JPH0764886B2 - Dispersion stabilizer for oil suspension polymerization - Google Patents

Description

The present invention relates to a lipophilic ethylenically unsaturated monomer unit, a cationic ethylenically unsaturated monomer unit and an anionic ethylenically unsaturated unit. The present invention relates to a dispersion stabilizer for oily suspension polymerization (hereinafter abbreviated as a dispersant), which is composed of an amphoteric polymer having three of the monomer units as essential constituent components.

[Conventional technology and problems]

As a method for obtaining a water-soluble ethylenically unsaturated monomer as a spherical particle polymer, a suspension polymerization method in an oily solvent is well known, and such a method generally uses a dispersant.
It is the function of the dispersant to keep the polymerizing monomers in dispersion, prevent or reduce the tendency of the polymer particles to agglomerate, and control particle shape.

Dispersants used for oil-based suspension polymerization of water-soluble ethylenically unsaturated monomers include, for example, sorbitan esters, sorbitan monostearate and sorbitan monooleate, ethoxylated fatty acid amides, glycerin fatty acid esters and the like. Ionic surfactants are known. Other groups of known dispersants are, for example, maleic anhydride treated products of resins having allyl groups, polymers containing carboxyl groups having an affinity for organic solvents, lipophilic fibrin derivatives and the like. It is a polymer compound.

However, when using the former group of dispersants,
The produced polymer becomes fine particles, which may cause difficulty in handling such as generation of dust in the separation and drying step. When the latter group of dispersants is used, the produced polymer becomes small granules, which can improve the above-mentioned drawbacks, but during the polymerization operation, the polymer particles are dispersed between the polymer particles and the 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.

[Means for solving problems]

It is an object of the present invention to provide a dispersant which remedies the above mentioned drawbacks of known dispersants conventionally used in oily suspension polymerization.

As a result of diligent research, the present inventors have found that a lipophilic ethylenically unsaturated monomer (A ₁ ) unit, a cationic ethylenically unsaturated monomer (A ₂ ) unit, and an anionic ethylenic The present invention has been completed by finding that an amphoteric polymer containing three unsaturated monomer (A ₃ ) units as essential constituents is useful as the dispersant.

In order to form the dispersant of the present invention, it is necessary to balance hydrophilicity and lipophilicity, and it is selected so as to be suitable for the polymerization reaction depending on the kind of the water-soluble ethylenically unsaturated monomer to be polymerized. However, the composition of the polymer is such that the lipophilic ethylenically unsaturated monomer (A ₁ ) unit is 70 to 99 mol%, and the cationic ethylenically unsaturated monomer (A ₂ ) unit is 0.5 to 29.5 mol. %, and anionic ethylenically unsaturated monomer (a ₃₎
A unit of 0.5 to 29.5 mol% is preferred. Further, the molar ratio of the cationic unsaturated monomer (A ₂ ) unit to the anionic unsaturated monomer (A ₃ ) unit is preferably 5 to 0.2. The molecular weight is preferably 1,000 to 1,000,000.

When the amount is out of the above range, the dispersion stabilizing ability is lowered, and when this is used as a dispersant for oily suspension polymerization, there arises a problem that particles agglomerate or the polymerization does not proceed smoothly. Polymers having a molecular weight of less than 1,000 or more than 1,000,000 do not show sufficient dispersion stabilizing ability even if the hydrophilicity and lipophilicity are balanced.

Lipophilic ethylenically unsaturated monomer (A ₁ ) in the present invention
Examples of the unit include styrene, alkyl-substituted styrene (alkyl group having 1 to 18 carbon atoms), (meth) acrylic acid alkyl ester (alkyl group having 1 to 1 carbon atoms).
8), fatty acid esters of vinyl alcohol (fatty acids having 2 to 18 carbon atoms) and N-alkyl (meth) acrylamide (alkyl groups having 1 to 18 carbon atoms).

Examples of the cationic ethylenically unsaturated monomer (A ₂ ) unit include monovinyl pyridines such as vinyl pyridine and 2-methyl-5-vinyl pyridine; N, N-dimethylaminostyrene, N, N-dimethylamino Styrenes having a dialkylamino group such as methylstyrene; N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate, N, N-diethylaminoethyl acrylate,
N, N-dimethylaminopropyl methacrylate, N, N-dimethylaminopropyl acrylate, N, N-diethylaminopropyl methacrylate, N, N-diethylaminopropyl acrylate ester having a dialkylamino group of acrylic acid or methacrylic acid; Vinyl ethers having a dialkylamino group such as 2-dimethylaminoethyl vinyl ether; N- (N ', N'-dimethylaminoethyl) methacrylamide, N- (N', N'-dimethylaminoethyl) acrylamide, N- ( N ', N'-diethylaminoethyl) methacrylamide, N- (N',
N'-diethylaminoethyl) acrylamide, N-
(N ', N'-dimethylaminopropyl) methacrylamide, N- (N', N'-dimethylaminopropyl) acrylamide, N- (N ', N'-diethylaminopropyl)
Examples thereof include acrylamide or methacrylamide units having a dialkylamino group such as methacrylamide, N- (N ', N'-diethylaminopropyl) acrylamide.

Anionic ethylenically unsaturated monomer (A ₃₎ as the unit, for example, acrylic acid, methacrylic acid, crotonic acid, vinyl benzoate, vinyl toluene sulfonic acid, 3-acrylamido-2,2-dimethyl-1- Unsaturated-basic acids such as sulphonic acid, styrene sulphonic acid, vinyl sulphonic acid or sulphoalkyl methacrylate; unsaturated dibasic acids such as itaconic acid, maleic acid, fumaric acid and carboxylic acids such as their monoesters and / or Alternatively, an ethylenically unsaturated monomer unit having a sulfonic acid group may be mentioned.

The lipophilic ethylenically unsaturated monomer (A ₁ ) unit, the cationic ethylenically unsaturated monomer (A ₂ ) unit, and the anionic ethylenically unsaturated monomer (A ₃ ) Units can be introduced into the polymer by copolymerizing the ethylenically unsaturated monomers A ₁ , A ₂ and A ₃ of interest.

The copolymerization of the ethylenically unsaturated monomer A ₁ , A ₂ and A ₃ for obtaining the amphoteric polymer of the present invention is carried out by mixing the monomer mixture in the above-mentioned predetermined ratio with the monomer in the presence of a radical initiator. It is preferably carried out by radical polymerization in the presence or absence of a medium for dissolving the mixture. In some cases, a chain transfer agent such as alkyl mercaptan, aromatic mercaptan, thioglycolic acid, and mercaptoethanol can be added to control the molecular weight of the produced polymer.

In the above copolymerization, known radical initiators may be used, for example, hydrogen peroxide, potassium persulfate,
Examples thereof include ammonium persulfate, sodium peroxide, t-butyl hydroperoxide, azobisisobutyronitrile, azobisisovaleronitrile and the like. Further, sodium bisulfite, sodium thiosulfate, ferrous ammonium sulfate or the like may be used in combination with these catalysts as an accelerator.

As the medium in the above copolymerization, benzene, toluene,
Aromatic solvents such as xylene and chlorobenzene, ether solvents such as tetrahydrofuran and dioxane, ketone solvents such as acetone and methyl ethyl ketone, amide solvents such as dimethylformamide and dimethylacetamide,
Sulfoxide solvents such as dimethyl sulfoxide and sulfolane, aliphatic solvents such as n-hexane and cyclohexane, halogenated hydrocarbon solvents such as chloroform and dichloromethane, alcohol solvents such as isopropyl alcohol and t-butyl alcohol, and the like. There is a mixed solvent. The reaction temperature and the reaction time may be in the known range in which radical polymerization is usually carried out, but generally 1 to 20 to 150 ° C.
It is selected in the range of 5 minutes to 15 hours depending on the reactivity of the substances A ₁ , A ₂ and A ₃ to be reacted, the decomposability of the catalyst, the boiling point of the solvent and the like.

The reaction product of A ₁ , A ₂ , and A ₃ reacted as described above is used as a solution of the medium as it is, or as a solid obtained by removing the medium, as a dispersant for oily suspension polymerization. Can be used. Further, when the abundance ratio of the cationic group and the anionic group in the polymer is not 1, the ionicity of the polymer should be improved by neutralizing and salting with an anionic substance or a cationic substance. Is also possible.

When the dispersant of the present invention is used in oil suspension polymerization, the amount used is usually 0.01 with respect to all monomers to be polymerized as an active ingredient.
-20% by weight, more preferably 0.05-10% by weight, and it is more preferable to use a small amount in this range.

As the water-soluble ethylenically unsaturated monomer which can be polymerized by the oily suspension polymerization to which the dispersant of the present invention is applied and which is dissolved in water at an arbitrary ratio, various ones can be mentioned. For example, alkali metal salt, ammonium salt, amine salt, acrylamide or methacrylamide or water-soluble N-substituted acrylamide or methacrylamide or vinyl imidazole, vinyl pyridine, vinyl pyrrolidone or sulfonated styrene, vinyl sulfonic acid of acrylic acid or methacrylic acid. Alkali metal salts and the like.

At the time of use, these monomers are used by dissolving them in water, but usually a solution having a concentration close to saturation with water is prepared.

The dispersant of the present invention can be used for homopolymerization of these monomers or copolymerization of two or more monomers.

As the solvent, an aromatic or aliphatic nonpolar solvent that does not dissolve water can be used. Examples of such substances include benzene, toluene, xylene, heptane, hexane, cyclohexane, and petroleum ethers.

As the polymerization initiator and the accelerator, known ones may be used. For example, hydrogen peroxide, potassium persulfate, ammonium persulfate, sodium peroxide, t-butyl hydroperoxide, azobisisobutyronitrile may be used as the initiator. , Azobisisovaleronitrile and the like, and examples of the promoter include sodium hydrogen sulfite, sodium thiosulfate, ammonium ferrous sulfate and the like.

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.

〔Example〕

Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Synthesis Example 1 Styrene 50.0 g, dimethylaminoethyl methacrylate 3.5
A mixture of 4 g, methacrylic acid 1.99 g, 2,2'-azobis-2,4-dimethylvaleronitrile 0.50 g and toluene 50 g was heated under a nitrogen stream at 65 ° C for 9 hours. The volatile matter was distilled off under reduced pressure to obtain 50.0 g of a dispersant ( 1 , Mn = 10,000).

Synthesis Example 2 Styrene 50.0 g, dimethylaminoethyl methacrylate 3.0
A mixture of g, 2.1 g of methacrylic acid, 0.52 g of 2,2′-azobis-2,4-dimethylvaleronitrile and 50 g of toluene was heated at 65 ° C. for 9 hours under a nitrogen stream. The volatile matter was distilled off under reduced pressure to obtain 54.5 g of a dispersant ( 2 Mn = 8,900).

Synthesis Example 3 Styrene 50.0 g, dimethylaminoethyl methacrylate 2.0
A mixture of g, 1.0 g of acrylic acid, 0.50 g of 2,2′-azobisisobutyronitrile and 50 g of toluene was heated at 65 ° C. for 9 hours under a nitrogen stream. The volatile matter was distilled off under reduced pressure to obtain 52.1 g of a dispersant ( 3 , Mn = 9,500).

Synthesis Example 4 A mixture of 50.0 g of lauryl methacrylate, 2.5 g of dimethylaminoethyl methacrylate, 1.4 g of methacrylic acid, 0.50 g of 2,2′-azobisisobutyronitrile and 50 g of toluene was heated at 65 ° C. for 9 hours under a nitrogen stream. did. The volatile matter was distilled off under reduced pressure to obtain 53.0 g of a dispersant ( 4 Mn = 6,800).

Example 1 127.5 g of acrylic acid having a purity of 80% by weight was placed in a 500 ml flask, and 30% by weight of a caustic soda aqueous solution was stirred while cooling.
After 141.8 g was added dropwise for 75 mol% neutralization, a solution prepared by dissolving 0.30 g of potassium persulfate in 12.5 g of ion-exchanged water was added.

312.5 g of cyclohexane in a flask equipped with a stirrer, a reflux condenser, and a dropping funnel, whose system was previously replaced with nitrogen.
Then, 1.5 g of the above-mentioned Dispersant 1 was charged and the temperature was started while stirring at a speed of 350 rpm to make cyclohexane gently reflux. In this state, the above-mentioned aqueous monomer solution was added dropwise from the dropping funnel for 30 minutes and then polymerized for 3 hours under reflux conditions. The polymer produced after the polymerization was separated and dried under reduced pressure to obtain 125 g of granular white dry polymer. The average particle size of the obtained polymer was 250 μm.

Examples 2 to 4 Dispersants 2 to 4 described in Synthesis Examples 2 to 4 were used in place of the dispersant 1 of Example 1, and the same operation as in Example 1 was performed. The results are shown in Table 1.

Copolymers of Daiwani styrene and methacrylic acid diethylaminoethyl comparison column 1 Dispersant 1 in Example 1 (dimethylaminoethyl methacrylate 4.5 mol% content, number average molecular weight 8,000) 1.5
Using g, the same operation as in Example 1 was performed. When 60 g of the monomer solution was dropped, a lump of polymer was deposited and stirring was impossible.

Copolymers of styrene and methacrylic acid in place of the dispersing agent 1 Comparative Example 2 Example 1 (containing 8.2mol methacrylic acid%, a number average molecular weight 2,200) using 1.5g, rows in the same manner as in Example 1 Ivy. When 50 g of the monomer solution was dropped, a lump of polymer was deposited and stirring was impossible. The results of Comparative Examples 1 and 2 suggest that styrene, dimethylaminoethyl methacrylate and methacrylic acid are essential components.

Comparative Example 3 The procedure of Example 1 was repeated using 5.0 g of sorbitan monolaurate instead of Dispersant 1 of Example 1 to obtain 120 g of a granular polymer. The average particle size of the obtained polymer is
It was as small as 50 μm.

Using the Comparative Example 4 instead of ethyl cellulose dispersant 1 of Example 1 (Hakiyuresu Ltd. N-100) 1.5 g in the same manner as in Example 1 to obtain 115.0g of the means pursuant granular polymer. The average particle size of the obtained polymer was 50 μm. There was 8.0 g of the polymer attached to the inner wall of the flask and the stirring rod, and
Compared to the case of 4, the polymer yield is lower.

Claims (3)

[Claims] 1. A lipophilic ethylenically unsaturated monomer unit 70-
99 mol%, cationic ethylenically unsaturated monomer units 0.
A dispersion stabilizer for oily suspension polymerization, which comprises a polymer having 5 to 29.5 mol% and an anionic ethylenically unsaturated monomer unit of 0.5 to 29.5 mol% as essential components. 2. The dispersion stabilizer for oily suspension polymerization according to claim 1, wherein the polymer has a number average molecular weight of 1,000 to 1,000,000. 3. The polymer according to claim 1 or 2, wherein the polymer has a molar ratio of the cationic unsaturated monomer unit to the anionic unsaturated monomer unit of 5 to 0.2. Dispersion stabilizer for oil suspension polymerization.