JP2005343379A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of effectively suppressing generation of a crack in an inner liner layer. <P>SOLUTION: In the pneumatic tire 1, a carcass layer 3 is attached and an inner liner layer 4 is formed on an inner surface rubber of the carcass layer 3. The inner liner layer 4 comprises a thermoplastic resin containing a rubber composition and a thickness dimension d in a shoulder part is larger than a thickness dimension in a tire crown part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can effectively suppress the occurrence of cracks in an inner liner layer.

  The pneumatic tire has an inner liner layer on its inner peripheral surface. The inner liner layer is made of a material having low gas permeability, and has a function of keeping the tire air pressure constant by suppressing air leakage from the inside of the tire due to permeation. As such a material, rubber having low gas permeability such as butyl rubber has been conventionally used. However, in order to reduce the weight of the tire, a film-like material made of a material containing a thermoplastic resin instead of the rubber material. Is proposed in Patent Document 1. Here, a large shear strain acts on the inner liner layer near the shoulder portion when the tire is used. When a material containing a thermoplastic resin is used as the inner liner layer, there is a problem that cracks are generated in the inner liner layer due to the shear strain, and air leakage of the tire occurs.

JP-A-8-258506

  In particular, when a material containing a thermoplastic resin is used as the inner liner layer, when the tire is used under low temperature conditions, the breaking strength of the inner liner layer is reduced compared to that at room temperature due to the curing of the inner liner layer. There was a problem that the layer easily cracked.

  Then, this invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can suppress generation | occurrence | production of the crack in an inner liner layer effectively.

  In order to achieve the above object, the pneumatic tire according to the present invention is a pneumatic tire in which an inner liner layer is formed on an inner rubber of a carcass layer mounted on a pair of bead portions. It consists of the thermoplastic resin containing a rubber composition, and the thickness dimension in a shoulder part is larger than the thickness dimension in a tire crown part, It is characterized by the above-mentioned.

  This pneumatic tire is configured such that the thickness dimension at the shoulder portion of the inner liner layer is larger than the thickness dimension at the tire crown portion. Thereby, since the durability of the inner liner layer in the shoulder portion is improved, there is an advantage that air leakage of the tire is effectively suppressed.

  The pneumatic tire according to the present invention is perpendicular to the boundary line between the inner rubber of the carcass layer and the inner liner layer in the tire meridian direction from the ground contact end P of the tread portion in the tire inner diameter direction. When the l is pulled, the inner liner layer has a range from the vertical l to the tire crown CL at least about 10 [%] from the vertical l toward the tire crown CL. It is formed to be thicker than CL.

  In the pneumatic tire, the above configuration has an advantage that the air leakage of the tire is more effectively suppressed. The ground contact P is defined in a state where a specified air pressure and a specified load are added to the rim assembled pneumatic tire. The tire crown portion CL is a portion located on the tire equator.

  Further, in the pneumatic tire according to the present invention, the range in which the inner liner layer is formed thick is a range of about 50 [%] or less from the perpendicular l toward the tire crown CL.

  In this pneumatic tire, the above configuration has an advantage that an increase in rolling resistance of the tire is suppressed.

  The pneumatic tire according to the present invention is perpendicular to the boundary line between the inner rubber of the carcass layer and the inner liner layer in the tire meridian direction from the ground contact end P of the tread portion in the tire inner diameter direction. When the l is pulled, the inner liner layer has a tire crown in a range from the normal l to the tire maximum width part SW, at least 20% from the normal l toward the tire maximum width part SW. It is formed to be thicker than the part CL.

  In the pneumatic tire, the above configuration has an advantage that the air leakage of the tire is more effectively suppressed. The tire maximum width portion SW refers to a portion that becomes the maximum width of the tire in a state where a specified air pressure and a specified load are applied to the rim assembled pneumatic tire 1.

  In the pneumatic tire according to the present invention, the range in which the inner liner layer is formed thick is a range of about 100 [%] or less from the perpendicular l toward the tire maximum width portion SW.

  In this pneumatic tire, the above configuration has an advantage that an increase in rolling resistance of the tire is suppressed.

  In the pneumatic tire according to the present invention, the inner liner layer has a thickness dimension of about 160 [%] to about 300 [%] with respect to the thickness dimension of the tire crown portion CL.

  With this pneumatic tire, the above configuration has an advantage that cracks in the inner liner layer can be more effectively suppressed while suppressing an increase in rolling resistance of the tire.

  According to this invention, since the thickness dimension in the shoulder portion of the inner liner layer is configured to be larger than the thickness dimension in the tire crown portion, the durability of the inner liner layer in the shoulder portion is improved. There is an advantage that tire air leakage is effectively suppressed.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements of the embodiments described below include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  1 is a cross-sectional view in the meridian direction showing a pneumatic tire according to Example 1 of the present invention. FIG. 2 is an enlarged view showing a shoulder portion of the pneumatic tire shown in FIG. 1. In this pneumatic tire 1, a carcass layer 3 is mounted between a pair of left and right bead portions 2, 2, and an inner liner layer 4 is provided on an inner rubber (tire inner peripheral surface) of the carcass layer 3. This pneumatic tire 1 has a feature in that the occurrence of cracks in the inner liner layer 4 can be effectively suppressed by devising the dimensions and material of the inner liner layer 4.

  In the inner liner layer 4, the range corresponding to the shoulder portion is formed to be thicker than other ranges (for example, the tire crown portion CL and the tire maximum width portion SW). That is, the inner liner layer 4 is configured such that the range in which a relatively large shear stress acts when the tire is used is thicker than the other ranges.

  Specifically, the inner liner layer 4 is formed thick in the following range. First, a vertical line 1 is drawn from the ground contact end P of the tread portion toward the tire inner diameter direction with respect to the boundary line between the inner rubber of the carcass layer 3 and the inner liner layer 4 in a sectional view in the tire meridian direction. Here, the ground contact P is defined in a state where a specified air pressure and a specified load are added to the rim assembled pneumatic tire 1. The inner liner layer 4 is thicker than the tire crown portion CL in the range from the perpendicular l to the tire crown portion CL, and the range from the perpendicular l to the tire crown portion CL is at least about 10 [%]. Formed as follows. Further, the inner liner layer 4 is thicker than the tire crown portion CL in the range from the perpendicular l to the tire maximum width portion SW, and the range from the perpendicular l to the tire maximum width portion SW is at least 20%. It is formed to be meat. Further, the inner liner layer 4 has a thickness gauge in which the portion where the largest shear stress acts when using the tire (for example, the intersection with the perpendicular l) is at least about 160 [%] or more with respect to the tire crown portion CL. It is formed to have (thickness dimension) d. In this pneumatic tire 1, the tire crown portion CL means a portion located on the tire equator, and the tire maximum width portion SW applies a prescribed air pressure and a prescribed load to the rim assembled pneumatic tire 1. In the state, it shall mean the part which becomes the maximum width of the tire.

  In this pneumatic tire 1, even if shear strain occurs in the inner liner layer 4 at the shoulder when the tire is used, the inner liner layer 4 is formed thick at this portion, so that cracks hardly occur. . Thereby, since the durability of the inner liner layer 4 is improved, there is an advantage that the air leakage of the tire is effectively suppressed. Moreover, the range (thickness range) formed thick is limited only to a necessary and sufficient range centering on a portion (shoulder portion) where a relatively large shear strain is likely to occur. In other words, in other ranges, the thickness is formed to be the same as that of a conventional pneumatic tire. Accordingly, an increase in rolling resistance of the tire is suppressed and an increase in tire weight is suppressed, so that there is an advantage that deterioration in fuel consumption of the automobile can be effectively suppressed.

  In the pneumatic tire 1, as described above, the inner liner layer 4 has at least about 10% of the range from the perpendicular l to the tire crown CL in the range from the perpendicular l to the tire crown CL. The range is formed to be thicker than the tire crown portion CL. This is preferable in that the occurrence of cracks in the inner liner layer 4 can be effectively suppressed while suppressing an increase in tire weight. Moreover, it is preferable that the range formed thickly is selected within the range of about 10 [%] to about 50 [%]. Thereby, there exists an advantage that generation | occurrence | production of the crack in the inner liner layer 4 can be suppressed more effectively, suppressing the increase in rolling resistance of a tire.

  Moreover, in this pneumatic tire 1, as described above, the inner liner layer 4 is at least 20% from the vertical line 1 to the maximum tire width part SW in the range from the normal line 1 to the maximum tire width part SW. Is formed to be thicker than the tire crown portion CL. This is preferable in that the occurrence of cracks in the inner liner layer 4 can be effectively suppressed while suppressing an increase in tire weight. Moreover, it is preferable that the range formed thickly is selected within the range of about 20 [%] to about 100 [%]. Thereby, there exists an advantage that generation | occurrence | production of the crack in the inner liner layer 4 can be suppressed more effectively, suppressing the increase in rolling resistance of a tire.

  In the pneumatic tire 1, as described above, the inner liner layer 4 has a portion where the largest shearing stress is applied when the tire is used (for example, a portion intersecting with the perpendicular l) with respect to the tire crown portion CL. It is formed so as to have a thickness gauge d of at least about 160 [%] or more. This is preferable in that the occurrence of cracks in the inner liner layer 4 can be effectively suppressed while suppressing an increase in tire weight. Further, the uneven thickness gauge d is preferably selected within a range of about 160 [%] to about 300 [%]. Furthermore, it is preferable to select the uneven thickness gauge d within a range of 200 [%] to 300 [%]. Thereby, there exists an advantage that generation | occurrence | production of the crack in the inner liner layer 4 can be suppressed more effectively, suppressing the increase in rolling resistance of a tire.

  Moreover, in this pneumatic tire 1, the inner liner layer 4 is made of a film-like member made of the following material, and this film-like member is constituted by being stuck on the inner rubber of the carcass layer 3. This film-like member (inner liner layer 4) is made of a thermoplastic resin containing a rubber composition. By using such a film-like member, there is an advantage that the air pressure retention property of the tire can be improved and the increase in the tire weight can be suppressed while ensuring the flexibility of the tire.

  The inner liner layer 4 is made of, for example, (A) an at least one thermoplastic resin having an air permeability coefficient of 25 × 10 −12 [cc · cm / cm 2 · sec · cmHg] or less and a Young's modulus exceeding 500 [MPa]. 10% [%] or more per weight of polymer component and (B) at least one elastomer component having an air permeability coefficient of 25 × 10 −12 [cc · cm / cm 2 · sec · cmHg] and Young's modulus of 500 [MPa] or less In an amount such that the total amount (A) + (B) of component (A) and component (B) is 30% by weight or more per total polymer component weight. And a tire polymer composition having an air permeability coefficient of 25 × 10 −12 [cc · cm / cm 2 · sec · cmHg] or less and a Young's modulus of 1 to 500 [MPa].

  The thermoplastic resin blended as the component (A) in this polymer composition has an air permeability coefficient of 25 × 10 −12 [cc · cm / cm 2 · sec · cmHg] or less, preferably 0.1 × 10 −12 to An arbitrary thermoplastic resin having a Young's modulus of more than 500 [MPa], preferably 500 to 3000 [MPa] at 10 × 10 −12 [cc · cm / cm 2 · sec · cmHg] can be used. It is 10% by weight or more, preferably 20 to 85% by weight [%], based on the total weight of the polymer components including resin and rubber.

  As said thermoplastic resin, the following thermoplastic resins and these or arbitrary resin mixtures containing these can be mentioned, for example.

  Polyamide resins (for example, nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 612 (N612), nylon 6 / 66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer Coalesce, nylon 66 / PPS copolymer), polyester resin (for example, polymethylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), Polymethylene naphthalate (PBN), liquid crystal polyester, Aromatic polyesters such as reoxyalkylenediimide acid / polymethylate terephthalate copolymer), polynitrile resins (for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / Styrene copolymer, methacrylonitrile / styrene / butadiene copolymer), polymethacrylate resin (for example, polymethyl methacrylate (PMMA), polyethyl methacrylate), polyvinyl resin (for example, vinyl acetate (EVA), polyvinyl alcohol) (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer ), Cellulosic resins (eg cellulose acetate, cellulose acetate butyrate), fluorine resins (eg polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer) (ETFE)), imide resins (for example, aromatic polyimide (PI)), and the like.

  As described above, these thermoplastic resins must have a specific air permeability coefficient, Young's modulus and blending amount. A material having a Young's modulus of 500 [MPa] or less and an air permeability coefficient of 25 × 10 −12 [cc · cm / cm 2 · sec · cmHg] or less has not been developed industrially yet. In addition, when the air permeability coefficient exceeds 25 × 10 −12 [cc · cm / cm 2 · sec · cmHg], the air permeability resistance as a tire polymer composition is lowered, and the tire is used as an air permeation prevention layer. The function is lost. Further, when the blending amount of these thermoplastic resins is less than 10% by weight, the air permeation resistance is similarly lowered, and it cannot be used as a tire air permeation preventive layer.

  The elastomer component blended as the component (B) in the above resin composition has an air permeability coefficient larger than 25 × 10 −12 [cc · cm / cm 2 · sec · cmHg] and a Young's modulus of 500 [MPa]. Any of the following elastomers or blends thereof, or reinforcing agents, fillers, cross-linking agents, softeners, anti-aging agents generally incorporated into the elastomer for the purpose of improving the dispersibility and heat resistance of the elastomer, etc. An elastomer composition to which a necessary amount of a compounding agent such as an agent and a processing aid is added, and the compounding amount is 10% by weight [%] of the total amount of the polymer component including the resin and the elastomer component constituting the air permeation prevention layer. As mentioned above, Preferably it is 10-85 weight [%].

  The elastomer constituting such an elastomer component is not particularly limited as long as it has the above-described air permeability coefficient and Young's modulus, and examples thereof include the following.

  Diene rubber and hydrogenated products thereof (for example, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefin rubber (for example, ethylene propylene) Rubber (EPDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer), halogen-containing rubber (eg brominated) Butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR), brominated product of isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHR, CHC), chlorosulfonated polyethylene ( CSM), chlorinated polyethylene (CM), maleic acid modification Chlorinated polyethylene (M-CM)), silicone rubber (eg methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (eg polysulfide rubber), fluorine rubber (eg vinylidene fluoride rubber, fluorine-containing) Vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicone rubber, fluorine-containing phosphazene rubber), thermoplastic elastomer (eg styrene elastomer, polyolefin elastomer, polyester elastomer, polyurethane elastomer, polyamide elastomer) And so on.

  It is to be noted that the elastomer component is a halogen-containing (for example, Br, Cr, I) -containing copolymer rubber of C4 to C7 isomonoolefin and p-alkylstyrene, and the p-alkylstyrene content is 5 of the total copolymer rubber. Mooney viscosity of 5 to 25% [%], preferably 6.0 to 20% [%], halogen content of 1.0% [%] or more, preferably 1.0 to 5.0% [%] A copolymer rubber having an ML1 + 8 (125 ° C.) of 30 or more, preferably 35 to 70 can be used. When this rubber is used, the weight ratio of component (A) to component (B) is (A) / (B) = 10/90 to 90/10, preferably 15/85 to 85/15.

  If the copolymer rubber has a p-alkylstyrene content of less than 5.5% by weight, the air permeation resistance of the resulting tire polymer composition is undesirably reduced. If it exceeds, it tends to become brittle at low temperatures, which is not preferable. If the halogen content is less than 1.0% by weight [%], the mechanical strength such as tensile strength decreases, which is not preferable. If the Mooney viscosity is less than 30, the air permeation resistance decreases, which is not preferable. Furthermore, if the blending ratio (weight basis) of the component (A) / component (B) is less than 10/90, the air permeation resistance is also unfavorable, and conversely if it exceeds 90/10, the flexibility is decreased. Absent.

  When the above-mentioned specific thermoplastic resin and the elastomer component are different in compatibility, it is preferable to make them compatible with each other using a suitable compatibilizer as the third component. By mixing a compatibilizer into the system, the interfacial tension between the thermoplastic resin and the elastomer component is reduced, and as a result, the rubber particle size forming the dispersion layer becomes finer, so the characteristics of both components are more It will be expressed effectively. Such a compatibilizing agent is generally a copolymer having both or one structure of a thermoplastic resin and an elastomer component, or an epoxy group, carbonyl group, halogen group, amino group capable of reacting with the thermoplastic resin or elastomer component. A copolymer having a group, an oxazoline group, a hydroxyl group and the like can be taken. These may be selected according to the kind of the thermoplastic resin and the elastomer component to be mixed, but those usually used include styrene / ethylene-butylene block copolymer (SEBS) and its maleic acid modified product, EPDM, EPDM / EPDM / Examples thereof include styrene or an EPDM / acrylonitrile graft copolymer and a maleic acid modified product thereof, a styrene / maleic acid copolymer, and a reactive phenoxy resin. The amount of the compatibilizing agent is not particularly limited, but it is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the polymer component (the total of the thermoplastic resin and the elastomer component).

  The composition ratio between the specific thermoplastic resin (A) and the elastomer component (B) may be appropriately determined depending on the balance of film thickness, air permeation resistance and flexibility, but a preferred range is 10/90 by weight. It is -90/10, More preferably, it is 20 / 80-85 / 15.

[An endurance test]
FIG. 3 is a table showing the results of a durability test of the pneumatic tire according to the present invention. In this durability test, low temperature durability and rolling resistance were measured using a pneumatic tire 1 having a tire size of 205 / 65R15.

  First, in the low temperature durability test, measurement was performed under an atmospheric temperature of −20 [degree], a tire air pressure of 120 [kPa], a load load factor of 60 [%], and a speed of 80 km / h. The low-temperature durability shown in the figure relates to the travel distance when a crack occurs in the inner liner layer 4 and is indicated by an index based on the conventional example (100).

  Next, in the rolling resistance test, the tire pressure was 200 [kPa], the rim width was 15 × 6 [JJ], the load was 4 [kN], and the speed was 80 km / h. The rolling resistance shown in the figure is preferably as small as possible, and is indicated by an index based on the conventional example (100).

  The uneven thickness gauge d shown in the figure is the thickness dimension of the thickest part of the inner liner layer 4, and the thickness dimension of the tire crown part (that is, the thickness dimension of the conventional example) is used as a reference. Displayed by index. In this durability test, the thickness deviation gauge d is a thickness dimension at the intersection of the perpendicular line 1 drawn from the ground contact end P and the inner liner layer 4. Further, the uneven thickness range shown in the figure is a range in which the inner liner layer 4 is formed thick, and is displayed as a percentage. In addition, in the indication of the uneven thickness range, the symbol CL indicates the range in the tire crown portion CL direction centered on the perpendicular l, and the symbol SW indicates the range with respect to the tire maximum width portion SW direction.

  In this durability test, in the conventional pneumatic tire, the inner liner layer 4 has a uniform thickness dimension of 0.1 [mm]. Therefore, the thickness gauge and the thickness range are not shown for this conventional example.

  In the pneumatic tires 1 of Comparative Examples 1 and 2 and Invention Examples 1 to 3, the inner liner layer 4 has a thick portion. In these pneumatic tires 1, the tire crown portion CL is configured with a thickness dimension of 0.1 [mm], and the thickness dimension in the shoulder portion is larger than the tire crown portion CL and the tire maximum width portion SW. It is configured as follows. For example, in the comparative example 1, since the thickness gauge d is 120, the thickness dimension of the shoulder portion is 0.12 [mm]. In addition, these pneumatic tires 1 are configured such that the uneven thickness range is 10 [%] in the tire crown portion CL direction and 20 [%] in the tire maximum width portion SW direction with the perpendicular l as the center. Specifically, the inner liner layer 4 is formed thick in a range of 10 [mm] in the tire crown CL direction and 10 [mm] in the tire maximum width SW direction with the perpendicular l as the center. .

  As shown in FIG. 3, in the pneumatic tires 1 of Invention Examples 1 to 3, the low temperature durability is remarkably improved (30 [%] to about 200 [%] increase) compared to the conventional example, Moreover, the rolling resistance is maintained at the same (100) as in the conventional example. In Comparative Example 2, the index of rolling resistance increases by 3 [%], which corresponds to about 10% deterioration in fuel consumption when converted to the fuel consumption of an automobile.

  As described above, the pneumatic tire according to the present invention is useful in that the occurrence of cracks in the inner liner layer can be effectively suppressed.

It is sectional drawing of the meridian direction which shows the pneumatic tire concerning Example 1 of this invention. It is an enlarged view which shows the shoulder part of the pneumatic tire described in FIG. It is a graph which shows the result of the durability test of the pneumatic tire concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead core 3 Carcass layer 4 Inner liner layer CL Tire crown part d Thickness gauge l Vertical line P Grounding end SW Tire maximum width part

Claims (6)

In the pneumatic tire in which the inner liner layer is formed on the inner rubber of the carcass layer mounted on the pair of bead portions,
The inner liner layer is made of a thermoplastic resin containing a rubber composition, and a thickness dimension in a shoulder portion is larger than a thickness dimension in a tire crown portion. When a vertical line 1 is drawn in the tire inner diameter direction from the ground contact end P of the tread portion with respect to the boundary line between the inner rubber of the carcass layer and the inner liner layer in a sectional view in the tire meridian direction,
The inner liner layer is thicker than the tire crown portion CL in a range from the perpendicular l to the tire crown portion CL in a range from the perpendicular l to the tire crown portion CL of at least about 10 [%]. The pneumatic tire according to claim 1 formed as described above.   3. The pneumatic tire according to claim 2, wherein a range in which the inner liner layer is formed thick is a range of about 50 [%] or less from the perpendicular l toward the tire crown portion CL. When a vertical line 1 is drawn in the tire inner diameter direction from the ground contact end P of the tread portion with respect to the boundary line between the inner rubber of the carcass layer and the inner liner layer in a sectional view in the tire meridian direction,
The inner liner layer is thicker than the tire crown portion CL in the range from the vertical l to the tire maximum width portion SW, and the range from the vertical l to the tire maximum width portion SW is at least 20%. The pneumatic tire according to claim 1, which is formed as described above.   5. The pneumatic tire according to claim 4, wherein a range in which the inner liner layer is formed thick is a range of about 100 [%] or less from the perpendicular l toward the tire maximum width portion SW.   The pneumatic tire according to any one of claims 1 to 5, wherein the inner liner layer has a thickness dimension of about 160 [%] to about 300 [%] with respect to a thickness dimension of the tire crown portion CL. .

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