KR20100062107A - Preparation method of toner for forming improved electrostatic images - Google Patents

Abstract

The present invention relates to a method for preparing a toner in which a temperature gradient condition of a melt kneading extruder is set when a toner containing two or more binder resins having different softening temperatures is set, and excellent in dispersibility of toner components and in a wide range. By exhibiting offset resistance and uniform physical properties, there is an advantage that a good image can be obtained.

Description

Preparation Method of Toner for Forming Improved Electrostatic Images

The present invention relates to a process for producing toner for forming an improved electrostatic image (i.e., high speed and high resolution images). More specifically, the present invention provides an improved electrostatic charge image having excellent offset resistance and uniform physical properties by setting the temperature gradient conditions of an extruder for melt kneading when preparing a toner including two or more binder resins having different softening temperatures. A manufacturing method of a toner for a solvent is provided.

Looking at the trend of the recent print technology, colorization is rapidly progressing with digitization. In particular, researches on an image forming method for realizing a high quality image and a toner used therein have been actively conducted with the spread of digital devices.

In this regard, an electrophotographic image forming method is characterized in that an electrostatic latent image formed on a photosensitive member by optical means is developed through a developing step, and then transferred to a recording medium such as a recording paper in a transfer step, followed by heat and It is a method of obtaining an image by fixing to a recording medium by pressure or the like.

To visualize and develop the electrostatic latent image, a toner powder obtained by kneading (mixing) and pulverizing a color pigment or the like in a resin is used. Such toners generally include a raw material mixing step, a melt-kneading step, It is prepared through a pulverization / classification step and an external step step.

In general, toner is required to have fixing property, offset resistance, charging stability, and the like, and recently, it is required to have improved physical properties in terms of glossiness, durability, storage stability, and the like of the fixed toner to obtain a high quality image.

In particular, the binder resin for toner is known as a component having a great influence on the physical properties of the toner, and various manufacturing techniques using a polyester resin having excellent melting and grinding characteristics have been developed.

Typically, polyester resins having a low molecular weight and a low softening temperature are advantageous for improving the glossiness of the toner, but have disadvantages of lowering offset resistance and durability. On the other hand, polyester resins having a high molecular weight and a high softening temperature are advantageous for improving melt viscosity characteristics of toner and improving offset resistance, but have problems of lowering glossiness and low temperature fixability.

In order to compensate for the above problems and to meet the improved fixability and offset resistance in a wide temperature range, the use of two or more binder resins based on molecular weight or softening point is proposed, rather than one polyester resin alone.

For example, Korean Patent Publication No. 2006-74092 has an acid value of 25 KOH mg / g or less, a softening point of 140 to 215 ° C., and a glass conductivity of 50 to 70 in order to improve fixability and offset resistance. Polyester and acid value of the high softening point of ℃ ℃ 40KOH mg / g or less, softening point of 100 to 150 ℃, and the glass transition temperature is 50 to 65 A toner composition comprising a polyester having a low softening point of ° C is disclosed.

Japanese Patent Publication No. 2007-148085 discloses an electrostatic charge phenomenon in which a polyester resin having a softening point of 145 to 190 ° C. and a polyester resin having a softening point of 85 to 130 ° C. is used as a binder resin or a binder resin to contain a colorant, a release agent, and the like. A toner for a solvent is disclosed.

As described above, the method of using two or more kinds of binder resins having different molecular weights or softening points is not easy to control the flow characteristics according to the temperature of each of the plurality of binder resins during melt kneading, leading to deterioration of physical properties of the toner.

On the other hand, the additives used in toner production reduce the resistance of the rotating part which rotates the developing sleeve in the developing process, and prevent the toner from fusing to the charging blade or the agglomeration of the toner particles, thereby making the toner uniform and stable with low torque. Get a floor. In addition, the toner exhibits a stable range of stable charging characteristics, and has a uniform melting characteristic during the fixing process. In this case, when the additive is not uniformly added to the surface of the toner, the charging properties of the particles are different from each other, and a uniform image may not be obtained, and problems such as melt unevenness may occur during the fixing process. In this case, a phenomenon in which an image becomes blurred and uneven in a long term appears. In order to solve the above problems, the design of the selection of the appropriate additives, the content and dispersion conditions, the toner particle size and the like should be considered.

In particular, the degree of dispersion of the raw material components for toner production using the melt kneading apparatus may be insufficient due to the limitation of the residence time due to the flow characteristics of the continuous kneading apparatus. In addition, even if the residence time is increased as much as possible, the inherent dispersion capacity is encountered, and the toner constituents are often difficult to mix at an optimum ratio due to the adhesion of the fine raw material components to the inner wall of the kneading apparatus or the aggregation of fine particles.

Therefore, in recent years, in order to solve such a problem, various methods regarding the preliminary kneading technique or the melt kneading technique consisting of a plurality of steps have been prepared.

In this regard, US Pat. No. 6,232,030 discloses a composition comprising a binder resin and a colorant in an open roller type continuous kneader (with heating and cooling functions, wherein a plurality of openings are melt kneaded along the axial direction of the roller of the kneader). It is disclosed for the toner manufacturing process comprising the step of melt kneading. According to this patent, melt kneading is continuously supplied with 6 to 70% by weight of the binder resin to be blended at a position of 0 L to 0.5 L from the roller end at the inlet side of the kneader (L is the length of the roller), and colorant 50 to 100 The weight percent is carried out in such a way that it is continuously fed at a position of 0L to 0.5L. However, in the case of the patent, problems of scattering and gas treatment of the raw materials due to the use of an open kneader may be caused, and the raw material composition may be affected by the external temperature.

As a remedy for this, Korean Patent No. 573882 uses a twin screw extruder, wherein the distance to the die at the tip of the extruder is L based on the inlet of the extruder for melt kneading the toner composition. When the outflow start temperature of the resin was TFB ° C, the temperature gradient of the extruder was maintained at TFB + 20 ° C to TFB + 90 ° C in the 0 to 3 / 8L section from the raw material inlet in the die direction toward the tip. Maintaining at TFB to TFB + 50 ° C. at 8L to 6 / 8L, and maintaining at TFB to TFB-100 ° C. at 6 / 8L to L; And a method of preparing a toner by injecting a toner composition through the raw material inlet and obtaining a toner composition passed through the extruder in the die.

In the case of the above-described technology, there is a limit to solve the problem that the binder resin properties such as molecular weight, gel content, etc. are greatly changed due to the process conditions subjected to heat and stress, especially in the melt kneading process consisting of a plurality of steps. In addition, when using two or more kinds of binder resins having different fluidity or behavior characteristics depending on temperature in order to improve the physical properties of the toner, the above technical limitations are more problematic, and thus solutions are urgently required.

As a result of continuous research, the present inventors have used two or more polyester resins having relatively different softening temperatures as binder resins, and melt kneading in consideration of changes in physical properties of the binder resins and other toner manufacturing components with temperature. It has been found that the above limitations of the prior art can be overcome by deriving the temperature gradient conditions in the process (eg melt kneading in the barrel of the extruder).

Accordingly, an object of the present invention is to overcome the problems caused when using two or more binder resins having different fluidity according to temperature in the melt kneading step for preparing toner, and at the same time, to reduce the agglomeration between the fine particles and the physical properties of the binder resin. It is to provide a method for producing a toner having a minimum offset resistance and uniform physical properties in a wide range.

Another object of the present invention is to provide a method of manufacturing a toner capable of increasing the efficiency of kneading in consideration of thermal properties of the toner constituents including two or more binder resins.

According to one embodiment of the present invention, a toner manufacturing method comprising melt-kneading a raw material for producing a toner comprising two or more polyester resins having different softening temperatures as a binder resin in an extruder,

When the distance to the extruder tip die is defined as L from the raw material inlet of the extruder, and the softening temperature of the resin having the highest softening temperature among the two or more binder resins is defined as T _m , the tip die from the raw material inlet of the extruder is defined. A toner manufacturing method is provided, wherein a temperature gradient condition is maintained as follows:

(i) T _m -50 ° C to T _m -20 ° C in an interval of 0-1 / 10L;

(ii) in the 1 / 10L ~ 2 / 10L interval, T _m -30 ℃ ~T _m;

(iii) 2 / 10L ~ in the 6 / 10L _{interval, T m -10 ℃ ~T m +} 40 ℃;

(iv) T _m −20 ° C. to T _m + 20 ° C. in the range 6 / 10L to 9 / 10L; And

(v) T _m -50 ° C. to T _m in the range 9 / 10L to L.

At this time, a part of the raw material for preparing the toner may be preliminarily kneaded to prepare a master batch, and then melt kneaded by introducing it into an extruder.

The toner manufacturing method according to the present invention dispersibility of toner components by newly deriving a temperature gradient condition during the melt kneading step performed to prepare a toner including two or more polyester binder resins having different softening temperatures. This excellent and wide range of offset resistance and uniform physical properties are provided to provide a toner capable of obtaining a good image. Therefore, broad commercialization is expected in the future.

The present invention can be achieved by the following description with reference to the accompanying drawings. It is to be understood that the preferred embodiments of the invention are described, but the invention is not necessarily limited thereto.

Binder resin

In the present invention, the binder resin corresponding to the main constituent of the toner exhibits a relatively low softening temperature (softening point) and glass transition temperature (Tg) as compared to other polymer resins, and is advantageous for image formation under low fixing temperature. In addition, polyester resins are used to increase the durability and efficiency of the electrostatic charge image developing apparatus. Such polyester-based resin is preferably about 1,000 to 200,000, more preferably a weight average molecular weight (Mw) of about 5,000 to 150,000, preferably about 80 to 190 ° C, and more preferably about 100 to 170 ° C. Temperature, and preferably about 40-80 ° C., more preferably about 55-75 ° C.

In this connection, in this invention, 2 or more types of polyester resin from which softening temperature differs among the polyester resin mentioned above is selected and used as a binder resin. According to a preferred embodiment of the present invention, a polyester resin (A1) belonging to a relatively high softening point region and a polyester resin (A2) belonging to a relatively low softening point region are used together. At this time, one or more resins may be selected from each of the resin of the high softening point region and the resin of the low softening point region. As described above, the reason why the resins in the high softening point region and the low softening point region are used simultaneously is advantageous in improving the advantages, durability, and offset resistance of the low softening point polyester resin, which is advantageous for the glossiness and low temperature fixability of the toner, as described above. It is to satisfy the advantages of the high softening point polyester resin to meet improved fixability, offset resistance, glossiness and the like in a wide temperature range.

In this embodiment, preferred examples of the resin (A1) in the high softening point region exhibit a weight average molecular weight (Mw) of about 50,000 to 200,000, a softening temperature of about 120 to 190 ° C, and a glass transition temperature of about 50 to 80 ° C. . On the other hand, a preferable example of the resin (A2) in the low softening point region shows a weight average molecular weight (Mw) of about 1000 to 100,000, a softening temperature of about 80 to 130 ° C, and a glass transition temperature of about 40 to 70 ° C.

In this regard, the softening point difference between the resin (A1) in the high softening point region and the resin (A2) in the low softening point region is preferably about 5 to 100 ° C, more preferably about 10 to 80 ° C. As described above, it is advantageous to keep the softening point difference in the above-mentioned range in order to obtain an improved toner by utilizing the properties between resins having different softening points and molecular weights.

On the other hand, according to a more preferred embodiment of the present invention, the mixing ratio (weight basis) of the high softening point resin (A1) and the low softening point resin (A2), that is, A1 / A2 is from about 0.1 to depending on the fixing temperature range of the toner particles required. 9.0, more preferably about 0.5-5.

According to an embodiment of the present invention, if the total content of the binder resin contained in the toner is too small, there may be a problem in the fixability of the toner, while in the case of too much, the problem of offset may occur. In view of this, the total content of the binder resin is preferably in the range of about 68 to 98% by weight, more preferably about 80 to 95% by weight, based on 100 parts by weight of the toner. On the other hand, only a polyester resin may be used as the binder resin as a constituent of the toner, but in some cases, a styrene resin, an acrylic resin, a styrene-acrylic resin, a polyolefin resin, and a polyamide resin may be used for the polyester resin. , Polyurethane resins, polycarbonate resins, or copolymers thereof may be used alone or in combination of two or more thereof. At this time, the content of the additional resin is preferably up to about 80% by weight, more preferably up to about 40% by weight in the binder resin.

Hereinafter, the additive component which is used together with the above-mentioned binder resin and comprises the raw material for toner manufacture is demonstrated. Each of these additives may be added alone to the binder resin, but in some cases, may be used in appropriate combination.

coloring agent

As the colorant usable in the present invention, those known in the art may be used without particular limitation, and specifically, various pigments and / or dyes of inorganic or organic may be used. Representative examples thereof include carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base (bass ), Sorbent red 49, sorbent red 146, sorbent blue 35, quinacridone, carmine 6B, disazo erosion, and the like. The said coloring agent can be used individually or in combination of 2 or more types.

When the content of the colorant is too small may have a problem in the light transmittance, while in the case of too much content may have a problem in dispersibility. In consideration of this, it may be preferably contained in the range of about 1.0 to 30% by weight, more preferably about 3.0 to 10% by weight based on 100 parts by weight of the toner. The colorant component may be introduced in the form of a master batch with a binder resin and other additives in consideration of dispersibility during melt kneading.

Wax

In an embodiment of the present invention, the wax component functions as a release agent, and those known in the art can be used without particular limitation. Both low melting point waxes and high melting point waxes can be used. Low melting waxes having a relatively low viscosity include carnauba wax, rice wax, natural plant ester waxes such as montan wax, paraffin wax, and the like. And synthetic hydrocarbon waxes such as polypropylene wax.

According to a preferred embodiment of the present invention, the cold offset (hot-offset) and hot offset (hot-offset) according to the temperature-specific viscosity characteristics of the wax to compensate for, and prevent the paper jam (wrap jam) in the fixing unit during image formation In order not to do so, waxes having different melting points may be used in combination. At this time, the melting point of the low melting wax is preferably about 50 to 100 ℃, the melting point of the high melting wax is preferably about 100 to 170 ℃.

In the case where the content of the wax is too high or too low, it is preferably about 0.5 to 10% by weight, more preferably about 2 to 5, based on 100 parts by weight of the toner, in consideration of problems in offset resistance and durability. It is contained in the toner in the weight range.

The wax may be introduced in the form of a master batch with a binder resin and other additives in consideration of dispersibility during melt kneading.

Charge control agent

According to an embodiment of the present invention, a charge control agent is added in order to stabilize the charging characteristics of the toner for electrostatic image development and to produce a toner capable of obtaining a high image by minimizing the generation of residual amount during image formation.

The charge control agent is not particularly limited, but may include quaternary ammonium salts, resins containing quaternary ammonium salts or amino groups, azo metal compounds, acetyl acetone metal compounds and their complexes, benzyl acids and aromatic hydroxycarboxes. Main acid system, various black acid system, salicylic acid system, phthalocyanine, perylene, quinacridone, metal salt or complex of nitrogen compound, boron compound or complex thereof, sulfonic acid salt containing carboxyl group, sulfonyl group, Triphenyl methane type, trimethyl ethane type, nigrosine dye, etc. can be used.

When the content of the charge control agent is too small, it is difficult to expect to control the amount of charge of the toner particles, while when too much, there is a problem that it is difficult to obtain stable charging characteristics. In consideration of this, it is preferably contained in the range of about 0.3 to 5% by weight, more preferably about 0.5 to 2% by weight, based on 100 parts by weight of toner particles.

The charge control agent used in the present invention may impart improved compatibility and dispersibility by master batching with the binder resin and other additive components.

In addition, the charge control agent may be used in an external process for imparting charging stability of toner particles together with titanium oxide, resin powder, and the like.

As described above, in the embodiment of the present invention, the preferred composition of the raw material for toner production into the extruder during melt kneading contains an internal additive based on the binder resin, and more specifically, the binder is based on 100 parts by weight of the toner. About 68-98 weight percent resin, about 1.0-30 weight percent colorant, about 0.5-10 weight percent wax, and about 0.3-5 weight percent charge control agent.

According to the present invention, a kneaded product obtained by melt kneading a binder resin and an additive such as a colorant is processed in the order of cooling, pulverization and classification to have an average particle diameter of a particle toner (for example, about 3 to 15 microns). ). By attaching various additives to the surface of such particulate toner, flow characteristics, charging characteristics, and the like can be improved. The external additive will be described below. However, in the present specification, the component is described as to adhere to the surface of the toner particles, but in some cases, at least one of the components may be used as an internal additive in the melt kneading step together with additive components such as colorants, waxes, and charge control agents. have.

External additive

As mentioned above, according to an embodiment of the present invention, the toner preferably includes at least one external additive in addition to the above-mentioned binder resin, colorant, wax, and charge control agent. Such external additives may be used by selecting one or two or more from inorganic fillers, fluidity improvers, and charge stabilizers known in the art. An example of this is as follows:

Since it is preferable that it is two or more types of silica from which an average particle diameter differs as said external additive, the reason for adding two or more types of silicas is for making flowability and durability compatible. At this time, it is preferable that two or more kinds of silica are selected within an average particle diameter range of 5 to 50 nm.

The surface of the silica may preferably be hydrophobized, with representative treatment agents used therein being silane coupling agents, silicone oils, or mixtures thereof. As described above, silica may be added as an external additive, but in some cases, silica may be added as an internal additive during raw material mixing. The amount of the external additive, especially silica, is preferably about 0.1 to 3 parts by weight based on 100 parts by weight of the toner particles.

In addition to silica, hydrophobized titanium oxide, various metal oxides (alumina, cerium oxide, barium titanate, strontium titanate, etc.), metal soaps such as zinc stearate, and spherical resin fine particles (for example, particle sizes of about 0.1 to 2 microns) Melamine formaldehyde resin) and the like may be used alone or in combination of two or more. The amount of the external additives other than the silica component is preferably in the range of about 0.1 to 1 parts by weight based on 100 parts by weight of the toner particles.

Melt kneading apparatus

The conventionally known toner manufacturing method is a raw roll toner manufacturing method using a mixer such as Henschel mixer, turbine type stirrer, super mixer, ball mill, and the like, followed by an open roll-type kneader, single screw or twin screw extruder. Kneading using a melt kneading machine, and the like, and cooling the kneaded dough obtained therefrom, and then mechanically pulverizing using an impact mill such as a hammer mill, finely pulverizing using a jet mill or the like, and then classifying It involves the process of attaching externally. In this regard, the present invention provides an improved method compared to the prior art in the melt kneading process as follows.

1 is a view schematically showing a twin screw extruder for melt kneading usable in a preferred embodiment of the present invention and a screw structure in the extruder.

According to the drawing, when the distance from the raw material inlet to the die at the tip of the extruder is defined as L, at least one kneading in the 3/10 to 6 / 10L section from the raw material inlet of the extruder toward the die (D) in the tip direction. Is located. This is for the efficient dispersion of the kneaded dough component in the melt kneading process. On the other hand, as shown, the vent portion may be located in the 8/10 to 9 / 10L section, the vent portion may be arranged in different positions or a plurality as necessary.

In addition, additive components kneaded with the binder resin (colorants, waxes, charge control agents and / or optionally external additives) may be introduced into the melt kneading step together with the binder resin through a melt kneading apparatus, that is, a raw material inlet of an extruder. In some cases, it may be introduced into the melt kneading step through a plurality of feeders or a plurality of inlets.

As described above, the present invention sets the temperature gradient conditions in the melt kneading process in consideration of the dispersion efficiency and temperature-dependent flow characteristics of each binder resin and additives. For this purpose, a screw type continuous twin screw extruder is preferably used.

According to the present invention, when the softening temperature of the resin having the highest softening temperature among two or more binder resins is defined as T _m , the temperature gradient condition is maintained in the direction of the tip die from the raw material inlet of the melt kneading apparatus, that is, the extruder as follows. do.

(i) in the range from 0 to 1 / 10L, T _m -50 ° C to T _m -20 ° C, preferably T _m -30 ° C to T _m -20 ° C.

(ii) 1 / 10L ~ 2 / 10L period, T _m -30 ℃ ~T _m, preferably T _m -20 _m ℃ ~T

(iii) 2 / 10L ~ 6 / 10L in the period _{T m -10 ℃ ~T m + 40} ℃, preferably from T _m + 20 _m ~T ℃

(iv) in the range of 6 / 10L to 9 / 10L, T _m -20 ° C to T _m + 20 ° C, preferably T _m -10 ° C to T _m + 10 ° C.

(v) T _m -50 ° C to T _m , preferably T _m -30 ° C to T _m -20 ° C in a 9 / 10L to L section.

As described above, in the extrusion kneading process, the binder resin receives the highest shear stress and controls the temperature gradient of each barrel as low as possible except for the area around the kneading portion for the purpose of effective dispersion of the additives, thereby minimizing the toner physical degradation. can do.

By setting the temperature gradient in the melt kneading apparatus described above, a toner having excellent dispersibility with respect to the constituents of the above-described raw materials for toner production and having a low deterioration in binder resin intrinsic properties during toner processing can be produced. Furthermore, when using two or more kinds of binder resins having different softening temperatures or melting viscosities, setting a higher processing temperature may cause changes in physical properties such as molecular weight or gel content of the binder resin having a lower softening temperature. If it is set to low, it is difficult to expect the effect of efficient melt kneading, or the binder resin of the high softening point may undergo a change of resin properties due to excessively high shear stress. On the other hand, under the temperature gradient conditions in the extruder newly derived from the present invention, it is possible to drastically improve the problem of deterioration in the dispersibility of the raw material components and deterioration of the toner properties which may be caused by the use of two or more binder resins.

The above-mentioned temperature gradient conditions in the present invention are particularly advantageous in producing toner as follows:

According to the present invention, it is preferably accompanied by a melt kneading step consisting of two steps. Specifically, additives for toner production, such as colorants, waxes, charge control agents, etc., are limited in terms of dispersibility in a binder resin according to their types. In this case, it is possible to improve the physical properties of the toner by manufacturing in the form of a master batch and introducing it into the main melt kneading process. For example, preliminarily kneading a part of the binder resin and at least a part of the additive using an open roll-type kneader or the like to prepare a master batch, and then using a melt kneading apparatus (for example, a twin screw extruder) Melt kneading with all other homogeneous or heterogeneous binder resins, except the binder resin used in the one-step kneading process (kneading temperature: about 50 to 150 ° C.), and the remaining additives (if all of the additives are not used in the master batch step) As a result, a toner having stable dispersibility and physical properties can be produced.

However, in the case of the two-step melt kneading process as described above, compared to the general toner manufacturing process using only a twin screw extruder, the melt kneading process by heat and shear stress is performed twice, so that the binder resin inherent unless the processing temperature conditions are properly set. The risk of deterioration of physical properties increases. The present invention can effectively solve the problems caused by the use of a plurality of binder resins having different softening temperatures.

It can be produced in the form of particles via melt kneading step according to the invention and subsequent steps (cooling, coarsely pulverized / pulverized), wherein the average particle size is typically in the range of about 3 to 15 microns.

The present invention can be more clearly understood by the following examples, which are only intended to illustrate the present invention and are not intended to limit the scope of the invention.

Example 1

As shown in Table 1 below, two kinds of polyester resins having different softening temperatures were used, and were carried out using an open roll type kneader and a melt kneading apparatus shown in FIG.

TABLE 1

Binder resin A1 A2 Glass transition temperature (℃) ¹ 71 62 Softening Temperature (℃) ² 145 115 Molecular Weight (Mw) 101,000 24,000

¹ : A differential scanning calorimeter (DSC Q100, TA Instrument) was used. The temperature increase rate was 10 ° C./min, the temperature was raised from 20 ° C. to 150 ° C., and after quenching to 20 ° C., the temperature was raised to 150 ° C. again.

² : A flow tester (CFT-500D, Shimadzu) was used, and a nozzle of 1 mm in diameter and 1 mm in height, a load of 20 kgf, and a heating rate were measured at 6 ° C / min. From the temperature-piston stroke curve, 1/2 of the difference between the piston stroke value corresponding to the outflow start temperature and the end temperature was determined, and the temperature corresponding to the piston stroke value was obtained to determine the softening temperature.

The composition of the raw materials for preparing toner, except for the external additive, was as follows:

93 weight% of binder resin (A1 + A2), 3.5 weight% of carbon black (B1, Mogul-L, Cabot), 1.0 weight of quaternary ammonium salt (C1, T-77, Hodogaya Chem.) %, Carnauba wax (D1, Towax-143, Toa Kasei) 1.5% by weight and low molecular weight polypropylene wax (D2, Viscol 660P, Sanyo Chem.) 1.0% by weight, the weight between the binder resins A1 and A2 The ratio (A1 / A2) was adjusted to 4/1.

First, a master batch was prepared by preliminarily kneading a polyester resin (A2), a coloring agent (B1), and a low melting wax (D1) having a softening temperature of 115 ° C at 120 ° C using an open roll type kneader. The master batch thus prepared and the polyester resin (A1), the charge control agent (C) and the high melting point wax (D2) having a softening temperature of 145 ° C. were mixed using a Henschel mixer, and then L / D shown in FIG. Through a raw material inlet of the = 35 twin-screw extruder freely dropped at a feed rate of 15 kg / hr based on the binder resin supply, and melt kneaded at a screw rotation speed of 200 rpm.

The temperature gradient in the extruder is 115-120 ° C. in the 0-1 / 10L section, 135-140 ° C. in the 1 / 10L-2 / 10L section, and 2 / 10L-6 / 10L section in the direction of the tip die from the raw material inlet. At 155 ~ 160 ℃, 6 / 10L ~ 9 / 10L sections, 135 ~ 140 ℃ and 9 / 10L ~ L sections were maintained at 115 ~ 120 ℃, respectively.

After cooling the melt-kneaded mixed dough under the temperature gradient conditions, each of them was crushed (coarsely pulverized / pulverized) in two stages using a hammer mill and a jet mill type 100AFG (Hosokawa Alpine) pulverizer, respectively, and 50ATP (Hosokawa). Air classification was performed using an Alpine classifier. 1.0 parts by weight of each of two hydrophobic silicas E1 (RX300, Aerosil) and E2 (H05TD, Wacker) having different average particle diameters to the toner particles having an average particle diameter of 6 to 10 µm thus obtained, and an acrylic styrene resin powder (F, MP- 1000, soken chemical co.) 0.5 parts by weight of a high-speed mixing / adhesion using a Henschel mixer to prepare a final toner.

Example 2

The same manner as in Example 1, except that the polyester resin (A1 and A2), the colorant, the wax and the charge control agent were directly fed into the twin screw extruder shown in FIG. Toner was prepared.

Comparative Example 1

During the melt kneading step, the temperature gradient of the twin screw extruder is directed from the raw material inlet to the tip die direction, 130 to 135 ° C for 0 to 1 / 10L sections, 145 to 150 ° C for 1 / 10L to 2 / 10L sections, and 2 / 10L to 9 / Toner was prepared in the same manner as in Example 1, except that the mixed dough was prepared by maintaining at 155 to 160 ° C in the 10L section and 160 to 170 ° C in the 9 / 10L to L section.

Comparative Example 2

In the same manner as in Comparative Example 1, except that the polyester resins (A1 and A2), the colorant, the wax and the charge control agent were prepared without being preliminarily kneaded, and fed directly into the twin screw extruder shown in FIG. Toner was prepared.

The physical properties of each of the toner particles obtained in Examples and Comparative Examples were evaluated as follows, and the results are shown in Table 2.

TABLE 2

Properties Example Comparative example One 2 One 2 Low Temperature Fixability ³ ◎ ○ ○ △ Offset Resistance ⁴ ○ ◎ × △ Dispersibility ⁵ ◎ △ ◎ △

³ : The minimum temperature at which the toner can be fixed to paper was measured by a fixing roller of 100 mm / s speed without silicone oil applied using a printer capable of setting and changing the temperature. In order to judge whether or not the toner was fixed, it was visually observed whether or not agglomeration of the fixed image occurred, and evaluated according to the following criteria.

◎ (very good): Fusing temperature is lower than 120 ° C

○ (good): The fixing temperature is 120 ° C or more and less than 130 ° C

△ (usable): Fusing temperature is 130 ° C or more and less than 150 ° C

× (defect): fixing temperature is 150 degreeC or more

⁴ : When the toner was fixed while the set temperature of the fixing roller was raised sequentially and repeatedly using the printer, visual observation was performed on whether or not toner contamination on the transfer paper occurred, and offset generation occurred at the lowest temperature at which contamination by the toner occurred. The temperature was taken and evaluated according to the following criteria.

(Excellent): Offset generation temperature is 220 degreeC or more

○ (good): offset generation temperature is 200 ° C or more and less than 220 ° C

△ (usable): offset generation temperature is 180 ° C or more and less than 200 ° C

× (defect): Offset generation temperature is 180 degrees C or less

⁵ : Toner particles were cut to a thickness of about 0.3 μm with a cutter such as a microtome, and photographed with a transmission electron microscope (1000 times). The distribution of the aggregates was observed except for the particles having the largest diameter in the 200 μm × 200 μm field of view, and the dispersibility was evaluated according to the number of particles.

(Excellent): Dispersibility is very good.

(Good): Dispersibility is favorable.

Δ (normal): Dispersibility is normal.

× (poor): The dispersibility is bad.

As shown in Table 2 above, in the case of melt kneading by setting the temperature gradient conditions in the twin screw extruder according to Examples 1 and 2, the low temperature fixability and the resistance compared to Comparative Examples 1 and 2 corresponding to the conventional toner production method A toner excellent in offset properties could be obtained. In particular, in the case of the toner produced by a two-step melt kneading process including a preliminary kneading step using an open roll type kneader (Example 1), it was particularly excellent in terms of low temperature fixability and dispersibility. In particular, as can be seen from the results of Comparative Example 1, it is possible to minimize the disadvantages of the two-stage kneading process, that is, offset generation due to the decrease in binder resin intrinsic properties.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of the present invention will be apparent from the appended claims.

1 is a view schematically showing a twin screw extruder for melt kneading usable in a preferred embodiment of the present invention and a screw structure in the extruder.

Claims (15)

A toner manufacturing method comprising the step of melt kneading a raw material for toner production comprising at least two polyester resins having different softening temperatures as a binder resin in an extruder, When the distance to the extruder tip die is defined as L from the raw material inlet of the extruder, and the softening temperature of the resin having the highest softening temperature among the two or more binder resins is defined as T _m , the tip die from the raw material inlet of the extruder is defined. A temperature gradient condition is maintained in the direction as follows: (i) T _m -50 ° C to T _m -20 ° C in an interval of 0-1 / 10L; (ii) in the 1 / 10L ~ 2 / 10L interval, T _m -30 ℃ ~T _m; (iii) 2 / 10L ~ in the 6 / 10L _{interval, T m -10 ℃ ~T m +} 40 ℃; (iv) T _m −20 ° C. to T _m + 20 ° C. in the range 6 / 10L to 9 / 10L; And (v) T _m -50 ° C. to T _m in the range 9 / 10L to L. 2. The toner according to claim 1, wherein the raw material for toner production comprises 68 to 98 wt% of a binder resin, 1.0 to 30 wt% of a colorant, 0.5 to 10 wt% of a wax, and 0.3 to 5 wt% of a charge control agent. Manufacturing method. The method of claim 2, wherein the melt kneading step comprises a portion of the binder resin; And pre-melt kneading at least a portion of the additive including the colorant, wax and charge control agent into a master batch form, And the master batch is fed into the raw material inlet of the extruder together with the remaining binder resin and the additive to melt kneading. The master batch is prepared using at least one of the two or more polyester resins, and at least two of the additives including the colorant, wax and charge control agent. Method for preparing toner.  5. The method of claim 3 or 4, wherein the additive further comprises one or more selected from the group consisting of an inorganic filler, a fluidity improver, and a charge stabilizer. 3. The method of claim 2, wherein at least some of the additives including the colorant, wax and charge control agent are introduced into the melt kneading step through a plurality of feeders or a plurality of inlets. The method of claim 1, wherein the extruder comprises at least one kneading part in a section of 3 / 10L to 6 / 10L in the direction of the die from the raw material inlet. The toner according to claim 1, wherein the two or more polyester resins have a weight average molecular weight (Mw) of 1,000 to 200,000, a softening temperature of 80 to 190 ° C, and a glass transition temperature of 40 to 80 ° C. Manufacturing method. The method of claim 8, wherein the two or more polyester resins are selected from one or two or more from the polyester resin of the high softening point region and the polyester resin of the low softening point region, respectively, The resin in the high softening point region exhibits a weight average molecular weight (Mw) of 50,000 to 200,000, a softening temperature of 120 to 190 ° C. and a glass transition temperature of 50 to 80 ° C., and the resin of the low softening point region has a weight average of 1,000 to 100,000. A molecular weight (Mw), a softening temperature of 80 to 130 ° C, and a glass transition temperature of 40 to 70 ° C. 10. The method of claim 9, wherein a softening point difference between the resin in the high softening point region and the resin in the low softening point region is 5 to 100 占 폚. The method of claim 9 or 10, wherein the weight ratio of the resin in the high softening point region to the resin in the low softening point region is 0.1 to 9.0. 2. The method of claim 1, further comprising cooling, pulverizing, and classifying the melted kneaded product to produce toner in the form of particles. 13. The method of claim 12, further comprising the step of externally adding one or two or more selected from an inorganic filler, a fluidity improver, and a charge stabilizer to the particle toner. 3. The method of claim 2, wherein the wax comprises a low melting wax having a melting point of 50 to 100 DEG C and a high melting wax having a melting point of 100 to 170 DEG C. The method of claim 2, wherein the binder resin is one or more selected from the group consisting of styrene resin, acrylic resin, styrene-acrylic resin, polyolefin resin, polyamide resin, polyurethane resin, polycarbonate resin, and copolymers thereof. Further comprising at least two additional resins selected, wherein the additional resin is contained in the binder resin at up to 80% by weight.

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