JP2001175029A - Method for producing modified polyester resin for electrophotograpffic toner and electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyester resin suitable for use as the binder of an electrophotographic toner and an electrophotographic toner excellent in both low temperature fixability and anti-hot-offsetting property and excellent also in shelf stability. SOLUTION: The modified polyester resin for electrophotography having a specified molecular weight distribution curve is produced by reacting a polyester resin with an epoxy-containing vinyl polymer. The electrophotographic toner contains the modified polyester resin as an essential component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of producing a polyester resin for an electrophotographic toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, and an electrophotography including the resin. The present invention relates to a toner for use.

[0002]

2. Description of the Related Art Conventionally, in the field of electrophotography, styrene-acrylic copolymers and various synthetic polymers have been used as a binder component used in a toner which is a colorant for forming an image. Among them, polyester resins are widely used as dry electrophotographic toners for color copying because of their characteristics such as appropriate melt viscosity and flexibility, and good image transparency.

[0003] However, since the polyester resin contains a polar ester bond in the skeleton, its performance such as water resistance and hydrolysis resistance is inferior to styrene acrylic copolymers and the like. As a result, the toner containing the polyester resin has insufficient environmental stability and has an unstable image quality. In addition, when the temperature of the heat roller for fixing rises, the viscoelastic behavior of the polyester resin at the time of melting is different from that of a styrene-acrylic copolymer or the like, so that toner powder partially adheres to the fixing roll. However, the so-called offset phenomenon is liable to occur, which contaminates the copy by being transferred to paper or the like again, and the application range of the polyester resin as a toner resin has been limited.

In recent years, the speed of copying machines, printers and the like has been remarkably increased, and the performance of toner used in such high-speed machines is required to be even higher. It is difficult to satisfy all the requirements such as fixing, no offset even at higher temperatures, stable image formation even when environmental conditions such as humidity fluctuate greatly, and rapid rise of charging. Was.

[0005] In order to satisfy this requirement, attempts have been made to increase the molecular weight of ordinary polyester resins by conducting an esterification reaction as they are, but no polyester resins having sufficient properties have yet been obtained.

In order to increase the molecular weight of the polyester resin,
There are three methods: a method of increasing the molecular weight of a linear polyester by a high vacuum reaction, a method of forming a branched structure by using a large amount of a trifunctional or higher-functional raw material component to form a branched structure, and a method of using the above together. Usually adopted.

[0007] In the case of a high vacuum decompression method, the reaction apparatus itself must be able to withstand a high degree of decompression operation, which is not a simple method. When a large amount of the branched component is used, the viscosity tends to increase rapidly in the latter half of the reaction,
There is a problem that it is difficult to control the reaction steps such as gelation of the whole reaction system.

[0008]

SUMMARY OF THE INVENTION The present invention provides a
Even when the feeding speed of the roller is increased, the electrostatic charge image can be fixed at a low temperature, and even at a higher temperature, the toner powder does not offset the fixing roll, so that the fixed image is not contaminated by the offset. It is another object of the present invention to provide a method for producing a polyester resin for an electrophotographic toner in which the charge rises quickly and the charge amount is stable without being affected by humidity.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies for solving the problems of the prior art, and as a result, they have been obtained by reacting a polyester resin with a vinyl polymer having an epoxy group. A modified polyester resin having a specific molecular weight distribution can be easily produced by a simple apparatus, and an electrophotographic toner containing the modified polyester resin as an essential component satisfies the above-mentioned problems. The inventors have found that the present invention has been completed.

That is, the present invention provides: A method for producing a modified polyester resin (C) for an electrophotographic toner, which comprises reacting a polyester resin (A) with an epoxy group-containing vinyl polymer (B), wherein the modified polyester resin (C) is tetrahydrofuran (THF) Gel permeation chromatography (GP
The molecular weight distribution curve obtained by the method C) has a molecular weight of 1,000 to 3,
A modified polyester resin for an electrophotographic toner, characterized in that the modified polyester resin has at least one peak in a region of 0,000 and at least one peak in a region of a molecular weight of 100,000 to 10,000,000 ( C)
1. A method for producing The acid value of the polyester resin (A) is 5 to 100 mgK
2. A method for producing the modified polyester resin (C) for electrophotographic toner as described in 1 above, which is OH / g. 3. The polyester resin (A) provides a method for producing a modified polyester resin (C) for an electrophotographic toner as described in (1) or (2) above, wherein a raw material having three or more functional groups is used; The modified polyester resin (C) for an electrophotographic toner according to any one of (1) to (3) above, wherein the epoxy equivalent of the epoxy group-containing vinyl polymer (B) is from 150 to 1,000.
4. A method for producing An object of the present invention is to provide an electrophotographic toner containing the modified polyester resin (C) obtained by the production method according to any one of the above 1 to 4 as an essential component.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a polyester resin for an electrophotographic toner according to the present invention will be described in detail.

The polyester resin (A) used in preparing the modified polyester resin (C) of the present invention is prepared by known and commonly used raw materials and production methods. The raw materials used at that time may be any known and commonly used raw materials constituting the polyester resin without any particular limitation. Typical raw materials used include polybasic acids such as dicarboxylic acids and reactive derivatives such as anhydrides or lower alkyl esters thereof, and polyhydric alcohols such as diol. Are preferably used.

The dicarboxylic acids include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, oxalic acid, malonic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, decane -1,10-
Aliphatic dibasic acids such as dicarboxylic acids; phthalic acid, phthalic anhydride, tetrahydrophthalic acid and its anhydride, hexahydrophthalic acid and its anhydride, tetrabromophthalic acid and its anhydride, tetrachlorophthalic acid and its anhydride Aromatic or alicyclic dibasic acids such as isophthalic acid, heptic acid and anhydride thereof, hymic acid and anhydride thereof, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid and 2,6-naphthalenedicarboxylic acid.

A carboxylic acid having three or more carboxyl groups in one molecule and a reactive derivative thereof can also be used as tribasic or higher polybasic acids.

[0015] Typical examples thereof include trimellitic acid, trimellitic anhydride, methylcyclohexentricarboxylic acid, methylcyclohexentricarboxylic anhydride, pyromellitic acid, pyromellitic anhydride and the like.

These polybasic acids or acid anhydrides may be used alone or in combination of two or more.

Further, as the above-mentioned polybasic acids, those in which part or all of the carboxyl group is an alkyl ester, an alkenyl ester or an aryl ester can be used.

When the polyester resin (A) is prepared, the raw material component may be, for example, hydroxy acid or 6-hydroxyhexanoic acid as a trifunctional raw material component such as dimethylolpropionic acid or dimethylolbutanoic acid. A compound having both a hydroxyl group and a carboxyl group in one molecule or a reactive derivative thereof can also be used.

Further, monobasic acids such as benzoic acid and p-tert-butylbenzoic acid can be used in combination as long as the effects of the present invention are not impaired.

Next, typical examples which can be used as the polyhydric alcohol component include ethylene glycol, 1,
2-propylene glycol, 1,4-butanediol,
1,5-pentanediole, 1,6-hexanediol-
, Diethylene glycol, dipropylene glycol,
Aliphatic diols such as triethylene glycol and neopentyl glycol; bisphenols such as bisphenol A and bisphenol F; ethylene oxide adducts of bisphenol A and bisphenol A Alkylene oxide adducts of bisphenol A such as propylene oxide adduct of aralkylene glycol or alicyclic diols such as xylylene diglycol, cyclohexane dimethanol and hydrogenated bisphenol A; Kind;

Further, monoepoxy compounds such as phenylglycidyl ether, "Kajura E10" (product name, monoglycidyl ester of branched fatty acid, manufactured by Shell Chemical Co., Ltd.) can also be used as such diols.

Compounds having three or more hydroxyl groups can also be used as the polyhydric alcohol component. Representative examples thereof include glycerin, trimethylolethane, trimethylolpropane, sorbitol, 1,2,3 , 6
-Hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, 2-methylpropanetriol, 1,3,5-trihydroxybenzene, tris (2-hydroxyethyl) And isocyanurate.

Further, the following polyepoxy compounds can also be used as polyhydric alcohols as a raw material component having three or more functional groups. For example, polyglycidyl ethers of various aliphatic or alicyclic polyols, such as ethylene glycol, hexanediol, neopentyl glycol, trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, sorbitol or hydrogenated bisphenol A; Hydroquinone,
Polyglycidyl ethers of compounds containing two of various phenolic hydroxyl groups, such as catechol, resorcin, bisphenol A, bisphenol S or bisphenol F; of compounds containing two of the above-mentioned phenolic hydroxyl groups Diglycidyl ethers of derivatives such as ethylene oxide or propylene oxide adducts;
Polyglycidyl ethers of various polyether polyols such as polyethylene glycol, polypropylene glycol or polytetramethylene glycol; polyglycidyl ethers of tris (2-hydroxyethyl) isocyanurate; adipic acid, butanetetracarboxylic acid, propanetricarboxylic acid Polyglycidyl esters of various aliphatic or aromatic polycarboxylic acids such as acid, phthalic acid, terephthalic acid or trimellitic acid; such as butadiene, hexadiene, octadiene, dodecadiene, cyclooctadiene, α-pinene or vinylcyclohexene Bisepoxides of various hydrocarbon dienes; bis (3,4-epoxycyclohexylmethyl) adipate or 3,4-epoxycyclohexylmethyl-3 Such as 4-epoxycyclohexyl carboxylate, various alicyclic polyepoxy compounds; or such as polybutadiene or polyisoprene, epoxidized various diene polymers; "EGM-
400 "[trade name of cyclic polysiloxane having a 3-glycidoxypropyl group, manufactured by Dow Corning Toray Silicone Co., Ltd.];

These polyhydric alcohols may be used alone or in combination of two or more. Further, in addition to these polyhydric alcohols, monovalent higher alcohols such as stearyl alcohol may be used in combination as long as the characteristics of the present invention are not impaired.

Among them, it is preferable to use a trifunctional or higher functional raw material component from the viewpoint of improving the offset resistance of the electrophotographic toner.

To prepare the polyester resin (A), a known and commonly used method can be used.

That is, for example, polyester resin (A)
As a method for preparing a polyester resin, there is a method of preparing a polyester resin by dehydrating and condensing the above-mentioned raw material components, that is, polybasic acids and polyhydric alcohols, under heating in a nitrogen atmosphere.

As the apparatus used at that time, a batch-type production apparatus such as a reaction vessel equipped with a nitrogen inlet, a thermometer, a stirrer, a rectification tower, etc. can be suitably used, and a deaeration port is provided. An extruder, a continuous reaction device, a kneader, and the like can also be used. Further, the esterification reaction can be promoted by appropriately reducing the pressure of the reaction system as required. Further, in order to accelerate the esterification reaction, a known and commonly used catalyst can be added.

Next, the properties of the modified polyester resin (A) of the present invention will be described.

The polyester resin (A) needs to have an appropriate amount of a hydroxyl group and / or a carboxyl group as a functional group that reacts with the epoxy group of the epoxy group-containing vinyl polymer (B).

More specifically, considering the reactivity with the epoxy group-containing vinyl polymer (B), the ease of production of the modified polyester resin (C), and the suitability as a toner binder, the polyester resin (A) Has a hydroxyl value of 5 to 5.
The range is preferably 100 mgKOH / g, and more preferably 8 to
More preferably, it is in the range of 70 mgKOH / g.
From the same viewpoint, the polyester resin (A) preferably has an acid value in the range of 5 to 100 mgKOH / g,
More preferably, it is in the range of 8 to 70 mgKOH / g.

Next, the epoxy group-containing vinyl polymer (B) of the present invention will be described.

The epoxy group-containing vinyl polymer (B) according to the present invention refers to a vinyl polymer having an epoxy group in a side chain.

The vinyl polymer (B) is composed of an epoxy group-containing vinyl monomer (b-1) and other monomers (b- It can be easily prepared by radical copolymerization with 2). As such a preparation method, a known and commonly used method can be used, but various polymerization methods such as a solution polymerization method, a non-aqueous dispersion polymerization method, and a bulk polymerization method can be used. Among them, the simplest method is a solution radical polymerization method in an organic solvent.

This solution radical polymerization method comprises a monomer containing the above monomer (b-1) as an essential component from the viewpoint of controlling the molecular weight of the epoxy group-containing vinyl polymer (B), easiness of production and the like. In this method, the mixture is subjected to solution radical polymerization under appropriate conditions, and then the solvent is distilled off from the obtained polymer solution to obtain a vinyl polymer (B).

As the apparatus used for preparing the epoxy group-containing vinyl polymer (B), those known and used, such as the apparatus used for preparing the polyester resin (A) described above, are used.

A specific adjustment method using this device is as follows. That is, a solvent such as xylene is charged into a reaction vessel equipped with a nitrogen inlet, a thermometer, a stirrer, a condenser, and the like, the temperature is raised to 80 to 140 ° C., and then the monomer mixture and the initiator are required for a predetermined time. And a polymerization reaction is carried out. After completion of the reaction, the solvent is distilled off by reducing the pressure of the reaction system, whereby the vinyl polymer (B) can be easily obtained.

The vinyl monomer having an epoxy group (b-1) used at this time includes glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate,
Examples include monomers such as 3,4-epoxycyclohexylmethyl (meth) acrylate, vinylcyclohexene oxide, glycidyl vinyl ether, methyl glycidyl vinyl ether and allyl glycidyl ether.

In preparing the vinyl polymer (B), a monomer (b-2) other than the monomer (b-1) is used.
Can also be used. Such another monomer (b-2)
As typical examples, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate , 2-ethylhexyl (meth)
Various esters of alkyl alcohol and (meth) acrylic acid, such as acrylate or lauryl (meth) acrylate; various aralkyl (meth) acrylates, such as benzyl (meth) acrylate or 2-phenylethyl (meth) acrylate; Various cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate or isobornyl (meth) acrylate; various ω-alkoxyalkyls such as 2-methoxyethyl (meth) acrylate or 4-methoxybutyl (meth) acrylate (Meth) acrylates; styrene, p-tert-butylstyrene, α-
Various aromatic vinyl monomers such as methyl styrene or vinyl toluene; various carboxylic acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl versatate or vinyl benzoate; crotone Alkyl esters of various crotonic acids, such as methyl acrylate or ethyl crotonate; dimethyl malate, di-n-butyl malate, dimethyl fumarate, di-n-butyl fumarate, dimethyl itaconate or di-n-butyl itaco Dialkyl esters of various unsaturated dibasic acids such as catenates; various cyano group-containing monomers such as (meth) acrylonitrile or crotononitrile; vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, chloro Trifluoroethylene or Kisa such as hexafluoropropylene, various fluoroolefins of; such as vinyl chloride or vinylidene chloride, various chlorinated olefins, ethylene, propylene, isobutylene, 1-butene or 1
Α-olefins such as -hexene; various alkyl vinyl ethers such as ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether or n-hexyl vinyl ether; various alkyl vinyl ethers; such as cyclopentyl vinyl ether, cyclohexyl vinyl ether or 4-methylcyclohexyl vinyl ether;
Various cycloalkyl vinyl ethers; N, N-dimethyl (meth) acrylamide, N- (meth) acryloylmorpholine, N- (meth) acryloylpyrrolidine,
Tertiary amide group-containing monomers such as N-vinylpyrrolidone; esters of (meth) acrylic acid with polyethers having one hydroxyl group in one molecule such as methoxypolyethylene glycol or methoxypolypropylene glycol Polyhydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate;
Hydroxypropyl (meth) acrylate or 4-
Hydroxyalkyl (meth) acrylates, such as hydroxybutyl (meth) acrylate; various hydroxyl-containing vinyl ethers, such as 2-hydroxyethyl vinyl ether or 4-hydroxybutyl vinyl ether; various hydroxyl groups, such as 2-hydroxyethyl allyl ether Containing allyl ethers; various polyoxyalkylene glycols obtained from various polyether polyols represented by polyethylene glycol and various unsaturated carboxylic acids represented by (meth) acrylic acid Monoesters; adducts of hydroxyl group-containing monomers with various lactones such as ε-caprolactone; or various epoxy group-containing such as glycidyl (meth) acrylate Unsaturated monomer and vinegar Adducts with various acids as represented by: 2,3-carbonatepropyl (meth) acrylate, 2-methyl-2,3-carbonatepropyl (meth) acrylate, 3,4-carbonatebutyl (meth) Acrylate, 3-methyl-3,4-carbonate butyl (meth) acrylate, 4-methyl-3,4
-Carbonate butyl (meth) acrylate, 4,5-
Carbonate pentyl (meth) acrylate, 6,7-
Carbonate hexyl (meth) acrylate, 5-ethyl-5,6-carbonate hexyl (meth) acrylate or 7,8-carbonate octyl (meth) acrylate, 2,3-carbonate propyl vinyl ether, di (2,3-carbonate propyl) 5-membered cyclocarbonate group-containing vinyl monomers such as malate or di (2,3-carbonatepropyl) itaconate; and the like.

The epoxy equivalent of the epoxy group-containing vinyl polymer (B) prepared by such a method has an epoxy equivalent of 150 in consideration of the reactivity with the polyester resin (A) and the performance of the electrophotographic toner. The range is preferably from 5,000 to 5,000 g / mol, and more preferably from 300 to 1,500.

In consideration of the production stability of the epoxy group-containing vinyl polymer (B) and the compatibility and reactivity with the polyester resin (A), the epoxy group-containing vinyl polymer (B) is The number average molecular weight (hereinafter referred to as “Mn”) is preferably in the range of 500 to 10,000, and more preferably in the range of 1,000 to 6,000.

Next, a method for producing the modified polyester resin (C) according to the present invention will be described.

The production method according to the present invention comprises reacting a polyester resin (A) with an epoxy group-containing vinyl polymer (B) to produce a modified polyester resin (C) having a specific molecular weight distribution. Features.

More specifically, the production method according to the present invention comprises a polyester resin (A) having a hydroxyl group and / or a carboxyl group and an epoxy group of a vinyl polymer (B). The modified polyester resin (C) is obtained by forming a chemical bond between the resin (A) and the vinyl polymer (B).

As the apparatus used in the production method according to the present invention, the above-mentioned known and commonly used apparatus can be used. That is, a batch-type manufacturing apparatus such as a reaction vessel equipped with a nitrogen inlet, a thermometer, a stirrer, a rectification column or a reflux condenser can be suitably used, and a screw extruder equipped with a deaeration port or A continuous reaction apparatus, a single-screw or twin-screw kneader, or the like can be used.

The reaction in the production method according to the present invention is preferably performed in a nitrogen atmosphere in order to prevent oxidation of products and the like.

Although the production method according to the present invention is not particularly limited, the polyester resin (A) is heated and melted at a temperature not lower than its melting point, and the vinyl polymer (B) is gradually charged therein. The simplest method is to obtain the desired modified polyester resin (C) by monitoring the acid value, viscosity and the like of the reaction system while uniformly stirring and mixing.

The polyester resin (A) and the vinyl polymer (B) when the modified polyester resin (C) is obtained by the reaction between the polyester resin (A) and the vinyl polymer (B)
Is not particularly limited, but the weight of the polyester resin (A) is represented by Wa, and the weight of the vinyl polymer (B) is represented by W.
b, considering the effects of the present invention and the ease of production of the modified polyester resin (C), Wb / Wa = 0.
It is preferably in the range of 01 to 0.5, and
It is more preferable that b / Wa is in the range of 0.03 to 0.2.

The reaction temperature at the time of reacting the polyester resin (A) with the vinyl polymer (B) is not particularly limited, but from the viewpoint of accelerating the reaction and suppressing side reactions, etc.
A range of 50 ° C to 300 ° C is preferable, and a range of 180 ° C to 2 ° C.
A range of 50 ° C. is more preferred.

The modified polyester resin (C) according to the present invention
Is used as a binder for an electrophotographic toner, and therefore must have appropriate properties such as pulverizability, melt viscosity and glass transition temperature. From such a viewpoint, the number average molecular weight (hereinafter, referred to as “Mn”) of the modified polyester resin (C) is preferably from 1,000 to 10,000.
, More preferably in the range of 2,000 to 6,000, and the weight average molecular weight (hereinafter referred to as “Mw”) is preferably in the range of 6,000 to 500,000, more preferably Is between 10,000 and 400,
000 is desirable.

The temperature at which the melt viscosity of the modified polyester resin (C) becomes 100,000 poise (hereinafter referred to as "T5") is preferably in the range of 80 to 200 ° C.
The temperature is more preferably in the range of 0 ° C to 160 ° C. The glass transition temperature (hereinafter referred to as “Tg”) is
A range of 50 ° C to 100 ° C is preferred, and 60 ° C to 80 ° C.
More preferably, it is in the range of ° C.

In order for an electrophotographic toner to have contradictory properties such as low-temperature fixability and high-temperature offset resistance, it is necessary that the modified polyester resin has a specific molecular weight distribution. That is, the modified polyester resin has at least one peak in a molecular weight range of 1,000 to 30,000 and a molecular weight of 100,000 to 1 in a molecular weight distribution curve by GPC of the THF-soluble component.
It must have at least one peak in the region of 0,000,000.

Here, the "peak" means a maximum value or a shoulder portion (shoulder portion) in a molecular weight distribution curve by GPC of a THF-soluble component of the modified polyester resin (C).

FIG. 1 shows a specific example of such a molecular weight distribution curve.

FIG. 1 shows an example of a distribution curve of the weight fraction of the molecular weight according to the GPC method.
0000 area (the horizontal axis LogM in the figure is 3.00 to
4.20 region) and a molecular weight M of 10
FIG. 4 shows a molecular weight distribution curve of the modified polyester resin (C) having a shoulder portion in a region of 0000 to 10,000,000 (a region where the horizontal axis LogM is 5.00 to 7.00 in the drawing). is there. The LogM on the horizontal axis in the figure represents the logarithmic value of the molecular weight M in terms of polystyrene, and the left vertical axis dW / d (Lo
gM) indicates the weight fraction of the molecule having the molecular weight M, the right vertical axis% indicates the integrated value of the molecular weight M and the weight W thereof, and the overall shape of the molecular weight distribution is a curve represented by dW / d (LogM). expressed.

The polyester resin having such a molecular weight distribution curve can be easily and easily produced by reacting the polyester resin (A) according to the present invention with the epoxy group-containing vinyl polymer (B).

Next, an electrophotographic toner using the modified polyester resin of the present invention will be described.

The toner for electrophotography of the present invention contains the modified polyester resin (C) as an essential component, and is usually prepared by blending other components exemplified below.

Other components used include a colorant, a charge controlling agent, a wax, a flow regulator and the like.

Typical examples of the coloring agent that can be used include black toners such as various types produced by thermal black method, acetylene black method, channel black method, furnace black method, lamp black method and the like. Carbon black and phthalocyanine bull, aniline bull, calco oil bull, ultra marine bull, methylene bull chloride, malachite green oxalate, chrome yellow, quinoline yellow, Dupont There are pigments such as oil red and rose bengal, and nigrosine-based or rhodamine-based dyes, and mixtures thereof can also be used.

As the charge controlling agent, various substances from low molecular weight compounds to high molecular weight compounds can be used. Typical examples thereof include homopolymerization or copolymerization of a nigrosine dye, a quaternary ammonium compound and a monomer having an amino group. There are polymer compounds obtained by polymerization, organometallic complexes, chelate compounds and the like.

Wax is added to assist in preventing toner from adhering to a fixing roll of a copying machine or a printer. Representative examples include natural waxes and various polyolefins.

The flow control agent is added to improve the flowability of the toner. For example, fine powder of vinylidene fluoride, fine powder of polytetrafluoroethylene, fine powder of silica by a wet method or a dry method, or the like may be used. it can.

Next, a method of manufacturing an electrophotographic toner according to the present invention will be described.

The toner for electrophotography according to the present invention is prepared by a known and commonly used method. One of the typical production methods is as follows. First, the modified polyester resin (C) according to the present invention, which is an essential component, is mixed with a coloring agent, a charge controlling agent, and a wax at a predetermined ratio using a Henschel mixer. I do. The mixture is melt-kneaded in a biaxial kneader in a temperature range of about 150 ° C. to 200 ° C., cooled, coarsely ground by a cutting mill, and finely ground by a jet mill to have an average particle size of about 7 μm. Classify the wind so that An electrophotographic toner can be prepared from the polyester resin according to the present invention by mixing the thus obtained finely pulverized product and the flow control agent at a predetermined ratio with a Henschel mixer.

Further, the toner for electrophotography according to the present invention
Can also be prepared, for example, by the method disclosed in JP-A-9-31502. That is,
It can also be prepared by a method in which a toner precursor is dispersed in water in advance and then powdered.

[0067]

Next, the present invention will be described specifically with reference to examples. However, the technical scope of the present invention is not limited to the following embodiments. In the examples, “parts” means “parts by weight” unless otherwise specified.

Synthesis Example 1 [Synthesis Example of Polyester Resin (A)] Ethylene glycol 46 was placed in a 5-liter flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a rectification tower.
9 parts, 788 parts of neopentyl glycol, 468 parts of isophthalic acid and 1,800 parts of terephthalic acid
After a certain time, the temperature was raised to 190 ° C., and after confirming that the inside of the reaction system was uniformly stirred, 1.5 parts of dibutyltin oxide was added. The temperature was increased while evaporating water generated from the same temperature to 240 ° C. over a further 6 hours, and the dehydration / condensation reaction was further continued at the same temperature for 3 hours, and finally the acid value was 5.7 mgKOH / g, Hydroxyl value is 44mg
KOH / g, softening point by ring and ball method is 104 ° C, GPC
Has a number average molecular weight (abbreviated as Mn) of 2,700,
A polyester resin having a weight average molecular weight (abbreviated as Mw) of 6,300 was obtained. This is a polyester resin (A
Abbreviated as -1).

Synthesis Example 2 Same as above Synthesis Example 1 except that 426 parts of ethylene glycol, 715 parts of neopentyl glycol, 73 parts of trimethylolpropane, 468 parts of isophthalic acid and 1,800 parts of terephthalic acid were used. The acid value is exactly 7.4 mg
KOH / g, hydroxyl value: 41 mgKOH / g, softening point by ring and ball method: 112 ° C., number average molecular weight (Mn) by GPC: 3,400, weight average molecular weight (Mw): 1
A polyester resin of 0.200 was obtained. This is abbreviated as polyester resin (A-2).

Synthesis Example 3 [Synthesis Example of Epoxy Group-Containing Vinyl Polymer (B)] In a flask having a 5 liter internal volume equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, 1,600 xylene was added.
Then, the temperature was increased to 135 ° C.

Then, at the same temperature, 1,440 parts of methyl methacrylate and 120 parts of n-butyl methacrylate
, A mixture of 840 parts of glycidyl methacrylate and 144 parts of t-butylperoxy-2-ethylhexanoate was added dropwise over a period of 6 hours.
And the polymerization reaction was continued for another 6 hours.

Then, under reduced pressure of 30 mmHg, xylene was distilled off from the contents of the flask to the outside of the system.
Mn is 2,600, Mw is 5,700, the softening point by the ring and ball method is 110 ° C., and the epoxy equivalent is 430.
g / mol of an epoxy group-containing vinyl polymer was obtained. This is abbreviated as vinyl polymer (B-1).

Synthesis Example 4 [Same as above] The vinyl monomer used was 1,440 parts of styrene,
120 parts of n-butyl methacrylate and 840 parts of glycidyl methacrylate were used, and the polymerization initiator was changed to 144 parts of t-butyl peroxy-2-ethylhexanoate. And the Mn by GPC method was 2,1 in exactly the same manner as in Synthesis Example 4.
00, Mw is 4,300, and softening point by ring and ball method is 10
At 5 ° C., an epoxy group-containing vinyl polymer having an epoxy equivalent of 420 g / mol was obtained. This is abbreviated as vinyl polymer (B-2).

Example 1 Preparation Example of Modified Polyester Resin (C) A polyester resin (A-A) was placed in a 5-liter flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser.
2,000 parts of 1) were charged, and the temperature was raised so as to enable stirring, and the temperature was kept at 230 ° C. Then, 140 parts of the vinyl polymer (B-1) was added, and the mixture was stirred and mixed uniformly, and reacted at the same temperature for 3 hours. As a result, T5 was 123 ° C., M
n is 3,200, Mw is 83,000, and Tg is 60
° C modified polyester resin was obtained. This is abbreviated as modified polyester resin (C-1). This modified polyester resin (C-1) has a peak at a position of about 8,500 in the molecular weight distribution curve and has a molecular weight of 10
It had a shoulder portion in the range from 0000 to 10,000,000.

Example 2 Same as in Example 1 except that the polyester resin (A-2) was used instead of the polyester resin (A-1), and T5 was 139 ° C. and Mn was 3,400. , Mw is 19
A modified polyester resin having a Tg of 62.degree. This is abbreviated as modified polyester resin (C-2). This modified polyester resin (C-2) has a peak at a molecular weight of about 10,000 in the molecular weight distribution curve.
Having a molecular weight of 100,000 to 10,000.
It had a shoulder portion in the area of 000.

Example 3 Same as in Example 1 except that the epoxy group-containing vinyl polymer (B-2) was used instead of the epoxy group-containing vinyl polymer (B-1). T5 is 128 ° C., Mn is 3,000, Mw is 100,000, and Tg is 60.
° C modified polyester resin was obtained. This is abbreviated as modified polyester resin (C-3). This modified polyester resin (C-3) has a peak at a position of about 9,000 in the molecular weight distribution curve and has a molecular weight of 10
It had a shoulder portion in the range from 0000 to 10,000,000.

Example 4 Same as in Example 2 except that the epoxy group-containing vinyl polymer (B-2) was used in place of the epoxy group-containing vinyl polymer (B-1). T5 is 137 ° C., Mn is 3,000, Mw is 170,000, and Tg is 61
° C modified polyester resin was obtained. This is abbreviated as modified polyester resin (C-4). This modified polyester resin (C-4) has a peak at a position where the molecular weight is about 12,000 in the molecular weight distribution curve, and has a molecular weight of 1
It had a shoulder portion in the region from 00,000 to 10,000,000.

The molecular weight and the molecular weight distribution in the above Examples were determined by the GPC method. Measurements were taken by Shodex GP
C SYSTEM-21 (manufactured by Showa Denko KK) was used.

The temperature (T5) at which the viscosity of the resin becomes 100,000 poise in the measurement of the melt viscosity at a constant rate with a Koka type flow tester is determined by the Koka type flow tester (CFT-500 manufactured by Shimadzu Corporation). ) At a heating rate of 6 ° C /
The results are shown under the conditions of a load of 10 kg and a die of 1 mmφ × 1 mm.

Comparative Example 1 [Preparation Example of Comparative Unmodified Polyester Resin] 386 parts of ethylene glycol, 650 parts of neopentyl glycol, 174 parts of trimethylolpropane, and 2,277 parts of terephthalic acid were used. The acid value was 10 mg KOH / g, the hydroxyl value was 31 mg KOH / g, and the viscosity of the resin was 100,000 poise in a constant-rate temperature rise measurement of the melt viscosity using a Koka flow tester. Polyester having a temperature (T5) of 141 ° C., a number average molecular weight (Mn) of 3,200 by GPC, a weight average molecular weight (Mw) of 140,000, and a glass transition temperature (Tg) of 66 ° C. by DSC A resin was obtained. This is abbreviated as a comparative polyester resin (A ′).

The polyester resin for comparison (A
') In the molecular weight distribution curve of the THF-soluble component by GPC (hereinafter referred to as “molecular weight distribution curve”).
It had a peak at a molecular weight of about 8,500, but had almost no shoulder in the molecular weight range of 100,000 to 10,000,000.

However, in the latter stage of the dehydration condensation reaction at 240 ° C., the dehydration condensation reaction became extremely slow. Therefore, treatments such as advancing the dehydration reaction under reduced pressure of the reaction system were performed, but gelation often occurred with a rapid increase in viscosity.

Examples 5 to 8 and Comparative Example 2 [Preparation and Evaluation of Toner] Modified polyester resins (C-1) to (C-4) synthesized in Examples 1 to 4 and comparative control resin (A ') )
The toner is prepared according to the composition shown in Table 1 below, and the fixing lower limit temperature (abbreviated as “Tl”) and the non-offset upper limit temperature (“Tu”) are determined using the fixing roll of an actual copying machine. Abbreviated as "). The toner by the blow-off method
Was evaluated for its charge amount and storage stability.

The toner was prepared by curing the modified polyester resin of the present invention and the polyester resin for comparison and control, respectively.
Bonn black, a charge controlling agent and a low molecular weight polypropylene wax are mixed at a predetermined ratio, and then mixed with a twin-screw kneader.
The mixture was melt-kneaded at a temperature of 60 ° C., and the kneaded product was cooled, coarsely pulverized, and further finely pulverized by a jet mill, and subjected to an air classifier so as to obtain toner particles having an average particle size of about 7 μm.

This toner was mixed with iron oxide powder (average particle diameter: 100 μm) so that the toner concentration was 4% by weight, to obtain an electrophotographic developer. Using this developer, the charge amount after standing under normal humidity conditions and high humidity conditions was measured. Further, a developer was separately prepared so that the toner concentration became 10% by weight, and used for fixing / offset and evaluation of images.

The fixing / offset was evaluated by preparing unfixed black solid band images (width 2 cm) on A4 size plain paper in advance for the number of sheets corresponding to the fixing temperature of each measurement. The fixing temperature was evaluated at a temperature at which toner was not adhered to the absorbent cotton by rubbing the obtained image with absorbent cotton by fixing the obtained image through a fixing portion of a copier modified so as to be able to set arbitrarily. The non-offset upper limit temperature was evaluated by visual evaluation as a temperature at which the toner which was offset from the fixing roll and adhered to a white portion other than the fixed image of the plain paper did not adhere to the image again. . The evaluation results are also shown in Table 1.

[0087]

[Table 1]

(Note) 1) The numbers in the mixing ratio represent parts by weight.

2) Carbon black # 44: Carbon black manufactured by Mitsubishi Chemical Corporation 3) BONTRON N-04: Charge control agent manufactured by Orient Chemical Co., Ltd. (for positive charging) 4) Pescol 550P: low molecular weight polypropylene wax manufactured by Sanyo Chemical Co., Ltd. 5) The normal condition of the charge amount was 25 ° C., the toner was left at 60% relative humidity for 48 hours or more. This means that the toner was left at 80% relative humidity for 48 hours and then measured.

6) The storage stability is a result of visually evaluating the blocking state of each toner powder after storing each toner at 50 ° C. and a relative humidity of 40% for 24 hours.

Here, “good” means that the toner powder maintains fluidity with little change from before storage.
"Defective" indicates a state in which the toner powder is totally agglomerated.

[0092]

According to the production method of the present invention, it is possible to easily obtain a modified polyester resin having a predetermined molecular weight distribution while greatly reducing the problem of gelation. Further, the electrophotographic toner using such a modified polyester resin as a binder is capable of fixing at a low temperature, is not offset even at a high temperature, and has excellent storage stability and is extremely practical.

[Brief description of the drawings]

FIG. 1 is a distribution curve of the weight fraction of the molecular weight of the modified polyester resin of the present invention by the GPC method.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masanobu Nakamura 1-17-30 Chuo Warabi, Saitama Prefecture 1-709 Rene Warabi 1-709 (72) Inventor Hideki Grimbayashi 3-5-11 Honmachi, Omiya City, Saitama F-term ( Reference) 2H005 AA01 AB02 CA02 CA07 CA08 CA18 DA06 DA10 DA10 EA06 EA10

Claims (5)

[Claims] 1. A method for producing a modified polyester resin (C) for an electrophotographic toner, comprising reacting a polyester resin (A) with an epoxy group-containing vinyl polymer (B), wherein the modified polyester resin (C) is , Tetrahydrofuran (T
HF) The molecular weight distribution curve by gel permeation chromatography (GPC) of the soluble component is
It has at least one peak in the range of 00 to 30,000, and has a molecular weight of 100,000 to 10,000,000.
A method for producing a modified polyester resin (C) for an electrophotographic toner, wherein the modified polyester resin (C) has at least one peak in a 0 region. 2. The method for producing a modified polyester resin for electrophotographic toner (C) according to claim 1, wherein said polyester resin (A) has an acid value of 5 to 100 mgKOH / g. 3. The method for producing a modified polyester resin (C) for an electrophotographic toner according to claim 1, wherein the polyester resin (A) uses a raw material component having three or more functionalities. 4. The modified polyester resin for an electrophotographic toner according to claim 1, wherein said epoxy group-containing vinyl polymer (B) has an epoxy equivalent of 150 to 5,000 g / mol. Manufacturing method. 5. An electrophotographic toner containing the modified polyester resin (C) obtained by the production method according to claim 1 as an essential component.