JP5376657B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire (hereinafter also simply referred to as “tire”), and more particularly to a pneumatic radial tire suitable for a small passenger car.

  In a tire assembled on a rim and attached to a vehicle, the tread portion oscillates against the road surface unevenness while the vehicle is running, so that the gas filled in the tire cavity resonates. This cavity resonance is the main cause of so-called road noise, and many of the resonance frequencies exist in the range of 180 to 300 Hz. When the road noise is transmitted to the vehicle interior, unlike a noise in other frequency bands, it takes a sharp and high peak value, which is annoying noise for passengers in the vehicle interior.

  As a technique for suppressing such cavity resonance and reducing road noise, for example, Patent Document 1 discloses an organic fiber having characteristic physical properties in a tire lumen formed by a rim and a tire attached to the rim. There is disclosed a tire assembly in which a vibration damping sheet made of a non-woven fabric is used. Further, in Patent Document 2, by applying an adhesive to the tire inner surface and adhering countless short fibers, the cavity resonance sound generated in the tire air chamber is absorbed by the short fibers to reduce vehicle interior noise. Technology is disclosed.

Japanese Patent No. 3384633 (Japanese Patent Laid-Open No. 08-132816, claims, etc.) JP 2004-082387 A (Claims etc.)

  As described above, various techniques for applying a sound absorbing material to the tire inner surface in order to reduce road noise have been proposed. Conventionally, such a sound absorbing material is generally post-applied to a vulcanized product tire. The manufacturing efficiency was poor. In addition, for example, Patent Document 2 discloses that a nonwoven fabric or the like is attached to an inner liner before vulcanization. However, when a nonwoven fabric made of one ordinary material is applied before vulcanization, Since the thickness is not restored while being crushed by the bladder during vulcanization, it is considered that the desired sound absorbing effect is not exhibited in the product tire.

  Accordingly, an object of the present invention is to provide a pneumatic tire that has an effect of reducing road noise and is excellent in manufacturing efficiency.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by using a laminate composed of two types of non-woven fabrics having different thermal shrinkage rates as a sound absorbing member to be attached to the tire inner surface, thereby completing the present invention. It came to.

That is, the pneumatic tire of the present invention is a pneumatic tire in which a sound absorbing member is attached to the inner surface.
The sound absorbing member comprises a laminate of two different nonwoven fabrics, and among the nonwoven fabrics constituting the laminate, the nonwoven fabric on the inner side in the tire radial direction has a higher heat shrinkage rate at 150 ° C. than the nonwoven fabric on the outer side in the tire radial direction. And, at the time of molding the tire, the laminate of the two different nonwoven fabrics is applied to the inner surface of the tire, and then the laminate is manufactured by vulcanization in a state of being applied. .

  In the present invention, it is preferable that the difference in thermal shrinkage at 150 ° C. between the nonwoven fabric inside in the tire radial direction and the nonwoven fabric outside in the tire radial direction is 5% or more. In addition, the sound absorbing member preferably has a thickness of 30% or more, particularly 40 to 80% of the thickness before the laminate is attached.

  Furthermore, in the present invention, it is preferable that the sound absorbing member has a thickness of 5 mm or more in an area of 90% or more of the entire pasting region, and the sound absorbing member covers at least 80% or more in the tire circumferential direction. It is also preferable that it is affixed. Furthermore, the sound absorbing member preferably has a width of 100 mm or more.

  According to the present invention, it is possible to realize a pneumatic tire that has a road noise reduction effect and is excellent in manufacturing efficiency by adopting the above configuration.

1 is a cross-sectional view in the width direction showing a pneumatic tire according to an embodiment of the present invention. It is explanatory drawing which concerns on the manufacturing process of the pneumatic tire of this invention.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
In FIG. 1, the cross-sectional view of the width direction of an example of the pneumatic tire of this invention is shown. The illustrated pneumatic tire includes a tread portion 1 that contacts the road surface, a pair of sidewall portions 2 and a pair of bead portions 3 that extend inward in the tire radial direction from both ends thereof, and is embedded in each bead portion 3. A carcass 5 that extends in a toroidal shape between the bead cores 4 to form a tire skeleton, and a belt 6 that is disposed outside the crown portion in the tire radial direction and reinforces the tread portion 1. Further, an air impermeable inner liner (not shown) is disposed on the innermost layer of the tire, that is, the tire inner surface facing the tire lumen 7.

  As shown in the drawing, in the tire of the present invention, a sound absorbing member 10 made of a nonwoven fabric is stuck to the inner surface. In this way, by arranging the sound absorbing member 10 made of nonwoven fabric on the inner surface, the vibration energy of the filling gas accompanying the cavity resonance generated in the tire lumen 7 is converted into the internal vibration energy inside the sound absorbing member 10. , And can be consumed as thermal energy, whereby the effect of reducing cavity resonance can be obtained. The term “filling gas” as used herein refers to what is generally filled into a tire, such as normal or air having a changed oxygen partial pressure, and an inert gas such as nitrogen gas.

  In the present invention, the sound absorbing member 10 is composed of a laminate of two different nonwoven fabrics 11 and 12, and among the nonwoven fabrics constituting these laminates, the nonwoven fabric 11 inside the tire radial direction is the nonwoven fabric outside the tire radial direction. It is important to use a material having a higher thermal shrinkage at 150 ° C. than 12. By using a laminate composed of two types of nonwoven fabrics 11 and 12 having different heat shrinkage rates as the sound absorbing member 10, the heat shrinkage rate is obtained when the sound absorbing member 10 is attached to an unvulcanized raw tire and then vulcanized. Due to the difference, the thickness of the laminate once crushed by the bladder during vulcanization is restored immediately after vulcanization. That is, in the present invention, after laminating a laminate of two different nonwoven fabrics 11 and 12 as shown in FIG. 2 (a) on the tire inner surface at the time of tire molding, vulcanization is performed in this state. As shown in (b), the laminated body was crushed by the bladder 20 during vulcanization, and once the thickness was almost lost, but after the pressure by the bladder 20 disappeared in the tire cooling process immediately after vulcanization, In one to two minutes, the nonwoven fabric 11 on the inner side in the tire radial direction having a high heat shrinkage ratio contracted as shown in FIG. As a whole, the sound absorbing member 10 made of a body can be restored in thickness in both the tire circumferential direction and the width direction.

  The difference in thermal shrinkage at 150 ° C. between the nonwoven fabric 11 on the inner side in the tire radial direction and the nonwoven fabric 12 on the outer side in the tire radial direction is preferably set to be 5% or more, particularly 5 to 15%. By setting the difference in thermal shrinkage to 5% or more based on the thickness of any nonwoven fabric, the effect of restoring the thickness of the sound absorbing member 10 due to the shrinkage of the nonwoven fabric 11 after vulcanization can be obtained more favorably. it can. Further, from the same viewpoint, for the nonwoven fabric 12 on the outer side in the tire radial direction, the absolute value of the heat shrinkage rate is preferably as small as possible.

  Here, in the present invention, preferably, the sound absorbing member 10 is 30% of the thickness of the product tire before application of the laminate in the product tire by appropriately selecting the combination of the thermal shrinkage rates of the nonwoven fabric 11 and the nonwoven fabric 12. In particular, the thickness is 40 to 80%. After the vulcanization, the sound absorbing member 10 is restored to a thickness of 30% or more of the thickness before the laminate is pasted, so that the sound absorbing material having a desired thickness can be efficiently obtained while suppressing the thickness of the nonwoven fabric to be used. The member 10 can be obtained.

  The nonwoven fabrics 11 and 12 constituting the sound absorbing member 10 are not particularly limited as long as they satisfy the above-described conditions relating to the heat shrinkage rate. Examples of the nonwoven fabrics that are conventionally used include polyethylene terephthalate. Organic fibers such as (PET), rayon, nylon, aromatic polyamide (aramid), inorganic fibers such as glass or carbon, animal-derived or plant-derived fibers and the like can be used in an integrated manner. Moreover, the length of the fiber which comprises a nonwoven fabric can be set arbitrarily.

  The tire of this invention should just be what the sound-absorbing member 10 consisting of the said nonwoven fabrics 11 and 12 is affixed on the inner surface, About the arrangement | positioning conditions of a sound-absorbing member, and the details of tire structures other than a sound-absorbing member, follow a conventional method. What is necessary is just to select suitably, and it does not restrict | limit especially. For example, the sound absorbing member 10 is disposed on the inner surface of the tread portion 1 in the illustrated example, but is not limited thereto, and may be disposed on the inner surface of the sidewall portion 2 or the bead portion 3.

  Moreover, as the arrangement area of the sound absorbing member 10, the larger the area, the larger the sound absorbing effect can be obtained. Preferably, the entire affixing area covers at least 80% or more, particularly 95-100% of the tire circumferential direction. It is arranged to have a thickness of 5 mm or more, particularly 8 to 15 mm in an area of 90% or more. Moreover, although a suitable arrangement | positioning width | variety is based also on a tire size, it is 100 mm or more. If the arrangement region is too narrow, a sufficient sound absorption effect cannot be obtained, and the road noise reduction effect is small. The same applies if the thickness is too thin.

  As described above, in the tire of the present invention, a laminate of two different nonwoven fabrics 11 and 12 is attached to the inner surface of the raw tire at the time of molding the tire, and then the raw tire is vulcanized with the laminate attached. By doing so, it can be manufactured. Therefore, the process of attaching the sound absorbing member to the inner surface of the product tire after vulcanization is unnecessary, and the manufacturing efficiency is excellent.

  In addition, there is no restriction | limiting in particular as a method of sticking the laminated body of the nonwoven fabrics 11 and 12 on the surface of a raw tire, However, Since the surface of the inner liner before vulcanization is sticky, a laminated body is used for an inner liner as it is. When the raw tire is attached and vulcanized as usual, when the laminate expands and the laminate is pressed against the inner liner, some of the fibers of the nonwoven fabric are embedded in the inner liner, With curing, the laminate is fixed to the inner liner. In addition, as an adhesive, a styrene-butadiene rubber latex adhesive, an aqueous polymer-isocyanate adhesive, or an acrylic or synthetic resin adhesive tape can be used for chemical bonding, After temporarily fixing the laminate with these adhesive tapes or adhesives, the laminate may be impregnated on the inner surface of the inner liner by heating and pressurizing during vulcanization and physically fixed.

  In addition, a hot melt adhesive can be suitably used for laminating the nonwoven fabrics 11 and 12, and specifically, for example, a polymer hot melt adhesive such as polyester, nylon, polypropylene, and olefin. Can be used to join the nonwoven fabrics together. In particular, it is preferable to use a hot-melt adhesive having a melting point of 70 to 180 ° C. in a powder form, a net form, a fiber form, or the like so as not to inhibit the airflow resistance between the nonwoven fabrics.

Hereinafter, the present invention will be described more specifically with reference to examples.
A pneumatic tire having the sound absorbing member 10 attached to the inner surface as shown in FIG. 1 was produced according to the conditions shown in the following table. Specifically, except for the conventional example, the nonwoven fabric alone or the laminate shown in the following table at the time of tire molding is pasted on the inner surface of the raw tire using a styrene-butadiene rubber latex adhesive as an adhesive, and thereafter This was produced by vulcanization at a temperature of about 160 ° C. In addition, a nylon hot melt adhesive was used for joining the nonwoven fabric laminates. The pasting area of the nonwoven fabric alone or the laminate was 95 mm in the tire circumferential direction at a width of 100 mm. For each of the obtained test tires, the effect of suppressing cavity resonance was evaluated in accordance with the following. The results are also shown in the table below.

<Evaluation of cavity resonance suppression effect>
Each test tire was mounted on a rim and mounted on a vehicle, and the indoor noise when traveling on an asphalt road surface under conditions of a speed of 60 km / h under appropriate internal pressure and load was measured. This measurement result was subjected to frequency analysis, and the suppression effect of the cavity resonance was evaluated based on the peak sound pressure level seen near 230 kHz. The evaluation result is expressed as an exponential ratio when the cavity resonance suppression effect of the comparative example is set to 100 with respect to the sound pressure level of the conventional example having no sound absorbing member. It is.

＊１）熱収縮率は、ＪＩＳ Ｌ １９０６に準拠して測定した。

* 1) The heat shrinkage rate was measured according to JIS L 1906.

  From the results in the above table, it is possible to obtain a sound-absorbing member having a desired thickness even after vulcanization by using a laminate composed of two different nonwoven fabrics that satisfy the conditions of the present invention. It is clear that a tire that exhibits a cavity resonance suppression effect and as a result has an excellent road noise reduction effect can be obtained. In addition, the test tires of each example can be manufactured by attaching a sound absorbing member before vulcanization, and the attaching operation of the sound absorbing member after vulcanization is not required, so that the production efficiency is excellent.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass 6 Belt 7 Tire inner cavity part 10 Sound absorption member 11,12 Nonwoven fabric 20 Bladder

Claims (7)

In the pneumatic tire in which the sound absorbing member is affixed to the inner surface,
The sound absorbing member Ri is Do a laminate of two different nonwoven fabric, of nonwoven fabric constituting the laminated body, the radially inner nonwoven fabric, than the nonwoven fabric of the radially outer tire, the heat shrinkage at 0.99 ° C. high rather, and air, characterized in that during tire molding, after adhered a laminate of the two different nonwoven inner surface of the tire, formed by produced by vulcanizing in a state where the laminate is pasted Enter tire. The tire and the radially inner nonwoven, the tire radius of the outwardly nonwoven pneumatic tire according to claim 1, wherein the difference in heat shrinkage ratio is 5% or more at 0.99 ° C.. The pneumatic tire according to claim 1 or 2 , wherein the sound absorbing member has a thickness of 30% or more of a thickness of the laminated body before pasting. The pneumatic tire according to claim 3, wherein the sound absorbing member has a thickness of 40 to 80% of a thickness of the laminated body before being attached.   The pneumatic tire according to any one of claims 1 to 4, wherein the sound-absorbing member has a thickness of 5 mm or more in an area of 90% or more of the entire pasting region.   The pneumatic tire according to any one of claims 1 to 5, wherein the sound absorbing member is affixed over an area of at least 80% in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 6, wherein the sound absorbing member has a width of 100 mm or more.

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