JPH02881A - Binder for toner - Google Patents

Abstract

PURPOSE:To obtain the good quality of the image which withstands long-term continuous use by incorporating a block polymer formed by esterifying a polyester resin having a specific hydroxyl group value and a styrene resin into the binder. CONSTITUTION:The block polymer formed by esterifying the polyester resin having 30-60 hydroxyl group value and <=5 acid value and the styrene resin having 1-10 acid value and 5,000-500,000mol.wt. is incorporated into the binder. The polyester resin is exemplified by, for example, the condensation polymer of polyhydric alcohol and polybasic acid. The polyhydric alcohol is preferably ethylene glycol, neopentyl glycol and bisphenols added with 2-3mol alkylene oxide, and mixtures composed of >=two kinds thereof. The stable sea and island structure having the sufficient dipsersibility of the polyester and vinyl resin is obtd. in this way and the stabilization of the image at the time of the long- term use is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a binder for toner. More specifically, the present invention relates to a binder for electrophotographic toner that exhibits a stable microphase split state even when subjected to thermal and mechanical energy loads.

[Prior Art] Conventionally, there are binders for electrophotographic toners that are mechanically mixed polyester and vinyl resin (for example, Japanese Patent Laid-Open No. 49-6931 and Japanese Patent Laid-Open No. 54-114).
Publication No. 245).

[Problems to be Solved by the Invention] However, polyester and vinyl resin have poor compatibility, and the system according to the above technology takes an unrestricted-dispersion state and takes a seabird state. This sea-island structure is necessary in order to simultaneously titrate the thermal properties necessary for a toner, such as good fixing properties at low temperatures and hot offset resistance at high temperatures. During toner production, when heat and mechanical energy are applied for kneading with carbon, the toner may break or, in extreme cases, the two components may completely separate. In operations such as melting and kneading to form toner, the average particle size of the islands is equal to or exceeds the average particle size of the toner, resulting in a decrease in image characteristics due to non-uniform charging of the toner, such as image instability during long-term use. A problem arises.

[Means for Solving the Problems] The present inventors have arrived at the present invention as a result of intensive studies on an electrophotographic toner binder having a stable seabird structure with sufficient dispersibility of polyester and vinyl resin.

That is, the present invention uses a polyester resin (b) having a hydroxyl value of 30 to 60 and an acid value of 5 or less, an acid value of -10 and a molecular weight of 5,000 to 500.
．． A binder for an electrophotographic toner comprising a block polymer obtained by esterifying an OOO type styrene resin (a), and (1) a styrene resin (
A), (2) a polyester resin (B) which is substantially incompatible with this, and (3) a resin (C) having a polystyrene resin structure and a polyester resin structure in one molecule as essential components. This is a toner binder for electrophotography.

(3) Polystyrene resin (resin having rζ structure and polyester resin structure in one molecule) according to the present invention (c
), a polyester resin (b) having a hydroxyl value of 30 to 60 and an acid value of 5 or less, and a polyester resin (b) having an acid value of 1 to 1
O and has a molecular weight of 5. A block polymer obtained by esterifying a styrenic resin (a) having a molecular weight of 500,000 to 500,000 is exemplified.

Examples of the polyester resin (b) include condensation products of polyhydric alcohols and polybasic acids.

Polyhydric alcohols include (1) ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, l,4-butanediol, neopentyl glycol,
Aliphatic glycols such as 1.6-hexanediol and their alkylene oxides [ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as P
(2) Hydroquinone, catechol, resorcinol, pyrogallol, bisphenols (bisphenol A1, bisphenol F, bisphenol sulfone, etc.) and hydrogenated bisphenols with alkylene oxides (EO and/or PO);
); (3) glycerin, trimethylolpropane, trimethylolethane, hexanetriol, pentaerythritol,
diglycerin, α-methyl glucoside, sorbitol,
xylit, mannitol, glucose, fructose,
Tri- to octavalent alcohols such as sia sugar and their alkylene oxide adducts; (4) Alkanolamines (triethanolamine, tripropaturamine, etc.), alkylene diamines (carbon numbers 2 to B) [ethylene diamine, hexa Polyalkylene such as methylene diamine (alkylene has 2 to 2 carbon atoms)
6) Polyamines [diethylenetriamine, triethylenetriamine, etc.], aromatic amines (aniline, phenylenediamine, diaminotoluene, xylylenediamine, methylenedianiline, diethyltolylenediamine, sophenyl ether diamine, etc.), alicyclic amines (in phorondiamine, cyclohexylmethanediamine, cyclohexylene diamine, etc.), heterocyclic amines (piperazine, aminoethylpiperazine, etc.)
Examples include amine group-containing polyhydric alcohols prepared by adding alkylene oxide (EO and/or PO) to such as those described in Japanese Patent No. 1044; and mixtures of two or more of these.

Among these, preferred are ethylene glycol, neopentyl glycol, and bisphenols (especially bisphenol A) with 2 to 3 moles of alkylene oxide added, and mixtures of two or more of these. Particularly preferred are bisphenol A. neopentyl glycol, and mixtures of two or more of these. The use of neopentyl glycol improves the crushability of the resulting polyester resin.

Polybasic acids include (1) succinic acid, maleic acid, fumaric acid, itaconic acid, azelaic acid, mesaconic acid, citraconic acid, cehatic acid, curtaconic acid, adipic acid, malonic acid, phthalic acid, isophthalic acid, terephthalic acid, Dibasic acids such as cyclohexanedicarboxylic acid, nadic acid, methylnadic acid, octylsuccinic acid, dodecenylsuccinic acid; (2) trimellitic acid, 1,2.4-cyclohexanedicarboxylic acid, 2,5.7-naphthalene tricarboxylic acid,
! .

2.4-butanetricarboxylic acid, 1,2.5-hexanetricarboxylic acid, 1.3-dicarboxyl-2-methyl-2-methylenecarboxypropane, pyromellitic acid,
Trivalent or higher polybasic acids such as benzophenonetetracarboxylic acid, cyclopentadienetetracarboxylic acid, tetra(methylenecarboxyl)methane, 1.2.7.8-octanetetracarboxylic acid; (3) Other polybasic acids such as sulfuric acid Polymerized fatty acids such as monomers and trimers; and anhydrides and lower alkyl esters of these acids can also be used.

Among these are succinic acid, maleic acid, fumaric acid,
Preferred are phthalic acid, isophthalic acid, terephthalic acid, and alkyl or alkenyl (alkyl group or alkenyl group having 4 to 18 carbon atoms) succinic acid represented by octylsuccinic acid and dodecenylsuccinic acid.

The polyester resin (b) according to the present invention is preferably a linear type, but a trihydric or higher alcohol such as trimethylolpropane and/or a trivalent or higher polybasic acid such as trimellitic acid may be used with a small ff1 (Usually 30 mol% or less, preferably 1% in polyhydric alcohol and polybasic acid)
0 mol % or less) can also be used. Furthermore, in addition to polyhydric alcohols and polybasic acids, amide bond-containing polyester resins produced using small amounts of polyamines such as hexamethylene diamine and methylene diamine can also be used as the polyester resins according to the present invention. I can do it.

In order to obtain a polyester resin (b) having an acid value of 5 or less and a hydroxyl value of 30 to 60, the molar ratio of polyhydric alcohol and polybasic acid is usually as follows:
S: 1-1.1:1, preferably 1.4:1-1°2=1.

The polyesterification reaction is carried out, if necessary, in the presence of an esterification catalyst (e.g. zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, etc.), usually at a concentration of 150 to 25
It can be carried out at any temperature of 0°C. In addition, the reaction can be carried out under normal pressure or reduced pressure, and with an inert gas or solvent (e.g.
It can be carried out in the presence or absence of toluene, xylene, etc.).

The end point of the reaction is determined by follow-up analysis of the acid value and hydroxyl value, and when the acid value and hydroxyl value are 5 or less and 30 to 60, respectively, the reaction is completed.If the acid value exceeds 5 in the obtained polyester resin, the hydroxyl value is 30 or less. If the hydroxyl value is less than 60, it will be difficult to obtain a block polymer, and if the hydroxyl value exceeds 60, the temperature at which the toner offsets the heat roll (hereinafter abbreviated as HO) will drop, making it difficult to use.

As the styrenic resin (a), styrenic monomer (meth)acrylic monomer [acrylic monomer and/or
Or it means a methacrylic monomer. This expression will be used below. Examples include resins obtained by polymerizing polyfunctional polymers and other monomers using a carboxyl group-containing polymerization initiator.

Examples of styrene monomers include styrene, alkylstyrenes (eg, α-methylstyrene, p-methylstyrene), and the like. Preferably it is styrene.

As a (meth)acrylic monomer, alkyl (meth)
Acrylates [alkyl having 1 to 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate Acrylates, etc., hydroxyl group-containing (meth)acrylates, hydroxyl ethyl (meth)acrylates, etc., amine group-containing (meth)acrylates [dimethylaminoethyl (meth)acrylate, diethylamine ethyl (meth)acrylate, etc., nitrile group-containing (Meth)acrylic compounds [such as acrylonitrile and (meth)acrylic acid can be mentioned. Among these, alkyl (meth)acrylates are preferred, and methyl (meth)acrylates are particularly preferred.
meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, (meth)acrylic acid, and mixtures of two or more thereof.

In order to obtain higher molecular weight polymers during polymerization, polyfunctional monomers containing at least two polymerizable double bonds [e.g. di- or polyvinyl compounds (divinylbenzene, divinyltoluene, ethylene glycol diacrylate,
1, 6-hexanediol diacrylate, etc.) can be added.

Preferred are divinylbenzene and 1,6-hexanediol diacrylate.

Other monomers include vinyl esters (eg, vinyl acetate, vinyl propionate, etc.) and aliphatic hydrocarbon monomers (eg, butadiene, etc.).

The amounts of these monomers are as follows, based on the total ff1 dish of all monomers. Styrenic monomers are usually 50
~90%, preferably 55-85%. (
The amount of meth)acrylic monomer is usually 50 to 10%, preferably 45 to 15%. 9 plates of styrene monomer
0% and the amount of (meth)acrylic monomer is 10%
If it is less than %, the toner minimum fixing temperature (hereinafter abbreviated as MF) will be high, and conversely, if each (■) is less than 50% and exceeds 50%, the temperature at which the toner causes offset to the heat roll (hereinafter abbreviated as HO) will be low. In addition, the blocking properties of the toner are also poor.

In addition, the polyfunctional monomer is usually 39A or less, preferably 1%
It is as follows. If the amount of polyfunctional monomer exceeds 3%, gelation occurs during polymerization.

The content of other monomers such as vinyl esters and aliphatic hydrocarbon monomers is usually 10% or less, preferably 5% or less.

Examples of the carboxyl group-containing polymerization initiator include 4,4'-azobis(4-cyanopentanoic acid) [trade name V-501, manufactured by Wako Saiyaku Co., Ltd.].

The amount of initiator is usually 0.000, based on the weight of total monomer.
It is 2 to 1.5%.

Polymerization is usually carried out by solution polymerization or suspension polymerization, and solution polymerization is preferred.

In the case of solution polymerization, the solvent is an aromatic hydrocarbon solvent (
toluene, xylene, etc.), chlorinated solvents (chloroform, carbon tetrachloride, ethylene dichloride, ethylene tetrachloride, etc.)
, ether solvents (l,4-dioxane, etc.), and mixed solvents of two or more thereof. The amount of solvent used is usually 10 to 1000% based on the total weight of monomers.
, preferably 30 to 400%. The amount of solvent used is 1
If it is less than 0%, the dispersion of each component is insufficient, and 1,000%
%, production efficiency decreases.

The polymerization reaction is usually carried out in an atmosphere of an inert gas such as nitrogen. Polymerization temperature is usually 50 to 200°C, preferably 7
The temperature is 0 to 150°C. If the temperature is lower than 50°C, the initiation ability of the polymerization initiator will be low. If the temperature exceeds 200°C, the polymer may decompose. The reaction time depends on other conditions, but is usually 1 to 50 hours, preferably 2 to 10 hours. When the reaction time is shorter than 1 hour, it is often difficult to control the reaction, and when it exceeds 50 hours, it is economically disadvantageous. The solvent used in polymerization is referred to as the solvent used after polymerization. Solvent removal is performed under normal pressure or reduced pressure.

The acid value of the styrenic resin (a) according to the present invention is 1 to 10.
° Preferably it is 2-8. If the acid value is less than 1, it will be difficult to obtain a block polymer, and if the acid value exceeds 10, the glass transition point (hereinafter abbreviated as Tg) of the toner will be low (and the blocking property will be poor). 5゜000~50
0.0001 Preferably 10,000 to 400,0
It is 00.

When the molecular weight exceeds 500,000, the minimum fixing temperature (hereinafter abbreviated as MF) of the toner increases, making it difficult to use.

If the molecular weight is less than 5,000, the glass transition point (hereinafter abbreviated as Tg) of the toner will be low and blocking properties will be poor.

The molecule ■ is tetrahydrofuran (hereinafter TH) as a solvent.
It is measured by gel permeation chromatography (hereinafter abbreviated as GPC) using GPC (hereinafter abbreviated as GPC), converted to standard polystyrene, and expressed as a weight average.

The acid value and molecular weight of the styrenic resin (a) can be adjusted by adjusting the polymerization conditions, such as the amount of initiator, the amount of polyfunctional monomer, and the amount of solvent.

The block polymer consisting of polyester resin (b) and styrene resin (a) usually has a ratio of 20:80 to 80:
It can be obtained by blending and esterifying in a weight ratio of 0 to 70:30, preferably 20° to 30°. The esterification reaction can be carried out by melt-blending the polyester resin and the styrene resin after removing the solvent, or by adding the polyester resin to the polymerization reaction solution of the styrene resin, mixing it, and removing the solvent. can. The latter is preferable from the viewpoint of simplifying the reaction process. The reaction is usually carried out at a temperature of 150-250"C.
This can be carried out under reduced pressure of about 0m+nHg. Moreover, if necessary, the esterification catalyst described in the section of the polymerization of the polyester resin can also be used. The end point of esterification is defined as the point in time when the acid value at the start of esterification becomes 1/2 or less. It usually takes 5 to 20 hours.

The glass transition point of the binder obtained by esterifying polyester resin and styrene resin is usually 40 to 80''.
C, and preferably 45 to 70'C for electrophotographic toner, which is the application of this binder.

If the glass transition point is less than 40''C, the toner will have poor storage stability, and if it exceeds 80''C, the MF will be high and it will be difficult to put it to practical use as a toner.

In the present invention, further other (+) styrenic resin (A),
Other (2) polyester resin (B) and low molecular weight polyolefin which are substantially incompatible with this can also be added.

As the other constituent monomers of the styrene resin (A), those described in the section of the block polymer above can be used, and the preferable ones are also the same. The resin does not need to have an acid value, and therefore common azo and peroxide polymerization initiators can be used to carry out the polymerization. The preferred molecular weight of other styrene resins is 5,00
0 or more and 500,000 or less. Molecular weight is 5,00
If it exceeds 0, the Tg of the binder decreases and the blocking property deteriorates, and if it exceeds 500,000, the MF of the toner increases.

As for the other polyester resins (B), those obtained from the polybasic acids and polyhydric alcohols described above can be used. Either the acid value or the hydroxyl value is usually 10 or less. If both the acid value and the hydroxyl value exceed 10, HO will be poor when used as a toner.

The weight average molecular weight of the low molecular weight polyolefin is usually i,ooo to 100,000, preferably 5,000 to
60゜OOOO (a): polyethylene, polypropylene, ethylene-α
Olefin (3 to 8 carbon atoms) copolymers (e.g. ethylene 50 wt% or more, especially 70 wt% or more), (b): (a) maleic acid derivatives (maleic anhydride, dimethyl maleate, diethyl maleate) ester, di-2-ethylhexyl maleate, etc.) adducts, (c): oxides of (a), (d): ethylenically unsaturated carboxylic acids ((meth)acrylic acid, itaconic acid, etc.) and/or their Esters (alkyl (C1-C18) esters) and ethylenically unsaturated hydrocarbons (ethylene, propylene, phthene-1
etc.) and mixtures of two or more of these.

Among the above low molecular weight polyolefins, (a) is a polymer plate polyolefin (the molecular weight is usually 10,000 to 2,000).
It can be obtained by thermally degrading (pyrolysis) 000) or by monopolymerizing or copolymerizing olefins. ([+) can be obtained by subjecting a low molecular weight polyolefin to an addition reaction with a maleic acid derivative in the presence of a peroxide catalyst or in the absence of a catalyst. (C) can be obtained by oxidizing a low molecular polyolefin with oxygen or an oxygen-containing gas (air), or by oxidizing it with ozone-containing oxygen or an ozone-containing gas (air). The acid value of the oxide is usually 100 or less, preferably 50 or less. (d) is an ethylenically unsaturated carboxylic acid and/or its alkyl ester (C
It is obtained by copolymerization of I-C18) and an ethylenically unsaturated hydrocarbon. ethylenically unsaturated carboxylic acid and/or
or the amount of its alkyl ester is usually 30% by weight
% or less, preferably 20% or less. The molecular weight of the low-molecular m-polyolefin is measured by GPC at +35°C using O-dichlorobenzene as a solvent.

The amounts of other styrene resins, other polyester resins, and low molecular weight polyolefins are each usually 30 weight or less, preferably 20 weight or less.

If the weight exceeds 30 weight, the dispersion state becomes poor and the image characteristics of the toner deteriorate.

The other styrene resins (A), other polyester resins (R), and low molecular weight polyolefins mentioned above can be melt-blended with the block polymer of the present invention, but they cannot be uniformly dispersed for use as a toner binder. Better performance can be obtained when the styrene resin (a) and polyester resin (b) are esterified or added during the polymerization process of the styrene resin (a). is desirable.

The electrophotographic toner to which the binder of the present invention can be used is:
Based on the weight of the toner, the toner binder is usually
0-95%, known coloring materials (carbon black, iron black, benzidine yellow, quinacridone, rhodamine B1
phthalocyanine, etc.) and usually 0 to 50% of magnetic powder (ferromagnetic gold dust powder such as iron, cobalt, nickel, etc., or compounds such as magnetite, hematite, ferrite, etc.).

Furthermore, various additives such as lubricants (polytetrafluoroethylene, low molecular weight polyolefins, fatty acids, or metal salts or amides thereof, etc.), charge control agents such as glosine, quaternary ammonium salts, etc.) can be included. The amount of these additives is usually 0-5% based on the weight of the toner.

Electrophotographic toner is produced by dry blending the above components, then melting and kneading, then coarsely pulverizing, and finally finely pulverizing using a jet pulverizer, etc., and then further classifying to have a particle size of usually 5 to 20 microns. Obtained as fine particles.

The electrophotographic toner is mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite, etc., if necessary, and used as a developer for an electrical latent image. Further, hydrophobic colloidal silica fine powder can also be used to improve the fluidity of the powder.

The electrophotographic toner is used by being fixed on a support (paper, polyester film, etc.), and a known hot roll fixing method can be used as a fixing method.

[Example] The present invention will be further explained with reference to Examples below, but the present invention is not limited thereto.

In the examples, all parts represent parts by weight.

In addition, molecular weight measurement by GPC is performed using equipment under the following conditions.
(2) ILC-802A column manufactured by Toyo Soda:
TSKgel GMHG 2 bottles (manufactured by Toyo Soda) Measurement temperature: 25°C Sample solution 20.5 times 2% weight HF solution solution injection fi:
200 μm Detection device: Refractive index detector A full molecular calibration curve was created using standard polystyrene.

Example 1 PO of 3,278 parts of terephthalic acid and bisphenol A
8.93 parts of the 2-mole adduct and 24 parts of dibutyltin oxide were charged into a four-flow flask, and a dehydration condensation reaction was carried out at a temperature of 180 to 240°C in a nitrogen stream. reaction 10
After some time, the acid value became 11 and the hydroxyl value became 40, so the reactant was taken out. Obtained polyester resin port A-11
The weight average molecular weight of is 5,000, the glass transition point is 58°
It was C.

On the other hand, a mixed solution of vinyl monomers (solution [1-11) consisting of 760 parts of styrene, 240 parts of butyl acrylate and 2 parts of divinylbenzene] and 7.7 parts of a polymerization initiator 44 + -azobis(4-cyanopentanoic acid) %
130 parts of 1.4-dioxane solution (solution [1-2)] was prepared. 1,4-dioxane 25 in a four flask
0 parts and Viscol 550p low molecular weight polypropylene manufactured by Sanyo Chemical Industries, Ltd.] 3 [i, 4 parts were added and refluxed in a nitrogen stream (120°C). Solution [1-1] and solution [1-2] were continuously added dropwise into the solution over 2 hours using a dropping pump to perform polymerization. Refluxing was further continued, and 26 parts of a 7.7% 1.4-dioxane solution of 4.4°-azobis(4-cyanopentanoic acid) was added every 2 hours. The amount of unreacted monomer remaining in the reaction solution was measured by gas chromatography, and the polymerization rate was 95%.
The polymerization was terminated when the temperature reached , and a solution of styrene resin (solution [B-1)] was obtained. The styrene resin obtained by removing the solvent from [B-1] had an acid value of 3.2 and a weight average molecular weight of 210,000.

400 parts of [A-1] were added to 834 parts of solution [B-1], and the mixture was stirred and heated to distill off 1,4-dioxane as a solvent. After the completion of distillation, the temperature was raised to 170°C and lommt (g
The esterification reaction was carried out under reduced pressure. After 13 hours, the acid value, which was 2.4 at the start of the esterification reaction, became 1.2, and the esterification was completed, and the binder (1) of the present invention
I got it. The obtained binder (1) was heated at 57°C and 68°C.
It has two glass transition points at C, the number average molecular weight is 4, and the weight average molecular weight is 180,000.
The acid value was l.2, and the hydroxyl value was 14.8.

Example 2 In the polymerization of styrenic resin, a solution of styrene resin (solution [B-2)] was obtained by carrying out the same operation as in Example 1 except that the poison in the polymerization initiator solution was changed to 110.5 parts. In addition[
The acid value of the styrene resin obtained by removing the solvent from B-2 is 2.
．． 7. The weight average molecular weight was 270.000.

A solution of polyester resin [A-1] and styrene resin [B-21] was esterified in the same manner as in Example-1 to obtain a binder (2). The obtained binder (2) is 58°
It has two glass transition points at C and 70'C,
Number average molecular weight is 7.000 Weight average molecular weight is 230
,000, the acid value was 1.1, and the hydroxyl value was 15.0.

Example 3 PO of 2,300 parts of isophthalic acid and bisphenol A
2.948 parts of 2 molar adduct, Eo of bisphenol A
Polyester resin [A-31] was obtained by polymerizing in the same manner as in Example 1 using 2.752 parts of the 2-mole adduct and 18 parts of dibutyltin oxide. The acid value of the obtained polyester resin CA-3 is 1.01, and the hydroxyl value is 4.
4.0, weight 1 average molecular weight was 7,000, and glass transition point was 54°C.

Add 400 parts of polyester resin [A-3] to 894 parts of the styrene resin solution [B-2] of Example-2,
An esterification reaction was performed to obtain a binder (3).

The obtained binder (3) has a glass transition point of 58°C1
Number average molecular weight is 7,000 Weight average molecular weight is 230
,000, the acid value was 1.0, and the hydroxyl value was 16.8.

Comparative Example 1 A mixture of vinyl monomers (solution [1-11) consisting of 760 parts of styrene, 240 parts of butyl acrylate and 2 parts of divinylbenzene, and 7.7% of the polymerization initiator azobisisobutyronitrile 1.4- 120 parts of dioxane solution (solution [1-31)] was prepared. 250 parts of 1,4-dioxane and 550 parts of Viscole in a four flask
1) [Low-molecular all-polypropylene manufactured by Sanyo Chemical Industries, Ltd.] 4 parts of 311i were added and refluxed in a nitrogen stream (
120″C). Add the solution [1-
1 and solution [13] were continuously added dropwise over 2 hours to carry out polymerization. Further, reflux is continued, and 4,4'-
7. Azobis (4-cyanopentanoic acid).
Add 26 parts of 7% 1,4-dioxane solution.

The remaining amount of unreacted monomer in the reaction solution was measured by gas chromatography, and when the polymerization rate reached 95%, the polymerization was terminated to obtain a binder (4).

The obtained binder (4) was heated to 57°C and 69°C twice.
It has a glass transition point of 5° and a number average molecular weight of 5°0.
00 Weight average molecular weight was 190.0001, acid value was 0.5, and hydroxyl value was 16.0.

Example 4 120 parts of the binder (4) obtained in Comparative Example 1, 40 parts of the binder (1) obtained in Example 1, and terephthalic acid obtained in the same manner as [:A-1] in Example 1. Polyester resin [A-4] consisting of a PO2 mol adduct of bisphenol A (acid value 0.5, water Fa value 201, weighted average molecule fi8eoo, glass transition point 58°C)
After heating and dissolving 80 parts of 1,4-dioxane in 300 parts of 1.4-dioxane,
．． 4-dioxane was distilled off to obtain a binder (5). The obtained binder (5) has two glass transition points at 58°C and 69°C, and has a number average molecular m of 4900.
The weighted average molecular weight was 200,000, the acid value was 0.3, and the hydroxyl value was 90.

Example 5 A mixture of vinyl monomers consisting of 780 parts of styrene, 240 parts of butyl acrylate, and 3 parts of divinylbenzene (
Solution [1-11) and a 7.7% solution of azobisisobutyronitrile and 1.4-dioxane as a polymerization initiator (
150 parts of solution [1-31] was prepared. 250 parts of 1.4 dioxane and 660 parts of Viscole in a four-necked flask
36.4 parts of low molecular weight polypropylene (produced by Sanyo Kasei Kogyo Co., Ltd.) was added and refluxed (120°C) in a nitrogen stream.

Using a dripping pump, add the solution [l-1] and the solution [l-1].
-3] was continuously added dropwise over 2 hours to perform polymerization.

Further, refluxing was continued, and 26 parts of the polymerization initiator solution was added every 2 hours. The remaining amount of unreacted monomer in the reaction solution was measured by gas chromatography, and when the polymerization rate reached 96%, the polymerization was completed and the styrene resin solution (solution [B-
3 pieces) were obtained. The acid value of the styrene resin obtained by removing the solvent from [B-3] is 0.0, and the average molecular weight of the mold plate is 300.
．． It was 000. In solution [B-31597 parts [A-
1 part eoo and 200 parts of binder (+) and 1.4 parts
- 1,4- which is a stirring solvent by adding 7800 parts of dioxa
Dioxane was distilled off. The obtained binder (6) has two glass transition points at 58°C and [i8°C, and has a number average molecular weight of 5,500 and a weight average molecular weight ff122.
0,000, the acid value was 0.7, and the hydroxyl value was 22.

Use Examples 1 to 5 and Comparative Use Example 1 Electrophotographic toners were prepared by the following method using binders (1) to (6), and an electrophotographic developer was also prepared.

Toner production method Binder: 90 parts Viscoel 660P 3 parts (low molecular weight polypropylene manufactured by Sanyo Chemical Industries, Ltd.) Carbon black MA-1008 parts (manufactured by Mitsubishi Chemical Industries, Ltd.) Eisenspiroblack TRH 1g (manufactured by Hodogaya Chemical Industries, Ltd.) ) After powder-blending the above-mentioned mixture, it was kneaded for 10 minutes at 140°C and 30 rpm using a Labo Plastomill, and the resulting kneaded product was pulverized using a jet mill PJM100 (manufactured by Nippon Ninematic Co., Ltd.). Fine powder of 5 μm or less was cut from the finely ground material using an air classifier MDS (manufactured by Nippon Pneumatic Co., Ltd.). Add Aerosil R to 1,000 parts of the obtained powder.
972 (manufactured by Nippon Aerosil Co., Ltd.) were uniformly mixed to obtain a toner.

Developer Preparation Method An electrophotographic developer was prepared by mixing 25 parts of the above toner with 1,000 parts of electrophotographic carrier iron powder (F-100 manufactured by Nippon Tetsuko Co., Ltd.).

The evaluation results are shown in Table-1 and Table-2.

Table 1 Evaluation results (1) Table evaluation results Note) Observability by composition image using a scanning electron microscope The average particle diameter (μ) was determined using Coulter Counter TAII (manufactured by Coulter Electronics, Inc., USA).

2) Image stability is Fuji Xerox Xerox 39
70 Using a copying machine, the heat roller temperature at which MF and HO were observed was measured.

3) Image stability is image 11 on the image surface after copying a predetermined number of sheets.
Evaluated in degrees. Specifically, it was measured using a Macbeth image densitometer, and the standard plain color was expressed as 0.06, and the standard black background was expressed as 1.87.

A stable sea-island structure can be maintained even when mechanical energy is applied. This is something that could not be achieved using conventional techniques. Since the dispersion is fine and uniform, the toner is evenly charged, resulting in good image quality that can withstand long-term continuous use. Furthermore, since the characteristics of each of the styrene resin and polyester resin are effectively exhibited, it has become possible to design and manufacture a well-balanced binder.

Binders (1) to (3) and (5) to (6) of the present invention
) are both superior to comparative product (4) in terms of their dispersion state in the beetroot powder and have excellent pulverization properties when forming into toner. Furthermore, the toner has a wide temperature range of MF and HO, has good fixing performance as a toner, and has excellent image stability.

[Effects of invention

Claims (1)

[Claims] 1. A polyester resin (b) having a hydroxyl value of 30 to 60 and an acid value of 5 or less, and a polyester resin (b) having an acid value of 1 to 10 and a molecular weight of 5,000 to 500. A binder for an electrophotographic toner, characterized in that it contains a block polymer obtained by esterifying a styrene resin (a) of 0.000%. 2. (a) is 90 to 50% by weight of styrenic monomer, (
Claim 1: The monomer is obtained by polymerizing monomers consisting of 10 to 50% by weight of a meth)acrylic monomer, 3% by weight or less of a polyfunctional monomer, and 10% by weight or less of other monomers using a carboxyl group-containing polymerization initiator. Binder listed. 3. The binder according to claim 1 or 2, wherein the low molecular weight polyolefin is added to the polyester resin manufacturing process, the styrene resin manufacturing process, and/or the esterification process of the polyester resin and styrene resin. 4. (1) Styrene resin (A), (2) polyester resin (B) that is substantially incompatible therewith, and (3) having a polystyrene resin structure and a polyester resin structure in one molecule. An electrophotographic toner binder containing resin (C) as an essential component.