Laminate and tire

Abstract

To provide a laminate excellent in elongation at break after heat deterioration while maintaining initial adhesiveness between a metal reinforcing material and a rubber layer.SOLUTION: There is provided a laminate that comprises a metal reinforcing material 10 and two or more rubber layers 20, wherein the rubber layer has at least an α layer 20A in contact with the metal reinforcing material and a β layer 20B in contact with the α layer; both the α layer and the β layer include a rubber component containing 60 to 100 mass% of an isoprene skeleton rubber and carbon black having a ratio (N2SA / IA) between a nitrogen adsorption specific surface area (N2SA) m2 / g and an iodine adsorption amount (IA) mg / g (N2SA / IA) is 1.2 m2 / mg or less; and the β layer further contains 0.1 to 11 pts.mass of an amine antioxidant represented by the following general formula (1) based on 100 pts.mass of the rubber component, in which in the formula, R1 and R2 are each independently a monovalent saturated hydrocarbon group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to laminates and tires. [Background technology]

[0002] For rubber products requiring particularly high strength, such as automobile tires and hoses, steel cord-rubber composites are used to reinforce the rubber and improve its strength and durability. These composites consist of a steel cord or other metal reinforcing material covered with coated rubber. In order for such steel cord-rubber composites to exhibit a high reinforcing effect and achieve reliability, stable and strong adhesion is necessary between the coated rubber and the metal reinforcing material.

[0003] To obtain a steel cord-rubber composite that exhibits such high adhesion between the coated rubber and the metal reinforcing material, a so-called direct vulcanization bonding method is widely used, in which metal reinforcing materials such as steel cords plated with zinc, brass, etc., are embedded in a coated rubber compounded with sulfur, and these are bonded simultaneously with the vulcanization of the rubber during heat vulcanization. To date, various studies have been conducted on this direct vulcanization bonding method in order to further improve the adhesion between the coated rubber and the metal reinforcing material.

[0004] For example, Patent Document 1 discloses a method for manufacturing a steel cord for reinforcing a steel cord-rubber composite, which is made by twisting together multiple filaments produced by wet drawing brass-plated steel wire. This method involves adding resorcinol to the wet lubricant used during steel wire drawing as an adhesion improver between the steel cord and the coating rubber, thereby causing resorcinol to adhere to the filament surface. However, with the method described in Patent Document 1, if the resorcinol is altered by the heat generated during steel filament drawing, it may not be able to be expected to have a sufficient effect as an adhesion improver between the steel cord and the coating rubber. Therefore, some kind of alternative method was required.

[0005] In general, in order to improve the initial adhesiveness between the coated rubber and the metal reinforcing material in direct vulcanization adhesion used for tires and the like, a rubber composition containing a cobalt salt, which is an adhesion promoter, in the coated rubber has been adopted. However, from the viewpoint of improving the durability against deterioration and crack growth of the coated rubber, it is desirable to reduce such cobalt salt as much as possible.

[0006] Therefore, Patent Document 2 discloses a technique for improving the initial adhesiveness and heat-resistant adhesiveness between the coated rubber and the steel cord even when the cobalt salt, which is an adhesion promoter, is reduced by using a steel cord in which a specific metal can exist at a specific ratio on the outermost surface.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] According to the technique of Patent Document 2, good adhesiveness (initial adhesiveness) between the rubber and the metal reinforcing material (steel cord) can be obtained. However, in recent years, with the increasing performance of rubber articles such as tires, the requirements for the adhesiveness between the rubber and the metal reinforcing material are considered to be increasingly strict. While maintaining the initial adhesiveness, improvement in the elongation at break after heat deterioration is also desired. Also, from the viewpoint of environmental load, it is desirable to reduce cobalt contained in the rubber and steel cord as much as possible. Even when cobalt is not used or the amount of cobalt used is small, the development of a technique with excellent adhesiveness between the rubber and the metal cord has been desired.

[0009] Therefore, an object of the present invention is to provide a laminate that maintains the initial adhesiveness between a metal reinforcing material and a rubber layer and has excellent elongation at break after heat deterioration. Another object of the present invention is to provide a tire having excellent durability of a member using such a laminate.

Means for Solving the Problems

[0010] The gist of the present invention for solving the above problems is as follows. The laminate of the present invention is a laminate comprising a metal reinforcing material and two or more rubber layers, wherein the rubber layer has at least an α layer in contact with the metal reinforcing material and a β layer in contact with the α layer, both the α layer and the β layer contain a rubber component containing 60 to 100% by mass of an isoprene skeleton rubber, and carbon black having a ratio (N2SA / IA) of nitrogen adsorption specific surface area (N2SA) m 2 / g to iodine adsorption amount (IA) mg / g of 1.2 m 2 / mg or less, and the β layer further contains an amine-based antioxidant represented by the following general formula (1):

Chemical formula

[0011] In the laminate of the present invention, it is preferable that the α layer further contains 0.1 to 11 parts by mass of the amine-based antioxidant represented by the general formula (1) with respect to 100 parts by mass of the rubber component. This is because it is possible to further increase the elongation at break after heat deterioration while maintaining the initial adhesiveness between the metal reinforcing material and the rubber layer.

[0012] Furthermore, in the laminate of the present invention, R in the general formula (1) 1 and R 2 However, it is preferable that each is independently a monovalent saturated hydrocarbon group having 1 to 20 carbon atoms in a chain or cyclic configuration. This is because it is possible to maintain the initial adhesion between the metal reinforcement and the rubber layer while further increasing the elongation at break after thermal degradation.

[0013] Furthermore, in the laminate of the present invention, it is preferable that the α layer does not contain silica. This is because it is possible to suppress the deterioration of the performance of the α layer while maintaining the heat-resistant adhesion between the metal reinforcement and the rubber layer.

[0014] Furthermore, in the laminate of the present invention, it is preferable that the α layer and / or the β layer do not contain N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine as an antioxidant. This is because it can further reduce the burden on the environment.

[0015] Furthermore, in the laminate of the present invention, it is preferable that the α layer constitutes the coating rubber layer of the belt, that the carbon black content in the β layer is less than 50 parts by mass per 100 parts by mass of the rubber component, and that the β layer does not contain cobalt. This is because the elongation at break after thermal degradation is effective while maintaining the initial adhesion between the metal reinforcement and the rubber layer.

[0016] Furthermore, in the laminate of the present invention, it is preferable that the α layer constitutes the coating rubber layer of the ply, and that the β layer does not contain silica. This is because the initial adhesion between the metal reinforcement and the rubber layer is maintained while the elongation at break after thermal degradation is effectively utilized.

[0017] The tire of the present invention is characterized by using the laminated material of the present invention as described above. The above configuration makes it possible to provide a component that maintains initial adhesion while exhibiting excellent elongation when cut after thermal degradation. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a laminate that maintains initial adhesion between the metal reinforcement and the rubber layer while exhibiting excellent elongation at the time of cutting after thermal degradation. Furthermore, according to the present invention, it is possible to provide a tire with excellent durability for components using a lightweight laminate. [Brief explanation of the drawing]

[0019] [Figure 1] This figure schematically shows a cross-section of a laminate according to one embodiment of the present invention. [Modes for carrying out the invention]

[0020] The laminate and tire of the present invention will be described in detail below based on their embodiments. Figure 1 is a schematic diagram showing a cross-section of one embodiment of the laminate of the present invention. <Laminate> As shown in Figure 1, the laminate of the present invention is a laminate 1 comprising a metal reinforcing material 10 and two or more rubber layers 20. The components of the laminate of the present invention will be described below.

[0021] (Metal reinforcement) The laminate of the present invention comprises a metal reinforcing material. The aforementioned metal reinforcing material is not particularly limited as long as it is a reinforcing member containing metal, and examples include metal cords and metal plates. Among these, metal cords are preferable from the standpoint of application to tires.

[0022] The aforementioned metal cord may be either a metal monofilament or a multifilament (twisted cord or bundled cord), and its shape is not limited. There are also no particular restrictions on the twisting structure when the metal cord is a twisted cord, and examples of twisting structures include single twist, double twist, layer twist, and composite twist of double twist and layer twist. Examples of these metal cords include cords made of metals such as steel, iron, and copper, and it is preferable that the surface is treated with plating, adhesive treatment, or other surface treatments to ensure suitable adhesion with the rubber composition.

[0023] Furthermore, the surface of the filament may be plated. Examples of plating types include zinc (Zn) plating, copper (Cu) plating, tin (Sn) plating, brass (copper-zinc (Cu-Zn) plating), bronze (copper-tin (Cu-Sn)) plating, and ternary plating containing copper, zinc, and cobalt. Among these, brass plating and ternary plating containing copper, zinc, and cobalt are preferred.

[0024] (Rubber layer) As shown in Figure 1, the laminate of the present invention comprises two or more rubber layers 20, and each rubber layer 20 has at least an α layer 20A in contact with the metal reinforcing material 10 and a β layer 20B in contact with the α layer. Furthermore, depending on the application of the laminate of the present invention, the rubber layer 20 may also have a further rubber layer (not shown) in addition to the α layer 20A and β layer 20B.

[0025] Both the α layer and the β layer are composed of a rubber composition containing rubber components and carbon black. Hereinafter, the rubber composition constituting the α layer may be referred to as the "α layer rubber composition," the rubber composition constituting the β layer as the "β layer rubber composition," and a rubber composition that meets the conditions for both the α and β layers may simply be referred to as the "rubber composition."

[0026] Furthermore, in the present invention, both the α layer and the β layer contain a rubber component containing 60 to 100% by mass of isoprene skeleton rubber, and a nitrogen adsorption specific surface area (N2SA) m 2 The ratio of iodine adsorption capacity (IA) mg / g to iodine adsorption capacity (N2SA / IA) is 1.2m 2 Includes carbon black with a concentration of less than / mg. Since the N2SA / IA is small, the number of surface functional groups of carbon black decreases, so the reactivity between the rubber component mainly composed of isoprene skeleton rubber and carbon black is suppressed, and network formation progresses. As a result, the crack growth resistance of the rubber layer after vulcanization increases, and consequently, the adhesion between the metal reinforcing material and the rubber layer is improved.

[0027] · Rubber component The α layer and the β layer contain a rubber component containing 60 to 100% by mass of isoprene skeleton rubber. Here, the isoprene skeleton rubber is a rubber having an isoprene unit as a main skeleton, and specifically, natural rubber (NR), synthetic isoprene rubber (IR), etc. are exemplified. By containing 60 to 100% by mass of the isoprene skeleton rubber, the effects of the present invention described below (the effect of improving ozone resistance by combined use with an amine-based antioxidant, the effect of suppressing the decrease in elongation at break (EB) and tensile strength (TB) after aging) are likely to appear significantly, and as a result, the crack growth resistance of the rubber layer after vulcanization also increases, which can contribute to the adhesion between the metal reinforcing material and the rubber layer. From the same viewpoint, the content of the isoprene skeleton rubber in the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and may be even preferably 100% by mass.

[0028] In addition to the isoprene skeleton rubber, the rubber component may also contain diene rubbers such as styrene-butadiene rubber (SBR), butadiene rubber (BR), and chloroprene rubber (CR). By containing these rubbers, the rubber elasticity of the rubber composition is excellent, and it becomes a rubber composition more suitable for tire applications. In addition, depending on the performance required for the α layer and the β layer, in addition to the diene rubber, a non-diene rubber may further be contained.

[0029] · Carbon black The α layer and the β layer further contain carbon black having a ratio (N2SA / IA) of nitrogen adsorption specific surface area (N2SA) to iodine adsorption amount (IA) of 1.2 m 2 / mg or less in addition to the rubber component. N2SA / IA is the ratio of nitrogen adsorption specific surface area (N2SA) [m²] to iodine adsorption number (IA) [mg / g]. 2 The value is [ / g], and the unit of N2SA / IA is [m 2 / g] / [mg / g]=[m 2 It is [ / mg].

[0030] A low N2SA / IA value indicates fewer surface functional groups in the carbon black, which suppresses the reactivity between the rubber component and the carbon black. This promotes the formation of a network between carbon blacks via resins, resulting in superior crack propagation resistance of the vulcanized rubber and excellent adhesion between the metal reinforcement and the vulcanized rubber. From the perspective of further enhancing network formation between carbon blacks, N2SA / IA is 1.10m 2 It is preferable that the value be less than / mg, and 1.06m 2 It is more preferable that the N2SA / IA ratio is 0.85m 2 Carbon black with a density smaller than / mg is difficult to obtain, and the reactivity between the rubber component and the carbon black enhances the formation of networks between the carbon black particles. Therefore, N2SA / IA is 0.90m 2 Preferably, it is 0.93m or more. 2 It is more preferable that it be 0.94m or more. 2 / It is even more preferable that the amount be mg or more.

[0031] The nitrogen adsorption specific surface area (N2SA) is 70-90 m². 2 It is preferable that the amount be / g, which is 75-85m 2It is more preferable that the ratio is / g. This allows for optimization of the carbon black structure, which further improves low heat generation, crack propagation resistance, and adhesion between the metal reinforcement and the rubber. The carbon black structure refers to the size of the structure (aggregate of carbon black particles) formed as a result of the fusion and connection of spherical carbon black particles. The nitrogen adsorption specific surface area can be measured by the single-point method in accordance with ISO 4652-1. For example, after immersing degassed carbon black in liquid nitrogen, the amount of nitrogen adsorbed on the carbon black surface at equilibrium is measured, and the specific surface area (m²) is calculated from the measured value. 2 It is possible to calculate ( / g).

[0032] The iodine adsorption amount (IA) is preferably 60 to 120 mg / g, and more preferably 70 to 100 mg / g. By keeping it within this range, the low heat generation properties of the rubber can be improved by optimizing the surface area. The amount of iodine adsorbed can be measured using a method compliant with JIS K6217-1 (2008) [Carbon black for rubber - Basic properties - Part 1: Method for determining the amount of iodine adsorbed (titration method)].

[0033] Furthermore, carbon black has a DBP (dibutyl phthalate) absorption capacity of 50-100 cm³. 3 It is preferable that the amount is / 100g. DBP absorption capacity: 50-100cm 3 The DBP absorption rate of carbon black is 90 cm³ / 100g. By using carbon black with a low structure, it is possible to achieve both reinforcing properties and appropriate flexibility in the rubber composition, resulting in superior crack propagation resistance. 3 It is more preferable that the weight be 100g or less, and 80cm 3 It is even more preferable that the amount be 100g or less. Furthermore, the DBP absorption amount of carbon black represents the amount of DBP (dibutyl phthalate) absorbed by 100g of carbon black, and can be measured using a method compliant with JIS K 6217-4 (2008).

[0034] The carbon black type is N2SA / IA, 1.2m 2 As long as the concentration is less than / mg, there are no particular limitations, and any hard carbon manufactured by the oil furnace method can be used, for example. Among these, it is preferable to use HAF grade carbon black from the viewpoint of achieving better low heat generation and crack propagation resistance, as well as adhesion between the metal reinforcement and the rubber.

[0035] Furthermore, the carbon black content in the rubber composition constituting the α layer and the β layer is preferably 35 to 45 parts by mass per 100 parts by mass of rubber component. By setting the carbon black content to 35 parts by mass or more per 100 parts by mass of rubber component, high reinforcing properties, crack propagation resistance, and adhesion between the metal reinforcing material and rubber can be obtained, while setting it to 45 parts by mass or less can further improve low heat generation. • Anti-aging agent In the laminate of the present invention, the β layer of the rubber layer further contains, in addition to the rubber components and carbon black described above, an amine-based antioxidant represented by the following general formula (1). [ka] [In the formula, R 1 and R 2 These are each independently monovalent saturated hydrocarbon groups.

[0036] Conventionally, in laminates formed from multiple rubber layers, the antioxidant can migrate from one rubber layer to another (for example, from the β layer to the α layer) due to the concentration gradient of the antioxidant contained in each layer. When the antioxidant migrates to the rubber at the adhesive interface (α layer), there is a problem in that the adhesion between the rubber and the metal reinforcement decreases due to the effect of the highly concentrated antioxidant. This problem is often observed when used at high temperatures, so there has been a strong desire to improve the elongation at break of the β layer after thermal degradation. Therefore, in the laminate of the present invention, by using an antioxidant in the β layer that moves more slowly in the rubber compared to other antioxidants (an amine-based antioxidant represented by the general formula (1) above), it is possible to prevent the antioxidant from becoming highly concentrated in the α layer and to increase the elongation of the β layer at the time of cutting after thermal degradation of the rubber layer and the metal member.

[0037] Furthermore, the amine-based antioxidant represented by the above general formula (1) contains a phenylenediamine moiety, similar to N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antioxidant 6PPD), but differs from antioxidant 6PPD in that it does not have double bonds other than the phenylenediamine moiety, thus having a lower environmental impact. Furthermore, the amine-based antioxidant represented by general formula (1) also has the effect of improving the ozone resistance of rubber compositions and suppressing the decrease in the maintenance rate of elongation at break (EB) and tensile strength (TB) after aging.

[0038] Here, in the general formula (1) above, R 1 and R 2 These are each independently monovalent saturated hydrocarbon groups. 1 and R 2 These may be the same or different, but from a synthesis standpoint, it is preferable that they be the same.

[0039] Furthermore, the number of carbon atoms in the monovalent saturated hydrocarbon group is preferably 1 to 20, more preferably 3 to 10, and particularly preferably 6 and 7. When the number of carbon atoms in the saturated hydrocarbon group is 20 or less, the number of moles per unit mass increases, which enhances the anti-aging effect, further suppresses the decrease in adhesive strength between the rubber and the metal cord, and improves the ozone resistance of the rubber composition. From a similar viewpoint, R in the above general formula (1) 1 and R 2 Preferably, each of these is an independent monovalent saturated hydrocarbon group having 1 to 20 carbon atoms in a chain or cyclic configuration.

[0040] Here, examples of the monovalent saturated hydrocarbon group include alkyl groups and cycloalkyl groups. The alkyl group may be linear or branched, and the cycloalkyl group may have further alkyl groups or the like bonded to it as substituents. Examples of the alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1,2-dimethylpentyl group, 1,3-dimethylpentyl group, 1,4-dimethylpentyl group, 2,3-dimethylpentyl group, 2,4-dimethylpentyl group, 3,4-dimethylpentyl group, n-hexyl group, 1-methylhexyl group, 2-methylhexyl group, various octyl groups, various decyl groups, various dodecyl groups, etc., and among these, 1,4-dimethylpentyl group is preferred. Examples of the cycloalkyl group include cyclopentyl group, methylcyclopentyl group, cyclohexyl group, methylcyclohexyl group, cycloheptyl group, and cyclooctyl group, among which the cyclohexyl group is preferred.

[0041] Furthermore, specific examples of amine-based antioxidants represented by the above general formula (1) include N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (antioxidant 77PD), N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine, and N,N'-dicyclohexyl-p-phenylenediamine (antioxidant CCPD). Among these, N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (antioxidant 77PD) and N,N'-dicyclohexyl-p-phenylenediamine (CCPD) are preferred, and N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (antioxidant 77PD) is particularly preferred. The amine-based antioxidants may be used individually or in combination of two or more.

[0042] Furthermore, the content of the amine-based antioxidant represented by the above general formula (1) in the β-layer rubber composition is the amine-based antioxidant represented by the above general formula (1). When the content of the amine-based antioxidant is 0.1 parts by mass or more per 100 parts by mass of the rubber component, the ozone resistance of the rubber composition and the adhesion between the rubber and the metal reinforcing material can be sufficiently ensured, and the decrease in elongation at break (EB) and tensile strength (TB) of the aged rubber composition can also be sufficiently suppressed. On the other hand, when the content of the amine-based antioxidant is 11 parts by mass or less per 100 parts by mass of the rubber component, adverse effects on rubber properties such as heat generation can be more reliably suppressed, making it suitable for tire applications. Furthermore, from the viewpoint of the ozone resistance of the β-layer rubber composition and the adhesion between the rubber and the metal cord, the content of the amine-based antioxidant is more preferably 1 part by mass or more, even more preferably 1 part by mass or more, and particularly preferably 2 parts by mass or more, per 100 parts by mass of the rubber component. Moreover, from the viewpoint of suppressing adverse effects on other rubber properties, the content of the amine-based antioxidant is preferably 8 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component.

[0043] In the laminate of the present invention, the β layer of the rubber layer requires an amine-based antioxidant represented by the general formula (1) above, but it is preferable that the α layer also contains an amine-based antioxidant represented by the general formula (1) above. In this case, the elongation at break of the β layer after thermal degradation can be further increased. The composition of the amine-based antioxidant represented by the general formula (1) above is as described above. When the α layer contains an amine-based antioxidant represented by the general formula (1), the content of the amine-based antioxidant represented by the general formula (1) in the α layer rubber composition is preferably 0.1 to 11 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 2 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0044] The α layer and / or the β layer may contain antioxidants other than the amine-based antioxidant represented by the general formula (1) above (other antioxidants). Examples of such other antioxidants include quinoline-based antioxidants. These quinoline-based antioxidants are antioxidants having a quinoline portion or a derivative thereof (such as a dihydroquinoline portion). The quinoline-based antioxidant, when included in each rubber composition, improves ozone resistance and suppresses the decrease in the maintenance rate of elongation at break (EB) and tensile strength (TB) after aging.

[0045] The quinoline-based antioxidant preferably has a dihydroquinoline moiety, and more preferably has a 1,2-dihydroquinoline moiety. Examples of the aforementioned quinoline-based antioxidants include polymers of 2,2,4-trimethyl-1,2-dihydroquinoline (antioxidant TMDQ), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, and 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline. The quinoline-based antioxidant preferably contains a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (antioxidant TMDQ). A quinoline-based antioxidant containing a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline has a high effect in improving the ozone resistance of the rubber composition and also has the advantage of being less likely to cause discoloration of the rubber composition. Polymers of 2,2,4-trimethyl-1,2-dihydroquinoline include dimers, trimers, and tetramers of 2,2,4-trimethyl-1,2-dihydroquinoline.

[0046] Furthermore, the content of the quinoline-based antioxidant in the α-layer rubber composition and the β-layer rubber composition is preferably in the range of 0.27 to 0.7 in terms of the mass ratio of the content of the quinoline-based antioxidant to the content of the amine-based antioxidant. For example, from the viewpoint of ensuring sufficient ozone resistance while suppressing adverse effects on rubber properties, and sufficiently inhibiting the decline in adhesion after aging, as well as the elongation at break (EB) and tensile strength (TB) of the rubber composition, it is preferable that the content of the quinoline-based antioxidant is 0.1 to 5 parts by mass per 100 parts by mass of the rubber component. When the content of the quinoline-based antioxidant is 0.1 parts by mass or more per 100 parts by mass of the rubber component, sufficient ozone resistance of the rubber composition can be ensured, and the decline in adhesion after aging, as well as the decline in elongation at break (EB) and tensile strength (TB) of the rubber composition can be sufficiently inhibited. On the other hand, when the content of the quinoline-based antioxidant is 5 parts by mass or less per 100 parts by mass of the rubber component, adverse effects on rubber properties (such as heat generation) can be suppressed, making it suitable for tire applications. Furthermore, from the viewpoint of further improving ozone resistance and adhesion, the content of the quinoline-based antioxidant in the α-layer rubber composition and / or the β-layer rubber composition is more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of more reliably suppressing adverse effects on other rubber properties, it is more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of the rubber component.

[0047] Furthermore, the α layer and the β layer may also contain antioxidants other than the amine-based antioxidant and quinoline-based antioxidant represented by the general formula (1) above. However, from the viewpoint of reducing the burden on the environment, it is preferable that the antioxidant does not contain N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine.

[0048] ·silica The α layer and the β layer may also contain silica as needed. However, the α layer is preferably silica-free from the viewpoint of suppressing a decrease in performance as an adhesive layer with the metal reinforcing material. Furthermore, if the β layer contains silica, the silica content is preferably 1 to 20 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0049] Furthermore, there are no particular restrictions on the type of silica; examples include wet silica, colloidal silica, calcium silicate, and aluminum silicate. Among the above, the silica is preferably wet silica, and more preferably precipitated silica. These silicas have high dispersibility, improved low exothermic properties, and enhanced crack resistance. Precipitated silica is silica obtained by first reacting the reaction solution at a relatively high temperature and in a neutral to alkaline pH range to grow primary silica particles, and then controlling the pH to the acidic side to aggregate the primary particles. Furthermore, the silica can be a commercially available product; for example, it can be obtained as Rhodia's ZeosilPremium 200MP (product name). Furthermore, the silica may be of one type only, or two or more types may be used.

[0050] ·resin The α layer and the β layer may also contain resin as needed. The inclusion of resin in the α and β layers allows for the formation of a network between the carbon blacks via the resin, thereby improving crack propagation resistance. The resin is not particularly limited, but from the viewpoint of further improving the crack propagation resistance of vulcanized rubber, 10.3 (cal / cm) is preferred. 3 ) 1 / 2 Preferably, it should be 11.0 (cal / cm³). 3 ) 1 / 2 It is more preferable that the value be 12.0 (cal / cm³). 3 ) 1 / 2 It is even more preferable that the value be 12.5 (cal / cm³). 3 ) 1 / 2 It is even more preferable that the SP value is 16 (cal / cm³). 3 )1 / 2 It is difficult to obtain resins exceeding this level. The SP value of a resin can be calculated according to the Flory-Huggins formula.

[0051] Furthermore, examples of the types of resins include at least one resin selected from terpene resins, phenolic resins, coumarone-indene resins, xylene resins, rosin-based resins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins, and alicyclic hydrocarbon resins. Among the above, the resin is preferably a dicyclopentadiene resin (DCPD resin) or a phenol resin, with phenol resin being more preferred.

[0052] The aforementioned terpene resin is a resin whose main component is a terpene polymer or a modified thereof, and examples include the "YS Resin PX," "YS Resin PXN," "YS Resin TO," and "YS Resin TR" series manufactured by Yasuhara Chemical Co., Ltd., and the "PicoLite" series manufactured by Hercules Corporation.

[0053] The phenolic resin is preferably a novolac-type thermoplastic phenolic resin, such as the "Sumilite Resin PR" series manufactured by Sumitomo Bakelite Co., Ltd., or "Tamanol 501" manufactured by Arakawa Chemical Industries, Ltd.

[0054] The aforementioned coumarone-indene resin is produced by polymerizing coumarone, indene, styrene, etc., in coal tar, and examples include the coumarone resin series manufactured by Kobe Oil Chemical Industry Co., Ltd. Xylene resin is a resin or modified product thereof obtained by condensing xylene and formaldehyde, and examples include the "Lignol" series of products manufactured by Lignite Co., Ltd.

[0055] Examples of the aforementioned rosin-based resins include pentaerythritol ester of rosin, glycerol ester of rosin, polymerized rosin, and hydrogenated rosin.

[0056] The aforementioned aromatic hydrocarbon resin is a petroleum resin produced from the C9 fraction, and examples include the "Nisseki Neopolymer" series manufactured by JX Nippon Oil & Energy Corporation. Aliphatic hydrocarbon resins are petroleum resins manufactured from the C5 fraction, and examples include the "Escolettes" series from ExxonMobil and the "Quinton 100" series from Zeon Corporation.

[0057] Alicyclic hydrocarbon resins include, for example, petroleum resins manufactured primarily from high-purity cyclopentadiene extracted from the C5 fraction, but C5 resins have an SP value of 10 (cal / cm³). 3 ) 1 / 2 Many are less than 10 (cal / cm²). Therefore, the SP value of the resin is 10 (cal / cm²). 3 ) 1 / 2 To achieve the above, it is preferable to use a dicyclopentadiene-based resin (DCPD-based resin) manufactured using high-purity dicyclopentadiene, which is obtained by dimerizing cyclopentadiene, as the main raw material.

[0058] Suitable examples of the dicyclopentadiene resin include the Quinton 1000 series (Quinton 1105, Quinton 1325, Quinton 1340) manufactured by Nippon Zeon Corporation.

[0059] The content of the resin in the α-layer rubber composition and the β-layer rubber composition is preferably 2 to 10 parts by mass, and more preferably 3 to 7 parts by mass, per 100 parts by mass of the rubber component. By setting the resin content to 2 parts by mass or more per 100 parts by mass of the rubber component, crack propagation resistance can be further improved, and by setting it to 10 parts by mass or less, deterioration of low heat generation can be suppressed.

[0060] Furthermore, the α-layer rubber composition and / or the β-layer rubber composition may also contain a methylene donor as the resin component. The melamine donor functions as a curing agent for the phenolic resin, improving the tensile strength of the rubber, and also improving the reinforcing properties of the rubber composition while maintaining excellent low heat generation. Furthermore, from the viewpoint of further improving the low heat generation and crack propagation resistance of the α layer and the β layer, it is preferable that the resin component consists of a phenolic resin and a methylene donor.

[0061] The type of methylene donor is not particularly limited and can be appropriately selected according to the required performance. Examples include hexamethylenetetramine, hexamethoxymethylmelamine, pentamethoxymethylmelamine, hexamethoxymethylmelamine, pentamethoxymethylmelamine, hexaethoxymethylmelamine, hexakis-(methoxymethyl)melamine, N,N',N”-trimethyl-N,N',N”-trimethylmelamine, N,N',N”-trimethylmelamine, N-methylmelamine, N,N'-(methoxymethyl)melamine, N,N',N”-tributyl-N,N',N”-trimethylmelamine, paraformaldehyde, etc. Among these, it is preferable that the methylene donor be at least one selected from the group consisting of hexamethylenetetramine, hexamethoxymethylmelamine, hexamethoxymethylmelamine, and paraformaldehyde. These methylene donors may be used individually or in combination of two or more types.

[0062] Other ingredients In addition to the rubber components, carbon black, and antioxidants mentioned above, and optional components such as silica and resin, the α layer and β layer may appropriately contain additives commonly used in the rubber industry, such as vulcanization accelerators, bismaleimide compounds, softeners, stearic acid, zinc oxide, waxes, and oils, within limits that do not impair the purpose of the present invention.

[0063] The type of vulcanization accelerator is not particularly limited, and examples include guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, dithiocarbamate-based, and xantate-based vulcanization accelerators. One of these vulcanization accelerators may be used alone, or two or more may be used in combination. Furthermore, among the vulcanization accelerators mentioned above, it is preferable to use a sulfenamide-based vulcanization accelerator from the viewpoint of being able to further increase the strength of the rubber composition after vulcanization. Examples of the sulfenamide-based sulfurization accelerators include N-cyclohexyl-2-benzothiazolyl sulfenamide, N,N-dicyclohexyl-2-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolyl sulfenamide, N-oxydiethylene-2-benzothiazolyl sulfenamide, N-methyl-2-benzothiazolyl sulfenamide, N-ethyl-2-benzothiazolyl sulfenamide, N-propyl-2-benzothiazolyl sulfenamide, N-butyl-2-benzothiazolyl sulfenamide, N-pentyl-2-benzothiazolyl sulfenamide, N-hexyl-2-benzothiazolyl sulfenamide, N-heptyl-2-benzothiazolyl sulfenamide, N-octyl-2-benzothiazolyl sulfenamide, N-2-ethylhexyl-2-benzothiazolyl sulfenamide, N-decyl-2-benzothiazolyl sulfenamide, N-dodecyl-2-benzothiazolyl sulfenamide, N-stearyl-2-benzothiazolyl sulfenamide, N,N-dimethyl-2-benzothiazolyl sulfenamide, N,N-diethyl-2-benzothiazolyl sulfenamide, N,N-dipropyl-2-benzothiazolyl sulfenamide, N,N-dibutyl-2-benzothiazolyl sulfenamide, N,N-dipentyl-2-benzothiazolyl sulfenamide, N,N-dihexyl Examples include N,N-2-benzothiazolyl sulfenamide, N,N-diheptyl-2-benzothiazolyl sulfenamide, N,N-dioctyl-2-benzothiazolyl sulfenamide, N,N-di-2-ethylhexylbenzothiazolyl sulfenamide, N,N-didecyl-2-benzothiazolyl sulfenamide, N,N-didodecyl-2-benzothiazolyl sulfenamide, and N,N-distearyl-2-benzothiazolyl sulfenamide. Among these, the vulcanization accelerator is more preferably composed of at least N-cyclohexyl-2-benzothiazolyl sulfenamide.

[0064] Furthermore, from the viewpoint of further improving the low heat generation and crack resistance of the rubber layer, the content of the vulcanization accelerator in the α-layer rubber composition and the β-layer rubber composition is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, preferably 2.0 parts by mass or less, more preferably 1.8 parts by mass or less, and even more preferably 1.6 parts by mass or less, per 100 parts by mass of the rubber component.

[0065] Furthermore, among the other components mentioned above, zinc oxide (ZnO) is used as a vulcanization accelerator. By further including the zinc oxide, vulcanization can be promoted, and the strength of the rubber layer can be further increased. Here, the zinc oxide content in the α-layer rubber composition and the β-layer rubber composition is not particularly limited, but from the viewpoint of further improving the low heat generation and crack resistance of the rubber layer, it is preferably 5 to 13 parts by mass, and more preferably 7 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0066] Furthermore, the α layer and the β layer may contain a cobalt compound to enhance the adhesion between the rubber layer and the metal reinforcing material. The type of cobalt compound is not particularly limited and can be appropriately selected according to the required performance. However, from the viewpoint of reducing the burden on the environment, the α layer and the β layer may be made without cobalt (cobalt-free). Note that "cobalt-free" in the α layer and the β layer means that cobalt is not actively incorporated into the α layer rubber composition and the β layer rubber composition, and excludes cases where cobalt is inevitably included or cobalt that has migrated from the metal reinforcing material to the rubber layer.

[0067] The method for producing the α-layer rubber composition and the β-layer rubber composition is not particularly limited. For example, it can be manufactured by combining the above-mentioned components and mixing them using a mixing machine such as a Banbury mixer, roll mixer, or internal mixer. Furthermore, the mixing of the components of the α-layer rubber composition and the β-layer rubber composition may be carried out in a single step, or it may be carried out in two or more steps.

[0068] The applications of the laminate of the present invention are not particularly limited. For example, it can be used as a reinforcing material in rubber articles that require particularly high strength, such as various automobile tires, conveyor belts, hoses, and rubber tracks. In particular, it can be suitably used as a reinforcing member for belts, carcass plies, wire chafers, etc., in various types of radial tires for automobiles.

[0069] (Belt coated rubber) Among the above-mentioned applications, the laminate of the present invention is preferably used as a tire belt. In this case, the α layer of the rubber layer can be used as the coating rubber layer of the belt. This allows the effect of improving the elongation at break after thermal degradation to be more pronounced while maintaining the initial adhesion of the laminate of the present invention.

[0070] Furthermore, when the laminate of the present invention is used as a tire belt, it is preferable that the carbon black content in the β layer of the rubber layer is less than 50 parts by mass per 100 parts by mass of the rubber component. This is because it ensures excellent elongation at break after thermal degradation of the metal reinforcing material and the rubber layer, while also maintaining good physical properties such as low heat generation.

[0071] Furthermore, when the laminate of the present invention is used as a tire belt, it is preferable that the β layer of the rubber layer does not contain cobalt. This is because it reduces the environmental burden, and even without cobalt in the β layer, the adhesion to the metal reinforcing material can be maintained.

[0072] (Ply-coated rubber) Among the above-mentioned applications, the laminate of the present invention is preferably used as a tire carcass ply. In this case, the α layer of the rubber layer can be used as the coating rubber layer of the ply. This allows the effect of improving the elongation at break after thermal degradation to be more pronounced while maintaining the initial adhesion of the laminate of the present invention.

[0073] Furthermore, when the laminate of the present invention is used as a carcass ply for a tire, it is preferable that the β layer of the rubber layer does not contain silica. This is because the required performance can be ensured even without silica in the β layer.

[0074] <Tires> The tire of the present invention is characterized by using the laminated material of the present invention as described above. By using the laminate of the present invention in the components that make up the tire, a component with excellent adhesion between the rubber layer and the metal reinforcing material can be obtained, and consequently, the durability of the tire can also be improved.

[0075] Furthermore, the tire of the present invention is preferably a pneumatic tire, and as the gas to be filled into the pneumatic tire, in addition to ordinary air or air with adjusted oxygen partial pressure, an inert gas such as nitrogen, argon, or helium can be used. The method for manufacturing the tire of the present invention is not particularly limited and can be manufactured using conventional methods. Generally, a rubber composition containing various components is processed into each component at an unvulcanized stage, and then bonded and molded on a tire molding machine using conventional methods to form a green tire. This green tire is then heated and pressurized in a vulcanizing machine to produce a tire. For example, the rubber composition of the present invention can be kneaded, and the resulting rubber composition can be used to rubberize metal cords to create an unvulcanized belt, an unvulcanized carcass, and other unvulcanized components, which are then laminated together to produce a tire by vulcanizing the unvulcanized laminate. [Examples]

[0076] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the examples described below.

[0077] <Examples 1-4, Comparative Examples 1-4> The α-layer rubber composition and β-layer rubber composition constituting the metal cord coating rubber layer are prepared according to the component compositions shown in Table 1. <Comparative Example 5 and Example 5> (Preparation of rubber composition) Rubber compositions were manufactured according to the formulations shown in Table 2. The α-layer rubber composition and β-layer rubber composition constituting the metal cord coating rubber layer were prepared. Subsequently, the steel cord, as described later, was coated with a rubber composition and evaluated.

[0078] The steel cords used in each example and comparative example were prepared as follows. In Examples 1-3 and Comparative Examples 1-3, a 1.7 mm diameter steel wire was repeatedly plated with 63.0% by mass of copper and 37.0% by mass of zinc, in that order. After that, a thermal diffusion treatment was performed at 550°C for 5 seconds to obtain the desired binary plating, and then the wire was drawn to obtain a steel wire with an average plating thickness of 0.25 μm and a diameter of 0.30 mm. Using each of the obtained steel wires, a 1 × 3 × 0.30 (mm) twisted steel cord was fabricated. In Examples 4-5 and Comparative Examples 4-5, 1.7 mm diameter steel wires were repeatedly plated with 63.0% copper by mass and 37.0% zinc by mass, in that order. After that, a thermal diffusion treatment was performed at 550°C for 5 seconds to obtain the desired binary plating, followed by wire drawing to obtain steel wires with an average plating thickness of 0.22 μm and diameters of 0.24 mm, 0.225 mm, and 0.15 mm. Using each of the obtained steel wires, a twisted steel cord with a 3×0.24 / 9×0.225+0.15 (mm) structure was fabricated.

[0079] <Rating> The metal cord-rubber laminates of each sample were evaluated under the following conditions. The evaluation results are shown in Table 2.

[0080] (1)Initial adhesion Twenty-five of the aforementioned steel cords were arranged parallel to each other in a 5cm width, and these steel cords were covered from above and below with an α-layer rubber composition. The α-layer rubber composition covering the cords was then attached to a 3mm thick β-layer rubber composition and vulcanized at 145°C for 40 minutes to bond the rubber composition and the steel cords. In this way, a steel cord-rubber composite was obtained in which steel cords were embedded in a 1mm thick rubber sheet. In accordance with ASTM D 2229, steel cords were extracted from each sample immediately after vulcanization, and the rubber coating percentage attached to the steel cords was determined visually on a scale of 0-100% to serve as an indicator of initial adhesion. The obtained coating percentages are shown in Table 2. A higher coating percentage indicates better initial adhesion.

[0081] (2) Retention rate of elongation at break (EB) after thermal degradation A rubber composition was vulcanized to prepare vulcanized rubber test specimens. Tensile tests were performed on the specimens immediately after preparation in accordance with JIS K 6251, and the initial elongation at break (EB) was measured. Next, vulcanized rubber test pieces were left at 100°C for 24 hours to allow thermal degradation to occur. After thermal degradation, tensile tests were performed on the test pieces in accordance with JIS K 6251, and the elongation at break (EB) after thermal degradation was measured. The retention rate of the elongation at break (EB) after thermal degradation was calculated from the initial elongation at break (EB) and the elongation at break (EB) after thermal degradation, according to the following formula. Retention rate of elongation at break (EB) after thermal degradation = Elongation at break after thermal degradation (EB) / Initial elongation at break (EB) × 100 (%) Furthermore, the retention rate of elongation at break (EB) after thermal degradation in Comparative Example 5 was set to 100, and expressed as an index. A larger index value indicates a higher retention rate of elongation at break (EB) after thermal degradation, and thus higher thermal degradation resistance (durability after thermal degradation).

[0082] [Table 1]

[0083] [Table 2]

[0084] *1 Natural rubber, RSS#3 *2 Natural rubber, TSR#20 *3 HAF grade carbon black, manufactured by Asahi Carbon Co., Ltd. "Asahi #70L" (Nitrogen adsorption specific surface area: 81 m2 / g, Iodine adsorption amount: 85 mg / g, N2SA / IA: 0.95 m 2 / mg) *4 Carbon black, CABOT "VALCAN 7H" (Nitrogen adsorption specific surface area: 117 m² / g, Iodine adsorption capacity: 120 mg / g, N2SA / IA: 0.975 m²) 2 / mg) *5 "NipSeal AQ" manufactured by Tosoh Silica Co., Ltd. *6 "Stearic Acid 50S" manufactured by Shin Nippon Rika Co., Ltd. *7 "Nonflex RD" manufactured by Seiko Chemical Co., Ltd. *8 Seiko Chemical Co., Ltd.'s "Nonflex RD-S" *9 N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocrac 6C" *10 N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine *11 2,2'-Methylenebis(4-methyl-6-tert-butylphenol), manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocrac NS-6" *12 A complex salt in which some of the organic acids in an organic acid cobalt salt are replaced with boric acid, OMG's "Manobond C" *13 Cobalt versatate, manufactured by DIC Corporation *14 Alkylphenol formaldehyde resin, SUMITOMO BAKELITE EUROPE, "DUREZ 19900" *15 Quinton 1105 manufactured by Nippon Zeon Co., Ltd. *16 Sulfenamide-based vulcanization accelerator, N-tert-butyl-2-benzothiazolyl sulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar NS-P" *17 Sulfenamide-based vulcanization accelerator, N-cyclohexyl-2-benzothiazolyl sulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar CZ-G" *18 "HK200-5" manufactured by Hosoi Chemical Industry Co., Ltd. *19 Powdered sulfur manufactured by Tsurumi Chemical Industries, Ltd.

[0085] The results in Table 1 show that the example samples exhibit superior performance in terms of elongation at break after thermal degradation, while maintaining initial adhesion, compared to the samples of each comparative example. [Industrial applicability]

[0086] According to the present invention, it is possible to provide a laminate that maintains initial adhesion between the metal reinforcement and the rubber layer while exhibiting excellent elongation at the time of cutting after thermal degradation. Furthermore, according to the present invention, it is possible to provide a tire with excellent durability using a lightweight laminate.

Claims

1. A laminate comprising a metal reinforcing material and two or more rubber layers, the rubber layer has at least an α layer in contact with the metal reinforcing material and a β layer in contact with the α layer, The α layer and the β layer are both a rubber component containing 60 to 100% by mass of an isoprene skeleton rubber; Nitrogen adsorption specific surface area (N ２ SA)m ２ / g and the ratio of iodine adsorption (IA) mg / g (N ２ SA / IA) is 1.2m ２ and carbon black having a molecular weight of 1000 mg or less; The β layer may further comprise a compound represented by the following general formula (1): 【Chemistry 1】 [In the formula, R １ and R ２ and each independently represent a monovalent saturated hydrocarbon group] in an amount of 0.1 to 11 parts by mass per 100 parts by mass of the rubber component.

2. The laminate according to claim 1, wherein the α layer further contains an amine-based antioxidant represented by the general formula (1) in an amount of 0.1 to 11 parts by mass per 100 parts by mass of the rubber component.

3. R in the general formula (1) １ and R ２ and each independently represent a linear or cyclic monovalent saturated hydrocarbon group having 1 to 20 carbon atoms.

4. The laminate according to claim 1 or 2, wherein the α layer does not contain silica.

5. 3. The laminate according to claim 1, wherein the β layer does not contain N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine as an antioxidant.

6. 3. The laminate according to claim 1, wherein the α layer does not contain N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine as an antioxidant.

7. 3. The laminate according to claim 1, wherein the α layer constitutes a coating rubber layer of the belt.

8. The laminate according to claim 6, wherein the content of the carbon black in the β layer is less than 50 parts by mass with respect to 100 parts by mass of the rubber component.

9. The laminate of claim 6 , wherein the beta layer is cobalt-free.

10. 3. The laminate according to claim 1, wherein the α layer constitutes a coating rubber layer of the ply.

11. The laminate of claim 10, wherein the beta layer is silica-free.

12. A tire comprising the laminate according to claim 1 or 2.

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