JP2002278152A - Color toner for electrostatic image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing method which is excellent in image gloss, full-color image color reproducibility, durability, soft PVC product stain resistance and productivity, and which does not apply a release oil to a fixing member or a very small amount is applied. To provide a full-color toner for developing an electrostatic image having sufficient offset resistance. SOLUTION: In a color toner for electrostatic image development containing at least a binder resin, a colorant and a release agent, the binder resin is mainly composed of a styrene monomer and a methyl acrylate monomer. As a main component, the binder resin in the toner contains substantially no tetrahydrofuran-insoluble matter, the weight average molecular weight by GPC is 12,000 to 50,000, and
A color toner for developing an electrostatic image, wherein the release agent is present as a rod-shaped domain in the toner, and the average thickness of the rod-shaped domain is 0.05 to 0.80 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

2. Description of the Related Art In electrophotographic image formation, an electrostatic latent image is formed on an image carrier such as a photoconductive substance, and charged toner particles adhere to the electrostatic latent image to form a visible image. After forming an image, it is transferred to a recording medium such as paper, and then fixed.
Output image. In recent years, the technology of copiers and printers using electrophotography has been rapidly expanding from monochrome to full color, and the market for full color has been expanding. Color image formation by full-color electrophotography generally involves three primary colors, yellow, magenta, and cyan.
All colors are reproduced by stacking color toners of four colors or four color toners in which black is added thereto. Therefore, in order to obtain a clear full-color image with excellent color reproducibility, it is necessary to smooth the surface of the fixed toner image to some extent, or to reduce light scattering on the surface or inside of the toner by eliminating voids between toners. is there. For this reason, the image gloss of a conventional full-color copying machine or the like is 10 to 50.
% Of medium to high gloss, and a sharp melt toner having low viscoelasticity when melted is used.

In general, as a method of fixing a dry toner image on a recording medium, a contact heat fixing method of heating a fixing member such as a roller or a belt having a smooth surface and pressing the fixing member against the toner is often used. This method has high heat efficiency, is capable of high-speed fixing, and has the advantage that the surface of the fixed toner image is easily smoothed, but on the other hand, it peels off after the heated fixing member surface and the toner in the molten state are brought into contact under pressure. For this reason, there is a disadvantage that the so-called offset phenomenon occurs, in which the melted toner is internally broken and a part of the toner image adheres to the surface of the fixing member and is transferred to another image.

In order to prevent this offset phenomenon, a method of forming the surface of a fixing member with silicone rubber or fluororesin having excellent releasability, and further applying a release oil such as silicone oil to the surface of the fixing member. Was generally adopted. Although this method is extremely effective in preventing toner offset, it requires a device for supplying a release oil, and the fixing device becomes large in size and cost increases. Furthermore, since the release oil adheres to the recording agent such as paper at the time of fixing, there is a problem that the writing property with the aqueous ink is significantly reduced. For this reason, in the monochrome toner, the viscoelasticity of the toner at the time of melting is increased by adjusting the molecular weight distribution of the binder resin or the like so that the melted toner does not break inside.
Further, by incorporating a release agent such as wax into the toner, a fixing method without applying a release oil to the fixing member tends to be adopted. However, as described above, color toner improves color reproducibility, so it is easy to offset because the melt viscoelasticity is low due to sharp melt and the toner is easily broken inside, and it is more difficult to make the fixing device oilless and apply a small amount. Become.

Also, when a release agent such as wax is contained in the toner, light scattering occurs at the interface between the binder resin and the release agent, and OH
There is a problem that the color reproducibility at P is reduced, and an excessive release agent cannot be contained.

[0006] Under such circumstances, an image having an appropriate gloss and excellent color reproducibility can be obtained, and a fixing method in which a releasing oil is not applied to a fixing member or a very small amount of oil is applied is sufficient. There is a long-felt need for a color toner having an anti-offset property, and many technical proposals have been made. For example, in the case of a polyester resin as a proposal from a binder resin, in Japanese Patent No. 2675948, the weight average molecular weight of specific divalent and trivalent acid components and a specific alcohol component is 13000 to 20,000, and the number average molecular weight is Is 5,000 to 8,000, and the weight average molecular weight (M
w) and the number average molecular weight (Mn) ratio Mw / Mn is 2-3.
5, the toner containing the non-linear polyester resin,
Japanese Patent No. 2981831 discloses a toner containing a linear polyester resin having a softening point of 90 to 120 ° C. and a non-linear polyester resin.
No. 61460 discloses a toner containing a polyester having a number average molecular weight of 2,500 to 3,500, a weight average molecular weight of 50,000 to 300,000, and containing no polyester insoluble in tetrahydrofuran (THF).
3903 shows a toner containing a non-linear polyester containing no THF-insoluble matter, and JP-A-8-101530 and JP-A-8-166688 disclose a 10% by weight THF-insoluble matter.
Toners containing the following polyester resins have been proposed.

Also, there have been many proposals to improve the offset property of a copolymer resin of a styrene monomer and a (meth) acrylate monomer as a color toner. For example, JP-A-6-175395 and JP-A-9-175
281747, JP-A-10-123752, JP-A-10-1275
171162, JP-A-11-24307, JP-A-11-11
-24309, JP-A-11-184149, Patent No. 27
49843 and the like. Although any of the toners showed some improvement in the anti-offset properties, the improvement from these binder resins alone provided adequate image gloss, excellent color reproducibility of the fixed image, and applied release oil to the fixing member. do not do,
Alternatively, it is difficult to simultaneously satisfy sufficient anti-offset properties in a fixing method in which the amount of oil applied is extremely small, and it is necessary to include a release agent in the toner. When a releasing agent is contained in the toner, the anti-offset property is obviously improved, but a problem such as a decrease in fluidity and durability of the toner occurs.

[0008] In order to solve this problem, there is a proposal to control the dispersion state of the release agent in the toner. For example, in Japanese Patent No. 2856494, the domain volume of the wax is 5-2.
A toner obtained by pulverizing a kneaded material of 0 μm ³ is disclosed in Japanese Patent No. 2891.
305, a toner in which the domain diameter B of the release agent is 0.03 <B / A <0.15 with respect to the polymer particles A is disclosed in
With -84398, the release agent domain diameter is 0.1 to 1.0 μm.
m has a particle size of 2 in JP-A-8-328293.
A toner in which wax particles having a particle size of 1 μm or less are 75% or more and wax particles having a particle size of 1 μm or less are disclosed in
In Japanese Patent No. 211889, a toner having a release agent domain having a particle diameter of 0.1 μm or more having an average particle diameter of 0.2 to 0.5 μm is disclosed. Less than 12% by number of wax particles less than 5% and less than 30% by number of wax particles having a size of 1 μm or more and less than 2 μm
95% toner is disclosed in Japanese Patent Application Laid-Open No. H11-174730.
Has proposed a toner containing a low molecular weight polypropylene wax having a dispersion diameter of 0.3 μm or less.

However, there is a strong demand in the market for higher image quality and higher reliability, and there is a strong demand for toners that can provide images with excellent color reproducibility and that simultaneously achieve high anti-offset properties and excellent durability. Have been. Further, toners have been reduced in particle size due to a demand for higher image quality. However, since the energy and time required for pulverization increase, a toner having excellent pulverizability is required. A copolymer resin of a styrene monomer and a (meth) acrylate monomer is generally superior in pulverizability as compared with a polyester resin, but is disadvantageous in that it easily contaminates a soft PVC product. There have been proposals to introduce various polar groups to improve the soft PVC product contamination (plasticizer resistance), but all have the problem that the chargeability under high humidity conditions is reduced.

[0010]

DISCLOSURE OF THE INVENTION The present invention has a moderate image gloss, is excellent in color reproducibility of a full-color image, and does not apply a release oil to a fixing member, or uses a very small amount of oil. It is an object of the present invention to provide a full-color toner for electrostatic image development that simultaneously satisfies sufficient anti-offset properties in a fixing method, and that also has excellent durability and productivity (pulverizability of toner) and excellent resistance to contamination of flexible PVC products. Aim.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above-mentioned problems have been solved by using a binder resin having specific characteristics and controlling the dispersion shape of the release agent in the toner. Have been achieved, and the present invention has been completed. That is, according to the present invention, the following color toner for electrostatic charge development is provided. (1) In a color toner for developing an electrostatic image containing at least a binder resin, a colorant and a release agent, the binder resin contains a styrene monomer and a methyl acrylate monomer as main constituent units. Containing a vinyl copolymer as a main component, and the binder resin in the toner substantially contains THF.
Contains no insolubles and has a weight average molecular weight of 12
000 to 50,000, wherein the release agent is present as a rod-shaped domain in the toner, and the average thickness of the rod-shaped domain is 0.05 μm to 0.80 μm. . (2) The solubility parameter (SP value) of the release agent is 8.
(8) The color toner for developing an electrostatic image according to the above (1), wherein the color toner is 8 to 9.2. (3) The molar ratio of the styrene monomer to the acrylate methyl ester monomer (styrene monomer: acrylate methyl ester monomer) in the binder resin is 50:50 or more.
The color toner for developing electrostatic images according to (1) or (2), wherein the ratio is 60:40. (4) Further, as external additives, at least (a) hydrophobically treated silica having a primary particle size of 0.01 to 0.03 μm, and (b) specific surface area of 20 to 50 m ² / g, bulk density of 100 to
The color toner for developing an electrostatic image according to any one of (1) to (3), wherein 250 g / l of silica subjected to hydrophobic treatment is added.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The reason that the toner containing the release agent exerts the release property at the time of fixing is that the heated release liquid is present between the fixing member such as a roller and the toner and acts similarly to the release oil. That's why. If the release agent domain is large, it is easily crushed inside the release agent or at the interface with the binder resin during pulverization, and the amount of the release agent exposed on the toner surface increases, so that the releasability increases, while the release agent domain increases. Is small, the amount of the release agent exposed on the toner surface decreases, and the releasability decreases. Then, a problem due to the release agent, that is, a decrease in fluidity, a decrease in durability due to a decrease in chargeability due to contamination of the carrier in the two-component system or the frictional charging member in the one-component system,
Since filming of the release agent onto the photoreceptor increases with the improvement of the releasability, there is an appropriate region in which the domain diameter of the release agent balances these. This means that the release agent inside the toner is hard to exude to the surface at the time of fixing, and the control of the domain diameter of the release agent controls the amount of the release agent exposed on the toner surface.

The first feature of the toner of the present invention is that the release agent exists as a rod-like domain in the toner. By making the release agent into a rod shape, the release agent inside the toner becomes easy to exude at the time of fixing, and the effect that the release property is exhibited relative to the release amount of the release agent on the toner surface is obtained. A toner structure that can improve the relationship between the defect point and the trade-off of releasability can be obtained.

A second feature of the toner of the present invention is that a resin mainly composed of a vinyl copolymer containing a styrene-based monomer and an acrylic acid methyl ester monomer as main constituent units as a fixing resin of the toner. Is used. The toner of the present invention is mainly composed of a vinyl-based copolymer containing a styrene-based monomer and a methyl acrylate monomer as main constituent units as a binder resin. This is to prevent the contamination of flexible PVC products from being easily obtained. The polyester resin has a solubility parameter that is clearly higher than the solubility parameter of the plasticizer contained in the soft PVC product, and is excellent in stain resistance to the soft PVC product. It is difficult to obtain drug domains. In particular, this tendency is remarkable because the color toner has low viscoelasticity at the time of melting and a low shearing force during kneading.

On the other hand, in a copolymer resin of a styrene monomer and a (meth) acrylate monomer, the release agent tends to be finely dispersed, but tends to contaminate a soft PVC product. The present inventors studied a copolymer resin of the styrene monomer and a (meth) acrylate monomer, and found that
A vinyl copolymer containing a styrene monomer and an acrylic acid methyl ester monomer as main constituent units was obtained only in a good release agent dispersion state and did not contaminate the flexible PVC product, Furthermore, they have found that this copolymer also has a feature of being excellent in pulverizability.

The styrene monomer referred to in the present invention includes styrene, methyl styrene, ethyl styrene, butyl styrene, hexyl styrene, octyl styrene and the like. Styrene is particularly preferred as the styrene monomer, and the molar ratio of the styrene monomer to the methyl acrylate monomer (styrene monomer: methyl acrylate monomer) is 50: 50-60. : 40 ensures that the soft PVC contamination prevention property is assured.

When the styrene monomer and the acrylate methyl ester monomer are copolymerized, other (meth) acrylic ester monomers or vinyl monomers may be used as long as the effects of the present invention are not impaired. A monomer and a crosslinking agent may be copolymerized. Specifically, methyl methacrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate,
Dodecyl (meth) acrylate, 2- (meth) acrylate
Ethylhexyl, lauryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-chloroethyl (meth) acrylate, (meth) acrylonitrile, (meth) acrylamide, (meth) acryl Acid, vinyl methyl ether,
Vinyl ethyl ether, vinyl isobutyl ether, N
Monomers such as vinylpyrrolidone, N-vinylpyridine and butadiene, and compounds having two or more polymerizable double bonds such as divinylbenzene, divinylnaphthalene and trimethylolpropane triacrylate as crosslinking agents.

As the method for synthesizing the vinyl copolymer of the binder resin used in the present invention, conventionally known methods such as solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization and dispersion polymerization can be used.

Further, as long as the effects of the present invention are not impaired, polyester resins, polyol resins, polyurethane resins, polyamide resins, epoxy resins, rosins, modified rosins, terpene resins, phenol resins, hydrogenated petroleum resins, etc. may be mixed. It does not matter.

In the present invention, the binder resin containing, as a main component, a vinyl copolymer containing a styrene-based monomer and an acrylic acid methyl ester monomer as main constituent units has a substantially THF-insoluble content. Not containing, and having a weight average molecular weight of 12,000 to 50,000 by GPC.
The binder resin in the toner does not substantially contain a THF-insoluble component, and the weight average molecular weight by GPC is 50,000 or less, so that a full-color image having appropriate gloss and excellent color reproducibility can be obtained. Can be. However,
If the weight average molecular weight is less than 12,000, the anti-offset properties will be insufficient.

In the measurement of the molecular weight by GPC in the present invention, the column is stabilized in a heat chamber at 40 ° C.
The column at this temperature was charged with THF as a solvent at 1 / min.
and a THF sample solution of the resin prepared at a sample concentration of 0.05 to 0.6% by weight.
Inject and measure. When measuring the molecular weight of a sample,
The molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, PressureChemica
lCo. Or Toyo Soda Kogyo's molecular weight is 6 × 10
² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ ,
5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10 ⁵ ,
It is suitable to use 8.6 × 10 ⁵ , 2 × 10 ⁶ , and 4.48 × 10 ⁶ , and to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

As the release agent used in the color toner of the present invention, conventionally known release agents can be used. For example, low molecular weight polyolefin wax such as low molecular weight polyethylene and low molecular weight polypropylene, synthetic hydrocarbon wax such as Fischer-Tropsch wax, natural wax such as beeswax, carnauba wax, candelilla wax, rice wax, montan wax, etc. , Paraffin wax, petroleum waxes such as microcrystalline wax, stearic acid, palmitic acid, higher fatty acids such as myristic acid, metal salts of higher fatty acids, higher fatty acid amides, synthetic ester waxes, and various modified waxes thereof Is mentioned. These can be used in combination of two or more.

Among these release agents, particularly, the melting point is 70 to 1
It is preferable to use one in the range of 25 ° C. Melting point 7
By setting the temperature to 0 ° C. or higher, a toner having excellent transferability and durability can be obtained. By setting the melting point to 125 ° C. or lower, the toner is quickly melted at the time of fixing, and a reliable releasing effect can be exhibited.

The release agent in the color toner of the present invention is present in the toner as rod-shaped domains having an average thickness of 0.05 to 0.80 μm. In order for the release agent in the toner to be in such a state, it is important to control the affinity between the binder resin and the release agent and to optimize kneading / cooling conditions. If the affinity between the binder resin and the release agent is low, kneading under high shear conditions and high-pressure rolling / quenching are required.However, it is necessary to increase the affinity while the binder resin and the release agent are incompatible. Thus, the desired release agent dispersion state can be easily and stably obtained.

As a specific index, when the solubility parameter (SP value) of the release agent is set to 8.8 to 9.2, the binder resin and the release agent are incompatible with each other while being immiscible. A desired release agent dispersion state can be obtained easily and stably by giving an affinity. Solubility parameter (SP value) of 8.8
-9.2 release agents include heated xylene, toluene,
It dissolves in any of benzene and does not precipitate even after cooling to 25 ° C. For example, carnauba wax, candelilla wax, rice wax, synthetic ester wax and the like can be mentioned.

The use amount of these release agents is preferably 2 to 15% by weight based on the toner. If it is less than 2% by weight, the effect of preventing offset is insufficient, and if it exceeds 15% by weight, the light transmittance is reduced, and the color reproducibility is poor.

The confirmation of the shape of the release agent and the calculation of the average thickness in the present invention were carried out by the following methods. First, the binder resin in the toner is dissolved, but the wax is not dissolved. The resin is dissolved in an organic solvent such as THF, and the shape is confirmed from an electron micrograph of the wax particles separated by a centrifugal separator. I asked.

As the colorant used in the color toner of the present invention, known pigments and dyes capable of obtaining toners of yellow, magenta, cyan, and black can be used. For example, as a yellow pigment, cadmium yellow, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hanza yellow G, Hanza yellow 10G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, tartrazine lake No. Also,
Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK. Red pigments include red, red, cadmium red, permanent red 4R, lithol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake,
Brilliant Carmine 3B is mentioned. Examples of purple pigments include Fast Violet B and Methyl Violet Lake.

Examples of the blue pigment include cobalt blue, alkali blue, Victoria Blue Lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, and indanthrene blue BC. As a green pigment,
Chrome green, chromium oxide, pigment green B,
Malachite green lake and the like. Examples of the black pigment include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides.
These can be used alone or in combination of two or more.

The color toner of the present invention can contain a charge control agent in the toner, if necessary. For example, nigrosine, an azine dye containing an alkyl group having 2 to 16 carbon atoms (Japanese Patent Publication No. 42-1627), a basic dye (for example, CI Basic Yellow 2 (C.I.
1000), C.I. I. Basic Yellow 3,
C. I. Basic Red 1 (CI. 4516)
0), C.I. I. Basic Red 9 (CI. 425)
00), C.I. I. Basic Violet 1 (C.I.
I. 42535), C.I. I. Basic Violet
3 (CI. 42555), C.I. I. Basic V
iolet 10 (CI. 45170), C.I. I. B
asic Violet 14 (CI. 4251)
0), C.I. I. Basic Blue 1 (CI.4
2025), C.I. I. Basic Blue 3 (C.I.
I. 51005), C.I. I. Basic Blue 5
(C.I. 42140), C.I. I. Basic Blu
e7 (CI. 42595), C.I. I. Basic
Blue 9 (CI. 52015), C.I. I. Bas
ic Blue 24 (CI. 52030), C.I.
I. Basic Blue 25 (CI.5202)
5), C.I. I. Basic Blue 26 (C.I.
44045), C.I. I. Basic Green 1
(C.I. 42040), C.I. I. Basic Gre
lake pigments of these basic dyes, such as C.en 4 (CI.42000); I. Solvent Blac
k8 (C.I. 26150), quaternary ammonium salts such as benzoylmethylhexadecyl ammonium chloride and decyltrimethyl chloride, or dialkyltin compounds such as dibutyl or dioctyl, dialkyltin borate compounds, guanidine derivatives, and amino groups Polyamine resins such as vinyl polymers and amino group-containing condensation polymers, JP-B-41-20153, JP-B-43-27596, and JP-B-44-63.
No. 97, JP-B-45-26478, metal complex salts of monoazo dyes described in JP-B-55-4275.
No. 2, JP-B-59-7385, metal complexes of salicylic acid, dialkylsalicylic acid, naphthoic acid and dicarboxylic acid, such as Zn, Al, Co, Cr and Fe, and sulfonated copper phthalocyanine pigments , Organic boron salts, fluorine-containing quaternary ammonium salts, calixarene-based compounds, and the like. For color toners other than black, the use of a charge control agent that impairs the intended color should of course be avoided, and a white salicylic acid derivative metal salt or the like is preferably used.

In the color toner of the present invention, it is preferred to externally add hydrophobic metal oxide fine particles such as silica, titanium oxide, and alumina to the toner base as a fluidity improver. A lubricant such as an aliphatic metal salt or polyvinylidene fluoride fine particles can also be used in combination. In particular, at least (a) the primary particle diameter of 0.01
(B) specific surface area of 20 to 50 m ² / g, bulk density of 100 to 250 g /
By using the hydrophobically treated silica in combination with 1, the toner can be excellent not only in the fluidity of the toner but also in charge rising property, developability, transferability and durability.

The following are typical examples of the hydrophobizing agent used here. Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane,
Chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, p-chlorophenyltrichlorosilane,
3-chloropropyltrichlorosilane, 3-chloropropyltrimethoxysilane, vinyltriethoxysilane,
Vinylmethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinyldichlorosilane, dimethylvinylchlorosilane, octyl-trichlorosilane, decyl-trichlorosilane,
Nonyl-trichlorosilane, (4-t-propylphenyl) -trichlorosilane, (4-t-butylphenyl)
-Trichlorosilane, dibentyl-dichlorosilane, dihexyl-dichlorosilane, dioctyl-dichlorosilane, dinonyl-dichlorosilane, didecyl-dichlorosilane, didodecyl-dichlorosilane, dihexadecyl-
Dichlorosilane, (4-t-butylphenyl) -octyl-dichlorosilane, dioctyl-dichlorosilane, didecenyl-dichlorosilane, dinonenyl-dichlorosilane, di-2-ethylhexyl-dichlorosilane, di-
3,3-dimethylpentyl-dichlorosilane, trihexyl-chlorosilane, trioctyl-chlorosilane, tridecyl-chlorosilane, dioctyl-methyl-chlorosilane, octyl-dimethyl-chlorosilane, (4-t
-Propylphenyl) -diethyl-chlorosilane, octyltrimethoxysilane, hexamethyldisilazane, hexaethyldisilazane, diethyltetramethyldisilazane, hexaphenyldisilazane, hexatolyldisilazane and the like. In addition, titanate-based coupling agents and aluminum-based coupling agents can also be used.

The color toner of the present invention can be used for both one-component development and two-component development. When the toner is used for a two-component developer, it is used by mixing with a carrier powder. As the carrier in this case, all known carriers can be used, and examples thereof include iron powder, ferrite powder, magnetite powder, nickel powder, glass beads, and the like, and those whose surfaces are coated with a resin or the like.

As a method for producing the color toner of the present invention, a conventionally known method can be applied. As a device for kneading the toner, a continuous twin roll from a batch twin roll or a continuous twin screw extruder is used. For example, KTK type 2 manufactured by Kobe Steel, Ltd.
Screw extruder, TEM twin screw extruder manufactured by Toshiba Machine Co., Ltd., KC
A twin screw extruder manufactured by K Company, a PCM twin screw extruder manufactured by Ikegai Iron Works, a KEX twin screw extruder manufactured by Kurimoto Tekkosho, and a continuous single screw kneader such as a co-kneader manufactured by Buss are preferred. Used for In order to obtain the desired dispersion state of the release agent of the present invention, it is important that the temperature of the kneaded material is not increased more than necessary and that the kneaded material is rapidly rolled and cooled. For the pulverization, for example, coarse pulverization is performed using a hammer mill, a rotoplex, a pulverizer, or the like, and further pulverization is performed using a fine pulverizer using a jet stream or a mechanical pulverizer. Further, the particle size of the pulverized product is adjusted by an air classifier or the like, and if necessary, an external additive is externally added to the base toner by a Henschel mixer or the like. The final particle diameter of the toner is preferably about 3 to 15 μm in terms of volume average particle diameter.

[0035]

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

The evaluation method and conditions in the examples are shown below. Glossiness Using a Ricoh color copier Pretail 650 modified machine, in which the fixing roller was replaced with a PFA tube-coated roller and the silicone oil coating device was removed, 1.0 ± 0.05 mg /
cm ² of toner was developed, and the glossiness of the solid image sample when the fixing roller surface temperature was 160 ° C. was measured using a gloss meter manufactured by Nippon Denshoku Industries Co., Ltd. ° was measured. The transfer paper is Ricoh full color PPC paper type 6000-7
0 W was used. In order to obtain an image with a higher gloss value, a higher gloss, a clearer image and excellent color reproducibility, a higher value is required.
The above gloss is required. The evaluation results are shown below. ：: Very high gloss and excellent color reproducibility ○: High gloss and excellent color reproducibility △: Slightly low gloss and poor color reproducibility ×: Low gloss and poor color reproducibility

Offset Resistance Using a modified Ricoh color copying machine Pretail 650 used for the evaluation of glossiness, the temperature of the fixing roller was changed by 5 ° C., and the temperature at which offset began to occur was measured. The transfer paper is Ricoh full color PPC paper type 600
0-70W was used. The evaluation results are shown below. ◎: Offset is not generated up to a very high temperature and the offset resistance is very good. ：: Offset is not generated up to a high temperature and the offset resistance is excellent. ：: Offset resistance equivalent to that of the conventional wax-containing color toner ×: Low temperature Offset occurs, resulting in poor offset resistance

Durability Using a copying machine similar to that used for the evaluation of the glossiness, 50,000 copies of a test chart having an image area of 10% were copied, and the degree of reduction in the charge amount of the developer was evaluated. ◎: Very small decrease in charge amount and excellent durability ○: Small decrease in charge amount and excellent durability ：: Durability equivalent to conventional wax-containing color toner ×: Very large decrease in charge amount and durability Inferior

Pulverizability The toner particle size when pulverized under a certain pulverization condition using a jet mill was evaluated. ◎: Very small particle size and excellent crushability ○: Small particle size and excellent crushability △: Normal particle size and general crushability ×: Large particle size and poor crushability

Soft PVC contamination resistance The fixed image is sandwiched between soft PVC desk mats.
The evaluation was based on the amount of toner transferred to the desk mat after standing at 30 ° C. for 24 hours under a load of g / cm ² . ：: Transfer amount of toner to desk mat 0 0 Δ: Trace amount of transfer of toner to desk mat ×: Large transfer amount of toner to desk mat

Example 1 100 parts by weight of styrene-acrylic acid methyl ester copolymer A 5 parts by weight of carboxylic acid-modified polyethylene wax (SP value is less than 8.8) 5 parts by weight Charge control agent (metal salt of salicylic acid derivative) 2 2.5 parts by weight Coloring agent (copper phthalocyanine blue pigment) 2.5 parts by weight However, the copolymerization ratio of styrene and methyl acrylate of styrene-methyl acrylate copolymer A is (molar ratio) 70:30, The weight average molecular weight by GPC was 20,000, and the THF-insoluble content was 0% by weight.
After sufficiently mixing the above materials with a blender, the mixture is kneaded with a twin-screw extruder, and after cooling, pulverized and classified to have a volume average particle size of about 7.
A 5 μm cyan mother toner was obtained. Mother toner 10
As an external additive, hydrophobic silica (a surface-treated product with hexamethyldisilazane; primary particle size is 0.
02 μm) was mixed with a Henschel mixer at 0.5 parts by weight to obtain a cyan toner. The average thickness of the rod-shaped release agent in this toner was 0.54 μm. 5 parts by weight of the toner and 95 parts by weight of the silicone resin-coated carrier were mixed and stirred to prepare a two-component developer, and the glossiness, offset resistance, durability, and soft PVC stain resistance were evaluated and the crushability was evaluated. As described above, the gloss was high, the offset resistance, the durability, and the pulverizability were excellent, but the soft PVC stain resistance was slightly inferior.

Example 2 100 parts by weight of styrene-acrylic acid methyl ester copolymer B 5 parts by weight of carboxylic acid-modified polyethylene wax (SP value is less than 8.8) 5 parts by weight Charge control agent (metal salt of salicylic acid derivative) 2 2.5 parts by weight Colorant (copper phthalocyanine blue pigment) 2.5 parts by weight However, the copolymerization ratio (molar ratio) of styrene and methyl acrylate of styrene-methyl acrylate copolymer B is 55:45, The weight average molecular weight by GPC was 40000, and the THF-insoluble content was 0% by weight. The above-mentioned materials were sufficiently mixed in a blender, kneaded with a twin-screw extruder, cooled, pulverized and classified to obtain a cyan mother toner having a volume average particle size of about 7.5 μm. As an external additive, 0.5 part by weight of hydrophobic silica (having a surface treated with hexamethyldisilazane, primary particle diameter is 0.02 μm) was mixed with 100 parts by weight of the base toner using a Henschel mixer. A cyan toner was obtained. The average thickness of the rod-shaped release agent in this toner was 0.61 μm. 5 parts by weight of the toner and 95 parts by weight of the silicone resin-coated carrier were mixed and stirred to prepare a two-component developer, and the glossiness, offset resistance, durability, and soft PVC stain resistance were evaluated and the crushability was evaluated. Although the gloss was slightly low, sufficient gloss was obtained under the conditions for cardboard where the linear speed of the copying machine was halved. The offset resistance was very excellent, and the durability, soft PVC stain resistance, and crushability were also excellent.

Example 3 100 parts by weight of styrene-acrylic acid methyl ester copolymer C 5 parts by weight of carboxylic acid-modified polyethylene wax (SP value is less than 8.8) 5 parts by weight Charge control agent (metal salt of salicylic acid derivative) 2 2.5 parts by weight Colorant (copper phthalocyanine blue pigment) 2.5 parts by weight However, the copolymerization ratio (molar ratio) of styrene and methyl acrylate of styrene-methyl acrylate copolymer C is 55:45, The weight average molecular weight by GPC was 20,000, and the THF-insoluble content was 0% by weight. The above-mentioned materials were sufficiently mixed in a blender, kneaded with a twin-screw extruder, cooled, pulverized and classified to obtain a cyan mother toner having a volume average particle size of about 7.5 μm. As an external additive, 0.5 part by weight of hydrophobic silica (having a surface treated with hexamethyldisilazane, primary particle diameter is 0.02 μm) was mixed with 100 parts by weight of the base toner using a Henschel mixer. A cyan toner was obtained. The average thickness of the rod-shaped release agent in this toner was 0.65 μm. 5 parts by weight of the toner and 95 parts by weight of the silicone resin-coated carrier were mixed and stirred to prepare a two-component developer, and the glossiness, offset resistance, durability, and soft PVC stain resistance were evaluated and the crushability was evaluated. As described above, the gloss was high, and the offset resistance and durability, soft PVC stain resistance, and pulverizability were excellent.

Example 4 100 parts by weight of styrene-methyl acrylate copolymer C 5 parts by weight of carnauba wax 2 parts by weight of charge control agent (metal salt of salicylic acid derivative) Coloring agent (copper phthalocyanine blue pigment) 2.5 parts by weight A toner was prepared in the same manner as in Example 3 except that the wax was changed to carnauba wax in the toner formulation in Example 3, and the same evaluation as in Example 3 was performed. The average thickness of the rod-shaped release agent in this toner was 0.28 μm, which was smaller than that of the toner of Example 3. The evaluation results are shown in Table 1. The gloss was high and the offset resistance and durability, soft PVC stain resistance, and pulverizability were all excellent. In particular, the durability was improved as compared with the toner of Example 3 and was very excellent.

Example 5 Styrene-methyl methacrylate-methyl methacrylate copolymer D 100 parts by weight Carnauba wax 5 parts by weight Charge control agent (metal salt of salicylic acid derivative) 2 parts by weight Colorant (copper) (Phthalocyanine blue pigment) 2.5 parts by weight provided that the styrene-methyl acrylate-methyl methacrylate copolymer D has a copolymerization ratio (molar ratio) of styrene, methyl acrylate and methyl methacrylate of 40:45: The weight average molecular weight by GPC was 20,000, and the THF insoluble matter was 0% by weight.
Met. A toner was prepared in the same manner as in Example 4, except that the binder resin was changed to styrene-methyl acrylate-methyl methacrylate copolymer D in the toner prescription of Example 4. The same evaluation was performed. The average thickness of the rod-shaped release agent in this toner is 0.1.
It was 36 μm. The evaluation results are shown in Table 1. The gloss was high, the offset resistance and durability, the soft PVC stain resistance,
Both grindability was excellent.

Example 6 ・ Styrene-methyl acrylate copolymer C 80 parts by weight ・ Polyester resin 20 parts by weight ・ Carnauba wax 5 parts by weight ・ Charge controlling agent (metal salt of salicylic acid derivative) 2 parts by weight ・ Colorant (Copper phthalocyanine blue pigment) 2.5 parts by weight The toner formulation of Example 4 was changed to the toner formulation of Example 4 except that the binder resin was changed to a mixture of styrene-methyl acrylate copolymer C and a polyester resin. A toner was prepared in the same manner as described above, and the same evaluation as in Example 4 was performed. This polyester resin was a terephthalic acid-based polyester, the weight average molecular weight was 20,000, and the THF insoluble content of the resin mixture was 0% by weight. The average thickness of the rod-shaped release agent in this toner was 0.44 μm. The evaluation results are shown in Table 1. The gloss was high and the offset resistance and durability, soft PVC stain resistance, and pulverizability were all excellent.

Example 7 With respect to 100 parts by weight of the base toner obtained in Example 3,
As external additives, 0.5 parts by weight of hydrophobic silica (surface-treated with hexamethyldisilazane, primary particle diameter: 0.02 μm) and hydrophobic silica (surface-treated with hexamethyldisilazane, specific surface area: 35 m) ² / g, bulk density 240 g /
l) 0.5 parts by weight were mixed with a Henschel mixer to obtain a cyan toner. 5 parts by weight of this toner and 95 parts by weight of a silicone resin-coated carrier are mixed and stirred to prepare a two-component developer, and gloss, offset resistance, durability,
The results of evaluating the soft PVC stain resistance and the crushability are shown in Table 1. The gloss was high, and the offset resistance and durability, the soft PVC stain resistance, and the crushability were excellent. In particular, the durability was improved as compared with the toner of Example 3 and was very excellent.

Comparative Example 1-100 parts by weight of styrene-methyl acrylate copolymer E-5 parts by weight of carboxylic acid-modified polyethylene wax (SP value is less than 8.8)-Charge control agent (metal salt of salicylic acid derivative) 2 2.5 parts by weight Colorant (copper phthalocyanine blue pigment) 2.5 parts by weight However, the copolymerization ratio of styrene and methyl acrylate of styrene-methyl acrylate copolymer E is 55:45, and the weight average by GPC Molecular weight is 10
000, THF insoluble content was 0% by weight. A toner was prepared using the above materials in the same manner as in Example 3 except that styrene-methyl acrylate copolymer E having a lower molecular weight was used than in Example 3, and evaluation was performed. The average thickness of the rod-shaped release agent in this toner was 0.66 μm. The evaluation results are shown in Table 1. As a result, higher glossiness was obtained as compared with the toner of Example 3, but the offset resistance was considerably inferior.

Comparative Example 2 100 parts by weight of styrene-acrylic acid methyl ester copolymer F 5 parts by weight of carboxylic acid-modified polyethylene wax (SP value is less than 8.8) 5 parts by weight Charge control agent (metal salt of salicylic acid derivative) 2 2.5 parts by weight Colorant (copper phthalocyanine blue pigment) 2.5 parts by weight However, the copolymerization ratio (molar ratio) of styrene and methyl acrylate of styrene-methyl acrylate copolymer F is 55:45, The weight average molecular weight by GPC was 60000, and the THF-insoluble content was 3% by weight. A toner was prepared and evaluated in the same manner as in Example 3 except that the styrene-acrylic acid methyl ester copolymer F having a high molecular weight and containing a THF-insoluble component was used. . The average thickness of the rod-shaped release agent in this toner was 0.59 μm. The evaluation results are shown in Table 1. As a result, although the offset resistance was superior to that of the toner of Example 3, the image was not glossy.

Comparative Example 3 100 parts by weight of polyester resin 5 parts by weight of carnauba wax 2 parts by weight of charge controlling agent (metal salt of salicylic acid derivative) 2.5 parts by weight of colorant (copper phthalocyanine blue pigment) Example 4 A toner was prepared in the same manner as in Example 4 by using the toner formulation described above except that the binder resin was changed to a polyester resin, and the same evaluation as in Example 4 was performed. This polyester resin is the same as that used in Example 6.
The average thickness of the rod-shaped release agent in this toner was 1.03 μm, which was larger than that of the toner of Example 4. The evaluation results are shown in Table 1. The durability and pulverizability were clearly inferior to those of the toner of Example 4.

Comparative Example 4 ・ Styrene-butyl acrylate copolymer 100 parts by weight ・ Carnauba wax 5 parts by weight ・ Charge control agent (metal salt of salicylic acid derivative) 2 parts by weight ・ Colorant (copper phthalocyanine blue pigment) 2 0.5 parts by weight A toner was prepared in the same manner as in Example 4, except that the binder resin was changed to a styrene-butyl acrylate copolymer in the same manner as in Example 4. Was evaluated. The copolymerization ratio (molar ratio) of styrene and butyl acrylate of this styrene-butyl acrylate copolymer was 80:20, the weight average molecular weight by GPC was 20,000, and the THF insoluble matter was 0% by weight. . No rod-shaped release agent was observed in the toner. It is considered that a part of the toner was insoluble in THF, and the binder resin and carnauba wax were in a compatible state or in a dispersed state close to it. The evaluation results are shown in Table 1. The toners of Example 4 were clearly inferior in offset resistance and soft PVC stain resistance.

[0052]

[Table 1]

[0053]

According to the first aspect of the present invention, the color toner comprises a binder resin.
Styrene monomer and acrylic acid methyl ester
And vinyl-based copolymers containing
And the binder resin in the toner is substantially TH
Contains no F insolubles and has a weight average molecular weight of 1
2000 to 50,000, and the release agent is contained in the toner.
Exists as a rod-shaped domain and the average of the rod-shaped domains
Since the thickness is 0.05 to 0.80 μm, a fixed image is suitable.
High gloss, excellent color reproduction of full-color images,
Do not apply release oil to the fixing member
Sufficient offset in fixing method with very small coating amount
At the same time as anti-cutting properties, and furthermore,
Productivity (toner grindability), contamination resistance for soft PVC products
Also excellent in nature. The color toner according to claim 2 is the color toner.
The solubility parameter (SP value) of the template is 8.8 to 9.2.
By doing so, the binder resin and the release agent are incompatible,
Easily and stably by giving appropriate affinity to the desired release agent
Excellent anti-offset because dispersion state can be obtained
And the durability is further improved. Claim 3
The color toner is composed of a styrene monomer in the binder resin and
Acrylic acid methyl ester monomer ratio (styrene-based
Monomer: acrylic acid methyl ester monomer) in a molar ratio of 5
By setting the ratio to 0:50 to 60:40, soft PVC contamination can be achieved.
The prevention is assured. The color toner according to claim 4.
Is (a) a primary particle diameter of at least 0.01 as an external additive.
-0.03 μm hydrophobized silica, and (b)
Specific surface area 20-50m ²/ G, bulk density 100-250g
/ L of hydrophobized silica is added,
The durability is further improved.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Keiko Shiraishi, Inventor 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masahide Yamashita 1-3-6, Nakamagome, Ota-ku, Tokyo Stock Inside Ricoh Company (72) Inventor Akihiro Ban 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Toshishi Sawada 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Mitsuteru Kato 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H005 AA01 AA06 AA08 AA15 AA21 CA04 CB13 EA05 EA06 EA10

Claims (4)

[Claims] 1. A color toner for developing an electrostatic image containing at least a binder resin, a colorant and a release agent, wherein the binder resin mainly comprises a styrene monomer and a methyl acrylate monomer. The binder resin in the toner contains substantially no tetrahydrofuran-insoluble matter, the weight average molecular weight by GPC is 12,000 to 50,000, and the releasing agent is a toner. A color toner for developing an electrostatic image, wherein the color toner exists as a rod-shaped domain therein, and the average thickness of the rod-shaped domain is 0.05 to 0.80 μm. 2. The solubility parameter (SP) of the release agent
(Value) is 8.8 to 9.2.
The color toner for developing an electrostatic image according to the above. 3. The molar ratio of a styrene monomer to an acrylic acid methyl ester monomer (styrene monomer: acrylic acid methyl ester monomer) in the binder resin is 5%.
2. The ratio is from 0:50 to 60:40.
Or a color toner for developing an electrostatic image according to 2. 4. Further, at least (a) 1
Hydrophobized silica having a secondary particle diameter of 0.01 to 0.03 μm and (b) hydrophobicized silica having a specific surface area of 20 to 50 m ² / g and a bulk density of 100 to 250 g / l are added. The color toner for developing an electrostatic image according to claim 1, wherein: