JP3370266B2 - Full-color electrophotographic developer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-color electrophotographic developer used for developing an electrostatic latent image formed in an electrophotographic method, an electrostatic printing method, an electrostatic recording method or the like.

[0002]

2. Description of the Related Art Conventionally, a two-component developer containing a toner and a carrier is used for developing an electrostatic latent image formed by an electrophotographic method or the like. As such a two-component developer, generally used is a two-component developer containing a ferrite carrier containing a heavy metal such as copper or zinc. However, such a two-component developer may be subject to use restrictions in some areas due to the use of heavy metals. Further, among the two-component developers, the two-component developer in which copper-zinc ferrite having a low saturation magnetization is mixed as a carrier has a drawback that carrier rising easily occurs.

Therefore, in recent years, as a developer capable of effectively preventing the carrier from rising, a two-component developer using magnetite having a large residual magnetization has been proposed. However, the two-component developer has a drawback that it causes deterioration of fluidity of the developer due to magnetization and may cause various problems such as reduction of image density.

Further, when a carrier containing magnetite is used and a large amount of a releasing agent is added in order to obtain a developer that can be used in a full-color electrophotographic system which does not require an oil coating device at the time of fixing, Has a drawback that the fluidity of the developer is further deteriorated due to heat generation during stirring.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide a full-color electrophotographic developer which is excellent in fluidity and does not cause carrier rising.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is a full-color electrophotographic toner containing a binder resin, a release agent and a colorant, wherein 50% by weight or more of the binder resin is softened. A full-color electrophotographic toner, which is a linear polyester having a point of 90 to 120 ° C. and the release agent is carnauba wax, and has the formula (I): (MnO) _x (Fe ₂ O ₃ ) _100-x (I) The present invention relates to a full-color electrophotographic developer prepared by mixing with a carrier represented by the formula (X represents an integer of 1 to 50).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The full-color electrophotographic developer of the present invention comprises a full-color electrophotographic toner containing a binder resin, a release agent and a colorant, and a compound of the formula (I): (MnO) _x ( Fe ₂ O ₃ ) _100-X (I) (wherein X represents an integer of 1 to 50) and the carrier represented by the formula.

First, the full-color electrophotographic toner will be described.

As described above, the full-color electrophotographic toner used in the present invention contains a binder resin, a release agent and a colorant.

The binder resin contains a linear polyester having a softening point of 90 to 120 ° C. The linear polyester is contained in the binder resin in an amount of 50% by weight or more, preferably 70% by weight or more, from the viewpoint of offset resistance, glossiness and transparency. The linear polyester is used as the main component of the binder resin in order to improve the smoothness and glossiness of the fixing surface by reducing the elasticity of the binder resin and increasing the melting rate. is there.

The linear polyester uses a divalent carboxylic acid component and a divalent alcohol component as constituent monomers.

In the present invention, the divalent carboxylic acid component contains at least one selected from the group consisting of aromatic and aliphatic dicarboxylic acids, anhydrides of dicarboxylic acids, and lower alkyl esters of dicarboxylic acids. .

The aromatic dicarboxylic acid is, for example, phthalic acid, isophthalic acid, terephthalic acid or the like, and the anhydride of the aromatic dicarboxylic acid is, for example, phthalic anhydride or the like, which is lower than the aromatic dicarboxylic acid. Examples of the alkyl (C1-5) ester include terephthalic acid esters such as dimethyl terephthalate.

Examples of the aliphatic dicarboxylic acid, the anhydride of the aliphatic dicarboxylic acid and the lower alkyl ester of the aliphatic dicarboxylic acid include, for example, fumaric acid, maleic acid, succinic acid, adipic acid and the like dicarboxylic acids having 4 to 10 carbon atoms. Acids and succinic acids substituted with an alkyl group or an alkenyl group having 1 to 20 carbon atoms such as n-dodecyl succinic acid and octenyl succinic acid, anhydrides of these acids, and lower alkyls of these acids (having 1 to 1 carbon atoms). 5) Esters and the like can be mentioned.

Among the above-mentioned divalent carboxylic acid components, aliphatic dicarboxylic acids having 2 to 30 carbon atoms, their anhydrides and their lower alkyl esters such as aliphatic dicarboxylic acids are offset resistance, glossiness and transparency. From the point of view,
The content of the carboxylic acid component in the carboxylic acid component is particularly preferably 50 to 90 mol% from the viewpoints of offset resistance, pulverizability efficiency and glass transition point.

The dihydric alcohol component is, for example, polyoxypropylene (2.2) -2,2-bis.
Alkylene oxide adducts of bisphenol A such as (4-hydroxyphenyl) propane and polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1,2- Propylene glycol,
Neopentyl glycol, diols having 2 to 10 carbon atoms such as 1,6-hexanediol, polyalkylene glycols such as polyethylene glycol, bisphenol A,
Examples thereof include hydrogenated bisphenol A, and these can be used alone or in admixture of two or more. Of these, alkylene oxide adducts of bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol and neopentyl glycol are preferred.

The linear polyester can be obtained by polymerizing by utilizing esterification reaction, transesterification reaction and the like. Specifically, for example, reaction temperature 1
At 70 to 220 ° C. and a reaction pressure of 5 mmHg to normal pressure, polycondensation and the like are performed while blending an esterification catalyst such as dibutyltin oxide and a catalyst such as a polymerization inhibitor such as hydroquinone, if necessary (optimum temperature, pressure, etc.). Is determined by the reactivity of the monomer, etc.), and the reaction may be terminated when the predetermined physical properties are achieved.

The softening point of the linear polyester is 90 ° C. or higher, preferably 95 ° C. or higher from the viewpoint of preventing cold offset, and 1 from the viewpoint of gloss and transparency.
The temperature is 20 ° C or lower, preferably 110 ° C or lower, and more preferably 105 ° C or lower. The softening point in the present invention is
It can be measured using a high performance type flow tester whose outline is described in JIS K7210.

The glass transition point of the linear polyester is
From the viewpoint of storage stability, 40 ° C or higher, preferably 45 ° C
The above is desirable. The glass transition point in the present invention can be measured using a differential scanning calorimeter.

As described above, the binder resin in the present invention contains the above-mentioned linear polyester as a main component, but within a range that does not impair the effects of the present invention, for example, a cross-linked polyester,
Other resins such as styrene-acrylic copolymer may be used in combination. In the present invention, it is preferable that, in addition to the linear polyester, it further contains a crosslinked polyester having a side chain of 2 to 30 carbon atoms.

The crosslinked polyester is excellent in preventing hot offset on the high temperature side, and by blending it in an appropriate amount, it is possible to suppress the decrease in the melting rate to the extent that the smoothness and glossiness of the fixing surface are not impaired in practical use. This is because it will be possible.

The crosslinked polyester is usually one in which, in addition to the constituent monomers of the divalent carboxylic acid component and the alcohol component, at least one of the trivalent or higher carboxylic acid component and the alcohol component is used as a constituent monomer. It is preferable that any one of the constituent monomers has a side chain having 2 to 30 carbon atoms such as dodecenyl succinic anhydride. 2 to 3 carbon atoms in cross-linked polyester
When a constituent monomer having a side chain of 0 is used, the softening point of the crosslinked polyester can be adjusted to enhance gloss at the time of fixing.

As the trivalent or higher carboxylic acid component, known ones such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid and acid anhydrides thereof, lower Alkyl (C1-C5) ester etc. are mentioned, These can be used individually or in mixture of 2 or more types. Of these, trimellitic acid or its derivative is preferable because it is inexpensive and the reaction control is easy.

Examples of the trihydric or higher alcohol component include sorbitol having 3 to 10 carbon atoms, 1,4-sorbitan, pentaerythritol, glycerol, trimethylolpropane and the like, and these may be used alone or in combination of two or more. It can be mixed and used. Of these, glycerol and trimethylolpropane are preferred.

The cross-linked polyester is contained in a binder resin,
From the viewpoint of preventing hot offset properties, it is desirable that the content is 5 wt% or more, preferably 10 wt% or more, and from the viewpoint of gloss at the time of fixing, 35 wt% or less, preferably 30 wt% or less. It is desirable to be present.

When the linear polyester and the crosslinked polyester are mixed and used, the difference in the softening point affects the glossiness. Therefore, the difference in softening point between the crosslinked polyester and the linear polyester is preferably 20 ° C. or less from the viewpoint of gloss at the time of fixing.

In the present invention, carnauba wax (melting point: about 83 ° C.) having a melting point lower than the softening point of the linear polyester by 10 to 20 ° C. or more is used as a release agent for preventing offset.

In the present invention, when the linear polyester and the carnauba wax are used in combination, the carnauba wax oozes out from the toner before the linear polyester is melted, so that in an oil-free environment,
It can have a wide non-offset temperature range.

From the viewpoint of offset resistance (high temperature side), the amount of the carnauba wax is preferably 3 parts by weight or more, and more preferably 5 parts by weight or more with respect to 100 parts by weight of the binder resin. From the viewpoint of ensuring the glass transition point, it is desirable that the amount is 15 parts by weight or less, preferably 12 parts by weight or less, relative to 100 parts by weight of the binder resin.

As the colorant contained in the toner used in the present invention, all the dyes and pigments used in the conventional colorants for toner can be used. Examples of the colorant used in the present invention include carbon black, acetoacetic acid arylamide monoazo yellow pigments, acetoacetic arylamide disazo yellow pigments, yellow dyes, red or red pigments, red dyes, copper phthalocyanine and the like. Derivatives such as blue dyes and pigments and green pigments can be used. These dyes and pigments may be used alone or in combination of two or more. The amount of the colorant used is not particularly limited, but is usually 0.1 to 100 parts by weight of the binder resin.
It is preferably about 10 parts by weight.

The toner used in the present invention may appropriately contain various additives as an internal additive or an external additive. Examples of the additive include a charge control agent, a fluidity improver, a cleaning property improver, a conductive substance, an extender filler, a reinforcing filler such as a fibrous substance, an antioxidant, and an antiaging agent. These may be used alone or in admixture of two or more.

The toner used in the present invention can be manufactured by a conventionally known method such as a kneading and pulverizing method, a spray dry method, and a polymerization method. For example, as a general example, first, a binder resin, a release agent, a colorant, various internal additives and the like are uniformly dispersed and mixed by a known mixer such as a Henschel mixer, and then the mixture is sealed in a kneader. It may be carried out by melt-kneading with a single-screw or twin-screw extruder or an open roll kneader, cooling, pulverizing, and classification. If necessary, a fluidity improver or the like can be added to the toner as an external additive.

The average particle size of the toner thus obtained is 5
It is preferably about 15 μm.

Next, the carrier used in the developer of the present invention will be described.

As described above, the carrier is represented by the formula (I): (MnO) _x (Fe ₂ O ₃ ) _100-X (I) (wherein, X represents an integer of 1 to 50). It is something.

The average particle size of the carrier is usually 50 to 50.
It is preferably about 150 μm.

The developer of the present invention can be prepared by mixing the full-color electrophotographic toner and the carrier using, for example, a V-shaped mixer.

Usually, the carrier is preferably used in an amount of about 90 to 98% by weight in the full-color electrophotographic developer.

The full-color electrophotographic developer of the present invention comprises
When fixing using a heat roller, excellent fluidity, even when used in a full-color electrophotographic system that does not require application of a release agent on the heat roller surface,
It does not raise the carrier.

[0040]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The softening point and glass transition point of the resins described in the examples are measured according to the methods described below.

[Softening point] Koka type flow tester (Co., Ltd.)
Shimadzu's product name: CFT-500) is used and 1 g
While heating the sample of No. 3 at a temperature rising rate of 6 ° C./min, a load of 30 kg / cm ² was applied by a plunger to obtain a diameter of 1 mm,
A nozzle with a length of 1 mm is pushed out, whereby a plunger drop amount (flow value) -temperature curve of the flow tester is drawn, and when the height of the S-shaped curve is h, the temperature corresponding to h / 2 (resin The temperature at which half flows out is defined as the softening point.

[Glass Transition Point] Using a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd., trade name: DSC210), the temperature was raised to 200 ° C., and the temperature was cooled from that temperature to room temperature at a rate of 10 ° C./min. When the sample was measured at a heating rate of 10 ° C./min, the temperature at the intersection of the extension line of the baseline below the glass transition point and the tangent line showing the maximum slope between the rising portion of the peak and the peak apex was measured. The glass transition point.

Resin Production Example 1 (Production of Linear Polyester) Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 999 g Polyoxyethylene (2.2) -2,2-bis (4-Hydroxyphenyl) propane 48 g Fumaric acid 156 g Dimethyl terephthalate 126 g Adipic acid 153 g Dibutyltin oxide 1 g Put in a four-necked flask, thermometer, stainless steel stirring rod,
Attach a down-flow type condenser and a nitrogen introduction tube, and in a mantle heater under a nitrogen stream at 200-230 ° C.
The reaction was carried out under reduced pressure with, and the linear polyester obtained was
This is resin A. Resin A had a softening point of 104.9 ° C and a glass transition point of 55.8 ° C.

Resin Production Example 2 (Production of Crosslinked Polyester) Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 460 g Polyoxyethylene (2.2) -2,2-bis ( 4-hydroxyphenyl) propane 425 g trimellitic anhydride 48 g dimethyl terephthalate 165 g dodecenyl succinic anhydride 268 g dibutyltin oxide 1 g The above substances were reacted in the same manner as in Resin Production Example 1 to obtain a crosslinked polyester. Resin B
And Resin B had a softening point of 102.8 ° C and a glass transition point of 57.8 ° C.

Toner Production Example 1 84 parts by weight of resin A, 16 parts by weight of resin B, 10 parts by weight of carnauba wax (melting point 83 ° C.), yellow pigment [Pig. Yellow]
Y-17] 3 parts by weight and 0.5 parts by weight of a charge control agent (manufactured by Nippon Carlit Co., Ltd., trade name: LR-147) were kneaded in a twin-screw extruder, and after cooling, ordinary pulverization and classification steps were performed. After that, fine powder having an average particle size of 7 μm was obtained. This was surface-treated with silica (manufactured by Cabot Corporation, trade name: TS-530) to obtain a yellow toner.

Toner Production Example 2 In the toner production example 1, instead of 3 parts by weight of the yellow pigment, a red pigment [C. I. Pigment Red 122] 6
Except for using parts by weight, the same procedure as in Toner Production Example 1 was conducted.
The magenta toner is obtained.

Toner Production Example 3 In the toner production example 1, instead of 3 parts by weight of the yellow pigment, a copper phthalocyanine pigment [C. I. Pigment Blue 15: 3], except that 3 parts by weight of Toner is used.
A cyan toner was obtained in the same manner as in.

Example 1 3.5 parts by weight of the yellow toner obtained in Toner Production Example 1 and manganese ferrite carrier [(MnO) ₃₀ (F
e ₂ O ₃ ) ₇₀ ] 96.5 parts by weight were mixed in a V-type mixer and stirred for 10 minutes to obtain a yellow developer.

Example 2 3.5 parts by weight of magenta toner obtained in Toner Production Example 2 and manganese ferrite carrier [(MnO) ₃₀ (F
e ₂ O ₃ ) ₇₀ ] 96.5 parts by weight were mixed in a V-type mixer and stirred for 10 minutes to obtain a magenta developer.

Example 3 3.5 parts by weight of the cyan toner obtained in Toner Production Example 3 and manganese ferrite carrier [(MnO) ₃₀ (Fe
The ₂ O _{3) 70]} 96.5 parts by weight were mixed in a V-type mixer to obtain a cyan developer and stirred for 10 minutes.

Comparative Example 1 In Example 1, the manganese ferrite carrier 96.
Comparative Yellow Developer 1 was obtained in the same manner as in Example 1 except that 96.5 parts by weight of a copper-zinc ferrite carrier (manufactured by Powder Tech Co., Ltd.) was used instead of 5 parts by weight.

Comparative Example 2 In Example 2, the manganese ferrite carrier 96.
Comparative magenta developer 1 was obtained in the same manner as in Example 2 except that 96.5 parts by weight of a copper-zinc ferrite carrier (manufactured by Powdertec Co., Ltd.) was used instead of 5 parts by weight.

Comparative Example 3 In Example 3, the manganese ferrite carrier 96.
Comparative Cyan Developer 1 was obtained in the same manner as in Example 3 except that 96.5 parts by weight of a copper-zinc ferrite carrier (manufactured by Powdertech Co., Ltd.) was used instead of 5 parts by weight.

Comparative Example 4 In Example 1, the manganese ferrite carrier 96.
Comparative Yellow Developer 2 was obtained in the same manner as in Example 1 except that 96.5 parts by weight of magnetite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) was used instead of 5 parts by weight.

Comparative Example 5 In Example 2, the manganese ferrite carrier 96.
Comparative magenta developer 2 was obtained in the same manner as in Example 2 except that 96.5 parts by weight of magnetite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) was used instead of 5 parts by weight.

Comparative Example 6 In Example 3, the manganese ferrite carrier 96.
Comparative cyan developer 2 was obtained in the same manner as in Example 3 except that 96.5 parts by weight of magnetite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) was used instead of 5 parts by weight.

Test Example 1 Yellow developer, magenta developer, cyan developer, comparative yellow developers 1 and 2, comparative magenta developers 1 and 2 and comparative cyan developers 1 and 2 were used only in the developing tank of a commercially available monochrome printer. Each of them was filled with a single color and then stirred in a device that made it possible to stir, and returned the developing tank to the actual printer at a stirring time of 1 hour, 2 hours, 3 hours, 4 hours, 8 hours, and 12 hours to perform an actual printing test. Was done.

As a result, although the yellow developer, the magenta developer and the cyan developer are capable of oil-free fixing, the residual magnetization of the carrier is small, so that the stirring time exceeds 12 hours. The fluidity of the developer was almost the same as the initial one. In addition, the density of the solid part of the printed image is kept at about 1.6, it hardly deteriorates with time, the halftone texture remains fine, and accurate printing is possible without being affected by stirring. Met.

Further, during printing, the carrier rising to the photosensitive member due to the low saturation magnetization of the carrier did not occur at all in the actual printing range, and neither the image disturbance nor the photosensitive member damage due to the carrier rising was observed. .

The comparative yellow developer 1, the comparative magenta developer 1 and the comparative cyan developer 1 have the same fluidity as the yellow developer, the magenta developer and the cyan developer even if the stirring time exceeds 12 hours. In terms of the degree, there was almost no difference from the initial stage. However, since the saturation magnetization of the carrier is low, the carrier rises, and in the print test, the image in the solid portion of the image, the continuous thin line portion and the halftone portion is disturbed,
Accurate printing was not possible.

Further, the photoreceptor was damaged due to the carrier rising to the photoreceptor due to the low saturation magnetization of the carrier.

In the comparative yellow developer 2, the comparative magenta developer 2 and the comparative cyan developer 2, the fluidity of the developer begins to deteriorate when the stirring time is 1 hour, and the developer on the mag roller stands up in 4 hours. The defects started to appear, and after 12 hours, the ears were almost gone. This is probably because the magnetite used as a carrier has a high remanence, which deteriorates the fluidity of the developer and causes heat generation, which has a thermal effect on the toner and further deteriorates the fluidity. Be done. In the actual printing test, the solid portion of the image became thin and rough as the fluidity deteriorated, and eventually printing became impossible.

[0064]

According to the present invention, it is possible to provide a full-color electrophotographic developer which is excellent in fluidity and does not cause carrier rise even when used in a full-color electrophotographic system which does not require an oil coating device. It became possible.

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-8-220808 (JP, A) JP-A-8-6302 (JP, A) JP-A-9-281805 (JP, A) JP-A 61- 36761 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08 G03G 9/107

Claims (4)

(57) [Claims] 1. A full-color electrophotographic toner containing a binder resin, a release agent and a colorant, wherein 50% by weight or more of the binder resin is a linear polyester having a softening point of 90 to 120 ° C. And a full-color electrophotographic toner in which the release agent is carnauba wax, and a formula (I): (MnO) _x (Fe ₂ O ₃ ) _100-X (I) (wherein X is 1 to 50). A developer for full-color electrophotography, which is formed by mixing with a carrier represented by an integer. 2. The full-color electrophotographic developer according to claim 1, wherein the binder resin further contains 5 to 35% by weight of a crosslinked polyester having a side chain of 2 to 30 carbon atoms. 3. The amount of carnauba wax is equal to that of the binder resin 10.
The full-color electrophotographic developer according to claim 1 or 2, which is 3 to 15 parts by weight with respect to 0 parts by weight. 4. A full color electrophotographic toner is a heat roller.
To the roller surface as a release agent when fixing with a roller
4. The oil application according to claim 1 is not required.
Full color electrophotographic developer.