JP2019026251A - Pneumatic type cushion tire for industrial vehicle - Google Patents

Abstract

To provide a pneumatic type cushion tire for an industrial vehicle that is able to further improve a tire life by improving abrasion resistance of a tire more than a conventional one.SOLUTION: In a pneumatic type cushion tire for an industrial vehicle, having an outside diameter of 650 to 700 mm and mounted on a front wheel of the industrial vehicle, a tread has a ground contact area (cm)× block height (mm) of 5500 to 6500, and a circumferential block rigidity of 3100 to 4000 N/mm. A rubber composition composing the tread contains 50 to 65 pts.mass of carbon black with a particle diameter of 18 to 25 nm with respect to 100 pts.mass of rubber constituent. The pneumatic type cushion tire has a loss tangent of 0.16 or less at 100°C.SELECTED DRAWING: None

Description

  The present invention relates to a pneumatic cushion tire for an industrial vehicle.

  For industrial vehicles such as forklift trucks where low speed and heavy loads are applied, a so-called pneumatic cushion tire (hereinafter simply referred to as “pneumatic tire”) that has the same appearance as a pneumatic tire and can be directly assembled to a rim used for a pneumatic tire. Tire)) is often used.

  FIG. 3 shows a configuration of a general pneumatic cushion tire. The pneumatic cushion tire 1 has a two-layer structure of a base rubber layer 2 disposed on the rim R side and a tread (cap) rubber layer 3 disposed on the radially outer side of the base rubber layer 2. In addition, 3A is a ground plane, 3B is a groove part, and 4 is a bead core. CL is a center line.

  Industrial vehicles equipped with such tires generally run on poor roads rather than public roads, and the frequency of turns is high, so the tires are subject to heavy burdens and wear, and the tread blocks are deformed. Easy to break. In addition, the tire tends to generate heat due to a low speed and a large load during traveling, and rubber blows easily.

  Therefore, conventionally, it has been proposed to improve the tire life by improving the tire wear resistance by improving the hardness or increasing the elongation by devising the composition of the tread rubber (for example, Patent Documents 1 and 2).

JP 10-53005 A Japanese Patent Laid-Open No. 10-315706

  However, the improvement in tire life is still not sufficient, and further improvement is required.

  Then, this invention makes it a subject to provide the pneumatic cushion tire for industrial vehicles which can aim at the further improvement of the tire life by improving the abrasion resistance of a tire further conventionally.

  The inventor has intensively studied and found that the above-described problems can be solved by the invention described below, and has completed the present invention.

The invention described in claim 1
A pneumatic cushion tire for an industrial vehicle having an outer diameter of 650 to 700 mm and attached to a front wheel of an industrial vehicle,
The tread has a ground contact area (cm ² ) × block height (mm) of 5500 to 6500 and a circumferential block rigidity of 3100 to 4000 N / mm,
The rubber composition constituting the tread contains 50 to 65 parts by mass of carbon black having a particle diameter of 18 to 25 nm with respect to 100 parts by mass of the rubber component, and the loss tangent at 100 ° C. is 0.16 or less. This is a pneumatic cushion tire for industrial vehicles.

The invention described in claim 2
The rubber component of the rubber composition constituting the tread contains natural rubber and butadiene rubber, and the content of the butadiene rubber is 10 to 40 parts by mass with respect to 100 parts by mass of the rubber component. The pneumatic cushion tire for an industrial vehicle according to claim 1.

The invention according to claim 3
3. The pneumatic cushion tire for industrial vehicles according to claim 1, wherein the ground contact area is 280 cm ² or more and the block height is 23 mm or less.

The invention according to claim 4
A pneumatic cushion tire for an industrial vehicle having an outer diameter of 500 to 550 mm and attached to a rear wheel of the industrial vehicle,
The tread has a ground contact area (cm ² ) × block height (mm) of 3000 to 4000, and a width direction block rigidity of 2000 to 3000 N / mm,
The rubber composition constituting the tread contains 20 to 55 parts by mass of carbon black having a particle size of 25 to 35 nm with respect to 100 parts by mass of the rubber component, and 10 to 10 parts by mass of butadiene rubber. It is a pneumatic cushion tire for industrial vehicles characterized by containing 40 parts by mass and having a loss tangent at 100 ° C. of 0.15 or less.

The invention described in claim 5
To the rubber composition constituting the tread, carbon black having a particle size of 25 to 35 nm and carbon black having a particle size of 18 to 25 nm are added at a ratio (mass ratio) of 1: 1, and a rubber component The pneumatic cushion tire for industrial vehicles according to claim 4, wherein the total amount of carbon black with respect to 100 parts by mass is 50 to 65 parts by mass.

The invention described in claim 6
The pneumatic cushion tire for an industrial vehicle according to claim 4 or 5, wherein the ground contact area is 190 cm ² or more and the block height is 20 mm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the abrasion resistance of a tire can be improved further conventionally and the pneumatic cushion tire for industrial vehicles which can aim at the further improvement of a tire life can be provided.

It is sectional drawing which shows the structure of the pneumatic cushion tire for industrial vehicles which concerns on one embodiment of this invention. It is a figure explaining how to obtain block rigidity. It is sectional drawing which shows the structure of the general type pneumatic tire for industrial vehicles.

[1] Pneumatic cushion tire for industrial vehicles according to the present invention First, the pneumatic cushion tire for industrial vehicles according to the present invention will be described including the progress of the study.

  The present inventor has examined the provision of a pneumatic cushion tire for an industrial vehicle that can further improve the tire life (life performance) by further improving the wear resistance of the tire. The mechanism of wear on the front and rear wheels of each tire was examined, and the points to be considered in improving the wear resistance of each tire were identified, and the means for solving them were studied.

  That is, in an industrial vehicle, a front wheel drive and a rear wheel operation method are generally employed. A tire having a large outer diameter is applied to a front wheel to which a large load is applied, and a tire having a small outer diameter is applied to a rear wheel that requires a small turn. However, since the force in the traveling direction mainly acts on the tread of the front wheel (front) that is the driving wheel, the block is deformed in the circumferential direction and is worn. On the other hand, the tread of the rear wheel (rear), which is the operation wheel, mainly acts in the width direction due to turning. Therefore, the block deforms in the width direction during turning, causing cracks to wear and generating heat and softening. To do.

  And, as a result of study, in order to improve the wear resistance of these tires, it is necessary to comprehensively consider these ingenuity on tread rubber compounding and tread shape individuation. I found out.

  That is, tire wear is not only worn away by friction with the road surface, but also involves deformation of the block, and if the deformation is large, fine cracks are generated in the rubber, which promotes wear.

  Wear is also promoted by heat generated by friction during turning. Specifically, the heat generation increases the loss tangent (tan δ) of the rubber composition and lowers the blow-resistant performance even before blowout occurs, so that wear is promoted.

  Therefore, as a device for blending tread rubber, it was considered to reduce the particle size of carbon black (hereinafter also referred to as “CB”) used as a reinforcing filler. By blending CB having a small particle diameter, the contact area between CB and rubber can be increased, so that the reinforcing effect of rubber is improved and the wear resistance is improved.

  Thus, CB having a finer particle diameter, specifically, CB having a particle size of 18 to 25 nm is used for the tread rubber composition for the front wheel, and a particle size of 25 is used for the tread rubber composition for the rear wheel. By adding CB of ˜35 nm and reinforcing each rubber, the rigidity of the tread block (block rigidity) increases, so that the deformation of the block can be reduced and the occurrence of breakage of the block is suppressed. Confirmed that it can.

  Further, such CB addition reduces tan δ, specifically, at 100 ° C., 0.16 or less for the front tread rubber composition and 0.15 or less for the rear tread rubber composition. Since it can be made smaller, it is possible to suppress the blow of rubber due to heat generation during traveling.

  Furthermore, when not only the hardness of the tread is increased by CB having a fine particle diameter, but also a rubber component in which butadiene rubber (hereinafter also referred to as “BR”) is added to natural rubber (NR) as a rubber component, It has been found that the wear resistance is improved. In particular, in the case of the rubber component of the rear wheel, a remarkable effect is exhibited.

  By adding BR, a flexible BR layer is formed in the NR layer serving as the matrix layer, and the progress of cracks in the tread stops at the BR layer, which makes it more difficult to wear. As a result, the wear resistance of the rear wheel, which applies a large force in the width direction during turning, is greatly improved.

  However, the improvement in wear resistance is still not sufficient only with the above-described tread rubber formulation. Therefore, the present inventor further examined the tread shape and realized that it is necessary to increase the ground contact area and the block height in order to improve the wear resistance.

  By increasing the contact area and the block height, you can earn a rubber volume that will be worn before the tire is completely worn (completed), so the wear resistance of the tire will be maintained for a long period of time. Thus, the life performance of the tire can be improved.

At this time, the product of the contact area (cm ² ) and the block height (mm) is within a certain range, specifically, 5500 to 6500 for the front wheels and 3000 to 4000 for the rear wheels. By setting, it has been found that the effect is synergistically combined with the effects of the tread rubber composition, and the wear resistance of the tire is greatly improved, and the present invention has been completed.

That is, the pneumatic cushion tire for industrial vehicles according to the present invention is
A pneumatic cushion tire for an industrial vehicle having an outer diameter of 650 to 700 mm and attached to a front wheel of an industrial vehicle,
The tread has a ground contact area (cm ² ) × block height (mm) of 5500 to 6500 and a circumferential block rigidity of 3100 to 4000 N / mm,
The rubber composition constituting the tread contains 50 to 65 parts by mass of carbon black having a particle diameter of 18 to 25 nm with respect to 100 parts by mass of the rubber component, and the loss tangent at 100 ° C. is 0.16 or less. This is a pneumatic cushion tire for industrial vehicles.

In addition, the pneumatic cushion tire for industrial vehicles according to the present invention,
A pneumatic cushion tire for an industrial vehicle having an outer diameter of 500 to 550 mm and attached to a rear wheel of the industrial vehicle,
The tread has a ground contact area (cm ² ) × block height (mm) of 3000 to 4000, and a width direction block rigidity of 2000 to 3000 N / mm,
The rubber composition constituting the tread contains 20 to 55 parts by mass of carbon black having a particle size of 25 to 35 nm with respect to 100 parts by mass of the rubber component, and 10 to 10 parts by mass of butadiene rubber. It is a pneumatic cushion tire for industrial vehicles characterized by containing 40 parts by mass and having a loss tangent at 100 ° C. of 0.15 or less.

[2] Embodiments of the Present Invention Based on the embodiments of the present invention, the present invention will be specifically described below with reference to the drawings.

1. First Embodiment A tire according to the present embodiment is a pneumatic cushion tire for an industrial vehicle having an outer diameter of 650 to 700 mm and attached to a front wheel of the industrial vehicle.

  As described above, since the force in the traveling direction mainly acts on the tread of the front wheel which is the driving wheel, the block is deformed and worn in the circumferential direction.

In the tire according to the present embodiment, the tread has a ground contact area (cm ² ) × block height (mm) of 5500 to 6500 as a tire having a large block rigidity in the circumferential direction and excellent in blow-proof performance. In addition, the tire has a circumferential block rigidity of 3100 to 4000 N / mm. The tire tread contains 50 to 65 parts by mass of carbon black having a particle diameter of 18 to 25 nm with respect to 100 parts by mass of the rubber component, and tan δ at 100 ° C. is 0.16 or less.

  By adopting such a configuration, each requirement is synergistically effective, and while maintaining the grip performance required for the front wheels, it is excellent in wear resistance and as a tire mounted on the front wheels of industrial vehicles. A suitable tire can be provided.

(1) Tread Shape FIG. 1 is a cross-sectional view showing a configuration of a tire according to the present embodiment. In FIG. 1, 3C is a tread, 31 is a block, D is an outer diameter of the tire, and HB is a protruding height of the block 31 from the tread 3C, that is, a block height. The other reference numerals are the same as those in FIG.

  In the present embodiment, there is no difference from the conventional general tire configuration shown in FIG. 3 in the basic configuration in which the rubber layer has a two-layer structure of the base rubber layer 2 and the tread rubber layer 3. The design of the shape of the tread surface, the composition of the rubber composition constituting the tread rubber layer 3, and the shape of the block 31 are different from the conventional ones.

In the present embodiment, in addition to the grip performance, the contact area (cm ² ) × the block height (mm) from the viewpoint of improving the rigidity of the block 31 and increasing the volume of rubber that is allowed to wear. ) Based on the size of the tread pattern. Specifically, the ground contact area (cm ² ) × block height (mm) is set to 5500-6500. More preferably, it is 5650-6350, and it is still more preferable in it being 5800-6200.

In the present embodiment, the ground contact area is preferably 280 cm ² or more and the block height is preferably 23 mm or less. Under this condition, the above-described ground contact area (cm ² ) × height (mm) By setting the value to be 5500 to 6500, the wear resistance of the tire can be sufficiently improved.

  In this embodiment, a rubber composition having a circumferential block rigidity of 3100 to 4000 N / mm and a tan δ at 100 ° C. of 0.16 or less is used as the rubber composition constituting the tread. By setting the circumferential block rigidity to 3100 to 4000 N / mm, it is possible to suppress wear due to the force in the traveling direction. More preferably, it is 3200-3900 N / mm, and it is further more preferable in it being 3300-3800 N / mm. Moreover, heat generation can be suppressed by setting tan δ at 100 ° C. to 0.16 or less. More preferably, it is 0.14 or less, and further preferably 0.12 or less.

  The circumferential block rigidity described above can be obtained based on F and Δ shown in FIG. In FIG. 2, 31 is a block formed on the tread surface of the tread, M is the circumferential length of the block 31, and HB is the block height. The block rigidity is represented by a ratio F / Δ between the load F acting in the circumferential direction on the tread surface of the block 31 and the distance Δ over which the block 31 has moved in the circumferential direction. The block rigidity can also be set by determining the circumferential length M and the block height HB of the block 31 after determining the rubber hardness.

(2) Compounding material of tread rubber composition Next, the compounding material used for the above-mentioned tread rubber composition will be described.

(A) Rubber component In this embodiment, natural (NR) rubber is used as the main component for the rubber component, but it is more preferable to add a part of butadiene (BR) rubber. As a result, a flexible BR layer is formed in the NR layer serving as the matrix layer, and the progress of cracks in the tread stops at the BR layer, making it more difficult to wear.

  NR rubber is not particularly limited, and is not limited to natural rubber commonly used in the rubber industry, such as SIR20, RSS # 3, TSR20, but also epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and deproteinized natural rubber. Modified natural rubber such as (DPNR) can also be used. In addition, although these natural rubbers can also be used independently, you may use 2 or more types together.

  The BR is not particularly limited. For example, BR730 and BR51 manufactured by JSR Corporation, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., BR150B, BR710, etc., high cis content BR, Nippon Zeon Co., Ltd. BR (SPB-containing BR) containing 1,2-syndiotactic polybutadiene crystals (SPB) such as VCR412, VCR617, etc. manufactured by Ube Industries, Ltd. . These can be used alone or in combination of two or more.

  And in this Embodiment, when adding BR to a rubber component, it is preferable that content of BR rubber in 100 mass parts of rubber components is 10-40 mass parts, and is 12-30 mass parts More preferably, it is more preferable in it being 14-25 mass parts.

(B) Carbon black In this Embodiment, carbon black with a particle diameter of 18-25 nm is used as carbon black (CB). It is more preferably 19 to 24 nm, and further preferably 20 to 23 nm.

  In addition, the particle diameter of CB can be calculated | required by observing the cross section of a tread with a transmission electron microscope (TEM).

  Specific examples of such CB include N220 (ASTM code). By blending CB having a fine particle diameter as described above, it is possible to reinforce the rubber while ensuring a large contact area with the rubber component. it can.

  And, by blending 50 to 65 parts by mass of such CB with respect to 100 parts by mass of the rubber component, tan δ at 100 ° C. can be made 0.16 or less, and heat generation during running can be suppressed. it can. The compounding amount with respect to 100 parts by mass of the rubber component is more preferably 52 to 63 parts by mass, and further preferably 54 to 61 parts by mass.

  In the present embodiment, in addition to the above CB, about 5 parts by mass of CB having another particle diameter may be added.

At this time, it is preferable that the BET specific surface area of CB is 40-300 m < ² > / g, Thereby, while ensuring the intensity | strength of rubber | gum, sufficient dispersibility can be ensured. More preferable to be 50~280m ² / g, further preferably a 60~260m ² / g.

  In addition, the BET specific surface area of CB can be measured by the method based on JISK6217, for example.

Further, the nitrogen adsorption specific surface area (N ₂ SA) of CB is 20 to 20 from the point that sufficient reinforcing property is obtained and crack growth resistance is excellent, and the hardness of the rubber is suppressed and low heat generation is excellent. is preferably 70m ² / g, more preferable to be 25~60m ² / g, further preferably a 25~40m ² / g.

  Note that the nitrogen adsorption specific surface area of CB can be measured by a method based on JIS K6217, for example.

(C) Other compounding materials In the present embodiment, in addition to the above materials, the following compounding agents generally used for the production of tires can be added.

  Antiaging agents include diphenylamine (p- (p-toluenesulfonylamide) -diphenylamine, octylated diphenylamine, etc.), p-phenylenediamine (N- (1,3-dimethylbutyl) -N′-phenyl-p -Phenylenediamine (6PPD), N-phenyl-N'-isopropyl-p-phenylenediamine (IPPD), N, N'-di-2-naphthyl-p-phenylenediamine, etc.) can be used. A specific example is “NOCRACK 6C” (N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

  Examples of the oil that can be used include process oil, vegetable oil and fat, and a mixture thereof. Examples of the process oil include paraffinic process oil, naphthenic process oil, and aromatic process oil. Vegetable oils include castor oil, cottonseed oil, rapeseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple oil, tall oil, corn oil, rice bran oil, beet flower oil, Sesame oil, olive oil, sunflower oil, palm kernel oil, coconut oil, jojoba oil, macadamia nut oil, safflower oil, tung oil, and the like. As an example of a specific aromatic process oil, “VIVATEC 500” manufactured by H & R may be mentioned.

  As the vulcanizing chemical, sulfur as a vulcanizing agent and a vulcanization accelerator can be appropriately used.

  As sulfur, powdered sulfur may be used, but considering the dispersibility in rubber, it is preferable to use oil-treated powdered sulfur.

  As the vulcanization accelerator, a vulcanization accelerator generally used in combination with powdered sulfur in the rubber industry can be used. Specific examples of the vulcanization accelerator include sulfenamide, thiazole and thiuram. Thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, or xanthate-based vulcanization accelerators, which can be used alone, but two or more May be used in combination. As an example of a specific sulfenamide vulcanization accelerator, “Noxeller NS” (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd. can be mentioned.

  Moreover, zinc oxide, stearic acid, etc. can also be used as a vulcanization acceleration aid.

  When the rubber composition in which the above-mentioned respective compounding materials are blended is used, the rubber is reinforced by ensuring a large contact area with the rubber component, and a tread rubber composition having a tan δ at 100 ° C. of 0.16 or less is obtained. be able to.

  In the above, tan δ at 100 ° C. was measured using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) under conditions of temperature 100 ° C., frequency 10 Hz, initial strain 10%, and dynamic strain 2%. can do.

  And, by using such a tread rubber composition, the above-mentioned tread shape makes it possible to produce a synergistic effect, while maintaining the grip performance necessary for the front wheels, and having excellent wear resistance. A tire suitable as a tire to be mounted on a front wheel of a vehicle can be provided.

2. Second Embodiment A tire according to the present embodiment is a pneumatic cushion tire for an industrial vehicle having an outer diameter of 500 to 550 mm and attached to a rear wheel of the industrial vehicle.

  As described above, the tread of the rear wheel, which is the operation wheel, mainly acts in the width direction due to turning, so that the block is deformed in the width direction during turning, causing cracks to wear and generating heat and softening. To do.

In the tire according to the present embodiment, the tread has a ground contact area (cm ² ) × block height (mm) of 3000 to 4000 as a tire having a large block rigidity in the width direction and excellent in blow-proof performance. And it is a tire whose width direction block rigidity is 2000-3000 N / mm. The tire tread contains carbon black having a particle diameter of 25 to 35 nm in an amount of 20 to 55 parts by mass with respect to 100 parts by mass of the rubber component, and butadiene rubber in an amount of 10 to 40 parts by mass with respect to 100 parts by mass of the rubber component. The tan δ at 100 ° C. is 0.15 or less.

  By adopting such a configuration, each requirement exhibits a synergistic effect, and even if the tire is greatly deformed in the width direction during turning, the occurrence of cracks is suppressed and wear is suppressed, and heat is generated. It is possible to provide a tire that can be suppressed and that is suitable as a tire to be mounted on the rear wheel of an industrial vehicle.

(1) Tread shape Also in the present embodiment, a tread pattern is set based on the size of a ground contact area (cm ² ) × block height (mm). Specifically, the ground contact area (cm ² ) × block height (mm) is set to 3000 to 4000. More preferably, it is 3200-3800, and it is further more preferable in it being 3400-3600.

Note that the ground contact area is 190 cm ² or more and the block height is preferably 20 mm or less. Under this condition, the value of the ground contact area (cm ² ) × height (mm) is 3000 to 4000. By setting so as to be, the wear resistance of the tire can be sufficiently improved.

  In this embodiment, a tread rubber having a width direction block rigidity of 2000 to 3000 N / mm and a tan δ at 100 ° C. of 0.15 or less is used as the tread rubber. By setting the width direction block rigidity to 2000 to 3000 N / mm, even if the tire is greatly deformed in the width direction during turning, the occurrence of cracks can be suppressed and wear can be suppressed. More preferably, it is 2100-2900 N / mm, and it is further more preferable in it being 2200-2800 N / mm. Further, by setting tan δ at 100 ° C. to 0.15 or less, rubber blow due to heat generation can be suppressed. More preferably, it is 0.14 or less, and further preferably 0.13 or less.

  The width direction block rigidity described above can be measured in the same manner as the measurement of the circumferential direction block rigidity shown in FIG. Specifically, M in FIG. 2 is the width of the block 31, and the load F acting in the width direction can be obtained by the ratio F / Δ with the distance Δ that has fallen and moved in the width direction.

(2) Compounding material of tread rubber composition Also in the present embodiment, the same compounding material as that of the front wheel tire can be basically used.

  However, in this Embodiment, the quantity of BR rubber added to a rubber component is set to 10-40 mass parts. More preferably, it is 12-30 mass parts, and it is further more preferable that it is 14-25 mass parts.

  In the present embodiment, carbon black having a particle diameter of 25 to 35 nm is used as the carbon black. It is more preferable that it is 26-34 nm, and it is further more preferable that it is 27-33 nm.

  Examples of CB having a particle diameter of 25 to 35 nm include N330 (ASTM code).

  And, by appropriately blending 20 to 55 parts by mass of such CB with respect to 100 parts by mass of the rubber component, tan δ at 100 ° C. can be made 0.15 or less, and heat generation during traveling can be achieved. Can be suppressed. The compounding amount with respect to 100 parts by mass of the rubber component is more preferably 25 to 50 parts by mass, and further preferably 30 to 45 parts by mass.

  At this time, carbon black having a particle diameter of 25 to 35 nm and carbon black having a particle diameter of 18 to 25 nm (N220) are added at a ratio (mass ratio) of 1: 1, so that carbon relative to 100 parts by mass of the rubber component is added. The total amount of black may be 50 to 70 parts by mass.

  By properly blending each of the above blended materials, it is possible to reinforce the rubber while ensuring a large contact area with the rubber component, and to provide a tread rubber composition having a tan δ at 100 ° C. of 0.15 or less. it can.

  And by using such a tread rubber composition, the shape of the tread described above provides a synergistic effect and suppresses the occurrence of cracks even if the tire deforms greatly in the width direction during turning. Therefore, it is possible to provide a tire suitable for being worn on the rear wheel of an industrial vehicle.

  Hereinafter, based on an Example, this invention is demonstrated more concretely.

1. Preparation of test body 1 to No. 1 A rubber composition for a tread was prepared based on the content of each compound shown in FIG. Table 1 also shows tan δ measured at 100 ° C. and 10 Hz measured for each rubber composition.

Each compounding material described in Table 1 is specifically as follows.
NR: TSR20
SBR: JBR SBR1502
BR: BR150B manufactured by Ube Industries
Rubber powder: powder rubber powder W2-A (30 mesh vulcanized rubber powder) manufactured by Asahi Recycled Rubber Co., Ltd.
Carbon Black 1: Show Black N220 Showa Cabot
Carbon Black 2: Show Black N330, Showa Cabot
Anti-aging agent: Nocrack 6C manufactured by Ouchi Shinsei Chemical Co., Ltd.
Stearic acid: Nippon Oil & Fats Co., Ltd. Beads stearic acid Tsubaki Zinc oxide: Mitsui Metal Mining Co., Ltd. zinc oxide Oil: H & R VIVATEC500
Sulfur: Seimisulfur manufactured by Nippon Kibushi Kogyo Co., Ltd. Vulcanization accelerator: Noxeller NS manufactured by Ouchi Shinsei Chemical Co., Ltd.

  Next, using the produced rubber composition, as shown in Tables 2 and 3, the tread pattern (ground contact area × block height) was changed to change the front wheel tire for forklift (size 7.00-12: Outer diameter 669 mm) and rear wheel tires (size 6.00-9: outer diameter 538 mm) were manufactured (N = 6).

The tread pattern has two types of contact area (cm ² ) × height (mm) of 260 × 18 (pattern A) and 285 × 21 (pattern B) in the front wheel tire, and in the rear wheel tire. The ground contact area (cm ² ) × height (mm) was 187 × 16 (pattern C) and 205 × 17 (pattern D).

2. Evaluation (1) Evaluation method After that, block rigidity (circumferential direction and width direction) is measured for each tire, and mounted on a forklift for life performance (straight on front tires and turning on rear tires). Evaluated.

  Life performance is evaluated when each tire is mounted on a forklift (manufactured by Toyota L & F, 8FG25 (2.5t car)), running on the concrete floor, and running for 3 months on average 20 hours a day. The time until the remaining groove became zero was estimated from the amount of wear, and this was defined as life. In addition, evaluation is shown by the relative index | exponent which sets the life of Experimental example 1 and Experimental example 11 which are a prior art example to 100, and it has shown that it is so that it is excellent performance, so that a numerical value is large.

(2) Evaluation results (a) Evaluation results for front wheels Table 2 shows the evaluation results for front wheel tires. In Table 2, Experimental Examples 5 to 9 are examples, and Experimental Examples 1 to 4 and Experimental Example 10 are comparative examples.

(B) Evaluation result of rear wheel Table 3 shows the evaluation result of the rear wheel tire. In Table 3, Experimental Examples 16 to 19 are examples, and Experimental Examples 11 to 15 are comparative examples.

  From Tables 2 and 3, it can be seen that by devising the composition of the tread rubber and the tread shape, synergistic effects are exhibited, the tire wear resistance is greatly improved, and the tire life is improved.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

1 Pneumatic cushion tire 2 Base rubber layer 3 Tread (cap) rubber layer 3A Ground surface 3B Groove 3C Tread 31 Block 4 Bead core CL Centerline D Tire outer diameter F Load acting on the circumference HB Block height M Block height Circumferential length R Rim Δ Distance the block has moved in the circumferential direction

Claims (6)

A pneumatic cushion tire for an industrial vehicle having an outer diameter of 650 to 700 mm and attached to a front wheel of an industrial vehicle,
The tread has a ground contact area (cm ² ) × block height (mm) of 5500 to 6500 and a circumferential block rigidity of 3100 to 4000 N / mm,
The rubber composition constituting the tread contains 50 to 65 parts by mass of carbon black having a particle diameter of 18 to 25 nm with respect to 100 parts by mass of the rubber component, and the loss tangent at 100 ° C. is 0.16 or less. A pneumatic cushion tire for industrial vehicles.   The rubber component of the rubber composition constituting the tread contains natural rubber and butadiene rubber, and the content of the butadiene rubber is 10 to 40 parts by mass with respect to 100 parts by mass of the rubber component. The pneumatic cushion tire for industrial vehicles according to claim 1. The pneumatic cushion tire for industrial vehicles according to claim 1 or 2, wherein the ground contact area is 280 cm ² or more and the block height is 23 mm or less. A pneumatic cushion tire for an industrial vehicle having an outer diameter of 500 to 550 mm and attached to a rear wheel of the industrial vehicle,
The tread has a ground contact area (cm ² ) × block height (mm) of 3000 to 4000, and a width direction block rigidity of 2000 to 3000 N / mm,
The rubber composition constituting the tread contains 20 to 55 parts by mass of carbon black having a particle size of 25 to 35 nm with respect to 100 parts by mass of the rubber component, and 10 to 10 parts by mass of butadiene rubber. A pneumatic cushion tire for industrial vehicles, containing 40 parts by mass and having a loss tangent at 100 ° C. of 0.15 or less.   To the rubber composition constituting the tread, carbon black having a particle size of 25 to 35 nm and carbon black having a particle size of 18 to 25 nm are added at a ratio (mass ratio) of 1: 1, and a rubber component The pneumatic cushion tire for industrial vehicles according to claim 4, wherein the total amount of carbon black with respect to 100 parts by mass is 50 to 65 parts by mass. The pneumatic cushion tire for an industrial vehicle according to claim 4 or 5, wherein the ground contact area is 190 cm ² or more and the block height is 20 mm or less.

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