JP2014024921A - Rubber compositions and pneumatic tires using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition in which a laminar or tabular clay mineral is blended at high blending quantity to the rubber constituent and which is characterized in that the air permeability thereof is decreased without causing a green strength deterioration of the unvulcanized rubber composition, and a pneumatic tire using the same.SOLUTION: Such a rubber composition is a rubber composition which is characterized in that 80 to 160 weight parts of laminar or tabular clay mineral (B) and polydinitrosobenzene, per 100 weight parts of rubber constituent (A) are blended.

Description

  The present invention relates to a rubber composition and a pneumatic tire using the rubber composition as an inner liner. In particular, the workability is improved without lowering the green strength of the unvulcanized rubber composition, and the air permeability is reduced. The present invention relates to a rubber composition for an inner liner and a pneumatic tire using the same.

  Conventionally, for the purpose of reducing the fuel consumption and weight of a tire, it has been proposed to reduce the air permeability of the inner liner of the tire and make the inner liner thinner. For example, it has been proposed to use a rubber composition filled with low carbon black at a high blending amount for the inner liner to reduce the thickness of the inner liner. There was a problem with sex.

In contrast, by using a rubber composition containing non-reinforcing and flat mica and clay for the inner liner, the air permeability can be reduced while maintaining the flexibility and low temperature durability of the inner liner. It has been known. For example, Patent Literature 1 discloses a rubber composition for an inner liner in which 1 to 150 parts by mass of an organically treated layered clay mineral is blended with respect to 100 parts by mass of a solid rubber. Discloses a rubber composition for an inner liner in which a rubber component and a layered or plate-like mineral having an aspect ratio of 3 or more and less than 30 are blended.
However, air permeability can be reduced by blending non-reinforcing and flat mica and clay at a high content, but tire production efficiency is reduced due to a decrease in vulcanization speed, and butyl rubber content is reduced. If the amount increases, the strength of the unvulcanized rubber composition (so-called green strength) decreases, resulting in a difference in strength depending on the direction of the sheet after calendering, or with a roll at the lower part of a kneader such as a Banbury mixer. There is a problem in that adhesion may occur, work efficiency deteriorates, and productivity decreases.

JP 2003-335902 A International Publication No. 01/62846

  The present invention relates to a rubber composition containing a layered or plate-like clay mineral in a high content, and a rubber composition having reduced air permeability without reducing the green strength of the unvulcanized rubber composition, and It is an object to provide a used pneumatic tire.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have formulated the above-mentioned problems by blending a specific organic compound in a rubber composition containing a high-content layered or platy clay mineral in the rubber component. Has been found to solve the problem, and the present invention has been completed.
That is, the present invention
1. A rubber composition comprising 80 to 160 parts by mass of a layered or platy clay mineral (B) and polydinitrosobenzene with respect to 100 parts by mass of the rubber component (A),
2. Furthermore, the rubber composition according to 1 above, wherein 15 parts by mass or less of carbon black is blended with 100 parts by mass of the rubber component (A),
3. Furthermore, the rubber composition according to 1 or 2 above, wherein 100 parts by mass of the rubber component (A) is blended with more than 1 part by mass and 15 parts by mass or less of zinc oxide.
4). The rubber composition according to any one of 1 to 3 above, wherein 0.01 to 10 parts by mass of the polydinitrosobenzene is blended with respect to 100 parts by mass of the rubber component (A).
5. The rubber composition according to any one of 1 to 4, wherein the rubber component (A) contains 80 to 100% by mass of a butyl rubber,
6). The rubber composition according to any one of 1 to 5, wherein the rubber composition is a rubber composition for an inner liner of a tire,
7). 7. A method for producing a rubber composition as described in any one of 1 to 6 above, wherein the rubber composition is kneaded in a plurality of stages, and at least a part of the polydinitrosobenzene in any stage other than the final stage of kneading. A method for producing a rubber composition, comprising adding
8). 7. The method for producing a rubber composition according to any one of 3 to 6, wherein the rubber composition is kneaded in a plurality of stages, and at least a part of the polydinitrosobenzene is produced in any stage other than the final stage of kneading. 8. A method for producing a rubber composition, comprising adding at least a part of the zinc oxide; A pneumatic tire using, as an inner liner, the rubber composition according to any one of 1 to 6 or the rubber composition obtained by the production method according to 7 or 8,
Is to provide.

  According to the present invention, in a rubber composition containing a layered or platy clay mineral in a high content in a rubber component, a rubber having reduced air permeability without causing a decrease in green strength of an unvulcanized rubber composition. A composition and a pneumatic tire using the composition can be provided.

It is a schematic diagram which shows the definition of the average aspect-ratio used for the layered or plate-like clay mineral (B) based on this invention.

The present invention is described in detail below.
[Rubber composition]
The rubber composition of the present invention is characterized in that 80 to 160 parts by mass of a layered or platy clay mineral (B) and polydinitrosobenzene are blended with 100 parts by mass of the rubber component (A). By blending polydinitrosobenzene, the green strength of the unvulcanized rubber composition can be increased, roll adhesion and the like can be prevented, and a decrease in the vulcanization rate can be suppressed.

[Rubber component (A)]
Although there is no restriction | limiting in particular as a rubber component used for the rubber composition of this invention, Diene type rubber is preferable and natural rubber (NR) and diene type synthetic rubber are mentioned as diene type rubber. Here, as the diene-based synthetic rubber, butyl rubber, polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber ( CR) and the like. These rubber components may be used alone or in combination of two or more.

In the rubber composition of the present invention, the rubber component (A) is preferably a butyl rubber. When the rubber component (A) is a butyl rubber, the air permeability of the rubber composition can be greatly reduced, and the rubber composition is suitable for an inner liner of a tire. In the rubber component (A), the butyl rubber is preferably 80 to 100% by mass. In this case, the rubber component (A) is 80 to 100% by mass of the butyl rubber and other diene rubbers 20 to 0. More preferably, the butyl rubber is 95 to 100% by mass, and other diene rubbers are 5 to 0% by mass. Here, the other diene rubber refers to a diene rubber other than the butyl rubber.
The butyl rubber includes not only butyl rubber (IIR) but also halogenated butyl rubber. Examples of the halogenated butyl rubber include halogenated copolymers of chlorinated butyl rubber, brominated butyl rubber, isobutylene and p-methylstyrene (particularly, , A brominated copolymer of isobutylene and p-methylstyrene). The halogenated copolymer of isobutylene and p-methylstyrene usually contains 0.5 to 20 mol% of p-methylstyrene. A brominated copolymer of isobutylene and p-methylstyrene is available from ExxonMobil Chemical Company under the trade name “EXXPRO 89-4” (registered trademark) (about 5% by weight p-methylstyrene and about 0. 75 mol%).

[Layered or platy clay mineral (B)]
The layered or plate-like clay mineral (B) used in the rubber composition of the present invention is used to reduce air permeability while maintaining flex resistance and low temperature durability when used as a tire inner liner. .
As the layered or plate-like clay mineral (B), either a natural product or a synthetic product can be used. Examples of the layered or plate-like clay mineral (B) include water-containing composites of clay (for example, kaolin clay, sericite clay, calcined clay, etc.), mica, feldspar, silica and alumina. Examples of layered clay minerals include smectite clay minerals such as montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, halloysite, and swelling mica. These layered or plate-like clay minerals (B) may be natural or synthesized. Moreover, these may be used individually by 1 type and may be used in combination of 2 or more type.

Of the layered or plate-like clay minerals (B) described above used in the present invention, organically layered clay minerals can also be preferably used as the layered clay mineral.
Here, the organized layered clay mineral refers to a layered clay mineral organized by organic onium ions. As this layered clay mineral, the aforementioned montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite and other smectite clay minerals, vermiculite, halloysite, and swelling mica can be used.

  The organically layered clay mineral may be a layered clay mineral that is swellable with respect to an organic solvent so that the organic onium salt molecules described later can easily enter between the layers of the clay mineral (so-called intercalation). preferable. By using such a swellable layered clay mineral, the organic onium salt sufficiently penetrates between the layers, and when kneaded with rubber, it further expands in the rubber matrix due to the expansion of the layers by the penetration of rubber molecules. The dispersion of the layered clay mineral is obtained on the nano order. From this point, among the layered clay minerals, mica having a large average particle diameter, particularly swellable mica is preferable. The layered clay mineral can be organically treated by treatment with an organic onium salt, and an ammonium salt is particularly preferred as the organic onium salt.

  Examples of the organic onium ion that organicizes the layered clay mineral include hexyl ammonium ion, octyl ammonium ion, 2-ethylhexyl ammonium ion, dodecyl ammonium ion, octadecyl ammonium ion, dioctyl dimethyl ammonium ion, trioctyl ammonium ion, and distearyl. Dimethyl ammonium ion, trimethyl octadecyl ammonium ion, dimethyl octadecyl ammonium ion, methyl octadecyl ammonium ion, trimethyl dodecyl ammonium ion, dimethyl dodecyl ammonium ion, methyl dodecyl ammonium ion, trimethyl hexadecyl ammonium ion, dimethyl hexadecyl ammonium ion, methyl hexadecyl ammonium ion Ion, and the like.

Further, as unsaturated and unsaturated organic onium ions, 1-hexenylammonium ion, 1-dodecenylammonium ion, 9-octadecenylammonium ion (oleylammonium ion), 9,12-octadecadienyl Ammonium ions (linol ammonium ions), 9,12,15-octadecatrienyl ammonium ions (linoleyl ammonium ions) and the like can also be used. Among the above-mentioned organically modified layered viscosity minerals, those organically formed with distearyldimethylammonium ions are particularly preferable. Organization of the layered clay mineral is obtained, for example, by immersing the clay mineral in an aqueous solution containing organic onium ions and then washing the clay mineral with water to remove excess organic onium ions. The organically modified layered clay mineral thus obtained is blended and kneaded with the rubber component, so that the layered clay mineral is dispersed in the rubber as nano-order fine particles and extremely effectively improves the air permeation resistance. It becomes possible.
For this reason, the above-mentioned organized layered clay mineral is blended with a rubber component having a glass transition temperature of −55 ° C. or less, in particular, so that the rubber composition satisfies both air permeation resistance and low temperature durability. Can be obtained.

As the clay mineral used as the rubber composition of the present invention, clay is particularly preferable among the layered or plate-like clay minerals (B) described above, and kaolin clay, sericite clay, fired clay, and surface treatment are performed. A plate-like clay such as silane-modified clay is preferable, and kaolin clay is particularly preferable. If the average particle diameter (average Stokes equivalent diameter) of the layered or plate-like viscosity mineral of the component (B) is too large, the bending resistance is reduced, so it is preferably 50 μm or less, and more preferably 0.2 to 30 μm. A range of about 0.2 to 5 μm is particularly preferable, and a range of 0.2 to 2 μm is most preferable.
If the average aspect ratio of the lamellar or platy clay mineral (B) is 2 to 200, the plane of the lamellar or platy clay mineral particles in the inner liner is oriented in a direction intersecting the thickness direction of the inner liner. As a result of blocking the air permeation path, good air permeation resistance is obtained, but the average aspect ratio is preferably 3 to 150, more preferably 5 to 100, still more preferably 5 to 50, and particularly preferably 5 to 30. As a result, better air permeation resistance can be obtained.
If the average aspect ratio of the component (B) is 200 or less, the component (B) will be more uniformly dispersed during rubber kneading, resulting in poor flex resistance and air permeability resistance due to poor dispersion. Can be suitably prevented. Moreover, if the average aspect ratio is 3 or more, the air permeation resistance is further improved.
The average aspect ratio is determined as x / y from the average major axis x and the average thickness y as shown in FIG.

  In the rubber composition of this invention, 80-160 mass parts of layered or plate-like clay minerals (B) are mix | blended with respect to 100 mass parts of rubber components (A), It is characterized by the above-mentioned. When the amount of the component (B) is less than 80 parts by mass, the air permeability is increased and the performance when used as a tire is deteriorated. Moreover, when (B) component exceeds 160 mass parts, the workability | operativity of a kneading | mixing step or a rolling (calendar) process will fall. 85-160 mass parts is preferable and the compounding quantity of (B) component has more preferable 90-150 mass parts.

[Polydinitrosobenzene]
A preferred example of the polydinitrosobenzene used in the rubber composition of the invention is poly-p-dinitrosobenzene. As 25% poly-p-dinitrosobenzene, Ouchi Shinsei Chemical Co., Ltd., trade name “Barnock DNB” is commercially available.
When the rubber composition of the invention is blended with polydinitrosobenzene, the green strength of the unvulcanized rubber composition is increased and roll adhesion is less likely to occur. In addition, polydinitrosobenzene serves as a vulcanization activator in the case of the combined use of a thiazole vulcanization accelerator and a thiuram vulcanization accelerator in sulfur vulcanization, and thus also has an effect of shortening the vulcanization time.
The rubber composition of the invention preferably contains 0.01 to 10 parts by mass of polydinitrosobenzene per 100 parts by mass of the rubber component (A). If it is 0.01 mass part or more, the green strength of an unvulcanized rubber composition will improve, and if it is 10 mass parts or less, it is economically advantageous.

[Carbon black]
As carbon black used as desired in the rubber composition of the invention, any carbon black conventionally used for reinforcing rubber compositions can be appropriately selected and used. For example, as a preferable carbon black, N539 (FEF-LS), N550 (FEF), N660 (GPF), N634 (GPF-LS), N642 (GPF-LS), N7524, N762 (SRF-LM-NS) ), N772, N774 (SRF-HM-NS), and the like. Carbon black preferably has the following colloidal characteristics. That is, the nitrogen adsorption specific surface area (N ₂ SA) is preferably 50 m ² / g or less, and more preferably 20 to 50 m ² / g. Further, dibutyl phthalate (DBP) absorption is preferably 125 cm ^3/100 g or less, and more preferably be about 30~120cm ³ / 100g. Here, the nitrogen adsorption specific surface area (N ₂ SA) of the colloidal characteristics is a value measured according to JIS K 6217-2: 2001, and the DBP absorption is a value measured according to JIS K 6217-4: 2008.
The rubber composition of the present invention preferably contains 15 parts by mass or less of carbon black and more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the rubber component (A). By setting the blending amount of carbon black to 15 parts by mass or less, it becomes possible to regularly arrange the layered or plate-like clay mineral (B) in the tire circumferential direction, and while maintaining the flexibility and low temperature, Low air resistance can be achieved. In addition, by blending carbon black, the green strength of the unvulcanized rubber composition can be increased, and deterioration in factory workability due to mogging and chigile during the rubber composition transportation can also be suppressed.

[Zinc oxide]
Zinc oxide optionally used in the rubber composition of the invention is generally used as a vulcanization accelerating aid for the rubber composition. Zinc white, active zinc oxide, surface-treated zinc oxide, composite oxidation Zinc oxide and zinc oxide-containing materials such as zinc and composite active zinc oxide can be used.
In the rubber composition of this invention, it is preferable to mix | blend zinc oxide more than 1 mass part and 15 mass parts or less with respect to 100 mass parts of rubber components (A), and mix | blending 1.5-15 mass parts. More preferably, it is further more preferable to mix | blend 2-15 mass parts. By blending more than 1 part by mass and not more than 15 parts by mass of zinc oxide, it is possible to prevent a decrease in the vulcanization rate and to prevent a decrease in the green strength of the unvulcanized rubber composition. Therefore, the working efficiency at the time of tire manufacture when the rubber composition of the present invention is used as an inner liner of a tire can be improved.

  In the rubber composition of the present invention, it is not essential to add a fatty acid metal salt, but the rubber composition of the present invention preferably contains a fatty acid metal salt. The fatty acid metal salt is a salt of a fatty acid and a metal, and has an effect of improving workability of the rubber composition by suppressing adhesion of the unvulcanized rubber composition to the roll. Here, the fatty acid constituting the fatty acid metal salt includes palmitic acid, stearic acid, oleic acid, linoleic acid, and the like, while the metals constituting the fatty acid metal salt include K, Na, Ca, Zn, Mg. , Ba and the like. The fatty acid metal salt is, for example, palm oil, palm kernel oil, olive oil, almond oil, canola oil, peanut oil, rice sugar oil, cocoa butter, soybean oil, cottonseed oil, sesame oil, linseed oil, castor oil, rapeseed oil, etc. It can be obtained by adding a base such as sodium hydroxide or potassium hydroxide to vegetable oil or animal oil such as beef tallow and saponifying (ie, hydrolyzing into glycerin and a fatty acid metal salt). In addition, the said fatty acid salt may be used individually by 1 type, and may mix and use 2 or more types.

  The blending amount of the fatty acid metal salt is preferably in the range of 0.1 to 3 parts by mass, more preferably in the range of 0.1 to 2 parts by mass with respect to 100 parts by mass of the rubber component. When the blending amount of the fatty acid metal salt is in the range of 0.1 to 3 parts by mass with respect to 100 parts by mass of the rubber component, the effect of improving the workability of the rubber composition becomes particularly remarkable.

  Further, the rubber composition of the present invention may contain a process oil such as naphthenic oil, paraffinic oil, and aroma oil, and a softening agent such as blown asphalt. The blending amount is not particularly limited and is appropriately blended depending on the application. For example, when the total of the blending amount of carbon black and the laminar or plate-like clay mineral (B) is relatively small (rubber component 100 (Up to about 100 parts by mass per part by mass) may be blended in an amount of 1 part by mass or more, particularly 3 parts by mass to 20 parts by mass with respect to 100 parts by mass of the rubber component. Here, the naphthenic oil has a% CN of 30 or more by ring analysis (mdM method), and the paraffinic oil has a% CP of 60 or more.

  Further, in the rubber composition of the present invention, in order to improve the dispersibility of the layered or plate-like clay mineral (B) in the rubber, if desired, dispersion improvement of a silane coupling agent, dimethylstearylamine, triethanolamine, etc. An agent can be added. The addition amount is preferably 0.1 to 5 parts by mass per 100 parts by mass of the rubber component.

Furthermore, organic short fibers made of an organic polymer resin can be blended in the rubber composition of the present invention. Thus, by mix | blending an organic short fiber, the inner surface code | cord exposure which may arise when manufacturing the tire with the thin inner liner thickness can be suppressed efficiently. The average diameter of the organic short fibers is preferably 1 μm to 100 μm, and the average length is preferably about 0.1 mm to 0.5 mm. The organic short fibers may be blended as a composite (hereinafter sometimes referred to as FRR) obtained by kneading short fibers and an unvulcanized rubber component in advance.
The blending amount of such organic short fibers is preferably 0.3 to 15 parts by mass per 100 parts by mass of the rubber component. When the blending amount is 0.3 parts by mass or more, the effect of eliminating the inner surface cord exposure can be sufficiently obtained, and when the blending amount is 5 parts by mass or less, adverse effects on workability can be suppressed. The material of the organic short fiber is not particularly limited, and examples thereof include polyamides such as nylon 6, ny66, syndiotactic-1,2-polybutadiene, isotactic polypropylene, polyethylene, and the like. Polyamide is preferred. When organic short fibers are blended, an adhesion improver for rubber and fibers such as hexamethylenetetramine and resorcin can be further blended in order to increase the modulus of the resulting rubber composition.

  In addition to the above-mentioned compounding agents, the rubber composition of the present invention contains various chemicals commonly used in the rubber industry, such as vulcanizing agents, vulcanization accelerators, anti-aging agents, scorch preventing agents, stearic acid and the like. It can mix | blend in the range which does not impair the objective of invention.

  The rubber composition of the present invention can be produced by a usual method. That is, the rubber component (A), the layered or plate-like clay mineral (B), polydinitrosobenzene, and carbon black, zinc oxide and other compounding agents, which are appropriately used as necessary, are kneaded using a kneader. .

  As a method for producing the rubber composition of the present invention, it is preferable that the rubber composition is kneaded in a plurality of stages, and at least a part of polydinitrosobenzene is added in any stage other than the final stage of kneading. By adding polydinitrosobenzene at any stage other than the final stage of kneading, the green strength of the unvulcanized rubber composition can be increased more effectively.

  Furthermore, as a method for producing the rubber composition of the present invention, the rubber composition is kneaded in a plurality of stages, and at least one part of the polydinitrosobenzene and at least one of the zinc oxides at any stage other than the final stage of kneading. It is preferable to add parts. By adding polydinitrosobenzene and zinc oxide at any stage other than the final stage of kneading, the green strength of the unvulcanized rubber composition is increased more effectively and the viscosity of the unvulcanized rubber composition is reduced. In addition, it is preferable because the processability of the unvulcanized rubber composition can be improved and the vulcanization time can be further improved (the vulcanization time can be shortened).

  In the present invention, the final stage of kneading refers to a kneading stage in which a vulcanizing agent such as sulfur is added. Further, any stage other than the final stage of kneading is a stage of kneading only the rubber component (A) or a stage of kneading the rubber component (A) and a filler other than the layered or plate-like clay mineral (B). Is not included. As any stage other than the final stage of kneading, the first stage of kneading the rubber component (A) and at least a part of the layered or platy clay mineral (B) (hereinafter referred to as “first stage of kneading”) Or the second stage of kneading. The second stage of kneading may be a stage of kneading the rubber component (A) and the remainder of the layered or platy clay mineral (B), or all the lamellar or platy clay minerals ( When B) is kneaded, it may be a stage in which polydinitrosobenzene alone or polydinitrosobenzene and a compounding agent other than the layered or plate-like clay mineral (B) are kneaded. Stages other than the final stage of kneading may be collectively referred to as “master batch kneading stage”.

The maximum temperature of the rubber composition in the first stage of kneading according to the present invention is preferably 80 to 150 ° C.
The kneading time in the first stage of kneading is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and further preferably 3 to 12 minutes. If the kneading time is 1 minute or longer, the dispersibility of the layered or platy clay mineral (B) can be improved, and if the kneading time is 30 minutes or shorter, the molecular weight reduction of the rubber component (A) is suppressed. Because it can be done.
Moreover, when providing the 2nd stage of kneading | mixing depending on necessity, it is preferable that the maximum temperature of the rubber composition in the 2nd stage of kneading | mixing is 80-150 degreeC. The kneading time in the second stage of kneading is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and further preferably 3 to 12 minutes.

  In the first stage of the kneading, it is preferable that only the rubber component (A) is masticated by a kneading machine such as a Banbury mixer. In the present invention, this mastication treatment is preferably performed for 10 seconds or more. By setting the mastication treatment time to 10 seconds or longer, the layered or platy clay mineral (B) is added to the rotor surface in the subsequent kneading treatment of the rubber component (A) and the lamellar or platy clay mineral (B). The formation of agglomerates can be suppressed, and excellent air permeation resistance and bending resistance can be obtained after vulcanization of the obtained rubber composition. In addition, since the productivity decreases when the mastication treatment time is lengthened, the mastication treatment time is more preferably in the range of 10 seconds to 60 seconds. Further, if the first kneading step is performed without performing the mastication treatment, an agglomerate of the layered or plate-like clay mineral (B) is easily generated on the rotor surface, and the air resistance of the rubber composition after vulcanization is increased. Permeability and bending resistance may not be obtained sufficiently.

The rubber composition that has been subjected to the kneading treatment process from the first stage to the last stage is subjected to a vulcanizing agent addition process by adding a vulcanizing agent and, if necessary, a vulcanization accelerator in the final stage.
The kneading is usually performed at a temperature in the range of about 80 to 120 ° C. in the vulcanizing agent addition step in this final stage. When the kneading temperature exceeds 120 ° C., vulcanization starts, which may cause a decrease in air permeation resistance and flex resistance of the rubber composition after vulcanization, which is not desirable. The kneading time at the final stage is usually a time within a range of about 1 to 10 minutes.

By using such a kneading method for the rubber composition of the present invention described above, the dispersibility of the layered or platy clay mineral (B) and carbon black is good, and the air permeation resistance, the flex resistance, A rubber composition having excellent low-temperature durability can be produced with high productivity.
The type of the kneader is not particularly limited, and can be appropriately selected from those normally used in the rubber industry, such as a closed mixer such as a Banbury mixer and an intermix, and a roll mixer, but a closed kneader is preferable.
The rubber composition of the present invention thus obtained is suitably used as a rubber composition for tire inner liners. The rubber composition should have a dynamic elastic modulus at −20 ° C. and a strain amplitude of 0.1% after vulcanization of 800 MPa or less, more preferably 600 MPa or less.

The pneumatic tire of the present invention is produced by a normal method using the rubber composition as an inner liner. That is, if necessary, the rubber composition of the present invention obtained by blending various chemicals as described above is processed as an inner liner member in an unvulcanized state, and calendered as an inner liner of a tire by a conventional manufacturing process. It is processed into a sheet by molding or the like. The inner liner layer is vulcanized at a vulcanization temperature of 130 ° C. or higher after being formed into a tire.
The rubber composition of the present invention can be vulcanized in a shorter time than the conventional vulcanization time despite the high content of the layered or plate-like clay mineral (B), and therefore the working time is reduced. This makes it possible to shorten the tire productivity. And air permeability can be reduced, without causing the strength fall of an unvulcanized rubber composition.
Further, by using the rubber composition of the present invention for the inner liner, a tire having a thin inner liner, that is, a tire having a thin gauge of the inner liner can be easily manufactured.

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. Various physical property evaluation methods were performed by the following methods.
(1) Green strength As the strength of the unvulcanized rubber composition, a tensile test of unvulcanized rubber was performed in accordance with JIS K 6251: 2010. A sample obtained by punching an unvulcanized rubber sheet with a thickness of 4.00 ± 0.40 mm into a ring shape (JIS-5 type) was pulled at a temperature of 40 ° C. at a rate of 100 ± 5 mm / min, and until the time of fracture. Stress measurement was performed to measure the tensile strength of the unvulcanized rubber composition. The green strength was expressed as an index with the tensile strength of Comparative Example 2 being 100.
Green strength index = {(tensile strength of unvulcanized rubber composition for test) / (tensile strength of unvulcanized rubber composition of Comparative Example 2)} × 100

(2) Roll adhesion The calendar work was performed with a 50 ° C. roll, and the adhesion of the rubber composition to the calendar roll when the calendar was formed was evaluated according to the following criteria.
A: Roll adhesion did not occur and the workability of the unvulcanized rubber composition was good.
○: Slight roll adhesion occurred, but the workability of the unvulcanized rubber composition did not deteriorate.
(Triangle | delta): Although roll contact | adherence generate | occur | produced, it was mild and the workability | operativity of the unvulcanized rubber composition hardly fell.
×: Roll adhesion occurred, and the workability of the unvulcanized rubber composition was greatly reduced.
(3) 90% vulcanization time [t _c (90)]
90% vulcanization of the unvulcanized rubber compositions obtained in Examples 1 to 7 and Comparative Examples 1 to 6 in accordance with the method of obtaining vulcanization characteristics using a vibration vulcanization tester of JIS K 6300-2: 2001 Time [t _c (90)] (min, 145 ° C.) was measured. Measure the vulcanization torque curve at 145 ° C ± 1 ° C using a CJR Clastometer as a measuring instrument, and add 90% of the time (min) required to reach 90% of the maximum value. Sulfuration time [t _c (90)] was used. The [t _c (90)] of the unvulcanized rubber composition of Comparative Example 2 was set to 100, and indexed by the following formula. The smaller the value of the 90% vulcanization time [t _c (90)] index, the faster the vulcanization rate.
Between 90% vulcanization time _{[t c (90)] [} t c (90)] index = {subjected試未vulcanized rubber composition [t _c (90)] / unvulcanized rubber composition of Comparative Example 2 } × 100

(4) Air permeability The rubber composition obtained by vulcanization obtained in Examples 1 to 7 and Comparative Examples 1 to 6 was measured according to JIS K 716-2: 2006 “Plastic Film and Sheet—Gas Permeability Test Method— The air permeability coefficient was measured at 23 ° C. ± 2 ° C. using an oxygen permeability measuring device (manufactured by Toyo Seiki Co., Ltd.) in accordance with “Part 2: Isobaric method”. The smaller the air permeability coefficient, the better the air permeation resistance (gas barrier property). From the obtained air permeability coefficient, the air permeability coefficient of Comparative Example 2 was set as 100 and indicated as an index. The smaller the index value, the smaller the air permeability coefficient and the better.
Air permeability index = {(Air permeability coefficient of test vulcanized rubber composition) / (Air permeability coefficient of vulcanized rubber composition of Comparative Example 2)} × 100

Examples 1-7 and Comparative Examples 1-6
Thirteen types of rubber compositions were prepared according to the formulation shown in Table 1.
These rubber compositions are kneaded using a Banbury mixer in two stages, the first stage of high temperature kneading (maximum temperature 140 ° C.) and the final stage of low temperature kneading (maximum temperature 100 ° C.) to obtain an unvulcanized rubber composition. It was. The rubber compositions of Examples 1 to 6 and Comparative Examples 1 to 6 were kneaded by adding all of the rubber component, clay, carbon black, process oil and stearic acid in the first stage. In the final stage of Examples 1 to 3, poly-p-dinitrosobenzene, a vulcanization accelerator, and sulfur were kneaded into the master batch obtained in the first stage of high-temperature kneading. In the final stage of Examples 4 to 6 and Comparative Example 6, poly-p-dinitrosobenzene, zinc oxide, vulcanization accelerator and sulfur were kneaded into the master batch obtained in the first stage of high temperature kneading. In the final stage of Comparative Examples 1 to 3, a vulcanization accelerator and sulfur were kneaded into the master batch obtained in the first stage of high-temperature kneading.
The rubber composition of Example 7 was kneaded by adding all of the rubber component, clay, poly-p-dinitrosobenzene, carbon black, zinc oxide, process oil and stearic acid in the first stage, and then in the final stage. The vulcanization accelerator and sulfur were kneaded into the master batch obtained in the first stage of high temperature kneading.
About the obtained unvulcanized rubber composition, green strength, roll adhesion, and 90% vulcanization time [t _c (90)] were measured.
Next, the unvulcanized rubber composition of the test piece obtained by calender molding was vulcanized at 160 ° C. for 50 minutes, and the air permeability of the obtained rubber composition of the test piece after vulcanization was evaluated. did. The results are shown in Table 1.

[Note] In Table 1,
* 1: Product name "JSR BROMOBUTYL 2255" manufactured by JSR Corporation
* 2: Asahi Carbon Co., Ltd., N660, trade name "Asahi # 55" ^{_{(N 2 SA: 26m 2 /}} g, DBP absorption amount: 87cm ³ / 100g)
* 3: Flat clay [J, M, manufactured by Huber, Inc. Trademark: “POLYFIL DL” (Aspect Ratio: 10), Average Particle Size: 1 μm] (The flat clay has a large aspect ratio of kaolin clay)
* 4: 25% poly-p-dinitrosobenzene manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name “Barnock DNB” was used. The content of poly-p-dinitrosobenzene is 4 parts by mass of “Varnock DNB”.
* 5: Paraffinic oil, Paraffinic oil manufactured by Idemitsu Kosan Co., Ltd., trade name “Diana Process Oil PW-90”
* 6: Normal zinc oxide [Zinc oxide, 2 types, manufactured by Hakusuitec Co., Ltd.]
* 7: Vulcanization accelerator DM, di-2-benzothiazolyl disulfide, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name “Noxeller DM-P”

[Evaluation results]
As shown in Table 1, it is clear that Example 1 blended with polydinitrosobenzene is better in all of green strength, roll adhesion, vulcanization time, and air permeability than Comparative Example 3. It became.
Furthermore, when the compounding quantity of polydinitrosobenzene was increased, it became clear from the result of Examples 1-3 that the effect became more favorable.

  The rubber composition of the present invention is useful as a rubber composition for inner liners of various tires, and is used for passenger cars, light trucks, light passenger cars, light trucks and large vehicles (for trucks, buses, construction vehicles, etc.). It is suitably used as an inner liner for various pneumatic tires.

Claims (9)

  A rubber composition comprising 80 to 160 parts by mass of a layered or platy clay mineral (B) and polydinitrosobenzene per 100 parts by mass of the rubber component (A).   Furthermore, the rubber composition of Claim 1 formed by mix | blending 15 mass parts or less of carbon black with respect to 100 mass parts of said rubber components (A).   Furthermore, the rubber composition of Claim 1 or 2 formed by mix | blending zinc oxide more than 15 mass parts with respect to 100 mass parts of said rubber components (A).   The rubber composition according to any one of claims 1 to 3, wherein 0.01 to 10 parts by mass of the polydinitrosobenzene is blended with 100 parts by mass of the rubber component (A).   The rubber composition according to any one of claims 1 to 4, wherein the rubber component (A) contains 80 to 100% by mass of a butyl rubber.   The rubber composition according to any one of claims 1 to 5, wherein the rubber composition is a rubber composition for a tire inner liner.   The method for producing a rubber composition according to any one of claims 1 to 6, wherein the rubber composition is kneaded in a plurality of stages, and at least one of the polydinitrosobenzenes in any stage other than the final stage of kneading. A method for producing a rubber composition, comprising adding a part.   The method for producing a rubber composition according to any one of claims 3 to 6, wherein the rubber composition is kneaded in a plurality of stages, and at least one of the polydinitrosobenzenes in any stage other than the final stage of kneading. And a method for producing a rubber composition, comprising adding at least part of the zinc oxide.   A pneumatic tire using the rubber composition according to any one of claims 1 to 6 or the rubber composition obtained by the production method according to claim 7 or 8 as an inner liner.

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