tire

Abstract

Provided is a tire in which a reinforcement cord including polyamide multifilaments is used as a reinforcement cord for a reinforcement member of the tire, the tire having improved durability and low rolling resistance.　A tire 10 comprises a belt 2 composed of at least one belt layer on the tire-radius-directional outer side of a carcass 1, at least one cap layer 3a that is positioned on the tire-diameter-directional outer side of the belt 2 and that covers the entire width of the belt 2, and at least a pair of layers 3b covering only the vicinities of both width-directional ends of the belt, wherein: reinforcing cords of the layers 3b include semi-aromatic polyamide multifilaments composed of a polycondensate of a non-aromatic diamine and a dicarboxylic acid containing an aromatic dicarboxylic acid, or a polycondensate of a diamine containing an aromatic diamine and a non-aromatic dicarboxylic acid; and the reinforcing cords in the portions of the cap layer 3a that do not overlap the layers 3b in the tire diameter direction include aliphatic polyamide multifilaments.

Description

[Technical field]

[0001] The present invention relates to a tire, and more particularly to a tire that uses a reinforcing cord containing a polyamide multifilament as a reinforcing cord for a reinforcing member of the tire, thereby improving low rolling resistance and high-speed durability. [Background technology]

[0002] In recent years, environmental problems such as global warming due to an increase in CO2 emissions and resource depletion problems have become more serious. For this reason, tires are being required to be lightweight and fuel-efficient. Conventionally, there has been active improvement and development of rubber properties such as shape, structure, and tread for tires, and weight reduction and fuel efficiency have been achieved by reducing the amount of rubber used and reducing the rolling resistance of tires. Since the rubber components play a major role in rolling resistance, for example, reduction in loss of the rubber components themselves such as tread rubber, bead filler rubber, belt coating rubber, and bead filler rubber, and reduction in distortion of the shape and structure of the rubber components have been studied and optimized.

[0003] Recently, with the progress of reducing the loss of rubber members themselves, the contribution of members other than rubber members to the rolling resistance caused by dynamic repeated strain has become non-negligible. Members other than rubber members include carcass ply layers, belt layers, belt reinforcing layers, etc., and among these, the belt reinforcing layer has a large strain fluctuation during rolling contact, so a technology to reduce the loss of the belt reinforcing layer is desired. Under these circumstances, Patent Document 1 proposes a reinforcing cord material that can be suitably used as a cap ply layer (belt reinforcing layer) in tires, has excellent mechanical properties such as rigidity, thermal properties, etc., and reduces only the loss. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-103913 A Summary of the Invention [Problem to be solved by the invention]

[0005] At present, organic fibers such as polyester, rayon, and nylon are used for tire reinforcing members. Among these, nylon fibers, which are polyamide fibers, have the advantages of being superior in adhesion to rubber and excellent in fatigue resistance compared to other fiber types. However, when these polyamide fibers are used as reinforcing members, the reduction in loss is not necessarily sufficient, and there is a demand for improving rolling resistance without deteriorating high-speed durability.

[0006] Therefore, an object of the present invention is to provide a tire which uses a reinforcing cord containing polyamide multifilaments as the reinforcing cord of the reinforcing member of the tire and which has low rolling resistance and improved high-speed durability. [Means for solving the problem]

[0007] As a result of intensive research into solving the above-mentioned problems, the inventors have found that by using polyamide multifilaments having a specified structure as reinforcing cords in specified portions, it is possible to achieve a high degree of compatibility between low rolling resistance and high-speed durability, thereby solving the above-mentioned problems, and have thus completed the present invention.

[0008] That is, the tire of the present invention is a tire including a belt composed of at least one belt layer on the tire radially outer side of a carcass, at least one cap layer disposed on the tire radially outer side of the belt and covering the entire width of the belt, and at least a pair of layer layers covering only the vicinity of both ends of the belt in the width direction, The reinforcing cord of the layer layer includes a multifilament of semi-aromatic polyamide made of a polycondensate of a dicarboxylic acid including an aromatic dicarboxylic acid and a non-aromatic diamine or a polycondensate of a diamine including a non-aromatic dicarboxylic acid and an aromatic diamine, and the reinforcing cord of the cap layer in a portion not overlapping with the layer layer in the tire radial direction includes a multifilament of aliphatic polyamide.

[0009] In the tire of the present invention, the reinforcing cord in the portion of the cap layer overlapping with the layer layer in the tire radial direction preferably includes the multifilament of the semi-aromatic polyamide. In the tire of the present invention, the semi-aromatic polyamide is preferably a polycondensate of a dicarboxylic acid including an aromatic dicarboxylic acid and a non-aromatic diamine, and the non-aromatic diamine is preferably at least one of an aliphatic diamine and an alicyclic diamine. In the tire of the present invention, the glass transition temperature of the reinforcing cord of the layer layer taken out of the tire is preferably 80 to 230°C. Furthermore, in the tire of the present invention, the ratio E'(100°C) / E'(25°C) of the dynamic modulus of elasticity at 100°C to the dynamic modulus of elasticity at 25°C of the reinforcing cord of the layer layer taken out of the tire is preferably 0.7 to 1.0. Furthermore, in the tire of the present invention, the moisture content of the reinforcing cord of the layer layer taken out of the tire is preferably 0.1 to 2.0 mass%.

[0010] In the tire of the present invention, the ratio of the loss tangent tan δ(25°C) at 25°C to the loss tangent tan δ(100°C) at 100°C of the reinforcing cord of the layer layer taken out of the tire, tan δ(25°C) / tan δ(100°C), is preferably 0.7 to 1.0. In the tire of the present invention, the loss tangent tan δ(25°C) at 25°C of the reinforcing cord of the layer layer taken out of the tire is preferably 0.01 to 0.06. In the tire of the present invention, the ratio of the aromatic dicarboxylic acid to the dicarboxylic acid of the reinforcing cord of the layer layer is preferably 50 mol% or more. In the tire of the present invention, the ratio of the dicarboxylic acid having one aromatic ring to the aromatic dicarboxylic acid is preferably 20 mol% or more, the ratio of the dicarboxylic acid having two aromatic rings to the aromatic dicarboxylic acid is preferably 20 mol% or more, or the ratio of the dicarboxylic acid having three aromatic rings to the aromatic dicarboxylic acid is preferably 20 mol% or more. In the tire of the present invention, the ratio of the diamine having 7 to 12 carbon atoms to the diamine is preferably 20 mol % or more. Furthermore, in the tire of the present invention, the reinforcing cord of the layer may be a hybrid cord of the polyamide multifilament and at least one fiber selected from the group consisting of polyester fiber, nylon fiber, aramid fiber, polyketone fiber, glass fiber, carbon fiber, polyparaphenylene benzobisoxazole fiber, and polyarylate fiber.

[0011] In the tire of the present invention, the reinforcing cord of the layer taken out from the tire has a structure represented by the following formulas (1) and (2): α1=N1×√(0.125×D1 / ρ)×10 -3 (1) α2=N2×√(0.125×D2 / ρ)×10 -3 (2) (N1 is the number of first twists [turns / 10 cm], D1 is the fineness of one first twist yarn [dtex], N2 is the number of first twists [turns / 10 cm], D2 is the total fineness of the cord [dtex], ρ is the density of the reinforcing cord of the layer [g / cm3 ]) is preferably 0.1 to 0.9, and the final twist coefficient α2 is preferably 0.1 to 1.2. Furthermore, in the tire of the present invention, it is preferable that α1 is 0.1 to 0.5, and α2 is 0.1 to 0.7. Furthermore, in the tire of the present invention, it is preferable that the total fineness of the reinforcing cords of the layer layer is 1000 to 8000 dtex. Furthermore, in the tire of the present invention, it is preferable that the number of ply twists N1 of the reinforcing cords is 10 to 30 times / 10 cm. Furthermore, in the tire of the present invention, it is preferable that the number of final twists N2 of the reinforcing cords of the layer layer is 10 to 30 times / 10 cm.

[0012] The tire of the present invention is suitable for use as a passenger vehicle tire.

[0013] Here, the tan δ of the reinforcing cord of the layer layer is a value measured by using a Rheograph Solid, Rheovibron, Spectrometer, Metravib, or the like under the conditions of a reinforcing cord having a length of 5 cm, a predetermined temperature, a measurement frequency of 10 Hz, a static tension of 100 g, and a dynamic repeated strain of 1000 μm. The glass transition temperature (Tg) is a value measured by differential scanning calorimetry (DSC). Furthermore, the dynamic modulus E' of the reinforcing cord of the layer layer can be measured under the same conditions as the measurement of the tan δ of the reinforcing cord. Furthermore, "the ratio of dicarboxylic acid having one aromatic ring to aromatic dicarboxylic acid is 20 mol% or more" means "the ratio of structural units derived from aromatic dicarboxylic acid to structural units derived from raw material monomer components is 10 mol% or more". The same applies to "the ratio of dicarboxylic acids having two aromatic rings to the aromatic dicarboxylic acids is 20 mol% or more," "the ratio of dicarboxylic acids having three aromatic rings to the aromatic dicarboxylic acids is 20 mol% or more," and "the ratio of diamines having 7 to 12 carbon atoms to the diamines is 20 mol% or more." Effect of the Invention

[0014] According to the present invention, a tire can be provided that uses a reinforcing cord containing polyamide multifilaments as the reinforcing cord of the reinforcing member of the tire, thereby achieving both low rolling resistance and high-speed durability. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic cross-sectional view in the tire width direction of a tire according to one preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the tire of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic cross-sectional view in the tire width direction of a tire according to a preferred embodiment of the present invention. A tire 10 of the present invention is a tire including a belt 2 consisting of at least one belt layer on the tire radially outer side of a carcass 1, and at least one belt reinforcing layer 3 covering the entire width of the belt 2 on the tire radially outer side of the belt 2. In the illustrated example, the carcass 1 spanning between a pair of bead cores 4 is made of one carcass ply, the belt 2 is made of two belt layers 2a and 2b, and a bead filler 5 is arranged on the tire radially outer side of the bead core 4.

[0017] In the illustrated example, the belt reinforcing layer 3 is composed of a cap layer 3a arranged to cover the entire belt 2, and a pair of layer layers 3b arranged to cover only both ends of the cap layer 3a. The cap layer 3a is arranged to be continuous from one tire half to the other tire half, intersecting the tire equatorial plane E, while the layer layer 3b is composed of a pair of layers arranged to cover only the ends of the cap layer 3a in each tire half without intersecting the tire equatorial plane E. In the tire 10 of the present invention, the cap layer 3a may be two or more layers, or may be combined with two or more layer layers 3b. The belt reinforcing layer 3 is usually composed of a rubber-coated layer of cords arranged substantially parallel to the tire circumferential direction.

[0018] In the tire 10 of the present invention, the reinforcing cord of the layer 3b includes a multifilament of semi-aromatic polyamide made of a polycondensate of a dicarboxylic acid containing an aromatic dicarboxylic acid and a non-aromatic diamine or a polycondensate of a diamine containing a non-aromatic dicarboxylic acid and an aromatic diamine. The reinforcing cord of the cap layer 3a in the portion not overlapping with the layer 3b in the tire radial direction includes a multifilament of aliphatic polyamide. The semi-aromatic polyamide may be one in which the dicarboxylic acid contains an aromatic dicarboxylic acid, or one in which the diamine contains an aromatic diamine. However, it is particularly preferable that the dicarboxylic acid contains an aromatic dicarboxylic acid, and the diamine is at least one of an aliphatic diamine and an alicyclic diamine.

[0019] Nylon 66 is commonly used as the reinforcing cord for the belt reinforcing layer 3, but this type of reinforcing cord has a low glass transition temperature Tg (50°C), and therefore low rigidity at high temperatures and poor steering stability. On the other hand, reinforcing cords using aramid fibers can ensure rigidity at high temperatures, but have the problem that their rigidity is too high, significantly impairing tire manufacturability.

[0020] In contrast, semi-aromatic polyamide has a high Tg due to intermolecular interactions and also has moderate rigidity, so that by using it as a reinforcing cord for the belt reinforcing layer 3, it is possible to improve the durability and steering stability during high-speed driving without impairing tire productivity. In addition, the loss tangent tan δ in the tire usage area is small, which is advantageous for reducing the rolling resistance of the tire. Furthermore, polyamide fibers made of alicyclic dicarboxylic acids and aliphatic diamines have high water absorption and low stability of physical properties. Furthermore, since semi-aromatic polyamide fibers also have low water absorption, it is possible to ensure stability of physical properties.

[0021] However, in tires designed for high-speed driving, semi-aromatic polyamides do not always have sufficient cord breaking strength or adhesion to rubber, and may not be able to provide sufficient high-speed durability. Here, the cord distortion in the tire is greater in the shoulder section than in the center section, so the loss due to dynamic repeated distortion of the reinforcing cord is higher in the shoulder section. On the other hand, during high-speed driving, the cord load on the center section due to centrifugal force is particularly large, making it prone to failure. Therefore, in the tire 10 of the present invention, aliphatic polyamide multifilaments such as conventional nylon fibers that can ensure durability are used in the center section, and cords containing semi-aromatic polyamide filaments are used as reinforcing cords in the shoulder section, where the effect of reducing rolling resistance is greatly obtained. This allows the tire to achieve both low rolling resistance and high-speed durability at a high level.

[0022] In the tire of the present invention, the reinforcing cord in the portion of the cap layer 3a that overlaps with the layer layer 3b in the tire radial direction is preferably the same as the reinforcing cord in the layer layer 3b, that is, a cord including multifilaments of semi-aromatic polyamide made of a polycondensate of a dicarboxylic acid containing an aromatic dicarboxylic acid and a non-aromatic diamine or a polycondensate of a diamine containing a non-aromatic dicarboxylic acid and an aromatic diamine, thereby making it possible to satisfactorily obtain the above-mentioned effects.

[0023] In the tire 10 of the present invention, the Tg of the reinforcing cord of the layer 3b taken out from the tire 10 is preferably 80 to 230°C. By using a cord having a high Tg as the reinforcing cord of the layer 3b in this manner, the loss tangent tanδ in the tire use region can be reduced, and the rolling resistance of the tire 10 can be improved. The Tg is preferably 100 to 160°C.

[0024] In the tire 10 of the present invention, the ratio of the loss tangent tan δ(25°C) at 25°C to the loss tangent tan δ(100°C) at 100°C of the reinforcing cord of the layer 3b taken out of the tire 10, that is, the value of tan δ(25°C) / tan δ(100°C), is preferably 0.7 to 1.0. In particular, the loss tangent tan δ(25°C) at 25°C of the reinforcing cord of the layer 3b taken out of the tire is preferably 0.01 to 0.06. Since such a reinforcing cord has a low tan δ at high temperatures, it is possible to suppress the generation of heat and maintain the durability of the tire at high speeds. The value of tan δ(25°C) / tan δ(100°C) is preferably 0.85 to 1.0.

[0025] Furthermore, in the tire 10 of the present invention, the ratio E'(100°C) / E'(25°C) of the dynamic modulus of elasticity at 25°C of the reinforcement cord of the layer 3b taken out of the tire 10 to the dynamic modulus of elasticity at 100°C, E'(25°C), is preferably 0.7 to 1.0. By setting the value of E'(100°C) / E'(25°C) within the above range, it is possible to maintain steering stability at high temperatures. In particular, it is preferable that the dynamic modulus of elasticity at 25°C of the reinforcement cord of the layer 3b taken out of the tire is 0.7 to 0.8.

[0026] Furthermore, in the tire 10 of the present invention, the moisture content of the reinforcing cord of the layer 3b taken out from the tire 10 is preferably 0.1 to 2.0 mass%. As described above, the semi-aromatic polyamide fiber relating to the reinforcing cord of the tire 10 of the present invention has low water absorption, and therefore the stability of the cord properties can be ensured. In particular, the effect of the present invention can be favorably obtained when the moisture content is 0.1 to 2.0 mass%.

[0027] The tan δ(25°C) / tan δ(100°C) and E'(100°C) / E'(25°C) values ​​of the reinforcing cords in the layer 3b can be adjusted by appropriately selecting the type of reinforcing cord, the number of twists, the immersion conditions when immersing the surface of the reinforcing cord in the adhesive applied thereto, the type of adhesive, and the conditions of the heat treatment after the adhesive treatment. In the tire 10 of the present invention, the end count of the reinforcing cords in the cap layer 3a and the layer 3b can be appropriately set according to the strength of the reinforcing cord, and is 20 to 100 cords / 50 mm, more preferably 30 to 80 cords / 50 mm, and even more preferably 40 to 60 cords / 50 mm.

[0028] In the tire 10 of the present invention, the reinforcing cord of the layer 3b taken out from the tire is represented by the following formulas (1) and (2): α1=N1×√(0.125×D1 / ρ)×10 -3 (1) α2=N2×√(0.125×D2 / ρ)×10 -3 (2) It is preferable that the first twist coefficient α1 is 0.1 to 0.9 and the final twist coefficient α2 is 0.1 to 1.2, where N1 is the number of first twists [times / 10 cm], D1 is the fineness of one first twist yarn [dtex], N2 is the number of final twists [times / 10 cm], D2 is the total fineness of the cord [dtex], and ρ is the density of the reinforcing cord [g / cm 3 By twisting the multifilament of the semi-aromatic polyamide according to the present invention, the tenacity utilization rate is averaged and the fatigue resistance is improved. In particular, by satisfying the above conditions, it is possible to achieve both the rigidity and fatigue resistance of the reinforcing cord of the layer 3b. The tension during twisting is preferably 0.01 to 0.2 cN / dtex.

[0029] Furthermore, in the tire 10 of the present invention, it is preferable that α1 is 0.1 to 0.5 and α2 is 0.1 to 0.7. By satisfying these conditions, it is possible to achieve a high balance between the rigidity and fatigue resistance of the reinforcing cord of the layer 3b. In particular, it is preferable that the number of first twists N1 of the reinforcing cord of the layer 3b is 10 to 30 times / 10 cm and the number of second twists N2 is 10 to 30 times / 10 cm.

[0030] The reinforcing cord of the layer 3b of the tire 10 of the present invention preferably has a total fineness of 1000 to 8000 dtex. By making the total fineness 1000 dtex or more, sufficient strength can be ensured. On the other hand, from the viewpoint of spinnability and post-processing, the total fineness is preferably 8000 dtex or less. More preferably, the total fineness is 5000 dtex or less.

[0031] In the tire 10 of the present invention, the reinforcing cord of the layer 3b may be a cord made of only multifilaments of semi-aromatic polyamide, or may be a so-called hybrid cord made of other fibers in combination. Examples of the other fibers include at least one fiber selected from the group consisting of polyester fibers, nylon fibers, aramid fibers, polyketone fibers, glass fibers, carbon fibers, polyparaphenylene benzobisoxazole fibers, and polyarylate fibers.

[0032] Next, the material and manufacturing method of the cord using the semi-aromatic polyamide multifilament according to the tire 10 of the present invention will be described in detail. The semi-aromatic polyamide multifilament is a polyamide multifilament made of a polycondensate of a dicarboxylic acid containing an aromatic dicarboxylic acid and a non-aromatic diamine, or a polycondensate of a non-aromatic dicarboxylic acid and a diamine containing an aromatic diamine. The dicarboxylic acid may contain an aromatic dicarboxylic acid, and the diamine may contain an aromatic diamine. In particular, the multifilament made of a polyamide containing an aromatic dicarboxylic acid as the dicarboxylic acid and containing at least one of an aliphatic diamine and an alicyclic diamine as the diamine is preferable.

[0033] <Dicarboxylic acid> In the semi-aromatic polyamide multifilament according to the tire 10 of the present invention, the ratio of aromatic dicarboxylic acid to dicarboxylic acid is preferably at least 50 mol %, more preferably 60 mol % or more, and further preferably 70 mol % or more. This makes it possible to obtain a semi-aromatic polyamide multifilament having high Tg, excellent fiber strength, and excellent spinnability.

[0034] The aromatic dicarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include aromatic dicarboxylic acids having 8 to 20 carbon atoms, which are unsubstituted or substituted with various substituents, such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, etc. These may be used alone or in combination of two or more.

[0035] In the semi-aromatic polyamide multifilament according to the tire 10 of the present invention, as a dicarboxylic acid other than an aromatic dicarboxylic acid, for example, an alicyclic dicarboxylic acid having an alicyclic structure with 3 to 10 carbon atoms, a linear or branched aliphatic dicarboxylic acid having 3 to 20 carbon atoms, etc. can be used.

[0036] Specific examples of alicyclic dicarboxylic acids having 3 to 10 carbon atoms in an alicyclic structure include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid. In the reinforcing cord used in the tire 10 of the present invention, the alicyclic dicarboxylic acid may be unsubstituted or may have a substituent. Examples of the substituent include alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl, but are not limited thereto. Among these, 1,4-cyclohexanedicarboxylic acid is preferred from the viewpoints of heat resistance, dimensional stability, strength, and the like of the reinforcing cord. The alicyclic dicarboxylic acids may be used alone or in combination of two or more.

[0037] Alicyclic dicarboxylic acids have geometric isomers of trans and cis. For example, 1,4-cyclohexanedicarboxylic acid as a raw material monomer may be used either in the trans or cis form, or as a mixture of trans and cis forms in various ratios.

[0038] Examples of linear or branched aliphatic dicarboxylic acids having 3 to 20 carbon atoms include, but are not limited to, malonic acid, dimethylmalonic acid, succinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylglutaric acid, 2,2-diethylsuccinic acid, 2,3-diethylglutaric acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosane diacid, and diglycolic acid.

[0039] In general, when the number of aromatic rings contained in the dicarboxylic acid constituting the polyamide multifilament increases, the binding strength due to the interaction between the aromatic rings in the molecules increases, and Tg increases. Therefore, the aromatic rings contained in the dicarboxylic acid may be adjusted according to the required durability and steering stability during high-speed driving. For example, the ratio of dicarboxylic acid having one aromatic ring to aromatic dicarboxylic acid is 20 mol% or more, the ratio of dicarboxylic acid having two aromatic rings to aromatic dicarboxylic acid is 20 mol% or more, and the ratio of dicarboxylic acid having three aromatic rings to aromatic dicarboxylic acid is 20 mol% or more can be appropriately used. In addition, when the aromatic rings contained in the dicarboxylic acid increase, the melting point (Tm) also increases at the same time, and the spinning workability of the fiber decreases, but it is possible to lower Tm by increasing the number of carbon atoms of the diamine component.

[0040] <Diamine> In the semi-aromatic polyamide multifilament according to the tire 10 of the present invention, from the viewpoints of spinning stability, heat resistance, and low water absorption, the ratio of the diamine having 7 to 12 carbon atoms to the total diamine is preferably 20 mol% or more, more preferably 30 mol% or more and 80 mol% or less, even more preferably 40 mol% or more and 75 mol% or less, and particularly preferably 45 mol% or more and 70 mol% or less.

[0041] Generally, polymers with high Tg tend to have high Tm. If Tm is too high, polyamides undergo thermal decomposition during melting, resulting in a decrease in molecular weight and strength, coloring, and inclusion of decomposition gas, leading to poor spinnability. However, by containing 20 mol% or more of a diamine having 7 to 12 carbon atoms, Tm can be suppressed to a level suitable for melt spinning while maintaining a high Tg. In addition, polyamides containing a diamine having 7 to 12 carbon atoms have high thermal stability during melting, so that multifilaments with excellent spinning stability and good uniformity can be obtained. Furthermore, by reducing the amide group concentration in the polyamide, multifilaments with excellent dimensional stability during water absorption can be obtained. In particular, 1,9-nonanediamine and 1,10-decamethylenediamine are preferable from the viewpoint of achieving both spinning stability and strength.

[0042] The diamine other than 1,9-nonanediamine and 1,10-decamethylenediamine is not particularly limited, and may be an unsubstituted linear aliphatic diamine, a branched aliphatic diamine having a substituent such as an alkyl group having 1 to 4 carbon atoms, or an alicyclic diamine. Examples of the substituent include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Examples of diamines other than 1,9-nonanediamine and 1,10-decamethylenediamine include linear aliphatic diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, undecamethylenediamine, dodecamethylenediamine, and tridecamethylenediamine, 2-methylpentamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2-methyloctamethylenediamine, 2,4-dimethyloctamethylenediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, and 1,3-cyclopentanediamine.

[0043] In the semi-aromatic polyamide multifilament according to the tire 10 of the present invention, an aromatic diamine may be added to the diamine within a range that does not inhibit the fluidity of the polyamide. The aromatic diamine is a diamine containing an aromatic group, and examples thereof include, but are not limited to, meta-xylylenediamine, ortho-xylylenediamine, and para-xylylenediamine.

[0044] As the diamine other than 1,9-nonanediamine and 1,10-decamethylenediamine, a diamine having 5 to 6 carbon atoms is preferably included, and the ratio of the diamine having 5 to 6 carbon atoms is more preferably 20 mol % or more. By copolymerizing a diamine having 5 to 6 carbon atoms other than 1,9-nonanediamine and 1,10-decamethylenediamine, a polymer having high crystallinity can be obtained while maintaining a suitable melting point suitable for spinning. Examples of the diamine having 5 to 6 carbon atoms include pentamethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, 2,5-dimethylhexanediamine, and 2,2,4-trimethylhexamethylenediamine.

[0045] Among the diamines having 5 to 6 carbon atoms, 2-methylpentamethylenediamine is preferred from the viewpoints of spinnability, fluidity, and strength. If the ratio of 2-methylpentamethylenediamine is too high, 2-methylpentamethylenediamine undergoes self-cyclization and decomposes when melted, causing a decrease in molecular weight, resulting in poor spinnability and strength. The ratio of 2-methylpentamethylenediamine in the diamine must be set within a range that ensures fluidity while not causing decomposition when melted, and is preferably 20 mol% or more and 70 mol% or less, more preferably 20 mol% or more and 60 mol% or less, and even more preferably 20 mol% or more and 55 mol% or less.

[0046] Furthermore, among the diamines having 5 to 6 carbon atoms, hexamethylenediamine is preferred from the viewpoint of heat resistance of the reinforcing cord according to the tire 10 of the present invention. If the ratio of hexamethylenediamine is too high, the melting point becomes too high, making spinning difficult, so the ratio of hexamethylenediamine in the diamine is preferably 20 mol% or more and 60 mol% or less, more preferably 20 mol% or more and 50 mol% or less, and even more preferably 20 mol% or more and 45 mol% or less.

[0047] The amount of dicarboxylic acid and the amount of diamine added are preferably about the same molar amount in order to increase the molecular weight. Taking into consideration the amount of diamine that escapes to the outside of the reaction system during the polymerization reaction in the molar ratio, the molar amount of the total diamine is preferably 0.90 to 1.20, more preferably 0.95 to 1.10, and further preferably 0.98 to 1.05, relative to the molar amount of the total dicarboxylic acid of 1.00.

[0048] When polyamide is polymerized from dicarboxylic acid and diamine, a known terminal blocking agent can be further added to adjust molecular weight. Examples of terminal blocking agents include monocarboxylic acid, monoamine, acid anhydride such as phthalic anhydride, monoisocyanate, monoacid halide, monoester, monoalcohol, etc., and from the viewpoint of thermal stability, monocarboxylic acid and monoamine are preferable. One type of terminal blocking agent may be used, or two or more types may be used in combination.

[0049] In the semi-aromatic polyamide multifilament of the reinforcing cord of the layer 3b of the tire 10 of the present invention, the cross ratio is preferably 1.7 or less. The cross ratio is a value obtained by dividing the maximum diameter of the multifilament by the minimum diameter, and is a measure of uniformity between single yarns. Since the strength of the multifilament is pulled by the low physical property in the strength distribution of the single yarns, if the variation between the single yarns is large, the strength is not developed. Therefore, in the semi-aromatic polyamide multifilament of the tire 10 of the present invention, the cross ratio is preferably 1.7 or less, more preferably 1.6 or less, and even more preferably 1.5 or less. By having a cross ratio of 1.7 or less, drawing at the single yarn level is performed uniformly, the variation in single yarn strength is small, and excellent strength is developed as a semi-aromatic polyamide multifilament. The lower limit of the cross ratio is 1.0.

[0050] <Method of producing semi-aromatic polyamide> Examples of methods for producing semi-aromatic polyamides include (1) a method in which an aqueous solution or suspension of a dicarboxylic acid / diamine salt or a mixture thereof is heated and polymerized while maintaining the molten state (thermal melt polymerization method), (2) a method in which the degree of polymerization of the polyamide obtained by the thermal melt polymerization method is increased while maintaining the solid state at a temperature below the melting point (thermal melt polymerization / solid-state polymerization method), (3) a method in which an aqueous solution or suspension of a diamine / dicarboxylate salt or a mixture thereof is heated and the precipitated prepolymer is further melted again in an extruder such as a kneader to increase the degree of polymerization (prepolymer / extrusion polymerization method), (4) a method in which an aqueous solution or suspension of a diamine / dicarboxylate salt or a mixture thereof is heated and the precipitated prepolymer is further melted again in a temperature below the melting point of the polyamide to increase the degree of polymerization while maintaining the solid state (prepolymer / solid-state polymerization method), (5) a method in which a diamine / dicarboxylate salt or a mixture thereof is polymerized while maintaining the solid state (solid-state polymerization method), and (6) a method in which a dicarboxylic acid halide component equivalent to the dicarboxylic acid and a diamine component are polymerized (solution method).

[0051] As a method for producing semi-aromatic polyamide, it is preferable to produce polyamide by (1) hot melt polymerization method or (2) hot melt polymerization / solid phase polymerization method, because it is easy to maintain the trans isomer ratio at 85% or less and the color tone of the obtained polyamide is excellent. The polymerization form may be a batch type or a continuous type. The polymerization apparatus is not particularly limited, and known apparatuses such as an autoclave type reactor, a tumbler type reactor, and an extruder type reactor such as a kneader can be mentioned.

[0052] <Semi-aromatic polyamide multifilament> The semi-aromatic polyamide multifilament according to the tire 10 of the present invention is obtained by fiberizing the semi-aromatic polyamide described above. Various methods can be used to manufacture the semi-aromatic polyamide multifilament, but melt spinning is usually used, and it is preferable to carry out the method using a screw-type melt extruder. The polyamide spinning temperature (melting temperature) is preferably 300°C or higher and 360°C or lower. If it is 300°C or higher, it is possible to suppress the inclusion of unmelted matter due to insufficient heat. If it is 360°C or lower, the thermal decomposition of the polymer and the generation of decomposition gas are significantly reduced, and the spinnability is improved.

[0053] For the semi-aromatic polyamide multifilament cord of the tire 10 of the present invention, it is preferable to use an adhesive for bonding the rubber constituting the tire and the semi-aromatic polyamide multifilament cord, and a resorcin-formalin-latex liquid (RFL liquid) is preferable as this adhesive.

[0054] After the RFL liquid is applied, the RFL liquid is dried, fixed, and relaxed. The drying temperature of the RFL liquid is preferably 120 to 250°C, more preferably 140 to 200°C, and the drying time is preferably 10 seconds or more, more preferably 20 to 120 seconds. The twisted yarn after drying is subsequently subjected to heat treatment in the heat setting zone and normalizing zone. The temperature and time in the heat setting zone and normalizing zone are preferably 150 to 250°C and 10 to 300 seconds, respectively. At this time, the yarn is stretched by 2% to 10%, and preferably by 3% to 9%.

[0055] The tire 10 of the present invention comprises a belt 2 consisting of at least one belt layer on the tire radial outer side of the carcass 1, at least one cap layer 3a arranged on the tire radial outer side of the belt 2 and covering the entire width of the belt 2, and at least a pair of layer layers 3b covering both ends in the width direction of the belt 2, in which the reinforcing cord of the layer layer 3b contains a multifilament of semi-aromatic polyamide consisting of a polycondensate of a dicarboxylic acid containing an aromatic dicarboxylic acid and a non-aromatic diamine or a polycondensate of a diamine containing a non-aromatic dicarboxylic acid and an aromatic diamine, and the reinforcing cord of the cap layer 3a in the tire radial direction that does not overlap with the layer layer 3b contains a multifilament of aliphatic polyamide, and there is no particular limitation, and a known structure can be adopted. In the tire 10 of the present invention, it is sufficient that at least one layer of the cap layer 3a is made of the above-mentioned rubber-cord composite, and the other layers may have a conventional structure.

[0056] For example, in the example shown in FIG. 1, the carcass 1 is composed of one carcass ply, but in the tire 10 of the present invention, the number of layers of the carcass ply is not limited to this, and may be two or more layers. In addition, a known organic fiber cord can be used as the reinforcing cord of the carcass 1, and the angle of the carcass cord can be in a direction substantially perpendicular to the tire circumferential direction, for example, 70 to 90 degrees. As the organic fiber cord, a known cord that is usually used can be used. For example, a cord made of nylon or polyethylene terephthalate (PET) can also be used. Furthermore, the locking structure of the carcass ply in the bead portion is not limited to the structure in which it is wound around the bead core 4 and locked as shown in the figure, and may be a structure in which the end of the carcass ply is sandwiched between two layers of bead cores (not shown).

[0057] In the tire 10 shown in the figure, the belt 2 is composed of two belt layers 2a and 2b, but in the tire 10 of the present invention, the belt layer may be three or more layers. The belt layer may be a rubberized layer of cords extending at an inclination of, for example, ±15 to 40° with respect to the tire circumferential direction, preferably a rubberized layer of metal cords such as steel. For example, the two belt layers 2a and 2b shown in the figure may be crossing layers in which the metal cords constituting each belt layer cross each other with the tire equatorial plane E in between. The metal cord may be a metal cord in which a plurality of metal filaments are twisted together, or may be a bundle of a plurality of metal filaments that are not twisted together. Furthermore, a plurality of metal filaments may be arranged in parallel without twisting, and in this case, the metal filaments may be straight or shaped.

[0058] Examples of the form of a metal cord in which multiple metal filaments are arranged in parallel without being twisted together include metal filaments arranged in parallel in a bundle of preferably 2 or more, more preferably 5 or more, and preferably 20 or less, more preferably 12 or less, even more preferably 10 or less, and particularly preferably 9 or less.

[0059] A rubber-metal cord composite having a metal cord in which multiple metal filaments are arranged in parallel without being twisted together or a bundle of metal cords can be manufactured by a known method. For example, the metal cords can be arranged in parallel at a predetermined interval and coated from above and below with an elastomer sheet having a thickness of about 0.5 mm. The metal filaments can also be shaped by a conventional method using a normal shaping machine.

[0060] Furthermore, in the tire 10 of the present invention, although not shown, an inner liner may be disposed in the innermost layer. In the tire 10 of the present invention, as the gas filled in the tire, normal air or air with a changed oxygen partial pressure, or an inert gas such as nitrogen can be used. The tire of the present invention is suitable for passenger car tires. EXAMPLES

[0061] The tire of the present invention will now be described in more detail with reference to examples. <Examples and Comparative Examples> A tire of the type shown in FIG. 1 was produced with a tire size of 205 / 55R16. The carcass is composed of a single carcass ply arranged in a direction substantially perpendicular to the tire circumferential direction. A belt consisting of two belt layers is arranged on the tire radially outer side of this carcass, and one cap layer and one layer of layer are arranged as belt reinforcing layers on the tire radially outer side of this belt so as to be substantially parallel (0° to 5°) to the tire circumferential direction. The configurations of the cap layer 3a and layer layer 3b are as shown in Table 1. In the table, the semi-aromatic polyamide mainly consists of terephthalic acid and 1,9-diaminenonane. The physical properties of the reinforcing cord are as follows.

[0062] Code structure: 1400dtex / 2 Aromatic dicarboxylic acid ratio: 100 mol% Tg: 139℃ Tan δ(25℃):0.05 Tan δ(100℃):0.05 tanδ(25℃) / tanδ(100℃):1.0 E'(100℃): 3.6GPa E'(25℃):4.7GPa E'(100℃) / E'(25℃):0.77 Moisture content: 1.3% by mass N1:26 times / 10cm N2: 26 times / 10cm α1:0.32 α2:0.46

[0063] The rolling resistance and high-speed durability of the obtained tires were evaluated according to the following procedure. Note that the Tg, tan δ(25°C) / tan δ(100°C), and E'(100°C) / E'(25°C) values ​​of the cord made of semi-aromatic polyamide multifilament were adjusted by adjusting the ratio of aromatic dicarboxylic acid to dicarboxylic acid, the number of twists, the immersion conditions when immersed in adhesive, and the conditions of heat treatment after adhesive treatment.

[0064] <Rolling resistance> Each tire was mounted on a regular rim specified by JATMA, inflated to the appropriate internal pressure, and loaded with the appropriate load in a drum test at a speed of 80 km / h. The resistance of each tire in Comparative Example 1 and Comparative Example 2 was measured directly, and in Example 1 and Example 2, the resistance of each tire was estimated and calculated based on the cord structure, fiber type, and the results of the Comparative Example, for evaluation. The smaller the index value, the smaller the rolling resistance and the more excellent it is. The results obtained are shown in Table 1.

[0065] <High speed durability> The obtained tires were mounted on regular rims specified by JATMA, inflated to the appropriate internal pressure, and loaded with the appropriate load. The tires were run on a drum tester starting at a speed of 120 km / h, stepping up the speed by 10 km / h every 20 minutes, and the speed at which each tire failed was measured for Comparative Example 1 and Comparative Example 2. In Example 1 and Example 2, the high-speed durability of each tire was evaluated based on the cord structure, fiber type, and the results of the comparative example. ◎ indicates that the tire is equivalent to a conventional tire, and ◯ indicates that the tire is inferior to a conventional tire, but has sufficient performance in terms of practicality. The results are also shown in Table 1.

[0066] [Table 1] *1: The part of the cap layer that overlaps with the layer layer in the radial direction of the tire. *2: The part of the cap layer that does not overlap with the layer layer in the radial direction of the tire. *3: Nylon 66

[0067] From the above, it is evident that the tire of the present invention has improved rolling resistance and durability. [Explanation of symbols]

[0068] 10 Tires 1. Carcass 2 Belt 3 Belt reinforcement layer 3a Cap layer 3b Layer 4 Bead Core 5 Bead Filler

Claims

1. A tire including a belt composed of at least one belt layer on the radially outer side of a carcass, at least one cap layer disposed on the radially outer side of the belt and covering the entire width of the belt, and at least a pair of layer layers covering only the vicinity of both ends of the belt in the width direction, The reinforcing cord of the layer includes a multifilament of semi-aromatic polyamide made of a polycondensate of a dicarboxylic acid including an aromatic dicarboxylic acid and a non-aromatic diamine or a polycondensate of a non-aromatic dicarboxylic acid and a diamine including an aromatic diamine, A tire characterized in that a reinforcing cord in a portion of the cap layer that does not overlap with the layer layer in the tire radial direction contains aliphatic polyamide multifilaments.

2. The tire according to claim 1 , wherein a reinforcing cord in a portion of the cap layer that overlaps with the layer layer in the tire radial direction includes multifilaments of the semi-aromatic polyamide.

3. 3. The tire according to claim 1, wherein the semi-aromatic polyamide is a polycondensate of a dicarboxylic acid, including an aromatic dicarboxylic acid, and a non-aromatic diamine.

4. The tire according to any one of claims 1 to 3, wherein the non-aromatic diamine is at least one of an aliphatic diamine and an alicyclic diamine.

5. The tire according to any one of claims 1 to 4, wherein the glass transition temperature of the reinforcing cord of the layer taken out from the tire is 80 to 230°C.

6. The tire according to any one of claims 1 to 5, wherein the ratio E'(100°C) / E'(25°C) of the dynamic modulus of elasticity E'(100°C) at 100°C to the dynamic modulus of elasticity E'(25°C) at 25°C of the reinforcement cord of the layer removed from the tire is 0.7 to 1.

0.

7. The tire according to any one of claims 1 to 6, wherein the moisture content of the reinforcing cord of the layer taken out from the tire is 0.1 to 2.0 mass %.

8. The tire according to any one of claims 1 to 7, wherein the ratio of the loss tangent tan δ(25°C) at 25°C to the loss tangent tan δ(100°C) at 100°C of the reinforcement cord of the layer removed from the tire, tan δ(25°C) / tan δ(100°C), is 0.7 to 1.

0.

9. 9. The tire according to claim 1, wherein the loss tangent tan δ(25° C.) at 25° C. of the reinforcing cord of the layer taken out from the tire is 0.01 to 0.

06.

10. The tire according to any one of claims 1 to 9, wherein a ratio of the aromatic dicarboxylic acid to the dicarboxylic acid in the reinforcing cord of the layer is 50 mol % or more.

11. The tire according to any one of claims 1 to 10, wherein a ratio of a dicarboxylic acid having one aromatic ring to the aromatic dicarboxylic acid in the reinforcing cord of the layer is 20 mol % or more.

12. The tire according to any one of claims 1 to 10, wherein a ratio of a dicarboxylic acid having two aromatic rings to the aromatic dicarboxylic acid in the reinforcing cord of the layer is 20 mol % or more.

13. The tire according to any one of claims 1 to 10, wherein a ratio of a dicarboxylic acid having three aromatic rings to the aromatic dicarboxylic acid in the reinforcing cord of the layer is 20 mol % or more.

14. The tire according to any one of claims 1 to 13, wherein a ratio of the non-aromatic diamine having 7 to 12 carbon atoms to the non-aromatic diamine in the reinforcing cord of the layer is 20 mol % or more.

15. The reinforcing cord of the layer taken out from the tire has a structure represented by the following formula (1) or (2): α1=N1×√(0125×D1 / ρ)×10 －３ (1) α2=N2×√(0.125×D2 / ρ)×10 －３ (2) (N1 is the number of first twists [turns / 10 cm], D1 is the fineness [dtex] of one first twist yarn, N2 is the number of second twists [turns / 10 cm], D2 is the total fineness [dtex] of the cord, and ρ is the density [g / cm ３ 15. The tire according to claim 1, wherein the ply twist coefficient α1, expressed as: (a) is 0.1 to 0.9, and the top twist coefficient α2, expressed as: (b) is 0.1 to 1.

2.

16. The tire according to claim 15, wherein said α1 is 0.1 to 0.5, and said α2 is 0.1 to 0.

7.

17. The tire according to any one of claims 1 to 16, wherein the total fineness of the reinforcing cords in the layer is 1,000 to 8,000 dtex.

18. The tire according to any one of claims 15 to 17, wherein the number of ply twists N1 of the reinforcing cords in the layer is 10 to 30 twists / 10 cm.

19. The tire according to any one of claims 15 to 18, wherein the number of final twists N2 of the reinforcing cords in the layer is 10 to 30 twists / 10 cm.

20. The tire according to any one of claims 1 to 19, which is for a passenger car.

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