JP2000318409A - Pneumatic tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the occurrence of belt edge separation and to improve durabilityby constituting a belt edge cushion layer of specific hydrogenated NBR rubber and arranging an adhesive rubber layer blending specific aromatic petroleum resin, etc., between the layer and adjacent other member rubber. SOLUTION: A rubber rubber component (rubber including hydrogenated NBR) blending the 0-120 pts.wt. of metacrylic acid zinc and the 0-60 pts.wt. part of carbon black to the 100 pts.wt. of rubber including ethylene unsaturated nitryl-conjugate diene high saturated rubber with less than 30% content of a conjugate diene unit is used for a belt edge cushion layer 2 a total pts.wt. is a 10-120 pts.wt. Additionally, an adhesive layer blending a 5-80 pts.wt. of aromatic petroleum resin of average molecular weight of 300-1500, a softening point of 50-160 deg.C and iodine absorbing quantity of 20 g/100 g in a diene rubber and acrylonitrile-butadiene copolymer rubber 100 pts.wt. is arranged between the layer and adjacent other member 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 "), which relates to a heavy duty pneumatic tire used for a belt edge cushion layer of a tire.

[0002]

2. Description of the Related Art A belt layer of a heavy-duty pneumatic tire used for a conventional truck, bus or the like has a structure as shown in FIG. 1, and an end of the belt layer 4 is formed by extending the belt layer 4 and its extension. A discontinuity in rigidity occurs between the rubber and the upper rubber, and stress concentration tends to occur there. As a result, there is a problem that separation of the belt end occurs. Therefore, the same kind of rubber is arranged in a tape shape at the belt interlayer edge portion of the tire (belt edge cushion layer 2).
It is well known to improve the durability of the belt edge. However, particularly when the tire is recycled as a rectified tire, it is necessary to further extend the life of the tire, and further improvement in the durability of the belt edge portion has been demanded.

[0003]

Therefore, in the present invention,
An object of the present invention is to provide a heavy-duty pneumatic tire with excellent durability by eliminating the problem of the separation of the pneumatic tire caused by the end portion of the belt layer.

[0004]

According to the present invention, in a heavy duty pneumatic tire having at least two belt layers obtained by rubberizing an organic fiber cord or a steel cord, a belt layer at an end of the belt layer is provided. The zinc methacrylate is added to the belt edge cushion layer in an amount of 0 to 120 parts by weight based on 100 parts by weight of a rubber containing an ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber having a co-projection diene unit content of 30% or less. Parts by weight and carbon black are compounded in an amount of 0 to 60 parts by weight, and the total amount of zinc methacrylate and carbon black is 10 to 120 parts by weight (hereinafter referred to simply as "rubber containing hydrogenated NBR"). ), And (A) a natural rubber, a polyisoprene rubber, or a polybutene rubber between the rubber composition and an adjacent diene rubber. Diene rubber, conjugated diene - at least one diene rubber and selected from aromatic vinyl copolymer rubber (B) acrylonitrile - butadiene copolymer rubber per 100 parts by weight (C) Average molecular weight 300
~ 1500, softening point 50 ~ 160 ° C, iodine adsorption 20
g / 100 g or more of an aromatic petroleum resin in an amount of 5 to 80 parts by weight is provided with an adhesive rubber layer (hereinafter, simply referred to as "adhesive rubber layer") composed of a rubber composition. A tire is provided.

According to the present invention, the rubber of the belt edge cushion layer has a co-projection diene unit content of 30%.
% Of an ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber of not more than 40 parts by weight based on 100 parts by weight of the total amount of the rubber.

Further, according to the present invention, there is provided a pneumatic tire for heavy load, wherein the thickness of the adhesive rubber layer is 0.1 to 2.0 mm.

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 duty pneumatic tire is provided.

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

[0009]

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, an ethylenically unsaturated nitrile having a co-projection diene unit content of 30% or less is contained in a belt edge cushion layer disposed between belt layers at the end of the belt layer in a pneumatic tire. For 100 parts by weight of rubber containing conjugated diene-based highly saturated rubber (hydrogenated NBR),
A rubber composition (including hydrogenated NBR) containing 0 to 120 parts by weight of zinc methacrylate and 0 to 60 parts by weight of carbon black, and a total of 10 to 120 parts by weight of zinc methacrylate and carbon black. (A) between the belt edge cushion layer composed of the rubber containing the hydrogenated NBR and the adjacent other part composed of the diene rubber, At least one diene rubber selected from isoprene rubber, polybutadiene rubber, conjugated diene-aromatic vinyl copolymer rubber and (B) acrylonitrile-butadiene copolymer rubber (100 parts by weight), (C) average molecular weight of 300 to An aromatic petroleum resin having a 1500, a softening point of 50 to 160 ° C. and an iodine adsorption amount of 20 g / 100 g or more
An adhesive rubber layer (adhesive rubber layer) made of a rubber composition blended with a rubber composition containing up to 80 parts by weight, a belt edge cushion layer made of rubber containing hydrogenated NBR, and a part part made of diene rubber; Is characterized by being firmly bonded.

[0010] 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 material for the belt edge cushion layer, it is possible to eliminate the problem of tire separation caused by the end portion of the belt layer and improve the durability.

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 contain 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 belt edge cushion layer composed of the rubber containing hydrogenated NBR and the diene rubber layer of the adjacent part, (A) ) Natural rubber, polyisoprene rubber,
At least one diene rubber selected from polybutadiene rubber and conjugated diene-aromatic vinyl copolymer rubber is blended with (B) acrylonitrile-butadiene copolymer rubber, and a total of (A) + (B) 100 wt. Parts by weight (C) average molecular weight 300 to 1500, softening point 50 to 16
It is necessary to adhere via an adhesive rubber layer containing 5-80 parts by weight of an aromatic petroleum resin having an iodine adsorption amount of 20 g / 100 g or more at 0 ° C. (A) + (B) Total 1
If the amount of the aromatic petroleum resin (C) is less than 5 parts by weight relative to 00 parts by weight, the adhesive strength is reduced, and
Exceeding 80 parts by weight generates a large amount of heat, which in any case 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 blended with 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.
The belt edge cushion layer 2 disposed between the belt layers 4 at the ends of the belt layers 4 is made of rubber containing hydrogenated NBR.
In particular, it is preferable that the belt edge cushion layer 2 is inserted between the belt layers 4 whose cord angles cross each other. Further, a specific adhesive rubber layer 3 is formed between a rubber containing hydrogenated NBR constituting the belt edge cushion layer 2 and a diene rubber such as a belt coat rubber or a tread rubber of a part member adjacent to the belt edge cushion layer 2. By this, the rubber containing hydrogenated NBR and the diene rubber are firmly adhered to each other. The adhesive rubber layer 3 may be produced by bonding the adhesive rubber sheet of the present invention to the extruded belt edge cushion rubber layer 2 or extruding the belt edge cushion rubber and the adhesive rubber simultaneously.

As the belt layer 4, an organic fiber cord can be used in addition to the steel cord. Examples of the organic fiber cord include an aromatic polyamide fiber cord (aramid fiber cord), a nylon fiber cord, a polyester fiber cord, a polyarylate fiber cord, a polyvinyl alcohol fiber cord, a rayon fiber cord, and an acrylic fiber cord. it can.

[0022]

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 thickness of 0.8 mm and a belt edge cushion layer having a composition shown in Table 2 below was prepared from the composition (rubber A to rubber F) shown in Table 1 below. As shown in FIG. 1, a test tire (size: 275) in which the adhesive rubber layer 3 was laminated on both sides of the edge cushion layer 2 and disposed between the belt layers 4 at the end of the belt layer of the heavy duty pneumatic tire 1 as shown in FIG. /70R22.5) and submitted for the following test. In addition, all the compounding amounts of Table 1 and Table 2 are expressed in parts by weight. In FIG. 1, the belt layer No. 4 uses the No. 1 to No. 4 steel belt, and 6 indicates the carcass.

Belt 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
(kg) and the running distance was measured until the belt edge portion caused separation.
The index was set as an index with the tire of (conventionally compounded) as 100. The larger this value, the better the belt edge separation resistance.

[0025]

[Table 1]

NR: RSS # 3 NBR: Nipol DN401, Nippon Zeon Co., Ltd. Aromatic petroleum resin: FR-120, Fujikosan Co., Ltd. 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.

[0027]

[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 above, Comparative Example 1 in which the belt edge cushion layer was conventionally blended and Comparative Example 2 in which the belt edge cushion layer was a rubber containing hydrogenated NBR but was not provided with an adhesive rubber layer. In comparison, all of the tires of Examples 1 to 8 of the present invention obtained favorable results on the belt edge separation resistance.

[0030]

According to the present invention, a predetermined hydrogenated N is added to the belt edge cushion layer in the pneumatic tire for heavy load.
By using a rubber containing BR and using a predetermined adhesive rubber layer as an adhesive layer between the rubber containing hydrogenated NBR and a part made of another rubber adjacent thereto, pneumatic air caused by the belt layer end is obtained. The problem of belt edge separation of the tire can be eliminated, 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 in which a belt edge cushion layer of a heavy-duty pneumatic tire is formed of a predetermined rubber material.

[Explanation of symbols]

 1 Pneumatic tire for heavy load 2 Belt edge cushion layer 3 Adhesive rubber layer 4 Belt layer 5 Carcass layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 7/00 C08L 7/00 9/00 9/00 9/02 9/02 // (C08L 9/00 57:02) F term (reference) 4J002 AC01W AC03W AC06W AC07X AC08W AC111 BA013 DA037 EG046 FD017 FD206 GN01

Claims (5)

[Claims] 1. A heavy-duty pneumatic tire having at least two belt layers obtained by rubberizing an organic fiber cord or a steel cord, wherein a belt edge cushion layer disposed between the belt layers at an end of the belt layer is shared. Rubber 100 containing an ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber having a content of a diene unit of 30% or less
0 to 120 parts by weight of zinc methacrylate and 0 to 60 parts by weight of carbon black, and a total of 10 to 120 parts by weight of zinc methacrylate and carbon black. Make up, and
Between the rubber composition and the adjacent diene rubber,
(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 in 100 parts by weight in total (C) average molecular weight 300-1500, softening point 50-1
A pneumatic tire for heavy loads, comprising an adhesive rubber layer comprising a rubber composition containing 5-80 parts by weight of an aromatic petroleum resin having an iodine adsorption amount of 20 g / 100 g or more at 60 ° C. 2. The rubber of the belt edge cushion 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 pneumatic tire for heavy load according to claim 1, wherein the pneumatic tire contains at least 40 parts 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.