JPH11147402A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase strength of a tire against deformation by disposing rubber composition which includes a specific wt.% of ethylene unsaturated nitrile-diene high saturated rubber, the content of which by unit of diene is equal to or less than a specific wt.%, and a specific wt.% of zinc methacrylate. SOLUTION: Hydrogenated NBR whose content by unit of diene is equal to or less than wt.% of 30 is used as the ethylene unsaturated nitrile-diene high saturated copolymer rubber (hydrogenated NBR) used in bead toe portion. The hydrogenated NBR used preferably contains diene unit by 20% or less by wt.%. When the content of diene unit is equal to or greater than 30% by wt.%, that is, when partial water dope rate is 50% or less, the strength of the rubber composition is insufficient. Accordingly, desirable strength cannot be obtained. The bead toe portion consists of hydrogenated NBR rubber composition mixed with zinc methacrylate by 20 to 120 wt.% with respect a total wt.% of rubber 100, including 70 to 100 wt.% of hydrogenated NBR.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic tire, and more particularly, to a highly saturated ethylenically unsaturated nitrile-conjugated diene system having a conjugated diene unit content of 30% by weight or less in a bead toe portion of the tire. Copolymer rubber (hereinafter, referred to as
It is called “hydrogenated NBR”. ), And a pneumatic tire using a specific hydrogenated NBR composition.

[0002]

2. Description of the Related Art A hard rubber layer is arranged on a bead toe portion,
Japanese Unexamined Patent Publication (Kokai) No. 2-179513 discloses that by reducing the decrease in rubber hardness at high temperatures, the rim resistance is improved and the steering stability during high-speed continuous running is improved. However, if a large amount of resin or carbon black is blended for the purpose of hardening the rubber layer of the bead toe, the rubber becomes brittle, and there is a problem that the bead toe cannot withstand large deformation during rim assembly and is damaged. Was.

[0003]

Accordingly, in the present invention, a specific hydrogenated NBR composition having a higher hardness than rubber, a higher strength against deformation, and a lower temperature dependence of hardness than rubber is used in the bead toe portion. It is an object of the present invention to provide a pneumatic tire having improved rim separation resistance and improved steering stability without lowering the strength of the bead toe portion.

[0004]

According to the present invention, an ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber having a conjugated diene unit content of 30% by weight or less is contained in at least a part of the bead toe portion. There is provided a pneumatic tire in which a rubber composition containing from 100 to 100 parts by weight and containing zinc methacrylate from 20 to 120 parts by weight is arranged.

Further, according to the present invention, the rubber composition in the bead toe portion is further blended with 40 parts by weight or less of carbon black, and the total amount of zinc methacrylate and carbon black is 120 parts by weight or less. Included tires are provided.

According to the present invention, (A) natural rubber,
At least one diene rubber selected from polyisoprene rubber, polybutadiene rubber, conjugated diene rubber-aromatic vinyl copolymer rubber, and (B) acrylonitrile-
To 100 parts by weight of butadiene copolymer rubber, (C) an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160 ° C., and an iodine adsorption amount of 20 g / 100 g or more was added.
A pneumatic tire in which a bead toe portion rubber member is bonded to an adjacent rubber layer via an adhesive rubber layer made of a rubber composition mixed with 80 parts by weight is provided.

Further, according to the present invention, the weight ratio of the component (A) to the component (B) in the adhesive rubber layer is (A) / (B).
Is 90/10 to 10/90, the thickness of the adhesive rubber layer is 0.1 to 1.5 mm, and the adhesive rubber layer is a higher methacrylic acid ester, triallyl. Pneumatic containing at least one co-crosslinking agent selected from isocyanurate, a metal salt of methacrylic acid or acrylic acid, diallyl phthalate, and 1,2-polybutadiene, and crosslinked with an organic peroxide. A tire is provided.

[0008]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a member constituting a bead toe portion of a pneumatic tire is provided with a given hydrogenated NBR.
Using the composition, and bonding between the bead toe portion and an adjacent rubber layer via an adhesive rubber layer made of a specific diene rubber, acrylonitrile-butadiene copolymer rubber, and an aromatic petroleum resin The main feature is.

The hydrogenated NBR used in the bead toe portion in the present invention has a conjugated diene unit content of 3
An ethylenically unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber having 0% by weight or less is used. Hydrogenated NBR
Use a conjugated diene unit having a content of 30% by weight or less, more preferably 20% by weight or less. If the content of the conjugated diene unit is 30% by weight or more, that is, the partial hydrogenation ratio is about 50% or less, the strength of the rubber composition becomes insufficient, and the desired strength cannot be obtained.

The above-mentioned hydrogenated NBR (ethylenically unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber) is already known, and includes ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile and 1,3-butadiene; Copolymers with conjugated dienes such as isoprene and 1,3-pentadiene, monomers copolymerizable with the above two monomers, for example, vinyl aromatic compounds, (meth) acrylic acid, alkyl (meth) ) Acrylates, alkoxyalkyl (meth) acrylates, cyanoalkyl (meth) acrylates and other multi-component copolymers, specifically,
Acrylonitrile-butadiene copolymer rubber, acrylonitrile-isoprene copolymer rubber, acrylonitrile-butadiene-isoprene copolymer rubber, acrylonitrile-
Butadiene-acrylate copolymer rubber, acrylonitrile-butadiene-acrylate-methacrylic acid copolymer rubber and the like can be mentioned. These rubbers contain 30 to 60% by weight of an ethylenically unsaturated nitrile unit, and the conjugated diene unit is reduced to 30% by weight or less, preferably 20% by weight or less by means such as partial hydrogenation of the conjugated diene unit. .

The bead toe portion used in the present invention comprises a hydrogenated NBR rubber composition obtained by blending 20 to 120 parts by weight of zinc methacrylate with respect to 100 parts by weight of the rubber containing 70 to 100 parts by weight of the hydrogenated NBR. It is necessary to configure. In this hydrogenated NBR rubber composition,
If the hydrogenated NBR is less than 70 parts by weight, it is unsuitable for use because it is too soft and the steering stability is reduced, but there is no problem with 100 parts by weight. If the amount of zinc methacrylate to be added to the hydrogenated NBR composition is less than 20 parts by weight, the steering stability is deteriorated because it is too soft, and if it exceeds 120 parts by weight, the fitting property with the rim is deteriorated because it is too hard. I do. The hydrogenated NBR composition may further contain 40 parts by weight or less of carbon black. In this case, the total blending amount of the zinc methacrylate and carbon black needs to be 120 parts by weight or less. If the amount of the carbon black exceeds 40 parts by weight, the carbon black becomes brittle and is damaged by large deformation when the tire rim is assembled. On the other hand, if the total amount of zinc methacrylate and carbon black exceeds 120 parts by weight, it becomes too hard and the fitting property with the rim deteriorates.

The method of mixing the above zinc methacrylate (including the one in the form of zinc dimethacrylate) into the hydrogenated NBR composition is not particularly limited, but a roll, Banbury or the like usually used in the rubber industry is used. A mixer such as a kneader, a single-screw kneader, or a twin-screw kneader can be used. In addition to the method of directly mixing zinc methacrylate with hydrogenated NBR, first, a zinc compound such as zinc oxide or zinc carbonate is blended with hydrogenated NBR and sufficiently dispersed, and then methacrylic acid is mixed or absorbed. Alternatively, a method of forming zinc methacrylate in the polymer may be adopted, and this method is preferable because a very good dispersion of zinc methacrylate can be obtained. It is also preferable to use a composition in which zinc methacrylate and a zinc compound are dispersed in hydrogenated NBR in advance.
C "(trade name) series, for example, ZSC2295, ZS
It is available as C2295N, ZSC2395, ZSC2298, and the like.

The hydrogenated NBR composition is preferably crosslinked with an organic peroxide. As the organic peroxide, those commonly used for peroxide vulcanization of rubber can be used. For example, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, benzoyl peroxide, 2,5
-Dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-mono (t -Butylperoxy) hexane, α, α'-bis (t-butylperoxy-m-isopropyl) benzene and the like. These organic peroxides may be used alone or in combination of two or more.
It is desirable to add 10 to 10 parts by weight, preferably 0.2 to 6 parts by weight.

The hydrogenated NBR compound includes other fillers such as silica, calcium carbonate, talc, triallyl isocyanurate, higher esters of methacrylic acid, diallyl phthalate, m-phenylene bismaleimide, Crosslinking aids such as 1,2-polybutadiene and other plasticizers commonly used in the rubber industry;
An antioxidant, a stabilizer, an adhesive, a resin, a processing aid, a coloring agent, and the like may be appropriately blended.

According to the present invention, there are provided (A) natural rubber, polyisoprene rubber, polybutadiene rubber, conjugated diene-aromatic, and At least one diene rubber selected from vinyl copolymer rubbers and (B) acrylonitrile-butadiene copolymer rubber are blended, and (A) + (B) 100 parts by weight in total and (C) average An aromatic petroleum resin having a molecular weight of 300 to 1500, a softening point of 50 to 160 ° C., and an iodine adsorption amount of 20 g / 100 g or more is used.
Adhesion can be achieved via an adhesive rubber layer containing 80 parts by weight. If the amount of the aromatic petroleum resin of (C) is less than 5 parts by weight based on 100 parts by weight of (A) + (B) in total, the processability of the adhesive rubber is deteriorated. Also, 8
If it exceeds 0 parts by weight, the compression set deteriorates.

The compounding ratio of (A) the diene rubber and (B) the acrylonitrile-butadiene copolymer rubber contained in the adhesive rubber layer is such that A: B = 10: 90 to 90:10. It is preferred in that respect. The thickness of the adhesive rubber layer is preferably 0.1 to 1.5 mm, more preferably 0.2 to 0.8 mm. If the thickness is less than 0.1 mm, the adhesive rubber layer will be cut or difficult to process during production. If the thickness is more than 1.5 mm, the bead width will be wide and the fit with the rim will be poor. It is not preferable because it deteriorates.

The adhesive rubber layer may further comprise at least one selected from higher esters of methacrylic acid, triallyl isocyanurate, metal salts of methacrylic acid or acrylic acid, diallyl phthalate, and 1,2-polybutadiene.
It is more preferred to include a co-crosslinking agent and to crosslink with an organic peroxide. In addition to the (C) aromatic petroleum resin, a compounding agent generally mixed with rubber, for example, a filler such as carbon, silica, talc, etc. , An antioxidant, a plasticizer, a processing aid, a resin, an adhesive, a crosslinking aid, a vulcanization accelerator, a tackifier and the like may be appropriately compounded.

The tire according to the present invention does not necessarily require the above-mentioned adhesive rubber layer since the distortion generated in the bead toe portion is small in the case of ordinary running, but in the case of running with high severity (for example, circuit running), It is preferable to have an adhesive rubber layer because the distortion is increased in the bead toe portion.

The bead toe rubber member according to the present invention is actually used in a mode as shown in the embodiments (A) and (B) of FIG. In addition, a preferable arrangement relationship of the bead toe portion rubber member will be described with reference to FIG.
It is preferable to arrange them so as to satisfy the relationship of Ls and Hc ≦ H ≦ 2Hc. In the formula, L: distance in the tire axial direction from the bead toe below the bead core of the toe portion rubber member, Lc: distance in the tire axial direction from the bead toe to the inside of the bead core, Ls: distance in the tire axial direction from the bead toe to the outside of the bead core, H: toe portion rubber member Hc: height in the tire radial direction from the bead toe to the upper end of the toe portion rubber member, and Hc: height in the tire radial direction from the bead toe of the toe portion rubber member to the center of the bead core. Here, in the case of L <Lc, since there is no portion facing the lower side of the bead core, the toe rubber member may fall off when the rim is assembled, and in the case of L> Ls. In this case, the fitting between the tire and the rim may be deteriorated. When H <Hc,
The bead portion may easily fall down during cornering, and the effect of improving steering stability may be reduced.
In the case of 2Hc, the fitting by the rim assembly may be slightly reduced.

[0020]

Hereinafter, the present invention will be described with reference to Examples.
It goes without saying that the scope of the present invention is not limited to these examples.

In the following conventional examples, examples and comparative examples,
Tire size: 185 / 65R14 using the components shown in each table and having the tire configuration shown in each table.
Were produced, and the test results for these tires were shown.

The following commercially available products were used as the components used in each example. In addition, the compounding agent which does not vary is not described in the table of the Examples. 1) Compounding component HNBR of toe rubber part HNBR: Zetpol 2020 (manufactured by Zeon Corporation) Variable zinc methacrylate: R-20S (manufactured by Asada Chemical) variable carbon black (FEF grade): HTC-100 (manufactured by Chubu Carbon) variable zinc zinc : Zinc flower # 3 (manufactured by Seido Chemical) 5 parts by weight Antioxidant: Nowgard 445 (manufactured by Uniroyal) 1.5 parts by weight Organic peroxide: Perkadox 14/40 (manufactured by gunpowder Akzo) 5 parts by weight 2) Compounding component of adhesive rubber layer Diene rubber (NR): RSS # 3 Variable NBR: Nipol DN401 (manufactured by Nippon Zeon) Variable carbon black: N339 (manufactured by Showa Cabot) 50 parts by weight Aromatic petroleum resin: FR-120 (manufactured by Fujikosan) Zinc flower: zinc flower # 3 (manufactured by Seido Chemical) 5 parts by weight Stearic acid: bead stearic acid (manufactured by NOF Corporation) Part Antioxidant: Nocrack 224 (manufactured by Ouchi Shinko Chemical) 1 part by weight Sulfur: 2 parts by weight of insoluble sulfur (in the case of sulfur vulcanization system blending) Vulcanization accelerator: Noxeller CZ-G (manufactured by Ouchi Shinko Chemical) 1 Parts by weight (in the case of sulfur vulcanization) Vulcanization accelerator: Noxeller TOT-N (manufactured by Ouchi Shinko Chemical) 0.5 part by weight (in the case of sulfur vulcanization) Organic peroxide (40% diluted product) ): Parkadox 14/40 (produced by Gunpowder Akzo) 5 parts by weight (in the case of organic peroxide cross-linking compound) Co-crosslinking agent (TAIC): TAIC (manufactured by Nippon Kasei) 3 parts by weight (organic peroxide cross-linking compound) in the case of)

The rubber compounds used in the conventional example and comparative example 1 are as follows. Rubber compounding Conventional example Comparative example 1 (parts by weight) (parts by weight) NR: RSS # 3 40 40 BR: Nipol BR1220 60 60 (manufactured by Zeon Corporation) Carbon black: N326M 60 80 (manufactured by Showa Cabot) Zinc flower: Zinc flower # 3 (manufactured by Seido Chemical) 5 5 Stearic acid: Bead stearic acid 11 (manufactured by NOF Corporation) Antioxidant: Nocrack 6C22 (manufactured by Ouchi Shinko Chemical) Phenol resin: Sumikanol 610 66 (manufactured by Sumitomo Chemical) Sulfur: Insoluble sulfur 55 Vulcanization accelerator: Noxeller NS-F22 (manufactured by Ouchi Shinko Chemical)

The measurement and evaluation methods in each example are as follows. 1) A test tire assembled on a rim having a rim resistance of 14 × 5.5 J was mounted on a 1.5-liter FF passenger car, and a semicircle having a radius of 6 m as shown in FIG. The vehicle was driven at a speed of 35 km / h on the test course, and the tire pressure of the left front wheel of the test vehicle was reduced by 10 kPa from 200 kPa in increments of 10 kPa, and the air pressure when a rim touch or rim detachment occurred was measured. The test was performed at each air pressure (200 kPa, 190 kPa, 1
80 kPa,...) And repeated five times. The index is shown as an index (reciprocal) with the value of the conventional tire as a reference (100). The larger the index, the better the rim resistance.

2) Evaluation of steering stability Immediately after a test tire assembled on a rim of 14 × 5.5 J was mounted on a 1.5-liter FF passenger car and conditioned at a high speed for about 30 minutes. Five pylons were installed at 30 m intervals on a straight road of asphalt pavement to perform a slalom run, and the running time was measured. The running time was indicated by an index (reciprocal) with the time of a conventional tire being 100. The larger the index, the better the steering stability.

3) Evaluation test of rim assembling property A tire is mounted on a rim of 14 × 5.5J by a rim assembling apparatus (Tire Changer MON-2 manufactured by Hoffman Japan KK).
In 1E-4), rim assembly and rim removal were each repeated 10 times, and the presence or absence of damage to the bead toe portion was observed. "○" indicates that no damage occurred even after repeating 10 times, "O" indicates that damage did not occur after 3 times but damage occurred by 10 times, but damage occurred by 3 times The result is indicated by "x".

4) Fitting evaluation test A small amount of soapy water is applied to the bead portion in contact with the rim of the tire, and while the soapy water does not dry, the rim assembling apparatus (Tire Changer MON-21E manufactured by Hoffman Japan KK) is used.
-4) Assemble the rim. Thereafter, the air pressure was filled to 200 kPa, and after leaving it for 10 minutes, the interval between the rim check line and the rim flange at the bead portion of the tire was measured at equal intervals over 20 turns in a direction perpendicular to the tire axis.・ Toe peak value was determined. This value is shown as an index (reciprocal number) with the conventional tire as 100. The larger the index, the better the fit.

Conventional tires, Examples 1 to 4 and Comparative examples 1 to 2 When the compounding amount of hydrogenated NBR in the toe rubber member was changed, the rim resistance of the test tire, the steering stability,
Table I below shows the test results related to the rim assembling property and the fitting property.

[0029]

[Table 1]

From the results in Table I, it can be seen that the hydrogenated N
Each of the examples using the toe rubber member having the BR composition has excellent rim removal resistance, steering stability,
It can be seen that the rim assembling property and the fitting property are shown.

Conventional tires, Examples 5 to 7 and Comparative examples 3 to 6 Test tires in which the amounts of zinc methacrylate and carbon black in the toe rubber members were changed were changed in rim resistance, steering stability and rim. Table II below shows the test results related to the assembling property and the fitting property.

[0032]

[Table 2]

From the results in Table II, it can be seen that each of the examples using the tow rubber member having the composition of zinc methacrylate and carbon black according to the present invention has excellent rim-off resistance and steering stability. It can be seen that the rim assembling property and the fitting property are shown.

Conventional Examples and Examples 8 to 9 (A) Diene rubber and (B) NBR in the adhesive rubber layer
Table III below shows the test results relating to the rim resistance, the steering stability, the rim assembling property, and the fitting property of the test tires when the compounding ratio was changed.

[0035]

[Table 3]

From the results in Table III, it can be seen that each of the examples using the adhesive rubber layer having each component composition of the adhesive rubber according to the present invention has excellent rim removal resistance, steering stability,
It can be seen that the rim assembling property and the fitting property are shown.

Conventional Example, Examples 10 to 14 and Comparative Example 7
8 adhesive rubber layer thickness of bead unseating resistance of test tires in the case of changing the steering stability, the test results of the rim assembly resistance and fitting property in the following Table IV.

[0038]

[Table 4]

From the results in Table IV, it can be seen that each of the examples using the adhesive rubber layer having the thickness of the adhesive rubber layer according to the present invention has excellent rim removal resistance, steering stability and rim assembly. It can be seen that the properties and the fitting properties are shown.

[0040]

As described above, in the present invention, the hydrogenated NBR according to the present invention is applied to at least a part of the bead toe portion of the tire.
By using the composition and further firmly adhering it to the adjacent rubber using a predetermined adhesive rubber layer, it is excellent in terms of rim disengagement resistance, steering stability, rim assembling property, fitting property, etc. A pneumatic tire can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view in the meridian direction of a tire showing a configuration of a toe rubber member in a bead structure of a pneumatic tire.

FIG. 2 is a meridional section view of the tire showing a positional relationship of a toe rubber member in a bead toe portion of the pneumatic tire.

FIG. 3 is a view showing an outline of a test course used in a rim resistance test of a test tire.

Claims (6)

[Claims] 1. An ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber having a conjugated diene unit content of 30% by weight or less in at least a part of a bead toe portion.
A pneumatic tire comprising a rubber composition containing 0 parts by weight and containing 20 to 120 parts by weight of zinc methacrylate. 2. The rubber composition of the bead toe part further contains carbon black in an amount of 40 parts by weight or less, and the total amount of zinc methacrylate and carbon black is 120 parts by weight.
The pneumatic tire according to claim 1, wherein the amount is not more than part by weight. (A) natural rubber, polyisoprene rubber,
At least one diene rubber selected from polybutadiene rubber, conjugated diene-aromatic vinyl copolymer rubber, and (B) acrylonitrile-butadiene copolymer rubber 1
An adhesive rubber layer composed of a rubber composition in which (C) an aromatic petroleum resin having an average molecular weight of 300 to 1500, a softening point of 50 to 160 ° C, and an iodine adsorption amount of 20 g / 100 g or more is mixed with 00 parts by weight. The pneumatic tire according to claim 1 or 2, wherein the bead toe portion rubber member is adhered to an adjacent rubber layer via a via. 4. The weight ratio (A) / (B) of the component (A) to the component (B) in the adhesive rubber layer is 90/10 to 1
The pneumatic tire according to claim 3, wherein the ratio is 0/90. 5. The adhesive rubber layer has a thickness of 0.1-1.
The pneumatic tire according to claim 3 or 4, wherein the diameter is 5 mm. 6. The adhesive rubber layer further comprises at least one selected from the group consisting of higher esters of methacrylic acid, triallyl isocyanurate, metal salts of methacrylic acid or acrylic acid, diallyl phthalate and 1,2-polybutadiene. The pneumatic tire according to any one of claims 3 to 5, comprising a crosslinking agent and being crosslinked with an organic peroxide.