JP6957963B2 - Adhesion condition determination method and pneumatic tire manufacturing method - Google Patents

Description

The present invention method for determining the adhesion state relates及Beauty pneumatic tire manufacturing method.

Pneumatic tires generally use a reinforcing member comprising a steel cord and a coated rubber covering the steel cord. The surface of the steel cord used for the reinforcing member is, for example, brass-plated in order to improve the adhesiveness with the coated rubber, and by vulcanization, the copper contained in the brass plating becomes sulfur in the coated rubber. Combined with, the coated rubber is glued to the steel cord.

If the adhesion between the steel cord and the coated rubber is not good, the adhesion may be broken while the vehicle is running, the steel cord may peel off from the coated rubber, and the tire may burst. Therefore, in order to improve the durability of the tire, it is important to maintain a good adhesive state between the steel cord and the coated rubber.
Conventionally, it has been known to add an organic cobalt salt to a rubber composition to be a coated rubber or to include cobalt in brass plating in order to promote the formation of a bond between copper and sulfur. For example, in Patent Document 1, by drawing a steel filament on which a plating layer containing copper, zinc and cobalt is formed under predetermined conditions, the surface of the plating has a composition suitable for adhesion to rubber, and as a result, , It is stated that the adhesiveness between rubber and steel cord can be improved.

Japanese Unexamined Patent Publication No. 2016-78482

By the way, in the produced tire, the adhesive state between the steel cord and the coated rubber may be evaluated. At the time of evaluation, if it is known in what state the steel cord and the coated rubber are in a good adhesive state, it is considered that the adhesive state can be easily evaluated. However, the state of adhesion between the steel cord and the coated rubber changes depending on the vulcanization conditions and the degree of deterioration of the rubber during use, so what is the state of the steel cord and the coated rubber when the state of adhesion is good? Is not easy to identify.

An object of the present invention is to provide a method for determining an adhesive state, which can easily evaluate the quality of the adhesive state between a metal material and a rubber material. Another object of the present invention is to provide a metal-rubber composite, a pneumatic tire, and a method for manufacturing a pneumatic tire, which can suppress deterioration of the adhesive state between the metal material and the rubber material.

One aspect of the present invention is a method for determining an adhesive state between a metal material and a rubber material covering the metal material.
The metal material has a plating layer containing brass or zinc as a main component on the surface layer.
It exists in the rubber material on the inner surface of the rubber material exposed in a region near the interface located along the interface at a distance from the interface with the metal material, and on the surface of the metal material, respectively. Measure the amount of cobalt and
When the amount of cobalt on the surface of the metal material is larger than the amount of cobalt on the inner surface of the rubber material, it is determined that the adhesion between the metal material and the rubber material is good.

Another aspect of the present invention is a metal-rubber complex.
A metal material having a plating layer containing brass or zinc as the main component on the surface layer,
A metal-rubber complex comprising a rubber material covering the metal material.
Of the metal material and the rubber material, at least the metal material contains cobalt.
With respect to the amount of cobalt on the inner surface of the rubber material exposed in the rubber material in a region near the interface located along the interface at intervals from the interface with the metal material, the surface of the metal material It is characterized by a large amount of cobalt.

The rubber material is obtained by vulcanizing a rubber composition coated with the metal material.
The rubber composition preferably contains 30 to 80 parts by mass of carbon black and 3 to 10 parts by mass of sulfur with respect to 100 parts by mass of diene-based rubber.

The ratio of the amount of cobalt on the surface of the metal material to the amount of cobalt on the inner surface of the rubber material is preferably 150% or more.

Another aspect of the present invention is a pneumatic tire provided with the metal-rubber complex as a reinforcing member for reinforcing the tire structure.
The reinforcing member has a plurality of aligned cords as the metal material of the metal-rubber composite, and has a coated rubber in contact with the surface of the cords as the rubber material of the metal-rubber composite. , Characterized by.

Another aspect of the present invention is a method for manufacturing a pneumatic tire.
A raw tire is produced which is a sheet-like member having a plurality of aligned cords made of a metal material and a rubber composition covering the cords, and which includes the sheet-like member wound in the circumferential direction. Steps and
The step of vulcanizing the raw tire is provided.
The cord has a plating layer containing brass or zinc as a main component on the surface layer.
In the vulcanized raw tire, the amount of cobalt contained in the cord is more than 0 atomic% and 10 atomic% or less, and the amount of cobalt contained in the coated rubber obtained by vulcanizing the rubber composition is 0 to 1 mass. % And
It exists in the coated rubber on the inner surface of the coated rubber exposed in a region near the interface located along the interface at intervals from the interface of the coated rubber with the cord, and on the surface of the cord. when measured cobalt amount, so that the cobalt content of the surface of the cord is 150% to 400% of the cobalt content of the interior surface of the coating rubber, vulcanizing step, and, the raw tire to produce the raw tire It is characterized by performing steps.

According to the present invention, it is possible to easily evaluate the quality of the adhesive state between the metal material and the rubber material. Further, according to the present invention, a metal-rubber composite and a pneumatic tire capable of suppressing deterioration of the adhesive state between the metal material and the rubber material can be obtained.

It is a figure which shows the cut surface of a brass plating cord and a coated rubber. It is a graph which shows the result of XAS measurement of the surface of a brass plate after an adhesive treatment. It is a figure which shows the cut surface of a belt member. It is a figure which shows the radial cross section of a pneumatic tire.

Hereinafter, a method for determining the adhesive state, a metal-rubber composite, a pneumatic tire, and a method for manufacturing the pneumatic tire will be described.

(Method of determining the adhesive state)
The method for determining the adhesive state of the present embodiment is a method for determining the adhesive state between the metal material and the rubber material covering the metal material.

The metal material has a plating layer containing brass or zinc as a main component on the surface layer. The plating layer may be located at a position including the surface of the metal material as long as it is contained in the surface layer of the metal material (for example, a layer from the surface of the metal material to a depth of 0.01 to 1 μm), and the surface of the metal material. It may be located at a distance from. An example of the case where the plating layer is located at a position spaced from the surface of the metal material includes a film containing a metal element formed so as to cover the surface of the plating layer, which will be described later.
The plating (hereinafter, also referred to as brass plating) layer containing brass as a main component is a layer containing copper (Cu) as a main component (containing 50 atomic% or more) and zinc (Zn) in an amount of 20 atomic% or more. The brass plating layer may be composed of copper and zinc, and may contain one or more metal elements other than copper and zinc. The plating layer containing zinc as a main component (hereinafter, also referred to as zinc plating) is a layer containing at least 50 atomic% or more of zinc, and may contain one or more metal elements other than zinc. Examples of the metal element contained in the brass plating layer and the zinc plating layer include cobalt (Co) and nickel (Ni). Cobalt functions as a catalyst that promotes the reaction between a metal element such as copper contained in the plating layer and sulfur in a rubber composition described later. The plating layer can be formed on the surface of the main body of the metal material located inside the plating layer by, for example, an electroplating treatment, a hot-dip plating treatment, or a heat treatment performed in combination with these treatments. The thickness of the plating layer is, for example, 0.05 to 0.5 μm.

Examples of the main body of the metal material include, but are not limited to, steel cords, which may be materials other than steel, and may be in a form other than the cords such as plate-shaped, granular, and lump-shaped. May be good.

The rubber material is a material obtained by vulcanizing a rubber composition coated with a metal material. The rubber composition will be described in detail later.

In the determination method of the present embodiment, the inner surface of the rubber material exposed in the rubber material in the region near the interface located along the interface at a distance from the interface with the metal material, and the surface of the metal material. Measure the amount of cobalt present in each. Then, when the amount of cobalt on the surface of the metal material is larger than the amount of cobalt on the inner surface, it is determined that the adhesion between the metal material and the rubber material is good.

Here, with reference to FIG. 1, the surface of the metal material, the region near the interface of the rubber material, and the inner surface will be described. FIG. 1 shows a cut surface of a steel cord with a brass plating layer (hereinafter referred to as a brass plating cord) 11 which is an example of a metal material, and a coated rubber 15 which coats a brass plating cord 11 which is an example of a rubber material. It is a figure.
The brass plating of the brass plating cord 11 is located at a position forming the outermost layer of the brass plating cord 11, and forms the surface 11a of the brass plating cord 11. For the surface 11a to be measured for the amount of cobalt, for example, the coated rubber 15 adhered to the brass plating cord 11 is scraped off or peeled off, and the coated rubber 15 remaining on the surface 11a is subjected to a solvent such as toluene. It can be obtained by swelling with and removing.
The inner surface of the coated rubber 15 is a surface exposed at an arbitrary position in the interface vicinity region 15b of the coated rubber 15. The interface vicinity region 15b is a region located in the coated rubber 15 in an annular shape along the interface 15a at a distance from the interface 15a of the coated rubber 15 with the brass plating cord 11, and is sandwiched between two alternate long and short dash lines in FIG. Area. Specifically, the interface vicinity region 15b is a region having a length of 0.1% away from the interface 15a and a length of 0.1% of the thickness of the coated rubber 15 and a length of 0.1 to 20% in the direction away from the interface 15a, preferably. A region having a length of 0.5% to 10% in the direction away from the interface 15a, which is 0.5% of the thickness of the coated rubber 15 from the interface 15a. The thickness of the coated rubber 15 is the length of the coated rubber 15 in the vertical direction in FIG. Alternatively, the interface vicinity region 15b may be a region having a length of 1 μm away from the interface 15a in the direction away from the interface 15a and a length region of 1 to 1000 μm in the direction away from the interface 15a. The inner surface of the coated rubber 15 to be measured for the amount of cobalt is exposed by scraping or slicing the coated rubber 15 at an arbitrary position in the interface vicinity region 15b, for example, using an instrument such as a cutter or a knife. Can be obtained.

As described above, the adhesive state between the metal material and the rubber material changes depending on the vulcanization conditions and the degree of deterioration of the rubber material. Therefore, the ideal state of the metal material and the rubber material having a good adhesive state is specified. It's not easy to do. According to the study of the present inventor, it has been clarified that the adhesive state between the metal material and the rubber material is good when the amount of cobalt on the surface of the metal material is larger than the amount of cobalt on the inner surface. The good adhesive state between the metal material and the rubber material specifically means that the deterioration of the adhesive state between the metal material and the rubber material with time is suppressed or suppressed. According to the determination method of the present embodiment, the amount of cobalt on the surface and the inner surface of the metal material can be measured, and the quality of the adhesive state between the metal material and the rubber material can be easily evaluated based on the amount of cobalt in both. can. For example, the method of determining the present embodiment can be used to determine the state of adhesion between the metal material (cord) and the rubber material (coated rubber) that make up the belt member of a pneumatic tire, when the tire is new, in use, or after it has been used. Can go and evaluate.

The amount of cobalt can be measured, for example, by using X-ray absorption spectroscopy (XAS). In the measurement by the XAS method, the amount of cobalt existing on the surface of the measurement target (the depth region of about several nm forming the surface) is measured by using X-rays (soft X-rays) having an energy amount of 0.1 to 2 keV. can do. Specifically, the surface of the metal material and the inner surface of the rubber material are each irradiated with X-ray irradiation energy while changing in the range of 750 to 830 eV including the energy region corresponding to cobalt, and the measurement target. An absorption spectrum can be obtained by detecting the amount of photoelectrons emitted from and the amount of current corresponding to the amount of photoelectrons emitted from. The intensity I ₁ of the absorption spectrum, as measured samples of gold (Au), by dividing the intensity I ₀ of the absorption spectrum obtained by irradiating X-rays under the same conditions, the normalized intensity of the cobalt, i.e. strength A ratio of I ₁ / I ₀ is obtained. FIG. 2 shows an example of the measurement result of the surface of the brass plate after the bonding treatment (after vulcanization). In FIG. 2, the vertical axis represents I ₁ / I ₀ , and the horizontal axis represents the X-ray irradiation energy. In the absorption spectrum shown in FIG. 2, a peak indicating cobalt appears in the vicinity of 778 eV.
Further, measurements were made while changing the X-ray irradiation energy in the range of 260 to 310 eV including the energy region corresponding to carbon (C), which is the main component of the rubber material, and the σ bond peak of carbon of 293 eV was measured in the above I ₁ / a I ₀ in the same way that was determined to obtain the intensity I ₁ / I ₀ which is standardized carbon, a value obtained by dividing the I ₁ / I ₀ of cobalt I ₁ / I ₀ of carbon and the amount of cobalt , Compare the amount of carbon dioxide on the surface of the metal material with the amount of carbon dioxide on the inner surface of the rubber material. Specifically, the ratio of the amount of cobalt on the surface of the metal material to the amount of cobalt on the inner surface of the rubber material (hereinafter, also referred to as the cobalt amount ratio) is calculated and evaluated. As a result, if the cobalt amount ratio exceeds 100%, it is determined that the adhesive state between the metal material and the rubber material is good. On the other hand, when the cobalt amount ratio is 100% or less, it is determined that the adhesive state between the metal material and the rubber material is not good.
By performing XAS measurement using soft X-rays in this way, surface observation focusing on a specific element (cobalt) can be performed, and the quality of the adhesive state between the metal material and the rubber material can be easily evaluated. Can be done. Further, when performing XAS measurement using soft X-rays, it is possible to easily prepare a sample to be measured and perform the measurement itself.

In the determination method of the present embodiment, at least one of the metal material and the rubber material whose cobalt amount is to be measured may contain cobalt, and none of them may contain cobalt. good. According to the determination method of the present embodiment, in any case, it is possible to determine whether or not the adhesive state of the metal material and the rubber material is good or bad.

(Metal-rubber complex)
Next, the metal-rubber composite of the present embodiment will be described.
The metal-rubber complex comprises the metal and rubber materials described above.

The rubber material is obtained by vulcanizing a rubber composition coated with a metal material, and the rubber composition contains a diene-based rubber and sulfur.

Examples of the diene rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and the like, or among these rubbers. A blend of two or more types can be mentioned.

Sulfur is preferably contained in an amount of 3 to 10 parts by mass with respect to 100 parts by mass of the diene rubber. If the sulfur content is less than 3 parts by mass, the reaction with the metal element on the surface of the metal material may not be sufficiently performed, and it may be difficult to improve the adhesive state. Further, if the sulfur content exceeds 10 parts by mass, the hardness of the rubber material becomes too high, which may make it unsuitable for use in pneumatic tires and the like.

The rubber composition further preferably contains carbon black. Carbon black is preferably contained in an amount of 30 to 80 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of carbon black is less than 30 parts by mass, the hardness of the rubber material decreases, and the hardness may be insufficient for use in pneumatic tires and the like unless a filler such as silica is used in combination. If the content of carbon black exceeds 80 parts by mass, the hardness of the rubber material becomes too high, which may make it unsuitable for use in pneumatic tires and the like.

The rubber composition may further contain an organic cobalt salt. The cobalt in the organic cobalt salt is diffused into the rubber material or the metal material during vulcanization and becomes a cobalt source in the rubber material and the metal material. Acids that make up the organic cobalt salt include versatic acid, naphthenic acid, stearic acid, oleic acid, ricinolic acid, linoleic acid, linoleic acid, dehydrated castor oil, resin acid, neodecanoic acid, naphthenic acid, hydroxystearic acid, and avietic acid. , Cabric acid, 2-ethylhexanoic acid, octyl acid, benzoic acid, bivariic acid, n-heptanoic acid, 2,2-dimethylpentanoic acid, 2-ethylpentanoic acid, 4,4-dimethylpentanoic acid, n-octanoic acid , 2,2-dimethylhexanoic acid, 2-ethylhexanoic acid, 4,4-dimethylhexanoic acid, 2,4,4-trimethylpentanoic acid, n-nonanoic acid, 2,2-dimethylheptanic acid, 6,6- Dimethylpeptanoic acid, 3,5,5-trimethylhexanoic acid, n-decanoic acid, 2,2-dimethyloctanoic acid, 7,7-dimethyloctanoic acid, n-undecanoic acid, "Versatic" 10® And so on. The organic cobalt salt contains at least one of these acids, and may contain other acids in addition to the above acids. For example, a complex salt in which a part of the above acid is replaced with boric acid may be used as the organic cobalt salt. As the organic cobalt salt, cobalt stearate, cobalt neodecanoate, and cobalt naphthenate are preferable because they have good dispersibility in the rubber composition.

The rubber composition may also contain additives such as zinc oxide, an antioxidant, a vulcanization accelerator, a processing aid, a plasticizer, and a vulcanizing agent. These additives can be included in general blending amounts.

The rubber composition is produced by mixing each of the above components using a general kneader such as a Banbury mixer, a kneader, or a roll.

The metal material preferably contains cobalt in the surface layer before vulcanization. When cobalt is contained in the surface layer of the metal material, it becomes easy to increase the cobalt amount ratio to a size exceeding 100%. Cobalt may be contained in the plating layer, or may be contained in the film formed on the surface of the plating layer.
The cobalt-containing film is, for example, a film obtained by applying a solution containing a cobalt salt to the surface of the plating layer and drying it. The solution containing the cobalt salt contains an organic solvent and a cobalt salt. As the organic solvent, for example, gasoline, ether, toluene, xylene, acetone and the like are used. As the cobalt salt, those having the above-listed acids as constituent acids can be used as the cobalt salt contained in the rubber composition. The solution containing the cobalt salt may further contain a diene-based rubber. As the diene-based rubber, the same type as the diene-based rubber in the rubber composition is preferably used in terms of improving the affinity with the diene-based rubber contained in the rubber composition, for example, natural rubber (NR). ), Polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR) and the like are preferably used. The solution containing the cobalt salt is adhered to the surface of the plating layer by continuously immersing the metal material, or continuously spraying or applying it to the metal material, and the solution is dried to dry the organic solvent. By removing the above, a film containing a cobalt salt is formed.

The metal-rubber complex is produced by coating a metal material with a rubber composition and vulcanizing it. For example, when the metal-rubber composite is a belt member of a pneumatic tire, a rubber composition is supplied from both sides sandwiching a plurality of aligned cords to cover the cords, and for each raw tire provided with this coating. It is produced by vulcanization. When the form of the metal material is plate-shaped, the metal-rubber composite has a rubber composition placed on one surface of the plate-shaped metal material, or both surfaces of the plate-shaped metal material. It is produced by sandwiching it with a rubber composition and vulcanizing it. When the form of the metal material is granular, the metal-rubber composite is produced by mixing the granular metal material in the rubber composition and vulcanizing it.

In the metal-rubber composite, the amount of cobalt is, for example, more than 0 atomic% and 10 atomic% or less in the metal material, and 0 to 1% by mass in terms of cobalt in the rubber material.

FIG. 3 shows the cut surfaces of the belt members 7 and 8 of the pneumatic tire as an example of the metal-rubber composite. The belt members 7 and 8 include a plurality of brass-plated cords 11 which are aligned as a metal material, and a coated rubber 15 which covers these cords as a rubber material.
The cord 11 includes at least one wire. In FIG. 3, the cord 11 is composed of one wire, but according to one embodiment, the cord 11 may be composed of a plurality of wires.
The diameter of the cord 11 is, for example, 0.1 to 3 mm.
The thickness of the coated rubber 15 is, for example, 0.5 to 3 mm when it is a belt member of a pneumatic tire.

In the metal-rubber composite of the present embodiment, the amount of cobalt on the surface of the metal material is larger than the amount of cobalt on the inner surface of the rubber material, so that the adhesive state between the metal material and the rubber material is good. Therefore, when the metal-rubber composite is used as the belt members 7 and 8 of the pneumatic tire, it is possible to prevent the tire from bursting due to peeling between the cord 11 and the coated rubber 15 while the vehicle is running. It can improve the durability of pneumatic tires.

The ratio of the amount of cobalt on the surface of the metal material to the amount of cobalt on the inner surface of the rubber material is preferably 150% or more. It was found that when the above ratio is 150% or more, it is possible to suppress the state of adhesion between the metal material and the rubber material from deteriorating with time with use. The upper limit of the above ratio is not particularly limited, but is, for example, 400%.

The metal-rubber composite of the present embodiment is used not only for belt members of pneumatic tires, but also for reinforcing members of pneumatic tires other than belt members, or for industrial rubber products such as transport belts and hoses. Can be done.

(Pneumatic tire)
Next, the pneumatic tire of the present embodiment will be described with reference to FIG.
FIG. 4 is a diagram showing a radial cross section of the pneumatic tire (hereinafter, also referred to as a tire) 10 of the present embodiment.

The tire 10 is composed of a tread portion 1, a sidewall portion 2, and a bead portion 3. The tread portion 1 is provided with a tread pattern on its surface. A carcass layer 4 is mounted between the pair of left and right bead portions 3. The carcass layer 4 contains a plurality of organic fiber cords extending in the tire radial direction, and is folded back from the inside to the outside of the tire around the bead core 5 arranged in each bead portion 3. Further, a bead filler 6 is arranged on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by a main body portion and a folded portion of the carcass layer 4. On the other hand, a plurality of layers (two layers in FIG. 4) of belt members 7 and 8 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1.
Each of the belt members 7 and 8 includes a plurality of aligned cords that are inclined with respect to the tire circumferential direction, and the cords are arranged so as to intersect each other between the belt members 7 and 8. The belt members 7 and 8 are one form of the metal-rubber composite described above, and in these belt members 7 and 8, the inclination angle of the cord with respect to the tire circumferential direction is set in the range of, for example, 10 ° to 40 °. There is.
Further, a belt reinforcing member 9 is provided on the outer peripheral side of the belt members 7 and 8. The belt reinforcing member 9 includes an organic fiber cord oriented in the tire circumferential direction. In the belt reinforcing member 9, the angle of the organic fiber cord with respect to the tire circumferential direction is set to, for example, 0 ° to 5 °.

The tire 10 of the present embodiment includes the metal-rubber composite as the belt members 7 and 8, and the amount of cobalt on the surface of the cord is larger than the amount of cobalt on the inner surface of the coated rubber. Therefore, the cord and the coated rubber are adhered to each other. The condition is good. Therefore, it is possible to prevent the tire 10 from bursting due to peeling between the cord 11 and the coated rubber 15 while the vehicle is running, and the durability of the tire 10 is improved. In general, with pneumatic tires, the cord is placed in an environment where the surface is easily oxidized by the heat generated inside the tire when the vehicle is running, the moisture contained in the rubber, or the moisture that has entered the tire due to scratches on the surface. Being exposed. When the surface of the cord is oxidized, the bond between the metal such as Cu-S and sulfur decreases, and the adhesive state deteriorates with time with use. However, in the tire 10 of the present embodiment, since the amount of cobalt on the surface of the cord is larger than the amount of cobalt on the inner surface of the coated rubber, deterioration of the adhesive state between the metal material and the rubber material over time is suppressed.

(Manufacturing method of pneumatic tires)
Next, a method for manufacturing the pneumatic tire of the present embodiment will be described.
The method for manufacturing a pneumatic tire of the present embodiment includes a step of producing a raw tire and a step of vulcanizing the raw tire. The cord, coated rubber, and rubber composition described here are configured in the same manner as the cord, coated rubber, and rubber composition described above.

In the step of producing a raw tire, a sheet-like member comprising a plurality of aligned cords made of a metal material and a rubber composition covering the cords, which is wound in the circumferential direction. To produce a raw tire equipped with. In this step, specifically, on the inner liner, the carcass ply, which is a reinforcing member of the pneumatic tire, and the sheet-shaped member, which is a belt member, are wound around the forming drum in this order and connected. Repeat to stack. Further, a band-shaped member serving as a belt reinforcing member which is a reinforcing member of a pneumatic tire is spirally wound in the tire circumferential direction and laminated on the belt member so as to cover the belt member in the tire width direction. The cord included in each member serving as the carcass ply and the belt reinforcing member is an organic fiber cord. The sheet-like member to be the carcass ply is folded around a pair of bead cores and a rubber material to be a bead filler arranged on both sides in the width direction of the forming drum. The rubber material to be the sidewall portion is attached on the sheet-like member to be the carcass ply. A rubber material to be a tread portion is attached onto the laminated reinforcing member to produce a raw tire.

In the step of vulcanizing a raw tire, the raw tire is placed in a molding die and vulcanized to produce a vulcanized tire, that is, a pneumatic tire.

In the manufacturing method of the present embodiment, when the amount of cobalt present on the surface of the cord and the inner surface of the coated rubber is measured, the raw tire is manufactured so that the amount of cobalt on the surface of the cord is larger than the amount of cobalt on the inner surface. And the step of vulcanizing the raw tire.

In the step of producing a raw tire, the cord and the rubber composition contained in the raw material member to be the belt member may contain cobalt in at least one of them, but the amount of cobalt on the surface of the cord is adjusted to the cobalt on the inner surface of the coated rubber. It is preferable that the cord contains cobalt at least because it is easy to increase the amount. Before vulcanization, the amount of cobalt contained in the cord is preferably larger than the amount of cobalt contained in the rubber composition, but may be equal or smaller.

In the step of vulcanizing a raw tire, the vulcanization conditions are, for example, 3 to 60 minutes in a temperature range of 140 to 190 ° C. The vulcanization temperature is preferably in the temperature range of 145 to 180 ° C. When the vulcanization temperature is 190 ° C. or lower, the reaction between the metal element on the surface layer of the metal material and the sulfur in the rubber composition is sufficiently carried out, and the adhesive state between the metal material and the rubber material tends to be good. If the vulcanization temperature is too high, the vulcanization may be completed before a relationship is formed in which the amount of cobalt on the surface of the cord is greater than the amount of cobalt on the inner surface of the coated rubber. Further, in the above temperature range, the vulcanization time is preferably 10 to 40 minutes. When the vulcanization time is 10 minutes or more, the adhesive state tends to be good.

In the production method of the present embodiment, the vulcanization conditions of the rubber composition may be determined based on the determination result of the determination method described above.

The tire 10 described above can be manufactured by using the manufacturing method of the present embodiment. That is, it is possible to manufacture the tire 10 including the belt members 7 and 8 in which the amount of cobalt on the surface of the brass plating cord is larger than the amount of cobalt on the inner surface of the coated rubber. Therefore, according to the manufacturing method of the present embodiment, it is possible to obtain a tire 10 having a good adhesive state between the brass plating cord and the coated rubber and having improved durability.

(Experimental example)
In order to investigate the effect of the present invention, a test piece of a metal-rubber composite and a test sample of a belt member were prepared, the rubber adhesion rate was measured, and the cobalt amount ratio was obtained to determine the adhesion state between the metal material and the rubber material. Was evaluated.

In order to obtain the two types of rubber compositions "Rubber 1" and "Rubber 2" shown in Table 1, the components excluding sulfur and the vulcanization accelerator are kneaded at 160 ° C. for 5 minutes with a 1.8 L closed mixer. An unvulcanized rubber composition was prepared by adding sulfur and a vulcanization accelerator to the released master batch and kneading with an open roll.
On the other hand, the metal materials "Metal 1" and "Metal 2" having two composition ratios shown in Table 2 were prepared. Specifically, two brass plates (manufactured by Niraco, 2 mm thick) that look like metal materials with brass plating are prepared, and one brass plate is used as it is for "metal 1", and "metal 2" is used. To the surface of the other brass plate, a solution containing a cobalt salt was applied and dried to form a film containing the cobalt salt. As the solution, a solution prepared by dissolving cobalt stearate in acetone at a blending ratio of 10 parts by mass of cobalt stearate and 90 parts by mass of acetone was used. After applying this solution, the solution was allowed to stand in a warm air furnace at 60 ° C. for 10 seconds to remove the organic solvent to form a film containing a cobalt salt.
Next, each unvulcanized rubber composition is placed on each of the two brass plates with the combination of the metal material and the rubber composition shown in Table 3, and the vulcanization time shown in Table 3 is 170 ° C. Vulcanization was carried out in the mold to prepare 6 kinds of test pieces (Experimental Examples 1 to 6). A coated rubber was cut out from each test piece using a cutter so as to be scraped off from one surface of the brass plate in a region near the interface (a region having a depth of 10 to 500 μm from the interface of the rubber material with the brass plate). On the other hand, the rubber material remaining on the surface of the brass plate was swollen with toluene and removed. Then, the amount of cobalt was measured on the surface of the brass plate to which the rubber material was adhered and the inner surface of the rubber material in the manner described above, and the cobalt amount ratio was determined. The amount of cobalt was measured using the XAS method at New SUBARU BL10 of the University of Hyogo.

On the other hand, the rubber compositions "rubber 1" and "rubber 2" kneaded by the above method, and the brass plating cord corresponding to "metal 1" and "metal 2" as the metal materials having the composition ratios shown in Table 2 The corresponding brass plating cords having formed a film containing a cobalt salt were embedded in the rubber composition in parallel with each other at intervals of 12.5 mm in the combination shown in Table 3, respectively, at 170 ° C. (200 ° C in Experimental Example 6) Two types of test samples, a test sample that was vulcanized in the mold at the vulcanization time shown in Table 3, and a test sample that was further aged after vulcanization. Was produced. The aging treatment was carried out by leaving the test sample for 2 weeks in a moist heat environment with a humidity of 96% and a temperature of 70 ° C., which was prepared by using steam, and deteriorating it. After vulcanization, the rubber adhesion rate of the test sample not subjected to the aging treatment and the test sample subjected to the aging treatment was measured as follows. The measurement results of each test sample are shown in the columns of "after vulcanization" and "after deterioration" in Table 3.

(Rubber adhesion rate)
The cord was pulled out according to ASTM D1871, and the adhesion ratio of the rubber remaining on the cord (the ratio of the area of the rubber-adhered portion to the surface area of the cord) was visually measured.

(Adhesive state)
Regarding the test sample deteriorated by aging treatment, D is when the rubber adhesion rate is less than 30%, C is when it is 30% or more, and B is when it is 50% or more, and 80% or more. A case was evaluated as A.

The types of raw materials used for rubber 1 and rubber 2 shown in Table 1 are shown below. The numerical values in the table represent parts by mass (%).
・ NR: Natural rubber, RSS # 3
-CB: Carbon black (HAF-LS), manufactured by Tokai Carbon Co., Ltd., Seest 300
・ Zinc flower: manufactured by Shodo Chemical Industry Co., Ltd., 3 types of zinc oxide ・ Anti-aging agent: manufactured by Flexis Co., Ltd., Santoflex 6PPD
-Co stearate: manufactured by DIC Corporation-Sulfur: manufactured by AkzoNobel, Cristex HS OT 20
・ Vulcanization accelerator: Noxeller DZ manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

The numerical values in the table represent the concentration (atomic%) of the metal element measured by X-ray photoelectron spectroscopy.

From the comparison between Experimental Examples 1, 2, 4 and 5 and Experimental Examples 3 and 6, when the amount of cobalt on the surface of the metal material is larger than the amount of cobalt on the inner surface of the rubber material, the rubber adhesion rate after deterioration is 30%. It can be seen that the deterioration of the adhesive state over time due to deterioration can be suppressed. That is, it can be seen that the adhesive state between the metal material and the rubber material is good.
Further, from the comparison between Experimental Examples 1, 2 and 4 and Experimental Example 5, when the cobalt amount ratio is 150% or more, the rubber adhesion rate after deterioration exceeds 50%, and the adhesive state due to deterioration over time It can be seen that the effect of suppressing the deterioration is high.

From Experimental Examples 1 and 5, even if the rubber composition contains cobalt and the metal material does not contain cobalt, some cobalt is transferred from the rubber composition to the metal material by vulcanization, and the cobalt amount ratio. It was found that may exceed 100%.
Further, from Experimental Example 4, when the rubber composition does not contain cobalt and the metal material contains cobalt, some cobalt is transferred from the metal material into the rubber composition by vulcanization. It turns out that it may be done.

Although the method for determining the adhesive state of the present invention, the metal-rubber composite, the pneumatic tire, and the method for producing the pneumatic tire have been described above, the present invention is not limited to the above embodiments and examples, and the present invention is not limited to the above embodiments and examples. Of course, various improvements and changes may be made as long as the purpose is not deviated.

1 Tread part 2 sidewall part 3 bead part 4 carcass layer 5 bead core 6 bead filler 7, 8 belt member 9 belt reinforcing member 10 pneumatic tire 11 brass plating cord 11a brass plating cord surface 15 coated rubber 15a coated rubber interface 15b near the interface region

Claims (2)

It is a method of determining the adhesive state between a metal material and a rubber material covering the metal material.
The metal material has a plating layer containing brass or zinc as a main component on the surface layer.
It exists in the rubber material on the inner surface of the rubber material exposed in a region near the interface located along the interface at a distance from the interface with the metal material, and on the surface of the metal material, respectively. Measure the amount of cobalt and
When the amount of cobalt on the surface of the metal material is larger than the amount of cobalt on the inner surface of the rubber material, it is determined that the adhesion between the metal material and the rubber material is good. Judgment method. It ’s a method of manufacturing pneumatic tires.
A raw tire is produced which is a sheet-like member having a plurality of aligned cords made of a metal material and a rubber composition covering the cords, and which includes the sheet-like member wound in the circumferential direction. Steps and
The step of vulcanizing the raw tire is provided.
The cord has a plating layer containing brass or zinc as a main component on the surface layer.
In the vulcanized raw tire, the amount of cobalt contained in the cord is more than 0 atomic% and 10 atomic% or less, and the amount of cobalt contained in the coated rubber obtained by vulcanizing the rubber composition is 0 to 1 mass. % And
It exists in the coated rubber on each of the inner surface of the coated rubber exposed in a region near the interface located along the interface at intervals from the interface of the coated rubber with the cord, and the surface of the cord. when measured cobalt amount, so that the cobalt content of the surface of the cord is 150% to 400% of the cobalt content of the interior surface of the coating rubber, vulcanizing step, and, the raw tire to produce the raw tire A method of manufacturing a pneumatic tire, characterized in that steps are taken.

Images