JPH028602B2 - - Google Patents

Description

[Detailed description of the invention]

Water-soluble polymers or crosslinked hydrophilic polymers, such as alkali metal salts of (meth)acrylic acid, (meth)acrylamide, tertiary and quaternary salts of aminoalkyl esters of (meth)acrylic acid, etc. The polymer or copolymer is a thickener,
In recent years, the demand for crosslinked hydrophilic polymers made insoluble in water by the use of a certain crosslinking agent has been increasing in demand as paper strength agents, soil conditioners, fiber treatment agents, precipitating flocculants, and as water absorbing agents. In general, the reversed-phase suspension polymerization method is a method for obtaining this type of polymer on an industrial scale because it is simple in terms of equipment, easy to control the reaction temperature, and the resulting polymer is pearl-like, making it easy to handle. It is excellent in this respect. In this case, an aqueous solution of a water-soluble vinyl monomer containing a water-soluble radical polymerization initiator is dispersed in the monomer and a water-insoluble organic solvent in the presence of a dispersant, and this system is held at the polymerization temperature for a predetermined period of time to form particles. The polymer is obtained by filtration. However, if the dispersant used here is not appropriate, the monomer aqueous solution droplets become strongly sticky as the polymerization progresses, and may aggregate or adhere to the reaction vessel wall or stirring rod. As this dispersant, there are many examples in which emulsifiers with a low HLB (hydrophilicity-lipophilicity balance) (2 to 8) or polymers with a similar structure are synthesized and used, but in order to stabilize the dispersion, In order to achieve this, large amounts of these dispersants must be used, resulting in the resulting polymer being a fine powder and problems in product purity. For example, in JP-A-46-2044, block and graft copolymers are used, but in the method described in the publication, it is thought that homopolymers of block and grafting monomers are simultaneously produced during copolymerization, It is difficult to obtain block and graft copolymers with good purity, and the amount used as a stabilizer is quite large, 5 to 20% by weight (based on the weight of the monomer). Generally, there are various methods for maintaining dispersion stability. For example, it is considered that a dispersing agent can be used that acts between the dispersed phase and the continuous phase so that electrostatic repulsion force or repulsion force generated from steric repulsion effects such as volume restriction effect and osmotic pressure effect acts. . However, it is quite difficult to prepare such a dispersant in a dispersion system treated in the present invention. Therefore, as a result of extensive studies on this point, the present inventors have made a polymer by suspending an aqueous solution containing one or more water-soluble vinyl monomers in the monomer and an organic solvent insoluble in water. (A) 0.1 to 10% by weight of one or more vinyl monomers having a hydrophilic group; (B) copolymerizable with the vinyl monomer (A), and the polymer is copolymerizable with the organic obtained by radical polymerization of a mixture of one or more hydrophobic vinyl monomers having good solubility in a solvent, and
We have found a method for producing a polymer characterized by using as a dispersant a copolymer that can be dissolved in the organic solvent even at a temperature 50° C. lower than the polymerization temperature of the water-soluble vinyl monomer. As mentioned above, the dispersant used in the present invention is a copolymer of a vinyl monomer (A) having a hydrophilic group and a hydrophobic vinyl monomer (B). vinyl monomers having a group, an amide group, an amino group, a sulfonic acid group, a hydroxyl group, etc., such as (meth)acrylic acid, itaconic acid, (meth)acrylamide,
N-vinylpyrrolidone, (meth)acrylic acid aminoalkyl ester, vinyl sulfonic acid, styrene sulfonic acid, hydroxyethyl (meth)acrylate, etc. are also hydrophobic vinyl monomers (B) that can be copolymerized with the vinyl monomer (A). As the solvent, styrene, (meth)acrylic acid alkyl ester, acrylonitrile, vinyl acetate, etc. can be used, and the selection of these types and amounts depends on the type of organic solvent used. Just follow the general rule that it dissolves in things. Among these vinyl monomers (B), (meth)acrylic acid with a carbon number of 1 to
Particularly preferred are alkyl esters of 12. Vinyl monomer (A) is copolymerized at 0.1 to 10% by weight,
Preferably it is 0.1 to 6% by weight. If it exceeds 10% by weight, the resulting dispersant polymer may have poor solubility in organic solvents, or even if dissolved,
It exhibits a reverse phase emulsion state and no pearl-like polymer is obtained. Further, the degree of polymerization of this dispersant polymer is within a range that maintains good solubility in the organic solvent used, and the higher the degree of polymerization, the better the dispersibility. The dispersant used in the present invention is one that is sufficiently soluble in an organic solvent, that is, one that has good solubility in an organic solvent. It can be dissolved in the organic solvent used even at a temperature 50°C lower than the polymerization temperature in water droplet type reverse phase suspension polymerization. Preferred dispersants are
It can be dissolved in the organic solvent used even at temperatures as low as 100°C. (However, the above temperature is 50℃ or 100℃ lower.
cm ² is one that can be dissolved at a temperature equal to or higher than the freezing point when the organic solvent is solidified. ) If a dispersant with good solubility is used in this way, even if the amount of dispersant used is very small, e.g.
Stable reverse-phase suspension polymerization is possible even at a high dispersion ratio of %. The dispersant polymer used in the present invention can be synthesized by any of the general methods such as solution polymerization, emulsion polymerization, and suspension (normal phase) polymerization, but polymers with a high degree of polymerization can be easily obtained. Emulsion polymerization and suspension polymerization are particularly suitable. Further, as a polymerization initiator used during polymerization, for example, benzoyl peroxide, azobisisobutyronitrile, ammonium persulfate, potassium persulfate, etc. can be used alone or in a redox system in combination with a reducing agent. As described above, the dispersant polymer used in the present invention is a random copolymer that can be easily synthesized, and furthermore,
According to the invention, this dispersant polymer is added in small amounts, preferably from 0.001 to 1% by weight, particularly preferably from 0.005% by weight.
Even when using only ~0.3% by weight (based on monomer aqueous solution), pearl-shaped water-soluble polymers can be produced stably with a high dispersion ratio of 50-60%, and with almost no deposits on reaction vessels or stirring rods. can be obtained. The organic solvent used in the present invention can be any solvent that is generally called a hydrophobic solvent, but representative examples include C ₆ to C ₁₀ aliphatic hydrocarbons,
In particular, aromatic hydrocarbons such as n-hexane, n-heptane, n-octane, and cyclohexane, halogenated hydrocarbons such as benzene, toluene, xylene, tri- or tetrachloroethylene, tri- or tetrachloroethane, carbon tetrachloride, Chlorbenzene, etc. These solvents may be used alone or as a mixed solvent of two or more. As the water-soluble vinyl monomer used in the present invention, any monomer can be used as long as it is radically polymerizable, the monomer or polymer is soluble in water, and is substantially insoluble in the organic solvent of the continuous phase. Typical monomers include alkali metal salts of (meth)acrylic acid, (meth)acrylamide,
These include tertiary salts or quaternary salts of aminoalkyl esters of (meth)acrylic acid. These monomers may be used alone or two or more types may be copolymerized. Moreover, by adding a certain type of crosslinking agent to this monomer aqueous solution, a water-insoluble crosslinking agent hydrophilic polymer can be obtained. As the crosslinking agent, for example, methylene bis(meth)acrylamide, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, divinylbenzene, triarylmonomethylammonium chloride, etc. can be used. The preferred amount of crosslinking agent used is 0.005 to 5% by weight (based on monomer). These monomers are polymerized in an aqueous solution, but their concentration is not particularly limited. When carrying out the polymerization of the present invention, any polymerization initiator that generates free radicals at the polymerization temperature can be used, but generally water-soluble ammonium persulfate, potassium persulfate, hydrogen peroxide, etc., and water-soluble azo 2,2'-Azobis-2 as a system initiator
-amidinopropane hydrochloride, 4,4'-azobiscyanopentanoic acid, etc. can be used. The polymerization of the present invention can be carried out as follows. An aqueous monomer solution to which a polymerization initiator has already been added is dispersed with stirring into an organic solvent in which a dispersant polymer is preferably dissolved in 0.001 to 1% by weight, particularly preferably 0.005 to 0.3% by weight (based on the monomer aqueous solution). .
Although the ratio of the monomer aqueous solution as the dispersed phase and the organic solvent as the continuous phase is not particularly limited, it is preferable that the dispersion ratio of the aqueous solution is about 60% or less. The order in which the components are added is not critical and may differ from the order described herein. The rotational speed of stirring is determined according to the amount necessary to uniformly disperse the reaction system and the desired particle size. Next, when the atmosphere of the reaction system is replaced with nitrogen, polymerization starts. The polymerization temperature is kept constant during the reaction, and is not particularly limited as long as it is below the boiling point of the dispersion medium and maintains the solubility of the dispersant polymer used.
After the polymerization is completed, it is cooled and filtered to obtain a pearl-like polymer. If necessary, the polymer can be dehydrated by azeotroping with the organic solvent used. Next, the present invention will be explained with reference to examples. Example [A] Synthesis of dispersant polymer (A-1) Distilled water in a separable flask with a capacity of 500 ml
Add an aqueous solution consisting of 30 parts and 2.0 parts of polyoxyethylene (n=30) octyl phenyl ether,
Polymerization temperature is 40℃ while replacing the atmosphere with nitrogen gas.
Increase the temperature to. Next, an aqueous solution consisting of 8 parts of polyoxyethylene (n=30) octyl phenyl ether, 0.2 parts of sodium lauryl sulfate, and 70 parts of distilled water, 3 parts of acrylic acid (2.9% in the monomer) as the vinyl monomer (A), and vinyl Monomer (B)
60 parts of 2-ethylhexyl acrylate (58.3% in monomer), 40 parts of styrene (in monomer)
103 parts of a monomer mixture consisting of 38.8%) and
10% of a monomer pre-emulsion consisting of 0.125 parts of ammonium persulfate (0.12% of monomers) as a polymerization initiator was added into the flask, followed by 10% of a reducing agent aqueous solution consisting of 0.075 parts of acidic sodium sulfite and 30 parts of distilled water. Add. After the polymerization begins and the temporary heat generation subsides, the remaining 90% of the monomer pre-emulsion and the reducing agent aqueous solution are simultaneously drop-polymerized over a period of 4 hours. Thereafter, the temperature of the polymerization system was raised to 60°C, maintained for 1 hour, and then cooled to room temperature. During the polymerization, stirring is continued while constantly flowing a small amount of nitrogen. The resulting polymer emulsion has a solid content
It was 43%. The dispersant polymer obtained here was sufficiently dissolved in toluene, xylene, tetra or trichloroethylene, etc. at -10°C. (A-2) 2 parts of dimethylaminoethyl methacrylate (1.9% in the monomer) was used as the vinyl monomer (A), 100 parts of 2-ethylhexyl acrylate (98.1% in the monomer) was used as the vinyl monomer (B), and the rest were Examples. Polymerization was carried out in the same manner as (A-1). The obtained dispersant polymers were n-hexane, n-heptane, n-octane, toluene,
It was sufficiently dissolved in xylene, tetra or trichloroethylene, chlorobenzene, etc. at 0°C. (A-3) 3 parts of acrylic acid (2.9% in the monomer) as the vinyl monomer (A), 40 parts of 2-ethylhexyl acrylate (in the monomer) as the vinyl monomer (B)
38.8%), 60 parts of isobutyl methacrylate (58.3% in monomer), and the rest were as in Example (A-
Polymerization was carried out in the same manner as in 1). The obtained dispersant polymer is dissolved in n-heptane/tetrachloroethylene (=6/4 volume ratio) mixture, toluene, xylene, tetra or trichloroethylene, etc.
It was sufficiently dissolved at ℃. (A-4) 2 parts of N-vinylpyrrolidone (1.9% in monomer) as vinyl monomer (A), vinyl monomer (B)
60 parts of 2-ethylhexyl acrylate (58.8% in monomer), isobutyl methacrylate
The polymerization method was the same as in Example (A-1) using 40 parts (39.3% in monomer). The obtained functional agent polymer was dissolved in toluene, xylene, tetra or trichloroethylene, n-heptane/tetrachloroethylene (=5/5 volume ratio) mixture at 5°C. (A-5) 2.37 parts of sodium chloride, 0.0052 parts of sodium polyacrylate (0.05% based on monomer) and distilled water
An aqueous solution containing 234.63 parts is placed in a 500 ml separable flask with two baffles, and the temperature is raised to 60°C while replacing the atmosphere with nitrogen gas.
Next, the rotation speed of the stirring blade was set to 350 to 400 rpm, and 3 parts of dimethylaminoethyl methacrylate (2.9% in the monomer) was added as the vinyl monomer (A).
A monomer mixture consisting of 60 parts of styrene (58.3% in the monomer) and 40 parts of isobutyl methacrylate (38.8% in the monomer) as the vinyl monomer (B)
Add a solution of 0.2575 parts of azobisisobutyronitrile (0.25% based on monomer) as a polymerization initiator to 103 parts. Approximately 1 hour after adding the monomer, the temperature inside the flask reaches a maximum temperature of 62-63°C. After that, it was reacted for 4 hours, cooled to room temperature,
Pass and dry. The obtained polymer particles (dispersant) are spherical particles of 0.2 to 1.0 mm, and can be sufficiently dissolved at 5°C in toluene, xylene, tetra or trichloroethylene, chlorobenzene, n-heptane/tetrachloroethylene = 5/5 volume ratio mixture, etc. did. [B] Water-soluble vinyl monomer reverse phase suspension polymerization (B-1) to (B-8) Dispersion medium 1.8 and initiator were dissolved in a cylindrical round bottom separable flask (No. 4) equipped with four baffles. 1.2 kg of the aqueous Nomer solution was charged, and the dispersant polymer synthesized in Example [A] was added while stirring at a predetermined rotation speed. (Add as emulsion). Raising the temperature to the polymerization temperature,
After about 30 minutes, a homogeneous dispersion will occur. Next, when nitrogen is blown into the atmosphere to replace the atmosphere with nitrogen, polymerization starts and is completed in about 4 hours. Then 60℃
After cooling for about 1 hour, the mixture is filtered and dried to obtain a pearl-like polymer. In addition, the solid content concentration is 80%
If the concentration is less than 80%, after the polymerization is completed, water is removed by azeotropic dehydration so that the solid content concentration is 80%. Yield is 95-98% in all cases.

【table】

[Table] (B-9) Using n-heptane/tetrachlorethylene = 5/5 volume ratio mixture 1.2 as the dispersion medium and 1.8 g of the polymer obtained in Example (A-5) as the dispersant (0.1% based on the monomer aqueous solution). , 1.8 kg of 35% sodium acrylate aqueous solution (PH = 8.5), 0.126 g of methylene bisacrylamide (0.02% to sodium acrylate) as a crosslinking agent, and 63 mg of ammonium persulfate (0.01% to monomer) as a polymerization initiator to the monomer aqueous solution. Dissolve and polymerize at 60℃
Then, polymerization was carried out in the same manner as in Examples (B-1) to (B-8). Obtained polymer particles (particle size
300μ, yield 95%) is insoluble in water, 550g water/g
It showed the water absorbency of the polymer. (B-10) Using 1.8 g of toluene as a dispersion medium and 1.2 g of the polymer obtained in Example (A-4) as a dispersant (0.1% of monomer aqueous solution), acrylamide
360g, β-methacroyloxyethyltrimethylammonium chloride 360g, triarylmonomethylammonium chloride 14.4g (2% based on monomer) as a cross-linking agent, 0.147g ammonium persulfate (0.02% based on monomer) as a polymerization initiator, and 465.6g water. Example (B-1) at a polymerization temperature of 60°C with a monomer aqueous solution dissolved in
Polymerization was carried out in the same manner as in (B-6). The obtained polymer particles (particle size 250μ, yield 95%) were insoluble in water and exhibited a water absorption of 300g water/g polymer. (B-11) In Examples (B-1) to (B-10), the amount of dispersant added was 0.005% (based on the monomer aqueous solution).
Polymerization was carried out in the same manner as in Examples (B1) to (B-10) except that Example (B-
Similar to 1) to (B-10), the reaction proceeded in a well-dispersed state. As described above, according to the method of the present invention, the dispersion effect was excellent even when the amount of dispersant used was small, and no problems were observed during polymerization. Comparative Example 1 In the same manner as in Example (A-1), methacrylic acid (3%)-2-ethylhexyl acrylate (24.2
%) isobutyl methacrylate (72.8%) copolymer (dispersant polymer) was synthesized. The dispersant polymer was dissolved in n-heptane at 50-55°C. 0.005% of this dispersant polymer (based on monomer aqueous solution)
Polymerization was carried out in the same manner as in Example (B-3) except that In this case, the dispersion stabilizing effect of the dispersant polymer was poor, and agglomeration of dispersed particles and adhesion to the reaction vessel were observed during polymerization.

Claims (1)

[Claims] 1. When producing a polymer by suspending an aqueous solution containing one or more water-soluble vinyl monomers in the monomer and a water-insoluble organic solvent, (A) a hydrophilic group (B) a hydrophobic vinyl monomer that is copolymerizable with the vinyl monomer (A) and whose polymer has good solubility in the organic solvent; A copolymer obtained by radical polymerization of a mixture of one or more of the following and which is soluble in the organic solvent even at a temperature 50°C lower than the polymerization temperature of the water-soluble vinyl monomer is used as a dispersant. Manufacturing method for characteristic polymers.