JP2002146033A - Method for producing vinylpyrrolidone-based polymer powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain vinylpyrrolidone-based polymer powder having high bulk specific gravity and improved handling easiness. SOLUTION: The method for producing vinylpyrrolidone-based polymer powder comprises a drying process by coating a solution containing at least one kind of vinylpyrrolidone-based polymer at least two times on the heat transfer surface of a heating surface adhesion-type dryer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a vinylpyrrolidone-based polymer powder having a high bulk specific gravity and improved handleability.

[0002]

2. Description of the Related Art Vinylpyrrolidone-based polymers such as polyvinylpyrrolidone and vinylpyrrolidone copolymer have advantages and advantages such as biocompatibility, safety and hydrophilicity. Are widely used in various fields such as paints, dispersants, inks, and electronic components.

[0003] As described above, vinylpyrrolidone polymers are used in a wide variety of applications. Therefore, when a vinylpyrrolidone polymer is applied to various uses, the solvent used to obtain the polymer must remain in the polymer. That is, it must be a powder. To use the vinylpyrrolidone-based polymer powder, the powder is often dissolved in some solvent.
When the powder is dissolved in a solvent, if the powder is bulky, that is, if the bulk specific gravity is low, the powder is likely to float on the surface of the solvent, and further powder (the powder that remains without being kneaded when the powder is kneaded with water or the like). Portion) is easily formed, and a very complicated operation and a long-time dissolving operation are required. Further, the powder having a low bulk specific gravity is economically disadvantageous in terms of transportation cost and inventory space.

On the other hand, in order to dry a particularly viscous polymer solution obtained by solution polymerization, suspension polymerization, emulsion polymerization or the like, a heating surface contact type dryer such as a drum dryer or a belt dryer is known.

[0005]

However, polyvinylpyrrolidone and the like, which have a particularly high glass transition temperature, are liable to become a non-flowable gel during the drying process. Many air bubbles are easily generated inside the object. Therefore, even if a vinylpyrrolidone-based polymer powder is produced using the above method, it is difficult to obtain sufficient bulk specific gravity with good productivity. Accordingly, an object of the present invention is to provide a method capable of easily producing a vinylpyrrolidone-based polymer powder having a high bulk specific gravity and improved handleability.

[0006]

An object of the present invention is to coat and dry a solution containing at least one kind of vinylpyrrolidone polymer on a heat transfer surface of a heating surface contact type dryer at least twice. This has been found to be a solution.

Under various conditions, the present inventors have applied a solution containing a vinylpyrrolidone-based polymer to a heat transfer surface of a heating surface contact type dryer, scraped a dried product, and crushed the dried product. However, it was not found that a powder having a sufficient bulk specific gravity was obtained. On the other hand, as a result of further various studies, bubbles were caught in the dried product obtained by coating the solution on the heat transfer surface of the heating surface contact type dryer, and a sufficient bulk specific gravity was obtained. It is found that there is no such material, and by performing a very simple operation of performing the coating twice or more, a dried product with few bubbles can be obtained. The dried product is scraped off according to a usual method, and crushed as necessary. Thus, an excellent vinylpyrrolidone-based polymer powder having a high bulk density can be easily obtained.

According to the present invention, a high-viscosity liquid that is difficult to dry and a coating that is difficult to apply are set by appropriately setting the drying conditions of the heating surface contact dryer and the supply method and supply conditions of the solution containing the vinylpyrrolidone polymer. It can sufficiently cope with drying of various solutions such as a low viscosity liquid. According to the present invention, a vinylpyrrolidone-based polymer powder having a bulk specific gravity of 0.3 g / ml or more can be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The “vinylpyrrolidone-based polymer” in the present invention is specifically a polyvinylpyrrolidone and / or a vinylpyrrolidone copolymer. Further, the "solution containing a vinylpyrrolidone-based polymer" refers to a reaction solution obtained after the polymerization reaction of the vinylpyrrolidone-based polymer described below, or a solution obtained by dissolving a dried product of the vinylpyrrolidone-based polymer in a solvent. Means At this time, it is not necessary that the whole amount of the dried product is dissolved, and a part of the dried product may remain undissolved. Hereinafter, the solution may be simply referred to as “polymer-containing solution”.

[0010] Polyvinylpyrrolidone is a compound represented by the following general formula (1) and is obtained by polymerizing vinylpyrrolidone by an arbitrary method as described below.

[0011]

Embedded image

The vinylpyrrolidone copolymer is a copolymer containing vinylpyrrolidone and a comonomer copolymerizable therewith. The comonomer to be copolymerized with vinylpyrrolidone is not particularly limited, and specifically includes, for example, 1) methyl (meth) acrylate, (meth)
(Meth) acrylates such as ethyl acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, hydroxyethyl (meth) acrylate;
2) (meth) acrylamide and (meth) acrylamide derivatives such as N-monomethyl (meth) acrylamide, N-monoethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide; 3) (meth) acrylic acid Basic unsaturated monomers such as dimethylaminoethyl, dimethylaminoethyl (meth) acrylamide, vinylpyridine and vinylimidazole; 4) vinylamides such as vinylformamide, vinylacetamide and vinyloxazolidone; 5) (meth) acrylic acid; Carboxyl group-containing unsaturated monomers such as itaconic acid, maleic acid and fumaric acid; 6) unsaturated acid anhydrides such as maleic anhydride and itaconic anhydride; 7) vinyl esters such as vinyl acetate and vinyl propionate 8) vinyl ethylene carbonate and its derivatives; 9 Styrene and its derivatives; 1
0) Ethyl (meth) acrylate-2-sulfonate and its derivatives; 11) Vinyl sulfonic acid and its derivatives; 12) Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether;
3) olefins such as ethylene, propylene, octene and butadiene; and the like. Among these comonomers, from the viewpoint of copolymerizability with vinylpyrrolidone, etc.,
1) to 8) are particularly preferred. The above comonomer is 1
Only one type may be used, or two or more types may be mixed and copolymerized with vinylpyrrolidone.

The proportion of vinylpyrrolidone in all monomer components in the vinylpyrrolidone copolymer is not particularly limited, but is preferably 5 mol% or more based on all monomer components.
0 mol% or more is more preferable, and 50 mol% or more is most preferable. When the vinylpyrrolidone content in the copolymer is 5 mol% or more, various properties derived from vinylpyrrolidone can be sufficiently exhibited, which is preferable.

The polymerization reaction for obtaining the vinylpyrrolidone polymer can be carried out by a conventionally known polymerization method, for example, bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, precipitation polymerization and the like.

The polymerization reaction for obtaining the vinylpyrrolidone polymer is carried out by a conventionally known polymerization initiator, specifically, for example, 2,2
Radical polymerization based polymerization initiation of azo compounds such as 2'-azobisisobutyronitrile and 2,2'-azobis (2-methylpropionamidine) dihydrochloride, and peroxides such as benzoyl peroxide and hydrogen peroxide. And a cationic polymerization initiator such as boron trifluoride or a complex thereof, iron (II) chloride, diethylaluminum chloride, diethylzinc, heteropolyacid, activated clay, and the like.
The concentration of the polymerization initiator in the polymerization reaction is not particularly limited.
% By weight, more preferably 0.01 to 5% by weight, and most preferably 0.05 to 3% by weight. In conducting the polymerization reaction, any chain transfer agent, cocatalyst, pH adjuster, buffer, etc. may be used as needed, in addition to the polymerization initiator.

The solvent used for the polymerization reaction for obtaining the vinylpyrrolidone-based polymer or the solvent used for preparing the solution containing the vinylpyrrolidone-based polymer is not particularly limited. For example, water; methyl alcohol, ethyl alcohol, Alcohols such as isopropyl alcohol and diethylene glycol; alkylene glycol ethers (acetates) such as propylene glycol monomethyl acetate and diethylene glycol monomethyl ether acetate; amides such as dimethylformamide and N-methylpyrrolidone; ethyl acetate, butyl acetate and γ-butyrolactone Esters such as hexane and octane; alicyclic saturated hydrocarbons such as cyclohexane; alicyclic unsaturated hydrocarbons such as cyclohexene; benzene and toluene Aromatic hydrocarbons such as xylene; ketones such as acetone and methyl ethyl ketone; halogenated hydrocarbons such as dichloroethane, chloroform and carbon tetrachloride; ethers such as diethyl ether, dioxane and tetrahydrofuran; sulfonic acid esters such as dimethyl sulfoxide , Carbonates such as dimethyl carbonate and diethyl carbonate; ethylene carbonate;
Alicyclic carbonates such as propylene carbonate; and the like. Of these, ethers (acetates) and amides are particularly preferred, and water and alcohols are more preferred. These solvents may be used alone or
More than one kind can be mixed and used.

These solvents have a polymer concentration of preferably 1 to 99% by weight, more preferably 5 to 70% by weight, in the polymer solution after the polymerization reaction or after dissolving the vinylpyrrolidone polymer. Preferably, it is used so as to be 10 to 60% by weight.

Further, at least one antioxidant is added to the vinylpyrrolidone-based polymer at a ratio of preferably 0.00001 to 30% by weight, more preferably 0.01 to 3% by weight. Is preferred. This not only suppresses a change in K value and coloring that occur when the polymer solution is dried, but also improves the storage stability of the vinylpyrrolidone-based polymer. Examples of usable antioxidants include phenolic antioxidants such as sodium salicylate and potassium methylbenzotriazole; bisphenol antioxidants such as 2,2'-methylenebis (4-methyl-6-t-butylphenol) A high molecular weight phenolic antioxidant such as 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane; a sulfur type antioxidant such as dilauryl 3,3'-thiodipropionate Antioxidants; phosphorus-based antioxidants such as triphenyl phosphite; alcohol-based antioxidants such as erythorbic acid; amine-based antioxidants such as methylated diphenylamine; 4-benzoyloxy-2,
Hindered amine antioxidants such as 2,6,6-tetramethylpiperidine; and the like. One of these antioxidants may be used alone, or two or more thereof may be used in combination.

In the present invention, the method of blending the antioxidant with the vinylpyrrolidone-based polymer is as follows.
Although there is no particular limitation, it is preferable to mix the reaction solution after the polymerization reaction or a solution of a vinylpyrrolidone polymer obtained by dissolving a dried product of the vinylpyrrolidone polymer in a solvent.

In the present invention, the pH of the polymer-containing solution in a 5% by weight aqueous solution is preferably from 4 to 12, more preferably from 5 to 9. When the pH of the polymer-containing solution is in the above-mentioned range, no insolubles are generated at the time of drying, and the K value is not significantly reduced, which is favorable.

Further, the polymer-containing solution of the present invention preferably has a K value represented by the Fikentcher equation defined below of preferably 50 to 130, more preferably 70 to 120. Within this range, the polymer-containing solution exhibits good film-forming properties on the heat transfer surface, and is therefore preferred.

Here, the K value is a value calculated from the following Fikentcher equation using the measured viscosity.

[0023]

(Equation 1)

The polymer-containing solution applied to the present invention further contains various additives such as a processing stabilizer, a plasticizer, a dispersant, a filler, an antioxidant, a pigment and a curing agent, if necessary. May be.

The method of the present invention comprises a step of coating a solution containing at least one vinylpyrrolidone-based polymer described above at least twice on a heat transfer surface of a heating surface contact dryer and coating and drying the solution. Features.

The heating surface contact type dryer of the present invention is a device for heating and drying a material by heat conduction from a surface heated by a heat medium, that is, a heat transfer surface. By coating the solution containing the vinylpyrrolidone polymer twice or more, it is possible to obtain a dried product of the vinylpyrrolidone polymer having few air bubbles on the heat transfer surface. Further, the heating surface contact type dryer of the present invention includes a stock solution feeder, and may further include a dried material peeling device / apparatus, a crusher, a transporter, and the like.

The heat medium is not particularly limited, and various kinds of conventionally known heat mediums can be used. Specific examples thereof include organic heat medium oils such as Dow sam, hot water, steam, silicone oil, electric heaters and the like. Is mentioned.

The heat transfer surface may be any type in which a heat medium is present therein and serves as a heat source for the material, and may be a movable type or a fixed type. There is no limitation on the shape of the heat transfer surface, and the heat transfer surface may be flat, curved such as a convex surface or a concave surface, or may have any other shape.
The material of the heat transfer surface is not particularly limited, and any material such as stainless steel, iron, titanium, Teflon (registered trademark), and rubber can be applied. Among them, those made of metal such as stainless steel are preferable because of their high heat transfer efficiency. Further, the heat transfer surface in the present invention includes not only a surface heated by a heat medium but also a transport belt, a tray filled with materials, and the like. Further, in the present invention, it is possible to further increase the drying efficiency by using one or more of infrared rays, microwaves, hot air and the like in addition to heating from the heat transfer surface. As the heating surface contact type dryer corresponding to the above contents, various types of conventionally known dryers can be used. For example, drum dryers (single, double, twin, etc.), belt dryers, shelf-type dryers, multi-cylinder cylinders Mold dryer, compact disk dryer and the like.

The stock solution feeder is not particularly limited, and various types known in the art can be used, and examples thereof include a oscillating nozzle, a header type nozzle, a spray, a roller, a blade, and a dipping bath. Similarly, the dry material peeling device and apparatus are not particularly limited, and various conventionally known types can be used, and examples thereof include a scraper such as a doctor knife, a paddle, and a spatula. The crusher / pulverizer is not particularly limited, and any one described later can be applied. Further, each of the operations of drying, crushing, and pulverization described above may be performed in a dehumidified atmosphere depending on the properties (hygroscopicity and the like) of the product powder.

The temperature of the heat transfer surface of the dryer is not particularly limited, and is preferably higher than the boiling point of the solvent of the polymer-containing solution, and more preferably higher than the boiling point by 10 ° C. or more. Further, the temperature of the heat transfer surface is preferably lower than the glass transition temperature of the vinylpyrrolidone-based polymer contained in the solution by 10 ° C. or more. As a result, the film-forming property of the polymer is improved, and thus the polymer can be easily applied repeatedly. Specifically, although it depends on the vinylpyrrolidone-based polymer to be used, its solution temperature, and the method of supplying the solution, it is preferably 80 ° C to 180 ° C, more preferably 10 ° C to 180 ° C.
The reaction is performed at a temperature of 0 ° C to 170 ° C, more preferably 120 ° C to 160 ° C.

The drying time from the first application of the solution to the peeling can be set arbitrarily according to the vinylpyrrolidone-based polymer to be used, the concentration of the solution, the method of supplying the solution, the drier, and the like.範 囲 60 minutes. The coating thickness of the solution also depends on the vinylpyrrolidone polymer used, the concentration of the solution, the method of supplying the solution, the dryer, etc., but is preferably about 0.05 mm to 10 mm, and about 0.1 mm to 5 mm. Is more preferable. The method of adjusting the coating thickness is not particularly limited, and adjusts the clearance between the calender, the blade, the roller, and the heat transfer surface, and adjusts the viscosity of the solution,
Any method such as adjusting the supply speed of the solution can be applied. The solution supply speed can be set at any set value, but it is preferable to set the solution in consideration of the balance between productivity and the quality (moisture) of the dried product.

The moisture content of the dried product obtained by the above preferred method and conditions is 10% or less on a wet basis, and can be reduced to 5% or less. Further, by further optimizing the conditions and the like, it is possible to reduce the value to 1% or less. The thickness of the product film depends on the vinylpyrrolidone polymer used, the concentration of the solution, the method of supplying the solution, and the like.
Those having a size of about 01 mm to 5 mm can be obtained.

Among the above-mentioned heating surface contact type dryers, drum dryers, belt dryers, and shelf-type dryers that can be preferably used in the present invention are particularly suitable for heat efficiency, rapidity, continuous operability and the like. From the viewpoint, a drum dryer is preferable. Drum dryer is on the surface of the rotating drum heated from the inside with steam or other heat medium,
This is a device in which the solution containing the vinylpyrrolidone-based polymer is applied in a thin film form, evaporated and dried during one rotation, and the dried product is scraped off with a scraping device (scraper) such as a doctor knife. In the present invention, while the drum makes one rotation, supply (application) and drying of the solution are repeated to obtain a dried product. Here, in the supply of the solution after the second time, it is not necessary that the film supplied before that is completely dried. If the film is substantially dried so as not to hinder the supply of the solution after the second time. Good.

In the present invention, either a single drum dryer as shown in FIG. 1 or a double or twin drum dryer as shown in FIG. 2 may be used. Especially the single drum dryer
It is preferable in that various solution supply methods can be applied and drying design is easy.

Hereinafter, a case where a drum dryer is applied to the present invention will be described in detail. The method of applying the solution is not particularly limited, and any stock solution feeder as described above can be used. Specific examples thereof include a dip feed method, a roll feed method, a splash feed method, and a spray feed method. Can be The dip feed method is a method in which a liquid tank is provided at a lower portion of a drum, a solution is supplied to the tank, the drum is immersed in the liquid, and the solution is attached to the drum surface and supplied. If you use this method,
It is preferable to provide a stirrer in the liquid tank to prevent precipitation of solids and to keep the concentration distribution of the liquid uniform. The roll feed system is a system in which a solution is supplied between a drying drum and a feed roll by a conventionally known oscillating nozzle, header type nozzle, single tube, or the like, and an object to be dried is attached to the drying drum.

In the case of the splash feed method or the spray feed method, a liquid tank is provided at a lower portion of a drum, a solution is supplied to the liquid tank, and the solution in the liquid tank is homogenized. In the case of a spray feed, a solution is taken out from a liquid tank and sprayed from a spray nozzle onto the drum surface using a pump to attach the blade to the drum surface.

According to the present invention, the method of the present invention can be easily achieved by appropriately designing the above-mentioned supply system so that the solution is coated on the heat transfer surface twice or more. Two or more of one kind of supply method may be set, or two or more kinds of supply methods may be used in combination. The dip-feed method and the roll-feed method are advantageous in that the supply of the high-viscosity liquid is easy and the loss of the solution due to the rebound of the solution from the drum and the contamination of the apparatus are hardly generated.

The temperature of the heat transfer surface of the drum dryer can be set in the above-mentioned temperature range. The rotation speed of the drum is not particularly limited, as with the heat transfer surface temperature, and depends on the vinylpyrrolidone-based polymer to be used, its solution temperature, the method of supplying the solution, and the desired physical properties of the vinylpyrrolidone-based polymer powder. Can be set as appropriate. Usually, 0.
1 rpm to 10 rpm, preferably 0.2 rpm to 5 r
pm, more preferably 0.3 rpm to 3 rpm.

The coating thickness of the solution can be about 0.1 mm to 5 mm, depending on the vinylpyrrolidone polymer used, the concentration of the solution and the method of supplying the solution. The method of adjusting the coating thickness is not particularly limited, and adjusts the clearance between the calender, the blade, the roller, and the heat transfer surface, and adjusts the viscosity of the solution,
Any method such as adjusting the supply speed of the solution can be applied. The solution supply speed can be set at an arbitrary set value, but it is preferable to consider the balance between the productivity and the quality (moisture) of the dried product, and to supply the solution per unit heat transfer area of the rotating drum. The speed is 1 kg / (m ² · hr)
１００100 kg / (m ² · hr), preferably 5 kg / (m ² · hr)
(M ² · hr) to 50 kg / (m ² · hr) is more preferable.

The moisture content of the dried product obtained by the above-mentioned preferred method and conditions can be the above-mentioned amount. The thickness of the product film depends on the vinylpyrrolidone polymer used, the concentration of the solution, the method of supplying the solution, and the like, but can be about 0.01 mm to 0.3 mm.

The dried product obtained by the multi-layer coating obtained as described above is scraped off by a scraping device (scraper) such as a doctor knife according to a conventionally known method and, if necessary, subjected to a pulverizing step. , A vinylpyrrolidone-based polymer powder can be obtained. If the peeled dried product is not in the desired powdery properties but in the form of coarse particles, ribbons, sheets, rods, or the like, it is necessary to further form the powder through a crushing or pulverizing step. Equipment for crushing and crushing at that time,
There is no particular limitation, and examples thereof include a paddle type, a hammer mill, a pin mill, a ball mill, a thin mill, and a vibration mill. The operations of drying, crushing, and pulverization described above may be performed in a dehumidified atmosphere depending on the properties (hygroscopicity, etc.) of the product powder. The average particle size of the obtained powder is not particularly limited and can be appropriately set depending on the application, but is preferably in the range of 30 μm to 300 μm.

The vinylpyrrolidone-based polymer powder obtained by the present invention has a high bulk specific gravity, has improved solubility in a solution, and has good handleability. According to the present invention, a vinylpyrrolidone-based polymer powder having a bulk specific gravity of 0.3 g / ml or more, particularly 0.4 g / ml or more can be obtained. Incidentally, the bulk specific gravity in the present invention refers to JIS K7370.
This is the value obtained by the method of "How to determine the apparent bulk density of plastic."

[0043]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. Example 1 Water 1 was added to a 20-liter reactor equipped with a stirrer, a monomer supply tank, a thermometer, a heating bath, a cooling pipe, and a N ₂ gas introduction pipe.
2.8 kg was charged and sealed with N ₂ gas. The temperature inside the flask was heated to 70 ° C. while stirring. 3.2 kg of vinylpyrrolidone and 1 g of 2,2'-azobis (2-amidinopropane) dihydrochloride were fed into the system over 30 minutes.
After heating at the same temperature for 2 hours, the internal temperature was raised to 100 ° C., and further heated for 1 hour to obtain a polyvinylpyrrolidone having a K value of 91.
A 0% by weight aqueous solution was obtained. The viscosity at 25 ° C. of this aqueous solution was 24000 mPa.

As shown in FIG. 1, a metal coating roll having a diameter of 100 mm and a clearance of 0 mm between the heating drum and a single drum dryer having a heating drum having a diameter of 568 mm and a width of 560 mm (a drum heating area of 1 m ² ) were used. Set at 2 places to be 3mm, 200m in diameter
m of a rubber roll in close contact with the heating drum,
It was set as an application roll. Here, the position of the second application roll is set at the same height as the rotation axis of the drum main body, the first application roll / second application roll installation angle α is 45 °, and the third application roll / second application roll installation angle β is −. Set to 45 °.

After steam was introduced into the heating drum and the temperature of the heating surface of the heating drum was set at 140 ° C., the heating drum was heated at 1 rpm.
The coating roll was rotated at a constant speed of m, and the coating roll was rotated such that the peripheral speed of the outer peripheral portion of the coating roll became the peripheral speed of the outer peripheral portion of the heating drum. The polyvinylpyrrolidone aqueous solution was supplied to three application rolls by a liquid feed pump to obtain a sheet-shaped dried product. The supply rate of the aqueous solution is 12.5 kg / hr
Met. The moisture content of the obtained dried product was confirmed to be 1.6% by weight by a Karl Fischer moisture meter.

The above-mentioned dried sheet is formed into flakes by a paddle type coarse pulverizer and then pulverized by a hammer mill using a screen having a hole diameter of 1 mm to obtain an average particle diameter of 150 mm.
A μm polyvinylpyrrolidone powder was obtained. The bulk specific gravity of the obtained polyvinylpyrrolidone powder was 0.52 g / ml.

Example 2 The number of rotations of the heating drum and the coating roll was set to 1 in Example 1.
5 times and the supply rate of the aqueous solution of polyvinylpyrrolidone is 1
Except for 8.0 kg / hr, the same as in Example 1
A sheet-like dried product having a water content of 1.9% by weight was obtained. Further, it was crushed and pulverized in the same manner as in Example 1 to obtain an average particle diameter of 150 μm.
m, a polyvinylpyrrolidone powder having a bulk specific gravity of 0.48 g / ml was obtained.

Example 3 The procedure of Example 1 was repeated, except that the temperature of the heating surface of the heating drum was 155 ° C., and the supply rate of the aqueous solution of polyvinylpyrrolidone was 17.0 kg / hr. A sheet-like dried product was obtained. Further, it was crushed and pulverized in the same manner as in Example 1 to obtain an average particle diameter of 155 μm and a bulk density of 0.47.
g / ml of polyvinylpyrrolidone powder was obtained.

Example 4 The procedure of Example 1 was repeated, except that the amount of 2,2'-azobis (2-amidinopropane) dihydrochloride was changed to 8 g, to obtain a polyvinylpyrrolidone having a K value of 67. 2
0% by weight aqueous solution (viscosity at 25 ° C. of 1800 mPa
-S). Using this solution, the feed rate was 12.0 kg /
A water content of 2.3 in the same manner as in Example 1 except for changing to hr.
By weight, a sheet-shaped dried product was obtained. Further, it was crushed and pulverized in the same manner as in Example 1 to obtain a polyvinylpyrrolidone powder having an average particle size of 155 μm and a bulk specific gravity of 0.56 g / ml.

Example 5 Example 3 was repeated except that the third application roll was removed from the three application rolls used in Example 1, and the supply rate of the aqueous solution of polyvinylpyrrolidone was 10.5 kg / hr.
In the same manner as in the above, a sheet-shaped dried product having a water content of 1.7% by weight was obtained. Further, it was crushed and pulverized in the same manner as in Example 1 to obtain a polyvinylpyrrolidone powder having an average particle diameter of 165 μm and a bulk specific gravity of 0.43 g / ml.

Example 6 As shown in FIG. 2, the clearance between the heating drums of a double drum dryer (drum heating area: 1 m ² ) having a heating drum having a diameter of 400 mm and a width of 400 mm was set to 0.5 m.
m, and a metal coating roll having a diameter of 100 mm was set at one position for each heating drum so that the clearance from the heating drum was 0.3 mm. Further, a liquid receiving tray was set below the application roll. Here, the second coating roll installation angle γ was set to −45 °.

Steam was introduced into the heating drum, and the temperature of the heating surface of the heating drum was set to 140 ° C.
The coating roll was rotated at a constant speed at a speed of rpm, and the coating roll was rotated such that the peripheral speed of the outer peripheral portion of the coating roll became the peripheral speed of the outer peripheral portion of the heating drum. The aqueous solution of polyvinylpyrrolidone used in Example 1 was supplied between the heating drums and to the application roll section by a liquid sending pump. The supply rate of the aqueous solution is 10.0 kg
/ Hr, and a sheet-like dried product having a water content of 1.8% by weight was obtained. Further, it was crushed and pulverized in the same manner as in Example 1 to obtain a polyvinylpyrrolidone powder having an average particle size of 160 μm and a bulk specific gravity of 0.40 g / ml.

Comparative Example 1 Of the three application rolls used in Example 1, the second and third application rolls were removed, and the clearance between the first application roll and the heating drum was adjusted to 0.5 mm. After the temperature of the heating surface of the heating drum was set to 140 ° C., the heating drum was rotated at a constant speed of 1 rpm, and the aqueous solution of polyvinylpyrrolidone used in Example 1 was sent by a liquid sending pump.
The mixture was supplied to the application roll at a supply speed of 0 kg / hr to obtain a sheet-shaped dried product having a water content of 2.4% by weight. Further, the powder was crushed and pulverized in the same manner as in Example 1 to obtain a polyvinylpyrrolidone powder having an average particle diameter of 160 μm. The obtained powder had a bulk specific gravity of 0.25 g / ml and was very bulky. Met.

[0054]

According to the present invention, a vinylpyrrolidone-based polymer powder having a high bulk specific gravity and good handleability can be obtained by a very simple method.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a single drum dryer used in an example.

FIG. 2 is a schematic sectional view of a double drum dryer used in Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating drum 2 Scraper 3 1st application roll 4 2nd application roll 5 3rd application roll 6 Liquid supply pump 7 Liquid supply line 8 Dry matter 9 Liquid receiving tray for 2nd application roll alpha 1st application roll / 2nd application roll installation Angle β Third coating roll / second coating roll installation angle γ Second coating roll installation angle

Continued on the front page (72) Inventor Masatoshi Kurahashi 5-8, Nishiobari-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. (72) Inventor Hiroaki Aku 992, Nishioki, Akahama-ku, Aboshi-ku, Himeji-shi, Hyogo 1 Nippon Shokubai Co., Ltd. F term (reference) 4F070 AA38 AC45 AE28 DA21 DC08 DC12 DC16

Claims (2)

[Claims] 1. A method for coating and drying a solution containing at least one kind of vinylpyrrolidone-based polymer on a heat transfer surface of a heating surface contact type drier twice or more. A method for producing a polymer powder. 2. The method for producing a vinylpyrrolidone-based polymer powder according to claim 1, wherein the bulk specific gravity of the powder is 0.3 g / ml or more.