JP2012255066A - Rubber composition for tire inner liner and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire inner liner, which provides excellent air permeation-preventing function and fatigue endurance and emits an aromatic odor for a long period of time; and to provide a pneumatic tire using the same.SOLUTION: This invention relates to: the rubber composition for the tire inner liner, containing a combination of 0.5 to 15 pts.mass of a microcapsule that contains a perfume material, based on 100 pts.mass of a rubber component containing 50 pts.mass or more of butyl rubber; and the pneumatic tire in which the rubber composition is used as the inner liner.

Description

  TECHNICAL FIELD The present invention relates to a rubber composition for a tire inner liner and a pneumatic tire using the same, and more specifically, a tire that imparts excellent air permeation prevention performance and fatigue resistance and emits fragrance over a long period of time. The present invention relates to a rubber composition for an inner liner and a pneumatic tire using the same.

  An inner liner mainly composed of butyl rubber having excellent air permeation prevention performance is provided on the inner surface of the tubeless pneumatic tire. However, the inner liner cannot completely block the filling air in the tire lumen, and for a long period of time, the filling air permeates the inner liner and diffuses into the carcass layer and the belt layer disposed on the outer peripheral side. Further, there is a problem that oxygen in the filled air oxidizes and deteriorates the rubber component of the carcass layer and the belt layer, thereby reducing durability. Further, when the tire air pressure decreases, the tire deflection increases, leading to failure. As a countermeasure against this, a technique for blending a rubber composition for a tire inner liner with a plate-like inorganic filler such as talc or clay having a flat plate-like structure is known. It was difficult to disperse in the air, and it was difficult to obtain desired air permeation prevention performance and fatigue resistance.

  On the other hand, a pneumatic tire is composed mainly of a vulcanized rubber composition. This vulcanized rubber has a unique odor, and when storing tires in closed store warehouses or garages, many users complain of discomfort due to this odor, and improvement has been desired.

Patent Document 1 below discloses a pneumatic tire in which an aromatic fragrance is held on the outer surface region of the tire. However, by applying or blending a fragrance, the tire can emit a fragrance and extinguish the odor to form a comfortable atmosphere, but its effect is limited to a short period (initial) after tire manufacture, There is a problem that the fragrance decreases as the tire is used for a long period of time.
Moreover, the following patent document 2 discloses a technique for blending perfume-containing particles into a tire tread. However, even in this technique, there is a problem that the fragrance divergence is concentrated in a short period (initial stage) after the manufacture of the tire and the effect does not last long.

Japanese Patent Laid-Open No. 7-69003 JP 2002-114873 A

  Accordingly, an object of the present invention is to provide a rubber composition for a tire inner liner that imparts excellent air permeation preventing performance and fatigue resistance and emits aroma over a long period of time, and a pneumatic tire using the same.

As a result of intensive studies, the present inventors have found that the above problem can be solved by blending a specific amount of microcapsules containing a fragrance into a rubber component having a specific composition, and the present invention can be completed. did it.
That is, the present invention is as follows.
1. A rubber composition for a tire inner liner, comprising 0.5 to 15 parts by mass of a microcapsule containing a fragrance per 100 parts by mass of a rubber component containing 50 parts by mass or more of butyl rubber.
2. A pneumatic tire using the rubber composition for a tire inner liner described in 1 above as an inner liner.

  According to the present invention, since a specific amount of a microcapsule containing a fragrance is blended with a rubber component having a specific composition, the tire imparts excellent air permeation prevention performance and fatigue resistance and emits a fragrance over a long period of time. A rubber composition for an inner liner and a pneumatic tire using the same can be provided.

Hereinafter, the present invention will be described in more detail.
(Rubber component)
The rubber component used in the present invention contains 50 parts by mass or more of butyl rubber when the whole is 100 parts by mass.
Examples of the butyl rubber include any butyl rubber used for the inner liner, such as butyl rubber (IIR) and halogenated butyl rubber (Br-IIR, Cl-IIR). As a commercial item of butyl rubber, for example, Nippon Butyl Co., Ltd., which is brominated butyl rubber, trade name BROMOBUTYL2255 and the like can be mentioned.
As the rubber component other than the butyl rubber, any of the diene rubbers used as the rubber composition for tires can be used, but natural rubber (NR) is preferable. When the blending ratio of the diene rubber exceeds 50 parts by mass, the air permeation prevention performance is deteriorated.

(Microcapsules containing fragrance)
The microcapsule containing a fragrance used in the present invention is a spherical substance obtained by wrapping a core fragrance with a wall material, and the contained fragrance is diffused in the wall material or outside the wall material and is physically applied to the microcapsule. When force is applied, the capsule wall breaks and releases the fragrance of the core material. By blending this microcapsule with the rubber composition for the tire inner liner, unlike the techniques described in Patent Documents 1 and 2, the fragrance does not diverge in a large amount at the initial stage after the tire production. The divergence lasts uniformly throughout the tire's long-term use.

  The manufacturing method of the microcapsule containing a fragrance is not particularly limited, and a known microencapsulation method can be employed. Specifically, chemical production methods (interfacial polymerization method, in situ polymerization method, orifice method), physicochemical methods (coacervation method), mechanical / physical methods (air suspension coating method, spray drying method, High-speed air-flow impact method). Examples of the microcapsule wall material include various polymer compounds such as crosslinked or uncrosslinked acrylic resin, polyurea, polyurethane, polyamide, melamine resin, urea resin, alginate, gelatin, gum arabic, and starch.

In the microcapsule containing the fragrance used in the present invention, the particle size is preferably 5 to 60 μm, more preferably 10 to 50 μm, and particularly preferably 15 to 40 μm. In this particle size range, the air permeation prevention performance and fatigue resistance of the rubber composition for the inner liner and the effect of sustaining the fragrance emission over a long period of time can be further improved.
Moreover, the thickness of the wall material of the microcapsule is preferably, for example, 1 to 20 μm, and more preferably 3 to 15 μm. In the range of the thickness of the wall material, the air permeation preventing performance and fatigue resistance of the rubber composition for the inner liner, and the effect of sustaining the fragrance emission over a long period of time can be further improved.

  The fragrance used in the present invention is not particularly limited in its kind and amount of use as long as the fragrance can be diffused and the odor of the tire can be relieved, but the evaporation loss during processing such as kneading with rubber or vulcanization is not limited. Those having a boiling point of 190 ° C. or higher are particularly preferable so as not to be scattered or decomposed and altered.

  Specifically, at least one selected from the group consisting of heliotrope, jasmine, rose, orange flower, amber, musk, and lemon can be used.

  As a more specific fragrance, a tab (TABU) type in which rose, amber, musk and jasmine fragrance components are added together with a solvent dioctyl phthalate (DOP) to an oriental base mainly composed of the following patchouli oil. There is a fragrance.

Oriental base: patchouli oil, hercoline (methylabietate), vanillin, ethyl vanillin Coumarin rose fragrance ingredients: phenylethyl alcohol, geraniol, iso-bornyl methoxycyclohexanol (iso-Bornyl methoxycyclohexanol)
Amber-based fragrance ingredient: Tetrahydroparamethylquinoline Musk-type fragrance ingredient: Garak solid, musk ketone Jasmine-type fragrance ingredient: α-amylcinnamaldehyde, methyl dihydrojasmonate Lemon-type fragrance: For example, lemon peel and juice A component extracted by a steam distillation method, a hot water distillation method, an organic solvent extraction method, a pressing method, a non-volatile solvent extraction method, a supercritical fluid extraction method, or a synthetic product of the component.

In addition, the following heliotrope fragrance component is the main fragrance, jasmine fragrance component, and in addition to the harmonic and diffusive, amethyst with rose fragrance component and orange flower fragrance component added with solvent DOP ( AMETHYST) type fragrances, which are sweet and heavy, and are particularly suitable for suppressing rubber odor.
Heliotrope fragrance ingredients: heliotropin, musk ketone, coumarin, ethyl vanillin, acetyl cedrene, hercoline (methyl abieticate), eugenol, methyl ionone Rose fragrance ingredients: Damascon-β, Damascon-α, iso-bornylmethoxycyclohexanol Orange Flower-based fragrance ingredients: methyl anthranilate, γ-undecalactone, γ-nonalactone Jasmine-based fragrance ingredients: methyl dihydrojasmonate

(Blend ratio of rubber composition for tire inner liner)
The rubber composition for a tire inner liner of the present invention comprises 0.5 to 15 parts by mass of a microcapsule containing a fragrance per 100 parts by mass of a rubber component containing 50 parts by mass or more of a butyl rubber. And
If the blending amount of the microcapsules containing the fragrance is less than 0.5 parts by mass, the amount added is too small to achieve the effects of the present invention. Conversely, if it exceeds 15 parts by mass, the fatigue resistance will deteriorate.

  The more preferable amount of the microcapsule containing the fragrance is 1 to 12 parts by mass with respect to 100 parts by mass of the rubber component.

  The rubber composition for a tire inner liner of the present invention includes a rubber composition such as a vulcanization or crosslinking agent, a vulcanization or crosslinking accelerator, a filler, various oils, an anti-aging agent, and a plasticizer in addition to the above-described components. Various additives that are generally blended in can be blended, and such additives can be kneaded by a general method to form a composition, which can be used for vulcanization or crosslinking. The blending amounts of these additives can be set to conventional general blending amounts as long as the object of the present invention is not violated. In order to further improve the air permeation prevention performance, scale-like and flat fillers may be used in combination, but in this case, fatigue resistance generally tends to decrease.

The rubber composition for a tire inner liner of the present invention can be used for producing a pneumatic tire according to a conventional method for producing a pneumatic tire.
The thickness of the inner liner is preferably 200 to 5000 μm, and more preferably 400 to 3000 μm, from the viewpoint of the effect of the present invention.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Examples 1-3 and Comparative Examples 1-6
Preparation of Sample In the formulation (parts by mass) shown in Table 1, the formulation components excluding sulfur and the vulcanization accelerator were weighed, kneaded with a 1.7 L Banbury mixer for 4 minutes, and mastered when reaching 155 ± 5 ° C. The batch was discharged and cooled at room temperature. This master batch was subjected to a 1.7 L Banbury mixer, and sulfur, a vulcanization accelerator, and a vulcanization retarder were added and mixed to prepare a rubber composition.
Next, the obtained rubber composition was press vulcanized at 160 ° C. for 20 minutes in a predetermined mold to prepare a vulcanized rubber test piece. The physical properties of the obtained vulcanized rubber specimens were measured by the following test methods.

・ Air permeability coefficient Using the vulcanized test piece of the obtained rubber composition, the test gas is equivalent to air in accordance with method A (differential pressure type) of JIS K7126 “Plastic film and sheet gas permeability test method”. (Nitrogen: oxygen = 8: 2), and the air permeability coefficient was measured at a test temperature of 30 ° C. The obtained results are shown in Table 1 as an index with Comparative Example 1 as 100. A smaller index means a smaller air permeability coefficient and better air permeation prevention performance.
-Fatigue resistance In accordance with JIS K6251, using a JIS No. 3 dumbbell-shaped sample, repeated strain was applied at a strain rate of 60%, and the number of times until breakage was measured. The numerical values in the table are shown as indexes with the value of Comparative Example 1 as 100. The larger the value, the higher the flex resistance, that is, the better the fatigue resistance.
・ Smell sensory evaluation At the predetermined time after vulcanization shown in Table 1, the smell of the obtained vulcanized rubber test piece was smelled by 10 people, and the number of people who answered that the smell of the fragrance was 6 or more. “It was judged as“ vulcanized rubber odor ”by 5 or less people.
The results are shown in Table 1.

* 1: IIR (brominated butyl rubber, bromobutyl 2255 manufactured by Nippon Butyl Co., Ltd.)
* 2: NR (RSS # 3)
* 3: Carbon black (Niteron Carbon Co., Ltd. Niteron # 55S GPF (nitrogen adsorption specific surface area = 28 m ² / g)
* 4: Zinc oxide (3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.)
* 5: Resin (aromatic petroleum resin, FR-120 manufactured by Air Water)
* 6: Oil (Extract No. 4 manufactured by Showa Shell Sekiyu KK)
* 7: Sulfur (Tsurumi Chemical Co., Ltd., oil-treated sulfur)
* 8: Vulcanization accelerator (Sunshine DM-PO manufactured by Sanshin Chemical Industry Co., Ltd.)
* 9: Fragrance (lemon flavor)
* 10: Microcapsules containing fragrances (spherical substances with an average particle size of 30 μm, wrapped in the above-mentioned lemon-based fragrance as a core material with wall material made of acrylic resin with a thickness of 8 μm)

As apparent from Table 1 above, the rubber composition for tire inner liners prepared in Examples 1 to 3 of the present invention was formulated with a specific amount of microcapsules containing a fragrance in a rubber component having a specific composition. As a result, it was revealed that superior air permeation prevention performance and fatigue resistance were imparted compared to the conventional representative composition of Comparative Example 1, and fragrance was emitted over a long period of time.
On the other hand, Comparative Example 2 uses NR as a rubber component, does not use a microcapsule containing a fragrance, and simply blends a fragrance, so it cannot obtain air permeation prevention performance, It was also found that the fragrance divergence was concentrated in a short period after vulcanization and the effect did not last long.
Comparative Example 3 is a system in which the NR is reduced and butyl rubber is blended as compared with the blended formulation of Comparative Example 2, but the microcapsules containing the fragrance are not used, and only the fragrance is blended. It has been found that the desired air permeation prevention performance and fatigue resistance cannot be obtained, and that the fragrance emission does not last for a long time.
In Comparative Example 4, since the blending amount of the microcapsules containing the fragrance was less than the lower limit specified in the present invention, improvement in air permeation prevention performance and fatigue resistance was not recognized. It was also found that the fragrance divergence was concentrated in a short period after vulcanization and the effect did not last long.
In Comparative Example 5, since the blending amount of the microcapsules containing the fragrance exceeded the upper limit defined in the present invention, the fatigue resistance was deteriorated.
Although the comparative example 6 mix | blends the microcapsule containing a fragrance | flavor, since the butyl-type rubber is not used, the divergence of a fragrance does not continue for a long period of time, and especially the air permeation prevention performance deteriorated.

Claims (2)

  A rubber composition for a tire inner liner, comprising 0.5 to 15 parts by mass of a microcapsule containing a fragrance per 100 parts by mass of a rubber component containing 50 parts by mass or more of butyl rubber.   A pneumatic tire using the rubber composition for a tire inner liner according to claim 1 as an inner liner.