KR100429790B1 - Toner composition and manufacturing method of toner using the same - Google Patents

Abstract

The present invention discloses a toner composition and a method for producing the toner using the same. The toner composition includes a binder resin forming monomer, a colorant, a stabilizer, a charge control agent, a lubricant, and a polymerization initiator. The stabilizer is dispersed in hydrophobic silica in distilled water adjusted to pH 10-14, and then pH 6-6. It is characterized in that the result obtained by adjusting to 8. By using the toner composition of the present invention, it is possible to produce a toner having improved charge amount, average particle size and particle size distribution characteristics. In particular, when the toner composition contains a surfactant, a toner having a very high dispersibility of a colorant and a charge control agent may be obtained, and an improved image quality may be obtained using such a toner.

Description

Toner composition and manufacturing method of toner using same {Toner composition and manufacturing method of toner using the same}

The present invention relates to a toner composition and a method for manufacturing the toner using the same, and more particularly, a composition for forming a toner having improved dispersibility of a colorant as well as improved particle size and charge amount characteristics, and a method for producing a toner using the composition. It is about.

Recently, with the development of the computer industry, the demand for printers is gradually increasing. In line with this trend, the use of toner is also increasing.

Toners used in image formation are mostly manufactured by a pulverization method. Looking at the method of manufacturing the toner by the grinding method, first, a polymer binder resin, a colorant, a charge control agent and the like are mixed dry. The mixture is then melt mixed, cooled, and the resultant milled to produce toner particles.

The toner produced according to the above method has a wide distribution of particle diameters. Therefore, toner particles outside the predetermined particle size range have to be discarded, which is not preferable in terms of manufacturing cost. In addition, there is a problem that the resolution is lowered due to the limitation of dispersion of the charge control agent, the colorant and the like and the shape of the toner particles. In order to improve this problem, a method of producing spherical toner particles by a polymerization method has been proposed. Polymerization can be divided into emulsion polymerization and suspension polymerization. However, according to the emulsified polymerization, the particle size of the finally produced toner is so small that it is too small to be harmful to the human body, so that it is difficult to practically apply to the printer. For this reason, suspension polymerization is preferred to emulsification polymerization.

A method of manufacturing toner according to the suspension polymerization method will be briefly described as follows.

Water is used as a reaction medium, and a polymerization reaction is performed by adding a binder resin forming monomer, a charge control agent, a stabilizer, a lubricant, and a coloring agent.

Upon completion of the polymerization, a precipitate forms in the reaction mixture. By filtering and drying the obtained precipitate, spherical toner particles can be obtained.

Phosphate or hydrophobic silica is used as the stabilizer. By the way, when phosphate is used as a stabilizer, the particle size of the finally produced toner particles is too large, approximately 35 mu m, the particle size distribution is wide, and the charge amount characteristics are poor. This makes them unsuitable for use as toners.

On the other hand, in the case of using hydrophobic silica as a stabilizer, since hydrophobic silica is hardly dispersed in water, it is very difficult to be evenly mixed with each component constituting the toner composition, and thus the polymerization reaction itself cannot be achieved. In order to solve this problem, a method of performing a polymerization reaction by dissolving hydrophobic silica in an organic solvent such as methanol and mixing the respective components of the toner composition is proposed. By the way, according to this method, spherical toner particles could not be obtained.

The technical problem to be achieved by the present invention is to solve the above problems to provide a composition for forming a toner having improved dispersibility and particle size characteristics of the colorant.

Another technical object of the present invention is to provide a method for producing a toner using the composition.

1 to 7 are optical micrographs of toner particles prepared according to Example 1-5 and Comparative Example 3-4 of the present invention,

8 to 14 show particle size distribution characteristics of toner particles prepared according to Examples 1-5 and Comparative Examples 3-4 of the present invention.

In order to achieve the first object, in the present invention, in the toner composition comprising a binder resin forming monomer, a colorant, a stabilizer, a charge control agent, a lubricant and a polymerization initiator, the stabilizer is hydrophobic in distilled water adjusted to pH 10-14. Dispersing silica and then adjusting the pH to 6 to 8 to provide a toner composition characterized in that the result.

The second object of the present invention is the step of (a) adjusting the distilled water to pH 10-14 using a water-soluble base, and then adding and dispersing hydrophobic silica thereto; (b) adjusting the pH of the mixture to 6-8; (c) mixing a binder resin forming monomer, a polymerization initiator, a charge control agent, a lubricant and a colorant, and then adding the mixture to the mixture obtained in step (b); (d) polymerizing the resultant to form toner particles; And (e) removing the foreign matter remaining on the surface of the toner particles.

The toner composition of the present invention is characterized by using a resultant obtained by dispersing hydrophobic silica in distilled water adjusted to pH 10-14 as a stabilizer and then neutralizing it to pH 6-8. By adding and mixing the binder resin forming monomer, colorant, stabilizer, charge control agent, lubricant and polymerization initiator to such a stabilizer, it is possible to obtain a toner composition in which each component is uniformly dispersed as a whole, unlike conventional toner compositions.

It is preferable that the mixed weight ratio of the binder resin forming monomer and the silica solid content is 50: 1 to 25: 1. Here, if the mixing ratio of the silica solid content to the binder resin forming monomer exceeds the above range, it is very difficult to recover the toner particles after the polymerization reaction, and if it is below the above range, the toner particles are aggregated, which is not preferable.

In addition, the toner composition of the present invention may further include an ionic surfactant. In this case, the ionic surfactant is not particularly limited, and both cationic or anionic surfactants can be used.

As the anionic surfactant, sodium lauryl sulfate is used, and as the cationic surfactant, cetyltrimethylammonium bromide or cetyltrimethylammonium chloride is used. And the mixing weight ratio of the binder resin forming monomer and the cationic surfactant is preferably 1000: 1 to 2000: 1. If the mixing ratio of the cationic surfactant to the monomer for forming the binder resin exceeds the above range, recovery of toner particles is difficult, and if it is below the above range, dispersibility of the colorant is poor, which is not preferable.

As the monomer for forming the binder resin of the present invention, any monomer commonly used when preparing toner by a polymerization method can be used. In the present invention, styrene and butyl methacrylate are used, wherein the mixed weight ratio of styrene and butyl methacrylate is preferably 6: 4 to 9: 1, and more preferably 7: 3 to 8: 2. .

The charge control agent of the present invention is a material that controls the charge of the toner, and any charge control agent can be used. And as a coloring agent of this invention, carbon black which is a black pigment is used.

The lubricant used in the present invention is a substance which improves the fluidity of the toner, and wax is used here. As the polymerization initiator, any conventional polymerization initiator may be used.

Hereinafter, a method of manufacturing toner using the toner composition according to the present invention will be described.

Distilled water is adjusted to pH 10-14 with a water-soluble base, and then hydrophobic silica is added thereto to disperse it. Subsequently, the mixture is adjusted to pH 6-8 to neutralize. Herein, the water-soluble base is not particularly limited, and sodium hydroxide, potassium hydroxide, ammonium hydroxide and the like can be used. The acid used for neutralizing the aqueous hydrophobic silica solution of pH 10-14 is not particularly limited, but formic acid is preferably used.

A mixture of a monomer for forming a binder resin, a charge control agent, a colorant, a lubricant, and a polymerization initiator is added to the reaction mixture, and the mixture is sufficiently mixed. In some cases, ionic surfactants, in particular cationic surfactants, are further added to the mixture. This mixing process is preferably carried out in a ball mill.

Thereafter, the resultant is subjected to a polymerization reaction in a nitrogen atmosphere. Upon completion of the polymerization, methanol is used to remove unreacted material from the reaction mixture. Here, when the polymerization conversion rate is as low as 70 to 80%, it is preferable to remove unreacted material using methanol, and when the polymerization conversion rate is high, it is preferable to remove unreacted material using distilled water.

Thereafter, the obtained precipitate is filtered, and then foreign matter remaining on the surface of the precipitate is removed. Dilute potassium hydroxide solution or methanol is used to remove this foreign matter. The toner particles according to the present invention can be obtained by drying the resultant in which the foreign matter is removed in a vacuum oven for a predetermined time.

The average particle diameter of the toner obtained according to the above method is 5 to 20 µm, the amount of charge is -10 to -20 (µc / g), and the glass transition temperature is 60 to 75 ° C.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited only to the following Examples.

<Example 1>

Aqueous ammonia was added to 600 ml of distilled water to adjust the pH to about 10, and 6 g of hydrophobic silica R-972 (Degussa) was added thereto, which was then stirred at 5000 rpm for 10 minutes in a high speed homogenizer. Subsequently, the first composition was prepared by neutralizing the aqueous hydrophobic silica alkali solution using formic acid.

Styrene 140 ml, butyl methacrylate 60 ml, 4 g of 2,2-azobisisobutyronitrile, carbon black 2350 (Mitsubishi Corporation) (average particle diameter: 15 nm) 6 g, Bontron S-34 (Bontron S-34) 2 g of (Orient Chemical) and 2 g of wax were mixed to prepare a second composition.

The mixture of the first composition and the second composition was stirred for 24 hours in a ball-mill. Subsequently, the polymerization reaction was carried out at 75 ° C. for 7 hours under a nitrogen atmosphere.

After the reaction was completed, unreacted styrene and butyl methacrylate were removed from the reaction mixture using methanol. Subsequently, the resultant was filtered and washed, and then dried in a vacuum oven for 2 days to prepare toner particles.

<Example 2>

The same procedure as in Example 1 was carried out except that the content of carbon black was 10 g.

<Example 3>

The same procedure was followed as in Example 1, except that the first composition further contained 0.1 g of cetyltrimethylammonium bromide (CTAB).

<Example 4>

The hydrophobic silica aqueous alkali solution was prepared according to the same method as in Example 1 except that an aqueous sodium hydroxide solution was used instead of an aqueous ammonia solution.

Example 5

The same procedure as in Example 1 was carried out except that Degusa's Printex L-6 (average particle diameter: 18 nm) was used as the carbon black instead of 2350.

Comparative Example 1

400 ml of distilled water and 100 ml of methanol were mixed, and 6 g of R-972 (Degussa), which is hydrophobic silica, was dispersed therein to prepare a first composition.

140 ml of styrene and 60 ml of butyl methacrylate were mixed in 600 ml of distilled water, followed by 4 g of 2,2-azobisisobutyronitrile, 6 g of carbon black, 2 g of Bontron S-34, and 2 g of wax was added and mixed to prepare a second composition.

The second composition was added to the first composition, and then the reaction mixture was polymerized at 75 ° C. for 7 hours under a nitrogen atmosphere.

After the reaction was completed, unreacted styrene and butyl methacrylate were removed from the reaction mixture using methanol. The resultant was then filtered and washed and dried for 2 days in a vacuum oven.

Comparative Example 2

The preparation of the first composition was carried out according to the same method as in Example 1, except for using di-n-butylamine instead of ammonia water.

Comparative Example 3

A first composition was prepared by adding 3 g of tri-calcium phosphate (Ca 3 (PO 4) 2: Yakuri pure chemicals) to 600 ml of distilled water.

140 ml of styrene, 60 ml of butyl methacrylate, 2 g of 2,2-azobisisobutyronitrile, 6 g of carbon black (Mitsubishi Corporation), 2 g of Bontron S-34 (Orient Chemical) and 2 g of wax To prepare a second composition by mixing.

After adding the second composition to the first composition, the mixture was mixed in a ball mill for 24 hours. Thereafter, the mixture was subjected to a polymerization reaction at 75 ° C. for 7 hours under a nitrogen atmosphere.

After the reaction was completed, unreacted styrene and butyl methacrylate were removed from the reaction mixture using methanol. Subsequently, the resultant was filtered and washed, and then dried in a vacuum oven for 2 days to prepare toner particles.

<Comparative Example 4>

The same procedure as in Example 1 was carried out except that the first composition and the second composition were mixed in a high speed stirrer.

When toner particles were produced according to Comparative Example 1, the conversion rate of the polymerization reaction was very low, and it was difficult to obtain spherical toner particles after the completion of the polymerization reaction. In the case of preparing the first composition using n-butylamine (Comparative Example 2), it was difficult to obtain the first composition having a uniform composition because hydrophobic silica itself was entangled, and thus the polymerization reaction itself was difficult.

On the other hand, the characteristics of the toner particles prepared according to Example 1-5 and Comparative Example 3-4 were evaluated according to the following method.

The particle size and particle size distribution of the toner particles were measured using a coulter counter and a laser particle analyzer, and the surface analysis of the toner particles was evaluated using a scanning electron microscope (SEM). do.

The dispersibility of the carbon black in the toner particles was evaluated as follows using an optical microscope (LABOPHOT-2, manufactured by Nikon Corporation).

◎: carbon black is very finely dispersed

○: finely dispersed carbon black

(Triangle | delta): It is a grade which the big particle of carbon black is seen slightly.

X: large particles of carbon black are seen

The glass transition temperature is measured using a differential scanning calorimeter (DSC), and the molecular weight is measured using gel permeation chromatography (GPC).

The charge amount of the toner particles is measured using a Toshiba blow-off meter.

Meanwhile, the dispersibility, average particle diameter, glass transition temperature, and charge amount of carbon black of the toner particles prepared according to Examples 1-5 and Comparative Examples 1-4 were measured and shown in Table 1 below.

division Dispersibility of Carbon Black Average particle size (㎛) Glass transition temperature (℃) Charge amount (μc / g) Example 1 ○ 12.57 68.04 -11.54 Example 2 ○ 13.76 66.14 -12.16 Example 3 ◎ 12.87 64.37 -15.48 Example 4 ◎ 12.75 67.48 -12.16 Example 5 ◎ 5.25 66.22 -20.27 Comparative Example 3 △ 38.28 65.36 +7.35 Comparative Example 4 △ 26.99 66.12 -9.56

Table 1 shows that the toner particles prepared according to Example 1-5 had very good dispersibility of carbon black as compared with the case of Comparative Examples 3 and 4.

In particular, the particle diameters of the toner particles prepared according to Comparative Example 3 tended to be bisected into 20 µm or more and 10 µm or less. Among them, toner particles having a large particle size of 20 µm or more have some degree of dispersion of pigments therein, while toner particles having a small particle size of 10 µm or less do not have any pigment therein.

1 to 5 are optical micrographs of toner particles prepared according to Example 1-5, and FIGS. 6 to 7 are optical micrographs of toner particles prepared according to Comparative Example 3-4.

1 to 5, it can be seen that the toner particles prepared according to Examples 1-5 have a very good dispersibility of carbon black as compared with the case of Comparative Examples 3 and 4. In particular, referring to FIG. 3, when cetyltrimethylammonium bromide (CTAB) was added (Example 3), it was found that carbon black was very evenly dispersed in the toner particles.

Meanwhile, particle size distribution characteristics of the toner particles prepared according to Example 1-5 and Comparative Example 3-4 were examined and shown in FIGS. 8-14.

8-14, it can be seen that the particle size distribution characteristics of the toner particles prepared according to Examples 1-5 are improved compared to the toner particles prepared according to Comparative Examples 3 and 4.

In addition, it can be seen from Table 1 that the toner particles prepared according to Example 1-5 have improved charge amount and average particle diameter characteristics of the toner particles as compared with Comparative Example 3-4.

By using the toner composition of the present invention, it is possible to produce a toner having improved charge amount, average particle size and particle size distribution characteristics. In particular, when the toner composition contains a surfactant, a toner having a very high dispersibility of a colorant and a charge control agent may be obtained, and an improved image quality may be obtained using such a toner.

Claims (8)

A toner composition comprising a binder resin forming monomer, a colorant, a stabilizer, a charge control agent, a lubricant, and a polymerization initiator, The stabilizer is a result obtained by dispersing hydrophobic silica in distilled water adjusted to pH 10-14, and then adjusted to pH 6-8, The composition further comprises an ionic surfactant, Toner composition, characterized in that the mixing weight ratio of the forming resin for the binder resin and the silica solid content is 50: 1 to 25: 1. The toner composition of claim 1, wherein a mixed weight ratio of the monomer for forming the binder resin and the ionic surfactant is 1000: 1 to 2000: 1. The method of claim 1, wherein the ionic surfactant is sodium lauryl sulfate (anionic surfactant) or selected from the group consisting of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride Toner composition, characterized in that the cationic surfactant. (a) adjusting distilled water to pH 10-14 using a water-soluble base, and then dispersing hydrophobic silica therein; (b) adjusting the pH of the mixture to 6-8; (c) mixing a binder resin forming monomer, a polymerization initiator, a charge control agent, a lubricant, a colorant, and an ionic surfactant, and then adding the mixture to the mixture obtained in step (b); (d) polymerizing the resultant to form toner particles; And (e) removing foreign matter remaining on the surface of the toner particles; A mixing weight ratio of the forming resin for the binder resin and the silica solid content is 50: 1 to 25: 1. The method of claim 4 wherein the water soluble base is selected from the group consisting of ammonium hydroxide, sodium hydroxide and potassium hydroxide. The method according to claim 4, wherein the ionic surfactant is sodium lauryl sulfate, which is an anionic surfactant, or is selected from the group consisting of cetyltrimethylammonium bromide and cetyltrimethylammonium bromide. A cationic surfactant. The method of claim 4, wherein the mixed weight ratio of the monomer for forming the binder resin and the ionic surfactant is 1000: 1 to 2000: 1. A toner prepared according to any one of claims 4, 5, 6 and 7.