JP2004043600A - Method for producing hydrogenated conjugated diene-based polymer latex - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simplified production method for hydrogenating a hydrogenated conjugated diene-based polymer, especially a copolymer of a conjugated diene and an α, β-unsaturated nitrile, of the carbon-carbon double bond in a state of a latex, which enables industrial materialization from the aspects of quality and economy. <P>SOLUTION: The method for producing the hydrogenated conjugated diene-based polymer latex comprises at least a process (A) for dissolving or dispersing a platinum group metal-containing hydrogenation catalyst into a conjugated diene-based polymer latex and hydrogenating the carbon-carbon unsaturated bond of the polymer, a process (B) for complexing the platinum group metal with a complexing agent to form a water-insoluble complex and a process (C) for filtering the water-insoluble complex by using a filter having a plurality of filter elements to separate the water-insoluble complex from the hydrogenation reaction mixture. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a hydrogenated conjugated diene polymer latex.
[0002]
[Prior art]
As a useful modification means of a conjugated diene-based polymer, for example, a method of selectively or partially hydrogenating a carbon-carbon unsaturated bond of a polymer, such as a hydrogenated acrylonitrile-butadiene copolymer, is often used. Has been adopted.
As a typical process for producing such a hydrogenated conjugated diene-based polymer, (1) a step of emulsion-polymerizing a monomer containing a conjugated diene and coagulating and drying the obtained latex to prepare a raw material polymer (2) a step of dissolving the raw material polymer in an organic solvent and hydrogenating it using a supported (heterogeneous) catalyst in which a hydrogenation catalyst is supported on a carrier insoluble in the organic solvent; (3) hydrogenation There is known a process comprising a step of separating a supported catalyst from a reaction mixture and then recovering a target hydrogenated polymer from an organic solvent.
[0003]
However, the above process requires an operation of dissolving the raw material polymer once recovered from the latex of the conjugated diene-based polymer in an organic solvent, and distilling off the organic solvent used in the hydrogenation reaction after the reaction. Further, for example, a hydrogenated conjugated diene-based polymer in a latex state may be used for applications such as adhesives, but the above process cannot directly produce a hydrogenated conjugated polymer in such a state.
[0004]
Therefore, there is a strong demand for the development of a process for hydrogenating a conjugated diene polymer in a latex state, and various studies have been made (for example, U.S. Pat. No. 3,898,208 and JP-A-2-178305). Gazettes).
[0005]
When hydrogenation is performed by such a process, the use of a non-supported catalyst that dissolves or disperses in an aqueous medium increases the contact efficiency between the polymer in the latex and the hydrogenation catalyst and improves the hydrogenation activity. It is extremely difficult to separate the catalyst, and there is a problem that the cost of the catalyst is significantly increased because the catalyst cannot be recovered and reused.
[0006]
[Problems to be solved by the invention]
In view of the above circumstances, an object of the present invention is a method for producing a simplified hydrogenated conjugated diene-based polymer latex in which carbon-carbon unsaturated bonds of a conjugated diene-based polymer are hydrogenated in a latex state, in particular, a hydrogenation reaction. An object of the present invention is to provide an industrial method for producing a hydrogenated conjugated diene-based polymer latex that efficiently separates the catalyst used in the above.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies and as a result, dissolved or dispersed a hydrogenation catalyst containing a platinum group element in a conjugated diene-based polymer latex to form a carbon-carbon unsaturated bond of the polymer with hydrogen. In the production method, a complexing agent that forms a water-insoluble complex with the platinum group element was added to the hydrogenation reaction mixture to precipitate the platinum group element. By separating this precipitate using a specific filtration device, it is possible to efficiently recover the hydrogenation catalyst on an industrial scale, and to produce a hydrogenated conjugated diene-based polymer latex having a small amount of remaining catalyst. Heading, the present invention has been completed.
[0008]
That is, in the present invention, a hydrogenation catalyst containing a platinum group element is dissolved or dispersed in a latex of a conjugated diene polymer to hydrogenate carbon-carbon unsaturated bonds of the polymer (A); (B) forming a water-insoluble complex by complexing the platinum group element with a complexing agent; and separating the water-insoluble complex from a hydrogenation reaction mixture by filtration using a filtration device having a plurality of filter elements. (C); The filter element in the form of a cylinder or a hollow disk is preferably housed in a sealable housing, and the filtering device is preferably a fundabag filter or a leaf filter. Further, it is preferable that the filter element is precoated with a filter aid to perform filtration.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the method for producing the hydrogenated conjugated diene polymer latex of the present invention will be described in detail.
[0010]
The production method of the present invention comprises the step of dissolving or dispersing a hydrogenation catalyst containing a platinum group element in a latex of a conjugated diene polymer to hydrogenate carbon-carbon unsaturated bonds of the polymer (A). A step (B) of complexing the platinum group element with a complexing agent to form a water-insoluble complex; and separating the water-insoluble complex from a hydrogenation reaction mixture by filtration using a filtration device having a plurality of filter elements. Step (C);
[0011]
The latex of the conjugated diene-based polymer to which the present method is applied generally contains one or more conjugated diene monomers or one or more monomers copolymerizable with the conjugated diene monomer. It can be obtained by emulsion polymerization in combination with one or more conjugated diene monomers. Latex can also be obtained by a phase inversion method following solution polymerization.
[0012]
The conjugated diene monomer is not particularly limited, and for example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 2-chloro-1 , 3-butadiene, 1,3-pentadiene and the like. Among these, 1,3-butadiene and 2-methyl-1,3-butadiene are preferred, and 1,3-butadiene is more preferred.
[0013]
Examples of monomers copolymerizable with the conjugated diene monomer include α, β-ethylenically unsaturated nitrile monomers such as acrylonitrile, methacrylonitrile, crotonitrile, and vinylidene cyanide; acrylic acid, methacrylic acid Α, β-ethylenically unsaturated carboxylic acids such as crotonic acid, fumaric acid, maleic acid and itaconic acid and their anhydrides; methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, trifluoroacrylate Α, β-ethylenically unsaturated carboxylic esters such as ethyl, methyl methacrylate and methyl crotonate; α, β-ethylenically unsaturated carbonamides such as acrylamide and methacrylamide; styrene, α-methylstyrene, p-methyl Vinyl aromatic compounds such as styrene, divinylbenzene and vinylpyridine ; Vinylether compounds such as fluoroethyl vinyl ether; vinyl acetate, vinyl esters such as vinyl propionate and the like.
[0014]
Among these monomers, from the viewpoint that the hydrogenation reaction in the present invention easily proceeds, a monomer having an electron-withdrawing functional group is preferable, and an α, β-unsaturated nitrile monomer, particularly acrylonitrile, is preferably used. Can be
[0015]
Emulsion polymerization is generally performed in an aqueous medium using a radical polymerization initiator. Known polymerization initiators may be used. The polymerization reaction may be any of a batch system, a semi-batch system, and a continuous system, 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.
[0016]
The monomer composition ratio in the conjugated diene polymer is not particularly limited, but is 5 to 100% by weight of a conjugated diene monomer and 95 to 0% by weight of a monomer copolymerizable therewith, and is preferably a conjugated diene monomer. 10 to 90% by weight of a monomer and 90 to 10% by weight of a monomer copolymerizable therewith. The weight average molecular weight (measured by gel permeation chromatography and calculated in terms of standard polystyrene) is not particularly limited, but is usually 5,000 to 500,000.
[0017]
The solid content concentration of the latex of such a conjugated diene polymer 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, and a concentration method.
[0018]
In the present invention, the step (A) of hydrogenating carbon-carbon unsaturated bonds of a conjugated diene polymer latex in a latex of the polymer is performed as follows.
[0019]
The hydrogenation catalyst containing a platinum group element used in the step (A) is a water-soluble or water-dispersible platinum group element compound, and specifically, ruthenium, rhodium, palladium, osmium, iridium, platinum Is a compound of Such a hydrogenation catalyst is dissolved or dispersed in the above-mentioned latex without being supported on a carrier and subjected to a hydrogenation reaction. As the hydrogenation catalyst, a palladium or rhodium compound is preferable, and a palladium compound is particularly preferable. Further, two or more platinum group element compounds may be used in combination, but also in this case, it is preferable to use a palladium compound as a main catalyst component.
[0020]
The palladium compound is not particularly limited as long as it is water-soluble or water-dispersible, preferably water-soluble, and has hydrogenation catalytic activity. Usually, a palladium compound having a valency of II or IV is used, and its form is a salt or a complex salt.
[0021]
Examples of the palladium compound include: organic acid salts such as palladium acetate, palladium formate, and palladium propionate; inorganic acid salts such as palladium nitrate and palladium sulfate; halogens such as palladium fluoride, palladium chloride, palladium bromide, and palladium iodide Inorganic palladium compounds such as palladium oxide and palladium hydroxide; organic palladium compounds such as dichloro (cyclooctadiene) palladium, dichloro (norbornadiene) palladium and dichlorobis (triphenylphosphine) palladium; sodium tetrachloropalladate, hexachloropalladium acid Halogenated salts such as ammonium; complex salts such as potassium tetracyanopalladate; and the like.
Among these palladium compounds, organic or inorganic acid salts such as palladium acetate, palladium nitrate, and palladium sulfate; palladium chloride; halide salts such as sodium tetrachloropalladate and ammonium hexachloropalladate; Palladium, palladium nitrate and palladium chloride are more preferred.
[0022]
Examples of the rhodium compound include halides such as rhodium chloride, rhodium bromide and rhodium iodide; inorganic acid salts such as rhodium nitrate and rhodium sulfate; rhodium acetate, rhodium formate, rhodium propionate, rhodium butyrate, rhodium valerate and naphthenic acid. Organic acid salts such as rhodium and rhodium acetylacetonate; rhodium oxide; rhodium trihydroxide; and the like.
[0023]
Such a compound of the platinum group element can be obtained from a commercial product, or can be prepared and used by a known method. The method for dissolving or dispersing the compound of the platinum group element in latex is not particularly limited, and a method of directly adding the compound to the latex, a method of dissolving or dispersing the compound in water, and the like are exemplified. In the latter method, for example, when an inorganic acid such as nitric acid, sulfuric acid, hydrochloric acid, bromic acid, perchloric acid, and phosphoric acid; a sodium salt and a potassium salt of the inorganic acid; an organic acid such as acetic acid; Is improved in some cases, which is preferable.
[0024]
The production method of the present invention uses a hydrogenation catalyst as described above dissolved or dispersed in a latex of a conjugated diene-based polymer to efficiently advance the hydrogenation reaction in a latex state. When the reaction is performed under basic conditions, the reaction efficiency is further improved, and the amount of catalyst used can be reduced. Such basic conditions are not particularly limited as long as the pH of the hydrogenation reaction liquid (latex) measured by a pH meter is more than 7, preferably 7.2 to 13, more preferably 7.5 to 12. 0.5, and more preferably 8.0 to 12.
[0025]
The basic compound for making the hydrogenation reaction solution basic is not particularly limited, and examples thereof include an alkali metal compound, an alkaline earth metal compound, ammonia, an ammonium salt compound, and an organic amine compound. Preferred are alkali metal compounds and alkaline earth metal compounds.
[0026]
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; and lithium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. A bicarbonate compound is preferably used, and more preferably an alkali metal hydroxide.
As the alkaline earth metal compound, hydroxides, carbonate compounds and bicarbonate compounds of alkaline earth metals such as magnesium, calcium, strontium and barium are preferably used, and more preferably hydroxide.
Examples of the ammonium salt compound include ammonium carbonate and ammonium hydrogen carbonate.
Examples of the organic amine compound include triethylamine, ethanolamine, morpholine, N-methylmorpholine, pyridine, hexamethylenediamine, dodecamethylenediamine, xylylenediamine, and the like.
[0027]
These basic compounds can be used as they are, or can be used after being diluted or dissolved with water or an organic solvent such as alcohol. The basic compounds 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 exhibits basicity. Further, the method of adding the basic compound to the hydrogenation reaction solution is not particularly limited, and for example, a method of adding the basic compound to the latex in advance before adding the hydrogenation catalyst to the hydrogenation reaction solution. And a method of adding a basic compound after the start of the hydrogenation reaction.
[0028]
Further, a catalyst stabilizer can be used for the purpose of maintaining the stability of the platinum group element compound in the latex. Specific examples of the catalyst stabilizer include polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl acetal, sodium polyacrylate, sodium polyphosphate, gelatin, albumin, protalbic acid, and risalbic acid. Among these, polyvinyl pyrrolidone, polyvinyl alcohol and sodium polyacrylate are particularly preferred.
[0029]
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 not desirable because side reactions such as hydrogenation of a nitrile group may occur. On the other hand, if the reaction temperature is excessively low, the reaction rate decreases, which is not practical.
The pressure of hydrogen is usually 0.1 Mpa to 20 MPa, preferably 0.1 Mpa to 15 MPa, and more preferably 0.1 Mpa to 10 MPa. The reaction time is not particularly limited, but is usually 30 minutes to 50 hours.
[0030]
According to the production method of the present invention, particularly the hydrogenation reaction under basic conditions, the hydrogenation reaction proceeds rapidly despite the reaction in a latex state. The hydrogenation rate of the obtained hydrogenated conjugated diene polymer (the ratio of hydrogenated carbon-carbon double bonds to the total number of carbon-carbon double bonds present in the polymer before the reaction) is determined by the above-described various types. By appropriately changing the reaction conditions, it can be arbitrarily controlled in the range of 1 to 100%. The hydrogenation rate represented by the iodine value is preferably 120 or less.
[0031]
In the present invention, the step (B) of forming a water-insoluble complex by complexing a platinum group element with a complexing agent is performed as follows.
[0032]
In the step (B), the platinum group element in the platinum group element compound present in the aqueous medium or the polymer particles of the latex of the conjugated diene polymer after the completion of the hydrogenation reaction is complexed with a complexing agent. To form a water-insoluble complex. The complex forms as a precipitate in the latex.
[0033]
The complexing agent is preferably added to the latex after completion of the hydrogenation reaction in the form of a powder, a solution or a dispersion. Specifically, the complexing agent is brought into contact with the platinum group element compound by stirring, mixing, or the like to form a complex. The complex precipitates in the latex, but in order to grow or agglomerate to a particle size larger than the polymer particles, it is preferable to perform steps of stirring under heating, followed by standing, and cooling. The latex pH at the time of complex formation is preferably adjusted to about 8 to 10.5.
[0034]
The complexing agent is not particularly limited as long as it forms a water-insoluble complex with a platinum group element, but a complexing agent which forms a water-insoluble complex having strong cohesion is preferable. Specifically, for example, an oxime compound is mentioned, and a dioxime compound is preferable from the viewpoint of the strength of complex formation power, and α, β-alkanedione dioxime such as dimethylglyoxime and cyclohexanedionedioxime is more preferable. Among them, dimethylglyoxime is most preferred. The amount of the complexing agent to be used is generally 1 to 50 times, preferably 2 to 30 times, the mole of the platinum group element contained in the used catalyst.
[0035]
In the present invention, before or simultaneously with the step (B), the oxidation treatment is preferably carried out by bringing a reduced catalyst present in the system after the completion of the hydrogenation reaction into contact with an oxidizing agent. By performing the oxidation treatment, the complex is more easily generated in the step (B).
[0036]
The oxidizing agent is not particularly limited as long as it has catalytic oxidizing ability, and examples thereof include air (oxygen); peroxides such as hydrogen peroxide, peracetic acid, and perbenzoic acid; and the like. Hydrogen peroxide, more preferably hydrogen peroxide.
The amount of these oxidizing agents to be used is not particularly limited, but is 1 to 100 times, preferably 3 to 50 times the mol of the platinum group element contained in the catalyst used for the hydrogenation reaction. The contact temperature is usually 0 to 100 ° C, preferably 50 to 95 ° C, more preferably 70 to 90 ° C. The contact time is usually 10 minutes to 20 hours, preferably 30 minutes to 10 hours.
The method of contact between the catalyst and the oxidizing agent is not uniform depending on the type of the oxidizing agent, but when air is used as the oxidizing agent, a method of continuously blowing air into the reaction mixture in an open state; A method in which the atmosphere in the gas phase of a certain reaction mixture container is air and the reaction mixture is stirred. When hydrogen peroxide is used, it may be added to the reaction mixture and stirred.
[0037]
In the present invention, the step (C) of separating a water-insoluble complex of a platinum group element is performed as follows. That is, the reaction mixture containing the insoluble complex of the platinum group element precipitated and formed in the latex in the step (B) is filtered using a filtration device having a plurality of filter elements to separate the insoluble complex from the reaction mixture. .
[0038]
The filtration device used in the step (C) includes a plurality of filter elements housed in a sealable housing. The “filter element” refers to the entirety of a member having a “filtration” function of a filtration device, such as a case where only a filter medium is used or a case where a filter medium and a filter plate are used.
[0039]
The filter device preferably has a filter element having a cylindrical or hollow disk shape, and the number thereof is preferably 5 or more, more preferably 10 or more. When the shape of the filter element is cylindrical or disk-shaped, and the filtration device has the above-mentioned number of the filter elements, the filtration area is increased and the filtration speed is improved.
[0040]
The filter element of the filtration device used in the present invention has a structure that allows passage of the hydrogenated conjugated diene polymer latex of the reaction mixture of step (B) but does not allow passage of the water-insoluble complex. Specifically, a filter medium having pores of such a size is used. Examples of the material include natural fibers, synthetic fibers, metals, synthetic resins, and ceramics. These filter media may be used in combination.
The filter plate of the filter element is preferably made of metal or synthetic resin from the viewpoint of strength and the like. The metal is preferably stainless steel, and the synthetic resin is preferably reinforced polypropylene resin, polyvinylidene fluoride resin, polyphenylene sulfide, or the like.
[0041]
It is preferable that the housing of the filtration device is open to the outside only with a housing hole for introducing a substance to be filtered and for extracting a filtrate. It is preferable that a pipe or the like from the outside of the housing is directly connected to the housing hole.
In the above-mentioned filtration device, the reaction mixture, which is a substance to be filtered, is filled into the housing from the housing hole through the pipe. The inside of the housing is pressurized by filling the reaction mixture, the reaction mixture is filtered when passing through the filter element, and the filtrate (latex) is taken out. Then, the water-insoluble complex of the platinum group element is captured on the filter element.
[0042]
Examples of the above-mentioned filtration device include a filtration device generally known as a pressurized filter, such as a fundaback filter or a leaf filter.
[0043]
In the present invention, it is preferable to pre-coat the filter element with a filter aid such as diatomaceous earth in order to perform efficient filtration without clogging. Specifically, a suspension of the filter aid is filled in the housing before the supply of the substance to be filtered, and the suspension is filtered to form a precoat layer of the filter aid on the filter element.
[0044]
The insoluble complex of the platinum group element captured on the filter element is blown off from the filter element by passing air or the like through the filter element in a direction opposite to the filtration direction, and can be recovered together with the filter aid.
[0045]
In the production method of the present invention, in particular, as a result of employing the separation step (C) of the hydrogenation catalyst containing the platinum group element as described above, the hydrogenated conjugated diene-based polymer from which the platinum group element compound is almost completely removed is obtained. Latex can be obtained. The recovery rate of the platinum group element can be 90% or more based on the platinum group element used in the hydrogenation reaction, and can be 95% or more if conditions are selected. The content (residual amount) of the platinum group element in the latex is usually 200 ppm or less. In addition, if the amount of the catalyst is reduced by a reaction under basic conditions or the like, a hydrogenated conjugated diene-based polymer latex having a platinum group element content of 100 ppm or less per polymer can be obtained.
[0046]
Further, in order to separate a hydrogenated polymer rubber from the hydrogenated conjugated diene-based polymer latex obtained by the production method of the present invention into a rubber product, a method generally used in industry may be appropriately employed. . For example, a polymer latex is added with a coagulant such as aluminum sulfate, magnesium sulfate, and calcium chloride to obtain a crumb, and, if necessary, washed with water, and then drained, dried with hot air, dried under reduced pressure, or subjected to a drying step such as extrusion drying. Thus, a hydrogenated conjugated diene polymer rubber can be obtained.
[0047]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Parts and% in these examples are by weight unless otherwise specified.
[0048]
The hydrogenation rate of the hydrogenated conjugated diene polymer was measured by proton NMR. The amount of palladium in the hydrogenated conjugated diene polymer rubber was measured by atomic absorption spectrometry after a part of the hydrogenated polymer rubber was carbonized / ashed at 600 ° C., dissolved in sulfuric acid. Since the hydrogenated polymer rubber whose palladium amount was measured was obtained by concentrating and drying the entire amount of the hydrogenated polymer latex using a rotary evaporator, the amount of palladium contained in the polymer latex and the rubber was the same. It is.
[0049]
Example 1
An autoclave was charged sequentially 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 the inside of the reactor was replaced with nitrogen, 63 parts of butadiene were sealed. The reactor was cooled to 10 ° C., and 0.01 part of cumene hydroperoxide and 0.01 part of ferrous sulfate were added. Next, the reactor was stirred for 16 hours while maintaining the reactor at 10 ° C., and the contents were thoroughly mixed and polymerized. Thereafter, a 10% aqueous solution of hydroquinone was added into the reactor to terminate the polymerization. The polymerization conversion was 90%. Unreacted monomers were removed from the polymerization reaction solution to obtain an acrylonitrile-butadiene copolymer (NBR) latex to be subjected to a hydrogenation reaction.
[0050]
Polyvinylpyrrolidone having a weight average molecular weight of 5,000 was added to 300 L of a palladium catalyst acidic aqueous solution obtained by adding 5-fold molar equivalent of nitric acid to palladium acetate (the used amount is 800 ppm in the ratio of Pd metal / NBR) to palladium. 5 times by weight. Further, a potassium hydroxide aqueous solution was added to prepare a catalyst aqueous solution A having a pH of 9.0.
[0051]
The total amount of 400 L of the NBR latex (solid content: 120 kg) and the total amount of the aqueous catalyst solution A adjusted to a total solid concentration of 30% were charged into an autoclave equipped with a stirrer, and nitrogen gas was flown for 10 minutes to remove dissolved oxygen in the latex. After the inside of the system was replaced with hydrogen gas twice, 3 MPa of hydrogen was pressurized. The contents were heated to 50 ° C. and reacted for 6 hours to obtain a hydrogenated NBR reaction mixture in a latex state.
[0052]
24 L of 30% hydrogen peroxide solution was added to the reaction mixture in the latex state, followed by stirring at 80 ° C. for 2 hours (oxidation treatment). Next, the pH of the reaction mixture (latex) was adjusted to 9.5, and dimethylglyoxime equivalent to 5 times the molar amount of palladium contained in the catalyst aqueous solution A was added as powder. Then, when the mixture was heated to 80 ° C. and stirred for 5 hours, insolubles were precipitated in the latex.
[0053]
The reaction mixture containing the insolubles was filtered using a Fundabac filter (manufactured by Ishikawajima-Harima Heavy Industries, Ltd., trade name: FUNDABAC, see FIG. 1). The fundaback filter has a large number of tubular filter elements 1 (16 to 218 depending on the model) in a sealable housing 2. Each filter element 1 has a tubular filter plate covered with a filter cloth 7, and the tubular filter plate comprises a candle piece 5 through which filtrate passes and a riser pipe 6 at the center where the filtrate collects. (See FIG. 2).
The filter element was precoated with radiolite (diatomaceous earth) suspension, and then filtered under pressure.
The obtained white filtrate was concentrated under reduced pressure by a rotary evaporator to obtain solid hydrogenated NBR. The hydrogenation rate of the hydrogenated NBR was 93%. The amount of palladium in the hydrogenated NBR was 40 ppm. Further, the amount of palladium lost due to leakage at the time of filtration or adhesion to the housing wall was only 1% of the amount used for the hydrogenation reaction.
[0054]
Example 2
The same operation as in Example 1 was performed except that the filtration was performed using a leaf filter (manufactured by Ishikawajima-Harima Heavy Industries, Ltd.) as a filtration device. The leaf filter has twelve disc-shaped filter elements, which are attached to a cylindrical core passing through a central portion. One end of the cylindrical core is closed, and the other end is opened to the outside through the wall of the housing. Each of the filter element mounting portions has at least one core hole, and the filtrate filtered by the filter element is used for filtering. It is structured to be collected and taken out. Each filter element has a stainless steel wire mesh as a filter medium. Precoating with radio light was performed in the same manner as in Example 1. The time required to obtain the same amount of filtrate as in Example 1 was the same as in Example 1.
The amount of palladium in the obtained hydrogenated NBR was 40 ppm. In addition, the amount of palladium lost due to leakage at the time of filtration or adhesion to the housing wall surface was 3% of the amount used for the hydrogenation reaction.
[0055]
Comparative Example 1
The same operation as in Example 1 was performed except that the filtration was performed using a membrane filter (manufactured by Millipore) having only one filter element covered with a polytetrafluoroethylene membrane as a filtration device. No pre-coating with radio light was performed.
Although the amount of palladium in the obtained hydrogenated NBR was 40 ppm, the filter element was replaced once because clogging occurred during filtration. The time required to obtain the same amount of filtrate as in Example 1 was twice as long as that in Example 1. As a result, the loss of palladium was 15% of the amount used for the hydrogenation reaction.
[0056]
As is clear from Examples 1 and 2 and Comparative Example 1, when filtration is performed using a membrane filter having only one filter element, the filtration speed decreases, clogging occurs, and catalyst loss also occurs. large. In contrast, it was confirmed that when filtration was performed using a filtration device having a plurality of filter elements, the used catalyst could be efficiently separated without loss, and a polymer having a small residual amount of palladium was obtained.
[0057]
【The invention's effect】
According to the method for producing a hydrogenated conjugated diene polymer latex of the present invention, since a non-supported (homogeneous) hydrogenation catalyst dissolved or dispersed in water is used, the catalyst for the conjugated diene polymer in the latex is used. And the hydrogenation reaction proceeds rapidly. Then, the used catalyst is a water-insoluble complex, and by using this as a filter having a plurality of filter elements, efficient filtration and recovery can be achieved, and a production process having high practical value in industry can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic view of one filtering device that can be used in the present invention.
FIG. 2 is an enlarged schematic view of a filter element of the filtration device of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Filter element 2 Housing 3 Stock solution inlet 4 Filtrate outlet 5 Candle piece 6 Riser pipe 7 Filter cloth 8 Precoat layer

Claims (4)

Dissolving or dispersing a hydrogenation catalyst containing a platinum group element in a latex of a conjugated diene polymer to hydrogenate carbon-carbon unsaturated bonds of the polymer (A); (B) forming a water-insoluble complex by complexing with a reagent; and (C) separating the water-insoluble complex from the hydrogenation reaction mixture by filtration using a filtration device having a plurality of filter elements. A method for producing a hydrogenated conjugated diene-based polymer latex, comprising: The method according to claim 1, wherein the filter element having a tubular or hollow disk shape is housed in a sealable housing. 3. The method according to claim 1, wherein the filtration device is a fundabag filter or a leaf filter. The production method according to claim 1, wherein the filtration is performed by pre-coating the filter element with a filter aid.

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