JPH0915906A - Production of toner for developing electrostatic latent image - Google Patents

Abstract

PURPOSE: To obtain a toner giving a clear fine image by using a resin blend contg. a thermoplastic resin having functional groups capable of reacting with isocyanato groups and an org. polyisocyanate compd. CONSTITUTION: A resin blend contg. a thermoplastic resin having functional groups capable of reacting with isocyanato groups and an org. polyisocyanate compd. is kneaded, cooled, pulverized and classified. The resin binder has functional groups capable of reacting with isocyanato groups and the functional groups are, e.g. hydroxyl groups or carboxyl groups. Styrene-acrylic resin or polyester resin having hydroxyl groups and/or carboxyl groups in each molecule is preferably used. The styrene-acrylic resin is, e.g. a styrene-acrylic acid or n-butyl-acrylic acid copolymer. The polyester resin or styrene-acrylic resin preferably has 50-60 deg.C glass transition temp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner for developing an electrostatic latent image in an electrophotographic process, and more specifically, a method for producing a toner for developing an electrostatic latent image having both low temperature fixing property and anti-offset property. Regarding the method.

[0002]

2. Description of the Related Art In the electrophotographic process, a photoconductive photoconductor is charged in accordance with a pattern such as characters and figures, and this is exposed to form an electrostatic latent image. Then, the electrostatic latent image is formed. Is developed with a developer, the thus-obtained toner image is transferred to a paper or other substrate, and this is fixed by heating and / or pressure to obtain an image. Conventionally, various methods have been proposed and put to practical use for fixing such a toner image. Among them, a fixing method using a heat roller is widely adopted from the viewpoint of safety, thermal efficiency, and the like.

On the other hand, in recent years, in order to speed up the electrophotographic process, downsize the apparatus, and save energy, it is necessary to reduce the diameter of the roller and the capacity of the heater even in the fixing method using a heat roller. Therefore, there is a demand for a toner that can be fixed at a lower temperature than ever before.

To impart low temperature fixability to the toner, a resin having a low glass transition point or a resin having a low softening point may simply be used as the binder resin. However, according to such a method, the toner is During storage, toner particles adhere to each other and agglomerate to cause blocking, or so-called filming occurs in which toner is fused to a carrier or a photoconductor.

Therefore, for example, Japanese Patent Laid-Open No. 59-18534.
No. 8 and Japanese Patent Application Laid-Open No. 61-56352 propose a method of coating the surface of such toner particles with a polymer film by utilizing a microencapsulation technique. 54-28630, JP-A-61-56
No. 353, JP-A-61-56353, etc.
It has been proposed to fix inorganic or organic fine particles to the toner surface. However, in such a method, the processing is complicated, and the charge control of the obtained toner is insufficient and uncertain, so that a clear and beautiful copied image cannot be obtained.

As another method for obtaining a low-temperature fixing toner, a binder resin (or binder resin) of the toner has a molecular weight distribution consisting of a high molecular weight component and a low molecular weight component, and among them, the low molecular weight Using a resin containing a large amount of components is disclosed in, for example, JP-A-59-223453, JP-A-60-252361, and JP-A-60-2.
It is disclosed in Japanese Patent No. 52362. According to this method, the so-called sharp melt property of the toner is improved,
The toner is apt to cause blocking, and there is a limit as a measure for improving the low temperature fixing property. Further, in order to impart a sharp melting property to the toner, it is preferable to use a linear polyester resin which is a crystalline polymer, for example, as described in JP-A-5-58.
Although it is proposed in Japanese Patent Laid-Open No. 4-86342, there is a problem in offset property.

As described above, conventionally, there are various limitations in simultaneously providing the toner with the fixability at a low temperature and the anti-offset property at a high temperature. Therefore, in reality, the binder resin is appropriately cross-linked. The method of using the one is generally adopted. For example, JP-A-61-86760 discloses a crosslinked polyester resin obtained by reacting a polyvalent carboxylic acid component containing a trivalent or higher valent aromatic carboxylic acid with an etherified bisphenol, and then reacting an organic polyisocyanate. A toner for electrostatic latent image development has been proposed which uses as a binder resin. However, as described above, the resin cross-linked prior to the production of the toner is liable to cause the breakage of the molecular chain during the mixing and kneading with the other compound, and thus the toner thus obtained has a low temperature fixing property and a high temperature resistance. Both cannot be said to be sufficient in terms of offset property.

Therefore, for example, Japanese Patent Laid-Open No. 59-45451.
As described in Japanese Patent Publication No. JP-A-2003-264, a method of vulcanizing the binder resin with a vulcanizing agent when a binder resin containing a diene polymer is melt-kneaded with another compound in the production of a toner is proposed. Has been done. In addition, Japanese Patent Publication No. 59-33907 discloses a thermosetting acrylic resin or polyester resin having a crosslinkable functional group, a low molecular weight crosslinking agent such as diamine or dicarboxylic acid, or a crosslinking resin such as an isocyanate resin. A method has been proposed in which the binder resin is blended and melt-kneaded to crosslink the binder resin. However, according to these methods, if the binder resin is cross-linked to a level that satisfies offset resistance, on the contrary, the glass transition temperature rises and the low temperature fixability is impaired.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems in toner for developing an electrostatic latent image, and has a low fixing temperature and offset resistance. An object is to provide a toner that gives a clear and beautiful image.

[0010]

A method for producing a toner for developing an electrostatic latent image according to the present invention comprises kneading a resin blend containing a thermoplastic resin having a functional group capable of reacting with an isocyanate group and an organic polyisocyanate compound. And cooling, crushing, and classification.

In the present invention, the binder resin has a functional group capable of reacting with an isocyanate group, and examples of such a functional group include a hydroxyl group and a carboxyl group. Particularly, according to the present invention, a styrene-acrylic resin or polyester resin having a hydroxyl group and / or a carboxyl group in the molecule is preferably used.

The polyester resin used in the present invention is a linear polyester obtained by polycondensing a dihydric alcohol and a divalent carboxylic acid, or a polyhydric alcohol having a valence of 3 or more together with a dihydric alcohol and a divalent carboxylic acid. It is a non-linear polyester obtained by using an alcohol and / or a polycarboxylic acid.

Examples of the dihydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4- Diols such as butenediol, 1,4-bis (hydroxymethyl) cyclohexane,
Examples thereof include etherified bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneated bisphenol A, and the like.

Examples of the divalent carboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and naphthalene dicarboxylic acid, succinic acid, fumaric acid, adipic acid,
Maleic acid, sebacic acid, decamethylene dicarboxylic acid,
Aliphatic dicarboxylic acids such as mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, malonic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, etc. Examples thereof include dicarboxylic acids, acid anhydrides thereof, dimers of lower alkyl esters and linoleic acid, and the like.

Examples of the trihydric or higher polyhydric alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,
4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,
4-butanetriol, 1,2,5-pentanetriol,
Examples thereof include glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolbutane, trimethylolpropane and 1,3.5-trihydroxymethylbenzene.

Examples of the trivalent or higher polycarboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5, 7-naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 1,2,4-butane tricarboxylic acid, 1,2,5-hexane tricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene Carboxylpropane, tetra (methylenecarboxyl) methane, 1,2,7,8
Examples include octane tetracarboxylic acid, embol trimer, acid anhydrides or lower alkyl esters thereof, and the like.

Examples of the linear polyester resin include (poly) alkylene glycol and divalent carboxylic acid,
In particular, a resin obtained by polycondensation with an aliphatic dibasic acid having 4 to 20 carbon atoms, such as polyethylene sebacate,
Polyethylene adipate, polyethylene succinate,
Polyethylene-p- (carbophenoxy) undecaate, polyethylene-p- (carbophenoxy) butyrate, polyethylene-p-phenylene diacetate, polyhexamethylene carbonate, polyhexamethylene-p
-(Carbophenoxy) undecaate, polyhexamethylene oxalate, polyhexamethylene sebacate,
Polyhexamethylene decandioate, polyoctamethylene dodecanedioate, polynonamethylene azelate, polynonamethylene terephthalate, polydecamethylene adipate, polydecamethylene azelate, polydecamethylene oxalate, polydecamethylene sebacate,
Polydecamethylene succinate, polydecamethylene dodecanedioate, polydecamethylene octadecanedioate, polytetramethylene sebacate, polytetramethylene-p-phenylene diacetate, polytrimethylene dodecanedioate, polytrimethylene octadecanedioate , Polytrimethylene oxalate, poly-p-
Xylene adipate, poly-p-xylene sebacate,
Poly-4,4'-isopropylidene diphenylene adipate, poly-4,4'-isopropylidene phenylene malonate, polyhexamethylene decamethylene sebacate, polydecamethylene sebacate terephthalate, polydecamethylene-2-methyl -1,3-propanediol dodecanedioate etc. can be mentioned.

The styrene-acrylic resin used in the present invention can be obtained by copolymerizing a styrene monomer with a (meth) acrylic acid ester and, if necessary, (meth) acrylic acid.

Examples of the styrene-based monomer include
In addition to styrene, o-methylstyrene, p-methylstyrene, p-ethylstyrene, α-methylstyrene, 2,4
-Dimethyl styrene, pt-butyl styrene, pn
-Octyl styrene, pn-dodecyl styrene, p-
Methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and the like can be mentioned. Of these, styrene is preferably used.

Examples of the (meth) acrylic acid ester include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-acrylic acid.
Butyl, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, dimethylaminoethyl acrylate, acrylic Acrylic acid esters such as diethyl aminoethyl acid ester, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid. (Meth) acrylic acid esters such as 2-ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like can be mentioned.

As an example of the styrene-acrylic resin which can be preferably used in the present invention, there can be mentioned, for example, a styrene-n-butyl acrylate-acrylic acid copolymer. The glass transition point of the polyester resin or styrene-acrylic resin used in the present invention is preferably in the range of 50 to 60 ° C.

Next, the organic polyisocyanate used in the present invention may be any of aliphatic, aromatic, araliphatic or alicyclic, but it is a polyisocyanate compound having two or more functional groups, and particularly in the present invention. Has an isocyanate equivalent weight (molecular weight per isocyanate group) of 80
Those in the range of to 220 are preferably used. The molecular weight is preferably 1,000 or less, and particularly preferably about 150 to 800.

Examples of such organic polyisocyanates include aliphatic polyisocyanates such as hexamethylene diisocyanate (molecular weight 168, isocyanate equivalent weight 84), lysine diisocyanate (molecular weight 212, isocyanate equivalent weight 106), p-phenylene diisocyanate (molecular weight 160, isocyanate equivalent 8
0), tolylene diisocyanate (TDI, molecular weight 17
4, isocyanate equivalent 87), naphthylene diisocyanate (NDI, molecular weight 168, isocyanate equivalent 8)
4), tolidine diisocyanate (TODI, molecular weight 2
64, isocyanate equivalent 132), 4,4'-diphenylmethane diisocyanate (MDI, molecular weight 250, isocyanate equivalent 125), aromatic polyisocyanates such as polymeric MDI (average molecular weight 360 to 400, isocyanate equivalent 130 or less, Keiji Iwata "Plastics" Material Course 2 Polyurethane Resin ", pages 48-49 (published by Nikkan Kogyo Shimbun, 1978), xylylene diisocyanate (XDI, molecular weight 188, isocyanate equivalent 9
4), tetramethylxylylene diisocyanate (TM
Aroaliphatic polyisocyanates such as XDI, molecular weight 244, isocyanate equivalent 122), cyclohexyl diisocyanate (CHPI, molecular weight 166, isocyanate equivalent 83), hydrogenated xylylene diisocyanate (hydrogenated XDI, molecular weight 194, isocyanate equivalent 97), isopropylidene Bis (4-cyclohexyl isocyanate) (IPC, molecular weight 290, isocyanate equivalent 14
5), isophorone diisocyanate (IPDI, molecular weight 222, isocyanate equivalent weight 111), dicyclohexylmethane diisocyanate (HMDI, molecular weight 262,
Isocyanate equivalent 131) etc. can be mentioned.

Examples of trifunctional or higher functional organic polyisocyanates include triphenylmethane triisocyanate (commercially available Sumitomo Bayer Desmodur R, molecular weight 370, isocyanate equivalent 123), tris (p-isocyanatophenyl) thiophosphite. (Commercial item Sumitomo Bayer Desmodur RF, molecular weight 452, isocyanate equivalent 151), polyfunctional aromatic isocyanate (commercial item Takeda Yakuhin Coronate L, Sumitomo Bayer Sumidule L, Sumitomo Bayer Desmodule L, etc., molecular weight 6
56, an isocyanate equivalent 218), a polyfunctional aliphatic isocyanate (commercial product Sumitomo Bayer Sumidule N, molecular weight 504, isocyanate equivalent 168) and the like.

Such an organic polyisocyanate is usually used in an amount of 0.1 to 10 relative to 100 parts by weight of the binder resin.
It is used in parts by weight, preferably 0.2 to 5 parts by weight. According to the invention, in addition to the organic polyisocyanate and the colorant in the polyester resin or styrene-acrylic resin, if necessary, a charge control agent, a wax as an offset preventing agent, a magnetic powder, etc. are mixed, The toner for electrostatic latent image development can be obtained by kneading, then pulverizing and classifying.

As the colorant, any of those conventionally used in toners for developing electrostatic latent images can be used. Examples of such colorants include, for example, carbon black, nigrosine dye (CI No. 50415), aniline blue (CI No. 50405), calco oil blue (CI No.
azoic Blue 3), Chrome Yellow (CI No. 14090),
Ultramarine Blue (CI No. 77103), Dyupon Oil Red (CI No. 26105), Quinoline Yellow (C.
I. No. 47005), methylene blue chloride (CI No.
52015), phthalocyanine blue (CI No. 74160),
Malachite Green Oxalate (CI No. 42000),
Lamp black (CI No. 77266), rose bengal (CI No. 45435) and the like can be mentioned.

In addition to these, various organic or inorganic chromatic dyes and chromatic pigments can be used as a coloring agent. In particular, an organic material having a clear color and having excellent light resistance and hiding power. Chromatic pigments are preferably used. Examples of such chromatic color pigments include CI pigment red 5 (Permanent Carmine FB, Hoechst Japan Co., Ltd.), CI pigment red 48: 1 (Sumika Print Red C, Sumitomo Chemical Co., Ltd.), CI pigment red 53:
1 (Chromoftal Magenta G, Ciba Geigy),
CI Pigment Red 57: 1 (Sumika Print Carmine 6BC, Sumitomo Chemical Co., Ltd.), CI Pigment Red 123
(Kayasettsu EB, Nippon Kayaku), CI Pigment Red 139 (Kayasettsu E-GR, Nippon Kayaku), CI Pigment Red 144 (Chromoftal Red BRN, Ciba Geigy), CI Pigment Red 149 (PV Hua Stred B, Hoechst Japan), CI Pigment Red 166 (Chromoftal Scarlet R, Ciba Geigy), CI Pigment Red 177 (Chromoftal Red A38, Chiba Geigy) , CI Pigment Red 178 (Kayasetetsu E-GG, Nippon Kayaku Co., Ltd.), CI Pigment Red 2
22 (Chromoftal Red Magenta G, Ciba Geigy), CI Pigment Orange 31 (Chromoftal Orange 4R, Ciba Geigy), CI Pigment Orange 43 (Hosta Palm Orange GR, Hoechst), CI Pigment Yellow 17 (Fast Yellow GBFN, Sumitomo Chemical Co., Ltd.), CI Pigment Yellow 14
(Benzidine Yellow OT, Dupont), CI Pigment Yellow 138 (Variotor Yellow L0960
HD, Basuf), CI Pigment Yellow 93 (Chromoftal Yellow 3G, Ciba Geigy), CI Pigment Green 7 (Chromoftal Green GF, Ciba Geigy), CI Pigment Green 36 (Cyanine Green S537-2Y) , Dainichi Seika Co., Ltd., CI Pigment Blue 15: 3 (Cyanine Blue A330, Sanyo Pigment Co., Ltd.), CI Pigment Blue 60 (Chromoftal Blue A3R, Ciba Geigy), CI Pigment Violet 23 (Sumika Print Forst Bio) Lett RLN, Sumitomo Chemical Co., Ltd.) and the like.

If necessary, red iron oxide, titanium oxide, carbon black and the like may be used in combination with the above-mentioned coloring agent. Examples of chromatic dyes include azo dyes, anthraquinone dyes, indigoid dyes, quinone imine dyes, and phthalocyanine dyes. These colorants may be used alone, or
Two or more kinds may be used in combination. The colorant is usually used in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the binder resin. Further, when a magnetic toner is obtained, coloring magnetic powder can be used as a coloring agent.

As the charge control agent, any charge control agent conventionally used in toners for developing electrostatic latent images can be used.
As a negatively chargeable charge control agent, JP-A-57-1414 is known.
52, JP-A-58-7645, JP-A-58
-1111049, JP-A-58-185653, JP-A-57-167033, JP-B-44-6.
2: 1 type metal-containing azo dyes such as those described in JP-A No. 397 and the like, for example, JP-A-57-104940, JP-A-57-111541, and JP-A-57-12435.
No. 7, JP-A-53-127726, and the like, metal complexes of aromatic oxycarboxylic acids and aromatic dicarboxylic acids, for example, as described in JP-A-52-45931. Examples thereof include sulfonylamine derivatives of copper phthalocyanine dyes and sulfonamide derivative dyes of copper phthalocyanine.

Examples of the positively chargeable charge control agent include, for example, JP-A-49-51951 and JP-A-52-1.
Quaternary ammonium compounds such as those described in JP-A-0141, etc., for example, JP-A-56-11461, JP-A-54-158932, and US Pat.
54,205 alkylpyridinium compounds such as those described in the specification, alkylpicolinium compounds,
Various nigrosine dyes and the like can be mentioned.

Such a charge control agent is used in an amount of 0.1 to 10 parts by weight, particularly 0.3 in relation to 100 parts by weight of the binder resin.
It is preferably in the range of up to 5 parts by weight. As the offset preventing agent, for example, various waxes having a melting point in the range of 50 to 150 ° C. can be preferably used. Specifically, for example, liquid or solid paraffin, polyolefin wax such as polyethylene and polypropylene, aliphatic metal salt, fatty acid ester, partially saponified fatty acid ester, higher fatty acid, higher alcohol, silicone varnish, amide wax, aliphatic wax Examples thereof include fluorocarbons and modified products thereof.

Such an offset preventing agent is usually used in an amount of 0.1 to 30 parts by weight, particularly 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin. According to the present invention, as described above, the organic polyisocyanate and the colorant are added to the binder resin, and if necessary, a charge control agent, an anti-offset agent, magnetic powder and the like are mixed to obtain a blended product. 100 to 140 ° C., preferably
After kneading at a temperature in the range of 110 to 130 ° C., pulverizing,
A toner for developing an electrostatic latent image can be obtained by classifying into a required average particle size.

[0033]

As described above, according to the present invention, in the production of a toner, the organic polyisocyanate not only cross-links the binder resin with each other, but the isocyanate group of the organic polyisocyanate is different from that of other organic or inorganic substances. Since it easily reacts with the hydroxyl group or carboxyl group of the substance, for example, organic polyisocyanate forms a cross-link between the binder resin and the particles of the colorant or the charge control agent,
Also, crosslinks are formed between particles of the colorant and the charge control agent, and thus, in the toner particles, not only the binder resin but also the particles of the colorant and the charge control agent are at least partially bonded through the organic polyisocyanate. Since they are interconnected with each other, the melting temperature of the high temperature side of the obtained toner can be maintained high while effectively suppressing the increase of the glass transition temperature of the binder resin, and at the high temperature while securing the low temperature fixability. The offset resistance of can be improved.

[0034]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

Example 1 Styrene having a glass transition temperature of 57 ° C.-butyl acrylate-
As shown in Table 1, in the acrylic acid copolymer, carbon black (“Dia Black # 2” manufactured by Mitsubishi Chemical Co., Ltd.) was used.
350 "), a charge control agent (Hodogaya Chemical Co., Ltd. metal-containing pigment" Spiron Black TRH "), an anti-offset agent (Sanyo Chemical Co., Ltd. polypropylene wax" Viscole 550P "), and an organic polyisocyanate ( M
DI) was mixed and kneaded with a twin-screw extruder at 120 ° C., then cooled, pulverized and classified to obtain a toner. Table 1 shows the temperature characteristics and fixing characteristics of this toner.

Example 2 As shown in Table 1, carbon black (“Diablack # 2350” manufactured by Mitsubishi Chemical Co., Ltd.), a charge control agent (Orient Chemical Co., Ltd.) was added to a polyester resin having a glass transition temperature of 55 ° C. ) Metal-containing pigment "Bontron S-3
4 ”), an anti-offset agent (polypropylene wax“ Viscor 550P ”manufactured by Sanyo Kasei Co., Ltd.) and a polyfunctional polyisocyanate (Desmodur L) are mixed,
After kneading with a twin-screw extruder at 120 ° C., it was cooled, pulverized, and classified to obtain a toner. Table 1 shows the temperature characteristics and fixing characteristics of this toner.

Example 3 A polyester resin having a glass transition temperature of 53 ° C., as shown in Table 1, carbon black colorant (“Dia Black MA-100” manufactured by Mitsubishi Chemical Co., Ltd.) and a charge control agent (Orient Chemical ( Co., Ltd. metal-containing pigment "Bontron N-0"
7 "), an anti-offset agent (polypropylene wax" Viscole 660P "manufactured by Sanyo Kasei Co., Ltd.) and an organic polyisocyanate (TDI) are mixed and kneaded at 115 ° C in a twin-screw extruder, and then cooled. It was crushed and classified to obtain a toner. Table 1 shows the temperature characteristics and fixing characteristics of this toner.

Comparative Example 1 A toner was obtained in the same manner as in Example 1 except that organic polyisocyanate was not used as a compounding agent. Table 1 shows the temperature characteristics and fixing characteristics of this toner.

Comparative Example 2 A toner was obtained in the same manner as in Example 2 except that organic polyisocyanate was not used as a compounding agent. Table 1 shows the temperature characteristics and fixing characteristics of this toner.

Comparative Example 3 A toner was obtained in the same manner as in Example 3 except that organic polyisocyanate was not used as a compounding agent. Table 1 shows the temperature characteristics and fixing characteristics of this toner.

Comparative Example 4 As shown in Table 1, a polyester resin having a glass transition temperature of 65 ° C. was colored with carbon black (“Dia Black # 2350” manufactured by Mitsubishi Chemical Co., Ltd.) and a charge control agent (Hodogaya Chemical Co., Ltd.). Metal-containing pigment "Spiron Black TR"
H ") and an offset preventive agent (polypropylene wax" Viscor 550P "manufactured by Sanyo Chemical Industry Co., Ltd.) are mixed and kneaded at 120 ° C in a twin-screw extruder, and then cooled.
It was crushed and classified to obtain a toner. Table 1 shows the temperature characteristics and fixing characteristics of this toner.

The compounding agents shown in Table 1 were mixed with a polyester resin having a glass transition temperature of 65 ° C., and the mixture was mixed with a twin-screw extruder at 120 ° C.
After kneading, the mixture was cooled, pulverized and classified to obtain a toner. Table 1 shows the temperature characteristics and fixing characteristics of this toner.

[0043]

[Table 1]

The temperature characteristic and the fixing characteristic of the toner were measured as follows. A drop-type flow tester CFT-500 manufactured by Shimadzu Corporation was used to heat 1.5 g of the sample to a heating rate of 2.0 ° C.
/ Min, load 10 kg, die length 1 mm, diameter 1 mm, measure the position of the plunger with respect to temperature, and melt the toner, the temperature at which the plunger starts to drop from the reference position 0 mm is the melting start temperature. In addition, the temperature when the plunger is lowered by 4 mm from the reference position 0 mm as the toner is melted is defined as 4 mm drop temperature.

An unfixed image having a solid portion was sampled using a commercially available copying machine, and the image was fixed through a fixing tester set to a predetermined condition, where an offset phenomenon started to occur on the high temperature side. This temperature was defined as the high temperature offset generation temperature. The minimum fixing temperature is the lower limit temperature at which the fixing strength is 90% or more. The fixing strength (%) is obtained by measuring the image density of a solid portion at 5 points and then rubbing the portion under predetermined conditions. The image density was measured again and determined from (image density after rubbing) / (image density before rubbing) × 100.

Claims (4)

[Claims] 1. An electrostatic latent image characterized by kneading, cooling, pulverizing and classifying a resin blend containing a thermoplastic resin having a functional group capable of reacting with an isocyanate group and an organic polyisocyanate compound. Method for producing developing toner. 2. The method for producing a toner for developing an electrostatic latent image according to claim 1, wherein the thermoplastic resin is a polyester resin or a styrene-acrylic resin. 3. The method for producing a toner for developing an electrostatic latent image according to claim 2, wherein the thermoplastic resin has a glass transition point in the range of 50 to 60 ° C. 4. An organic polyisocyanate having a molecular weight of 150 to
Having an isocyanate equivalent of 80 to 22
The method for producing a toner for developing an electrostatic latent image according to claim 1, having 0.