JP2007223350A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire preventing a heat separation failure by effectively suppressing/radiating heat of heat generation of a tread part (especially, a center part) when the tire is loaded. <P>SOLUTION: In the pneumatic tire, a number of rug grooves 22 are disposed on a tread part, and a narrow grooves 24 having the width of 20 mm or less is disposed in the width direction on a center part C between two tire circumferences by respectively connecting the end positions of these rug grooves substantially in the tire circumferential direction. A shallow groove 26 in the circumferential direction is provided on the center part along the tire circumferential direction, a negative ratio is not larger than 8% except the shallow grooves 26 in the circumferential direction in the area of 25% of the tread width with the equator CL as its center, and a rubber composition composed by blending the compound having a part Q containing dipolar nitrogen and 4 to 6 nitrogen containing heterocyclic parts B containing oxygen or sulfur by 0.1 to 30 pts.mass with respect to 100 pts.mass of at least one kind of rubber component selected from the group composed of natural rubber and synthetic rubber, is used as a tire member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire. More specifically, the present invention relates to a pneumatic tire suitable for a demanding pneumatic tire for a construction vehicle by improving heat generation in a tire tread and improving wear resistance.

  Conventionally, in a construction vehicle tire having a so-called lug pattern in which a large number of lug grooves are arranged at predetermined intervals, in order to improve the wear resistance, a tread rubber having good wear resistance is used and a tread volume is reduced. It is common to use means such as increasing the tread pattern (deepening the groove), decreasing the negative rate, and increasing the land rigidity.

  However, when the wear resistance is improved by using the above-mentioned means, in particular, there is a tendency to cause deterioration of the heat generation of the tread portion at the time of tire rolling, and this deterioration of heat generation is caused by the heat of the tread portion. This could cause a failure such as separation. Accordingly, a tread rubber / base rubber having good heat generation while maintaining wear resistance is required. However, heat generation and wear resistance are contradictory, and there is a limit in meeting the needs of users to a high degree.

In particular, the land portions of the two tire circumferences formed by tying the end positions of the lug grooves substantially in the tire circumferential direction have a small heat radiation area, so the heat generation temperature tends to increase.
For this reason, in recent years, a technology has been developed in which a narrow groove having a width of 20 mm or less is arranged in the land portion in order to minimize the decrease in tread volume, minimize the decrease in land portion rigidity, and increase the heat radiation area. (For example, see Patent Documents 1 and 2).

However, recently, due to the progress of tire size increase, flattening, and heavy load accompanying the increase in size of construction vehicles, the exothermic deterioration of the tread portion tends to become remarkable. It is still important to suppress the heat generation.
JP-A-2001-213120 (Claims, Examples, etc.) JP 2000-233610 A (Claims, Examples, etc.)

  In view of the above-described conventional problems, the present invention improves the heat dissipation of the tire center part, improves the heat generation in the tire tread, and improves the wear resistance. An object of the present invention is to provide a pneumatic tire suitable for the above.

  As a result of intensive studies to solve the above-described conventional problems, the present inventors have arranged a number of lug grooves extending from the respective tread ends toward the tire equatorial plane in the tread portion. A narrow groove having a width of 20 mm or less is arranged in the width direction at the center portion between two tire circumferences formed by connecting the end positions of the grooves substantially in the tire circumferential direction, and a depth of 70 mm or more. In the pneumatic tire having a main groove, it is found that the above-described pneumatic tire can be obtained by making the structure of the tire center part a specific structure and using a specific rubber composition for the tire member. Has been completed.

That is, the present invention resides in the following (1) to (8).
(1) A large number of lug grooves extending from the respective tread ends toward the tire equatorial plane are disposed in the tread portion, and the terminal positions of these lug grooves are substantially connected in the tire circumferential direction 2. In a pneumatic tire in which a narrow groove having a width of 20 mm or less is arranged in the width direction in the center portion between the tire circumferences, a shallow circumferential groove extending along the tire circumferential direction is provided in the center portion, and the equator is centered. 100 parts by mass of at least one rubber component selected from the group consisting of natural rubber and synthetic rubber and having a negative rate of 8% or less excluding circumferential shallow grooves in the region of 25% of the tread width A rubber composition formed by blending 0.1 to 30 parts by mass of a compound having a part Q containing dipolar nitrogen and a compound having 4 to 6 nitrogen-containing heterocyclic parts B containing oxygen or sulfur. A pneumatic tire characterized by being used as a member.
(2) The dipolar nitrogen portion is selected from at least one of A1-C (A2) = N (A3) → O, A1-C≡N → O, and A1-C≡N → N-A4. A1 to A4 may be different from each other, hydrogen or a group having 20 or less carbon atoms or a linking chain connecting the B, and the compound is bonded to at least one of A1 to A4 and the B is connected. The pneumatic tire according to (1) above.
(3) A1 to A4 of the above compound are hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms (however, the aromatic ring has a nitro group) , A cyano group, a chloro group, a bromo group, an acyl group, a carbonylalkyl group, an alkyl group, and an alkoxyl group), or a connecting chain (2) The described pneumatic tire.
(4) The pneumatic tire according to (1), wherein the nitrogen-containing heterocycle of the B part is oxazoline or thiazoline.
(5) The above compound is 4- (2-oxazolyl) -phenyl-N-methyl-nitrone, 4- (2-thiazolyl) -phenyl-N-methyl-nitrone, 4- (2-oxazolyl) -phenyl- N-phenyl-nitrone, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrone, phenyl-N-4- (2-oxazolyl) -phenyl-nitrone, phenyl-N-4- (2-thiazolyl)- Phenyl-nitrone, 4-tolyl-N-4- (2-oxazolyl) -phenyl-nitrone, 4-tolyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4-methoxyphenyl-N-4- ( 2-Oxazolyl) -phenyl-nitrone, 4-methoxyphenyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4- (2-oxazolyl) -phenyl-nitrile Xoxide, 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-methyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-methyl-nitrileimine, 4 -(2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-phenyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrileimine, phenyl-N- The pneumatic tire according to (4) above, comprising at least one of 4- (2-oxazolyl) -phenyl-nitrileimine and phenyl-N-4- (2-thiazolyl) -phenyl-nitrileimine.
(6) The pneumatic tire according to any one of (1) to (5), wherein a groove depth of the circumferential shallow groove is 25% or less of the lug groove depth.
(7) The pneumatic tire according to any one of (1) to (6), wherein a groove width of the circumferential shallow groove is not less than 30 mm and not more than 50 mm.
(8) The pneumatic tire described in any one of (1) to (7) above, wherein the pneumatic tire is a pneumatic tire for construction vehicles.
In the present invention, the “tread end” means that a pneumatic tire is mounted on a standard rim defined in JATMA YEAR BOOK (2002 edition, Japan Automobile Association Standard), and is applied in JATMA YEAR BOOK. Fills 100% of the air pressure (maximum air pressure) with respect to the maximum load capacity (internal pressure-load capacity correspondence table) as the internal pressure, and indicates the outermost contact portion in the tire width direction when the maximum load capacity is applied. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the heat dissipation of a tire center part, the heat_generation | fever property in a tire tread can be improved further, and abrasion resistance can further be improved, The tread part (especially center part) at the time of tire load ) Is effectively suppressed and dissipated to prevent heat separation failure, and in particular, a pneumatic tire for construction vehicles is provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2 show a pneumatic tire for construction vehicles showing a first embodiment of the present invention. FIG. 1 is a sectional view in the tire radial direction, and FIGS. 2 (A) and 2 (B) are respectively. It is the top view which shows a tread part, and tire radial direction sectional drawing.
As shown in FIGS. 1 and 2, the pneumatic tire 10 for a construction vehicle according to the first embodiment of the present invention includes a carcass 12 whose both ends are folded back by bead cores 11. The carcass 12 is composed of one layer or a plurality of layers.

  A belt layer 14 in which a plurality of belt plies are stacked is embedded on the outer side in the tire radial direction of the crown portion 12 </ b> C of the carcass 12. A tread portion 18 having grooves is formed on the outer side of the belt layer 14 in the tire radial direction.

In the present embodiment, as a tread rubber / base rubber of the tread portion 18, a part Q containing dipolar nitrogen with respect to 100 parts by mass of at least one rubber component selected from the group consisting of natural rubber and synthetic rubber, and It is comprised from the rubber composition formed by mix | blending 0.1-30 mass parts of compounds which have 4-6 nitrogen-containing heterocyclic part B containing oxygen or sulfur.
Examples of the rubber component to be used include at least one selected from the group consisting of natural rubber and synthetic rubber. As a synthetic rubber, it can select suitably from well-known things according to the objective. Conjugated rubber is particularly preferable, and it is preferable to appropriately select at least one from styrene-butadiene copolymer (SBR), polyisoprene (IR), polybutadiene (BR), acrylonitrile-butadiene rubber, chloroprene rubber, and butyl rubber. . Particularly preferably, the wear resistance can be further improved by selecting SBR. Further, the total amount of the synthetic rubber is desirably included in the range of 30 to 100% by mass including the modified conjugated diene polymer.

In the present embodiment, in the rubber composition used for the tread portion 18, carbon black and / or silica or the like is blended with the rubber component. These are preferably blended in the range of 30 to 70 parts by mass with respect to 100 parts by mass of the rubber component. When the amount of carbon black and white carbon decreases, the elastic modulus tends to decrease. Further, when the amount of carbon or the like increases, the low heat build-up of the vulcanized rubber composition tends to deteriorate.
As carbon black that can be used, those usually used in the rubber industry can be used. For example, various grades of carbon black such as SAF, HAF, ISAF, FEF, and GPF can be used alone or in admixture of two or more.
Preferably, those in terms of further improvement of the effect of the present invention, the nitrogen adsorption specific surface area _(N 2 SA) of carbon black is 30 to 200 m ² / g or DBP oil absorption amount of 60~200 ^(cm 3 / 100g) Is desirable.

  The compounding amount of the carbon black is preferably 20 to 100 parts by mass, particularly 20 to 80 parts by mass with respect to 100 parts by mass of the rubber component. If the amount of carbon black is less than 20 parts by mass, the exothermic property is excellent, but the wear resistance may be significantly impaired. On the other hand, if it exceeds 100 parts by mass, the workability may be deteriorated.

Moreover, it is preferable to mix | blend a silica as a filler in a rubber composition. As silica to be used, those having a nitrogen adsorption specific surface area (N ₂ SA) of 180 to 270 m ² / g are desirable from the viewpoint of further improving the chipping property improvement by the hysteresis loss improvement. If N ₂ SA exceeds 270 m ² / g, the factory workability deteriorates, which is not preferable.
It is preferable to mix | blend 1-40 mass parts with respect to 100 mass parts of rubber components from the point of the further ensuring ensuring dispersion | distribution, and it is preferable that it is the range of 3-30 mass parts especially.

In the present invention, the rubber composition used for the tread portion 18 has a part Q containing dipolar nitrogen and 4 to 6 nitrogen-containing heterocyclic parts B containing oxygen or sulfur with respect to 100 parts by mass of the rubber component. It is necessary to blend 0.1 to 30 parts by mass of the compound. Preferably, 0.3 to 5 parts by mass is blended.
The compound used is included in the compound of the present invention as long as it contains a dipolar nitrogen moiety. Specific examples of particularly preferred dipolar nitrogen moieties include A1-C (A2) = N (A3) → O (nitrone system), A1-C≡N → O (nitrile oxide system), and A1-C≡. N → N-A4 (nitrile imine type) can be mentioned. These dipolar nitrogen portions Q are reactively bonded to double bond portions in a polymer such as a rubber component as shown in the following reaction formulas (1) to (3).

The groups A1 to A4 in the nitrone-based, nitrile oxide-based, and nitrileimine-based dipolar nitrogen portions Q are preferably hydrogen, a group having 20 or less carbon atoms, or a connecting chain. When the number of carbon atoms exceeds 20, the molecular weight of the compound itself increases, and the reactivity with the rubber component becomes worse.
Since the said compound has B part, A1-A4 can become a connecting chain which connects B part. However, in the case of A1 to A3, in the case of only A1, or in the case of A1 and A4, at least one or more are connected to the B portion, and a plurality of B portions may exist. A1 to A4 may be different or the same.

  As specific groups or connecting chains of A1 to A4 of the above compound, specifically, hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms ( However, the aromatic ring may have a nitro group, a cyano group, a chloro group, a bromo group, an acyl group, a carbonylalkyl group, an alkyl group, and an alkoxyl group). Or a linking chain. The alkyl group, acyl group, carbonylalkyl group, and alkoxyl group may have a branched chain or a cyclo ring. A1 to A4 may be different from each other.

The B portion of the above compound consists of a nitrogen-containing heterocycle having oxygen or sulfur such as oxetine, thiozetin, oxazoline, thiazoline, tetrahydrooxazine and tetrahydrothioxazine. In particular, it consists of a 4- to 6-membered nitrogen-containing heterocyclic ring represented by the following structural formulas (I) to (III) (X in the table is oxygen: O or sulfur: S). Of these, oxazoline and thiozoline of the structural formula (II) are preferable. In each structural formula, R1 to R7 are hydrogen, a group having 20 or less carbon atoms, or a connecting chain. Moreover, in each structural formula similarly to the case of A1 to A4, in the case of R1 to R3, in the case of R1 to R5, or in the case of R1 to R7, at least one or more of A1 to A4 connected to Q Equivalent to.
As described above, the B portion undergoes a binding reaction of the following reaction formulas (4) to (15), and carbon black and white carbon (silica) can be uniformly incorporated into the rubber component polymer.

  Specific examples of the above compounds include 4- (2-oxazolyl) -phenyl-N-methyl-nitrone, 4- (2-thiazolyl) -phenyl-N-methyl-nitrone, and 4- (2-oxazolyl). -Phenyl-N-phenyl-nitrone, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrone, phenyl-N-4- (2-oxazolyl) -phenyl-nitrone, phenyl-N-4- (2- Thiazolyl) -phenyl-nitrone, 4-tolyl-N-4- (2-oxazolyl) -phenyl-nitrone, 4-tolyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4-methoxyphenyl-N- 4- (2-oxazolyl) -phenyl-nitrone, 4-methoxyphenyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4- (2-oxazolyl) -fe Ru-nitrile oxide, 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-methyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-methyl-nitrile Imine, 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-phenyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrileimine, phenyl -N-4- (2-oxazolyl) -phenyl-nitrileimine, phenyl-N-4- (2-thiazolyl) -phenyl-nitrileimine and the like can be mentioned.

  In such a compound, for example, 4- (2-oxazolyl) -phenyl-N-methyl-nitrone [hereinafter referred to as “4OPMN”. See formula (IV) below] and 4- (2-oxazolyl) -phenyl-N-phenyl-nitrone [hereinafter referred to as “4OPPN”. The following formula (V) can be specifically mentioned.

The method for producing the above compound can be produced without undue experimentation. For example, with respect to 4OPMN and 4OPPN, the manufacturing method can be shown in the examples described later.
Also, other compounds can be produced by typical production methods by appropriately selecting other starting materials and intermediate materials.
Said compound is contained in 0.1-30 mass parts with respect to 100 mass parts of rubber components. In particular, it is preferable to contain in 0.1-5 mass parts. If the compounding amount of the compound is less than 0.1 parts by mass, the effects of low heat generation and low hysteresis loss are not sufficient. When the compounding amount of the compound exceeds 30 parts by mass, the cost increases significantly, which is not preferable.

  Furthermore, the rubber composition to be used can contain various components usually used in the rubber industry, as long as the object of the present invention is not impaired. For example, as various components, fillers (for example, inorganic fillers such as calcium carbonate and calcium carbonate); vulcanization accelerators; anti-aging agents; zinc oxide; stearic acid; softeners; An agent can be mentioned. As vulcanization accelerators, thiazole vulcanization accelerators such as MBTS (dibenzothiazyl disulfide) and CZ (N-cyclohexyl-2-benzothiazylsulfenamide); thiurams such as TT (tetramethylthiuram sulfide) And guanidine-based vulcanization accelerators such as DPG (diphenylguanidine).

In the pneumatic tire 10 of the present embodiment, first, the rubber composition having the above-described configuration is used as the rubber of the tread portion 18 to improve the wear resistance, uneven wear resistance, and low hysteresis loss, and the tire is remarkably made. It can be improved. In addition to this, when the above compound is added, the reaction of the above reaction formulas (1) to (3) occurs between the double bond portion (P) in the rubber component and the Q portion of the compound. Furthermore, the reaction of carbon black (CB) or silica and the compound B part occurs in the above reaction formulas (4) to (15).
Due to the action of such a compound, carbon black and silica are sufficiently diffused in the rubber composition. As a result, in addition to wear resistance, the low heat buildup and low hysteresis loss of the tread rubber are further improved, and the use performance as a pneumatic tire for construction vehicles is further enhanced.
Furthermore, in the pneumatic tire 10 of the present embodiment, heat dissipation is enhanced by forming a tread portion 18 provided with a groove having a specific structure described in detail below on the outer side in the tire radial direction of the belt layer 14. Will be able to.

That is, as shown in FIG. 2, a plurality of lug grooves 22, 22... Are arranged in the tread shoulder regions on both sides in the tire width direction.
In addition, in the tire center portion C between the two tire circumferences (indicated by reference numerals 15 and 15) formed by tying the end positions of the lug grooves 22, 22. A plurality of widthwise narrow grooves 24, 24... That are substantially along the tire width direction are arranged. The width direction narrow groove 24 has an inner end in the tire width direction that terminates in the tread (inner side in the tire width direction than the tread end T), and an outer end in the tire width direction is connected to the tip of the lug groove 22. Is formed. The outer end of each lug groove 22 in the tire width direction extends beyond the tread end T so as to allow drainage to the outer side in the tire width direction.

  Further, an equatorial upper shallow groove 26 extending in the tire circumferential direction on the tire equator CL is disposed. The width GW and depth d of the equatorial upper shallow groove 26 are set to a width and a depth so that the heat generation at the tire center portion C can be sufficiently suppressed from when the tire is new to when the tread portion 18 generates significant heat until the initial use of the tire. Has been.

In this construction vehicle pneumatic tire 10, an equatorial upper shallow groove 26 extending in the tire circumferential direction on the tire equator CL is disposed, whereby the compressive stress acting on the tire center portion C can be relieved, In addition, the heat dissipation area can be increased. Therefore, it is possible to obtain the construction vehicle pneumatic tire 10 that effectively suppresses the temperature rise of the tread portion 18 when the tire is loaded and suppresses the occurrence of tire failure such as heat separation.
Further, the plurality of width direction narrow grooves 24 disposed in the tire center portion C have tire width direction inner ends terminating in the tread. Thereby, it can be set as the tire excellent in the traction performance which improved abrasion resistance by suppressing the fall of land part rigidity. In addition, heat dissipation can be improved even if the number of the width-direction narrow grooves 24 is increased, or the heat dissipation can be improved by disposing the width-direction narrow grooves 24 at positions where the temperature is the highest away from the lug grooves 22. Can do.

  Further, the width (SW) of the width direction narrow groove 24 is set to 20 mm or less, preferably within a range of 4 to 20 mm, and the groove depth (SW-d) of the width direction narrow groove 24 is equal to that of the lug groove 22. It is in the range of 50 to 95% of the groove depth (D). As a result, the effect of improving the heat dissipation is sufficiently exhibited, and it is avoided that the block rigidity of the tire center portion C becomes too low. If the width (SW) of the width direction narrow groove 24 exceeds 20 mm, the block rigidity of the tire center portion becomes low, and the problem of uneven wear and tread chipping is likely to occur. The effect of enhancing the properties is not sufficiently exhibited. Further, if the groove depth (SW-d) of the width direction narrow groove 24 is less than 50% of the groove depth (D) of the lug groove 22, a sufficient heat dissipation effect cannot be obtained, while 95% is reduced. If it exceeds, the block rigidity of the tire center portion becomes low, and problems of uneven wear and tread chipping are likely to occur.

  Furthermore, the groove width (GW) of the equatorial upper shallow groove 26 is preferably in the range of 30 to 50 mm. As a result, the effect of alleviating the compressive stress acting on the tire center portion C at the time of tire load rolling is further sufficiently exerted, and it is avoided that the contact area of the tire center portion C is excessively reduced to cause a belt end failure. Has been. In addition, if this groove width (GW) is less than 30 mm, the effect of relaxing the compressive stress acting on the center portion at the time of tire load rolling tends to be insufficient, while the groove width (GW) ) Exceeds 50 mm, the contact area of the center portion is excessively generated, and the contact pressure increases in the tread side area, and the belt end failure tends to occur.

  Further, the groove depth (d) of the equatorial upper shallow groove 26 is preferably 25% or less, more preferably 10 to 25% of the groove depth (D) of the lug groove 22. As a result, a sufficient heat dissipation effect can be obtained, and deterioration of wear resistance due to a decrease in tread volume is sufficiently avoided. In addition, if the circumferential shallow groove 24 is larger than 25% of the depth of the lug groove 22, the decrease in the tread volume cannot be ignored, and the wear resistance may be deteriorated.

  Further, in the region of 25% of the tread width around the tire equator CL, the negative rate in the region excluding the equator upper shallow groove 26 is 8% or less, preferably in the range of 2 to 8%. Has been. By setting the negative rate to 8% or less, it is possible to efficiently reduce heat generation without reducing the wear resistance of the tire center portion C. The tread width is the distance between the tread ends T on both sides in the tire width direction.

In the pneumatic tire 10 for construction vehicles according to the first embodiment configured as described above, 1) at least one rubber component 100 selected from the group consisting of natural rubber and synthetic rubber as a tire tread rubber base rubber member. A rubber composition comprising 0.1 to 30 parts by mass of a compound having a part Q containing dipolar nitrogen and 4 to 6 nitrogen-containing heterocyclic parts B containing oxygen or sulfur is used with respect to parts by mass. 2) In the tire tread portion, the center portion is provided with a circumferential shallow groove extending along the tire circumferential direction, and the negative rate except for the circumferential shallow groove in the region of 25% of the tread width centered on the equator. Is set to 8% or less, that is, by the configuration of 1) above, the heat dissipation of the tire center portion is enhanced, and the configuration of the above 2) The heat resistance at the tread part (especially at the center part) can be effectively suppressed and radiated to prevent heat separation failure. A pneumatic tire, particularly a pneumatic tire for construction vehicles, can be obtained.
In particular, if the flatness of the tire is 90% or less, the belt tension burden becomes larger than the general 95 series of OR tires (pneumatic tires for construction vehicles), and the heat generation in the tread portion becomes larger. Entered tires are more effective. Further, if the coefficient corresponding to the maximum speed of the tire load / load capability correspondence table defined in TRA is 1.4 or more, the load on the tire air volume is increased and the heat generation in the tread portion is further increased. Therefore, the pneumatic tire of the present invention is more effective. The rubber composition having the above configuration is used for tire members, and is particularly preferably applied to tread rubber and base rubber. The pneumatic tire can use air or an inert gas such as nitrogen as the gas to be filled.

  Below, the pneumatic tire for construction vehicles which becomes other embodiment of this invention is explained in full detail, referring drawings further. In the following embodiments, the tire tread rubber / base rubber member uses the same rubber composition as that of the first embodiment, and the tread portion 18 has a different groove shape and structure. is there. The same configurations as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The effects of the following embodiments are further added to the effects of the first embodiment.

(Second Embodiment)
FIG. 3 is a plan view showing a tread portion of a pneumatic tire for construction vehicles showing a second embodiment of the present invention.
In the pneumatic tire for construction vehicles of the second embodiment, the width direction narrow grooves 27 are formed between the lug grooves 22 as shown in FIG. 3 instead of the width direction narrow grooves 24 as compared to the first embodiment. ing.
The width direction narrow groove 27 is disposed in the tire center portion C substantially along the tire width direction. The width-direction narrow groove 27 straddles the equator shallow shallow groove 26, and both ends are connected to the terminal end of the lug groove 22.
In the pneumatic tire for construction vehicles of the second embodiment, since the rubber composition described above is used, the heat generation in the tire tread can be further improved, and the wear resistance can be further improved. And since it becomes the structure which connected the width direction narrow groove and the lug groove like 1st Embodiment, it can be set as the pneumatic tire for construction vehicles which can improve the heat dissipation of a tire center part further.

(Third embodiment)
FIG. 4 is a plan view showing a tread portion of a pneumatic tire for construction vehicles showing a third embodiment of the present invention.
The pneumatic tire for a construction vehicle according to the third embodiment has a widthwise narrow groove 34 formed in the tread portion as shown in FIG. 4 instead of the widthwise narrow groove 24 as compared with the first embodiment. .
The width direction narrow groove 34 is disposed substantially along the tire width direction in the tire center portion C. The width-direction narrow groove 34 straddles the equatorial upper shallow groove 26, ends at both ends in the tread, and is not connected to the lug groove 22.
In the pneumatic tire 28 for construction vehicles according to the third embodiment, since the rubber composition described above is used, the heat generation in the tire tread can be further improved, and the wear resistance can be further improved. If the width direction narrow groove and the lug groove are connected as in the first embodiment, the deformation differs depending on the traction force between the width direction narrow groove and the lug groove, and cracks occur due to stress concentration at the connection site. It can be a pneumatic tire for construction vehicles that is very effective for users who require a large traction force.

(Fourth embodiment)
FIG. 5 is a plan view showing a tread portion of a pneumatic tire for construction vehicles showing a fourth embodiment of the present invention.
As shown in FIG. 5, the pneumatic tire for construction vehicles according to the fourth embodiment is a tire along two straight lines connecting the end positions of the lug grooves 22 in the tire circumferential direction, as shown in FIG. A non-equatorial upper narrow groove 46 extending in the circumferential direction is further arranged. The groove depth of the non-equatorial upper narrow groove 46 is in the range of 10 to 25% of the groove depth of the lug groove. Both ends of the width direction narrow groove 34 are connected to the non-equatorial upper narrow groove 46.
In the pneumatic tire for construction vehicles according to the fourth embodiment, since the rubber composition described above is used, the heat generation in the tire tread can be further improved, and the wear resistance can be further improved. , Side slip can be ensured and the rigidity in the width direction can be prevented by the narrow groove.

(Fifth embodiment)
FIG. 6 is a plan view showing a tread portion of a pneumatic tire for construction vehicles showing a fifth embodiment of the present invention.
As shown in FIG. 6, the pneumatic tire for construction vehicles according to the fifth embodiment has a hand in which the non-equatorial upper narrow groove 46 is disposed, as in the third embodiment. An equatorial upper shallow groove 26 is also disposed.
In the present embodiment, the lug groove 52 is different in shape from the lug groove 22 of the third embodiment, and the groove width of the lug groove 52 becomes narrower as it approaches the non-equatorial upper narrow groove 46. The end of the lug groove 52 is connected to the non-equatorial upper narrow groove 46.
Further, a width direction narrow groove 54 is formed in the tire center portion C in place of the width direction narrow groove 34 described in the fourth embodiment. Both ends of the width direction narrow groove 54 are connected to the non-equatorial upper narrow groove 46. Further, the width direction narrow groove 54 is formed in a curved groove whose inclination angle with respect to the tire width direction gradually decreases as the non-equatorial upper narrow groove 46 is approached.
Further, between the lug grooves 52 adjacent to each other in the tire circumferential direction, a second width direction narrow groove 56 in which the inner end in the tire width direction is connected to the non-equatorial upper narrow groove 46 is formed.
In the pneumatic tire for construction vehicles according to the fifth embodiment, since the above rubber composition is used, the heat generation in the tire tread can be further improved, and the wear resistance can be further improved. Further, the narrow groove can suppress the decrease in the block rigidity to the minimum, and can ensure the skid resistance and the traction resistance slip.

(Sixth embodiment)
FIG. 7 is a plan view showing a tread portion of a pneumatic tire for construction vehicles showing a sixth embodiment of the present invention.
In the pneumatic tire for construction vehicles according to the sixth embodiment, as shown in FIG. 7, a non-equatorial upper narrow groove 66 extending in the tire circumferential direction is used instead of the non-equatorial upper narrow groove 46 as compared with the fourth embodiment. Is formed. An equatorial upper shallow groove 26 is also disposed.
The lug groove 62 is different in shape from the lug groove 22 of the fourth embodiment, and the groove width is narrow near the non-equatorial upper narrow groove 46. The end of the lug groove 62 is connected to the non-equatorial upper narrow groove 46.
Further, a width direction narrow groove 64 is formed in the tire center portion C in place of the width direction narrow groove 34 described in the fifth embodiment. Both ends of the width direction narrow groove 64 are located closer to the tire equator CL side than the inner end of the lug groove 62 in the tire width direction, and therefore the non-equatorial upper narrow groove 66 extends in a zigzag shape in the tire circumferential direction. . The term “zigzag extending in the tire circumferential direction” means that the groove portions that are inclined with respect to the tire circumferential direction extend in the tire circumferential direction while turning back so that the inclination directions are alternate.
In the pneumatic tire for construction vehicles according to the sixth embodiment, since the rubber composition described above is used, the heat generation in the tire tread can be further improved, and the wear resistance can be further improved. Since the surface area is increased by the narrow grooves extending in a zigzag shape, the temperature of the entire tread can be reduced. This is effective for users who use tires at high speeds.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by the following Example.

[Examples 1-4 and Comparative Examples 1-4]
In order to further confirm the invention of the present invention, tire members serving as a tire tread portion and a base portion were prepared according to the composition shown in Table 1 below. In addition, 4OPPN shown in the following Table 1; (4- (2-oxazolyl) -phenyl-N-phenylnitrone), 4OPMN; (4- (2-oxazolyl) -phenyl-N-methylnitrone)] Obtained by the method.

Using this tire member, a pneumatic radial tire (tire size 40.00R57) having the tread condition (groove structure, conforming to FIG. 2) shown in Table 2 below was produced. About each obtained pneumatic radial tire, after incorporating in a TRA regular rim, the heat generation performance (INDEX) and abrasion resistance (INDEX) were evaluated based on each test method below by using a regular load and a regular internal pressure.
Here, “regular rim” refers to a standard rim in the applicable size specified in the 2004 version of YEAR BOOK issued by JATMA, and “normal load” and “regular internal pressure” are similarly issued by JATMA. It refers to the maximum load and the air pressure for the maximum load in the applicable size / ply rating defined in the 2004 YEAR BOOK. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

<Manufacture of 4OPPN>
To a solution obtained by stirring and mixing 15.0 g of 4-formyl-benzoyl chloride (1 equivalent) in 300 ml of chloroform, a solution obtained by adding 10.9 g of 2-aminoethanol (2 equivalents) to 200 ml of chloroform was added dropwise at −10 ° C. And added. After the solution was placed at 25 ° C. for 2 hours, the white precipitate was removed by filtration. The filtrate was dried by a rotary evaporator to obtain 17.4 g of 4-formyl-N- (2-hydroxyethyl) -benzamide as a yellow liquid.
To 50 ml of concentrated sulfuric acid, 17.4 g of 4-formyl-N- (2-hydroxyethyl) -benzamide was added dropwise with stirring, and the mixture was heated at 100 ° C. for 1 hour. To this solution, 500 ml of 20% sodium hydroxide and chloroform were added dropwise with stirring and mixing, and the temperature was maintained at 15 ° C. or lower. The product layer was separated and dried to give 6.3 g of 4- (2-oxazolyl) -benzaldehyde.
A mixture of 4- (2-oxazolyl) -benzaldehyde (1 eq, 6.3 g) and N-phenyl-hydroxyamine (1 eq, 3.9 g) was refluxed in 100 ml ethanol for 30 min to a volume of 50 ml. Concentrated. The same amount of 50 ml of water was added and the mixture was cooled to 5 ° C. overnight in a refrigerator. Filtration separation and drying gave white crystals, yielding 6.7 g of 4- (2-oxazolyl) -phenyl-N-phenylnitrone.

<Manufacturing of 4OPMN>
To a solution obtained by stirring and mixing 4-formyl-benzoyl chloride (15.0 g, 89 mmol) in 300 ml of chloroform, a solution obtained by adding 2-aminoethanol (10.9 g, 178 mmol) to 200 ml of chloroform was added dropwise at −10 ° C. added. After the solution was placed at 25 ° C. for 2 hours, the white precipitate was removed by filtration. The filtrate was dried by a rotary evaporator to obtain 17 g (88 mmol) of yellow liquid 4-formyl-N- (2-hydroxyethyl) -benzamide.
4-Formyl-N- (2-hydroxyethyl) -benzamide (17 g, 88 mmol) was added dropwise to 50 ml of concentrated sulfuric acid with stirring, and the mixture was heated at 100 ° C. for 1 hour. To this solution, 500 ml each of 20% sodium hydroxide solution and chloroform were mixed and added dropwise with stirring, and the temperature was maintained at 15 ° C. or lower. The product layer was separated and dried to give 6.3 g (36 mmol) of 4- (2-oxazolyl) -benzaldehyde (41% yield).
A mixture of 4- (2-oxazolyl) -benzaldehyde (1 eq, 6.3 g) and N-methyl-hydroxyamine (1.7 g, 36 mmol) was refluxed in 100 ml of ethanol for 30 minutes and concentrated to a volume of 50 ml. did. The same amount of 50 ml of water was added and the mixture was cooled to 5 ° C. overnight in a refrigerator. White crystals were obtained by filtration and drying, yielding 5.1 g of 4- (2-oxazolyl) -phenyl-N-methylnitrone (69% yield).

Evaluation method of heat generation performance (INDEX) A drum system with a speed and step load condition of 10 km / h was implemented, the temperature at a position at a constant depth of the tread was measured, and Comparative Example 1 was used as a control value (control) 100. Examples were expressed as indices. It shows that it is excellent in low exothermic property, so that the value of an index | exponent is large.

Wear resistance (INDEX) evaluation method Attached to the front wheel of a 190-ton dump truck, traveled at a constant speed of 10 km / h for 100 hours, and then measured the remaining grooves at each position where the tread was divided into 8 in the width direction. The average value of the gauge required for the calculation was calculated as the amount of wear. Then, when performing the performance evaluation, the evaluation in Comparative Example 1 was set as an index 100, and an index that was a relative evaluation was calculated for the tires of other Comparative Examples and Examples. The calculation results are shown in Table 2 below. The larger this index (wear resistance index), the higher the performance.

  As is apparent from the results of Tables 1 and 2, Examples 1 to 4 within the scope of the present invention are excellent in low heat generation and wear resistance as compared with Comparative Examples 1 to 4 outside the scope of the present invention. As a result, it was found that a pneumatic tire for a construction vehicle in which heat separation failure is prevented can be obtained by effectively suppressing and dissipating heat generated in the tread portion (particularly the center portion) when the tire is loaded.

  Since the pneumatic tire of the present invention is excellent in heat dissipation, low heat generation and wear resistance, it can be suitably used for construction vehicle tires, and thus has high industrial utility value.

BRIEF DESCRIPTION OF THE DRAWINGS The pneumatic tire for construction vehicles which shows 1st Embodiment of this invention is shown, and it is a tire radial direction sectional drawing. (A) And (B) is the top view and tire radial direction sectional drawing which respectively show the tread part of the pneumatic tire for construction vehicles of 1st Embodiment. It is a top view which shows the tread part of the pneumatic tire for construction vehicles of 2nd Embodiment. It is a top view which shows the tread part of the pneumatic tire for construction vehicles of 3rd Embodiment. It is a top view which shows the tread part of the pneumatic tire for construction vehicles of 4th Embodiment. It is a top view which shows the tread part of the pneumatic tire for construction vehicles of 5th Embodiment. It is a top view which shows the tread part of the pneumatic tire for construction vehicles of 6th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tire for construction vehicle 18 Tread part 22 Lug groove 24 Width direction narrow groove 26 Equatorial upper shallow groove C Tire center part CL Tire equator

Claims (8)

  Two tires formed by arranging a large number of lug grooves extending from the respective tread ends toward the tire equatorial plane in the tread portion, and connecting the terminal positions of these lug grooves substantially in the tire circumferential direction. In a pneumatic tire in which a narrow groove having a width of 20 mm or less is arranged in the width direction in the center portion between the circumferences, a tread centering on the equator is provided in the center portion with a circumferential shallow groove extending along the tire circumferential direction. With respect to 100 parts by mass of at least one rubber component selected from the group consisting of natural rubber and synthetic rubber and having a negative rate of 8% or less excluding circumferential shallow grooves in the region of 25% of the width A rubber composition comprising 0.1 to 30 parts by mass of a compound having a part Q containing dipolar nitrogen and a compound having 4 to 6 nitrogen-containing heterocyclic parts B containing oxygen or sulfur is used as a tire member. Pneumatic tire, characterized in that it is formed by use.   The dipolar nitrogen portion is selected from at least one of A1-C (A2) = N (A3) → O, A1-C≡N → O, and A1-C≡N → N-A4, and the A1 -A4 is hydrogen which may be different from each other, or a group having 20 or less carbon atoms or a connecting chain connecting the B, and the compound is bonded to at least one of A1 to A4. The pneumatic tire according to 1.   A1 to A4 of the above compound are hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms (however, the aromatic ring has a nitro group, a cyano group) A chloro group, a bromo group, an acyl group, a carbonylalkyl group, an alkyl group, and an alkoxyl group), or a connecting chain. tire.   The pneumatic tire according to claim 1, wherein the nitrogen-containing heterocycle of the B part is oxazoline or thiazoline.   The above compounds are 4- (2-oxazolyl) -phenyl-N-methyl-nitrone, 4- (2-thiazolyl) -phenyl-N-methyl-nitrone, 4- (2-oxazolyl) -phenyl-N-phenyl. -Nitrone, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrone, phenyl-N-4- (2-oxazolyl) -phenyl-nitrone, phenyl-N-4- (2-thiazolyl) -phenyl-nitrone 4-tolyl-N-4- (2-oxazolyl) -phenyl-nitrone, 4-tolyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4-methoxyphenyl-N-4- (2-oxazolyl) ) -Phenyl-nitrone, 4-methoxyphenyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4- (2-oxazolyl) -phenyl-nitrileoxy 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-methyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-methyl-nitrileimine, 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-phenyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrileimine, phenyl-N-4 The pneumatic tire according to claim 4, comprising at least one of-(2-oxazolyl) -phenyl-nitrileimine and phenyl-N-4- (2-thiazolyl) -phenyl-nitrileimine.   The pneumatic tire according to any one of claims 1 to 5, wherein a groove depth of the circumferential shallow groove is 25% or less of the lug groove depth.   The pneumatic tire according to any one of claims 1 to 6, wherein a groove width of the circumferential shallow groove is 30 to 50 mm.   The pneumatic tire according to any one of claims 1 to 7, wherein the pneumatic tire is a pneumatic tire for construction vehicles.

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