Conjugated diene copolymer, method for producing same, and impact-resistant styrene resin composition

Abstract

This conjugated diene copolymer is configured such that the accumulated light emission of weak light generated by chemical reaction is no greater than 150 x 105 cps and the Δb value before and after heating for 2 hours at 160°C is no greater than 4.0.

Description

Conjugated diene polymer, its production method, and impact-resistant styrene resin composition

[0001] The present invention relates to a conjugated diene polymer, a method for producing the same, and an impact-resistant styrene resin composition.

[0002] Styrenic resins have excellent rigidity, transparency, processability, etc., and are widely used in a variety of applications, from everyday items to industrial products. However, styrene resins have the drawback of being hard but brittle and having low impact strength. On the other hand, when unvulcanized rubber is used as a toughening agent and graft-copolymerized with a styrene monomer by bulk polymerization, solution polymerization, or bulk suspension polymerization, rubber particles are dispersed in a polystyrene matrix, and the dispersed rubber absorbs impact, thereby producing an impact-resistant styrene resin composition that improves on the impact strength that is a drawback of styrene resins. Impact-resistant styrene resin compositions have an excellent balance between impact strength and rigidity and are used as a variety of packaging materials and containers, primarily for home appliances and food containers.

[0003] Recently, there has been a demand for higher quality products, and the demand for better appearance of impact-resistant styrene-based resin compositions is increasing. Furthermore, gloss and impact strength are important physical properties of impact-resistant styrene-based resin compositions, and there remains a strong demand for an improved balance between these two trade-off properties. One way to improve the balance between gloss and impact strength is to reduce gel in the conjugated diene polymer used as rubber particles. This is because gel not involved in graft polymerization is reduced, and all of the added conjugated diene polymer participates in graft polymerization. For example, Patent Document 1 proposes suppressing gel in rubber particles by blending a specific sulfur-containing phenolic stabilizer with a specific low-cis conjugated diene polymer obtained by a continuous polymerization method. Patent Document 2 proposes a conjugated diene polymer with good appearance and reduced gel generation by lowering the temperature when feeding monomers to a polymerization reactor in a continuous polymerization method.

[0004] JP 11-228742 A JP 2014-108977 A

[0005] However, the conjugated diene polymers described above still have room for improvement in order to fully satisfy the increasing balance between appearance, gloss, and impact strength required for impact-resistant polystyrene polymers. Therefore, in order to solve the above-mentioned problems, an object of the present invention is to provide a conjugated diene polymer capable of providing an impact-resistant styrene resin composition having an excellent balance between appearance, gloss, and impact strength, a method for producing the conjugated diene polymer, and an impact-resistant styrene resin composition containing the conjugated diene polymer.

[0006] The present inventors have conducted extensive research to solve the above problems, and as a result have completed the present invention. That is, the present invention is as follows: <1> A method for detecting a weak luminescence due to a chemical reaction in which the cumulative luminescence amount is 150×10 ５ A conjugated diene-based polymer having a viscosity of 50 cps or less and a Δb value of 4.0 or less before and after heating at 160°C for 2 hours. <2> The conjugated diene-based polymer according to <1> above, wherein the 5% by mass styrene solution viscosity (SV) of the conjugated diene-based polymer measured at 25°C is 50 < SV ≦ 75 (mPa s). <3> The conjugated diene-based polymer according to <1> above, wherein the 5% by mass styrene solution viscosity (SV) of the conjugated diene-based polymer measured at 25°C is 75 < SV ≦ 280 (mPa s). <4> The conjugated diene-based polymer according to any one of <1> to <3> above, wherein the P (phosphorus) content of the conjugated diene-based polymer is 20 ppm or less. <5> The conjugated diene-based polymer according to any one of <1> to <4> above, wherein the Δb value is 3.0 or less. <6> The conjugated diene-based polymer according to any one of <1> to <4> above, wherein the integrated quantity of light emitted is 40 × 10 ５<7> The conjugated diene polymer according to any one of <1> to <5>, wherein the molecular weight distribution (Mw / Mn) of the conjugated diene polymer, as measured by GPC (gel permeation chromatography), is 1.5 or more and 2.5 or less. <8> The conjugated diene polymer according to any one of <1> to <7>, wherein the conjugated diene polymer is polybutadiene. <9> The conjugated diene polymer according to any one of <1> to <8>, wherein the conjugated diene polymer is polybutadiene for use in an impact-resistant styrene polymer composition. <10> A method for producing a conjugated diene polymer, comprising: a polymerization step of continuously supplying 1,3-butadiene or 1,3-butadiene and an aromatic vinyl compound, and an inert solvent to a polymerization reactor, and continuously polymerizing using an organolithium compound as an initiator to obtain an active-end-containing conjugated diene polymer; and the following steps (1) to (3): (1) A deactivator addition step of adding a deactivator that deactivates an active polymerization terminal of the active end-containing conjugated diene polymer, (2) A neutralizer addition step of adding a neutralizer that neutralizes lithium hydroxide, and (3) A stabilizer addition step of adding a stabilizer. <11> A method for producing a conjugated diene polymer according to <10>, wherein the deactivator addition step, the neutralizer addition step, and the stabilizer addition step are carried out in this order. <12> An impact-resistant styrene polymer composition comprising the conjugated diene polymer according to any one of <1> to <9>.

[0007] According to the present invention, there are provided a conjugated diene polymer capable of providing an impact-resistant styrene-based resin composition having an excellent balance between appearance, gloss, and impact strength, a method for producing the conjugated diene-based polymer, and an impact-resistant styrene-based resin composition containing the conjugated diene-based polymer.

[0008] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0009] [Conjugated diene polymer] The conjugated diene polymer of the present embodiment has an integrated luminescence amount of weak luminescence due to a chemical reaction of 150×10 ５ The Δb value before and after heating at 160° C. for 2 hours is 4.0 or less. Although not particularly limited, examples of the conjugated diene-based polymer of the present embodiment include polybutadiene, and further include polybutadiene for impact-resistant styrene-based polymer compositions.

[0010] (Cumulative Amount of Light Emitted) The cumulative amount of light emitted by the weak light generated by the chemical reaction of the conjugated diene polymer of this embodiment (hereinafter, sometimes simply referred to as "cumulative amount of light emitted") is 150×10 ５ cps or less, preferably 75 x 10 ５ cps, more preferably 40×10 ５ cps or less. Here, "the integrated amount of faint luminescence due to a chemical reaction of a conjugated diene polymer" refers to the total amount of luminescence detected due to the oxidation reaction of the conjugated diene polymer. The integrated amount of luminescence can be measured, for example, by the following means. The device used to measure the integrated amount of luminescence is an ultraweak luminescence detection spectroscopy system (CLA-FS4, manufactured by Tohoku Electronics Industries Co., Ltd.) and a temperature-raising sample chamber (CLS-SH1, manufactured by Tohoku Electronics Industries Co., Ltd.). The temperature was raised from the measurement starting temperature of 50°C to 200°C at a temperature rise rate of 20°C / min in an oxygen atmosphere of 50 ml / min, and then maintained at 200°C for 10 minutes from the start of the temperature rise. The total amount of luminescence for 10 minutes from the start of the temperature rise was taken as the integrated amount of luminescence. This detects luminescence due to an oxidation reaction that occurs when a conjugated diene polymer is heated in air or oxygen. In other words, the greater the amount of luminescence, the more oxidation reaction has occurred, indicating poor thermal stability. Impact-resistant styrene polymer compositions prepared using conjugated styrene polymers with poor thermal stability tend to have a poor balance between gloss and impact strength.

[0011] (Δb Value) The "b value" is a value relating to color difference, and is a value that indicates the intensity of color for yellow and blue-purple. In the conjugated diene polymer of this embodiment, the "Δb value before and after heating at 160°C for 2 hours" (hereinafter sometimes simply referred to as "Δb value") is the difference between the b value before heating and the b value after heating at 160°C for 2 hours. Detailed conditions will be described in the Examples. The Δb of the conjugated diene polymer of this embodiment is 4.0 or less, and preferably 3.0 or less. If it is within this range, when it is made into an impact resistant styrene polymer composition, an impact resistant styrene polymer composition with excellent appearance and little yellowness tends to be obtained.

[0012] (5 Mass% Styrene Solution Viscosity (SV)) The conjugated diene polymer of this embodiment can have a 5 mass% styrene solution viscosity (hereinafter sometimes simply referred to as "SV") at a measurement temperature of 25°C of 50 < SV ≦ 75 (mPa s). "5 mass% styrene solution viscosity at a measurement temperature of 25°C" means a value obtained by measuring a 5 mass% styrene solution of the conjugated diene polymer at 25°C using a Cannon-Fenske viscometer. SV can be measured by the method described in the Examples below. When a conjugated diene polymer having an SV within this range is used, an impact-resistant styrene polymer composition having small rubber particles can be easily obtained, and the composition tends to have excellent gloss. From this perspective, the SV is preferably 55 ≦ SV ≦ 75 (mPa s), more preferably 60 ≦ SV ≦ 70 (mPa s). Furthermore, the conjugated diene polymer of this embodiment can have an SV of 75 < SV ≦ 280 (mPa s). When a conjugated diene polymer having an SV in this range is used, an impact-resistant styrene polymer composition having large rubber particles can be easily obtained, and the impact resistance tends to be excellent. From this viewpoint, the SV is preferably 85≦SV≦250 (mPa s), and more preferably 140≦SV≦180 (mPa s).

[0013] (Molecular Weight, Molecular Weight Distribution) The conjugated diene polymer of this embodiment may have a polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of preferably 200,000 to 800,000, more preferably 250,000 to 700,000, and even more preferably 300,000 to 600,000. From the viewpoint of suppressing cold flow of the resulting conjugated diene polymer, Mw is preferably 200,000 or more. Furthermore, in terms of correlation with the solution viscosity of the conjugated diene polymer, Mw is preferably 800,000 or less. Furthermore, from the viewpoint of improving productivity, the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (molecular weight distribution: Mw / Mn) is preferably 1.5 to 2.5. When the molecular weight distribution of the conjugated diene polymer is within this range, the balance between gloss and impact strength tends to be excellent when used with an impact-resistant styrene polymer composition. Furthermore, when the conjugated diene polymer of this embodiment exhibits the same SV, the larger the molecular weight distribution, the better the cold flow property tends to be. Generally, in order to improve the cold flow property, a method of introducing branched components using a coupling agent or the like during polymerization is adopted. However, this method increases the amount of polymerization initiator used, and the costs of the polymerization initiator and coupling agent are incurable, so a larger molecular weight distribution is preferred. Here, a larger molecular weight distribution means a molecular weight distribution of 1.5 or more.

[0014] (Mooney Viscosity) The conjugated diene polymer of the present embodiment has a Mooney viscosity (ML １＋４ The Mooney viscosity (ML １＋４ ) of 25 or more tends to further suppress cold flow, and from the viewpoint of bale molding during industrial production, １＋４ ) is preferably 100 or less. １＋４) is 30 or more and 80 or less, more preferably 30 or more and 75 or less, and from the viewpoints of gloss and impact resistance when made into an impact-resistant styrene-based resin composition and handling such as mixing and stirring with raw materials for the impact-resistant styrene-based resin composition, still more preferably 40 or more and 60 or less.

[0015] (P Content) The conjugated diene polymer of this embodiment preferably has a P (phosphorus) content of 150 ppm, more preferably 100 ppm or less, even more preferably 50 ppm or less, and particularly preferably contains no P. Here, "containing no P" means that the P content is 20 ppm or less. P is often present in the conjugated diene polymer in the form of a phosphate ester, which is expected to have a color-improving effect. P often hydrolyzes to generate phosphoric acid, which corrodes metals and the like, causing rust and possibly contaminating them. Furthermore, a polymer containing a phosphate ester is slippery; for example, the extruder may slip during the dehydration step of removing the solvent by steam stripping after polymerization, resulting in a conjugated diene polymer containing a large amount of water, or the drying time may be longer than usual. If the water content of the conjugated diene polymer is high, for example, when polymerizing an impact-resistant styrene polymer, the desired impact-resistant styrene polymer may not be obtained.

[0016] [Method for Producing Conjugated Diene Polymer] The conjugated diene polymer of this embodiment can be synthesized, for example, by the following production method. The method for producing the conjugated diene polymer of this embodiment (hereinafter sometimes referred to as the "production method of this embodiment") includes a polymerization step of continuously supplying 1,3-butadiene or 1,3-butadiene and an aromatic vinyl compound, and an inert solvent to a polymerization reactor and continuously polymerizing using an organolithium compound as an initiator to obtain an active end-containing conjugated diene polymer, and the following steps (1) to (3): (1) a deactivator addition step of adding a deactivator that deactivates the active polymerization ends of the active end-containing conjugated diene polymer, (2) a neutralizer addition step of adding a neutralizer that neutralizes lithium hydroxide, and (3) a stabilizer addition step of adding a stabilizer. The production method of this embodiment may include other steps before or after each of the steps. Furthermore, after the polymerization step, the order of steps (1) to (3) (particularly the order of steps (1) and (2)) is not limited, and either step may precede the other, or they may be carried out simultaneously.

[0017] The integrated light emission amount of the conjugated diene polymer of this embodiment can be adjusted by controlling the order of each addition step and the amount of stabilizer added.

[0018] The "Δb value" of the conjugated diene polymer of the present embodiment can be adjusted not only by the amount of stabilizer added and the order of each addition step, but also, for example, by performing a demineralization step for removing metals from the conjugated diene polymer solution instead of or in addition to the neutralizing agent addition step, and by controlling the conditions of that step.

[0019] <Polymerization Step> In the production method of this embodiment, in the polymerization step, a monomer (1,3-butadiene alone or 1,3-butadiene and an aromatic vinyl compound) and an inert solvent are continuously supplied to a polymerization reactor, and the monomers are continuously (co)polymerized using an organolithium compound as an initiator to obtain a conjugated diene polymer having an active end. The conjugated diene polymer is a homopolymer of 1,3-butadiene or a copolymer of 1,3-butadiene and an aromatic vinyl compound. In the production method of this embodiment, raw material monomers and an inert solvent are supplied to a polymerization reactor, and the monomers are continuously polymerized, ultimately producing a polymer with a broad molecular weight distribution.

[0020] (Polymerization Temperature) In the production method of this embodiment, the polymerization temperature is preferably 70° C. or higher from the viewpoint of efficient production, and 130° C. or lower from the viewpoint of reducing side reactions.

[0021] (Polymerization Reactor) In the production method of this embodiment, the shape of the polymerization reactor is not particularly limited, and for example, a reactor of a tank type, a tubular type, a tower type, or the like equipped with an agitator can be used. The form of the polymerization reactor is not particularly limited, and for example, it may be a complete mixing type reactor or a plug flow type reactor. The reactor includes a reactor installed midway through a transfer pipe. The plug flow type reactor is not particularly limited, and includes a static mixer or a dynamic mixer having an agitation function. In the production method of this embodiment, one or two or more reactors connected in parallel or in series can be used.

[0022] (Aromatic Vinyl Compound) In the production method of this embodiment, the aromatic vinyl compound may be a monomer copolymerizable with a conjugated diene compound, particularly 1,3-butadiene, and is not particularly limited. Examples include styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of ease of industrial availability. Furthermore, from the viewpoint of preventing cold flow in the polymer obtained by the polymerization step, a polyfunctional aromatic vinyl compound such as divinylbenzene may be used to control branching. These compounds may be used alone or in combination of two or more.

[0023] (Organolithium Compound) In the production method of this embodiment, the organolithium compound used as the polymerization initiator is not particularly limited, and examples thereof include monoorganolithium compounds and polyfunctional organolithium compounds. Examples of monoorganolithium compounds include, but are not limited to, low molecular weight compounds, solubilized oligomeric organolithium compounds, compounds having a carbon-lithium bond in the bonding mode between the organic group and lithium, and compounds having a nitrogen-lithium bond. Examples of carbon-lithium compounds include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium. Examples of compounds having a nitrogen-lithium bond include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium di-n-hexylamide, lithium diisopropylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, and lithium morpholide.

[0024] The polyfunctional organolithium compound is not particularly limited, but examples thereof include 1,4-dilithiobutane, a reaction product of sec-butyllithium and diisopropenylbenzene, 1,3,5-trilithiobenzene, a reaction product of n-butyllithium with 1,3-butadiene and divinylbenzene, and a reaction product of n-butyllithium and a polyacetylene compound. The organolithium compound is not particularly limited, but known compounds disclosed in, for example, U.S. Pat. No. 5,708,092, British Patent No. 2,241,239, and U.S. Pat. No. 5,527,753 can also be used. From the viewpoints of industrial availability and ease of control of the polymerization reaction, n-butyllithium and sec-butyllithium are preferred as organolithium compounds. The organolithium compounds may be used alone or in combination of two or more.

[0025] (Polymerization Solvent (Inert Solvent)) In the production method of this embodiment, the polymerization reaction of the monomers is carried out in an inert solvent. The inert solvent is not particularly limited, and examples thereof include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific examples include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene, and hydrocarbons consisting of mixtures thereof.

[0026] (Allenes) In the production method of this embodiment, from the viewpoint of improving the effect of suppressing gel formation, it is preferable to allow allenes to coexist with the monomers and inert solvent in the polymerization system. On the other hand, in order to sufficiently proceed with the coupling reaction and obtain a necessary and sufficient degree of branching, it is preferable to control the total content concentration (mass) of allenes in the polymerization system within a specific range. The total content concentration (mass) of allenes is preferably 50 ppm or more and 350 ppm or less, more preferably 60 ppm or more and 300 ppm or less, and even more preferably 70 ppm or more and 250 ppm or less, relative to the monomer. Examples of allenes include propadiene and 1,2-butadiene.

[0027] (Other Additives) A ​​polar compound can be added to the polymerization reactor for the purpose of randomly copolymerizing butadiene and an aromatic vinyl compound, controlling the amount of 1,2-vinyl bonds in butadiene bond units, or promoting the polymerization reaction. The polar compound is not particularly limited, and examples thereof include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium tert-amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more. The amount of polar compound used is not particularly limited and can be selected depending on the purpose, etc. Specifically, a ratio of 0.01 to 100 moles per mole of polymerization initiator is preferred. Such polar compounds (vinylating agents) can be used in an appropriate amount depending on the desired vinyl bond content as a modifier for the microstructure of the butadiene portion of the polymer. Many polar compounds also have an effective randomizing effect in the copolymerization of butadiene and an aromatic vinyl compound, and can be used as an agent for adjusting the distribution of the aromatic vinyl compound or the amount of styrene blocks. One method for randomizing butadiene and an aromatic vinyl compound is, for example, to initiate a copolymerization reaction with styrene and a portion of the 1,3-butadiene, and then intermittently add the remaining 1,3-butadiene during the copolymerization reaction.

[0028] (Active End-Containing Conjugated Diene Polymer) In the production method of this embodiment, an active end-containing conjugated diene polymer is obtained in the polymerization step as described above. The microstructure of the butadiene moiety in the conjugated diene polymer is not particularly limited, but it is preferable that the 1,2-vinyl content is 10% to 80% and the cis-1,4-content is 10% to 85%. In particular, a 1,2-vinyl content of 10% to 25% is preferable for use as a modifier for styrene-based resins. The 1,2-vinyl content can be adjusted using polar compounds as described above. For example, this can be achieved by feeding an ether such as tetrahydrofuran (THF) into a reactor together with the monomer and an inert solvent in the polymerization step and conducting the polymerization. When the aromatic vinyl compound in the production method of this embodiment is styrene, the amount of vinyl bonds (1,2-bonds) in the butadiene bond units can be determined by Hampton's method (R.R. Hampton, Analytical Chemistry, 21, 923 (1949)). The amount of bound aromatic vinyl in the conjugated diene polymer is not particularly limited, but is preferably 0% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less. The amount of bound aromatic vinyl can be measured by ultraviolet absorption of phenyl groups.

[0029] When two or more types of monomers are used in this embodiment, the active end-containing conjugated diene polymer (copolymer) may be a random copolymer or a block copolymer. The compositional distribution of each monomer unit in the random copolymer chain is not particularly limited, and examples include a completely random copolymer with a statistically random composition and a tapered (gradient) random copolymer in which the composition is distributed in a tapered pattern. The bonding mode of butadiene, i.e., the composition of 1,4-bonds or 1,2-bonds, may be uniform or may have a distribution. Examples of block copolymers include a type 2 block copolymer (diblock) consisting of two blocks, a type 3 block copolymer (triblock) consisting of three blocks, and a type 4 block copolymer (tetrablock) consisting of four blocks. For example, if the block consisting of an aromatic vinyl compound such as styrene is represented by "S" and the block consisting of butadiene is represented by "B," the copolymer may be represented as an S-B2 block copolymer, an S-B-S3 block copolymer, an S-B-S-B4 block copolymer, or the like. In the above formula, the composition of each block does not necessarily have to be uniform. For example, block B may be a copolymer of butadiene and an aromatic vinyl compound. Similarly, in the above formula, the boundaries between the blocks do not necessarily need to be clearly distinguished. For example, when block B is a copolymer of butadiene and an aromatic vinyl compound, the aromatic vinyl compound in block B may be distributed uniformly or in a tapered pattern. Furthermore, block B may contain a plurality of portions where the aromatic vinyl compound is distributed uniformly and / or a plurality of portions where the aromatic vinyl compound is distributed in a tapered pattern. Furthermore, block B may contain a plurality of segments with different aromatic vinyl compound contents. When a copolymer contains a plurality of blocks S and a plurality of blocks B, the structures, such as molecular weight and composition, of these blocks may be the same or different. The monomer composition distribution can be measured by osmic acid decomposition or ozonolysis.

[0030] <Coupling Step> The production method of this embodiment may include a coupling step. The coupling step can be carried out between the polymerization step and the quencher addition step. In the coupling step, a coupling agent represented by the following formula (1) is continuously added to the active terminals of the conjugated diene polymer to cause a reaction, thereby continuously producing a branched conjugated diene polymer. (In formula (1), each R independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms. n is an integer of 0 or 1.) In the production method of the present embodiment, by continuously carrying out the coupling reaction, a polymer having a wide molecular weight distribution can be obtained.

[0031] (Coupling Agent) In the production method of this embodiment, by using the coupling agent represented by formula (1), a conjugated diene-based polymer with excellent appearance can be produced without containing a halogen compound. Examples of the coupling agent include, but are not limited to, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane. Among these, tetramethoxysilane and tetraethoxysilane are preferred from the viewpoints of industrial availability and ease of branching reaction. These compounds may be used as is or dissolved in a solvent. When a solvent is used, it is preferable to use a hydrocarbon solvent that is inert to the active terminals of the linear butadiene-based polymer. Examples of hydrocarbon solvents include benzene, toluene, cyclohexane, and n-hexane.

[0032] (Amount of Coupling Agent Added) In the production method of this embodiment, the amount of the coupling agent added is not particularly limited, but is preferably 0.1 mol or more and 0.6 mol or less, more preferably 0.13 mol or more and 0.5 mol or less, and even more preferably 0.15 mol or more and 0.4 mol or less, relative to 1 mol of the polymerization initiator. The amount is preferably 0.1 mol or more so that the conjugated diene polymer has a sufficient degree of branching, and is preferably 0.6 mol or less so that the coupling agent is added in an amount greater than necessary, which would result in a decrease in the degree of branching and an increase in costs.

[0033] (Coupling Reactor) In the production method of this embodiment, the shape of the coupling reactor is not particularly limited, and for example, a reactor of a tank type, a tubular type, a tower type, or the like equipped with a stirrer is used. The form of the coupling reactor is not particularly limited, and for example, it may be a complete mixing type reactor or a plug flow type reactor. The reactor includes a reactor installed midway through a transfer pipe. The plug flow type reactor is not particularly limited, and includes a static mixer or a dynamic mixer having a stirring function.

[0034] (Coupling Reaction Temperature) The coupling reaction temperature in the production method of this embodiment is not particularly limited, but is preferably 50° C. or higher and 130° C. or lower, and more preferably 60° C. or higher and 120° C. or lower. In order to proceed with the coupling reaction with high efficiency without deactivating the active terminals, the reaction is preferably carried out at 130° C. or lower, and from the viewpoint of the coupling reaction rate, the reaction is preferably carried out at 50° C. or higher.

[0035] (Coupling Reaction Time) The reaction time when the coupling agent is reacted with the active terminal of the linear butadiene-based polymer is not particularly limited, but from the viewpoint of the coupling reaction rate, the reaction time is preferably from 30 seconds to 120 minutes, more preferably from 1 minute to 60 minutes, and even more preferably from 2 minutes to 45 minutes. Here, the coupling reaction time refers to the average residence time of the active terminal-containing linear butadiene-based polymer in the coupling step.

[0036] (Removal of Impurities) For example, treating acetylenes and the like contained as impurities in the monomer and the inert solvent with an organometallic compound before subjecting them to a polymerization reaction is preferred because it tends to give a polymer having a high concentration of active ends and also tends to achieve a high coupling rate.

[0037] [Deactivator Addition Step] The deactivator addition step is, for example, a step of adding a deactivator to a solution of the obtained conjugated diene polymer after carrying out a polymerization reaction or a coupling reaction, in order to deactivate the active polymerization terminal of the active end-containing conjugated diene. The deactivator is not particularly limited, and examples thereof include water, alcohols such as methanol, ethanol, and isopropanol. Water is preferred from the viewpoint of easy availability.

[0038] (Amount of Deactivator Added) In the production method of this embodiment, the amount of the deactivator added is not particularly limited, but is preferably 5 parts by mass or more and 50 parts by mass or less, more preferably 7 parts by mass or more and 30 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the polymer having an active terminal. The amount of the deactivator added is preferably 5 parts by mass or more in order to suppress side reactions caused by lithium having polymerization activity, and is preferably 50 parts by mass or less in terms of production costs.

[0039] [Neutralizing Agent Addition Step] The neutralizing agent addition step is a step of adding a neutralizing agent to a solution of the resulting conjugated diene polymer after the polymerization reaction or coupling reaction to neutralize lithium hydroxide. Lithium hydroxide is produced, for example, by the reaction of an organic lithium initiator with a deactivator. The neutralizing agent is not particularly limited, and examples include carboxylic acids such as benzoic acid, stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, mainly 10 carbon atoms), aqueous solutions of inorganic acids, and carbon dioxide. Lithium reacted with the deactivator tends to deteriorate the aforementioned Δb value by reacting with the stabilizer described below. Adding a neutralizing agent allows the neutralizing agent to react with lithium, preventing the lithium reacting with the stabilizer, thereby suppressing deterioration of Δb value. Carbon dioxide is preferred as the neutralizing agent, as it prevents unreacted neutralizing agent from remaining in the conjugated diene polymer.

[0040] (Amount of Neutralizing Agent Added) In the production method of this embodiment, the amount of the neutralizing agent added is not particularly limited, but is preferably 0.5 mol or more and 5.0 mol or less, more preferably 0.8 mol or more and 3.0 mol or less, and even more preferably 1.0 mol or more and 2.0 mol or less, relative to 1 mol of the polymerization initiator. The amount of the neutralizing agent added is preferably 0.5 mol or more in terms of appearance, and is preferably 5.0 mol or less in terms of production costs.

[0041] [Stabilizer Addition Step] The stabilizer addition step is a step of adding a stabilizer to a solution of the conjugated diene polymer obtained after the polymerization reaction or the coupling reaction. Examples of the stabilizer include stabilizers, and it is preferable to add a stabilizer to the resulting conjugated diene polymer from the viewpoint of suppressing gel formation due to the thermal history of an extruder or the like and improving stability during processing. The stabilizer is not particularly limited, and known stabilizers such as phenolic stabilizers, phosphorus-based stabilizers, and sulfur-containing phenolic compounds can be used. Only one type of compound that can be used as a stabilizer may be used, or two or more types may be used in combination. The phenol-based stabilizer is not particularly limited, and examples thereof include 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-i-butylphenol, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, 2,2-methylene-bis-(4-methyl-6-tert-butylphenol), 2,2-ethylene-bis-(4-methyl-6-tert-butylphenol), etc. The phosphorus-based stabilizer is not particularly limited, and examples thereof include tris(nonylphenyl)phosphite, tris-(2,4-di-tert-butylphenyl)phosphite, cyclic neopentanetetraylbis(octadecylphosphite), etc.

[0042] When the neutralizing agent is carbon dioxide gas, the amounts of the phenolic stabilizer and the phosphorus-based stabilizer added are each preferably 0.15 to 5.0 parts by mass, more preferably 0.20 to 3.0 parts by mass, even more preferably 0.25 to 1.0 parts by mass, and even more preferably 0.45 to 0.8 parts by mass, relative to 100 parts by mass of the conjugated diene polymer. When the neutralizing agent is other than carbon dioxide gas, the amounts of the phenolic stabilizer and the phosphorus-based stabilizer added are each preferably 0.01 to 5.0 parts by mass, more preferably 0.1 to 3.0 parts by mass, even more preferably 0.25 to 1.0 parts by mass, and even more preferably 0.45 to 0.8 parts by mass, relative to 100 parts by mass of the conjugated diene polymer. From the viewpoint of reducing the cumulative amount of emitted ink and the Δb value, the amount of the phenolic stabilizer and the phosphorus-based stabilizer added is preferably 0.01 parts by mass or more, and from the viewpoint of production costs, 5.0 parts by mass or less.

[0043] The sulfur-containing phenolic stabilizer is not particularly limited, and examples thereof include 2,4-bis(n-octylthiomethyl)-6-methylphenol, 2,4-bis(2',3'-dihydroxypropylthiomethyl)-3,6-dimethylphenol, and 2,4-bis(2'-acetyloxyethylthiomethyl)-3,6-dimethylphenol. The amount of the sulfur-containing phenolic stabilizer added is preferably 0.01 to 2.0 parts by mass, more preferably 0.10 to 1.5 parts by mass, and even more preferably 0.13 to 1.0 parts by mass, relative to 100 parts by mass of the conjugated diene polymer. From the viewpoint of reducing the integrated light emission and the Δb value, the amount of the sulfur-containing phenolic stabilizer added is preferably 0.01 parts by mass or more, and from the viewpoints of production cost and odor, it is preferably 2.0 parts by mass or less.

[0044] The order of the deactivator addition step, neutralizer addition step, and stabilizer addition step is preferably the deactivator addition step, neutralizer addition step, and stabilizer addition step. The polymerization-active lithium reacts with the deactivator, and the reaction product (lithium hydroxide) reacts with the neutralizer, thereby suppressing the reaction between lithium and the stabilizer. Suppressing the reaction between lithium and the stabilizer improves Δb. Furthermore, suppressing the reaction between lithium and the stabilizer allows for the production of a conjugated diene-based polymer containing the stabilizer in the exact amount added.

[0045] <Method for Obtaining Conjugated Diene Polymer> In the production method of the present embodiment, the method for obtaining the conjugated diene polymer from the polymer solution is not particularly limited, and any known method can be used. Examples include a method in which the solvent is separated by steam stripping or the like, the polymer is filtered, and then the polymer is dehydrated and dried to obtain the polymer, a method in which the polymer is concentrated in a flashing tank and then devolatilized using a vent extruder or the like, and a method in which the polymer is directly devolatilized using a drum dryer or the like.

[0046] (Hydrogenation Reaction) The production method of this embodiment may include a step of further hydrogenating the conjugated diene polymer in an inert solvent to convert all or part of the double bonds into saturated hydrocarbons. The inclusion of such a step is preferable from the viewpoints of improving heat resistance and weather resistance and preventing deterioration of the product when processed at high temperatures, and as a result, the product exhibits even better performance in various applications such as automotive applications. More specifically, the hydrogenation rate of the unsaturated double bonds based on butadiene (hereinafter sometimes referred to as the "hydrogenation rate") can be selected as desired depending on the purpose and is not particularly limited.

[0047] When used as a resin-modifying rubber such as an impact-resistant styrene-based resin composition, it is preferable that the double bonds of the butadiene moiety remain partially. From this perspective, the hydrogenation rate of the butadiene moiety in the conjugated diene polymer is preferably 3% to 70% or less, more preferably 5% to 65% or less, and even more preferably 10% to 60% or less. When the conjugated diene polymer contains a monomer unit based on an aromatic vinyl compound, the hydrogenation rate of the aromatic double bonds based on the aromatic vinyl compound is not particularly limited, but is preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less. The hydrogenation rate can be determined using a nuclear magnetic resonance (NMR) spectrometer or the like. The hydrogenation method is not particularly limited, and known methods can be used. A particularly suitable hydrogenation method is to blow gaseous hydrogen into a polymer solution in the presence of a catalyst. Examples of the catalyst include heterogeneous catalysts such as catalysts in which a noble metal is supported on a porous inorganic material; catalysts in which a salt of nickel, cobalt, or the like is solubilized and reacted with an organoaluminum, and homogeneous catalysts such as catalysts using metallocenes such as titanocene. Among these, titanocene catalysts are particularly preferred from the viewpoint of allowing selection of mild hydrogenation conditions. Furthermore, the hydrogenation of aromatic groups can be carried out using a supported noble metal catalyst. Specific examples of hydrogenation catalysts include (1) supported heterogeneous hydrogenation catalysts in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, diatomaceous earth, or the like; (2) so-called Ziegler-type hydrogenation catalysts that use a transition metal salt such as an organic acid salt or acetylacetone salt of Ni, Co, Fe, Cr, or the like and a reducing agent such as organoaluminum; and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, or the like. For example, known hydrogenation catalysts described in JP-B Nos. 42-8704, 43-6636, 63-4841, 1988, 1-37970, 1-53851, 2-9041, and JP-A No. 8-109219 can be used. A preferred hydrogenation catalyst is a reaction mixture of a titanocene compound and a reducing organometallic compound.

[0048] The conjugated diene polymer composition of this embodiment also includes a conjugated diene polymer composition containing 0.01 to 0.5 parts by mass of an organic fatty acid relative to 100 parts by mass of the conjugated diene polymer. The organic fatty acid is not particularly limited, and examples thereof include capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, vaccenic acid, linoleic acid, succinic acid, citric acid, and malic acid. From the viewpoints of ensuring mold releasability of the rubber in the extruder while not inhibiting radical polymerization during production of the impact-resistant styrene-based resin composition, the content of the organic fatty acid is preferably 0.01 to 0.5 parts by mass in total relative to 100 parts by mass of the conjugated diene polymer.

[0049] [Impact-Resistant Styrenic Polymer Composition] When the conjugated diene polymer of the present embodiment is used for modifying a styrene-based resin, such as an impact-resistant polystyrene-based polymer composition, the conjugated diene polymer of the present embodiment may be used alone or in combination with a linear butadiene-based polymer or a styrene-butadiene copolymer.

[0050] The impact-resistant styrene polymer composition can be produced by, for example, bulk polymerization using the conjugated diene polymer of this embodiment. Specifically, styrene and the conjugated diene polymer of this embodiment are added to a reactor equipped with a stirrer, and a stabilizer, a chain transfer agent, and the like are added as needed, followed by stirring to dissolve the mixture and prepare a pre-polymerization solution. A catalyst such as di-tert-butyl peroxide is added to the pre-polymerization solution as needed, and the mixture is heated to polymerize, thereby obtaining an impact-resistant styrene polymer composition.

[0051] The method for producing the impact-resistant styrene-based resin composition is not particularly limited as long as the constituent requirements of this embodiment are satisfied, and any known method can be used. Usually, a preferred method is to dissolve the conjugated diene polymer (1) and the random copolymer (2) in a mixture of an aromatic vinyl monomer or a monomer copolymerizable with the aromatic vinyl monomer to obtain a rubber solution, and then graft-polymerize the rubber solution by carrying out a polymerization step such as bulk polymerization, bulk suspension polymerization, or solution polymerization while stirring the rubber solution so as to apply a shearing stress, thereby obtaining an impact-resistant styrene-based resin composition in which rubber particles are dispersed in a matrix composed of an aromatic vinyl monomer or a copolymer of the aromatic vinyl monomer and a monomer copolymerizable with the aromatic vinyl monomer.

[0052] Examples of aromatic vinyl monomers used in the production method for impact-resistant styrene-based resin compositions include α-alkyl-substituted styrenes such as styrene, vinylnaphthalene, α-methylstyrene, α-ethylstyrene, and α-methyl-p-methylstyrene; nuclear-alkyl-substituted styrenes such as m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylvinylbenzene, and p-tert-butylstyrene; halogenated styrenes such as monochlorostyrene, dichlorostyrene, tribromostyrene, and tetrabromostyrene; p-hydroxystyrene, o-methoxystyrene, and the like. These are used alone or as a mixture of two or more. Of these, styrene, α-methylstyrene, and p-methylstyrene are preferred.

[0053] The copolymerizable monomer other than the aromatic vinyl monomer may be selected from unsaturated nitrile monomers, (meth)acrylic acid esters, and other copolymerizable monomers.

[0054] Examples of unsaturated nitrile monomers include, but are not limited to, acrylonitrile and methacrylonitrile. These may be used alone or in a mixture of two or more. Acrylonitrile is particularly preferred. Examples of (meth)acrylic acid esters include, but are not limited to, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, dodecyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, dodecyl methacrylate, and cyclohexyl methacrylate. These may be used alone or in a mixture of two or more. Methyl methacrylate is particularly preferred. Other copolymerizable monomers include, but are not limited to, acrylic acid, methacrylic acid, vinyl acetate, maleic anhydride, N-methylmaleimide, and N-phenylmaleimide.

[0055] In addition, in the method for producing an impact-resistant styrene-based resin composition, polymerization may be carried out by adding an inert solvent to the above-mentioned aromatic vinyl monomer or a mixed solution of a monomer copolymerizable with the aromatic vinyl monomer. Examples of the inert solvent include, but are not limited to, ethylbenzene and toluene. Alternatively, one or more polar solvents such as methyl ethyl ketone and cyclohexanone may be used. The amount of these inert solvents is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, per 100 parts by mass of the aromatic vinyl monomer mixed solution in which the conjugated diene polymer (1) and the random copolymer (2) are dissolved.

[0056] In the method for producing the impact-resistant styrene-based resin composition of the present embodiment, when radically polymerizing the aromatic vinyl monomer in which the conjugated diene polymer (1) or the random copolymer (2) is dissolved, or the mixed solution of the aromatic vinyl monomer and a monomer copolymerizable with the aromatic vinyl monomer, the polymerization may be carried out in the presence of an organic peroxide or an azo compound.

[0057] Examples of organic peroxides include, but are not limited to, peroxyketals such as 1,1-bis(t-butylperoxy)cyclohexane and 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane; dialkyl peroxides such as di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and dicumyl peroxide; diacyl peroxides such as benzoyl peroxide, m-toluoyl peroxide and lauroyl peroxide; dimyristyl peroxide; Examples of suitable organic peroxides include peroxydicarbonates such as diisopropyl peroxydicarbonate and diisopropyl peroxydicarbonate; peroxyesters such as t-butylperoxyisopropylcarbonate, t-butylperoxyacetate, di-t-butyldiperoxyisophthalate, and t-butylperoxybenzoate; ketone peroxides such as cyclohexanone peroxide and methyl ethyl ketone peroxide; and hydroperoxides such as p-menthahydroperoxide, t-butylhydroperoxide, and cumene hydroperoxide. Examples of suitable azo compounds include, but are not limited to, azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These compounds may be used singly or in combination. The amount of the organic peroxide or azo compound used is preferably in the range of 10 to 1,000 ppm in the mixed solution of the aromatic vinyl monomer or the aromatic vinyl monomer and a copolymerizable monomer.

[0058] In the method for producing an impact-resistant styrene-based resin composition, it is preferable to use a known chain transfer agent in the graft polymerization step described above. Examples of the chain transfer agent include, but are not limited to, mercaptans such as n-dodecyl mercaptan, tert-dodecyl mercaptan, α-methylstyrene dimer, 1-phenylbutene-2-fluorene, dipentene, and chloroform, terpenes, and halogen compounds.

[0059] The impact-resistant styrene-based resin composition may contain known antioxidants and ultraviolet stabilizers. Examples of the antioxidant include, but are not limited to, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,6-di-t-butyl-4-methylphenol, 2-(1-methylcyclohexyl)-4,6-dimethylphenol, 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(6-t-butyl-3-methylphenol), 2,4-bis[(octylthio)methyl]-o-cresol, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], tris(dinonylphenyl)phosphite, and tris-(2,4-di-t-butylphenyl)phosphite. The amount of the antioxidant added is preferably 0.01 to 5 parts by mass, and more preferably 0.1 to 2 parts by mass, per 100 parts by mass of the impact resistant styrene resin composition of this embodiment.

[0060] Examples of UV stabilizers include, but are not limited to, triazole-based stabilizers such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole and 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole; hindered amine-based stabilizers such as bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate; and p-t-butylphenyl salicylate and 2,2'-dihydroxy-4-methoxybenzophenone. Particularly preferred are triazole-based stabilizers and hindered amine-based stabilizers, either alone or in combination. The amount of these UV stabilizers added is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 2 parts by mass, per 100 parts by mass of the impact-resistant styrene-based resin composition of this embodiment.

[0061] If necessary, the impact-resistant styrene-based resin composition may contain a conventional internal lubricant such as liquid paraffin, mineral oil, organic polysiloxane, etc. For example, 0.005 to 10 parts by mass of polydimethylsiloxane, which is an organic polysiloxane, may be added to 100 parts by mass of the impact-resistant styrene-based resin composition.

[0062] The impact-resistant styrene-based resin composition of this embodiment may be blended with a flame retardant and a flame retardant aid, as needed, to impart flame retardancy. Conventional flame retardants can be used as the flame retardant, and halogen-based flame retardants, phosphorus-based flame retardants, and the like are effective. Examples of the flame retardant include, but are not limited to, decabromodiphenyl oxide, tetrabromobisphenol A, tetrabromobisphenol A oligomer, tris-(2,3-dibromopropyl-1)isocyanurate, ammonium phosphate, red phosphorus, and tricresyl phosphate. Examples of the flame retardant aid include, but are not limited to, antimony trioxide, antimony pentoxide, sodium antimonate, antimony trichloride, antimony pentachloride, zinc borate, barium metaborate, and zirconium oxide. The blending amount of the flame retardant is preferably 5 to 40 parts by mass per 100 parts by mass of the impact resistant styrene-based resin composition of this embodiment, and the blending amount of the flame retardant aid is preferably 2 to 20 parts by mass per 100 parts by mass of the impact resistant styrene-based resin composition of this embodiment.

[0063] The impact-resistant styrene-based resin composition of this embodiment may contain various additives, such as lubricants, mold release agents, fillers, antistatic agents, and colorants, as needed. Furthermore, other thermoplastic resins, such as general-purpose polystyrene, AS resin, ABS resin, AES resin, MBS resin, polyphenylene ether, polycarbonate, styrene-butadiene copolymer, methyl methacrylate-styrene copolymer resin, maleic anhydride-styrene copolymer resin, polyamide resin, and polyester resin, may also be mixed. Addition of these resins imparts heat resistance, rigidity, impact resistance, appearance, paintability, and the like, and one or more types may be used depending on the application.

[0064] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples in any way. Samples were analyzed by the following methods. (1) Mooney Viscosity Mooney viscosity was measured using a Mooney viscometer (Ueshima Seisakusho Co., Ltd., "VR1132") in accordance with JIS K6300 (ISO289-1). The measurement temperature was 100°C. First, the sample was preheated for 1 minute, and the rotor was rotated at 2 rpm. The torque was measured after 4 minutes to determine the Mooney viscosity (ML １＋４ )

[0065] (2) Viscosity of 5% by mass styrene solution (SV) 2.385 g of a sample was dissolved in 50 mL of styrene, and the SV was measured at 25° C. using a Cannon-Fenske viscometer (viscometer number: 350) manufactured by Shibata Scientific Co., Ltd. However, since only sample B had a high SV, the SV was measured using a Cannon-Fenske viscometer (viscometer number: 400) manufactured by Shibata Scientific Co., Ltd.

[0066] (3) Molecular weight distribution (Mw / Mn) A chromatogram was measured using a GPC measuring device (HLC-8320GPC manufactured by Tosoh Corporation) connected to three columns packed with polystyrene gel, and the mass average molecular weight (Mw) and number average molecular weight (Mn) were determined based on a calibration curve using standard polystyrene, and the molecular weight distribution (Mw / Mn) was calculated. Tetrahydrofuran (THF) was used as the eluent. The column used consisted of three columns connected in series: a guard column: TSKguardcolumn SuperMP(HZ)-H manufactured by Tosoh Corporation, and a column: TSKgel SuperMultipore HZ-H manufactured by Tosoh Corporation. An RI detector ("HLC8320" manufactured by Tosoh Corporation) was used under conditions of an oven temperature of 40°C and a THF flow rate of 1.0 mL / min. 10 mg of the sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 200 μL of the measurement solution was injected into a GPC measurement device and measured.

[0067] (4) P Content The P content in the conjugated diene polymers of the examples and comparative examples described below was measured using an inductively coupled plasma (ICP, Inductive Coupled Plaza, manufactured by Shimadzu Corporation, device name: ICPS-7510). First, the conjugated diene polymer was completely dissolved with sulfuric acid and nitric acid, and an aqueous solution containing metal components was sprayed into argon plasma. The intensities of the wavelengths of light specific to the various metal elements emitted from the solution were measured, and the amount of P (ppm by mass) contained in 100 parts by mass of the conjugated diene polymer was determined by a calibration curve method.

[0068] (5) Accumulated luminescence quantity A 1 mm thick press-molded sample was cut into a 1 cm x 1 cm piece and placed in a 20 mm diameter aluminum dish. Measurement was performed in accordance with ISO 4765: 2022 using a weak luminescence image measuring device (CLA-FS4) and a sample chamber (CLS-SH1) manufactured by Tohoku Electronics Industries Co., Ltd. In an oxygen atmosphere (50 ml / min), the temperature was increased from 50°C to 200°C at a rate of 20°C / min, and then maintained at 200°C for 10 minutes from the start of the temperature increase, and the accumulated luminescence quantity for 10 minutes was calculated.

[0069] (6) Δb Value A sample was cut into a size of 5 cm in diameter and 15 mm in height, and placed in a stainless steel Petri dish also having a diameter of 5 cm and a height of 15 mm, followed by heating at 160°C for 2 hours. The b values ​​were measured before and after heating, and the Δb value was calculated based on the following formula: Δb Value = (b Value after Heating) - (b Value before Heating) The b value was measured in the thickness direction by reflection measurement using a color difference meter ZE6000 manufactured by Nippon Denshoku Kogyo Co., Ltd.

[0070] (7) Glossiness Using an injection-molded test piece (3 cm x 3 cm x 3 mm), the glossiness (incident angle 60°) of the gate and end gate portions was measured in accordance with ASTM D-523, and the average value was calculated.

[0071] (8) Izod Impact Strength: Measurement was carried out in accordance with ISO 180 using an injection-molded test piece (with a notch) having a thickness of 4.0 mm.

[0072] (9) Appearance The b value of an injection-molded test piece (3 cm x 3 cm x 3 mm) was measured in the thickness direction by reflection measurement using a color difference meter ZE6000 manufactured by Nippon Denshoku Kogyo Co., Ltd.

[0073] (10) Water Content The water content of the conjugated diene polymers in the examples and comparative examples described below was measured in accordance with ISO 248-2. If the water content was more than 0.5% by mass, there was a risk that polymerization of the impact-resistant styrene-based polymer would be inhibited. Therefore, after confirming that the water content was 0.5% by mass or less, polymerization of the impact-resistant styrene-based polymer was carried out.

[0074] Example 1 An autoclave (a tank-type reactor equipped with a stirrer) having an internal volume of 11 L, an internal height-to-diameter ratio (L / D) of 4, an inlet at the bottom, an outlet at the top, and a stirrer and a jacket for temperature control was used as a polymerization reactor. 1,3-butadiene, from which impurities such as moisture had been removed, were mixed at 30.6 g / min, 1,2-butadiene at 0.014 g / min, and n-hexane at 149.2 g / min, and continuously fed to the bottom of the reactor. Furthermore, n-butyllithium was fed as a polymerization initiator to the bottom of the reactor at a rate of 0.243 mmol / min, and the polymerization reaction was continued so that the internal temperature at the reactor outlet reached 114°C (polymerization step). Water was continuously added as a terminator to the active end-containing conjugated diene polymer solution flowing out from the top of the reactor in an amount of 10 g per 100 g of butadiene polymer, and the mixture was mixed using a static mixer (terminator addition step). Next, carbon dioxide gas as a neutralizing agent was continuously added under the condition that the molar ratio relative to the added n-butyllithium was 1:1.0, and the mixture was mixed in a static mixer (neutralizing agent addition step). Finally, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate as stabilizer 1 and 2,4-bis[(octylthio)methyl]-o-cresol as stabilizer 2 were continuously added in amounts of 0.50 g and 0.15 g, respectively, per 100 g of butadiene-based polymer, and the mixture was mixed in a static mixer to terminate the polymerization reaction (stabilizer addition step). The resulting conjugated diene-based polymer solution was desolvated by steam stripping, and the remaining water was removed for 10 minutes using an open roll to obtain Sample A. The analytical results of Sample A are shown in Table 1.

[0075] [Examples 2 to 5, Example 7, Comparative Example 2] The procedures were the same as in Example 1, and the respective conditions were as shown in Table 1. The analytical results of the obtained Samples B to E, G, and I are shown in Table 1.

[0076] Example 6 Using a polymerization reactor similar to that used in the polymerization step of Example 1, 1,3-butadiene, 1,2-butadiene, and n-hexane were mixed at 22.9 g / min, 0.014 g / min, and 95.8 g / min, after removing impurities such as moisture, and the resulting mixture was continuously fed to the bottom of the reactor. Furthermore, n-butyllithium was fed as a polymerization initiator to the bottom of the first reactor at a rate of 0.228 mmol / min, and the polymerization reaction was continued so that the internal temperature at the reactor outlet was 90°C (polymerization step). The temperature of the second reactor was maintained at 90°C, and the linear butadiene-based polymer solution flowing out of the top of the first reactor was continuously fed from the bottom. Furthermore, tetramethoxysilane, as a coupling agent, was added to the bottom of the second reactor at a rate of 0.046 mmol / min, and a coupling reaction was carried out (coupling step). To the branched butadiene polymer solution flowing out from the top of the second reactor, water as a terminator was continuously added in an amount of 20 g per 100 g of butadiene polymer, and the mixture was mixed in a static mixer (terminator addition step). Subsequently, carbon dioxide gas as a neutralizing agent was continuously added under conditions where the molar ratio relative to the added n-butyllithium was 1:1.0, and the mixture was mixed in a static mixer (neutralizing agent addition step). Finally, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate as stabilizer 1 and 2,4-bis[(octylthio)methyl]-o-cresol as stabilizer 2 were continuously added in amounts of 0.50 g and 0.15 g, respectively, per 100 g of butadiene polymer, and the mixture was mixed in a static mixer to terminate the polymerization reaction (stabilizer addition step). The resulting conjugated diene polymer solution was subjected to steam stripping to remove the solvent, and the remaining water was removed with an open roll for 10 minutes to obtain Sample F.

[0077] Example 8 Using a polymerization reactor similar to that used in the polymerization step of Example 1, 1,3-butadiene, 1,2-butadiene, and n-hexane were mixed at 42.2 g / min, 0.008 g / min, and 198.8 g / min, respectively, after removing impurities such as moisture. The mixture was continuously fed to the bottom of the reactor. Furthermore, n-butyllithium was fed as a polymerization initiator to the bottom of the first reactor at a rate of 1.20 mmol / min, and the polymerization reaction was continued so that the internal temperature at the reactor outlet was 100°C (polymerization step). The temperature of the second reactor was maintained at 100°C, and the linear butadiene-based polymer solution flowing out of the top of the first reactor was continuously fed from the bottom. Furthermore, tetramethoxysilane, as a coupling agent, was added to the bottom of the second reactor at a rate of 0.31 mmol / min, and a coupling reaction was carried out (coupling step). To the branched butadiene polymer solution flowing out from the top of the second reactor, water as a terminator was continuously added in an amount of 20 g per 100 g of butadiene polymer, and the mixture was mixed in a static mixer (terminator addition step). Subsequently, carbon dioxide gas as a neutralizing agent was continuously added under conditions where the molar ratio relative to the added n-butyllithium was 1:1.0, and the mixture was mixed in a static mixer (neutralizing agent addition step). Finally, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate as stabilizer 1 and 2,4-bis[(octylthio)methyl]-o-cresol as stabilizer 2 were continuously added in amounts of 0.50 g and 0.15 g, respectively, per 100 g of butadiene polymer, and the mixture was mixed in a static mixer to terminate the polymerization reaction (stabilizer addition step). The resulting conjugated diene polymer solution was subjected to steam stripping to remove the solvent, and the remaining water was removed with an open roll for 10 minutes to obtain Sample L.

[0078] [Example 9] The steps from the polymerization step to the stabilizer addition step were carried out in the same manner as in Example 1. The obtained conjugated diene polymer solution was subjected to steam stripping to remove the solvent, and polyoxyethylene alkyl ether phosphate was added in an amount of 0.3 g per 100 g of the conjugated diene polymer, and the remaining water was removed using an open roll to obtain Sample M. The time required to remove the remaining water using an open roll to a water content of 0.5% by mass was 40 minutes.

[0079] Comparative Example 1 Polymerization of an active end-containing conjugated diene polymer was carried out in the same manner as in Example 1. Without adding a neutralizing agent or a terminator, Stabilizer 1 and Stabilizer 2 were continuously added to the active end-containing butadiene polymer solution flowing out from the top of the reactor so that the amounts of Stabilizer 1 and Stabilizer 2 were 0.10 g and 0.10 g, respectively, per 100 g of the active end-containing conjugated diene polymer, and the mixture was mixed in a static mixer to terminate the polymerization reaction. The resulting conjugated diene polymer solution was desolvated by steam stripping, and the remaining water was removed for 10 minutes using an open roll to obtain Sample H. The analytical results of Sample H are shown in Table 1.

[0080] Comparative Example 3 The procedure was the same as in Comparative Example 1, and the conditions were as shown in Table 1. The analysis results of the obtained sample J are shown in Table 1.

[0081] Comparative Example 4 Polymerization of an active end-containing conjugated diene polymer was carried out in the same manner as in Example 1. Stabilizer 1 and Stabilizer 2 were continuously added to the active end-containing butadiene polymer solution flowing out from the top of the reactor in amounts of 0.50 g and 0.15 g per 100 g of conjugated diene polymer, respectively, and mixed in a static mixer (stabilizer addition step). Subsequently, water was continuously added as a terminator in an amount of 10.0 g per 100 g of active end-containing conjugated diene polymer, and mixed in a static mixer (terminator addition step). Furthermore, carbon dioxide gas was continuously added at a molar ratio of 1:1.0 relative to the added n-butyllithium, and mixed in a static mixer (neutralizer addition step). The resulting conjugated diene polymer solution was desolvated by steam stripping, and the remaining water was removed for 10 minutes using an open roll to obtain Sample K. The analytical results of Sample K are shown in Table 1.

[0082]

[0083] <Synthesis of Impact-Resistant Styrenic Resin Composition> An impact-resistant styrene-based resin composition was produced by the following bulk polymerization method. 91.76% by mass of styrene and 7.97% by mass of Sample A were added to a reactor equipped with a stirrer. Next, 0.23% by mass of n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate as a stabilizer and 0.02% by mass of t-dodecyl mercaptan as a chain transfer agent were added and dissolved with stirring to prepare a prepolymerization solution. To this was added 0.02% by mass of di-tert-butyl peroxide, and polymerization was carried out at 105°C for 6 hours with stirring. Subsequently, polymerization was carried out at 135°C, 150°C, and 170°C for 2 hours each without stirring, and then heat treatment was carried out at 220°C for 30 minutes. After cooling, the mixture was pulverized using a 5 mmφ mesh pulverizer and dried under reduced pressure at 80°C for 3 hours to obtain an impact-resistant styrene-based resin composition. The pulverized product was injection molded (mold temperature 60°C, nozzle tip temperature 220°C) to prepare test pieces, and the physical properties were measured. The physical properties of the obtained impact-resistant styrene-based resin compositions are shown in Table 1. Impact-resistant styrene-based resin compositions were obtained using samples B to M, respectively, in the same procedure.

[0084] Samples A to G, L and M gave impact-resistant styrene resin compositions that were excellent in appearance and had an excellent balance between gloss and impact strength.

Claims

1. The cumulative luminescence of weak light emitted by a chemical reaction is 150 x 10 ５ cps or less, and a Δb value before and after heating at 160°C for 2 hours of 4.0 or less.

2. The conjugated diene polymer according to claim 1, wherein the viscosity (SV) of the conjugated diene polymer in a 5% by mass styrene solution measured at 25°C is 50<SV≦75 (mPa·s).

3. The conjugated diene polymer according to claim 1, wherein the viscosity (SV) of the conjugated diene polymer in a 5% by mass styrene solution measured at 25°C is 75<SV≦280 (mPa·s).

4. The conjugated diene polymer according to claim 1, wherein the conjugated diene polymer has a P (phosphorus) content of 20 ppm or less.

5. The conjugated diene polymer according to claim 1, wherein the Δb value is 3.0 or less.

6. The cumulative light emission amount is 40 x 10 ５ The conjugated diene polymer according to claim 1, having a viscosity of 100 cps or less.

7. The conjugated diene polymer according to claim 1, wherein the molecular weight distribution (Mw / Mn) of the conjugated diene polymer measured by GPC (gel permeation chromatography) is 1.5 or more and 2.5 or less.

8. The conjugated diene polymer according to claim 1, wherein the conjugated diene polymer is polybutadiene.

9. The conjugated diene polymer according to claim 1, wherein the conjugated diene polymer is a polybutadiene for an impact resistant styrene polymer composition.

10. A method for producing a conjugated diene polymer, comprising a polymerization step of continuously supplying 1,3-butadiene or 1,3-butadiene and an aromatic vinyl compound, and an inert solvent to a polymerization reactor, and continuously polymerizing using an organolithium compound as an initiator to obtain an active end-containing conjugated diene polymer, and the following steps (1) to (3): (1) a deactivator addition step of adding a deactivator that deactivates the active polymerization ends of the active end-containing conjugated diene polymer, (2) a neutralizer addition step of adding a neutralizer that neutralizes lithium hydroxide, and (3) a stabilizer addition step of adding a stabilizer.

11. The method for producing a conjugated diene polymer according to claim 10, wherein the deactivator addition step, the neutralizing agent addition step, and the stabilizer addition step are carried out in this order.

12. An impact-resistant styrene polymer composition comprising the conjugated diene polymer according to any one of claims 1 to 9.

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