JP2004189214A - Method of manufacturing support for runflat tire and support for runflat tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a support for runflat tires and a support for runflat tires that maintains high adhesion between a supporting portion and a leg, and that is superior in durability. <P>SOLUTION: In a method of manufacturing an ring support for runflat tires having a supporting portion and a leg capable of bearing loads during runflat-driving, surface treatment including chemical conversion is performed to an area where bonding with the leg is made at the radially inward end of at least the supporting portion, and the radially inward end and the leg are bonded. In addition, a support for runflat tires is obtained by this manufacturing method or the like. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a support for an annular run flat tire and a support for a run flat tire, which are disposed inside a tire so that the support can be run for a considerable distance in a punctured state.

A run-flat tire can be run with a pneumatic tire, that is, a tire that can run with a certain distance without worry even if the tire internal pressure becomes 0 kg / cm ^{2 due} to puncturing (hereinafter referred to as a run-flat tire). A core type in which an annular core (support) made of metal or synthetic resin is attached to a rim portion in a tire air chamber (for example, see Patent Documents 1 and 2).

  As the core type, a rotary core type incorporated in a rim and a core type having two convex portions in a tire radial cross section attached to the rim (a double mountain shape) are known (for example, Patent Document 1). 3-6). The rotating core type has a problem in versatility in that a special wheel for fixing the rotating core is required. On the other hand, the double-core type is highly versatile because it can be attached to a conventional rim.

  In the case of ordinary anti-vibration rubber, it is used in a temperature range equivalent to the temperature of the outside air, but the inside of the tire is high pressure by pressurized air, and the temperature rises during running, so it is expected that the degradation environment will be quite severe Is done. On the other hand, in the past studies, little consideration was given to the deterioration of the support portion main body and the corrosion when the main body was made of metal.

Since the annular support is required only for run flat traveling, it is desirable that the annular support be made of a light material.
When the vehicle is run with this support assembled in the tire, moisture and acid ions derived from the rubber compound of the tire are present in the tire, and the temperature rises. Degradation due to being inside cannot be ignored.

  The support for the run flat tire has an annular leg bonded to both ends of the support, and is attached to the rim via the leg. At this time, in order to improve the adhesiveness between the both ends of the support portion and the leg portions, the bonded portion of the support portion may be subjected to a surface roughening treatment by shot blasting.

However, it was impossible to maintain a high adhesive force for a long time in the above-mentioned roughening treatment.
Also, regardless of the presence or absence of the above-mentioned surface roughening treatment, if there is uneven bonding at the bonding portion of the support portion, it may cause corrosion or the like, or cause poor bonding, leading to running stability or durability. May affect the run flat characteristics of the
Further, there is a problem in corrosion resistance such that rust may be generated at the support portion to which the legs are not adhered since the metal is exposed.

  During run-flat running when the internal pressure of the tire drops for some reason, the support as a composite of the metal support and the rubber legs supports the load, but the support composite rotates due to this load. While repeatedly receiving distortion, heat is generated due to the distortion. Run flat traveling guarantees that the vehicle can travel a certain distance without any problem (for example, it can travel 50 km or more at an speed of 80 km / h, etc.). Depending on the case, the temperature may exceed 150 ° C., and in the case of a support joined by applying a conventional two-component coating type vulcanizing adhesive, at the interface between the top coating adhesive of the support portion and the rubber leg and the rubber composition. There was a problem that peeling occurred and run-flat running could not be performed a sufficient distance.

Also, during run-flat running, the load is held by the convex portion of the support contacting the rear surface of the tire tread during emergency running with reduced internal pressure, but during emergency running in a state where the vehicle weight is heavy and the supporting load is large. For example, a heavy load is applied to the tire tread portion, and eventually the tire tread portion may fail to run due to failure.
Patent Literature 4 discloses a core to which a lubrication system is added in order to suppress damage to the back surface of the tread portion. Is not disclosed.
JP-A-2002-377519 JP-T-2001-519279 JP-A-10-297226 JP 2001-163020 A JP 2003-48410 A U.S. Pat. No. 6,463,974 B1

  From the above, it is an object of the present invention to provide a method for producing a run-flat tire support excellent in durability while maintaining high adhesion between the support portion and the leg, and to provide the run-flat tire support. .

The above object is achieved by the present invention described below.
That is, the present invention
<1> A method for producing an annular run-flat tire support having a support portion and a leg portion and capable of supporting a load during run-flat running,
A run-flat tire wherein a surface treatment including a chemical conversion treatment is applied to at least a bonding region with the leg at a radially inner end of the support portion, and the radially inner end and the leg are bonded to each other. This is a method for producing a support for use.
<2> The method for producing a run-flat tire support according to <1>, wherein the surface of the support portion is a metal material.
<3> The support for a run-flat tire according to <1> or <2>, wherein the support portion other than the adhesion region is subjected to rust prevention treatment, or the surface treatment and rust prevention treatment. It is a manufacturing method.
<4> The support for a run-flat tire according to any one of <1> to <3>, wherein the rust preventive treatment is a rust preventive coating process or a plating process for applying a rust preventive paint. Is the way.
<5> The method for producing a run-flat tire support according to any one of <1> to <4>, wherein the bonding between the radially inner end and the leg is vulcanization bonding. is there.
<6> The support for a run flat tire according to any one of <3> to <5>, wherein the leg portion is covered with a masking member, the support portion is exposed, and the rust prevention treatment is performed. Is a manufacturing method.

<7> A method for producing an annular run-flat tire support having a support portion and a leg portion and capable of supporting a load during run-flat running,
At least at the radially inner end of the support portion, the unvulcanized leg is subjected to a vulcanization bonding process via an adhesive to a bonding region with the leg, and the leg is bonded to the bonding region. Having a bonding process,
The application processing of the adhesive in the bonding step, after applying a primer adhesive to the bonding area, is a processing of applying a top coating adhesive,
The method for producing a support for a run-flat tire, wherein the overcoat adhesive is an adhesive containing a maleimide derivative.
<8> The method for producing a support for a run flat tire according to <7>, wherein the applied film thickness of the top coat adhesive is 2 μm or more.
<9> The method for producing a support for a run flat tire according to <7> or <8>, wherein at least the support portion is subjected to a chemical conversion treatment with a zinc phosphate-based treating agent.
<10> The method for producing a support for a run-flat tire according to any one of <7> to <9>, wherein the undercoat adhesive is an adhesive containing no halogen.

  <11> A run-flat tire support manufactured by the method for manufacturing a support according to any one of <1> to <10>.

<12> An annular run flat tire support having a support portion and a leg portion and capable of supporting a load during run flat running,
Part or all of the surface is covered with a coating layer,
The coating layer is any one of a resin layer containing a resin, a coating layer made of a paint containing a resin, a vulcanized adhesive layer containing a rubber component, and a rubber composition layer containing a diene rubber as a main component. A support for a run-flat tire, characterized in that:
<13> The run-flat tire support according to <12>, wherein a chemical conversion treatment with an inorganic salt-based chemical conversion treatment agent is performed in advance on at least a region where the coating layer is formed.

<14> An annular run-flat tire support having a support portion and a leg portion and capable of supporting a load during run-flat running,
At least the support is made of 780N class high-tensile steel, and is a run-flat tire support.
<15> The feature described in <14>, wherein the support portion is processed by drawing, and the carbon content in the 780N class high-tensile steel is 15 × 10 ⁻² % or less and the elongation is 20% or more. Is a support for a run flat tire.
<16>
The run-flat tire support according to <14> or <15>, wherein the 780N class high-tensile steel has a carbon equivalent of 0.6 or less.
<17> The run-flat tire support according to any one of <14> to <16>, wherein at least the cleanliness of the support portion is 0.05 or less.

<18>
The support portion has one or more convex portions projecting outward in a radial cross section, and one or more concave portions projecting inward,
At least one of the protrusions is constituted by a plurality of arcs having different radii of curvature, and among these arcs, the radius of curvature of the arc including the apex of the protrusion is the largest,
A distance (W) between the convex portion and another convex portion closest to the convex portion, a height (H) of the convex portion, a number (N) of the one or more convex portions, and a The run-flat tire support according to any one of <14> to <17>, wherein a curvature radius (R) of an arc including the vertex has a relationship represented by the following expression (1).
Formula (1): R (mm) ≧ 12 W / HN

As described above, according to the method for manufacturing a support for a run flat tire of the present invention, the support portion and the leg have high adhesiveness, and a support for a run flat tire having excellent durability can be manufactured. .
Further, in the support for a run flat tire of the present invention, the support portion and the leg portion have high adhesiveness, and the deterioration of the support portion and the damage of the contact portion between the support portion and the inner surface of the tire are reduced. , Its durability is excellent.

[Method of Manufacturing Support for Run Flat Tire]
(First manufacturing method)
Hereinafter, a first method for producing a support for a run flat tire of the present invention will be described.
First, a support portion of a support for a run flat tire is prepared. A flat metal plate is formed into a shape as shown in FIG. 1 by a forming method such as roll forming. That is, the drawing has curved portions 30A and 30B projecting upward and a curved portion 30C projecting downward, and has a shape having flange portions 30F and 30G at both ends. Then, as shown in FIG. 2, the support portion 26 of the support 16 is formed into a ring shape by bending or the like.
Here, as the material used for the metal flat plate, it is preferable to use a material whose surface is at least made of a metal material. Such materials include iron, high tension steel, SUS, aluminum and the like.

A surface including a chemical conversion treatment in a radially inner end portion (hereinafter, simply referred to as an “end portion”) of a support portion, in a region where the leg portion is attached to the end portion when the leg portion is provided (adhesion region). Perform processing.
In the case of the support portion 26 of the support 16 shown in FIG. 2, at least the entire flange portions 30F and 30G are subjected to a surface treatment including a chemical conversion treatment.

The chemical conversion treatment is a process for forming a thin film made of an inorganic salt on the metal surface of the support portion 26 to impart corrosion resistance to the metal surface or to improve the adhesion between the legs and the support portion 26 described later. . Therefore, by performing such a chemical conversion treatment, the adhesiveness between the adhesive region of the support portion 26 and the leg portion is improved, and high adhesiveness can be maintained even for a long run flat run.
Such adhesion is caused by the fact that phosphates and the like used in the chemical conversion treatment are crystallized on the metal surface, which is an adhesion region, to form a thin film. That is, it is considered that the film to be formed has irregularities, and the presence of the irregularities imparts an anchor effect to obtain high adhesive strength. In addition, the presence of such a film makes it possible to further improve the rust prevention effect (corrosion resistance effect) when the support portion 26 is subjected to rust prevention treatment later.

As the chemical conversion agent used for the chemical conversion treatment, phosphates such as zinc phosphate, zinc iron phosphate, zinc calcium phosphate, iron phosphate and manganese phosphate can be used. Practically, the above-mentioned chemical conversion agent is appropriately dissolved in a solvent and used.
The thickness of the film formed by the chemical conversion treatment is preferably from 0.1 to 50 μm, more preferably from 0.5 to 5 μm.

Examples of the surface treatment other than the chemical conversion treatment include a surface treatment (coating treatment) for applying chromate chromate, organic acid titanate, or the like. Also in this case, the above-mentioned treating agent is used after being appropriately dissolved in a solvent or the like.
The thickness of the coating formed by the coating treatment is preferably 0.1 to 50 μm, and more preferably 0.5 to 5 μm.

It is preferable that the rust prevention treatment is performed at least on the portion where the chemical conversion treatment has been performed. By performing the rust-preventive treatment at the place where the chemical conversion treatment has been performed, it is possible to prevent the generation of rust and the like and to further improve the corrosion resistance.
Further, the rust prevention treatment is also applied to the support portion other than the bonding area. Since such a portion is in a state where the metal is exposed, it is in an environment that is easily corroded, and corrosion resistance can be imparted by performing rust prevention treatment.

As the rust-preventive treatment, a rust-preventive coating treatment or a plating treatment, preferably, in which a rust-preventive paint is applied, may be mentioned.
It is preferable that the thickness of the coating film formed at the time of performing the rust-proof coating be 0.1 to 500 μm. If it is less than 0.1 μm, a sufficient rust-preventing effect may not be obtained, and if it exceeds 500 μm, cracks may be generated on the surface.

As a material used for the rust-preventive coating, a rust-preventive paint used for general metals can be applied. Specific examples include acrylic resin paint, polyester resin paint, polyurethane resin paint, epoxy resin paint, fluororesin paint, and silicon paint.
Further, examples of the plating treatment described above include zinc plating, chrome plating, and electrodeposition coating. The preferred plating thickness is the same as in the case of the antirust coating.

The chemical conversion treatment and the rust prevention treatment can be carried out by a method of immersion in these treatment liquids; a method of spraying a surface treatment agent or a rust preventive (rust preventive paint) using a spray.
In particular, when performing rust prevention treatment, it is preferable to cover the legs with a masking member, expose the support portion, and perform rust prevention treatment. At this time, it is preferable to perform spray coating while rotating the support. By covering the masking member, it is possible to selectively perform a rust prevention treatment on a desired range.

After performing the surface treatment and the rust prevention treatment that is performed if necessary, an adhesive is applied to the bonding portion of the support portion and vulcanized and bonded to the leg portion (adhesion process), so that the leg portion is formed at both ends. The formed support is produced.
After the surface treatment, the legs may be vulcanized and bonded, and then the support may be subjected to rust prevention treatment.

As the adhesive used for the vulcanization bonding, it is preferable to use a vulcanization type adhesive for rubber of synthetic resin type, phenolic resin type, silicone type or the like.
As conditions for the vulcanization bonding, the temperature is preferably from 120 to 200 ° C., and the time is preferably from 5 to 60 minutes.
Examples of the material used for the legs include NR (natural rubber), IR (isoprene rubber), BR (butadiene rubber), SBR (styrene butadiene rubber), and IIR (butyl rubber). .

It is preferable to perform a primer treatment before applying the adhesive. As the primer, it is preferable to use a synthetic rubber-based or epoxy-based primer containing at least one kind of polyisocyanate, epoxy resin, synthetic rubber, or the like.
Such processing is performed when a so-called two-component adhesive is used. That is, a primer layer formed by the primer treatment and a cover coat layer are formed on the primer layer on the adhesive portion.

(Second manufacturing method)
In the second method for manufacturing a support for a run-flat tire of the present invention, at least a radially inner end portion of the support portion is bonded to the leg portion with the unvulcanized leg portion via an adhesive. And a bonding step of bonding the legs to the bonding area by performing a heat bonding process.

  In a support in which legs are joined by applying a conventional two-component coating type vulcanizing adhesive, during run-flat running, a top coat adhesive and a rubber composition applied to an adhesion region between the support and the legs are applied. Peeling occurs at the interface. Therefore, in the present invention, the application process of the adhesive in the bonding process is a process of applying a top coat adhesive to a bonding area, and then applying a top coat adhesive, and using an adhesive containing a maleimide derivative in the top coat adhesive. .

  As a result of intensive studies by the present inventors, it has been found that there is a large difference in durability depending on the type of the topcoat adhesive. And, among the overcoating adhesives, it was found that when an adhesive containing a maleimide derivative was used, the bonding portion was relatively stable even when the heat generation temperature was high, so that the traveling distance until peeling was long. .

  The applied film thickness of the topcoat adhesive is preferably 2 μm or more. When the thickness is 2 μm or more, a stable adhesive force can be more reliably exhibited. The coating thickness is more preferably 5 μm or more.

  Further, it is preferable that at least the support portion is subjected to a chemical conversion treatment with a zinc phosphate treating agent. The surface treatment method on the support portion side also has an effect on the run flat durability, and the durability can be improved more by performing a chemical conversion treatment with a zinc phosphate-based treating agent than by performing no surface treatment. In order to further improve the durability, it is preferable to use blasting together.

The undercoat adhesive is preferably an adhesive containing no halogen.
In the undercoat adhesive, good adhesive strength can be maintained by using an adhesive containing no halogen. Further, even in the case where the undercoating adhesive is used in combination with a topcoating adhesive containing a maleimide derivative, the run-flat durability can be further improved by using an adhesive containing no halogen.
Further, the coating thickness is preferably 1 to 5 μm, more preferably 2 to 5 μm.

  In addition, the vulcanization bonding process has no problem of peeling at the interface between the rubber and the topcoat adhesive even when used under a high load applied high temperature environment, and manufactures a run flat support used under a high load applied high temperature environment. It is suitable for.

[Support for run flat tire]
The support manufactured by the first and second manufacturing methods of the present invention can be applied to various pneumatic run-flat tires. FIG. 3 shows an example of a pneumatic run-flat tire to which the support can be applied.

The (pneumatic) run flat tire 10 refers to a rim 12 on which a pneumatic tire 14 and a support 16 are assembled, as shown in FIG. The rim 12 is a standard rim corresponding to the size of the pneumatic tire 14.
As shown in FIG. 3, the pneumatic tire 14 includes a pair of bead portions 18, a toroidal carcass 20 extending across both the bead portions 18, and a plurality of carcass 20 located in a crown portion of the carcass 20 (the present embodiment). (2 sheets in FIG. 2) and a tread portion 24 formed on the belt layer 22.
The support 16 disposed inside the pneumatic tire 14 has a cross section shown in FIG. 3 formed in a ring shape, and is vulcanized at both ends of the support 26 and the support 26. Rubber legs 28.

  In the pneumatic run-flat tire as described above, the support 16 manufactured as described above is disposed inside the pneumatic tire 14, and the leg 28 of the support 16 is fixed together with the pneumatic tire 14 to the rim 12. It is manufactured by assembling.

Here, the standard rim is a rim specified in JATMA (Japan Automobile Tire Association) Year Book 2002 edition, and the standard load is a maximum rim when a single wheel of JATMA (Japan Automobile Tire Association) Year Book 2002 edition is applied. This is a load corresponding to the load capacity.
Outside Japan, the load is the maximum load (maximum load capacity) of a single wheel at the applicable size described in the following standard, and the internal pressure is the maximum load (maximum load of the single wheel) described in the following standard Rim) means a standard rim (or “Approved Rim” or “Recommended Rim”) in an applicable size described in the following standard.
Standards are determined by industry standards that are in effect in the area where the tire is manufactured or used. For example, in the United States, "The Book of The Tire and Rim Association Inc." and in Europe, "Standards Manual of The European Tire and Rim Technical Organization".

  In the pneumatic run-flat tire as described above, when the internal pressure of the pneumatic tire 14 is reduced, the rear surface of the tread portion 24 of the pneumatic tire 14 is moved to the convex portion of the support 16 (the radial direction of the support 16 in the drawing). (A portion protruding outward) is supported to enable travel.

  In addition, as the support for a run flat tire described above, if the support and the leg are joined by applying the above-described first or second manufacturing method of the present invention, the following aspects are provided. Support.

(First support)
The first support of the present invention has a support portion and a leg portion, has an annular structure capable of supporting a load during run-flat running, and has a part or all of its surface covered with a coating layer. The coating layer is any one of a resin layer containing a resin, a coating layer made of a paint containing the resin, a vulcanized adhesive layer containing a rubber component, and a rubber composition layer containing a diene rubber as a main component. It is.
Corrosion (rust) is caused by the presence of moisture, oxygen (oxidizing agent) and metal, causing a local battery action. Therefore, it is necessary to prevent any of the above substances from coming into contact with the coating layer. Depending on the material of the coating layer, there is a difference in the isolation effect (moisture permeability, oxygen permeability, oxidant permeability), so that the rust prevention level is different. Therefore, the coating layer is a layer as described above.

As the resin layer containing a resin, a phenol resin, an alkyd resin, an epoxy resin, or the like can be used.
As the coating layer made of a resin-containing paint, a composition or the like containing the above resin and a paint such as a rust preventive paint can be used.
As the vulcanized adhesive layer containing a rubber component, a layer composed of a vulcanized adhesive layer containing natural rubber, isoprene rubber, polybutadiene rubber, polystyrene-butadiene rubber, or the like can be used.
The rubber composition layer containing a diene rubber as a main component is not particularly limited as long as the rubber composition layer contains a diene rubber as a main component, but a layer containing a natural rubber, an isoprene rubber, a polybutadiene rubber, a polystyrene-butadiene rubber, or the like is used. it can.

From the viewpoint of corrosion resistance, the thickness of each of the above layers is preferably 1 to 5 mm, more preferably 2 to 4 mm.
As shown in FIG. 4, the coating layer 100 may be provided on the entire surface of the support portion on the back surface side of the tread portion. As shown in FIG. 5, a region (convex portion) that comes into contact with the back surface of the tread portion during run flat running. May be selectively provided.

  It is preferable that a chemical conversion treatment with an inorganic salt-based chemical conversion treatment agent is performed in advance on at least a region where the coating layer is formed. Since the chemical conversion film (inorganic salt) has a greening effect, the effect of coating increases. In other words, there is an effect that the local battery action hardly occurs. In the chemical conversion treatment, for example, a chemical conversion agent as described above can be used, and among them, zinc phosphate is preferable. Further, as the rust preventive treatment, a rust preventive paint composition containing a paint and a pigment in a synthetic resin can be used. At this time, as the synthetic resin, phenol, alkyd, epoxy, isocyanate-containing compounds and other various resins can be used.

(Second support)
The second support of the present invention is an annular run-flat tire support having a support portion and a leg portion and capable of supporting a load during run-flat running, and at least the support portion is made of 780N class high-tensile steel. Become.
Further, the support portion preferably has one or more convex portions projecting outward in a radial cross section and one or more concave portions projecting inward.
Further, as shown in FIG. 6, at least one of the convex portions is constituted by a plurality of arcs having different radii of curvature, and among these arcs, the convex portions (Ra1 and Rb1 in FIG. 6) are formed. The radius of curvature of the arc including the vertex is the largest.

Then, the distance (W) between one convex portion and another convex portion closest to the convex portion, the height (H) of one convex portion, the number (N) of one or more convex portions, and It is preferable that the radius of curvature (R) of an arc including the apex of the convex portion has a relationship represented by the following expression (1).
Formula (1): R (mm) ≧ 12 W / HN

The convex portion of the support portion is composed of a plurality of circular arcs having different radii of curvature, and among these circular arcs, the radius of curvature of the circular arc including the apex of the convex portion is maximized. The contact area with the support is larger than when the convex curve portion is constituted by an arc having a single radius of curvature.
For this reason, the load on the inner surface of the tread during an emergency running with the internal pressure lowered is reduced, and damage to the tread is suppressed. Here, the “apex of the convex portion” refers to a portion where the height H from the flange portions 30F and 30G of the support portion is largest, as shown in FIG. The “space (W) between one convex portion and another convex portion closest to the convex portion” is, as shown in FIG. 6, the distance between the vertex (Ra1) and the convex portion (Rb1) of each convex portion. The distance between them.

In order to effectively exert the above-described functions, the following configurations (1) to (6) are preferable.
(1) It is preferable that the absolute value of the radius of curvature of the arc including the apex of the projection is 25 mm or more.
(2) It is preferable that the width of the arc portion including the apex is about 80% of the width (Wa) of the convex portion. Here, the “convex width” refers to the distance between the deepest portion (Rc1) of the concave portion and the end of the flange portion 30F, as shown in FIG.
(3) The width of the arc portion including the apex is preferably about 40% of the width of the support portion (Wb). Here, the "width of the support portion" refers to the distance between the end of the flange 30F and the end of the flange 30G as shown in FIG.
(4) It is preferable that the supporting portion has a thickness of 1 to 2 mm. Further, it is preferable that the high strength steel sheet has a tensile strength of 80 kg / mm ² . Note that an aluminum alloy, FRP, or the like may be used as long as the tensile strength can be realized.

(6) It is preferable that the support portion of the support is a closed ring. Note that a slit may be provided as described in JP-A-2003-48410.
(7) The legs are preferably made of a rubber elastic material. Note that a multilayer structure such as US Pat. No. 6,649,474 B1 may be applied.
(8) It is preferable that the cross-sectional shape of the support portion includes two convex portions and one concave portion located therebetween. Note that a configuration having three or more convex portions may be used, such as “convex portion + concave portion + convex portion + concave portion + convex portion”. Preferably, the number of convex portions is 2 to 4.
(9) Specifically, it is preferable to use the tire size: 225 / 60R17, the applicable rim: 7JJ × 17, and the support preferably has a total width of 150 mm and a radial height of 60 mm.
(10) It is preferable that the cross-sectional shape of the support portion be bilaterally symmetric with respect to the equatorial plane. Note that the vehicle may be left-right asymmetric in consideration of a camber or the like when mounted on a vehicle.

  As for the above-mentioned first support of the present invention, it is preferable that at least the support portion is made of 780N class high tensile steel.

Conventionally, a low-strength (380 N or less) steel material has been used as a material for the support portion, and the support portion has been obtained by drawing. Since the above-mentioned steel material has low strength, it is thick and heavy to support the load at the time of run flat.
In order to solve this problem, if a steel plate having a higher strength (780 N or more) is used, the formability is extremely poor, and the steel cannot be formed into a metal shell shape.
Then, as a result of studying the above causes, the following three points were focused on the first and second supports.
(1) The elongation of the material is low and the material cracks during drawing.
Elongation can be improved by reducing the amount of carbon in steel.
(2) The welded portion of the material becomes hard and becomes discontinuous during drawing, and cracks occur at and near the welded portion. This can be solved by reducing the carbon equivalent.
(3) Impurities (manganese-based oxides and the like) contained in the material serve as a starting point, and may be broken during drawing. Therefore, the moldability can be improved by reducing these impurities.

Examples of the drawing method (1) include spatula drawing, spinning, roll forming, and hydroforming. In any case, in order to obtain a support ring-shaped molded product, the elongation percentage of the material in the main direction is required. Over 10%. When the elongation percentage in the main direction exceeds 10%, the elongation of the material is preferably 20% or more, more preferably 22% or more. If it is less than this, the material will break during processing. For this purpose, the amount of carbon is preferably set to 15 × 10 ⁻² % or less, and more preferably 10 × 10 ⁻² % or less. If it exceeds 15 × 10 ^-2 %, the elongation may not be increased to 20% or more.

In order to obtain the strength of the material even if the carbon is reduced in (2), Si, Mn, P, S, etc. are blended as components other than carbon to obtain the strength. Among them, what is called carbon equivalent is assumed below.
"Ceq (carbon equivalent) = C + Si / 24 + Mn / 6"
C, Si, and Mn in the above carbon equivalent formula indicate the contents (% by mass) of carbon, silicon, and manganese, respectively.

  The carbon equivalent is preferably 0.6 or less, more preferably 0.55 or less. If it exceeds 0.6, the HV value of the hardness of the welded portion exceeds 400, resulting in a discontinuous point, and a significant decrease in elongation, which may cause breakage during drawing.

  As an inclusion contained in the steel material of (3), there is an oxide of Mn, which serves as a starting point at the time of molding and breaks the material. The amount of the inclusions is defined by a parameter called cleanliness in JIS G055. The cleanliness is desirably 0.05 or less, and more desirably 0.02 or less. If it exceeds this, the inclusion may be used as a starting point, and the material may be broken during molding.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.
(Example 1)
The support portion of the support was formed from a flat plate (high-strength steel plate: thickness 1.6 mm) into a shape as shown in FIGS. 1 and 2 by a roll forming method.
A chemical conversion treatment (surface treatment) using zinc phosphate as a chemical conversion agent was applied to the region where the leg portion including the flange portion is formed and the support portion. The coating thickness was 4 μm.

Thereafter, an acrylic resin paint was applied to the support portions other than the portions where the leg portions were to be formed, and a rust-proof coating treatment was performed to form a 50 μm thick coating film.
An adhesive was applied to the locations where the legs were to be formed and vulcanized to form a support having the legs adhered to the ends.

(Example 2)
Except that a SUS304L (2.0 mm thick) flat plate was used in place of the high-tensile steel plate, and rust-proof coating treatment (coating thickness: 50 μm) was performed with a polyester resin paint instead of the acrylic resin paint. In the same manner as in Example 1, a support was produced.

(Example 3)
A support was produced in the same manner as in Example 1, except that a surface treatment of applying chromate chromate (thickness: 4 μm) was performed on the chemical conversion treatment.

(Example 4)
A support was produced in the same manner as in Example 1 except that the rustproofing treatment was not performed.

(Comparative Example 1)
A support was produced in the same manner as in Example 1 except that the chemical conversion treatment and the rust prevention treatment were not performed.

(Comparative Example 2)
A support was produced in the same manner as in Example 1 except that a flat plate of SUS304L (2.0 mm in thickness) was used instead of the high-tensile steel sheet, and the chemical conversion treatment and the rust prevention treatment were not performed.

The supports prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were sprayed with salt water to evaluate the time for the support to peel off from the legs and the time for the support to be rusted when the legs were not bonded. A saltwater test was performed. The results are shown in Table 1 below.
In the salt water test, a 35 ° C. aqueous sodium chloride solution (5% by mass) was used.

  As shown in Table 1, by performing the surface treatment including the chemical conversion treatment, it was possible to produce a support having higher adhesion to the legs and not corroding for a long time as compared with the comparative example.

The same configuration as the above-described pneumatic run flat tire (see FIG. 3), in which the support produced in Examples 1 to 4 is inserted into a 205 / 50R16 size pneumatic tire corresponding to the above tire size A run flat tire was manufactured by assembling the standard rim (6J).
When the run flat tire (200 km) was actually run on the manufactured run flat tire and the support after the run was observed, particularly in the support manufactured in Examples 1 to 3, rust or the like was generated on the support portion. There was no problem in appearance. Further, in the supports prepared in Examples 1 to 4, the adhesion between the support portions and the leg portions was good.

(Examples 5 to 12 and Comparative Examples 4 and 5)
An unvulcanized leg is subjected to a vulcanization bonding process via an adhesive at a radially inner end portion of the support portion at a bonding region with the leg, and the leg is bonded to the bonding region (bonding step). . The application of the adhesive was performed by sequentially applying the undercoat adhesive and the overcoat adhesive to the above-mentioned bonding area. The undercoat adhesive and the topcoat adhesive are as shown in Table 2 below. In Examples 5 to 8 and Comparative Example 5, a chemical conversion treatment was performed with a zinc phosphate-based chemical before the bonding step.

  The same configuration as the above-described pneumatic run flat tire (see FIG. 3), in which the support produced in Examples 1 to 4 is inserted into a 205 / 50R16 size pneumatic tire corresponding to the above tire size A run flat tire was manufactured by assembling the standard rim (6J). The oxygen internal pressure was set to 230 kPa, and the mixture was left in a constant temperature room at 70 ° C. for 2 weeks. Runflat mounted each test tire on the right rear wheel of the FR car, pulled out the core of the air valve, made the inside of the tire the same as the atmospheric pressure, and displayed the INDEX distance until a failure occurred. The larger the value, the better.

  From Table 2, it was confirmed that the supports prepared in Examples 5 to 12 had good adhesion between the support portions and the leg portions.

(Example 13)
In the same manner as in Example 1, the support and the leg were bonded. Except that the surface layer of the support was as shown in Table 3 below, legs were provided by the method of Example 1 to produce a support. A coating layer (3 mm) was formed by applying Chemlock 254 (top coat adhesive) to the surface of the support portion on the back surface side of the tread portion.

(Examples 14 to 24 and Reference Examples 1 and 2)
A support was produced in the same manner as in Example 13, except that the coating layer was as shown in Table 3 below.

The supports prepared in Examples 13 to 24 and Reference Examples 1 and 2 were subjected to SST durability (evaluation by salt spray test (SST) (JIS-Z-2371)). Specifically, a salt spray test for 480 hours was performed according to JIS-Z-2371, and evaluated according to the following criteria. The results are shown in Table 4 below.
The evaluation indices were as follows.
：: No rusting, no peeling of coating film was observed at all, and it was extremely excellent in practical use.
：: Although rusting and coating peeling were slightly observed, it can be said that it is practically excellent.
Δ: Rust and peeling of the coating film were slightly recognized, but there was no problem in practical use.
X: Rust and coating film peeling were slightly observed.
In addition, as an accelerated deterioration test, an actual vehicle run flat durability is measured by assembling a rim with a support at normal pressure, filling oxygen in the tire at an internal pressure of 230 kPa, and allowing the tire to stand in a constant temperature room at 70 ° C. for 2 weeks. In the run-flat running, each test tire was mounted on the right rear wheel of the FR vehicle, the core of the air valve was removed, the inside of the tire was made equal to the atmospheric pressure, and the running distance until the occurrence of a failure was indicated by INDEX.

  From Table 4, it was confirmed that all of the supports of Examples 13 to 24 had excellent durability.

(Example 25 and Reference Example 3)
Except that the shape of the support (using 780N class high-tensile steel for the support portion) was as shown in FIG. 6 and the settings of Ra1 to 3 and Rb1 to 3 and Rc1 in FIG. 6 were as shown in Table 5 below. Produced a support by the method of Example 1.
The test conditions for the RF durability are as follows. A test tire incorporating the above support is mounted on a 2500 cc rear-wheel drive passenger car, and the tire pressure at the right rear wheel is set to 0 kPa, the other three tire pressures are set to 210 kPa, and the tire runs at 90 km / h until a failure occurs. I let it. The results were indicated by an index with reference to Reference Example 3 being 100. The larger the value, the better the durability.

  From Table 5, it was confirmed that the durability of the support of Example 25 was further improved.

(Example 26 and Reference Examples 4 to 6)
A support was produced in the same manner as in Example 25, except that the material and characteristics of the support were as shown in Table 6 below. The inclusions in Table 6 refer to manganese oxide.

  The support portion of the support of Example 26 could be formed without breakage in the middle, but in Reference Examples 4 to 6, breakage occurred at a welded portion or the like and could not be formed.

It is a partial perspective view of the support part of a support body. It is a perspective view of a radial half cross section of a support body. FIG. 2 is a cross-sectional view of the pneumatic run flat tire when the rim is mounted. FIG. 2 is a cross-sectional view of the pneumatic run flat tire when the rim is mounted. FIG. 2 is a cross-sectional view of the pneumatic run flat tire when the rim is mounted. It is a partial sectional view for explaining the shape of a support.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 10 Pneumatic run flat tire 12 Rim 14 Pneumatic tire 16 Support 24 Tread 26 Support 28 Leg

Claims (18)

A method for producing an annular run flat tire support having a support portion and a leg portion and capable of supporting a load during run flat running,
A run-flat tire wherein a surface treatment including a chemical conversion treatment is applied to at least a bonding region with the leg at a radially inner end of the support portion, and the radially inner end and the leg are bonded to each other. Of producing a support for a vehicle.   The method for manufacturing a support for a run-flat tire according to claim 1, wherein the surface of the support portion is a metal material.   The method for manufacturing a support for a run-flat tire according to claim 1, wherein the support portion other than the adhesion region is subjected to a rust prevention treatment, or the surface treatment and the rust prevention treatment.   The method for producing a run-flat tire support according to any one of claims 1 to 3, wherein the rust prevention treatment is a rust prevention coating treatment or a plating treatment for applying a rust prevention paint.   The method for producing a support for a run-flat tire according to any one of claims 1 to 4, wherein the bonding between the radially inner end and the leg is vulcanization bonding.   The method for producing a run-flat tire support according to any one of claims 3 to 5, wherein a masking member is put on the leg, the support is exposed, and the rust prevention treatment is performed. A method for producing an annular run flat tire support having a support portion and a leg portion and capable of supporting a load during run flat running,
At least at the radially inner end of the support portion, the unvulcanized leg is subjected to a vulcanization bonding process via an adhesive to a bonding region with the leg, and the leg is bonded to the bonding region. Having a bonding process,
The application processing of the adhesive in the bonding step, after applying a primer adhesive to the bonding area, is a processing of applying a top coating adhesive,
The method for producing a support for a run-flat tire, wherein the overcoat adhesive is an adhesive containing a maleimide derivative.   The method for producing a support for a run-flat tire according to claim 7, wherein the applied film thickness of the top coat adhesive is 2 µm or more.   The method for producing a run-flat tire support according to claim 7 or 8, wherein at least the support portion is subjected to a chemical conversion treatment with a zinc phosphate-based treating agent.   The method for producing a support for a run-flat tire according to any one of claims 7 to 9, wherein the undercoat adhesive is an adhesive containing no halogen.   A run-flat tire support manufactured by the method for manufacturing a support according to claim 1. An annular run-flat tire support having a support portion and a leg portion and capable of supporting a load during run-flat running,
Part or all of the surface is covered with a coating layer,
The coating layer is any one of a resin layer containing a resin, a coating layer made of a paint containing a resin, a vulcanized adhesive layer containing a rubber component, and a rubber composition layer containing a diene rubber as a main component. A support for a run flat tire, characterized in that:   The run-flat tire support according to claim 12, wherein a chemical conversion treatment with an inorganic salt-based chemical conversion treatment agent is performed in advance on at least a region where the coating layer is formed. An annular run-flat tire support having a support portion and a leg portion and capable of supporting a load during run-flat running,
A support for a run-flat tire, wherein at least the support portion is made of 780N class high-tensile steel. 15. The run flat according to claim 14, wherein the support portion is processed by drawing, and the carbon content in the 780N class high-tensile steel is 15 * 10 ^<-2 >% or less and the elongation is 20% or more. Support for tires.   The run-flat tire support according to claim 14 or 15, wherein the 780N class high-tensile steel has a carbon equivalent of 0.6 or less.   The run-flat tire support according to any one of claims 14 to 16, wherein at least the cleanliness of the support portion is 0.05 or less. The support portion has one or more convex portions projecting outward in a radial cross section, and one or more concave portions projecting inward,
At least one of the protrusions is constituted by a plurality of arcs having different radii of curvature, and among these arcs, the radius of curvature of the arc including the apex of the protrusion is the largest,
A distance (W) between the convex portion and another convex portion closest to the convex portion, a height (H) of the convex portion, a number (N) of the one or more convex portions, and a The run-flat tire support according to any one of claims 14 to 17, wherein a radius of curvature (R) of an arc including a vertex has a relationship represented by the following expression (1).
Formula (1): R (mm) ≧ 12 W / HN

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