JPH0749444B2 - Method for producing polymer particle dispersion - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polymer particle dispersion.

[Prior Art] Conventionally, as a method for producing a polymer particle dispersion liquid, an emulsion polymerization method, a suspension polymerization method, a solution precipitation polymerization method, a method of precipitating polymer particles from a solution of a polymer, a method of redispersing a polymer, or the like. It has been known. In the production of polymer particle dispersions by these methods, stirring of the system is usually carried out by a rotary blade in order to prevent the polymer particles from coalescing, aggregating or splitting during the dispersion and production process of the monomers. However, it is difficult to sufficiently suppress coalescence, aggregation or division of particles in the production process of polymer particles by this method. As a result, the particle size of the obtained polymer particles was non-uniform and the particle size distribution was wide.

Therefore, various methods have been proposed for producing a uniform dispersion liquid of polymer particles having a narrow particle size distribution. One of them is, for example, polymerization in a system in which a medium flows in a pipe in a laminar flow state. The method is known. However, in this method, due to friction between the medium and the inner wall of the pipe, collision of polymer particles is unavoidable and coalescence of polymer particles,
It is not always sufficient to prevent agglomeration or fragmentation, and if it is attempted to improve this point sufficiently, it requires a large-scale device and it becomes difficult to obtain high productivity.

[Problems to be solved by the invention]

The present invention solves the problems of the prior art as described above, promotes dispersion or dissolution of monomers in a medium, prevents coalescence, aggregation or fragmentation of polymer particles during and after the formation process, An object of the present invention is to provide a method capable of producing a uniform dispersion liquid of polymer particles having a narrow diameter distribution with high production efficiency.

[Means for solving problems]

The above-mentioned object is to fill a reaction vessel filled with a mixing system for polymerization containing a monomer in a medium at a ratio of 98% by volume or more so that the inside of the reaction vessel is substantially filled, and the reaction vessel is placed at 0 to 5 ° with respect to the horizontal plane. While rotating the polymerization mixing system together with the reaction vessel by rotating around the rotation axis extending at an angle in the range or revolving around the rotation axis in a state separated from the rotation axis, the mixing for polymerization is performed. It is achieved by a method for producing a polymer particle dispersion, which comprises a step of polymerizing the monomer in a system to produce polymer particles in a state of being dispersed in the medium.

Next, the essential points of the present invention will be explained conceptually.

In the present invention, as shown in FIG. 1 and FIG.
For example, a cylindrical closed reaction vessel 1 is filled with a medium 3 containing a monomer so that the inner space of the reaction vessel 1 is substantially filled, and the central axis of the reaction vessel 1 is set to 0 with respect to the horizontal plane.
While keeping the angle in the range of ˜5 ° with this central axis as the rotation axis X, the reaction vessel 1 is rotated about its circumference at a constant rotation speed by a driving mechanism (not shown).
By causing the mixture system of the medium 3 and the monomer inside to rotate steadily around the rotation axis X together with the reaction vessel 1 due to the viscosity of the medium 3 in a state without any mechanical flow. To In this state, the monomers in the medium 3 are polymerized to generate polymer particles to produce a polymer particle dispersion liquid. Then, when the generated polymer particles are seen to settle, the rotation speed is increased.

If necessary, a buffer device (not shown) for adjusting the pressure inside the reaction container to a constant pressure can be attached to the reaction container.

In this way, the polymer particles generated in the mixing system rotating together with the reaction container change the existing position with respect to the outside of the reaction container with almost no change in the relative position in the medium due to the viscosity of the medium. Gravity can be applied sequentially from different directions, and such a state can be realized by appropriately selecting the specific gravity and size of the polymer particles, the specific gravity and viscosity of the medium, and the rotation speed of the reaction vessel. can do.

In this state, looking at the polymer particles (indicated by reference numeral 2 in FIG. 3) in the mixed system, one polymer particle 2 is a medium 3 as shown schematically in FIG.
Inside, the medium 3 relatively makes a gentle circular motion as shown by an arrow A in the absence of mechanical flow. Then, such local circular motion is uniformly generated in each polymer particle in a substantially approximated state, so that collision between the polymer particles is almost avoided, or the polymer particles are generated in the process of producing the polymer particles. Even if the particles collide with each other, the impact force does not cause the particles to coalesce with each other or agglomerate, so that the polymer particles are uniformly dispersed in a single particle state in the medium. It is supposed to be.

INDUSTRIAL APPLICABILITY The production method of the present invention can be applied to a type of polymerization in which a polymer is produced in a state of particles in a medium, and can be adopted in, for example, emulsion polymerization, suspension polymerization, solution precipitation polymerization and the like.

Therefore, the reaction system substances such as the medium and the monomer to be filled in the reaction vessel are selected depending on the polymerization mode adopted. For example, when the present invention is applied to emulsion polymerization or suspension polymerization, the monomer is dispersed in a medium (dispersion medium) to be in an emulsion or suspension state, and the dispersed monomer is the above-mentioned polymer particles. In the same state as above, the particles are uniformly dispersed in the dispersion medium, and polymer particles are generated as the polymerization proceeds. Further, in the emulsion polymerization, when the emulsifier is not used or when the amount is small even if the emulsifier is used, the monomer may be the oil layer as it is. Further, in the case of solution precipitation polymerization, the monomer is dissolved in a medium (solvent) and is in a solution state, and as the polymerization progresses, a polymer having a lower solubility is precipitated in a particle state.

In the present invention, the rotation speed of the reaction vessel is generally defined by the polymerization form, the size and specific gravity of the monomer oil droplets, the size and specific gravity of the polymer particles to be produced, the viscosity of the medium, the shape and size of the reaction vessel, etc. However, it is usually adjusted to about 1 to 30 rpm, preferably about 2 to 20 rpm.

In the present invention, it is necessary that the mixed system of the medium and the monomer in the reaction vessel is filled in a filled state so that there is substantially no space, and this ensures that the mixed system is kept in the reaction vessel. It becomes easy to rotate together with it. However, even if there is a space in the reaction vessel, if it is small, the disturbance in the medium due to the presence of the space is limited to a small area in the upper part of the mixing system in the reaction vessel. The above does not invalidate the effects of the present invention. However, when the proportion of the space in the reaction container is large, the mixed system cannot be rotated together with the reaction container without disturbing, and the object of the present invention cannot be achieved. Therefore, in the present invention, the filling rate of the mixed system in the reaction vessel is set to 98% by volume or more of the reaction vessel.

Further, the shape of the reaction vessel is preferably a cylindrical shape, such as a rectangular tube shape or a spherical shape, and there is no problem, and the rotation system is essentially rotated in a vertical plane so that the upper and lower sides of the vessel are interchanged. For example, as shown in FIG. 4, the container 12 may be held at the tip of an arm 11 that rotates around a horizontal rotation axis 10 and revolve around the vertical plane. Cylindrical reaction vessel 20 as shown in
May be rotated so as to rotate about a horizontal rotation axis Y extending in the radial direction.

Next, the present invention will be described in more detail according to the polymerization mode.

(1) Solution Precipitation Polymerization Method The combination of the monomer and the polymerization initiator to which the solution precipitation polymerization method is applied is not limited as long as the polymer is soluble in the medium and the produced polymer is insoluble in the medium. As monomers, styrene-based monomers such as styrene and chlorostyrene, methyl (meth) acrylate, (meth)
(Meth) acrylate monomers such as -n-butyl acrylate, hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, and polyoxyethylene (meth) acrylate; (meth) acrylonitrile; (meth) acrylamide (Meth) acrolein; vinyl acetate; vinyl halide-based monomers such as vinyl chloride and vinylidene chloride; unsaturated acid (anhydride) -based monomers such as (meth) acrylic acid, itaconic acid, (anhydrous) maleic acid;
Examples thereof include diene-based monomers such as butadiene and isoprene. Also, novolac resin, resole resin, trimethylolmelamine resin, unsaturated polyester resin,
Thermosetting resin prepolymers such as epoxy resins can also be used as monomers. When the polymer to be produced has a relatively high solubility in a solvent, it is preferable to reduce the solubility by using a polyfunctional monomer together. Examples of such polyfunctional monomers include divinylbenzene, triaryl isocyanurate, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, methylenebisacrylamide, polyoxyethylene di (meth) acrylate and the like. To be

As the polymerization initiator, a radical initiator, a transition metal-based complex catalyst, an anion initiator, and a cation initiator are used, and a radical initiator is generally used. Radical initiators include benzoyl peroxide, octanoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, hydrogen peroxide, potassium persulfate, ammonium persulfate, azobisisosulfate. Butyronitrile and redox catalysts using these, for example, a combination of benzoyl peroxide and dimethylaniline, hydrogen peroxide and ferrous chloride, potassium persulfate and sodium bisulfite, and the like are used. The amount of the radical polymerization initiator used is usually 0.1 to 5 parts by weight with respect to 100 parts by weight of the monomer, which is equivalent to the case of using another polymerization apparatus. In some cases, the polymerization may be performed only by heating without using these polymerization initiators. Examples of the medium include water; alcohols such as methanol, ethanol, ethylene glycol, cellosolve, and carbitol; ethyl acetate, n-butyl acetate, diethyl phthalate,
Esters such as tricresyl phosphate, γ-butyrolactone and ethyl silicate; ketones such as acetone, methyl ethyl ketone and acetophenone; ethers such as dibutyl ether, diphenyl ether, tetrahydrofuran and anisole; n-hexane, n-octane, cyclohexane, tetralin, decalin, Hydrocarbons such as benzene, toluene, xylene, liquid paraffin; halogenated hydrocarbons such as chlorobenzene, dichlorobenzene, dodecyl chloride, halogenated paraffins; formamide, dimethylformamide, dimethylacetamide, N
An amide such as methylpyrrolidone; and pyridine,
Examples thereof include morpholine and dimethyl sulfoxide, which can be used in an appropriate combination by adjusting the solubility of the monomer and the polymerization initiator.

Even if the mixing ratio of the monomer and the medium is raised to 10/100 to 50/100 which is 2 to 10 times as high as the conventional method, polymer particles having a narrow particle size distribution can be obtained. The preferred monomer / medium ratio is 10/100 to 30/100, and the larger the monomer / medium ratio, the larger the particle size of the polymer produced.

The particle size of the polymer particles produced in the solution precipitation polymerization method to which the present production method is applied tends to be smaller as the polymerization rate of the monomer and the solubility of the polymer in the solvent are smaller. It can be adjusted by the amount of the functional monomer used, the combination of solvents, the monomer / medium ratio, the type and amount of the polymerization initiator, the polymerization temperature and the like.

(2) Emulsion polymerization method As the monomer to which the emulsion polymerization method is applied, the above (1) is used.
It is possible to exemplify the monomer excluding the thermosetting resin prepolymer among the monomers exemplified in the solution precipitation polymerization method, but the amount of the water-soluble monomer used in the exemplified monoer is about 20% by weight or less of all the monomers. Limited to Since the medium in the emulsion polymerization method is water, the polymerization initiator is a water-soluble polymerization initiator among the above-mentioned polymerization initiators,
For example, potassium persulfate or the like is used.

As an emulsifier used for emulsion polymerization, sodium dodecylbenzene sulfonate, sodium lauryl sulfate, potassium fatty acid, polyoxyethylene nonylphenyl ether, etc. are used in an amount of about 0.1 to 3 parts by weight per 100 parts by weight of the monomer. If it is water soluble to some extent,
For example, when methyl methacrylate, acrylonitrile, styrene and methacrylic acid are used as monomers, the use of an emulsifier is not always necessary.

In the case of the total mixture system of monomers in the emulsion polymerization method, it is usually 2 to 40% by weight. In the emulsion polymerization method,
The particle size of the produced polymer particles can be adjusted by the polymerization temperature and the amount of the emulsifier, the combination of the monomers, the amount of the polyfunctional monomer used, the ratio of the monomer and water, the type and the amount of the polymerization initiator, and the like.

(3) Suspension polymerization method The monomer, polymerization initiator and medium to which the suspension polymerization method is applied may be the same as those exemplified in the above (1) solution precipitation polymerization method, but a combination thereof. The combination is limited to the combination in which the monomer containing the polymerization initiator is dispersed as droplets in the medium. Further, the monomer may be dissolved in a medium and dispersed as a droplet in another medium. For example, a solution of methacrylic acid, methylenebisacrylamide, potassium persulfate and water may be a liquid paraffin. Examples include combinations that are dispersed in.

In the suspension polymerization method, the ratio of the monomer to the whole mixed system is usually 2 to 40% by weight. In the suspension polymerization method,
The particle size of the polymer particles produced is determined by the particle size of the droplets containing the monomer when initially dispersed. The polymerization conditions other than those described above in (1) solution precipitation polymerization method (2) emulsion polymerization method and (3) suspension polymerization method are not particularly different from ordinary polymerization conditions, and generally used polymerization conditions are applied. can do.

〔Example〕

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited thereto. In the following description, "parts" and "%" represent parts by weight and% by weight.

Example 1 (Solution Precipitation Polymerization) (Monomer) Methacrylic acid 10 parts Methyl methacrylate 9 parts Ethylene glycol dimethacrylate 1 part (Media) Ethyl acetate 50 parts Chlorobenzene 50 parts (Polymerization initiator) Benzoyl peroxide 0.6 parts The mixture was mixed and filled in a cylindrical container having a volume of 100 ml without an air layer, and polymerization was performed at 70 ° C. for 7 hours while rotating the container around a horizontal axis at a rotation speed of 6 rpm. As a result, the average particle diameter is 3.5 μm, and the standard deviation of the particle diameter is 0.12.
A dispersion of spherical polymer particles of μm was obtained. The polymerization conversion rate in this polymerization was 92%, and formation of aggregates was not observed.

Comparative Example 1 A reaction vessel having a volume of 300 ml having an anchor type stirring blade was used.
Polymerization was carried out under the same conditions, except that the system was mechanically stirred at a rotation speed of 100 rpm and the monomer, medium and polymerization initiator having the same composition as in Example 1 were used. As a result, the whole became solid and it became impossible to stir, so the polymerization was carried out with double the amount of medium, and the average particle size was 1 μm, standard deviation
A dispersion of non-spherical polymer particles of 0.20 μm was obtained. In this polymerization, the polymerization conversion rate was 70% and the aggregate formation rate was 8
%Met.

Example 2 (Emulsion polymerization) (Monomer) Styrene 10 parts (Medium) Water 30 parts (Polymerization initiator) Potassium persulfate 0.05 part (Emulsifier) Sodium dodecylbenzenesulfonate 0.03 parts The above substances are mixed and a cylinder having a capacity of 100 ml is mixed. The mold container was filled without an air layer, and polymerization was carried out at 70 ° C. for 12 hours while rotating the container around a horizontal axis at a rotation speed of 13 rpm. As a result, the average particle size is 0.8 μm, and the standard deviation of the particle size is 0.01.
A dispersion of polystyrene particles of μm was obtained. The polymerization conversion rate in this polymerization was 95%, and the formation rate of aggregates was 1.6%.

Comparative Example 2 Using a reaction vessel having a volume of 300 ml with an anchor type stirring blade,
Polymerization was carried out under the same conditions using the monomers, medium, polymerization initiator and emulsifier having the same composition as in Example 2 except that the system was mechanically stirred at a rotation speed of 150 rpm. As a result, a dispersion liquid of polymer particles having an average particle diameter of 0.34 μm and a standard deviation of 0.02 μm was obtained. The polymerization conversion rate in this polymerization was 92.
%, The production rate of aggregates was 5.4%.

Example 3 (Suspension Polymerization) (Monomer) Styrene 20 parts Divinylbenzene 20 parts Toluene (solvent for diluting monomer) 20 parts (Medium) Polyvinyl alcohol (Gothenol GH20 "(Nippon Gosei Kagaku Co., Ltd.) 2% aqueous solution 300 Parts (polymerization initiator) benzoyl peroxide 1.5 parts The above substances were put into a flask and stirred for 30 minutes at a rotation speed of 300 rpm with a stirrer consisting of a flat plate turbine blade to make the monomer solution into droplets with a particle size of about 200 μm. Dispersed, and then
This dispersion was filled in a cylindrical container with a capacity of 100 ml without an air layer, and while rotating the container around a horizontal axis at a rotation speed of 10 rpm, polymerization was performed for 12 hours at 60 ° C. A dispersion was obtained. Then, the produced polymer particles were washed with water and sieved to obtain particles having a particle size of 156 to 254 μm. Particle size 156-254 μm for all polymer particles
The yield of polymer particles in the range was 56% by volume.

Comparative Example 3 A dispersion liquid of droplets having a particle diameter of about 200 μm, which was composed of a monomer, a medium and a polymerization initiator having the same composition as in Example 3, was prepared in the same manner as in Example 3. The dispersion obtained in the next step was placed in a reaction vessel having a capacity of 300 ml having an anchor type stirring blade, and the rotation speed was 200 r.
Polymerization was carried out under the same conditions as in Example 3 except for stirring at pm to obtain a dispersion liquid of polymer particles.

The produced polymer particles were washed with water and sieved to obtain particles in the range of 156 to 254 μm. The yield of polymer particles having a particle size in the range of 156 to 254 μm was 40% by volume based on the total amount of polymer particles produced.

〔The invention's effect〕

In the production method of the present invention, the reaction vessel is substantially filled with the polymerization mixture system containing the monomer in the medium.
A reaction vessel filled with 98% by volume or more is rotated around a rotating shaft extending at an angle of 0 to 5 ° with respect to a horizontal plane, or is separated from the rotating shaft around the rotating shaft. By revolving it, polymerization can be carried out without mechanically stirring the mixed system, so that the dispersion of the monomer in the medium and the dispersion of the polymer particles in the production process and after the production can be satisfactorily achieved. . Furthermore, in the production method of the present invention, since the mixing system is not mechanically agitated as described above, a force such as a shearing force or a large impact does not act on the polymer particles in the production process, Therefore, it is avoided that the polymer particles collide with each other and coalesce, aggregate or split.

As described above, according to the present invention, in a solution precipitation polymerization method, an emulsion polymerization method, a suspension polymerization method or the like for producing polymer particles, the polymer particles in the production process can be used as a medium without essentially applying a shearing force. Provided is a method capable of being always uniformly dispersed in a dispersion liquid, which has a large particle size, and in which uniform polymer particles having a narrow particle size distribution are uniformly dispersed, and which can be easily produced with high production efficiency. .

[Brief description of drawings]

1 and 2 are explanatory sectional views and perspective views of an example of the present invention, FIG. 3 is an explanatory view of movement of particles in a medium, and FIGS. 4 and 5 are other examples of the present invention. 3A and 3B are explanatory cross-sectional views and perspective views illustrating an example of FIG. 1,12,20 …… Reaction vessel 2 …… Polymer particles, 3 …… Medium

Claims (1)

[Claims] 1. A polymerization mixture system containing a monomer in a medium,
The reaction vessel filled with 98% by volume or more so that the inside of the reaction vessel is substantially filled is rotated around a rotation axis extending at an angle of 0 to 5 ° with respect to the horizontal plane, or the rotation axis is rotated. By revolving around the axis of rotation in a state away from the, while rotating the polymerization mixing system with the reaction vessel, by polymerizing the monomer in the polymerization mixing system, dispersed in the medium A method for producing a polymer particle dispersion, comprising a step of producing polymer particles in a state.