JP2011184544A - Polymer particle, process for production thereof, and external additive for toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer particle which is used as an external additive for a toner capable of imparting sufficient fluidity to electrophotographic toner, and a process for production thereof. <P>SOLUTION: The polymer particle is derived from a monomer mixture comprising a monofunctional vinyl monomer and urethane poly(meth)acrylate. The polymer particle has an average particle size of 0.05-1 μm. The percentage of the monofunctional vinyl monomer and the urethane poly(meth)acrylate which may be used is 60-95 wt.% and 40-5 wt.%, respectively. The urethane poly(meth)acrylate comprises a urethane moiety having a molecular weight of 200-5,000 and two or more (meth)acrylate groups. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to polymer particles, a method for producing the same, and an external additive for toner, and more specifically, as an external additive for electrophotographic toner that can be added to an electrophotographic toner to give sufficient fluidity to the toner. The present invention relates to usable polymer particles and a method for producing the same.

  In electrophotography and electrostatic recording, an electrostatic charge image is formed on a photoreceptor or electrostatic recording body, and the electrostatic charge image is developed using electrophotographic toner by a magnetic brush development method, a cascade development method, or the like. As a result, a toner image is formed, and this is transferred and fixed on a copy paper or the like to form a copy. Various additives (hereinafter referred to as “electrophotographic toner external additive” or “external toner additive”) are added to the electrophotographic toner used in the electrophotographic method and the electrostatic recording method. Thus, it is known that the toner performance can be improved.

  Fine particles used as an external additive for toner are required to have an average particle size smaller than that of electrophotographic toner, to have a uniform shape and size, and to impart sufficient fluidity and chargeability to the toner. . Such an external additive for the toner can improve various performances of the toner by entering between the toner particles to prevent adhesion between the toner particles or imparting fluidity to the toner.

  Conventionally, inorganic particles such as silica, titania and alumina or fine particles obtained by hydrophobizing the surface of these inorganic particles have been used as particles used for the external additive for toner. However, such an external additive for toner made of an inorganic material has a particle size of 0.05 μm or less and is too small and too hard to be externally added to the toner particle. There is a problem that the toner can be easily embedded or detached from the toner particles, and the toner cannot be provided with sufficient fluidity.

  As a technique for solving such a problem, an external additive for toner composed of polymer particles obtained by emulsion polymerization of a styrene-based or acrylic polymerizable monomer is known (Patent Documents 1 to 3). 3). Moreover, the manufacturing method of the urethane-acrylic particle internal mixture water dispersion is known (refer patent document 4).

Japanese Patent Publication No. 2-3172 JP-A-5-333585 JP 2003-295501 A Japanese Patent No. 43809090

  However, in the polymer particles described in Patent Documents 1 to 4, since the mechanical strength is too small, the external additive for toner is deformed or crushed on the toner particle surface. As a result, it has been found that the effect of preventing adhesion between toner particles cannot be provided, and the function of the toner for electrophotography may be deteriorated. In addition, as a means for improving the mechanical strength of polymer particles, it is generally known to crosslink polymer particles by copolymerizing bifunctional polymerizable monomers such as divinylbenzene and alkylene glycol dimethacrylate. Yes. However, even with such a method, the deformation and crushing of the toner external additive cannot be sufficiently suppressed, and the functional deterioration of the electrophotographic toner cannot be prevented.

  The present invention solves the above-mentioned problems, and an object of the present invention is to provide polymer particles that can be used as an external additive for toner capable of imparting sufficient fluidity to an electrophotographic toner. And a manufacturing method thereof.

  The inventors of the present invention believe that polymer particles derived from a monomer mixture containing urethane poly (meth) acrylate having a predetermined molecular weight and a monofunctional vinyl monomer in a predetermined ratio are suitable for toner as an external additive for toner. The present invention has been achieved by surprisingly finding that fluidity is imparted.

  Thus, according to the present invention, the polymer particles are derived from a monomer mixture containing a monofunctional vinyl monomer and urethane poly (meth) acrylate, and the polymer particles have an average particle diameter of 0.05 to 1 μm. The monofunctional vinyl monomer used and the urethane poly (meth) acrylate are in a proportion of 60 to 95% by weight and 40 to 5% by weight, and the urethane poly (meth) acrylate is a urethane having a molecular weight of 200 to 5,000. There is provided a polymer particle comprising a portion and two or more (meth) acrylate groups.

  In addition, according to the present invention, there is provided an external additive for toner comprising the above polymer particles.

  Furthermore, according to the present invention, there is provided a method for producing the polymer particle, wherein the monomer mixture contains a monofunctional vinyl monomer and urethane poly (meth) acrylate in a proportion of 60 to 95% by weight and 40 to 5% by weight. There is provided a method for producing polymer particles, wherein the polymer particles are obtained by emulsion polymerization in an aqueous medium in the presence of a surfactant and a water-soluble polymerization initiator.

The polymer particles of the present invention can impart sufficient fluidity to toner particles used in electrophotographic toners as external additives for toners, so that electrostatic particles in electrophotography, electrostatic recording, electrostatic printing, etc. Good development of the latent image can be realized. Therefore, it is suitably used for toners for electrophotography, copying machines, printers, and the like.
Further, when the urethane poly (meth) acrylate has 2 to 5 (meth) acrylate groups, the polymer particles of the present invention can impart excellent fluidity to the toner particles as an external additive for toner. it can.
The external additive for toner comprising the polymer particles of the present invention can realize good development of an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing and the like.

  In addition, as described above, the method for producing polymer particles according to the present invention makes it possible to produce polymer particles that can impart sufficient fluidity to toner particles as an external additive for toner.

It is a SEM image which shows the state which the polymer particle (external additive for toners) by Example 1 of this invention has adhered to the surface of the pseudo toner particle. It is a SEM image which shows the state which the polymer particle (external additive for toners) by the comparative example 2 of this invention has adhered to the pseudo toner particle surface.

  The polymer particles according to the present invention (hereinafter also simply referred to as particles) are polymer particles derived from a monomer mixture containing a monofunctional vinyl monomer and urethane poly (meth) acrylate. The average particle diameter of the polymer particles is 0.05 to 1 μm. The monofunctional vinyl monomer and urethane poly (meth) acrylate used are in a proportion of 60 to 95% by weight and 40 to 5% by weight. Urethane poly (meth) acrylate is composed of a urethane portion having a molecular weight of 200 to 5000 and two or more (meth) acrylate groups. (Meth) acryl refers to acryl or methacryl.

  The monofunctional vinyl monomer means a monomer having one carbon-carbon unsaturated double bond. The monofunctional vinyl monomer used in the present invention is preferably a styrene monomer or a (meth) acrylic ester monomer.

  Examples of the styrene monomer include styrene, p-methylstyrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-ethylstyrene, and the like. It is done. Of these, styrene is particularly preferable.

Examples of (meth) acrylic ester monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, ( T-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylic acid Examples include tridecyl, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like.
Each of the above styrene monomers or (meth) acrylic ester monomers may be used alone, or two or more of them may be used in combination.

  Urethane poly (meth) acrylate refers to a compound obtained by reacting a reaction product of a polyol and an organic polyisocyanate with a hydroxyl group-containing (meth) acrylate. For example, urethane di (meth) acrylate, isophorone diisocyanate obtained by reacting (meth) acrylate having a hydroxy group such as 2-hydroxypropyl (meth) acrylate with diisocyanate such as 1,6-hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate 2-Hydroxyethyl (meth) acrylate is a reaction product of urethane hex (meth) acrylate obtained by reacting pentaerythritol tri (meth) acrylate with dicyclomethane diisocyanate and poly (repeating unit n = 6 to 15) tetramethylene glycol. And polyurethane di (meth) acrylate reacted with acrylate.

  The urethane poly (meth) acrylate used in the present invention has a plurality of radically polymerizable (meth) acrylate groups at the end of the urethane oligomer. Urethane oligomer is a copolymer of isocyanate and polyol.

  The number of the (meth) acrylate groups of the urethane poly (meth) acrylate may be 2 or more, and 2 to 5 are preferable. More preferably, it is 2-3. When the number of (meth) acrylate groups is less than 2, when used as an external additive for electrophotographic toner, the particles may be crushed during external addition. On the other hand, when the number is more than 5, the polymerization stability at the time of emulsion polymerization is lowered, and the aggregation or coalescence of particles may occur during the polymerization. In this case, the average particle size of the obtained particles may exceed 1.0 μm, and may not fall within the range of particle sizes preferable as an external additive for toner.

  The molecular weight of the urethane moiety of the urethane poly (meth) acrylate is 200 to 5000. More preferably, it is 300-4500. When the molecular weight is less than 200, the mechanical strength of the particles becomes poor, and the particles may be crushed during external addition. On the other hand, when it exceeds 5000, the polymerization stability at the time of emulsion polymerization decreases, and the particles may aggregate or coalesce during the polymerization.

  Specific examples of urethane poly (meth) acrylate include New Frontier R-1214, R-1220, R-1301, R-1304, R-1308, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and EBECRYL 204, 205, manufactured by Daicel Cytec. 210, 220, 230, 270, High Cope AU manufactured by Tokushi Corporation, Urethane Acrylate AH-600, AT-600, UA-306H manufactured by Kyoeisha Chemical Co., Ltd., Urethane Acrylate Oligomer CN-980, 981 manufactured by Sartomer, and the like.

  The mixing ratio of the monofunctional vinyl monomer and urethane poly (meth) acrylate is preferably 60 to 95% by weight and 40 to 5% by weight. More preferably, they are 70-90 weight% of monofunctional vinyl monomers, and 30-10 weight% of urethane poly (meth) acrylates. When the proportion of urethane poly (meth) acrylate is less than 5% by weight, when used as an external additive for electrophotographic toner, particles may be crushed during external addition. On the other hand, when it is more than 40% by weight, the polymerization stability at the time of emulsion polymerization is lowered, and the aggregation or coalescence of particles may occur during the polymerization. In this case, the average particle size of the obtained particles may exceed 1.0 μm, and may not fall within the range of particle sizes preferable as an external additive for toner.

  In addition to the monofunctional vinyl-based monomer and urethane poly (meth) acrylate, other monomers and additives may be added to the polymer particles of the present invention as long as the effects of the present invention are not impaired.

  Examples of other monomers include polyfunctional polymerizable vinyl monomers. Specific examples include divinylbenzene and alkylene glycol dimethacrylate (alkylene preferably has 2 to 4 carbon atoms). The mixing ratio of the polyfunctional polymerizable vinyl monomer is preferably 50 parts by weight or less with respect to 100 parts by weight of the monofunctional vinyl monomer. More preferably, it is 0.1 to 40 parts by weight.

  Examples of other additives include a light stabilizer, an ultraviolet absorber, a pigment, a dye, an antifoaming agent, a thickener, a heat stabilizer, a leveling agent, a lubricant, and an antistatic agent.

  The average particle diameter of the polymer particles of the present invention is preferably 0.05 to 1 μm. More preferably, it is 0.08-0.6 micrometer. If it is smaller than 0.05 μm or larger than 1 μm, sufficient fluidity may not be imparted to the electrophotographic toner when used as an external toner additive.

  In the present invention, the polymerization method for obtaining polymer particles is carried out by emulsion polymerization. Emulsion polymerization is a polymerization method in which an aqueous medium, a monomer that is difficult to dissolve in the medium, and an emulsifier (surfactant) are mixed, and a polymerization initiator that is soluble in the medium is added to the mixture. Advantages of emulsion polymerization include that a polymer having a high degree of polymerization can be easily obtained at a high speed and that the temperature can be easily adjusted in order to obtain an aqueous medium. Hereinafter, although an example of the manufacturing method of the polymer particle by emulsion polymerization is demonstrated, this invention is not limited only to this manufacturing method.

  A monomer mixture containing a monofunctional vinyl monomer and urethane poly (meth) acrylate, and optionally other monomers, an additive, a surfactant and a water-soluble polymerization initiator are added and mixed to obtain a mixture. The obtained mixture is put into an aqueous medium and stirred at a predetermined temperature for a predetermined time to accelerate the polymerization reaction. Examples of a method for supplying the monomer and the like include a method in which the monomers are charged into the reaction system at once, or a method in which the monomers are supplied dropwise. In addition, as an aqueous medium, the mixture of water or water and a water-soluble solvent (for example, lower alcohol) is mentioned. Moreover, you may perform superposition | polymerization in inert atmosphere like nitrogen.

The surfactant used in the emulsion polymerization to obtain polymer particles may be a known one such as an anionic surfactant, a cationic surfactant, a zwitterionic surfactant, a nonionic surfactant, or the like. Good.

  Examples of the anionic surfactant include non-reactive anionic surfactants such as alkylbenzene sulfonate, alkyl diphenyl ether sulfonate, dialkyl sulfosuccinate and monoalkyl sulfosuccinate, polyoxyethylene-1- ( And reactive anionic surfactants such as allyloxymethyl) alkyl ether sulfate ammonium salt, polyoxyethylene alkylpropenyl phenyl ether sulfate ammonium salt, and polyoxyalkylene alkenyl ether ammonium sulfate.

  Examples of the cationic surfactant include lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetylmethylammonium chloride and distearyldimethylammonium chloride N-polyoxyalkylene-N, N, N-trialkylammonium salt. .

Examples of the zwitterionic surfactant include lauryl dimethylamine oxide and phosphate ester or phosphite ester surfactants.
Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxy Examples include ethylene-oxypropylene block polymers.

  The addition amount of the surfactant varies depending on the type, but is preferably 0.03 to 0.3 parts by weight with respect to 100 parts by weight of the total amount of the monofunctional vinyl monomer and urethane poly (meth) acrylate. More preferably, it is 0.05 to 0.2 parts by weight. If it is less than 0.03 parts by weight, sufficient fluidity may not be imparted to the toner. On the other hand, when the amount exceeds 0.3 parts by weight, the dispersion stability of the polymer particles may be deteriorated, and the polymer particles may aggregate after the polymerization, and sufficient fluidity may not be imparted to the toner.

  The water-soluble polymerization initiator is not particularly limited, and examples thereof include persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate, benzoyl peroxide, acetyl peroxide, methyl ethyl ketone peroxide, and t-butyl. Organic peroxides such as peroxide and dicumyl peroxide, 2,2-azobis [2- (2-imidazolin-2-yl) propane] hydrogen dichloride, 2,2-azobis [2- (2-imidazoline) -2-yl) propane] disulfate dihydrate, 2,2-azobis (2-amidinopropane) hydrogen dichloride, 2,2-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] Hydrate, 2,2-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} Hydrogen chloride, 2,2-azobis [2- (2-imidazolin-2-yl) propane], 2,2-azobis (1-imino-1-pyrrolidino-2-ethylpropane) hydrogen dichloride, 2,2- Azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], Azo compounds such as 2,2-azobis (N-hydroxyethylisobutyramide), 4,4-azobis (4-cyanopentanoic acid), azobisisobutyronitrile, azobis (2,4dimethylvaleronitrile), etc. Can be mentioned. The persulfates and organic peroxides include sodium sulfooxylate formaldehyde, sodium bisulfite, ammonium bisulfite, sodium thiosulfate, ammonium thiosulfate, hydrogen peroxide, sodium hydroxymethanesulfinate, L-ascorbic acid and its Examples also include redox initiators that use a reducing agent such as a salt, cuprous salt, and ferrous salt in combination with a polymerization initiator.

  Although the addition amount of a water-soluble polymerization initiator changes with kinds, 0.1-5 weight part is preferable with respect to 100 weight part of total amounts of a monofunctional vinyl-type monomer and urethane poly (meth) acrylate. More preferably, it is 0.3 to 3 parts by weight.

  When emulsion polymerization is performed in the present invention, a chain transfer agent may be added. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, and α-methylstyrene. Examples include dimer, phenol compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, and halogenated hydrocarbon compounds such as dichloromethane, dibromomethane, and carbon tetrachloride. It is done. The addition amount of the chain transfer agent is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the monomer mixture containing the monofunctional vinyl monomer and urethane poly (meth) acrylate. More preferably, it is 0.3 to 3 parts by weight.

  The ratio of the monomer mixture containing the monofunctional vinyl monomer and urethane poly (meth) acrylate and the aqueous medium is preferably in the range of 1:20 to 1: 2. More preferably, it is 1:15 to 1: 3. When the ratio of the monomer mixture is less than 1:20, productivity may be deteriorated. If the ratio of the monomer mixture is larger than 1: 2, the stability of the particles during polymerization may be deteriorated, and aggregates of polymer particles after polymerization may occur.

  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 2 to 10 hours.

  After polymerization is complete, the polymer particles are isolated from the aqueous medium. As the isolation method, a known method such as a spray drying method typified by a spray dryer, a method of drying by adhering to a heated rotating drum typified by a drum dryer, or a freeze drying method can be used. Desirably, the dried polymer particles are deagglomerated with a pulverizer or a pulverizer.

The polymer particles obtained by the above method can be suitably used as an external additive for an electrophotographic toner.
The polymer particles can be externally added to the electrophotographic toner resin by conventional methods and conditions such as a mechanical pulverization and mixing method. For example, a mill mixer, a Henschel mixer, a V-type mixer, Using a mixer, a hybridizer, a rocking mixer or the like, the polymer particles and the binder resin for electrophotographic toner can be mixed and stirred.

  The electrophotographic toner resin is not particularly limited. For example, styrene resin, styrene-acrylic resin, styrene-butadiene resin, styrene-maleic resin, styrene-vinyl methyl ether resin, styrene-methacrylic acid. Examples include synthetic resins such as ester resins, polyester resins, phenol resins, and epoxy resins.

  For example, when 1 to 5 parts by weight of polymer particles according to the present invention are externally added to 100 parts by weight of styrene-acrylic resin having an average particle diameter of 10 μm as an electrophotographic toner resin using a mill mixer, Since the mechanical strength of the coalesced particles is excellent, the particles can be externally added to the surface of the toner resin without being crushed, the adhesion between the toners can be effectively prevented, and the fluidity of the toner is improved. As a result, excellent printability can be realized.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
First, a method for measuring the average particle diameter in Examples and Comparative Examples and a method for evaluating the fluidity of toner particles to which polymer particles (external additive for toner) are externally added will be described.

(Measurement method of average particle size)
The average particle diameter here means a particle diameter measured using a method called a dynamic light scattering method or a photon correlation method. Specifically, an aqueous dispersion of acrylic polymer particles obtained by emulsion polymerization is prepared to be 0.1 wt% by diluting 200 times with ion-exchanged water, and irradiated with laser light at 25 ° C. The intensity of scattered light scattered from the polymer particles is measured with time change in units of microseconds. The numerical value calculated by the cumulant analysis method for the distribution of scattering intensity caused by the measured polymer resin particles is the average particle diameter. The cumulant analysis method is a method of analyzing by applying a normal distribution to calculate the average particle size. The average particle diameter by this method can be easily measured with a commercially available measuring apparatus. In the examples, “Zeta Sizer Nano ZS” manufactured by Malvern is used for measurement. Such a commercially available measuring apparatus is equipped with data analysis software, and the measured data is automatically analyzed.

(Evaluation method for fluidity)
In the present invention, the fluidity is evaluated by the sieve passing rate. The sieve passing rate means a measured value of the sieve passing rate using a powder tester manufactured by Hosokawa Micron. As a measurement sample, an external additive for electrophotographic toner composed of polymer particles obtained in Examples and Comparative Examples was externally added to binder resin particles for toner (hereinafter referred to as “pseudo toner”). Is used. The pseudo toner is evaluated from the measured value of the sieve passing rate.
The pseudo toner production method (a) and sieve passing rate 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 was dispersed in 2600 parts by weight of water, 0.13 parts by weight of sodium nitrite and phosphanol LO-529 (manufactured by Toho Chemical Co., Ltd.) 1.3 parts by weight are 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-butylperoxy-2-ethylhexanoate was dissolved. Is added and emulsified with a homogenizer at 4000 rpm. By treating the emulsified material with a nanomizer system LA-33 (manufactured by Nanomizer) at a treatment pressure of 0.5 MPa, a dispersion can be obtained. The resulting dispersion is heated at 60 ° C. for 6 hours while stirring at a stirring speed of 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 are dissolved are added, and the mixture is heated to 110 ° C. and further polymerized while continuing stirring for 1 hour. Thereafter, the binder resin for toner is obtained by cooling to room temperature and performing dehydration and drying. The obtained binder resin for toner has an average particle size of 10 μm.
A mixture of 15 g of the binder resin for toner and 0.45 g of the external additive for electrophotographic toner of the present invention was mixed for 5 seconds with a mill mixer (MX-X57-Y fiber mixer manufactured by National), and then allowed to stand for 1 minute. To do. The pseudo toner is obtained by repeating the operation 5 times in total by mixing again for 5 seconds and standing for 1 minute, and repeating this operation a total of 5 times.

(B) Method for Measuring Screen Passage First, 2 g of the pseudo toner obtained by the production method (a) is placed on a metal screen having a mesh size of 45 μm. Next, a rheostat voltage of 7.2 V is applied to a powder tester manufactured by Hosokawa Micron, and the sieve is vibrated for 93 seconds. After the vibration is finished, the weight of the powder remaining on the sieve is measured, and the value calculated by the following formula is defined as the sieve passing rate.
Sieve passing rate (%) = 100 − {(weight of powder remaining on sieve / 2 g) × 100}
The measured value of the passing rate of the pseudo toner is evaluated according to the following criteria.
○: Excellent fluidity can be imparted (sieving rate of 80% or more)
X: Poor fluidity-imparting effect (screening rate less than 80%)

Example 1
In a 5 L reactor equipped with a stirrer and a thermometer, 400 parts by weight of ion-exchanged water, anionic surfactant, polyoxyethylene-1- (allyloxymethyl) alkyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd.) Product name: AQUALON KH1025 (25% aqueous solution)) 0.1 parts by weight, methyl methacrylate 80 parts by weight, urethane poly (meth) acrylate, New Frontier R1214 (Daiichi Kogyo Seiyaku Co., Ltd .: 2 acrylate groups) ) 20 parts by weight was supplied and heated to 70 ° C. while stirring at a stirring speed of 250 rpm. Next, 0.5 part by weight of ammonium persulfate was added as a water-soluble polymerization initiator, and stirring was continued for 2 hours. Thereafter, stirring was further continued at 80 ° C. for 1 hour, and finally, the mixture was cooled to room temperature to obtain an aqueous dispersion of polymer particles. The average particle diameter of the obtained polymer particles was 0.24 μm.

The water dispersion of the above polymer particles is dried with a spray dryer at an air supply temperature of 105 ° C. and an exhaust temperature of 55 ° C., and the resulting powder is treated with an airflow pulverizer to obtain polymer particle powder (toner External additive) was obtained.
A pseudo toner was prepared using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 88%, which was in the range of evaluation (80% or more) in which “◯: excellent fluidity can be imparted”.
When the external additive for toner on the pseudo toner particles was observed with an SEM, the external additive was not crushed on the pseudo toner particles (see FIG. 1).
In addition, printing was performed using an electrophotographic toner having the polymer particles as an external additive, and the non-image portion on the 30000th and subsequent sheets was visually observed. )Met.

(Example 2)
Polymer particles were obtained in the same manner as in Example 1 except that 70 parts by weight of methyl methacrylate and 30 parts by weight of urethane poly (meth) acrylate were used. The average particle diameter of the obtained polymer particles was 0.26 μm.

The water dispersion of the above polymer particles is dried with a spray dryer at an air supply temperature of 105 ° C. and an exhaust temperature of 55 ° C., and the resulting powder is treated with an airflow pulverizer to obtain polymer particle powder (toner External additive) was obtained.
A pseudo toner was prepared using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 89%, which was in the range of evaluation (80% or more) in which “◯: excellent fluidity can be imparted”.
When the external toner additive on the pseudo toner particles was observed with an SEM, the external additive was not crushed on the pseudo toner particles.
In addition, printing was performed using an electrophotographic toner having the polymer particles as an external additive, and the non-image portion on the 30000th and subsequent sheets was visually observed. )Met.

(Example 3)
Polymer particles were obtained in the same manner as in Example 1 except that 90 parts by weight of methyl methacrylate and 10 parts by weight of urethane poly (meth) acrylate were used. The average particle diameter of the obtained polymer particles was 0.22 μm.

The water dispersion of the above polymer particles is dried with a spray dryer at an air supply temperature of 105 ° C. and an exhaust temperature of 55 ° C., and the resulting powder is treated with an airflow pulverizer to obtain polymer particle powder (toner External additive) was obtained.
A pseudo toner was prepared using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 87%, which was in the range of evaluation (80% or more) where “◯: excellent fluidity can be imparted”.
When the external toner additive on the pseudo toner particles was observed with an SEM, the external additive was not crushed on the pseudo toner particles.
In addition, printing was performed using an electrophotographic toner having the polymer particles as an external additive, and the non-image portion on the 30000th and subsequent sheets was visually observed. )Met.

Example 4
Polymer particles were obtained in the same manner as in Example 1 except that urethane poly (meth) acrylate was changed from New Frontier R1214 to New Frontier R1301 (Daiichi Kogyo Seiyaku Co., Ltd .: acrylate group number 3). The average particle diameter of the obtained polymer particles was 0.55 μm.

The water dispersion of the above polymer particles is dried with a spray dryer at an air supply temperature of 105 ° C. and an exhaust temperature of 55 ° C., and the resulting powder is treated with an airflow pulverizer to obtain polymer particle powder (toner External additive) was obtained.
A pseudo toner was prepared using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 83%, which was in the range of evaluation (80% or more) where “◯: excellent fluidity can be imparted”.
When the external toner additive on the pseudo toner particles was observed with an SEM, the external additive was not crushed on the pseudo toner particles.
In addition, printing was performed using an electrophotographic toner having the polymer particles as an external additive, and the non-image portion on the 30000th and subsequent sheets was visually observed. )Met.

(Example 5)
Polymer particles were obtained in the same manner as in Example 1 except that methyl methacrylate was changed to styrene. The average particle diameter of the obtained polymer particles was 0.28 μm.

The water dispersion of the above polymer particles is dried with a spray dryer at an air supply temperature of 105 ° C. and an exhaust temperature of 55 ° C., and the resulting powder is treated with an airflow pulverizer to obtain polymer particle powder (toner External additive) was obtained.
A pseudo toner was prepared using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passage rate was 85%, which was within the range of evaluation (80% or more) in which “◯: excellent fluidity can be imparted”.
When the external toner additive on the pseudo toner particles was observed with an SEM, the external additive was not crushed on the pseudo toner particles.
In addition, printing was performed using an electrophotographic toner having the polymer particles as an external additive, and the non-image portion on the 30000th and subsequent sheets was visually observed. )Met.

(Comparative Example 1)
Polymer particles were obtained in the same manner as in Example 1 except that 50 parts by weight of methyl methacrylate and 50 parts by weight of urethane poly (meth) acrylate were obtained. The average particle diameter of the particles was 1.56 μm, and the intended polymer particles were not obtained.

(Comparative Example 2)
Polymer particles were obtained in the same manner as in Example 1 except that 98 parts by weight of methyl methacrylate and 2 parts by weight of urethane poly (meth) acrylate were used. The average particle diameter of the obtained polymer particles was 0.19 μm.

The water dispersion of the above polymer particles is dried with a spray dryer at an air supply temperature of 105 ° C. and an exhaust temperature of 55 ° C., and the resulting powder is treated with an airflow pulverizer to obtain polymer particle powder (toner External additive) was obtained.
A pseudo toner was prepared using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 68%, which was in the range of evaluation “X: Poor fluidity imparting effect” (less than 80% sieve passing rate).
When the external additive for toner on the pseudo toner particles was observed with an SEM, it was crushed on the pseudo toner particles (see FIG. 2).
Further, when printing was performed using an electrophotographic toner having the polymer particles as an external additive and the non-image area on the 30000th and subsequent sheets was visually observed, there were many stains and there were practical problems (× )Met.

(Comparative Example 3)
Polymer particles are obtained in the same manner as in Example 1 except that ethylene glycol dimethacrylate, which is a bifunctional polymerizable monomer having no urethane moiety, is used instead of the bifunctional urethane poly (meth) acrylate. It was. The average particle diameter of the obtained polymer particles was 0.20 μm.

The water dispersion of the above polymer particles is dried with a spray dryer at an air supply temperature of 105 ° C. and an exhaust temperature of 55 ° C., and the resulting powder is treated with an airflow pulverizer to obtain polymer particle powder (toner External additive) was obtained.
A pseudo toner was prepared using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 71%, and was in the range of evaluation “X: poor fluidity imparting effect” (the sieve passing rate was less than 80%).
When the external additive for toner on the pseudo toner particles was observed with an SEM, it was crushed on the pseudo toner particles.
Further, when printing was performed using an electrophotographic toner having the polymer particles as an external additive and the non-image area on the 30000th and subsequent sheets was visually observed, there were many stains and there were practical problems (× )Met.
Examples 1 to 5 and Comparative Examples 1 to 4 are summarized in Table 1.

MMA: Methyl methacrylate St: Styrene R1214: New Frontier R1214 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (acrylate number 2, molecular weight 2000) (urethane poly (meth) acrylate)
R1301: New Frontier R1301 (3 acrylate groups, 3500 molecular weight) (urethane poly (meth) acrylate) manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
EGDMA: ethylene glycol dimethacrylate KH1025: polyoxyethylene-1- (allyloxymethyl) alkyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd .: trade name “AQUALON KH1025 (25% aqueous solution)”)

The result (evaluation) of Comparative Examples 1 and 2 is that the monofunctional vinyl monomer is not in the range of 60 to 95 parts by weight and the urethane poly (meth) acrylate 5 to 40 is not in the range of parts by weight. Conceivable.
The result (evaluation) of Comparative Example 3 is considered to result from the use of a monomer having no urethane moiety.

Claims (4)

  A polymer particle derived from a monomer mixture containing a monofunctional vinyl monomer and urethane poly (meth) acrylate, wherein the polymer particle has an average particle diameter of 0.05 to 1 μm and is used. Monomer and urethane poly (meth) acrylate in a proportion of 60 to 95% by weight and 40 to 5% by weight, urethane poly (meth) acrylate having a urethane part having a molecular weight of 200 to 5000 and two or more A polymer particle comprising a (meth) acrylate group.   The polymer particle according to claim 1, wherein the urethane poly (meth) acrylate has 2 to 5 (meth) acrylate groups.   An external additive for toner comprising the polymer particles according to claim 1.   It is a manufacturing method of the polymer particle of Claim 1 or 2, Comprising: The monomer which contains the said monofunctional vinyl-type monomer and the said urethane poly (meth) acrylate in the ratio of 60 to 95 weight% and 40 to 5 weight%. A method for producing polymer particles, wherein the polymer particles are obtained by emulsion polymerization in an aqueous medium in the presence of a surfactant and a water-soluble polymerization initiator.