JP2008296749A - Run flat tire, and run flat tire support and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a run flat tire having further more improved road noise reducing effects than a conventional run flat tire, and to provide a run flat tire support to be used for the same and its manufacturing method. <P>SOLUTION: In the run flat tire, the run flat tire support as a core is mounted. The run flat tire support 10 has a plurality of recessed portions 18 opening to at least the side face. On the openings of the recessed portions 18, a closed-cell polyurethane foam sheet 28 is mounted whose density d is 0.1<d≤0.5(g/cm<SP>3</SP>). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides a tire flat diameter that is necessary for maintaining a tire outer diameter when the tire is punctured, and is mounted on a rim of an automobile tire that can be safely driven, and is disposed inside a pneumatic tire so that the tire is punctured. The present invention relates to a run-flat tire support that maintains the tire outer diameter required in such a case and that can be safely run.

  Runflat tires can withstand the load and travel of the vehicle until it reaches the nearest service facility, even if the tire is punctured or if the tire pressure drops significantly or becomes zero. It is a tire with durability. As run-flat tires, a side reinforcing type in which the side portion of the tire is reinforced and a core type in which a support (core) is accommodated inside the tire are put into practical use. PAX systems and lightweight metal ring types have been put to practical use as core type supports.

  It is well known that not only run-flat tires but also general tires generate noise during travel, and in particular, road noise generated by so-called cavity resonance that vibrates the air in the tire is known to deteriorate the in-vehicle environment. . In the case of a core type run-flat tire, a support ring is arranged between the tire and the rim, so that cavity resonance is suppressed and road noise is reduced, but further road load is achieved to achieve a more comfortable interior environment. Reduction of noise is required.

As a core type run-flat tire corresponding to such a request, a tire using a support body in which a foam having an apparent density of 0.1 (g / cm ³ ) or less is fitted in a recess formed in the core is known. (For example, Patent Documents 1 and 2).

JP 2005-280454 A JP 2006-151028 A

  In the noise suppression technology for road noise disclosed in Patent Documents 1 and 2, open-cell polyurethane foam is described as a more preferable material to be fitted in the recess, and open-cell polyurethane is used in the examples. It is only a form. It is well known that open cell flexible polyurethane foam is a material used as a sound absorbing material in noise level measurement equipment such as an anechoic chamber, and it is logical to use such a sound absorbing foam as a sound absorbing material inside a tire. It is.

  However, the core-type run-flat tire equipped with a support in which the opening of the concave portion is actually sealed with an open-cell flexible polyurethane foam that is effective as a sound absorbing material as in Patent Documents 1 and 2, reduces road noise. It turned out that the effect was not enough.

  An object of the present invention is to provide a run flat tire that is more excellent in reducing road noise than the run flat tires described in Patent Documents 1 and 2, a run flat tire support used in the run flat tire, and a method for manufacturing the same. There is to do.

The run flat tire of the present invention is a run flat tire in which a run flat tire support that is a core is mounted inside the tire,
The run-flat tire support has a plurality of recesses opened at least on the side surfaces, and the density d is 0.1 <d ≦ 0.5 (g / cm ³ ) in the openings of the recesses. It is characterized in that a foam is attached.

  The run-flat tire having such a configuration is a run-flat tire that is more excellent in reducing road noise than the conventional run-flat tire.

The reason why road noise is effectively reduced as compared with open-cell flexible polyurethane foam and elastic membrane is not clear, but closed-cell polyurethane foam is a membrane (cell membrane) that forms bubbles and its Due to the presence of many gases confined in the thickness direction, the vibration damping effect due to the viscoelasticity of the polyurethane constituting the film occurs continuously in the thickness direction, and the sound energy is converted into thermal energy and kinetic energy. This is presumably due to the conversion. When the density of the open-cell polyurethane foam is less than 0.1 (g / cm ³ ), a sufficient road noise reduction effect cannot be obtained, and when it exceeds 0.5, the weight of the run-flat tire support increases and the vehicle The fuel consumption and centrifugal resistance performance during running are reduced.

Another aspect of the present invention is a run-flat tire support mounted inside a tire,
It has a plurality of recesses opened at least on the side surface, and the closed-cell polyurethane foam having a density d of 0.1 <d ≦ 0.5 (g / cm ³ ) is attached to the opening of the recess. It is characterized by.

  By using the run-flat tire support body having such a configuration, a run-flat tire that is more excellent in reducing road noise than the conventional run-flat tire can be obtained.

The method for producing a run-flat tire support according to the present invention includes a support molding step for producing a run-flat tire support having a plurality of recesses opened at least on a side surface, and curable so as to close at least the recess openings. It is characterized by having a foam forming step of forming a closed-cell polyurethane foam having a density d of 0.1 <d ≦ 0.5 (g / cm ³ ) by supplying and curing a foamed composition.

  According to the manufacturing method of the structure which concerns, the run flat tire support body which comprises the run flat tire more excellent in the reduction effect of road noise than before can be manufactured.

  As the run-flat tire support constituent material of the present invention, known materials can be used without limitation. Specifically, thermosetting resin or thermosetting such as vulcanized rubber (for example, disclosed in JP-A No. 2002-113736), thermosetting polyurethane elastomer (for example, disclosed in JP-T-2004-508997, WO01 / 42000A1, etc.). Examples thereof include a thermoplastic elastomer, a thermoplastic resin or a thermoplastic elastomer, a resin foam, and a lightweight metal.

  Among the above materials, it is preferable to use a material selected from thermosetting polyurethane resins or elastomers, polyurethane foams, and thermoplastic polyester elastomers.

  When the run-flat tire support is formed of a resin or an elastic body, it is possible to provide a reinforced portion formed of a steel cord, glass fiber, aramid fiber, etc., on the rim mounting portion that is the inner peripheral surface thereof. This is a preferred embodiment.

  The polyurethane foam to be attached to the recess formed on the run-flat tire support is a closed-cell polyurethane foam. Such a closed cell polyurethane foam can be produced, for example, by the following method.

  (1) A foaming composition containing a polyol compound, a foam stabilizer, a catalyst, and a polyol composition not containing a foaming agent, which is mechanically stirred in the presence of an inert substrate such as air or nitrogen gas, and containing fine bubbles of the inert substrate. A method in which a foamed composition is mixed with a polyisocyanate compound at a predetermined ratio to obtain a curable foamed composition, which is cured.

  (2) A polyol compound and a polyisocyanate compound are reacted in advance at an isocyanate group-excess stoichiometric ratio to obtain a prepolymer having an NCO group, and this prepolymer is mechanically stirred in the presence of an inert substrate such as air or nitrogen gas. Then, a prepolymer containing fine bubbles of the inert substrate is mixed with a polyalcohol, aromatic diamine or a mixture thereof as a curing agent in a predetermined ratio to the prepolymer to obtain a curable foam composition, How to cure.

  (3) The curable foaming composition containing fine bubbles by supplying the polyol composition of (1), the polyisocyanate compound, and an inert substrate such as air or nitrogen gas to the mixing head and mixing and stirring in the mixing head. Discharge and cure as a product (mechanical floss method).

  (4) The prepolymer of (2), the curing agent, and an inert substrate such as air or nitrogen gas are respectively supplied to the mixing head, mixed and stirred in the mixing head, and discharged as a curable foam composition containing fine bubbles. , Curing method (mechanical floss method).

  (5) A polyol composition containing a polyol compound, a foam stabilizer, and a catalyst, and a polyol composition not containing a foaming agent and a hollow resin balloon are agitated to form a foamed composition containing a hollow balloon, and a polyisocyanate compound at a predetermined ratio in the foamed composition. Is a method in which a curable foam composition is mixed and cured.

  (6) A polyol compound and a polyisocyanate compound are reacted in advance at an isocyanate group-excess stoichiometric ratio to obtain a prepolymer having an NCO group, and a hollow resin balloon is added to the prepolymer and stirred to form a foam containing a hollow balloon. A method of preparing a prepolymer, mixing a foamed prepolymer with a predetermined ratio of a polyhydric alcohol, an aromatic diamine or a mixture thereof to obtain a curable foamed composition, and curing the composition.

The density of the closed-cell polyurethane foam formed in the above method is performed by adjusting the amount of a substrate such as air dispersed as bubbles. The density d of the closed-cell polyurethane foam is 0.1 <d ≦ 0.5 (g / cm ³ ), more preferably 0.11 (g / cm ³ ) or more, and 0.12 (g / cm ³ ). More preferably, it is cm ³ ) or more.

Further, the hardness of the closed-cell polyurethane foam is not particularly limited as long as it has a sound-damping effect, but it is 1000 N / 314 cm ² or more in terms of hardness (40% ILD) according to A method defined in JIS K 6400-2, It is preferable that it is 5000 N / 314 cm ² or less.

  In the production method of the present invention, a run flat tire support having a plurality of recesses on at least the side surface is produced in the support molding step, and the above-mentioned (1) to (1) are formed in the recesses of the run flat tire support obtained in the foam formation step. The curable foam composition described in 6) is supplied so as to close the opening, and is cured to produce a run-flat tire support in which closed-cell polyurethane foam is attached to the opening of the recess. .

  According to the above production method, since the curable foam composition is supplied to the concave portion of the support and is cured as it is, the adhesion between the closed cell polyurethane foam and the inner wall surface of the concave portion of the support is good, and the run-flat tire There is an effect that there is no problem of falling off when the vehicle is mounted and normally traveled. Further, it is easier to manufacture the support than to fit the polyurethane foam blocks one by one in the recess.

  FIG. 1 is a perspective view illustrating a run-flat tire support of the present invention, and FIG. 2 is a part of a cross-sectional view taken along the line XX of FIG. The run-flat tire support 10 has a ring shape with a square cross section, and an outer peripheral portion 14 that contacts the inner surface of the tire during run-flat travel, an inner peripheral portion 12 that has an inner peripheral surface 13 that contacts the rim, and an outer peripheral portion 14 and an inner periphery. The width direction rib part 16 and the circumferential direction rib part 20 which connect the part 12 are comprised. Providing a reinforcing cord layer in the circumferential direction in the vicinity of the inner peripheral surface 13 of the inner peripheral portion 12 is a preferred mode. The width direction rib part 16 and the circumferential direction rib part 20 form the recessed part 18 provided in the side part of a run flat tire support body, and the block 28 of the closed cell polyurethane foam is mounted in the opening part of the recessed part 18. . On the inner peripheral surface 13 of the inner peripheral portion 12, a ridge 22 is formed for fitting with a groove formed in the rim when the rim is attached to prevent movement in the axial direction.

  The shape and the number of the recesses 18 are not particularly limited as long as the support 10 satisfies a request such as a predetermined mechanical strength. FIG. 1 shows an example of a stepped convex shape in which the side view shape is fan-shaped, the cross-sectional shape in the width direction is rectangular, and the planar shape is provided with steps 24 and 26. The shape of the recess 18 may be a fan shape in a side view, a rectangular shape in the width direction, a rectangular shape in a plan view, or a cylindrical shape. In the convex type having steps as shown in FIG. 1, the number of steps may be 1 or 3 or more.

  The thickness of the closed-cell polyurethane foam block 28 attached to the opening of the recess 18 is preferably more than 3 mm. The closed-cell polyurethane foam may be completely filled in the recesses 18, but is preferably filled in the vicinity of the opening from the viewpoint of reducing the weight of the support 10. In this case, it is preferable to provide a through hole 30 that allows the space behind the recess 18 closed by the closed cell polyurethane foam to communicate with the tire internal space.

  As a method of mounting the closed-cell polyurethane foam 28 in the recess 18, a method of manufacturing a polyurethane foam, cutting it into a predetermined shape and pushing it into the opening, a method of bonding and fixing to the peripheral wall surface of the opening using an adhesive, etc. Can be installed. As illustrated in FIG. 1, if the recess 18 has a planar shape with a step, and the thickness of the foam is the distance to the step on the opening side, alignment when the foam is mounted can be performed easily. The effect is obtained.

  As another method for attaching the closed-cell polyurethane foam, there is a method in which the curable foamed composition is supplied to the recess and cured as described above. In such a method, in order to mount the entire recess 18 in the vicinity of the opening without filling the foam, for example, in the recess 18 having the shape shown in FIG. Then, a method of supplying and curing the curable foam composition can be exemplified.

(Polyurethane foam block production example 1)
As a polyol compound, 275 parts by weight of Actol POP-45 (Mitsui Chemicals Polyurethane), 75 parts by weight of Plaxel 305 (Daicel Chemical Industries), and 150 parts by weight of Plaxel 205N (Daicel Chemical Industries) are mixed, and foam control is performed in the polyol mixture. Agent B8443 (Gold Schmidt) 50 parts by weight; 25 (Kao) 0.5 part by weight was added and mixed, and the liquid temperature was adjusted to 40 ° C. Subsequently, the mixed liquid was stirred using a biaxial mixer, and air was entrained to form fine bubbles to obtain a foamed composition. Stirring was performed until the polyol composition entrained air as fine bubbles to form a foam composition having a predetermined density.

179.35 parts by weight of Millionate MTL (Nippon Polyurethane Industry) as a polyisocyanate compound was added to the obtained foamed composition, and further stirred for 1 minute to obtain a curable foamed composition, which was poured into a mold and heated in an oven at 100 ° C. It was cured by heating for 16 hours to obtain a polyurethane foam. The obtained polyurethane foam was cut to produce a polyurethane foam block A of 30 mm × 25 mm × 15 mm (thickness). The density of the polyurethane foam block A was 0.15 g / cm ³ .

(Polyurethane foam block production example 2)
Polyurethane foam block B was produced in the same manner as in (Foam Production Example 1) except that the density of the polyurethane foam block obtained by changing the stirring time of the polyol mixture was changed to 0.3 g / cm ³ .

(Polyurethane foam block production example 3)
A commercially available sound-absorbing open-cell flexible polyurethane foam LBZ (density 0.025 g / cm ³ : Toyo Rubber Industries) was cut to produce a polyurethane foam block C of 30 mm × 25 mm × 2 mm (thickness).

(Polyurethane foam block production example 4)
A commercially available sound-absorbing open-cell flexible polyurethane foam LBU (density 0.035 g / cm ³ : Toyo Tire & Rubber) was cut to produce a polyurethane foam block D of 30 mm × 25 mm × 2 mm (thickness).

Example 1
1 and 2, a polyurethane foam block A is attached to all the recesses formed on the sides of a run-flat tire support (weight 2.43 kg) made of thermosetting polyurethane having the shape shown in FIGS. A run-flat tire was assembled using tires (215-660R46095V) and rims (205 × 460A). The run-flat tire was subjected to a bump ride test to evaluate road noise performance.

Evaluation of road noise performance was performed by running a drum at a tire pressure of 230 kPa, a load of 5776 N, a running speed of 60 km / h, and a cleat of 12.5 w ₁ × 5 h × 25 w ₂ , measuring axial force and performing frequency analysis to perform cavity resonance. The peak (Fz second peak) level was measured. Road noise performance is indicated by an index with a cavity resonance peak level of 23.4 dB of a run-flat tire using a run-flat tire support before the polyurethane foam block A is mounted as 100. The results are shown in Table 1 together with a weight index with the weight of the run-flat tire support without the polyurethane foam of Comparative Example 3 taken as 100.

(Example 2)
A run-flat tire was obtained in the same manner as in Example 1 except that the polyurethane foam block B was used as a polyurethane foam block to be attached to the recess of the run-flat tire support, and the same evaluation as in Example 1 was performed.

(Comparative Example 1)
A run-flat tire was produced in the same manner as in Example 1 except that the polyurethane foam block C was used as the polyurethane foam block to be mounted in the recess of the run-flat tire support, and the same evaluation as in Example 1 was performed.

(Comparative Example 2)
A run-flat tire was obtained in the same manner as in Example 1 except that the polyurethane foam block D was used as a polyurethane foam block to be mounted in the recess of the run-flat tire support, and the same evaluation as in Example 1 was performed.

(Comparative Example 3)
A run-flat tire support without a polyurethane foam was used to make a run-flat tire in the same manner as in Example 1, and the same evaluation as in Example 1 was performed.

  As shown in Table 1, the run-flat tire equipped with the run-flat tire support of the present invention had a road noise reduction effect superior to the support using the sound-absorbing open-cell flexible polyurethane foam. .

A perspective view illustrating a run-flat tire support XX sectional view of FIG.

Explanation of symbols

10 Run-flat tire support 18 Recess 28 Closed cell polyurethane foam

Claims (3)

A run-flat tire having a run-flat tire support that is a core inside the tire,
The run-flat tire support has a plurality of recesses opened at least on the side surfaces, and the density d is 0.1 <d ≦ 0.5 (g / cm ³ ) in the openings of the recesses. A run-flat tire characterized by foam. A run flat tire support to be mounted inside the tire,
It has a plurality of recesses opened at least on the side surface, and the closed-cell polyurethane foam having a density d of 0.1 <d ≦ 0.5 (g / cm ³ ) is attached to the opening of the recess. A run-flat tire support characterized by. A support molding process for producing a run-flat tire support having a plurality of recesses open at least on the side surfaces, and a curable foam composition is supplied and cured so as to close at least the openings of the recesses; A method for producing a run-flat tire support, comprising the step of forming a closed-cell polyurethane foam having a ratio of 0.1 <d ≦ 0.5 (g / cm ³ ).

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