JP2010235818A - Method for producing vinylpyrrolidone-based polymer solution and method for producing vinylpyrrolidone-based polymer powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyvinylpyrrolidone-based polymer with a lower amount of insoluble matter. <P>SOLUTION: The method for producing a vinylpyrrolidone-based polymer solution comprises polymerizing, in a solvent, a monomer containing N-vinyl-2-pyrrolidone having passed through a filter with 50 μm or less opening diameter. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a vinylpyrrolidone polymer solution and a vinylpyrrolidone polymer powder, and a polymer solution and a polymer powder obtained by these production methods.

  Polyvinylpyrrolidone is a safe functional polymer, in the form of powder or aqueous solution, used for cosmetics, medical and agrochemical intermediates, food additives, photosensitive electronic materials, tackifiers, and various special industrial applications. Widely used. Among these, polyvinylpyrrolidone powder is widely used as a viscosity modifier for a raw material liquid in producing a hollow fiber membrane or as a micropore forming agent for a hollow fiber membrane. For example, in Patent Documents 1 to 4, a raw material liquid containing polysulfone or polyethersulfone as a film-forming polymer and polyvinylpyrrolidone as a hydrophilic polymer is extruded from a spinneret, and water is the main component. A method for producing a hollow fiber membrane by immersing and coagulating in a coagulation bath and then winding is disclosed.

  However, the conventional polyvinyl pyrrolidone powder contains a large amount of insoluble matter such as gelled products and impurities. When the polyvinyl pyrrolidone powder contains a large amount of insoluble matter, for example, defective products are produced during the production of the hollow fiber membrane, or the filtration performance of the obtained hollow fiber membrane is lowered. At present, in order to avoid this, when producing a hollow fiber membrane, the raw material liquid is filtered to remove insoluble matters. For example, Patent Document 1 teaches that the raw material liquid is filtered to completely remove undissolved particles before extrusion from the spinneret (see paragraph [0027] in particular). However, in such a method, when the content of insoluble matter is large, there is a problem that the frequency of replacement of the filter becomes high and the productivity is greatly reduced. Further, when the K value of the polyvinylpyrrolidone powder is high, there is a problem that the viscosity of the raw material liquid becomes high and it is difficult to filter.

  Under the circumstances described above, the present inventors have heretofore performed a predetermined operation in producing a polyvinylpyrrolidone powder composition by polymerizing N-vinyl-2-pyrrolidone. , (1) before, during and / or after polymerization, by adjusting the pH of the polymerization solution using a secondary amine, (2) performing filtration after completion of the polymerization, By drying by a technique such as freeze-drying or reduced-pressure drying, (3) by dropping polymerization using a polymerization initiator that can be used at low temperature, the internal temperature is kept at 50 ° C. or lower. And / or (4) by adding an antioxidant to the polymerization solution before, during and / or after the polymerization, to reduce the insoluble matter content, and / or Or Thermal stability discloses high polyvinylpyrrolidone powder composition (Patent Document 5).

JP-A-10-121324 JP 2002-239348 A JP 2003-245524 A JP 2006-239576 A JP 2008-202035 A

  And this time, the present inventors raised as an object to provide a polyvinylpyrrolidone powder composition (polyvinylpyrrolidone-based polymer) having a much lower insoluble content than the above-mentioned polyvinylpyrrolidone powder composition. .

  As a result of intensive studies, the present inventors filtered N-vinyl-2-pyrrolidone that is a raw material for producing a polyvinylpyrrolidone-based polymer, and gelated products, solid impurities, etc. in N-vinyl-2-pyrrolidone If the insoluble matter is removed in advance, the amount of insoluble matter in the polymer solution or polymer powder obtained using the insoluble matter is significantly higher than expected from the amount of insoluble matter removed in N-vinyl-2-pyrrolidone. As a result, the present invention has been completed. Specifically, the amount of insoluble matter in the polymer solution or polymer powder is not reduced by the amount of insoluble matter removed in N-vinyl-2-pyrrolidone, but insoluble in N-vinyl-2-pyrrolidone. The amount of insoluble matter in the polymer solution and the polymer powder can be reduced greatly exceeding the amount of product removal. Therefore, in order to obtain a polymer solution and polymer powder with a small amount of insoluble matter, N-vinyl-2 -It has been found that it is very effective to remove insoluble matters in pyrrolidone in advance.

  That is, the method for producing a vinylpyrrolidone polymer solution of the present invention is characterized by polymerizing a monomer containing N-vinyl-2-pyrrolidone through a filter having a pore size of 50 μm or less in a solvent. Thereby, the insoluble matter in N-vinyl-2-pyrrolidone is previously removed by a filter before polymerization. As a result, as described above, the amount of insoluble matter in the polymer solution and polymer powder obtained by the present invention was remarkably reduced because of the monomer containing N-vinyl-2-pyrrolidone after the filtration treatment. This is presumed to be because the insoluble matter was prevented from being formed as a by-product due to the insoluble matter during the polymerization reaction and the subsequent drying and pulverization.

  In the present invention, it is a preferred embodiment to use water that has passed through a filter having a pore size of 50 μm or less as the solvent. As a result, insoluble matters (solid impurities, etc.) in the water are also removed in advance, so that insoluble matters are prevented from being by-produced due to the insoluble matters during the polymerization reaction and during drying / pulverization. Presumed to be.

  In the present invention, it is also a preferred embodiment that an organic acid is added to the reaction solution and / or a secondary amine is added after the polymerization.

  In the present specification, “after polymerization (after polymerization reaction)” includes a late reaction stage in which the polymerization reaction has advanced by 99%.

  The present invention also includes a method for producing a vinylpyrrolidone polymer powder, characterized in that the vinylpyrrolidone polymer solution obtained by the above production method is dried and then pulverized.

  Further, the present invention includes the vinylpyrrolidone polymer solution and vinylpyrrolidone polymer powder obtained by the above production method.

  Here, it is a preferred embodiment that the vinylpyrrolidone polymer solution of the present invention has an insoluble matter content of 9 ppm (mass basis; the same shall apply hereinafter) or less.

  Further, the vinyl pyrrolidone polymer powder of the present invention is a preferred embodiment having a K value of 50 or more and 120 or less and an insoluble matter content of 30 ppm or less.

  The insoluble matter content in the vinylpyrrolidone polymer solution and the vinylpyrrolidone polymer powder and the method for measuring the K value of the vinylpyrrolidone polymer powder will be described later.

  According to the present invention, it was possible to provide a vinylpyrrolidone polymer solution and a vinylpyrrolidone polymer powder with less insoluble matter.

(Method for producing polymer solution)
The method for producing a vinylpyrrolidone-based polymer solution of the present invention includes a monomer containing N-vinyl-2-pyrrolidone (hereinafter sometimes referred to as “purified NVP”) that has been passed through a filter having a pore size of 50 μm or less. It is characterized by polymerizing in a solvent.

  According to the production method of the present invention, as compared with the case where a polymer solution (and polymer powder) is obtained using unpurified N-vinyl-2-pyrrolidone that has not passed through a filter having a pore size of 50 μm or less, A polymer solution (and polymer powder) in which the amount of insoluble matter is significantly reduced can be obtained.

  Although the cause of this is not yet clear, the insoluble matter contained in N-vinyl-2-pyrrolidone was removed by filtering N-vinyl-2-pyrrolidone through a filter having a pore size of 50 μm or less. By using the purified NVP later in the polymerization reaction, other insoluble matter is newly added to the insoluble matter in the N-vinyl-2-pyrrolidone during the polymerization reaction (and subsequent drying and pulverization). It is presumed that it was possible to suppress the production.

  Hereinafter, the method for producing the vinylpyrrolidone polymer solution of the present invention will be described in detail.

<Filtration of N-vinyl-2-pyrrolidone>
The method of passing N-vinyl-2-pyrrolidone through a filter having a pore size of 50 μm or less (hereinafter sometimes referred to as “NVP filter”) is not particularly limited, and may be performed by a conventionally known method.

  The liquid temperature of N-vinyl-2-pyrrolidone when performing this step is not particularly limited, and may be room temperature. The upper limit is preferably 60 ° C. and more preferably 50 ° C. so that N-vinyl-2-pyrrolidone will not be altered.

  The material for the NVP filter used in this step is not particularly limited as long as it does not cause corrosion, dissolution, or alteration due to N-vinyl-2-pyrrolidone. For example, polytetrafluoroethylene (PTFE) or metal The filter made from is mentioned.

  In the present invention, a polymer solution finally obtained by filtering N-vinyl-2-pyrrolidone using an NVP filter having a pore size of 50 μm or less (and a polymer powder obtained using the polymer solution) ), The pore size is preferably 30 μm or less, more preferably 20 μm or less, further preferably 10 μm or less, and even more preferably 5 μm or less. . The lower limit of the pore diameter is not particularly limited, but a PTFE filter having a pore diameter of 1 μm is commercially available, which is preferable from the viewpoint of availability.

  In this step, two or more types of filters having different materials and pore diameters may be used in combination as the NVP filter.

<Polymer polymerization>
The method for polymerizing the monomer containing purified NVP is not particularly limited. For example, an azo compound and / or organic peroxide as a polymerization initiator in a monomer solution obtained by adding the monomer to a solvent. And a method of polymerizing by adding a product. Moreover, you may add arbitrary chain transfer agents, a pH adjuster, a buffering agent, etc. other than a polymerization initiator as needed.

≪Monomer amount in monomer solution≫
The amount of the monomer added to the solvent is, for example, preferably 5 parts by mass or more and 50 parts by mass or less, more preferably 10 parts by mass or more and 40 parts by mass or less, and further preferably 15 parts by mass with respect to 100 parts by mass of the solvent. Part to 30 parts by weight.

≪Solvent≫
In this step, an aqueous medium is usually used as a solvent. Here, the “aqueous medium” means water or a mixed solvent of water and a lower alcohol. Examples of the lower alcohol include methyl alcohol, ethyl alcohol, isopropyl alcohol, diethylene glycol and the like.

≪Water filtration≫
In the present invention, when naturally occurring water (for example, distilled water or ion exchange water) is used as a solvent, such water is also passed through a filter having a pore size of 50 μm or less (hereinafter sometimes referred to as “water filter”). It is preferable to keep it. Naturally derived water contains various impurities (insoluble matter), and the insoluble matter contained in the water is removed by passing through a water filter. Then, by using the water after filtration (hereinafter sometimes referred to as “purified water”) as a solvent for the polymerization reaction, a polymer solution and a polymer powder in which the amount of insoluble matter is remarkably reduced are obtained. Can do. The details of this cause are not clear, but during the polymerization reaction (and subsequent drying and pulverization), it is suppressed that other insoluble matter is newly produced as a by-product due to the insoluble matter contained in the water. It is presumed that.

  The method of passing water through the water filter is not particularly limited, and may be performed by a conventionally known method.

  The liquid temperature of the water at the time of performing this process is not specifically limited, It may be room temperature. The upper limit is not particularly limited as long as it does not exceed the heat resistance temperature of the filter to be used.

  The material of the water filter used in this step is not particularly limited as long as it does not cause corrosion, dissolution, or alteration due to water. For example, in addition to polytetrafluoroethylene (PTFE) or metal, cellulose Examples include acetate, cellulose nitrate, polyethersulfone, polypropylene, and nylon filters.

  In the present invention, the amount of insoluble matter in the finally obtained polymer liquid (and polymer powder obtained by using this) is reduced by filtering water using a water filter having a pore size of 50 μm or less. The pore diameter is preferably 30 μm or less, more preferably 20 μm or less, further preferably 10 μm or less, and even more preferably 5 μm or less. The lower limit of the pore diameter is not particularly limited, but a polyamide filter having a pore diameter of 0.2 μm and a cellulose acetate filter having a pore diameter of 0.45 μm are commercially available, which is preferable from the viewpoint of easy availability. . Moreover, you may use the filter used in order to remove the endotoxin in water as a filter for water.

  In this step, two or more filters having different materials and pore sizes may be used in combination as the water filter.

  In the present invention, it is practically preferable to preliminarily filter scales and bacteria in water with a coarse filter before passing water through the water filter.

≪Other monomers≫
In the present invention, only N-vinyl-2-pyrrolidone may be polymerized as a monomer component, but a monomer component containing another monomer together with N-vinyl-2-pyrrolidone may be polymerized. . Examples of such other monomers include (meth) acrylic acid, maleic acid, acrylamide-2-methylpropane sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, and salts thereof, (meth) acrylic acid ester, maleic acid. One selected from the group consisting of acid ester, (meth) acrylamide, N-vinylacetamide, N-vinylformamide, N-vinylimidazole, vinylpyridine, alkyl vinyl ether, acrylonitrile, styrene, vinyl acetate, allyl alcohol, olefins, etc. Or 2 or more types of monomers are mentioned. Note that (meth) acrylic acid esters include alkyl esters having 1 to 20 carbon atoms, dimethylaminomethylalkyl esters, quaternary salts thereof, hydroxyalkyl esters, and the like. The content of these other monomers is preferably from 0 to 50 mol%, more preferably from 0 to 20 mol%, more preferably from 0 to 10 mol, based on the entire structural unit constituting the polymer. % Is more preferable.

≪pH adjustment before polymerization≫
When performing the polymerization reaction, a pH adjuster may be added to the monomer solution before polymerization to adjust the pH of the monomer solution. This is to prevent the monomer (N-vinyl-2-pyrrolidone) from being hydrolyzed.

As the pH adjuster used in this step, a known compound can be used. For example, amine compounds such as primary amines, secondary amines, tertiary amines; NaOH, KOH, Ca (OH) ₂ And alkali (earth) metal hydroxides such as Na ₂ CO ₃ and carbonates such as guanidine carbonate. These pH adjusters may be used alone or in combination of two or more. Of these pH adjusters, secondary amines are preferred.

  When adjusting the pH of the monomer solution before polymerization, a pH adjusting agent or an aqueous solution thereof is added to the monomer solution to adjust the pH to a predetermined value. By this operation, the pH of the monomer solution is preferably adjusted to 7 or more and 10 or less, more preferably 7 or more and 9 or less. In addition, when adding the aqueous solution of a pH adjuster to a monomer solution, it is preferable that the water to be used is the said purified water.

  Secondary amines that can be used to adjust the pH include, for example, dimethylamine, diethylamine, dipropylamine, diisopropylamine, N-methylethylamine, N-methylpropylamine, N-methylisopropylamine, N-methyl. Butylamine, N-methylisobutylamine, N-methylcyclohexylamine, N-ethylpropylamine, N-ethylisopropylamine, N-ethylbutylamine, N-ethylisobutylamine, N-ethylcyclohexylamine, N-methylvinylamine, N -Aliphatic secondary amines such as methylallylamine; N-methylethylenediamine, N-ethylethylenediamine, N, N'-dimethylethylenediamine, N, N'-diethylethylenediamine, N-methyltrimethylenediamine N-ethyltrimethylenediamine, N, N′-dimethyltrimethylenediamine, N, N′-diethyltrimethylenediamine, aliphatic diamines and triamines such as diethylenetriamine, dipropylenetriamine; N-methylbenzylamine, N-ethylbenzyl Aromatic amines such as amine, N-methylphenethylamine, N-ethylphenethylamine; N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-isopropylethanolamine, N-butylethanolamine, N -Monoalkanolamines such as isobutylethanolamine; dialkanolamines such as diethanolamine, dipropanolamine, diisopropanolamine, dibutanolamine; pyrrolidine, piperidine And the like; piperazine, N- methylpiperazine, N- ethylpiperazine, morpholine, cyclic amines, such as thiomorpholine. These secondary amines may be used alone or in combination of two or more. Of these secondary amines, dialkanolamines and dialkylamines are preferred, dialkanolamines are more preferred, and diethanolamines are particularly preferred.

  The use amount of the pH adjuster may be appropriately adjusted according to the use amount of the monomer, and is not particularly limited. For example, the pH of the aqueous monomer solution is preferably 7 or more and 10 or less. Preferably, it may be 7 or more and 9 or less. Specifically, when a secondary amine is used as a pH adjuster, the amount used is preferably 10 ppm or more and 10,000 ppm or less, more preferably 50 ppm or more, 5% relative to the amount of monomer used. 1,000 ppm or less.

≪Insoluble matter amount in the pH adjusted monomer solution≫
In the production process of the present invention, the pH-adjusted monomer solution obtained by adding a pH adjuster (particularly a secondary amine) to the monomer aqueous solution may have an insoluble matter content of 0.3 ppm or less. preferable.

≪Polymerization initiator≫
As the polymerization initiator to be added to the monomer solution (including the pH-adjusted monomer solution; hereinafter the same), it is preferable to use an azo compound and / or an organic peroxide. When hydrogen peroxide is used as a polymerization initiator, the hydrogen abstraction ability is strong, so that the graft reaction is likely to proceed, and a marked increase in molecular weight may be confirmed.

  When adding a polymerization initiator to the monomer solution, nitrogen gas is previously blown into the monomer solution, and the oxygen concentration in the monomer solution is preferably adjusted to 1 ppm or less, more preferably 0.5 ppm or less. It may be left. In addition, the monomer solution is preferably heated to 40 ° C. or higher, more preferably 50 ° C. or higher, more preferably 60 ° C. or higher, preferably 100 ° C. or lower, more preferably 90 ° C. or lower, more preferably 80 ° C. or lower. You may keep it. Thereby, a polymerization reaction can be advanced rapidly.

  Examples of the azo compound that can be used as a polymerization initiator include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2 , 4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (isobutyric acid) dimethyl, 4,4′-azobis (4-cyano) Valeric acid), 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] n hydrate, 2, 2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 1,1'-azo Such as scan (cyclohexane-1-carbonitrile) and the like. These azo compounds may be used alone or in combination of two or more.

  Examples of the organic peroxide that can be used as the polymerization initiator include benzoyl peroxide, cumene hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,1 ′. -Di-t-butylperoxy-3,3,5-trimethylenecyclohexane, 1,3-di- (t-butylperoxy) -diisopropylbenzene, di-t-butyl peroxide, t-butyl hydroperoxide, t-butyl Examples include peroxy-2-ethylhexanoate, t-butylperoxypivalate, t-amylperoxy-2-ethylhexanoate, and t-amylhydroperoxide. These organic peroxides may be used alone or in combination of two or more.

  Moreover, in the case of a polymerization reaction, you may start superposition | polymerization with the redox type polymerization initiator which uses together said organic peroxide and a reducing agent.

Examples of the reducing agent include low valences such as iron (II), tin (II), titanium (III), chromium (II), V (II), Cu (II), and the like represented by mole salts. Metal salts in the state; amine compounds such as monoethanolamine, diethanolamine, triethanolamine, hydroxylamine, hydroxylamine hydrochloride, hydrazine and their salts; sodium dithionite, sodium formaldehyde sulfoxylate, hydroxymethanesulfinic acid In addition to sodium dihydrate, etc., organic compounds and salts thereof including groups such as —SH, —SO ₂ H, —NHNH ₂ , —COCH (OH) —; sodium sulfite, sodium bisulfite, metabisulfite, etc. Alkali metal sulfites, hypophosphorous acid, sodium hypophosphite, hydro Lower oxides such as sodium sulfate and sodium hyponitrite and salts thereof; invert sugars such as D-fructose and D-glucose; thiourea compounds such as thiourea and thiourea dioxide; L-ascorbic acid (salt), L-ascorbic acid ester Erythorbic acid (salt), erythorbic acid ester, and the like.

  Specific examples of the combination of the organic peroxide and the reducing agent include, for example, a combination of benzoyl peroxide and an amine, and a combination of cumene hydroperoxide and a metal compound such as iron (II) or Cu (II).

  The concentration of the polymerization initiator in the polymerization reaction may be appropriately adjusted according to the amount of the monomer component used, and is not particularly limited. For example, it is preferably 0 with respect to 100 parts by mass of the monomer. 0.001 part by mass or more and 3 parts by mass or less, more preferably 0.005 part by mass or more and 2 parts by mass or less, and further preferably 0.01 parts by mass or more and 1 part by mass or less.

≪Polymerization temperature≫
The reaction temperature in the polymerization reaction may be appropriately set according to the conditions such as reaction raw materials, but is preferably 40 ° C to 100 ° C, more preferably 50 ° C to 95 ° C, and further preferably 60 ° C to 90 ° C.

≪pH adjustment during polymerization≫
In the present invention, a secondary amine or an aqueous solution thereof may be added to the reaction solution to adjust the pH to a predetermined value at an appropriate stage from the start to the end of the polymerization reaction. This is to prevent the monomer (N-vinyl-2-pyrrolidone) from being hydrolyzed. Moreover, it is estimated that by using a secondary amine, it is possible to suppress insolubilization of a part of the polymer when the obtained polymer solution is dried.

  Secondary amines that can be used to adjust the pH of the reaction solution during polymerization include the secondary amines listed above as secondary amines that can be used to adjust the pH of the aqueous monomer solution. Can be mentioned. In addition, the secondary amine added to adjust the pH of the reaction solution during the polymerization may be the same as or different from the secondary amine added to adjust the pH of the aqueous monomer solution. .

  The use amount of the pH adjuster may be appropriately adjusted according to the use amount of the monomer and is not particularly limited. For example, the pH of the reaction solution is preferably 7 or more and 10 or less, more preferably. What is necessary is just to make it 7 or more and 9 or less. Specifically, when a secondary amine is used as a pH adjuster, the amount used is preferably 10 ppm or more and 10,000 ppm or less, more preferably 50 ppm or more, based on the amount of monomer used. It is 5,000 ppm or less.

≪Addition of organic acid≫
In the present invention, it is preferable to add an organic acid or an aqueous solution thereof to the reaction solution after the polymerization reaction. At this time, it is preferable to carry out the reaction while maintaining the reaction temperature during the polymerization reaction. As a result, the monomer (N-vinyl-2-pyrrolidone) can be hydrolyzed with an acid to reduce the amount of unreacted monomer (that is, the residual amount of monomer in the reaction solution). . Specifically, the residual amount of the monomer in the finally obtained vinylpyrrolidone polymer powder can be preferably 10 ppm or less, more preferably 8 ppm or less, and even more preferably 6 ppm or less.

  The organic acid that can be used to reduce the amount of the unreacted monomer is preferably a polyvalent carboxylic acid having a boiling point (for example, 100 ° C. or higher) higher than the reaction liquid temperature when the organic acid is added. Specifically, for example, oxalic acid, malonic acid, succinic acid, aspartic acid, citric acid, glutamic acid, fumaric acid, malic acid, maleic acid, phthalic acid, trimellitic acid, pyromellitic acid, and the like are more preferable. An organic acid that is a monovalent carboxylic acid, has a first dissociation constant of the carboxyl group of 3.0 or less, and has a calcium salt solubility in water at 20 ° C. of 0.1% by mass or more, specifically Examples thereof include malonic acid, ethyl malonic acid, ethyl methyl malonic acid, ethyl propyl malonic acid and the like. These organic acids may be used alone or in combination of two or more. Of these organic acids, malonic acid is particularly preferred. In addition, in this invention, when adding the aqueous solution of organic acid to a reaction liquid, it is preferable to use the purified water filtered.

  Here, it is preferable to use an organic acid that satisfies the above conditions. (2) In order to efficiently hydrolyze the monomer, (2) Use an inorganic acid such as hydrochloric acid. This is for preventing halogens such as chlorine from being mixed, and (3) using low boiling point organic acids such as formic acid and acetic acid to prevent the organic acid from volatilizing during addition and mixing.

  The amount of organic acid used may be appropriately adjusted according to the amount of monomer used during the polymerization reaction, and is not particularly limited. For example, the pH of the reaction solution after polymerization is preferably 5 or less, More preferably, it may be 3 or more and 4 or less. Specifically, the use amount of the organic acid is preferably 100 ppm or more and 10,000 ppm or less, more preferably 500 ppm or more and 5,000 ppm or less with respect to the use amount of the monomer.

  Since an organic acid is added to the reaction solution after the polymerization reaction, the vinyl pyrrolidone polymer solution of the present invention and the polymer powder obtained using the same are in a content according to the amount used as described above. It will contain organic acids. However, in order to adjust the pH of the aqueous monomer solution and / or to adjust the pH of the reaction solution during the polymerization, when adding a pH adjusting agent such as a secondary amine, the organic acid is May form salt with pH adjuster. In this case, the vinylpyrrolidone polymer solution of the present invention and the polymer powder obtained using the same contain a salt of the pH adjuster and an organic acid.

≪pH adjustment after polymerization≫
In the present invention, it is preferable to add a secondary amine or an aqueous solution thereof to the reaction solution after polymerization to adjust the pH of the reaction solution to a predetermined value. Thereby, the temporal stability of the polymer in the reaction solution can be enhanced. In addition, when a secondary amine is used, the polymer solution is dried when the obtained polymer solution is dried while preventing a part of the polymer from being insolubilized during neutralization (when the secondary amine is added). It is presumed that a part of can be insolubilized. At this time, it is preferable to carry out the reaction while maintaining the reaction temperature during the polymerization reaction (or during the acid addition).

  Secondary amines that can be used to adjust the pH of the reaction solution after polymerization include the secondary amines listed above as secondary amines that can be used to adjust the pH of the aqueous monomer solution before polymerization. Examples include amines. The secondary amine added to adjust the pH of the reaction solution after the polymerization is a secondary amine added to adjust the pH of the aqueous monomer solution, or to adjust the pH of the reaction solution during the polymerization. It may be the same as or different from the secondary amine to be added.

  The amount of secondary amine used in this step may be appropriately adjusted according to the amount of organic acid used, and is not particularly limited. For example, the pH of the reaction solution is preferably 4 or more and 7 or less. More preferably, it may be 5 or more and 7 or less. Specifically, the use amount of the secondary amine is preferably 100 ppm or more and 10,000 ppm or less, more preferably 120 ppm or more and 5,000 ppm or less with respect to the use amount of the monomer during the polymerization reaction. .

  When secondary amine or its aqueous solution is added to adjust the pH of the reaction solution after reducing the amount of unreacted monomers, the organic acid in the reaction solution forms a salt with this secondary amine. Have In this case, the vinylpyrrolidone polymer solution of the present invention and the polymer powder obtained using the same contain a salt of the secondary amine and organic acid.

≪Insoluble amount in vinylpyrrolidone polymer solution≫
The vinylpyrrolidone-based polymer solution obtained by the production method of the present invention preferably has an insoluble matter content of less than 10 ppm, more preferably 9 ppm or less.

(Production method of polymer powder)
In the present invention, the vinylpyrrolidone polymer solution obtained by the above production method may be dried and then pulverized to obtain a vinylpyrrolidone polymer powder.

  The method for drying the vinylpyrrolidone polymer solution may be a conventionally known method, and is not particularly limited. Examples thereof include a spray dryer drying method and a drum dryer drying method. Conditions such as drying temperature and time may be appropriately adjusted according to the amount of the vinylpyrrolidone polymer solution to be dried, and are not particularly limited. For example, preferably 100 ° C. or higher and 160 ° C. or lower. More preferably, drying may be performed at a temperature of 100 ° C. or higher and 150 ° C. or lower, preferably within 1 hour, more preferably within 30 minutes, and even more preferably within 10 minutes.

  The method for pulverizing the dried vinylpyrrolidone polymer may be a conventionally known method, and is not particularly limited. For example, a dry coarse pulverization method using a pin mill, a hammer mill or the like; a jet mill, a roller mill And dry fine pulverization using a ball mill, micron mill, etc. The pulverization conditions are not particularly limited, and may be set as appropriate so as to obtain a desired particle size according to the use of the powder.

  Here, the vinylpyrrolidone-based polymer powder may be in the form of, for example, granules, granules, spheres, lumps, scales, and amorphous. In addition, the size of the vinylpyrrolidone polymer powder may be appropriately adjusted according to the use of the powder, and is not particularly limited. However, the average particle size is not limited in terms of workability and solubility. Is preferably 10 μm or more and 3,000 μm or less, more preferably 50 μm or more and 1,000 μm or less, and further preferably 80 μm or more and 800 μm or less. Here, the “average particle diameter” is a numerical value measured by the method described below.

  The content of the secondary amine or salt thereof in the finally obtained vinylpyrrolidone polymer powder of the present invention is preferably 500 ppm or more and 10,000 ppm or less, more preferably 800 ppm or more and 6,000 ppm or less, Preferably it is 1,000 ppm or more and 4,000 ppm or less. The content of the secondary amine or a salt thereof is such that the vinyl pyrrolidone polymer powder is made into an aqueous solution and an ion chromatography apparatus (for example, ICS-2000, manufactured by Nippon Dionex Co., Ltd .; the column is Ion Pac AS- 15) is used to measure the content of the secondary amine or salt thereof present in the aqueous solution, and the relative content of the secondary amine or salt thereof to the vinylpyrrolidone polymer powder content is measured. It is calculated | required by calculating content.

<Amount of insoluble matter in vinylpyrrolidone polymer powder>
The vinylpyrrolidone polymer powder obtained by the production method of the present invention preferably has an insoluble matter content of 30 ppm or less.

  If the insoluble matter content is 30 ppm or less, the vinylpyrrolidone polymer powder dissolves in order to produce hollow fiber membranes and membrane filters on an industrial scale using the vinylpyrrolidone polymer powder of the present invention. When the raw material liquid is filtered, the replacement frequency of the filter can be suppressed, so that productivity can be improved. Also, even when the K value of the vinylpyrrolidone polymer powder is increased and the viscosity of the raw material liquid is increased, and it takes a long time to filter the raw material liquid, the filtration operation of the raw material liquid itself is omitted. Can maintain high productivity.

  The vinyl pyrrolidone polymer powder obtained by the production method of the present invention has a K value of preferably 50 or more, more preferably 60 or more, preferably 120 or less, more preferably 100 or less, and still more preferably 95 or less.

(Use)
The vinylpyrrolidone polymer solution and polymer powder obtained by the production method of the present invention are used for, for example, cosmetics, medical and agrochemical intermediates, food additives, photosensitive electronic materials, tackifiers, etc. It can be used for various special industrial applications (for example, production of hollow fiber membranes and membrane filters). In particular, since the content of insoluble matter is small, it is suitable for the production of hollow fiber membranes and membrane filters.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention. In the following examples and comparative examples, “parts” and “%” mean parts by mass and mass%, respectively.

First, a method for measuring the content of insoluble matter, the K value of polymer powder, the pH, the solid content, the amount of residual N-vinyl-2-pyrrolidone, and the average particle size will be described.
(1) Content measurement of insoluble matter (preparation of ion-exchanged water from which insoluble matter has been removed)
Ion exchange water is filtered through a filter having a pore diameter of 0.45 μm (manufactured by ADVANTEC, mixed cellulose ester system, diameter 90 mm), and 5,000 g of ion exchange water from which insoluble matter has been removed is collected.

(Preparation of suction filter)
The weight of a polytetrafluoroethylene filter (Sartorius, diameter 50 mm) having a pore diameter of 1.2 μm is accurately weighed to 0.0001 g (W ₁ g), and then set on a suction filter. Next, 50 g of isopropanol is filtered, and 50 g of ion-exchanged water from which insoluble matter has been removed is filtered to make the filter hydrophilic.

(Preparation of measurement sample)
<PH adjusted monomer solution>
A monomer solution with a pH adjusted obtained in the process of producing a vinylpyrrolidone polymer solution is used as a measurement sample.

<Vinyl pyrrolidone polymer solution>
A measurement sample is prepared by adding ion-exchanged water from which insolubles have been removed to the vinylpyrrolidone polymer solution obtained by the production method of the present invention to adjust the vinylpyrrolidone polymer concentration to 2%.

<Vinyl pyrrolidone polymer powder>
Add 4,900 g of ion-exchanged water from which insoluble materials have been removed to a 5 L beaker, add 100 g of vinylpyrrolidone polymer powder while stirring with a stirring blade, and take 60 minutes at 25 ° C. Dissolve. By this operation, 5,000 g of a 2% vinylpyrrolidone polymer powder aqueous solution is obtained and used as a measurement sample.

(Measurement of insoluble matter)
The measurement sample is suction filtered. After 4 hours from the start of suction filtration, the filtration is terminated, the residual liquid amount is measured, and the filtered liquid amount is obtained (W ₃ g). 50 g of ion-exchanged water from which insoluble matter has been removed is filtered three times, and the filter is washed with water. The filter is taken out from the suction filter and dried using a vacuum dryer at a reduced pressure of -0.09 MPa and a temperature of 70 ° C for 90 minutes. After drying, the mixture is placed in a desiccator and cooled for 10 minutes, and then the mass is measured (W ₂ g). The insoluble content is calculated according to the following formula.
≪Content of insoluble matter in the pH adjusted monomer solution≫
Content of insoluble matter (ppm / N-vinyl-2-pyrrolidone) =
[(W ₂ g-W ₁ g) / N-vinyl-2-pyrrolidone input amount] × 1,000,000
≪Content of insoluble matter in vinylpyrrolidone polymer solution≫
Insoluble content (ppm / vinyl pyrrolidone polymer) =
[(W ₂ g−W ₁ g) / (W ₃ g × 0.02)] × 1,000,000
≪Insoluble content in vinylpyrrolidone polymer powder≫
Content of insoluble matter (ppm / vinyl pyrrolidone polymer powder) =
[(W ₂ g−W ₁ g) / (W ₃ g × 0.02)] × 1,000,000

(2) Method for measuring K value of polymer powder K value is measured with a capillary viscometer at 25 ° C. for a 1% aqueous solution of vinylpyrrolidone polymer powder, and the viscosity formula of the following Fikencher:

[ _Where η _rel is the relative viscosity, c is the concentration of the aqueous solution (g / 100 mL), that is, the number of grams of vinylpyrrolidone polymer powder contained in 100 mL of the aqueous solution, and k ₀ is a variable related to the K value. To express]
Is a numerical value obtained by multiplying the value of k ₀ obtained by 1,000 (hereinafter, a method for obtaining the K value in this way may be referred to as “Fikencher method”). The larger the K value, the higher the molecular weight.

(3) Method for measuring pH of polymer powder The pH of the polymer powder was prepared by preparing a 5% aqueous solution of vinylpyrrolidone polymer powder at 25 ° C. under a pH meter (D- 51).

(4) Method for measuring solid content of polymer powder 2 g of polymer powder is quickly collected in an aluminum cup whose mass has been measured in advance, and precisely weighed to a unit of 0.1 mg. Next, the aluminum cup is housed in a hot air drier adjusted to 150 ± 5 ° C. and dried for 1 hour, and then the aluminum cup is taken out of the drier, immediately covered and cooled in a desiccator for 60 minutes. After cooling, weigh accurately to the nearest 0.1 mg. The solid content is calculated according to the following formula. The solid content is measured at three points and the average value is taken.
Solid content (%) = (W × 100) / S
[Wherein, W is the mass of polymer powder after drying (g), S is the amount of polymer powder collected (g)]

(5) Method for Measuring Residual N-Vinyl-2-Pyrrolidone Amount of Polymer Powder The residual amount of N-vinyl-2-pyrrolidone was prepared by preparing a 5% aqueous solution of vinylpyrrolidone polymer powder and performing liquid chromatography. The amount of N-vinyl-2-pyrrolidone remaining in the aqueous solution was measured at an absorption wavelength of 235 nm, and the relative content of N-vinyl-2-pyrrolidone relative to the content of the vinylpyrrolidone polymer powder was measured. Obtained by calculating the remaining amount.

(6) Measuring method of average particle diameter of polymer powder Vinylpyrrolidone polymer powder is dispersed in ethyl acetate. Next, the particle size distribution of the obtained dispersion is measured using a laser diffraction particle size distribution analyzer SALD-3000 (manufactured by Shimadzu Corporation). The median diameter of the obtained particle size distribution data is defined as the average particle diameter.

Example 1
<Filtration of N-vinyl-2-pyrrolidone>
N-vinyl-2-pyrrolidone was filtered (flow rate: 1400 kg / hr) through a polytetrafluoroethylene filter (manufactured by Chisso Filter, PF-010-W-G04) having a pore size of 1.0 μm to obtain purified NVP. .

<Water filtration>
The ion-exchanged water was filtered (flow rate 10,000 kg / hr) with a cellulose acetate filter (Advantech Toyo Co., Ltd., A045A-047A) having a pore size of 0.45 μm to obtain purified water.

<Preparation of pH adjusted monomer solution>
5589 parts of purified water and 1409 parts of purified NVP were charged into a 12 L reactor equipped with a warm water circulation jacket equipped with a stirrer, a thermometer, a reflux pipe, and a gas blowing pipe. Next, 2.11 parts of a 10% diethanolamine aqueous solution prepared using purified water was added as a pH adjusting agent to prepare a pH adjusted monomer solution (pH 8.5).

<Preparation of polymer solution>
≪Addition of polymerization initiator≫
While stirring this monomer aqueous solution, nitrogen gas was introduced at a flow rate of 1 L / min to remove dissolved oxygen in the pH-adjusted monomer solution (oxygen concentration: 0.2 ppm or less), and then stirred. However, the reactor was heated so that the internal temperature of the reactor became 70 ° C. In this reactor, as a polymerization initiator, an isopropyl alcohol solution of V-59 (manufactured by Wako Pure Chemical Industries, Ltd., 2,2′-azobis (2-methylbutyronitrile)) prepared at a concentration of 9.23% was used. 325 parts were added to initiate the polymerization reaction. After adding the polymerization initiator solution, the jacket warm water temperature was adjusted to 90 ° C. in about 1 hour.

≪Addition of organic acid≫
The reaction is continued for about 3 hours after the addition of the polymerization initiator solution. After the polymerization rate reaches 99.8% (the amount of residual N-vinyl-2-pyrrolidone is 0.2%), purified water is used. Then, 22.7 parts of the 5.6% aqueous malonic acid solution prepared above was added, the reaction solution was adjusted to pH 3.8, and the internal temperature was maintained at 90 ° C. for 90 minutes.

≪pH adjustment after polymerization≫
Subsequently, 27.61 parts of a 6.38% diethanolamine aqueous solution prepared using purified water was added to adjust the reaction solution to pH 6.5, and the internal temperature was maintained at 90 ° C. for 30 minutes. A vinylpyrrolidone-based polymer solution (N-vinyl-2-pyrrolidone homopolymer aqueous solution) was obtained.

<Drying and grinding>
The obtained vinylpyrrolidone-based polymer solution is put into a drum dryer and dried under the operating conditions of a drum surface temperature of 140 ° C. and a drum rotation speed of 1.5 rpm, and then the obtained dried product is put into a crusher and coarsely crushed. And then pulverized using a pulverizer (Victor Mill / VP-1 manufactured by Hosokawa Micron Corporation) to obtain a K value of 88.0, a pH of 6.0, a solid content of 97.0%, and a residual N- A vinylpyrrolidone polymer powder having an amount of vinyl-2-pyrrolidone of 6 ppm and an average particle size of 300 μm was obtained.

<Evaluation>
The insoluble matter content in the obtained pH-adjusted monomer solution, vinylpyrrolidone polymer solution, and vinylpyrrolidone polymer powder was measured. The results are shown in Table 1.

(Examples 2 to 10)
In the same manner as in Example 1, a pH-adjusted monomer solution, a vinyl pyrrolidone polymer solution, and a vinyl pyrrolidone polymer powder were obtained, and the contents of these insolubles were measured. The results are shown in Table 1.

(Comparative Example 1)
A pH-adjusted monomer in the same manner as in Example 1 except that N-vinyl-2-pyrrolidone and ion-exchanged water not filtered with a filter were used instead of purified NVP and purified water in Example 1. Solution, and a vinylpyrrolidone polymer solution having a K value of 88.1, a pH of 6.1, a solid content of 97.0%, a residual N-vinyl-2-pyrrolidone amount of 7 ppm, and an average particle size of A 300 μm vinylpyrrolidone polymer powder was obtained.

<Evaluation>
The insoluble matter content in the obtained pH-adjusted monomer solution, vinylpyrrolidone polymer solution, and vinylpyrrolidone polymer powder was measured. The results are shown in Table 2.
(Comparative Examples 2 to 10)
In the same manner as in Comparative Example 1, a pH-adjusted monomer solution, a vinylpyrrolidone-based polymer solution, and a vinylpyrrolidone-based polymer powder were obtained, and the content of these insoluble matters was measured. The results are shown in Table 2.

  From the results of Tables 1 and 2, when a monomer solution, a polymer solution, and a polymer powder were prepared using purified NVP and purified water (Example), when these were not used (Comparative Example) In contrast, the difference in insoluble matter removal amount in the monomer solution is only 0.69, but the difference becomes 10.3 and 29 as the polymer solution and the polymer powder become. It turns out that it becomes large with .7. That is, it was found that the insoluble matter in the polymer solution and the polymer powder can be significantly reduced by removing the insoluble matter at the monomer solution stage.

  In addition, according to the production method of the present invention, the dispersion of the amount of insoluble matter in the obtained polymer solution and polymer powder can be kept low, so that a polymer liquid and polymer powder with stable quality can be provided. I understood.

  Further, since the monomer solution has a lower viscosity than the polymer powder solution, the filtration operation can be easily performed. For this reason, the productivity of polymer powder having a high K value with a small amount of insoluble matter can be significantly increased.

  The vinylpyrrolidone-based polymer solution and polymer powder of the present invention are used as raw materials or additives, for example, cosmetics, pharmaceutical and agrochemical intermediates, food additives, photosensitive electronic materials, tackifiers and the like. Alternatively, it can be used in various fields for various special industrial applications (for example, production of hollow fiber membranes and membrane filters).

Claims (12)

  A method for producing a vinylpyrrolidone-based polymer solution, wherein a monomer containing N-vinyl-2-pyrrolidone that has been passed through a filter having a pore size of 50 μm or less is polymerized in a solvent.   The method for producing a vinylpyrrolidone polymer solution according to claim 1, wherein water that is passed through a filter having a pore size of 50 μm or less is used as the solvent.   The method for producing a vinylpyrrolidone polymer solution according to claim 1 or 2, wherein an organic acid is added to the reaction solution after the polymerization.   The method for producing a vinylpyrrolidone polymer solution according to any one of claims 1 to 3, wherein a secondary amine is added to the reaction solution after the polymerization.   A method for producing a vinylpyrrolidone polymer powder, characterized in that the vinylpyrrolidone polymer solution obtained by the production method according to any one of claims 1 to 4 is dried and then pulverized.   A vinylpyrrolidone-based polymer solution obtained by polymerizing a monomer containing N-vinyl-2-pyrrolidone in a solvent through a filter having a pore size of 50 μm or less.   The vinylpyrrolidone polymer solution according to claim 6, wherein water having passed through a filter having a pore size of 50 μm or less is used as the solvent.   The vinylpyrrolidone-based polymer solution according to claim 6 or 7 obtained by adding an organic acid to the reaction solution after polymerization.   The vinylpyrrolidone polymer solution according to any one of claims 6 to 8, obtained by adding a secondary amine to the reaction solution after polymerization.   The vinylpyrrolidone polymer solution according to any one of claims 6 to 9, wherein the insoluble matter content is 9 ppm or less.   A vinylpyrrolidone polymer powder obtained by drying and then pulverizing the vinylpyrrolidone polymer solution according to any one of claims 6 to 10.   The vinyl pyrrolidone-based polymer powder according to claim 11, having a K value of 50 or more and 120 or less and an insoluble content of 30 ppm or less.