JP4124004B2 - Hydrogenated conjugated diene polymer latex, process for producing the same, and hydrogenated conjugated diene polymer rubber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogenated conjugated diene-based polymer latex scan manufacturing how.
The hydrogenated conjugated diene polymer latex obtained by the production method of the present invention is characterized in that the amount of residual hydrogenation catalyst contained in the hydrogenated conjugated diene polymer constituting the latex is extremely low.
[0002]
[Prior art]
As a useful modification means of a conjugated diene polymer, there is often a method of selectively or partially hydrogenating a carbon-carbon unsaturated bond of a polymer such as a hydrogenated acrylonitrile-butadiene copolymer. It has been adopted. Hydrogenated conjugated diene polymer rubber is excellent in various properties such as oil resistance, weather resistance, ozone resistance, heat resistance, and cold resistance, and is therefore used in a wide range of industrial applications.
[0003]
As a typical process for producing such a hydrogenated conjugated diene polymer, (1) a step of emulsion polymerizing a monomer containing a conjugated diene and coagulating and drying the resulting latex to prepare a raw material polymer (2) a step of hydrogenating using a supported (heterogeneous) catalyst in which a raw material polymer is dissolved in an organic solvent and a hydrogenation catalyst is supported on a carrier insoluble in the organic solvent; (3) hydrogenation 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 is known.
[0004]
However, in the above process, the raw material polymer once recovered from the latex of the conjugated diene polymer is crushed with a crusher or the like and dissolved again in the organic solvent, or the organic solvent used in the hydrogenation reaction is distilled off after the reaction. It is difficult to say that it is too diverted and efficient. In addition, for example, it is conceivable to use a hydrogenated conjugated diene polymer in a latex state for applications such as an adhesive, but the above process cannot directly produce a hydrogenated polymer in such a state.
[0005]
Therefore, development of a process for hydrogenating a conjugated diene polymer in a latex state has been strongly demanded, and various studies have been made (see, for example, Patent Document 1 and Patent Document 2).
However, in a hydrogenation reaction in a latex state containing an aqueous medium, when a supported catalyst such as the conventional process is used, the catalytic activity is not sufficiently satisfactory. In addition, when a non-supported catalyst that is dissolved or dispersed in an aqueous medium is used, it is extremely difficult to separate the catalyst after completion of the reaction, and the catalyst cost cannot be recovered and reused. was there. In addition, when a hydrogenated conjugated diene polymer in a latex state is used as a product, a large amount of residual catalyst is mixed and quality problems such as coloring are likely to occur.
[0006]
[Patent Document 1]
US Pat. No. 3,898,208 [Patent Document 2]
JP-A-2-178305 gazette
[Problems to be solved by the invention]
In view of the above circumstances, an object of the present invention is a hydrogenated conjugated diene polymer latex that has an extremely low residual amount of metal derived from the hydrogenation catalyst used in the production process, is inexpensive, and has no quality problems such as coloring. Another object of the present invention is to provide a hydrogenated conjugated diene polymer rubber.
Still another object of the present invention is to provide a simplified method for producing a hydrogenated conjugated diene polymer latex in which a carbon-carbon unsaturated bond of a conjugated diene polymer is hydrogenated in a latex state, particularly a catalyst used in a hydrogenation reaction. An object of the present invention is to provide a process for producing a hydrogenated conjugated diene polymer latex that is easily separated and industrially advantageous.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the inventors of the present invention dissolved or dispersed a hydrogenation catalyst containing a platinum group element compound in a conjugated diene polymer latex, Hydrogenate carbon-carbon unsaturated bonds, and then add precipitates formed by adding a complexing agent that forms a water-insoluble complex with platinum group elements into the latex of the hydrogenated polymer to be produced by means such as filtration. It has been found that a hydrogenated conjugated diene polymer latex having a low content of metal derived from a hydrogenation catalyst can be produced very efficiently by separation.
[0009]
In addition, since the improved method as described above is (1) a non-supported catalyst dissolved or dispersed in the latex, it is easy to contact or incorporate the catalyst into the conjugated diene polymer in the latex. The hydrogenation reaction proceeds promptly; (2) the used hydrogenation catalyst can be easily recovered and reused, so there is no problem in economy even if a large amount of catalyst is used; (3) Since the amount of the residual catalyst in the latex obtained is extremely small, it has been confirmed that the latex has no adverse effect on the quality of the latex product or rubber product, and the present invention has been completed.
[0011]
Thus, according to the present invention, a hydrogenation catalyst containing a platinum group element compound is dissolved or dispersed in a latex of a conjugated diene polymer to hydrogenate the carbon-carbon unsaturated bond of the polymer, Production of a hydrogenated conjugated diene polymer latex characterized by separating a precipitate formed by adding a complexing agent that forms a water-insoluble complex with a platinum group element in a latex of a hydrogenated polymer to be formed A method is provided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
It will be described in detail with the hydrogenated conjugated diene-based polymer latex scan of manufacturing how the present invention.
Latex hydrogenated conjugated diene polymer obtained by the process of the invention features that the content of platinum group elements is not more than 100ppm based on polymer weight. The content of platinum group elements is preferably not more than 80 ppm, more preferably 50ppm or less.
[0013]
Further, hydrogenated conjugated diene polymer rubber of the present invention is a rubber obtained by separating from the latex, to characterized in that the content of platinum group elements is not more than 100ppm based on polymer weight The The content of platinum group elements is preferably not more than 80 ppm, more preferably 50ppm or less.
The content of platinum group elements derived from the hydrogenation catalyst is significantly low well water iodination conjugated diene polymer rubber and latex as described above, there is no quality problems such as coloring. The lower the platinum group element content, the better. The lower limit is not limited, but in general, a hydrogenated conjugated diene polymer rubber having a content per polymer rubber of about 5 ppm or less is advantageously produced industrially. It is difficult.
[0014]
Although the weight average molecular weight (gel permeation chromatography method, standard polystyrene conversion) of the hydrogenated conjugated diene polymer constituting the latex is not particularly limited, it is usually in the range of 5,000 to 500,000.
The solid content concentration of the latex of the conjugated diene polymer as described above is not particularly limited, but is usually 2 to 70% by weight, preferably 5 to 60% by weight. The solid content concentration can be appropriately adjusted by a known method such as a blending method, a dilution method, or a concentration method.
[0015]
As described above, the latex containing a hydrogenated conjugated diene polymer having a reduced platinum group element content is useful as an adhesive, a coating agent, a paint, a dip-formed glove raw material, or the like. Since the amount of residual platinum group elements in latex is remarkably reduced, when used as an adhesive, coating agent, paint, etc., the corrosion resistance of the deposited or coated metal material is high, and the cause is residual platinum group elements. Since there is no darkening, coating agents and paints have a high degree of freedom in coloring. A glove obtained by dip-molding latex is suitable for work such as a semiconductor device manufacturing process.
[0016]
The latex of the hydrogenated conjugated diene polymer of the present invention is prepared by dissolving or dispersing a hydrogenation catalyst containing a platinum group element compound in a conjugated diene polymer latex to thereby remove the carbon-carbon unsaturated bond of the polymer. This is produced by a method of separating a precipitate formed by adding a complexing agent that forms a water-insoluble complex with a platinum group element in a hydrogenated polymer latex.
The latex of a conjugated diene polymer to which the present method can be applied is a latex comprising a homopolymer or a copolymer of a conjugated diene monomer, and one or more conjugated diene monomers, or a conjugated diene monomer It is produced by a conventionally known emulsion polymerization method by combining one or more monomers that can be copolymerized with one or more monomers and one or more conjugated diene monomers.
[0017]
The conjugated diene monomer is not particularly limited as long as it is a polymerizable monomer having a conjugated diene structure. For example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3 -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 preferable, and 1,3-butadiene is particularly preferable.
[0018]
Examples of the monomer copolymerizable with the conjugated diene monomer include α, β-ethylenically unsaturated nitrile monomers such as acrylonitrile, methacrylonitrile, crotonnitrile, vinylidene cyanide; acrylic acid, methacrylic acid , Crotonic acid, fumaric acid, maleic acid, itaconic acid and other α, β-ethylenically unsaturated carboxylic acids; methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, trifluoroethyl acrylate, methyl methacrylate, methyl crotonate, etc. Α, β-ethylenically unsaturated carboxylic acid esters of α, β-ethylenically unsaturated carboxylic acid amides such as acrylamide and methacrylamide; styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, vinylpyridine, etc. Vinyl aromatic compounds; And vinyl esters such as vinyl acetate and vinyl propionate; vinyl ether compounds such as fluoroethyl vinyl ether; and the like.
[0019]
Among these monomers, from the viewpoint of facilitating the hydrogenation reaction in the present invention, a monomer having an electron-withdrawing functional group is preferable, and an α, β-ethylenically unsaturated nitrile monomer, particularly acrylonitrile is preferable. Preferably used.
The monomer composition ratio in the conjugated diene polymer is not particularly limited, but is usually 5 to 100% by weight of the conjugated diene monomer and 95 to 0% by weight of the monomer copolymerizable therewith, preferably conjugated. It is 10 to 90% by weight of diene monomer, and 90 to 10% by weight of monomer copolymerizable therewith.
A suitable conjugated diene polymer is a copolymer of a conjugated diene monomer and an α, β-ethylenically unsaturated nitrile monomer, particularly 30 to 95% by weight of 1,3-butadiene, more preferably 45 It is a copolymer composed of ˜85 wt% and acrylonitrile 5˜70 wt%, more preferably 15˜55 wt%.
[0020]
Emulsion polymerization is generally performed in an aqueous medium using a radical polymerization initiator. A known polymerization initiator may be used. The polymerization reaction may be any of batch, semi-batch and continuous, and the polymerization temperature and pressure are not particularly limited. The emulsifier to be used is not particularly limited, and an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, and the like can be used, and an anionic surfactant is preferable. These emulsifiers may be used alone or in combination of two or more. The amount used is not particularly limited.
[0021]
The hydrogenation catalyst used in the production method of the present invention is a water-soluble compound or water-dispersible compound of a platinum group element (ruthenium, rhodium, palladium, osmium, iridium, platinum). 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, palladium or a rhodium compound is preferable, and a palladium compound is particularly preferable. Two or more platinum group element compounds may be used in combination, but in this case as well, it is preferable to use a palladium compound as the main catalyst component.
[0022]
The palladium compound is not particularly limited as long as it is water-soluble or water-dispersible, preferably water-soluble, and has hydrogenation catalyst activity. Usually, a divalent or IV valent palladium compound is used, and its form is a salt or a complex salt.
Examples of the palladium compound include organic acid salts such as palladium acetate and palladium cyanide; halides such as palladium fluoride, palladium chloride, palladium bromide and palladium iodide; oxygen acid salts such as palladium nitrate and palladium sulfate; Palladium; Palladium hydroxide; Palladium compounds such as dichloro (cyclooctadiene) palladium, dichloro (norbornadiene) palladium, dichlorobis (triphenylphosphine) palladium, sodium tetrachloropalladate, ammonium hexachloropalladate; potassium tetracyanopalladate, etc. Complex salts; and the like.
[0023]
Among these palladium compounds, palladium acetate, palladium nitrate, palladium sulfate, palladium chloride, sodium tetrachloropalladate, and ammonium hexachloropalladate are preferable, and palladium acetate, palladium nitrate, and palladium chloride are more preferable.
Examples of rhodium compounds 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;
[0024]
Such platinum group element compounds are commercially available, or can be prepared and used by known methods. In addition, a method for dissolving or dispersing the platinum group element compound in the latex is not particularly limited, and examples thereof include a method in which the compound is directly added to the latex and a method in which the compound is dissolved or dispersed in water. In the latter method, for example, inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, bromic acid, perchloric acid and phosphoric acid; sodium salts and potassium salts of these inorganic acids; organic acids such as acetic acid; In some cases, the solubility of is improved.
[0025]
In the method for producing a conjugated diene polymer latex according to the present invention, the above hydrogenation catalyst is dissolved or dispersed in the latex of the conjugated diene polymer, thereby allowing the hydrogenation reaction in the latex state to proceed efficiently. Can be made. When the hydrogenation reaction is carried out under basic conditions, the reaction efficiency can be 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 solution (latex) measured with a pH meter is more than 7, preferably 7.2 to 13, more preferably 7.5 to 12. .5, more preferably in the range of 8.0-12.
[0026]
The basic compound for making the hydrogenation reaction liquid basic is not particularly limited, and examples thereof include alkali metal compounds, alkaline earth metal compounds, ammonia, ammonium salt compounds, and organic amine compounds. Preferred are alkali metal compounds and alkaline earth metal compounds.
[0027]
Examples of the alkali metal compound include hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; carbonate compounds such as lithium carbonate, sodium carbonate and potassium carbonate; lithium hydrogen carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate Hydrogen carbonate compounds such as: oxides such as lithium oxide, potassium oxide and sodium oxide; organic acid salt compounds such as potassium acetate and sodium acetate; lithium methoxide, lithium ethoxide, sodium methoxide, sodium ethoxide, potassium alkoxides such as t-butoxide; phenoxides such as sodium phenoxide and potassium phenoxide; and the like. Preferred are alkali metal hydroxides, carbonate compounds, and bicarbonate compounds, and more preferred are hydroxides.
[0028]
Examples of the alkaline earth metal compound include hydroxides, carbonate compounds, bicarbonate compounds, oxides, organic acid salt compounds, alkoxides, phenoxides of alkaline earth metals such as magnesium, calcium, strontium, and barium. Is mentioned. Alkali earth metal hydroxides, carbonate compounds and bicarbonate compounds are preferred, and hydroxides are more preferred.
[0029]
Examples of ammonium salt compounds include ammonium carbonate and ammonium hydrogen carbonate. Examples of organic amine compounds include aliphatic, alicyclic, aromatic mono- and polyamino compounds, such as triethylamine, ethanolamine, morpholine, N-methylmorpholine, pyridine, hexamethylenediamine, dodecamethylenediamine, xylylene diene. Examples include amines.
[0030]
These basic compounds can be used as they are, or can be used by diluting or dissolving with an organic solvent such as water or alcohol. A basic compound may be used individually or may use 2 or more types together, What is necessary is just to select the usage-amount suitably so that a hydrogenation reaction liquid may show basicity. Further, the method and timing for adding the basic compound to the hydrogenation reaction liquid are not particularly limited. For example, the basic compound is added to the latex in advance before adding the hydrogenation catalyst to the hydrogenation reaction liquid. And a method of adding a basic compound after the start of the hydrogenation reaction.
[0031]
Furthermore, for the purpose of maintaining the stability of the platinum group element compound in the latex, as a hydrogenation catalyst stabilizer, the weight average molecular weight which is soluble or dispersible in the latex is preferably 1,000 to 100,000. Preferably, a polymer compound having a molecular weight of 2,000 to 50,000 can be used. By adding the stabilizer, the catalytic activity of the hydrogenation catalyst is increased, the amount of catalyst used can be reduced, and the storage stability of the catalyst solution can be improved.
[0032]
The hydrogenation catalyst stabilizer is soluble or dispersible in latex (refers to a stable dispersion state like a colloid), and does not cause aggregation or precipitation in the latex. As long as it can be maintained in a dissolved or dispersed state. Specific examples of hydrogenation catalyst stabilizers include polymers of vinyl compounds having a polar group in the side chain such as polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl acetal, polyalkyl vinyl ether; sodium polyacrylate, potassium polyacrylate, etc. Metal salts of polyacrylic acid; polyethers such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer; cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose; natural polymers such as gelatin and albumin; It is done. Among these, a polymer or polyether of a vinyl compound having a polar group in the side chain is preferable, and polyvinyl pyrrolidone or polyalkyl vinyl ether is particularly preferable.
[0033]
The hydrogenation catalyst stabilizer can be dissolved or dispersed in the latex together with the hydrogenation catalyst and used for the hydrogenation reaction. In this case, the concentration of the hydrogenation catalyst stabilizer in the latex is preferably 0.5 to 20 times by weight, more preferably 1 to 10 times by weight with respect to the metal element in the hydrogenation catalyst.
[0034]
The hydrogenation catalyst stabilizer can be dissolved or dispersed in water or an organic solvent together with the hydrogenation catalyst, prepared in advance as a hydrogenation catalyst solution, and subjected to a hydrogenation reaction. When the catalyst solution is an aqueous solution, for example, inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, bromic acid, perchloric acid and phosphoric acid; metal salts such as sodium salts and potassium salts of these inorganic acids; organic such as acetic acid Acid; and the like, and the addition of the acid may improve the solubility of the hydrogenation catalyst in water. In this case, the concentration of the acid in the catalyst aqueous solution is preferably 1 to 20 times by mole, more preferably 1 to 10 times by mole with respect to the metal element in the hydrogenation catalyst.
[0035]
In particular, the method for preparing the catalyst aqueous solution preferably includes a step of adding the hydrogenation catalyst stabilizer of the present invention to the aqueous solution following the step of preparing an acidic aqueous solution of the hydrogenation catalyst.
Even if the catalyst aqueous solution is allowed to stand at 25 ° C. for 1 hour or longer, preferably 1 day or longer, more preferably 14 days or longer after preparation, the hydrogenation catalyst does not aggregate or precipitate.
[0036]
The temperature of the hydrogenation reaction is usually 0 ° C to 200 ° C, preferably 5 ° C to 150 ° C, more preferably 10 to 100 ° C. An excessively high reaction temperature is undesirable because side reactions such as hydrogenation of nitrile groups may occur. On the other hand, when the reaction temperature is excessively lowered, the reaction rate is lowered, which is not practical.
The pressure of hydrogen is usually atmospheric pressure to 20 MPa, preferably atmospheric pressure to 15 MPa, more preferably atmospheric pressure to 10 MPa. Although reaction time is not specifically limited, Usually, it is 30 minutes-50 hours.
[0037]
According to the method for producing a conjugated diene polymer latex of the present invention, particularly the hydrogenation reaction under basic conditions, the hydrogenation reaction proceeds rapidly despite the reaction in the latex state. The hydrogenation rate of the resulting 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) By appropriately changing the reaction conditions, it can be arbitrarily controlled within the range of 1 to 100%. The hydrogenation rate represented by the iodine value is preferably 120 or less.
[0038]
The greatest feature of the method for producing a conjugated diene polymer latex according to the present invention is that the platinum group element present in the aqueous medium and / or polymer particles of the latex after the hydrogenation reaction is converted into the platinum group element. It is in the post-treatment and recovery of the catalyst that the complex forming ability is used to deposit or precipitate and aggregate in the latex in a separable form larger than the polymer particles. That is, after hydrogenating a conjugated diene polymer in a latex state, it is essential to separate precipitates formed in the latex by adding a complexing agent that forms a water-insoluble complex with a platinum group element. And By such a complexing agent treatment, the hydrogenation catalyst can be efficiently separated.
[0039]
Prior to or simultaneously with the addition of the complexing agent, it is preferable to add an oxidant to the hydrogenated polymer-containing reaction mixture to bring the catalyst (catalyst residue) contained in the reaction mixture into contact with the oxidant. That is, the catalyst in the system after completion of the hydrogenation reaction is in a reduced state, and is oxidized by contacting it with an oxidizing agent. The hydrogenation catalyst can be separated more efficiently by the oxidation treatment.
[0040]
The oxidizing agent is not particularly limited as long as it has catalytic oxidation ability, and examples thereof include air (oxygen); peroxides such as hydrogen peroxide, peracetic acid and perbenzoic acid; and preferably air, Hydrogen peroxide, more preferably hydrogen peroxide.
The usage-amount of these oxidizing agents is not specifically limited, It is 1-100 times mole with respect to the platinum group element contained in the catalyst used for the hydrogenation reaction, Preferably it is 3-50 times mole. Contact temperature is 0-100 degreeC normally, Preferably it is 50-95 degreeC, More preferably, it is 70-90 degreeC. The contact time is usually 10 minutes to 20 hours, preferably 30 minutes to 10 hours.
[0041]
The method for contacting the catalyst and the oxidizing agent is not uniform depending on the type of the oxidizing agent. For example, when air is used as the oxidizing agent, air is continuously blown into the reaction mixture in an open state; open or sealed And a method of stirring the reaction mixture by setting the gas portion atmosphere of the reaction mixture container in the state to air. When hydrogen peroxide is used, it may be added to the reaction mixture and stirred.
[0042]
After completion of the hydrogenation reaction, the complexing agent is added in the form of a powder or a solution, after or simultaneously with or without the above-mentioned oxidizing agent treatment. In order to form a complex by bringing a complexing agent and a platinum group element into contact with each other, to precipitate this in a latex, and to grow or agglomerate it to a particle size larger than that of the polymer particles, stirring in a heated state followed by static It is preferable to take the steps of placing and cooling. Moreover, it is preferable to adjust latex pH at the time of complex formation to about 8-10.5.
[0043]
The complexing agent is not particularly limited as long as it forms a water-insoluble complex with the platinum group element, but a complexing agent having strong self-aggregation property is preferable. Specific examples include oxime compounds. Dioxime compounds are preferred because of their strong complexing ability, and α, β-alkanedione dioximes such as dimethylglyoxime and cyclohexanedione dioxime are more preferred. Of these, dimethylglyoxime is most preferred. The amount of the complexing agent used is usually 1 to 50 times mol, preferably 2 to 30 times mol for the platinum group element of the catalyst used.
[0044]
By adding a complexing agent, the precipitate deposited in the latex and having a particle size larger than the polymer particles is removed from the latex and recovered by a known simple separation operation such as filtration or centrifugation. . For example, when filtering the precipitate, the filtration device and the filtration method are not limited except that a filter medium that passes only the latex but does not pass the precipitate is used. Both vacuum filtration and pressure filtration can be employed. The catalyst recovered as a precipitate in this way can be used for the hydrogenation reaction after regenerating as necessary.
[0045]
If desired, the reaction mixture containing the complexed product can be contacted with an adsorbent after completion of the complexing treatment in order to further increase the separation efficiency. Examples of the adsorbent include activated carbon; silicon-containing inorganic compounds such as diatomaceous earth, talc, clay, activated clay, and silica; activated alumina; synthetic zeolite such as radiolite; and ion exchange resin. Activated carbon and silicon-containing inorganic compounds are preferred.
The adsorption treatment can be performed by a method of adding an adsorbent to the reaction mixture containing the complexed product, stirring and mixing, or a method of passing the reaction mixture through a column packed with these adsorbents.
[0046]
The adsorbent adsorbing the complexed product can be removed from the reaction mixture by a known separation operation such as filtration or centrifugation.
As the filtration device, a filtration device having a structure in which a plurality of filter elements are housed in a sealable housing is preferably used. Here, the “filter element” includes an element made only of a filter medium, or an element made of a combination of a filter medium and a filter plate, and refers to the entire member that bears the “filtration” function of the filter device. In particular, in view of the filtration area and filtration rate, the filter element is preferably a cylindrical or hollow disk, and the number is preferably 5 or more, more preferably 10 or more. Examples of the filtration device provided with such a filter element include a pressurization type filter called a Fundaback filter or a leaf filter.
[0047]
In order to efficiently filter without clogging, the filter element can be precoated with a filter aid such as diatomaceous earth. Specifically, before supplying the substance to be filtered, a suspension of filter aid is filled in the housing, and the suspension is filtered to form a precoat layer of the filter aid on the filter element.
[0048]
In the production method of the present invention, a hydrogenated conjugated diene-based polymer latex in which the platinum group element catalyst can be almost removed can be obtained as a result of employing the above-described steps of separating and recovering the platinum group element catalyst. The recovery rate of the platinum group element is at least 70% with respect to the platinum group element used in the hydrogenation reaction, and can be about 95% or more if conditions are selected. The content (residual amount) of the platinum group element in the latex is usually 300 ppm or less. Further, if the conditions are appropriately selected, the amount of catalyst can be significantly reduced, and the hydrogenated conjugated diene having a platinum group element content per polymer of 100 ppm or less, preferably 80 ppm or less, more preferably 50 ppm or less. A polymer latex can be obtained.
[0049]
In order to separate the hydrogenated polymer rubber from the hydrogenated conjugated diene polymer latex obtained by the production method of the present invention into a rubber product, an industrially commonly used method may be appropriately employed. For example, a coagulant such as aluminum sulfate, magnesium sulfate, or calcium chloride is added to the polymer latex to obtain crumb, washed with water as necessary, and then subjected to drying steps such as draining, hot air drying, vacuum drying or extrusion drying. A hydrogenated conjugated diene polymer rubber can be obtained.
The separated platinum group element-containing catalyst and complexed product thereof can be recovered and reused by dissolution, decomposition, reaction treatment or the like.
[0050]
Examples 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. Further, parts and% in these examples are based on weight unless otherwise specified.
The hydrogenation rate of the hydrogenated conjugated diene polymer was measured by proton NMR. 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. and dissolved in sulfuric acid. 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. Therefore, the amount of palladium contained in the polymer latex and the rubber was the same. It is.
[0051]
Example 1
An autoclave was charged with 2 parts of potassium oleate, 180 parts of ion exchanged water, 37 parts of acrylonitrile, and 0.5 part of t-dodecyl mercaptan. After replacing the inside of the reactor with nitrogen, 63 parts of butadiene was sealed. The reactor was cooled to 10 ° C., and 0.01 parts of cumene hydroperoxide and 0.01 parts of ferrous sulfate were added. Next, the reactor was stirred for 16 hours while maintaining the temperature at 10 ° C., and the contents were mixed well. Thereafter, 10% hydroquinone aqueous solution 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 acrylonitrile-butadiene copolymer (NBR) latex for use in the hydrogenation reaction.
[0052]
Palladium acetate (the amount used is 800 ppm in the ratio of Pd metal / NBR) and nitric acid having a 5-fold molar equivalent of palladium added to 300 ml of an acidic palladium aqueous solution, and polyvinylpyrrolidone having a weight average molecular weight of 5000 to palladium. In contrast, it was added 5 times by weight. Further, an aqueous potassium hydroxide solution was added to prepare an aqueous catalyst solution A having a pH of 9.0.
The total amount of the NBR latex 400 ml (solid content 120 g) adjusted to a total solid content concentration of 30% and the catalyst aqueous solution A was put into an autoclave equipped with a stirrer, and nitrogen gas was allowed to flow for 10 minutes to remove dissolved oxygen in the latex. After the system was replaced with hydrogen gas twice, 3 MPa 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.
[0053]
Next, the pH of the reaction mixture (latex) was adjusted to 9.5, and dimethylglyoxime corresponding to a 5-fold molar amount of palladium contained in the catalyst aqueous solution A was added as a powder. And when it heated at 80 degreeC and stirred for 5 hours, insoluble matter precipitated in latex. The total amount of the latex was suction filtered to separate the precipitate. The resulting white filtrate was concentrated under reduced pressure using a rotary evaporator to obtain solid hydrogenated NBR. The hydrogenation rate of hydrogenated NBR was 93%. The amount of palladium in hydrogenated NBR was 65 ppm. This amount of palladium corresponded to 8.1% of the palladium charged in the hydrogenation reaction, and the remaining palladium was removed from the hydrogenated NBR.
[0054]
Comparative Example 1
In the same manner as in Example 1, preparation of NBR (polymerization conversion rate: 90%), preparation of catalyst solution A, and preparation of hydrogenated NBR latex (92% hydrogenation) were sequentially performed. The pH of the hydrogenation reaction mixture was adjusted to 9.5, and the mixture was heated to 80 ° C. and stirred for 5 hours without adding the dimethylglyoxime powder used in Example 1. During this warming and stirring, there was no change in the state of the reaction mixture (latex), and no precipitate as in Example 1 was observed. When the entire amount of the latex was suction filtered, all passed through the filter paper. The filtrate had a dark gray color with a blackish tinge. The obtained filtrate was concentrated under reduced pressure using a rotary evaporator to obtain solid hydrogenated NBR. The amount of palladium in this hydrogenated NBR was 789 ppm. This amount corresponded to 98.6% of the palladium charged in the hydrogenation reaction.
[0055]
Example 2
The same operation as in Example 1 was performed except that the potassium hydroxide used in the preparation of the aqueous catalyst solution A in Example 1 was not used. The hydrogenation rate of the obtained hydrogenated NBR was 65%. The amount of palladium in the hydrogenated NBR was 68 ppm. This corresponds to 8.5% of the palladium charged in the hydrogenation reaction, and the remaining palladium was removed from the hydrogenated NBR.
As is clear from Examples 1 and 2 and Comparative Example 1, as a post-treatment method after completion of the hydrogenation reaction, when a complexing agent (dimethylglyoxime) was added to the reaction mixture for treatment, the used catalyst was made efficient. It was confirmed that they could be separated well.
[0056]
Example 3
An autoclave was charged with 2 parts of potassium oleate, 180 parts of ion exchanged water, 37 parts of acrylonitrile, and 0.5 part of t-dodecyl mercaptan. After replacing the inside of the reactor with nitrogen, 63 parts of butadiene was sealed. The reactor was cooled to 10 ° C., and 0.01 parts of cumene hydroperoxide and 0.01 parts of ferrous sulfate were added. The contents were then stirred for 16 hours while maintaining the reactor at 10 ° C. Thereafter, 10% hydroquinone aqueous solution was added into the reactor to terminate the polymerization. Unreacted monomers were removed from the polymerization reaction solution to obtain a latex. The polymerization conversion was 90%. The acrylonitrile-butadiene copolymer (NBR) latex thus obtained was subjected to a hydrogenation reaction in a latex state.
[0057]
Palladium acetate (the amount used is 700 ppm in the ratio of Pd metal / NBR) was added to water, and 5-fold molar equivalent of nitric acid was added to palladium to prepare 300 parts of an acidic aqueous palladium solution. Polyvinylpyrrolidone having a weight average molecular weight of 5000 was added to the aqueous solution 5 times by weight with respect to palladium. Further, an aqueous potassium hydroxide solution was added to prepare an aqueous catalyst solution A having a pH of 9.0.
Put 400 parts of NBR latex adjusted to 30% of total solids (120 parts of solids) and the total amount of catalyst aqueous solution A in an autoclave with a stirrer, and then flow nitrogen gas for 10 minutes to remove dissolved oxygen in the latex. did. After the system was replaced with hydrogen gas twice, 3 MPa hydrogen was pressurized. The contents were heated to 50 ° C. and stirred for 6 hours to conduct a hydrogenation reaction, thereby obtaining a latex-state hydrogenated NBR reaction mixture.
[0058]
2 parts of 30% hydrogen peroxide water was added to the latex reaction mixture and stirred (oxidation treatment) at 80 ° C. for 2 hours. Next, the pH of the reaction mixture was adjusted to 9.5, and dimethylglyoxime corresponding to a 5-fold molar amount of palladium contained in the catalyst aqueous solution A was added as a powder. When the reaction mixture was stirred at 80 ° C. for 5 hours (complexation treatment), insoluble matters were precipitated in the latex. The total amount of the latex was suction filtered to separate the precipitate. The resulting white filtrate was concentrated under reduced pressure using a rotary evaporator to obtain solid hydrogenated NBR. The hydrogenation rate of hydrogenated NBR was 93%. The amount of palladium in hydrogenated NBR was 37 ppm. This amount of palladium corresponded to 5.2% of the palladium charged in the hydrogenation reaction, and the remaining palladium was removed from the hydrogenated NBR.
[0059]
In the method of Example 3 above, in order to examine the effect based on the oxidation treatment prior to the complexation treatment of the hydrogenation reaction mixture, a comparative experiment without the oxidation treatment was performed as follows. That is, NBR preparation (polymerization conversion rate: 90%), catalyst aqueous solution A preparation, and hydrogenation reaction in a latex state (hydrogenation 92%) were sequentially performed in the same manner as described above. Without adding aqueous hydrogen oxide, the pH of the reaction mixture was adjusted to 9.5 and stirred at 80 ° C. for 7 hours. The amount of palladium in the finally obtained hydrogenated NBR was 58 ppm.
As is apparent from the results of Example 3 and the comparative experiment, it can be seen that the palladium content in the obtained hydrogenated NBR varies depending on the presence or absence of an oxidation treatment as a post-treatment method after completion of the hydrogenation reaction. It was confirmed that the catalyst used for the hydrogenation reaction can be more efficiently separated from the reaction mixture by the oxidation treatment.
[0060]
【The invention's effect】
The latex of the hydrogenated conjugated diene polymer produced by the method of the present invention has an advantage that the amount of residual platinum group element derived from the hydrogenation catalyst is remarkably reduced.
Therefore, the latex of the hydrogenated conjugated diene polymer is useful as an adhesive, a coating agent, a paint, a dip-formed glove raw material, and the like. Since the amount of residual platinum group elements in latex is extremely low, when used as an adhesive, coating agent, paint, etc., the corrosion resistance of the deposited or coated metal material is high, and darkening caused by residual platinum group elements is also present. Since there are no coating agents and paints, there is a high degree of freedom in coloring. A glove obtained by dip-molding latex is suitable for work such as a semiconductor device manufacturing process.
Further, the hydrogenated conjugated diene polymer rubber obtained from the hydrogenated conjugated diene polymer latex has a remarkably low platinum group element content, so there is no fear of darkening or coloring derived from the platinum group element, Can be used in a wide range of industrial applications utilizing various properties such as heat resistance, weather resistance, ozone resistance, heat resistance, and cold resistance.

Claims (7)

  In the latex of the conjugated diene polymer, a hydrogenation catalyst containing a platinum group element compound is dissolved or dispersed to hydrogenate the carbon-carbon unsaturated bond of the polymer, and then the latex of the hydrogenated polymer to be produced A method for producing a hydrogenated conjugated diene polymer latex, wherein a precipitate formed by adding a complexing agent that forms a water-insoluble complex with a platinum group element is separated. The conjugated diene polymer is a homopolymer or copolymer of at least one conjugated diene monomer, or a copolymer of the at least one conjugated diene monomer and another copolymerizable monomer. The production method according to claim 1 , which is a polymer. The production method according to claim 1 or 2 , wherein the conjugated diene polymer is a copolymer of a conjugated diene monomer and an α, β-unsaturated ethylene nitrile monomer. The production method according to claim 1 or 2 , wherein the conjugated diene polymer is a copolymer of 30 to 95% by weight of 1,3-butadiene and 5 to 70% by weight of acrylonitrile. The production method according to any one of claims 1 to 4 , wherein the platinum group element is palladium. The production method according to any one of claims 1 to 5 , wherein the hydrogenation is performed under basic conditions. The production method according to any one of claims 1 to 6 , wherein the complexing agent is an oxime compound.