JPH10307419A - Electrophotographic toner and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner which can be fixed at low temp. by thermal fixing method and which sufficiently prevents from generating an offset and can form an OHP image with excellent transparency, and to provide its producing method. SOLUTION: This electrophotographic toner contains a thermoplastic resin, coloring agent and release agent, and further a rosin ester. Preferably the resin ester has 70 to 120 deg.C softening point, 60 to 2000 cPs melt viscosity at 150 deg.C and 5 to 60 cPs melt viscosity at 200 deg.C. The release agent and/or the coloring agent are preliminarily dispersed with the rosin ester, and then other components are added and mixed. The mixture is kneaded, pulverized and classified to produce the electrophotographic toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner for developing an electric latent image in an electrophotographic method or an electrostatic recording method, and more particularly to an electrophotographic toner suitable for forming a color image. .

[0002]

2. Description of the Related Art In an electrophotographic system in which a visible image is formed by developing an electric latent image with a developer, an electric latent image is formed on a photoconductor made of a photoconductive material, and then the latent image is developed. After forming a toner image by developing with a developer, the toner image is transferred to paper or the like, if necessary, and fixed by heating, pressing, or the like to obtain a visible image. In the electrophotographic method of forming a color image, an original is exposed using a color separation filter, or an image read by a scanner is written and exposed by a laser to form an electric latent image of, for example, a yellow image portion on a photoreceptor. After forming the latent image with a developer containing a yellow toner to form a yellow toner image, the yellow toner image is transferred and fixed on paper or the like, and then a magenta toner image, a cyan toner A color image is obtained by sequentially superimposing and fixing images. In recent years, there has been a demand for higher image quality, higher speed, smaller size, and higher reliability in such electrophotographic image formation, and development is proceeding in this direction.
In particular, in the formation of color images, it is necessary to widen the range of color reproducibility with high resolution. Therefore, the softening temperature of the color toner is lowered, the melt viscosity is lowered, and the color mixing of two or more color toners is improved. The device has been improved.

However, toner having such thermal characteristics tends to be easily offset to a fixing roller such as a heating roll during heating and fixing. A method of applying a release oil such as oil, or JP-A-50-144446, JP-A-60-123856
JP, JP-A-1-109360, JP-A-3-5-5
764, JP-A-4-9067, JP-A-4-9067
As disclosed in US Pat. No. 2,230,769 and Japanese Patent Application Laid-Open No. H8-50367, various methods of incorporating various release agents into toner have been performed.

However, in the former method, the fixing device is provided with an oil application device, so that the fixing device is complicated, and furthermore, there is a problem that an odor due to the release oil is generated at the time of fixing. In the latter method, filming occurs on the surface of the photoreceptor, the carrier in the developer and the surface of the developing sleeve are easily contaminated, and the toner using a resin having a low melt viscosity can sufficiently prevent the occurrence of the offset phenomenon. Can not be prevented. Further, in the toner to which the release agent is added, the release agent is not sufficiently finely dispersed, and when a toner image is formed on a film for an overhead projector (OHP) using the toner, the transparency of the OHP image is reduced. There is a problem of doing.

[0005]

Accordingly, an object of the present invention is to solve such a problem and to provide an OHP which can be fixed at a low temperature in a heat fixing method, sufficiently prevents the occurrence of an offset phenomenon, and has excellent transparency. An object of the present invention is to provide an electrophotographic toner capable of forming an image.

[0006]

An object of the present invention is to provide an electrophotographic toner containing a thermoplastic resin, a colorant and a release agent, wherein the toner further contains a rosin ester. Achieved by photographic toner. ADVANTAGE OF THE INVENTION According to the electrophotographic toner of this invention, it can fix at a lower temperature than before by the heat fixing method, can fully prevent the occurrence of an offset phenomenon, and can form an OHP image excellent in transparency.

The rosin ester used in the present invention is obtained by esterifying the carboxylic acid of rosin with a monohydric or dihydric alcohol. In particular, in order to exhibit good low-temperature fixability and toner transparency, The softening point of the rosin ester is preferably from 70 ° C to 120 ° C, and the melt viscosity of the rosin ester at 150 ° C is from 60 cps to 2000 cps,
Is preferably 5 cps to 60 cps. The softening point of the rosin ester mainly contributes to low-temperature fixability, and the melt viscosity of the rosin ester mainly contributes to toner transparency.

Further, since rosin ester has good compatibility with thermoplastic resin and is also compatible with release agent, rosin ester acts as a compatibilizer, and releasing agent and colorant are contained in thermoplastic resin. By forming a color image using a toner containing a rosin ester which can be finely dispersed, transparency and chroma of the color image can be improved. The amount of rosin ester used is thermoplastic resin,
It varies depending on the type of the colorant and the release agent, the method of adding the rosin ester, and the like, but is preferably 2 to 30 parts by weight per 100 parts by weight of the thermoplastic resin.

As the thermoplastic resin, conventionally known thermoplastic resins can be used, such as styrene, parachlorostyrene, vinyltoluene, vinyl chloride, vinyl acetate, vinyl propionate, methyl (meth) acrylate, ethyl (meth) acrylate, and the like. Propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth)
Dodecyl acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-chloroethyl (meth) acrylate,
(Meth) acrylonitrile, (meth) acrylamide,
Polymers of monomers such as (meth) acrylic acid, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl methyl ketone, N-vinyl pyrrolidone, N-vinyl pyridine, butadiene, or 2 of these monomers Copolymers composed of more than one kind, and mixtures thereof, etc., are mentioned. In addition, polyester, polyurethane, polyamide, epoxy resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, and the like can also be used.

The thermoplastic resin is preferably a polycondensation resin, in order to exhibit low-temperature fixability and prevent the occurrence of an offset phenomenon, and particularly preferably has a molecular weight (MW) of 1
Polycondensation resin of 20,000 to 20,000 and molecular weight (MW)
A mixed system of 80,000 to 150,000 polycondensation resins is preferred.

As the polycondensation resin, a polyester resin having a crosslinked structure is preferable.
A polyester resin containing a carboxylic acid having a valency of 3 or more, an acid anhydride thereof, a lower alkyl ester and / or an alcohol having a valency of 3 or more is preferred. Examples of such a polyester resin include polycondensates of a polyethylene adduct of bisphenol A or an ethylene oxide adduct of bisphenol A with terephthalic acid, succinic acid, trimellit anhydride, and the like.

As the colorant, black pigments such as carbon black (oil furnace black, channel black, lamp black, acetylene black, etc.), azine dyes such as aniline black, metal salt azo dyes,
Metal oxides, composite metal oxides and the like, as yellow pigments cadmium yellow, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G,
Benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, tartrazine lake, etc. are molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant as clear pigments. Orange GK etc. are red pigments such as Bengala, Cadmium Red, Permanent Red 4R, Risor Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B etc. But violet pigments such as Fast Violet B and Methyl Violet Lake, and blue pigments such as cobalt blue , Alkaline Blue, Victoria Blue Lake, Phthalocyanine Blue, Metal-Free Phthalocyanine Blue, Partial Chlorinated Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue BC, etc. as Green Pigments Chrome Green, Chromium Oxide, Pigment Green B, Malachite Green Lake And the like, and these can be used alone or as a mixture of two or more. The use amount of these coloring agents is preferably about 1 to 15% by weight based on the thermoplastic resin.

The releasing agent used in the present invention includes low molecular weight polyethylene, low molecular weight polypropylene,
Polyethylene oxide, Fischer-Tropsch wax, beeswax, carnauba wax, montan wax, paraffin wax, higher alcohols, stearic acid, palmitic acid, myristic acid, metal salts of higher fatty acids, higher fatty acid amides, higher esters, etc. These may be used alone or in combination of two or more.
Polyethylene, polypropylene, Fischer-Tropsch wax and carnauba wax are preferred. The amount of the release agent used is preferably about 1 to 10% by weight based on the thermoplastic resin.

Further, the electrophotographic toner of the present invention includes:
The following charge control agents can be used to control charging. That is, any of conventionally known charge control agents can be used, for example, nigrosine, C 2 to C 1
Azine dyes containing 6 alkyl groups (JP-B-42-16)
No. 27), basic dyes (for example, CI Basi)
c Yellow 2 (CI.41000), C.I. I.
Basic Yellow 3, C.I. I. BasicRe
d 1 (CI. 45160), C.I. I. Basic R
ed 9 (CI. 42500), C.I. I. Basic
Violet 1 (CI. 42535), C.I. I. B
asic Violet 3 (CI. 42555),
C. I. Basic Violet 10 (CI.45)
170), C.I. I. Basic Violet 14
(CI. 42510), C.I. I. Basic Blu
e1 (CI. 42025), C.I. I. Basic B
1ue 3 (CI. 50005), C.I. I. Basi
c B1ue 5 (CI. 42140), C.I. I. Ba
sicB1ue 7 (CI. 42595), C.I. I.
Basic B1ue 9 (CI. 52015), C.I.
I. Basic B1ue 24 (CI. 5203)
0), C.I. I. Basic B1ue 25 (CI.5
2025), C.I. I. Basic B1ue 26 (C.I.
I. 44045), C.I. I. Basic Green1
(C.I. 42040), C.I. I. Basic Gre
en 4 (C.I. 42000), and lake pigments of these basic dyes; I. SolventB1ac
k8 (C.I. 26150), quaternary ammonium salts such as benzoylmethyl-hexadecyl ammonium chloride and decyltrimethyl chloride, dialkyltin compounds such as dibutyl or dioctyl, dialkyltin borate compounds, guanidine derivatives and amino groups Polyamine resins such as vinyl polymers, amino group-containing condensation polymers, or JP-B Nos. 41-20153, 43-27596, 44-6397, and 45-26478. Gold complex salts of monoazo dyes, which are disclosed in
Salicylic acid described in JP-A-59-7385,
Z of dialkylsalicylic acid, naphthoic acid and dicarboxylic acid
Examples include metal complexes such as n, Al, Co, Cr, and Fe; sulfonated copper phthalocyanine pigments; and fluorine-based compounds described in JP-A-4-151168.

As a method for producing the electrophotographic toner of the present invention, a method for producing an electrophotographic toner by mixing a rosin ester with a thermoplastic resin, a colorant, a release agent, etc., kneading, pulverizing and classifying the toner. Alternatively, a release agent and a rosin ester, a colorant and a rosin ester, or a colorant and a release agent and a rosin ester are dispersed in advance, and other components are added thereto, mixed, kneaded, pulverized, classified, and then dispersed. By manufacturing a photographic toner, a colorant and a release agent can be easily finely dispersed.

To previously disperse the release agent and the rosin ester, or the colorant and the rosin ester, or the colorant, the release agent and the rosin ester, knead them with a two or three rolls under heating, or mix What is necessary is just to add the solvent above the softening temperature or a trace amount, and to disperse it with an attritor or a homogenizer. As the particle size of the electrophotographic toner thus manufactured, the volume average particle size is 4 to 10 μm.
m is preferable.

Further, the method for producing the electrophotographic toner of the present invention includes the step of suspending a polymerizable monomer having an ethylenic double bond in the presence of a polymerization initiator together with a colorant, a release agent, a rosin ester, and the like. The polymerization method is also preferable, and a polymerization toner in which a colorant and a release agent are finely dispersed can be obtained by this method. The volume average particle diameter of the polymerized toner is particularly preferably about 4 to 7 μm. By using the electrophotographic toner of the present invention in which the colorant and the release agent are finely dispersed in this manner, the OHP having higher transparency can be obtained.
An image can be formed.

[0018]

The present invention will be described below with reference to examples.

Example 1 100 parts by weight of styrene / n-butyl methacrylate (60/40) copolymer, 10 parts by weight of carbon black, 5 parts by weight of low molecular weight polypropylene, 5 parts by weight of chromium-containing azo dye and rosin ester (softening point 102 ° C, melt viscosity 1
072 cps (150 ° C), 48 cps (200 ° C))
The mixture consisting of 10 parts by weight was heated and kneaded with a hot roll, pulverized and classified to obtain a black toner having a volume average particle diameter of 9 μm. 0.3 parts by weight of colloidal silica was added to and mixed with 100 parts by weight of the toner, and 3 parts by weight of the toner was mixed with 100 parts by weight of an iron powder carrier to produce a two-component developer. This developer was put into a magnetic brush developing device, and the electrostatic latent image formed on the organic photoreceptor was developed by a usual electrophotographic method, and transferred to plain paper while applying corona discharge. When this transferred image was thermally fixed by a fixing roller not supplying silicone oil, the fixing temperature was 130 to 210.
There was no occurrence of paper wrapping or offset phenomenon in the range of ° C, and a good fixed image was obtained. Also, the above toner is
The toner was stored in a constant temperature bath at a temperature of 1 ° C. for 1 week, but no fusion of the toner was observed, and the blocking resistance of the toner was good.

Example 2 100 parts by weight of a styrene-methyl acrylate copolymer,
10 parts by weight of copper phthalocyanine, 5 parts by weight of low molecular weight polypropylene, 5 parts by weight of zinc 3,5-di-tert-butylsalicylate and rosin ester (softening point 83 ° C., melt viscosity 90 cps (150 ° C.), 8.5 cps (200
C)) A mixture consisting of 7 parts by weight was heated and kneaded with a hot roll, pulverized and classified to obtain a cyan toner having a volume average particle diameter of 8 μm. 0.3 parts by weight of colloidal silica was added to and mixed with 100 parts by weight of the toner, and 3 parts by weight of the toner was mixed with 100 parts by weight of an iron powder carrier to produce a two-component developer. This developer was set in the same apparatus as in Example 1, and the transferred image transferred in the same manner as in Example 1 was converted into a
When fixing was performed at each temperature in the same manner as in Example 1 except that the fixing temperature was increased by 10 ° C. from 210 ° C. to 210 ° C.
A clear image was obtained without offset phenomenon or paper wrapping. The toner was stored in a thermostat at 50 ° C. for one week, but no fusion of the toner was observed, and the blocking resistance of the toner was good.

Example 3 Polyester resin (polyoxyethylene (2.2)-
Condensed polymer composed of 2,2-bis (4-hydroxyphenyl) propane, terephthalic acid and trimellitic anhydride)
100 parts by weight, copper phthalocyanine 2 parts by weight, carnauba wax 5 parts by weight, 3,5-di-tert-butyl zinc zincate 5 parts by weight, and rosin ester (softening point 8
3 ° C, melt viscosity 90 cps (150 ° C), 8.5 cps
(200 ° C.) A mixture consisting of 10 parts by weight was heated and kneaded with a hot roll, pulverized and classified to obtain a toner having a volume average particle diameter of 7 μm. 0.3 parts by weight of colloidal silica is added to and mixed with 100 parts by weight of the toner, and 3 parts by weight of the toner is mixed with 100 parts by weight of an iron powder carrier to form a two-component developer. An image was formed.
As a result of a fixing test in the fixing temperature range of 130 ° C. to 210 ° C. in the same manner as in Example 1, a cyan image having excellent dot reproducibility without offset phenomenon or paper wrapping was obtained. The haze value of the copied image transferred to the polyester film was 16.8, which was excellent in transparency.

Example 4 Molecular weight (MW) in place of the polyester resin of Example 3
30 parts by weight of 12000 polyester resin and MW950
A toner having a volume average particle diameter of 7 μm was obtained in the same manner as in Example 3 except that 70 parts by weight of the polyester resin No. 00 was used. Using this toner, 130 ° C. to 2
As a result of performing a fixing test in a fixing temperature range of 10 ° C., a cyan image excellent in dot reproducibility without an offset phenomenon or paper wrapping was obtained. The haze value of the copied image transferred to the polyester film was measured and found to be 16.2, which was excellent in transparency.

Example 5 8 parts by weight of 3 parts by weight of Fischer-Tropsch wax and 5 parts by weight of rosin ester melted and mixed, 100 parts by weight of the resin used in Example 4, 3 parts by weight of quinacridone magenta pigment and 3 parts by weight And 5 parts by weight of zinc 5-di-tert-butylsalicylate were heated and kneaded in the same manner as in Example 1, pulverized and classified to obtain a toner having a volume average particle diameter of 7 μm. Using this toner, 130 ° C.
As a result of performing a fixing test in a fixing temperature range of 210 ° C., a magenta image having excellent dot reproducibility without an offset phenomenon or paper wrapping was obtained. When the haze value of the copied image transferred to the polyester film was measured, it was 13.8.
And excellent in transparency.

Example 6 3 parts by weight of quinacridone magenta pigment and rosin ester 1
0 parts by weight, 2 parts by weight of toluene were added and melted by heating, and 100 parts by weight of the resin used in Example 4, 5 parts by weight of carnauba wax, and zinc 3,5-di-tert-butylsalicylate were used. 5 parts by weight were heated and kneaded in the same manner as in Example 1, pulverized and classified to obtain a toner having a volume average particle diameter of 7 μm. 13 using this toner in the same manner as in Example 1.
As a result of performing a fixing test in a fixing temperature range of 0 ° C. to 210 ° C., a magenta image excellent in dot reproducibility without offset phenomenon or paper wrapping was obtained. The haze value of the copied image transferred to the polyester film was measured and found to be 14.3, which was excellent in transparency.

Example 7 A mixture of 3 parts by weight of quinacridone magenta pigment, 5 parts by weight of carnauba wax and 5 parts by weight of rosin ester mixed with 100 parts by weight of the resin used in Example 4 and 3,5- 5 parts by weight of zinc di-tert-butylsalicylate was heated and kneaded in the same manner as in Example 1, ground and classified to obtain a toner having a volume average particle diameter of 7 μm. As a result of performing a fixing test using this toner in a fixing temperature range of 130 ° C. to 210 ° C. in the same manner as in Example 1, a magenta image having excellent dot reproducibility without an offset phenomenon or paper wrapping was obtained. When the haze value of the copied image transferred to the polyester film was measured, it was 13.3, which was excellent in transparency.

COMPARATIVE EXAMPLE 1 Instead of 5 parts by weight of carnauba wax and 5 parts by weight of rosin ester of Example 7, only 5 parts by weight of carnauba wax was used in place of the hot-melted mixture. Similarly, a toner having a volume average particle diameter of 7 μm was obtained. 130 ° C. to 210 ° C. using this toner in the same manner as in Example 7.
As a result of performing a fixing test in a fixing temperature range of
Offset occurred in the range of 210 ° C. When the haze value of the copied image transferred to the polyester film was measured, it was 32.5 and was inferior in transparency.

Example 8 50 parts by weight of styrene and 50 parts of n-butyl acrylate
2 parts by weight of azobisisobutylnitrile dissolved in parts by weight, rosin ester (softening point: 83 ° C., melt viscosity: 90
5 parts by weight of cps (150 ° C., 8.5 cps (200 ° C.)) and 5 parts by weight of carnauba wax previously melt-mixed, 3 parts by weight of zinc 3,5-di-tert-butylsalicylate, and copper phthalocyanine 1.5 parts by weight of the pigment was dispersed in an aqueous polyvinyl alcohol solution using a homogenizer, suspension polymerization was performed at 80 to 90 ° C. for 10 hours, centrifuged, washed with water, filtered and dried, and the volume average particle diameter was 6 μm.
Was obtained. A developer was prepared using this toner in the same manner as in Example 1, and a fixing test was carried out. As a result, a clear cyan image having good spectral characteristics without an offset phenomenon or paper wrapping was obtained. 13. The haze value of the copied image transferred to the polyester film was measured.
6 was excellent in transparency.

[0028]

According to the toner for electrophotography of the present invention, the fixing can be performed at a low temperature in the heat fixing method, the occurrence of an offset phenomenon can be sufficiently prevented, and an OHP image having excellent transparency can be formed. Further, the electrophotographic toner of the present invention has excellent storage stability without toner blocking,
Further, the transparency of the color toner is particularly good.

Claims (15)

[Claims] 1. An electrophotographic toner comprising a thermoplastic resin, a colorant and a release agent, wherein the toner further contains a rosin ester. 2. The rosin ester has a softening point of 70 ° C. to 12 ° C.
2. The electrophotographic toner according to claim 1, wherein the temperature is 0.degree. 3. The electrophotographic toner according to claim 1, wherein the rosin ester has a melt viscosity at 150 ° C. of 60 cps to 2000 cps and a melt viscosity at 200 ° C. of 5 cps to 60 cps. 4. The electrophotographic toner according to claim 1, wherein the rosin ester is contained in an amount of 2 to 30 parts by weight per 100 parts by weight of the thermoplastic resin. 5. The electrophotographic toner according to claim 1, wherein the thermoplastic resin is a condensation polymerization resin. 6. The thermoplastic resin has a molecular weight (MW) of 1000.
Polycondensation resin of 0 to 20,000 and molecular weight (MW) of 800
6. The toner for electrophotography according to claim 1, wherein the toner contains from 0.001 to 150,000 polycondensation resins. 7. The electrophotographic toner according to claim 5, wherein the polycondensation resin is a polyester resin having a crosslinked structure. 8. A polyester resin having a crosslinked structure,
8. The electrophotographic toner according to claim 7, wherein the raw material monomer contains a tri- or higher carboxylic acid or an acid anhydride thereof, a lower alkyl ester and / or a tri- or higher valent alcohol. 9. The method according to claim 1, wherein the release agent is carnauba wax, polyethylene, polypropylene, Fischer-Tropsch wax.
6. The electrophotographic toner according to 6, 7, or 8. 10. The method according to claim 1, wherein the release agent and / or the colorant are finely dispersed.
The toner for electrophotography according to 5, 6, 7, 8 or 9. 11. A method for producing an electrophotographic toner, comprising dispersing a release agent and a rosin ester in advance, adding at least a thermoplastic resin and a colorant, mixing, kneading, pulverizing, and classifying. 12. A method for producing an electrophotographic toner, comprising dispersing a colorant and a rosin ester in advance, adding at least a thermoplastic resin and a release agent, mixing, kneading, pulverizing, and classifying. 13. A method for producing an electrophotographic toner, comprising dispersing a release agent, a colorant and a rosin ester in advance, adding at least a thermoplastic resin thereto, mixing, kneading, pulverizing and classifying. 14. A method for producing an electrophotographic toner, wherein suspension polymerization is carried out using a composition containing a polymerizable monomer, a colorant, a release agent, a rosin ester and a polymerization initiator. 15. The method for producing an electrophotographic toner according to claim 14, wherein the volume average particle diameter of the electrophotographic toner is 4 to 7 μm.