JP7373160B2 - Separation method of catalyst components - Google Patents

Description

The present invention relates to a catalyst component separation method for separating platinum group elements derived from platinum group element-containing catalysts from hydrogenated nitrile rubber.

Nitrile rubber (acrylonitrile-butadiene copolymer rubber) has traditionally been used as a material for automotive rubber parts such as hoses and tubes due to its oil resistance, mechanical properties, and chemical resistance. Hydrogenated nitrile rubber (hydrogenated acrylonitrile-butadiene copolymer rubber), which is made by hydrogenating the carbon-carbon double bonds in the rubber's polymer main chain, has even better heat resistance, so it is used in rubber parts such as belts, hoses, and diaphragms. has been done.

Such hydrogenated nitrile rubber is manufactured, for example, by the following manufacturing process. That is, a monomer mixture containing an α,β-ethylenically unsaturated nitrile monomer and a conjugated diene monomer is emulsion polymerized, the nitrile rubber latex obtained by emulsion polymerization is coagulated and dried, and then coagulated.・Dissolve the nitrile rubber obtained by drying in a water-soluble organic solvent to obtain a solution of nitrile rubber in a water-soluble organic solvent, and add a platinum group element-containing catalyst as a hydrogenation catalyst to this for hydrogenation. (For example, see Patent Document 1).

On the other hand, hydrogenated nitrile rubber produced by such a production method has a problem in that a relatively large amount of platinum group elements derived from a platinum group element-containing catalyst as a hydrogenation catalyst remains. Therefore, in Patent Document 2, an aqueous solution of a water-soluble polymer is added to a water-soluble organic solvent solution of hydrogenated nitrile rubber obtained by hydrogenating nitrile rubber in the presence of a catalyst containing a platinum group element. Then, by stirring, the platinum group element-containing catalyst is incorporated into the water-soluble polymer, and the water-soluble polymer is precipitated. Techniques have been proposed for separating platinum group elements from hydrogenated nitrile rubber.

Special table 2015-515532 publication International Publication No. 2018/016400

However, at the same time as the water-soluble polymer is precipitated, some of the hydrogenated nitrile rubber aggregates, and the aggregated hydrogenated nitrile rubber prevents the water-soluble polymer from taking up the platinum group element-containing catalyst. There is a problem in that it is not possible to separate nitrile rubber and platinum group elements with high efficiency. At the same time, nitrile rubber was mixed into the water-soluble polymer used to incorporate the platinum group element-containing catalyst, and only water-soluble polymers containing a relatively large amount of nitrile rubber could be recovered. There are also problems that hinder reuse.

The present invention has been made in view of the above circumstances, and is capable of separating platinum group elements derived from platinum group element-containing catalysts from hydrogenated nitrile rubber with high efficiency. It is an object of the present invention to provide a method for separating catalyst components that can easily recover water-soluble polymers used for separation of platinum group elements with high purity and high yield.

The present inventors previously prepared a water-soluble polymer solution in which the weight ratio of water-soluble organic solvent and water was adjusted within a specific range, and conducted a hydrogenation reaction in the presence of a platinum group element-containing catalyst. Platinum group elements can be separated from hydrogenated nitrile rubber with high efficiency by mixing the water-soluble organic solvent solution of hydrogenated nitrile rubber obtained in and the water-soluble polymer solution and then stirring; Furthermore, they discovered that nitrile rubber is less likely to be mixed into the water-soluble polymer used to separate platinum group elements from hydrogenated nitrile rubber, and that a highly purified water-soluble polymer can be recovered in high yield. It was completed.

That is, according to the present invention, a water-soluble organic solvent solution of hydrogenated nitrile rubber and a water-soluble polymer solution obtained by hydrogenating nitrile rubber in the presence of a platinum group element-containing catalyst are used. a mixing step of obtaining a mixed solution by mixing; and a water-soluble polymer that precipitates the water-soluble polymer while incorporating the platinum group element into the water-soluble polymer by stirring the mixed solution. a precipitation step, wherein the water-soluble polymer solution contains the water-soluble polymer, a water-soluble organic solvent, and water, and a weight ratio of the water-soluble organic solvent to water in the water-soluble polymer solution. is 1:1 to 3:1.

In the method for separating catalyst components of the present invention, the concentration of water in the liquid mixture is preferably 0.020 to 0.050% by weight.
In the method for separating catalyst components of the present invention, the concentration of the water-soluble polymer in the water-soluble polymer solution is preferably 1 to 40% by weight.
In the method for separating catalyst components of the present invention, it is preferable that the water-soluble polymer is an amino group-containing polyacrylamide.
In the method for separating catalyst components of the present invention, it is preferable that the platinum group element is palladium.

Further, according to the present invention, a hydrogenation step of hydrogenating nitrile rubber in a water-soluble organic solvent in the presence of a platinum group element-containing catalyst to obtain a solution of hydrogenated nitrile rubber in a water-soluble organic solvent; A mixing step of obtaining a mixed solution by mixing the water-soluble organic solvent solution of the hydrogenated nitrile rubber and the water-soluble polymer solution; a water-soluble polymer precipitation step of precipitating the water-soluble polymer while incorporating a platinum group element, the water-soluble polymer solution containing the water-soluble polymer, a water-soluble organic solvent, and water. There is provided a method for producing hydrogenated nitrile rubber, wherein the weight ratio of the water-soluble organic solvent to water in the water-soluble polymer solution is 1:1 to 3:1.

According to the present invention, the platinum group element derived from the platinum group element-containing catalyst can be separated from hydrogenated nitrile rubber with high efficiency, and furthermore, the platinum group element derived from the platinum group element-containing catalyst can be separated from the hydrogenated nitrile rubber. It is possible to provide a method for separating catalyst components, which can easily recover a reactive polymer with high purity and high yield.

The method for separating the catalyst component of hydrogenated nitrile rubber of the present invention includes a water-soluble organic solvent solution of hydrogenated nitrile rubber obtained by subjecting nitrile rubber to a hydrogenation reaction in the presence of a platinum group element-containing catalyst; , a mixing step of obtaining a mixed solution by mixing water-soluble polymer solutions, and stirring the mixed solution to incorporate the platinum group element into the water-soluble polymer while incorporating the platinum group element into the water-soluble polymer. and a water-soluble polymer precipitation step.

The nitrile rubber used in the present invention is, for example, a copolymer obtained by copolymerizing a monomer mixture containing at least an α,β-ethylenically unsaturated nitrile monomer and a conjugated diene monomer. Can be mentioned.

The α,β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α,β-ethylenically unsaturated compound having a nitrile group, such as acrylonitrile; α-chloroacrylonitrile, α-bromoacrylonitrile, etc. α-halogenoacrylonitrile; α-alkylacrylonitrile such as methacrylonitrile; and the like. Among these, acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is more preferred. The α,β-ethylenically unsaturated nitrile monomers may be used alone or in combination.

The content of α,β-ethylenically unsaturated nitrile monomer units in the nitrile rubber is 5 to 60% by weight, preferably 10 to 50% by weight, more preferably 15% by weight based on the total monomer units. ~50% by weight. By setting the content of the α,β-ethylenically unsaturated nitrile monomer unit within the above range, the resulting rubber crosslinked product can have excellent cold resistance and oil resistance.

As the conjugated diene monomer, conjugated diene monomers having 4 to 6 carbon atoms such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene are preferred. , 1,3-butadiene and isoprene are more preferred, and 1,3-butadiene is particularly preferred. The conjugated diene monomers may be used alone or in combination.

The content of conjugated diene monomer units (including portions hydrogenated by hydrogenation reaction) in the nitrile rubber is preferably 40 to 95% by weight, more preferably 40 to 95% by weight based on all monomer units. is 50 to 90% by weight, more preferably 50 to 85% by weight. By setting the content of the conjugated diene monomer unit within the above range, the resulting rubber crosslinked product can have excellent rubber elasticity while maintaining good heat resistance and chemical stability.

Furthermore, the nitrile rubber used in the present invention is a product obtained by copolymerizing an α,β-ethylenically unsaturated nitrile monomer and a conjugated diene monomer with other monomers that can be copolymerized with these. It's okay. Other copolymerizable monomers include α,β-ethylenically unsaturated monocarboxylic acid monomers, α,β-ethylenically unsaturated polycarboxylic acid monomers, and α,β-ethylenically unsaturated monocarboxylic acid monomers. Ethylenically unsaturated monocarboxylic acid ester monomer, α,β-ethylenically unsaturated dicarboxylic acid monoester monomer, ethylene, α-olefin monomer, aromatic vinyl monomer, fluorine-containing vinyl monomer , copolymerizable anti-aging agents, etc.

Examples of the α,β-ethylenically unsaturated monocarboxylic acid monomer include acrylic acid, methacrylic acid, ethyl acrylic acid, crotonic acid, and cinnamic acid.

Examples of the α,β-ethylenically unsaturated polycarboxylic acid monomer include butenedionic acid such as fumaric acid and maleic acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, allylmalonic acid, and terraconic acid. Further, examples of anhydrides of α,β-unsaturated polycarboxylic acids include maleic anhydride, itaconic anhydride, citraconic anhydride, and the like.

Examples of α,β-ethylenically unsaturated monocarboxylic acid ester monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-dodecyl acrylate, methyl methacrylate, and ethyl methacrylate. (Meth)acrylic ester having an alkyl group having 1 to 18 carbon atoms (abbreviation for "methacrylic ester and acrylic ester". The same applies hereinafter); methoxymethyl acrylate, ethoxypropyl acrylate, methoxybutyl acrylate, (Meth)acrylic acid esters having an alkoxyalkyl group having 2 to 18 carbon atoms, such as ethoxydodecyl acrylate, methoxyethyl methacrylate, methoxybutyl methacrylate, and ethoxypentyl methacrylate; α-cyanoethyl acrylate, α-cyanoethyl methacrylate (meth)acrylic acid esters having a cyanoalkyl group having 2 to 12 carbon atoms, such as cyanobutyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, etc. Examples include (meth)acrylic esters having 12 hydroxyalkyl groups; (meth)acrylic esters having fluoroalkyl groups having 1 to 12 carbon atoms, such as trifluoroethyl acrylate and tetrafluoropropyl methacrylate.

Examples of α,β-ethylenically unsaturated dicarboxylic acid monoester monomers include monoalkyl maleates such as monomethyl maleate, monoethyl maleate, monopropyl maleate, and mono-n-butyl maleate; monocyclopentyl maleate; Monocycloalkyl maleate esters such as monocyclohexyl maleate and monocycloheptyl maleate; monoalkylcycloalkyl maleate esters such as monomethylcyclopentyl maleate and monoethylcyclohexyl maleate; monomethyl fumarate, monoethyl fumarate, monofumarate Fumaric acid monoalkyl esters such as propyl and mono-n-butyl fumarate; fumaric acid monocycloalkyl esters such as monocyclopentyl fumarate, monocyclohexyl fumarate, and monocycloheptyl fumarate; monomethylcyclopentyl fumarate, monoethylcyclohexyl fumarate monoalkyl cycloalkyl fumarate esters such as monomethyl citraconate, monoethyl citraconate, monopropyl citraconate, mono-n-butyl citraconate; monocyclopentyl citraconate, monocyclohexyl citraconate, mono-citraconate Citraconic acid monocycloalkyl esters such as cycloheptyl; citraconic acid monocycloalkyl esters such as monomethylcyclopentyl citraconate, monoethylcyclohexyl citraconate; monomethyl itaconate, monoethyl itaconate, monopropyl itaconate, mono n-butyl itaconate itaconate monoalkyl esters such as monocyclopentyl itaconate, monocyclohexyl itaconate, monocycloheptyl itaconate; monoalkylcycloalkyl itaconate such as monomethylcyclopentyl itaconate, monoethylcyclohexyl itaconate, etc. Ester; etc. are mentioned.

The α-olefin monomer preferably has 3 to 12 carbon atoms, and includes, for example, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, and vinylpyridine.

Examples of the fluorine-containing vinyl monomer include fluoroethyl vinyl ether, fluoropropyl vinyl ether, o-trifluoromethylstyrene, vinyl pentafluorobenzoate, difluoroethylene, and tetrafluoroethylene.

Copolymerizable anti-aging agents include N-(4-anilinophenyl)acrylamide, N-(4-anilinophenyl)methacrylamide, N-(4-anilinophenyl)cinnamamide, and N-(4-anilinophenyl)acrylamide. phenyl)crotonamide, N-phenyl-4-(3-vinylbenzyloxy)aniline, N-phenyl-4-(4-vinylbenzyloxy)aniline, and the like.

A plurality of types of these other copolymerizable monomers may be used in combination. The content of other monomer units in the nitrile rubber is preferably 50% by weight or less, more preferably 40% by weight or less, even more preferably 10% by weight or less.

The method for producing the nitrile rubber used in the present invention is not particularly limited, but may be carried out by copolymerizing the above-mentioned monomers and, if necessary, hydrogenating the carbon-carbon double bonds in the resulting copolymer. can be manufactured. The polymerization method is not particularly limited and may be any known emulsion polymerization method or solution polymerization method, but emulsion polymerization method is preferred from the viewpoint of industrial productivity. During emulsion polymerization, commonly used polymerization auxiliary materials can be used in addition to emulsifiers, polymerization initiators, and molecular weight regulators. The emulsifier used is not particularly limited either, and anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used, but anionic surfactants are preferred. These emulsifiers may be used alone or in combination of two or more. The amount used is not particularly limited.

The solid content concentration of the nitrile rubber 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 known methods such as blending, dilution, and concentration.

The hydrogenation reaction of nitrile rubber may be carried out on the latex obtained by emulsion polymerization in its latex state, but from the viewpoint of catalytic activity etc., the latex obtained by emulsion polymerization may be coagulated and dried to form a solid state. It is preferable to obtain nitrile rubber and dissolve the obtained nitrile rubber in a water-soluble organic solvent to form a polymer solution. By using a water-soluble organic solvent, the platinum group element derived from the platinum group element-containing catalyst can be suitably separated from the hydrogenated nitrile rubber by the water-soluble polymer described below.

Coagulation and drying of the latex may be performed by a known method, but by providing a treatment step in which the crumb obtained by coagulation is brought into contact with a basic aqueous solution, the resulting nitrile rubber is dissolved in tetrahydrofuran (THF). It is preferable to modify the polymer solution so that the pH of the measured polymer solution exceeds 7. The pH of the polymer solution measured in THF is preferably in the range 7.2-12, more preferably 7.5-11.5, most preferably 8-11. By contacting the crumb with the basic aqueous solution, solution-based hydrogenation can proceed rapidly.

The concentration of nitrile rubber in the polymer solution during the hydrogenation reaction is preferably 1 to 70% by weight, more preferably 1 to 40% by weight, particularly preferably 2 to 20% by weight. Examples of water-soluble organic solvents include ketones such as acetone, methyl ethyl ketone, diethyl ketone, and methyl isopropyl ketone; ethers such as tetrahydrofuran and dioxane; and esters such as ethyl acetate. Among these organic solvents, ketones are preferably used, and acetone is particularly preferably used.

In the present invention, when performing the hydrogenation reaction, a platinum group element-containing catalyst is used as the hydrogenation catalyst. The platinum group element-containing catalyst may be any catalyst containing a platinum group element, that is, ruthenium, rhodium, palladium, osmium, iridium, or platinum, and is not particularly limited, but from the viewpoint of catalytic activity and availability, palladium compounds may be used. , rhodium compounds are preferred, and palladium compounds are more preferred. Further, two or more types of platinum group element compounds may be used in combination, but in that case as well, it is preferable to use a palladium compound as the main catalyst component.

As the palladium compound, a II-valent or IV-valent palladium compound is usually used, and its form is a salt or a complex salt.

Examples of palladium compounds include palladium acetate, palladium cyanide, palladium fluoride, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium oxide, palladium hydroxide, dichloro(cyclooctadiene)palladium, Examples include dichloro(norbornadiene)palladium, dichlorobis(triphenylphosphine)palladium, sodium tetrachloropalladate, ammonium hexachloropalladate, potassium tetracyanopalladate, and the like.

Among these palladium compounds, palladium acetate, palladium nitrate, palladium sulfate, palladium chloride, sodium tetrachloropalladate, and ammonium hexachloropalladate are preferred, and palladium acetate, palladium nitrate, and palladium chloride are more preferred.

Examples of rhodium compounds include rhodium chloride, rhodium bromide, rhodium iodide, rhodium nitrate, rhodium sulfate, rhodium acetate, rhodium formate, rhodium propionate, rhodium butyrate, rhodium valerate, rhodium naphthenate, rhodium acetylacetonate, and rhodium oxide. Examples include rhodium and rhodium trihydroxide.

In the present invention, as the platinum group element-containing catalyst, the above-mentioned palladium compounds and rhodium compounds may be used as they are, or the catalyst components such as the above-mentioned palladium compounds and rhodium compounds may be supported on a carrier. May be used as a catalyst.

The carrier for forming the supported catalyst may be any carrier that is generally used as a carrier for metal catalysts, but specifically, inorganic compounds containing carbon, silicon, aluminum, magnesium, etc. Among them, from the viewpoint of further increasing the adsorption efficiency of catalyst components such as palladium compounds and rhodium compounds, carriers having characteristics of an average particle diameter of 1 μm to 200 μm and a specific surface area of 200 to 2000 m ² /g are preferred. It is preferable to use

Such a carrier is appropriately selected from known catalyst carriers such as activated carbon, activated clay, talc, clay, alumina gel, silica, diatomaceous earth, and synthetic zeolite. Examples of the method for supporting the catalyst component on the carrier include an impregnation method, a coating method, a spraying method, and a precipitation method. The amount of catalyst component supported is usually 0.5 to 80% by weight, preferably 1 to 50% by weight, and more preferably 2 to 30% by weight, based on the total amount of catalyst and carrier. The carrier supporting the catalyst component can be shaped into, for example, a spherical shape, a cylindrical shape, a polygonal column shape, a honeycomb shape, etc., depending on the type of reactor and reaction type.

In addition, when using a salt of a platinum group element such as a palladium compound or a rhodium compound as a platinum group element-containing catalyst without supporting it on a carrier, a stabilizer should be used in combination to stabilize these compounds. is preferred. By providing a stabilizer in a medium in which a platinum group element-containing catalyst such as a palladium compound or a rhodium compound is dissolved or dispersed, nitrile rubber can be hydrogenated at a high hydrogenation rate.

Examples of such stabilizers include polymers of vinyl compounds having polar groups in side chains such as polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl acetal, and polyalkyl vinyl ether; sodium polyacrylate, potassium polyacrylate, etc. Metal salts of polyacrylic acid; polyethers such as polyethylene oxide, polypropylene oxide, and ethylene oxide-propylene oxide copolymers; cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose; natural polymers such as gelatin and albumin; . Among these, polymers of vinyl compounds having polar groups in side chains or polyethers are preferred. Among polymers of vinyl compounds having polar groups in side chains, polyvinylpyrrolidone and polyalkyl vinyl ether are preferred, and polymethyl vinyl ether is more preferred.

In addition, in the hydrogenation reaction, a reducing agent may be used in combination, and examples of reducing agents include hydrazines such as hydrazine, hydrazine hydrate, hydrazine acetate, hydrazine sulfate, and hydrazine hydrochloride, or compounds that liberate hydrazine. Examples include.

The temperature of the hydrogenation reaction is usually 0 to 200°C, preferably 5 to 150°C, more preferably 10 to 100°C. By controlling the temperature of the hydrogenation reaction within the above range, the reaction rate can be made sufficient while suppressing side reactions.

The hydrogen pressure during the hydrogenation reaction is usually 0.1 to 20 MPa, preferably 0.1 to 15 MPa, and more preferably 0.1 to 10 MPa. The reaction time is not particularly limited, but is usually 30 minutes to 50 hours. Note that it is preferable that the hydrogen gas be pressurized after first replacing the reaction system with an inert gas such as nitrogen, and then replacing it with hydrogen.

The weight average molecular weight (Mw) of the hydrogenated nitrile rubber is preferably 50,000 to 1,000,000, more preferably 70,000 to 800,000, even more preferably 100,000 to 600,000. The weight average molecular weight (Mw) of hydrogenated nitrile rubber can be determined in terms of standard polystyrene using gel permeation chromatography.

When a supported catalyst is used as the platinum group element-containing catalyst, a water-soluble organic solvent solution of hydrogenated nitrile rubber can be obtained by separating the supported catalyst by filtration, centrifugation, or the like.

In the present invention, a mixed solution is obtained by mixing the water-soluble organic solvent solution of hydrogenated nitrile rubber obtained as described above and a water-soluble polymer solution. Stir. According to the present invention, by mixing a water-soluble organic solvent solution of hydrogenated nitrile rubber and a water-soluble polymer solution and stirring the resulting mixture, The water-soluble polymer coordinates with the platinum group element, the platinum group element is incorporated into the water-soluble polymer, and on the other hand, the water-soluble polymer is dehydrated due to the influence of the water-soluble organic solvent. Water-soluble polymers can be precipitated with platinum group elements incorporated therein. Thereby, the hydrogenation catalyst, particularly the platinum group element derived from the platinum group element-containing catalyst, can be appropriately separated from the hydrogenated nitrile rubber. Furthermore, by incorporating the platinum group element into the water-soluble polymer, it is also possible to recover the platinum group element.

Furthermore, according to the present invention, when adding a water-soluble polymer to a water-soluble organic solvent solution of hydrogenated nitrile rubber, the water-soluble polymer is added in the form of a solution containing a water-soluble organic solvent and water in a specific weight ratio. As a result, while suppressing agglomeration of hydrogenated nitrile rubber, a water-soluble compound containing a platinum group element derived from a platinum group element-containing catalyst contained in a water-soluble organic solvent solution of hydrogenated nitrile rubber is produced. Polymers can be precipitated. Therefore, as in the conventional technology, some hydrogenated nitrile rubber aggregates at the same time as the water-soluble polymer is precipitated, and the aggregated hydrogenated nitrile rubber prevents the incorporation of platinum group elements into the water-soluble polymer. This problem is less likely to occur, and platinum group elements can be separated from hydrogenated nitrile rubber with higher efficiency. Furthermore, since the agglomerated hydrogenated nitrile rubber is difficult to mix with the water-soluble polymer that precipitates while incorporating platinum group elements, the water-soluble polymer can be easily recovered with high purity and high yield. It can be used for reuse.

The water-soluble polymer solution to be mixed with the water-soluble organic solvent solution of hydrogenated nitrile rubber contains a water-soluble polymer, a water-soluble organic solvent, and water.

The water-soluble polymer used in the present invention is not particularly limited as long as it has water solubility and is soluble in water. Such water-soluble polymers include amino group-containing poly(meth)acrylamide (meaning "amino group-containing polymethacrylamide and/or amino group-containing polyacrylamide"; the same shall apply hereinafter), hydroxy group-containing poly(meth)acrylamide, ) Modified group-containing poly(meth)acrylamide such as acrylamide; amino group-containing (meth)acrylate polymer (meaning "amino group-containing methacrylic polymer and/or amino group-containing acrylic polymer". The same applies hereinafter. ), modified group-containing (meth)acrylate polymers such as carboxykyl group-containing (meth)acrylate polymers, sulfonic acid group-containing (meth)acrylate polymers, and phosphoric acid group-containing (meth)acrylate polymers; Cellulose derivatives such as alkylcellulose, hydroxyalkylcellulose, and alkylhydroxyalkylcellulose; among these, cellulose derivatives have a high affinity with platinum group elements and are more effective in separating platinum group elements from hydrogenated nitrile rubber. From the viewpoint of high performance, modified group-containing (meth)acrylate polymers and modified group-containing poly(meth)acrylamides are preferred, modified group-containing poly(meth)acrylamides are more preferred, and amino group-containing poly(meth)acrylamides are even more preferred. . In addition, from the viewpoint of properly precipitating the water-soluble polymer after incorporating the platinum group element derived from the platinum group element-containing catalyst into the water-soluble polymer, electrically neutral It is preferably a water-soluble polymer (i.e., a water-soluble polymer that has not been cationized or anionized), and an electrically neutral amino group-containing poly(meth)acrylamide (i.e., a water-soluble polymer that has not been cationized or anionized). Particularly preferred are amino group-containing poly(meth)acrylamides).

The amino group-containing poly(meth)acrylamide is not particularly limited as long as it is a polymer mainly composed of amino group-containing (meth)acrylamide units, and at least a portion thereof contains an amino group. Amino group-containing poly(meth)acrylamide is, for example, a homopolymer of amino group-containing (meth)acrylamide monomers, a copolymer of two or more types of amino group-containing (meth)acrylamide monomers, or a copolymer of two or more types of amino group-containing (meth)acrylamide monomers. Examples include copolymers of group-containing (meth)acrylamide and one or more monomers copolymerizable with the group-containing (meth)acrylamide.

As the amino group-containing (meth)acrylamide monomer, N,N-dialkylaminoalkyl (meth)alkylamide is preferable, and N,N-dimethylaminoethyl acrylamide, N,N-dimethylaminoethyl methacrylamide, N,N -diethylaminoethyl acrylamide, N,N-diethylaminoethylmethacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, N,N-diethylaminopropylacrylamide, N,N-diethylaminopropylmethacrylamide More preferred is N,N-dimethylaminoethylmethacrylamide, particularly preferred. The amino group-containing (meth)acrylamide monomer may be used alone or in combination.
The content ratio of amino group-containing (meth)acrylamide monomer units in the amino group-containing poly(meth)acrylamide is preferably 30 to 30, from the viewpoint of further enhancing the separation effect of platinum group elements from hydrogenated nitrile rubber. The amount is 100% by weight, more preferably 50 to 100% by weight, particularly preferably 70 to 100% by weight.

The amino group-containing (meth)acrylate polymer is not particularly limited, as long as it is a polymer containing (meth)acrylic acid ester units as a main component and at least partially contains amino groups. . The amino group-containing (meth)acrylate polymer is, for example, a homopolymer of an amino group-containing (meth)acrylic ester monomer, or a copolymer of two or more amino group-containing (meth)acrylic ester monomers. Examples include a copolymer of one or more amino group-containing (meth)acrylic acid ester monomers and one or more monomers copolymerizable therewith.

Specific examples of amino group-containing (meth)acrylic acid ester monomers include N,N-dimethylaminoethyl acrylate (DMAEA), N,N-dimethylaminoethyl methacrylate (DMAEMA), and N,N-dimethylaminopropyl acrylate. , N,N-dimethylaminopropyl methacrylate, N,N-t-butylaminoethyl acrylate, N,N-t-butylaminoethyl methacrylate, N,N-monomethylaminoethyl acrylate, N,N-monomethylaminoethyl methacrylate, etc. Aminoalkyl (meth)acrylate; N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N,N-dimethylaminopropylacrylamide, N,N N-aminoalkyl (meth)acrylamides such as -dimethylaminopropyl methacrylamide, N,N-dimethylaminoethyl acrylamide, N,N-dimethylaminoethyl methacrylamide, and N-isopropylacrylamide; and the like. The amino group-containing (meth)acrylic acid ester monomers may be used alone or in combination. Among these, aminoalkyl (meth)acrylates are preferred, and N,N-dimethylaminoethyl methacrylate (DMAEMA) is particularly preferred.

Specific examples of copolymerizable monomers include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, itaconic anhydride, and fumaric anhydride; Hydroxyl group-containing vinyls such as hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate; styrene, 2-methylstyrene, t-butylstyrene, chlorstyrene, Aromatic vinyls such as vinyl anisole, vinylnaphthalene, divinylbenzene; Amides such as acrylamide, methacrylamide, N-methylolmethacrylamide, N-methylolacrylamide, diacetone acrylamide, maleic acid amide; Vinyls such as vinyl acetate, vinyl propionate, etc. Ester; vinylidene halides such as vinylidene chloride and vinylidene fluoride; vinyl chloride, vinyl ether, vinyl ketone, vinylamide, chloroprene, ethylene, propylene, isoprene, butadiene, chloroprene, vinylpyrrolidone, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, Glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, acrylonitrile, methacrylonitrile, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,3 -Butylene glycol dimethacrylate, 1,6-hexane diol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol diacrylate, 1,6-hexane diol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate Acrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane triacrylate, tetramethylolmethanetetraacrylate, allyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, isopropenyl-α,α-dimethyl Examples include benzyl isocyanate and allyl mercaptan. The copolymerizable monomers may be used alone or in combination.

The content ratio of the amino group-containing (meth)acrylic acid ester monomer unit in the amino group-containing (meth)acrylate polymer is determined from the viewpoint of further enhancing the separation effect of platinum group elements from hydrogenated nitrile rubber. The amount is preferably 30 to 100% by weight, more preferably 50 to 100% by weight, particularly preferably 70 to 100% by weight.

The weight average molecular weight (Mw) of the water-soluble polymer used in the present invention is preferably 1,000 to 1,500,000, more preferably is 5,000 to 1,200,000, more preferably 10,000 to 1,000,000, even more preferably 20,000 to 1,000,000, even more preferably 100,000 to 1,000, It is 000. The weight average molecular weight (Mw) of a water-soluble polymer can be determined in terms of standard polystyrene or standard polyethylene glycol using gel permeation chromatography.

Examples of the water-soluble organic solvent used for preparing the water-soluble polymer solution include ketones such as acetone, methyl ethyl ketone, diethyl ketone, and methyl isopropyl ketone; ethers such as tetrahydrofuran and dioxane; and esters such as ethyl acetate. Can be mentioned. Among these organic solvents, ketones are preferably used, and acetone is particularly preferably used. In particular, using the same water-soluble organic solvent as the one used in the hydrogenation reaction of nitrile rubber allows for more efficient separation of platinum group elements from hydrogenated nitrile rubber. This method is suitable from the viewpoint of recovering water-soluble polymers in high yield.

The concentration of the water-soluble polymer in the water-soluble polymer solution is said to enable more efficient separation of platinum group elements from hydrogenated nitrile rubber and to recover high-purity water-soluble polymers in high yields. From this point of view, it is preferably 1 to 40% by weight, more preferably 2 to 30% by weight, and still more preferably 5 to 20% by weight.

The weight ratio of the water-soluble organic solvent to water in the water-soluble polymer solution allows for more efficient separation of platinum group elements from hydrogenated nitrile rubber, and also allows high purity water-soluble polymers to be produced in high yield. From the viewpoint of recovery, the ratio is preferably 1:1 to 3:1, more preferably 1.3:1 to 2.5:1, and still more preferably 1.4:1 to 2.3:1.

In addition, the content of water-soluble polymer in the mixed solution obtained by mixing a water-soluble organic solvent solution of hydrogenated nitrile rubber and a water-soluble polymer solution is determined by the separation of platinum group elements from hydrogenated nitrile rubber. From the viewpoint of performing the process more efficiently and recovering high-purity water-soluble polymers at a high yield, it is preferably 0.01 to 50 parts by weight, more preferably 0.01 to 50 parts by weight per 100 parts by weight of hydrogenated nitrile rubber. is 0.05 to 25 parts by weight, more preferably 0.05 to 5 parts by weight, particularly preferably 0.05 to 1 part by weight.

In addition, the concentration of water in the mixture obtained by mixing a water-soluble organic solvent solution of hydrogenated nitrile rubber and a water-soluble polymer solution makes the separation of platinum group elements from hydrogenated nitrile rubber more efficient. In addition, from the viewpoint of recovering high-purity water-soluble polymers in high yield, the amount is preferably 0.005 to 0.060% by weight, more preferably 0.020 to 0.060% by weight, based on the mixed liquid. The amount is 0.050% by weight, more preferably 0.020 to 0.030% by weight.

The stirring method for stirring the liquid mixture is not particularly limited, and examples thereof include a method using a stirrer and a method using a shaker. Among them, a method using a stirrer is preferable. The stirring conditions during stirring are not particularly limited, and the stirring temperature is not particularly limited, but is preferably 5 to 50°C, more preferably 10 to 40°C. The stirring Reynolds number is preferably 900 to 2,500, more preferably 2,000 to 2,300 from the viewpoint of more efficiently separating platinum group elements from hydrogenated nitrile rubber. The stirring Reynolds number (Re) is a value expressed by Re=ρnd ² /μ. Here, ρ is the density of the mixed liquid to be stirred (kg/m ³ ), d is the diameter of the stirring blade (m), μ is the viscosity of the mixed liquid to be stirred (kg/(m・s)), and n is the Each represents the rotational speed (l/s=N/60) of the stirring blade.

According to the present invention, by mixing a water-soluble organic solvent solution of hydrogenated nitrile rubber and a water-soluble polymer solution having a specific composition and then stirring this, the water-soluble organic solvent of hydrogenated nitrile rubber The platinum group element derived from the platinum group element-containing catalyst contained in the solution is incorporated into the water-soluble polymer to precipitate the water-soluble polymer. The content of platinum group elements can be effectively reduced. Specifically, the content of platinum group elements contained in hydrogenated nitrile rubber can be reduced to preferably 50 weight ppm or less, more preferably 40 weight ppm or less, and even more preferably 30 weight ppm or less. It is. Since the hydrogenated nitrile rubber obtained by the present invention has a reduced content of platinum group elements, it is possible to effectively suppress the inhibition of the progress of the crosslinking reaction caused by platinum group elements. As a result, various properties such as heat aging resistance and compression set resistance can be appropriately improved. Furthermore, not only hydrogenated nitrile rubber but also water-soluble polymers used to separate platinum group elements derived from platinum group element-containing catalysts from hydrogenated nitrile rubber can be recovered with high purity and high yield. As a result, the water-soluble polymer can be easily reused, and even when the water-soluble polymer is reused in the method for separating the catalyst component of hydrogenated nitrile rubber, it is possible to easily reuse the water-soluble polymer. Platinum group elements can be efficiently separated from

The present invention will be specifically explained below with reference to Examples and Comparative Examples. In the following, "parts" are based on weight unless otherwise specified. The test and evaluation were as follows.

<Manufacture example 1>
(Production of hydrogenated acrylonitrile-butadiene copolymer)
A reactor was charged with 2 parts of potassium oleate, 180 parts of ion-exchanged water, 37 parts of acrylonitrile, and 0.5 part of t-dodecylmercaptan in this order. Next, after purging the inside of the reactor with nitrogen, 63 parts of butadiene was added, the reactor was cooled to 10°C, and 0.01 part of cumene hydroperoxide and 0.01 part of ferrous sulfate were added. . The contents were then stirred for 16 hours while the reactor was maintained at 10°C. After that, a 5% by weight aqueous hydroquinone solution was added into the reactor to stop the polymerization reaction, and unreacted monomers were removed from the polymerization reaction solution to obtain a latex of acrylonitrile-butadiene copolymer. Ta. The polymerization conversion rate was 90%.

Next, 300 parts of coagulated water in which 3 parts of calcium chloride (coagulant) was dissolved was placed in a separate reactor from the above, and while stirring this at 50°C, the latex obtained above was dropped into the coagulated water. did. Then, an aqueous potassium hydroxide solution was added thereto to precipitate the polymer crumb while maintaining the pH at 11.5, and then the polymer crumb was separated from the coagulated water, washed with water, and then dried under reduced pressure at 50°C. Next, the obtained polymer crumb was dissolved in acetone to prepare an acetone solution having a polymer content of 15% by weight.

Then, a silica-supported palladium (Pd) catalyst (Pd amount is 1000 ppm by weight in the ratio of "Pd metal/acrylonitrile-butadiene copolymer") was added to the acetone solution of the obtained acrylonitrile-butadiene copolymer. was placed in an autoclave equipped with a stirrer, and dissolved oxygen was removed by flowing nitrogen gas for 10 minutes. Next, after replacing the inside of the system with hydrogen gas twice, hydrogen was pressurized at 5 MPa, and the contents were heated to 50° C. and stirred for 6 hours to perform a hydrogenation reaction.

After the hydrogenation reaction was completed, the reaction system was cooled to room temperature, and the hydrogen in the system was replaced with nitrogen. Then, the solution of hydrogenated acrylonitrile-butadiene copolymer obtained by the hydrogenation reaction is filtered to recover the silica-supported palladium catalyst, and the solution of hydrogenated acrylonitrile-butadiene copolymer after filtration is filtered. Obtained.

A portion of the filtered hydrogenated acrylonitrile-butadiene copolymer solution obtained above was collected and poured into 10 times the amount of water to precipitate the copolymer. The copolymer was dried in a vacuum dryer for 24 hours to obtain a solid hydrogenated acrylonitrile-butadiene copolymer. Regarding the obtained solid hydrogenated acrylonitrile-butadiene copolymer, the amount of palladium in the copolymer was measured by atomic absorption spectrometry, and the amount of palladium was 142 ppm by weight. Further, when the iodine value was measured according to JIS K6235, the iodine value was 7.4.

<Manufacture example 2>
(Synthesis of monomer for water-soluble polymer production)
After dissolving 0.005 parts of p-methoxyphenol, 6.0 parts of N,N-dimethylethylenediamine, and 4.5 parts of sodium hydroxide in 35.0 parts of ion-exchanged water, the reactor was cooled to 5°C. Furthermore, 45.0 parts of dichloromethane was added. The reactor was stirred while being maintained at 5°C, and 9.5 parts of methacryloyl chloride was added dropwise over 10 minutes. After stirring for an additional hour while maintaining the reactor at 5°C, extraction was performed four times with dichloromethane. After drying the extract over anhydrous sodium sulfate, the solvent was removed using an evaporator to obtain N-[2-(dimethylamino)ethyl]methacrylamide.

<Manufacture example 3>
(Production of water-soluble polymer)
A reactor was charged with 29.5 parts of N-[2-(dimethylamino)ethyl]methacrylamide obtained in Production Example 2, 70.0 parts of ion-exchanged water, and 0.5 parts of ammonium persulfate, and then the reaction After purging the inside of the reactor with nitrogen, the reactor was heated to 30°C, and the contents were stirred for 96 hours while maintaining the temperature at 30°C. The resulting aqueous polymer solution was dropped into acetone to precipitate the polymer, and then the polymer was separated from the acetone and washed with acetone, followed by drying under reduced pressure at 50°C to form a solid aqueous solution. A polymer (poly(N-[2-(dimethylamino)ethyl]methacrylamide)) was obtained. Regarding the obtained water-soluble polymer, the weight average molecular weight (Mw) in terms of polystyrene was measured by GPC measurement, and the weight average molecular weight (Mw) was 200,000.

<Manufacture example 4>
The water-soluble polymer obtained in Production Example 3 was dissolved in an acetone/water solution in which acetone and distilled water were mixed at a weight ratio of 1.5:1, and the content of the water-soluble polymer was 6. A water-soluble polymer solution having a concentration of 86% by weight was obtained.

<Manufacture example 5>
The water-soluble polymer obtained in Production Example 3 was dissolved in an acetone/water solution in which acetone and distilled water were mixed at a weight ratio of 2.0:1, and the content of the water-soluble polymer was 6.0:1. A water-soluble polymer solution having a concentration of 98% by weight was obtained.

<Manufacture example 6>
The water-soluble polymer obtained in Production Example 3 was dissolved in an acetone/water solution in which acetone and distilled water were mixed at a weight ratio of 1.5:1 to obtain a water-soluble polymer content of 9. A water-soluble polymer solution having a concentration of 15% by weight was obtained.

<Manufacture example 7>
The water-soluble polymer obtained in Production Example 3 was dissolved in an acetone/water solution in which acetone and distilled water were mixed at a weight ratio of 2.0:1, and the content of the water-soluble polymer was 9. A water-soluble polymer solution having a concentration of 30% by weight was obtained.

<Manufacture example 8>
The water-soluble polymer obtained in Production Example 3 was dissolved in an acetone/water solution in which acetone and distilled water were mixed at a weight ratio of 1.5:1 to obtain a water-soluble polymer content of 9. A water-soluble polymer solution having a concentration of 73% by weight was obtained.

<Manufacture example 9>
The water-soluble polymer obtained in Production Example 3 was dissolved in an acetone/water solution in which acetone and distilled water were mixed at a weight ratio of 2.0:1, and the content of the water-soluble polymer was 9. A water-soluble polymer solution having a concentration of 88% by weight was obtained.

<Manufacture example 10>
The water-soluble polymer obtained in Production Example 3 was dissolved in only distilled water (weight ratio of acetone and distilled water 0:1) to obtain a water-soluble polymer with a water-soluble polymer content of 6.86% by weight. A polymer solution was obtained.

<Example 1>
A portion of the filtered solution of the hydrogenated acrylonitrile-butadiene copolymer obtained in Production Example 1 was collected and transferred to a separable flask, and the concentration of the hydrogenated acrylonitrile-butadiene copolymer was 7% by weight. After adjusting the concentration by adding acetone, a portion of this solution was sampled and the concentration of the hydrogenated acrylonitrile-butadiene copolymer solution was measured by the heating loss method, and it was found to be 7.1 wt. %Met. The water-soluble polymer solution obtained in Production Example 4 was added to 100 parts of the hydrogenated acrylonitrile-butadiene copolymer in the hydrogenated acrylonitrile-butadiene copolymer solution so that the amount of the water-soluble polymer was 0. A mixed solution was prepared by adding 0.075 parts. Next, the prepared mixed solution was stirred for 24 hours using two paddle blades (diameter 80 mm) under conditions such that the stirring Reynolds number (hereinafter referred to as stirring Re number) was 2200. After stirring for 24 hours, the water-soluble polymer became solid and precipitated. Next, by performing filtration, it was separated into a filtrate and a filtrate.

Subsequently, the filtered material was washed on the filter paper using 100 cc of acetone. This washing operation was carried out three times in total, and the filtered material was dried in a vacuum dryer for 12 hours. The dried filtrate mainly contained a water-soluble polymer adsorbed with palladium, with a small amount of hydrogenated acrylonitrile-butadiene copolymer remaining. The weight of the dried filtrate was equivalent to 91% by weight based on the weight of the water-soluble polymer charged. The ratio (% by weight) of the weight of the dried filtrate to the weight of the water-soluble polymer charged is shown in Table 1 as the "amino group-containing polyacrylamide recovery rate."

The concentration of the hydrogenated acrylonitrile-butadiene copolymer remaining in the dried filtrate was measured by the following method. The dried filtrate was poured into distilled water to dissolve the water-soluble polymer adsorbed with palladium contained in the filtrate, and the undissolved hydrogenated acrylonitrile-butadiene copolymer was recovered. When the weight of the recovered hydrogenated acrylonitrile-butadiene copolymer was measured, it was found to be 4% by weight based on the weight of the dried filtrate. The ratio of the weight of the hydrogenated acrylonitrile-butadiene copolymer to the weight of the dried filtrate (% by weight) is shown in Table 1 as the "concentration of the hydrogenated acrylonitrile-butadiene copolymer."

From the above, by the separation method using a water-soluble polymer solution, after washing and drying the filtrate three times in total, water-soluble polymers with palladium adsorbed can be recovered with a recovery rate of 91% by weight. It was found that the water-soluble polymer contained only 4% by weight of hydrogenated acrylonitrile-butadiene copolymer.

On the other hand, the acetone used for washing the filtrate was recovered as a filtrate together with the filtrate produced by filtration after stirring the mixed solution for 24 hours. The collected filtrate mainly contained hydrogenated acrylonitrile-butadiene copolymer and acetone, with small amounts of water-soluble polymer, water, and palladium remaining. By adding an equal amount of distilled water to the collected filtrate, a hydrogenated acrylonitrile-butadiene copolymer was precipitated from the filtrate. The obtained precipitate was dried in a vacuum dryer for 24 hours to obtain a solid hydrogenated acrylonitrile-butadiene copolymer. Regarding the obtained copolymer, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer was measured by atomic absorption spectrometry, and the amount of palladium was 34 ppm by weight. At this time, separation efficiency for separating palladium by water-soluble polymer from hydrogenated acrylonitrile-butadiene copolymer (Pd separation efficiency by water-soluble polymer (wt%) = [(hydrogenation before treatment with water-soluble polymer) Amount of palladium in acrylonitrile-butadiene copolymer) - (amount of palladium in hydrogenated acrylonitrile-butadiene copolymer after treatment with water-soluble polymer)] ÷ (hydrogenated acrylonitrile-butadiene before treatment with water-soluble polymer) The amount of palladium in the copolymer (×100) was 76% by weight.

<Example 2>
The same operation as in Example 1 was performed except that the water-soluble polymer solution obtained in Production Example 5 was used. The recovery rate of the water-soluble polymer recovered as a filtrate was 92% by weight, and the amount of hydrogenated acrylonitrile-butadiene copolymer contained therein was 3% by weight. Furthermore, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer recovered as a filtrate was 27 ppm by weight, and the Pd separation efficiency by the water-soluble polymer was 81% by weight.

<Example 3>
A solution of hydrogenated acrylonitrile-butadiene copolymer weighed into a separable flask was added to 100 parts of the hydrogenated acrylonitrile-butadiene copolymer obtained in Production Example 6. The same operation as in Example 1 was performed except that the water-soluble polymer solution obtained was added so that the amount of water-soluble polymer was 0.1 part. The recovery rate of the water-soluble polymer recovered as a filtrate was 91% by weight, and the amount of hydrogenated acrylonitrile-butadiene copolymer contained therein was 5% by weight. Further, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer recovered as a filtrate was 9 ppm by weight, and the Pd separation efficiency by the water-soluble polymer was 94% by weight.

<Example 4>
Add the hydrogenated acrylonitrile-butadiene copolymer solution weighed into a separable flask to 100 parts of the hydrogenated acrylonitrile-butadiene copolymer obtained in Production Example 7. The same operation as in Example 1 was performed except that the water-soluble polymer solution obtained was added so that the amount of water-soluble polymer was 0.1 part. The recovery rate of the water-soluble polymer recovered as a filtrate was 94% by weight, and the amount of hydrogenated acrylonitrile-butadiene copolymer contained therein was 3% by weight. Further, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer recovered as a filtrate was 6 ppm by weight, and the Pd separation efficiency by the water-soluble polymer was 96% by weight.

<Example 5>
Add the hydrogenated acrylonitrile-butadiene copolymer solution weighed into a separable flask to 100 parts of the hydrogenated acrylonitrile-butadiene copolymer obtained in Production Example 8. The same operation as in Example 1 was performed except that the water-soluble polymer solution obtained was added so that the amount of water-soluble polymer was 0.107 parts. The recovery rate of the water-soluble polymer recovered as a filtrate was 91% by weight, and the amount of hydrogenated acrylonitrile-butadiene copolymer contained therein was 5% by weight. Furthermore, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer recovered as a filtrate was 26 ppm by weight, and the Pd separation efficiency by the water-soluble polymer was 82% by weight.

<Example 6>
To the solution of the hydrogenated acrylonitrile-butadiene copolymer weighed in a separable flask, add the hydrogenated acrylonitrile-butadiene copolymer obtained in Production Example 9 to 100 parts of the hydrogenated acrylonitrile-butadiene copolymer in the solution of the hydrogenated acrylonitrile-butadiene copolymer. The same operation as in Example 1 was performed except that the water-soluble polymer solution obtained was added so that the amount of water-soluble polymer was 0.107 parts. The recovery rate of the water-soluble polymer recovered as a filtrate was 95% by weight, and the amount of hydrogenated acrylonitrile-butadiene copolymer contained therein was 4% by weight. Further, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer recovered as a filtrate was 20 ppm by weight, and the Pd separation efficiency by the water-soluble polymer was 86% by weight.

<Example 7>
The same procedure as in Example 1 was performed, except that the concentration of the hydrogenated acrylonitrile-butadiene copolymer in the hydrogenated acrylonitrile-butadiene copolymer solution weighed into a separable flask was adjusted to 2.5% by weight. I did it. The recovery rate of the water-soluble polymer recovered as a filtrate was 93% by weight, and the amount of hydrogenated acrylonitrile-butadiene copolymer contained therein was 3% by weight. Furthermore, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer recovered as a filtrate was 16 ppm by weight, and the Pd separation efficiency by the water-soluble polymer was 89% by weight.

<Example 8>
The same procedure as in Example 1 was performed, except that the concentration of the hydrogenated acrylonitrile-butadiene copolymer in the hydrogenated acrylonitrile-butadiene copolymer solution weighed into a separable flask was adjusted to 9.6% by weight. I did it. The recovery rate of the water-soluble polymer recovered as a filtrate was 92% by weight, and the amount of hydrogenated acrylonitrile-butadiene copolymer contained therein was 3% by weight. Furthermore, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer recovered as a filtrate was 40 ppm by weight, and the Pd separation efficiency by the water-soluble polymer was 72% by weight.

<Comparative example 1>
A portion of the filtered solution of the hydrogenated acrylonitrile-butadiene copolymer obtained in Production Example 1 was collected and transferred to a separable flask, and the concentration of the hydrogenated acrylonitrile-butadiene copolymer was 7% by weight. After adjusting the concentration by adding acetone, a portion of this solution was sampled and the concentration of the hydrogenated acrylonitrile-butadiene copolymer solution was measured by the heating loss method, and it was found to be 7.1 wt. %Met. The water-soluble polymer solution obtained in Production Example 10 was added to 100 parts of the hydrogenated acrylonitrile-butadiene copolymer in the hydrogenated acrylonitrile-butadiene copolymer solution so that the amount of the water-soluble polymer was 0. The total amount was 0.075 parts. Next, stirring was performed for 24 hours using two paddle blades (diameter 80 mm) under conditions such that the stirring Reynolds number (hereinafter referred to as stirring Re number) was 2200. After stirring for 24 hours, the water-soluble polymer became solid and precipitated. Next, by performing filtration, it was separated into a filtrate and a filtrate.

Subsequently, the filtered material was washed on the filter paper using 100 cc of acetone. This washing operation was carried out a total of 8 times, and the filtrate was dried in a vacuum dryer for 12 hours. The dried filtrate mainly contained a water-soluble polymer adsorbed with palladium, with a small amount of hydrogenated acrylonitrile-butadiene copolymer remaining. The weight of the dried filtrate was equivalent to 93% by weight based on the weight of the water-soluble polymer charged.

The content of hydrogenated acrylonitrile-butadiene copolymer remaining in the dried filtrate was measured by the following method. The dried filtrate was poured into distilled water to dissolve the water-soluble polymer adsorbed with palladium contained in the filtrate, and the undissolved hydrogenated acrylonitrile-butadiene copolymer was recovered. The recovered hydrogenated acrylonitrile-butadiene copolymer was weighed and found to be 13% by weight based on the weight of the dried filtrate.

From the above, in Comparative Example 1, the water-soluble polymer adsorbed with palladium was recovered with a recovery rate of 93% by weight after washing and drying the filtrate a total of 8 times, but the recovered water-soluble polymer It was found that the polymer contained as much as 13% by weight of hydrogenated acrylonitrile-butadiene copolymer.

On the other hand, the acetone used for washing the filtrate was recovered as a filtrate together with the filtrate produced by filtration after stirring the mixed solution for 24 hours. The collected filtrate mainly contained hydrogenated acrylonitrile-butadiene copolymer and acetone, with small amounts of water-soluble polymer, water, and palladium remaining. By adding an equal amount of distilled water to the collected filtrate, a hydrogenated acrylonitrile-butadiene copolymer was precipitated from the filtrate. The obtained precipitate was dried in a vacuum dryer for 24 hours to obtain a solid hydrogenated acrylonitrile-butadiene copolymer. Regarding the obtained copolymer, the amount of palladium in the hydrogenated acrylonitrile-butadiene copolymer was measured by atomic absorption spectrometry, and the amount of palladium was 41 ppm by weight. At this time, the Pd separation efficiency by the water-soluble polymer was 71% by weight.

This is because the only solvent for dissolving water-soluble polymers is distilled water, so when a water-soluble polymer solution is added to an acetone solution of hydrogenated acrylonitrile-butadiene copolymer, the hydrogen dissolved in acetone This is because the acrylonitrile-butadiene copolymer aggregated and precipitated together with the water-soluble polymer. Therefore, when washing the filtered water-soluble polymer, the number of washings increased to transfer the aggregates of hydrogenated acrylonitrile-butadiene copolymer to the filtrate side, and the hydrogenation contained in the water-soluble polymer The weight concentration of acrylonitrile-butadiene copolymer has also increased. In addition, since the aggregation and precipitation of the water-soluble polymer and the aggregation of the hydrogenated acrylonitrile-butadiene copolymer occur simultaneously, palladium incorporated inside the agglomerated hydrogenated acrylonitrile-butadiene copolymer becomes highly water-soluble. Pd was not adsorbed to the molecules, and the Pd separation efficiency was slightly inferior.

As shown in Table 1, by using a water-soluble polymer solution containing a water-soluble polymer, a water-soluble organic solvent, and water, and in which the weight ratio of the water-soluble organic solvent to water is within a specific range, hydrogen Palladium can be separated without agglomerating the acrylonitrile-butadiene copolymer, and water-soluble polymers adsorbed with palladium can be easily recovered in high yield. Furthermore, the Pd separation efficiency by the water-soluble polymer at that time was also high, and the results were good (Examples 1 to 8).

Claims (7)

By mixing a water-soluble organic solvent solution of hydrogenated nitrile rubber obtained by hydrogenating nitrile rubber in the presence of a platinum group element-containing catalyst and a water-soluble polymer solution, a mixed solution is prepared. a mixing step to obtain;
a water-soluble polymer precipitation step of precipitating the water-soluble polymer while incorporating the platinum group element into the water-soluble polymer by stirring the mixed solution;
The water-soluble polymer is at least one selected from an electrically neutral modified group-containing (meth)acrylate polymer and an electrically neutral modified group-containing poly(meth)acrylamide,
The water-soluble polymer solution contains the water-soluble polymer, a water-soluble organic solvent, and water, and the weight ratio of the water-soluble organic solvent to water in the water-soluble polymer solution is 1:1 to 3. : A method for separating catalyst components of hydrogenated nitrile rubber according to 1. The method for separating a catalyst component of hydrogenated nitrile rubber according to claim 1, wherein the concentration of water in the mixed liquid is 0.020 to 0.050% by weight. The method for separating a catalyst component of hydrogenated nitrile rubber according to claim 1 or 2, wherein the concentration of the water-soluble polymer in the water-soluble polymer solution is 1 to 40% by weight. The method for separating a hydrogenated nitrile rubber catalyst according to any one of claims 1 to 3, wherein the water-soluble polymer is an electrically neutral modified group-containing poly(meth)acrylamide.. The method for separating a catalyst component of hydrogenated nitrile rubber according to any one of claims 1 to 4 , wherein the water-soluble polymer is an amino group-containing poly (meth) acrylamide. The method for separating a catalyst component of hydrogenated nitrile rubber according to any one of claims 1 to 5 , wherein the platinum group element is palladium. A hydrogenation step of hydrogenating nitrile rubber in a water-soluble organic solvent in the presence of a platinum group element-containing catalyst to obtain a solution of hydrogenated nitrile rubber in a water-soluble organic solvent;
a mixing step of obtaining a mixed solution by mixing the water-soluble organic solvent solution of the hydrogenated nitrile rubber and the water-soluble polymer solution;
a water-soluble polymer precipitation step of precipitating the water-soluble polymer while incorporating the platinum group element into the water-soluble polymer by stirring the mixed solution;
The water-soluble polymer is at least one selected from an electrically neutral modified group-containing (meth)acrylate polymer and an electrically neutral modified group-containing poly(meth)acrylamide,
The water-soluble polymer solution contains the water-soluble polymer, a water-soluble organic solvent, and water, and the weight ratio of the water-soluble organic solvent to water in the water-soluble polymer solution is 1:1 to 3. : 1. A method for producing hydrogenated nitrile rubber.