JPS61126113A - Production of partially hydrolyzed polyacrylamide polymer - Google Patents

Abstract

PURPOSE:To produce the titled finely powdered polymer efficiently, by adjusting the pH of an aqueous solution of an acrylamide-based monomer mixture to a specified value and partially hydrolyzing the amide groups simultaneously with the polymerization of the monomer. CONSTITUTION:A caustic alkali (e.g., NaOH) and a polybasic acid (salt) (e.g., boric acid) are added to an aqueous solution containing 10-50wt% monomer mixture of 50-100wt% acrylamide and 50-0wt% water-soluble vinyl monomer copolymerizable therewith (e.g., acrylic acid) to adjust its pH to 8.5-10.0. This aqueous solution is emulsified in an organic solvent (e.g., toluene) containing a dispersant or an emulsifier (e.g., sorbitan monolaurate). The formed emulsion is subjected to reversed phase suspension or emulsion polymerization at a temperature of 40 deg.C to the b.p. of the organic solvent for 2-8hr in the presence of a polymerization initiator and at the same time to the partial hydrolysis of the amide groups. The product is spray-dried to obtain the titled polymer having a degree of polymerization >=10,000, a degree of hydrolysis of amide groups >=1mol% and an average particle diameter <=200mum.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention enables the production of partially hydrolyzed polyacrylamide polymers, which are used for various purposes such as flocculants, cleaning bilges, and granulation base materials, by a simple operation. The present invention relates to a method for efficiently producing powder-form products.

[Conventional technology]

Various production methods have been proposed for partially hydrolyzed polyacrylamide.

For example, as a method in which polyacrylamide is first produced by reverse phase suspension polymerization and then partially hydrolyzed by adding an alkali,
There are No. 04903 and No. 56-104904. However, in the method of JP-A-51-41090, since an aqueous alkali solution is directly added after the polymerization is completed, the emulsion is likely to break and lumps are often formed, thus requiring a pulverization step. Also, JP-A-56-1049
The methods of No. 03 and No. 56-104904 are improved methods of the above production method, but since oil-in-water emulsifiers and alcohols are used together, a step of recovering these is required after production, resulting in poor workability. The disadvantage is that it decreases.

On the other hand, as a method for hydrolyzing at the same time as polymerization, methods of Japanese Patent Publications No. 52-45753 and No. 53-3431 have also been proposed. However, since these methods are essentially based on aqueous solution polymerization, when attempting to obtain a finely powdered polymer, it is necessary to crush the dried polymer, and this pulverization process causes deterioration of the polymer. (reduction in molecular weight and insolubilization) is unavoidable. Furthermore, within the molar ratio range of alkali and boric acid described in the specifications of these patents, the pH of the aqueous monomer solution exceeds 10, so when an azo initiator is used, the induction period becomes extremely long. There is a problem that polymerization cannot actually be started.

[Problem that the invention seeks to solve]

Therefore, an object of the present invention is to provide a method for efficiently producing finely powdered partially hydrolyzed polyacrylamide without requiring complicated steps and without causing deterioration of the polymer. be.

Furthermore, the present invention provides a production method that allows smooth polymerization even when an azo initiator is used, and allows hydrolysis to proceed simultaneously with polymerization.

[Means for solving problems]

In the present invention, when reverse phase suspension polymerization or reverse phase emulsion polymerization is adopted as the polymerization method of monomers, and when the pH of the monomer aqueous solution is adjusted to 8.5 to 10.0, polymerization and hydrolysis occur. This was based on the knowledge that the process proceeds simultaneously and that a finely powdered polymer can be easily obtained.

That is, the present invention provides a monomer aqueous solution for polymerizing an aqueous solution containing acrylamide alone or a mixture of acrylamide and a water-soluble vinyl monomer copolymerizable therewith by reverse phase suspension polymerization or reverse phase emulsion polymerization. The present invention provides a method for producing a partially hydrolyzed polyacrylamide polymer, which comprises adjusting the pH of the polyacrylamide polymer to 8.5 to 10.0 to partially hydrolyze the amide group simultaneously with polymerization.

The monomer used in the present invention is acrylamide or a mixture of acrylamide and a water-soluble vinyl monomer copolymerizable therewith. Such copolymerizable monomers include acrylic acid methacrylic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid or salts thereof, or methacrylamide, dimethylacrylamide, acrylonitrile, hydroxyethyl acrylate or methacrylate. etc., or a mixture of two or more thereof, and the amount of acrylamide is 50 to 99% by weight (hereinafter abbreviated as %).
It is recommended that the mixture be within the range of . Further, it is desirable that the monomer concentration in the monomer aqueous solution is 10 to 50%, preferably 15 to 40%.

In the present invention, the pH of the monomer aqueous solution is 8.5 to 1.
It is necessary to adjust the pH to 0.0, and various known methods can be used to adjust the pH to this level. , is preferable from the viewpoint of promoting polymerization and hydrolysis. Examples of the caustic alkali used here include caustic soda and caustic potash, and the hydrolysis rate can be adjusted by adjusting the amount of these added. As the polybasic acid, boric acid, phosphoric acid, oxalic acid, citric acid, or a mixture thereof can be used, and the pH of the monomer aqueous solution is preferably adjusted to 8.5 to 10.0 depending on the amount of the polybasic acid added. , 9.0~
Adjust to 10.0. It is also preferable to adjust to the above p)l by using a salt such as an alkali metal salt or an ammonium salt of the polybasic acid alone or in combination with a caustic alkali and/or a polybasic acid. In addition, the pH of the monomer aqueous solution is
If the pH value exceeds 10.0, the induction period for the polymerization reaction becomes so long that it becomes virtually impossible to initiate the polymerization, and if the pH value is less than 8.5, the hydrolysis of acrylamide does not proceed.

The amount of polybasic acid required to adjust the pH of the monomer aqueous solution to 8.5 to 10.0 varies depending on the type of polybasic acid used and the type of copolymerization monomer. For example, when boric acid is used, caustic The amount is preferably in the range of 1.2 to 3.0 mol based on the alkali.

In the present invention, it is essential to perform reverse-phase suspension polymerization or reverse-phase emulsion polymerization, and the polymerization initiator used for this removal is as follows:
Azo initiators are preferred since they do not impair the water solubility of the resulting polymer. In order to perform reverse phase suspension polymerization, 2,2'-azobis(iso7'thi++,)S,
Noki 11d64# S Q Re-Yashibis (N
, N''-dimethyleneisobutyramidine hydrochloride), 2.
Examples include 2'-azobis(N,N'-dimethyleneisobutyramidine), 4.4''-azobis(4-cyanovaleric acid), and 2,2°-azobis(imbutyramidine hydrochloride). Or 2,2゛-azobis (N,
Preferably, N'-dimethyleneisobutyramidine hydrochloride) is used. In addition, in order to perform reverse phase emulsion polymerization, 2.
2'-azobis(isobutyronitrile), 2.2'-azobis(2,4-dimethylvaleronitrile), 2.2'
-azobis(2-methylbuty(lonitrile), 1,1
”-azobis(1-cyclohexanecarbonitrile),
2.2'-Azobis(2,44-)limethylpenkune)
2,2"-azobis(imbutyronitrile) or 2,2°-azobis(2,4
-dimethylvaleronitrile) is preferably used. The amount of these initiators used is 0.00 per monomer.
It is desirable to use it in a range of 5 to 0.5%.

The organic solvent used for performing the reversed-phase suspension polymerization or reversed-phase emulsion polymerization of the present invention includes aliphatic or alicyclic hydrocarbons such as n-hebutane, n-hexane, heptane, octane, and cyclohexane, and benzene. Examples include aromatic hydrocarbons such as toluene and xylene, and the amount used is preferably 0.5 to 5 times the weight of the monomer aqueous solution.

In addition, as a dispersant or emulsifier used to emulsify an aqueous monomer solution in an organic solvent in a water-in-oil type, sorbitan monoesters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monooleate are used. , sorbitol EO adduct (P=
1 to 3) monostearate or monoisostearate, E O adduct of nonylphenyl ether (P =
1 to 8), glycerin monostearate, and the like. The amount of these emulsifiers used is preferably 0.1 to 5% by weight based on the organic solvent. Furthermore, among the above compounds,
EO means ethylene oxide, and P indicates the average number of added moles of ethylene oxide (the same applies below).

The polymerization temperature can be set to any temperature from 40°C to the boiling point of the organic solvent, but in order to shorten the polymerization induction period to allow the polymerization to proceed smoothly and not to significantly reduce the molecular weight of the resulting polymer. The polymerization is preferably carried out at 50 to 70°C.

Further, the polymerization time is usually 2 to 8 hours, preferably 3 to 6 hours. Hydrolysis proceeds smoothly due to the heat generated during polymerization, but in some cases, after the completion of the polymerization reaction, hydrolysis can be further progressed by aging at the reflux temperature of the organic solvent.

Fine powder with an average particle size of 200 μm or less can be produced by spray-drying the dispersion of the aqueous polymer solution obtained by polymerization, or by adding a solvent such as methanol, ethanol, or acetone and drying after dehydration. It is possible to ask a polymer of the form ().

By the above production method, a partially hydrolyzed polyacrylamide-based polymer having a degree of polymerization of 10,000 or more and a hydrolysis rate of amide groups of 1 mole or more is usually produced in +7 days. -2
[Effects of the Invention] According to the present invention, the deterioration of the acrylamide polymer obtained by aqueous solution polymerization does not occur when the polymer is pulverized, and it is possible to carry out reverse-phase suspension or emulsion polymerization. Partially hydrolyzed acrylamide-based polymers can be efficiently obtained in the form of fine powder without the need for the formation of lumps that occur when alkali is added later, and without the need for special measures to avoid such lumps.

The partially hydrolyzed acrylamide polymer in the form of fine powder, which is covered by the present invention, can of course be used for well-known purposes such as flocculants, but furthermore, taking advantage of its characteristics, it can be used in powder form. , and is soluble in water during use, and is effectively used as an additive for compositions that require relatively rapid dissolution. Examples of such uses include the bilgoo component of granular detergents, or the patent application filed in 1973.
Examples include the additive for granulating a quaternary ammonium salt compound as a granular detergent composition described in No. 9-125365.

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Example 1 50 g of acrylamide, 2 g of caustic soda, and 5 g of boric acid were dissolved in 150 g of ion-exchanged water (the pH of this aqueous solution was 9.2). Next, 1 mj2 of an aqueous solution prepared by dissolving 3 g of 2.2'-azo-bis(isobutyramidine hydrochloride) in ion-exchanged water to obtain 5'Omβ was added thereto. This solution was added to a solution of 6 g of sorbitan monostearate dissolved in 800 g of n-hexane at 40°C in a 2J2 glass reactor equipped with a stirrer, a reflux condenser, and a nitrogen inlet tube, and then stirred. , Nitrogen was introduced through a nitrogen inlet tube, and the atmosphere was replaced with nitrogen at 40° C. for 15 minutes.

Then, the temperature was raised to 65°C to start polymerization. After polymerizing at 65°C for 5 hours, it was cooled and n-
After removing hexane, it was dispersed in 2 Il of methanol, filtered, and further dried in 500 ml of methanol.
The polymer was separated by filtration and dried to obtain a polymer. Yield: 48.5 g
Met. Obtained point 1l-p
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1 + TsuriJ-Jlwork 0 υ
/”III v) ll&A'lpower /1
The intrinsic viscosity ([η]) measured in a solution of % L'Ji -NO/uQ IN nitric acid at 25°C was 7.8, and the hydrolysis rate determined by colloid titration was 5.2 mol%. . In addition, the colloid titration was carried out by the following method.

Precisely weigh approximately 0.1 g of the colloid titration product and dissolve it in ion-exchanged water to make 100 mJ2. 200ml of this solution
rrl in a beaker, add 100ml of ion-exchanged fishing rod, add monoethanolamine, and adjust the pH to about 1.
Adjust to 0.5. Then, 10 ml of '/2[10N ~ methyl glycol chitosan solution] is added, and the mixture is titrated with '/400 N-polyvinyl potassium nitrate solution using toluidine blue as an indicator. The end point of the titration was the point at which the solution changed color from blue to reddish-purple. A blank test was conducted without separately adding an aqueous solution of the produced polymer, and the hydrolysis rate was calculated from the difference between the blank and the titration value.

Examples 2-3 and Comparative Examples 1-2 The amounts of caustic soda and boric acid used are shown in Table 1. 1st day - 1st day - 1st month 1) ILL, l'-11 funeral V-exit was carried out.Measurement value of pH of monomer aqueous solution and obtained polymer The analytical values of the properties are summarized in Table 1.

The properties of the polymer were also measured in the same manner as in Example 1.

Example 4 47.5 g of acrylamide, 2.5 g of sodium styrene sulfonate, 2 g of caustic soda, and 2.5 g of phosphoric acid were dissolved in 120 g of ion-exchanged water (the pH of this aqueous solution was 9).
．． 5). Next, 3 g of 2,2''-azobis(isobutyramidine hydrochloride) was dissolved in ion-exchanged water to make 50 m! of an aqueous solution of 1 mj29+-S +-; Police Station) Roku'heko
I++1shilu I小s /Ju Qry O-ri 1 the 1 person λ ``Bird'' Ding] 栖1 Beh Sea 111
17 In a 2β glass reactor equipped with a nitrogen inlet tube, 6 g of monostearate of sorbitol EO adduct (P = 2) was added to a solution of 6 g of monostearate of sorbitol EO adduct (P = 2) dissolved in 800 g of n-hexane at 40 °C. Then, while stirring, nitrogen was introduced through a nitrogen inlet tube, and the atmosphere was replaced with nitrogen at 40° C. for 15 minutes. then 6
Polymerization was started by raising the temperature to 5°C. After polymerizing at 65° C. for 5 hours, it was cooled, and the resulting dispersion was spray-dried under reduced pressure to obtain a polymer. Yield was 45g. The obtained polymer was a fine powder with an average particle size of 60 μm, and the intrinsic viscosity measured at 25° C. in an IN sodium nitrate solution was j7.
1. The hydrolysis rate of the acrylamide moiety calculated by colloid titration was 5.5 mol%.

Practical hm example 5 Aqueous solution 22 in which 48 g of acrylamide and 2 g of sodium 2-acrylamide-2-methylpropanesulfonate were dissolved.
．． 16g (prepared by dissolving 1.81g of commercially available 2-acrylamido-2-methylpropanesulfonic acid and 0.35g of caustic soda in 20g of ion-exchanged water), 2g of caustic soda and 5g of boric acid dissolved in 130g of ion-exchanged water. (The p++ of this aqueous solution was 9.6). Next, 1 g of 2.2'-azobis(N,N'-dimethyleneisobutyramidine hydrochloride) was dissolved in ion-exchanged water.
0mf! 1 mf of aqueous solution! was added to this. This solution was mixed with 7 g of sorbitan monostearate in 700 g of cyclohexane in a reactor similar to that of Example 1.
It was added to the solution dissolved at 40° C., nitrogen was introduced through a nitrogen introduction tube while stirring, and the mixture was replaced with nitrogen at 40° C. for 15 minutes. Next, the temperature was raised to 60°C to start polymerization. After polymerizing at 60°C for 4 hours, cooling, removing cyclohexane by decantation, dispersing in 2β methanol,
The polymer was separated by filtration, and then dehydrated in methanol at 500 mN, filtered, and dried to obtain a first class polymer. Yield was 47.8 g. The obtained polymer was a fine powder with an average particle size of 40 μm, the intrinsic viscosity measured at 25°C in IN sodium nitrate solution was 7.6, and the hydrolysis rate of acrylamide calculated by colloid titration was 49 mol%. ,Ta. The hydrolysis rate was calculated on the assumption that sodium 2-acrylamide-2-methylpropanesulfonate was not hydrolyzed.

Example 6 50 g of acrylamide, 2.5 g of caustic soda, and 5 g of boric acid were dissolved in 150 g of ion-exchanged water (the pH of this aqueous solution was 9.7). This solution was mixed with 20 g of sorbitan monoole, 0.06 g of azobisisobutyronitrile, and 80 g of cyclohexane in the same reactor as in Example 1.
0g was dissolved at 40°C, nitrogen was introduced through a nitrogen inlet tube under stirring, and the atmosphere was replaced with nitrogen at 40°C for 15 minutes.

Then, the temperature was raised to 65°C to start polymerization. After polymerizing at 65°C for 4 hours, the temperature was raised to the reflux temperature of cyclohexane, aged for 2 hours, and then cooled. The obtained dispersion was
2! The polymer was dispersed in methanol, separated by filtration, further dehydrated in methanol (11), separated by filtration, and dried to obtain a polymer.

Yield was 45.7 g. The degraded polymer is a fine powder with a particle size of 5-10 μm, has an intrinsic viscosity of 6.9 measured at 25°C in a 1>7 sodium nitrate solution, and a hydrolysis rate of 5.6 mol% determined by colloid titration. Met.

Claims (5)

[Claims] (1) When polymerizing an aqueous solution containing acrylamide alone or a mixed monomer of acrylamide and a water-soluble vinyl monomer copolymerizable therewith by reverse-phase suspension polymerization or reverse-phase emulsion polymerization, the pH of the monomer aqueous solution is set to 8. 5 to 10.0, and partially hydrolyzing the amide group at the same time as polymerization. (2) The manufacturing method according to claim (1), in which an azo-based initiator is used as a polymerization initiator. (3) The manufacturing method according to claim (1), in which a caustic alkali and a polybasic acid are used to adjust the pH of the monomer aqueous solution. (4) The manufacturing method according to claim (1), in which a polybasic acid salt is used to adjust the pH of the monomer aqueous solution. (5) The manufacturing method according to claim (3) or (4), wherein the polybasic acid is at least one selected from the group of boric acid, phosphoric acid, oxalic acid, and citric acid.