JP2009013197A - Rubber composition for inner liner and tire having inner liner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for an inner liner having improved mechanical strength (tensile strength, breaking strength and breaking elongation), low fuel consumption properties (rolling resistance characteristics and low heat build-up properties), abrasion resistance and reducing effects on air permeation amount and even processability and to provide a tire having the inner liner using the rubber composition. <P>SOLUTION: The rubber composition for the inner liner comprises a rubber component comprising 10-100 wt.% of a deproteinized natural rubber having ≤0.3 wt.% of the total nitrogen content as an index of proteins. The tire has the inner liner using the rubber composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber composition for an inner liner and a tire having an inner liner using the same.

  The inner liner is disposed inside the tire among the tire members, and is required to work to improve air retention by reducing the amount of air leakage (air permeation amount) from the inside of the pneumatic tire to the outside. . In recent years, tires have been reduced in heat and weight due to the strong social demand for lower fuel consumption of vehicles, and the inner liner has also been reduced in weight.

  Conventionally, there has been a problem that the amount of air permeation increases when the blending ratio of natural rubber is increased in order to improve the fuel efficiency of a vehicle. Therefore, the rubber composition for the inner liner aimed at weight reduction of the tire by formulating butyl rubber such as butyl rubber which does not easily transmit air to improve the air retention of the tire and making the rubber gauge thinner. Has been developed. However, butyl rubber is excellent in reducing the air permeation amount, but the hysteresis loss of the resulting rubber composition is large. The higher the butyl rubber content, the greater the heat generated by the tire and the fuel efficiency characteristics of the car. There was a problem that decreased.

  Therefore, an inner liner or carcass made of a composition containing a resin such as polyester melamine resin and acrylic resin and a scaly filler such as silica and aluminum is used for the purpose of suppressing cracking that occurs during tire running with a small amount of air permeation. A pneumatic tire is proposed (for example, see Patent Document 1).

  For the purpose of reducing the amount of air permeation, a pneumatic tire having an inner liner made of a rubber composition for an inner liner containing plate-like mica such as sericite has been proposed (for example, see Patent Document 2). .

  By the way, natural rubber has excellent raw rubber strength (green strength) compared with synthetic rubber, and is excellent in processability. In addition, vulcanized rubber is often used for large tires such as truck / bus tires because of its high mechanical strength and excellent wear resistance. However, in recent years, low-fuel consumption of large tires has been regarded as important from the viewpoint of environmental issues such as resource saving and stricter regulations on carbon dioxide emission control, and the wear resistance, which is an excellent characteristic of natural rubber, has been reduced. Without improvement, there is an urgent need to improve fuel efficiency. In view of these circumstances, a low fuel consumption performance is also required for an inner liner that greatly affects the fuel consumption performance of a tire.

  On the other hand, natural rubber is said to cause gelation due to entanglement of molecules due to non-rubber components such as proteins and lipids present in natural rubber. When gelation occurs, there is a drawback that the viscosity of the rubber increases and the processability deteriorates. In general, in order to improve the processability of natural rubber, a method of kneading with a kneading roll machine or a closed mixer and lowering the molecular weight is used. Since it cuts at random, it causes deterioration of fuel consumption characteristics. On the other hand, a method for removing a protein, which is one of the factors of gelation, has been proposed as a method for suppressing gelation.

  Therefore, in order to obtain a tire tread rubber composition excellent in fuel efficiency and processability without impairing mechanical properties, the rubber component has a weight average molecular weight of 1.4 million or more and a nitrogen content of 0.1 weight. % Or less, a rubber composition for tire treads containing a deproteinized natural rubber (see, for example, Patent Document 3) has been proposed.

JP 2004-345470 A JP-A-11-140234 JP 2005-47993 A

  The present invention is an inner with improved mechanical strength (tensile strength, breaking strength, elongation at break), low fuel consumption (rolling resistance characteristics, low heat generation), wear resistance, air permeation reduction effect, and workability. It is an object to provide a rubber composition for a liner and a tire having an inner liner using the rubber composition.

  The present invention relates to a rubber composition for an inner liner containing a rubber component containing 10 to 100% by weight of a deproteinized natural rubber having a total nitrogen content of 0.3% by weight or less as an index of protein.

  The total nitrogen content of the deproteinized natural rubber is preferably 0.1% by weight or less.

  The content of the deproteinized natural rubber in the rubber component is preferably 50 to 100% by weight.

  The weight average molecular weight of the deproteinized natural rubber is preferably 1.4 million to 2 million.

  In the rubber composition for an inner liner, the rubber component preferably contains natural rubber and / or butadiene rubber as a diene rubber.

  In the rubber composition for an inner liner, the rubber component preferably contains chlorobutyl rubber as a butyl rubber.

  The content of deproteinized natural rubber in the rubber component is 10 to 100% by weight, the content of natural rubber is 0 to 90% by weight, and the content of butadiene rubber and / or chlorobutyl rubber is 0 to 90% by weight. Preferably there is.

  The rubber composition for an inner liner preferably contains 5 to 150 parts by weight of a filler with respect to 100 parts by weight of the rubber component.

  In the rubber composition for an inner liner, the filler is preferably silica and / or carbon black.

In the rubber composition for an inner liner, the nitrogen adsorption specific surface area of silica is preferably 100 to 300 m ² / g.

In the rubber composition for an inner liner, the nitrogen adsorption specific surface area of carbon black is preferably 70 m ² / g or more, and the dibutyl phthalate oil absorption is preferably 70 ml / 100 g or more.

  The present invention also relates to a tire having an inner liner using the rubber composition for an inner liner.

  According to the present invention, by containing a predetermined amount of deproteinized natural rubber having a total nitrogen content of 0.3% by weight or less, mechanical strength (tensile strength, breaking strength, breaking elongation), low fuel consumption (rolling) Resistance composition, low heat generation), low fuel consumption (rolling resistance characteristics), wear resistance, air permeation reduction effect, and further improved processability and rubber composition for inner liner and inner liner using the same Tires can be provided.

  The rubber composition for an inner liner of the present invention contains a rubber component containing a predetermined deproteinized natural rubber (hereinafter sometimes referred to as DPNR).

  FIG. 1 is a partial cross-sectional view of a tire composed of the inner liner of the present invention.

  As shown in FIG. 1, the tire of the present invention can include components such as a sidewall 1, a clinch apex 2, a bead core 3, a bead 4, an inner liner 5, a belt 6, and a tread 7 that a passenger car tire has. . In FIG. 1, the inner liner 5 is disposed on the tire inner surface of members such as a tread 7, sidewalls 1, and beads 4 constituting the tire. The bead 4 is arranged inside the clinch apex 2 so as to extend radially outward from the bead core 3. The sidewalls 1 forming the tire skin are arranged so as to extend inward in the tire radial direction from both ends of the tread 7, and the clinch apex 2 is arranged at the inner ends of the respective sidewalls 1. The inner end of the tire in the radial direction can contact the metal rim 8.

  In the present invention, deproteinization which is contained in natural rubber (NR) in an amount of about 5 to 10% by weight, removes a protein causing gelation, and has a total nitrogen content of 0.3% by weight or less as a protein index. By blending natural rubber (DPNR) as a part of the rubber component, improvement in mechanical strength (tensile strength, breaking strength, breaking elongation), processability and fuel efficiency are improved. In addition, as a process which deproteinizes natural rubber, the conventionally well-known method described in Unexamined-Japanese-Patent No. 2005-47993 etc. is employable. In addition, as a NR to be deproteinized, a conventionally used grade such as RSS # 3 or TSR20 can be used.

  In the present invention, the total nitrogen content is used as an index of the protein content of the deproteinized natural rubber. The total nitrogen content of the deproteinized natural rubber is 0.3% by weight or less, preferably 0.1% by weight or less, more preferably 0.08% by weight or less because it does not cause gelation. The lower limit of the total nitrogen content of the deproteinized natural rubber is preferably low, and it is desirable not to contain nitrogen if possible. However, the lower limit is usually 0.01% by weight due to limitations such as the production method.

  The weight average molecular weight of the deproteinized natural rubber is preferably 1,400,000 or more, more preferably 1,800,000 or more from the viewpoint of high raw rubber strength, excellent tensile properties (breaking strength, elongation at break, etc.) and low heat build-up (reduction of tan δ). More preferred. The upper limit of the weight average molecular weight of the deproteinized natural rubber is not particularly limited, but is usually preferably 2 million or less from the viewpoint that the resulting rubber composition does not have too high a viscosity and is excellent in processability.

  In addition, the deproteinized natural rubber is a natural rubber with a reduced gel content, and the gel content of the deproteinized natural rubber measured as a toluene insoluble component can suppress an increase in the viscosity of the unvulcanized rubber and is excellent in processability. From the viewpoint, 10% by weight or less is preferable. In addition, the one where the gel content rate of deproteinized natural rubber is low is preferable, and it is desirable not to contain a gel part if possible.

  The content of the deproteinized natural rubber in the rubber component is 10% by weight or more, preferably 50% by weight or more. If the content of the deproteinized natural rubber is less than 10% by weight, the effect of improving the processability, wear resistance, rolling resistance characteristics and tensile properties by blending the deproteinized natural rubber is not preferable. Further, the upper limit of the content of the deproteinized natural rubber in the rubber component is not particularly limited and may be 100% by weight, but is preferably 80% by weight or less from the viewpoint of excellent raw rubber strength.

  In the present invention, when a rubber component other than DPNR is used as the diene rubber component, examples of the rubber component used in combination with DPNR include NR, butadiene rubber (BR), isoprene rubber (IR), and styrene butadiene rubber (SBR). ), Styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), etc., which are excellent in low air permeability (reduction effect of air permeation amount). From the viewpoint, NR and BR are preferable.

  In particular, it is preferable to use halogenated butyl rubber such as chlorobutyl rubber (Cl-IIR) and bromobutyl rubber (Br-IIR) and butyl rubber such as butyl rubber (IIR) as the rubber component used for the rubber composition for the inner liner. . Among these butyl rubbers, a halogenated butyl rubber is preferable because air and moisture permeability can be kept low.

  As NR, the grade used conventionally, such as RSS # 3 and TSR20, can be used similarly to NR used for DPNR.

  When NR is included, the content of NR in the rubber component is preferably from 0 to 90% by weight, more preferably from 10 to 90% by weight, and even more preferably from 20 to 80% by weight, from the viewpoint of excellent fracture characteristics.

  There is no restriction | limiting in particular as BR, BR150B, BR130B by Ube Industries, Inc. used conventionally can be used.

  When BR is included, the BR content in the rubber component is preferably 0 to 90% by weight, more preferably 10 to 90% by weight, and even more preferably 20 to 80% by weight, from the viewpoint of excellent processability.

  The halogenated butyl rubber is not particularly limited, and conventionally used chlorobutyl rubber (Cl-IIR) and bromobutyl rubber (Br-IIR) can be used, and HT manufactured by ExxonMobil Co., Ltd. is commercially available. -1068, Bayer's PolyBB 2040, and the like.

  When the halogenated butyl rubber is included, the content of the halogenated butyl rubber in the rubber component is preferably 0 to 90% by weight, more preferably 10 to 90% by weight, from the viewpoint of excellent low air permeability or air permeability. 20-80% by weight is even more preferred.

  The rubber composition for an inner liner of the present invention preferably contains a filler in addition to the rubber component containing DPNR.

  The filler is not particularly limited, and conventionally used carbon black and silica are well known. In addition to these, calcium carbonate, magnesium oxide, magnesium hydroxide, alumina, aluminum hydroxide, clay, talc and the like are also included. Among them, it is preferable to use carbon black because it is excellent in durability (reinforcing property), and silica is preferable because it is excellent in rolling resistance characteristics (low heat generation property).

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 m ² / g or more, and more preferably 80 m ² / g or more, because it is excellent in durability (reinforcing property). Further, the nitrogen adsorption specific surface area (N ₂ SA) of carbon black is the reason that in order to prevent the strength by poor dispersion decreases, preferably 250 meters ² / g or less, more preferably 230 m ² / g.

  The DBP (dibutyl phthalate) oil absorption amount of carbon black is preferably 70 ml / 100 g or more, more preferably 80 ml / 100 g or more, because it is excellent in durability (reinforcing property). The DBP oil absorption of carbon black is preferably 200 ml / 100 g or less, and more preferably 190 ml / 100 g or less.

  Specific examples of the carbon black include HAF, ISAF, SAF and the like, but are not particularly limited.

  When carbon black is blended as a filler, the blending amount of carbon black is preferably 5 to 150 parts by weight, preferably 10 to 140 parts by weight based on 100 parts by weight of the rubber component, from the viewpoint of excellent durability (reinforcing property). Part is more preferred.

The nitrogen adsorption specific surface area (N ₂ SA) of the silica, because of excellent durability (reinforcing), preferably at least ^{100m 2 / g, 110m 2 /} g or more is more preferable. Further, the nitrogen adsorption specific surface area (N ₂ SA) of carbon black is, for the reason that it is possible to prevent the heat generation is increased by the dispersion deteriorates, preferably 300 meters ² / g or less, more preferably 290 m ² / g .

  When silica is blended as a filler, the blending amount of silica is preferably 5 to 150 parts by weight with respect to 100 parts by weight of the rubber component from the viewpoint of excellent wet grip and rolling resistance characteristics (low heat build-up), and 10 to 140 parts. Part by weight is more preferred.

  In the present invention, when silica is used as the filler, it is preferable to contain a silane coupling agent. The silane coupling agent that can be suitably used in the present invention can be any silane coupling agent conventionally used in combination with silica. Specifically, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) Tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide Bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (3- Riethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide Bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxy Silylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolylte Sulfides such as rasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltrisulfide Mercapto series such as ethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, vinyl series such as vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltri Amino series such as methoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, γ Glycidoxy systems such as glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 3-nitropropyltrimethoxysilane, Nitro-based compounds such as 3-nitropropyltriethoxysilane, chloro-based compounds such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane and 2-chloroethyltriethoxysilane It is done. Bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, 3-mercaptopropyltrimethoxysilane, and the like are preferably used because of the effect of adding a coupling agent and cost. These silane coupling agents may be used alone or in combination of two or more.

  The blending amount of the silane coupling agent is preferably 0 to 20 parts by weight with respect to 100 parts by weight of silica, because a coupling effect can be obtained at an appropriate cost, and even better reinforcement and wear resistance can be achieved. 2 to 15 parts by weight is more preferable.

  The rubber composition for an inner liner of the present invention is a compounding agent conventionally used in the tire industry, such as oil, wax, anti-aging agent, in addition to the rubber component containing DPNR, filler and silane coupling agent. Vulcanizing agents such as stearic acid, zinc oxide and sulfur, vulcanization accelerators and the like can be appropriately blended.

  The rubber composition for an inner liner of the present invention is produced by a general method. That is, the rubber composition for an inner liner of the present invention can be produced by kneading the rubber component, if necessary, other compounding agents with a Banbury mixer, kneader, open roll, etc., and then vulcanizing. .

  Here, as shown in FIG. 1 which is a partial cross-sectional view of a tire constituted of the inner liner of the present invention, the inner liner 5 is a tire of members such as a tread 7, sidewalls 1, and beads 4 constituting the tire. It is a rubber part arranged on the inner surface, and has the role of suppressing cracks by following the effect of reducing the amount of air permeation and the rubber expansion and contraction movement during tire travel.

  The rubber composition for an inner liner of the present invention is used as an inner liner among tire members because it can improve processability, wear resistance, rolling resistance characteristics (low heat generation characteristics), and tensile characteristics. It is.

  The tire of the present invention is produced by a usual method using the rubber composition for an inner liner of the present invention. That is, if necessary, the rubber composition of the present invention blended with the above compounding agent is extruded in accordance with the shape of the inner liner of the tire at an unvulcanized stage, and molded on a tire molding machine by a normal method. By doing so, an unvulcanized tire is formed. The unvulcanized tire is heated and pressed in a vulcanizer to produce a tire.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Hereinafter, various commercially available chemicals used in Examples and Comparative Examples will be described.
Natural rubber (NR): RSS # 3
Butadiene rubber (BR): BR150B manufactured by Ube Industries, Ltd.
Chlorobutyl rubber (Cl-IIR): HT-1068 manufactured by ExxonMobil Corporation
DPNR (1): nitrogen content 0.034% (adjusted according to the preparation of the following deproteinized natural rubber)
DPNR (2): Nitrogen content 0.25% (adjusted according to the preparation of the following deproteinized natural rubber)
DPNR (3): nitrogen content 0.35% (adjusted according to the preparation of the following deproteinized natural rubber)
Carbon black (ISAF): N550 manufactured by Showa Cabot Co., Ltd. (N ₂ SA: 143 m ² / g, DBP oil absorption: 113 ml / 100 g)
Ultrasil VN3 manufactured by Degussa Japan Co., Ltd. (N ₂ SA: 210 m ² / g)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Oil: Diana Process PS32 manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Stearic acid: Zinc stearate oxide manufactured by Nippon Oil & Fats Co., Ltd .: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Kogyo Co., Ltd.
Vulcanization accelerator (2): Noxeller DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Deproteinized natural rubber was prepared by the following method and analyzed.

Deproteinization treatment of natural rubber (Preparation method of deproteinized natural rubber (DPNR (1)))
150 ml of high ammonia type natural rubber latex (solid content 60.2%) manufactured by Soctech (Malaysia) is diluted with 2 liters of distilled water so that the rubber solid content becomes 10%, and 0.12% sodium naphthenate. And the pH was adjusted to 9.2 by adding sodium dihydrogen phosphate. Subsequently, 7.8 g of deproteinase alkalase (Novo Nordisk Bio Industry Co., Ltd.) was dispersed in 100 ml of distilled water and added to the diluted natural rubber latex. After adjusting the pH of the latex to 9.2 again, it was maintained at 37 ° C. for 24 hours for deproteinization treatment. The anionic surfactant polyoxyethylene lauryl ether sulfate sodium (KP4401 manufactured by Kao Corporation) was added at a rate of 1% by weight to the latex that had been subjected to deproteinization treatment, and centrifuged at 10,000 rpm for 30 minutes. Separation was performed. After centrifugation, the creamy rubber component separated into the upper layer was taken out and further diluted with water to obtain a deproteinized natural rubber latex subjected to deproteinization treatment with a rubber solid content of 60%.

  The deproteinized natural rubber latex was cast on a glass plate, dried at room temperature, and then dried under reduced pressure to obtain a polymer. The obtained polymer was cast on a glass plate, dried at room temperature, and then dried under reduced pressure. After drying, extraction with a mixed solvent of acetone and 2-butanone (3: 1) was performed to remove impurities such as homopolymer, and DPNR (1) was obtained.

(Method for preparing deproteinized natural rubber (DPNR (2)))
Deproteinization natural rubber was prepared in the same manner as in Deproteinization natural rubber preparation method-1, except that 2.0 g of deproteinase alkalase (Novonordisk Bioindustry Co., Ltd.) was replaced with deproteinization natural rubber production method-1. Natural rubber latex was obtained.

  The deproteinized natural rubber latex was cast on a glass plate, dried at room temperature, and then dried under reduced pressure to obtain a polymer. The obtained polymer was cast on a glass plate, dried at room temperature, and then dried under reduced pressure. After drying, extraction with a mixed solvent of acetone and 2-butanone (3: 1) was performed to remove impurities such as homopolymer, and DPNR (2) was obtained.

(Method for preparing deproteinized natural rubber (DPNR (3)))
Deproteinization natural rubber was prepared in the same manner as in Deproteinization natural rubber preparation method-1, except that 0.1 g of deproteinase alkalase (Novonordisk Bioindustry Co., Ltd.) was used. Natural rubber latex was obtained.

  The deproteinized natural rubber latex was cast on a glass plate, dried at room temperature, and then dried under reduced pressure to obtain a polymer. The obtained polymer was cast on a glass plate, dried at room temperature, and then dried under reduced pressure. After drying, extraction with a mixed solvent of acetone and 2-butanone (3: 1) was performed to remove impurities such as homopolymer, and DPNR (3) was obtained.

(Method for preparing NR)
A commercially available high ammonia natural rubber latex (Hytex, manufactured by Nomura Trading Co., Ltd.) was cast on a glass plate, dried at room temperature, and then dried under reduced pressure to obtain a polymer. The obtained polymer was cast on a glass plate, dried at room temperature, and then dried under reduced pressure. After drying, extraction with a mixed solvent of acetone and 2-butanone (3: 1) was performed to remove impurities such as homopolymer, and NR was obtained.

(Nitrogen content)
The nitrogen content was measured by the Kjeldahl test method.

(Gel content)
In the present invention, the gel content in raw rubber means a value measured as a toluene insoluble matter. 70 mg of a sample obtained by cutting raw rubber into 1 mm × 1 mm was weighed, 35 ml of toluene was added thereto, and the mixture was allowed to stand in a cool dark place for 1 week. Subsequently, the gel was centrifuged to precipitate a gel component insoluble in toluene, and the soluble component in the supernatant was removed. Only the gel component was washed with methanol, dried, and the weight (mg) was measured. The gel content (%) was determined by the following formula.
Gel content (%) = (weight after drying) / (initial sample weight) × 100

(Molecular weight measurement)
The weight average molecular weight was determined by gel permeation chromatography (solvent: tetrahydrofuran).

  The results of analysis for NR and DPNR (1) to (3) are shown in Table 1.

Examples 1-4 and Comparative Examples 1-6
Using a 1.7 L Banbury mixer manufactured by Kobe Steel, various materials excluding sulfur and a vulcanization accelerator were kneaded at about 150 ° C. for 5 minutes to obtain a kneaded product. Thereafter, on a biaxial open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded for 5 minutes at about 80 ° C. to obtain an unvulcanized rubber composition. Furthermore, the rubber composition for inner liners of Examples 1 to 4 and Comparative Examples 1 to 6 was obtained by press vulcanizing the obtained unvulcanized rubber composition at 175 ° C. for 12 minutes under the condition of 20 kgf. And 225 / 55R17 passenger car tires were produced.

(Processing test)
It was measured at 130 ° C. in accordance with the Mooney viscosity (ML _{1 + 4} ) measurement method defined in JIS K6300. As the value of the Mooney viscosity (ML 1 + ₄₎ viscosity is small is low, excellent processability. Then, the processability index of the comparative example as a reference was set to 100, and the Mooney viscosity (ML _{1 + 4} ) of each formulation was displayed as an index by the following calculation formula. The larger the workability index, the lower the Mooney viscosity and the better the workability. In Examples 1-2 and Comparative Examples 1-2, the workability index of Comparative Example 1 was 100 (Table 2), and in Example 3 and Comparative Example 3, the workability index of Comparative Example 3 was 100 (Table 3). In Comparative Examples 4 to 5, the workability index of Comparative Example 4 was 100 (Table 4), and in Example 4 and Comparative Example 6, the workability index of Comparative Example 6 was 100 (Table 5).
(Processability index) =
(ML _{1 + 4 of} comparative example as reference) / (ML _{1 + 4 of} each formulation) × 100

(Tensile test)
Using a No. 3 dumbbell-shaped test piece made of the vulcanized rubber composition, a tensile test was conducted according to JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber-Determination of Tensile Properties”, and the strength at break ( TB (MPa)) and elongation at break (EB (%)) were measured. The greater the values of TB and EB, the greater the strength and the better. Then, the strength index at break and the elongation index at break of the comparative example as a reference were set to 100, and the strength at break (TB (MPa)) and the elongation at break (EB (%)) of each compound were indexed by the following formulas. displayed. The larger the strength index at break and the elongation index at break, the greater the strength and the better. In Examples 1-2 and Comparative Examples 1-2, the strength index at break and the elongation index at break of Comparative Example 1 were 100 (Table 2), and in Example 3 and Comparative Example 3, the breakage of Comparative Example 3 was The strength index and the elongation index at break were 100 (Table 3), and in Comparative Examples 4 to 5, the strength index at break and the elongation index at break were 100 (Table 4) in Comparative Example 4, and in Example 4 and Comparative Example 6, The strength index at break and the elongation index at break of Comparative Example 6 were set to 100 (Table 5).
(Strength index at break) =
(TB (MPa) of each formulation) / (TB (MPa) of a comparative example serving as a reference) × 100
(Elongation at break) =
(EB of each formulation (%)) / (EB of reference comparative example (%)) × 100

(Abrasion test)
The amount of lamborn wear was measured with a lambbone wear tester under the conditions of a load of 1.5 kgf, a temperature of 20 ° C., a slip rate of 20%, and a test time of 5 minutes. The smaller the amount of wear (loss), the better the wear resistance. Then, the volume loss of each formulation was calculated, and the abrasion resistance index of the comparative example as a reference was set to 100, and the wear amount (loss amount) of each formulation was displayed as an index by the following formula. A larger wear index indicates better wear resistance. In Examples 1 and 2 and Comparative Examples 1 and 2, the abrasion resistance index of Comparative Example 1 is 100 (Table 2). In Examples 3 and 3, the abrasion resistance index of Comparative Example 3 is 100 (Table 3). In Comparative Examples 4 to 5, the abrasion resistance index of Comparative Example 4 was 100 (Table 4), and in Example 4 and Comparative Example 6, the abrasion resistance index of Comparative Example 6 was 100 (Table 5).
(Abrasion resistance index) =
(Loss amount of reference comparative example) / (Loss amount of each formulation) × 100

(Rolling resistance test)
Using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho, tan δ was measured at 70 ° C. under conditions of an initial strain of 10%, a dynamic strain of 2%, and a vibration frequency of 10 Hz. The smaller tan δ is, the better the heat generation and rolling resistance are, and the better the fuel efficiency is. And the rolling resistance index of the comparative example used as a reference | standard was set to 100, and tan (delta) of each mixing | blending was displayed as an index | exponent by the following formula. The larger the rolling resistance index, the better the rolling resistance characteristics. In Examples 1 and 2 and Comparative Examples 1 and 2, the rolling resistance index of Comparative Example 1 is 100 (Table 2). In Examples 3 and 3, the rolling resistance index of Comparative Example 3 is 100 (Table 3). In Comparative Examples 4 to 5, the rolling resistance index of Comparative Example 4 was set to 100 (Table 4), and in Example 4 and Comparative Example 6, the rolling resistance index of Comparative Example 6 was set to 100 (Table 5).
(Rolling resistance index)
= (Tan δ of reference example for reference) / (tan δ of each formulation) × 100

(Air permeability test)
Air permeation was measured according to ASTM D-1434-75M method. The smaller the amount of air permeation, the better the air permeation resistance, which is desirable. Then, the air permeation resistance index of the reference comparative example was set to 100, and the air permeation amount of each formulation was displayed as an index by the following calculation formula. The larger the air permeation resistance index, the better the air permeation resistance index. In Examples 1 and 2 and Comparative Examples 1 and 2, the air permeability index of Comparative Example 1 is 100 (Table 2). In Examples 3 and 3, the air permeability index of Comparative Example 3 is 100 (Table 3), in Comparative Examples 4 to 5, the air permeability index of Comparative Example 4 is 100 (Table 4), and in Example 4 and Comparative Example 6, the air permeability index of Comparative Example 6 is 100 (Table 4). Table 5).
(Air permeability resistance index)
= (Air permeation amount of reference comparative example) / (Air permeation amount of each formulation) × 100

  The evaluation results are shown in Tables 2-5.

  From Table 2, Example 1 (0.034% by weight) and Example 2 (0.25% by weight) using DPNR having a nitrogen content of 0.3% by weight or less showed workability, rolling resistance, There is an improvement in performance in terms of wear and tensile properties. However, Comparative Example 1 (0.35% by weight) and Comparative Example 2 (0.5% by weight) using DPNR or NR having a nitrogen content exceeding 0.3% by weight show no improvement in performance.

  From Table 3 and Table 4, if the content of the deproteinized natural rubber in the rubber component is 10% by weight or more (Example 3), the effect by addition is seen, but in less than 10% by weight (Comparative Example 5) The effect is not seen.

It is a fragmentary sectional view of the tire constituted from the inner liner of the present invention.

Explanation of symbols

1 side wall 2 clinch apex 3 bead core 4 bead 5 inner liner 6 belt 7 tread 8 rim

Claims (12)

A rubber composition for an inner liner containing a rubber component containing 10 to 100% by weight of a deproteinized natural rubber having a total nitrogen content of 0.3% by weight or less as an index of protein. The rubber composition for an inner liner according to claim 1, wherein the total nitrogen content of the deproteinized natural rubber is 0.1% by weight or less. The rubber composition for an inner liner according to any one of claims 1 to 2, wherein the content of the deproteinized natural rubber in the rubber component is 50 to 100% by weight. The rubber composition for an inner liner according to any one of claims 1 to 3, wherein the deproteinized natural rubber has a weight average molecular weight of 1,400,000 to 2,000,000. The rubber composition for an inner liner according to any one of claims 1 to 4, wherein the rubber component contains natural rubber and / or butadiene rubber as a diene rubber. The rubber composition for an inner liner according to any one of claims 1 to 5, wherein the rubber component contains chlorobutyl rubber as a butyl rubber. The content of deproteinized natural rubber in the rubber component is 10 to 100% by weight, the content of natural rubber is 0 to 90% by weight, and the content of butadiene rubber and / or chlorobutyl rubber is 0 to 90% by weight. The rubber composition for an inner liner according to any one of claims 1 to 6. For 100 parts by weight of rubber component,
The rubber composition for an inner liner according to any one of claims 1 to 7, comprising 5 to 150 parts by weight of a filler. The rubber composition for an inner liner according to claim 8, wherein the filler is silica and / or carbon black. The rubber composition for an inner liner according to claim 9, wherein the silica has a nitrogen adsorption specific surface area of 100 to 300 m ² / g. 10. The rubber composition for an inner liner according to claim 9, wherein the nitrogen adsorption specific surface area of carbon black is 70 m ² / g or more and the dibutyl phthalate oil absorption is 70 ml / 100 g or more. The tire which has an inner liner using the rubber composition for inner liners in any one of Claims 1-11.

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