JP2000318405A - Pneumatic tier for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain occurrence of carcass edge separation by constituting a reinforcing rubber layer arranged on the outside of a carcass edge part of specific hydrogenated NBR rubber and arranging an adhesive rubber layer blending specific aromatic petroleum resin, etc., between adjacent other material rubber. SOLUTION: A reinforcing rubber layer 4 for the outside of a carcass edge part rubber component (rubber including hydrogenated NBR) composed of the 0-120 pts.wt. of methacrylic acid zinc and the 0-60 pts.wt. of carbon black to the 100 pts.wt. of rubber including ethylene unsaturated nitrly-conjugate diene high saturated rubber with the content of less than 30% conjugate diene unit, where total weight part is 10-120. Additionally, an adhesive rubber layer blending a 5-80 pts.wt. of aromatic petroleum resin of everage molecular weight 300-15000, a softening point of 50-160 deg.C and iodine absorbing quantity of more than 20 g/100 g is arranged between adjacent other material rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for heavy loads, and more particularly to a rubber containing a specific hydrogenated NBR (that is, an ethylenically unsaturated rubber having a conjugated diene unit content of 30% or less). 0 to 120 parts by weight of zinc methacrylate and 0 to 60 parts by weight of carbon black are added to 100 parts by weight of the rubber containing the nitrile-conjugated diene-based highly saturated rubber, and the total amount of zinc methacrylate and carbon black is added. Is 10 to 120 parts by weight "), and a heavy-duty pneumatic tire used for a reinforcing rubber layer disposed outside a carcass edge portion of a folded portion of a carcass of a tire.

[0002]

2. Description of the Related Art Conventionally, in heavy duty pneumatic tires used for trucks and buses, carcass edge separation occurs due to repeated application of tension and compression to the carcass edge portion of the carcass turning portion in the bead portion of the tire during running. There was a problem that it was easy to do. Therefore, as a solution to the above, in order to suppress the occurrence of separation at the carcass edge portion and to improve its durability, a proposal has been made to provide a reinforcing layer or a cushion rubber layer in which a cord is embedded in rubber at the carcass edge portion of the carcass turn-back portion. Is being done. However, the required improvement has not yet been achieved, and it is necessary to further improve the durability of the carcass edge part. I was

[0003]

Therefore, in the present invention,
An object of the present invention is to provide a heavy-duty pneumatic tire with excellent durability, which suppresses the occurrence of separation of the pneumatic tire due to the carcass edge portion of the carcass turning portion in the bead portion.

[0004]

According to the present invention, in a heavy-duty pneumatic tire in which a carcass is folded back via a bead core, a reinforcing rubber layer (hereinafter simply referred to as a "carcass edge") disposed outside a carcass edge portion of a folded portion of the carcass. The content of co-diene units is 30%.
A total of 100 parts by weight of the rubber containing the following ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber is mixed with 0 to 120 parts by weight of zinc methacrylate and 0 to 60 parts by weight of carbon black, and zinc methacrylate And a rubber composition in which the total amount of carbon black is 10 to 120 parts by weight (hereinafter simply referred to as "rubber containing hydrogenated NBR").
That. And (A) at least one selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber, and conjugated diene-aromatic vinyl copolymer rubber between the rubber composition and an adjacent diene rubber. One type of diene rubber and (B) 100 parts by weight of acrylonitrile-butadiene copolymer rubber in total (C) average molecular weight of 300 to 1
500, softening point 50-160 ° C, iodine adsorption 20g /
A heavy-duty pneumatic tire characterized in that an adhesive rubber layer (hereinafter, simply referred to as “adhesive rubber layer”) composed of a rubber composition containing 5-80 parts by weight of an aromatic petroleum resin of 100 g or more is arranged. Provided.

Further, according to the present invention, the rubber of the reinforcing rubber layer is prepared by adding an ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber having a co-projection diene unit content of 30% or less to a total amount of rubber of 100%. There is provided a heavy duty pneumatic tire characterized by containing 40 parts by weight or more based on parts by weight.
Further, according to the present invention, the thickness of the adhesive rubber layer is 0.1
A heavy-duty pneumatic tire having a diameter of from 2.0 mm to 2.0 mm is provided.

According to the present invention, the weight ratio (A) / (B) of the rubber (A) and the rubber (B) in the adhesive rubber layer is 90/10 to 10/90. A heavy pneumatic tire is provided.

Further, according to the present invention, the adhesive rubber layer is formed of 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. A pneumatic tire for heavy load is provided, which comprises one type of co-crosslinking agent and is crosslinked with an organic peroxide.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, the reinforcing rubber layer disposed outside the carcass edge portion of the carcass turn-back portion of the pneumatic tire has a co-projection diene unit content of 30%.
For 100 parts by weight of the rubber containing the following ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber (hydrogenated NBR), 0 to 120 parts by weight of zinc methacrylate and 0 to 60 parts by weight of carbon black are blended, And the total amount of zinc methacrylate and carbon black is 10 to 12
0 parts by weight of rubber composition (rubber containing hydrogenated NBR)
And (A) natural rubber, polyisoprene rubber, between the reinforcing rubber layer composed of the rubber containing the hydrogenated NBR and the adjacent other part composed of the diene rubber. 100 parts by weight of at least one diene rubber selected from polybutadiene rubber, conjugated diene-aromatic vinyl copolymer rubber and (B) acrylonitrile-butadiene copolymer rubber, and (C) an average molecular weight of 30
0-1500, softening point 50-160 ° C, iodine adsorption amount 2
An adhesive rubber layer (adhesive rubber layer) composed of a rubber composition containing 5-80 parts by weight of an aromatic petroleum resin of 0 g / 100 g or more, and the reinforcing rubber composed of a rubber containing the hydrogenated NBR; It is characterized in that the layer and the parts made of diene rubber are firmly bonded.

The rubber containing hydrogenated NBR of the present invention contains zinc methacrylate in an amount of 0 to 120 parts by weight, preferably 10 to 100 parts by weight, based on 100 parts by weight of the rubber containing the hydrogenated NBR.
A rubber composition is used in which 120 parts by weight and 0 to 60 parts by weight of carbon black are mixed, and the total amount of zinc methacrylate and carbon black is 10 to 120 parts by weight. In the rubber containing the hydrogenated NBR, the hydrogenated NBR is more preferably at least 40 parts by weight out of 100 parts by weight of the total amount of the rubber from the viewpoint of the strength of the rubber, and this is 100 parts by weight. Does not matter at all. If the total amount of zinc methacrylate and carbon black to be added to the rubber containing hydrogenated NBR is less than 10 parts by weight, the strength becomes insufficient, and
Exceeding the parts by weight is too hard, which leads to tire destruction, which is inconvenient. And this hydrogenated NB
The rubber containing R is excellent in breaking strength, durability, and fatigue resistance, has low heat generation, and has a small decrease in hardness at a high temperature as compared with the conventional diene rubber. By using the reinforcing rubber layer, to suppress the occurrence of separation of the pneumatic tire due to the carcass edge portion of the carcass folded portion in the bead portion,
Durability can be improved.

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 co-projection dienes such as isoprene and 1,3-pentadiene, monomers copolymerizable with the above two monomers, for example, vinyl aromatic compounds, (meth) acrylic acid, alkyl It is a multi-component copolymer with (meth) acrylate, alkoxyalkyl (meth) acrylate, cyanoalkyl (meth) acrylate, and the like.
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 co-projection diene unit is reduced to 30% by weight or less, preferably 20% by weight or less by means such as partial hydrogenation of a conjugated diene unit. is there.

The method of mixing the hydrogenated NBR with the zinc methacrylate (including those in the form of zinc dimethacrylate) and / or carbon black is not particularly limited, but is usually used in the rubber industry. For example, a mixer such as a roll, a Banbury, a kneader, a single-screw kneader, or a twin-screw kneader can be used.

As a method of mixing zinc methacrylate with hydrogenated NBR, besides a method of directly mixing zinc methacrylate with hydrogenated NBR, first, a zinc compound such as zinc oxide or zinc carbonate is mixed with hydrogenated NBR. After blending and fully dispersing, a method may be adopted in which methacrylic acid is mixed or absorbed to form zinc methacrylate in the polymer.This method provides a very good dispersion of zinc methacrylate. preferable. It is also preferable to use a composition in which zinc methacrylate and a zinc compound are dispersed in hydrogenated NBR in advance.
SC "(trade name) series, such as ZSC2295, Z
It is available as SC2295N, ZSC2395, ZSC2298, and the like.

The rubber containing hydrogenated NBR is preferably crosslinked by an organic peroxide compounded as a crosslinking agent. 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) hexine-3, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-mono (t-butylperoxy)
Oxy) hexane, α, α′-bis (t-butylperoxy-m-isopropyl) benzene and the like.
One or more of these organic peroxides are used, and it is desirable to add 0.2 to 10 parts by weight, preferably 0.2 to 6 parts by weight, per 100 parts by weight of rubber.

The rubber containing hydrogenated NBR may include other fillers such as silica, calcium carbonate, talc, etc.
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, and the like may be appropriately blended.

According to the present invention, in order to improve the adhesiveness between the reinforcing rubber layer composed of the rubber containing hydrogenated NBR and the diene rubber layer of another adjacent part,
(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 (A) :( B) = 10: 90 to 90: 1.
It is preferably 0 in terms of adhesive strength. If it exceeds this range, the adhesive strength will decrease. Further, the thickness of the adhesive rubber layer is preferably 0.1 to 2.0 mm, more preferably 0.2 to 0.8 mm. This thickness is 0.1mm
If the thickness is thinner, processing is difficult, such as the occurrence of cuts in the adhesive rubber layer during production, and if it is thicker than 2.0 mm,
Although this does not cause any problem in normal running, it is not preferable because the adhesive rubber layer generates heat and breaks the adhesive layer during long running.

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.

Further, in addition to the aromatic petroleum resin (C), a compounding agent generally compounded in rubber, for example, carbon black,
Fillers such as silica and talc, antioxidants, plasticizers, processing aids, resins, adhesives, crosslinking aids, vulcanization accelerators, tackifiers and the like may be appropriately blended.

According to the present invention, as shown in FIG.
Tire bead portion 1 In the tire bead portion 1, a carcass edge portion 3a corresponding to an end of a folded portion 3a of the carcass 3 in which steel cords are arranged in a direction perpendicular to the tire circumferential direction, which is folded from the inside to the outside of the tire via the bead core 2. The reinforcing rubber layer 4 arranged outside (in the direction of the outer surface of the tire) is made of rubber containing hydrogenated NBR of the present invention.
Further, a specific adhesive rubber layer 5 is interposed between a rubber containing hydrogenated NBR constituting the reinforcing rubber layer 4 and a diene rubber of a part member adjacent to the reinforcing rubber layer 4 to thereby provide a rubber containing hydrogenated NBR. And the diene rubber are firmly adhered. The adhesive rubber layer 5 is made of the extruded reinforcing rubber layer 4.
Alternatively, the adhesive rubber sheet of the present invention may be bonded thereto, or the rubber of the reinforcing rubber layer 4 and the adhesive rubber may be simultaneously extruded.

[0020]

EXAMPLES The present invention will be further described with reference to the following examples, but it goes without saying that the scope of the present invention is not limited to these examples.

The test tires used in each of the following examples were manufactured as follows. Preparation of Test Tire An adhesive rubber layer having a composition of 0.8 mm in thickness and a reinforcing rubber layer having the composition shown in Table 2 below were prepared from the composition (rubber A to rubber F) shown in Table 1 below. As shown in FIG. 1, the adhesive rubber layer 5 laminated on both sides is disposed outside the bead portion on the carcass edge portion 3a 'of the folded portion 3a of the carcass 3 in the bead portion 1 of the heavy duty pneumatic tire. Test tire (size: 275 / 70R22.
5) was prepared and subjected to the following test. In addition, all the compounding amounts of Table 1 and Table 2 are represented by parts by weight.
Denotes a steel chafer, and 7 denotes an organic fiber reinforcing layer.

Carcass Edge Separation Resistance Each test tire was mounted on a rim having a rim size of 22.5 × 8.25, the air pressure was 900 kPa, and the drum diameter was 170.
Using a 7 mm indoor drum tester, the speed was set to 45 km / h, and 140% (4410
The vehicle traveled under a load of (kg), and the traveling distance until the carcass edge portion caused separation was determined.
The index was set as an index with the tire of (conventionally compounded) as 100. The larger the value, the better the carcass edge separation resistance.

[0023]

[Table 1]

NR: RSS # 3 NBR: Nipol DN401, Nippon Zeon Co., Ltd. Aromatic petroleum resin: FR-120, Fujikosan Co-crosslinking agent: TAIC, Nippon Kasei Co., Ltd. Organic peroxide (40% dilution): Parka Docks 14 /
40, Kayaku Akzo Co., Ltd. Sulfur: insoluble sulfur Vulcanization accelerator (CZ): Noxeller CZ-G, Ouchi Shinko Chemical Co., Ltd. Vulcanization accelerator (TOT-N): Noxeller TOT-N, Ouchi Shinko Chemical Co., Ltd.

[0025]

[Table 2]

NR: RSS # 3 HNBR (hydrogenated NBR): Zetpol 2020,
Nippon Zeon Co., Ltd., content of co-diene diene unit about 10% HAF carbon black: Seast 300, Tokai Carbon Co., Ltd. Zinc flower: 3 kinds of zinc oxide, Shodo Chemical Co., Ltd. Stearic acid: Beads stearic acid, Nippon Yushi Co., Ltd. Antioxidant 1: Nocrack 6C, Ouchi Shinko Chemical Co., Ltd. Antioxidant 2: Nocrack 224, Ouchi Shinko Chemical Co., Ltd. Antioxidant 3: Nowguard 445, Uniroyal Co., Ltd. Crosslinking agent: Parkadox 14/40, Kayaku Akzo Co., Ltd. Crosslinker: TAIC, Nippon Kasei Co. Sulfur: Cristex HSOT 20, Flexis Vulcanization accelerator: Noxeller DZ-G, Ouchi Shinko Chemical Industry

As shown in Table 2, Comparative Example 1 in which the reinforcing rubber layer was conventionally compounded and Comparative Example 2 in which the reinforcing rubber layer was a rubber containing hydrogenated NBR but was not provided with the adhesive rubber layer
In comparison, all of the tires of Examples 1 to 8 of the present invention obtained good results of carcass edge separation resistance.

[0028]

According to the present invention, a rubber containing a predetermined hydrogenated NBR is used as a reinforcing rubber in a pneumatic tire for heavy load, and a rubber between the rubber containing the hydrogenated NBR and a part made of another rubber adjacent thereto is used. By using a predetermined adhesive rubber layer for the adhesive layer, the occurrence of carcass edge separation of the pneumatic tire due to the carcass edge portion can be suppressed, and a tire having excellent durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view in the meridian direction of a tire bead portion in which a reinforcing rubber layer of a carcass edge portion of a heavy-duty pneumatic tire is formed of a predetermined rubber material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead part 2 Bead core 3 Carcass 3a Folding part 3a 'carcass edge part 4 Reinforcement rubber layer 5 Adhesive rubber layer 6 Steel chafer 7 Organic fiber reinforcement layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/098 C08K 5/098 C08L 9/00 C08L 9/00 9/02 9/02 57/00 57 / 00 F term (reference) 4J002 AC01W AC02W AC03W AC044 AC06W AC08X BA01Y EG016 EH076 EH146 EU196 FD144 FD146 GN01

Claims (5)

[Claims] 1. A heavy-duty pneumatic tire in which a carcass is folded back via a bead core, a reinforcing rubber layer disposed outside a carcass edge portion of a folded portion of the carcass has a co-projection diene unit content of 30% or less. A total of 100 parts by weight of the rubber containing a certain ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber is added with 0 to 1 zinc methacrylate.
20 parts by weight and 0 to 60 parts by weight of carbon black are blended, and the total amount of zinc methacrylate and carbon black is 10 to 120 parts by weight, and the rubber composition is adjacent to the rubber composition. (A) at least one diene rubber selected from natural rubber, polyisoprene rubber, polybutadiene rubber, conjugated diene-aromatic vinyl copolymer rubber, and (B) acrylonitrile-butadiene A rubber composition in which (C) 5-80 parts by weight of an aromatic petroleum resin having an average molecular weight of 300-1500, a softening point of 50-160 ° C., and an iodine adsorption amount of 20 g / 100 g or more is mixed with 100 parts by weight of the copolymer rubber. A heavy-duty pneumatic tire characterized by having an adhesive rubber layer disposed thereon. 2. The rubber for the reinforcing rubber layer is prepared by adding an ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber having a co-projection diene unit content of 30% or less to 100 parts by weight of the total amount of rubber. The heavy-duty pneumatic tire according to claim 1, wherein the pneumatic tire contains not less than part by weight. 3. The adhesive rubber layer has a thickness of 0.1 to 2.0.
The pneumatic tire for heavy load according to claim 1 or 2, wherein 4. The weight ratio (A) / (B) of the rubber (A) and the rubber (B) in the adhesive rubber layer is 90/10 to 10/9.
The heavy-duty pneumatic tire according to any one of claims 1 to 3, wherein the value is 0. 5. The adhesive rubber layer according to claim 1, wherein the methacrylic acid higher ester, triallyl isocyanurate, a metal salt of methacrylic acid or acrylic acid, diallyl phthalate,
The pneumatic tire for heavy load according to any one of claims 1 to 4, comprising at least one co-crosslinking agent selected from 1,2-polybutadiene, and crosslinking with an organic peroxide.