improve fuel efficiency, molding processability, and the like in a well-balanced manner. The N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-81.

The content of silica with respect to 100 parts by mass of the rubber component is 80 parts by mass or more from the viewpoint of good performance of the present embodiment. The content of silica is preferably 81 parts by mass or more, more preferably 82 parts by mass or more, more preferably 83 parts by mass or more, more preferably 84 parts by mass, from the viewpoint of silica dispersibility, fuel efficiency, moldability, etc. It is at least 85 parts by mass, more preferably at least 85 parts by mass. Also, the content of silica is preferably 150 parts by mass or less, more preferably 140 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less.

<Other Fillers>
Other fillers than silica may be used as fillers. Such fillers are not particularly limited, and any filler commonly used in this field, such as carbon black, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, talc, clay, etc., can be used. be able to. These fillers may be used singly or in combination of two or more. When a filler other than silica is used, carbon black is preferable from the viewpoint of rubber strength. That is, the filler preferably contains silica and carbon black, or preferably consists of silica and carbon black only.

(Carbon black)
Carbon black is not particularly limited, and those commonly used in the tire industry, such as GPF, FEF, HAF, ISAF, and SAF, can be used.

The N ₂ SA of carbon black is preferably 50 m ² /g or more, more preferably 70 m ² /g or more, still more preferably 90 m ² /g or more, from the viewpoint of obtaining sufficient reinforcing properties and wear resistance. In addition, the N ₂ SA of carbon black is preferably 500 m ² /g or less, more preferably 450 m ² /g or less, even more preferably 300 m ² /g or less, and 250 m ² from the viewpoint of excellent dispersibility and low heat generation. /g or less is more preferable. The N ₂ SA of carbon black is a value measured according to JIS K 6217-2:2001.

The DBP oil absorption of carbon black is preferably 50 ml/100 g or more, more preferably 100 ml/100 g or more, from the viewpoint of abrasion resistance. From the viewpoint of grip performance, the DBP oil absorption of carbon black is preferably 250 ml/100 g or less, more preferably 200 ml/100 g or less, and more preferably 150 ml/100 g or less. The DBP oil absorption of carbon black is a value measured according to JIS K 6217-4:2008.

When carbon black is contained, the content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and 5 parts by mass or more, from the viewpoint of obtaining sufficient reinforcement and abrasion resistance. is more preferable, and 7 parts by mass or more is even more preferable. In addition, the content of carbon black is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, more preferably 20 parts by mass or less, from the viewpoint of moldability, fuel efficiency and wear resistance, and 15 parts by mass. More preferred are:

<Silane coupling agent>
Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and any silane coupling agent conventionally used in combination with silica in the rubber industry can be used. Examples of such silane coupling agents include bis(3-triethoxysilylpropyl) tetrasulfide, bis(2-triethoxysilylethyl) tetrasulfide, bis(4-triethoxysilylbutyl) tetrasulfide, bis( 3-trimethoxysilylpropyl) tetrasulfide, bis(2-trimethoxysilylethyl) tetrasulfide, bis(4-trimethoxysilylbutyl) tetrasulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(2- triethoxysilylethyl) trisulfide, bis(4-triethoxysilylbutyl) trisulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(2-trimethoxysilylethyl) trisulfide, bis(4-trimethoxy silylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, Bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N- Dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl Silane coupling agents having a sulfide group such as tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Momentive's NXT-Z100, NXT-Z45, silane coupling agents having a mercapto group such as NXT; vinyltriethoxysilane, vinyltrimethoxysilane, etc. silane coupling agent having a vinyl group of; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, Silane coupling agents having an amino group such as 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane; γ-glycidoxypropyltriethoxysilane, γ- Glycidoxy-based silane coupling agents such as glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane; 3-nitropropyltrimethoxysilane, 3-nitropropyl Nitro-based silane coupling agents such as triethoxysilane; Chloro-based silanes such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane coupling agent; These silane coupling agents may be used singly or in combination of two or more. Among them, sulfide-based and mercapto-based are preferable because they have a strong binding force with silica and are excellent in fuel efficiency. In addition, the use of mercapto-based resins is preferable from the viewpoint that fuel efficiency and wear resistance can be favorably improved.

When the silane coupling agent is contained, the content relative to 100 parts by mass of silica is more preferably 1.0 parts by mass or more, since effects such as sufficient silica dispersibility and viscosity reduction can be obtained, and 2.0 parts by mass. It is more preferably at least 4.0 parts by mass, even more preferably at least 6.0 parts by mass. In addition, the content of the silane coupling agent is preferably 20.0 parts by mass or less, and 18.0 parts by mass or less, for the reason of efficiently obtaining sufficient coupling effect and silica dispersion effect to ensure reinforcement. is more preferable, and 15.0 parts by mass or less is even more preferable.

<Aminoguanidine weak acid salt>
The rubber composition for tires according to the present embodiment is characterized by containing an aminoguanidine weak acid salt.

In the present embodiment, the aminoguanidine weak acid salt is a salt composed of aminoguanidine and a weak acid, and the guanidine moiety of aminoguanidine forms a salt with the weak acid. Aminoguanidine weak acid salt may be a salt consisting of one molecule of weak acid and one molecule of aminoguanidine, or may be a salt consisting of one molecule of weak acid and two molecules of aminoguanidine.

The aminoguanidine weak acid salt is not particularly limited as long as it can exhibit the effects of the present embodiment. The weak acid used in the aminoguanidine weak acid salt can be either an organic acid or an inorganic acid, but an inorganic acid is preferred. Specific examples of aminoguanidine weak acid salts include aminoguanidine bicarbonate (aminoguanidine bicarbonate) composed of aminoguanidine and carbonic acid, and aminoguanidine phosphate composed of aminoguanidine and phosphoric acid. Such aminoguanidine weak acid salts may be used singly or in combination of two or more. Among them, the effect of the present embodiment by containing aminoguanidine weak acid salt can be exhibited more satisfactorily, the fuel efficiency and breaking strength are excellent, and from the viewpoint of achieving both moldability and vulcanization speed, bicarbonate It preferably contains at least one selected from the group consisting of aminoguanidine and aminoguanidine phosphate. The weak acid of aminoguanidine is preferably aminoguanidine bicarbonate, preferably aminoguanidine phosphate, or preferably composed of aminoguanidine bicarbonate and aminoguanidine phosphate.

The aminoguanidine weak acid salt of the present embodiment can be obtained by a known method, for example, a method of mixing aminoguanidine bicarbonate and a weak acid. Commercially available aminoguanidine bicarbonate and weak acid can be used. For example, those manufactured by Tokyo Kasei Kogyo Co., Ltd. can be used.

The content of the aminoguanidine weak acid salt is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The content of the aminoguanidine weak acid salt is preferably 0.05 parts by mass or more, more preferably 0.10 parts by mass or more, more preferably 0.30 parts by mass or more, and even more preferably 0.50 parts by mass or more. In addition, the content of the aminoguanidine weak acid salt is preferably 9 parts by mass or less, more preferably 7 parts by mass or less, more preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and more preferably 2.5 parts by mass or less. Preferably, 2.0 parts by mass or less is more preferable. By setting it as such a range, the effect of this embodiment can be exhibited more satisfactorily.

<Plasticizer>
The rubber composition for tires according to the present embodiment preferably further contains a plasticizer.

The plasticizer is not particularly limited, and those commonly used in the rubber industry as plasticizers and softeners can be used. For example, they are known as resins, oils, liquid polymers, low-temperature plasticizers, and the like. including any A plasticizer may be used individually by 1 type, and may be used in combination of 2 or more type. Among these, resins, oils, and liquid polymers are preferred, resins and oils are more preferred, and resins and oils alone are more preferred, because the effects of the present embodiment can be exhibited more satisfactorily.

(resin)
The resin is not particularly limited, and any one commonly used in the rubber industry can be suitably used. Examples include styrene copolymer resins, adhesive resins, crosslinkable resins, compatibilizing resins, and the like.

The softening point of these resins is preferably in the range of −20 to 180° C. from the viewpoint of suitably exhibiting the function as a plasticizer. The upper limit of the softening point is preferably 170°C or lower, more preferably 150°C or lower, and even more preferably 130°C or lower. The lower limit of the softening point is preferably -10°C or higher, more preferably -5°C or higher. In this specification, the softening point of a resin is the temperature at which a ball descends when the softening point specified in JIS K 6220-1 is measured with a ring and ball type softening point measuring device.

The weight average molecular weight (Mw) of these resins is preferably within a predetermined range from the viewpoint of obtaining good moldability and ensuring rubber hardness. Specifically, Mw is preferably 120,000 or less, more preferably 10,000 or less, and even more preferably 5,000 or less. Moreover, Mw is preferably 200 or more, more preferably 250 or more, still more preferably 300 or more, and even more preferably 350 or more. In this specification, the Mw of the resin is a gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ- manufactured by Tosoh Corporation. M) is a value obtained by standard polystyrene conversion based on the measured value.

<<Styrene/α-methylstyrene copolymer resin>>
A styrene/α-methylstyrene copolymer resin is a resin obtained by polymerizing styrene and α-methylstyrene.

≪Hydrogenated terpene resin≫
A hydrogenated terpene-based resin is obtained by hydrogenating (hydrogenating) a terpene-based resin. The hydrogenation treatment to the terpene-based resin can be performed by a known method.

The hydrogenated terpene resin is not particularly limited, and for example, α-pinene, β-pinene, limonene, polyterpene resin composed of at least one selected from terpene raw materials such as dipentene, a terpene compound and an aromatic compound as raw materials and a terpene-based resin such as a terpene-phenol resin made from a terpene compound and a phenol-based compound, which are obtained by subjecting the terpene-based resin to a hydrogenation treatment. Here, examples of aromatic compounds used as raw materials for aromatic modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples include phenol, bisphenol A, cresol and xylenol.

≪Adhesive resin≫
The adhesive resin is usually an oligomer having a property of compatibility or at least semi-compatibility with the rubber component and having a molecular weight of several hundred to several ten thousands. By blending the adhesive resin, the adhesiveness (moldability) of the unvulcanized product during tire molding is improved. Here, the adhesive resin is not particularly limited, and any resins other than those mentioned above that are commonly used in the rubber industry can be suitably used. Resins, styrene resins, acrylic resins, rosin-based resins, dicyclopentadiene resins (DCPD resins), and the like. Examples of phenolic resins include those manufactured by BASF Corporation and Taoka Chemical Co., Ltd. Examples of coumarone-indene resins include those manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. and those manufactured by JXTG Energy Co., Ltd. As the styrene resin, for example, those manufactured by Arizona Chemical can be used. As the terpene-based resin, for example, those manufactured by Arizona Chemical Co., Ltd., or those manufactured by Yasuhara Chemical Co., Ltd. can be used. As the rosin-based resin, for example, those manufactured by Harima Kasei Co., Ltd. or those manufactured by Arakawa Chemical Industries, Ltd. can be used. Among them, phenolic resins, coumarone-indene resins, terpene-based resins, and acrylic resins are preferably used because of their excellent grip performance.

≪Liquid resin≫
As the resin, a liquid (liquid resin) can be preferably used from the viewpoint of exhibiting the effect as a plasticizer. Here, liquid resin refers to resin that is not cured at room temperature (25° C.).

As the liquid resin, for example, a liquid coumarone-indene resin, a liquid terpene resin, or the like can be suitably used. Among them, liquid coumarone-indene resin is preferred.

The liquid coumarone-indene resin contains coumarone and indene as monomer components constituting the skeleton (main chain) of the resin. In addition to coumarone and indene, monomer components contained in the skeleton include styrene, α-methylstyrene, methylindene, vinyltoluene, and the like. The softening point of the liquid coumarone-indene resin is preferably -20 to 45°C. The upper limit is preferably 40°C or lower, more preferably 35°C or lower. The lower limit is preferably -10°C or higher, more preferably -5°C or higher. As the liquid coumarone-indene resin, for example, those manufactured by Rutgers Chemicals can be preferably used.

(oil)
The oil is not particularly limited, and any one commonly used in the rubber industry can be suitably used. Examples thereof include process oil, vegetable oil, animal oil and the like. Examples of process oils include paraffinic process oils, naphthenic process oils, and aromatic process oils. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, sesame oil, olive oil, sunflower oil. oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, safflower oil, tung oil and the like. Animal fats and oils include oleyl alcohol, fish oil, and beef tallow. Among them, process oil is preferable because it is advantageous in processability, and process oil with a low polycyclic aromatic compound (PCA) content (low PCA content process oil) is preferred.

Low PCA content process oils include Treated Distillate Aromatic Extract (TDAE), which is obtained by re-extracting oil aromatic process oils, aromatic substitute oil which is a mixed oil of asphalt and naphthenic oil, and mild extraction solvates (MES). ), and heavy naphthenic oils.

(liquid polymer)
The liquid polymer is preferably a liquid polymer having a polystyrene equivalent weight average molecular weight of 1.0×10 ³ to 2.0×10 ⁵ as measured by gel permeation chromatography (GPC). By setting it in such a range, there is a tendency that fracture properties, durability, and moldability can be obtained in a well-balanced manner.

The liquid polymer is not particularly limited, and any polymer commonly used in the rubber industry can be suitably used. Examples thereof include liquid SBR, liquid BR, liquid IR, and liquid SIR. Among them, it is preferable to use liquid SBR because it can improve durability performance and grip performance in a well-balanced manner.

(low temperature plasticizer)
The low-temperature plasticizer is not particularly limited, and any one commonly used in the rubber industry can be suitably used. ), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate ( TCP), ester-based plasticizers such as trixylenyl phosphate (TXP), and the like. Among these, DOS and TOP are preferred from the viewpoint of the balance between the plasticizing effect and wear resistance at low temperatures, and DOS is preferred from the viewpoint of excellent fuel efficiency.

The freezing point of the low-temperature plasticizer is preferably −50° C. or lower, more preferably −70° C. or lower, from the viewpoint of sufficient grip improvement effect. Also, the lower limit of the freezing point of the low-temperature plasticizer is not particularly limited.

The viscosity of the low-temperature plasticizer at 25° C. is preferably 30 mPa·s or less, more preferably 20 mPa·s or less, from the viewpoint of a sufficient grip improving effect. Moreover, the lower limit of the viscosity of the low-temperature plasticizer is not particularly limited.

(Content)
The content of the plasticizer with respect to 100 parts by mass of the rubber component is 30 parts by mass or more. The content is preferably within a predetermined range that is further limited from the viewpoint of fuel efficiency and wear resistance. Such a range is preferably 35 parts by mass or more, and more preferably 40 parts by mass or more. Preferably, 45 parts by mass or more is more preferable. The content of the plasticizer is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less. In addition to the oil components contained in the oil-extended rubber and insoluble sulfur, the plasticizer content also includes post-add oil (an oil that is added separately from the oil components contained in the oil-extended rubber and insoluble sulfur). .

The resin content of the plasticizer is preferably 1 part by mass or more, more preferably 5 parts by mass or more, more preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more. The content of the resin is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, more preferably 45 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less.

Among the plasticizers, the content of oil is more preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and more preferably 20 parts by mass or more. The content of the oil is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, more preferably 35 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less.

<Other compounding agents>
In addition to the above components, the rubber composition according to the present embodiment contains compounding agents commonly used in the production of rubber compositions, such as zinc oxide, stearic acid, antioxidants, waxes, vulcanizing agents, A vulcanization accelerator or the like can be appropriately blended.

(Antiaging agent)
The anti-aging agent is not particularly limited, and any of those commonly used in the rubber industry can be suitably used. , phenol-based anti-aging agents, sulfur-based anti-aging agents, phosphorus-based anti-aging agents, and the like. Antiaging agents may be used singly or in combination of two or more.

The content of the anti-aging agent with respect to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more. Moreover, 7 mass parts or less are preferable, and, as for content of antiaging agent, 5 mass parts or less are more preferable. By setting it as such a range, the effect of this embodiment can be exhibited more satisfactorily.

(wax)
The wax is not particularly limited, and any one commonly used in the rubber industry can be suitably used. Examples thereof include paraffin waxes manufactured by Nippon Seiro Co., Ltd. and Paramelt. Waxes may be used singly or in combination of two or more.

When the wax is contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.2 parts by mass or more. Also, it is preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, and even more preferably 2.0 parts by mass or less. By setting it as such a range, the effect of this embodiment can be exhibited more satisfactorily.

(vulcanizing agent)
The vulcanizing agent is not particularly limited, and known vulcanizing agents can be used. Examples thereof include sulfur, organic peroxides, resin vulcanizing agents, and metal oxides such as magnesium oxide. Among them, it is preferable to use sulfur. Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur, all of which are preferably used. The vulcanizing agents may be used singly or in combination of two or more.

When sulfur is contained as a vulcanizing agent, the content relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more. In addition, the sulfur content is preferably 7 parts by mass or less, more preferably 5 parts by mass or less. By setting it as such a range, the effect of this embodiment can be exhibited more satisfactorily.

(Vulcanization accelerator)
The vulcanization accelerator is not particularly limited, and known vulcanization auxiliaries can be used. system, aldehyde-ammonia system, imidazoline system, or xanthate system vulcanization accelerators. Among these, sulfenamide-based and guanidine-based adhesives are preferred because the scorch time and vulcanization time can be well balanced. The vulcanization accelerator may be used singly or in combination of two or more.

Examples of sulfenamide-based vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N '-dicyclohexyl-2-benzothiazolylsulfenamide (DZ) and the like. Among them, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) is preferred.

Guanidine-based vulcanization accelerators include, for example, 1,3-diphenylguanidine (DPG), diorthotolylguanidine, orthotolylbiguanidine, and the like. Among them, 1,3-diphenylguanidine (DPG) is preferable from the viewpoint of shortening the vulcanization time.

In the present embodiment, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) and 1,3-diphenylguanidine ( DPG) alone is more preferred.

When the vulcanization accelerator is contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more. Also, the content of the vulcanization accelerator is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.5 parts by mass or less. By setting it as such a range, the effect of this embodiment can be exhibited more satisfactorily.

<Manufacture of tire rubber composition>
The tire rubber composition of the present embodiment is produced by a known method. For example, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll, or the like, and then vulcanizing. In the kneading, the components other than the vulcanizing agent and the vulcanization accelerator are first kneaded, and then the vulcanizing agent and the vulcanization accelerator are added to the resulting kneaded product and kneaded. The method of blending the aminoguanidine weak acid salt is also not particularly limited, and it can be blended as a powder as it is. It can also be blended by a method of blending as an emulsion solution or the like.

<Rubber composition for tires>
The tire rubber composition of the present embodiment can be used for each tire member such as a tread, undertread, carcass, sidewall and bead of a tire. In particular, a tire having a tread made of the rubber composition for tires of the present embodiment is preferable because of its excellent fuel efficiency, breaking strength and wear resistance.

<Tire manufacturing>
The tire of this embodiment can be manufactured by a normal method using the rubber composition for tires. That is, the tire rubber composition is extruded in an unvulcanized stage so as to match the shape of a tire member such as a tire tread, molded on a tire molding machine by a normal method, and pasted together with other tire members. Combine to form an unvulcanized tire. The tire of the present embodiment can be manufactured by heating and pressurizing this unvulcanized tire in a vulcanizer. The vulcanization temperature is not particularly limited as long as it is a general vulcanization temperature in the tire industry.

<Tire>
The tire of this embodiment may be a pneumatic tire or a non-pneumatic tire, but is preferably a pneumatic tire. Pneumatic tires can be used for various tires such as high-performance tires such as tires for passenger cars, tires for trucks and buses, tires for motorcycles, racing tires, and run-flat tires.

<Others>
In this specification, when a numerical range is expressed as "10 to 100", the numerical range includes values at both ends unless otherwise specified.

Although the present embodiment will be described based on examples, the present embodiment is not limited only to the examples.

Various chemicals used in Examples and Comparative Examples are listed below.
Natural rubber (NR): TSR20
Styrene-butadiene rubber (SBR): Asaprene E15 from Asahi Kasei Corporation
Butadiene rubber (BR): BR150B manufactured by Ube Industries, Ltd.
Silica: Ultrasil VN3 from Evonik (N ₂ SA (BET): 175 m ² /g)
Silane coupling agent (coupling agent): Evonik Si69 (bis (3-triethoxysilylpropyl) tetrasulfide)
Resin: SYLVATRAXX4401 manufactured by Arizona Chemical Co.
Oil: Diana process oil PA32 manufactured by Idemitsu Kosan Co., Ltd.
Antiaging agent: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd.
Zinc oxide stearate sulfur vulcanization accelerator 1: N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)
Vulcanization accelerator 2: 1,3-diphenylguanidine (DPG)
Aminoguanidine Weak Salt 1 (AG Weak Salt 1): Aminoguanidine Phosphate Aminoguanidine Weak Salt 2 (AG Weak Salt 2): Aminoguanidine Bicarbonate

Examples 1-3 and Comparative Examples 1-3
Various chemicals (excluding sulfur and vulcanization accelerators 1 and 2) among the compounding contents shown in Table 1 are kneaded in a Banbury mixer to obtain a kneaded product. Next, using an open roll, sulfur and vulcanization accelerators 1 and 2 are added to the resulting kneaded material and kneaded to obtain an unvulcanized rubber composition.

A vulcanized rubber composition is produced by molding the unvulcanized rubber composition into a desired shape and subjecting it to press vulcanization at 170°C. The vulcanization time is twice the vulcanization characteristic t90 at 170°C determined below.

The unvulcanized rubber composition is extruded using an extruder equipped with a tread-shaped die, bonded together with other tire members to form an unvulcanized tire, and press-vulcanized at 170°C. to manufacture test tires (size: 195/65R15).

<Moldability>
For the unvulcanized rubber composition, a vulcanization test was performed at a measurement temperature of 130 ° C. using a vibrating vulcanization tester (curastometer) described in JIS K 6300, and the time and torque were plotted. Obtain a sulfur velocity curve. When ML is the minimum value of the torque on the vulcanization speed curve, MH is the maximum value, and ME is the difference (MH-ML), the time t10 (scorch time) (minutes) to reach ML+0.1ME is read. Assuming that the scorch time of the standard comparative example is 100, the values are expressed as indices according to the following formula. The larger the value, the longer the scorch time and the better the moldability.
(Moldability index) =
{(scorch time of each formulation)/(scorch time of reference comparative example)}×100

<Vulcanization speed>
For the unvulcanized rubber composition, a vulcanization characteristic t90 at 170°C is obtained using a viscoelasticity measuring device (manufactured by Alpha Technologies, trade name: RPA2000), and the vulcanization time is taken as the vulcanization time. Assuming that the vulcanization time of the standard comparative example is 100, the values are expressed as indices according to the following formula. A larger value indicates a shorter vulcanization time.
(Vulcanization rate index) = {(vulcanization time of reference comparative example) / (vulcanization time of each formulation)} x 100

<Breaking strength>
Using a No. 6 dumbbell-shaped test piece made of a vulcanized rubber composition, according to JIS K 6251: 2010 "Vulcanized rubber and thermoplastic rubber-Determination of tensile properties", a tensile test was performed in an atmosphere of 25 ° C. Measure breaking strength TB (MPa) and elongation at break EB (%). Then, the value of TB×EB/2 (MPa %) is calculated. The calculated value is converted into an index with the reference comparative example being 100 according to the following formula. A larger value indicates better breaking strength.
(Breaking strength index) = {(value of each formulation) / (value of reference comparative example)} x 100

<Fuel efficiency>
For the vulcanized rubber composition, the loss tangent ( tan δ _{50° C.} ) is measured, and the fuel efficiency index of the standard comparative example is set to 100, and the fuel efficiency of each composition is expressed as an index according to the following formula. The larger the value, the smaller the rolling resistance and the better the fuel efficiency.
(Fuel efficiency index) =
{(tan δ _{50° C.} of reference comparative example)/(tan δ _{50° C.} of each formulation)}×100

Each index or a value close to it is obtained by conducting each of the above tests based on the formulation contents of Table 1.

In this embodiment, the target value of the moldability index is not less than 100, and the target value of the vulcanization speed index is not less than 100. Moreover, the breaking strength index and the fuel efficiency index exceed 100, and the larger the better.

Claims (7)

For 100 parts by mass of a rubber component containing 50% by mass or more of styrene-butadiene rubber,
80 parts by mass or more of silica,
30 parts by mass or more of a plasticizer, and
A rubber composition for tires comprising an aminoguanidine weak acid salt,
A rubber composition for tires, wherein the plasticizer contains a resin and an oil, and the resin content is 5 parts by mass or more and the oil content is 5 parts by mass or more. For 100 parts by mass of a rubber component containing 50% by mass or more of styrene-butadiene rubber,
80 parts by mass or more of silica,
30 parts by mass or more of a plasticizer, and
A rubber composition for tires comprising an aminoguanidine weak acid salt,
A rubber composition for tires, wherein the rubber component further contains at least one selected from the group consisting of natural rubber and butadiene rubber. 3. The rubber composition for a tire according to claim 1, wherein the rubber component further contains natural rubber and butadiene rubber in addition to 50% by mass or more of styrene-butadiene rubber. The rubber composition for tires according to any one of claims 1 to 3, wherein the aminoguanidine weak acid salt is at least one selected from the group consisting of aminoguanidine bicarbonate and aminoguanidine phosphate. The rubber composition for tires according to any one of claims 1 to 4, wherein the content of aminoguanidine weak acid salt is 0.01 to 10 parts by mass. A tire comprising a tire member composed of the tire rubber composition according to any one of claims 1 to 5. A tire according to claim 6, wherein the tire component is a tread.