JP7255773B2 - Method for producing rubber-like polymer and method for producing rubber composition for tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a rubber-like polymer and a method for producing a rubber composition for tires.

Latex obtained by synthesizing a rubber-like polymer may be coagulated to recover the rubber-like polymer. As the aggregation method, as described in paragraph 0048 of Patent Document 1, a method of adding an inorganic metal salt or a coagulant such as a poor solvent is known.

However, when the particle size of the rubber-like polymer is small, the addition of the inorganic metal salt may result in insufficient aggregation. Moreover, when a large amount of inorganic metal salt is used, inorganic metal ions remain in the rubber-like polymer, and there is a possibility that the properties of the compounded rubber composition may be deteriorated. In particular, when a rubber composition for tires is blended with a rubber-like polymer for the purpose of improving tire performance such as wet grip performance, there is a possibility that the fuel efficiency may be deteriorated.

In the case of industrially producing a rubber-like polymer, generally, after performing a polymerization reaction, flocculation is performed in a flocculation tank, and the flocculated polymer is recovered from a discharge port provided at the bottom of the flocculation tank. I do.

However, in the method of adding a poor solvent, the rubber-like polymer coagulates into lumps, loses its fluidity, and has a problem that it cannot be discharged from the discharge port of the coagulation tank.

Japanese Patent No. 5967342

In view of the above points, the present invention provides a method for producing a rubber-like polymer that has excellent workability in industrial production, and a method that can improve wet grip performance while maintaining low fuel consumption. It aims at providing the manufacturing method of the rubber composition for tires.

In the method for producing a rubber-like polymer according to the present invention, a rubber-like polymer is produced by adding a flocculant to a latex containing a rubber-like polymer that is a copolymer of isodecyl methacrylate and ethylene glycol dimethacrylate. An aggregating step is provided, and an aqueous solution containing an inorganic metal salt and an organic solvent are used as the aggregating liquid, and the amount of the inorganic metal salt compounded is 3 to 10 parts per 100 parts by mass of the rubber-like polymer. The content of the organic solvent is 30 to 60% by mass in the liquid component of the mixture of the latex, the aqueous solution, and the organic solvent.

The rubber-like polymer can be synthesized by emulsion polymerization.

The sp value of the organic solvent may be 11-15.

In the method for producing a rubber composition for tires according to the present invention, the above rubber-like polymer is compounded.

According to the method for producing a rubbery polymer of the present invention, workability in industrial production can be greatly improved, and according to the method for producing a rubber composition for tires of the present invention, fuel efficiency can be improved It is possible to obtain a rubber composition for a tire having improved wet grip performance while maintaining the wet grip performance.

Matters related to the implementation of the present invention will be described in detail below.

The method for producing a rubber-like polymer according to the present embodiment has an aggregation step of adding an aggregation liquid to a latex containing a rubber-like polymer to aggregate the rubber-like polymer. An aqueous solution containing a metal salt and an organic solvent are used, the amount of the inorganic metal salt is 3 to 10 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the amount of the organic solvent is the amount described above. It should be 10 to 60% by mass in the liquid component of the liquid mixture of the latex, the above aqueous solution, and the above organic solvent.

Examples of inorganic metal salts include, but are not limited to, metal salts such as sodium hydroxide, sodium sulfate, calcium sulfate, magnesium sulfate, ammonium sulfate, aluminum sulfate, sodium chloride, calcium chloride, and magnesium chloride. It may be used in combination. Among these inorganic metal salts, inorganic metal salts having trivalent inorganic metal ions are preferred.

Although the concentration of the aqueous solution containing the inorganic metal salt is not particularly limited, it is preferably 0.1 to 30% by mass, more preferably 1 to 10% by mass.

The amount of the inorganic metal salt compounded is not particularly limited as long as it is 3 to 10 parts by mass with respect to 100 parts by mass of the rubber-like polymer, but it is preferably 3 to 7 parts by mass. When it is 3 parts by mass or more, a slurry-like rubbery polymer is easily obtained, and when it is 10 parts by mass or less, the amount of the inorganic metal salt remaining in the rubbery polymer can be suppressed, and a rubbery polymer is obtained. By blending the polymer, it is easy to obtain excellent physical properties of the rubber composition.

The addition rate of the inorganic metal salt is not particularly limited, but it is preferably 0.1 to 10 parts by mass/min, and 0.5 to 5 parts by mass/min with respect to 100 parts by mass of the rubber-like polymer. is more preferable.

The organic solvent is not particularly limited, but preferably has an sp value of 11 to 15. For example, methanol (sp value: 14.5), isopropyl alcohol (sp value: 11.5), acetonitrile (sp value: 11.9), ethanol (sp value: 12.7), dimethylformamide (sp value: 12.0), dimethyl sulfoxide (sp value: 12.0), ethylene glycol (sp value: 14.2), etc. are preferred. can be used for When the sp value is within the above range, a slurry-like rubber-like polymer is easily obtained.

In this specification, the sp value (solubility parameter) refers to, for example, Junji Mukai and Noriyuki Kaneshiro, "Jitsugaku Kombunshi for Engineers" (Kodansha, published on October 1, 1981), pp. 71-77. is the value δ [(cal/cm ³ ) ^1/2 ] at 25° C. calculated by the Fedors formula described in 1 (cal/cm ³ ) ^1/2 = 2.05 (MJ/m ³ ) ^{1 /2} , therefore, an SP value of 10 (cal/cm ³ ) ^1/2 or less means 20.5 (MJ/m ³ ) ^1/2 or less.
Fedors formula:
SP value (δ) = (Ev/v) ^1/2 = (ΣΔei/ΣΔvi) ^1/2
Ev: evaporation energy v: molar volume Δei: evaporation energy of each component atom or atomic group Δvi: molar volume of each atom or atomic group

The vaporization energies and molar volumes of each atom or atomic group used in the calculation of the above formula are given by F. Fedors, Polym. Eng. Sci. , 14, 147 <1974>.

The amount of the organic solvent is not particularly limited as long as it is 10 to 60% by mass in the liquid component of the latex, the aqueous solution containing the inorganic metal salt, and the mixed liquid of the organic solvent, but it is 15 to 50% by mass. is preferred. When it is 10% by mass or more, aggregation of the rubber-like polymer tends to occur, and when it is 60% by mass or less, a slurry-like rubber-like polymer is likely to be obtained.

The addition rate of the organic solvent is not particularly limited, but is preferably 0.1 to 10 parts by mass/min with respect to 100 parts by mass of the liquid component of the mixed liquid of the latex and the aqueous solution containing the inorganic metal salt. Preferably, it is 0.5 to 5 parts by mass/min.

As in the present embodiment, when an aqueous solution containing an inorganic metal salt and an organic solvent are added to a latex containing a rubber-like polymer, the rubber-like polymer does not agglomerate and form secondary particles or tertiary particles. A slurry state in which the particles of the rubber-like polymer are dispersed can be maintained. Although the mechanism is not clear, the charge on the surface of the rubber-like polymer is canceled by the inorganic metal ions, which increases the compatibility between the rubber-like polymer and the organic solvent, and the rubber-like polymer gradually aggregates. It is considered to be for According to the production method of the present embodiment, the rubber-like polymer crumb obtained in industrial production has fluidity, so that the rubber-like polymer can be easily recovered from the outlet of the flocculation tank. . As used herein, the term "aggregation" refers to a phenomenon in which colloidal particles aggregate to form larger particles.

The aqueous solution containing the inorganic metal salt and the organic solvent may be added separately, or may be mixed in advance and added as a mixed solution. Preferably the solvent is added or added as a mixture. That is, the aggregation step includes the first aggregation step of adding an aqueous solution containing an inorganic metal salt to aggregate the rubber-like polymer, and the addition of an organic solvent having an sp value of 11 to 15 to aggregate the rubber-like polymer. Alternatively, a mixed solution of an aqueous solution containing an inorganic metal salt and an organic solvent having an sp value of 11 to 15 is added to aggregate the rubber-like polymer. A process is preferred.

The rate of addition in the case of adding as a mixed liquid is not particularly limited, but it is preferably 0.1 to 10 parts by mass/min, and 0.5 to 5 parts by mass/min with respect to 100 parts by mass of the liquid component of the latex. min is more preferred.

The method of polymerizing the rubber-like polymer is not particularly limited, and examples thereof include emulsion polymerization, solution polymerization, and suspension polymerization. Among them, emulsion polymerization is preferred.

The stirrer used in the agglomeration step of the present embodiment is not particularly limited, and for example, stirrers with general stirring blades such as three-way swept-back blades, paddle-type, anchor-type, turbine blades, and Maxblend blades can be used. can be used.

The rotation speed of the stirrer in the aggregation step of the present embodiment is not particularly limited, and varies depending on the stirring blade shape of the stirrer used. It may be 100-400 rpm.

Examples of the present invention are shown below, but the present invention is not limited to these examples.
[Synthesis example]
3000 g of 2,4,6-trimethylheptyl methacrylate (isodecyl methacrylate), 78.8 g of ethylene glycol dimethacrylate, 382.2 g of sodium dodecyl sulfate, 6300 g of water and 700 g of ethanol are mixed and allowed to stir for 1 hour. After emulsifying the monomers, 35.8 g of potassium persulfate was added, nitrogen bubbling was carried out for 1 hour while stirring, and the solution was maintained at 70° C. for 8 hours to obtain fine particles of the rubber-like polymer. A dispersed latex was obtained.

Aggregation was carried out by adding a flocculant while stirring the obtained latex.

Stirring was carried out by a mechanical stirring method using stirring blades in the coagulation tank, and the stirring blades were swept back in three directions.

The aggregation state of the obtained rubber-like polymer was confirmed visually. Those in which agglomerated rubber-like polymers are dispersed in a slurry form are evaluated as having excellent workability in industrial production. Those that formed lumps were evaluated as unsuitable for industrial production.

[Example 1-1]
While stirring the obtained emulsion at 300 rpm, 5250 g of a 3 wt % aluminum sulfate aqueous solution was added to loosely coagulate the polymer, and then 5250 g of isopropyl alcohol (IPA) was added to coagulate the rubber-like polymer 1. rice field. Rubber-like polymer 1 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 30% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

[Example 1-2]
Rubber-like polymer 2 was aggregated in the same manner as in Example 1-1 except that 5250 g of acetonitrile was used instead of isopropyl alcohol used in Example 1-1. Rubber-like polymer 2 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 30% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

[Example 1-3]
Rubber-like polymer 3 was aggregated in the same manner as in Example 1-1, except that 5250 g of ethanol was used instead of isopropyl alcohol used in Example 1-1. Rubber-like polymer 3 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 30% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

[Example 1-4]
Rubber-like polymer 4 was aggregated in the same manner as in Example 1-1, except that 5250 g of methanol was used instead of isopropyl alcohol used in Example 1-1. The rubber-like polymer 4 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 30% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

[Comparative Example 1-1]
Rubber-like polymer 5 was aggregated in the same manner as in Example 1-4, except that the concentration of the aluminum sulfate aqueous solution used in Example 1-4 was changed to 1.2% by mass. The rubber-like polymer 5 was coagulated and precipitated as a lumpy solid. The amount of the inorganic metal salt was 2 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the amount of the organic solvent was 30% by mass in the liquid component of the mixture of the latex and the coagulant. .

[Example 1-5]
Rubber-like polymer 6 was aggregated in the same manner as in Example 1-4, except that the concentration of the aluminum sulfate aqueous solution used in Example 1-4 was changed to 4.2% by mass. The rubber-like polymer 6 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 7 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 30% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

[Comparative Example 1-3]
Rubber-like polymer 8 was aggregated in the same manner as in Example 1-4 except that 2205 g of methanol was used in Example 1-4. Since the solution only became cloudy and no solid content could be visually confirmed, the cohesiveness of the rubber-like polymer 8 was evaluated as insufficient. The amount of the inorganic metal salt was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the amount of the organic solvent was 15% by mass in the liquid component of the mixed liquid of the latex and the coagulation liquid. .

[Example 1-6]
Rubber-like polymer 9 was aggregated in the same manner as in Example 1-4, except that 18,375 g of methanol was used in Example 1-4. Rubber-like polymer 9 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 60% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

[Comparative Example 1-4]
Rubber-like polymer 10 was aggregated in the same manner as in Example 1-4, except that 22,890 g of methanol was used in Example 1-4. The rubber-like polymer 10 was coagulated and precipitated as a lumpy solid. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 65% by mass in the liquid component of the mixed liquid of the latex and the coagulation liquid. .

[Example 1-7]
Rubber-like polymer 11 was aggregated in the same manner as in Example 1-4, except that 5250 g of an aqueous sodium chloride solution was used instead of aluminum sulfate used in Example 1-4. The rubber-like polymer 11 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 30% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

[Example 1-8]
Rubber-like polymer 12 was aggregated in the same manner as in Example 1-4 except that 5250 g of an aqueous calcium chloride solution was used instead of aluminum sulfate used in Example 1-4. The rubber-like polymer 12 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 30% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

[Example 1-9]
Rubber-like polymer 13 was coagulated in the same manner as in Example 1-4, except that 5,250 g of a 3 wt % aluminum sulfate aqueous solution and 5,250 g of methanol were mixed in advance as a coagulating liquid. The rubber-like polymer 13 precipitated as a slurry dispersed in the solution. The amount of the inorganic metal salt compounded was 5 parts by mass with respect to 100 parts by mass of the rubber-like polymer, and the compounded amount of the organic solvent was 30% by mass in the liquid component of the liquid mixture of the latex and the coagulation liquid. .

For those obtained as a slurry-like rubber-like polymer, the concentration of inorganic metal ions remaining in the rubber-like polymer was measured. The measurement methods are as follows, and the measurement results are shown in Table 1.

Total amount of metal ions: To 0.1 g of the obtained polymer was added 5 ml of nitric acid, decomposed with microwaves, diluted to 50 ml with distilled water, and used as a measurement solution. Using "Optima 8300" manufactured by PerkinElmer Co., Ltd., inductively coupled plasma emission spectroscopy (ICP-OES) was performed to measure sodium concentration, potassium concentration, aluminum concentration, and calcium concentration, and the total value was obtained.

As shown in Table 1, by using an aqueous solution containing an inorganic metal salt and an organic solvent together as a flocculating agent in predetermined amounts, a slurry-like rubber-like polymer that maintains fluidity can be obtained. It was found that excellent workability can be obtained in general production.

The rubber-like polymer obtained in slurry form was evaluated for tire performance when blended with a rubber composition for tires.

Using a Banbury mixer, according to the formulation (parts by mass) shown in Table 2 below, first, in the non-professional kneading process, the vulcanization accelerator and components other than sulfur are added and mixed (discharge temperature = 160 ° C.), and in the professional kneading process , a vulcanization accelerator and sulfur were added and mixed (exhaust temperature = 90°C) to prepare a rubber composition.

Details of each component in Table 2 are as follows.

・Modified SBR: "HPR350" manufactured by JSR Corporation, alkoxy group and amino group terminal modified solution polymerized SBR
・ BR: “Ubepol BR150B” manufactured by Ube Industries, Ltd.
・ Silica: “Nip Seal AQ” manufactured by Tosoh Silica Co., Ltd.
Silane coupling agent: Evonik Japan Co., Ltd. "Si69", bis (3-triethoxysilylpropyl) tetrasulfide Rubber-like polymer 1: Rubber-like polymer obtained in Example 1-1 above Rubber-like polymer 2: The rubber-like polymer obtained in Example 1-2 above/Rubber-like polymer 3: The rubber-like polymer/rubber-like polymer obtained in Example 1-3 above 4: Rubber-like polymer obtained in Example 1-4 above/Rubber-like polymer 6: Rubber-like polymer obtained in Example 1-5 above
・Rubber-like polymer 9: The rubber-like polymer obtained in Example 1-6 above ・Rubber-like polymer 11: The rubber-like polymer obtained in Example 1-7 above ・Rubber-like polymer 12 : Rubber-like polymer obtained in Example 1-8 above Rubber-like polymer 13: Rubber-like polymer obtained in Example 1-9 above Zinc white: Mitsui Kinzoku Mining Co., Ltd. " 1 kind of zinc white
・ Anti-aging agent: "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・ Sulfur: “Rubber powder sulfur 150 mesh” manufactured by Hosoi Chemical Industry Co., Ltd.
・ Vulcanization accelerator: "Noccellar CZ" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
・Secondary vulcanization accelerator: "Noccellar D" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

Wet grip performance and fuel efficiency were evaluated for each of the obtained rubber compositions. The evaluation method is as follows.

- Wet grip performance: The loss factor tan δ was measured at a temperature of 0°C. Tan δ at 0° C. is generally used as an index of grip performance on wet road surfaces (wet grip performance) in rubber compositions for tires. indicates that

· Low fuel consumption: Loss factor tan δ was measured at a temperature of 60°C. Tan δ at 60° C. is generally used as an indicator of fuel efficiency in rubber compositions for tires. The smaller the above index, the smaller the tan δ. It shows that it is superior to

The results are as shown in Table 2. Comparative Example 2-1 and Examples 2-1 to 2-9 were compared to obtain the production methods of Examples 1-1 to 1-9. It was found that a rubber composition for tires with improved wet grip performance while maintaining low fuel consumption can be obtained by a method for producing a rubber composition containing a rubber-like polymer with a small residual amount of metal ions. .

The method for producing a rubber-like polymer of the present invention can be suitably used for industrial production of a rubber-like polymer used for various purposes.

Claims (4)

a flocculation step of flocculating the rubber-like polymer by adding a flocculating liquid to a latex containing a rubber-like polymer that is a copolymer of isodecyl methacrylate and ethylene glycol dimethacrylate ;
Using an aqueous solution containing an inorganic metal salt and an organic solvent as the aggregation liquid,
The amount of the inorganic metal salt compounded is 3 to 10 parts by mass with respect to 100 parts by mass of the rubber-like polymer,
A method for producing a rubber-like polymer, wherein the blending amount of the organic solvent is 30 to 60% by mass in the liquid component of the mixed liquid of the latex, the aqueous solution, and the organic solvent. 2. The method for producing a rubber-like polymer according to claim 1, wherein the rubber-like polymer is synthesized by emulsion polymerization. 3. The method for producing a rubber-like polymer according to claim 1, wherein the organic solvent has an sp value of 11-15. A method for producing a rubber composition for tires, comprising blending the rubber-like polymer obtained by the production method according to any one of claims 1 to 3.