JP4107129B2 - Process for producing hydrogenated conjugated diene polymer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionThe waterThe present invention relates to a method for producing an elemental conjugated diene polymer.
[0002]
[Prior art]
In the chemical industry that manufactures pharmaceuticals, agricultural chemicals, petrochemical products, polymers, etc., hydrogenation reaction that converts carbon-carbon unsaturated bonds and carbon-nitrogen unsaturated bonds contained in various compounds into corresponding saturated bonds Widely done.
For example, in the polymer field, a method for selectively or partially hydrogenating a carbon-carbon double bond of a conjugated diene polymer is known as a useful modification means of the conjugated diene polymer. Hydrogenated acrylonitrile-butadiene Hydrogenated conjugated diene polymers such as copolymers are produced on an industrial scale.
[0003]
As a typical process for producing such a hydrogenated conjugated diene polymer, (1) a step of emulsion polymerizing a monomer containing a conjugated diene and coagulating and drying the resulting latex to prepare a raw material polymer (2) a step of hydrogenating the starting polymer by dissolving it in an organic solvent (hydrogenation reaction solvent) and using a supported catalyst in which a platinum group element-containing catalyst is supported on a carrier insoluble in the organic solvent; A process comprising a step of separating a supported catalyst from the hydrogenation reaction mixture and then recovering a target hydrogenated polymer from an organic solvent is known.
[0004]
However, in the above processes (1) to (2), the raw material polymer once recovered from the latex of the conjugated diene polymer is crushed and dissolved again in the organic solvent, or the organic solvent is distilled off after the hydrogenation reaction. Troublesome operations such as doing so. Furthermore, depending on the preparation conditions of the supported catalyst used in the above (2), the support may be damaged during the hydrogenation reaction, and the catalyst components may fall off from the support. After the reaction, almost the entire amount of the supported catalyst is separated. -Even if recovered, there was a problem that the recovery rate of a valuable and expensive platinum group element-containing catalyst decreased.
[0005]
On the other hand, a process using an organic solvent-soluble non-supported catalyst without using a supported catalyst as in (2) above, or a support or non-support without passing through the steps (1) to (2) above. Various studies have also been made on the process of directly hydrogenating a conjugated diene polymer in a latex state obtained by emulsion polymerization using a type catalyst (see, for example, Patent Document 1 and Patent Document 2).
[0006]
However, in a hydrogenation reaction in a latex state containing an aqueous medium, when a supported catalyst such as the conventional process is used, the catalytic activity is not sufficiently satisfactory. In addition, when an unsupported catalyst that is dissolved or dispersed in an organic solvent or an aqueous medium is used, it is extremely difficult to separate and recover the catalyst after completion of the reaction, and the catalyst cannot be reused, resulting in a significant increase in catalyst cost. There was a problem.
[0007]
[Patent Document 1]
U.S. Pat. No. 3,898,208
[Patent Document 2]
JP-A-2-178305
[0008]
[Problems to be solved by the invention]
  The object of the present invention is based on the above circumstances.WaterWhen producing an elemental conjugated diene polymer, the platinum group element-containing catalyst used in the hydrogenation reaction of the starting polymer can be efficiently separated and recovered from a reaction mixture containing an organic solvent or an aqueous medium. It is an object of the present invention to provide a process for producing a hydrogenated conjugated diene polymer that is particularly advantageous.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have targeted both a reaction system for hydrogenating a conjugated diene polymer (raw material) in a latex state and a reaction system for hydrogenating an organic solvent solution. We have intensively studied post-treatment methods after completion of the reaction. As a result, first, an oxidizing agent is added to the reaction mixture to oxidize the catalyst residue. Simultaneously or subsequently, a complexing agent is added to the reaction mixture to complex the catalyst residue. It was found that the complex produced by the method can be separated efficiently.
[0010]
  Moreover, the improvement regarding the post-treatment method of the hydrogenation reaction as described above is as follows.(1) WaterThe platinum group element-containing catalyst used in the elementalization reaction can be easily recovered and reused, so there is no problem in economy even if a large amount of catalyst is used.WaterThe production of an elemental conjugated diene polymer can be advantageously carried out industrially;2) Hydrogenation obtainedConjugated diene polymersThe amount of residual catalyst in theConjugated diene polymersThe present invention has been completed by confirming that it has advantages such as having less adverse effects on the quality of products including
[0012]
  According to the present invention, in the presence of a platinum group element-containing catalyst.The monomer composition ratio is 10 to 90% by weight of the conjugated diene monomer and 90 to 10% by weight of the monomer copolymerizable with the conjugated diene monomer.A reaction step (A) for hydrogenating the conjugated diene polymer; an oxidation treatment step (B) for bringing the catalyst contained in the reaction mixture into contact with an oxidizing agent;Subsequent to the step (B) or at the same time or during the processA complexing step (C) of adding a complexing agent to the reaction mixture to form an oxidized catalyst complex; and a catalyst recovery step (D) for separating the complex formed from the complexed reaction mixture. A method for producing a hydrogenated conjugated diene polymer is provided.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
  Less thansewageThe production method of the elemental conjugated diene polymer will be described in detail.
[0015]
  The method for producing a hydrogenated conjugated diene polymer of the present invention is carried out in the presence of a platinum group element-containing catalyst.The monomer composition ratio is 10 to 90% by weight of the conjugated diene monomer and 90 to 10% by weight of the monomer copolymerizable with the conjugated diene monomer.A reaction step (A) for hydrogenating the conjugated diene polymer; an oxidation treatment step (B) for bringing the catalyst contained in the reaction mixture into contact with an oxidizing agent;Subsequent to the step (B) or at the same time or during the processA complexing step (C) of adding a complexing agent to the reaction mixture to form an oxidized catalyst complex; and a catalyst recovery step (D) for separating the complex formed from the complexed reaction mixture. It is essential.
[0016]
The reaction step (A), oxidation treatment step (B), complexation treatment step (C) and catalyst recovery step (D) are performed in this order, but other treatment steps may be added if desired. Can do. In addition, a process (B) and a process (C) can also be performed simultaneously. Further, the catalyst recovered in the step (D) can be purified or regenerated as necessary, and then supplied again to the step (A).
[0017]
  The hydrogenation in the reaction step (A) means that at least a part of the carbon-carbon double bond contained in the conjugated diene polymer is hydrogenated to be converted into a saturated bond. Conjugated diene polymer applied to this step (A)Are bothManufactured by a conventionally known emulsion polymerization method or solution polymerization method, preferably by an emulsion polymerization method, by combining one or more monomers copolymerizable with a role diene monomer with one or more conjugated diene monomers Is done.
[0018]
The conjugated diene monomer is not particularly limited as long as it is a polymerizable monomer having a conjugated diene structure. For example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2, Examples include 3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, and 1,3-pentadiene. Among these, 1,3-butadiene and 2-methyl-1,3-butadiene are preferable, and 1,3-butadiene is more preferable.
[0019]
Examples of monomers copolymerizable with the conjugated diene monomer include α, β-ethylenically unsaturated nitrile monomers such as acrylonitrile, methacrylonitrile, and crotonnitrile; acrylic acid, methacrylic acid, and crotonic acid. Α, β-ethylenically unsaturated carboxylic acids such as fumaric acid, maleic acid and itaconic acid; α, β-ethylenic acids such as methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, trifluoroethyl acrylate and methyl methacrylate Unsaturated carboxylic acid esters; α, β-ethylene unsaturated carboxylic acid amides such as acrylamide and methacrylamide; vinyl aromatic compounds such as styrene, α-methylstyrene, p-methylstyrene and divinylbenzene; vinyl acetate and vinyl propionate Vinyl esthetics such as ; Vinylether compounds such as fluoroethyl vinyl ether; and the like.
[0020]
  Among these monomers that can be copolymerized with the conjugated diene monomer, a monomer having an electron-withdrawing functional group is preferable from the viewpoint that the hydrogenation reaction in the step (A) easily proceeds, and α, β -Ethylenically unsaturated nitrile monomers, especially acrylonitrile, are preferably used.
  Monomer composition ratio in conjugated diene polymersAre bothIt is 10 to 90% by weight of a diene monomer, and 90 to 10% by weight of a monomer copolymerizable therewith.
[0021]
Specific examples of the conjugated diene polymer applied to the hydrogenation in the step (A) include a butadiene polymer, an isoprene polymer, a butadiene-styrene copolymer, an acrylonitrile-butadiene copolymer, and an acrylonitrile-isoprene copolymer. , Acrylonitrile-butadiene-isoprene copolymer, methacrylonitrile-butadiene copolymer, methacrylonitrile-isoprene copolymer, methacrylonitrile-butadiene-isoprene copolymer, acrylonitrile-methacrylonitrile-butadiene copolymer, acrylonitrile-butadiene- Examples thereof include a methyl acrylate copolymer and an acrylonitrile-butadiene-acrylic acid copolymer.
[0022]
Among the conjugated diene polymers, acrylonitrile-1,3-butadiene copolymer, methacrylonitrile-1,3-butadiene copolymer are used from the viewpoint of practicality and versatility as a raw material for producing a hydrogenated copolymer. Coalescence is preferred. In particular, a copolymer obtained from 30 to 95% by weight of 1,3-butadiene, preferably 45 to 85% by weight and 5 to 70% by weight of acrylonitrile, preferably 15 to 55% by weight is suitable.
[0023]
The weight average molecular weight (gel permeation chromatography method, standard polystyrene conversion) is not particularly limited, but is usually 5,000 to 500,000.
[0024]
An emulsion polymerization method suitable as a method for preparing a conjugated diene polymer (raw material) is generally carried out in an aqueous medium using a radical polymerization initiator, and known polymerization initiators and molecular weight regulators can be used. That's fine. The polymerization reaction may be any of batch, semi-batch and continuous, and the polymerization temperature and pressure are not particularly limited. The emulsifier to be used is not particularly limited, and an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, and the like can be used, and an anionic surfactant is preferable. These emulsifiers may be used alone or in combination of two or more. The amount used is not particularly limited.
[0025]
The solid content concentration of the conjugated diene polymer latex obtained by emulsion polymerization is not particularly limited, but is usually 2 to 70% by weight, preferably 5 to 60% by weight. The solid content concentration can be appropriately adjusted by a known method such as a blending method, a dilution method, or a concentration method.
When the hydrogenation reaction in the step (A) is performed in a latex state (hereinafter also referred to as “latex hydrogenation”), the latex solid content concentration is adjusted to a range of 10 to 50% by weight from the viewpoint of reaction efficiency. It is more preferable.
[0026]
The hydrogenation reaction in the step (A) is carried out in the state of a polymer solution in which a conjugated diene polymer rubber obtained by coagulating and drying a latex obtained by emulsion polymerization is dissolved in an appropriate organic solvent (hereinafter referred to as “solution system”). Also referred to as “hydrogenation”).
In this case, the latex can be coagulated and dried by a known method, but by providing a treatment step for bringing the crumb obtained by coagulation into contact with a basic aqueous solution, the resulting conjugated diene polymer rubber is treated with tetrahydrofuran ( It is preferable to modify so that the pH of the polymer solution measured by dissolving in THF) exceeds 7. The pH of the polymer solution measured by dissolving in THF is preferably in the range of 7.2 to 12, more preferably 7.5 to 11.5, and most preferably 8 to 11. By this contact treatment between the crumb and the basic aqueous solution, the solution-based hydrogenation can be rapidly advanced.
[0027]
The solution concentration of the conjugated diene polymer in the solution hydrogenation is 1 to 70% by weight, preferably 2 to 40% by weight. Examples of the organic solvent used for solution hydrogenation include linear or cyclic aliphatic hydrocarbons such as n-hexane, cyclohexane, and n-heptane; aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene. Ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isopropyl ketone, 2-pentanone, 3-pentanone, cyclopentanone, cyclohexanone; ethers such as diethyl ether, tetrahydrofuran, dioxane, anisole; esters such as ethyl acetate; Is mentioned. Of these organic solvents, ketones are preferably used.
[0028]
The catalyst used for the hydrogenation reaction in the step (A) is a hydrogenation catalyst containing a platinum group element (ruthenium, rhodium, palladium, osmium, iridium or platinum). As a hydrogenation catalyst, a palladium compound and a rhodium compound are preferable from the viewpoint of catalytic activity and availability, and a palladium compound is more preferable. Two or more platinum group element compounds may be used in combination, but in this case as well, it is preferable to use a palladium compound as the main catalyst component.
[0029]
The palladium compound as the hydrogenation catalyst is not particularly limited as long as it has catalytic activity. Usually, a divalent or IV valent palladium compound is used, and its form is a salt or a complex salt.
Examples of the palladium compound include organic acid salts such as palladium acetate and palladium cyanide; halides such as palladium fluoride, palladium chloride, palladium bromide and palladium iodide; oxygen acid salts such as palladium nitrate and palladium sulfate; Palladium; Palladium hydroxide; Palladium compounds such as dichloro (cyclooctadiene) palladium, dichloro (norbornadiene) palladium, dichlorobis (triphenylphosphine) palladium, sodium tetrachloropalladate, ammonium hexachloropalladate; potassium tetracyanopalladate, etc. Complex salts; and the like.
[0030]
Among these palladium compounds, palladium acetate, palladium nitrate, palladium sulfate, palladium chloride, sodium tetrachloropalladate, and ammonium hexachloropalladate are preferable, and palladium acetate, palladium nitrate, and palladium chloride are more preferable.
[0031]
The rhodium compound as the hydrogenation catalyst is not particularly limited as long as it has catalytic activity. For example, halides such as rhodium chloride, rhodium bromide and rhodium iodide; inorganic acid salts such as rhodium nitrate and rhodium sulfate; Organic acid salts such as rhodium acetate, rhodium formate, rhodium propionate, rhodium butyrate, rhodium valerate, rhodium naphthenate and rhodium acetylacetonate; rhodium oxide; rhodium trihydroxide;
[0032]
The hydrogenation catalyst can be used as an unsupported catalyst in which the catalyst component is directly dissolved or dispersed in the reaction system without being supported on the support. Moreover, it can also be used as a supported catalyst in which a catalyst component is supported on a carrier and charged into a reaction system. Furthermore, a supported type catalyst and a non-supported type catalyst can be used in combination.
[0033]
As the supported catalyst carrier, for example, known catalyst carriers such as activated carbon, activated clay, alumina gel, silica gel, diatomaceous earth are used. Examples of the method for supporting the catalyst component on the carrier include an impregnation method, a coating method, a spray method, an adsorption method, and a precipitation method. The supported amount of the catalyst component is usually 0.5 to 80% by weight, preferably 1 to 50% by weight, more preferably 2 to 30% by weight. The carrier carrying the catalyst component can be formed into, for example, a spherical shape, a cylindrical shape, a polygonal column shape, a honeycomb shape, or the like according to the type of reactor, the reaction mode, and the like. The supported catalyst may be added as it is to the reaction system for latex or solution hydrogenation.
[0034]
As a method of adding the unsupported catalyst to both of the above reaction systems, a method of directly adding and then dissolving or dispersing in the reaction system; preliminarily dissolving or dispersing in water or an organic solvent and reacting in a catalyst solution state A method of adding to the system; When preparing the latter method, particularly an aqueous catalyst solution, for example, inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, bromic acid, perchloric acid and phosphoric acid; sodium salts and potassium salts of these inorganic acids; organic acids such as acetic acid; Coexistence of these may improve the solubility in water and may be preferable.
[0035]
Furthermore, when applying an unsupported catalyst to latex-based hydrogenation, it is soluble or dispersible in the latex as a hydrogenation catalyst stabilizer for the purpose of maintaining the stability of the platinum group element-containing catalyst in the latex. A polymer compound having a weight average molecular weight of preferably 1,000 to 100,000, more preferably 2,000 to 50,000 can be used. The addition of the stabilizer increases the catalytic activity of the hydrogenation catalyst, reduces the amount of catalyst used, and improves the storage stability of the catalyst solution.
[0036]
The hydrogenation catalyst stabilizer is soluble or dispersible in the catalyst-containing solution and / or polymer latex (refers to a stable dispersion state like a colloid), and aggregates or precipitates in the latex. As long as the hydrogenation catalyst can be maintained in a dissolved or dispersed state without causing the above. Specific examples of hydrogenation catalyst stabilizers include polymers of vinyl compounds having a polar group in the side chain such as polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl acetal, polyalkyl vinyl ether; sodium polyacrylate, potassium polyacrylate, etc. Metal salts of polyacrylic acid; polyethers such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer; cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose; natural polymers such as gelatin and albumin; It is done. Among these, a polymer or polyether of a vinyl compound having a polar group in the side chain is preferable. Polyvinyl pyrrolidone and polyalkyl vinyl ether are particularly preferred.
[0037]
The hydrogenation catalyst stabilizer can be dissolved or dispersed in the latex together with the hydrogenation catalyst and used for the hydrogenation reaction. The hydrogenation catalyst stabilizer can be dissolved or dispersed in water or an organic solvent together with the hydrogenation catalyst, prepared in advance as a hydrogenation catalyst solution, and subjected to a hydrogenation reaction. When the catalyst solution is an aqueous solution, an inorganic acid, a metal salt thereof, an organic acid, or the like can be added, and the addition of the catalyst may improve the solubility of the hydrogenation catalyst in water. In this case, the concentration of the acid in the catalyst aqueous solution is preferably 1 to 20 times by mole, more preferably 1 to 10 times by mole with respect to the metal element in the hydrogenation catalyst.
[0038]
In particular, the method for preparing the catalyst aqueous solution preferably includes a step of adding the hydrogenation catalyst stabilizer of the present invention to the aqueous solution following the step of preparing an acidic aqueous solution of the hydrogenation catalyst.
Even if the catalyst aqueous solution is allowed to stand at 25 ° C. for 1 hour or longer, preferably 1 day or longer, more preferably 14 days or longer after preparation, the hydrogenation catalyst does not aggregate or precipitate.
[0039]
The temperature of the hydrogenation reaction is usually 0 ° C to 200 ° C, preferably 5 ° C to 150 ° C, more preferably 10 to 100 ° C. An excessively high reaction temperature is undesirable because side reactions such as hydrogenation of nitrile groups may occur. On the other hand, when the reaction temperature is excessively lowered, the reaction rate is lowered, which is not practical.
The pressure of hydrogen is usually atmospheric pressure to 20 MPa, preferably atmospheric pressure to 15 MPa, more preferably atmospheric pressure to 10 MPa. Although reaction time is not specifically limited, Usually, it is 30 minutes-50 hours. The hydrogen gas is preferably pressurized after first substituting the reaction system with an inert gas such as nitrogen and further substituting with hydrogen.
[0040]
The latex and solution hydrogenation reactions in step (A) can be carried out under basic conditions to improve the reaction efficiency and reduce the amount of hydrogenation catalyst used. The method for carrying out the reaction under basic conditions is not particularly limited, and can be appropriately selected depending on the reaction system of latex hydrogenation and solution hydrogenation.
[0041]
For example, in latex hydrogenation, a method in which a basic compound is directly added to the reaction system so that the pH of the hydrogenation reaction liquid (latex) measured with a pH meter exceeds 7 is mentioned. The pH of the hydrogenation reaction solution is preferably in the range of 7.2 to 13, more preferably 7.5 to 12.5, and still more preferably 8.0 to 12. The method and timing of adding the basic compound are not particularly limited. For example, a method of adding a basic compound to the latex in advance before adding the catalyst to the hydrogenation reaction solution; The method of adding; etc. are mentioned.
[0042]
In solution hydrogenation, as described above, in the step of preparing a conjugated diene polymer rubber (raw material) to be subjected to a hydrogenation reaction, the polymer is brought into contact with a basic aqueous solution; hydrogen And a method of adding a basic compound to the reaction system after the start of the chemical reaction.
Furthermore, for both latex hydrogenation and solution hydrogenation, a method of adding a basic compound at the stage of preparing a catalyst solution of an unsupported catalyst, particularly a catalyst aqueous solution, can be employed. When an inorganic acid or the like is used to promote the dissolution of the unsupported catalyst in water, a basic compound in an amount equal to or more than neutralizing it is added to the aqueous catalyst solution.
[0043]
The basic compound for making the hydrogenation reaction solution or the catalyst solution basic is not particularly limited, and examples thereof include alkali metal compounds, alkaline earth metal compounds, ammonia, ammonium salt compounds, and organic amine compounds. Preferred are alkali metal compounds and alkaline earth metal compounds.
[0044]
Examples of the alkali metal compound include hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; carbonate compounds such as lithium carbonate, sodium carbonate and potassium carbonate; lithium hydrogen carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate Hydrogen carbonate compounds such as: oxides such as lithium oxide, potassium oxide and sodium oxide; organic acid salt compounds such as potassium acetate and sodium acetate; lithium methoxide, lithium ethoxide, sodium methoxide, sodium ethoxide, potassium alkoxides such as t-butoxide; phenoxides such as sodium phenoxide and potassium phenoxide; and the like. Preferred are alkali metal hydroxides, carbonate compounds, and bicarbonate compounds, and more preferred are hydroxides.
[0045]
Examples of the alkaline earth metal compound include hydroxides, carbonate compounds, bicarbonate compounds, oxides, organic acid salt compounds, alkoxides, phenoxides of alkaline earth metals such as magnesium, calcium, strontium, and barium. Is mentioned. Alkali earth metal hydroxides, carbonate compounds and bicarbonate compounds are preferred, and hydroxides are more preferred.
[0046]
Examples of ammonium salt compounds include ammonium carbonate and ammonium hydrogen carbonate. Examples of organic amine compounds include aliphatic, alicyclic, aromatic mono- and polyamino compounds, such as triethylamine, ethanolamine, morpholine, N-methylmorpholine, pyridine, hexamethylenediamine, dodecamethylenediamine, xylylene diene. Examples include amines.
[0047]
These basic compounds can be used as they are, or can be used by diluting or dissolving them in water or an organic solvent such as alcohol or ketone. The basic compound may be used alone or in combination of two or more, and the amount used may be appropriately selected so that the hydrogenation reaction solution and the catalyst solution exhibit basicity.
[0048]
Hydrogenation rate of hydrogenated conjugated diene polymer obtained by the production method of the present invention (ratio of hydrogenated carbon-carbon double bonds to the total number of carbon-carbon double bonds present in the polymer before the reaction) ) Can be arbitrarily controlled within a range of 1 to 100%. The hydrogenation rate represented by the iodine value is preferably 120 or less.
[0049]
One of the major features of the production method according to the present invention is that the oxidation treatment step in which the catalyst (catalyst residue) contained in the reaction mixture is brought into contact with an oxidizing agent as a post-treatment method for the hydrogenation reaction step (A) described above (B) is provided. The catalyst in the system after completion of the hydrogenation reaction is in a reduced state, and in step (B), it is oxidized by bringing it into contact with an oxidizing agent. The oxidizing agent is not particularly limited as long as it has catalytic oxidation ability, and can be appropriately selected according to each reaction system of latex hydrogenation and solution hydrogenation.
[0050]
Examples of the oxidant for latex hydrogenation include air (oxygen); peroxides such as hydrogen peroxide, peracetic acid, and perbenzoic acid; preferably air, hydrogen peroxide, and more preferably hydrogen peroxide. Hydrogen oxide. As an oxidizing agent for solution hydrogenation, iodine; ferric chloride (FeCl₃Metal halides such as hydrogen peroxide, peracetic acid, perbenzoic acid, etc., preferably ferric chloride, iodine, more preferably ferric chloride.
[0051]
The usage-amount of these catalyst oxidizing agents is not specifically limited, It is 1-100 times mole with respect to the platinum group element contained in the catalyst used for the hydrogenation reaction, Preferably it is 3-50 times mole. Contact temperature is 0-100 degreeC normally, Preferably it is 50-95 degreeC, More preferably, it is 70-90 degreeC. The contact time is usually 10 minutes to 20 hours, preferably 30 minutes to 10 hours.
[0052]
The contact method between the catalyst and the oxidizing agent is not uniform depending on the kind of the oxidizing agent, but can be appropriately selected depending on the reaction system of latex hydrogenation and solution hydrogenation. For example, when air is used as the oxidizing agent in the latex hydrogenation step (B), a method of continuously blowing air into the reaction mixture in an open state; a gas portion atmosphere of a reaction mixture container in an open or sealed state A method of stirring the reaction mixture with air; and the like. When hydrogen peroxide is used, it may be added to the reaction mixture and stirred. Further, when an oxidizing agent such as ferric chloride, iodine, or hydrogen peroxide is applied to the solution hydrogenation step (B), a predetermined amount thereof may be added to the reaction mixture and stirred.
[0053]
Another major feature of the production method according to the present invention is that the complexing treatment is performed subsequent to the above-mentioned step (B), or simultaneously or in the course thereof. That is, the complexing treatment step (C) in which a complexing agent is added to the reaction mixture oxidized in the step (B) to form a catalyst complex is essential.
[0054]
The complexing agent used in the step (C) is not particularly limited as long as it has a catalyst complexing ability, and can be appropriately selected according to each reaction system of latex hydrogenation and solution hydrogenation. The complexing treatment method is not particularly limited, and can be carried out by adding a predetermined amount of complexing agent as it is or as a solution of water or an organic solvent to the reaction mixture and stirring.
[0055]
As the latex hydrogenation complexing agent, those that form a water-insoluble complex with a platinum group element are preferable. Examples of such a complexing agent include oxime compounds, and dioxime compounds are preferable from the viewpoint of strength of complex formation, and α, β-alkanedione dioximes such as dimethylglyoxime and cyclohexanedione dioxime are more preferable. Of these, dimethylglyoxime is most preferred.
[0056]
Examples of the complexing agent for solution hydrogenation include ammonia; ammonium salts of organic acids or inorganic acids such as ammonium acetate, ammonium benzoate, and ammonium sulfate. Ammonia and ammonium acetate are preferable, and ammonia is more preferable.
[0057]
The amount of the complexing agent to be used is generally 1 to 50 times mol, preferably 2 to 30 times mol, of the platinum group element contained in the catalyst used for the hydrogenation reaction in step (A). The complexing time is usually 10 minutes to 20 hours, preferably 30 minutes to 10 hours.
The complexing treatment temperature is usually 0 to 100 ° C., but for example, in the latex hydrogenation complexing treatment, the complex is grown or aggregated until the particle diameter becomes larger than that of the polymer particles. It is preferable to take the steps of stirring, followed by standing and cooling. Moreover, it is preferable to adjust latex pH at the time of complex formation to about 8-10.5.
[0058]
In the production method of the present invention, a catalyst separation step (D) is provided following the complexing step (C). That is, it is essential to separate the produced complex from the complexed reaction mixture. The separation method of the produced | generated complex is not specifically limited, A suitable complex separation method is employable according to each reaction system of latex type hydrogenation and solution type hydrogenation.
[0059]
For example, in latex hydrogenation, when dimethylglyoxime is used as the complexing agent in the step (C), an insoluble complex is precipitated in the reaction mixture (latex). Thus, the precipitate can be easily removed from the reaction mixture and recovered. When filtering the precipitate, the filtration device, the filtration method, and the like are not limited except that a filter cloth or filter paper that only permeates latex is used. Although vacuum filtration or pressure filtration can be employed, in order to efficiently perform filtration, it is preferable to coat the filter cloth with a filter aid such as diatomaceous earth and perform vacuum filtration.
[0060]
Moreover, when isolate | separating the produced | generated complex, the method of making an adsorbent contain in the reaction mixture containing a complex, for example, and making a reaction mixture stir or leave still can be employ | adopted. The use of an adsorbent is particularly suitable in solution-based hydrogenation.
[0061]
The adsorbent may be present in the reaction mixture from the beginning, but is preferably added to the reaction mixture containing the complexed product after completion of the complexing step (C). Examples of the adsorbent include activated carbon; silicon-containing inorganic compounds such as diatomaceous earth, talc, clay, activated clay, and silica; activated alumina; synthetic zeolite such as radiolite; and ion exchange resin. Activated carbon and silicon-containing inorganic compounds are preferred.
[0062]
In the production method of the present invention, by employing the steps (B) to (D) as described above, the hydrogenation catalyst containing a platinum group element applied to the step (A) is separated and recovered very efficiently. Can do.
[0063]
As a filtration device used for separation by filtration, a filtration device having a structure in which a plurality of filter elements are housed in a sealable housing is preferably used. Here, the “filter element” includes an element made only of a filter medium, or an element made of a combination of a filter medium and a filter plate, and refers to the entire member that bears the “filtration” function of the filter device. In particular, in view of the filtration area and the filtration speed, those having a cylindrical or hollow disk-like filter element are preferable. Examples of the filtration device provided with such a filter element include a pressurization type filter called a Fundaback filter or a leaf filter.
[0064]
In order to efficiently filter without clogging, the filter element can be precoated with a filter aid such as diatomaceous earth. Specifically, before supplying the substance to be filtered, a suspension of filter aid is filled in the housing, and the suspension is filtered to form a precoat layer of the filter aid on the filter element.
[0065]
In latex hydrogenation, a hydrogenated conjugated diene polymer latex from which most of the hydrogenation catalyst has been removed can be obtained, so that a latex product can be produced as it is. The content of platinum group element in the latex (per polymer) is usually 300 ppm or less, preferably 100 ppm or less. Further, by coagulating and drying the polymer latex by a known method, a hydrogenated conjugated diene polymer rubber from which the hydrogenation catalyst has been almost removed can be obtained. That is, a method usually used industrially, for example, adding a coagulant such as aluminum sulfate, magnesium sulfate, calcium chloride to polymer latex to obtain crumb, washing with water if necessary, draining, hot air drying, decompression Through a drying process such as drying or extrusion drying, a hydrogenated conjugated diene polymer rubber can be obtained.
[0066]
The separated platinum group element-containing catalyst and complexed product thereof can be recovered and reused by dissolution, decomposition, reaction treatment or the like.
When a supported catalyst is used in the solution-based hydrogenation step (A), by performing steps (B) to (D), a considerable amount of the catalyst component dropped into the reaction solvent from the support is separated and recovered. can do. Also, when a non-supported catalyst is used in the solution-based hydrogenation step (A), a considerable amount of the catalyst used can be separated and recovered from the reaction mixture. In solution hydrogenation, after separating the catalyst in step (D), the organic solvent is distilled off by a known method to obtain a hydrogenated conjugated diene polymer.
[0067]
When an unsupported catalyst is used in latex or solution hydrogenation, the recovery rate of platinum group elements is usually 70% or more, and can be 95% or more if conditions are selected. In addition, when a supported catalyst is used, the total recovery rate of platinum group elements combined with the platinum group elements recovered in the state of being supported on the carrier is usually 70% or more, and if the conditions are selected, it should be 95% or more. Can do.
The latex of the hydrogenated conjugated diene polymer finally recovered by the latex hydrogenation method usually has a platinum group element content per polymer of 100 ppm or less, preferably 80 ppm or less, more preferably 50 ppm or less. be able to.
[0068]
In addition, the hydrogenated conjugated diene polymer rubber obtained by separating from the latex and the hydrogenated conjugated diene polymer rubber obtained in solution hydrogenation also have a platinum group element content derived from the hydrogenation catalyst. As described above, it can be obtained as extremely low. The lower the platinum group element content, the better. The lower limit is not limited, but in general, a hydrogenated conjugated diene polymer rubber having a content per polymer rubber of about 5 ppm or less is advantageously produced industrially. It is difficult.
The separated platinum group element-containing catalyst and complexed product thereof can be recovered and reused by dissolution, decomposition, reaction treatment or the like.
[0069]
Example
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples. Further, parts and% in these examples are based on weight unless otherwise specified.
The hydrogenation rate of the hydrogenated conjugated diene polymer was measured by proton NMR. In addition, after recovery of the hydrogenation catalyst, the amount of palladium in the separated hydrogenated conjugated diene polymer rubber is such that a part of the hydrogenated polymer rubber is carbonized / ashed at 600 ° C. and dissolved in sulfuric acid. It was measured by absorption spectrometry.
[0070]
Example 1  Latex hydrogenation
An autoclave was charged with 2 parts of potassium oleate, 180 parts of ion exchanged water, 37 parts of acrylonitrile, and 0.5 part of t-dodecyl mercaptan. After replacing the inside of the reactor with nitrogen, 63 parts of butadiene was sealed. The reactor was cooled to 10 ° C., and 0.01 parts of cumene hydroperoxide and 0.01 parts of ferrous sulfate were added. The contents were then stirred for 16 hours while maintaining the reactor at 10 ° C. Thereafter, 10% hydroquinone aqueous solution was added into the reactor to terminate the polymerization. Unreacted monomers were removed from the polymerization reaction solution to obtain a latex. The polymerization conversion was 90%. The acrylonitrile-butadiene copolymer (NBR) latex thus obtained was subjected to a hydrogenation reaction in a latex state.
[0071]
Palladium acetate (the amount used is 700 ppm in the ratio of Pd metal / NBR) was added to water, and 5-fold molar equivalent of nitric acid was added to palladium to prepare 300 parts of an acidic aqueous palladium solution. Polyvinylpyrrolidone having a weight average molecular weight of 5000 was added to the aqueous solution 5 times by weight with respect to palladium. Further, an aqueous potassium hydroxide solution was added to prepare an aqueous catalyst solution A having a pH of 9.0.
Put 400 parts of NBR latex adjusted to 30% of total solids (120 parts of solids) and the total amount of catalyst aqueous solution A in an autoclave with a stirrer, and then flow nitrogen gas for 10 minutes to remove dissolved oxygen in the latex. did. After the system was replaced with hydrogen gas twice, 3 MPa hydrogen was pressurized. The contents were heated to 50 ° C. and stirred for 6 hours to conduct a hydrogenation reaction, thereby obtaining a latex-state hydrogenated NBR reaction mixture.
[0072]
2 parts of 30% hydrogen peroxide water was added to the latex reaction mixture and stirred (oxidation treatment) at 80 ° C. for 2 hours. Next, the pH of the reaction mixture was adjusted to 9.5, and dimethylglyoxime corresponding to a 5-fold molar amount of palladium contained in the catalyst aqueous solution A was added as a powder. When the reaction mixture was stirred at 80 ° C. for 5 hours (complexation treatment), insoluble matters were precipitated in the latex. The total amount of the latex was suction filtered to separate the precipitate. The resulting white filtrate was concentrated under reduced pressure using a rotary evaporator to obtain solid hydrogenated NBR. The hydrogenation rate of hydrogenated NBR was 93%.
The amount of palladium in hydrogenated NBR was 37 ppm. This amount of palladium corresponded to 5.2% of the palladium charged in the hydrogenation reaction, and the remaining palladium was removed from the hydrogenated NBR.
[0073]
Comparative Example 1  Latex hydrogenation
In the same manner as in Example 1, preparation of NBR (polymerization conversion rate: 90%), preparation of aqueous catalyst solution A, and hydrogenation reaction in a latex state (92% hydrogenation) were sequentially performed. Without adding the hydrogen peroxide solution and dimethylglyoxime used in Example 1, the pH of the reaction mixture was adjusted to 9.5 and stirred at 80 ° C. for 7 hours. There was no change in the state of the reaction mixture (latex), and no precipitate as in Example 1 was observed. When the entire amount of the latex was suction filtered, all of it passed through the filter paper. The filtrate had a dark gray color with a blackish tinge. The obtained filtrate was concentrated under reduced pressure using a rotary evaporator to obtain solid hydrogenated NBR.
The amount of palladium in the hydrogenated NBR was 690 ppm, corresponding to 98.6% of the palladium charged in the hydrogenation reaction.
[0074]
Example 2  Solution hydrogenation
In the same manner as in Example 1, an acrylonitrile-butadiene copolymer (NBR) latex was prepared. While stirring 300 parts of coagulated water dissolving 3 parts of calcium chloride (coagulant) at 50 ° C., the latex was added dropwise to coagulated water to coagulate the latex. The crumb was separated from the coagulated water, washed with water, and dried under reduced pressure at 50 ° C. This crumb was dissolved in acetone to prepare a 15% polymer solution. To 800 parts of the acetone solution (120 parts of solid content), palladium acetate (the amount used is 500 ppm in terms of Pd metal / NBR) is added to an autoclave with a stirrer, and nitrogen gas is allowed to flow for 10 minutes to dissolve dissolved oxygen. Removed. After the system was replaced with hydrogen gas twice, 5 MPa hydrogen was pressurized. The contents were heated to 50 ° C. and stirred for 6 hours to conduct a hydrogenation reaction.
[0075]
After completion of the hydrogenation reaction, the system was cooled to room temperature and the hydrogen in the system was replaced with nitrogen. To this reaction mixture, 1.84 parts of ferric chloride was added and stirred (oxidation treatment) at 30 ° C. for 3 hours. Next, 16 parts of aqueous ammonia was added and stirred at 80 ° C. for 5 hours (complexation treatment). After cooling, 6 parts of activated carbon was added and stirred (adsorption treatment) at room temperature for 3 hours, and then the activated carbon was filtered off. The obtained filtrate was added to 10 times the amount of water, and the precipitated rubber was taken out. It was dried in a vacuum dryer for 24 hours to obtain hydrogenated NBR.
The amount of palladium in the hydrogenated NBR was 50 ppm, corresponding to 10% of the palladium charged in the hydrogenation reaction, and the remaining palladium was removed from the hydrogenated NBR.
[0076]
Comparative Example 2  Solution hydrogenation
In the same manner as in Example 2, preparation of NBR (polymerization conversion rate: 90%), preparation of the acetone solution, and hydrogenation reaction were sequentially performed. The reaction mixture was stirred at 30 ° C. for 3 hours without adding the ferric chloride used in Example 2. Next, without adding the ammonia water used in Example 2, 16 parts of water was added and stirred at 80 ° C. for 5 hours. After cooling, 6 parts of activated carbon was added and stirred (adsorption treatment) at room temperature for 3 hours, and then the activated carbon was filtered off. The obtained filtrate was added to 10 times the amount of water, and the precipitated rubber was taken out. It was dried in a vacuum dryer for 24 hours to obtain hydrogenated NBR.
[0077]
The amount of palladium in this hydrogenated NBR was 495 ppm, corresponding to 99% of the palladium charged in the hydrogenation reaction.
As is clear from comparison between Example 1 and Example 2 and Comparative Example 1 and Comparative Example 2, the obtained hydrogen was determined depending on the presence or absence of oxidation treatment and complexation treatment as post-treatment methods after completion of the hydrogenation reaction. It can be seen that the palladium content in the modified NBR is greatly different. It was confirmed that the catalyst used in the hydrogenation reaction (latex system, solution system) can be efficiently separated from the reaction mixture by performing the oxidation treatment and the complexation treatment.
[0078]
【The invention's effect】
  Of the present inventionManufacturingAccording to the method, the platinum group element-containing catalyst used in the hydrogenation reaction can be easily recovered and reused, so even if a large amount of catalyst is used, there is no problem in economic efficiency.WaterAn elemental conjugated diene polymer can be advantageously produced industrially.
[0079]
The latex of the hydrogenated conjugated diene polymer obtained by the production method of the present invention is useful as an adhesive, a coating agent, a paint, a dip-formed glove raw material, and the like. Since the amount of residual platinum group elements in latex is significantly reduced, when used as an adhesive, coating agent, paint, etc., the corrosion resistance of the deposited or coated metal material is high, and the residual platinum group elements are the cause. Since there is no darkening, coating agents and paints have a high degree of freedom in coloring. Also, gloves obtained by dip molding latex are suitable for operations such as semiconductor device manufacturing processes.
[0080]
The hydrogenated conjugated diene polymer rubber obtained from the above hydrogenated conjugated diene polymer latex and the hydrogenated conjugated diene polymer rubber obtained by solution hydrogenation are both darkened from platinum group elements. Or there is no fear of coloring and it can be advantageously used in a wide range of industrial applications utilizing various properties such as oil resistance, weather resistance, ozone resistance, heat resistance and cold resistance.

Claims (8)

In the presence of a platinum group element-containing catalyst , the monomer composition ratio is 10 to 90% by weight of a conjugated diene monomer and 90 to 10% by weight of a monomer copolymerizable with the conjugated diene monomer. Reaction step (A) for hydrogenating the diene polymer; oxidation treatment step (B) for bringing the catalyst contained in the reaction mixture into contact with an oxidant; subsequent to the step (B), simultaneously or in the course thereof A complexing step (C) of adding a complexing agent to the reaction mixture to form an oxidized catalyst complex; and a catalyst recovery step (D) for separating the complex formed from the complexed reaction mixture. A method for producing a hydrogenated conjugated diene polymer.   The production method according to claim 1, wherein the conjugated diene polymer is a copolymer of a conjugated diene monomer and an α, β-unsaturated ethylenic nitrile monomer. The production method according to claim 1 , wherein the conjugated diene polymer is a copolymer of 30 to 95% by weight of 1,3-butadiene and 5 to 70% by weight of acrylonitrile. The process according to any one of claims 1 to 3 platinum group metal is palladium. The process according to any one of claims 1 to 4 for the hydrogenation in step (A) under basic conditions. The production method according to any one of claims 1 to 5 , wherein the complexing agent used in the step (C) is an oxime compound. The production method according to any one of claims 1 to 6 , wherein the oxidizing agent used in the step (B) is air, oxygen, peroxide, iodine, or a metal halide. The production method according to any one of claims 1 to 6 , wherein the oxidizing agent used in the step (B) is air, hydrogen peroxide, iodine or ferric chloride.