JP2014210866A - Method for producing conjugated diene polymer, conjugated diene polymer obtained by the method and method for preventing coloration of conjugated diene polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a conjugated diene polymer which can prevent oxidation of a polymer without influencing an environment, reduce residual chlorine which is a co-catalyst residue and prevent coloration of a conjugated diene polymer without influencing other components when formed into a rubber composition, and to provide a conjugated diene polymer obtained by the method and a method for preventing coloration of the conjugated diene polymer.SOLUTION: There is provided a method for producing a conjugated diene polymer in which (1) water and (2) a carboxylic acid salt having a chelating action are added after polymerization of a diene-based monomer.

Description

  The present invention relates to a method for producing a conjugated diene polymer that can prevent coloring of the conjugated diene polymer by adding a carboxylate having a chelating action, the conjugated diene polymer obtained thereby, and the conjugated diene. The present invention relates to a method for preventing coloration of a polymer.

  Conventionally, many compounds such as various catalysts, promoters, and antioxidants are often added to the conjugated diene polymer in the production process. In particular, the addition of an antioxidant prevents the product from deteriorating, so such an additive is essential. However, when there are many kinds and amounts of additives, side effects such as coloring and odor often occur, and unexpected problems may occur.

  In particular, when a side effect of coloring occurs, it often becomes a big problem for applications in which transparency is required for products, and many solutions have been attempted so far.

  For example, Patent Document 1 discloses a method for recovering a polymer by adding a predetermined phosphoric acid ester and water (ROH) to obtain a transparent polymer having excellent color tone and moist heat resistance and excellent in devitrification resistance. Is described.

  Moreover, in patent document 2, by superposing | polymerizing 1 or more types of phenolic compounds after superposition | polymerization of a butadiene rubber, it adjusts so that pH value is the range of 4-11, and oxygen content may be 0-0.3 ppm. , Providing stable and colorless polybutadiene rubber.

International Publication No. 2006/088160 Special table 2003-535926

  However, when a phosphorus-based additive is added as in the method described in Patent Document 1, phosphoric acid is generated and the influence on the environment becomes a problem. Moreover, in the method described in Patent Document 2, it is necessary to adjust the oxygen content of moisture, and there is a problem that there are many restrictions on industrialization.

  The present invention has been made in view of the above problems, can prevent oxidation of the polymer without affecting the environment, and can further reduce residual chlorine which is a cocatalyst residue. A process for producing a conjugated diene polymer that can prevent coloring of the conjugated diene polymer without affecting other components, and a conjugated diene polymer obtained thereby, and a method for preventing coloration of the conjugated diene polymer The purpose is to provide.

  As a result of diligent studies to achieve the above object, the present inventors have succeeded in polymerizing a diene monomer and then adding water and a carboxylate having a chelating action without affecting the environment. It is possible to prevent oxidation of the coal, further reduce residual chlorine as a cocatalyst residue, and prevent coloring of the conjugated diene polymer without affecting other components when the rubber composition is formed. And found the present invention. That is, the present invention relates to a method for producing a conjugated diene polymer, wherein (1) water and (2) a carboxylate having a chelating action are added after polymerization of a diene monomer.

  In the production method of the present invention, it is preferable that the (2) carboxylic acid salt having a chelating action is previously dissolved in (1) water and added as a carboxylic acid aqueous solution having a chelating action. It is preferable that the carboxylate salt having an ethylenediaminetetraacetate salt.

  In the production method of the present invention, the conjugated diene polymer preferably has a 1,4-cis structure of 80 to 99% and a 1,2-vinyl structure of 0.5 to 20%. The diene polymer is preferably produced by polymerization using a catalyst comprising a transition metal catalyst and an organoaluminum promoter.

  The present invention also relates to a conjugated diene polymer produced by the production method.

  The present invention also relates to a coloring prevention method for a conjugated diene polymer, which comprises introducing a carboxylic acid aqueous solution having a chelating action after polymerization of a diene monomer.

  As described above, according to the present invention, the oxidation of the polymer can be prevented without affecting the environment, and the residual chlorine as the cocatalyst residue can be reduced. A method for producing a conjugated diene polymer capable of preventing coloring of the conjugated diene polymer without affecting the components, a conjugated diene polymer obtained thereby, and a method for preventing coloration of the conjugated diene polymer can be provided. .

  The method for producing a conjugated diene polymer of the present invention is characterized in that (1) water and (2) a carboxylate having a chelating action are added after polymerization of a diene monomer. Hereinafter, a suitable embodiment is described in detail about the manufacturing method of the conjugated diene polymer of the present invention.

  As a method for producing a conjugated diene polymer according to this embodiment, (A) a diene monomer is dissolved in (B) an organic solvent, (C) water is dissolved therein, and then (D) a transition metal catalyst and (E) An organoaluminum cocatalyst is added for polymerization, and after polymerization, (1) water and (2) a carboxylate having a chelating action, and in some cases (F) a polymerization terminator and (G) an antioxidant. It is preferable to add.

(A) Diene monomer In the present embodiment, examples of the diene monomer include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and the like. Is mentioned. These may be used individually by 1 type, may mix 2 or more types, and also may be used by copolymerizing with other dienes, such as 1, 3- hexadiene. Of these, 1,3-butadiene is preferred.

(B) Organic solvent Examples of the organic solvent used in this embodiment include aromatic hydrocarbons such as toluene, benzene, and xylene, aliphatic hydrocarbons such as n-hexane, butane, heptane, and pentane, cyclopentane, and cyclohexane. Aliphatic hydrocarbons, olefinic hydrocarbons such as 1-butene, cis-2-butene, trans-2-butene, hydrocarbon solvents such as mineral spirit, solvent naphtha, kerosene, and halogenated carbonization such as methylene chloride Examples thereof include hydrogen-based solvents. Further, 1,3-butadiene itself may be used as a polymerization solvent. The organic solvent is preferably a non-aromatic hydrocarbon, particularly cyclohexane.

(D) Transition metal catalyst As a transition metal catalyst which can be used for this embodiment, a cobalt-type catalyst is mentioned. As the cobalt-based catalyst, a cobalt salt or complex is preferably used. Specifically, cobalt salts such as cobalt octaate, cobalt chloride, cobalt bromide, cobalt nitrate, cobalt octylic acid (ethylhexanoic acid), cobalt naphthenate, cobalt acetate, cobalt malonate and the like are particularly preferable. . Further, cobalt bisacetylacetonate, trisacetylacetonate; acetoacetic acid ethyl ester cobalt; cobalt base pyridine complex, organic base complex such as picoline complex, or ethyl alcohol complex. Of these, cobalt octaate is particularly preferable.

The amount of the cobalt-based catalyst added is usually preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻⁴ mol of the cobalt-based catalyst with ^respect to 1 mol of the diene monomer (A), and 1 × 10 ⁻⁶ to 1 × 10 ^{−. 5} moles is particularly preferred.

  In the present embodiment, the conjugated diene polymer can be produced even with a (D) transition metal catalyst other than cobalt. Examples of the (D) transition metal catalyst other than the cobalt-based catalyst include nickel-based, neodymium-based, and vanadium-based catalysts. Among these, a vanadium-based catalyst is particularly preferable.

Examples of vanadium-based catalysts include cyclopentadienyl vanadium trichloride, methylcyclopentadienyl vanadium trichloride, ethylcyclopentadienyl vanadium trichloride, propylcyclopentadienyl vanadium trichloride, isopropylcyclopentadienyl vanadium trichloride, (1,2-dimethylcyclopentadienyl) vanadium trichloride, (1,3-dimethylcyclopentadienyl) vanadium trichloride, (1,2,3-trimethylcyclopentadienyl) vanadium trichloride, (1, 2,4-trimethylcyclopentadienyl) vanadium trichloride, (1,2,3,4-tetramethylcyclopentadienyl) vanadium trichloride, (pentamethylcyclopent Dienyl) vanadium trichloride, (2-methylindenyl) vanadium trichloride, cyclopentadienyl vanadium tri-t-butoxide, cyclopentadienyl vanadium tri-propoxide, cyclopentadienyl vanadium dimethoxy chloride, (t-butylamide) Dimethyl (η ⁵ -cyclopentadienyl) silane vanadium dichloride, cyclopentadienyl tris (diethylamide) vanadium, cyclopentadienyltris (i-propylamido) vanadium, cyclopentadienyloxovanadium dichloride, methylcyclopentadienyl Oxovanadium dichloride, benzylcyclopentadienyl oxovanadium dichloride, (1,3-dimethylcyclopentadienyl) oxovanadi Mujikuroraido, (t-butylamido) dimethyl (eta ⁵ - cyclopentadienyl) silane oxovanadium dichloride, cyclopentadienyl oxovanadium di methoxide, cyclopentadienyl oxovanadium di-i- propoxide, (cyclopentadienyl) And bis (diethylamide) oxovanadium. Among these, cyclopentadienyl vanadium trichloride and cyclopentadienyl oxo vanadium dichloride are preferable. The addition amount of the vanadium catalyst is usually preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻⁴ mol of the vanadium catalyst with respect to 1 mol of the (A) diene monomer, and 1 × 10 ⁻⁶ to 1 × 10 ^{−. 5} moles is particularly preferred.

  Furthermore, as the form of the conjugated diene polymer according to the type of the metal catalyst, lithium catalyst polymerization-polybutadiene (Li-BR), cobalt catalyst polymerization-polybutadiene (Co-BR), vanadium catalyst polymerization-polybutadiene (V-BR), Neodymium-catalyzed polymerization-polybutadiene (Nd-BR), nickel-catalyzed polymerization-polybutadiene (Ni-BR), titanium-catalyzed polymerization-polybutadiene (Ti-BR), styrene-butadiene-block copolymer (SB, SBS, SEBS), random styrene- Examples include butadiene-copolymer (L-SBR), butadiene-isoprene-copolymer (BI), and styrene-butadiene-isoprene-terpolymer (SIB). Here, cobalt-catalyzed polymerization-polybutadiene (Co-BR) is particularly suitable for the method of the present embodiment.

(E) Organoaluminum promoter The organoaluminum promoter used in the present embodiment includes trialkylaluminums such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, and tridecylaluminum. Can do. In addition, dialkylaluminum chloride such as dimethylaluminum chloride and diethylaluminum chloride; dialkylaluminum bromide; alkylaluminum sesquichloride such as sesquiethylaluminum chloride; alkylaluminum sesquibromide; Can be mentioned. Further, organic aluminum hydride compounds such as diethylaluminum hydride, diisobutylaluminum hydride, sesquiethylaluminum hydride, and the like can be given.

  These (E) organoaluminum cocatalysts can be used alone or in combination of two or more. When two or more are used in combination, the organoaluminum halogen compound is used per 1 mole of trialkylaluminum. 0.1-99 mol is preferable, 0.25-19 mol is more preferable, 1-15 mol is still more preferable, 3-9 mol is especially preferable. Of these, triethylaluminum, diethylaluminum chloride and the like are particularly preferable.

  (E) The addition amount of the organoaluminum co-catalyst is preferably in the range of 50 to 2000 mol with respect to 1 mol of the transition metal catalyst (D).

(C) The amount of water added is preferably such that the molar ratio (Al / H ₂ O) between (E) the organoaluminum promoter and (C) water is 1.00 to 2.00, It is more preferably 1.95, even more preferably 1.10 to 1.90, and particularly preferably 1.10 to 1.80. When Al / H ₂ O is smaller than 1.00 or larger than 2.00, the conjugated diene polymer is likely to be colored or discolored with time, and the gel content tends to increase, which is not preferable.

  In addition, (C) water and (E) organoaluminum are preferably aged, and the aging time is preferably 3 to 30 minutes, more preferably 4 to 25 minutes, and particularly preferably 4.5 to 15 minutes. When the aging time is shorter than 3 minutes, the conjugated diene polymer tends to be colored and discolored over time. When the aging time is longer than 30 minutes, the yield of the rubber itself tends to decrease and the productivity tends to deteriorate. It is not preferable.

  In the present embodiment, after polymerization of the diene monomer, (1) water and (2) a carboxylate having a chelating action are added. The term “after polymerization of the diene monomer” means a state after the diene monomer has been polymerized at least 30%, preferably 35% or more, and more preferably 40% or more. (1) Water and (2) a carboxylate having a chelating action can be obtained by dissolving (2) a carboxylate having a chelating action in advance in (1) water and simultaneously adding it as a carboxylic acid aqueous solution having a chelating action. , (1) water and (2) a carboxylate having a chelating action may be added separately. However, (2) carboxylates having a chelating action are particularly effective in the state of an aqueous solution. Therefore, (1) water and (2) a carboxylate having a chelating action are The acid salt is preferably dissolved in (1) water in advance and added as a carboxylic acid aqueous solution having a chelating action.

(2) Carboxylic acid salt having a chelating action Examples of the carboxylating acid salt having a chelating action used in the present embodiment include edetate (ethylenediaminetetraacetate), hydroxyethylethylenediaminetriacetate, pentetate (diethylenetriamine-5 Acetate), phytate, etidronate (hydroxyethane diphosphonate), oxalate, polyamino acid salts (polyaspartate, polyglutamate, etc.), aspartate diacetate, glutamate diacetate, Examples include salts of polyphosphoric acid, metaphosphoric acid, phosphoric acid, citric acid, alanine, dihydroxyethylglycine, gluconic acid, succinic acid, and tartaric acid. Of these, edetate (ethylenediaminetetraacetate: EDTA salt) is preferably used.
Examples of the EDTA salt include Na salt (2Na salt, 3Na salt, 4Na salt), K salt (2K salt, 3K salt, 4K salt), Ca · Na salt (Ca · 2Na salt), and the like. . These may be hydrates. Among them, EDTA Na salt is preferable because of its high chelating action, and EDTA 2Na salt is more preferable from the viewpoint of solubility in water and high chelating action. Carboxylic acid salts having a chelating action can be used singly or in combination of two or more.

  (2) The addition amount of the carboxylate having a chelating action is preferably 100 to 2000 ppm, more preferably 200 to 1000 ppm with respect to the conjugated diene polymer after polymerization. If it is less than 100 ppm, the anti-coloring effect is low, and if it exceeds 2000 ppm, the chemical oxygen demand of the waste water is increased, which is not preferable.

  The coloration of the conjugated diene polymer may be influenced by, for example, a complex centered on a transition metal added as a catalyst or a colored substance such as a chlorine compound (residual chlorine) remaining in the polymer. Later, it is considered that (1) water and (2) a carboxylate having a chelating action can be added to reduce these colored substances by the chelating action and prevent the conjugated diene polymer from being colored. .

  In this embodiment, (F) a polymerization terminator and (G) an antioxidant can be added after polymerization of the diene monomer. There are no particular restrictions on the order of addition of (1) water, (2) a carboxylate having a chelating action, (F) a polymerization terminator, and (G) an antioxidant. For example, (F) a polymerization terminator and (G) An antioxidant is added, and then (1) water and (2) a carboxylate having a chelating action are added.

(F) Polymerization Terminator The polymerization of the conjugated diene polymer can be stopped by adding water, alcohol, organic acid or inorganic acid and / or phenol by a usual method. Among these, dispersibility is good, and preferable polymerization terminators include water and lower alcohols.
The lower alcohol preferably has 5 or less carbon atoms, and specifically includes methanol, ethanol, propanol, isopropanol, butanol, ter-butyl alcohol, pentanol and isomers thereof. These may be used alone or in combination of two or more.
The amount of water is preferably ratio raw material mixed solution total is 1.38 × ¹⁰ -8 ~9.9vol%, more preferably 2.76 × ¹⁰ -8 ~5vol%, It is still more preferable that it is 4.14 * 10 < ^-8 > -3vol%. The total raw material mixed solution is the total amount of a diene monomer as a raw material charged into the reactor, a mixed solution of organic solvents such as cyclohexane and butene, and a raw material mixed solution added before modification.

  In this embodiment, (F) a polymerization terminator and (G) an antioxidant may be added at the same time, (G) an antioxidant may be added after the polymerization terminator, The order of adding (G) antioxidant and (F) polymerization terminator may be reversed. Further, when (F) the polymerization terminator is other than water, (G) addition of the antioxidant can be omitted.

(G) Antioxidant Examples of the antioxidant include 4,6-bis (octylmethyl) -o-cresol (CAS-No. 110553-27-0), octadecyl-3- ( 3,5-ditertbutyl-4-hydroxyphenyl) propionate (CAS-No. 2082-79-3), pentaerythritol tetrakis [3 (3,5-ditertbutyl-4-hydroxyphenyl) propionate] (CAS- No. 6683-19-8) and the like. Other examples include phosphorus antioxidants.

(G) As an addition amount of the antioxidant, a necessary amount may be appropriately added depending on a period to be stabilized, but 5 × 10 ^{−6 to} 3 × 10 ⁻⁴ mol per 1 mol of the diene monomer. Preferably, 1 × 10 ⁻⁵ to 2 × 10 ⁻⁴ mol is more preferable. If the amount of the antioxidant is too small, the anti-deterioration function cannot be obtained, and if it is too large, it causes coloring, which is not preferable.

  In this embodiment, a known molecular weight regulator, for example, non-conjugated dienes such as cyclooctadiene and allene, or α-olefins such as ethylene, propylene, and butene-1 can be used during polymerization. .

  The polymerization temperature is preferably in the range of -30 to 100 ° C, particularly preferably in the range of 30 to 80 ° C. The polymerization time is preferably in the range of 5 minutes to 12 hours, particularly preferably 10 minutes to 6 hours. The polymerization pressure can be carried out under normal pressure or a pressure up to about 10 atmospheres (gauge pressure).

  The hue of the conjugated diene polymer produced according to this embodiment is colorless, and the color difference (ΔE * ab) is preferably less than 6.00.

  The conjugated diene polymer produced according to the present embodiment preferably has a microstructure having a 1,4-cis structure of 80 to 99% and a 1,2-vinyl structure of 0.5 to 20%. .

  The stable colorless conjugated diene polymer produced according to the present embodiment can produce all types of vulcanizates. For example, tires, hoses, footwear members, industrial belts, medical rubbers, sports It can also be used for producing articles, crawlers or packings and for impact modification of polymers based on vinyl aromatic compounds, for example polystyrene and ABS-polymers produced by the bulk process.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to these examples. First, each measuring method is as follows.

(Hue)
The evaluation of the hue was confirmed visually.
(Color difference (ΔE ^* ab))
The color difference was evaluated by measuring the reflected light of a polybutadiene sheet (5 mm) sample placed in front of a standard white plate, measuring the reflected light using a color difference meter (ΔE ^* ab: the smaller this value, the better).
(Oxidation induction period)
Using a differential scanning calorimeter DSC-50 (manufactured by Shimadzu Corporation), the time until the oxidation exothermic peak of the diene polymer was measured at 150 ° C. in an air atmosphere.
(Residual chlorine)
After dissolving 10 g of diene polymer in 300 ml of toluene, 100 ml of distilled water was added, and the chlorine component was extracted into distilled water by vigorous stirring. Thereafter, chlorine ions were measured using an ion chromatograph to obtain a chlorine concentration in the sample.

(Mooney viscosity (ML _{1 + 4} , 100 ° C))
It measured based on JISK6300.
(Vulcanization time)
It measured at 150 degreeC using the curast meter (JSR curast meter IIF type).
(hardness)
The measurement was performed according to JIS K 6253.
(Tensile properties)
Measurement was performed with a No. 3 dumbbell according to JIS K6251.
(specific gravity)
The specific gravity was measured at 23 ° C. using an automatic hydrometer HD type (manufactured by Toyo Seiki Seisakusho).

Example 1
The inside of the polymerization autoclave having an internal volume of 1.5 L was purged with nitrogen, and 0.70 L of a raw material mixed solution (cyclohexane 20 wt%, butadiene 40 wt%, butene 40 wt%) was charged and stirred. Next, 1.95 mM of water was added and stirring was continued at room temperature for 30 minutes. Thereafter, 2.96 mM diethylaluminum chloride (DEAC) was added, and the mixture was aged by stirring for 5 minutes. Then, 6.6 mM 1,5-cyclooctadiene (COD) is added as a molecular weight regulator, the solution temperature is 50 ° C., and 8.7 μM of cobalt octaate (Co (Oct) ₂ ) is added to initiate polymerization. For 30 minutes. After the reaction, as an antioxidant, 4,4-bis (octylmethyl) -o-cresol 0.24 mM was added as a cyclohexane solution, and 2 ml of EDTA · 4Na 0.34 mM was added as an aqueous solution and stirred. Thereafter, 0.57 L of water was added as demineralized water, stirred for 30 minutes, allowed to stand for 30 minutes, separated from water, and a polybutadiene solution was recovered.
Thereafter, the recovered polybutadiene solution was vacuum dried at 105 ° C. for 2.0 hours to obtain polybutadiene. The results are shown in Table 1.

(Example 2)
The same procedure as in Example 1 was conducted except that the EDTA · 4Na aqueous solution was changed to an EDTA · 3Na aqueous solution. The results are shown in Table 1.

Example 3
The same procedure as in Example 1 was performed except that the EDTA · 4Na aqueous solution was changed to an EDTA · 2Na aqueous solution. The results are shown in Table 1.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the EDTA · 4Na aqueous solution was changed to 2 ml of water. The results are shown in Table 1.

(Comparative Example 2)
The same procedure as in Example 1 was performed except that the EDTA · 4Na aqueous solution was changed to an aqueous solution of Na oleate 0.42 mM. The results are shown in Table 1.

  From the results of Table 1, it can be seen that Examples 1 to 3 of the present invention have a colorless hue and a low color difference (ΔE * ab) compared to Comparative Examples 1 and 2. That is, it can be seen that the polybutadiene prepared by the production method of the present invention is satisfactorily suppressed in coloring. Moreover, it turns out that Example 3 which added EDTA * 2Na can prolong the oxidation induction period of a polybutadiene, and can exhibit the antioxidant effect compared with the comparative example 1 which is not added. It was also confirmed that residual chlorine, which is a cocatalyst residue, can also be reduced.

Next, it was confirmed that the colorless conjugated diene polymer produced by the production method of the present invention does not affect other physical properties when formed into a rubber composition.
Specifically, according to ASTM D3189, a rubber composition was prepared by the following composition, and the obtained vulcanized test piece was evaluated. The results are shown in Table 2.

<Combination>
Polybutadiene: 100 parts by weight, carbon black (HAF IRB # 7): 60 parts by weight, aroma oil: 15 parts by weight, No. 1 zinc white: 3 parts by weight, stearic acid: 2 parts by weight, vulcanization accelerator (TBBS): 0.9 parts by weight, sulfur: 1.5 parts by weight

From the results of Table 2, it can be seen that Example 3 to which EDTA · 2Na was added did not affect any physical properties when used in the rubber composition as compared with Comparative Example 1 to which EDTA · 2Na was not added.

Claims (7)

  A method for producing a conjugated diene polymer comprising adding (1) water and (2) a carboxylate having a chelating action after polymerization of a diene monomer.   The method for producing a conjugated diene polymer according to claim 1, wherein the (2) carboxylate salt having a chelating action is previously dissolved in the water (1) and added as a carboxylic acid aqueous solution having a chelating action. .   2. The method for producing a conjugated diene polymer according to claim 1, wherein the carboxylate having (2) chelating action is ethylenediaminetetraacetate.   The conjugated diene polymer according to claim 1, wherein the conjugated diene polymer has a 1,4-cis structure of 80 to 99% and a 1,2-vinyl structure of 0.5 to 20%. Manufacturing method.   The method for producing a conjugated diene polymer according to claim 1, wherein the conjugated diene polymer is produced by polymerization using a catalyst comprising a transition metal catalyst and an organoaluminum promoter.   A conjugated diene polymer produced by the production method according to claim 1. A method for preventing coloration of a conjugated diene polymer, comprising introducing a carboxylic acid aqueous solution having a chelating action after polymerization of a diene monomer.