JP2006292820A - Resin composition for electrophotographic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for electrophotographic toner from which the electrophotographic toner for a heat roll fixing system, hardly causing hot offset and having excellent low temperature fixing property can be preferably obtained. <P>SOLUTION: The resin composition for electrophotographic toner contains a reaction product (P) of rosin (R) and an epoxy group-containing compound (E), preferably a reaction product of gum rosin and/or tall rosin and a bisphenol epoxy resin and/or a novolac epoxy resin, and a binder resin (Q), preferably a polyester resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin composition for an electrophotographic toner that can favorably obtain an electrophotographic toner for a heat fixing system that hardly causes hot offset and is excellent in low-temperature fixability.

  In a so-called electrophotographic printing method in which an electrostatic latent image formed on a photoreceptor is visualized by an electrophotographic toner and information is fixed on a medium through a process such as transfer, the printing speed can be increased. A method (heat roll fixing method) in which electrophotographic toner is fused onto a medium by a roll (heat roll) is currently the mainstream.

  In this heat roll fixing system, the tendency to reduce the heat energy used as much as possible has become remarkable due to the recent increase in environmental conservation awareness. That is, there is a need for an electrophotographic toner that can be fixed at a lower temperature.

  However, since the electrophotographic toner used in the heat roll fixing method is required to have a performance not to be offset (hot offset) to the fixing roll, the binder resin (binder) used for the electrophotographic toner is a high molecular weight thermoplastic resin. Alternatively, partially crosslinked thermoplastic resins have been mainly used. For this reason, it is necessary to set a high temperature for fixing and fixing the electrophotographic toner (fixing temperature), and the current social demand for energy saving is not fully satisfied.

  In such a situation, in order to obtain an electrophotographic toner having a low fixing temperature, for example, an electrophotographic toner comprising colored particles containing a rosin ester having an acid value of 2 or less and an external additive is disclosed (for example, Patent Document 1). However, even with the electrophotographic toner described in Patent Document 1, it is necessary to set the fixing temperature to about 135 ° C., and there is a demand for a resin composition for electrophotographic toner that can be used at a lower fixing temperature.

JP 2003-322997 A

  An object of the present invention is to provide a resin composition for an electrophotographic toner capable of suitably obtaining an electrophotographic toner for a heat fixing system that hardly causes hot offset and has excellent low-temperature fixability. is there.

  As a result of intensive studies, the present inventors, instead of the rosin ester obtained by esterifying the rosin used in Patent Document 1 with an alcohol, contain a reaction product of a rosin and an epoxy group-containing compound and a binder resin. The electrophotographic toner obtained using the resin composition has a fixing temperature of about 95 to 115 ° C., which can be as low as about 20 to 40 ° C. compared to the toner of Patent Document 1, and a temperature at which a hot offset phenomenon starts (offset start temperature). ) Is as high as 190 to 200 ° C. and has excellent offset resistance, and the present invention has been completed.

  That is, the present invention comprises an electrophotographic toner resin composition comprising a reaction product (P) of a rosin (R) and an epoxy group-containing compound (E) and a binding resin (Q). Is to provide.

  According to the present invention, it is possible to provide a resin composition capable of obtaining an electrophotographic toner having both low temperature fixability and hot offset property.

  The rosin (R) used in the present invention is a general term for low-volatile resin acids obtained from trees, and the main component is derived from natural products including abietic acid, which is a kind of tricyclic diterpenes, and isomers thereof. It is a substance. Specific components include, for example, levopimaric acid, pultrinic acid, neoabietic acid, dehydroabietic acid, dihydroabietic acid and the like in addition to abietic acid, and rosin (R) used in the present invention is a mixture thereof. is there. The rosins are roughly classified into three types according to the collection method: tol rosin using pulp as raw material, gum rosin using raw pine oil as raw material, and wood rosin using pine root as raw material. Rosin belongs to a monocarboxylic acid as a chemical structure, and a carboxyl group is a typical reactive group. Since rosin (R) used in the present invention is easily available, gum rosin and / or tall rosin is preferable.

  The epoxy group-containing compound (E) used in the present invention is a compound containing one or more epoxy groups in one molecule and is a condensate of bisphenol A and epichlorohydrin, bisphenol type epoxy resin, phenol novolac resin. Typical examples include a condensate of chloroquine and epichlorohydrin, a novolak type epoxy resin which is a condensate of cresol novolac resin and epichlorohydrin, and the like. A vinyl polymer obtained by copolymerizing glycidyl methacrylate (GMA) can also be used as the epoxy group-containing compound (E).

  Furthermore, the compounds shown below can also be used as the epoxy group-containing compound (E). Specifically, various aliphatic or fats such as ethylene glycol, 1,6-hexanediol, neopentyl glycol, trimethylol propane, trimethylol ethane, glycerin, pentaerythritol, sorbitol, or hydrogenated bisphenol A are used. Polyglycidyl ethers of cyclic polyols;

Polyglycidyl ethers of various aromatic diols such as hydroquinone, catechol, resorcin, bisphenol A, bisphenol S or bisphenol F; such as the ethylene oxide or propylene oxide adducts of aromatic diols as listed above; Diglycidyl ethers of aromatic diol derivatives;

Polyglycidyl ethers of various polyether polyols such as polyethylene glycol, polypropylene glycol or polytetramethylene glycol; polyglycidyl ethers of tris (2-hydroxyethyl) isocyanurate; adipic acid, butanetetracarboxylic acid, propanetricarboxylic acid Polyglycidyl esters of various aliphatic or aromatic polycarboxylic acids such as acid, phthalic acid, terephthalic acid or trimellitic acid;

Various bisepoxides of various hydrocarbon dienes such as butadiene, hexadiene, octadiene, dodecadiene, cyclooctadiene, α-pinene or vinylcyclohexene; bis (3,4-epoxycyclohexylmethyl) adipate or 3,4- Various alicyclic polyepoxy compounds such as epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate; or various epoxidized products of various diene polymers such as polybutadiene or polyisoprene;

Various homopolymers of various epoxy group-containing vinyl monomers or epoxy group-containing vinyl monomers, (meth) acrylic vinyl monomers, vinyl ester vinyl monomers, vinyl ether vinyl monomers Epoxy group obtained by copolymerizing monomers, copolymerizable monomers such as aromatic vinyl vinyl monomers, fluoroolefin vinyl monomers and other epoxy group-containing vinyl monomers Examples thereof include various vinyl copolymers such as an acrylic copolymer, a vinyl ester copolymer, and a fluoroolefin copolymer.

  As the epoxy group-containing compound (E) used in the present invention, a bisphenol type epoxy resin and / or a novolak type epoxy resin is preferable because a reaction product (P) having a high glass transition temperature (Tg) can be easily obtained. .

  The reaction product (P) used in the present invention is obtained by reacting the rosin with the epoxy group-containing compound (E). The reaction between the rosin (R) and the epoxy group-containing compound (E) proceeds mainly by a ring-opening reaction between the carboxyl group of the rosin (R) and the epoxy group of the epoxy group-containing compound (E). In this case, the reaction temperature is preferably a temperature that is equal to or higher than the melting points of both constituent components and can be uniformly mixed, and is specifically in the range of about 60 to 200 ° C. In the reaction, a catalyst for promoting the ring-opening reaction of the epoxy group may be added. Examples of the catalyst that can be used include amines such as ethylenediamine, trimethylamine, and 2-methylimidazole; quaternary ammonium salts such as butyltrimethylammonium chloride; and triphenylphosphine. The reaction can be carried out by various methods. In general, in the case of a batch system, a rosin (R) is added to a heatable flask equipped with a condenser, a stirrer, an inert gas inlet, a thermometer and the like at a predetermined ratio. ) And the epoxy group-containing compound (E), heated and melted, and appropriately sampled the reaction product, so that the progress of the reaction can be traced. The degree of progress of the reaction can be confirmed mainly by a decrease in the acid value, and the reaction can be completed as appropriate when reaching the stoichiometric end point or the vicinity thereof. The reaction ratio between the rosin (R) and the epoxy group-containing compound (E) is not particularly limited, but the carboxylic acid group (r) in the rosin (R) is the epoxy group (e) in the epoxy group-containing compound (E). The molar ratio of the carboxylic acid group (r) in the rosin (R) to the epoxy group (e) in the epoxy group-containing compound (E) is preferably [(r). / (E)] is more preferably in the range of 1.05 to 2.

  The acid value of the reaction product P used in the present invention is preferably 0.5 to 50 mgKOH / g, more preferably 0.5 to 15 mgKOH / g. 60-120 degreeC is preferable and, as for the melt viscosity (T1 / 2) by a Koka type flow tester, 60-100 are more preferable. The glass transition temperature (Tg) determined by differential scanning calorimetry (DSC) is preferably 40 to 100 ° C, more preferably 50 to 90 ° C. The T1 / 2 is the temperature when the plunger (piston) comes to the middle point in the process from the start of the outflow to the end of the outflow in the Koka-type flow tester (CFT-500D manufactured by Shimadzu Corporation). Say.

Next, the binding resin (Q) used in the present invention will be described.
Any binder resin (Q) can be used as long as it can be used as the main binder of the electrophotographic toner. Typical examples include styrene-acrylic copolymers, polyester resins, and epoxy resins. Among these, polyester resins are preferable because of a good balance of fixability and offset resistance.

The polyester resin can be prepared by a well-known conventional method. The raw material used in that case can be used without particular limitation as long as it is a known and common raw material constituting the polyester resin. Typical examples of such raw materials include polybasic acids such as dicarboxylic acids and their anhydrides or their lower alkyl esters (hereinafter referred to as “polybasic acids”) and polyhydric alcohols such as diols. -The following are preferably used.

  Examples of the dicarboxylic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, oxalic acid, malonic acid, succinic acid, succinic anhydride, dodecyl succinic acid, dodecyl succinic anhydride, dodecenyl succinic acid, Aliphatic dibasic acids such as dodecenyl succinic anhydride, adipic acid, azelaic acid, sebacic acid, decane-1,10-dicarboxylic acid;

Phthalic acid, phthalic anhydride, tetrahydrophthalic acid and its anhydride, hexahydrophthalic acid and its anhydride, tetrabromophthalic acid and its anhydride, tetrachlorophthalic acid and its anhydride, het acid and its anhydride, Himic And aromatic or alicyclic dibasic acids such as isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid.

  Furthermore, a carboxylic acid having three or more carboxyl groups in one molecule and a reactive derivative thereof can be used as a trifunctional or higher functional raw material component. Typical examples of these include trimellitic acid, trimellitic anhydride, methylcyclohexentricarboxylic acid, methylcyclohexentricarboxylic anhydride, pyromellitic acid, pyromellitic anhydride, and the like.

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

  Furthermore, as the above-mentioned polybasic acids, those in which part or all of the carboxyl groups are alkyl esters, alkenyl esters or aryl esters can also be used.

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

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

  Next, typical examples that can be used as the polyhydric alcohol component include bisphenol A derivatives such as bisphenol A and polyalkylene oxide adducts of bisphenol A; ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, neo And aliphatic diols such as pentyl glycol; and alicyclic diols such as cyclohexanedimethanol.

  In addition, aliphatic monoepoxy compounds such as “Cadurah E10” [monoglycidyl ester of branched fatty acid manufactured by Shell Chemical Co., Ltd.] can also be used as such diols.

  A compound having three or more hydroxyl groups can also be used as one of trifunctional or higher functional ingredients, and typical examples thereof include glycerin, trimethylolethane, trimethylolpropane, sorbitol, 1,2 , 3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, 2-methylpropanetriol, 1,3,5-trihydroxybenzene, tris (2 -Hydroxyethyl) isocyanurate.

  Further, although not a polyhydric alcohol component, an epoxy group-containing compound having one or more epoxy groups in one molecule can also be used as a raw material for preparing a polyester resin. -There are epoxy type epoxy resin and novolak type epoxy resin.

  As a method of preparing the polyester resin, a method of preparing a polyester resin by dehydrating and condensing the above-described raw material polybasic acids and polyhydric alcohols under heating in a nitrogen atmosphere is common. As an apparatus used at this time, a batch-type production apparatus such as a reaction vessel equipped with a nitrogen inlet, a thermometer, a stirrer, a rectifying column, etc. can be suitably used, and an extruder equipped with a deaeration port Alternatively, a continuous reaction apparatus, a kneader or the like can be used. In the dehydration condensation, the esterification reaction can be promoted by reducing the pressure of the reaction system as necessary. Furthermore, a known and commonly used catalyst can be added to accelerate the esterification reaction.

  As the binding resin (Q) used in the present invention, a polyester resin is preferable. Among these polyester resins, a specific molecular weight range or a specific structure is required to obtain good fixability and offset resistance. Is preferred.

  That is, the weight average molecular weight of the polyester resin soluble in tetrahydrofuran (THF) by gel permeation chromatography (GPC) is preferably in the range of 5,000 to 500,000. Further, the polyester resin preferably has a branched structure. This branched polyester resin can be easily prepared by using a trifunctional or higher functional raw material component in combination among the raw material components used in preparing the above-described polyester resin.

  In order to obtain a polyester resin having such properties, a method by esterification is simple, but more preferably, a method of mixing a plurality of polyester resins having different molecular weight ranges in preparation of a toner is simpler, In addition, the degree of freedom in designing the toner is great. Specifically, the THF-soluble GPC method weight average molecular weight (Mw) is in the range of 5,000 to 25,000, and the differential scanning calorimetry (DSC) glass transition temperature (Tg) is 50. Mix the polyester resin (q1) at ˜90 ° C. with the polyester resin (q2) whose Mw is 25,000 to 500,000 by GPC method and Tg is 50 to 90 ° C. by DSC method. The polyester resin obtained by this is preferable.

  When mixing the polyester resin (q1) and the polyester resin (q2), when the weight of the polyester resin (q1) is (w1) and the weight of the polyester resin (q2) is (w2), the polyester resin ( It is preferable to mix q1) and the polyester resin (q2) so as to be 10/90 to 90/10 in terms of (w1) / (w2).

  As the mixing ratio [(P) / (Q)] of the reaction product (P) and the binder resin (Q), an electrophotographic toner having a good balance between fixability and hot offset can be obtained. 0.05-1 is preferable on a weight basis, and 0.1-0.5 is more preferable.

  Any melt viscosity of the resin composition for an electrophotographic toner of the present invention can be used as long as the toner can be used, but the flow start temperature (Tfb) by the Koka type flow tester is 80 to 80. 110 ° C. is preferred. Moreover, 120-150 degreeC is preferable for the 1/2 fall temperature (T1 / 2) of the plunger by an elevating type flow tester.

  The Tfb is a temperature displayed as the temperature at the outflow start point of the temperature / piston stroke curve in the Koka type flow tester (CFT-500D manufactured by Shimadzu Corporation). The load at the time of measurement is 10 kg, and the heating rate is 6 ° C./min. T1 / 2 means the temperature at which the plunger (piston) reaches the middle point in the process from the start of the outflow to the end of the outflow in the Koka-type flow tester (CFT-500D manufactured by Shimadzu Corporation). .

  Examples of a method for preparing an electrophotographic toner using the resin composition for an electrophotographic toner of the present invention include a preparation method including the following steps. First, after preparing a mixture by premixing the resin composition for an electrophotographic toner of the present invention, a colorant and, if necessary, a charge control agent, a wax, a flow regulator and the like with a Henschel mixer or the like, this mixture is mixed with 3 The mixture is melt kneaded with an apparatus such as a roll, a pressure kneader, or a twin screw extruder to obtain a kneaded product. Next, the kneaded product is cooled, coarsely pulverized, and toner particles having a predetermined particle diameter are obtained by a method such as a mechanical pulverization method using a turbo mill or an air pulverization method using a jet mill. Further, the toner particles are generally classified by an air classifier or the like as necessary. Usually, the volume average particle diameter is adjusted to 5 to 15 μm. In addition, the toner particles thus prepared are generally mixed with fine particles such as silica powder, titanium oxide and alumina as external additives in order to improve the fluidity of the powder and the charging characteristics. is there.

  Examples of the colorant include various carbon blacks produced by a thermal black method, an acetylene black method, a channel black method, a furnace black method, a lamp black method and the like in the case of a black toner. . In the case of color toner, phthalocyanine bull, aniline bull, calco oil bull, ultramarine bull, methylene bull chloride, malachite green oxate, chrome yellow, quinoline yellow, dupont oil red, rose bengal Pigments, nigrosine-type or rhodamine-type dyes, and the like, which can be used alone or in combination of two or more.

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

  The wax is added so as to prevent the toner from offsetting to a fixing roll of a copying machine or a printer and to enable low-temperature fixing. Typical examples thereof include polypropylene wax, Polyethylene wax, polyamide wax, Fischer-Tropsch wax, synthetic ester wax, various natural waxes and the like can be used as appropriate. Among them, carnauba wax, montan ester wax, rice wax and / or scale insect wax are preferably used. .

  The flow modifier is added to improve the fluidity of the toner. For example, vinylidene fluoride fine powder, polytetrafluoroethylene fine powder, wet or dry silica fine powder, and the like can be used. .

  The electrophotographic toner obtained by using the resin composition for an electrophotographic toner of the present invention is remarkably low in comparison with a conventional electrophotographic toner when used as a two-component developer or a non-magnetic one-component developer. Printing can be performed at a fixing temperature, and the thermal stability of the electrophotographic toner is good, and further, an excellent electrophotographic toner without an offset phenomenon can be obtained without a decrease in elasticity of the binder resin itself.

  Next, the present invention will be specifically described with reference to Examples and Comparative Examples. In the examples, “parts” means parts by weight unless otherwise specified.

Synthesis Example 1 [Synthesis of reaction product (P) of rosin (R) and epoxy group-containing compound (E)]
Into a 5 L flask equipped with a condenser, a stirrer, a nitrogen gas inlet and a thermometer, 1,346 g of gum rosin X (Dainippon Ink Chemical Co., Ltd., gum rosin, acid value 178 mgKOH / g) and Epicron 1050 [ A bisphenol A type epoxy resin manufactured by Dainippon Ink & Chemicals, Inc., epoxy equivalent 480] and 3,456 g were charged and the temperature was raised to 130 ° C. over 1 hour, and the reaction system was uniformly stirred. Then, 3.3 g of triphenylphosphine was added and the temperature was raised to 190 ° C. over 1 hour. The ring opening reaction between the acid group of rosin and the epoxy group of the epoxy resin is carried out continuously for 4 hours at the same temperature, the acid value is 0.8 mgKOH / g, and the melt viscosity (T1 / 2) by Koka type flow tester A reaction product having a temperature of 106 ° C. and a glass transition temperature (Tg) by differential scanning calorimetry (DSC) of 64 ° C. was obtained. This is abbreviated as (P-1).

Synthesis example 2 (same as above)
Into a 5 L flask equipped with a cooling tube, a stirrer, a nitrogen gas inlet, and a thermometer, 1,200 g of Heartol rosin RX (Tallrosin, acid value 175 mgKOH / g, manufactured by Harima Chemical Co., Ltd.) and Epicron 1050 3,456 g was charged and the temperature was raised to 130 ° C. over 1 hour. After confirming that the reaction system was uniformly stirred, the temperature was raised to 200 ° C. over 1 hour. The ring-opening reaction between the acid group of rosin and the epoxy group of the epoxy resin is continued for 2 hours at the same temperature, the acid value is 0.4 mgKOH / g, T1 / 2 is 91 ° C., and Tg by DSC method is 50 ° C. A reaction product was obtained. This is abbreviated as (P-2).

Synthesis example 3 (same as above)
Into a 5 L flask equipped with a condenser, a stirrer, a nitrogen gas inlet, and a thermometer, 2,205 g of Tolurosin X and Epicron 660 [Crezo-Lunovolak type epoxy resin manufactured by Dainippon Ink & Chemicals, Ltd., Epoxy equivalent 208] 2,619 g was charged and the temperature was raised to 140 ° C over 1 hour. After confirming that the reaction system was uniformly stirred, the temperature was raised to 200 ° C over 1 hour. Raised. The ring-opening reaction between the acid group of rosin and the epoxy group of the epoxy resin is continued for 2 hours at the same temperature, the acid value is 0.7 mgKOH / g, T1 / 2 is 126 ° C., and Tg by DSC method is 66 ° C. A reaction product was obtained. This is abbreviated as (P-3).

Synthesis Example 4 [Synthesis Example of Binder Resin (Q)]
A 5 liter flask equipped with a rectifying column, a stirrer, a nitrogen gas inlet and a thermometer was charged with 525 g of ethylene glycol, 858 g of neopentyl glycol and 168 g of trimethylolpropane, and took 1 hour. After raising the temperature to 120 ° C. and confirming that the inside of the reaction system was uniformly stirred, 2.0 parts of dibutyltin oxide was added. Next, 2,712 g of terephthalic acid and 112 g of Khajura E10 (monoglycidyl ester of branched fatty acid manufactured by Shell Chemical Co., Ltd.) were charged, and the temperature was raised from the same temperature to 240 ° C. for 10 hours while distilling off the generated water. Raised. The dehydration condensation reaction is continued for 8 hours at the same temperature, the acid value is 12.0 mgKOH / g, the reaction is continued until T1 / 2 reaches 158 ° C, the Tg by DSC method is 60 ° C, the gel permeation (GPC) method A polyester resin having a weight average molecular weight (Mw) of 226,000 was obtained. This is abbreviated as binder resin (Q-1).

Synthesis example 5 (same as above)
Into a 5 liter flask equipped with a rectifying column, a stirrer, a nitrogen gas inlet, and a thermometer, 460 g of ethylene glycol, 772 g of neopentyl glycol and 850% epiclone [manufactured by Dainippon Ink & Chemicals, Inc. 196 g of bisphenol type epoxy resin, epoxy equivalent 190] was added, and after 1 hour, the temperature was raised to 120 ° C. and it was confirmed that the inside of the reaction system was uniformly stirred. 0 g was charged. Next, 2,460 g of terephthalic acid and 112 g of cadura E10 were charged, and the temperature was raised from the same temperature to 240 ° C. over 10 hours while distilling off the generated water. The dehydration condensation reaction is continued for 8 hours at the same temperature, and the reaction is continued until the acid value is 13.0 mgKOH / g and T1 / 2 reaches 188 ° C., the DSC Tg is 58 ° C., the GPC Mw is 305, A polyester resin of 000 was obtained. This is abbreviated as binder resin (Q-2).

Synthesis Example 6 (same as above) [Synthesis Example of Binder Resin (Q)]
Into a 5 liter flask equipped with a rectifying column, a stirrer, a nitrogen gas inlet, and a thermometer, 496 parts of ethylene glycol and 832 parts of neopentyl glycol are charged and temperature is required for 1 hour. Was raised to 120 ° C., and after confirming that the inside of the reaction system was uniformly stirred, 2.0 parts of dibutyltin oxide was added. Next, 2,400 parts of terephthalic acid and 272 parts of para-tert-butylbenzoic acid were charged, and the temperature was raised from the same temperature to 240 ° C. over 10 hours while distilling off the generated water. The dehydration condensation reaction was continued for another 8 hours at the same temperature, the acid value was 11.0 mgKOH / g, the softening point by the ring and ball method was 106 ° C., the glass transition temperature (Tg) by the DSC method was 56 ° C., and the Mw by the GPC method was 6 800 polyester resin was obtained. This is abbreviated as polyester resin (Q-3).

Example 1
The reaction product (P-1), binder resin Q-1, colorant, wax and charge control agent are blended in the proportions shown in Table 1, mixed with a Henschel mixer, and melt-kneaded with a twin screw extruder. Thereafter, the kneaded product was cooled and coarsely pulverized, and finely pulverized using a jet mill. Subsequently, the finely pulverized product was classified to prepare a volume average particle size of 10 μm, and resin fine particles were prepared.
To 100 parts by weight of the resin fine particles, 1 part by weight of silica HDK3050EP (silica powder manufactured by Wakka Chemicals Co., Ltd.) was added and mixed with a Henschel mixer to obtain an electrophotographic toner. The obtained electrophotographic toner was evaluated for flow start temperature (Tfb), plunger half drop temperature (T1 / 2), fixing start temperature, fixing strength, offset start temperature, and storage stability. The evaluation methods for fixing start temperature, fixing strength, offset start temperature and storage stability are shown below. The results are shown in Table 3.

<Evaluation method of fixing start temperature>
The set temperature of the heat roll is changed from 80 ° C to 210 ° C in 5 ° C increments, and a mending tape (manufactured by Sumitomo 3M) is attached to the solid print portion, and the tape is further fixed at a constant speed in a certain direction. When the image density before and after peeling was measured with a Macbeth densitometer (RD-918) and the ratio of the density value after peeling to the value before peeling was expressed in%, the value was 80% The above temperature was defined as the fixing start temperature. The lower this temperature is, the better the toner has a low-temperature fixability.

<Method for evaluating fixing strength>
Solid printing was performed at a set temperature of the heat roll of 120 ° C., and the image density of the obtained solid printing surface was measured with a Macbeth densitometer (RD-918). A mending tape (manufactured by Sumitomo 3M) is attached to the solid printing surface, and the image density before and after peeling is measured with a Macbeth densitometer (RD-918) when the tape is peeled in a constant direction at a constant speed. The ratio of the concentration value after peeling to the value before peeling was expressed in%. The larger this value, the better the toner at low temperature fixability.

<Evaluation method of offset start temperature>
When the set temperature of the heat roll was changed from 80 ° C. to 210 ° C. in increments of 5 ° C., the solid print portion was offset again on the same paper and displayed at the lowest temperature that can be visually confirmed. The higher this temperature, the better the offset resistance.

<Evaluation method of storage stability test>
50 g of toner was put in a 100 cc polyethylene container (with an inner lid), sealed, and evaluated for the aggregation state of toner powder after storage for 7 days in a thermostat adjusted to 50% relative humidity at 50 ° C. The evaluation criteria are as follows.
A: The fluidity is good with no change from before storage.
○: Take out from the container and touch it with your hand.
Δ: When the container is taken out from the container onto the paper, it comes out with the shape of the container maintained about half, but it loosens when the lump is loosened by hand.
X: When it is taken out from a container on paper, it comes out in a state where the shape of the container is maintained as it is, and when loosened by hand, there is a hard agglomerate.

The condition settings for the fixing roll and the like are as follows.
Roll material: Top; Polytetrafluoroethylene, Bottom; Silicon Upper roll load: 20 kg
Nip width: 10mm
Paper feed speed: 80 cm / sec

Examples 2 to 4 and Comparative Examples 1 and 2
An electrophotographic toner was prepared in the same manner as in Example 1 except that it was blended according to the composition shown in Table 2. In the same manner as in Example 1, Tfb, T1 / 2, fixing start temperature, fixing strength, offset start temperature, and storage stability were evaluated. The evaluation methods for fixing start temperature, fixing strength, offset start temperature and storage stability are shown below. The results are shown in Table 3.

Footnotes in Table 2 Elf8: Elftex 8 (trade name of carbon black manufactured by Cabot Corporation in the United States)
550P: Biscol 550P [polypropylene wax manufactured by Sanyo Chemical Co., Ltd.]
E-84: Bontron E-84 [Salicylic acid metal complex manufactured by Orient Chemical Co., Ltd.]

Claims (8)

A resin composition for an electrophotographic toner comprising a reaction product (P) of a rosin (R) and an epoxy group-containing compound (E) and a binding resin (Q). The resin composition for an electrophotographic toner according to claim 1, wherein the rosin (R) is gum rosin and / or tall rosin. 2. The resin composition for an electrophotographic toner according to claim 1, wherein the epoxy group-containing compound (E) is a bisphenol type epoxy resin and / or a novolac type epoxy resin. The reaction product (P) comprises rosin (R) and an epoxy group-containing compound (E), carboxylic acid group (r) in rosin (R) and epoxy group (e) in epoxy group-containing compound (E). The resin composition for an electrophotographic toner according to claim 1, which is obtained by reacting such that the molar ratio [(r) / (e)] is 1.05 to 2. 2. The resin composition for an electrophotographic toner according to claim 1, wherein the binding resin (Q) is a polyester resin. The binder resin (Q) has a weight average molecular weight (Mw) of 5,000 to 25,000 as determined by gel permeation chromatography (GPC) in which tetrahydrofuran (THF) is soluble, and differential scanning calorimetry ( The polyester resin (q1) having a glass transition temperature (Tg) by DSC method of 50 to 90 ° C., Mw by GPC method of THF-soluble content is 25,000 to 500,000, and Tg by DSC method is 50 to 50 The resin composition for an electrophotographic toner according to claim 1, which is a mixture with a polyester resin (q2) at 90 ° C. 2. The resin composition for electrophotographic toner according to claim 1, wherein the mixing ratio [(P) / (Q)] of the reaction product (P) and the binder resin (Q) is 0.05 to 1 on a weight basis. . The flow start temperature (Tfb) by the Koka type flow tester is 80 to 110 ° C, and the plunger half drop temperature (T1 / 2) is 120 to 150 ° C. The resin composition for electrophotographic toner according to Item.