JP2874740B2 - Process for producing powdery 2-pyrrolidone polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a 2-pyrrolidone polymer useful as a fiber or plastic material in powder form.

[0002]

2. Description of the Related Art It has been disclosed in Japanese Patent Publication No. 47-26678 and U.S. Pat. It is known from US Pat. No. 3,174,951. Further, as a main polymerization method, a bulk polymerization method and a suspension polymerization method in which polymerization is performed in the presence of an aprotic solvent that does not adversely affect the polymerization reaction are known.

In the bulk polymerization of 2-pyrrolidone, since the polymerization temperature is sufficiently lower than that of the produced 2-pyrrolidone polymer, the polymer formed during the polymerization reaction is precipitated, and thereafter the polymerization proceeds in a solid state. , 2-pyrrolidone polymers are obtained in hard lumps. Therefore, after completion of the polymerization reaction, it becomes difficult to remove the 2-pyrrolidone polymer from the reaction tank, or it becomes difficult to remove unreacted 2-pyrrolidone or a basic polymerization catalyst residue contained in the polymer. The temperature of the polymer mixture becomes non-uniform due to the heat of polymerization, resulting in 2
-It has a drawback that it is difficult to control the molecular weight of a pyrrolidone polymer, and is considered to be a polymerization method having many problems in industrialization. Therefore, many studies have been made on the assumption that the suspension polymerization method having relatively few defects as mentioned in the bulk polymerization is a polymerization method suitable for industrialization.

For example, Japanese Patent Publication No. 37-6746 discloses a method of obtaining a powdery 2-pyrrolidone polymer in a saturated hydrocarbon in which 2-pyrrolidone is not dissolved in the presence of an alkali metal salt of a fatty acid such as sodium stearate. Is disclosed. In this method, most of the generated 2-pyrrolidone polymer adheres to the polymerization tank wall or the stirrer or becomes a large lump, and only a part of the polymer becomes a powder, which is substantially different from the bulk polymerization. In addition, the relative viscosity, which is a measure of the molecular weight of the 2-pyrrolidone polymer formed as described in the examples, is not very high.

JP-B-48-42719 discloses a powdery 2-pyrrolidone polymer in a saturated hydrocarbon in which 2-pyrrolidone is not dissolved in the presence of a nonionic surfactant such as a block polyether of ethylene oxide and propylene oxide. Are disclosed. This method produces a large mass of 2-pyrrolidone polymer during polymerization,
Many of the polymers adhered to the polymerization tank walls and the stirrer, making it difficult to take them out of the polymerization tank and taking time to remove unreacted monomers. Further, the relative viscosity of the obtained 2-pyrrolidone polymer is not high.

Japanese Patent Publication No. 57-31742 discloses a method of obtaining a powdery 2-pyrrolidone polymer by adding an acid to the polymerization mixture before the formed 2-pyrrolidone polymer is aggregated during the polymerization reaction. ing. In this method, when an acid is added at a time when the polymerization yield is as low as 10 to 15%, a powdery polymer may be obtained. However, in this case, since the polymerization yield is low, the productivity is low. In addition, when the polymerization yield is 20% or more, it is difficult to powder the polymer even if an acid is added, and most of the polymer becomes a lump, which makes it difficult to remove the polymer from the polymerization tank. It takes a long time to remove the reactive monomer, has a disadvantage that a part of the polymer adheres to the polymerization tank wall or a stirrer, and the obtained polymer has a relatively low relative viscosity.

In Japanese Patent Publication No. Sho 62-61054, the first step of the polymerization reaction is to carry out bulk polymerization to a polymerization yield of 10%, and then, in the second step, the produced polymer and an insoluble liquid dispersant are mixed and suspended. A method is disclosed in which polymerization is carried out, and the polymerization reaction proceeds to obtain a powdery 2-pyrrolidone polymer. This method involves two stages of polymerization reaction and is disadvantageous in the process, and it has been difficult to obtain a powdery polymer in which most of the polymer adheres to the inner wall of the polymerization tank.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a powdery 2-pyrrolidone polymer which has a high relative viscosity and is industrially easy to handle.

That is, an object of the present invention is to provide 2-pyrrolidone with 2-pyrrolidone in suspension polymerization by the action of carbon dioxide or sulfur dioxide as a basic polymerization catalyst and a polymerization initiator in an aprotic solvent. And that the compound represented by the chemical formula (2) is present in an amount of 0.1 to 5% by weight.

Embedded image (Where R is a hydrocarbon group having 10 to 30 carbon atoms and M is a divalent metal).

As the basic polymerization catalyst used in the present invention, compounds generally used in anionic polymerization of lactams can be used, such as alkali metals such as sodium, potassium and lithium; hydroxides and hydrides of alkali metals; Alcoholates, oxides and salts such as potassium hydroxide, sodium hydride, potassium methylate, sodium methylate, sodium pyrrolidone, potassium pyrrolidone;
Basic organometallic compounds such as lithium alkyl, potassium alkyl, sodium alkyl, and aluminum alkyl; alkali metal aryls such as sodium phenyl and sodium naphthalene; Grignard reagents such as butylmagnesium bromide and the like; and quaternary bases represented by the chemical formula (3) and so on.

Embedded image (Where R ₁ , R ₂ , and R ₃ are lower alkyl and R ₄ is an alkyl, aryl, or aralkyl group)

Of these, potassium hydroxide, potassium methylate, sodium methylate, sodium pyrrolidone and potassium pyrrolidone are particularly preferred. When using potassium hydroxide, potassium methylate, sodium methylate, etc., mix excess 2-pyrrolidone and these compounds prior to polymerization, and use after removing water and alcohols by-produced by the reaction. Is preferred.

The amount of the basic catalyst used in the present invention is 0.1 to 30 mol%, preferably 1 to 20 mol%, per 1 mol of 2-pyrrolidone. If the amount used is less than the lower limit or more than the upper limit, the polymerization yield and the relative viscosity of the polymer are undesirably low.

As the polymerization initiator used in the present invention, carbon dioxide or sulfur dioxide is preferably of high purity, but any industrially available carbon dioxide or sulfur dioxide can be used as long as it does not contain impurities that inhibit polymerization. The amount of carbon dioxide or sulfur dioxide used is 10 to 90 mol% based on 1 mol of the basic catalyst,
Preferably it is 20 to 60 mol%. If the amount of carbon dioxide or sulfur dioxide is out of the above range, the polymerization rate becomes low, and the relative viscosity of the obtained polymer becomes low, which is not preferable.

It is preferable to use carbon dioxide or sulfur dioxide alone as the polymerization initiator, but in the present invention, other known polymerization initiators can be used together with carbon dioxide or sulfur dioxide. Other polymerization initiators that can be used together with carbon dioxide or sulfur dioxide include lactam acyl compounds such as acetylpyrrolidone and acetylcaprolactam, acyl compounds such as adipoylbiscaprolactam, acid anhydrides such as acetic anhydride and benzene anhydride, and toluene diisocyanate. Carbamide compounds such as 1,6-hexamethylenebiscarbamidocaprolactam, 1- (1-pyrolin-2-yl) -2-pyrrolidone, 1- (1-azacyclohepta-1-en-2)
-Yl) -2-pyrrolidone, 6-caprolactam-1-
(1-azacyclopenta-1-en-2-yl) -1-
There are quaternary ammonium salts such as aza-2-oxocyclopentane, tetramethylammonium chloride and the like, and reaction products of these polymerization initiators, basic polymerization catalysts and the like.

These polymerization initiators can be used in an amount smaller than the amount of carbon dioxide or sulfur dioxide used. Further, the main polymerization is largely affected by moisture, and it is preferable to use 2-pyrrolidone having a moisture content of 0.1 wt% or less by a method such as distillation.

The aprotic solvents used in the present invention include cyclic ethers such as tetrahydrofuran and dioxane, linear ethers such as ethyl ether and isopropyl ether, hexane, benzene, toluene, xylene, dimethylformamide and hexamethylphosphoramide. , Dimethylacetamide, dimethylsulfoxide,
Examples include dimethylsulfolane and N-methylpyrrolidone. It is preferable to reduce the water content of these by distillation before use. The amount of the aprotic solvent used is 0.5 to 5 times by volume, preferably 2 to 4 times by volume the total amount of pyrrolidone used for the polymerization. When the amount is less than the lower limit, it is difficult to produce a good powder, and when the amount is more than the upper limit, there is no difference in effect, but it is not preferable from the viewpoint of productivity, for example, it takes time to separate the polymer from the polymer.

M of the compound represented by the formula (1) used in the present invention is calcium, magnesium, aene,
A divalent metal such as barium or strontium, wherein R is a hydrocarbon group having 10 to 30 carbon atoms, and among them, a saturated hydrocarbon is preferable. Specific examples include barium laurate, calcium myristate, aene myristate, calcium palmitate, magnesium palmitate, aene palmitate, calcium stearate, magnesium stearate, aene stearate, calcium linoleate, magnesium linoleate, calcium behenate and so on.

The amount of the compound represented by the formula (1) is 0.1 to 5% by weight, preferably 1 to 3% by weight, based on 2-pyrrolidone. If it is less than the lower limit, it is difficult to obtain a good powdery polymer, and if it is more than the upper limit, the relative viscosity of the obtained 2-pyrrolidone polymer becomes low, or the compound represented by the chemical formula (1) is removed from the polymer. It is not preferable because it takes time.

The 2-pyrrolidone polymer of the present invention is prepared by adding a predetermined amount of a basic catalyst to purified substantially anhydrous 2-pyrrolidone (reacting as necessary to remove by-products). Carbon dioxide or sulfur dioxide as a polymerization initiator is added to the solution, and the mixture is dispersed in an aprotic solvent in which the compound represented by the chemical formula (1) is dispersed.
It can be obtained by subjecting 2-pyrrolidone to ring-opening polymerization at a temperature of ７０70 ° C. If the temperature is higher than 100 ° C., the polymerization rate becomes extremely slow, which is not preferable.

The addition of carbon dioxide or sulfur dioxide may be carried out in the presence or absence of an aprotic solvent. Carbon dioxide or sulfur dioxide may be added to 2-pyrrolidone containing a basic catalyst at a temperature of 150 ° C. or less, preferably 15 to 150 ° C. 10
It can be implemented relatively easily by blowing a predetermined amount in a temperature range of 0 ° C. The compound represented by the chemical formula (1) may be added before or after blowing carbon dioxide gas or sulfur dioxide. If it is within 20% by weight of the total polymerization composition, it can be copolymerized with γ-butyrolactone, α-piperidone, ε-caprolactam, laurolactam and the like.

[0021]

According to the present invention, when 2-pyrrolidone is subjected to suspension polymerization by the action of a basic polymerization catalyst and carbon dioxide gas or sulfur dioxide as a polymerization initiator in an aprotic solvent, 0.1 to 5 By the presence of the compound represented by the chemical formula (1) in a weight%, a powdery 2-pyrrolidone polymer having a high relative viscosity can be obtained.

Hereinafter, the present invention will be described specifically with reference to examples. Incidentally, the polymerization yield used in Examples and Comparative Examples,
Ηγ (relative viscosity), which is a measure of molecular weight, is a value measured by the following method. The form of the produced 2-pyrrolidone polymer (whether powdery or not) was visually observed.

(1) Polymerization Yield After polymerizing for a predetermined time, the polymer mixture and the aprotic solvent are separated by filtration, and the polymer mixture is put into 10 times or more of hot water (50 to 60 ° C.), Stir and wash for 3 hours. After removing the hot water, add new warm water and repeat the same operation. After performing this operation again, the remaining produced polymer is dried under reduced pressure (about 70 ° C., 24 hours or more), weighed, and calculated by the following equation.

[0024]

(Equation 1)

(2) ηγ (relative viscosity) After completely dissolving 0.5 g of the dried 2-pyrrolidone polymer in 100 cc of m-cresol at room temperature, the mixture was allowed to flow at 30 ° C. using an Ostwald viscometer at a temperature of 30 ° C. (unit: Second) and the value calculated by the following formula.

[0026]

(Equation 2)

Example 1 220 g (2.58 mol) of substantially anhydrous 2-pyrrolidone
l) into a flask equipped with a stirrer and vacuum,
After heating to 65 ° C, 85% pure potassium hydroxide 1
5.52 g (0.235 mol in terms of potassium hydroxide)
Was added thereto to cause a reaction, and the pressure inside the flask was reduced (115 ° C.,
(About 5 mmHg), 24 g of a mixture of by-produced water and 2-pyrrolidone was distilled off, and a 2-pyrrolidone solution containing 10 mol% of calcium pyrrolidone was prepared. Nitrogen gas was introduced into the flask to normal pressure, and the liquid temperature was lowered to 25 ° C. After mixing this solution and 400 g of n-hexane, 4 g of calcium stearate was added and mixed uniformly. Subsequently, 3.5 g of carbon dioxide (0.08 mol, 0.34 mol based on 1 mol of the basic catalyst potassium pyrrolidone) was introduced under stirring at 25 ° C. (about 60 rpm).
The flask was placed in a water bath at 45 ° C. and polymerized for 24 hours under a nitrogen gas atmosphere. After the completion of the polymerization reaction, the polymerization mixture was in a powder form, and no adhesion to the flask was observed. The polymerization mixture and n-hexane were separated by filtration, and the polymerization mixture was sufficiently washed with water to remove unreacted monomers and catalyst residues, and dried under reduced pressure at 70 ° C. for 24 hours. The polymerization yield was 49%, and ηγ was 15.7.

Comparative Example 1 An experiment was carried out in the same manner as in Example 1 except that calcium stearate was not used. At the end of the polymerization reaction, the polymerization mixture was massive and strongly adhered to the inner wall of the flask, and the polymerization mixture could not be taken out without destroying the flask. The polymerization yield was 39%, and ηγ was 6.8.

Comparative Example 2 The same procedure as in Example 1 was carried out except that sodium stearate was used instead of calcium stearate. At the end of the polymerization reaction, most of the polymerization mixture adhered to the inner wall of the flask or the stirring rod or was in a lump, and the amount of the powder was small. The polymerization yield was 34%, and ηγ was 6.2.

Comparative Example 3 A polyoxyethylene polyoxypropylene block polymer (Epan 45) was used instead of calcium stearate.
0, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in the same manner as in Example 1 except that 4 g was used. Most of the polymerization mixture at the end of the polymerization reaction was in a lump or adhered to the inner wall of a flask or a stirring rod, and a small amount of a powdery mixture was obtained. The polymerization yield was 29%, and ηγ was 4.8.

Comparative Example 4 The same procedure as in Example 1 was carried out except that calcium propionate was used instead of calcium stearate. About half of the polymerization mixture at the end of the polymerization reaction adhered to the inner wall of the flask and the stirring rod, and the rest was in the form of powder. It was difficult to remove what had adhered to the inner wall of the flask or the stirring rod. The polymerization yield was 39%, and ηγ was 8.1.

Comparative Example 5 The same procedure was performed as in Example 1 except that the amount of calcium stearate used was changed to 12 g. At the end of the polymerization reaction, most of the polymerization mixture was in the form of powder, and a small amount adhered to the inner wall of the flask or the stirring rod. However, the polymerization yield was 35% and ηγ was as low as 6.9.

Example 2 In place of carbon dioxide gas, 5.1 g of sulfur dioxide (0.08 mol) was used.
1) was carried out in the same manner as in Example 1 except that the polymerization time was changed to 20 hours. At the end of the polymerization reaction, the polymerization mixture was in the form of a powder and did not adhere to a flask or the like.
The polymerization yield was 51%, and ηγ was 8.1.

Examples 3 to 6 Amount of carbon dioxide used, polymerization initiator 1 used in combination with carbon dioxide
(1-pyrrolin-2-yl) -2-pyrrolidone (abbreviation P
The procedure was performed in the same manner as in Example 1 except that the amount of DPD) used and the polymerization temperature were changed to the values shown in Table 1. Table 1 shows the morphology, polymerization yield, and ηγ of the 2-pyrrolidone polymer.

Example 7 200 g of substantially anhydrous 2-pyrrolidone (2.35 mol)
l) into a flask equipped with a stirrer and vacuum,
After heating to 90 ° C., 6.7 g (0.123 mol) of sodium methylate having a purity of 95% was added and reacted.
The by-produced methanol is distilled off, and sodium pyrrolidone 5
A 2-pyrrolidone solution containing mol% was prepared. Nitrogen gas was introduced into the flask to return to normal pressure, and the temperature of the solution was adjusted to 3
After cooling to 5 ° C, 1.5 g of carbon dioxide (0.034
1, 0.23 mol per 1 mol of the basic catalyst sodium pyrrolidone) was introduced and reacted. N-
Hexane 280 g, magnesium palmitate 4 g and N-acetyl-ε-caprolactam 0.33 g were added,
This mixture was polymerized at 35 ° C. for 15 hours at 35 ° C. with stirring under a nitrogen gas atmosphere. The n-hexane was removed by filtration, the obtained polymer mixture was sufficiently washed with water to remove unreacted monomers and sodium, and dried under reduced pressure at 70 ° C. for 24 hours. The obtained 2-pyrrolidone polymer was in a powder form, the polymerization yield was 34%, and ηγ was 10.6.

[Table 1]

Claims (1)

(57) [Claims] When 2-pyrrolidone is subjected to suspension polymerization in an aprotic solvent by the action of a basic polymerization catalyst and carbon dioxide or sulfur dioxide as a polymerization initiator, 2-pyrrolidone has a chemical formula (1) The compound represented by 0.1 to 5
% By weight (Where R is a hydrocarbon group having 10 to 30 carbon atoms and M is a divalent metal). A method for producing a powdery 2-pyrrolidone polymer, characterized in that: