KR20140073658A - Toner and method of preparing the same - Google Patents

Abstract

Disclosed are a toner and a method to manufacture the same. The disclosed toner comprises: a core unit including a first binding resin and wax; a first shell unit comprising a second binding resin and a coloring agent, and surrounding the core unit; and a second shell unit comprising a third binding resin and surrounding the first shell unit, wherein the first shell unit and the second shell unit does not comprise wax.

Description

Toner and method of preparing same

A toner and a manufacturing method thereof are disclosed. More particularly, the present invention relates to a toner having a triple structure which is excellent in low temperature fixability and strength and a method for producing the same.

Generally, the toner is prepared by adding a coloring agent, wax, or the like to a thermoplastic resin serving as a binder resin. In addition, a charge control agent for imparting chargeability to the toner and holding it, a release agent for releasing the toner from the fixing unit of the image forming apparatus, an external agent for improving the physical properties such as imparting fluidity and developability to the toner, May be added to the toner. Examples of the method for producing such a toner include a physical method such as a pulverization method and a chemical method such as a suspension polymerization method, an emulsion aggregation method, a chemical milling method, and a dispersion polymerization method.

Among them, the emulsion aggregation method (see U.S. Patent No. 5,916,725, No. 6,268,103, etc.) includes a step of preparing a fine emulsion resin particle composition through emulsion polymerization, and a step of coagulating the composition with a colorant etc. in a separate dispersion do. This method has an advantage in that it can solve problems such as a high cost and a wide particle size distribution in the pulverization method, and can make the toner particles spherical by controlling the coagulation condition.

However, toner particles produced by the conventional emulsion agglomeration method have a problem that a part of the wax is protruded to the toner surface, the physical properties between the toner particles are not constant due to process variations, and the excellent low temperature fixability and strength are not satisfied at the same time.

An embodiment of the present invention provides a triple structure toner excellent in both low temperature fixability and strength.

Another embodiment of the present invention provides a method of producing the toner.

According to an aspect of the present invention,

A core portion comprising a first binder resin and a wax;

A first shell portion including a second binder resin and a colorant and surrounding the core portion; And

And a second shell portion including a third binder resin and surrounding the first shell portion,

The first shell part and the second shell part provide a toner not containing wax.

The core portion and the second shell portion may not contain a coloring agent.

The weight average molecular weight (Mw ₁ ) of the first binder resin, the weight average molecular weight (Mw ₂ ) of the second binder resin and the weight average molecular weight (Mw ₃ ) of the third binder resin may satisfy the following formula:

Mw ₁ < Mw ₂ < Mw ₃ .

The first binder resin may have a weight average molecular weight (Mw ₁ ) of 24,000 to 45,000, the second binder resin may have a weight average molecular weight (Mw ₂ ) of 42,000 to 55,000, The molecular weight (Mw ₃ ) may be from 55,000 to 79,000.

The toner may include 70 to 90 parts by weight of the first binder resin, 5 to 25 parts by weight of the second binder resin, and 1 to 6 parts by weight of the third binder resin.

According to another aspect of the present invention,

Adding a first binder resin dispersion liquid, a wax dispersion liquid and a coagulant to a reactor, and then raising the reactor contents first to form a toner core section;

Adding a second binder resin dispersion liquid and a colorant dispersion liquid to the reactor contents containing the toner core portion to form a first shell portion surrounding the toner core portion;

Further adding a third binder resin dispersion to the reactor contents containing the first shell portion to form a second shell portion surrounding the first shell portion; And

And secondarily raising the contents of the reactor through the second shell forming step to obtain aggregated toner particles.

The primary temperature increase may be performed at a temperature 2 to 20 ° C lower than the glass transition temperature of the first binder resin injected into the core portion forming step.

The secondary heating may be performed at a temperature 10-40 ° C higher than the glass transition temperature of the third binder resin added to the second shell forming step.

According to the method for producing a toner according to an embodiment of the present invention, a toner having a wide fixing temperature range, excellent low temperature fixability, high strength, and excellent image quality even with a small amount of colorant can be obtained.

1 is a schematic view of a toner according to an embodiment of the present invention.

Hereinafter, a toner according to an embodiment of the present invention and a method for producing the same will be described in detail.

A toner according to an embodiment of the present invention includes a core portion including a first binder resin and a wax, a second binder resin and a colorant, a first shell portion surrounding the core portion, and a third binder resin, And a second shell portion surrounding the shell portion, wherein the first shell portion and the second shell portion do not include wax. As used herein, the term &quot; toner &quot; may refer to one toner particle, depending on the context, and may refer to a collection of toner particles (i.e., toner powder).

The wax is disposed on the core portion as the innermost layer, and the wax is not disposed on the first shell portion as the intermediate layer and the second shell portion as the outermost layer. As a result, the wax does not protrude above the surface of the toner, A difference in physical properties between the particles can be prevented. That is, in almost all of the toner particles, the waxes are located inside the toner (that is, the core portion) and do not protrude above the surface of the toner.

The core portion and the second shell portion may not contain a coloring agent. Thus, the colorant is not substantially disposed in the core portion as the innermost layer and the second shell portion as the outermost layer, and the colorant is disposed only in the first shell portion as the intermediate layer. Thus, even with a small amount of colorant, Concentration can be realized. That is, most of the external visible light incident on the toner strikes the coloring agent in the first shell part, which is the intermediate layer, and is reflected. Therefore, the external visible light hardly reaches the core portion as the innermost layer, so that even if the coloring agent is arranged in the core portion, the coloring agent does not contribute to the image density. Therefore, even when the coloring agent is not disposed in the core portion, it is possible to realize an image density almost equal to that in the case where the coloring agent is arranged in the core portion.

The weight average molecular weight (Mw ₁ ) of the first binder resin, the weight average molecular weight (Mw ₂ ) of the second binder resin and the weight average molecular weight (Mw ₃ ) of the third binder resin may satisfy the following formula:

Mw ₁ < Mw ₂ < Mw ₃ .

By lowering the weight average molecular weight (Mw ₁ ) of the first binder resin in the core portion, the glass transition temperature of the whole toner can be lowered. As a result, the low temperature fixability of the toner can be improved.

Further, by increasing the weight average molecular weight (Mw ₃ ) of the third binder resin in the second shell portion as the outermost layer, the thermal strength and mechanical strength of the toner can be increased. Accordingly, even when the toner is stored for a long period of time under a high-temperature environment, caking phenomenon, which is a phenomenon in which the toner melts and fuses to each other, can be prevented and the storage stability of the toner can be improved.

Further, by setting the weight average molecular weight (Mw ₂ ) of the second binder resin in the first shell part as the middle layer to be intermediate between the Mw ₁ and the Mw ₃ , the core part and the second shell part And can be strongly coupled by mediation. Thus, when the toner is subjected to stress in the cartridge, the resistance is increased, thereby preventing image defects such as a streak from occurring when the toner is used in an image forming apparatus.

The first binder resin may have a weight average molecular weight (Mw _3a ) of 24,000 to 45,000, the second binder resin may have a weight average molecular weight (Mw _3b ) of 42,000 to 55,000, The molecular weight (Mw _3c ) may be from 55,000 to 79,000.

The toner may include 70 to 90 parts by weight of the first binder resin, 5 to 25 parts by weight of the second binder resin, and 1 to 6 parts by weight of the third binder resin. If the content ratio of the binder resin is within the above range, the wax and the colorant can be stably distributed only in the core portion and the first shell portion of the toner without interlayer migration in the three layers.

Hereinafter, the structure of the above-described toner will be described in more detail with reference to Fig.

1 is a schematic view of a toner according to an embodiment of the present invention.

Referring to FIG. 1, the toner includes a core portion 10, a first shell portion 20 surrounding the core portion 10, and a second shell portion 30 surrounding the first shell portion 20.

The wax 2 is distributed in the core portion 10 together with the first binder resin 3a and the colorant 1 is distributed in the first shell portion 20 together with the second binder resin 3b, Only the third binder resin 3c is distributed without the coloring agent and the wax. Further, the external additive 4 may be further distributed on the surface of the second shell part 30. [ Since the coloring agent and the wax are not present on the surface of the second shell part 30 as described above, the toner before external addition can have a smooth surface and is excellent in fixability due to the absence of surface wax and surface colorant. Image density can be realized. On the other hand, if wax or a colorant is present on the surface of the toner, the fixing property and the optical density (OD) deteriorate, and the toner surface becomes rough due to aggregation between wax and / or colorant particles, Or fouls the fuser.

Hereinafter, a method of manufacturing a toner according to an embodiment of the present invention will be described in detail.

The toner manufacturing method includes the steps of charging a first binder resin dispersion liquid, a wax dispersion liquid, and a coagulant into a reactor, then subjecting the contents of the reactor to a first temperature elevation to form a toner core portion, Forming a first shell portion surrounding the toner core portion by further adding a dispersion liquid and a colorant dispersion to the first shell portion; adding a third binder resin dispersion to the reactor contents containing the first shell portion to form a second shell portion surrounding the first shell portion; Forming a shell part, and secondarily raising the reactor contents through the second shell part forming step to obtain aggregated toner particles. Each of the above steps may be performed in one reactor, but the present invention is not limited thereto. One or more of the four steps and two or more steps may be performed in two or more reactors.

The reactor may comprise a stirrer, a heating means (e.g. a heater), a pressurizing means and / or a depressurizing means (e. G., A vacuum line and a vacuum pump).

In one embodiment, the binder resin dispersion, the colorant dispersion, and the wax dispersion may be the same or similar to the latex dispersion, colorant dispersion, and wax dispersion described in Korean Patent Publication No. 2010-0048071. Korean Patent Publication No. 2010-0048071 is incorporated herein by reference in its entirety.

In another embodiment, the binder resin dispersion, the colorant dispersion, and the wax dispersion may be the same or similar to the polyester resin dispersion, colorant dispersion, and wax dispersion disclosed in Korean Patent Publication No. 2010-0115148 . Korean Patent Publication No. 2010-0115148 is incorporated herein by reference in its entirety.

The glass transition temperature of the first binder resin may be 54 to 58 ° C, the glass transition temperature of the second binder resin may be 54 to 60 ° C, and the glass transition temperature of the third binder resin may be 56 to 62 ° C Lt; / RTI &gt; When the glass transition temperature of each binder resin is within the above range, the toner formed using each of the binder resin particles is excellent in storage stability, and hot offset hardly occurs even in color printing.

The colorant to be used in the preparation of the colorant dispersion may be black pigments, cyan pigments, magenta pigments, yellow pigments, and mixtures thereof, which are pigments commonly used commercially.

The wax used in the preparation of the wax dispersion may be a known wax. Natural waxes such as carnauba wax and rice wax; Synthetic waxes such as polypropylene wax and polyethylene wax; Petroleum waxes such as montan wax; Alcohol wax; And an ester-based wax. The wax may be used alone or in combination of two or more.

In addition, the wax may include at least one of a paraffin wax and a polyester wax. The paraffin wax mainly contains C ₂₀ to C ₃₆ linear saturated hydrocarbons, and may have a weight average molecular weight of 30 to 500 and a melting point of 40 to 80 ° C.

The wax may be a mixed wax of the paraffin wax and the polyester wax, for example, HNP-9 or HNP-11 wax.

The coagulant may be added not only to the core forming step but also to the first shell forming step and / or the second shell forming step. As such coagulant, Fe-polysilicate such as NaCl, KCl, or PSI (Poly Silicato Iron) may be used.

In the conventional toner manufacturing method, the binder resin dispersion, the colorant dispersion, and the wax dispersion are mixed at one time, and then the aggregation and coalescence process is performed to produce the toner. Thus, not only the colorant and the wax are present in the toner but also exposed to the surface of the toner, The surface of the outer sheath toner becomes rough and the circularity of each toner particle is not uniform, thereby deteriorating the fixability of the toner.

However, in the method of manufacturing a toner according to an embodiment of the present invention, the first binder resin dispersion liquid and the wax dispersion liquid are added to the reactor, mixed and then subjected to an aggregation process to form a core section, and then the contents of the reactor containing the core section The second binder resin dispersion liquid and the colorant dispersion liquid are further introduced to form a first shell portion surrounding the core portion so as to prevent the wax from being exposed to the surface of the toner and to arrange the colorant in the first shell portion as the intermediate layer, A third binder resin is further added to the first shell portion to form a second shell portion surrounding the first shell portion to prevent the colorant from being exposed on the surface of the toner. Then, the coalescing process is performed. That is, as shown in Fig. 1, the core portion 10 including the first binder resin 3a and the wax 2 is formed first, and then the second binder resin 3b and the colorant 1 are contained The second shell part 30 including the third binder resin 3c is formed so as to surround the core part 10 and the first shell part 20 is surrounded by the first shell part 20, The amount of colorant 1 and wax 2 exposed on the surface (i.e., the surface of the second shell portion 30) is made substantially zero. In this case, a large amount of wax 2 is present only in the core portion 10. On the other hand, when the wax is exposed to the surface of the toner, the fixing property deteriorates, and when the colorant is exposed on the surface of the toner, the image density is lowered. Therefore, according to the method for producing a toner according to an embodiment of the present invention, it is possible to obtain a toner excellent in fixability (particularly low-temperature fixability) and image density.

The amount of the wax added to the core portion may be 5 to 13 parts by weight based on 100 parts by weight of the total amount of the first, second and third binder resins.

The primary temperature increase may be 2 to 20 ° C lower than the glass transition temperature (Tg ₁ ) of the first binder resin injected into the core portion forming step. If the temperature at the time of the first heating is within the above range (Tg ₁ minus (-) 2 to 20 ° C), uniform agglomeration occurs on a particle-by-particle basis.

The aggregation may proceed until the particle diameter of the toner becomes 5.0 to 6.0 mu m.

The secondary heating may be performed at a temperature 10 to 40 ° C higher than the glass transition temperature (Tg ₃ ) of the third binder resin added to the second shell forming step. If the temperature at the time of the second heating is within the above range (Tg ₃ plus (+) 10 to 40 ° C), it is possible to prevent the phenomenon that the wax masses stick together to protrude from the toner surface after the wax mass is formed have.

The coalescence can proceed until the particle diameter of the toner becomes 6.6 to 7.2 탆, whereby toner particles having substantially uniform particle size and shape can be obtained.

The binder resins used in the above steps may be the same kind of binder resin.

The binder resin added to the toner manufacturing method preferably has a ratio of 70 to 90 parts by weight, 5 to 25 parts by weight and 1 to 6 parts by weight to the core portion forming step, the first shell portion forming step and the second shell portion forming step, respectively Lt; / RTI &gt; If the content ratio of the binder resin used in each of the above steps is within the above-mentioned range, it is possible to prevent the wax and the colorant from being exposed to the surface of the toner (that is, the surface of the second shell part).

The method of manufacturing the toner may further include washing and drying the toner particles obtained in the combining step with water. First, the reactor contents containing the toner particles are cooled to room temperature, filtered, the filtrate is removed, and the toner particles are washed with water. Pure water having a conductivity of 10 uS / cm or less may be used for the washing, and the washing may be continued until the conductivity of the filtered filtrate becomes 50 uS / cm or less. Cleaning of the toner with pure water may proceed batchwise or continuously. Cleaning of the toner using pure water can be performed to remove unnecessary components other than toner components such as impurities that may affect the chargeability of the toner and unnecessary coagulants that do not participate in aggregation.

The toner obtained after the washing step can be dried by using a fluid bed dryer, a flash jet dryer or the like. Further, a desired external additive can be added to the toner obtained by drying. The external additive is for improving the fluidity of the toner or controlling the charging property. Examples of the external additive include large diameter silica (particle diameter:? 40 nm), small particle size silica (7 nm? Particle diameter? 30 nm), polymer beads, Mixtures may be used.

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

Manufacturing example  1-1: Binder resin  Preparation of Dispersion (A)

A reactor having a volume of 30 liters equipped with a stirrer, a thermometer and a condenser was installed in an oil bath. Distilled water and surfactant (Dowfax 2A1) were added into the thus-prepared reactor in an amount of 8, 100 g and 31 g, respectively, and the temperature of the reactor was increased to 75 캜 and stirred at a stirring speed of 100 rpm. Thereafter, an emulsified mixture of monomers such as 9,200 g of styrene, 2,450 g of butyl acrylate, 350 g of 2-carboxyethyl acrylate, 4,870 g of distilled water, 220 g of a surfactant (Dowfax 2A1) and 170 g of 1-dodecanethiol Type impeller at 450 rpm for 30 minutes and then slowly added to the reactor for 1 hour. After the completion of the addition, a mixture of 3,277 g of distilled water and 175 g of ammonium persulfate was added thereto, and the reaction was allowed to proceed for about 8 hours, followed by slow cooling to room temperature (25 ° C) to complete the reaction. As a result, a binder resin was obtained.

After completion of the reaction, the glass transition temperature (Tg) of the binder resin obtained above was measured using a differential scanning calorimeter (DSC). As a result, the temperature was 56 ° C. Further, the weight average molecular weight of the binder resin was measured by GPC (gel permeation chromatography) using a polystyrene standard sample, and the weight average molecular weight was 25,000.

Manufacturing example  1-2: Binder resin  Preparation of Dispersion (B)

A reactor having a volume of 30 liters equipped with a stirrer, a thermometer and a condenser was installed in an oil bath. The reactor was charged with distilled water and surfactant (Dowfax 2A1) in amounts of 8, 100 g and 31 g, respectively. The temperature of the reactor was increased to 70 캜 and stirred at a stirring speed of 100 rpm. Thereafter, an emulsified mixture of monomers, namely, 8,500 g of styrene, 3,150 g of butyl acrylate, 350 g of 2-carboxyethyl acrylate, 4,870 g of distilled water and 220 g of a surfactant (Dowfax 2A1) was stirred with a disk type impeller at 450 rpm for 30 minutes Then, it was slowly added to the reactor for 1 hour. After the addition was completed, a mixture of 3,277 g of distilled water and 90 g of ammonium persulfate was added thereto for 10 minutes, and the reaction was allowed to proceed for about 8 hours, followed by slow cooling to room temperature (25 ° C.) to complete the reaction. As a result, a binder resin was obtained. The glass transition temperature (Tg) and weight average molecular weight of the binder resin measured by the same method as in Production Example 1-1 were 65 ° C and 350,000, respectively.

Manufacturing example  1-3: Binder resin  Preparation of Dispersion (C)

(Dowfax 2A1), 226 g of distilled water, 226 g of a surfactant (Dowfax 2A1), 2 g of polyethylene glycol ethyl ether (meth) acrylate as a macromonomer A binder resin dispersion (C) was prepared in the same manner as in Production Example 1-1 except that 530 g of acrylate and 188 g of 1-dodecanethiol were used as a chain transfer agent. The glass transition temperature (Tg) and weight average molecular weight of the binder resin measured by the same method as in Production Example 1-1 were 57 ° C and 45,000, respectively.

Manufacturing example  2: Preparation of colorant dispersion

540 g of cyan pigment (ECB303, manufactured by Dainippon Ink & Chemicals, Inc.), 27 g of a surfactant (Dowfax 2A1) and 2,450 g of distilled water were placed in a reactor having a volume of 5 liters equipped with a stirrer, a thermometer and a condenser, Respectively. After performing the preliminary dispersion for 10 hours, it was dispersed for 4 hours using a bead mill (Zeta RS, Netzsch, Germany). As a result, a colorant dispersion was obtained.

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

Manufacturing example  3: Preparation of wax dispersion

65 g of a surfactant (Dowfax 2A1) and 1,935 g of distilled water were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a condenser, and the mixture was stirred at 95 ° C for about 2 hours with stirring to obtain solid wax (HNP- Were introduced into the reactor. The mixed solution was dispersed for 30 minutes using a pressure discharge type homogenizer (Nihon Precision Machinery). As a result, a wax dispersion was obtained.

After completion of the dispersion, the particle size of the dispersed wax particles was measured using Multisizer 2000 (manufactured by Malvern), and the D50 (v) was found to be 200 nm.

Example  1 to 4: Preparation of toner particles of core-first shell-second shell structure

(Core part forming step)

The binder resin dispersion (A) prepared in Preparation Example 1-1, the binder resin dispersion (B) prepared in Preparation Example 1-2 and the wax dispersion prepared in Production Example 3 were fed into a 70-liter reactor, And stirred at 25 DEG C for about 15 minutes at a stirring linear velocity of 1.21 m / sec. A mixed solution (PSI / nitric acid aqueous solution = 1/2 (weight ratio)) of PSI (Poly Silcato Iron) and an aqueous nitric acid solution (concentration = 1.88 wt%) was added as a coagulant to the mixture and homogenized (IKA, 50) at 25 DEG C at a stirring rate of 10,000 rpm for 30 minutes. At this time, the pH of the contents of the reactor was 1.6. Thereafter, the temperature of the reactor was elevated to 53 캜 for the first time, and the mixture was stirred at 140 rpm to continue aggregation until the D50 (v) of the toner particles became 5.3 탆

(First cell formation step)

The binder resin dispersion (A) prepared in Preparation Example 1-1, the binder resin dispersion (B) prepared in Preparation Example 1-2 and the binder resin dispersion (B) prepared in Production Example 2 were added to the reactor, The colorant dispersion was added over 30 minutes. Thereafter, the agitation was continued at a stirring speed of 120 rpm until the average particle diameter of the toner particles became 6.3 탆 while the temperature of the reactor was maintained at 53 캜, and agglomeration was continued.

(Second shell portion forming step)

After the first shell portion forming step, the binder resin dispersion (A) prepared in Preparation Example 1-1 and the binder resin dispersion (B) prepared in Production Example 1-2 were added to the reactor over 20 minutes . Subsequently, stirring was continued until the average particle diameter of the toner particles became 6.8 탆 while the temperature of the reactor was maintained at 53 캜.

(Subsequent step)

After the second shell part formation step, a 4 wt% sodium hydroxide aqueous solution was added to the reactor, and the mixture was stirred at 115 rpm until the pH reached 4. When the pH was 7, the mixture was stirred at 100 rpm. Thereafter, the temperature of the reactor was elevated to 96 캜 while maintaining the stirring speed, so that the toner particles were allowed to coalesce. Thereafter, when the circularity was measured using FPIA-3000 (manufactured by Sysmex, Japan), when the measured circularity was 0.980, the temperature of the reactor was cooled to 40 ° C and the pH of the reactor contents was adjusted to 9.0 The separated toner particles were washed four times with distilled water and then mixed with an aqueous nitric acid solution of 1.88 wt% in distilled water to prepare a toner having a pH of 1.5 , And then washed with distilled water four times to remove all of the surfactant and the like. Thereafter, the washed toner particles were dried in a fluid bed drier at a temperature of 40 캜 for 5 hours to obtain dried toner particles. The contents of the components used in the respective Examples, and the glass transition temperature and the weight average molecular weight of the final binder resin are shown in Table 1 below. The binder resin dispersion (A) and the binder resin dispersion (B) were mixed in the ratios shown in Table 1 below and then dried to obtain a solid content of the binder resin . Thereafter, the solid content was dissolved in THF (tetrahydrofuran), analyzed by GPC (gel permeation chromatography) in which black lines were formed with standard polystyrene, and the weight average molecular weight thereof was measured.

Example 1 Example 2 Example 3 Example 4 Core portion
Forming step Binder resin
Dispersion (A) (g) 9,240 8,780 9,240 9,240 Binder resin
Dispersion (B) (g) 0 470 0 0 The glass transition temperature (캜) of the final binder resin 56 57 56 56 The weight average molecular weight of the final binder resin 25,000 43,000 25,000 25,000 Wax dispersion (g) 1,860 1,860 1,860 1,860 Coagulant (g) 4,010 4,010 4,010 4,010 The first shell portion
Forming step Binder resin
Dispersion (A) (g) 2,728 2,632 2,632 2,728 Binder resin
Dispersion (B) (g) 144 248 248 144 The glass transition temperature (캜) of the final binder resin 57 58 58 57 The weight average molecular weight of the final binder resin 43,000 55,000 55,000 43,000 Colorant dispersion (g) 1,460 1,460 1,460 1,460 The second shell part forming step Binder resin
Dispersion (A) (g) 610 610 610 658 Binder resin
Dispersion (B) (g) 108 108 108 62 The glass transition temperature (캜) of the final binder resin 60 60 60 58 The weight average molecular weight of the final binder resin 76,000 76,000 76,000 55,000

Comparative Example  1: Preparation of toner particles of core-shell structure

13,881 g of the binder resin dispersion (C) prepared in Preparation Example 1-3, 2,238 g of the colorant dispersion prepared in Preparation Example 2 and 2,873 g of the wax dispersion prepared in Preparation Example 3 were introduced into a 70-liter reactor, Followed by stirring at 25 DEG C for about 15 minutes at a stirring speed of 80 rpm. 5,760 g of a mixed solution (PSI / nitric acid aqueous solution = 1/2 (weight ratio)) of PSI (Poly Silicato Iron) and an aqueous nitric acid solution (concentration = 1.88 wt%) was added as a coagulant, T-50) at 25 DEG C for 30 minutes at a stirring speed of 10,000 rpm to homogenize the contents of the reactor. At this time, the pH of the contents of the reactor was 1.6. Thereafter, the temperature of the reactor was raised to 53 ° C., and the mixture was stirred at 140 rpm to continue the aggregation until the D50 (v) of the toner particles became 6.4 μm. Thereafter, the binder resin dispersion liquid C) were added over about 20 minutes. Thereafter, stirring was continued until the average particle diameter of the toner particles became 7.0 mu m. Then, a 4 wt% aqueous solution of sodium hydroxide was added to the reactor and stirred at 115 rpm until the pH became 4. When the pH reached 7 The mixture was stirred at 100 rpm. Thereafter, the temperature of the reactor was raised to 96 캜 while maintaining the stirring speed, so that the toner particles were allowed to coalesce. Thereafter, when the circularity was measured using FPIA-3000 (manufactured by Sysmex, Japan), when the measured circularity was 0.980, the temperature of the reactor was cooled to 40 ° C and the pH of the contents of the reactor was adjusted to 9.0 The toner particles were separated by using a nylon mesh (pore size: 16 탆), and the separated toner particles were washed with distilled water four times. Then, a pH of 1.5 was prepared by mixing 1.88 wt% of nitric acid aqueous solution with distilled water And then washed again with distilled water for 4 times to remove all the surfactants and the like. Thereafter, the washed toner particles were dried in a fluid bed drier at a temperature of 40 캜 for 5 hours to obtain dried toner particles.

Comparative Example  2: Single layer  Preparation of Toner Particles of Structure

2300 g of the binder resin dispersion (C) prepared in Preparation Example 1-3, 1,410 g of the colorant dispersion prepared in Preparation Example 2 and 1,100 g of the wax dispersion prepared in Preparation Example 3 were mixed in a 70 L reactor to obtain a mixed solution . 3702 g of a mixed solution (PSI / nitric acid aqueous solution = 1/2 (weight ratio)) of PSI (Poly Silicato Iron) and an aqueous nitric acid solution (concentration = 1.88 wt%) was added as a coagulant and the mixture was homogenized -50) at a speed of 10,000 rpm for 20 minutes. Thereafter, the temperature of the reactor was raised to 53 캜 and agglomeration was continued until D50 (v) was 7.0 탆 (measured using a Multisizer ™ 3 Coulter Counter ^® ). 384 g of a 1N aqueous solution of sodium hydroxide was added to the reactor to stop the growth of the particles while maintaining the aggregation temperature, and the stirring speed was lowered at 80 rpm, and the temperature of the reactor was raised to 95 캜 to aggregate the toner particles. At this time, the unification was continued until the circularity of the toner particles became 0.985. Subsequently, the temperature of the reactor was lowered to 40 ° C, the toner was separated using a filter device (apparatus name: filter press), and then the separated toner was washed with ultrapure water until the electrical conductivity of the washing water became 50 μS / cm or less After washing repeatedly, a 0.3 M nitric acid aqueous solution was mixed with ultrapure water and rewashed with a mixed solution having a pH of 1.5 to make the electrical conductivity of the washing water to be less than 10 μS / cm. Thereafter, a wet cake of the washed toner was dried in a fluidized bed drier to a water content of 1 wt% or less.

Measurement of circularity of toner particles

The circularity of the toner particles in Examples 1 to 4 and Comparative Examples 1 and 2 was measured using FPIA-3000 (manufactured by Sysmex, Japan). In the roundness measurement using FPIA-3000, a measurement sample was prepared by adding a proper amount of a surfactant (Dowfax 2A1) to 50 to 100 ml of distilled water, adding 10 to 20 mg of toner particles thereto, and dispersing the dispersion in an ultrasonic disperser for 1 minute .

The circularity is automatically obtained from FPIA-3000 by the following equation (1).

[Equation 1]

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

In the above equation, the area means the area of the projected toner, and the perimeter means the circumferential length of the projected toner. This value can have a value from 0 to 1, and the closer to 1, the more spherical.

Evaluation example

The toner prepared in Examples 1 to 4 and Comparative Examples 1 and 2 was evaluated in terms of volume average particle size, particle size distribution, charge distribution, image density, toner consumption, transfer efficiency, fixability, fixing temperature range and image quality as follows The results are shown in Tables 2 and 3, respectively.

Volume average particle diameter ( D50 (v)) and Particle size distribution  evaluation

Distribution of the toner particle size (GSDv and GSDp) is Beckman everything between the multi (Beckman Coulter Inc.) low (Multisizer ™ 3 Coulter Counter ^® Using the measured average grain size to the next, is calculated by equation (2), and 3 The aperture was 100 mu m in the above multisizer, and 50 to 100 mL of ISOTON-II (Beckman Coulter Co.), which is an electrolytic solution, was added to a surfactant ( Dowfax 2A1) was added in an appropriate amount, 10 to 15 mg of a measurement sample was added thereto, and the mixture was dispersed in an ultrasonic disperser for 5 minutes to prepare a sample.

&Quot; (2) &quot;

(p: 입자수)
GSDp =

(p: number of particles)

In the formula (2), GSDp is a particle size distribution based on the number of particles. The smaller the particle size distribution, the narrower the particle size distribution. D16p and D84p measure the particle diameters of the toner particles, Means a particle size corresponding to 16% and 84% of the number of particles.

&Quot; (3) &quot;

(v: 부피)GSDv =

(v: volume)

In Equation (3), GSDv is a volume-based particle size distribution. The smaller the particle size distribution, the smaller the particle size distribution. D16v and D84v are the particle sizes of the toner particles, 16% and 84%, respectively.

Charge amount evaluation

The charge distribution of the toner was measured using a q / m meter (Epping, Germany). 0.7 g of the toner particles prepared in each of the above Examples and Comparative Examples and 9.3 g of carrier (100 탆, Japan Atomic Chemical Society) were placed in a 100-mL-tube and then allowed to stand for 8 hours or longer under NN condition (20 캜 and 50% RH) Respectively. Subsequently, the mixture was mixed at 96 rpm for 10 minutes using a Turbula mixer (WAB, Switzerland). After mixing, 1.0 g of sample was placed in a measuring cell of q / m meter, and the charge was measured under NN condition by scanning under conditions of 2 L / min and 100 voltage.

Image density evaluation

Image density evaluation was performed by developing a device that modified CLP-510 (Samsung), a digital full-color printer. The image density was measured using a Spectroeye spectrophotometer (GretagMacbeth).

Evaluation of Toner Consumption

Using the toner particles prepared in the above-described Examples and Comparative Examples, 1,000 sheets of A4 paper were printed using a 3% print character ratio image on a Samsung CLP-510 printer, the weight of the developing device and the waste toner were measured, The toner consumption per 1000 sheets was calculated as shown in the following equation (4).

&Quot; (4) &quot;

Toner consumption per 1,000 sheets = (initial developer weight) - [(developer weight after output) - (waste toner weight after output)]

Evaluation of transfer efficiency

The toner particles prepared in the above Examples and Comparative Examples were used to inhale the toner of the organic photoconductor drum, the intermediate transfer member, and the paper after transferring using a 2 cm * 2 cm solid pattern in the Samsung CLP-510 printer, Respectively. Transfer efficiencies were calculated from the following weighted values by the following equations (5) and (6).

&Quot; (5) &quot;

Primary transfer efficiency (%) = [(amount of toner on the intermediate transfer member) / (amount of total pre-toner on the photosensitive member)] * 100

&Quot; (6) &quot;

Secondary transfer efficiency (%) = [(amount of toner on paper) / (total amount of pre-toner on intermediate transfer member)] * 100

Evaluation of fixability and fixing temperature range

- Equipment: belt type fuser

- Unfixed images for test: 100% pattern

- Test temperature: 110 ~ 210 ℃

- Speed: 160 mm / sec

- Dwell time: 0.08 sec

(TG 810G; manufactured by Cabot Corporation) and 0.05 g of silica (RX50, manufactured by Degussa) under the above-mentioned conditions were mixed with 9.75 g of the toner particles prepared in the above Examples and Comparative Examples, To collect unfixed images on a 30mm x 40mm solid on a Samsung CLP-510 printer. Then, the fixability of the unfixed image was evaluated while changing the temperature of the fixing roller in a fixing tester modified so that the fixing temperature could be arbitrarily changed. After the OD (Optical Density) of each fixed image was measured, an 810 tape of 3M company was attached to the fixed image area, and 500 g of the spindle was reciprocated 5 times on the tape. After removing the tape, OD was measured again. The fixability was calculated by the following equation (7).

&Quot; (7) &quot;

Fixability (%) = [(OD after tape removal) / (OD before tape removal)] * 100

The fixing temperature range in which the fixing property was 90% or more without regard to cold offset or hot offset was regarded as the fixation temperature range of the toner. That is, the fixing temperature range of the toner is the following MFT to HOT.

- Minimum Fusing Temperature (MFT): Minimum temperature at which fixability is 90% or higher without cold offset

- HOT (Hot Offset Temperature): The fixability is 90% or more, but the lowest temperature at which hot offset occurs

Image quality evaluation

(TG 810G; manufactured by Cabot), and 0.05 g of silica (RX50, manufactured by Degussa) were used to prepare toner particles of external N2 images of JIS-JIS-SCID were output from the CLP-510 printer, and image quality was evaluated based on the following criteria.

- ○: The detail of the image is clearly visible

- Δ: slightly outdated

- ×: Image detail is broken

D50 (v)
(탆) GSDp GSDv Charge amount
(μC / mg) Image density
Toner consumption (g) Example 1 6.96 1.24 1.22 -54.8 1.38 13.6 Example 2 6.92 1.24 1.22 -56.2 1.40 13.7 Example 3 6.97 1.23 1.22 -53.9 1.37 13.1 Example 4 6.92 1.24 1.21 -54.7 1.37 13.0 Comparative Example 1 6.90 1.24 1.21 -51.1 1.24 15.0 Comparative Example 2 6.94 1.25 1.23 -51.0 1.18 17.3

Transfer efficiency (%) Fixability
(%) Fusing temperature range (℃) Image quality Primary Secondary Example 1 97.0 94.7 99.1 120-190 ○ Example 2 93.2 93.6 99.4 130 ~ 200 ○ Example 3 96.5 93.4 98.7 120-190 ○ Example 4 93.7 92.2 97.9 130 ~ 200 ○ Comparative Example 1 92.6 90.9 92.2 140-190 △ Comparative Example 2 90.4 87.1 85.7 140-170 ×

Referring to Tables 3 and 4, the toners prepared in Examples 1 to 4 were higher in charge amount and fixability than the toners prepared in Comparative Examples 1 and 2, and showed excellent image quality. In particular, the toners prepared in Examples 1 to 4 were found to have a wider fixing temperature range and better low temperature fixability than the toners prepared in Comparative Examples 1 and 2.

Although the present invention has been described with reference to the drawings and embodiments, it is to be understood that various changes and modifications may be made without departing from the scope of the invention as defined by the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

1: Colorant 2: Wax
3a: first binder resin 3b: second binder resin
3c: third binder resin 4: external additive
10: core part 20: first shell part
30: second shell part

Claims (10)

A core portion comprising a first binder resin and a wax;
A first shell portion including a second binder resin and a colorant and surrounding the core portion; And
And a second shell portion including a third binder resin and surrounding the first shell portion,
Wherein the first shell part and the second shell part do not contain wax. The method according to claim 1,
Wherein the core portion and the second shell portion do not contain a coloring agent. The method according to claim 1,
Wherein a weight average molecular weight (Mw ₁ ) of the first binder resin, a weight average molecular weight (Mw ₂ ) of the second binder resin and a weight average molecular weight (Mw ₃ ) of the third binder resin satisfy the following formula:
Mw ₁ < Mw ₂ < Mw ₃ . The method of claim 3,
Wherein the weight average molecular weight of the first binder resin (Mw ₁₎ is 24,000 ~ 45,000, and wherein the weight average molecular weight of the second binder resin (Mw ₂₎ is 42,000 ~ 55,000, and a weight average molecular weight of said third binder resin (Mw ₃ ) Is from 55,000 to 79,000. The method according to claim 1,
Wherein the toner comprises 70 to 90 parts by weight of the first binder resin, 5 to 25 parts by weight of the second binder resin, and 1 to 6 parts by weight of the third binder resin. Adding a first binder resin dispersion liquid, a wax dispersion liquid and a coagulant to a reactor, and then raising the reactor contents first to form a toner core section;
Adding a second binder resin dispersion liquid and a colorant dispersion liquid to the reactor contents containing the toner core portion to form a first shell portion surrounding the toner core portion;
Further adding a third binder resin dispersion to the reactor contents containing the first shell portion to form a second shell portion surrounding the first shell portion; And
And secondarily raising the reactor contents through the second shell part forming step to obtain unified toner particles. The method according to claim 6,
Wherein the primary temperature elevation progresses to a temperature 2 to 20 占 폚 lower than a glass transition temperature of the first binder resin injected into the core portion forming step. The method according to claim 6,
Wherein the secondary increase in temperature progresses to a temperature 10 to 40 캜 higher than a glass transition temperature of the third binder resin added to the second shell part forming step. The method according to claim 6,
The weight average molecular weight (Mw ₁ ) of the first binder resin injected in the core forming step, the weight average molecular weight (Mw ₂ ) of the second binder resin injected in the first shell forming step and the weight average molecular weight 3 The weight average molecular weight (Mw ₃ ) of the binder resin satisfies the following formula:
Mw ₁ < Mw ₂ < Mw ₃ . The method according to claim 6,
The binder resin added to the toner manufacturing method preferably has a ratio of 70 to 90 parts by weight, 5 to 25 parts by weight and 1 to 6 parts by weight to the core portion forming step, the first shell portion forming step and the second shell portion forming step, respectively By weight of the toner.

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