JPS6368850A - Electrophotographic developer composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition capable of preventing offset without applying any offset preventing solution, by using a specific polyester resin to a main component of a binding resin of the titled composition, and by incorporating at least two kinds of electric charge controlling agents to the titled composition. CONSTITUTION:The main component of the binding resin contd. in the titled composition is composed of the polyester resin obtd. by effecting a condensation polymerization of a diol component shown by formula I, a divalent carboxylic acid or its acid anhydride or its lower alkylester containing an alkyl or an alkenyl succinic acid in 5-50mol% (based on the total carboxylic acid component), and a trivalent or more carboxylic acid or its acid anhydride or its lower alkylester including tetracarboxylic acid shown by formula II or its acid anhydride or its lower alkylester in 0.1-20mol% (based on the total carboxylic acid component). The polyester resin has >=1.2 OHV/AV (wherein, AV is the acid value and OHV is the hydroxyl value). The titled composition contains at least two kinds of the electric charge controlling agents. Thus, the titled composition capable of giving a sufficient broad nonoffset range is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer composition for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, and the like.

[Conventional technology and problems]

Conventional electrophotographic methods include uniformly charging a photoconductive insulating layer, then exposing the layer to light, as described in U.S. Pat. An electrical latent image is formed by dissipating the charge on the second part, and is visualized by attaching a colored, electrically charged fine powder called toner to the latent image (developing process). The visible image is transferred to a transfer material such as transfer paper (transfer step), and then permanently fixed by heating, pressure, or other suitable fixing method (fixing step).

In this way, toner is used not only in the development process but also in the transfer process.
It must have the functions required in each step of the fixing process.

Generally, toner is subjected to mechanical frictional force due to shearing force and impact force during mechanical operation in a developing device, and deteriorates while copying several thousand to tens of thousands of sheets. To prevent this type of toner deterioration, it is best to use strong resins with large molecular weights that can withstand mechanical friction, but these resins generally have a high softening point and cannot be used in oven fixing, which is a non-contact fixing method, or infrared rays. With radiant fixing, the thermal efficiency is poor and fixing is not sufficient.Also, since the contact fixing method has good thermal efficiency, even in the widely used heat roller constant fixing method, it is necessary to use heat to achieve sufficient fixing. It is necessary to raise the temperature of the roller, which not only causes problems such as deterioration of the fixing device, curling of paper, and increased energy consumption, but also has poor pulverization properties when using such resin, so it is difficult to manufacture toner. In this case, the manufacturing efficiency decreases significantly.Therefore, the degree of polymerization of the binder resin,
Furthermore, those having too high a softening point cannot be used. On the other hand, in the heat roller fixed fixing method, the heating roller surface and the toner image surface of the sheet to be fixed are in pressure contact, so the thermal efficiency is extremely high and it is widely used from low speeds to high speeds. Upon contact, toner adheres to the surface of the heating roller and is transferred to subsequent transfer paper, etc.
A so-called offset phenomenon is likely to occur. In order to prevent this phenomenon, the surface of the heating roller is treated with a material with excellent mold release properties such as a fluorine-based resin, and in addition, a mold release agent such as silicone oil is coated on the surface of the heating roller.

However, the method of applying silicone oil or the like is not preferable because the fixing device becomes large and not only expensive but also complicated, which can easily cause I/Rubble.

Also, Japanese Patent Publication No. 55-6895, Japanese Patent Publication No. 56-98202
As described in the above publication, there is a method of improving the offset phenomenon by widening the molecular weight distribution width of the binder resin, but generally the degree of polymerization of the resin increases and the fixing temperature used also needs to be set high.

As a further improved method, as described in Japanese Patent Publication No. 57-493, Japanese Patent Application Laid-open No. 50-44836, and Japanese Patent Application Publication No. 57-37353, there is a method of improving the offset phenomenon by making the resin asymmetrical and crosslinking it. However, the retention point has not improved.

Generally, the minimum fusing temperature is between the low temperature offset and the high temperature offset, so the usable temperature range is between the minimum fusing temperature and the high temperature offset.The minimum fusing temperature should be lowered as much as possible, and the temperature at which high temperature offset occurs should be raised as much as possible. This makes it possible to lower the usable fixing temperature and widen the usable temperature range, resulting in energy savings, high-speed fixing, and prevention of paper curl.

In addition, in order to be able to make double-sided copies without any trouble, the copiers have become more intelligent, the temperature control of the fixing device has become more accurate, and
There are many advantages such as relaxing the tolerance range.

Therefore, resins and toners with good fixing properties and offset resistance are always desired.

When using a styrene-based binder resin to meet such requirements, Japanese Patent Application Laid-Open Nos. 49-65232 and 1977-
As described in No. 28840 and JP-A No. 50-81342, a method of adding paraffin wax, low molecular weight polyolefin, etc. as an offset preventing agent is known, but if the amount added is small, there is no effect, and if there is a large amount, the developer It has also been confirmed that the deterioration of

Polyester resin inherently has good fixing properties, and can be sufficiently fixed even in a non-contact fixing method, as described in U.S. Pat. It was difficult to use.

As described in JP-A-50-44836, JP-A-57-37353, and JP-A-57-109875, polyester resins with improved offset resistance using polyhydric carboxylic acids have sufficient properties for use. There are problems in that they do not have anti-offset properties, or those that do do so at the expense of the low-temperature fixing properties that polyester resins have. On the other hand, L-toner using polyester resin may have poor fluidity compared to styrene-based toner, and may become agglomerated, resulting in poor toner conveyance in the developing device, resulting in poor developability and poor image quality. A visible image with poor image quality, such as unevenness and background smearing, was sometimes formed.

In order to improve the fluidity of toner, a large amount of fluidity improver such as hydrophobic silica fine powder is added, and as a result, the surface of the electrostatic image support is cleaned using a urethane rubber blade or the like. If this happens, toner particles may become trapped between the blade and the electrostatic image support, resulting in poor cleaning and smearing of the visible image.

Furthermore, when using an image forming apparatus having a recycling system in which toner that has been developed but has not been transferred is returned to the developing device for reuse, fine particles of hydrophobic silica are embedded in the surface of the 1-toner particles. , the fluidity of the toner may be reduced and a visible image of poor quality may be formed.

Further, the polyester resin itself has appropriate triboelectric charging properties, and therefore it is possible to impart charging ability to the toner without adding a charge control agent. However, since the entire resin is charged, its frictional charging properties gradually increase.For example, as more than 50,000 copies are made continuously, the amount of charge of the toner using polyester resin changes, and the image density decreases. This may have a negative effect on the visible image, such as making it thinner.

The present invention was made to meet these demands, and its purpose is to prevent offset without applying an anti-offset liquid in a heat roller fixed fixing method, and to
Another object of the present invention is to provide a developer that can be fixed at a lower fixing temperature.

Another object of the present invention is to provide a developer that has good fluidity, does not cause blocking, and has a long life (hard to deteriorate).

[Means for solving problems]

That is, in the present invention, the main component of the binder resin is (b) The following formula (In the formula, R is ethylene or propylene group, X.

Each y is an integer of 1 or more, and the average value of x+y is 2 to 7. ); (b) a divalent carboxylic acid or its acid anhydride or its lower alkyl ester containing 5 to 50 mol% of alkyl or alkenyl succinic acid in the total carboxylic acid component; and (c) the following: Tetracarboxylic acid or its acid anhydride or lower thereof represented by the formula % (wherein X is an alkylene group or alkenylene group having 5 to 30 carbon atoms and having one or more side chains having 3 or more carbon atoms) Alkyl ester in total carboxylic acid components from 0.1 to
A polyester resin obtained by cocondensation polymerization with a trivalent or higher polycarboxylic acid containing 20 mol% or its acid anhydride or its lower alkyl ester, the acid value of the polyester resin being AV and the hydroxyl value being OHV. sometimes,
The present invention relates to an electrophotographic developer composition comprising a polyester resin having a value of 011v/AV of 1.2 or more and containing at least two types of charge control agents.

In the present invention, in particular, the softening point of the binder resin is 106 to 16.
0''C and a glass transition temperature of 50 to 80°C, and the charge control agents include at least one type of positively chargeable charge control agent and at least one type of negatively chargeable charge control agent. The amount of the positively chargeable charge control agent used is preferably 172 or less of the amount of the negatively chargeable charge control agent used.

On the other hand, unless a transesterification reaction or a reaction with a monovalent carboxylic acid and/or alcohol is performed, carboxyl groups and/or hydroxyl groups remain at the molecular ends of polyester, but the friction of the polyester resin itself depends on the amount of these end groups. It has been confirmed that the amount of charge changes. If the amount of terminal groups, especially the acid value, is reduced too much, the amount of triboelectricity of the polyester resin will decrease, and if the amount of endgroups, especially the acid value, is increased too much, the amount of triboelectricity of the polyester resin will increase to a certain level, but on the other hand, The environmental dependence after forming into a toner becomes significant, making it difficult to use it as a developer composition. Polyester resins having an acid value of 5 to 60 (KO 11 mg/g) are often used for toners. Now, when the acid value of the polyester resin is AV and the hydroxylization is 011■, a toner made of a polyester resin has an OHν/AV value of 1.2 or more, although the reason is not strictly elucidated. The toner has improved fluidity, and the use of this toner makes it possible to lower the minimum fixing temperature.

The polyester resin used as the main component of the binder resin in the present invention includes alcohol, carboxylic acid,
Alternatively, it can be obtained by condensation polymerization with carboxylic acid ester or carboxylic acid anhydride, but as the diol component (a) of the alcohol component, polyoxypropylene (2,2)
-2,2-bis(4-hydroxyphenyl)propane,
Polyquine propylene (3,3)-2,2-bis(4-
Hydroxyphenyl) propane, polyoxyethylene (
2,0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2,0)-polyoxyethylene(2,0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2,0)-polyoxyethylene(2,0)-2,2-bis(4-hydroxyphenyl)propane, Oxypropylene (6)-2
, 2-bis(4-hydroxyphenyl)propane, and the like.

In addition, other diols such as ethylene glycol, diethylene glycol, triethylene glycol,
■, 2-propylene glycol, 113-propylene glycol, L4-butanediol, neopentyl glycol, 1,4-butynediol, 1.5-bentanediol, 1,z 6-hexanediol, 1,4-cyclohexane dimeta Diols such as tool, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, hisphenol A, hydrogenated bisphenol A8, and other dihydric alcohols can be added in an amount of about 10 mol % or less in the alcohol component.

In addition, among the divalent carboxylic acid components in the present invention, examples of the alkyl or alkenyl succinic acid include n-butylsuccinic acid, n-butenylsuccinic acid, isobutylsuccinic acid, isobutenylsuccinic acid, and n-octylsuccinic acid. , n-
Examples include octenylsuccinic acid, n-dodecylsuccinic acid, n-F decenylsuccinic acid, isododecylsuccinic acid, isododecenylsuccinic acid, anhydrides and lower alkyl esters of these acids. By using alkyl or alkenyl succinic acid, the temperature at which offset occurs is not lowered,
The minimum fixing temperature can be lowered, but if it is too little, the effect will be weak, and if it is too high, the glass transition temperature will be lowered and the storage stability of the toner will deteriorate. Therefore, its content is preferably 5 to 50 mol% in the total carboxylic acid components.

Further, in the present invention, examples of the (b) divalent carboxylic acid component other than alkyl or alkenylsuccinic acid include maleic acid, fumaric acid, citraconic acid, itaconic acid,
Glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, cehatic acid, azelaic acid, malonic acid, or anhydrides, lower alkyl esters, and other divalent carboxylic acids of these acids. can be mentioned.

In addition, among the polyvalent carboxylic acids (c) in the present invention, the following formula % formula % (in the formula, × is an alkylene group having 5 to 30 carbon atoms having one or more side chains having 3 or more carbon atoms, or It is an alkenylene group.

) Tetracarboxylic acids represented by the following (1) to
Examples include those shown in 0.

(1) 4-neopentylizonyl-1,2,6,7-heptanetetracarboxylic acid (2) 4-neopentyl-C2,6,7-hebutene (4
)-tetracarboxylic acid (3) 3-methyl-4-heptenyl-1,2,5,6-
Hexanetetracarboxylic acid (4) 3-methyl-3-heptyl-5-methyl-C2,
6,7-heptene(4)-tetracarboxylic acid(5)3-
Nonyl-4-methylisonyl-1,2,5,6-hexanetetracarboxylic acid (6) 3-desylizonyl-1,2,5,6-hexanetetracarboxylic acid (7) 3-nonyl-C2,6,7~ Heptene (4)-tetracarboxylic acid (8) 3-decenyl-1,2,5,6-hexanetetracarboxylic acid (9) 3-butyl-3-ethylenyl-1,2,5,6-
Hexanetetracarboxylic acid Q[Il 3-methyl-4-butyrisonyl-1,2,
6,7-hebutanetetracarboxylic acid 0υ 3-methyl-4-butyl-1,2,6,7-heptene(4)-tetracarboxylic acid 3-methyl-5-octyl-1,2,6,7 -hebutene(4)-tetracarboxylic acid The structural formulas of these compounds are shown below. For convenience, all the compounds are shown in the form of acid anhydrides.

(1) C -C-C (2) C -C-C U +41 0-C-C-CC QO) C-(: By using these tetracarboxylic acids, the lowest fixing temperature can be lowered in the fixing process. It is possible to lower the resistance and improve offset resistance, but if used in small amounts, the effect is small, and if used in large amounts, the fixing performance will be poor (not only will it be difficult to control the degree of resin polymerization during manufacturing) becomes.

Therefore, its content is 0.1 to 20% of the total carboxylic acid components.
It is mol%, more preferably 1 to 10 mol%.

Among the trivalent or higher polyhydric carboxylic acid components (c) in the present invention, other than the above-mentioned tetracarboxylic acids are preferable components for improving the off-cent phenomenon, but if there is too little, the effect is weak, and when there is too much, the reaction is Difficult to control
Not only is it difficult to obtain a polyester resin with stable performance, but also undesirable phenomena occur, such as the resin becoming hard and difficult to crush, resulting in a marked drop in toner production efficiency, and an increase in the minimum fixing temperature. Specifically, trivalent or higher polyvalent carboxylic acid components other than the above-mentioned tetracarboxylic acid include 1,2.4-benzenetricarboxylic acid, 1,2.5-benzenetricarboxylic acid, 2,537-naphthalenetricarboxylic acid, 1 ．．
2.4-naphthalenetricarboxylic acid, 1.2.4-butanetricarboxylic acid, 1,2.5-hexanetricarboxylic acid, 1.3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2.4 - cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1.2,7.8-octanetetracarboxylic acid, pyromellitic acid, embol trimer acid, and anhydrides thereof,
Examples include lower alkyl esters and other trivalent or higher carboxylic acids.

The binder resin mainly composed of polyester resin as described above used in the present invention has a softening point of 106 to 10.
160°C and a glass transition temperature of 50 to 80°C are preferable, but if the softening point is less than 106°C, it is not effective in obtaining a sufficient non-offset region, and if it exceeds 160°C, the minimum fixing temperature becomes high, etc. , undesirable phenomena occur. On the other hand, if the glass transition temperature is less than 50°C, the storage stability after forming a toner will be poor, and if it exceeds 80°C, it will adversely affect the fixing performance, which is not preferable.

In addition, the acid value and hydroxyl value of polyester resin are JIS K
When the ethyl acetate insoluble content is 3% by weight or more, dioxane is preferably used as the acid value measurement solvent.

In the present invention, when the acid value is AV and the hydroxyl value is 0IIV, a polyester resin having a value of 01 (V/AV of 1.2 or more) is the main component of the binder resin, but the value of 0IIV/AV is A toner obtained using a polyester resin with a polyester resin of less than 1.2 has a higher minimum fixing temperature than a toner obtained using a polyester resin with a polyester resin of 1.2 or more, and also has poor fluidity. In order to obtain this, it is necessary to add a large amount of a fluidity improver such as hydrophobic silica fine powder, and in this case, as described above, a visible image with poor image quality is often formed.

The above-mentioned polyester resin having an OHV/AV value of 1.2 or more can be easily obtained by using a larger number of functional groups in the alcohol component than in the carboxylic acid component in the polycondensation reaction described above.

The developer composition of the present invention contains the above-mentioned polyester resin and at least two kinds of charge control agents, preferably one or more of each of positively chargeable and negatively chargeable charge control agents, and uses a positively chargeable charge control agent. The amount is 1 of the amount of negatively chargeable charge control agent used.
/2 or less, even if more than 50,000 copies were made continuously, it was possible to obtain good visible images without any decrease in density.

Specific examples of positively chargeable charge control agents include nigrosine dyes, such as "Nigrosine Base EXJ", "Oil Blank BSj", "Oil Black SOJ", "Bontron N", etc.
-01J, [Bontron N-11-1 (manufactured by Orient Chemical Co., Ltd.), triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, such as "Bontron P-51J (Orient Chemical Co., Ltd.) Polyamine resins such as rAFP-It J (manufactured by Orient Chemical Co., Ltd.), cetyltrimethylammonium bromide, etc. can be mentioned.

Specific examples of negatively chargeable charge control agents include metal-containing ab dyes, such as "Parifast Blank 3804 J,"
Bontron 5-31 J, "Bontron 5-32", "
Bontron 5-34 J, "Bontron 5-36" (manufactured by Orient Kagaku Co., Ltd.), "Eisenspiron Brasoku TνHj (manufactured by Odugaya Kagaku Co., Ltd.), copper phthalocyanine dyes, metal complexes of alkyl derivatives of salicylic acid, e.g. Bontron E-82], [Bontron E-84J, [
Other examples include Bondron B-85J (manufactured by Orient Chemical Co., Ltd.).

The above charge control agent has a charge control agent of 0.1 to 8.0 with respect to the binder resin.
It is contained in an amount of 0.2 to 5.0% by weight, preferably 0.2 to 5.0% by weight.

The polyester resin used in the present invention can be produced by condensation polymerization of a polyhydric carboxylic acid component and a polyol component, for example, at a temperature of 180 to 250° C. in an inert gas atmosphere. At this time, commonly used nistylation catalysts such as zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, etc. can be used to accelerate the reaction. It can also be produced under reduced pressure for the same purpose.

A toner is obtained using the polyester resin according to the present invention as a main component of a binder resin. For example, in order to improve the crushability in forming a toner, styrene or styrene-acrylic resin having a number average molecular weight of 11,000 or less is used. , other resins may be used up to 30% by weight in the binder resin. At the time of toner preparation, in addition to colorants and magnetic substances, property improvers such as wax as an anti-offset agent and hydrophobic silica as a fluidity improver are added, but the polyester resin according to the present invention is used as a binder resin. When used, it is not necessary to add the property improver, and even if it is added, the amount added can be small.

Colorants used in the present invention include various carbon blacks produced by thermal black method, acetylene black method, channel blank method, lamp black method, etc., phthalocyanine blue, and permanent brown F.
G, Brilliant Fast Scarle Soto, Pigment Green B10-Dammin-B Heath, Solvent Red 49, Turben Trend 146, Solvent Blue 35
etc., and mixtures thereof, etc., and are usually used in an amount of 1 to 15 parts by weight per 100 parts by weight of the binder resin.

In the present invention, the above-mentioned polyester resin and at least two kinds of charge control agents are essential components, and after uniformly dispersing a coloring agent and, in some cases, a property improving agent, melting, kneading, cooling, and pulverization are performed by a known method. , after classification, average particle size 5-15 μm
The toner is obtained by dry processing by mixing it with magnetic powder, that is, an iron oxide carrier, a true spherical iron oxide carrier, a ferrite carrier, etc., or a carrier coated with a resin or the like. Used as a two-component developer.

When making a magnetic toner using the binder resin according to the present invention,
Examples of the magnetic material include powders of ferromagnetic metals such as iron, cobalt, and nickel, and alloys or compounds containing ferromagnetic elements such as ferrite, hematite, and magnetite, and the magnetic material has an average particle size of 0.1 It can be used in the form of a fine powder of ~1 .mu.m, by scattering about 40 to 70 parts by weight on 100 parts by weight of the binder resin.

(Examples) Hereinafter, examples of manufacturing a binder resin and examples of the present invention will be described, but the present invention is not limited to these examples.

It should be noted that all composition ratios shown in Examples are expressed in parts by weight.

Production Example 1 Polyoxypropylene (2,2)-2,2-bis(4-
840 g of polyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane, 177 g of succinic acid, 88 g of n-butenylsuccinic acid, and 3-isodecenyl-1,,2,
163 g of 5,6-hexanetetracarboxylic acid was placed in a fourth glass flask (size 21), equipped with a thermometer, a stainless steel stirring bar, a falling condenser, and a nitrogen introduction tube, and heated in a mantle heater under a nitrogen stream. The reaction was carried out at 200°C with stirring. The degree of polymerization is ASTHE 2B-
Tracking was performed from the softening point corresponding to 51T, and the softening point was 122
The reaction was terminated when the temperature was reached. The obtained resin was a pale yellow solid, and the glass transition temperature measured by DSC (differential calorimeter) was 65°C. In addition, the acid value of the resin is 13KOHD.
1g/g, and the hydroxyl value was 26KOHmg/g.

The resin is referred to as a binder resin (ll).

Production Example 2 Polyoxypropylene (2,2)-2,2-bis(4-
Hydroxyphenyl)propane 1050g, isooctenylsuccinic acid 102g, azelaic acid 169g, 1.
Using 126 g of 2.4-Hensentricarboxylic acid and 109 g of 3-methyl-4-hebutenyl-B2,5.6-hexanetetracarboxylic acid, the same apparatus and procedure as in Production Example 1 were used to obtain a mixture with a softening point of 122° C. Glass transition temperature 62℃, acid value 19KOHmg/g, hydroxyl value 37KOl (mg/
g of polyester resin was obtained. The resin is bonded with a binder resin (2
).

Production Example 3 In the same manner as Production Example 1, except that the amount of succinic acid was changed to 190 g, the softening point was 122°C and the glass transition temperature was 64°C.
°C, acid value 24KO1 (mg/g, hydroxyl value 20KOH)
mg/g of polyester resin was obtained. This resin is referred to as a binder resin (3).

Production Example 4 In Production Example 1, the reaction was completed when the softening point reached 105 °C, the glass transition temperature was 60 °C, and the acid value was 15 KOIn+g.
/g, and a polyester resin having a hydroxyl value of 30 KOHmg/g was obtained. This resin is referred to as a binder resin (4).

Examples 1 to 3, Comparative Examples 1 to 5 Materials with the following compositions were mixed in a ball mill, then melted and kneaded in a pressure kneader, cooled, and then subjected to normal crushing and classification processes to prepare toner with an average particle size of 11 μm. did.

<Composition> Example 1 Binder resin fl) 90 parts Example 2 Binder resin f21 90 parts Carbon black [Regal 400R 47 parts Example 3 Binder resin (1190 parts Carbon blank "Regal 400RJ 7 parts Comparative example 1 Binder resin (1) 90 parts Carbon blank "Regal 400RJ 7 parts Comparative example 2 Binder resin (1190 parts Carbon blank [Regal 400RJ 7 parts Comparative example 3 Binder resin (119Q parts Carbon black [Regal 400RJ 7 parts Comparative example 4 Binder resin (3190 parts carbon blank [Regal 400R 47 parts Comparative Example 5 Binder resin + 41 9Q parts Carbon blank "Regal 4001? J 7 parts or more of the toners obtained in Examples 1 to 3, respectively, Toner 1 to Toner 3, Comparative Example 1 The toners obtained in steps 1 to 5 are referred to as comparative toner 1 to comparative toner 5, respectively.

39g each of the above toners and 1261g of resin-coated iron powder
A commercially available electrophotographic copying machine (the photoreceptor is amorphous selenium, the rotation speed of the fixing roller is 255+wm/see, the temperature of the heat roller in the fixing device is variable, and the oil coating device is mixed with (removed)
Images were taken at .

The fixing temperature was controlled at 120° C. to 220° C., and the fixing properties and offset properties of the image were evaluated. The results are shown in Table 1.

The minimum fixing temperature here is 15 mm x 7.5 mm on the bottom.
A load of 500 g was placed on a 500 g sand eraser, and the image fixed through the fixing machine was rubbed back and forth 5 times, and the optical reflection density was measured using a Machhess reflection densitometer before and after rubbing, and the fixing rate was determined as defined below. This refers to the temperature of the fixing roller when the temperature exceeds 70%.

However, Comparative Toner 4 has poor toner fluidity and poor toner transportability within the developing device, and as a result, from the initial image,
Image unevenness and background stains occurred.

Comparative Toner 5 had a low minimum fixing temperature, but the non-offset area was narrow. For comparative toners 1 and 2, the image density began to decrease when the number of continuous copies exceeded 53,000 sheets, and the image density remained low even after 70,000 sheets were printed. Comparison toner 3
Staining occurred from the beginning.

On the other hand, Toner 1 to Toner 3 of the present invention had good fixing properties and good toner transport properties, and the visible image quality was good from the initial stage up to 120,000 sheets.

Procedural amendment (voluntary) August 19, 1985 1, Indication of the case Japanese Patent Application No. 61-213512 2, Name of the invention Electrophotographic developer composition 3, Person making the amendment Relationship to the case Patent applicant (091) Kao Co., Ltd. Company 4, Agent Nakai Building, 1-3 Nihonbashi Yokoyama-cho, Chuo-ku, Tokyo Column 6 of the detailed explanation of the invention in the specification, Contents of amendment (1) End line of page 23 of the specification: In the condensation polymerization reaction, after "", add "Although it is necessary to take into account the flow of raw material monomers out of the reaction system due to monomer evaporation, sublimation, etc."

Claims (1)

[Claims] 1. The main component of the binder resin is (a) the following formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R is an ethylene or propylene group, and x and y are each an integer of 1 or more. and the average value of x + y is 2 to 7. Acid anhydride or its lower alkyl ester, (c) The following formula▲ Numerical formula, chemical formula, table, etc.▼ (In the formula, or an alkenylene group) or its acid anhydride or its lower alkyl ester in the total carboxylic acid component.
A polyester resin obtained by cocondensation polymerization with a trivalent or higher polycarboxylic acid containing 20 mol% or its acid anhydride or its lower alkyl ester, the acid value of the polyester resin being AV and the hydroxyl value being OHV. sometimes,
An electrophotographic developer composition comprising a polyester resin having an OHV/AV value of 1.2 or more and containing at least two types of charge control agents. 2. The softening point of the binder resin is 106 to 160°C,
The electrophotographic developer composition according to claim 1, having a glass transition temperature of 50 to 80°C. 3. The electrophotographic developer composition according to claim 1, wherein the charge control agent comprises at least one positively chargeable charge control agent and at least one negatively chargeable charge control agent. 4. The electrophotographic developer according to claim 3, wherein of the charge control agents, the amount of the positively chargeable charge control agent used is 1/2 or less of the amount of the negatively chargeable charge control agent used. agent composition.