JP4933112B2 - Handling method of vinylpyrrolidone polymer - Google Patents

Description

  The present invention relates to a method for handling a vinylpyrrolidone polymer, and more particularly to a method for handling a vinylpyrrolidone polymer that suppresses a decrease in the K value with time.

  Vinyl pyrrolidone polymers having various K values are produced and used depending on their applications. The K value is a constant representing the degree of polymerization (molecular weight) proposed by German chemist Fikencher.

However, it is known that the vinyl pyrrolidone polymer has a K value that decreases with time during storage, and as a countermeasure, it is mainly stored in contact with an inert gas (for example, patents). Reference 1). In particular, in the case of commercialization, a method is used in which after the vinylpyrrolidone polymer is introduced into the packaging material, an inert gas such as nitrogen is introduced into the packaging material and sealed.
Japanese Patent No. 3274127

  The above conventional method suppresses the decrease in the K value to some extent, but is not sufficient. For a product that requires strict management of the K value, such as a viscosity modifier, there is a more effective method. It was sought after.

  The present invention has been made in view of the above, and an object of the present invention is to provide a handling method capable of reducing the decrease in K value over time during storage of a vinylpyrrolidone polymer.

In order to solve the above problems, the method for handling the vinyl pyrrolidone polymer of the present invention is to form a sheet by drying the solution containing the vinyl pyrrolidone polymer using a heating surface contact type dryer. The sheet-like vinylpyrrolidone polymer is cooled while flowing an inert gas in a cooling process line that is a pipe-shaped or tunnel-shaped shielded space and is blocked from outside air except for the entrance and exit. The coalescence is to be stored sealed in an atmosphere having an oxygen concentration of 5% or less.

  In the above, when the cooled vinylpyrrolidone polymer is used as a powder, vinylpyrrolidone is pulverized while introducing an inert gas from the intake port in a pulverizer equipped with an intake port that introduces gas into the pulverization section. It is preferable to form a polymer powder and store the vinylpyrrolidone polymer in the form of a powder in an atmosphere having an oxygen concentration of 5% or less.

  According to the method for handling the vinylpyrrolidone polymer of the present invention, it is possible to more effectively suppress the decrease in the K value as compared with the conventional method.

  The vinyl pyrrolidone polymer that is the subject of the present invention is a homopolymer of vinyl pyrrolidone (N-vinyl-2-pyrrolidone, hereinafter also referred to as VP) or a copolymer of VP and other monomers. Other monomers are not particularly limited as long as they are copolymerizable with VP. Examples thereof include acrylic acid, methacrylic acid, alkyl esters of acrylic acid (such as methyl acrylate and ethyl acrylate), and methacrylic acid. Alkyl esters (methyl methacrylate, ethyl methacrylate, etc.), aminoalkyl esters of acrylic acid (diethylaminoethyl acrylate, etc.), aminoalkyl esters of methacrylic acid, monoesters of acrylic acid and glycol, monoesters of methacrylic acid and glycol ( Hydroxyethyl methacrylate), acrylic An alkali metal salt of methacrylic acid, an ammonium salt of acrylic acid, an ammonium salt of methacrylic acid, a quaternary ammonium derivative of an aminoalkyl ester of acrylic acid, a quaternary ammonium derivative of an aminoalkyl ester of methacrylic acid, Quaternary ammonium compounds of diethylaminoethyl acrylate and methyl sulfate, vinyl methyl ether, vinyl ethyl ether, alkali metal salts of vinyl sulfonic acid, ammonium salts of vinyl sulfonic acid, styrene sulfonic acid, styrene sulfonate, allyl sulfonic acid, Allyl sulfonate, methallyl sulfonic acid, methallyl sulfonate, vinyl acetate, vinyl stearate, N-vinyl imidazole, N-vinyl acetamide, N-vinyl formamide, N-vinyl carbonate Rorakutamu, N- vinylcarbazole, acrylamide, methacrylamide, N- alkyl acrylamide, N- methylolacrylamide, N, N- methylenebisacrylamide, glycol diacrylate, glycol dimethacrylate, divinyl benzene, glycol diallyl ether. The proportion of vinyl pyrrolidone and other monomers is not particularly limited, but as a guide, the proportion of VP is 20% by weight or more.

  The vinyl pyrrolidone polymer can be produced by a conventionally known production method, that is, a method in which a vinyl pyrrolidone monomer is polymerized, for example, in an aqueous solution using a radical polymerization initiator.

  The “solution containing a vinylpyrrolidone polymer” as used in the present invention means a solution obtained by dissolving a reaction solution after a polymerization reaction of a vinylpyrrolidone polymer or a dried product of a vinylpyrrolidone polymer in a solvent. To do. The vinylpyrrolidone polymer content of the vinylpyrrolidone polymer-containing solution is not particularly limited, but is preferably 5 to 50% by weight, more preferably 10 to 40% by weight.

  In the present invention, in the step of drying the solution containing the vinylpyrrolidone polymer using a heating surface contact-type dryer, cooling is performed while flowing an inert gas in the dried product cooling process line, and the cooled vinylpyrrolidone heavy is cooled. The coalescence is stored tightly in an atmosphere with an oxygen concentration of 5% or less.

  The cooling process line is preferably a shielded space such as a pipe or a tunnel, and is blocked from outside air except for the entrance and exit.

  Since the high temperature vinylpyrrolidone polymer absorbs the atmosphere during cooling, flowing an inert gas into the atmosphere in the cooling line prevents the vinylpyrrolidone polymer from absorbing oxygen, and lowers the K value during subsequent storage. Can be suppressed.

  The oxygen concentration in the atmosphere is preferably 5% or less by flowing an inert gas. More preferably, it is 1% or less.

  The heating surface contact dryer is a device heated by a heat medium, that is, a device for drying by heating the material by heat conduction from the heating surface, and the heating surface is fed by a raw material supply device such as a liquid feed pump. By supplying a vinylpyrrolidone polymer-containing solution and applying the solution with a pressure roll, a dried product of the vinylpyrrolidone polymer is obtained on the heating surface.

  A specific example of the heating surface contact-type dryer is a drum dryer, and any of a single drum dryer, a double drum dryer, and a twin drum dryer can be used.

  In these drum dryers, the vinylpyrrolidone-based polymer-containing solution is applied in a thin film on the surface of a rotating drum heated from the inside by steam or other heat medium, dried during one rotation, a doctor knife, etc. The scraping device (scraper) of the above is used to scrape dry matter. The dried product thus scraped is processed into various shapes such as a sheet shape, a ribbon shape, a rod shape, and a powder as necessary.

  FIG. 1 is a schematic cross-sectional view showing an outline of an example of a single drum dryer and its peripheral devices. In these drawings, reference numeral 1 is a heating drum, 1a is a heating surface, 2 is a scraper, 3, 4 and 5 are pressure rolls, 6 is a liquid feed pump, 7 is a liquid feed line, and 8 is a peeled dried product. Show. In these apparatuses, the vinylpyrrolidone-based polymer-containing solution supplied from the liquid feed pump 6 via the liquid feed line 7 is applied to the heating surface 1a of the heating drum by the pressure-bonding rolls 3, 4, and 5, and the dried product 8 is obtained. It is peeled off by the scraper 2. In addition, although these figures show the case where there are three crimping rolls, the present invention is not limited to this, and there may be one or four or more.

  In addition, the oxygen concentration as used in the field of this invention means the absolute amount of oxygen which occupies in the gaseous volume of unit volume. For example, in the above, the oxygen concentration is the ratio of the volume occupied by oxygen in the cooling line at normal pressure to the cooling line volume. The oxygen concentration can be easily measured with a commercially available oxygen concentration meter such as a galvanic cell diffusion type or a zirconia sensor type.

  Next, the handling method in the case of grind | pulverizing a vinyl pyrrolidone polymer is demonstrated.

  In this method, a vinylpyrrolidone polymer powder is obtained by pulverizing a vinylpyrrolidone polymer while introducing an inert gas from the inlet through a pulverizer equipped with an inlet for introducing gas into the pulverizing section. Then, this is sealed in an atmosphere having an oxygen concentration of 5% or less to suppress a decrease in K value.

  FIG. 2 is a schematic cross-sectional view showing an example of the structure of a pulverizer that can be used in the present invention. Reference numeral 11 denotes a raw material supply port, 12 denotes an intake port, 13 denotes a pulverizing unit, and 14 denotes a take-out port. The raw material (here, the vinyl pyrrolidone polymer before pulverization) is supplied from the raw material supply port 11 as indicated by the white arrow, pulverized by the pulverization unit 13, and taken out from the take-out port 14 as indicated by the arrow. An intake port 12 is provided in front of the pulverization unit 13 so that an arbitrary gas can be fed into the pulverization unit 13.

  The molecular chain is broken at the time of pulverization of the vinyl pyrrolidone polymer, and it is considered that the radical K causes a decrease in K value due to the radical, but by introducing an inert gas into the pulverization atmosphere, the oxygen of the vinyl pyrrolidone polymer Absorption is prevented, and a decrease in K value during subsequent storage is suppressed. The bulk specific gravity is preferably 0.4 g / ml or more. When the bulk specific gravity is small, the oxygen is easily absorbed when oxygen is present in the atmosphere, leading to a decrease in the K value.

  The pulverizer used in this method is not particularly limited, and a commonly used pulverizer such as a hammer mill, a pin mill, a feather mill, a ball mill, a mortar mill or the like is used, and a hammer mill and a pin mill are particularly preferably used.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[Example 1]
As shown in FIG. 1, a single drum dryer having a heating drum 1 having a diameter of 1.0 m and a width of 2.0 m (drum heating area 6 m ² ) is provided with clearances 30, 30 cm in diameter from the heating rolls. Were set at three locations so that the thickness was 0.3 mm, 0.3 mm, or 0.1 mm. Furthermore, the scraper 2 was attached. After introducing steam into the heating drum 1 and setting the heating surface 1a of the heating drum to 140 ° C., the heating drum is rotated at a constant speed of 1 rpm, and the peripheral speed of the outer periphery of the crimping roll is set to the circumference of the outer periphery of the heating drum. The pressure-bonding roll was rotated so as to be fast. Pittskol K-90L (Daiichi Kogyo Seiyaku Co., Ltd.) K value 93.0 was supplied to the three pressure-bonding rolls by the liquid feed pump 6 at 50 kg / hr to obtain a sheet-like dried product 8. The dried sheet was cooled in a cooling line equipped with an oxygen sensor while purging nitrogen so that the oxygen concentration was 4%. Subsequently, it was sealed and stored at 60 ° C. for 3 months with an oxygen concentration of 4%.

[Example 2]
A sheet-like dried product was obtained in the same manner as in Example 1, followed by pulverization with a pulverizer (AP-1 manufactured by Hosokawa Micron Co., Ltd.), followed by hermetically storing in an oxygen concentration of 4% (60 ° C., 3 months). However, the pulverizing atmosphere of the dried sheet was adjusted to an oxygen concentration of 4% by nitrogen purge.

[Example 3]
A sheet-like dried product was obtained in the same manner as in Example 1 except that the oxygen concentration in the cooling step was changed to 0.8%. Except that, it was pulverized in the same manner as in Example 2 and stored in a sealed state.

[Comparative Example 1]
A sheet-like dried product was obtained in the same manner as in Example 1 except that the sheet-like dried product was cooled in the air, and stored under the same conditions.

[Comparative Example 2]
A powder was obtained in the same manner as in Example 2 except that pulverization was performed in the air, and the powder was stored under the same conditions.

Viscosity of each of the above samples is measured immediately before sealed storage and after sealed storage (60 ° C., 3 months), and the K value is calculated from the following formula using the measured viscosity. ΔK) expressed by the equation was examined, and further evaluated according to the following criteria. The results are shown in the table.

  Here, C represents the number of grams in 100 ml of the solution, and ηrel represents the viscosity of the solution with respect to the solvent.

ΔK = [(K value of sample immediately before sealed storage) − (K value of sample after sealed storage)]
Evaluation: No change… ◎
Less than 1.0… ○
1.0 or more

  The handling method of the present invention can be applied to vinylpyrrolidone polymers used for various purposes, but is particularly preferably used for vinylpyrrolidone polymers for viscosity modifiers.

It is a schematic cross section which shows the heating surface close | contact type dryer (single drum dryer) used in the Example of this invention. It is a schematic cross section which shows the outline of the structure of the grinder which can be used by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heating drum 1a ... Heating surface 2 ... Scraper 3, 4, 5 ... Crimp roll 6 ... Liquid feed pump 7 ... Liquid feed line 8 ... Dry matter 11 ... Raw material supply port 12 ... Intake air Mouth 13 …… Crushing part 14 …… Removal port

Claims (2)

The solution containing the vinylpyrrolidone polymer is dried using a heated surface contact dryer to form a sheet ,
The dried sheet-like vinylpyrrolidone polymer is cooled while flowing an inert gas in a cooling process line which is a pipe-shaped or tunnel-shaped shielded space and is blocked from outside air except for the entrance and exit .
A method for handling a vinyl pyrrolidone polymer, comprising: sealing the cooled vinyl pyrrolidone polymer in an atmosphere having an oxygen concentration of 5% or less. The cooled vinylpyrrolidone polymer is pulverized while introducing an inert gas from the intake port in a pulverizer equipped with an inlet for introducing gas into the pulverization section, and is made into a vinylpyrrolidone polymer powder,
The method for handling a vinyl pyrrolidone polymer according to claim 1, wherein the vinyl pyrrolidone polymer in powder form is stored tightly in an atmosphere having an oxygen concentration of 5% or less.

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