JP2019001925A - Rubber composition for sealant - Google Patents

Abstract

To provide a rubber composition for sealant capable of saving weight of a sealant material per unit volume, absorbing cavity resonance tone generated in a tire by a hollow part while alleviating ununiformity of weight, providing a sound absorption effect and excellent in sound attenuation.SOLUTION: There is provided a rubber composition for sealant containing a butyl rubber as a rubber component, and a hollow fiber as an additive. There is provided a rubber composition for sealant, in which hollow rate (A) of the hollow fiber is 10 to 50% and fiber length thereof is 0.1 to 10 mm. There is provided a rubber composition for sealant, in which content of the hollow fiber is preferably 5 to 20 pts.mass based on 100 pts.mass of the rubber component.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition for a sealant that is optimal for a sealant material having a safety function such as a tire that enables safe traveling during puncture.

2. Description of the Related Art Conventionally, a type in which a product tire is manufactured by applying a highly adhesive sealant material is known.
This sealant material is usually a member arranged on the inner surface of the tread portion of the pneumatic tire. When the gas in the pneumatic tire is ejected from the damaged portion to the outside during puncture or the like, the sealant is applied to the damaged portion. This is a tire safety function that enables safe driving by preventing the pneumatic tire from bursting or suddenly lowering the internal pressure by flowing and sealing.

  Conventionally, as a rubber composition for a sealant, for example, a cylinder formed of a resin film mainly composed of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer in a thermoplastic resin on the inner surface of a tread portion of a tire. There are known ones that are filled inside (see, for example, Patent Document 1).

  However, if the layer of the sealant material as described in Patent Document 1 is disposed on the inner surface of the tire, the weight increases, and the fluidity causes fluidity. There is a problem such as an increase in the cavity resonance sound generated in the case.

JP 2009-269446 A (Claims, Examples, etc.)

  The present invention intends to solve the above-mentioned problems of the prior art, and reduces the weight of the sealant material without impairing the puncture prevention function of the sealant material arranged on the tire inner surface or the like. An object of the present invention is to provide a rubber composition for a sealant that alleviates non-uniformity and absorbs cavity resonance generated inside a tire to obtain a sound absorption effect.

  As a result of intensive investigations in view of the above-mentioned problems of the prior art, the present inventor has found that the rubber composition for sealant can be obtained by including butyl rubber as a rubber component and a specific material as an additive. The headline and the present invention have been completed.

That is, the rubber composition for sealant of the present invention is characterized by containing butyl rubber as a rubber component and hollow fibers as an additive. By including this hollow fiber, the weight of the sealant material per unit volume can be reduced, the non-uniformity of the weight can be eased, and the hollow part can absorb the cavity resonance sound generated inside the tire, thereby absorbing the sound. The effect is obtained and the silence is demonstrated.
The hollow ratio of the hollow fiber is preferably 10 to 50%, and the fiber length of the hollow fiber is preferably 0.1 to 10 mm. By making the hollow ratio (A) and fiber length (B) of the hollow fiber within the above ranges, the weight can be further reduced, the non-uniformity of the weight is further reduced, and the hollow portion is inside the tire. Absorbing the generated cavity resonance sound and the like, a further sound absorption effect is obtained, and the silence is further exhibited.
It is preferable that content of the said hollow fiber is 5-20 mass parts with respect to 100 mass parts of rubber components. By setting the content of the hollow fiber within the above range, it is possible to achieve both high weight reduction, reduction of weight non-uniformity, and sound deadening.

  According to the present invention, the weight of the sealant material per unit volume can be reduced without impairing the basic performance of the sealant material, the unevenness of the weight can be reduced, and a hollow portion is generated inside the tire or the like. A rubber composition for a sealant that absorbs cavity resonance sound and the like, obtains a sound absorbing effect, and has excellent sound deadening properties is provided.

It is the fragmentary sectional view which showed typically an example of the tire using the rubber composition for sealants of this invention.

Hereinafter, embodiments of the present invention will be specifically described.
The rubber composition for a sealant of the present invention is characterized by containing butyl rubber as a rubber component and hollow fibers as an additive.

[Rubber component]
The rubber component used in the present invention is not particularly limited as long as it is a rubber component used for a sealant, but at least butyl rubber (IIR) from the viewpoint of improvement in puncture prevention function, deterioration resistance, air permeability, and the like. It is necessary to include.

  As the butyl rubber used in the present invention, either modified butyl rubber or unmodified butyl rubber can be used, or these may be mixed. As the modified butyl rubber, halogenated butyl rubber such as chlorinated butyl rubber and brominated butyl rubber can be suitably used. Butyl rubber has the advantage of high crack resistance compared to other low air-permeable resin compositions and the like, and is a material that can be suitably used as a sealant.

The rubber component other than the butyl rubber is not particularly limited, and a conventionally known rubber component can be used. For example, a diene rubber has improved crack resistance, resistance to peeling from adjacent members, and tire molding. From the viewpoint of ensuring workability, it is preferable.
The diene rubber is not particularly limited. For example, natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), ethylene propylene rubber (EPDM), acrylonitrile-butadiene rubber. Examples thereof include diene rubbers such as (NBR) and chloroprene rubber (CR). These may be used individually by 1 type and may be used in combination of 2 or more type.

  The proportion of butyl rubber in the rubber component may be adjusted as appropriate according to the desired performance and the like, and is 30% by mass or more based on the total amount of the rubber component from the viewpoint of ensuring air permeation resistance and sealing performance. It is preferable that it is 40-100 mass%, and it is more preferable.

[Hollow fiber]
In the present invention, the “hollow fiber” means a fiber having a hollow portion (hole) inside, and is not particularly limited as long as it is a fiber having a hollow portion in the fiber cross section.
The cross-sectional shape of the hollow fiber that can be used is not particularly limited, and for example, a circular shape, a triangular shape, a polygonal shape such as a square shape, a flat shape, an oval shape, a star shape, or the like can be adopted. And the shape of the hollow portion on the outside and the inside of the fiber cross section may be different, like the same shape with a circular inside hollow part, the outside of the fiber cross section is circular, and the inside hollow part is a triangular shape, Furthermore, it may be a well-shaped (multiaxial intersection, etc.), a C-shaped hollow fiber (C-shaped hollow fiber including a slit in which a cross section of the hollow fiber is opened), an atypical hollow fiber such as an eyeglass type, or the like. Further, in addition to one hollow part (single hole type) in the fiber cross section, a plurality of hollow parts (porous type) may exist, and the number of hollow parts formed in the fiber cross section is one. Or two or more may be sufficient.

  The raw material used for the hollow fiber may be either an organic material or an inorganic material as long as it can be processed into a hollow fiber. For example, various organic polyamide materials such as nylon 6, nylon 66, and aromatic polyamide are used as the organic material. Fiber, Polyethylene terephthalate, Polybutylene terephthalate, Polylactic acid, Polyglycolic acid, Polyester fiber such as polycarbonate, Acrylic fiber such as polyacrylonitrile, Polyolefin fiber such as polyethylene and polypropylene, Polymethyl methacrylate Polymethacrylate fibers such as polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, polyurethane fibers, phenol fibers, polyvinylidene fluoride, polytetrafluoroethylene, etc. Ranaru fluorine-based fibers, polymethylpentene fibers, can be used polyalkylene para oxybenzoate material such systems, glass fiber in the inorganic material, such as carbon fiber may be used. Moreover, you may use the said material combining each material. The material forming the hollow fiber may contain a heat stabilizer, various stabilizers, and the like as necessary.

The manufacturing method of the said hollow fiber is not specifically limited, It can manufacture by a well-known method. For example, as a method of making a hollow fiber from the beginning, a method of manufacturing using a horseshoe type, C type nozzle, double tube nozzle or the like as a nozzle, or by stretching a hollow fiber precursor made of a thermoplastic resin A method of reducing the diameter, and the like. Further, a fiber precursor having different components at least in the central portion and the outer peripheral portion is produced, and the central component is removed from the fiber precursor by, for example, removing the hollow fiber. And the like. As the hollow fiber, one produced by any method can be used.
Further, the hollow fiber may be composed of a composite fiber as long as it has a hollow part in the fiber cross section, and the composite fiber is a core-sheath composite fiber in which the cross section is arranged in a core-sheath type. , Parallel composite fibers whose sections are arranged in a parallel type, and radiation composite fibers whose sections are arranged in a radial type.

  The hollow fiber having the above-described structure used in the present invention reduces the weight of the sealant material per unit volume by reducing the weight of the sealant material by being contained in the sealant rubber composition. It can absorb the cavity resonance sound and the like, and can exhibit the silencing property due to the sound absorption effect. Preferably, the hollow ratio (A), fiber length (B), etc. of the hollow fiber are as follows. desirable.

The hollow ratio (A) of the hollow fiber is not particularly limited, but can be appropriately selected according to further improvement of the effect of the present invention, processing conditions, and required characteristics, and preferably a sufficient sound absorbing effect and weight reduction. From the above point, it is desirable that the content be 10 to 50%, more preferably 25 to 45%, and particularly preferably 30 to 45%.
By setting the hollow ratio to 10% or more, a sufficient sound absorbing effect is exhibited. On the other hand, when it is 50% or less, the rubber matrix is not immersed and the effect of the present invention can be further exhibited.

In the present invention, the hollow ratio of the hollow fiber to be used can be calculated by measuring the total cross-sectional area (S1) and the area of the hollow portion (S2) in the fiber cross section and using the following equation. However, when there are a plurality of hollow portions in the fiber cross section, the total area of all the hollow portions is defined as the area of the hollow portion (S2). In addition, the calculation method of the hollow ratio in a C-shaped hollow fiber connects the open outer periphery contact with a line, and calculates the hollow area enclosed by the line and the fiber inner peripheral part as S2.
Hollow ratio (%) = (S2 / S1) × 100

The fiber length (B) of the hollow fiber can be arbitrarily set, and is preferably 0.1 to 10 mm, and more preferably 0.5 to 8 mm, from the viewpoints of coatability and workability of the sealant. .
When the fiber length is 0.1 mm or more, a sufficient sound absorbing effect is exhibited. On the other hand, when the fiber length is 10 mm or less, the application of the sealant is not uneven, and the application property and workability of the sealant are improved. It becomes.

  Furthermore, the hollow fiber to be used preferably has a softening point of 140 ° C. or higher in terms of production of the sealant material.

  Examples of commercially available hollow fibers that can be used include hollow polyethylene terephthalate fiber “Aerocapsule” (single-hole type) manufactured by Teijin Frontier, hollow polyester fiber “octa” (single-hole type), and hollow polyester manufactured by Asahi Kasei Corporation. Fiber “twin air” (glasses type), hollow nylon fiber “Sebona Samron” (porous type) manufactured by Toray, C-type hollow polyester fiber “Airy Samron”, hollow polyethylene terephthalate fiber “air mint” manufactured by Kuraray (porous type) ), Hollow PVA fiber “Claron K-II” (porous type), hollow polyester fiber “Air Max” (single-hole type) manufactured by Toyobo STC, well type (multi-axis crossed) hollow nylon fiber “made by Unitika Trading” "Micro Art" (single hole type), hollow polyester fiber "Air Hull" manufactured by Mitsubishi Rayon "(Single-hole type) and the like although not limited thereto.

The content of the hollow fiber used in the present invention is preferably 5 to 20 parts by mass, and more preferably 8 to 15 parts by mass with respect to 100 parts by mass of the rubber component.
By setting the content of the hollow fiber to 5 parts by mass or more, the weight of the sealant material per unit volume can be reduced. On the other hand, by setting the content to 20 parts by mass or less, the application of the sealant is uneven. In other words, the coating property and workability of the sealant are improved.

[Other ingredients]
The rubber composition for sealant according to the present invention is filled with a conventionally known reinforcing material such as carbon black and silica, alimina, calcium carbonate, etc. used for the rubber composition for sealant, in addition to the rubber component and hollow fiber described above. Materials, pigments (organic pigments, inorganic pigments), colorants such as dyes, stearic acid, tackifiers (tackifiers), vulcanizing agents, vulcanization accelerators, anti-aging agents, softeners, plasticizers, processing aids Such components may be added in an appropriate amount as necessary.

  The rubber composition for a sealant according to the present invention configured as described above is kneaded using a kneader such as a Banbury mixer or a kneader, and can be suitably used for a sealant such as an automobile tire by a general-purpose manufacturing method. it can.

In the tire using the rubber composition for a sealant according to the present invention, the rubber composition for a sealant of the present invention may be disposed on the inner surface of the tread portion or may be embedded in the inside. The size, shape, structure, etc. of the tire are not particularly limited and can be appropriately selected according to the purpose. For example, it can be suitably used for passenger car tires, truck / bus tires, motorcycle tires, bicycle tires, construction vehicle tires, aircraft tires, and the like. As the structure, a known structure can be adopted. For example, a structure having a pair of beads, a bead filler, a carcass, a sidewall portion, a belt portion, a tread portion, an inner liner, and the like can be preferably cited.
When the rubber composition for a sealant of the present invention is disposed on the inner surface, the thickness thereof is not particularly limited, and is appropriately determined depending on the use, purpose, type of the sealant material, fluidity of the sealant composition, and the like. Although it can be selected, it is usually preferably about 0.5 to 4 mm.

  FIG. 1 is a partial cross-sectional view showing an example in which a rubber composition for a sealant according to the present invention is used in a pneumatic tire. In an example of this pneumatic tire, a pair of bead portions 1, a pair of sidewall portions 2 that are continuous to the outside in the radial direction of the bead portion 1, and a tread portion 3 that straddles the sidewall portions 2. Become. A carcass 5 made of a carcass ply extending in a toroidal shape is disposed between the bead cores 4 of the bead portion 1, and a belt 6 having two belt layers is disposed radially outward of the tread portion 3 of the carcass 5. Thus, a tire skeleton is formed. Further, in this example of the pneumatic tire, the sealant 7 and the inner liner 8 are disposed on the tire inner surface side of the carcass 5 from the carcass 5 side.

  In this pneumatic tire, by using a rubber composition for a sealant that contains butyl rubber as a rubber component and a hollow fiber as an additive as the sealant 7, the gas in the pneumatic tire is exposed from the damaged part to the outside during puncture or the like. The sealant flows into the damaged part and seals when it is blown into the tire, thereby impairing the basic performance of the sealant, such as preventing the rupture of the pneumatic tire or sudden drop in internal pressure, enabling safe driving In addition, the weight of the sealant per unit volume can be reduced and the non-uniformity of the weight can be reduced, so that the fuel efficiency of the pneumatic tire can be improved, and a hollow portion is generated inside the tire. A pneumatic tire that absorbs cavity resonance sound and the like, obtains a sound absorbing effect, and has excellent sound deadening properties can be obtained.

  In the present invention, the rubber composition for sealant having the above-described configuration is used as the rubber composition for sealant in pneumatic tires such as automobile tires, truck / bus tires, construction vehicle tires, and aircraft tires. , Various pressure vessels having a sealant, such as ad balloons, balloons, rubber boats, hovercraft, rubber dams, dome-shaped spherical domes, and the like.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these.

(Examples 1-8 and Comparative Examples 1-3)
The rubber composition for sealants according to Examples 1 to 8 and Comparative Examples 1 to 3 was prepared using a kneader according to the compounding formulation (each rubber component, each hollow fiber, and other components) shown in Table 1 below.
About each obtained rubber composition for sealants, the lightness, sound absorption property, sealing performance, and coating viscosity were evaluated with the following evaluation method.
The evaluation results are shown in Table 1 below.

(Lightweight evaluation method)
Each of the obtained rubber compositions for sealant was molded into a sheet shape, and then the specific gravity was measured. The specific composition was expressed as an index with the weight of Comparative Example 1 being 100. A smaller value indicates a lighter weight.

(Sound absorption evaluation method)
Each of the obtained rubber compositions for sealant was applied to a tire (tire size: 195 / 65R15) (thickness: 3 mm) and assembled with a rim, and then the tire sound absorption was measured in an actual vehicle running test. Comparative Example 1 The sound absorptivity was expressed as an index with 100 as the sound absorption property. It shows that it is excellent in sound-absorbing property, so that a value is small.

(Seal performance evaluation method)
Each sealant rubber composition obtained was applied to the inside of the tire and assembled into a rim, and with the internal pressure (250 kPa) applied, 4 M size nails and 4 L size nails were stabbed to confirm the air leakage state. And evaluated according to the following evaluation criteria.
Evaluation criteria:
○: Within 2 small leaks.
Δ: 3 or more minute leaks, no major leaks.
X: One or more large leaks.

(Method for evaluating coating viscosity)
The obtained rubber composition for sealant was measured for viscosity with a Mooney viscometer (ML _{1 + 4} : 130 ° C.), and expressed as an index with the viscosity of Comparative Example 1 being 100. A larger value indicates a higher coating viscosity, and an index of 100 to 110 indicates excellent coating performance.

* 1 to * 8 in Table 1 above are as follows.
* 1: Bromobutyl 2255 (manufactured by ExxonMobil)
* 2: EP35 (manufactured by JSR)
* 3: Aero capsule (manufactured by Teijin Frontier), fiber length 2 mm, hollow ratio: 35%
* 4: Sebonner Samron (Toray Industries, Inc.), fiber length 2 mm, hollow ratio: 40%
* 5: Air mint (manufactured by Kuraray Co., Ltd.), fiber length 2 mm, hollow ratio: 40%
* 6: Airhart (Mitsubishi Rayon Co., Ltd.), fiber length 2 mm, hollow ratio: 30%
* 7: Microart (Unitika Trading Co., Ltd.), fiber length 2 mm, hollow ratio: 35%
* 8: Tetron (manufactured by Toray Industries, Inc.), fiber length 2 mm, hollow rate 0%
* 9: Super Oil Y22 (JX Nippon Oil & Energy Corporation)
* 10: REGAL300 (manufactured by Cabot)
* 11: HK200-5 (Hosoi Chemical Co., Ltd.)

As is clear from the results of Table 1 above, the rubber compositions for sealants of Examples 1 to 8 according to the present invention obtained favorable results in all of lightness, sound absorption, sealing performance, and coating performance. On the other hand, it was confirmed that the rubber compositions for sealants of Comparative Examples 1 to 3 were defective in at least one of lightness, sound absorption, sealing performance, and coating performance.
Looking at Comparative Examples 1 to 3, in Comparative Example 1, the hollow fiber is not included, and in Comparative Example 2 and Comparative Example 3, the effect of the present invention cannot be exhibited because of the non-hollow fiber. .

  A rubber composition for a sealant that can be suitably used as a sealant for pneumatic tires such as automobile tires, truck / bus tires, construction vehicle tires, and aircraft tires is obtained.

1 Bead part 2 Side wall part 3 Tread part 4 Bead core 5 Carcass 6 Belt 7 Sealant 8 Inner liner

Claims (4)

  A rubber composition for a sealant comprising butyl rubber as a rubber component and hollow fibers as an additive.   The rubber composition for sealant according to claim 1, wherein the hollow ratio (A) of the hollow fiber is 10 to 50%.   The rubber composition for a sealant according to claim 1 or 2, wherein the fiber length (B) of the hollow fiber is 0.1 to 10 mm.   The rubber composition for sealant according to any one of claims 1 to 3, wherein the content of the hollow fiber is 5 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

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