阅读说明：本技术 硫化橡胶组合物的制造方法 (Method for producing vulcanized rubber composition ) 是由 角田克彦 于 2019-02-21 设计创作，主要内容包括：本发明提供一种硫化橡胶组合物的制造方法,所述硫化橡胶组合物包括含有聚异戊二烯橡胶的橡胶组分和间规1,2-聚丁二烯。所述制造方法增加硫化橡胶组合物的耐龟裂生长性并且特征在于：将间规1,2-聚丁二烯和聚异戊二烯橡胶在比间规1,2-聚丁二烯的熔点高10～100℃的温度下混炼,并且将所得的未硫化橡胶组合物在不大于间规1,2-聚丁二烯的熔点±15℃的温度下硫化。(The present invention provides a method for producing a vulcanized rubber composition comprising a rubber component containing a polyisoprene rubber and a syndiotactic 1, 2-polybutadiene. The manufacturing method increases the crack growth resistance of the vulcanized rubber composition and is characterized in that: syndiotactic 1, 2-polybutadiene and polyisoprene rubber are kneaded at a temperature of 10 to 100 ℃ higher than the melting point of syndiotactic 1, 2-polybutadiene, and the resulting unvulcanized rubber composition is vulcanized at a temperature of not more than the melting point of syndiotactic 1, 2-polybutadiene +/-15 ℃.)

1. A process for producing a vulcanized rubber composition comprising a rubber component comprising a polyisoprene rubber and a syndiotactic 1, 2-polybutadiene, wherein

The syndiotactic 1, 2-polybutadiene and the polyisoprene rubber are kneaded at a temperature of 10 to 100 ℃ higher than the melting point of the syndiotactic 1, 2-polybutadiene, and the resulting unvulcanized rubber composition is vulcanized at a temperature falling within a range of ± 15 ℃ of the melting point of the syndiotactic 1, 2-polybutadiene.

2. The process for producing a vulcanized rubber composition according to claim 1, wherein the melting point of the syndiotactic 1, 2-polybutadiene is 100 to 180 ℃.

3. The method for producing a vulcanized rubber composition according to claim 1 or 2, wherein the syndiotactic 1, 2-polybutadiene is included in an amount of 2 to 50 parts by mass with respect to 100 parts by mass of the rubber component containing a polyisoprene rubber.

4. The method for producing a vulcanized rubber composition according to any one of claims 1 to 3, wherein the polyisoprene rubber is a natural rubber.

5. The method for producing a vulcanized rubber composition according to any one of claims 1 to 4, wherein the vulcanized rubber composition further comprises a filler.

6. A vulcanized rubber composition produced by the production method according to any one of claims 1 to 5.

7. A tire using the vulcanized rubber composition according to claim 6.

8. A rubber product selected from the group consisting of a conveyor belt, a vibration-proof rubber, a vibration-isolating rubber, a rubber crawler belt, a hose and a fender product, said rubber product being produced using the vulcanized rubber composition according to claim 6.

Technical Field

The present invention relates to a method for producing a vulcanized rubber composition comprising a rubber component containing a polyisoprene rubber and a syndiotactic 1, 2-polybutadiene.

Background

In general, a vulcanized rubber composition used for producing rubber products such as tires, conveyor belts, vibration-proof rubbers, and vibration-isolating rubbers is required to be highly durable. However, diene rubbers such as Butadiene Rubber (BR) and styrene-butadiene rubber (SBR) which have hitherto been commonly used in the rubber industry are insufficient in durability against cracking under high strain input, i.e., resistance to crack growth. Under such circumstances, various rubber components and rubber compositions are being developed.

As a means for improving the crack growth resistance, a method of mixing a polybutadiene rubber containing syndiotactic 1, 2-polybutadiene (hereinafter may be abbreviated as SPB) in a rubber composition is known (for example, see PTL 1). However, the crack growth resistance is not sufficient, and further improvement is desired.

High-strength gels are developed by semi-interpenetrating network structure hydrogels or interpenetrating network structure hydrogels, that is, double network gels produced by introducing a second monomer component into a network structure formed by polymerizing and crosslinking a first monomer component, followed by polymerizing and optionally crosslinking a second monomer component, wherein 10 mol% or more of the first monomer component is a charged unsaturated monomer, 60 mol% or more of the second monomer component is an electrically neutral unsaturated monomer, the molar ratio of the amount of the first monomer component to the amount of the second monomer component is 1/2 to 1/100, and in the case of polymerization and crosslinking of the second monomer component, the degree of crosslinking thereof is set to be smaller than that in the case of polymerization and crosslinking of the first monomer component (for example, see PTL 2).

Reference list

Patent document

PTL 1：JP 8-85303 A

PTL 2：WO2003/093337

Disclosure of Invention

Problems to be solved by the invention

The object of the present invention is to improve the crack growth resistance of a vulcanized rubber composition.

Means for solving the problems

The present inventors have diligently studied for the purpose of solving the above problems, and as a result, have conceived the following technical ideas: by applying the concept of the double network to the vulcanized rubber composition, the crack growth resistance of the vulcanized rubber composition can be greatly improved, and the present invention has been completed.

The present invention is as follows.

[1] A method for producing a vulcanized rubber composition comprising a rubber component containing a polyisoprene rubber and a syndiotactic 1, 2-polybutadiene, wherein the syndiotactic 1, 2-polybutadiene and the polyisoprene rubber are kneaded at a temperature of 10 to 100 ℃ higher than the melting point of the syndiotactic 1, 2-polybutadiene, and the resulting unvulcanized rubber composition is vulcanized at a temperature falling within a range of ± 15 ℃ of the melting point of the syndiotactic 1, 2-polybutadiene.

[2] The process for producing a vulcanized rubber composition according to [1], wherein the syndiotactic 1, 2-polybutadiene has a melting point of 100 to 180 ℃.

[3] The method for producing a vulcanized rubber composition according to [1] or [2], wherein the syndiotactic 1, 2-polybutadiene is included in an amount of 2 to 50 parts by mass with respect to 100 parts by mass of the rubber component containing a polyisoprene rubber.

[4] The method for producing a vulcanized rubber composition according to any one of [1] to [3], wherein the polyisoprene rubber is a natural rubber.

[5] The method for producing a vulcanized rubber composition according to any one of [1] to [4], wherein the vulcanized rubber composition further comprises a filler.

[6] A vulcanized rubber composition produced by the production method according to any one of [1] to [5 ].

[7] A tire using the vulcanized rubber composition according to [6 ].

[8] A rubber product selected from the group consisting of a conveyor belt, a vibration-proof rubber, a vibration-isolating rubber, a rubber crawler, a belt, a hose and a fender product (fender), which uses the vulcanized rubber composition according to [6 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the crack growth resistance of the vulcanized rubber composition can be greatly improved.

Detailed Description

The present invention is a method for producing a vulcanized rubber composition comprising a rubber component containing a polyisoprene rubber and a syndiotactic 1, 2-polybutadiene, wherein the syndiotactic 1, 2-polybutadiene and the polyisoprene rubber are kneaded at a temperature of 10 to 100 ℃ higher than the melting point of the syndiotactic 1, 2-polybutadiene, and the resulting unvulcanized rubber composition is vulcanized at a temperature falling within a range of ± 15 ℃ from the melting point of the syndiotactic 1, 2-polybutadiene.

In the present invention, the melting point is measured according to the following method: a sample of syndiotactic 1, 2-polybutadiene was placed in a Differential Scanning Calorimetry (DSC) apparatus and heated at a heating rate of 10 deg.C/min, where the melting peak temperature of the DSC curve was referred to as the melting point of the sample.

[ method for producing vulcanized rubber composition ]

In the method for producing the vulcanized rubber composition of the present invention, the temperature at the time of kneading the syndiotactic 1, 2-polybutadiene and the polyisoprene rubber (in the master batch kneading stage) is defined as follows: the kneading temperature is 10 to 100 ℃, preferably 12 to 50 ℃ higher than the melting point of the syndiotactic 1, 2-polybutadiene so that the syndiotactic 1, 2-polybutadiene is completely compatible with the polyisoprene rubber, and then the unvulcanized rubber composition obtained is vulcanized in the vicinity of the melting point of the syndiotactic 1, 2-polybutadiene so that the syndiotactic 1, 2-polybutadiene is half-phase-dissolved in the polyisoprene rubber and is thereby fixed as a network in the polyisoprene, and therefore, a double network is formed in the vulcanized rubber composition, thereby obtaining a high-strength rubber composition having significantly improved resistance to the growth of tortoise shells. The master batch will be described hereinafter.

The dual network of the present invention is of the following structure: syndiotactic 1, 2-polybutadiene forms a three-dimensional network structure in the polyisoprene rubber matrix, wherein the syndiotactic 1, 2-polybutadiene network first plays a role in taking stress in achieving effective energy dissipation, thereby exhibiting an improvement in the resistance to growth of fissures.

In the method for producing the vulcanized rubber composition of the present invention, when the temperature at the time of kneading the syndiotactic 1, 2-polybutadiene and the polyisoprene rubber (at the time of masterbatch kneading) is not higher than 10 ℃ higher than the melting point of the syndiotactic 1, 2-polybutadiene, it will be difficult to completely dissolve the syndiotactic 1, 2-polybutadiene in the polyisoprene rubber, and if so, even when the resulting composition is vulcanized at a temperature falling within the range of the melting point. + -. 15 ℃, a good network structure of the semi-compatible syndiotactic 1, 2-polybutadiene will not be formed.

On the other hand, in the method for producing the vulcanized rubber composition of the present invention, when the temperature at the time of kneading the syndiotactic 1, 2-polybutadiene and the polyisoprene rubber (in the master batch kneading stage) exceeds a temperature of 100 ℃ higher than the melting point of the syndiotactic 1, 2-polybutadiene, the polyisoprene rubber and/or the syndiotactic 1, 2-polybutadiene are thermally deteriorated, and finally, in such a case, the crack growth resistance is hardly improved.

In the method for producing the vulcanized rubber composition of the present invention, a mixer such as a Banbury mixer, a roll or an internal mixer is preferably used.

Regarding the vulcanization temperature of the vulcanized rubber composition of the present invention, the unvulcanized rubber composition needs to be vulcanized at a temperature falling within a range of. + -. 15 ℃ for the melting point of syndiotactic 1, 2-polybutadiene, preferably within a range of. + -. 13 ℃ for the melting point of syndiotactic 1, 2-polybutadiene.

When the vulcanization temperature of the vulcanized rubber composition of the present invention is higher than the "melting point +15 ℃ of syndiotactic 1, 2-polybutadiene", the crystals of syndiotactic 1, 2-polybutadiene may be re-dissolved in the polyisoprene rubber so that the polyisoprene rubber and the syndiotactic 1, 2-polybutadiene may be in an amorphous dispersed state, and thus the network of syndiotactic 1, 2-polybutadiene may be difficult to form.

On the other hand, when the vulcanization temperature of the vulcanized rubber composition of the invention is lower than the "melting point-15 ℃ of syndiotactic 1, 2-polybutadiene, the syndiotactic 1, 2-polybutadiene in the polyisoprene rubber may be in a crystalline state, and therefore the network of the syndiotactic 1, 2-polybutadiene may be difficult to form.

The temperature at the time of kneading in the method for producing a vulcanized rubber composition of the present invention means the temperature of the master batch of the rubber composition at the time of discharging the master batch out of the kneading apparatus in the present invention, and means the internal temperature of the master batch measured with a temperature sensor or the like immediately after discharging out of the kneading apparatus. However, in the case where the kneading apparatus employed is equipped with a temperature measuring means for measuring the temperature of the rubber composition in the apparatus, the temperature of the master batch at the time of discharge can be measured. Here, the masterbatch means a rubber composition produced in a stage of mixing the rubber component and the syndiotactic 1, 2-polybutadiene in a mixing stage in which a vulcanizing agent and a vulcanization accelerator have not been mixed.

The temperature at the time of vulcanization in the production method of the vulcanized rubber composition of the present invention means a maximum temperature (generally, a preset temperature of a vulcanization apparatus used) during progress of vulcanization after vulcanization is started to the end thereof.

The "vulcanization" mentioned in the present invention is not limited to sulfur crosslinking but includes non-sulfur crosslinking such as peroxide crosslinking.

[ rubber component ]

The rubber component in the vulcanized rubber composition of the present invention comprises a polyisoprene rubber. The polyisoprene rubber is one or more selected from natural rubber and synthetic polyisoprene rubber, and natural rubber is preferable from the viewpoint of improving the fracture resistance (crack growth resistance).

Preferably, the rubber component contains a polyisoprene rubber in an amount of 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, further more preferably 80% by mass or more, and particularly preferably, the rubber component is 100% by mass of a polyisoprene rubber.

The rubber component may contain any other rubber, as required, in addition to the polyisoprene rubber, preferably, a conjugated diene rubber other than the polyisoprene rubber therein.

The conjugated diene rubber other than the polyisoprene rubber is preferably at least one diene rubber selected from the group consisting of styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (e.g., Cl-IIR, BR-IIR), ethylene-propylene-diene terpolymer (EPDM), ethylene-butadiene copolymer rubber and propylene-butadiene copolymer rubber. One or two or more of the polyisoprene rubbers may be used alone or as a blend thereof.

The rubber component may contain a non-diene rubber within a range not to impair the advantageous effects of the present invention.

[ syndiotactic 1, 2-polybutadiene ]

The melting point of the syndiotactic 1, 2-polybutadiene in the present invention is preferably 100 to 180 ℃, more preferably 110 to 180 ℃, and even more preferably 115 to 180 ℃.

When the melting point of the syndiotactic 1, 2-polybutadiene is 100 ℃ or more, the vulcanization temperature of the rubber composition is hardly higher than a temperature falling within the range of. + -. 15 ℃ from the melting point of the syndiotactic 1, 2-polybutadiene, so that the polyisoprene rubber and the syndiotactic 1, 2-polybutadiene may be in an amorphous dispersed state, and therefore a network of the syndiotactic 1, 2-polybutadiene may be easily formed.

On the other hand, when the melting point of the syndiotactic 1, 2-polybutadiene is 180 ℃ or less, rubber scorch (rubber deterioration, molecular breakage, gel formation) does not occur and rubber properties are not reduced at the time of kneading the polyisoprene rubber. Further, the vulcanization temperature of the rubber composition is almost not lower than a temperature falling within the range of the melting point of syndiotactic 1, 2-polybutadiene. + -. 15 ℃ so that the syndiotactic 1, 2-polybutadiene in the polyisoprene rubber may be difficult to be in a crystalline state, and therefore a network of syndiotactic 1, 2-polybutadiene may be easily formed.

The syndiotactic 1, 2-polybutadiene in the present invention is prepared by polymerizing 1, 3-butadiene monomer in an organic solvent containing an aliphatic solvent using an iron-based catalyst composition or a cobalt-based catalyst composition, and may be prepared, for example, according to the polymerization methods described in JP 2000-119325A, JP 2000-119326A, JP 2004-528410A, JP 2005-518467A, JP 2005-527641A, JP 2009-108330A, JP 7-25212A, JP 6-306207A, JP 6-199103A, JP 6-92108A and JP 6-87975A.

Examples of iron-based catalyst compositions include: a catalyst composition prepared by mixing (a) an iron-containing compound, (b) an α -acylphosphonic acid diester, and (c) an organoaluminum compound, a catalyst composition prepared by mixing (a) an iron-containing compound, (b) an α -acylphosphonic acid diester, (c) an organoaluminum compound, and any other organometallic compound or Lewis base, and a catalyst composition comprising (a) an iron-containing compound, (b) a dihydrocarbylphosphite, and (c) an organoaluminum compound.

The cobalt-based catalyst composition comprises: catalyst systems comprising soluble cobalt, such as cobalt octoate, cobalt 1-naphthenate or cobalt benzoate, organoaluminum compounds, such as trimethylaluminum, triethylaluminum, tributylaluminum or triphenylaluminum, and carbon disulfide.

Preferably, the syndiotactic 1, 2-polybutadiene in the present invention has a 1, 2-bond content of 70 mass% or more, more preferably 80 mass% or more, even more preferably 85 mass% or more, and particularly more preferably 90 mass% or more.

In the 1, 2-bond, the syndiotacticity is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, further more preferably 85% by mass or more, and particularly more preferably 90% by mass or more. The syndiotacticity in the present invention means the content of syndiotacticity in 1, 2-bonds.

With syndiotacticity of 1, 2-bonds through syndiotactic 1, 2-polybutadiene¹H and¹³c Nuclear Magnetic Resonance (NMR) analysis.

The syndiotactic 1, 2-polybutadiene in the present invention preferably has a weight average molecular weight of 100,000 to 600,000, more preferably 120,000 to 600,000, still more preferably 140,000 to 600,000, and even more preferably 160,000 to 600,000.

The syndiotacticity of the 1, 2-bond in the syndiotactic 1, 2-polybutadiene is preferably 60% or more, more preferably 65% or more, even more preferably 70% or more, and still more preferably 80% or more. This is because the double network is formed more easily as the syndiotacticity of the 1, 2-bond is higher.

The crystallinity of the syndiotactic 1, 2-polybutadiene is preferably 30 to 80%, more preferably 40 to 80%, and even more preferably 45 to 80%.

When the weight average molecular weight of the syndiotactic 1, 2-polybutadiene falls within the range of 100,000 to 600,000, the syndiotacticity of the 1, 2-bond is 60% or more, and the crystallinity falls within the range of 30 to 80%, the formation of a double network is easy. In this case, the crack growth resistance may be improved, and the syndiotactic 1, 2-polybutadiene may be difficult to be a fracture nucleus functioning as a foreign substance, and from this point, the crack growth resistance may be improved.

[ vulcanized rubber composition ]

The vulcanized rubber composition produced in the present invention preferably contains syndiotactic 1, 2-polybutadiene in an amount of 2 to 50 parts by mass, more preferably 2 to 50 parts by mass, even more preferably 5 to 50 parts by mass, further more preferably 5 to 30 parts by mass, and particularly more preferably 5 to 20 parts by mass, relative to 100 parts by mass of the rubber component containing a polyisoprene rubber therein.

When the composition contains the syndiotactic 1, 2-polybutadiene in an amount of 2 parts by mass or more, a double network of the rubber component containing the polyisoprene rubber and the syndiotactic 1, 2-polybutadiene can be well formed and the crack growth resistance can be improved thereby.

On the other hand, when the composition contains syndiotactic 1, 2-polybutadiene in an amount of 50 parts by mass or less, the following risks can be circumvented: syndiotactic 1, 2-polybutadiene will act as a foreign material intended to act as a nucleus for breakage.

[ Filler ]

The vulcanized rubber composition produced in the present invention may contain a filler. This is because, when a filler is contained, the strength of the vulcanized rubber composition can be high.

As the filler, carbon black or an inorganic filler or an organic filler other than carbon black may be contained. One or two or more kinds of fillers alone may be used alone or in combination.

Preferably, the vulcanized rubber composition of the present invention contains a filler in an amount of 10 to 160 parts by mass, more preferably 15 to 140 parts by mass, even more preferably 15 to 120 parts by mass, and particularly more preferably 20 to 120 parts by mass, relative to 100 parts by mass of the rubber component.

[ carbon Black ]

The carbon black that the vulcanized rubber composition of the present invention may contain is not particularly limited, and for example, SAF, ISAF, IISAF, N339, HAF, FEF or GPF grade carbon black may be used. Nitrogen adsorption specific surface area (N)₂SA, measured according to JIS K6217-2: 2001) is preferably 20 to 160m²A concentration of 25 to 160 m/g is more preferable²A/g, even more preferably 25 to 150m²A specific more preferable range is 30 to 150m²(ii) in terms of/g. The dibutyl phthalate oil absorption (DBP, measured according to JIS K6217-4: 2008) is preferably 40 to 160ml/100g, more preferably 40 to 150ml/100g, even more preferably 50 to 150ml/100g, still more preferably 60 to 150ml/100g, and particularly more preferably 60 to 140ml/100 g. One or two or more kinds of carbon black may be used alone or in combination.

From the viewpoint of improving the strength of the vulcanized rubber composition, the amount (mass%) of carbon black in 100 mass% of the filler is preferably 40 mass% or more, more preferably 50 mass% or more, even more preferably 70 mass% or more, and particularly more preferably 90 mass% or more.

[ inorganic Filler other than carbon Black ]

The inorganic filler other than carbon black that the vulcanized rubber composition of the present invention may contain is preferably silica. Examples of the silica include wet-process silica (hydrous silicic acid), dry-process silica (anhydrous silicic acid), calcium silicate, and aluminum silicate, and among them, wet-process silica is preferable.

Preferably, the wet-process silica has a BET specific surface area (measured according to ISO 5794/1) of 40 to 350m²(ii) in terms of/g. Silica having a BET specific surface area falling within this range has an advantage of being able to satisfy both the rubber reinforcing property and the dispersibility in the rubber component. From this viewpoint, the BET specific surface area falls within the range of 80 to 300m²Silica in the range of/g is more preferred. As such silicas, there are mentioned, for example, "Nipsil AQ" and "Nipsil KQ" from Tosoh Silica Corporation and "Nipsil Corporation" from Evonik CorporationCommercially available products such as "Ultrasil VN3" from It are available.

One or two or more kinds of silica may be used alone or in combination.

Other inorganic fillers besides silica include aluminum hydroxide and clays.

In the case where silica is used as the filler, silane coupling agents such as bis (3-triethoxysilylpropyl) polysulfide, bis (3-triethoxysilylpropyl) disulfide and 3-trimethoxysilylpropylbenzothiazole tetrasulfide are favorably used. The amount of the silane coupling agent to be mixed varies depending on the type of the silane coupling agent, but is preferably selected from the range of 2 to 20 parts by mass per 100 parts by mass of silica.

The unvulcanized rubber composition in the invention may contain compounding agents generally used in the rubber industry, for example, vulcanizing agents, vulcanization accelerators, processing oils, anti-aging agents, scorch retarders, oxidizing agents and stearic acid, as needed and within a range not to impair the advantageous effects of the invention.

In the case of sulfur crosslinking, the vulcanizing agents include sulfur-containing vulcanizing agents, such as sulfur (e.g., powdered sulfur), morpholine disulfide, and polysulfide compounds. The non-sulfur crosslinking includes peroxide crosslinking using t-butyl hydroperoxide, 1,3, 3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, diisopropylbenzene hydroperoxide, t-butylcumyl peroxide, or the like.

[ tires and other rubber articles ]

The vulcanized rubber composition of the present invention can be favorably used in a wide range of fields of tires and other rubber articles. Rubber products other than tires to which the vulcanized rubber composition of the present invention is well applied include conveyor belts, vibration-proof rubbers, vibration-isolating rubbers, rubber tracks, belts, hoses, and fender products.