JPH0559107A - Dispersing agent for reverse-phase suspension polymerization - Google Patents

Abstract

(57) [Summary] [Structure] Lipophilic ethylenically unsaturated monomer units 70 to 99
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. [Effect] When a polymer is produced using the dispersant for reverse phase suspension polymerization of the present invention, almost no aggregates of the polymer are observed, and the produced polymer has a particle size of several hundred μm. Since it has an average particle size, it is possible to significantly improve workability and productivity in all steps of polymer production.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a reverse phase composed of a polymer having as essential constituents both a lipophilic ethylenically unsaturated monomer unit and an ethylenically unsaturated monomer unit having a sugar residue. The present invention relates to a dispersant for suspension polymerization (hereinafter abbreviated as a dispersant).

[0002]

As a method for obtaining a water-soluble ethylenically unsaturated monomer as a spherical particle polymer, polymerization is carried out by suspending / dispersing an aqueous monomer solution in a hydrophobic solvent. The so-called reverse 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 polymerizing monomers in a dispersed state, prevent or reduce the tendency of the polymer particles to agglomerate, and control the particle size.

Dispersants used in reverse phase suspension polymerization of water-soluble ethylenically unsaturated monomers include, for example, sorbitan esters (sorbitan monostearate, sorbitan monooleate, etc.), ethoxylated fatty acids. Nonionic surfactants such as amides and glycerin fatty acid esters are known. Another group of known dispersants is, for example, allyl
lyl) group-containing resin treated with maleic anhydride, a polymer containing a carboxyl group having an affinity for an organic solvent, a high molecular compound such as a lipophilic fibrin derivative. However, when the former group of dispersants is used, the produced polymer becomes 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 polymer produced is in the form of small granules, but the former drawback can be improved, but during the polymerization operation, the polymer particles are dispersed between the polymer particles and the tank wall of the polymerization tank and the stirrer. It is inevitable that sticking will occur and a significant portion of the reacted monomers will be lost as unusable polymerization vessel deposits.
Generally, it takes a lot of labor to remove the deposits of the water-soluble ethylenically unsaturated monomer in the polymerization tank, which hinders the efficient production of the granular polymer. It is an object of the present invention to provide a dispersant that overcomes the above-mentioned drawbacks of known dispersants conventionally used in reverse phase suspension polymerization.

[0004]

Means for Solving the Problems As a result of earnest research, the present inventors have found that both lipophilic ethylenically unsaturated monomer units and ethylenically unsaturated monomer units having a sugar residue are essential constituents. The present invention has been completed by finding that the polymer as a component is useful as a dispersant for reverse phase suspension polymerization. That is,
The present invention relates to lipophilic ethylenically unsaturated monomer units 70-99.
The present invention relates to a dispersant for reversed phase suspension polymerization, which comprises 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, the lipophilic ethylenically unsaturated monomer unit is, for example, styrene, alkyl-substituted styrene (alkyl group having 1 to 18 carbon atoms), (meth).
Acrylic acid alkyl ester (alkyl group having 1 to 18 carbon atoms), vinyl alcohol fatty acid ester (fatty acid having 2 to 18 carbon atoms), N-alkyl (meth) acrylamide (alkyl group having 1 to 18 carbon atoms), etc. An example is a monomer unit. Further, as the sugar residue contained in the ethylenically unsaturated monomer unit having a sugar residue, known residues such as monosaccharides, oligosaccharides and polysaccharides, 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 pentacarbon 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, etc., and hydrolysis of starch, cellulose and the like. The thing etc. can be mentioned. In addition, as a typical example of polysaccharides,
Examples thereof include chitin, chitosan, starch and cellulose. Examples of the ethylenically unsaturated monomer unit having the above sugar residue include glucoxyethyl (meth) acrylate and Kobayashi et al. (Polym. J., 15, 667 (198
3), ibid, 17, 567 (1985)), a styrene derivative having glucose, maltose, lactose and maltotriose as a side chain as represented by the following formula.

[0006]

[Chemical 1]

Further, a reaction product of chitosan with (meth) acrylic acid chloride or glycidyl (meth) acrylate may be mentioned. In order to form the dispersant of the present invention, it is necessary to balance hydrophilicity and lipophilicity, and the lipophilic ethylenically unsaturated monomer unit and the ethylenically unsaturated monomer having a sugar residue used are used. It can be controlled by the kind 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 kind of the water-soluble ethylenically unsaturated monomer to be suspension-polymerized. The proportion 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 70-99 mol% of the former and 1-30 mol% of the latter. Is. Polymers in which the proportion of ethylenically unsaturated monomer units having a sugar residue exceeds 30 mol% are not preferred because of insufficient affinity for oily solvents. 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 show a sufficient dispersion stabilizing effect even if the hydrophilicity and lipophilicity are balanced. Dispersant of the present invention, the lipophilic ethylenically unsaturated monomer and the ethylenically unsaturated monomer having a sugar residue, the presence of a solvent such that these monomers and the resulting polymer can be uniformly dissolved It can be produced by radical polymerization with an azo or peroxide initiator.

When the dispersant of the present invention is used in 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 within a small range of this range. As the water-soluble ethylenically unsaturated monomer which can be polymerized by the reverse phase suspension polymerization to which the dispersant of the present invention is applied and which is soluble in water at an arbitrary ratio, various ones can be mentioned. For example, acrylic acid or methacrylic acid alkali metal salt, ammonium salt, amine salt, acrylamide or methacrylamide or water-soluble N-substituted acrylamide or methacrylamide, vinyl imidazole, vinyl pyridine, vinyl pyrrolidone, or sulfonated styrene. , Vinyl sulfonic acid alkali metal salts and the like. At the time of use, these monomers are dissolved in water before use, but usually a solution having a concentration close to saturation with respect to water is used.

The dispersant of the present invention can be used for homopolymerization of these monomers or copolymerization of two or more kinds of monomers. Examples of the hydrophobic solvent used in the reverse phase suspension polymerization include aromatic and aliphatic nonpolar solvents that do not dissolve water. Examples of such substances include benzene, toluene, xylene, heptane, hexane, cyclohexane, and petroleum ethers. As the polymerization initiator and the accelerator used in the reverse phase suspension polymerization, known ones may be used. For example, hydrogen peroxide, potassium persulfate, and
Examples thereof include ammonium persulfate, sodium peroxide, t-butyl hydroperoxide, azobisisobutyronitrile, azobisisovaleronitrile, and the like, and as the promoter, sodium hydrogen sulfite, sodium thiosulfate, ferrous ammonium sulfate and the like. Is mentioned. The method for carrying out suspension polymerization with the dispersant of the present invention is the same as the conventional method. The polymer of the present invention can be a good dispersant by itself, but other emulsifiers or dispersants may be used in combination if necessary.

[0010]

EXAMPLES The present invention will now be specifically described 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 introduction tube, 104.2 g (1.0 mol) of styrene, 17.5 g (0.03 mol) of a 50% aqueous glucooxyethyl methacrylate solution,
After adding 100 g of acetonitrile and 1.3 g of 2,2'-azobisisobutyronitrile (hereinafter abbreviated as AIBN) and mixing, nitrogen gas replacement was sufficiently performed. After raising the temperature to 80 ℃,
Polymerization was carried out at 8 ° C for 8 hours. After diluting with acetone, the polymer solution was precipitated from 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 glucooxyethyl methacrylate monomer unit is 3.2 mol%. The number average molecular weight 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 glucooxyethyl methacrylate, acetonitrile 1
Polymerization and polymer isolation were carried out in the same manner as in Synthesis Example 1 using 00 g and AIBN 1.3 g. 97.2 g of dispersant B are obtained,
From 400 MHz- ¹ H-NMR, it contained 5.3 mol% of glucooxyethyl methacrylate monomer unit. The number average molecular weight by GPC was 33,000 (pst conversion).

Synthetic Example 3 Polymerization / monomerization was carried out in the same manner as in Synthetic Example 1 using 128.2 g (1.0 mol) of isopropyl methacrylate, 29.2 g (0.05 mol) of 50% aqueous glucooxyethyl methacrylate solution, 100 g of acetonitrile and 1.3 g of AIBN. I went away. 121.5 g of Dispersant C was obtained and contained 5.2 mol% of glucooxyethyl methacrylate monomer unit by 400 MHz- ¹ H-NMR. Also, G
The number average molecular weight by PC was 41,000 (pst conversion).

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

Synthesis Example 5 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, polymerization and polymerization were carried out in the same manner as in Synthesis Example 1. Isolation was performed. 103.0 g of dispersant E are obtained, 40
From 0 MHz- ¹ H-NMR, it contained 5.4 mol% of a sugar residue-containing monomer unit. The number average molecular weight by GPC is
It was 45,000 (pst conversion).

Example 1 An 80% aqueous acrylic acid solution 127.5 was added to a 500 ml four-necked flask.
g was taken, and 140 g of a 30% caustic soda aqueous solution was added dropwise while stirring under cooling to neutralize. Next, a solution prepared by dissolving 0.23 g of potassium persulfate 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,
A 1-liter four-necked flask equipped with a dropping funnel and a nitrogen gas introduction tube was charged with 400 ml of cyclohexane and 1.25 g of the dispersant A of Synthesis Example 1, and blown with nitrogen gas to raise the temperature to 75 ° C. while expelling dissolved oxygen. did. Then, the monomer / initiator aqueous solution was added dropwise under reflux conditions of cyclohexane for 30 minutes while stirring at 350 rpm, and then polymerization was performed for 3 hours under reflux conditions. 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 deposit was observed 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 with the dispersant B, the dispersant C, the dispersant D and the dispersant E of Synthesis Examples 2 to 5. Polymerization was carried out. The yield of the obtained sodium polyacrylate and the average particle size of the particles are shown in Table 1. In all cases, almost no deposits were observed in the tank.

[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 unit, number average molecular weight) was used.
28,000) The same operation as in Example 1 was performed except that 1.25 g was used, and during the dropping of the monomer initiator solution,
The generated sodium polyacrylate became lumpy and could not be stirred.

Comparative Example 2 The same operation as in Example 1 was conducted except that 1.25 g of sorbitan monostearate was used in place of the dispersant A of Example 1, and 86.5 g of sodium polyacrylate fine particles were obtained. Obtained, the average particle size was 50 μm. Further, a considerable amount of deposit was found in the reaction tank.

[0021]

As described in detail in the examples, when a polymer is produced using the dispersant for reverse phase suspension polymerization of the present invention, almost no aggregate of the polymer is observed, Further, the produced polymer has an average particle diameter of several hundred μm, and it is possible to remarkably improve workability and productivity in all steps of producing the polymer. For example, when the dispersant of the present invention is used, there is almost no polymer agglomerate in the reaction tank, so that it has the effect of enabling long-term production without removing the deposits in the tank. ..

Claims (2)

[Claims] 1. A lipophilic ethylenically unsaturated monomer unit 70
A dispersant for reversed-phase suspension polymerization, which comprises a polymer having 99 to 99 mol% and 1 to 30 mol% of an ethylenically unsaturated monomer unit having a sugar residue as essential components. 2. The dispersant for reverse phase suspension polymerization according to claim 1, wherein the polymer has a number average molecular weight of 500 to 500,000.