JP2002296832A - Binder resin for toner and electrostatic charge image developing electrophotographic toner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder resin for a toner having good electrostatic property, low temperature fixability and blocking resistance and to provide a toner. SOLUTION: The toner having good characteristics is obtained by using a resin based on a polyester resin having 1.21-1.30 g/cm<3> density, a number average molecular weight of 1,500-20,000 and 45-75 deg.C glass transition temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner used for developing an electrostatic image in electrophotography, electrostatic printing, and the like, and more particularly to fixing properties, blocking resistance, and environmental stability. Are good, and in particular, they relate to an electrophotographic toner having excellent hot offset resistance and durability.

[0002]

2. Description of the Related Art With the development of office automation, the demand for copying machines and laser printers using electrophotography has been rapidly increasing, and the demands for their performance have also become more sophisticated. In general, in order to obtain a visible image using electrophotography, a photosensitive member such as selenium, amorphous silicon, or an organic semiconductor is charged, exposed, developed using a developer containing a toner, and formed on the photosensitive member. A method has been adopted in which the formed toner image is transferred to transfer paper and then fixed using a heat roll or the like. At this time, it is needless to say that a developed image has no fog and a clear image having a sufficient image density needs to be formed.
From the viewpoint of high speed, energy saving, and improvement of safety, maintenance-free and high durability are strongly demanded, and toners having excellent low-temperature fixability are also demanded. In order to improve the fixability of the toner, it is generally necessary to reduce the viscosity of the toner at the time of melting to increase the adhesion area with the fixing base material. Therefore, the glass transition point (Tg) of the conventionally used toner binder resin is required. Or to reduce the molecular weight. However, resins having a low glass transition point generally have poor blocking resistance, so that it is difficult to stably exist as a powder during use or storage of the toner. When the image is fixed by the hot roll fixing method, the hot roll and the toner in a molten state are in direct contact with each other at the time of fixing, but at this time the toner transferred onto the hot roll stains transfer paper and the like to be sent next, There is a disadvantage that a so-called offset phenomenon is likely to occur. This tendency is more pronounced when the molecular weight of the resin is smaller.

In recent years, a digital system capable of outputting information from a computer or a facsimile has been spotlighted as an image forming system in the electrophotographic system. In the digital exposure, a laser is used as an exposure means, so that a fine line drawing can be output as compared with the conventional analog method, and a toner having a small particle size is required to obtain a more delicate image. However, when the particle size of the toner is reduced, if the resin strength, that is, the powder is easily crushed, the amount of fine powder generated during the production increases, the production yield drops significantly, and the cost increases, which is not preferable. Further, fine particles are liable to be generated during stirring with the carrier in the copying machine, and the carrier is contaminated, which causes unstable charge amount and fog.

[0004] Further, with the speeding up of copiers and printers, the speeding up of charged parts has been progressing in order to speed up the rise of charging. Accordingly, in the two-component developing method, the friction speed between the toner and the carrier increases, and in the one-component developing method, the friction speed between the toner and the charging blade increases. That is, higher durability is required for the toner. Under such circumstances, various toners using a higher-density polyester resin as a binder resin in place of a styrene-acrylic resin that has been conventionally mainly used have been proposed (for example, Japanese Patent Application Laid-Open No. 61-284773). , JP 6
JP-A-2-291668, JP-B-7-101318, JP-B8-3663, U.S. Pat.
3,057, etc.). However, in many cases, the main components are a bisphenol A derivative and terephthalic acid, and a toner using a polyester resin having a large amount of terephthalic acid and ethylene glycol or 1,4-butanediol in the resin skeleton (Japanese Patent Publication No. Hei 8-8). 5947), but the toner obtained from these has not yet satisfactorily solved the above problems.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to provide an electrophotographic toner for electrostatic charge development which does not have the above-mentioned conventional problems and satisfies the above-mentioned various characteristics which have been conventionally required for the toner. Things. That is, an object of the present invention is to provide a binder resin for a toner, which has good chargeability, low-temperature fixability, fixability, and blocking resistance, and an electrophotographic toner for electrostatic charge development using the resin. In particular, an object of the present invention is to provide an electrophotographic toner for electrostatic charge development which is superior in hot offset resistance and durability as compared with a conventionally used electrophotographic toner and a binder resin used for this toner. It is to be. Another object of the present invention is to provide a toner for developing an electrostatic charge image capable of always obtaining a stable and high-density developed image even at high temperature and high humidity or low temperature and low humidity. It is another object of the present invention to provide a toner for developing an electrostatic image capable of forming a stable developed image for a long period of time. Another object of the present invention is to provide a toner for developing an electrostatic charge image capable of reducing the weight average particle diameter to 10 μm or less while suppressing the generation of fine powder of 5 μm or less to a small amount due to excellent durability. Still another object of the present invention is to provide a novel resin used for an electrophotographic toner.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve these problems, and as a result, have found an excellent binder resin for toner which could not be attained by the prior art, thereby completing the present invention. Reached. That is, the present invention provides: (1) a polyester resin having a density of 1.21 to 1.30 g / cm ³ , a number average molecular weight of 1500 to 20,000 and a glass transition temperature of 45 to 75 ° C. A binder resin for a toner, comprising as a main component. (2) The polyester resin is PET or / and PB
The binder resin for a toner according to (1), wherein T is T. (3) The binder resin for a toner according to (1) or (2), which is a urethane-modified polyester resin having a chain length of a polyisocyanate. (4) As the binder resin for a toner, (1) to (3). And an electrophotographic toner for electrostatic charge development using the resin described in any one of the above as a main component.

[0007]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described in more detail. The density of the polyester resin used in the present invention is from 1.21 to 1.30 g / cm ³ , and more preferably from 1.24 to 1.30 g / cm ³ .
If it is less than 1.21 g / cm ³ , it may not be preferable in terms of durability, and if it is more than 1.30 g / cm ³ , the pulverizability may be undesirably deteriorated. Number average molecular weight is 100
0 to 20,000 or less is preferable, but 2,000 to 15
000 or less is more preferable. When the number average molecular weight is less than 1000, it is not preferable in terms of hot offset resistance and durability, and when it is 20,000 or more, it may not be preferable in terms of fixability. Tg usually needs to be 40 to 75 ° C. If the temperature is lower than 40 ° C., the toner may cause blocking, which is not preferable. PET and PBT, which are raw materials of the polyester resin of the present invention, are obtained by processing recycled products into flakes, and have a weight average molecular weight of about 20,000 to 60,000.
Is not limited to the molecular weight distribution, composition, production method, form to be used, and the like. Also, it is not limited to recycled products. The polyester resin of the present invention may be a resin obtained by cross-linking two or more resins with a urethane-modified, epoxy-modified or trifunctional monomer. In particular, a resin obtained by urethane-modifying a polyester resin is preferably used. Hereinafter, as an example of a method for producing a polyester resin, a method in which a low molecular polyester (A) and a base polyester (B) are prepared, and after mixing, a urethane reaction with a polyvalent isocyanate is described.

[0008] The low-molecular polyester resin (A) comprises P
PE for all alcohol components including ethylene glycol and butylene glycol components in ET and / or PBT
It can be produced by polycondensing an alcohol component containing at least one diol and at least one acid component with 5 to 90 mol% of ethylene glycol and butylene glycol components in T and / or PBT. Reaction temperature is 2
It is preferably from 00 to 270 ° C, more preferably from 220 to 270 ° C.
Preferably it is 250 ° C. When the reaction temperature is 200 ° C. or lower, the solubility of PET and PBT deteriorates and the reaction time is prolonged, which tends to be unfavorable. Reaction temperature 27
If the temperature is 0 ° C. or higher, the decomposition of the raw material occurs, which tends to be unfavorable.

As the acid component, any of those conventionally used in producing polyester resins can be used. For example, terephthalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid , Sebacic acid, alkyl dicarboxylic acids such as azelaic acid,
Examples include unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, and itaconic acid; benzenedicarboxylic acids such as phthalic acid, isophthalic acid, and phthalic anhydride; and anhydrides or lower alkyl esters of these dicarboxylic acids. Further, for the purpose of adjusting the molecular weight, a monocarboxylic acid and a polycarboxylic acid having three or more valences can be used. Preferred monocarboxylic acids include aliphatic monocarboxylic acids such as octanoic acid, decanoic acid, dodecanoic acid, myristic acid, palmitic acid, and stearic acid, and even when branched, they have an unsaturated group. May be
Further, since these aliphatic monocarboxylic acids have a property of lowering the glass transition point, an aromatic monocarboxylic acid such as benzoic acid or naphthalene carboxylic acid may be used for adjusting the glass transition point. Examples of the polycarboxylic acid include trimellitic acid, pyromellitic acid, and acid anhydrides thereof.

As the alcohol component, any of those conventionally used in the production of polyester resins can be used. For example, ethylene glycol,
1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,3-butanediol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,5-pentane Diol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-
Alkyl diols such as 1,3-hexanediol,
Alicyclic diols such as hydrogenated bisphenol A and cyclohexane dimethanol, bisphenol F and bisphenol S derivatives, for example, alkylene oxide which is a reaction product of bisphenol F and bisphenol S with ethylene oxide and propylene oxide, and the above-mentioned bishydroxyethyl Aromatic diols which are lower alkyl esters of dicarboxylic acids such as terephthalic acid ester, bishydroxypropyl terephthalic acid ester and bishydroxybutyl terephthalic acid ester are exemplified. Further, bisphenol A derivatives such as bisphenol A alkylene oxide such as bisphenol A / ethylene oxide adduct and bisphenol A / propylene oxide adduct may be mentioned. Further, for the purpose of adjusting the molecular weight, a monoalcohol and a trivalent or higher polyol can be used. Preferred monools include octanol, decanol, dodecanol, myristyl alcohol, palmityl alcohol, aliphatic monoalcohols such as stearyl alcohol, and may be branched or may have an unsaturated group. . Examples of the trivalent or higher polyol include glycerin, 2-methylpropanetriol, trimethylolpropane, trimethylolethane, sorbit, and sorbitan.

On the other hand, the base polyester resin (B)
PE for all alcohol components including ethylene glycol and butylene glycol components in ET and / or PBT
It is produced by polycondensing an alcohol component comprising 5 to 90 mol% of ethylene glycol and butylene glycol components in T and / or PBT and at least one diol component and at least one or more acid components. At this time, the reaction temperature is preferably from 200 to 270 ° C.
The temperature is preferably from 20 to 250 ° C. Reaction temperature 20
When the temperature is 0 ° C. or lower, the solubility of PET and PBT is deteriorated, and the reaction time is prolonged. When the reaction temperature is 270 ° C. or higher, decomposition of the raw material occurs, which tends to be unfavorable.

Examples of the acid component here include those described for the polyester resin (A). As the alcohol component, those described for the polyester resin (A) are also mentioned. However, in order to sufficiently polymerize during chain extension with polyisocyanate, at least one
It is preferable to contain at least three or more polyols. When the trivalent or higher polyol component is usually less than 0.5 mol% based on the total alcohol component, it is difficult to polymerize when the chain is extended with polyisocyanate, and the offset resistance and durability are insufficient. On the other hand, if it exceeds 20 mol%, gelation is liable to occur and polycondensation is difficult to occur. Therefore, it is preferable to use 0.5 to 20 mol%, more preferably 2 to 20 mol%. More preferred. Further, at the time of polycondensation, 2 to 20 mol% is usually used based on all alcohol components or all carboxylic acid components.
More preferably, an amount of at least one long-chain aliphatic monoalcohol or long-chain aliphatic monocarboxylic acid is additionally present. The amount of the long-chain aliphatic monoalcohol or long-chain aliphatic monocarboxylic acid to be used is preferably 2 to 20 mol%, based on the total amount of the raw material monomers, and when it is 2 mol% or less, the anti-winding property is low, and Above, there is a tendency that the monofunctional compound inhibits polymerization and becomes difficult to polymerize, which is not preferable.

The polycondensation reaction for obtaining the polyester resin (A) or the polyester resin (B) is carried out in a known manner such as a high-temperature polycondensation in the absence of a solvent or a solution polycondensation in an inert gas such as nitrogen gas. It can be done by a method. The ratio of the carboxylic acid and the alcohol used in the reaction is such that the ratio of the latter hydroxyl group to the former carboxyl group is 0.7 to 1.
It is generally four.

The polyester resin (A) has a hydroxyl value of 10 KOH mg / g or less and a density of 1.21 g / cm ³ or more.
It is preferably 30 g / cm ³ or less. The number average molecular weight is from 1,000 to 20,000, but from 2,000 to 15,
000 is more preferred. When the number average molecular weight is less than 1,000, it is not preferable in terms of hot offset resistance and durability, and when it is 20,000 or more, it is not preferable in terms of fixability.

The polyester resin (B) has a density of 1.
More preferably, it is 21 g / cm ³ or more and 1.30 g / cm ³ or less, and the hydroxyl value is 10 to 90 KOH mg / g. When the hydroxyl value is less than 10, it may be difficult to polymerize, and the offset resistance may be insufficient. When the hydroxyl value is 90 or more, the gel content may be too large and the fixability may be insufficient. The number average molecular weight is preferably 1,000 or more and 50,000 or less. More preferably, it is 1,000 to 20,000. When the number average molecular weight is less than 1000, it may not be preferable in terms of hot offset resistance and durability. When the number average molecular weight is 50,000 or more, the viscosity at the time of production is too high, which is not economically preferable.

The urethane-modified polyester resin (C) obtained by chain-extending a mixture of the low-molecular polyester (A) and the base polyester resin (B) with polyisocyanate is represented by (A)
It is preferable that it is 0.2-2 molar equivalent as an isocyanate group with respect to 1 molar equivalent of the total hydroxyl value of (B) and (B), and it is more preferable that it is 0.5 molar equivalent-1.5 molar equivalent. If it is less than 0.2 molar equivalent, it is not preferable in terms of hot offset resistance, and if it exceeds 2 molar equivalent, polyisocyanate may be present as a monomer in the produced resin, which is not preferable. .

Examples of the polyisocyanate used in the resin (C) include diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and tetramethylene diisocyanate. It is also possible to use other trivalent or higher polyisocyanates.

The weight ratio of the polyester resin (A) to the polyester resin (B) is from 0/100 to 90/10, preferably from 10/90 to 90/10, and more preferably from 20/80 to 80/10. / 20 is preferable.
When it is 90/10 to 100/0, it tends to be unfavorable in terms of hot offset resistance and especially durability. In addition, polyester resin (A) and polyester resin (B)
It is preferable from the viewpoint of hot offset resistance that the molecular weight distribution (Mw / Mn) of the polyester resin composed of the polyester resin (C) obtained by urethane modification is 6 or more.

In the present invention, the acid value is 1 g of resin.
Means the number of mg of potassium hydroxide required to neutralize the resin, and the hydroxyl value is the potassium hydroxide required to neutralize the acid anhydride necessary to esterify the hydroxyl groups in 1 g of the resin. Means the mg number.

In the toner for developing an electrostatic image of the present invention, in addition to the resin, other known binder resins other than the resin, a charge adjusting agent, a coloring agent, a wax, a magnetic material, an abrasive, Materials commonly used in the production of toner such as a fluidizing material can be added.

As the other resin which can be used together with the above resin, any resin may be used as long as it is conventionally known as a binder resin for a toner for developing an electrostatic image. For example, polystyrene, poly-p-chlorostyrene, polyvinyl toluene Styrene such as styrene and a substituted polymer thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer,
Styrene-methacrylate copolymer, styrene-
α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer Styrene-based copolymers such as styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polystyrene Vinyl acetate, silicone resin, polyester resin other than the above resins, polyurethane resin, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin, cross-linked styrene Resins such as copolymers. However, it is needless to say that the amount used is within a range in which the performance of the resin of the present invention is exhibited.

As the charge control agent, known charge control agents can be used alone or in combination. The charge control agent may be an amount necessary to bring the toner to a desired charge amount, for example, 0.05 to 100 parts by weight of the resin.
It is preferably about 10 to 10 parts by weight. Examples of the positive charge control agent include a nigrosine dye, a quaternary ammonium salt compound, a triphenylmethane compound, an imidazole compound, and a polyamine resin. Also,
Examples of the negative charge control agent include metal-containing azo dyes such as Cr, Co, Al, and Fe, metal salicylate compounds, metal alkylsalicylate compounds, and curlic arene compounds.

As the colorant that can be used in the toner for developing an electrostatic image of the present invention, any colorant that is conventionally known to be used in the production of a toner can be used. Examples thereof include fatty acid metal salts, various carbon blacks, phthalocyanine-based, rhodamine-based, quinacridone-based, triallylmethane-based, anthraquinone-based, azo-, and diazo-based dyes and pigments. The coloring agents can be used alone or in combination of two or more.

The magnetic material that can be used in the toner for developing an electrostatic image of the present invention includes any of alloys and compounds containing a ferromagnetic element conventionally used in the production of magnetic toners. Is also good. Examples of these magnetic substances include magnetite, maghetite, a compound of iron oxide or a divalent metal and iron oxide such as ferrite, iron,
Metals such as cobalt and nickel or metals such as aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium Alloys, and mixtures thereof. These magnetic materials preferably have an average particle size of about 0.1 to 2 μm, and more preferably about 0.1 to 0.5 μm. The content of the magnetic substance in the toner is usually about 20 to 200 parts by mass, preferably 40 to 150 parts by mass, based on 100 parts by mass of the binder resin. The saturation magnetization of the toner is preferably 15 to 35 emu / g (measurement magnetic field: 1 kOe).

The toner of the present invention may further contain, if necessary, known additives used in the production of toners such as a release agent, a lubricant, a fluidity improver, an abrasive, a conductivity-imparting agent, and an image peeling preventive. The agent can be added internally or externally.
Examples of these additives include release agents such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax, carnauba wax, sasol wax, wax-like substances such as paraffin wax, and these are usually binder resins. It is added to the toner in an amount of about 0.5 to 20% based on 100% by weight. Examples of the lubricant include polyvinylidene fluoride, zinc stearate, and the like. Examples of the fluidity improver include colloidal silica, aluminum oxide, and titanium oxide. Examples of the abrasive include cerium oxide, silicon carbide, strontium titanate, and tungsten carbide. , Calcium carbonate, etc.
Examples of the conductivity-imparting agent include carbon black and tin oxide. Further, fine powder of a fluorine-containing polymer such as polyvinylidene fluoride is preferable in terms of fluidity, abrasiveness, charge stability and the like.

The toner according to the present invention can be manufactured by a conventionally known method. Generally, the above-mentioned toner constituent materials are sufficiently mixed by a mixer such as a ball mill and a Henschel mixer, and then kneaded well using a hot kneader such as a hot roll kneader or a single-screw or twin-screw extruder. After cooling and solidifying, it is preferable to produce by a method of mechanically coarsely pulverizing using a pulverizer such as a hammer mill, then finely pulverizing with a jet mill or the like, and then classifying. However, the method of producing the toner is not limited to this method, and other methods such as a method of dispersing other toner constituent materials in a binder resin solution, followed by spray drying, a method of producing a toner by a so-called microcapsule method, and the like. Can also be arbitrarily adopted.

The toner of the present invention may be mixed with a carrier to form a two-component or one-component toner. It can be used as a five-component developer, or as a magnetic one-component developer containing magnetic powder in the toner, a non-magnetic one-component developer without using a carrier or magnetic powder, or a microtoning developer Can be. When the toner of the present invention has two components or one.
When used as a five-component developer, any conventionally known carrier can be used as the carrier. Examples of carriers that can be used include magnetic powders such as iron powder, ferrite powder, and nickel powder, glass beads, and the like, or those obtained by treating the surfaces of these with a resin. As the resin for coating the carrier surface, a styrene-acrylate copolymer, a styrene-methacrylate copolymer, an acrylate copolymer, a methacrylate copolymer, a fluorine-containing resin,
Examples thereof include a silicon-containing resin, a polyamide resin, an ionomer resin, a polyphenylene sulfide resin, and the like, and a mixture thereof. Among these, a fluorine-containing resin and a silicon-containing resin are particularly preferable because the formation of spent toner is small.

The weight average particle diameter of the toner of the present invention is 10
Although it is not more than μm, it is preferably from 3 to 10 μm in terms of development characteristics, and more preferably from 5 to 10 μm in terms of development characteristics. The weight average particle size of the toner is 1
If the thickness exceeds 0 μm, it is difficult to develop a fine image, which is not preferable in terms of development characteristics. The particle size distribution of the toner can be measured using, for example, a Coulter counter.

[0029]

The present invention will be described more specifically with reference to the following examples. However, the following examples are only for describing the present invention, and the present invention is not limited to those described in these examples.

Production example A1 of polyester resin (A) A 5-liter four-necked flask was equipped with a reflux condenser, a water separator, a nitrogen gas inlet tube, a thermometer and a stirrer.
Flaky recycled PET (weight average molecular weight 550
7), 30.0 mol% of polyol KB300 (manufactured by Mitsui Chemicals, Inc.), and terephthalic acid (TPA).
Dehydration condensation polymerization was carried out at 240 ° C. while introducing 0 mol% and 8.0 mol% of benzoic acid into the flask. When the OH value of the reaction product reached a predetermined value, it was extracted from the flask, cooled and pulverized to obtain a resin A1. The density of the obtained resin was 1.25 g / cm ³ . Table 1 shows the physical property values of the obtained polyester resin A1.

The type and amount of acid used in Production Example A2 to A5 materials and alcohols (molar ratio), except that it is assumed in Table 1, according to Preparation A1, was prepared polyester resin A2 to A5. Table 1 shows the physical property values of the obtained polyester resins A2 to A5.

[0032]

[Table 1]

Production Examples B1 to B5 Polyester resins B1 to B5 were produced in accordance with Production Example A1, except that the types and amounts (molar ratios) of acids and alcohols used as raw materials were as shown in Table 2. Table 2 shows the physical property values of the obtained polyester resins B1 to B5.

[0034]

[Table 2]

Example 1 Polyester resin A1 and polyester resin B2 were
1 was used at a rate of 60% by weight, B2 was used at a rate of 40% by weight, and the polyester resin A1 was first supplied to a twin-screw kneader (KEX-40, manufactured by Kurimoto Iron Works) at a flow rate of 6 kg / hr. B1 is supplied at a flow rate of 4 kg / hr, melt-kneaded and conveyed, and tolylene diisocyanate is further supplied at a flow rate of 233 g / hr to the resin mixture being kneaded and conveyed to continue the kneading and to carry out a reaction. Thus, a mixed resin of the urethane-modified polyester resin C1 was obtained. Table 3 shows the physical properties of the mixed resin.

Examples 2 to 5 Example 1 was repeated except that the types and mixing ratios of the polyester resin (A) and the polyester resin (B) were set to the ratios shown in Table 3.
To obtain a mixed resin of a urethane-modified polyester resin (C). Table 3 shows the physical property values of this mixed resin.

Comparative Examples 1 and 2 Example 1 was repeated except that the types and the mixing ratios of the polyester resin (A) and the polyester resin (B) were set to the ratios shown in Table 3.
To obtain a mixed resin of a urethane-modified polyester resin (C). Table 3 shows the physical property values of this mixed resin.

[0038]

[Table 3]

Evaluation of Mixed Resin Toner The mixed resins obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were converted into toners by the following method and evaluated. The mixed resin obtained in Example 1 is shown as a typical example, but other mixed resins were converted into toners in exactly the same manner.

Toner of the mixed resin obtained in Example 1
Mixed resin 90 parts by weight of carbon black obtained by chromatography of Example 1 (manufactured by Mitsubishi Chemical Corporation MA100) 5 parts by weight charge control agent (metal-containing system chromed; Spiron Black 2 parts by TRH, Hodogaya Chemical Co., Ltd.) Wax (Polyolefin type; Mitsui High Wax NP 3 parts by weight 105, manufactured by Mitsui Chemicals, Inc.) After mixing with a Henschel mixer, the mixture is put into a twin-screw kneader and kneaded, and the extruded product is cooled at room temperature and then hammer milled. After coarse pulverization, it is finely pulverized with a jet mill pulverizer (manufactured by Nippon Pneumatic) and guided to a classifier (manufactured by Nippon Pneumatic). Those having a particle diameter of 20.0 μm or more have a weight average particle diameter of 1.0% by volume or less of 8%.
A μm toner was obtained. To 100 parts by weight of this toner powder, 0.3 parts by weight of hydrophobic silica (Aerosil R-972, manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain toner particles. Further, 4 parts of the toner particles were mixed with 96 parts of a ferrite carrier (F150 manufactured by Nippon Iron Powder) to obtain a developer. Table 4 shows the results of a copy test conducted by using a magnetic brush method heat roll type copying machine equipped with a selenium photoreceptor and changing the fixing temperature. A durability test was also performed using these developers. The results are also shown in Table 4.

(Durability) A 100 ml screw tube was filled with 100 parts of the developer and stirred for 40 hours at 200 rpm with a turbula shaker mixer. The evaluation criteria are shown below. A: 1% by weight or less.・ ・ ・: 1 to 3% by weight. Δ: 3 to 10% by weight. ×: 10% by weight or more. (Offset resistance) The evaluation of the offset resistance is based on the measurement of the minimum fixing temperature described above. However, after an unfixed image is formed by the copying machine, the toner image is transferred and fixed by the heat roller fixing device described above. Then, an operation of sending a blank transfer sheet to the heat roller fixing device under the same conditions and visually observing whether or not toner stain occurs on the transfer sheet is performed by setting a temperature of the heat roller of the heat roller fixing device. Were sequentially raised, and the lowest set temperature at which toner contamination occurred was taken as the offset occurrence temperature. Also,
Environmental conditions are normal temperature and normal pressure (temperature 22 ° C, relative humidity 55%)
And ◎: Offset occurrence temperature ≧ 235 ° C. ○; 235 ° C.> Offset occurrence temperature ≧ 220
℃ △; 220 ℃> offset occurrence temperature ≧ 20
5 ° C. ×; 205 ° C.> Offset occurrence temperature (Fixing property) The fixing property is as follows. An unfixed image is created by a copying machine modified from a commercially available electrophotographic copying machine, and the unfixed image is fixed to a fixing unit of a commercially available copying machine. Was fixed using a modified heat roller fixing device. The fixing speed of the heat roll was 210 mm / sec, and the temperature of the heat roller was changed by 5 ° C. to fix the toner. The obtained fixed image was rubbed 10 times with a load of 0.5 Kg by a sand eraser (manufactured by Dragonfly Pencil),
The image density before and after the friction test was measured by a Macbeth reflection densitometer. The lowest fixing temperature at which the rate of change of the image density at each temperature became 70% or more was defined as the lowest fixing temperature.
The heat roller fixing device used here does not have a silicone oil supply mechanism. The environmental conditions are
Normal temperature and normal pressure (temperature 22 ° C., relative humidity 55%). ；; Minimum fixing temperature ≤ 150 ° C △; 190 ° C ≧ Minimum fixing temperature> 150 ° C ×; Minimum fixing temperature> 190 ° C (pulverizability) The volume average particle size is the volume average particle size obtained by a Coulter counter. The determination of the pulverizability was performed according to the following criteria by measuring the volume average particle size of a sample pulverized by a jet mill under a certain condition.

[0042]

[Table 4]

It can be said that the fixing property by the copy paper test is in a sufficient range for use in both the examples and comparative examples.
As a result, good durability and offset resistance, which are considered to be caused by the resin density, were confirmed.

[0044]

According to the present invention, a urethane-modified polyester resin having a density of 1.22 to 1.30 g / cm ³ , a number average molecular weight of 1,000 to 20,000, and a glass transition temperature of 45 to 75 ° C. and chain extended with a polyisocyanate is used as a binder resin. The resulting toner exhibits good fixability, is particularly excellent in durability and offset resistance, and has excellent performance as an electrophotographic toner.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Yuji Emura 580-32 Nagaura, Nagaura, Sodegaura-shi, Chiba F-term (reference) 2H005 AA01 CA08 CA18 EA03 EA06 EA10

Claims (4)

[Claims] 1. A density of 1.21 or more and 1.30 g / cm ^3.
A binder resin having a number average molecular weight of from 1500 to 20,000 and a glass transition temperature of from 45 to 75 ° C. as a main component. 2. The binder resin for a toner according to claim 1, wherein the polyester resin is PET and / or PBT. 3. The binder resin for a toner according to claim 1, wherein the binder resin is a urethane-modified polyester resin chain-chained with a polyisocyanate. 4. The toner according to claim 1, which is used as a binder resin for a toner.
An electrophotographic toner for electrostatic charge development using the resin according to any one of the above-described items 3 to 3 as a main component.