JP2001222137A - Resin composition for color toner, color toner and method of producing resin composition for color toner or color toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for a color toner which maintains a good state of the dispersion property between a styrene-(meth)acrylyate copolymer and a pigment and which shows excellent smoothness of the surface of the fixed toner, transparency and electrification property, and to provide the color toner and a method of producing the resin composition for the color toner and the color toner. SOLUTION: In the resin composition for a color toner essentially comprises a styrene-(meth)acrylate copolymer and a pigment, the melt viscosity ηA of the styrene-(meth)acrylate copolymer (A) at 120 deg.C and the melt viscosity ηB of the styrene-(meth)acrylate copolymer (B) at 120 deg.C satisfy 3×102<=ηA<=3×104 (dyn sec/cm2), 5×102<=ηB<=5×104 (dyn sec/cm2), and ηA<=ηB.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for a color toner used for electrophotography and the like, a color toner, and a method for producing a color toner. The present invention relates to a color toner resin composition, a color toner, and a method for producing a color toner used in a developing method.

[0002]

2. Description of the Related Art In full-color electrophotography, a non-magnetic one-component dry developing system is frequently used as a system for developing an electrostatic charge image. In the non-magnetic one-component dry development system,
Normally, the toner is charged by friction with the sleeve, and this is attached to the electrostatic latent image on the photoconductor by electric attraction,
Next, the image is transferred onto a copy sheet and fixed by a hot roll or the like to form a permanent visible image.

However, in the above-described full-color electrophotography, various characteristics which have not been required in the conventional black-and-white monochrome toner have been required. First, it must be ensured that the fixed toner does not diffusely reflect light and impair color reproducibility. In the case of a monochrome toner, a resin may be used after crosslinking, or a large amount of a high molecular weight substance may be used. However, in the case of a color toner, irregular reflection occurs due to irregularities formed on a fixing surface. However, the desired film strength cannot be obtained without cross-linking or the use of a high molecular weight substance, so that the toner is destroyed and the charging performance is reduced.

[0004] Further, since full-color toner produces an intermediate color by superimposing toners of different colors, transparency is required. However, if a large amount of wax is added to prevent offset, the transparency of the toner is impaired, and it becomes difficult to use the toner as a full-color toner. Further, if the dispersibility with the pigment is poor, the transparency is deteriorated, and problems such as poor charging occur.

In general, when a pigment is melt-kneaded with a thermoplastic resin, a so-called master batch in which the pigment is melt-kneaded at a high concentration with the thermoplastic resin is prepared, and this is diluted with a new thermoplastic resin to disperse the pigment. A masterbatch-type melt-kneading method for improving the properties is used.
In the production of toner, for example, Japanese Patent Application Laid-Open
JP-A-69-70, JP-A-6-130724, JP-A-9-288376-9, etc., when producing a toner, prepare a pigment master batch of a binder resin composed of a polyester resin and prepare a new polyester resin. A masterbatch method of diluting with a binder resin is disclosed.

However, irrespective of the poor compatibility between the styrene- (meth) acrylate-based copolymer and the pigment, despite the excellent resin film strength of the styrene- (meth) acrylate-based copolymer, However, a resin composition for color toner and a color toner having the above constitution and excellent dispersibility have not been developed.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been developed in view of the fact that the dispersibility of a styrene- (meth) acrylate-based copolymer and a pigment is well maintained, An object of the present invention is to provide a resin composition for a color toner, a color toner, and a method for producing a resin composition or a color toner for a color toner, which are excellent in surface smoothness, transparency, and chargeability.

[0008]

According to the first aspect of the present invention, there is provided a color toner resin composition or a color toner comprising a styrene- (meth) acrylate copolymer and a pigment as main components. In the composition, one of the styrene- (meth) acrylate-based copolymer (A)
When the melt viscosity at 20 ° C. is η _A and the melt viscosity of the styrene- (meth) acrylate copolymer (B) at 120 ° C. is η _B , 3 × 10 ² ≦ η _A ≦ 3 × 1.
^{0 4 (μN · sec / cm} 2), 5 × 10 2 ≦ η B ≦ 5
× 10 ⁴ (μN · sec / cm ² ) and η _A
≦ η _B.

The resin composition for a color toner or the color toner according to the second aspect of the present invention is a color toner in which a styrene- (meth) acrylate copolymer and a pigment form a sea-island structure. The area occupied by the pigment particles forming the islands in an arbitrary 5 μm × 5 μm range of the color toner observed with a microscope is 3 μm ² or less.

[0010] The color toner according to the third aspect of the invention uses the resin composition for a color toner according to the first or second aspect.

The method for producing a resin composition for a color toner or the method for producing a color toner according to the invention of claim 4 is a method for producing a resin composition for a color toner according to claim 1 or 2 or the method for producing a color toner according to claim 3. Wherein a styrene- (meth) acrylate copolymer (A) having a low melt viscosity and a pigment (C) are melt-kneaded and pulverized to obtain a first melt-kneading step and a first melt-kneading step. A second melt-kneading step of melt-kneading the obtained granules and a styrene- (meth) acrylate copolymer (B) having a high melt viscosity, and pulverizing the granules, and a granule obtained in the second melt-kneading step Is classified.

The styrene component of the styrene- (meth) acrylate copolymer used in the present invention includes:
Not limited to only styrene, for example, o-
Methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-ethyl styrene, 2,
4-dimethylstyrene, pn-butylstyrene, p-
t-butylstyrene, pn-hexylstyrene, p-
n-octyl styrene, pn-dodecyl styrene, p
And styrene monomers such as -methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene.

The above (meth) acrylic ester component is not particularly limited. Examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate,
Alkyl acrylates such as n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylic acid Alkyl methacrylates such as n-butyl, isobutyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, stearyl methacrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate , Phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, bisglycidyl methacrylate , Polyethylene glycol dimethacrylate, methacryloxyethyl phosphate, and the like. Among them, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate and the like are preferably used.

The styrene component and the (meth) acrylate component of the styrene- (meth) acrylate-based copolymer may include, for example, acrylic acid, methacrylic acid, α-ethylacrylic acid, Acrylic acid such as crotonic acid and its α- or β-alkyl derivative, fumaric acid, maleic acid, citraconic acid, unsaturated dicarboxylic acid such as itaconic acid and its monoester or diester derivatives, monoacryloyloxyethyl succinate, Other vinyl monomer components such as succinic acid monomethacryloyloxyethyl ester, acrylonitrile, methacrylonitrile, and acrylamide may be added.

The means for preparing the styrene- (meth) acrylate copolymers (A) and (B) is not particularly limited, and may be, for example, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. And a bulk polymerization method.

The melt viscosity η _A of the styrene- (meth) acrylate copolymer (A) is 3 × 10 ² μN
If it is less than sec / cm ² , the compatibility with the styrene- (meth) acrylate-based copolymer (B) is reduced, and the styrene- (meth) acrylate-based copolymer is melt-kneaded. If the re-dispersion of the pigment in (A) is inhibited and it exceeds 3 × 10 ⁴ μN · sec / cm ² , the dispersibility of the pigment of the styrene- (meth) acrylate-based copolymer (A) itself is reduced. Since it decreases, it is limited to the above range.

The melt viscosity η _B of the styrene- (meth) acrylate copolymer (B) is 5 × 10 ² μN
If it is less than sec / cm ² , the storage stability of the obtained resin composition for color toner or color toner decreases, and the strength of the coating film decreases, resulting in 5 × 10 ⁴ μN · sec / cm.
^If it exceeds ² , the fixability and the transparency of the color toner are reduced, so that the content is limited to the above range.

The styrene- (meth) acrylate copolymers (A) and (B) each have a melt viscosity η _A and η _B of 5 × 10 ^{2 to} 3 × 10 ⁴ (μN · s).
ec / cm ² ), η _A = η _B may be satisfied.

The pigment used in the present invention is not particularly limited, and includes, for example, known azo pigments, phthalocyanine pigments, lake pigments, carbon black, aniline black, and lamp black used in color toners. And quinoline yellow, rhodamine B, quinacridone and the like.

If the content of the pigment is too small, desired coloring cannot be obtained, and if the content is too large, not only the dispersibility of the pigment is lowered but also the transparency is deteriorated.
It is 1 to 10% by weight based on the total amount of the (meth) acrylate copolymers (A) and (B).

The resin composition for color toner or the color toner of the present invention may contain a charge controlling agent, a release agent,
Other additives may be included. The charge control agent is not particularly limited, for example, nigrosine dye, ammonium salt, pyridinium salt, positive charge control agent such as azine, chromium complex, charge control agent for negative charge such as iron complex and the like Is mentioned.

The release agent is not particularly restricted but includes, for example, olefin polymers such as polyethylene and polypropylene, natural hydrocarbon compounds such as paraffin wax, and synthetic hydrocarbon compounds such as Fischer-Tropsch wax. Hydrocarbon crystalline polymers are exemplified.

In the resin composition for color toner or color toner of the present invention, the styrene- (meth) acrylate copolymers (A) and (B) and the pigment (C) form a sea-island structure, It is preferable that the area occupied by the pigment (C) particles constituting the island in an arbitrary area of 5 μm × 5 μm of the color toner observed by a transmission electron microscope is 3 μm ² or less.

The method for producing the resin composition for color toner or the color toner of the present invention is not particularly limited. For example, a styrene- (meth) acrylate copolymer (A) having a low melt viscosity is used. Melt-kneading and pulverizing the pigment and the pigment (C), and a styrene- (meth) acrylate-based copolymer (B) having a high melt viscosity with the granular material obtained in the first melt-kneading step. ) Is preferably provided with a second melt-kneading step of melt-kneading and pulverizing, and a step of classifying the granular material obtained in the second melt-kneading step.

In the above method for producing a resin composition for a color toner or a color toner, if the blending amount of the pigment (C) in the first melt-kneading step is too large, the dispersibility of the pigment (C) is reduced and bleeding occurs. Therefore, the amount is preferably 80 parts by weight or less based on 100 parts by weight of the styrene- (meth) acrylate copolymer (A).

If the amount of the granular material obtained in the first melt-kneading step in the second melt-kneading step is too large, it adversely affects the performance such as fixability and offset property of the binder resin as a color toner. Styrene- (meth)
It is preferably 40 parts by weight or less based on 100 parts by weight of the acrylate copolymer (B).

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Preparation of Styrene- (meth) acrylic acid ester-based copolymer] 400 g of toluene was placed in a 3-liter separable flask, and the gas phase was replaced with nitrogen gas. The mixture was heated under reflux cooling, and a mixture of 800 g of styrene, 200 g of n-butyl acrylate, and a toluene solution of 1 g of AIBN as a polymerization initiator was stirred while stirring at the time when the reflux of toluene occurred.
The solution polymerization was performed while dropping over time. After completion of the dropwise addition, heating was continued for 1 hour while stirring at the boiling point of toluene under reflux cooling, and then the solvent was removed under reduced pressure while gradually increasing the temperature of the system, followed by cooling and pulverization to obtain granular styrene.
A (meth) acrylate copolymer (hereinafter simply referred to as a resin) was prepared. Further, Resins (1) and (2) were prepared in the same manner as in the above preparation method, using the charged amounts shown in Table 1.

The melt viscosity of the obtained resin at 120 ° C. was measured by the following method. The measurement results are shown in Table 1.

[Method of Measuring Melt Viscosity] Using a viscoelasticity measuring device (“RAD-700” manufactured by Rheometrics),
A sample piece having a diameter of 20 mm and a thickness of 2 mm was prepared.
mm parallel plate, angular velocity 100 rad / se
c, The melt viscosity at 120 ° C. was measured under the conditions of a temperature rising rate of 3 ° C./min and a strain of 5%.

[0031]

[Table 1]

Example 1 100 parts by weight of a resin and 20 parts by weight of a copper phthalocyanine pigment were melt-kneaded in a kneader so that the resin temperature was heated to a range of 100 to 110 ° C., and the obtained kneaded product was pulverized. It was made into a granular body using a machine (first melt-kneading step). Next, 35 parts by weight of the granular material obtained in the first melt-kneading step was added to 100 parts by weight of the resin, and the mixture was melt-kneaded by heating in a kneader so that the resin temperature was in the range of 100 to 110 ° C. The kneaded product was roughly pulverized using a pulverizer, and further finely pulverized with a jet mill to obtain a resin composition for color toner (second melt-kneading step).

The granular material obtained in the second melt-kneading step was subjected to a classifier to obtain a fine powder having a 50% average particle size of about 9 μm.
To the above fine powder, 2% by weight of silica fine powder ("Aerosil R972D" manufactured by Nippon Aerosil Co., Ltd.) as a charge control agent and 5% by weight of Fischer-Tropsch wax as a release agent are externally added and mixed by stirring to prepare a color toner. did.

(Example 2, Comparative Examples 1 and 2) Color toners were prepared in the same manner as in Example 1 with the compounding amounts shown in Table 2.

[0035]

[Table 2]

(Comparative Example 3) The total amount of the resin and the resin of the color toner of Example 1 and the compounding ratio of the pigment were changed to 100 parts by weight of the resin of the present example without dividing the melt-kneading step into two stages. Then, the mixture was melt-kneaded all at once in a single melt-kneading step, and the subsequent steps were the same as in Example 1 to produce a color toner.

In order to evaluate the performance of the resin compositions for color toners obtained in Examples 1 and 2 and Comparative Examples 1 to 3 and the color toner using the same, the dispersibility of the pigment and the smoothness of the fixing surface (gloss) were evaluated. Degree), transparency and chargeability were tested by the following methods. The test results are shown in Table 3.

[Pigment Dispersibility] The resin composition mass obtained in the second melt-kneading step is dyed, and then, is subjected to a microtome to a thickness of about 0.1 μm.
A sample of a 5 μm thin film piece was prepared, and the sea-island structure formed by the styrene- (meth) acrylate copolymers (A) and (B) and the pigment (C) was observed with a transmission electron microscope. The maximum dispersed particle area (n _max ) of the pigment as one island component in the range of 5 μm was measured.

[Smoothness of Fixing Surface] The smoothness of the fixing surface of the color toner was measured using a gloss meter ("Gross Guard", manufactured by Gardner Co., USA, incident angle: 60 degrees). Evaluation was based on criteria. ◎: extremely good (gloss 5
0 or more), ：: good (gross 30 or more and less than 50) X: bad (less than 30)

[Transparency] The color tone of the halftone (intermediate color) portion after fixing the color toner was visually observed and evaluated according to the following criteria. ◎: extremely good (halftone is reproduced beautifully), ：: good (halftone is slightly dull and disturbed, but within an acceptable range) ×: bad (halftone is slightly dull, Disturbances that exceed the permissible limit)

[Charging Property] A running test of 10,000 sheets was performed in a copying room at a temperature of 30 ° C. and a humidity of 50%.
Ten samples were withdrawn every 00 sheets, and the stability of the charge amount of the color toner was visually observed and evaluated according to the following criteria. ◎: extremely good (no change in the image is recognized), ：: good (image is slightly disturbed, but within an allowable range) ×: poor (a change is clearly recognized in the image characteristics, and the allowable limit) Which goes beyond)

[0042]

[Table 3]

[0043]

Since the resin composition for color toner or the color toner according to the first aspect of the present invention is constituted as described above, the dispersibility of the pigment in the color toner is improved and the fixing is firm. It has a smooth fixing surface and excellent transparency, faithfully reproduces beautiful full-color prints, and changes the image characteristics of the copied image even after long-time continuous copying. It is an excellent thing that is not messy.

Since the resin composition for a color toner or the color toner according to the second aspect of the present invention is constituted as described above, it has the excellent characteristics described in the preceding item and can exhibit various effects. is there.

The method for producing a resin composition for a color toner or the method for producing a color toner according to the third aspect of the present invention is configured as described above, and thus has the excellent characteristics described in the preceding paragraph and exhibits excellent effects. The obtained resin composition for color toner or color toner can be produced.

Claims (4)

[Claims] 1. A color toner resin composition comprising a styrene- (meth) acrylate-based copolymer and a pigment as main components, the styrene- (meth) acrylate-based copolymer (A) having a temperature of 120 ° C. Is the melt viscosity at η _A and the melt viscosity at 120 ° C. of the styrene- (meth) acrylate copolymer (B) at η _B is 3 × 10 ² ≦ η _A ≦ 3 × 10 ⁴ (μN · sec / c
m ² ), 5 × 10 ² ≦ η _B ≦ 5 × 10 ⁴ (μN · sec
/ Cm ² ), and η _A ≦ η _B. 2. A color toner in which a styrene- (meth) acrylate-based copolymer and a pigment form an islands-in-the-sea structure, wherein the color toner observed in a 5 μm × 5 μm range of the color toner observed with a transmission electron microscope. A resin composition for a color toner, wherein an area occupied by a pigment particle group constituting an island is 3 μm ² or less. 3. A color toner comprising the resin composition for a color toner according to claim 1 or 2. 4. The method for producing a resin composition for a color toner according to claim 1 or 2 or the method for producing a color toner according to claim 3, wherein the styrene- (meth) acrylate copolymer having a low melt viscosity is used. A) melt-kneading and pigment (C) a first melt-kneading step, and a styrene- (meth) acrylate-based copolymer having a high melt viscosity and a granular material obtained in the first melt-kneading step (B) is melt-kneaded and pulverized, and a step of classifying the granular material obtained in the second melt-kneading step is characterized by comprising a step of: Production method.