JPH11100463A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a pneumatic tire improved in run flat properties in puncture or burst, by arranging a reinforcing liner having a specific composition and a crescent-shaped cross section on a side wall part. SOLUTION: This pneumatic tire is obtained by arranging a reinforcing liner layer of crescent-shaped cross section prepared by blending 100 pts.wt. of a rubber containing 70-100 pts.wt. of a hydrogenated NBR with 20-120 pts.wt. of zinc methacrylate and 0-40 pts.wt. of carbon black (the total of zinc methacrylate and carbon black is <=120 pts.wt.) on a side wall part and bonding the reinforcing liner layer through an adhesive rubber layer prepared by compounding 100 pts.wt. of the total of (A) a specific diene-based rubber and (B) an acrylonitrile-butadiene copolymer rubber and (C) 5-80 pts.wt. of an aromatic petroleum resin having 300-1,500 average molecular weight, 50-160 deg.C softening point and >=20 g/100 g iodine adsorption number to an adjoining rubber layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a puncture or burst run in which a reinforcing liner having a crescent cross section in which zinc methacrylate is blended with hydrogenated NBR is disposed on a sidewall portion. The present invention relates to a pneumatic tire with improved flatness.

[0002]

2. Description of the Related Art Conventionally, a crescent cross section is mainly provided between a carcass layer and an inner liner layer of a side wall portion in order to add a run flat property capable of traveling a certain distance even when the internal pressure is suddenly reduced due to a puncture or a burst. There is a run flat tire into which a reinforcing liner having a shape is inserted. In order to improve the run flat property, the reinforcing liner layer needs to have high elasticity. Therefore, a large amount of carbon black is generally mixed. However, the heat generated in the side wall portion, which is greatly deformed, increases the rolling resistance.In addition, it is difficult to improve the run flat property, for example, the rubber is broken by the generated heat and causes a failure. Was.

In order to solve this problem, hydrogenated NBR having higher rigidity than general-purpose rubber is applied to tire members,
Japanese Patent Application Laid-Open (JP-A) No. 5-185805 discloses a method in which an adjacent rubber layer is adhered to an adjacent rubber layer via an adhesive layer composed of an isobutylene-isoprene copolymer rubber and an ultrahigh molecular weight polyethylene sheet to improve the adhesiveness. However, this method has insufficient adhesiveness and insufficient durability. In addition, there is a problem that productivity is poor because the adhesive layer is composed of two layers.

[0004]

Therefore, in the present invention,
In order to improve the run flat property, the reinforcing liner having a crescent cross-sectional shape to be inserted between the carcass layer and the inner liner layer of the sidewall portion is configured by a specific member,
The reinforcing liner and the rubber layer adjacent thereto are
It is an object of the present invention to provide a pneumatic tire that is firmly bonded through a specific adhesive rubber layer made of a layer.

[0005]

According to the present invention, an ethylenically unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber having a conjugated diene unit content of 30% by weight or more is used.
A total of 100 parts by weight of rubber containing 100 to 100 parts by weight contains zinc methacrylate in an amount of 20 to 120 parts by weight and does not contain carbon black or 40 parts by weight or less, and the amount of zinc methacrylate and carbon black A reinforcing liner layer having a crescent cross-sectional shape made of a rubber composition having a total of 120 parts by weight or less is disposed on the side wall portion, and (A) natural rubber, polyisoprene rubber, polybutadiene rubber, conjugated diene-aromatic vinyl copolymer (C) an average molecular weight of 300 to 1500, and a total of 100 parts by weight of at least one diene rubber selected from coalesced rubbers and (B) an acrylonitrile-butadiene copolymer rubber.
Softening point 50-160 ° C, iodine adsorption 20g / 100g
A pneumatic tire is provided which is bonded to an adjacent rubber layer via an adhesive rubber layer containing 5 to 80 parts by weight of the above aromatic petroleum resin.

Further, according to the present invention, the adhesive rubber layer has a thickness of 0.1 to 2.0 mm, and (A) a diene rubber and (B) acrylonitrile contained in the adhesive rubber layer. When the weight ratio of the butadiene copolymer rubber is A: B =
10:90 to 90:10, and the adhesive rubber layer is made of a higher ester of methacrylic acid, triallyl isocyanurate, a metal salt of methacrylic acid or acrylic acid, diallyl phthalate and 1,2-polybutadiene. The pneumatic tire according to claim 1, further comprising at least one co-crosslinking agent selected from the group consisting of:

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a hydrogenated NBR is given to a material constituting a reinforcing liner layer having a crescent cross section which is inserted and arranged between a carcass layer and an inner liner layer in a sidewall portion of a pneumatic tire. When the composition is used, it is possible to increase the elasticity of the reinforcing liner layer without increasing the heat generation property, and to improve the run flat property without increasing the rolling resistance because the elastic modulus at the time of high temperature is small. Also, even if the elasticity of the material is increased, it has higher durability than the conventional rubber composition, so that even if the cross-sectional area of the reinforcing liner layer is reduced, the elasticity of the reinforcing liner layer can be made equal to the conventional one. Therefore, it has been found that a lightweight run flat tire can be obtained without lowering the run flat property.

As the hydrogenated NBR used in the reinforcing liner layer in the present invention, an ethylenically unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber having a conjugated diene unit content of 30% 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 reinforcing liner layer having a crescent cross section used in the present invention comprises 20 to 120 parts by weight of zinc methacrylate and carbon black 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 constitute a hydrogenated NBR rubber composition in which 0 to 40 parts by weight is blended and the total amount of the zinc methacrylate and carbon black is 120 parts by weight or less. In this hydrogenated NBR composition, if the hydrogenated NBR is 70 parts by weight or less, it is too soft and unsuitable for use.
There is no problem even with 100 parts by weight. In addition, hydrogenated NB
If the zinc methacrylate blended in the R composition is less than 20 parts by weight, it will be too soft, and if it exceeds 120 parts by weight, it will be too hard. Further, there is no problem even if carbon black is not blended in the hydrogenated NBR composition.
It is not preferable that the content is more than 0 parts by weight because the composition becomes brittle and may be broken. On the other hand, if the total of the carbon black and zinc methacrylate to be added to the hydrogenated NBR composition exceeds 120 parts by weight, the composition becomes too hard and the riding comfort of the vehicle is deteriorated.

The method of mixing the above-mentioned zinc methacrylate (including those in the form of zinc dimethacrylate) into the hydrogenated NBR composition is not particularly limited, but rolls and Banburys usually used in the rubber industry are 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-butylcumyl 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 may include 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, in order to improve the adhesion between the reinforcing liner layer and the adjacent rubber layer,
(A) at least one diene rubber selected from natural rubber, polyisoprene rubber, polybutadiene rubber, conjugated diene-aromatic vinyl copolymer rubber and (B) acrylonitrile-butadiene copolymer rubber, (A)
+ (B) 100 parts by weight in total, (C) average molecular weight 3
It is necessary to adhere through an adhesive rubber layer containing 5-80 parts by weight of an aromatic petroleum resin having a temperature of 00 to 1500, a softening point of 50 to 160 ° C., and an iodine adsorption amount of 20 g / 100 g or more. When the blending amount of the aromatic petroleum resin of the above (C) is less than 5 parts by weight with respect to the total of (A) + (B) 100 parts by weight, the adhesive strength is reduced. Is large, and in any case, it leads to the destruction of the tire.

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. If it exceeds this range, the adhesive strength will decrease. The thickness of the adhesive rubber layer is
The thickness is preferably 0.1 to 2.0 mm, more preferably 0.1 mm.
2 to 0.8 mm. If this thickness is less than 0.1mm,
If the adhesive rubber layer is cut off during production and processing becomes difficult, and if it is thicker than 2.0 mm, it does not cause any problem in normal running, but this running rubber is used for long running or running under high severity conditions. It is not preferable because the layer generates heat and the adhesive layer is broken.

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.

Hereinafter, the arrangement of the reinforcing liner layer in the pneumatic tire of the present invention will be described with reference to FIG. FIGS. 1 (a) to 1 (e) are half-sectional views in the meridian direction of a pneumatic tire of the present invention. These figures show a reinforcing liner layer, an adhesive rubber layer, and an adjacent rubber having a crescent cross section in a sidewall portion of the tire. 3 shows a mutual arrangement relationship between the reinforcing liner layer and the belt layer and the bead filler of the reinforcing liner layer.

[0018] Arrangement relationship of reinforcing liners [Fig.
(E)] and its merits (a): the carcass layer is composed of two layers inside and outside, the inside carcass layer is folded around the bead core from the inside to the outside of the tire, and this terminal is turned into the inside carcass layer and the outside carcass layer. The outer carcass layer is folded back with the bead core, and the crescent-shaped reinforcing liner layer has one end overlapping the end of the tread belt layer and the other end. Is arranged so as to overlap with the bead filler in the bead part. However, the terminal may be arranged near the bead core by rolling down the outer carcass layer without folding the carcass layer around the bead core. Since the local deformation of the side wall portion is small and the whole is smoothly deformed, the run flat property is most improved, which is a preferable structure. (B): Structure in which one end of the reinforcing liner layer does not overlap with the end of the belt layer as compared to (a). Since the local deformation of the sidewall portion is larger than (a), the effect of improving the run flat property is slightly lower than that of the structure of (a). However, the effect of improving the run flatness is sufficient as compared with the case where the present invention is not used. . (C): A structure in which one end of the reinforcing liner layer does not overlap with the bead filler with respect to (a). Since the local deformation of the side wall portion is larger than (a), the effect of improving the run flat property is slightly lower than that of the structure of (a), but the effect of improvement is sufficient compared with the case where the present invention is not used. . (D): A structure in which both ends of the reinforcing liner layer do not overlap with the belt layer and the bead filler with respect to (a). Since the local deformation of the sidewall portion is larger than (a), the effect of improving the run flat property is slightly lower than that of the structure of (b) or (c), but there is an improvement effect as compared with the case where the present invention is not used. . (E): A structure in which the carcass layer is composed of two layers, and both of the two carcass layers are turned around the bead core from the inside to the outside of the tire. Compared with the structure of (a), the step of turning the outer carcass layer inward can be omitted, and the productivity is improved.

[0019]

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.

The following commercial products were used as the components used in each of the following Examples and Comparative Examples. In addition, the compounding agent which does not vary is not described in the table of the Examples. 1) Components of reinforcing liner layer Hydrogenated NBR: Zetpol 2020 (manufactured by Nippon Zeon) Variable amount Zinc methacrylate: R-20S (manufactured by Asada Chemical) Variable amount Carbon black: N339 (manufactured by Showa Cabot) Variable amount organic peroxide (40% Diluted product): Barcadox 14/40 (by Kazaku Akzo) 5 parts by weight Antioxidant: Nowgard 445 (by Uniroyal) 1.5 parts by weight 2) Compounding components 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) Variable zinc flower: zinc flower # 3 (manufactured by Seido Chemical 5 parts by weight Stearic acid: Bead stearic acid (Nippon Oil & Fat) 1 part by weight Antioxidant: Nocrack 224 (Ouchi Shinko Chemical) 1 part by weight Sulfur: Insoluble sulfur 2 parts by weight (sulfur vulcanization system) Acceleration of vulcanization Agent: Noxeller CZ-G (Ouchi Shinko Chemical) 1 part by weight Vulcanization accelerator: Noxeller TOT-N (manufactured by Ouchi Shinko Chemical) 0.5 parts by weight (sulfur vulcanization) Organic peroxide (40% diluted product): Perkadox 14/40 (Kakuyaku Akzo Variable (organic peroxide cross-linked) Co-crosslinking agent: TAIC (Nippon Kasei) Variable (organic peroxide cross-linked)

The rubber compounds A and B used in Conventional Examples 1 and 2 in Table I are as follows. Conventional rubber compound A B (parts by weight) (parts by weight) NR: RSS # 3 40 40 BR: Nipol BR1220 (manufactured by Nippon Zeon) 60 60 Carbon black: N326M (manufactured by Showa Cabot) 60 80 Zinc flower: Zinc flower # 3 ( 5 5 Stearic acid: Bead stearic acid (Nippon Yushi) 1 1 Antioxidant: Nocrack 6C (Ouchi Shinko Chemical) 2 2 Phenol resin: Sumicanol 610 (Sumitomo Chemical) 6 6 Sulfur: Insoluble sulfur 5 5 Vulcanization accelerator: Noxeller NS-F (Ouchi Shinko Chemical) 2 2

Production of Test Run Flat Tire A reinforcing liner layer and an adhesive layer having the composition shown in each example were formed by a conventional method, and these were formed into a predetermined shape as shown in FIG.
They were arranged and adhered so as to have the arrangement relationships shown in (a) to (e). A run-flat tire having a size of 255 / 40R17 was produced and subjected to a run-flat durability test, a rolling resistance test, and a riding comfort test, respectively.

The measurement and evaluation methods in each example are as follows. 1) Run flat durability test method 4.90kN / 0kP
In a, run with test tires installed so that the tires do not fall off the rim, and measure the distance until the tires fail. Each example is shown by an index with the conventional tire being 100, and the larger the index is, the better the run flat durability is.

2) Rolling resistance test method The vehicle travels under the following conditions, and the rolling resistance at that time is measured.
The index is expressed as an index with the measured value of the conventional tire being 100, indicating that a smaller value is better. Running conditions: Drum surface is smooth, made of steel and has a diameter of 17
The ambient temperature was 23 ± 2 using a 07 mm drum tester.
℃, rim size 17 × 9JJ, test internal pressure 220kP
a, Run at a speed of 80 km / h with a load of 5.5 kN.

3) Ride comfort test method The test tire was mounted on a rim of 17 × 9JJ and the internal pressure was 220
Fill it with kPa, mount it on a car, and evaluate the feeling by driving on a test course with five trained drivers. The results were scored by a 5-point scale based on the following criteria based on a relative comparison with a reference tire, and the average score of the three persons excluding the highest point and the lowest point was classified as follows. Judgment criteria: 5: Excellent 4: Excellent 3: Equivalent 2: Inferior 1: Inferior Classification: Average point is larger than standard (3 points): ◎ Standard equivalent: ○ Below standard: ×

Conventional Examples 1-2, Examples 1-22 and Comparison
Table 1 shows the measurement and evaluation results of the run flat tires in Examples 1 to 10 .

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

As can be seen from the results of Table I, the reinforcing liner layer of the composition according to the present invention is bonded to an adjacent rubber layer in a predetermined arrangement through an adhesive rubber layer of a predetermined composition. The pneumatic tire thus obtained has good run-flat durability, rolling resistance, and riding comfort, and it can be seen that an excellent run-flat tire can be obtained.

[Brief description of the drawings]

FIG. 1 is a meridian direction half cross-sectional view showing an aspect of an arrangement portion of a reinforcing liner layer in a run flat tire.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 5/098 C08K 5/098

Claims (4)

[Claims] 1. A total of 10 rubbers containing 70 to 100 parts by weight of an ethylenically unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber having a conjugated diene unit content of 30% by weight or less.
0 parts by weight, 20 to 120 parts by weight of zinc methacrylate, and no carbon black or 40
A reinforcing liner layer having a crescent cross-sectional shape made of a rubber composition containing not more than 120 parts by weight of zinc methacrylate and carbon black in a total amount of not more than 120 parts by weight, and (A) At least one diene rubber selected from natural rubber, polyisoprene rubber, polybutadiene rubber, conjugated diene-aromatic vinyl copolymer rubber, and (B) acrylonitrile-butadiene copolymer rubber, ) 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 used for 5-80.
A pneumatic tire characterized by being bonded to an adjacent rubber layer via an adhesive rubber layer blended by weight. 2. The adhesive rubber layer has a thickness of 0.1 to 2.
The pneumatic tire according to claim 1, wherein the diameter is 0 mm. 3. The weight ratio of (A) the diene rubber and (B) the acrylonitrile-butadiene copolymer rubber contained in the adhesive rubber layer is in the range of A: B = 10: 90 to 90:10. The pneumatic tire according to claim 1, wherein: 4. The adhesive rubber layer according to claim 1, wherein the adhesive rubber layer comprises 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.
The pneumatic tire according to any one of claims 1, 2, or 3, comprising a kind of co-crosslinking agent, and crosslinked with an organic peroxide.