JP2012254742A - Pneumatic tire and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which is easy in manufacturing and can reduce a hollow resonance sound, and to provide a method of manufacturing the same.SOLUTION: There are provided: the pneumatic tire which is characterized in that a plurality of kinds of short fibers 10 are firmly adhered to the internal face of the tire; and the method of manufacturing the pneumatic tire which is characterized by comprising a step of coating the internal face of the tire with an adhesive, and a step of adhering the plurality of kinds of short fibers 10 to a region coated with the adhesive. It is preferable that the plurality of kinds of short fibers 10 are formed of short fibers having a plurality of kinds of lengths, and also formed of short fibers having a plurality of kinds of materials.

Description

  The present invention relates to a pneumatic tire and a method for manufacturing the pneumatic tire, and more particularly to a low-noise tire in which countless short fibers are erected on the tire inner surface in order to reduce cavity resonance noise and a method for manufacturing the same. is there.

  It is known that a pneumatic tire has a cavity resonance phenomenon due to the length of a circular pipe inside the tire due to its structure. In any pneumatic tire, the cavity resonance frequency is composed of a plurality of frequencies in the range of 200 to 270 Hz, which contributes to unpleasant vehicle interior noise.

  As described above, the cause of vehicle interior noise is the resonance of air inside the tire. Therefore, as a conventional improvement method, a method of absorbing sound inside the tire is effective. For example, Japanese Patent Application Laid-Open No. 2004-82387 discloses As described, a method of adhering short fibers to the tire inner surface has been proposed.

JP 2004-82387 A

  However, the conventional method as disclosed in Japanese Patent Application Laid-Open No. 2004-82387 uses one type of short fiber, and here, the sound absorption characteristics of the short fiber are mainly determined by the type of short fiber to be used. For this reason, when one kind of short fiber is used, there is a problem that the frequency range in which the effect appears is narrow and a sufficient sound absorbing effect cannot always be obtained.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pneumatic tire that solves the above-described problems of the prior art, can be easily manufactured, and can reliably reduce cavity resonance noise, and a method for manufacturing the pneumatic tire. .

  As a result of intensive studies to achieve the above-mentioned object, the present inventor can reduce cavity resonance noise in a wide range of frequencies by providing a plurality of types of short fibers fixed to the inner surface of a pneumatic tire with an adhesive. As a result, the present invention has been completed.

  That is, the pneumatic tire of the present invention is characterized in that a plurality of types of short fibers are fixed to the inner surface of the tire with an adhesive.

  In a preferred example of the pneumatic tire of the present invention, the plurality of types of short fibers are composed of a plurality of types of short fibers.

  In another preferred embodiment of the pneumatic tire of the present invention, the plurality of types of short fibers are made of a plurality of types of short fibers. Here, it is preferable that the specific fibers have different specific gravities.

In the pneumatic tire of the present invention, the plurality of types of short fibers have an average length of the shortest short fibers of 0.5 to 3 mm, and an average length of the longest short fibers is an average length of the shortest short fibers. It is preferable that it is 1.5 to 3.3 times.
Here, the average length of the short fibers in the present invention is the length that becomes a peak when having a plurality of peaks when plotted on a graph with the length of the short fibers on the horizontal axis and the number of the short fibers on the vertical axis. is there.
This assumes a case where short fiber groups having a certain length are manufactured and short fiber groups having different lengths are mixed. Due to manufacturing errors, etc., the graph with the short fiber length as the horizontal axis and the number of the short fibers as the vertical axis has a distribution having a plurality of peaks. This peak becomes the peak of each short fiber group, and the longest peak and the shortest peak may be used for the comparison of the average length.
The present invention is not limited to the distribution of the graph having a plurality of peaks, and may be a random distribution. In this case, the horizontal axis is plotted in a graph with length / vertical axis as the number, the average length of all fibers is measured, and the average of each part is divided into a part below the average length and the above part. Compare lengths.

In the pneumatic tire of the present invention, it is preferable that the shortest short fiber is 30 to 60% of the total number of the plurality of types of short fibers, and the short fiber with the smallest content is 30%. It is also preferable that it is ˜50%.
In addition, the number composition ratio and content mentioned here are the shortest short fibers in each short fiber group when a short fiber group having a certain length is manufactured and short fiber groups having different lengths are mixed. What is necessary is just to compare the number composition ratio and content (weight) of a group and the short fiber group with the least content.

  In another preferred embodiment of the pneumatic tire of the present invention, the plurality of types of short fibers have an average length of 0.5 to 10 mm.

  In another preferred embodiment of the pneumatic tire of the present invention, the area of the region where the plural types of short fibers are fixed to the tire inner surface is 25% or more of the area of the tire inner surface. In another preferable example of the pneumatic tire of the present invention, 100 or more of the plurality of types of short fibers are provided per square centimeter in a region where the plurality of types of short fibers are fixed to the tire inner surface. .

  In another preferred embodiment of the pneumatic tire of the present invention, the plurality of types of short fibers have an average diameter of 1 to 500 μm.

  In the pneumatic tire of the present invention, it is preferable that the region where the plurality of types of short fibers are fixed includes a plurality of short fiber groups, and the plurality of short fiber groups are fixed independently of each other.

  In another preferred embodiment of the pneumatic tire of the present invention, an inner liner made of a modified ethylene-vinyl alcohol copolymer obtained by reacting an epoxy compound with an ethylene-vinyl alcohol copolymer is provided.

Moreover, the method for producing the pneumatic tire of the present invention includes
Applying an adhesive to the inner surface of the tire;
And a step of adhering a plurality of types of short fibers to a portion where the adhesive is applied.

  In a preferred example of the method for manufacturing a pneumatic tire according to the present invention, the plurality of types of short fibers are provided on the inner surface of the tire by electrostatic flocking.

  According to the present invention, there is provided a pneumatic tire in which a plurality of types of short fibers are fixedly provided on the inner surface of the tire with an adhesive, which is easy to manufacture and can reliably reduce cavity resonance noise. be able to. Moreover, the simple manufacturing method of this pneumatic tire can be provided.

It is sectional drawing of the right half of one embodiment of the pneumatic tire of this invention. It is a figure which shows the measurement result in the tire of Example 1, Example 2, Comparative Example 1, and Reference Example 1.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of the right half of one embodiment of the pneumatic tire of the present invention. The pneumatic tire shown in FIG. 1 has a pair of bead portions 1 and a pair of sidewall portions 2 and a tread portion 3 connected to both sidewall portions 2, and extends in a toroidal shape between the pair of bead portions 1. A carcass 4 composed of a single carcass ply for reinforcing these portions 1, 2 and 3, a belt 5 composed of two belt layers arranged on the outer side in the tire radial direction of the carcass 4, and the belt 5 The belt reinforcing layer 6 disposed on the outer side in the tire radial direction, the bead filler 8 disposed on the outer side in the tire radial direction of the ring-shaped bead core 7 embedded in the bead portion 1, and the tire of the carcass 4 And an inner liner 9 disposed on the inner surface side.

  The illustrated carcass 4 is composed of a single carcass ply, and has a main body extending in a toroidal shape between a pair of bead cores 7 and around each bead core 7 from the inside to the outside in the tire width direction. In the pneumatic tire of the present invention, the number of plies and the structure of the carcass 4 are not limited to this. Further, in the illustrated pneumatic tire, a bead filler 8 is disposed between the carcass main body portion and the carcass folded portion.

  Further, in the illustrated pneumatic tire, a belt 5 composed of two belt layers is disposed on the outer side in the tire radial direction of the crown portion of the carcass 4, and the belt layer is usually on the tire equatorial plane. The belt 5 is composed of rubberized layers of steel cords extending obliquely with respect to each other, and the two belt layers are laminated so that the steel cords constituting the belt layers cross each other across the tire equatorial plane. . The belt 5 in the figure is composed of two belt layers, but in the pneumatic tire of the present invention, the number of belt layers constituting the belt 5 may be three or more. Further, in the illustrated pneumatic tire, one belt reinforcing layer 6 is disposed on the outer side in the tire radial direction of the belt 5, but the pneumatic tire of the present invention does not include the belt reinforcing layer 6. In addition, the number of the belt reinforcing layers 6 may be two or more.

Here, in the pneumatic tire shown in FIG. 1, it is necessary that a plurality of types of short fibers 10 are fixedly provided with an adhesive on the tire inner surface, that is, the tire inner surface side of the inner liner 9. In the pneumatic tire of the present invention, since a plurality of types of short fibers are fixed to the inner surface of the tire with an adhesive, these are in relation to the air chamber inner surface formed when the tire is mounted on the rim. Short fibers will be provided. And since the short fiber fixed to the tire inner surface absorbs a cavity resonance sound, the noise resulting from the cavity resonance phenomenon can be reduced by the short fiber. Further, in the pneumatic tire of the present invention, since a plurality of types of short fibers are used, the frequency range in which the sound absorption effect is expressed is widened and the noise reduction is greater than when a single type of short fibers is used. An effect can be obtained.
Here, “plural types” means that properties such as material, shape (length, thickness, curvature, etc.), physical properties (density, rigidity, etc.) are different.

  As described above, in the pneumatic tire of the present invention, a plurality of types of short fibers are provided on the inner surface of the tire, and it is preferable that the plurality of types of short fibers consist of a plurality of types of short fibers. Since the sound absorption characteristics of short fibers vary depending on their length, the use of multiple types of short fibers provides a sound absorption effect over a wider frequency range than when single length short fibers are used. It appears and a greater noise reduction effect can be obtained.

  Note that two types of short fibers, a short fiber 10A having a shorter length and a short fiber 10B having a longer length, are fixed to the tire inner surface of the illustrated tire. There may be three or more types of fibers.

  In the pneumatic tire of the present invention, the plurality of types of short fibers have an average length of the shortest short fibers of 0.5 to 3 mm, and an average length of the longest short fibers is the shortest short fibers. The average length is preferably 1.5 to 3.3 times. When the average length of the shortest short fibers is less than 0.5 mm, the effect of reducing the cavity resonance noise becomes small. On the other hand, when the average length of the longest short fibers exceeds 10 mm, the short fibers are easily entangled with each other, the workability is deteriorated, and it is difficult to uniformly disperse the tire inner surface, and the sound absorbing effect cannot be sufficiently exhibited. There is a fear. Further, if the ratio of the average length is not 1.5 to 3 times that of the longer one (that is, the longest short fiber) than the short one (that is, the shortest short fiber), the effect of widening the frequency range in which the sound absorption effect appears is obtained. There is a possibility that a sufficient noise reduction effect cannot be obtained.

  Moreover, the pneumatic tire of this invention WHEREIN: It is preferable that the shortest short fiber is 30 to 60% of the whole number composition ratio of the said several types of short fiber. If the short fiber having the shortest number of short fibers is not within the range of 30 to 60% of the whole, the effect of widening the frequency range in which the sound absorption effect appears is small, and there is a possibility that a sufficient noise reduction effect cannot be obtained. is there.

  In the pneumatic tire of the present invention, it is also preferable that the plurality of types of short fibers are made of a plurality of types of short fibers. Since the sound absorption characteristics of short fibers vary depending on the material used, the frequency range where the effect appears can be expanded by using short fibers of different types as well as the length, and the noise level is larger than that of a single type. A reduction effect can be obtained.

  Here, short fibers such as organic synthetic fibers, inorganic fibers, regenerated fibers, natural fibers, and the like can be used as the short fibers. Examples of the organic synthetic fiber include polyolefins such as polyethylene, polypropylene and polybutylene, aliphatic polyamides such as nylon, aromatic polyamides such as Kevlar, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polyethylene succinate and polymethyl methacrylate. , Syndiotactic-1,2-polybutadiene, acrylonitrile-butadiene-styrene copolymer, polystyrene, and fibers made of these copolymers. Examples of inorganic fibers include carbon fibers and glass fibers. Examples of regenerated fibers include rayon and cupra. Examples of natural fibers include cotton, silk, wool, and the like. Among these, from the viewpoint of combining fibers having different specific gravities as much as possible and from the viewpoint of cost, versatility, etc., combining fibers having a relatively low specific gravity such as nylon and polypropylene and fibers having a relatively high specific gravity such as polyester and rayon. Is preferred.

  Moreover, the pneumatic tire of this invention WHEREIN: It is preferable that the short fiber with the least content is 30 to 50% of the whole number composition ratio of the said several types of short fiber. If the short fibers with the smallest content are not in the range of 30 to 50% of the total, the effect of widening the frequency range in which the sound absorption effect appears is small, and a sufficient noise reduction effect cannot be obtained. There is a fear.

  In the pneumatic tire of the present invention, the plurality of types of short fibers preferably have an average length of 0.5 to 10 mm. When the average length of the short fibers is less than 0.5 mm, the effect of reducing the cavity resonance sound becomes small. On the other hand, when the average length of the short fibers exceeds 10 mm, the short fibers are easily entangled with each other, the workability is deteriorated, and it is difficult to uniformly disperse the tire inner surface, and the sound absorbing effect may not be sufficiently exhibited. is there.

  In the pneumatic tire of the present invention, the area of the region where the plurality of types of short fibers are fixed to the tire inner surface is preferably 25% or more of the area of the tire inner surface. By setting the area of the region where the short fibers are fixed to the tire inner surface to 25% or more of the area of the tire inner surface, cavity resonance can be reliably reduced.

  In the pneumatic tire of the present invention, it is preferable that 100 or more of the plurality of types of short fibers are provided per square centimeter in a region where the plurality of types of short fibers are fixed to the tire inner surface. When the density of short fibers is low, the effect of reducing cavity resonance is insufficient. Therefore, in order to reliably obtain the effect of reducing cavity resonance, in the region where the short fibers are fixed, 100 short fibers per square centimeter (average) Value) or more.

  In the pneumatic tire of the present invention, the plurality of types of short fibers preferably have an average diameter of 1 to 500 μm. When the average diameter of the short fibers is less than 1 μm, yarn breakage occurs frequently in the short fiber manufacturing process, and the productivity of the short fibers decreases. On the other hand, when the average diameter of the short fibers exceeds 500 μm, the total weight of the short fibers becomes large, which may affect the rotation balance of the tire.

  In the pneumatic tire of the present invention, it is preferable that the region where the plurality of types of short fibers are fixed includes a plurality of short fiber groups, and the plurality of short fiber groups are fixed independently of each other. By providing the region where the short fibers are fixed without being continuous, even if the adhesive layer may be peeled off, the peeled-off range is extremely small and the cavity resonance suppressing effect can be maintained.

  Moreover, the manufacturing method of the pneumatic tire of the present invention includes (i) a step of applying an adhesive to the tire inner surface, and (ii) a step of bonding a plurality of types of short fibers to a portion where the adhesive is applied. It is characterized by that. In the tire manufacturing method of the present invention, first, an adhesive is applied to the short fiber bonding portion on the inner surface of the tire, and then an infinite number of plural types of short fibers are bonded to the portion where the adhesive is applied. A pneumatic tire capable of obtaining such an excellent sound absorbing effect can be efficiently manufactured. Here, the adhesive to be used is not particularly limited, and any adhesive can be used.

  In the method for manufacturing a pneumatic tire of the present invention, it is preferable to provide the plurality of types of short fibers on the tire inner surface by electrostatic flocking. An infinite number of types of short fibers can be adhered to the tire inner surface by various methods, but by using electrostatic flocking, the innumerable short fibers are easily fixed in a standing state on the tire inner surface. Therefore, it is possible to efficiently manufacture a pneumatic tire that can obtain a sound absorption effect.

  Electrostatic flocking is a processing technology that charges short fibers and implants the short fibers vertically onto an object that has been coated with an adhesive by electrostatic force. It is suitable for planting short fibers on the inner surface of a tire having a three-dimensional curvature.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  A tire (Comparative Example 1 per square centimeter) having about 15 g of nylon 15 fibers (short fiber A) having a thickness of 15 denier (φ45 μm) and a length of 2 mm on the inner surface of the tire of the same specification and electrostatic flocking on the inner surface of the tire. (The number of short fibers = about 20,000), the same short fiber A12g, a thickness of 15 denier (φ45 μm), and a 4 mm long nylon short fiber (short fiber B) 24g. Example 1, the ratio of the number of short fibers A and short fibers B is 50%, the number of short fibers per square centimeter = about 10,000, short fibers A12 g, thickness 20 denier (φ45 μm), length 4 mm A tire obtained by electrostatically flocking 32 g of rayon short fibers (short fibers C) in the same region (Example 2, the number ratio of short fibers A and short fibers C is 50% per square centimeter, respectively. A number = about 10,000) of fibers were prepared and tires without the short fibers (see Example 1), with respect to each tire were indoor drum test.

  Further, in the tires of Comparative Example 1, Example 1 and Example 2, the region where the flocked is 75% of the tire inner surface. Further, the tire is a general commercial product of size 195 / 65R15 having the structure shown in FIG. 1, the rim used is 6JJ-15, under the conditions of a load of 4.25 kN, an internal pressure of 220 kPa, and a speed of 60 km / h, The vertical tire axial force was measured with an indoor drum tester to obtain the frequency spectrum shown in FIG.

  In FIG. 2, the peaks seen around 225 Hz and 240 Hz are due to cavity resonance, but the tire of Comparative Example 1 with only short fiber A has a peak around 225 Hz reduced by about 5 dB, but the peak around 240 Hz is The reduction effect was small at about 3 dB. On the other hand, the tire of Example 1 in which the short fibers A and B are processed and the tire of Example 2 in which the short fibers A and C are processed have a large reduction effect of about 7 dB in the peak around 240 Hz. ing.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Carcass 5 Belt 6 Belt reinforcement layer 7 Bead core 8 Bead filler 9 Inner liner 10 Short fiber 10A Short short fiber 10B Short fiber longer than

Claims (15)

  A pneumatic tire comprising a plurality of types of short fibers fixed to an inner surface of the tire with an adhesive.   The pneumatic tire according to claim 1, wherein the plurality of types of short fibers are made of a plurality of types of short fibers.   The pneumatic tire according to claim 1 or 2, wherein the plurality of types of short fibers are made of a plurality of types of short fibers.   The pneumatic tire according to claim 3, wherein the short fibers of the plurality of types of materials have different specific gravities.   In the plurality of types of short fibers, the average length of the shortest short fibers is 0.5 to 3 mm, and the average length of the longest short fibers is 1.5 to 3.3 of the average length of the shortest short fibers. The pneumatic tire according to claim 2, wherein the pneumatic tire is three times larger.   6. The pneumatic tire according to claim 2, wherein the shortest short fibers are 30 to 60% of the total number of the short fibers.   The pneumatic tire according to any one of claims 1 to 6, wherein the short fiber having the smallest content of the plurality of types of short fibers is 30 to 50% of the whole.   The pneumatic tire according to any one of claims 1 to 7, wherein the plurality of types of short fibers have an average length of 0.5 to 10 mm.   The pneumatic tire according to any one of claims 1 to 8, wherein an area of the region where the plural types of short fibers are fixed to the tire inner surface is 25% or more of an area of the tire inner surface. .   The region where the plurality of types of short fibers are fixed to the inner surface of the tire is provided with 100 or more of the plurality of types of short fibers per square centimeter. The described pneumatic tire.   The pneumatic tire according to any one of claims 1 to 10, wherein the plurality of types of short fibers have an average diameter of 1 to 500 µm.   The region where the plurality of types of short fibers are fixed comprises a plurality of short fiber groups, and the plurality of short fiber groups are fixed independently of each other. The pneumatic tire according to item.   The air according to any one of claims 1 to 12, further comprising an inner liner made of a modified ethylene-vinyl alcohol copolymer obtained by reacting an epoxy compound with an ethylene-vinyl alcohol copolymer. Enter tire. Applying an adhesive to the inner surface of the tire;
And a step of adhering a plurality of types of short fibers to a portion to which the adhesive is applied.   The method for producing a pneumatic tire according to claim 14, wherein the plurality of types of short fibers are provided on the inner surface of the tire by electrostatic flocking.

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