JPH07219274A - Electrophotographic color toner and fixing method - Google Patents

Abstract

PURPOSE:To allow a color toner to hold excellent OHP transparency, winding resistance and axti-offset property. CONSTITUTION:In the electrophotographic color toner containing at least a binder resin, an polyolefin wax and a pigment-dispersed resin, the pigment- dispersed resin is obtained by heating after incorporating a hydrated paste of the pigment into a resin solution for dispersing the pigment and there is a relation expressed by an equation, 1.5>=¦SPp-SPb¦>=0.5, between the SP value (SPp) of the binding resin and the SP value (SPb) of the pigment dispersing resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color toner for electrophotography used for forming a color image.

[0002]

2. Description of the Related Art Conventionally, when a color image is formed by superposing color toner images by subtractive color photography, color toners such as yellow, magenta and cyan are used. In such a color toner, light resistance,
From the viewpoint of improving the color tone and the like, a pigment is advantageously used as a colorant.

On the other hand, in order to satisfactorily fix the color toners by the heat roller fixing device, the color toners are required to have offset resistance and winding resistance. From this point of view, it is effective to add a polyolefin wax to the color toner.

However, since the pigment generally has a high compatibility with the polyolefin wax, the polyolefin wax is deeply dispersed together with the pigment in the binder resin, and as a result, the color toner particles are fixed when the color toner is fixed. There is a problem that the bleeding of the polyolefin wax from the surface becomes insufficient and the offset resistance and the winding resistance are lowered.

Regarding the fixing property of OHP, it is known that a linear polyester resin obtained by a polycondensation reaction of a polyol and a polycarboxylic acid is used as a toner resin because it has a sharp melting property. (See Japanese Patent Laid-Open No. 50-63939) When the color toner containing the linear polyester resin is fixed by the heat roller fixing method, there is an offset phenomenon in which the molten toner is transferred to the fixing roller. There is a problem that tends to occur.
As means for preventing the occurrence of such an offset phenomenon,
A technique is known in which silicon oil is applied to the surface of a fixing roller to prevent molten toner from transferring to the fixing roller. However, OH consisting of polyester film, etc.
When a large amount of silicon oil is supplied as in the conventional case when forming an image on a P sheet, the silicon oil adheres to the OHP sheet, and the O due to the excessively adhered silicon oil.
There is a problem that HP transmission unevenness occurs.

Further, it is generally practiced to incorporate a polyolefin wax into the toner to improve the releasability, but in the case of a color toner, the polyolefin wax is incorporated into the color pigment, and therefore the polyolefin wax is fixed at the time of heat roller fixing. Is difficult to seep out, and sufficient releasability cannot be exhibited.

Therefore, in order to make it difficult for the polyolefin wax to be incorporated into the color pigment, the following method has been proposed.

(1) A technique for forming a color toner by dispersing a pigment (hereinafter also referred to as a processed pigment) coated with a polyester resin having a molecular weight higher than that of the polyester resin in a binder resin composed of the polyester resin (Japanese Patent Application Laid-Open No. 2000-242242). See Japanese Patent Publication No. 62-280755).

(2) When a processed pigment obtained by melt-kneading a pigment and a pigment resin is dispersed and contained in a binder resin to form a color toner, the weight average molecular weight of the pigment resin is the same as that of the binder resin. A technique of making the weight average molecular weight smaller than the weight average molecular weight so that the binder resin has a weight average molecular weight of 100,000 or more (see JP-A-2-66561).

(3) In the case of producing a color toner, a method in which a colorant and a binder resin are melted, kneaded, pulverized, and then classified to obtain a toner having a predetermined particle size is mainly used. At that time, when using a pigment as a coloring agent to be used,
Since the pigment is coarsened by drying, it becomes necessary to re-pulverize it to make it into fine particles. To improve this point, an aqueous dispersion of fine particle pigments obtained by the acid paste method or acid slurry method is mixed into an organic solvent solution of the resin and heat-treated to bind the pigment dispersion resin. A technique of mixing with a resin (see JP-A-62-127847).

(4) A method of using a masterbatch in which a styrene resin or a styrene-acrylic resin and a pigment are kneaded with a polyester resin binder (JP-A-3-107).
(See Publication No. 869).

(5) Color toner technology in which a pigment surface-treated with a material such as rosin is added to a specific polyester resin (see Japanese Patent Laid-Open No. 4-317070).

[0013]

However, JP-A-62-280
In the technology described in Japanese Patent No. 755, since the compatibility between the pigment and the high molecular weight polyester resin is still insufficient, the pigment in the processed pigment easily migrates into the binder resin, and as a result, the polyolefin in the binder resin is The wax is taken into the pigment and is deeply dispersed, and eventually, there is a problem that the offset resistance and the winding resistance are deteriorated during the fixing of the color toner.

In the technique described in Japanese Patent Application Laid-Open No. 2-66561, since the processed pigment is prepared by melt-kneading the pigment and the pigment resin, the details of the pigment particles are not covered with the pigment resin,
After all, the releasability of the toner is likely to decrease.

In the technique described in Japanese Patent Laid-Open No. 62-127847,
Since the binder resin and the pigment dispersion resin have the same composition and are compatible with each other,
Although the dispersion of the pigment is improved, re-aggregation of the pigment and further incorporation of the polyolefin wax occur at the time of melt-kneading, and as a result, there arises a problem that offset resistance and winding resistance are deteriorated at the time of fixing the toner.

In the technique described in JP-A-3-107869, since a styrene resin having a large Sp value difference with respect to the polyester resin is used, when the polyester resin and the masterbatch are kneaded, the polyester of the styrene resin itself is used. Poor dispersion due to low solubility in the resin causes an increase in the dispersed diameter of the pigment, resulting in a problem of reduced transparency.

The technique described in Japanese Patent Application Laid-Open No. 4-317070 has a drawback that the presence of an additive such as rosin causes problems such as inhibition of fixing property.

As described above, various proposals have been made, but no color toner satisfying good OHP transparency and good offset property has been obtained.

Further, generally, by using a crosslinked resin or a non-linear resin having a high melt viscosity, the offset resistance of the toner can be improved. But transparent OHP
In order to obtain an image, it is necessary to raise the temperature of the toner layer to a temperature not lower than the melting and softening point of the toner binder resin at the time of fixing with a heat roller to reduce the viscosity and form a flat fixed image surface. Therefore, even if a toner having a high melt viscosity and originally excellent in offset resistance is used, fixing offset occurs, and
There is a problem that the transparency of the HP image is also reduced.

In order to solve this problem, when toner having a low melt viscosity is used and silicone oil is applied to the fixing roller, fixing offset can be sufficiently prevented if the amount of silicone oil applied is small. It is difficult, and conversely, when the amount of silicone oil applied is large, the silicone oil adheres to the OHP sheet, and OHP transmission unevenness occurs due to the excessively adhered silicone oil. In a system in which it is necessary to apply silicone oil, various problems occur due to silicone oil.

Therefore, there has been proposed a toner which requires an effect of improving the offset property. As a means of increasing the offset resistance of the toner without increasing the melt viscosity of the binder resin, it is effective to include a polyolefin wax in the toner to improve the releasability of the toner. Has a good affinity for the color pigment and the polyolefin wax, and since the polyolefin wax is incorporated into the color pigment, there is a problem that the polyolefin wax is less likely to exude during fixing on a heat roller, and sufficient releasability cannot be exhibited. On the other hand, when the amount of the polyolefin wax added is increased to obtain sufficient releasability, the fixed image becomes clouded, and there is a problem that an OHP image with excellent transparency cannot be obtained.

Therefore, the present invention has been made in view of the above-mentioned actual situation in the prior art to improve the situation. That is, an object of the present invention is to provide a color toner excellent in offset resistance at the time of fixing and winding resistance while maintaining high dispersibility of the pigment in the binder resin and forming an OHP image having excellent transparency. To provide.

[0023]

In order to achieve the above object, the color toner of the present invention uses a polyolefin wax and a pigment dispersion resin incompatible with the binder resin in the binder resin. It was completed by discovering that it is possible to prevent reaggregation of the pigment, maintain uniform dispersion, prevent migration of the pigment into the binder resin, and suppress the highly dispersed state of the polyolefin wax in the binder resin. It is a thing.

That is, in a color toner containing at least a binder resin, a polyolefin wax, and a pigment-dispersing resin, after the pigment-containing resin is mixed with the pigment-containing water-containing paste in the pigment-dispersing resin solution. It was obtained by heat treatment, and was 1.5 ≧ | SPp-SP between the SP value (SPb) of the binder resin and the SP value (SPp) of the pigment dispersion resin.
The present invention can be achieved by an electrophotographic color toner characterized by having a relationship of b | ≧ 0.5. or,
Those satisfying the following conditions are more preferable.

The electrophotographic photograph as described above, wherein the pigment is 30 to 200 parts by weight with respect to 100 parts by weight of the pigment dispersing resin, and the proportion of the pigment dispersing resin in the entire color toner is 2 to 30% by weight. Color toner.

The fixing method for color toner for electrophotography as described above, wherein the elasticity of the fixing roller has a hardness of 50 ° to 85 °.

Since the dispersion of the polyolefin wax in the pigment is suppressed as described above, the bleeding of the polyolefin wax from the surface of the toner particles becomes good at the time of fixing, and the offset property, the winding property and the OHP permeability are improved. . Further, in this case, the outflow of the pigment can be prevented by making the compatibility between the binder resin and the pigment dispersion resin specific.

That is, by setting the difference between the SP value (SPb) of the binder resin and the SP value (SPp) of the pigment dispersion resin to be 0.5 or more, it is possible to prevent the outflow of the pigment. If the difference between the two exceeds 1.5, the solubility difference between the binder resin and the pigment-dispersing resin becomes too large, resulting in poor dispersion of the pigment-dispersing resin in the binder resin.

The solubility parameter (SP) is Hildeb
It is defined by the following equation in the rand-Scatchard dissolution theory.

[0030]

[Equation 1]

However, ΔEV represents the evaporation energy, and V
Represents the molecular volume and ΔEV / V represents the cohesive energy density. The unit of solubility parameter (SP) is (cal / cm ³ )
It is ^1/2 .

There are various methods for obtaining the solubility parameter value. For example, the reference “RF Fedors, Polymer. Eng., 14, (2) 147” is used.
(1974) ”. That is, in the structural formula of the compound to be obtained, the following formula is used to calculate from the data of the evaporation energy of atoms and atomic groups and the molar volume.

[0033]

[Equation 2]

However, Δei and ΔVi represent vaporization energy volumes of atoms or atomic groups, respectively. In addition, regarding polyester resins, the literature “KWSuh, DHClarke, J. Pol.
ym.Sci., Part A-1, 5, 1671 (1967) ”. This is a method in which a non-solvent is added to a polymer solution and the solubility parameter value is determined by the amount of the non-solvent required until turbidity occurs.

The pigment-dispersed resin used in the present invention is obtained by adding and mixing a water-containing paste of a pigment to a solution in which a binder resin and a pigment-dispersing resin having an SP value within a specific range are dissolved, and heat-treated. It is obtained by drying and crushing.
The mixing ratio of both is preferably 30 to 200 parts by weight of the pigment with respect to 100 parts by weight of the resin for dispersing the pigment. Here, the water content in the pigment-containing paste is approximately 10 to 50% by weight. If the water content is too large, the pigment will agglomerate due to the water when dispersed in the resin, and if the water content is too small, the pigment itself will agglomerate, causing a problem of poor dispersion. The proportion of the pigment-dispersed resin in the entire color toner is preferably 2 to 30% by weight.

In order to form a solution of the pigment-dispersing resin, the resin is added to and mixed with an organic solvent such as benzene, toluene, acetone, methyl ethyl ketone, and ethyl acetate to form a solution. Here, the concentration of the resin in the solution is approximately 10 to
30% by weight.

In the present invention, by coating the color pigment with a resin which is incompatible with the binder resin, the surface of the pigment is sufficiently covered, so that the polyolefin wax is not taken into the pigment and the releasability is greatly improved. To do. Therefore, even if the melt viscosity of the toner layer is lowered to form the OHP image, the fixing offset does not occur at the time of fixing the heat roller.

[0038]

The pigment-dispersing resin may have any SP value difference between the binder resin and the pigment-dispersing resin within a specific range. For example, when the binder resin is a polyester resin, SP value = 10.8 and SP = 10.3 to 9.3 or SP value = 11.3 to 12.3 may be selected. Specifically, as a pigment dispersion resin, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p- Ethylstyrene ・ 2,4-dimethylstyrene ・ pt-butylstyrene ・ pn-hexylstyrene ・ pn-octylstyrene ・ pn-nonylstyrene ・ p-
Styrene or styrene derivatives such as n-decyl styrene, pn-dodecyl styrene, and methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, methacrylic acid
t-Butyl / methacrylic acid n-octyl / methacrylic acid 2-
Methacrylic acid ester derivatives such as ethylhexyl, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, etc.
Ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, acrylic acid Dimethylaminoethyl
A copolymer with an acrylate derivative such as diethylaminoethyl acrylate is suitable.

Further, olefins such as ethylene, propylene and isobutylene, vinyl chloride, vinylidene chloride,
Halogen vinyls such as vinyl bromide and vinyl fluoride, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl methyl ketone,
Vinyl ketones such as vinyl ethyl ketone / vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole / N-vinyl indole / N-vinyl pyrrolidone, vinyl compounds such as vinyl naphthalene / vinyl pyridine, acrylonitrile / methacrylonitrile / Acrylic acid or methacrylic acid derivatives such as acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, methacrylamide, N-butylmethacrylamide, N-octadecylacrylamide, acrylic acid, methacrylic acid, α-ethylacrylic acid, fumaric acid It may be a copolymer with maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, maleic acid monooctyl ester, cinnamic acid anhydride, alkenyl succinic acid methyl half ester, etc.,
In any case, the resin for pigment dispersion of the present invention can be obtained by setting the SP value within the above range.

When the binder resin is styrene-acrylic resin, the SP value of this is in the range of approximately 9.2 to 9.7, and therefore the SP value of the pigment dispersing resin is 0.5 to 1.5 in absolute value. A resin having a difference of 1 may be used. Specifically, so-called condensation resins such as polyester resin, nylon resin, urethane resin, urea resin, epoxy resin are used, and polyester resin is preferable.

The binder resin can be selected from resins such as polyester resin, styrene resin, styrene-acrylic resin and epoxy resin, and particularly polyester resin and styrene-acrylic resin can be preferably used. .

As the polyolefin wax, low molecular weight polypropylene / low molecular weight polyethylene / ethylene-
Examples thereof include propylene copolymers and the like. From the standpoint of offset resistance, it is 100 in DSC as a polyolefin.
Those having a melting peak at ˜180 ° C. are preferable. From the viewpoint of mold releasability and fluidity, the blending ratio of the polyolefin wax is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

The color pigments used in the present invention include:
Examples include yellow pigments, magenta pigments, cyan pigments, and red pigments. As the yellow pigment, a benzidine yellow pigment is desirable. The benzidine-based yellow pigment refers to a yellow organic pigment of 3,3'-dichlorobenzidine derivative. Specifically, CI Pigment Yellow No. 12, Same as 13, Same as 14, Same as 15, Same as 17, Same as 55, Same as 83, Same as 1
74 (CI No. 21090, 21100, 21095, 21105) and the like are representative. The magenta pigment is 2,9-dimethylquinacridone, which is a quinacridone-based magenta pigment.
(CIPigment Red 122), CIPigment Red No.57-1, which is an azo lake type magenta pigment, and the like can be mentioned. As the cyan pigment, a copper phthalocyanine-based pigment is preferable. Specific examples include CI Pigment Blue No. 15, 15-3, 15-4, 15-6 and halogenated phthalocyanine. As the red pigment, an insoluble monoazo pigment, an azo lake pigment, and a perylene pigment are desirable. Specifically, CI Pigment Red 22, 48-1, 48-2, 48-3, 53-1,
57-1, 112, 149, 178 and the like.

As the method for producing the color toner of the present invention, a binder resin, a polyolefin wax, a pigment dispersion resin, and a charge control agent optionally used are premixed, then melt-kneaded and cooled. Then, a method of pulverizing and classifying can be adopted. Furthermore, inorganic fine particles such as hydrophobic silica or titanium oxide may be added to and mixed with the colored particles obtained by pulverizing and classifying.

The volume average particle diameter of the color toner in the present invention is 4 to 20 μm, preferably 5 to 15 μm. The volume average particle size is a value measured by a Coulter counter.

The color toner of the present invention can be used as a two-component developer by mixing it with a carrier. As the carrier constituting the two-component developer, either an uncoated carrier composed only of magnetic material particles such as iron and ferrite, or a resin coated carrier in which the surfaces of the magnetic material particles are coated with a resin may be used. The volume average particle diameter of the carrier is preferably 30 to 150 μm.

FIG. 1 shows the overall structure of an image forming apparatus 3 using a fixing roller 2. Reference numeral 4 denotes a rotatable photoconductor drum, and a belt electrode 5 formed on the outer peripheral surface of the photoconductor drum 4 for charging the photoconductor 4A, and an exposure document 6 for exposing the charged photoconductor 4A surface. The original 6 is irradiated by the exposure lamp 7, the reflecting mirror 8 moving together with the exposing lamp 7, and the light from the reflecting mirror 8 are received, and the lens 11 and the reflecting mirror 12 are provided by the reflecting mirrors 9 and 10 arranged at 90 °. The image of the original 6 is exposed through the. The electrostatic latent image formed by the exposure is developed by the developing device 13 (actually, in the case of color development, there are usually four developing devices of magenta, cyan, yellow and black), and By development, a visible image 13A made of toner or the like is formed on the surface of the photosensitive drum 4. On the other hand, the recording paper P fed from the paper feed unit 14 is temporarily stopped by the second paper feed roller 15, the second paper feed roller 15 is started so as to match the visible image 13A, and the transfer pole 16 is used. The visible image 13A is transferred onto the recording paper P. After the transfer is completed, the recording sheet P is separated by the separation pole 17 and is conveyed to the fixing roller 2 by the conveying device 18. After the visible image 13A (hereinafter referred to as a toner image) is transferred onto the recording paper P, the toner remaining on the photoconductor 4A is cleaned by the cleaning device L1. A pressure roller 20 is provided on the fixing roller 2, and a heating means 21 is built in the fixing roller 2 to heat the fixing roller 2 to a constant temperature. The recording paper P is pressed against the fixing roller 2 by the pressure contact roller 20, and the transferred visible image 13A is fixed. After the fixing is completed, the surface of the fixing roller 2 is immediately cleaned by the cleaning member 22 formed in a roller shape, and the recording paper P
Is discharged to the paper discharge unit 23.

FIG. 2 shows a pressure-bonding roller 20 that pressure-bonds the fixing roller 2 to the fixing roller 2 in the conveying path P1 of the recording paper P, and a core material 22A that cleans the surface of the fixing roller 2 after fixing.
2 shows a fixing device 24 in which a roller-shaped cleaning member 22 provided in the above is combined. Center line 25 of the fixing roller 2
As a result, the cleaning member 22 is arranged on the paper discharge side of the transport path P1, and is brought into pressure contact with the surface of the fixing roller 2 as illustrated.

With the above-described structure, the toner image 13A is formed on the photosensitive surface 4A of the photosensitive drum 4 of the image forming apparatus 3, is transferred to the recording paper P, and is transferred to the recording paper P by the conveying device 18. Is conveyed to the fixing device 24 shown in FIG. The recording paper P is conveyed on the conveyance path P1 and heated by the heating means 21 (2
The recording paper P is pressure-bonded by the pressure roller 20 by the fixing roller 2 which is set to about 00 °, and the toner image 13A on the recording paper P is fixed. The recording paper P on which the toner image 13A is fixed is ejected to the paper ejection unit 23 shown in FIG. On the other hand, since a part of the toner image 13A adheres to the fixing roller 2 on which the toner image 13A is fixed, cleaning is performed by the cleaning member 22.

In the mechanical constitution of the fixing device, it is preferable to use an elastic roller as the roller on the side where the toner layer on the image support is in direct contact. That is, when the fixing roller has elasticity, the surface of the fixing upper roller itself deforms and presses against the unevenness of the surface of the unfixed toner image, so that the toner image can be uniformly heated and pressed, and the glossiness can be improved. It is possible to obtain a uniform image of. In this case, the elasticity of the fixing roller is preferably 50 ° to 85 ° in hardness. If the hardness is less than 50 °, the fixing roller will deform excessively,
There is a problem in the paper passing property of the image support. If the hardness is higher than 85 °, the deformation of the surface of the fixing roller will be insufficient, so
It becomes impossible to uniformly heat the toner layer. Further, the roller on the side which is pressed against the fixing roller via the image support (hereinafter referred to as a pressure roller) has a hardness so as to sufficiently press the fixing roller against the surface of the unfixed toner image. Is preferably the same as the hardness of the fixing roller or higher than the hardness of the fixing roller. In order to impart elasticity of such an appropriate hardness to the fixing roller and the pressure roller, an elastic rubber layer made of silicone rubber, fluororubber or the like may be provided on the roller surface. Incidentally, these hardnesses are measured by an Asker C hardness meter.

Further, in order to impart releasability for the purpose of preventing offset, polyvinylidene fluoride (PVF), polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) is provided on the roller surface. It is preferable to provide a coating layer having low surface energy, such as Further, a method of improving the releasability of the fixing roller itself by applying a very small amount of silicon oil by bringing a pad, a web or a roll containing silicone oil into contact with the fixing roller is also a preferable method.

[0052]

EXAMPLES Examples of the present invention will be specifically described below together with comparative examples, but the present invention is not limited to these embodiments. In the following, "part" means "part by weight".

Example 1 (Production of Pigment Dispersion Resin) A water-containing paste (water content = 35%) of a fine particle benzidine yellow pigment composed of a 3,3′-dichlorobenzidine derivative was used as a styrene-acryl copolymer having an SP value of 9.8. The polymer resin was added to a solution dissolved in acetone, then heated to 60 ° C., stirred for 1 hour, the solvent was removed, and the mixture was dried and pulverized to obtain a pigment dispersion resin A of the present invention.

The compounding ratio is 60 parts by weight of styrene-acrylic copolymer resin and 40 parts by weight of yellow pigment.

(Production of Color Toner) Polyester Resin (SP = 10.8) 100 parts Polypropylene wax 4 parts Pigment Dispersion Resin A (SP = 9.8) 20 parts The above materials were premixed with a Henschel mixer, and then with an extruder. The mixture was melt-kneaded, cooled, and then finely pulverized to obtain colored particles having a volume average particle diameter of 9.1 μm.

Hydrophobic silica fine particles were added to the colored particles 1.0
The yellow toner of the present invention was obtained by adding and mixing it in a ratio of about 5% by weight. This is designated as "Example Toner 1".

Example 2 (Production of Pigment Dispersion Resin) Water-containing paste of finely divided magenta pigment composed of 2,9-dimethylquinacridone (water content = 48)
%) Is added to a solution of a linear polyester resin having an SP value of 10.9 dissolved in acetone, and the mixture is heated to 60 ° C., stirred for 1 hour, the solvent is removed, and the mixture is dried and pulverized to obtain a pigment dispersion resin B of the present invention. Obtained.

The mixing ratio was 60 parts of linear polyester resin and 40 parts of magenta pigment.

(Production of Color Toner) Styrene-acrylic copolymer resin (SP = 9.6) 100 parts Polypropylene wax 4 parts Pigment Dispersion Resin B (SP = 10.9) 20 parts The above materials are used as “Example toner 1”. A color toner of the present invention having a volume average particle diameter of 8.9 μm was obtained in the same manner as in the production example of. This is designated as "Example Toner 2".

Example 3 (Production of Pigment Dispersion Resin) In Production Example of Pigment Dispersion Resin B, a linear polyester resin having a different composition was used, and an aqueous dispersion of a fine particle cyan pigment made of copper phthalocyanine as a pigment was used. Pigment Dispersion Resin C of the present invention was obtained in the same manner except that (water content = 13%) was used.

(Production of Color Toner) Styrene-acrylic copolymer resin (SP = 9.6) 100 parts Polypropylene wax 4 parts Pigment Dispersion Resin C (SP = 8.9) 20 parts In Example-2, Pigment Dispersion Resin B A cyan color toner having a volume average particle size of 8.1 μm was obtained in the same manner except that the pigment dispersion resin C was used in place of the above. This is “Example Toner 3”.
And

Comparative Example-1 Styrene-acrylic copolymer resin (SP = 9.6) 100 parts Polypropylene wax 4 parts Pigment Dispersion Resin A (SP = 9.8) 20 parts was treated in the same manner as in Example 1 and volume averaged. A comparative yellow color toner having a particle size of 9.0 μm was obtained. This is designated as “Comparative Toner 1”.

Comparative Example-2 Polyester resin (SP = 10.8) 100 parts Polypropylene wax 4 parts Pigment Dispersion Resin B (SP = 10.9) 20 parts was treated in the same manner as in Example 1 to give a volume average particle diameter of 9.1 μm. A magenta color toner for comparison was obtained. This is designated as “Comparative Toner 2”.

Comparative Example-3 Polyester Resin (SP = 10.9) 100 Parts Polypropylene Wax 4 Parts Pigment Dispersion Resin C (SP = 8.9) 20 parts was treated in the same manner as in Example 1 to give a volume average particle diameter of 8.9 μm. A cyan color toner for comparison was obtained. This is designated as “Comparative Toner 3”.

Comparative Example-4 (Production of Pigment Dispersion Resin) In the production example of Pigment Dispersion Resin A, a pigment dispersion resin D for comparison was prepared in the same manner except that the pigment alone was used without using the water-containing paste of the pigment. Got

(Production of Color Toner) Polyester Resin (SP = 10.8) 100 Parts Polypropylene Wax 4 Parts Pigment Dispersion Resin D (SP = 9.8) 20 parts was treated in the same manner as in Example 1 to give a comparative yellow color toner. Got This is designated as “comparative toner 4”.

(Evaluation Test) Each two-component type developer was prepared by mixing the color toners obtained in the above Examples and Comparative Examples with the carrier at a ratio such that the toner concentration was 7% by weight. The carrier used was a coating carrier having a weight average particle diameter of 40 μm, which was obtained by forming a resin coating layer of styrene-methyl methacrylate copolymer resin having a thickness of 1.0 μm on the surface of spherical ferrite particles.

Using each of the above two-component developers,
A test of forming a solid unfixed image having a width of 5 cm only on the leading end side of the fixing paper and then fixing the unfixed toner image from the leading end side of the fixing paper by changing the fixing temperature with a heat roller fixing device, The wrapping occurrence temperature (below it describes the temperature at which wrapping occurs) and the offset occurrence temperature (above it describes the temperature at which offset occurs) were measured.
The heat roller fixing device used was a fixing roller having a PFA (tetrafluoroethylene-perfluoroethylene-perfluoroalkyl vinyl ether copolymer) coating layer, and a silicone rubber coating layer having an Asker C hardness of 65 °. The load of the upper roller was 1.5 kg / cm, and the linear velocity was set to 140 mm / sec for the measurement of the winding generation temperature and 40 mm / sec for the measurement of the offset generation temperature. In addition, in the case of evaluation of the fixing offset, evaluation using an OHP sheet was also performed.

The results are shown in Table 1.

[0070]

[Table 1]

As can be understood from the results of Table 1, according to the color toner of the present invention, since the bleeding of the polyolefin wax is excellent, the wrapping generation temperature is low, the wrapping resistance is excellent, and the offset generation temperature is high. High and excellent in offset resistance.

The transparency of the OHP image was measured using a "Hitachi 330 type self-recording spectrophotometer" (manufactured by Hitachi, Ltd.) with an OHP sheet bearing no toner as a reference.
The visible spectral transmittance of the solid toner image in the HP image was measured, and the difference in spectral transmittance between 650 nm and 450 nm for yellow toner, the difference in spectral transmittance between 650 nm and 550 nm for magenta toner, and the spectral transmittance between 500 nm and 600 nm for cyan toner. Was calculated and used as a measure of transparency. The temperature of the fixing roller was 170 ° C, 180 ° C, 190 ° C, and 200 ° C.

With respect to the fixing offset, the presence or absence of the occurrence of the fixing offset was visually judged.

[0074]

[Table 2]

It is clear from Table 2 that the OHP of the present invention has excellent transparency.

[0076]

The color toner of the present invention can maintain excellent OHP transparency, winding resistance, and offset resistance during fixing.

That is, in the present invention, by dispersing the pigment in an incompatible resin, it is possible to prevent the pigment from flowing out and prevent the primary particles of the pigment from coalescing. OH with excellent transparency that inhibits dissolution, does not cause winding, does not cause fixing offset
A P image can be formed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus.

FIG. 2 is an explanatory diagram of a fixing device used for fixing the color toner of the present invention.

[Explanation of symbols]

 2 fixing roller 3 image forming device 4 photoconductor drum 5 belt electrode 6 original 7 exposure lamp 13 developing device 13A visible image (toner image) 14 paper feed unit 16 transfer pole 17 separation pole 22A core material 24 fixing device P recording paper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 9/08 325 331 381

Claims (3)

[Claims] 1. A color toner for electrophotography, comprising at least a binder resin, a polyolefin wax, and a pigment dispersion resin, wherein a water-containing paste containing a pigment as the existing pigment dispersion resin is placed in a pigment dispersion resin solution. The SP value (SPb) of the binder resin is obtained by heating after mixing.
And the SP value (SPp) of the pigment-dispersing resin have the following relationship: 1.5 ≧ | SPp-SPb | ≧ 0.5 2. The pigment is 30 to 200 parts by weight with respect to 100 parts by weight of the pigment dispersing resin, and the ratio of the pigment dispersing resin in the entire color toner is 2 to 30% by weight. The described color toner for electrophotography. 3. The method of fixing a color toner for electrophotography according to claim 1, wherein the elasticity of the fixing roller has a hardness of 50 ° to 85 °.