JP2872831B2 - Dispersant for reversed phase suspension polymerization - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reversed phase comprising a polymer comprising both lipophilic ethylenically unsaturated monomer units and a sugar residue ethylenically unsaturated monomer unit as essential components. The present invention relates to a dispersant for suspension polymerization (hereinafter, abbreviated as a dispersant).

[0002]

2. Description of the Related Art As a method for obtaining a water-soluble ethylenically unsaturated monomer as a spherical particle polymer, an aqueous monomer solution is suspended and dispersed in a hydrophobic solvent to carry out polymerization. The so-called reversed-phase suspension polymerization method is well known, and a dispersant is generally used in such a method. It is the function of the dispersant to keep the monomers to be polymerized in a dispersed state, prevent or reduce the tendency of the polymer particles to agglomerate, and control the particle size.

[0003] Dispersants used in the reverse phase suspension polymerization of water-soluble ethylenically unsaturated monomers include, for example, sorbitan esters (such as sorbitan monostearate and sorbitan monooleate) and ethoxylated fatty acids. Nonionic surfactants such as amides and glycerin fatty acid esters are known. Another group of known dispersants is, for example, allyl (al
It is a high molecular compound such as a maleic anhydride-treated resin having an lyl) group, a carboxyl group-containing polymer having an affinity for an organic solvent, and a lipophilic cellulose derivative. However, when the former group of dispersants is used, the resulting polymer may be in the form of fine particles, which may make handling difficult, such as generation of dust in the separation and drying step. When the latter group of dispersants is used, the produced polymer becomes small granular and can improve the disadvantage of the former, but the polymer particles and the tank wall of the polymerization tank and the stirrer during the polymerization operation. It is inevitable that sticking will occur and a significant portion of the reacted monomer will be lost as unusable polymerization vessel deposits.
Generally, it takes a great deal of effort to remove deposits on a polymerization tank of a water-soluble ethylenically unsaturated monomer, which hinders efficient production of a granular polymer. It is an object of the present invention to provide a dispersant which ameliorates the above-mentioned disadvantages of the known dispersants conventionally used for reversed-phase suspension polymerization.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that both the lipophilic ethylenically unsaturated monomer unit and the ethylenically unsaturated monomer unit having a sugar residue are essential constituents. The inventors have found that a polymer as a component is useful as a dispersant for reversed-phase suspension polymerization, and completed the present invention. That is,
The present invention relates to a lipophilic ethylenically unsaturated monomer unit 70-99.
The present invention relates to a dispersant for reversed-phase suspension polymerization comprising a polymer having mol% and 1 to 30 mol% of an ethylenically unsaturated monomer unit having a sugar residue as an essential component.

In the present invention, examples of the lipophilic ethylenically unsaturated monomer unit include styrene, alkyl-substituted styrene (alkyl having 1 to 18 carbon atoms), (meth)
Acrylic acid alkyl esters (alkyl groups having 1 to 18 carbon atoms), vinyl alcohol fatty acid esters (fatty acids having 2 to 18 carbon atoms), N-alkyl (meth) acrylamides (alkyl group having 1 to 18 carbon atoms), etc. Monomer units. Further, as the saccharide residue contained in the ethylenically unsaturated monomer unit having a saccharide residue, any of known saccharides, oligosaccharides, polysaccharides and the like, or residues of derivatives thereof can be used. . Representative examples of monosaccharides include hexacarbon monosaccharides such as glucose, mannose, galactose, glucosamine, mannosamine, and galactosamine, and pentose monosaccharides such as arabinose, xylose, and ribose. Representative examples of oligosaccharides include lactose, trehalose, maltose, cellobiose, isomaltose, gentiobiose, laminaribiose, chitobiose, xylobiose, mannobiose, sophorose, maltotriose, maltotetraose, and hydrolysis of starch, cellulose, and the like. Objects and the like. Also, typical examples of polysaccharides include:
Chitin, chitosan, starch, cellulose and the like can be mentioned. Examples of the ethylenically unsaturated monomer unit having a sugar residue include glucoxyethyl (meth) acrylate and Kobayashi et al.'S reference (Polym. J., 15, 667 (198)
3), ibid, 17, 567 (1985)), a styrene derivative having glucose, maltose, lactose and maltotriose as side chains as represented by the following formula:

[0006]

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Further, a reaction product of chitosan with (meth) acrylic acid chloride or (meth) acrylic acid glycidyl may be used. In order to form the dispersant of the present invention, it is necessary to balance hydrophilicity and lipophilicity, and to use an ethylenically unsaturated monomer having a lipophilic ethylenically unsaturated monomer unit and a sugar residue. It can be controlled by the type and content of the body unit and the molecular weight of the polymer, and is selected so as to be suitable for the polymerization reaction depending on the type of the water-soluble ethylenically unsaturated monomer to be subjected to suspension polymerization. The ratio of the lipophilic ethylenically unsaturated monomer unit and the ethylenically unsaturated monomer unit having a sugar residue constituting the polymer of the present invention is 70 to 99 mol% of the former and 1 to 30 mol% of the latter. It is. Polymers in which the proportion of the ethylenically unsaturated monomer units having a sugar residue exceeds 30 mol% are not preferred because the affinity for oily solvents is insufficient. The number average molecular weight of the polymer of the present invention is 500 to 50.
0,000 is preferred. Polymers having a number average molecular weight of less than 500 or more than 500,000 do not exhibit a sufficient dispersion stabilizing effect even when the balance between hydrophilicity and lipophilicity is achieved. The dispersant according to the present invention is characterized in that the lipophilic ethylenically unsaturated monomer and the ethylenically unsaturated monomer having a sugar residue are present in the presence of a solvent capable of uniformly dissolving the monomer and the resulting polymer. It can be produced by radical polymerization with an azo or peroxide initiator.

When the dispersant of the present invention is used in the reverse phase suspension polymerization, the amount used is usually 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, based on all monomers to be polymerized as an active ingredient. It is more preferable to use in a smaller range out of this range. Various types of water-soluble ethylenically unsaturated monomers that can be polymerized by reverse phase suspension polymerization using the dispersant of the present invention and are soluble in water at an arbitrary ratio can be given. For example, alkali metal salts, ammonium salts, amine salts of acrylic acid or methacrylic acid, acrylamide or methacrylamide, or water-soluble N-substituted acrylamide or methacrylamide, or vinylimidazole, vinylpyridine, vinylpyrrolidone, or sulfonated styrene And alkali metal salts of vinyl sulfonic acid. When used, these monomers are used by dissolving them in water, and usually a solution having a concentration close to saturation with water is used.

The dispersant of the present invention can be used for copolymerizing these monomers alone or two or more monomers. Examples of the hydrophobic solvent used for the reverse phase suspension polymerization include aromatic and aliphatic non-polar solvents which do not dissolve water. Examples of such substances include benzene, toluene, xylene, heptane, hexane, cyclohexane, and petroleum ethers. Known polymerization initiators and accelerators may be used for the reverse phase suspension polymerization.For example, hydrogen peroxide, potassium persulfate,
Examples include ammonium persulfate, sodium peroxide, t-butyl hydroperoxide, azobisisobutyronitrile, azobisisovaleronitrile, and the like.As the accelerator, sodium hydrogen sulfite, sodium thiosulfate, ferrous ammonium sulfate, and the like. Is mentioned. The method of performing suspension polymerization with the dispersant of the present invention is the same as the conventional method. The polymer of the present invention can be used alone as a good dispersant, but if necessary, another emulsifier or a dispersant may be used in combination.

[0010]

EXAMPLES Next, the present invention will be described specifically with reference to Synthesis Examples, Examples and Comparative Examples, but the present invention is not limited to these Examples.

Synthesis Example 1 In a 300 ml four-necked flask equipped with a stirrer, a reflux condenser and a nitrogen gas inlet tube, 104.2 g (1.0 mol) of styrene, 17.5 g (0.03 mol) of a 50% aqueous solution of glucoxyethyl methacrylate,
After 100 g of acetonitrile and 1.3 g of 2,2'-azobisisobutyronitrile (hereinafter abbreviated as AIBN) were added and mixed, the mixture was sufficiently purged with nitrogen gas. After raising the temperature to 80 ° C, 80
Polymerization was performed at 8 ° C. for 8 hours. After dilution with acetone, the polymer solution was precipitated from an n-hexane / water two-layer solvent system,
Filtration and drying gave 101.0 g of dispersant A. 400MHz−
^{From 1} H-NMR, the content of the glucoxyethyl methacrylate monomer unit was 3.2 mol%. The number average molecular weight determined by GPC was 35,000 (pst conversion).

Synthesis Example 2 104.2 g (1.0 mol) of styrene, 29.2 g (0.05 mol) of a 50% aqueous solution of glucoxyethyl methacrylate, acetonitrile 1
Using 100 g of AIBN and 1.3 g of AIBN, polymerization and polymer isolation were carried out in the same manner as in Synthesis Example 1. 97.2 g of dispersant B are obtained,
From 400 MHz- ¹ H-NMR, it contained 5.3 mol% of a glucoxyethyl methacrylate monomer unit. The number average molecular weight determined by GPC was 33,000 (pst conversion).

SYNTHESIS EXAMPLE 3 Polymerization and polymerization were carried out in the same manner as in Synthesis Example 1 using 128.2 g (1.0 mol) of isopropyl methacrylate, 29.2 g (0.05 mol) of a 50% aqueous solution of glucoxyethyl methacrylate, 100 g of acetonitrile and 1.3 g of AIBN. Separated. 121.5 g of Dispersant C was obtained and contained 5.2 mol% of a glucoxyethyl methacrylate monomer unit by 400 MHz- ¹ H-NMR. G
The number average molecular weight determined by PC was 41,000 (pst conversion).

Synthesis Example 4 128.2 g (1.0 mol) of n-propyl methacrylate, N-p
Using 15.6 g (0.05 mol) of -vinylbenzyl-D-gluconamide, 100 g of acetonitrile, and 1.3 g of AIBN, polymerization and isolation were carried out in the same manner as in Synthesis Example 1. 112.5 g of Dispersant D was obtained and contained 4.9 mol% of the sugar residue-containing monomer unit by 400 MHz- ¹ H-NMR. The number average molecular weight determined by GPC was 33,000 (pst conversion).

Synthesis Example 5 Polymerization was carried out in the same manner as in Synthesis Example 1 using 104.2 g (1.0 mol) of styrene, 15.6 g (0.05 mol) of Np-vinylbenzyl-D-gluconamide, 100 g of acetonitrile, and 1.3 g of AIBN. Isolation was performed. 103.0 g of dispersant E were obtained, 40
From 0 MHz- ¹ H-NMR, it was found to contain 5.4 mol% of the sugar residue-containing monomer unit. The number average molecular weight by GPC is
It was 45,000 (pst conversion).

EXAMPLE 1 127.5% aqueous 80% acrylic acid solution was placed in a 500 ml four-necked flask.
g of the solution, and while stirring under cooling, 140 g of a 30% aqueous sodium hydroxide solution was added dropwise to neutralize the solution. Next, a solution in which 0.23 g of potassium persulfate was dissolved in 7.5 g of ion-exchanged water was added and mixed, and dissolved oxygen was removed by blowing nitrogen gas to prepare a monomer / initiator aqueous solution. Stirrer, reflux condenser,
400 ml of cyclohexane and 1.25 g of the dispersant A of Synthesis Example 1 were charged into a 1-liter four-necked flask equipped with a dropping funnel and a nitrogen gas inlet tube, and the temperature was raised to 75 ° C. while blowing out nitrogen gas to expel dissolved oxygen. did. Next, the monomer / initiator aqueous solution was added dropwise over 30 minutes while stirring at 350 rpm under a refluxing condition of cyclohexane, and then polymerization was performed for 3 hours under the refluxing condition. After the polymerization, the produced polymer was separated by filtration and dried under reduced pressure at 80 ° C to 100 ° C to obtain 86.5 g of granular sodium polyacrylate. The average particle size of the obtained polymer was 290 μm, and almost no deposits were found in the tank.

Examples 2 to 5 In the same manner as in Example 1 except that the dispersant A of Example 1 was replaced by the dispersants B, C, D and E of Synthesis Examples 2 to 5, Polymerization was performed. Table 1 shows the yield of the obtained sodium polyacrylate and the average particle size of the particles. In any case, deposits in the tank were hardly observed.

[0018]

[Table 1]

Comparative Example 1 Instead of the dispersant A of Example 1, a copolymer of styrene and dimethylaminoethyl methacrylate (containing 4.5 mol% of dimethylaminoethyl methacrylate units, number average molecular weight)
28,000) Except for using 1.25 g, the same operation as in Example 1 was performed, and during the dropping of the monomer initiator solution,
The produced sodium polyacrylate became clumpy and became unable to stir.

Comparative Example 2 The same operation as in Example 1 was carried out except that 1.25 g of sorbitan monostearate was used instead of dispersant A of Example 1, to find that 86.5 g of sodium polyacrylate fine particles were obtained. The average particle size was 50 μm. Further, considerable deposits were observed in the reaction tank.

[0021]

As specifically described in Examples, when a polymer is produced using the dispersant for reversed phase suspension polymerization of the present invention, almost no polymer aggregates are observed, Further, the produced polymer has an average particle size of several hundred μm, and it is possible to remarkably improve the workability and productivity in all the steps of producing the polymer. For example, when the dispersant of the present invention is used, since there is almost no polymer agglomerate in the reaction tank, there is an effect that long-term production can be performed without removing deposits in the tank. .

Claims (2)

(57) [Claims] 1. A lipophilic ethylenically unsaturated monomer unit 70.
A dispersant for reversed-phase suspension polymerization, comprising a polymer having an essential component of 1 to 30 mol% of an ethylenically unsaturated monomer unit having a sugar residue of from 99 to 99 mol%. 2. The dispersant according to claim 1, wherein the polymer has a number average molecular weight of 500 to 500,000.