JPH07239572A - Electrophotographic binder and electrophotographic toner containing the same - Google Patents

Abstract

PURPOSE:To obtain a binder excellent in fixability at a low temp. and anti- offsetting property by mixing and dispersing high mol.wt. styrene resin in a resin obtd. by simultaneously carrying out polymn. reactions in the same vessel with stock monomers far polyester resin and styrene resin. CONSTITUTION:Styrene resin (A) is uniformly dispersed in a resin (B) obtd. by simultaneously carrying out a condensation polymn. reaction for obtaining polyester resin and a radical polymn. reaction for obtaining styrene resin in the same vessel with a mixture of stock monomers for the resins to obtain the objective electrophotographic binder. A polyol component and a polybasic carboxylic acid component such as polybasic carboxylic acid or polybasic carboxylic acid ester are used as stock monomers for polyester resin in the resin B. Polymerizable monomers used for forming the styrene resin A and styrene resin in the resin B may be of the same kind or of different kinds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic binder having excellent low-temperature fixability and offset resistance, and an electrophotographic toner containing the same.

[0002]

2. Description of the Related Art Electrophotographic methods used in image forming apparatuses such as laser printers and dry electrostatic copying machines are described in US Pat.
No. 221,776, No. 2,297,691, No. 2,357,809, etc., the photoconductive insulating layer was uniformly charged (charging step), then the layer was exposed and exposed. An electrostatic latent image is formed by dissipating the electric charge of the part (exposure step), and further visualized by attaching colored fine powder called toner to the electrostatic latent image (developing step), After the obtained visible image is transferred onto a transfer material such as transfer paper (transfer step), it is permanently fixed by heating, pressure or other appropriate means (fixing step).

Of these, in the fixing step, a contact heat fixing method such as heat roller fixing and a non-contact heat fixing method such as oven fixing are used. This contact heating fixing method is characterized by high thermal efficiency, and can lower the temperature applied to the fixing device as compared with the non-contact heating fixing method, and is effective for energy saving and downsizing of a copying machine. However, in this contact heating fixing method, there is a problem that a part of the toner melted at the time of fixing is transferred to a heat roller, and an offset phenomenon occurs in which the toner is transferred to a subsequent transfer sheet or the like.
In order to prevent this phenomenon, the surface of the heat roller is processed with a material having good releasability such as fluorine resin, or a release agent such as silicone oil is applied to the surface of the heat roller. However, the method using silicone oil or the like is not preferable because the fixing device becomes large and complicated, which may increase the cost and cause troubles.

Conventionally, a styrene resin represented by a styrene-acrylic copolymer has been used for this kind of toner. In the case of styrene resin, it is necessary to increase the softening point and crosslink density of the resin in order to improve the offset resistance,
This sacrifices low temperature fixability. On the contrary, if low temperature fixability is emphasized, problems occur in offset resistance and blocking resistance. Further, there is known a method of adding paraffin wax, low molecular weight polyolefin and the like as an offset preventive agent (JP-A-49-65232, JP-A-50-28840, JP-A-50-81342). In this case, if the addition amount is small, the effect cannot be obtained.

Polyester resin is used as a binder resin for toner which is excellent in low-temperature fixability. Polyester resins are inherently well-fixed, see US Pat. No. 359,00.
As described in the specification No. 0, the toner is sufficiently fixed even in the non-contact heat fixing method, but in the heat roller fixing method, an offset phenomenon is likely to occur and it is difficult to use. Also,
JP-A-50-44836, JP-A-57-37353, JP-A-
As described in JP-A-57-109875, a polyester resin having improved offset resistance using a polyvalent carboxylic acid does not have or has sufficient offset resistance to be used. In addition to sacrificing the low temperature fixing property originally possessed by the polyester resin, there is a problem that the resin itself or the pulverizability is extremely poor in the toner forming process.

For this reason, attempts have been made to use a polyester resin having excellent fixability in combination with a styrene resin. For example, a method of mixing a polyester resin and a styrene-acrylic resin (JP-A-49-6931 and JP-A-5-6931).
4-114245, JP-A-57-70523, JP-A-2-1614
64), a method of chemically bonding a polyester resin and a styrene-acrylic resin (JP-A-56-116043),
Method of copolymerizing styrenic monomer with unsaturated polyester (JP-A-57-60339, JP-A-63-279265)
JP-A No. 1-156759 and JP-A No. 2-5073), a method of copolymerizing a styrene-based monomer with a polyester resin having an acryloyl group (JP-A-59-45453).
JP-A-2-29), a method of copolymerizing a reactive polyester and a styrene monomer in the presence of a polyester resin (JP-A-2-29)
No. 664), a method of blocking a polyester resin and a styrene resin with an ester bond (Japanese Patent Laid-Open No. 2-881), and the like.

However, since the polyester resin and the styrenic resin are originally poor in compatibility, when merely mechanically mixing, depending on the mixing ratio, the resin and carbon black are internally added when the toner is formed. Dispersion of the agent becomes poor and chargeability becomes non-uniform, which causes a problem such as scumming in image evaluation. In addition, when the molecular weights of the two resins are different, a difference may occur in the melt viscosities of the two resins, which makes it difficult to reduce the dispersed particle size of the resin in the dispersed phase. The dispersion of the internal additive such as black is very poor, and there is a problem that the image stability is largely deteriorated. Further, when polymerizing a styrenic monomer on the reactive polyester, there is a problem that the composition is limited in order to prevent gelation.

Therefore, the present inventors previously blended, as a developer having both low temperature fixing property and anti-offset property, a mixture of two raw material monomers of a polymerization system in which a polymerization reaction is carried out by independent reaction paths. , A developer composition using a binder resin obtained by carrying out the two polymerization reactions in parallel in the same container (Japanese Patent Laid-Open No. 4-14
2301 publication).

However, when this method is applied to a combination of a polyester resin and a styrene resin to produce a resin, the fixing temperature can be lowered, but the molecular weight of the styrene resin as the dispersed phase can be increased. Therefore, the offset resistance was not sufficiently improved. Therefore, in view of the recent increase in speed of copying machines, further improvement in offset resistance is desired.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electrophotographic binder excellent in low-temperature fixability and offset resistance, and an electrophotographic toner containing the same.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the inventors of the present invention conducted a polymerization reaction in parallel in the same container using raw materials of polyester resin and styrene resin. By mixing and dispersing a high molecular weight styrene resin in the resin thus obtained, it was found that a binder having excellent low-temperature fixing property and offset resistance can be obtained,
The present invention has been completed.

That is, the present invention uses a mixture of a raw material monomer of a polyester resin and a raw material monomer of a styrene resin to carry out a polycondensation reaction to obtain a polyester resin and a radical polymerization reaction to obtain a styrene resin in the same container in parallel. Other styrene resin (2) in the resin (1) obtained by
The present invention relates to an electrophotographic binder in which the above are uniformly dispersed, a method for producing the same, and an electrophotographic toner containing the electrophotographic binder.

The polyester resin in the resin (1) used in the present invention comprises a polyhydric alcohol component and a polybasic carboxylic acid component such as polybasic carboxylic acid, polybasic carboxylic acid ester and carboxylic acid anhydride as raw material monomers. It is what

Here, as the divalent polyhydric alcohol component, for example, polyoxypropylene (2.2) -2,2-
Bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, poly Oxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl)
Propylene, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane and other bisphenol A alkylene oxide adducts, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3 -Propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,
4-Cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, hydrogenated bisphenol A and the like can be mentioned.

Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol and 1,2,4-. Butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethyl Examples thereof include benzene.

Examples of divalent polybasic carboxylic acid components include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid and succinic acid. , Adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, n-octyl succinic acid, isooctenyl succinic acid , Isooctyl succinic acid, anhydrides or lower alkyl esters of these acids, and the like.

Examples of trivalent or higher carboxylic acid components include 1,2,4-benzenetricarboxylic acid, 2,5,7-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, Examples thereof include 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, and anhydrides or lower alkyl esters of these acids.

Of these carboxylic acid components, it is preferable to use a monomer capable of undergoing both condensation polymerization and addition polymerization, such as fumaric acid and maleic acid. These carboxylic acid components are preferably used in a proportion of 0.5 to 10% by weight, particularly 0.5 to 5% by weight, based on the total raw material monomers of the polyester resin.

The polymerizable monomer used to form the styrene resin in the resin (1) used in the present invention and the styrene resin in the resin (2) may be the same or different. It may be one. Representative styrene resin polymerizable monomers are styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene,
Styrene-based monomers such as p-chlorostyrene and vinylnaphthalene; or such styrene-based monomers and vinyl-based monomers other than styrene-based monomers, such as ethylene-based unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; Vinyl halides such as vinyl chloride, vinyl bromide, vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl formate, vinyl caproate; such as acrylic acid, methyl acrylate, ethyl acrylate, acrylic acid n-propyl, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, amyl acrylate, cyclohexyl acrylate, n-acrylate
Octyl, isooctyl acrylate, decyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methoxyethyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-Methyl chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-methacrylic acid
Propyl, isopropyl methacrylate, n-methacrylic acid
Butyl, isobutyl methacrylate, tert-methacrylic acid
Butyl, amyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, decyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methoxyethyl methacrylate, 2-hydroxyethyl methacrylate, Ethylenic monocarboxylic acids such as glycidyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like; esters of ethylenic monocarboxylic acids such as acrylonitrile, methacrylonitrile, acrylamide; dimethyl maleate Ethylenic dicarboxylic acids and their substitution products; vinyl ketones such as vinyl methyl ketone; vinyl ethers such as vinyl methyl ether; If vinylidene halides such as vinylidene chloride; such as N- vinyl pyrrole, as combinations of such N- vinyl compounds such as N- vinylpyrrolidone.

If desired, a cross-linking agent may be used, and examples thereof include divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1 , 6-hexylene glycol dimethacrylate,
Neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane, 2,2'-bis (4-acryloxydiethoxyphenyl) propane , Trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, dibromoneopentylglycol dimethacrylate, diallyl phthalate and other general crosslinking agents, alone or in combination of two or more as necessary. Can be used.

If a large amount of these cross-linking agents is used, the toner is less likely to be melted by heat, resulting in poor heat fixing property or heat pressure fixing property. Further, when the amount used is small, it is difficult to prevent the offset phenomenon in which a part of the toner adheres to the roller surface without being completely fixed to the paper and is transferred to the next paper during heat roller fixing. Further, the amount of these cross-linking agents used is preferably 0.01 to 15% by weight, particularly 0.1 to 10% by weight, based on the polymerizable monomer.

The polymerization initiator used in producing the styrene resin is, for example, 2,2'-azobis (2,4-
Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile Azo or diazo polymerization initiators such as; benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, dicumyl peroxide, etc. Examples include physical polymerization initiators.

The polymerization initiator can be used in combination of two or more kinds for the purpose of controlling the molecular weight and molecular weight distribution of the polymer and the reaction time, and can be used in combination with 100 parts by weight of the polymerizable monomer. It is preferable to use 0.1 to 20 parts by weight, particularly 1 to 10 parts by weight.

In the binder of the present invention, the polyester resin component in the resin (1) forms a continuous phase, and the styrene resin component in the resin (1) and the styrene resin component in the resin (2) form a dispersed phase. It is necessary to form the dispersed phase, and the dispersed phase preferably has a diameter of 2.0 μm or less. When the dispersed phase becomes large, the mechanical strength of the toner becomes weak, and when printing is continued, the binder resin is broken and fine powder increases, so that the stability with time deteriorates. The particle size of the dispersed phase can be measured by cutting the toner with a microtome and observing the obtained flakes with a transmission scanning electron microscope.

The size of the dispersed phase may be controlled by the compatibility between the styrene resin of the resin (1) and the resin (2), the control by the mixing ratio of the resin (1) and the resin (2), and the like. However, the mixing ratio is 100 to 100 parts by weight of the binder, 65 to 98 parts by weight of the resin (1),
It is preferable to adjust within the range that (2) becomes 2 to 35 parts by weight. If the mixing ratio of the resin (1) and the resin (2) is out of this range, the toner may deviate from the proper charge amount.

The ratio of the polyester resin component to the styrene resin component in the binder of the present invention is 50/50 to 95/5, especially 70 /
The range of 30 to 90/10 is preferable. If the proportion of the styrene resin exceeds 50% by weight, the fixability will be poor, and if it is less than 5% by weight, the image stability against the environment will be poor, which is not preferable.

The resin (1) preferably has a softening point of 95 to 170 ° C. and a glass transition temperature of 50 to 80 ° C. The softening point and the glass transition temperature of the binder resin can be easily adjusted by adjusting the amount of the polymerization initiator or the catalyst in the raw material monomer mixture or selecting the reaction conditions.

The weight average molecular weight of the styrene resin in the resin (1) is preferably 60,000 or less in order to secure a sufficient low temperature fixing property. The weight average molecular weight of the resin (2) is 100,000 or more, in order to secure sufficient offset resistance.
In particular, it is preferably 200,000 or more. The average molecular weight of the styrene resin can be easily controlled by adjusting the amounts of the polymerization initiator and chain transfer agent used and the polymerization temperature.

The resin (1) is obtained by carrying out a condensation polymerization reaction for obtaining a polyester resin and a radical polymerization reaction for obtaining a styrene resin in parallel in the same container. The progress and completion of the polymerization reaction do not have to be simultaneous in time, and the reaction temperature and reaction time can be appropriately selected according to the respective reaction mechanisms to proceed and complete the reaction in sequence.

For example, as a typical method for producing the resin (1), in the raw material monomer mixture of the polyester resin component,
A mixture of the styrene resin raw material monomer and the polymerization initiator is added dropwise and mixed in advance to first complete the radical polymerization reaction for obtaining the styrene resin, and then the reaction temperature is raised to carry out the condensation polymerization reaction for obtaining the polyester resin. A method of completing the polymerization can be mentioned. As described above, the binder resin in which the fine styrene resin is dispersed in the polyester resin can be obtained by the method of allowing two independent reactions to proceed in parallel in the reaction container.

The resin (2) can be obtained by a usual solution polymerization method, emulsion polymerization method, suspension polymerization method, bulk polymerization method, dispersion polymerization method or the like.

The binder of the present invention is produced by mixing and dispersing the resin (2) in the resin (1) obtained as described above.

Of the two styrene-based resins which are the dispersed phase in the binder of the present invention, the styrene-based resin in Resin (1) has a chemical bond with the polyester resin which is the dispersion medium. On the other hand, the resin (2) can be distinguished from the polyester resin in that it does not have such a chemical bond.

The electrophotographic toner of the present invention comprises the binder of the present invention obtained as described above, or the resin (1) before mixing.
It can be produced by uniformly mixing the resin (2) with the coloring agent and then melt-kneading, cooling, pulverizing and classifying by a known method. Further, a charge control agent, wax, magnetic material, etc. may be blended in the toner of the present invention as required.

The colorant is not particularly limited, and conventionally known inorganic pigments such as carbon black and iron black, and chromatic dyes and organic pigments can be used. The colorant is preferably added in an amount of about 1 to 15 parts by weight based on 100 parts by weight of the binder resin.

The charge control agent used as necessary is not particularly limited. For example, in the case of using a negative charging toner, any negative charging charge conventionally known to be used for electrophotography is used. A control agent can also be used.
Specific examples of the negatively chargeable charge control agent include, for example, "Varifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", and "Bontron".
Metal-containing azo dyes such as "S-36" (all manufactured by Orient Chemical Co., Ltd.) and "Aizenspirone Black T-77" (manufactured by Hodogaya Chemical Co., Ltd.); for example, "Bontron E-82", "Bontron"
Metal complexes of copper phthalocyanine dyes such as E-84 "," Bontron E-85 "(all manufactured by Orient Chemical Co., Ltd.) and alkyl salicylate derivatives; for example," Copy Charge NX VP434 "
Examples thereof include quaternary ammonium salts (manufactured by Hoechst Co.) and the like, and they can be used alone or in combination of two or more kinds.

Further, a positively chargeable charge control agent can also be used in combination, and if 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, 50,000 sheets or more. Even if copying is performed continuously, a good visible image can be obtained without a decrease in density.

Specific examples of the positively chargeable charge control agent used in the case of using the positively chargeable toner or in combination with the negatively chargeable charge control agent in the negatively chargeable toner include, for example, "Nigrosine base". EX "" Oil Black
"BS", "Oil Black SO", "Bontron N-01",
"Bontron N-11" (above, manufactured by Orient Chemical Co., Ltd.),
Nigrosine dyes such as "Copy Blue PR" (manufactured by Hoechst); for example, "Bontron P-51" (manufactured by Orient Chemical Co.), cetyltrimethylammonium bromide, "Copy
Charge PX VP435 "(manufactured by Hoechst) and triphenylmethane dyes containing a tertiary amine as a side chain and quaternary ammonium salt compounds; for example, polyamine resins such as" AFP-B "(manufactured by Orient Chemical Co.); For example, "PLZ-2001",
Examples thereof include imidazole derivatives such as "PLZ-8001" (above, manufactured by Shikoku Kasei).

The above charge control agent is 0.1 with respect to the binder.
It is preferred to use ~ 8.0% by weight, especially 0.2-5.0% by weight.

Further, generally, when a toner is manufactured, a characteristic improving agent such as an offset preventing agent such as polyolefin or a fluidity improving agent such as hydrophobic silica is added as an offset preventing agent, and is added to the toner of the present invention. However, since the toner of the present invention is extremely excellent in offset resistance and fluidity, it is not necessary to add these property improving agents,
Moreover, even when adding, a small amount is sufficient.

Further, when the toner of the present invention is a magnetic toner, a magnetic substance is mixed. As a magnetic substance, a substance that is magnetized when placed in a magnetic field, such as iron or cobalt,
Powders of ferromagnetic metals such as nickel or alloys or compounds containing elements exhibiting ferromagnetism such as ferrite, hematite and magnetite can be used. These magnetic substances are preferably blended in an amount of 15 to 70% by weight based on the weight of the toner.

The electrophotographic toner of the present invention is further mixed with carrier particles such as iron powder, glass beads, nickel powder and ferrite powder, if necessary, and used as a developer for an electric latent image.

The toner of the present invention includes a magnetic brush developing method, a cascade developing method, a developing method using a conductive magnetic toner, a developing method using a high resistance magnetic toner, a fur brush developing method,
It can be applied to various developing methods such as a powder cloud method and an impression developing method.

[0044]

The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
The compositions shown in the examples are all expressed in parts by weight. Also,
The glass transition temperature (T _g ) of the obtained resin is measured by a differential scanning calorimeter, and the molecular weight is measured by GPC (gel permeation chromatography) according to the following conditions.

<Measurement of glass transition temperature> Using a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd.), the temperature was raised to 100 ° C.,
After standing at that temperature for 3 minutes, when cooling the sample cooled to room temperature at a temperature decrease rate of 10 ° C / min at a temperature increase rate of 10 ° C / min, the extension line and peak of the baseline below the glass transition temperature The temperature at the intersection with the tangent line showing the maximum slope between the rising portion and the apex of the peak is defined as the glass transition temperature (T _g ).

<Measurement of molecular weight by GPC> The column was stabilized in a constant temperature bath at 40 ° C., and chloroform was used as an eluent.
Flow at a flow rate of ml / min, and inject 100 μl of a chloroform solution of the sample adjusted to a sample temperature of 0.05 to 0.5% by weight for measurement. The molecular weight of the sample is calculated from the retention time of the peak, based on the calibration curve obtained from the sample having several kinds of monodisperse polystyrene as the standard for the molecular weight distribution of the sample. Analytical column: GMHLX + G3000HXL (Toyo Soda Co., Ltd.)

Resin Production Example 1 Styrene-based resin monomer: styrene 410 g and 2-
90 g of ethylhexyl acrylate and 20 g of azobisisobutyronitrile as a polymerization initiator were placed in a dropping funnel. On the other hand, polyoxypropylene (2.2) -2,2-bis
(4-hydroxyphenyl) propane 780g, fumaric acid 24
g, isododecenyl succinic anhydride 76 g, terephthalic acid
250 g and dibutyl tin oxide 2 g were put into a 5 liter glass four-necked flask, and a thermometer, a stainless stir bar, a flow-down condenser and a nitrogen inlet tube were attached. Place this in a mantle heater under a nitrogen stream for 13
The styrene resin monomer and the polymerization initiator were added dropwise from the above dropping funnel over 1 hour while stirring at 5 ° C., and the temperature was raised to react at 220 ° C. The degree of polymerization is ASTM E28-
Following the softening point according to 67, when the softening point reached 105 ° C, the reaction was terminated. The obtained resin is a pale yellow solid and has a glass transition temperature of 60 with only one peak.
It was ℃. The weight average molecular weight of the styrene acrylate resin in the resin by GPC was about 30,000.
The resin is referred to as a binder resin (A).

Resin Production Example 2 Styrene 400 g and 2-
180 g of ethylhexyl acrylate, 15 g of α-methylstyrene dimer as a chain transfer agent, and 25 g of dicumyl peroxide as a polymerization initiator were placed in a dropping funnel. On the other hand, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 800g, fumaric acid 15g, 1,
2,4-benzenetricarboxylic acid 60g, isophthalic acid 250
g and 2 g of dibutyltin oxide were placed in a 5 liter glass four-necked flask, and a thermometer, a stainless stir bar, a downflow condenser and a nitrogen introduction tube were attached.
Thereafter, the same procedure as in Resin Production Example 1 was carried out to obtain a resin. The glass transition temperature of the obtained resin has only one peak,
It was 58 ° C. The weight average molecular weight of the styrene acrylate resin in the resin by GPC was about 45,000. The resin is referred to as a binder resin (B).

Resin Production Example 3 550 g of xylene was placed in a 5 liter glass four-necked flask equipped with a thermometer, a stainless stir bar, a falling condenser and a nitrogen introducing tube, and the temperature was raised to 135 ° C. after introducing nitrogen. Styrene as a monomer of styrene resin 800g
Then, 300 g of n-butyl acrylate and 30 g of dicumyl peroxide as a polymerization initiator were placed in a dropping funnel and added dropwise over 1 hour, followed by aging at 135 ° C. for 2 hours. Then, the temperature was raised to 200 ° C., xylene was distilled off under reduced pressure, the mixture was extracted into a vat, cooled, and then pulverized. ASTM E28
The softening point according to -67 was 130 ° C, and the glass transition temperature was 65 ° C. The weight average molecular weight of the resin measured by GPC is about 80,
It was 000. The resin is referred to as a binder resin (C).

Resin Production Example 4 1400 g of ion-exchanged water and 7 g of 50% aqueous solution of dioctyl sulfosuccinate sodium salt were added to a 5 liter four-necked flask equipped with a stirrer, a flow-down condenser, a thermometer and a nitrogen blowing tube. When the temperature was raised to 0 ° C, a solution prepared by dissolving 7 g of potassium persulfate in 50 g of ion-exchanged water was added, and then a mixed solution of 760 g of styrene and 240 g of n-butyl acrylate was added over 1 hour. After dropping, the mixture was aged for 1.5 hours at 70 ° C., then salted out, washed and dried to obtain a resin. The resulting resin had a softening point of 145 ° C and a glass transition temperature of 68 ° C. The weight average molecular weight of the resin measured by GPC was about 250,000. Binder resin
(D).

Resin Production Example 5 Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 714 g, polyoxyethylene (2.2) -2,2
-Bis (4-hydroxyphenyl) propane 663g, isophthalic acid 518g, isooctenyl succinic acid 70g, 1,2,4-
80 g of benzenetricarboxylic acid and 3 g of dibutyltin oxide were placed in a 5 liter glass four-necked flask, a thermometer, a stainless steel stirrer, a downflow condenser and a nitrogen introduction tube were attached, and in a mantle heater,
The reaction was carried out with stirring at 210 ° C under a nitrogen stream, and the reaction was terminated when the softening point reached 100 ° C. The obtained resin was a pale yellow solid and had a glass transition temperature of 61 ° C.
The resin is referred to as a binder resin (E).

Examples 1 to 4 and Comparative Examples 1 and 2 Materials having the following compositions were well mixed in a Henschel mixer, kneaded in a twin-screw extruder, cooled, and coarsened,
The toner was pulverized with a jet mill and further classified with an air classifier to obtain an untreated toner having an average particle size of 10 μm.

[0053]

[Table 1] Example 1 Binder resin (A) 80 parts Binder resin (D) 20 parts Carbon black (Cabot Co., Regal 330R) 6 parts Negative charge control agent (Hodogaya Chemical Co., Ltd. Aizenspirone) Black T-77) 2 parts Low molecular weight polypropylene (Mitsui Petrochemical Co., NP-055) 2 parts

[0054]

[Table 2] Example 2 Binder resin (A) 70 parts Binder resin (D) 30 parts Carbon black (Cabot Co., Regal 330R) 6 parts Negatively chargeable charge control agent (Hodogaya Chemical Co., Ltd. Eisenspirone) Black T-77) 2 parts Low molecular weight polypropylene (Mitsui Petrochemical Co., NP-055) 2 parts

[0055]

[Table 3] Example 3 Binder resin (B) 80 parts Binder resin (D) 20 parts Carbon black (Cabot Co., Regal 330R) 6 parts Negative charge control agent (Hodogaya Chemical Co., Ltd. Aizenspirone) Black T-77) 2 parts Low molecular weight polypropylene (Mitsui Petrochemical Co., NP-055) 2 parts

[0056]

[Table 4] Example 4 Binder resin (A) 80 parts Binder resin (C) 20 parts Carbon black (Cabot Co., Regal 330R) 6 parts Negative charge control agent (Hodogaya Chemical Co., Ltd. Aizenspirone) Black T-77) 2 parts Low molecular weight polypropylene (Mitsui Petrochemical Co., NP-055) 2 parts

[0057]

[Table 5] Comparative Example 1 Binder resin (A) 100 parts Carbon black (Cabot Co., Regal 330R) 6 parts Negative charge control agent (Hodogaya Chemical Co., Aizenspiron Black T-77) 2 parts Low Molecular weight polypropylene (Mitsui Petrochemical Co., NP-055) 2 parts

[0058]

[Table 6] Comparative Example 2 Binder resin (D) 80 parts Binder resin (E) 20 parts Carbon black (Cabot Co., Regal 330R) 6 parts Negative charge control agent (Hodogaya Chemical Co., Ltd. Aizenspirone) Black T-77) 2 parts Low molecular weight polypropylene (Mitsui Petrochemical Co., NP-055) 2 parts

Test Example 1 For each 1000 parts by weight of the untreated toners obtained in Examples 1 to 4 and Comparative Examples 1 and 2, the hydrophobic silica "AEROSIL" was used.
3 g of "R-972" (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed and attached using a Henschel mixer to complete the toner. A developer was prepared by mixing 66 parts of each of the above toners and 2134 parts of a ferrite powder (average particle size: 100 μm) coated with a silicone resin. Commercially available electrophotographic copying machines with these developers (photoreceptor is amorphous selenium, fixing roller rotation speed is set to 450 mm / sec, heat roller temperature in fixing device is variable, and oil applying device is removed) Then, the image was printed out, and the fixing property was evaluated according to the following method. <Evaluation method of fixability> Rubbing the image fixed through a fixing machine on a sand eraser with a bottom of 15 mm x 7.5 mm for 5 times with a load of 500 g, and before and after rubbing the optical reflection density of Macbeth It was measured using a densitometer, and the temperature of the fixing roller when the fixing rate defined by the following formula exceeded 70% was defined as the minimum fixing temperature. The temperature of the fixing roller is
The temperature was controlled between 120 and 240 ° C. The results are shown in Table 7.
Shown in.

[0060]

[Equation 1]

[0061]

[Table 7]

As is apparent from Table 7, all the toners of the present invention had a low minimum fixing temperature and a high high temperature offset generation temperature, and had excellent performance. On the other hand, in Comparative Example 1, the minimum fixing temperature was low, but the high temperature offset generation temperature was low, and in Comparative Example 2, the minimum fixing temperature was high and the high temperature offset generation temperature was also low.

[0063]

The electrophotographic binder of the present invention and the electrophotographic toner using the same have excellent low-temperature fixability and offset resistance.

Claims (5)

[Claims] 1. A mixture of a raw material monomer for a polyester resin and a raw material monomer for a styrene resin is used to obtain a polyester resin and a radical polymerization reaction for obtaining a styrene resin in the same container in parallel. A binder for electrophotography, in which another styrene resin (2) is uniformly dispersed in the obtained resin (1). 2. The styrene resin (2) has a weight average molecular weight of 1
The binder for electrophotography according to claim 1, which is at least 0,000. 3. The dispersed phase styrene resin has a diameter of 2.
The binder for electrophotography according to claim 1, which has a thickness of 0 μm or less. 4. A mixture of a raw material monomer for a polyester resin and a raw material monomer for a styrenic resin, and the polycondensation reaction for obtaining a polyester resin and the radical polymerization reaction for obtaining a styrenic resin are carried out in parallel in the same container. A method for producing a binder for electrophotography, which comprises mixing and dispersing another styrene-based resin produced separately into the resin. 5. An electrophotographic toner containing the electrophotographic binder according to claim 1.