KR20100072715A - Method for preparing toner - Google Patents

Abstract

PURPOSE: A manufacturing method of a toner is provided to simplify the manufacturing process of the toner with a narrow particle size distribution, and to reduce the manufacturing cost. CONSTITUTION: A manufacturing method of a toner comprises the following steps: mixing a latex dispersion solution, a colorant dispersion solution, and a wax dispersion solution at 40~60deg C; cohering particles of the toner by adding a coagulant to the mixture and homogenizing; fusing the cohered toner particles; and cooling the fused toner particles. Latex inside the latex dispersion solution contains styrene moiety. The toner has a core-shell structure.

Description

Method for preparing toner {Method for preparing toner}

The present invention relates to a method for producing toner by emulsion coagulation, and more particularly, to a method for producing a toner capable of producing a toner having a narrow particle size distribution in a simple process.

Generally, toner is prepared by adding a colorant, a charge control agent, a wax, or the like to a thermoplastic resin serving as a binder resin. Further, in order to impart fluidity to the toner or to improve physical properties such as charge control or cleaning property, fine inorganic metal powders such as silica and titanium oxide may be added to the toner as an external additive. As toner production methods, there are physical methods such as grinding method and chemical methods such as suspension polymerization method and emulsion aggregation method.

Among these, the emulsion agglomeration method (see US Patent Nos. 5,916,725, 6,268,103, etc.) consists of preparing a fine emulsion resin particle composition through an emulsion polymerization reaction, and then agglomerating the composition together with pigments in a separate dispersion. . This method has the advantage of making the toner particles spherical by improving the problems such as high cost, wide particle size distribution, and the like in the pulverization method, and adjusting the coagulation conditions.

In general, a method of preparing toner by emulsion coagulation is to aggregate the binder resin, the colorant, and the wax present in the latex phase using a coagulant, and then to produce final toner particles through a fusing process. More specifically, mixing a latex dispersion, a colorant dispersion and a wax dispersion, adding and homogenizing a flocculant to the mixture, agglomerating the homogenized mixture to form toner particles, and fusing the aggregated toner particles. step; And cooling the fused toner particles. At this time, the homogenized mixture at room temperature is first heated to a temperature of 5 to 15 ° C. lower than the glass transition temperature of the latex resin, and then subjected to an agglomeration step. The growth is stopped and then secondly raised to a temperature higher than, for example, the glass transition temperature of the latex resin for fusion. That is, after homogenizing the reaction mixture at room temperature and then coagulating, stopping growth, and fusion and cooling after the second elevated temperature, the coagulation step after homogenization tends to widen the particle size distribution of the toner. . In addition, since the first temperature increase rate has a significant effect on the characteristics of the toner particles, the process is complicated and the manufacturing cost increases as the process control factor increases.

Accordingly, an object of the present invention is to provide a toner manufacturing method in which a toner having a narrow particle size distribution can be obtained in the method of producing toner by emulsion coagulation, which can reduce manufacturing time and cost by reducing process control factors. do.

In order to solve the above problems, the present invention,

Mixing the latex dispersion, the colorant dispersion and the wax dispersion at 40 to 60 ° C;

Agglomerating toner particles by adding and homogenizing a flocculant to the mixture;

Fusing the aggregated toner particles; And

It provides a toner manufacturing method comprising the step of cooling the fused toner particles.

According to one embodiment of the invention, the latex dispersion may be a latex containing a styrene residue.

According to another embodiment of the present invention, the toner may have a core-shell structure.

According to the production method of the present invention, a toner having a narrow particle size distribution can be produced by a simpler process.

Hereinafter will be described in detail with respect to a preferred embodiment of the present invention.

The toner manufacturing method according to the present invention comprises the steps of mixing a latex dispersion, a colorant dispersion and a wax dispersion at 40 to 60 ℃;

Agglomerating toner particles by adding and homogenizing a flocculant to the mixture;

Fusing the aggregated toner particles; And

Cooling the fused toner particles.

In the conventional method for preparing toner by emulsion coagulation, a coagulant is added to the reaction mixture at room temperature, homogenized, and then the toner particles are agglomerated at a first elevated temperature, and the toner particles are fused at a second elevated temperature. By adding and homogenizing the flocculant to the mixture, there is no need to control the primary temperature rise rate for flocculation as in the prior art, which shortens the process time, reduces the manufacturing cost, and also narrows the particle size distribution of the toner. That is, the latex dispersion, the wax dispersion, and the colorant dispersion are mixed at a temperature of 40 to 60 ° C., which is necessary for flocculation, and then the flocculant is added and homogenized so that homogenization and aggregation occur simultaneously.

When the aggregated toner particles reach a desired size, the toner particles are adjusted to stop the growth of the toner particles, and then fused, cooled, and dried to obtain the desired toner particles. The dried toner particles may be externally treated with silica or the like to adjust the charge amount and the like to prepare a final laser printer toner.

The manufacturing method of the toner of the present invention can also be applied to a toner having a core-shell structure. In the case of producing a toner having a core-shell structure, a flocculant is added to a mixture of a latex dispersion, a colorant dispersion and a wax dispersion for the core and homogenized. Then, the first flocculation toner is prepared by the coagulation step, and a latex dispersion for shell is added to the obtained first flocculation toner to form a shell layer, followed by a fusing step.

The binder resin included in the latex which can be used in the toner manufacturing method of the present invention is one or two or more polymerizable monomers selected from vinyl monomers, polar monomers having a carboxyl group, monomers having an unsaturated polyester group, and monomers having a fatty acid group. It can be prepared by polymerization.

As the macromonomer added to adjust the number average molecular weight and glass transition temperature (Tg) of the binder resin, polyethylene glycol ethyl ether methacrylate, polyethylene glycol methyl methacrylate, polyethylene glycol methyl acrylate, and the like may be used. As the chain transfer agent, divinyl benzene, 1-dodecanethiol, or the like may be used.

The amount of the macromonomer added is preferably 0.3 to 30 parts by weight based on 100 parts by weight of the binder resin.

Some of the binder resins may be selected and further reacted with a crosslinking agent, and an isocyanate compound, an epoxy compound, or the like may be used as the crosslinking agent.

A crosslinking resin is formed by the crosslinking reaction of the binder resin and the crosslinking agent, and the content of the crosslinking resin contained in the toner is generally 5 to 30 parts by weight based on 100 parts by weight of the uncrosslinked binder resin. When the content of the crosslinked resin is less than 5 parts by weight, it is not preferable because the molecular weight decreases and the fixing temperature range is narrowed. When the content of the crosslinked resin is more than 30 parts by weight, it is not preferable because the resin becomes too hard and does not benefit low temperature fixability.

The colorant may be used as the pigment itself or in the form of a pigment masterbatch in which the pigment is dispersed in the resin.

The pigment may be appropriately selected from black pigments, cyan pigments, magenta pigments, yellow pigments, and mixtures thereof, which are commonly used pigments.

The content of the colorant may be sufficient to color the toner to form a visible image by development, for example, preferably 1 to 20 parts by weight based on 100 parts by weight of the binder resin.

On the other hand, a charge control agent and the like may be used as the additive.

As the charge control agent, both an ancillary charge control agent and an antistatic charge control agent may be used. Examples of the charge control agent include an organometallic complex or a chelate compound; Metal-containing salicylic acid compounds; And organometallic complexes of aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids may be used, and any known ones are not particularly limited. As the antistatic charge control agent, a product modified with nigrosine and a fatty acid metal salt thereof, an onium salt containing a quaternary ammonium salt, or the like may be used alone or in combination of two or more thereof. Such a charge control agent charges the toner stably and at high speed by the electrostatic force, thereby stably supporting the toner on the developing roller.

The content of the charge control agent included in the toner is generally within the range of 0.1 parts by weight to 10 parts by weight based on 100 parts by weight of the total toner composition.

As the wax can improve the fixability of the toner image, polyalkylene waxes such as low molecular weight polypropylene and low molecular weight polyethylene, ester wax, carnauba wax, paraffin wax and the like can be used. The amount of wax contained in the toner is generally within the range of 0.1 part by weight to 30 parts by weight with respect to 100 parts by weight of the total toner composition. When the content of the wax is less than 0.1 parts by weight, it is not desirable to realize an oilless fixation capable of fixing the toner particles without using oil, and when the content of the wax exceeds 30 parts by weight, the toner is agglomerated when stored. This is undesirable because it can be caused.

In addition, the additive may further include an external additive. The external additive is to improve the fluidity of the toner or to control the charging characteristics, and includes large particle size silica, small particle size silica, and polymer beads.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these embodiments.

Example 1

(Production of Latex Dispersion for Core)

A 5 liter reactor with a stirrer, thermometer and condenser was installed in the oil bath. 990 g and 4.8 g of distilled water and a surfactant (Dowfax 2A1) were added to the reactor thus installed, and the reactor temperature was increased to 70 ° C. and stirred at a speed of 100 rpm. 20.25 g of potassium persulfate was then added as an initiator. Thereafter, monomers, ie, 1257 g of styrene, 483 g of butyl acrylate, 55.5 g of 2-carboxyethyl acrylate, and 33.9 g of 1,10-decanediol diacrylate, 761.25 g of distilled water, 33.9 g of a surfactant (Dowfax 2A1), and a macromonomer Emulsion mixture of polyethylene glycol ethyl ether methacrylate as 79.5g and 1-dodecanethiol 28.2g as a chain transfer agent was stirred for 30 minutes at 400-500 rpm with a disk-type impeller, and then slowly charged into the reactor for 1 hour. . After the reaction was performed for about 8 hours and then slowly cooled to room temperature to complete the reaction.

After completion of the reaction, the glass transition temperature (Tg) of the binder resin was measured using a differential scanning calorimeter (DSC), and the temperature was 57 ° C. The number average molecular weight of the binder resin was measured by gel permeation chromatography (GPC) using a polystyrene reference sample. As a result, the number average molecular weight was 15,000.

Preparation of Latex Dispersion for Shell

2,200 g of deionized water was added to a 4 liter reactor, and the mixture was heated to 80 ° C. while stirring while purging N ₂ . Thereafter, 390 g of styrene monomer, 145 g of butyl methacrylate, 20 g of methacrylic acid, and 10 g of epoxy acrylate were completely dissolved after stirring, and a mixture of 10% of all monomers of the mixture was first introduced into a heated reactor. Subsequently, an initiator solution in which 16 g of potassium persulfate was dissolved in 140 g of deionized water was added thereto, followed by reaction for 10 minutes. The remaining 90% of the monomer mixture was added dropwise when the polymer in the reactor showed suspension. The reaction product was added dropwise for 2 hours, and when the addition of the monomer was completed, the reaction was allowed to proceed for an additional 4 hours and finished to prepare a latex dispersion for shell.

(Production of Colorant Dispersion)

Into a volume 4 liter reactor equipped with a stirrer, a thermometer, and a condenser, 540 g of cyan pigment (ECB303, Japan), 27 g of surfactant (Dowfax 2A1), and 2,450 g of distilled water were added, followed by preliminary stirring for about 10 hours. Dispersion was performed. After pre-dispersion for 10 hours, using Ultimaizer (Amtech Co., Ltd.) was dispersed for 4 times until the particle size to 200nm or less at 1500bar. As a result, a cyan pigment dispersion was obtained.

After completion of the dispersion, the particle size of the cyan pigment particles was measured using a Multisizer 2000 (manufactured by Malvern Corporation), and the D50 (v) was 170 nm. Here, D50 (v) refers to a particle size corresponding to 50% of the volume average particle diameter, that is, a particle size corresponding to 50% of the total volume when the volume is accumulated from small particles by measuring the particle diameter.

(Production of Wax Dispersion)

After adding 65 g of surfactant (Dowfax 2A1) and 1,935 g of distilled water to a volume 5 liter reactor equipped with a stirrer, a thermometer, and a condenser, the mixture was slowly stirred at a high temperature for about 2 hours, and then wax (NOF Japan, WE-5). 1,000 g was charged to the reactor. The mixture was dispersed for 30 minutes using a homogenizer (IKA, T-45). As a result, a wax dispersion was obtained.

After completion of the dispersion, the particle size of the dispersed particles was measured using a Multisizer 2000 (manufactured by Malvern Corporation), and the D50 (v) was 320 nm.

(Production of Toner Particles)

3300 g of the latex dispersion for cores, 530 g of a colorant dispersion, 590 g of a wax dispersion, and 10300 g of distilled water were added to a 20 liter reactor, and the temperature of the reactor was increased to 51 ° C. and stirred and mixed at 120 rpm. 970 g of a 2: 1 (mass ratio) mixture of 0.3 N HNO ₃ and PSI (Poly Silicato Iron) was added to the flocculant, and the mixture was stirred at 140 rpm to aggregate. Aggregation was continued until D50 (v) became 6.45 ~ 6.50㎛, and the stirring speed was increased to 170rpm and 1280g of the latex dispersion for shell was added, and then the stirring speed was lowered to 140rpm. 900 g of 1N sodium hydroxide aqueous solution was added to the reactor, and the mixture was stirred at 120 rpm until pH 4, and at 100 rpm until pH 7. The stirring speed was lowered to 80 rpm, and then the temperature of the reactor was raised to 80 ° C. to allow toner particles to fuse. Fusion was continued until the circularity was 0.970.

Subsequently, the temperature of the reactor was cooled to 40 ° C., the toner was separated using a filtration device (device name: filter press), and the separated toner was washed with 1N HNO ₃ aqueous solution and washed again with distilled water five times to form a surfactant or the like. Were removed. Thereafter, the washed toner particles were dried in a fluid bed dryer at a temperature of 40 ° C. for 5 hours to obtain dried toner particles.

Example 2

3300 g of the latex dispersion for cores, 530 g of colorant dispersion, 590 g of wax dispersion, and 10300 g of distilled water, respectively, were heated in a 20 liter reactor at 40 ° C. and introduced into the reactor, and the reactor was kept at 40 ° C. at 120 rpm. Stir and mix. 970 g of a 2: 1 (mass ratio) mixture of 0.3 N HNO ₃ and PSI (Poly Silicato Iron) was added to the flocculant, and the mixture was stirred at 140 rpm to aggregate. Aggregation was continued until D50 (v) became 6.45 ~ 6.50㎛, and the stirring speed was increased to 170rpm and 1280g of the latex dispersion for shell was added, and then the stirring speed was lowered to 140rpm. 900 g of 1N sodium hydroxide aqueous solution was added to the reactor, and the mixture was stirred at 120 rpm until pH 4, and at 100 rpm until pH 7. The stirring speed was lowered to 80 rpm, and then the temperature of the reactor was raised to 80 ° C. to allow toner particles to fuse. Fusion was continued until the circularity was 0.970.

Subsequently, the temperature of the reactor was cooled to 40 ° C., the toner was separated using a filtration device (device name: filter press), and the separated toner was washed with 1N HNO ₃ aqueous solution and washed again with distilled water five times to form a surfactant or the like. Were removed. Thereafter, the washed toner particles were dried in a fluid bed dryer at a temperature of 40 ° C. for 5 hours to obtain dried toner particles.

Example 3

3300 g of the latex dispersion for cores, 530 g of colorant dispersion, 590 g of wax dispersion, and 10300 g of distilled water, respectively, were heated in a 20-liter reactor at 60 ° C. and introduced into the reactor, and then the reactor was kept at 60 ° C. at 120 rpm. Stir and mix. 970 g of a 2: 1 (mass ratio) mixture of 0.3 N HNO ₃ and PSI (Poly Silicato Iron) was added thereto as a coagulant, and aggregation was performed while stirring at 140 rpm. Aggregation was continued until D50 (v) became 6.45˜6.50 μm, and the stirring speed was increased to 170 rpm, and 1280 g of the latex dispersion for the shell was added thereto, followed by lowering the stirring speed to 140 rpm. 900 g of 1N sodium hydroxide aqueous solution was added to the reactor, and the mixture was stirred at 120 rpm until pH 4, and at 100 rpm until pH 7. The stirring speed was lowered to 80 rpm, and then the temperature of the reactor was raised to 80 ° C. to allow toner particles to fuse. Fusion was continued until the circularity was 0.970.

Subsequently, the temperature of the reactor was cooled to 40 ° C., the toner was separated using a filtration device (device name: filter press), and the separated toner was washed with 1N HNO ₃ aqueous solution and washed again with distilled water five times to form a surfactant or the like. Were removed. Thereafter, the washed toner particles were dried in a fluid bed dryer at a temperature of 40 ° C. for 5 hours to obtain dried toner particles.

Comparative Example 1

3300 g of the latex dispersion for the core, 530 g of the colorant dispersion, and 590 g of the wax dispersion prepared above were added to a 20-liter reactor, followed by stirring at 120 rpm at room temperature, followed by mixing, followed by 0.3 N HNO ₃ and PSI (Poly Silicato Iron) Toner particles were obtained in the same manner as in Example 1, except that 970 g of a 2: 1 (mass ratio) mixture was added and the mixture was stirred at 140 rpm and the temperature of the reactor was increased to 51 ° C. to cause aggregation.

Assessment Methods

Hereinafter, the physical properties of the toner particles prepared in Examples and Comparative Examples were evaluated by the following method.

The GSDp and GSDv of the toner particles in Examples 1 to 3 and Comparative Example 1 were obtained by measuring the average particle diameter using a Multisizer ™ 3 Coulter Counter ^® of Beckman Coulter Inc. Obtained by 1 and 2. In the multisizer, an aperture is 100 μm, and an appropriate amount of a surfactant is added to 50-100 ml of ISOTON-II (Beckman Coulter Co., Ltd.), which is an electrolyte, and 10-15 mg of the measurement sample is added thereto. Samples were prepared by dispersing the dispersion machine for 5 minutes.

[Equation 1]

(p : 입자수)GSDp =

(p: number of particles)

[Equation 2]

(v : 부피)GSDv =

(v: volume)

Circularity was measured using FPIA-3000 (manufactured by Sysmex, Japan). In the circularity measurement using FPIA-3000, the measurement sample was prepared by adding an appropriate amount of a surfactant to 50 to 100 ml of distilled water, adding 10 to 20 mg of toner particles thereto, and then dispersing in an ultrasonic disperser for 1 minute.

The circularity is automatically obtained from FPIA-3000 by the following formula (3).

[Equation 3]

Circularity = 2 × (area × π) ^1/2 / perimeter

In the above formula, the area means the area of the projected toner, and the perimeter means the circumferential length of the projected toner. This value can range from 0 to 1, the closer to 1, the spherical.

In addition, the evaluation method of resin is as follows.

The glass transition temperature (Tg, ° C.) was measured by using a differential scanning calorimeter (Netzsch Co., Ltd.) and heating the sample at 20 ° C. to 200 ° C. at a heating rate of 10 ° C./min, and then at 10 ° C./min. After quenching to < RTI ID = 0.0 > C, < / RTI >

The charge amount was measured using a Vertex Charge Analyzer 150 (Vertex Image Products, Yukon, Penn.) As a blow-off powder charge amount measuring device.

In the blow-off method, a mixture of powder and carrier is placed in a cylindrical container with nets at both ends, high pressure gas is blown from one end to separate the powder and carrier, and only the powder is blown off from the eyes of the net. At this time, the amount of charge that is equivalent to the amount of charge that the powder has taken out of the container and has the opposite polarity remains in the carrier. In addition, all of the electric charges due to this charge are gathered in the capacitor by the Faraday cage and the capacitor is charged by the amount. By measuring the potential across the capacitor, the charge amount Q of the powder is obtained by the following equation.

[Equation 4]

Q = CV

Where C is the capacitor capacity, V is the voltage across the capacitor, and Q is the amount of charge in the powder.

The charging rate is measured by dividing the amount of charge generated between the two materials by the time required for mixing while mixing the carrier and toner particles. The initial charge rate means the rate at which the charge amount is formed on the toner, and the initial charge rate in the present invention was calculated as the charge amount measured after 1 minute of mixing time between the carrier and the toner.

The fluidity was measured after leaving the toner sample under N / N and H / H conditions using a Micron Powder Characteristics Tester (manufactured by HOSOKAWA), and the larger the value, the poorer the fluidity.

-N / N condition: 2hr, 25 ℃, humidity 55%

-H / H condition: 15hr, 50 ℃, humidity 80% + 2hr, 25 ℃, humidity 55%

The evaluation results are shown in Table 1 below.

GSDp GSDv liquidity
(H / H) liquidity
(N / N) Initial charge speed
(μC / min) Charge
(μC / gram) Example 1 1.268 1.246 87.7 81.5 15 29 Example 2 1.269 1.244 89.1 83.2 14 31 Example 3 1.276 1.248 88.5 84.5 15 28 Comparative Example 1 1.318 1.277 89.3 84.9 13 31

As shown in the table, it can be seen that the toner produced by the production method of the present invention has a narrower particle size distribution than that produced by the conventional method, while maintaining other properties such as fluidity, initial charge rate and charge amount. .

Tables 2 to 4 below show the number of particles having GSDp, GSDv and particle size less than 3 μm in the process steps in the production method according to Examples 1 to 3 and Comparative Example 1.

GSDp Example 1 Example 2 Example 3 Comparative Example 1 When homogenization is complete 1.264 1.268 1.274 1.264 When aggregation is complete 1.258 1.259 1.262 1.315 When to add latex for shell 1.259 1.257 1.270 1.310 30 minutes after latex 1.260 1.255 1.268 1.309 NaOH input completion time 1.260 1.257 1.266 1.315 30 minutes after completion of NaOH 1.256 1.258 1.262 1.318 Fusion point of view 1.268 1.269 1.276 1.318

GSDv Example 1 Example 2 Example 3 Comparative Example 1 When homogenization is complete 1.295 1.288 1.299 1.333 When aggregation is complete 1.225 1.222 1.228 1.249 When to add latex for shell 1.230 1.232 1.235 1.249 30 minutes after latex 1.237 1.230 1.233 1.240 NaOH input completion time 1.230 1.227 1.233 1.236 30 minutes after completion of NaOH 1.230 1.232 1.237 1.237 Fusion point of view 1.246 1.244 1.248 1.281

Number of particles less than 3 μm Example 1 Example 2 Example 3 Comparative Example 1 When aggregation is complete 2.540 2.500 2.700 3.680 When to add latex for shell 2.700 2.680 2.700 3.880 30 minutes after latex 2.440 2.350 2.550 3.775 NaOH input completion time 2.240 2.200 2.300 3.375 30 minutes after completion of NaOH 2.200 2.200 2.300 3.258 Fusion point of view 2.300 2.350 2.400 3.488

1 is a graph showing GSDp values according to process steps in the manufacturing method according to Examples 1 to 3 and Comparative Example 1. FIG. Figure 2 is a graph showing the GSDv value for each step in the manufacturing method according to Examples 1 to 3 and Comparative Example 1. 3 is a graph showing the number of particles having a particle size of less than 3 μm in each step in the manufacturing method according to Examples 1 to 3 and Comparative Example 1. FIG. 1 to 3, the homogenization completion point (HOMO), the aggregation completion point (agglomeration), the latex injection completion point for the shell (LS Wan), 30 minutes after the latex injection completion (LS 30 '), NaOH addition completion point (NaOH Wan) 30 minutes after the completion of NaOH addition (NaOH 30 ') and the time of fusion (fusion), respectively. In FIG. 3, however, the number of particles having a size less than 3 μm at the time of completion of homogenization was too large to be represented on the drawing. As shown in the figure, in the case of Examples 1 to 3, it can be seen that the particle size distribution of the toner particles is narrower than that of Comparative Example 1, and that the number of fine powders is much smaller .

Although the preferred embodiment according to the present invention has been described above, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the protection scope of the present invention should be defined by the appended claims.

1 is a graph showing GSDp of toner particles according to the manufacturing processes of Examples 1 to 3 and Comparative Example 1. FIG.

2 is a graph showing GSDv of toner particles according to the manufacturing processes of Examples 1 to 3 and Comparative Example 1. FIG.

3 is a graph showing the number of particles having an average particle diameter of less than 3 μm according to the manufacturing processes of Examples 1 to 3 and Comparative Example 1. FIG.

Claims (3)

Mixing the latex dispersion, the colorant dispersion and the wax dispersion at 40 to 60 ° C; Agglomerating toner particles by adding and homogenizing a flocculant to the mixture; Fusing the aggregated toner particles; And And cooling the fused toner particles. The method of claim 1, The latex dispersion is a method of producing a toner, characterized in that the latex comprises a styrene residue. The method of claim 1, And the toner has a core-shell structure.

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