JP3189315B2 - Method for producing N-vinyl carboxylic acid amide polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a suspension polymerization of a mixture of N-vinyl carboxylic acid amide and acrylonitrile.
The relates to a method of obtaining N- vinylcarboxamide polymers, also relates to a method for obtaining a modified product of the polymer to further hydrolyzed to N- vinylcarboxamides polymer. The polymer obtained by the method of the present invention has a high molecular weight, and can be used as a flocculant for dehydrating organic sludge, a drainage improver in the papermaking industry and a filler retention improver.

[0002]

2. Description of the Related Art There are many known methods for polymerizing N-vinyl carboxylic acid amide in the form of an aqueous solution or modifying it (Japanese Patent Publication No. 63-9523). When polymerizing in the form of this aqueous solution, a polymer can be easily obtained,
On the other hand, when a polymer having a high molecular weight is to be produced, the solution becomes extremely viscous, and if the concentration is high, it becomes a hydrated solid. Therefore, it is extremely difficult to use this and to lead to a modification step. Therefore, usually, complicated steps such as drying and granulation of the polymer are required before the modification step.

Further, an aqueous monomer solution is dispersed in a hydrocarbon-based dispersion medium using an oil-soluble polymer dispersion stabilizer such as ethyl cellulose and subjected to suspension polymerization to obtain a granular polymer, which is further hydrolyzed. A method for obtaining a modified product of N-vinylcarboxylic acid amide is known (JP-A-61-141712).

[0004]

However, oil-soluble polymers such as ethyl cellulose used in the method of Japanese Patent Application Laid-Open No. 61-141712 include the following. In addition, it is necessary to further add a surfactant or an alcohol as a hydrophilic substance. 2) The oil-soluble polymer is easily decomposed in the hydrolysis step, is difficult to recover, and is expensive. There was a problem.

[0005]

The inventors of the present invention have conducted intensive studies on the above problems, and have found that
Specific molar ratios of rubonic amide and acrylonitrile
When the mixture is subjected to suspension polymerization, a good granular polymer is obtained even when a specific surfactant is used instead of the oil-soluble polymer, and a modified product of hydrolyzed N-vinylcarboxylic acid amide Was efficiently obtained, and the surfactant used in the polymerization reaction was recovered and found to be sufficiently reusable, and the present invention was reached.

That is, the gist of the present invention is as follows.
₂ = CHNHCOR (wherein R represents a hydrogen atom or a methyl group)
And acrylonitrile in a ratio of 20:80 to 95: 5 (mole
A mixture of the above (2) and (3) in the presence of a hydrocarbon dispersion medium, water and a nonionic surfactant having an HLB of 9 to 20 to produce an N-vinylcarboxylic acid amide polymer. And secondly, a method for producing a modified N-vinylcarboxylic acid amide polymer obtained by modifying the polymer obtained by the production method.

Hereinafter, the present invention will be described in detail. The N-vinylcarboxylic acid amide represented by the general formula CH2 = CHNHCOR (wherein R represents a hydrogen atom or a methyl group) used in the present invention includes N-vinylformamide and N-vinylacetamide. For the purpose of obtaining a modified product of a vinyl carboxylic acid amide polymer, N-
Vinyl formamide is preferred.

In the polymerization of the present invention, a mixture of N-vinylcarboxylic acid amide and acrylonitrile is used.

[0009] N-vinylcarboxylic acid amide (A) and
When copolymerizing Rironitoriru (B), the copolymerization molar ratio of (A) and (B), 2 0: 80 to 95: 5, preferably 30: 70 to 90: 10, more preferably 40:
60-80: Ru 20 der. The raw material vinyl compound is dispersed in a hydrocarbon dispersion medium in the form of an aqueous solution and subjected to suspension polymerization.
The concentration of the aqueous solution of the raw material monomer is polymerized at an arbitrary concentration in the range of 5 to 95% by weight, and preferably 20 to 80% by weight in order to obtain a high molecular weight polymer.

As the hydrocarbon dispersion medium, a hydrocarbon azeotropic with water is preferred. For example, chain saturated hydrocarbons such as n-hexane, n-heptane, n-octane, nonane, decane, undecane and dodecane, a petroleum fraction having a boiling point of 65 to 250 ° C, preferably a petroleum fraction having a boiling point of 80 ° C to 180 ° C, Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene. The dispersion medium is used in an amount of usually 0.5 to 10 times, preferably 1 to 5 times the weight of the aqueous solution of the raw material vinyl compound.

A feature of the present invention resides in that a specific surfactant is used as a dispersion stabilizer in the above suspension polymerization.
The surfactant used in the present invention is HLB (Hydroph).
is a nonionic surfactant having an ilic lipophilic balance of 9 to 20, preferably 12 to 19; polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, molyglyceride, sorbitol alkyl ester, and sucrose. Alkyl esters and the like, and preferably polyoxyethylene alkyl ethers and polyoxyethylene alkyl phenyl ethers. Specifically, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene stearyl ether Compounds such as oxyethylene phenyl ether, polyoxyethylene laurate, polyoxyethylene oleate, polyoxyethylene stearate, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan oleate, and polyoxyethylene sorbitan stearate are exemplified. .

The above surfactant is used in an amount of 0.01 to 5% by weight, preferably 0.05 to 1% by weight, based on the dispersion medium.
Is appropriately selected from the range. A general radical polymerization initiator can be used as the polymerization initiator, but an azo compound is preferable. Particularly preferred are water-soluble azo compounds such as 2,2'-azobis-2-amidinopropane hydrochloride, sulfate and acetate, azobis-N, N'-dimethyleneisobutylamidine hydrochloride, sulfate and Acetates, alkali metal salts and ammonium salts of 4,4'-azobis-4-cyanovaleric acid are exemplified. The radical polymerization initiator is used in an amount of 100 to 10000 ppm, preferably 500 to 5000 ppm based on the weight of the starting vinyl compound.
Used in the ppm range. The method of adding the radical polymerization initiator is not particularly limited, but it is preferable to dissolve the radical polymerization initiator in an aqueous solution containing the raw material vinyl compound, and then disperse the radical polymerization initiator in a hydrocarbon-based dispersion medium for polymerization. Further, in some cases, additives such as ammonium chloride and calcium chloride are used as a polymerization stabilizer. The additive is used in an amount of usually 0.1 to 20% by weight, preferably 1 to 15% by weight, based on all monomers.

[0013] The polymerization temperature is usually 30 to 100 ° C, preferably 50 to 80 ° C. The polymerization time is usually 0.5
10 to 10 hours, preferably 1 to 8 hours. During the polymerization, heat of polymerization is generated, so that the polymerization temperature is usually adjusted by cooling the polymerization system so that the polymerization temperature is kept within the above range. To carry out the polymerization, the dispersion medium containing the surfactant is maintained at the polymerization temperature, and in a nitrogen gas stream,
A method in which an aqueous monomer solution containing a polymerization initiator is added to a dispersion medium with stirring is exemplified, but the method is not particularly limited to the mixing of a monomer, a solvent, and an auxiliary.

The water-containing N-vinylcarboxylic acid amide polymer thus obtained is heated under stirring by using a hydrocarbon-based compound azeotropic with water as a dispersion medium, and dispersed by boiling distillation of water and the hydrocarbon-based dispersion medium. Water is removed in this state, and a powdery N-vinylcarboxylic acid amide polymer can be produced. The polymer does not contain fine powder and usually has a particle size of 0.1 to
It shows a bead shape with a uniform particle size of 3.0 mm, especially about 0.5 to 2.0 mm.

The N-vinylcarboxylic acid amide polymer obtained by the above method may be modified by hydrolysis in water under acidic or basic conditions, or in a hydrophilic solvent such as an alcohol containing water. Examples of the method include hydrolysis, alcoholysis, and the like. Examples of the alcohol used for alcoholysis include alcohols having 1 to 4 carbon atoms, and preferably methanol. Specifically, the part to be modified is the second group of N-vinylcarboxylic acid amide.
A primary amide group, which is a part of an amide and is modified as a result. In the case of a copolymer, a part of the structure of the water-soluble vinyl compound used may be subject to modification.
For example, a nitrile group may be an amide group or a carbosyl group.

For the acidic hydrolysis, any water-soluble monovalent strong acid can be used. For example, hydrogen chloride, hydrogen bromide, hydrogen fluoride, nitric acid, sulfamic acid, methanesulfonic acid, ethanesulfonic acid and the like are exemplified, and hydrogen chloride is particularly preferred. In this case, hydrogen chloride may be introduced into the reaction system in a gaseous state, or may be added as an aqueous hydrochloric acid solution. Any of a water-soluble strong base is used for the basic hydrolysis, and sodium hydroxide, potassium hydroxide and lithium hydroxide are particularly preferable.

The acid and base are preferably used in the form of an aqueous solution, and the concentration thereof can be arbitrarily selected within the range of usually 5% by weight to the concentration of a saturated aqueous solution of an acid or base. In the case of acidic hydrolysis, it is preferable to use a saturated aqueous solution because the higher the concentration of the polymer in the hydrated polymer at the time of the reaction, the faster the denaturation rate. If necessary, the water-containing N-vinylcarboxylic acid amide polymer may be dehydrated by azeotropic distillation of water as a dispersion medium, and then an acid may be added. The amount of the acid used is appropriately used depending on the desired hydrolysis rate, but is usually 1 to 2 times the equivalent of the amide group having the desired hydrolysis rate. The temperature of the acidic hydrolysis is 20 for N-vinylformamide polymer.
To 130 ° C, preferably 60 to 120 ° C, and in the case of an N-vinylacetamide polymer, 50 to 150 ° C, preferably 90 to 130 ° C. It is carried out in a pressurized reaction system as needed.

In the case of basic hydrolysis, the concentration of the polymer in the hydrated polymer during the reaction is preferably 10 to 50% by weight. The amount of the base used is appropriately used according to the target hydrolysis rate, but is usually used appropriately according to the target hydrolysis rate, but is usually 1 to 3 times the equivalent of the amide group having the target hydrolysis rate. It is. The temperature of the basic hydrolysis is 20 ° C to 100 ° C, preferably 50 ° C to 80 ° C for the N-vinylformamide polymer, and 80 ° C to 180 ° C for the N-vinylacetamide polymer. It is carried out in a pressurized reaction system as needed. Basic hydrolysis is easy to crosslink due to impurities in the polymer, but it is prevented by adding one or more compounds selected from ammonia, primary amine and secondary amine as necessary and hydrolyzing. it can. The basic hydrolyzate can be neutralized to form a salt, if necessary. As the neutralizing agent, any of acids can be used, but the same monovalent strong acid as that used for acid hydrolysis is preferable.

If necessary, the neutralized product of the acidic hydrolyzate and the basic hydrolyzate can be made into a powder by solvent dehydration or azeotropic distillation of a dispersion medium with water. Further, since the remaining separated mother liquor contains the recovered surfactant, the surfactant is distilled to remove the hydrocarbon-based dispersion medium by distillation, and is usually concentrated to 80% or more, preferably 95% or more. Collected. The recovered surfactant can be reused in the polymerization reaction.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the invention. Example 1 400 g of toluene as a dispersion medium and polyoxyethylene oleyl ether (Daiichi Kogyo Seiyaku Co., Ltd. product name “Neugen ET140E”) were placed in a 1-liter four-necked flask equipped with a stirrer, a cooling pipe, a dropping funnel and a nitrogen gas introduction pipe. ”, H
(LB = 14.0), and the temperature was raised to 60 ° C. with stirring. Next, 76 g of N-vinylformamide (purity = 93.0%), 53 g of acrylonitrile (purity of 99.5%), 2,2′-azobis-2-amidinopropane dihydrochloride were added in a dropping funnel under a nitrogen gas stream. A solution was prepared by adding water to 0.2 g of salt to make a total amount of 210 g over 3 hours.
The solution was added dropwise to the dispersion medium maintained at a temperature of 0 ° C. Thereafter, the reaction was carried out by stirring at 60 ° C. for 3 hours under a nitrogen gas stream. Next, an azeotropic distillation tube for esterification was attached between the cooling tube and the four-necked flask, the bath temperature was raised to 90 ° C., and water-toluene azeotropic distillation was carried out with stirring to remove water in the polymer. 4
After cooling to 0 ° C., the product was filtered through a nutsier and dried with aeration through toluene. Table 1 shows the shape of the polymer.

Examples 2 to 6 and Comparative Examples 1 to 4 Experiments were carried out in the same manner as in Example 1 except that the type of the dispersion medium and the type of the surfactant were changed as shown in Table 1. Table 1 shows the results.

[0022]

[Table 1]

Example 7 Polymerization was carried out in the same manner as in Example 1 except that 6.4 g of ammonium chloride was used as a polymerization stabilizer in the monomer solution of Example 1. Subsequently, 100 g of the reaction solution was transferred to a 500 ml flask, and 22.0 g of concentrated hydrochloric acid (1.3 times by mol with respect to N-vinylformamide) was added.
Hydrolysis for hours. After cooling to room temperature, 200 ml of a concentrated hydrochloric acid-methanol mixed solution (volume ratio: 1:10) was added, washed with stirring, filtered, and dried under reduced pressure to obtain a powdery polymer having a reduced viscosity of 3.5. The reduced viscosity was measured by immersing 0.1 g of the sample in 100 g of 1N saline at room temperature for 4 hours to dissolve it, and then measuring the temperature at 25 ° C. with an Ostwald viscometer.

Example 8 After polymerizing and hydrolyzing in the same manner as in Example 2, an azeotropic distillation tube for esterification was attached between the cooling tube and the four-necked flask, and the mixture was stirred at a bath temperature of 90 ° C. The water content of the polymer was removed by a water-cyclohexane azeotropic distillation. After cooling to 40.degree. C., the product was filtered through a nutchie to separate the polymer. The remaining separated mother liquor was pumped up at 90 ° C. When the remaining concentrate mainly composed of the surfactant was analyzed by gas chromatography, no decomposition product of the surfactant was found. Further, the same operations as in Examples 1 and 7 were performed except that the recovered surfactant was used, but the obtained polymer showed the same properties as those in Examples 1 and 7.

[0025]

According to the present invention, N-vinylcarboxylic acid amide can be polymerized under a high concentration condition to obtain a powdery bead polymer having an extremely high molecular weight. N
-The vinylcarboxylic amide polymer can be modified under high concentration conditions. Furthermore, it is possible to recycle the surfactant used for the polymerization.

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 26/00-26/02 C08F 2/16-2/20

Claims (4)

(57) [Claims] 1. A compound of the general formula CH ₂ ＣＨCHNHCOR (wherein
R represents a hydrogen atom or a methyl group. N)
-2 of vinyl carboxylic acid amide and acrylonitrile
N: a mixture of 0:80 to 95: 5 (molar ratio) is subjected to suspension polymerization in the presence of a hydrocarbon dispersion medium, water and a nonionic surfactant having an HLB of 9 to 20. −
A method for producing a vinyl carboxylic acid amide polymer. 2. A compound of the general formula CH ₂ ＣＨCHNHCOR wherein
R represents a hydrogen atom or a methyl group. N)
-2 of vinyl carboxylic acid amide and acrylonitrile
A mixture of 0:80 to 95: 5 (molar ratio) was subjected to suspension polymerization in the presence of a hydrocarbon-based dispersion medium, water and a nonionic surfactant having an HLB of 9 to 20 to give N-vinyl carboxylic acid. A method for producing a modified product of an N-vinylcarboxylic acid amide polymer, which comprises obtaining an acid amide polymer and then modifying it. 3. The method according to claim 2, wherein the modified N-vinylcarboxylic acid amide polymer is separated, the dispersion medium is removed, and the recovered surfactant is reused in suspension polymerization. -A method for producing a modified vinylcarboxylic acid amide polymer. 4. The process of claims 1 to 3 surfactant is a polyoxyethylene alkyl ether or polyoxyethylene alkyl phenyl ether.