JP5337355B2 - Rubber composition for insulation and tire having insulation using the same - Google Patents

Description

  The present invention relates to a rubber composition for insulation and a tire having insulation using the rubber composition.

  Conventionally, in order to reduce the rolling resistance of a tire, a technique using a low exothermic composition in an insulation portion has been used. In order to further reduce the heat generation of fuel-efficient installations, it is conceivable to reduce carbon black or increase the particle size of carbon black.

  However, when the carbon black is reduced or carbon black having a large particle size is used, the strength of the rubber composition is lowered. This decrease in strength is not preferable because it causes a decrease in tire durability and a decrease in lateral rigidity.

  In general, in rubber compositions used for insulation, natural rubber, butadiene rubber, styrene butadiene rubber, or the like is used as the rubber component, and natural rubber is blended as an essential component. In this natural rubber, there are about 5 to 10% by weight of non-rubber components such as proteins and lipids, and these non-rubber components, especially proteins, are said to cause entanglement of molecular chains, and gelation is caused. This causes a cause of the occurrence, and when gelation occurs, 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.

  Therefore, a method for removing a protein, which is one of the factors of gelation, is known, and it has been proposed to use the obtained deproteinized natural rubber as a rubber for a tire component (Patent Document). 1).

Japanese Patent No. 3294901

  An object of the present invention is to provide a rubber composition for installation that can improve processability, fuel efficiency and rubber strength, and a tire having an installation using the rubber composition.

  The present invention relates to a rubber composition for insulation containing a rubber component including 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 2 to 100% by weight.

  The content of the deproteinized natural rubber in the rubber component is preferably 2 to 60% by weight, and the content of the natural rubber is preferably 40 to 98% by weight.

  The rubber composition for insulation preferably contains 30 to 70 parts by weight of a filler with respect to 100 parts by weight of the rubber component.

The filler is preferably carbon black having a nitrogen adsorption specific surface area of 25 to 40 m ² / g.

  The rubber composition for insulation preferably contains 5 to 20 parts by weight of oil with respect to 100 parts by weight of the rubber component.

  It is preferable that the rubber composition for insulation contains 1.0 to 4.0 parts by weight of wax with respect to 100 parts by weight of the rubber component.

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

  According to the present invention, by including a specific deproteinized natural rubber, a rubber composition for installation that can improve processability, fuel efficiency, rubber strength, and steering stability, and an installation using the rubber composition. A tire having the same can be provided.

  The rubber composition for insulation of the present invention contains a rubber component containing a specific deproteinized natural rubber (hereinafter sometimes referred to as DPNR).

  In the present invention, a DPNR 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 as a part of the rubber component, processability, low fuel consumption, rubber strength and handling stability are improved. As the treatment for deproteinizing NR, conventionally known methods described in JP-A-6-329838, JP-A-2005-47993 and the like can be employed. 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 0.05% by weight or less. When the total nitrogen content exceeds 0.3% by weight, it causes gelation and the processability is deteriorated. The lower limit of the total nitrogen content of the deproteinized natural rubber is preferably low, and it is desirable that nitrogen is not contained if possible. However, the lower limit is usually 0.03% by weight due to limitations such as the production method.

  The weight average molecular weight of DPNR is preferably 1.4 million or more from the viewpoint of high raw rubber strength and excellent wear resistance. The upper limit of the weight average molecular weight of DPNR is not particularly limited, but is usually 1.7 million.

  Further, DPNR is NR with reduced gel content, and the gel content of DPNR measured as toluene insoluble is 10% by weight or less from the viewpoint of suppressing the increase in the viscosity of unvulcanized rubber and being excellent in processability. Is preferred. The gel content of DPNR is preferably low, and it is desirable that the gel content is not contained if possible. However, the lower limit is usually 2.0% by weight because of limitations such as the production method.

  The content of DPNR in the rubber component is preferably 2% by weight or more, more preferably 5% by weight or more, and still more preferably 10% by weight or more. If the DPNR content is in the above range, it is preferable because the low rolling resistance performance and the steering stability can be improved in a balanced manner by blending DPNR. The upper limit of the DPNR content in the rubber component is not particularly limited and may be 100% by weight, but is preferably 80% by weight or less and more preferably 60% by weight or less from the viewpoint of cost reduction.

  In the present invention, when a rubber component other than DPNR is used as the rubber component, examples of the rubber component used in combination with DPNR include NR, isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), Styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), etc. are listed, but from the point of excellent workability, fatigue resistance and flex resistance, NR Is preferred.

  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 40 to 98% by weight, more preferably 45 to 90% by weight, from the viewpoint of excellent processability and fatigue resistance.

  In addition, when DPNR and NR are used together as the rubber component, the DPNR content in the rubber component is preferably 2 to 60% by weight, and the NR content in the rubber component is preferably 40 to 98% by weight.

  The rubber composition for insulation of the present invention preferably further contains a filler.

  As the filler, carbon black is well known, and even if silica is used instead of carbon black, the same effect can be obtained as a rubber composition for insulation. In addition to these, calcium carbonate, magnesium oxide, magnesium hydroxide, alumina, aluminum hydroxide, clay, talc and the like are also included. Among these, carbon black and silica are preferable from the viewpoint of excellent balance between reinforcement and workability.

When carbon black is used as a filler, the nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 25 to 40 m ² / g from the viewpoint of excellent reinforcement, workability, and fatigue resistance.

  The blending amount of the filler is preferably 30 to 70 parts by weight with respect to 100 parts by weight of the rubber component from the viewpoint of excellent reinforcement, workability, and fatigue resistance.

  In this invention, when using a silica as a 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 rubber composition for insulation of the present invention preferably further contains oil.

  Examples of the oil include process oil, vegetable oil and fat, animal fat and the like.

  Examples of the process oil include paraffinic process oil, naphthenic process oil, and aromatic process oil.

  Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, sesame oil, olive oil, sunflower oil , Palm kernel oil, coconut oil, jojoba oil, macadamia nut oil, safflower oil, tung oil and the like.

  Examples of animal fats include oleyl alcohol, fish oil, and beef tallow.

  Among these, process oil is preferable and aroma oil is more preferable because of a high supply amount and low cost.

  The blending amount of the oil is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the rubber component from the viewpoint of excellent processability.

  The rubber composition for insulation of the present invention preferably further contains a wax.

  Examples of the wax include petroleum waxes such as paraffin wax, and vegetable waxes such as carnauba wax, rice wax, candelilla wax, Japan wax, urushi wax, sugar cane wax, and palm wax. Of these, petroleum waxes are preferred because they are supplied in a high amount and have excellent compatibility with rubber.

  The blending amount of the wax is preferably 1.0 to 4.0 parts by weight with respect to 100 parts by weight of the rubber component in consideration of blooming due to precipitation.

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

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

  The rubber composition for insulation according to the present invention is used as an installation among tire members because it contributes greatly to the heat generation and steering stability of the tire.

  Hereinafter, with reference to the drawings, the installation in a tire having an installation using the rubber composition for installation of the present invention will be described.

  FIG. 1 is a partial cross-sectional view of a tire showing a structure having insulation using the rubber composition for insulation of the present invention. As shown in FIG. 1, the installation 6 includes a tread 1, a sidewall 2, a carcass 3 disposed inside the tread 1 and the sidewall 2, and an outside of the carcass 3 inside the tread 1. In the tire having the inner liner 5 disposed inside the breaker 4 and the carcass 3, it is a rubber layer disposed inside the carcass 3 and outside the inner liner 5. , Has a role to ensure flex resistance.

  The tire of the present invention is produced by a usual method using the rubber composition for insulation of the present invention. That is, if necessary, the rubber composition for insulation of the present invention blended with the above-mentioned compounding agent is extruded in accordance with the shape of the tire insulation at an unvulcanized stage, and is used on a tire molding machine. An unvulcanized tire is formed by molding by the method. 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
Carbon Black: Show Black N660 (N ₂ SA: 35 m ² / g) manufactured by Cabot Japan
Silica: Ultrasil VN3 manufactured by Degussa
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Process oil: JOMO process X140 manufactured by Japan Energy Co., Ltd.
Wax: Sannoc Wax anti-aging agent manufactured by Ouchi Shinsei Chemical Industry Co., Ltd .: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-product manufactured by Ouchi New Chemical Co., Ltd.) Phenylenediamine)
Stearic acid: Zinc stearate oxide manufactured by Nippon Oil & Fats Co., Ltd .: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Chemical Industry Co., Ltd.
Vulcanization accelerator (2): Noxeller D (N, N'-diphenyl guanidine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

Preparation Example 1: Preparation of Deproteinized Natural Rubber (1) (DPNR (1)) 150 ml of high ammonia type natural rubber latex (solid content 60.2%) manufactured by Softech Co., Ltd., Malaysia has a rubber solid content of 10%. The mixture was diluted with 2 L of distilled water and stabilized with 0.12% sodium naphthenate, and sodium dihydrogen phosphate was added to adjust the pH to 9.2. Subsequently, 7.8 g of deproteinase alkalase (manufactured by Novo Disc 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 Co., Ltd.) is added to the latex that has been deproteinized at a rate of 1% by weight, and centrifuged at 10,000 rpm for 30 minutes. I did it. 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 having 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 and a commercially available high ammonia natural rubber latex (Hytex made by Nomura Trading Co., Ltd.) were 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 homopolymers, and deproteinized natural rubber (1) (DPNR (1)) was obtained.

Preparation Example 2: Preparation of deproteinized natural rubber (2) (DPNR (2)) Deproteinized natural rubber (2) (DPNR (2) was prepared in the same manner as in Preparation Example 1, except that 2.0 g of deproteinase alcalase was added. )).

Preparation Example 3 Preparation of Deproteinized Natural Rubber (3) (DPNR (3)) Similar to Preparation Example 1 except that 0.1 g of deproteinase alkalase was added, deproteinized natural rubber (3) (DPNR (3) )).

(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

(Weight average molecular weight)
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 1-7 and Comparative Examples 1-5
Using a 1.7 L Banbury mixer manufactured by Kobe Steel, various materials excluding sulfur and a vulcanization accelerator were kneaded at 160 ° C. for 4 minutes to obtain a kneaded product. Thereafter, on an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded material and kneaded for 2 minutes at 100 ° C. to obtain an unvulcanized rubber composition. Furthermore, the rubber composition for insulation of Examples 1-7 and Comparative Examples 1-5 was obtained by press-curing the obtained unvulcanized rubber composition for 30 minutes on 150 degreeC conditions. In the following characteristic evaluation, Comparative Example 1 was used as the reference formulation in Examples 1 to 5 and Comparative Examples 1 to 3, and Comparative Example 4 was used as Examples 6 to 7 and Comparative Examples 4 to 5.

(Mooney viscosity)
According to JIS K 6300 “Testing method for unvulcanized rubber”, a small rotor is rotated at a temperature of 130 ° C. heated by preheating for 1 minute using a Mooney viscosity tester manufactured by Shimadzu Corporation. The Mooney viscosity of the unvulcanized rubber composition after 4 minutes was measured. The Mooney viscosity index of the reference blend was set to 100, and the Mooney viscosity of each blend was displayed as an index according to the following calculation formula. In addition, it shows that it is easy to process and the workability is excellent, so that the value of Mooney viscosity index is large.
(Mooney Viscosity Index) = (Mooney Viscosity of Reference Formula)
÷ (Mooney viscosity of each formulation) x 100

(Viscoelasticity test)
Using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho, tan δ and E * at 70 ° C. were measured under conditions of an initial strain of 10%, a dynamic strain of 2%, and a vibration frequency of 10 Hz. Then, the rolling resistance index and the rubber strength index of the reference blend were set to 100, and tan δ and E * of each blend were displayed as indices according to the following calculation formulas. In addition, it shows that it is excellent in low-fuel-consumption property, so that a rolling resistance index is large, and it shows that it is excellent in rubber strength, so that a rubber strength index is large.
(Rolling resistance index) = (tan δ of Comparative Example 1) ÷ (tan δ of each formulation) × 100
(Rubber Strength Index) = (E * of each compound) ÷ (E * of Comparative Example 1) × 100

(Maneuvering stability)
The unvulcanized rubber composition was molded into an insulation shape and bonded together with other tire members to form an unvulcanized tire and vulcanized to produce a 195 / 65R15 size tire.

  The manufactured tire was mounted on a 2000cc class front-wheel drive vehicle (FF vehicle), and the test driver evaluated the steering stability during steering. Evaluation was made with a reference blend of 6 points, and was evaluated in increments of 0.5. The higher the score, the better the steering stability.

  The said evaluation result is shown to Tables 2-4.

It is a fragmentary sectional view of a tire which shows a structure which has insulation using a rubber composition for insulation of the present invention.

Explanation of symbols

1 Tread 2 Side Wall 3 Carcass 4 Breaker 5 Inner Liner 6 Installation

Claims (7)

A rubber composition for insulation containing a rubber component including a deproteinized natural rubber having a total nitrogen content of 0.3% by weight or less as an index of protein,
A rubber composition for insulation wherein the content of deproteinized natural rubber in the rubber component is 2 to 60% by weight and the content of natural rubber is 40 to 98% by weight . The rubber composition for insulation according to claim 1, wherein the total nitrogen content of the deproteinized natural rubber is 0.1% by weight or less. For 100 parts by weight of rubber component,
The rubber composition for insulation according to any one of claims 1 to 2 , comprising 30 to 70 parts by weight of a filler. The rubber composition for insulation according to claim 3 , wherein the filler is carbon black having a nitrogen adsorption specific surface area of 25 to 40 m ² / g. For 100 parts by weight of rubber component,
The rubber composition for insulation according to any one of claims 1 to 4 , comprising 5 to 20 parts by weight of oil. For 100 parts by weight of rubber component,
The rubber composition for insulation according to any one of claims 1 to 5 , comprising 1.0 to 4.0 parts by weight of a wax. A tire having an insulation using the rubber composition for insulation according to any one of claims 1 to 6 .

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