JP2012077170A - Method for producing polymer particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polymer particle which has excellent polymerization stability, and can exhibit stable fluidity even under the increase of humidity when being used as an electrophotographic toner external additive.SOLUTION: In the method for producing a polymer particle, 100 pts.wt. of a polymerizable vinyl monomer comprising (meth)acrylic acid ester based monomer and (meth)acrylic acid allyl is emulsion-polymerized in an aqueous medium in the presence of 0.05 to 0.5 pts.wt. of ion-denatured vinyl alcohol without adding a surfactant.

Description

    The present invention relates to a method for producing polymer particles, particularly polymer particles useful as an electrophotographic toner external additive.

  Many polymer particles that have been widely used in the past as paint additives, adhesives, cosmetic additives, toner additives, light diffusing agents, liquid crystal spacers, binders, rheology modifiers, extenders, coating film performance improvers, etc. Is known to be charged on the particles themselves. As an application example using the charging phenomenon of the polymer particles, for example, it is used as an additive (toner external additive) that imparts charging properties by adding to an electrophotographic toner used for electrostatic image development. Or used as particles for powder coating. Thus, the charged polymer particles have a high utility value, but in the case of the polymer particles used in such application examples, it is desired to have a stable charge amount in a high humidity environment. Yes.

  In addition, the polymer particles used in such an application need to have a controlled particle size. In order to control the particle size of the polymer particles, a method of classifying the polymer particles after production may be considered, but it is desirable to control at the polymerization stage in view of production efficiency. Thus, as a polymerization method capable of controlling the particle size and the like of the polymer particles in this way, generally, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method and the like can be mentioned. Among these, according to the emulsion polymerization method, charged submicron-sized polymer particles can be obtained easily and stably.

  Such an emulsion polymerization method is generally a method in which a monomer is polymerized in an aqueous medium by adding a water-soluble polymerization initiator in the presence of a surfactant. The polymer particles obtained by this emulsion polymerization method have a large amount of surfactant remaining on the surface, so that they easily adsorb moisture in the air, and can have high charge in a low humidity environment, for example. In a high-humidity environment, the charge amount decreases due to the effect of adsorbed moisture, and when used as an external additive for electrophotographic toner, high chargeability cannot be maintained.

  Therefore, a styrene-based or acrylic heavy polymer produced by using, as a polymer dispersion stabilizer, polyvinyl alcohol (hereinafter abbreviated as PVA) into which a sulfone group or a mercapto group is introduced at the terminal instead of a surfactant. Combined particles have been proposed (Patent Documents 1 and 2).

In order to improve the polymerization stability by such a method, it is necessary to increase the amount of PVA used. However, since PVA itself is a hydrophilic polymer, PVA adheres to the surface of polymer particles obtained by polymerization. Therefore, if the amount of PVA used increases, the amount of PVA adhering to the particle surface also increases, and when the PVA adhering to the surface adsorbs moisture and is used as an external additive for electrophotographic toner, it is under high humidity. There was a problem that a high charge amount could not be maintained.

In addition, when polymer particles are used as an external toner additive, the charge control agent and paraffin contained in the toner are absorbed or adsorbed by the external additive, and the properties of the toner change. There has been a demand for polymer particles having excellent properties. As described above, there has not been proposed a production method capable of stably obtaining polymer particles having a stable amount of charge and excellent solvent resistance without changing the water adsorption amount due to environmental changes.

JP-A-50-155579 JP-A-6-179705

  An object of the present invention is to provide a method for producing polymer particles that are excellent in polymerization stability, do not change the amount of moisture adsorption due to environmental changes, and have excellent solvent resistance.

  According to the first aspect of the present invention, there is provided a means for solving the above-mentioned problem. 100 parts by weight of a polymerizable vinyl monomer comprising a (meth) acrylic acid ester monomer and 10 to 60% by weight of allyl (meth) acrylate Is a method for producing polymer particles in which emulsion polymerization is carried out without adding a surfactant in an aqueous medium in the presence of 0.05 to 0.5 parts by weight of ion-modified vinyl alcohol. According to the configuration of the present invention, polymer particles having excellent polymerization stability can be obtained without using a surfactant and in spite of a small amount of dispersion stabilizer. The polymer particles thus obtained have a low rate of change in water adsorption rate under different humidity environments and have solvent resistance, so when used as an electrophotographic toner external additive, even under high humidity conditions. It shows a stable charge amount and does not adsorb a charge control agent or the like.

  Further, according to the second invention, in addition to the structure of the first invention, emulsion polymerization is performed after the droplet diameter of the polymerizable monomer is dispersed in a state of 5.0 to 500 μm in an aqueous medium. According to the configuration of the second invention, since the emulsion monomer is dispersed after the droplet diameter of the polymerizable monomer is dispersed in an aqueous medium in a state of 5.0 to 500 μm, the aggregated product is extremely small, Uniform polymer particles can be obtained stably.

  According to the method for producing polymer particles of the present invention, polymer particles having excellent polymerization stability and having stable charging properties even under high humidity when used as an external additive for an electrophotographic toner are obtained. Therefore, it is suitable as an additive for toners and carriers used for electrostatic image development, powder coating additives, civil engineering material top coats, sealers, inkjet recording materials, and electrodeposition paints. ing.

Hereinafter, the method for producing the polymer particles of the present invention and the case where the polymer particles are used as an electrophotographic toner external additive will be described in detail.
In the present invention, 100 parts by weight of a polymerizable vinyl monomer comprising a (meth) acrylic acid ester monomer and 10 to 60% by weight of allyl (meth) acrylate is added to 0.05 to 0.5 parts by weight of ion-modified vinyl. This is a method for producing polymer particles which are emulsion-polymerized in an aqueous medium in the presence of alcohol without adding a surfactant.

  In the (meth) acrylic ester monomer used in the present invention, “(meth) acryl” means acrylic or methacrylic.

  That is, the (meth) acrylic acid ester monomer used in the present invention includes, for example, an acrylic acid ester monomer as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, Examples thereof include t-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isodecyl acrylate, lauryl acrylate, tridecyl acrylate, stearyl acrylate, cyclohexyl acrylate, and the like. Examples of methacrylic acid ester monomers include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, Examples include octyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, and the like. These (meth) acrylic ester monomers may be used alone or in combination. Even in such a (meth) acrylic ester monomer, methyl methacrylate or ethyl methacrylate is preferable, and methyl methacrylate is particularly preferable from the viewpoint of solvent resistance.

  In the present invention, allyl (meth) acrylate is selected as the crosslinking agent, and this is selected in consideration of the reactivity with the (meth) acrylic ester monomer. For example, when divinylbenzene, ethylene glycol dimethacrylate, or the like is used as the crosslinking agent, the polymer particles cannot be stably produced because of high reactivity. Therefore, in the present invention, allyl (meth) acrylate is used. The mixing ratio of allyl (meth) acrylate is 10 to 60% by weight in the polymerizable vinyl monomer. When the mixing ratio is less than 10% by weight, the solvent resistance is insufficient, and when it exceeds 60% by weight, the polymerization stability is deteriorated and the intended particles cannot be obtained. The mixing ratio of allyl (meth) acrylate is preferably 20 to 50% by weight. In the polymerizable vinyl monomer, allyl methacrylate and allyl acrylate may be used alone or in combination. Among these, allyl methacrylate is particularly preferable from the viewpoint of polymerization reactivity with (meth) acrylic acid ester.

  In addition, other monomers and additives may be used in combination with the polymerizable vinyl monomer of the present invention as long as the effects of the present invention are not impaired. Examples of other monomers include styrene monomers. Specific examples of the styrene monomer include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and chlorostyrene. These styrenic monomers may be used alone or in combination. Other additives include light stabilizers, ultraviolet absorbers, pigments, dyes, antifoaming agents, thickeners, thermal stabilizers, leveling agents, lubricants, antistatic agents and the like. These additives can be variously selected depending on the performance of the polymer particles obtained.

As the ion-modified polyvinyl alcohol (hereinafter “ion-modified PVA”) used in the present invention, either anion-modified or cation-modified PVA is selected and used. Since the ion-modified PVA has an ionic group having a strong ionic repulsion force in an aqueous medium, the droplets and the resulting polymer particles can be further stabilized. Specific examples of the ion-modified PVA include anion-modified polyvinyl alcohol (hereinafter referred to as “anion-modified PVA”) such as sulfonic acid group-modified polyvinyl alcohol and carboxyl group-modified polyvinyl alcohol. Examples thereof include polyvinyl alcohol. These are appropriately selected depending on whether the obtained polymer particles are negatively charged or positively charged. If the polymer particles are negatively charged, the anion-modified PVA is a positively charged polymer. In the case of particles, cation-modified PVA is selected.
Usually, it is used alone, but two or more types may be combined as long as they have the same ionicity. Among these, sulfonic acid group-modified polyvinyl alcohol is preferred as the anion-modified PVA and amino group-modified polyvinyl alcohol is preferred as the cation-modified PVA from the viewpoint of the stability of the droplets and polymer particles.

  The amount of the ion-modified PVA used is preferably 0.05 to 0.5 parts by weight, particularly preferably 0.05 to 0.2 parts by weight, based on 100 parts by weight of the polymerizable vinyl monomer. When the amount of ion-modified PVA used is less than 0.05 parts by weight based on 100 parts by weight of the polymerizable vinyl monomer, the dispersion stability of the droplets (particles) of the polymerizable vinyl monomer is deteriorated during the polymerization. The polymer particles aggregate and target particles cannot be obtained. On the other hand, when the amount is more than 0.5 parts by weight, the dispersion stability of the polymerizable vinyl monomer (particles) is improved, but a large amount of ion-modified PVA remains on the surface of the obtained polymer particles. Therefore, in the obtained polymer particles, the surface ion-modified PVA adsorbs moisture, and it becomes impossible to impart stable chargeability to the toner in a high humidity environment.

  In the present invention, a water-soluble polymerization initiator is used as the polymerization initiator. Various water-soluble polymerization initiators can be used. Examples of the water-soluble polymerization initiator include persulfate polymerization initiators such as ammonium persulfate, potassium persulfate, and sodium persulfate, benzoyl peroxide, acetyl peroxide, methyl ethyl ketone peroxide, t-butyl peroxide, and dicumyl peroxide. Organic peroxide polymerization initiators such as 2,2-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2-azobis [2- (2-imidazoline-2- Yl) propane] · disulfuric acid · dihydrate, 2,2-azobis (2-amidinopropane) · dihydrochloride, 2,2-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] Hydrate, 2,2-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2- Zobis [2- (2-imidazolin-2-yl) propane], 2,2-azobis (1-imino-1-pyrrolidino-2-ethylpropane) dihydrochloride, 2,2-azobis {2-methyl- N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2-azobis ( N-hydroxyethylisobutyramide), 4,4-azobis (4-cyanopentanoic acid), azobisisobutyronitrile, azobis (2,4dimethylvaleronitrile), and other azo polymerization initiators. In addition, polymerization initiators for persulfates and organic peroxides include sodium sulfooxylate formaldehyde, sodium bisulfite, ammonium bisulfite, sodium thiosulfate, ammonium thiosulfate, hydrogen peroxide, sodium hydroxymethanesulfinate, L-ascorbine. Also included are redox initiators and the like that use acids and reducing agents such as salts thereof, cuprous salts and ferrous salts in combination with polymerization initiators.

  Although a polymerization initiator changes with kinds, it is preferable to use 0.1-5 weight part with respect to 100 weight part of polymeric vinyl monomers.

  The production method of the present invention is a method for producing polymer particles by emulsion polymerization, but a chain transfer agent may be added during the polymerization. Specific examples of the chain transfer agent include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, α-methylstyrene dimer, 2,6-di- Examples thereof include phenolic compounds such as t-butyl-4-methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, and halogenated hydrocarbon compounds such as dichloromethane, dibromomethane, and carbon tetrachloride.

  Here, when emulsion polymerization is started after the polymerizable vinyl monomer is made into fine droplets in an aqueous medium, the monomer droplets are uniformly dispersed and stabilized in the aqueous medium, and the polymerization reaction proceeds uniformly. It is possible to stably obtain very few polymer particles such as. The diameter of the droplet is 5 to 500 microns, with 5 to 200 microns being particularly preferred. If it is smaller than 5 microns or larger than 500 microns, the stabilization of the droplets is hindered and aggregated particles are likely to be generated. As a method for producing the fine droplets, it is preferred to produce the reaction solution by applying a large shear stress, and it is preferred to use a stirrer or a homogenizer.

  The use ratio (weight ratio) of the polymerizable vinyl monomer and the aqueous medium is preferably in the range of 1:20 to 1: 2 for the polymerizable vinyl monomer: aqueous medium. When the ratio of the polymerizable vinyl monomer is less than 1:20, productivity may be deteriorated, which is not preferable. On the other hand, when the ratio of the polymerizable vinyl monomer is more than 1: 2, the stability of the particles during the polymerization is deteriorated, and there is an undesired formation of aggregates of polymer particles after the polymerization. A more preferable use ratio is 1:15 to 1: 3.

  The stirring rotation speed of the polymerization system is preferably 100 to 500 rpm, for example, when a 5 liter reactor is used. Moreover, although superposition | polymerization temperature changes with kinds of the monomer and polymerization initiator to be used, it is preferable that it is 30-100 degreeC, and it is preferable that superposition | polymerization time is 0.5 to 10 hours.

  In addition, the polymer particles can be isolated from the aqueous medium by a known method, such as a spray drying method represented by a spray dryer, or a method of drying by adhering to a heated rotating drum represented by a drum dryer. It can be carried out by a freeze-drying method or the like. In addition, when agglomerated particles are generated during drying, it is preferable to crush with a crusher or the like.

  The optimum particle diameter of the polymer particles obtained by the production method of the present invention can be set depending on the application. The polymer particles obtained by the production method of the present invention have a particle diameter of 0.1 to 1.0 μm so as to exhibit good performance when used as an electrophotographic toner external additive. It is preferable to have an average particle size. When the particle diameter of the polymer particles is less than 0.1 μm, when used as an electrophotographic toner external additive, sufficient fluidity cannot be imparted to the toner, and the performance as a toner becomes insufficient. On the other hand, if the particle size of the polymer particles is larger than 1.0 μm, when used as an external toner additive for electrophotography, the toner surface tends to be detached, so that the toner has sufficient fluidity. The toner cannot be applied, and the toner performance is insufficient. In addition, the measuring method of an average particle diameter is described in the Example column.

  Thus, according to the present invention, it is possible to provide a method for producing polymer particles that are excellent in polymerization stability, do not change the amount of moisture adsorption due to environmental changes, and have excellent solvent resistance. In addition, the polymer particles obtained by the production method of the present invention can impart a stable charge amount to the electrophotographic toner, so that the electrophotographic toner can be of higher quality, and can be used for electrophotography and copying. It is suitably used as an external additive for toners for machines and printers.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to this. The monomer droplet diameter, polymerization stability, average particle diameter, moisture adsorption amount (change rate T of moisture adsorption amount rate), and solvent resistance in Examples and Comparative Examples are described below.

(Monomer droplet diameter)
The term “monomer droplet diameter” as used herein means the diameter of polymerizable vinyl monomer droplets dispersed in an aqueous medium. That is, a polymerizable vinyl monomer is added to an aqueous medium, and a sufficiently dispersed reaction liquid is observed with an optical microscope, and the diameter of 30 droplets clearly reflected is measured, and the arithmetic average value is calculated as the monomer droplet diameter. It was.

(Polymerization stability)
Polymerization stability here means the aggregate production rate (%) calculated by the following formula. The smaller the aggregate production rate (%), the better the polymerization stability. Therefore, the agglomeration rate (%) is preferably less than 0.5%. That is, the entire amount of the aqueous dispersion of polymer particles obtained was passed through a stainless steel sieve having an opening of 100 μm, and the residue on the sieve was dried at 50 ° C. for 24 hours, and then the weight (Wa) of the residue was weighed. The aggregate production rate (%) was calculated by the following formula.
Aggregate formation rate = (Wa / polymerizable vinyl monomer use amount) × 100

(Average particle size)
The average particle diameter here means a particle diameter measured using a method called a dynamic light scattering method. That is, an aqueous dispersion of polymer particles obtained by emulsion polymerization is diluted with ion-exchanged water (for example, 200 times) to prepare 0.1 wt%, and irradiated with laser light at 25 ° C. The intensity of the scattered light scattered from the light is measured over time in microseconds. The average particle size obtained by a cumulant analysis method for calculating the average particle size by applying the scattering intensity distribution caused by the detected polymer particles to the normal distribution. This type of average particle size can be easily measured with a commercially available measuring apparatus. In this example, “Zeta Sizer-Nano ZS” commercially available from Malvern is used for measurement.
The above-described commercially available measurement apparatus is equipped with data analysis software, and can automatically analyze measurement data.

(Change rate of moisture adsorption)
The amount of moisture adsorbed here means a value calculated from the amount of change in weight before and after storage after storing the polymer particles in a constant temperature and humidity environment for a predetermined time. That is, the polymer particles were previously dried at 55 ° C. for 24 hours, and 1 g of the dried polymer particles was stored in an atmosphere at a temperature of 20 ° C. and a relative humidity of 80% for 1 hour, and then the weight (g) of the polymer particles was determined. Weigh. This value and W _80, and a (1) Water adsorption ratio sigma _{80 (%)} of the polymer particles a value obtained by calculation from the equation.
Moisture adsorption rate σ ₈₀ (%) = (W ₈₀ −1) × 100 (1)
After storing for 1 hour at a temperature of 20 ° C. and a relative humidity of 40% by the same method, the weight (g) of the polymer particles is weighed, and this value is set as W ₄₀ , and W ₈₀ in the formula (1) is set to W ₄₀ . The calculated value was changed to the moisture adsorption rate σ ₄₀ . Next, the rate of change (expressed as T) of the moisture adsorption rate measured by the weight between the relative humidity of 40% and 80% was calculated by the following equation (2).
T = [(σ ₄₀ −σ ₈₀ ) / σ ₄₀ ] × 100
Here, the smaller the rate of change T, the less moisture is adsorbed even under high humidity, and it is stable against changes in the humidity environment.

(Solvent resistance)
1 g of polymer particles and 10 g of toluene were added to a 20 ml centrifuge tube, shaken well, allowed to stand at room temperature for 24 hours, and then centrifuged at 6000 rpm for 5 minutes to observe the state of the polymer particles. Here, it was determined that the polymer particles were not dissolved at the bottom of the centrifuge tube.

  The pseudo toner production method (a) and blow-off charge amount measurement method (b) will be described below.

(A) Method for producing pseudo toner In a 5 L autoclave, 26 parts by weight of magnesium pyrophosphate is dispersed in 2600 parts by weight of water, 0.13 parts by weight of sodium nitrite, Phosphanol LO-529 (manufactured by Toho Chemical Co., Ltd.) 1.3 parts by weight were dissolved. A mixed solution of 910 parts by weight of styrene and 390 parts by weight of butyl methacrylate in which 10.4 parts by weight of azobisisobutyronitrile, 3.9 parts by weight of t-butyl peroxy-2-ethylhexanoate was dissolved. Was dispersed with a homogenizer at 4000 rpm, and then treated with a nanomizer system LA-33 (manufactured by Nanomizer Co., Ltd.) at a treatment pressure of 0.5 MPa to obtain a dispersion. The resulting dispersion was heated at 60 ° C. for 6 hours with stirring at 450 rpm. Thereafter, 1.3 parts by weight of sulfamic acid and 100 parts by weight of water in which 2.6 parts by weight of sodium dodecylbenzenesulfonate were dissolved were added, and the mixture was heated to 110 ° C. and further polymerized while continuing stirring for 1 hour. . Thereafter, the mixture was cooled to room temperature and dehydrated and dried to obtain toner particles. The average particle diameter of the obtained toner particles was 10 μm.

  15 g of the toner particles and 0.45 g of the electrophotographic toner external additive (polymer particles produced according to the present invention) were mixed for 5 seconds with a mill mixer (National MX-X57-Y fiber mixer), and then statically left for 1 minute. Stored. The mixture was again mixed for 5 seconds and kept still for 1 minute, and this operation was performed a total of 5 times to obtain a pseudo toner.

(B) Measurement method of blow-off charge amount In the above method, 0.5 g of pseudo toner and 9.5 g of standard carrier N-02 (manufactured by the Imaging Society of Japan) were put in a 50 cc polypropylene container, sealed, and then up and down 200 times. Mix by shaking. Thereafter, the container was opened and allowed to stand for 24 hours under constant temperature and humidity of 20 ° C. and a relative humidity of 60%. Next, 0.2 g of the sample was weighed and put into a measurement sample chamber containing a 400 mesh screen to measure the blow-off charge amount. In addition, this kind of blow-off charge amount can be easily measured with a commercially available measuring apparatus, and TB-203 commercially available from Kyocera Chemical Co., Ltd. was used in this example. The measurement was performed under constant temperature and humidity of 20 ° C. and a relative humidity of 60%, nitrogen gas was used for blowing, the blowing pressure was 10 kPa, and the suction pressure was 9 kPa.
From the measured value of the blow-off charge amount of the pseudo toner, the chargeability was evaluated according to the following criteria.
In addition, the reference value of the following blow-off charge amount is an absolute value.
○: Excellent chargeability (blow-off charge amount 20-40 μC / g)
×: Inferior in chargeability (blow-off charge amount 20 μC or less / g)

(Example 1).
In a 5 L autoclave equipped with a stirrer, a reflux condenser, and a thermometer, 0.8 parts by weight of cationic modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd .: CM-318, amino group-modified PVA) was deoxygenated. Dissolved in 3200 parts by weight of ion-exchanged water, 640 parts by weight of methyl methacrylate (MMA) and 160 parts by weight of allyl methacrylate (AMA) were supplied, and a homogenizer (Special Machine Industries, Ltd .: TK HOMOMIXER MARK) The mixture was stirred according to II) to prepare a dispersion having a monomer droplet diameter of 500 μm. In this dispersion, 2,2-azobis (2-amidinopropane) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd .; decomposition temperature for obtaining a half-life of 10 hours: 56 ° C.) 4 parts by weight Was added to the dispersion, and the dispersion was heated to 70 ° C., followed by emulsion polymerization while continuing stirring at 70 ° C. for 3 hours, and then cooled to room temperature and dried by spray drying to obtain polymer particles. The obtained polymer particles had an average particle size of 0.324 μm, an aggregate formation rate of 0.2%, a rate of change in moisture adsorption amount of 20%, and excellent solvent resistance. According to this production method, it has been found that polymer particles having a small rate of change in moisture adsorption and excellent solvent resistance can be obtained very stably.

(Example 2)
Polymer particles were obtained in the same manner as in Example 1 except that the cationic modified polyvinyl alcohol was changed to 0.4 part by weight and the monomer droplet diameter was changed to 5 μm. The obtained polymer particles had an average particle size of 0.501 μm, an aggregate formation rate of 0.1%, a moisture adsorption rate change rate of 15%, and excellent solvent resistance. According to this production method, it has been found that polymer particles having a small rate of change in moisture adsorption and excellent solvent resistance can be obtained very stably.

(Example 3)
Polymer particles were obtained in the same manner as in Example 2 except that the amount of the cationic modified polyvinyl alcohol was changed to 0.8 parts by weight. The obtained polymer particles had an average particle size of 0.431 μm, an aggregate formation rate of 0.0%, a moisture adsorption rate change rate of 20%, and excellent solvent resistance. According to this production method, it has been found that polymer particles having a small rate of change in moisture adsorption and excellent solvent resistance can be obtained very stably.

Example 4
Polymer particles were obtained in the same manner as in Example 2 except that the cationic modified polyvinyl alcohol was changed to 4.0 parts by weight. The obtained polymer particles had an average particle size of 0.398 μm, an aggregate formation rate of 0.0%, a moisture adsorption rate change rate of 25%, and excellent solvent resistance. According to this production method, it has been found that polymer particles having a small rate of change in moisture adsorption and excellent solvent resistance can be obtained very stably. A pseudo toner was prepared using the polymer particles as an electrophotographic toner external additive, and the blow-off charge amount was measured. As a result, it was +29 μC / g and had excellent chargeability.

(Example 5)
Polymer particles were obtained in the same manner as in Example 1 except that the monomer droplet diameter was changed to 100 μm. The obtained polymer particles had an average particle size of 0.350 μm, an aggregate formation rate of 0.1%, a moisture adsorption rate of change of 20%, and excellent solvent resistance. According to this production method, it has been found that polymer particles having a small rate of change in moisture adsorption and excellent solvent resistance can be obtained very stably.

(Example 6)
Polymer particles were obtained in the same manner as in Example 1 except that methyl methacrylate (MMA) was changed to 480 parts by weight, allyl methacrylate (AMA) was changed to 320 parts by weight, and the monomer droplet diameter was changed to 50 μm. . The obtained polymer particles had an average particle size of 0.345 μm, an aggregate formation rate of 0.2%, a rate of change of moisture adsorption amount of 17%, and were excellent in solvent resistance. According to this production method, it has been found that polymer particles having a small rate of change in moisture adsorption and excellent solvent resistance can be obtained very stably.

(Example 7)
0.8 parts by weight of cationic modified polyvinyl alcohol is added to 0.8 parts by weight of anionic modified polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: L-3266, sulfonic acid group-modified PVA), and the monomer droplet diameter is 50 μm. Except for the change, polymer particles were obtained in the same manner as in Example 1. The obtained polymer particles had an average particle size of 0.332 μm, an agglomerate production rate of 0.1%, a moisture adsorption amount change rate of 20%, and excellent solvent resistance. According to this production method, it has been found that polymer particles having a small rate of change in moisture adsorption and excellent solvent resistance can be obtained very stably. A pseudo toner was prepared using the polymer particles as an external additive for electrophotographic toner, and the blow-off charge amount was measured. As a result, it was -30 μC / g and had excellent chargeability.

(Comparative Example 1)
Polymer particles were obtained in the same manner as in Example 5, except that the cationic modified polyvinyl alcohol was changed to 0.16 parts by weight and the monomer droplet diameter was changed to 100 μm. The obtained polymer particles had an average particle size of 0.375 μm, an aggregate formation rate of 5.1%, a rate of change in moisture adsorption amount of 12%, and had solvent resistance. In this production method, although the rate of change in the amount of moisture adsorption is small and polymer particles having solvent resistance can be obtained, the polymerization stability is extremely poor.

(Comparative Example 2)
Polymer particles were obtained in the same manner as in Comparative Example 1, except that the cationic modified polyvinyl alcohol was changed to 8.0 parts by weight. The obtained polymer particles had an average particle size of 0.301 μm, an agglomerate production rate of 0.1%, a moisture adsorption rate change rate of 50%, and had solvent resistance. In this production method, polymer particles having good polymerization stability and solvent resistance can be obtained, but it has been found that the rate of change in the amount of moisture adsorption becomes very large. A pseudo toner was prepared using the polymer particles as an external additive for electrophotography, and the blow-off charge amount was measured. As a result, it was +15 μC / g, and the chargeability was poor.

(Comparative Example 3)
Polymer particles were obtained in the same manner as in Example 1 except that methyl methacrylate (MMA) was changed to 796 parts by weight and allyl methacrylate (AMA) was changed to 4 parts by weight. The obtained polymer particles have an average particle size of 0.324 μm, an aggregate formation rate of 0.1%, and a moisture adsorption amount change rate of 22%. The polymer particles are dissolved in a solvent, and the solvent resistance is improved. Did not have. In this production method, polymer particles having good polymerization stability and a small rate of change in the amount of moisture adsorption can be obtained, but particles having solvent resistance cannot be obtained, and the charge control agent and the like are absorbed. Is inappropriate.

(Comparative Example 4)
The same procedure as in Example 1 was conducted except that methyl methacrylate (MMA) was changed to 240 parts by weight and allyl methacrylate (AMA) was changed to 560 parts by weight. It was not obtained.

  According to the method for producing polymer particles of the present invention, it has a very good polymerization stability, and there is little change in moisture adsorption amount even when changing from a low-humidity environment to a high-humidity environment. Combined particles can be obtained. Therefore, it exhibits an excellent function as an external additive for an electrophotographic toner used for electrostatic image development. In addition, using such properties, for example, it is also used as a raw material for additives for carriers, additives for powder coating, top coats for civil engineering materials, sealers, ink jet recording materials, electrodeposition paints, etc. be able to.

Claims (2)

  In the presence of 0.05 to 0.5 parts by weight of ion-modified vinyl alcohol, 100 parts by weight of a polymerizable vinyl monomer comprising a (meth) acrylic acid ester monomer and 10 to 60% by weight of allyl (meth) acrylate. A method for producing polymer particles, which is emulsion-polymerized in an aqueous medium without adding a surfactant. The manufacturing method according to claim 1,
A method for producing polymer particles, comprising polymerizing a polymerizable vinyl monomer after obtaining a state in which a droplet diameter of the polymerizable vinyl monomer is 5.0 to 500 μm.