JP5452895B2 - Cleaning method for filter media - Google Patents

Description

  The present invention relates to a method for cleaning a filter medium for promoting efficient reuse of the filter medium after a filtering operation for removing impurities from a polymer slurry. More specifically, the present invention relates to a method for washing a filter medium by flowing a solvent in the same direction as filtration after a filtration operation for removing impurities from a polymer slurry.

  A living polymerization method is generally known as a precise method for polymer synthesis. Living polymerization is not only capable of controlling the molecular weight and molecular weight distribution, but is also an effective method for obtaining a polymer with a clear terminal structure. Recently, also in radical polymerization, a polymerization system capable of living polymerization has been found, and research on living radical polymerization has been actively conducted. In particular, a polymer having a narrow molecular weight distribution can be obtained by utilizing atom transfer radical polymerization. As an example of atom transfer radical polymerization, a polymerization system using an organic halide or sulfonyl halide compound as an initiator, and a metal complex having a group 8 element, group 9, group 10, or group 11 element as a central metal in the periodic table as a catalyst (See, for example, Matyjaszewski et al., J. Am. Chem. Soc. 1995, 117, 5614, Macromolecules 1995, 28, 7901, Science 1996, 272, 866, or Sawamoto et al., Macromolecules 1995, 28, 21).

  Since the transition metal complex which is a polymerization catalyst remains in the vinyl polymer produced by atom transfer radical polymerization, problems such as coloring of the polymer, influence on physical properties and environmental safety arise. For example, a vinyl polymer having an alkenyl group at the terminal produced by using an atom transfer radical polymerization method is converted to a crosslinkable silyl group terminal polymer and may be very useful industrially. The residual polymerization catalyst in radical polymerization acts as a catalyst poison for the hydrosilylation reaction, so that the hydrosilylation reaction is hindered, and in order to proceed with the hydrosilylation reaction, it is necessary to use a large amount of an expensive transition metal catalyst. occured.

  As means for solving these problems, it has been reported that a vinyl polymer obtained by atom transfer radical polymerization is brought into contact with an adsorbent for purification (Patent Document 1). However, in order to remove the catalyst poison of the hydrosilylation reaction, it is necessary to remove the adsorbent used here and the remaining transition metal complex from the polymer solution to a very low residual amount.

  As a method for removing these adsorbents and transition metal complexes, a centrifugal separator having a high centrifugal force is used. However, when the fine inorganic powder is removed from the polymer solution having a high viscosity, the separation may be insufficient depending on the particle diameter, and as a result, the required hydrosilylation activity may not be obtained. Another problem is that a large amount of light liquid is lost when the separated solid is discharged.

  There is also a description that the adsorbent used when purifying a polymer obtained by living radical polymerization is removed by filtration (for example, Patent Document 2 or 3). However, when a large amount of industrially filtered polymerization catalyst or adsorbent used for purification is industrially filtered, filter media such as filter cloth and wire mesh are clogged, resulting in a problem that the filtration speed is reduced. It became clear while I was there. For this reason, the productivity is lowered and the cost is increased due to an increase in the time cycle due to the slow filtration rate.

In order to control the clogging of the filter hole, a method of removing clogged particles by backwashing the filter medium in a filter having a special mechanism (for example, Patent Document 4) has also been proposed.
JP-A-11-193307 JP 2001-323012 A Japanese Patent Application No. 2002-320845 JP 2005-280354 A

  If the filter medium is frequently exchanged for controlling the clogging of the filter medium, it takes time and cost. If the filtration area is increased and the amount of filtrate per unit area is reduced, the apparatus becomes larger and clogging is alleviated, but it is not fundamentally solved.

  The backwashing of the filter medium requires a special mechanism and cannot be used for general filters.

  Then, an object of this invention is to provide the technique which can use a filter medium continuously, without replacing | exchanging a filter medium and a special mechanism.

  As a result of intensive studies to solve the above problems, the present inventors have found the following filter medium cleaning method and have completed the present invention.

That is, the present invention is a filter medium cleaning method for filtering and purifying a vinyl polymer produced by atom transfer radical polymerization, and is 0.3 MPa or more in an amount of 80 kg / m ² or more per unit area of the filter medium. The present invention relates to a cleaning method, characterized by flowing a solvent under the pressurized condition.

  In the cleaning method, the solvent may be an ester solvent.

  In the cleaning method, the solvent may be butyl acetate.

  In the cleaning method, the solvent may be the same as the diluent used for the filtration operation of the vinyl polymer.

  In the cleaning method, the vinyl polymer may be a (meth) acrylic polymer.

  In the above washing method, the solid content removed by the filtration purification and removed by the washing method is a polymerization catalyst, aluminum silicate, activated alumina-based adsorbent, magnesium oxide-based adsorbent, aluminum oxide-based adsorbent, aluminum oxide- Magnesium oxide adsorbent, synthetic hydrotalcite, activated clay, activated carbon, zeolite, diatomaceous earth filter aid, pearlite filter aid, sand, anthracite, cellulose, carbonaceous filter aid, acid clay, and bentonite It may be one selected from the group consisting of or a combination thereof.

  By using the method for cleaning a filter medium of the present invention, in the filtration step for purification of the polymer, it is possible to save the trouble of exchanging the filter medium, and without using the production line, the filter medium can be used continuously. It is particularly useful for mass production facilities.

  The cleaning method of the present invention is used for reusing the filter medium after filtering and purifying a vinyl polymer produced by atom transfer radical polymerization. Here, atom transfer radical polymerization is a polymerization method using a transition metal complex as a polymerization catalyst.

  More specifically, atom transfer radical polymerization of a vinyl monomer using a transition metal complex as a polymerization catalyst is one of living radical polymerization, and an organic halide or a sulfonyl halide compound is used as an initiator and transition metal is mainly used. This is a method of radical polymerization of a vinyl monomer using a metal complex of a metal as a catalyst. Specifically, for example, Matyjaszewski et al., Journal of the American Chemical Society (J. Am. Chem. Soc.) 1995, 117, 5614, Macromolecules ( Macromolecules) 1995, 28, 7901, Science 1996, 272, 866, WO 96/30421 pamphlet, WO 97/18247 pamphlet, WO 98/01480 pamphlet, WO 98/40415 pamphlet, Sawamoto ( Sawamoto et al., Macromolecules 1995, 28, 1721, JP-A-9-208616, JP-A-8-41117, and the like. .

  Examples of the organic halide used as the initiator include organic halides having a particularly highly reactive carbon-halogen bond, such as a carbonyl compound having a halogen atom at the α-position and a compound having a halogen atom at the benzyl-position. It is done.

By performing atom transfer radical polymerization of a vinyl monomer using an organic halide or a sulfonyl halide compound as an initiator, the general formula (1):
-CX (R ₁ ) (R ₂ ) (1)
(Wherein R ₁ and R ₂ are groups bonded to the ethylenically unsaturated group of the vinyl monomer, and X is a chlorine atom, bromine atom or iodine atom), a vinyl polymer having a terminal structure is obtained.

  Examples of the transition metal complex used as the polymerization catalyst include elements of Group 7, Group 8, Group 9, Group 10 or Group 11, preferably Group 8, Group 9, Group 10 of the periodic table. Alternatively, a transition metal complex having a group 11 element as a central metal is used.

  Examples of the central metal of the transition metal complex include iron, nickel, ruthenium, and copper. Among these, for example, zero-valent copper, monovalent copper, divalent ruthenium, divalent iron, and divalent nickel are preferable, and among them, vinyl polymers having good zero-valent or monovalent copper are preferable. It is preferable from the point obtained.

  Specific examples of the monovalent copper compound among the metal compounds constituting the transition metal complex (the compound before ligand coordination) include, for example, cuprous chloride, cuprous bromide, and iodide iodide. Examples include cuprous, cuprous cyanide, cuprous oxide, and cuprous perchlorate.

  Examples of the ligand that forms the transition metal complex include polyamine compounds, triamine compounds, pyridine, and bipyridine. Of these, polyamine compounds and triamine compounds are preferred.

  In the case of using a copper compound, for example, 2,2′-bipyridyl, its derivative, 1,10-phenanthroline, its derivative, tetramethylethylenediamine, pentamethyldiethylenetriamine, hexamethyltris (2 -Polyamines such as aminoethyl) amine are added.

A tristriphenylphosphine complex of divalent ruthenium chloride (RuCl ₂ (PPh ₃ ) ₃ ) is also suitable as a catalyst. When a ruthenium compound is used as a catalyst, it is preferable to add an aluminum alkoxide as an activator.

Further, a divalent iron bistriphenylphosphine complex (FeCl ₂ (PPh ₃ ) ₂ ), a divalent nickel bistriphenylphosphine complex (NiCl ₂ (PPh ₃ ) ₂ ), a divalent nickel bistributylphosphine complex ( NiBr ₂ (PBu ₃ ) ₂ ) is also suitable as a catalyst.

  The vinyl monomer used for the production of the vinyl polymer is not particularly limited, and specific examples thereof include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) Acrylic acid-n-propyl, (meth) acrylic acid isopropyl, (meth) acrylic acid-n-butyl, (meth) acrylic acid isobutyl, (meth) acrylic acid-tert-butyl, (meth) acrylic acid-n-pentyl , (Meth) acrylic acid-n-hexyl, (meth) acrylic acid-n-heptyl, (meth) acrylic acid-n-octyl, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid nonyl, (meth ) (Meth) acrylic acid alkyl esters such as decyl acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate ( Alkyl group having 1 to 50 carbon atoms), (meth) acrylic acid cyclic alkyl ester such as cyclohexyl (meth) acrylic acid (cyclic alkyl group having 5 to 50 carbon atoms), phenyl (meth) acrylate, (meth) acrylic acid (Meth) acrylic acid aryl esters such as toluyl (aryl group having 6 to 50 carbon atoms), (meth) acrylic acid aralkyl esters such as benzyl (meth) acrylate (7 to 50 carbon atoms in aralkyl group), (meth) (Meth) acrylic acid alkoxyalkyl esters such as 2-methoxyethyl acrylate and (meth) acrylic acid-3-methoxybutyl (alkoxy group having 1 to 50 carbon atoms, alkyl group having 1 to 50 carbon atoms), (meta ) (Meth) acrylic, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate Hydroxyalkyl ester (hydroxyalkyl group having 1 to 50 carbon atoms), (meth) acrylic acid epoxy group-containing alkyl ester such as glycidyl (meth) acrylate (alkyl group having 1 to 50 carbon atoms), (meth) acrylic acid 2 -(Meth) acrylic acid aminoalkyl ester (aminoalkyl group having 1 to 50 carbon atoms) such as aminoethyl, (meth) acrylic acid alkoxysilyl group-containing alkyl ester (alkoxy) such as γ- (methacryloyloxypropyl) trimethoxysilane Group having 1 to 50 carbon atoms, alkyl group having 1 to 50 carbon atoms), (meth) acrylic acid ethylene oxide adduct (ethylene oxide addition number 2 to 50), (meth) acrylic acid trifluoromethylmethyl, ) 2-trifluoromethylethyl acrylate, (meth) acrylic 2-perfluoroethylethyl phosphate, 2-perfluoroethyl-2-perfluorobutylethyl (meth) acrylate, 2-perfluoroethyl (meth) acrylate, perfluoromethyl (meth) acrylate, (meth) Diperfluoromethylmethyl acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate, (Meth) acrylic acid-based monomers such as (meth) acrylic acid fluorine-containing alkyl esters (carbon number of fluorine-containing alkyl group 1 to 50) such as (meth) acrylic acid 2-perfluorohexadecylethyl; styrene, vinyltoluene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, its salts Styrene-based monomers; fluorine-containing vinyl monomers such as perfluoroethylene, perfluoropropylene, and vinylidene fluoride; silicon-containing vinyl monomers such as vinylalkoxysilanes such as vinyltrimethoxysilane and vinyltriethoxysilane; maleic anhydride, maleic Acids, monoalkyl and dialkyl esters of maleic acid; fumaric acid, monoalkyl and dialkyl esters of fumaric acid; maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide , Phenylmaleimide, cyclohexylmaleimide and other maleimide monomers; acrylonitrile, methacrylonitrile, etc. Lyl group-containing vinyl monomers; amide group-containing vinyl monomers such as acrylamide and methacrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate; alkenes such as ethylene and propylene Conjugated dienes such as butadiene and isoprene; vinyl chloride, vinylidene chloride, allyl chloride, allyl alcohol and the like. These may be used alone or in combination of two or more. Among these, styrenic monomers and (meth) acrylic acid monomers are preferable from the viewpoint of physical properties of the product, and acrylic acid ester monomers and methacrylic acid ester monomers are more preferable, and acrylic acid ester monomers are particularly preferable. Particularly preferred are butyl acrylate, ethyl acrylate, and 2-methoxyethyl acrylate.

  In the present invention, these preferred monomers are also referred to as vinyl polymers even when they are copolymerized with other monomers and further block copolymerized. In that case, these preferable monomers are contained in a weight ratio of 40% or more.

  In the above expression format, for example, (meth) acrylic acid represents acrylic acid and / or methacrylic acid.

The polymerization reaction from the vinyl monomer to the vinyl polymer can be performed without a solvent, but can also be performed in various solvents. The polymerization can also be carried out in an emulsion system or a system using supercritical fluid CO ₂ as a medium.

  A polymerization solvent, a polymerization initiator, and a transition metal complex as a polymerization catalyst are charged into a polymerization vessel, and a vinyl polymer is produced by, for example, dropping a vinyl monomer in the presence of these.

  The vinyl polymer of the present invention is not limited, but may be a polymer containing a halogen or an alkenyl group, or a modified terminal or side chain such as hydrosilylated. Therefore, the vinyl polymer to be subjected to purification can be any polymer before or after modification such as halogenation, alkenyl group introduction, hydrosilylation and the like.

  Such a vinyl polymer is filtered for the purpose of removing a polymerization catalyst such as solid copper present in the reaction mixture of atom transfer radical polymerization. Alternatively, for the purpose of removing such a polymerization catalyst, it is first subjected to an adsorption treatment and then filtered. Alternatively, filtration is performed after appropriate operations such as heating and centrifugation.

  As one of the pretreatment methods for the solid copper removal treatment, which is one of the purification treatments, a vinyl polymer containing a transition metal complex is mixed with a solvent having specific characteristics to dissolve the vinyl polymer and remain. Examples include purification methods that insolubilize and enlarge transition metal complexes. In particular, since the low dielectric constant solvent is a poor solvent for the transition metal complex, the transition metal complex is easily insolubilized by the addition of the low dielectric constant solvent, and is enlarged by collision of the insolubilized transition metals. Insoluble and enlarged transition metal complexes and transition metals can be removed by filtration or the like.

  Alternatively, by treating a vinyl polymer produced by atom transfer radical polymerization of a vinyl monomer using a transition metal complex as a polymerization catalyst at a high temperature to promote enlargement and insolubilization of the transition metal complex, by filtration or the like Can be removed.

  There is no restriction | limiting in particular as an apparatus which dissolves a polymer in a solvent, For example, a general purpose stirring tank can be used in a batch type, and a line mixer etc. can be used in a continuous type.

  Moreover, when adding an adsorbent before filtration, for example, an adsorbent such as a synthetic resin adsorbent such as activated carbon or an ion exchange resin, or an inorganic adsorbent such as zeolite can be used. Any of these can be preferably used.

  As the activated carbon, conventionally known various types can be used.

  Examples of the synthetic resin-based adsorbent include ion exchange resins and chelate ion exchange resins. Examples of functional groups of acidic ion exchange resins include carboxylic acid groups and sulfonic acid groups. Examples of functional groups of basic ion exchange resins include amino groups. Examples of functional groups of chelate ion exchange resins include iminodioxy groups. Examples include acetic acid groups and polyamine groups.

  The inorganic adsorbent has a solid acid, solid base or neutral character, and the particles have a porous structure. Such inorganic adsorbents are not particularly limited, but typical examples thereof include those containing aluminum, magnesium, silicon and the like as main components alone or a combination thereof. For example, silicon dioxide; magnesium oxide; silica gel; silica / alumina, aluminum silicate; magnesium silicate; activated alumina; clay-based adsorbent such as acid clay and activated clay; zeolite generically named hydrous aluminosilicate mineral group such as sodium aluminum silicate Examples thereof include an aluminum-based adsorbent; an aluminum oxide-based adsorbent; an aluminum oxide-magnesium oxide-based adsorbent; a dawsonite compound; and a hydrotalcite compound. There are natural and synthetic zeolites, both of which can be used.

  As silicon dioxide, crystalline, amorphous, amorphous, glassy, synthetic, natural products, etc. are known, but any powder can be used here.

  Specific examples of silicon dioxide include silicic acid made from clay minerals obtained by acid treatment of activated clay, Carplex BS304, Carplex BS304F, Carplex # 67, Carplex # 80 (all of which are Shionogi) Examples include, but are not limited to, synthetic silicic acid.

  Moreover, as a specific example of aluminum silicate, a part of silicon of silicic acid is replaced with aluminum, and pumice, fly ash, kaolin, bentonite, activated clay, diatomaceous earth and the like are known. Among these, synthetic aluminum silicate has a large specific surface area and high adsorption capacity. Examples of the synthetic aluminum silicate include, but are not limited to, the KYOWARD 700 series (manufactured by Kyowa Chemical Co., Ltd.).

As the synthetic hydrotalcite, hydrotalcite compounds include divalent metals (Mg ²⁺ , Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ etc.) and trivalent metals (Al ³⁺ , Fe ^3+). , Cr ³⁺ , Co ³⁺ , In ³⁺ etc.) or a part of the hydroxyl group of the hydroxide is a halogen ion, NO ₃ ⁻ , CO ₃ ²⁻ , SO ₄ ²⁻ , Fe (CN) ₆ ^{3 -,} _CH 3 CO ₂ ^-, oxalic acid ion, is obtained by exchanging the anions such as salicylate. Of these, hydrotalcite in which the divalent metal is Mg ²⁺ , the trivalent metal is Al ³⁺ and a part of the hydroxyl group is replaced with CO ₃ ²⁻ is preferable. Examples include, but are not limited to, the KYOWARD 1000 series (all manufactured by Kyowa Chemical Co., Ltd.). An adsorbent obtained by firing the hydrotalcite is also preferably used. Of these, MgO—AlO ₃ based solid solutions obtained by firing hydrotalcites in which the divalent metal is Mg ²⁺ and the trivalent metal is Al ³⁺ are preferable. For example, Kyoward 2000 (manufactured by Kyowa Chemical Co., Ltd.) ), But is not limited thereto. In the present invention, the fired products of hydrotalcites are also classified as hydrotalcites.

  In addition to these, pearlite filter aid, sand, anthracite, cellulose, carbonaceous filter aid, and acid clay are also used as the adsorbent.

  An adsorbent may be used independently and may be used in combination of 2 or more type.

  After the polymer or polymer solution is brought into contact with the adsorbent, filtration can be performed alone or in combination with other methods such as centrifugation and sedimentation. At this time, it is possible to dilute if necessary and to filter the target polymer solution.

  In the present invention, the filtration method in which the filter medium to be cleaned is used is not particularly limited, and any method using equipment such as a filter press, a drum filter, a pressure nutsche, and a pressure leaf filter is adopted. it can. In the method of the present invention, the flow direction of the cleaning liquid is the same as that of backwashing, and therefore is not restricted by the structure of the device. Therefore, the present invention can be applied to all filters, and is particularly effective for a filter having a structure having no backwashing mechanism.

  Filter media such as filter paper, filter cloth, wire mesh, and sintered plate can be used as the filter media, but non-standard filter media such as filter sand are not applicable. In addition, it is possible to perform the cleaning according to the present invention after removing the deposited cake after performing filtration by performing body feed or pre-coating with a filter aid. Examples of the filter cloth include heat-resistant, solvent-resistant, and durable synthetic resin fibers such as polypropylene and polyethylene, cotton, and aramid, and these can be preferably used as the filter medium in the cleaning method of the present invention. The material of the wire mesh and the sintered plate is not particularly limited, and those having a mesh of 100 to 400 mesh are preferably used. Diatomaceous earth, perlite, etc. are used suitably for the filter aid used in order to improve filterability. From the viewpoint of achieving both particle capturing properties and filtration speed, the filter aid is preferably one having an average particle size of 5 to 100 μm, more preferably 20 to 50 μm. When the average particle size is less than 5 μm, the filtration rate decreases because the resistance of the filter cake is large. When the average particle size exceeds 100 μm, a solid component with a small particle size forms a cake layer with high resistance in the gap between the filter aids. There is a tendency that the effect of increasing the value cannot be obtained.

  After the polymer slurry is filtered, the filtered solid deposited on the filter medium is discharged and subjected to washing with a solvent. The washing can be performed by removing the filter medium from the filter, but it is preferable to perform washing with a solvent while the filter medium is attached to the filter. In particular, for example, with a vibrating horizontal plate type pressure filter, after the polymer slurry having a concentration of 0.5 to 5% by weight is treated for 0.1 to 2 tons, the filter medium is washed while the filter medium is attached to the filter. But is not limited.

  The solvent for washing is not limited, but water is not preferable because it does not dissolve the polymer, and thus causes precipitation of the polymer in the filter medium and may further cause clogging. The solvent for washing is preferably a solvent that dissolves the vinyl polymer to be filtered. More preferred is the same solvent as the solvent in which the polymer is diluted by the purification treatment. By using a solvent that dissolves the polymer during washing, the polymer remaining in the filter medium can be dissolved and washed. Furthermore, by using the same dilution solvent as that used during the purification process, there is no need to worry about product contamination. Such solvents include, but are not limited to, ester solvents such as butyl acetate.

During washing, the pressure is increased to 0.3 MPa or more, and a total amount of 80 kg or more of solvent per 1 m ^{2 of} the filter medium is used. At this time, there is no upper limit to the pressure, and the pressure resistance of the filter is possible. The “pressure” here refers to the pressure applied to the filtration surface and is the same as the differential pressure between the supply liquid and the liquid after filtration. Usually, in a pressurizable filter, the pressure is a value displayed by a pressure gauge installed at a fluid inlet, and the outlet is a pressure under normal conditions at atmospheric pressure. The pressure in the vertical direction, such as a filter press, is also referred to herein, and refers to the differential pressure between the supply liquid and the liquid after filtration. Further, although there is no upper limit for the amount of the solvent, it is appropriate that the amount is 200 kg or less, preferably 100 kg, per 1 m ^{2 of} the filter medium.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all washing | cleaning in an Example is order washing.

（ここで、Ｐは圧力〔Ｐａ〕、ｖは濾過速度〔ｍ^３／ｍ^２ｓ〕、Ｒは、濾過抵抗〔ｍ^−１〕、Ｒｃは、ケーク抵抗〔ｍ^−１〕、Ｒｍは、濾材抵抗〔ｍ^−１〕）のように、粘度μと濾過抵抗Ｒの積の逆数と比例関係にある。さらに濾過抵抗Ｒはケーク抵抗Ｒｃと濾材抵抗Ｒｍに分けられる。 (Evaluation method)
A method for numerically evaluating the clogging of the filter medium will be described. The relationship between the filtration speed v and the filtration pressure P is

(Where P is the pressure [Pa], v is the filtration rate [m ³ / m ² s], R is the filtration resistance [m ⁻¹ ], Rc is the cake resistance [m ⁻¹ ], and Rm is the filter medium. Resistance [m ⁻¹ ]), which is proportional to the inverse of the product of viscosity μ and filtration resistance R. Further, the filtration resistance R is divided into a cake resistance Rc and a filter medium resistance Rm.

  As shown in FIG. 1, when time is taken on the horizontal axis and P / μv is taken on the vertical axis, the cake resistance Rc increases with time, so that Rc = 0 when time = 0. Therefore, the intercept becomes the filter medium resistance Rm. If the resistance of the filter medium is large, it can be determined that the filter medium is clogged. That is, when experimentally clogging the filter medium = filter medium resistance Rm, the filtration pressure and the filtration rate per unit filtration area may be recorded and plotted as shown in FIG. Measurement In the present invention, clogging of the filter medium is quantified based on the magnitude of the resistance value of the filter medium. Details are described in pages 803 to 806 of the “Chemical Engineering Handbook, Revised Sixth Edition”.

(Evaluation experiment method)
Set a filter medium whose filter area is to be measured in a Nutsche pressure filter with a filtration area of 28.26 cm ² , filter the slurry at a constant pressure, measure the amount of filtrate over time, and plot the graph of FIG. Becomes the filter medium resistance Rm.

(Production Example 1)
The required amount per 100 kg of polymer is as follows, but these were scaled up to produce a large amount of polymer. CuBr (0.84 kg) was charged into a reactor equipped with a stirrer and a jacket, and the inside of the reaction vessel was purged with nitrogen. Acetonitrile (8.79 kg) was added, warm water was passed through the jacket, and the mixture was stirred at 80 ° C. for 30 minutes. To this were added butyl acrylate (100 kg) and diethyl 2,5-dibromoadipate (3.51 kg), and the mixture was further stirred at 80 ° C. for 25 minutes. Triamine was added thereto to start the reaction. Triamine was appropriately added during the reaction, and 6 hours after the start of the reaction, 1,7-octadiene (21.5 kg) and triamine were added and stirring was continued for 6 hours to obtain a polymer solution.

The solvent was removed from the polymer solution at 80 ° C. under vacuum conditions. After adding 125 kg of butyl acetate to 100 kg of the polymer from which the solvent had been removed, the solid copper catalyst was removed by filtering the solution. Kyoward 500SH (manufactured by Kyowa Chemical Co., Ltd.) 0.49 kg and Kyoward 700 SEN (manufactured by Kyowa Chemical Co., Ltd.) 0.49 kg were added as adsorbents to the solution after removing the copper catalyst, and heated at 100 ° C. for 1 hour. . The adsorbent was removed from the slurry by filtration. The solvent was removed from this polymer solution at 100 ° C. under vacuum.
Kyoward 500SH (manufactured by Kyowa Chemical) 1.0 kg and Kyoward 700 SEN (manufactured by Kyowa Chemical) 0.1 kg were added to the polymer as an adsorbent, and the mixture was stirred at 190 ° C. under vacuum conditions. Next, 10 kg of butyl acetate and 1.0 kg of Kyoward 500SH (manufactured by Kyowa Chemical) and 1.0 kg of Kyoward 700 SEN (manufactured by Kyowa Chemical) were added as adsorbents, and the mixture was stirred at 180 ° C. for 9 hours. 90 kg of butyl acetate was added to obtain a polymer slurry [1].

(Production Example 2)
The required amount per 100 kg of polymer is as follows, but these were scaled up to produce a large amount of polymer. CuBr (0.93 kg) was charged into a reactor equipped with a stirrer and a jacket, and the inside of the reaction vessel was purged with nitrogen. Acetonitrile (9.54 kg) was added, warm water was passed through the jacket, and the mixture was stirred at 80 ° C. for 30 minutes. To this was added butyl acrylate (27.66 kg), ethyl acrylate (39.76 kg), methoxyethyl acrylate (32.58 kg), diethyl 2,5-dibromoadipate (1.94 kg), and further at 80 ° C. Stir for 25 minutes. Triamine was added thereto to start the reaction. Triamine was added appropriately during the reaction, and 6 hours after the start of the reaction, 1,7-octadiene (23.78 kg) and triamine were added and stirring was continued for 2 hours to obtain a polymer solution. The solvent was removed from the polymer solution at 80 ° C. under vacuum conditions. After adding 125 kg of butyl acetate to 100 kg of the polymer from which the solvent had been removed, the solid copper catalyst was removed by filtering the solution. Kyoward 500SH (manufactured by Kyowa Chemical Co., Ltd.) 1.0 kg and Kyoward 700 SEN (manufactured by Kyowa Chemical Co., Ltd.) 1.0 kg as adsorbents were added to the solution after removing the copper catalyst, and heated at 100 ° C. for 1 hour. . The adsorbent was removed from the slurry by filtration. The solvent was removed from this polymer solution at 100 ° C. under vacuum.

  Kyoward 500SH (manufactured by Kyowa Chemical) 1.0 kg and Kyoward 700 SEN (manufactured by Kyowa Chemical) 0.1 kg were added to the polymer as adsorbents, and the mixture was stirred at 180 ° C. under vacuum conditions. Next, 10 kg of butyl acetate and 1.0 kg of Kyoward 500SH (manufactured by Kyowa Chemical Co., Ltd.) and 0.1 kg of Kyoward 700SEN (manufactured by Kyowa Chemical Co., Ltd.) were added as adsorbents and stirred at 180 ° C. for 6 hours. 90 kg of butyl acetate was added to obtain a polymer slurry [2].

(Production Example 3)
The required amount per 100 kg of polymer is as follows, but these were scaled up to produce a large amount of polymer. CuBr (0.84 kg) was charged into a reactor equipped with a stirrer and a jacket, and the inside of the reaction vessel was purged with nitrogen. Acetonitrile (8.79 kg) was added, warm water was passed through the jacket, and the mixture was stirred at 80 ° C. for 30 minutes. To this were added butyl acrylate (100 kg) and diethyl 2,5-dibromoadipate (1.76 kg), and the mixture was further stirred at 80 ° C. for 25 minutes. Triamine was added thereto to start the reaction. Triamine was appropriately added during the reaction, and 6 hours after the start of the reaction, 1,7-octadiene (21.5 kg) and triamine were added and stirring was continued for 6 hours to obtain a polymer solution.

  The solvent was removed from the polymer solution at 80 ° C. under vacuum conditions. After 100 kg of butyl acetate was added to 100 kg of the polymer from which the solvent had been removed, the solid copper catalyst was removed by filtering the solution. Kyoward 500SH (manufactured by Kyowa Chemical Co., Ltd.) 0.5 kg and Kyoward 700 SEN (manufactured by Kyowa Chemical Co., Ltd.) 0.5 kg were added as adsorbents to the solution after removing the copper catalyst, and heated at 100 ° C. for 1 hour. . The adsorbent was removed from the slurry by filtration. The solvent was removed from this polymer solution at 100 ° C. under vacuum.

  To this polymer, 0.5 kg of Kyoward 500SH (manufactured by Kyowa Chemical) and 0.1 kg of Kyoward 700SEN (manufactured by Kyowa Chemical) were added as adsorbents and stirred at 190 ° C. under vacuum conditions. Next, 10 kg of butyl acetate and 1.0 kg of KYOWARD 500SH (manufactured by Kyowa Chemical Co., Ltd.) and 0.1 kg of KYOWARD 700 SEN (manufactured by Kyowa Chemical Co., Ltd.) were added as an adsorbent, and the mixture was stirred at 180 ° C. for 6 hours. 90 kg of butyl acetate was added to obtain a polymer slurry [3].

Example 1
The polymer slurries [1], [2], and [3] were treated with a vibration horizontal plate type pressure filter (manufactured by Towa Giken Co., Ltd., 3-stage leaf filter filtration area 1 m ² , metal mesh 350 mesh) for 25 t. The deposited cake was discharged, the wire mesh after filtration was removed, and the filter media resistance was measured with a Nutsche type pressure filter. The wire mesh was completely blocked, and the filter media resistance was ∞ (unmeasurable). That is, it was clogged.

The wire mesh was removed, set in a Nutsche type pressure filter, charged with 80 kg / m ² of butyl acetate and pressurized to 0.3 MPa to wash the wire mesh. The washing time was 2 to 3 seconds. Then, when filter medium resistance was measured by polymer slurry [1], it was 10Gm < ^-1 > and clogging was eliminated.

(Comparative Example 1)
The closed wire mesh of (Example 1) was set in a Nutsche pressure filter, charged with 80 kg / m ² of butyl acetate and pressurized to 0.1 MPa, but remained blocked and clogging was eliminated. There wasn't.

(Comparative Example 2)
The closed wire mesh of (Example 1) was set in a Nutsche type pressure filter, charged with 80 kg / m ² of butyl acetate and pressurized to 0.2 MPa, but remained blocked and clogging was eliminated. There wasn't.

(Comparative Example 3)
In order to see the clogging recovery index of the evaluation object of the example, a new 350 mesh wire mesh was set in a Nutsche type pressure filter, and the filter medium resistance was measured with the polymer slurry [1]. The value obtained by the measurement is 1.4 Gm ⁻¹ . With this value, clogging does not occur even when a small amount of filtration is performed.

(Example 2)
When the filter medium resistance after 4t filtration of the polymer slurry [3] with a vibrating horizontal plate type pressure filter (Towa Giken 3-stage leaf filter filtration area 1 m ² , wire mesh 350 mesh) is 13.5 Gm ⁻¹ . Yes, it was clogged.

Thereafter, 80 kg / m ² of butyl acetate was charged into a vibrating horizontal plate type pressure filter and pressurized to 0.3 MPa to wash the wire mesh. The washing time was 2 to 3 seconds. Thereafter, the polymer slurry [2] was filtered, and the resistance of the filter medium was measured to be 1.2 Gm ⁻¹ .

(Comparative Example 4)
In order to see the clogging recovery index to be evaluated in the examples, the polymer slurry [2] was filtered through a new polyester nonwoven fabric having a mesh size of 100 μm, and the resistance of the filter medium was measured. The measured value is 0.14 Gm ⁻¹ , and clogging does not occur even if a small amount of filtration is performed.

(Example 3)
The polymer slurry [2] was filtered with a new polyester nonwoven fabric with a mesh size of 100 μm for 2 tons per ¹ m2, a part was cut out and the resistance of the filter medium was measured to be 2.67 Gm− ¹ , resulting in clogging.

A portion of this polyester nonwoven fabric was cut out, set in a Nutsche type pressure filter, charged with 80 kg / m ² of butyl acetate, and then pressurized to 0.3 MPa to wash the nonwoven fabric. The washing time was 2 to 3 seconds. Thereafter, when the filter medium resistance was measured with the polymer slurry [2], it was 0.51 Gm ⁻¹ and the clogging was eliminated.

Filtration is a graph showing the relationship between the excess-resistance R and time.

Claims (6)

A method of washing a filter medium for filtering and purifying a vinyl polymer produced by atom transfer radical polymerization, wherein the amount is 80 kg / m ² or more per unit area of the filter medium under a pressure of 0.3 MPa or more. A cleaning method characterized by flowing a solvent in the same direction as filtration .   2. The cleaning method according to claim 1, wherein the solvent is an ester solvent.   The cleaning method according to claim 2, wherein the solvent is butyl acetate.   The cleaning method according to any one of claims 1 to 3, wherein the solvent is the same as the diluent used during the filtration operation of the vinyl polymer.   The cleaning method according to claim 1, wherein the vinyl polymer is a (meth) acrylic polymer.   The solids removed by filtration purification and removed by the washing method are polymerized catalyst, aluminum silicate, activated alumina-based adsorbent, magnesium oxide-based adsorbent, aluminum oxide-based adsorbent, aluminum oxide-magnesium oxide-based adsorbent, Selected from the group consisting of synthetic hydrotalcite, activated clay, activated carbon, zeolite, diatomaceous earth filter aid, pearlite filter aid, sand, anthracite, cellulose, carbonaceous filter aid, acid clay, and bentonite. The cleaning method according to claim 1, wherein the cleaning method is one or a combination thereof.

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