JP4402023B2 - Binder resin for toner for electrophotography - Google Patents

Description

  The present invention relates to a binder resin for an electrophotographic toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, an electrophotographic toner containing the binder resin, and The present invention relates to an image forming method using the electrophotographic toner.

  2. Description of the Related Art In recent years, toner image forming apparatuses have been strictly pursued for reduction in size and weight, speed, reliability, on-demand, and further energy saving.

  Therefore, in place of a heat roll type fixing device that has been widely used, a fixing device such as a belt nip method (see Patent Document 1), flash fixing (see Patent Document 2), oven fixing (see Patent Document 3), or the like is included. An image forming apparatus has been reported. In the belt nip method, since the nip width of the fixing nip portion can be widened, the thermal efficiency can be increased. In non-contact fixing, unimaged toner is not crushed by a heat roller or the like, so that a high-quality image can be formed.

On the other hand, as an attempt for a toner, a toner using a polyester having a high softening point and a monovalent long-chain aliphatic monoalcohol as a raw material has been reported as a toner having excellent offset resistance (patent) References 4 and 5).
JP-A-9-34291 JP-A-7-28355 JP 2003-162084 A JP-A-11-282203 JP-A-7-333891

  Compared with a heat roll fixing type fixing machine, a belt nip type fixing machine or a non-contact fixing type fixing machine has a small pressure applied to toner during fixing, and it is difficult to maintain a low temperature fixing property (fixing strength). .

  An object of the present invention is to provide a binder resin for an electrophotographic toner having good low-temperature fixability and offset resistance even when a pressing force during fixing is low, an electrophotographic toner containing the binder resin, and the An object of the present invention is to provide an image forming method using an electrophotographic toner.

The present invention
[1] Contains at least one monovalent aliphatic compound selected from the group consisting of a monovalent aliphatic carboxylic acid compound having 10 to 24 carbon atoms and a monovalent aliphatic alcohol having 10 to 24 carbon atoms. Electrophotographic for use in an image forming apparatus having a fixing machine having a softening point of 110 to 130 ° C. and having a fixing pressure of 600 N or less, obtained by condensation polymerization of the raw material monomer Binder resin for toner,
[2] An electrophotographic toner used for an image forming apparatus having a fixing machine containing the binder resin described in [1] and having a pressing force of 600 N or less during fixing, and [3] 2] An image forming method comprising a step of fixing the electrophotographic toner described in an image forming apparatus having a fixing machine having a pressing force of 600 N or less during fixing.

  The binder resin for electrophotographic toner of the present invention and the toner for electrophotography containing the binder resin are excellent in that they have good low-temperature fixability and offset resistance even when the pressure during fixing is low. It plays. Further, by using the toner of the present invention, it is possible to satisfactorily fix the toner even at a low temperature and a low pressure to form an image.

  The binder resin for an electrophotographic toner of the present invention is obtained by polycondensing a raw material monomer containing a monovalent aliphatic compound having a specific carbon number (hereinafter also referred to as a monovalent long-chain aliphatic compound). It is characterized in that it contains a polyester with a low softening point. When the applied pressure when fixing the toner is low, it is difficult for heat to be transferred to the toner, and it is difficult to improve the offset resistance by using a high molecular weight resin having a high softening point. However, in the present invention, since a monovalent long-chain aliphatic compound is used as a raw material monomer for polyester, a soft part (thermally weak part) is generated in the polyester, and the molecular weight is relatively higher than the softening point. High polyester is obtained. As a result, it is surprisingly assumed that both low-temperature fixability and offset resistance, which are usually considered to be contradictory properties, are achieved.

  In the present invention, the monovalent aliphatic compound is at least one selected from the group consisting of a monovalent aliphatic carboxylic acid compound having 10 to 24 carbon atoms and a monovalent aliphatic alcohol having 10 to 24 carbon atoms. However, a monovalent aliphatic carboxylic acid compound having 10 to 24 carbon atoms is preferred from the viewpoint of fixability, particularly offset resistance.

  Examples of the monovalent aliphatic carboxylic acid compound having 10 to 24 carbon atoms include decanoic acid, undecanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, behenic acid, anhydrides and alkyls of these acids (carbon number 1 -3) An ester etc. are mentioned.

  Examples of the monovalent aliphatic alcohol having 10 to 24 carbon atoms include 1-dodecanol, pentadecanol, hexadecanol, and octadecanol (stearyl alcohol).

  The monovalent aliphatic compound may have either a straight chain structure or a branched chain structure, but in order to further enhance the desired effect of the present invention, it has 10 to 24 carbon atoms, preferably 12 to 18 carbon atoms. It is preferable that it has the following linear structure.

  The content of the monovalent aliphatic compound is preferably from 0.1 to 20 mol%, more preferably from 1 to 15 mol%, still more preferably from 2 to 10 mol% in the raw material monomer.

  As the raw material monomer for the polyester contained in the binder resin for toner of the present invention, an alcohol component and a carboxylic acid component are used in addition to the monovalent aliphatic compound.

  Examples of the alcohol component include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, I):

(In the formula, RO is an alkylene oxide, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers indicating the average added mole number of alkylene oxide, and the sum of x and y is 1 to 16) (Preferably 1.5 to 5.0)
Divalent alcohols such as alkylene oxide adducts of bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, hydrogenated bisphenol A and the like A trihydric or higher polyhydric alcohol such as sorbitol, pentaerythritol, glycerin, trimethylolpropane and the like;

  In the present invention, it is preferable that a propylene oxide adduct of bisphenol A is used as the alcohol component. The content of the propylene oxide adduct of bisphenol A is preferably 30 mol% or more, more preferably 50 to 95 mol%, further preferably 70 to 90 mol% in the alcohol component, from the viewpoint of toner storage stability.

  Further, in the propylene oxide adduct of bisphenol A, the content of the propylene oxide adduct of bisphenol A added with 3 mol or more of propylene oxide is preferably 15 mol% or more, more preferably 20 to 85 mol%, and more preferably 40 to 70 More preferred is mol%.

  The average addition mole number of the propylene oxide adduct of bisphenol A is preferably 1.5 to 4.0, more preferably 2.1 to 4.0, further preferably 2.3 to 3.5, and further preferably 2.9 to 3.4. The average number of moles added here means the average number of moles of propylene oxide added to 1 mole of bisphenol A.

  On the other hand, in the carboxylic acid component, divalent carboxylic acid compounds include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutacone An aliphatic dicarboxylic acid such as succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms such as acid, succinic acid, adipic acid, dodecenyl succinic acid, octyl succinic acid; Examples include anhydrides and alkyl (C1-3) esters of these acids. Of these, aromatic dicarboxylic acid compounds are preferred from the viewpoint of chargeability, terephthalic acid and isophthalic acid are more preferred, and terephthalic acid is even more preferred.

  The content of the aromatic dicarboxylic acid compound is preferably 55 to 99 mol%, more preferably 70 to 90 mol% in the carboxylic acid component.

  Examples of the trivalent or higher polyvalent carboxylic acid compound include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid and acid anhydrides thereof, lower alkyl (C1-C3) ester etc. are mentioned.

  The content of the trivalent or higher polyvalent carboxylic acid compound is preferably 3 to 49 mol%, more preferably 10 to 45 mol%, still more preferably 20 to 40 mol% in the carboxylic acid component from the viewpoint of grindability. .

  The content of trivalent or higher raw material monomers (trivalent or higher polyhydric alcohols and / or trivalent or higher polyvalent carboxylic acid compounds) is preferably 1 to 25 mol%, preferably 3 to 23 mol% in all raw material monomers. Is more preferable, and 7 to 21 mol% is more preferable.

  The binder resin of the present invention is, for example, a polycondensation of a raw material monomer containing a monovalent long-chain aliphatic compound at a temperature of 180 to 250 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst. Can be manufactured.

  Further, the binder resin of the present invention includes a hybrid resin having the polyester and vinyl resin.

  Examples of the raw material monomer for the vinyl resin include styrene compounds such as styrene and α-methylstyrene; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl acetate; Vinyl esters such as vinyl propionate; alkyl (1-18) esters of (meth) acrylic acid, esters of ethylenic monocarboxylic acids such as dimethylaminoethyl (meth) acrylate; vinyl ethers such as vinyl methyl ether Vinylidene halides such as vinylidene chloride; N-vinyl compounds such as N-vinylpyrrolidone, and the like. The alkyl ester of styrene and / or (meth) acrylic acid is 50% by weight or more, preferably 80 to 100% by weight. % Content is desirable.

  In addition, when polymerizing the raw material monomer of the vinyl resin, a polymerization initiator, a crosslinking agent, or the like may be used as necessary.

  In the present invention, the weight ratio of polyester to vinyl resin, that is, the weight ratio of polyester raw material monomer to vinyl resin raw material monomer is preferably 50/50 to 95/5 since the continuous phase is preferably polyester. Is preferable, and 60/40 to 95/5 is more preferable.

  In the hybrid resin, it is preferable that the polyester and the vinyl resin are partially chemically bonded via both reactive monomers capable of reacting with both the polyester raw material monomer and the vinyl resin raw material monomer. Therefore, in the present invention, the polycondensation reaction for forming the polyester and the addition polymerization reaction for forming the vinyl resin are preferably performed in the presence of both reactive monomers, whereby the polyester and the vinyl resin are partially obtained. Thus, a resin in which the vinyl resin is more finely and uniformly dispersed in the polyester can be obtained.

  Both reactive monomers have at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an epoxy group, a primary amino group and a secondary amino group in the molecule, preferably a hydroxyl group and / or carboxyl. A monomer having a group, more preferably a carboxyl group and an ethylenically unsaturated bond is preferred. Specific examples of the both reactive monomers include, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid and the like, and these hydroxyalkyl (C1-3) esters may be used. In view of the above, acrylic acid, methacrylic acid and fumaric acid are preferable.

  In the present invention, among the two reactive monomers, a monomer having two or more functional groups (polycarboxylic acid or the like) and a derivative thereof are used as a raw material monomer for polyester, and a monomer having one functional group (monocarboxylic acid or the like) and its derivative Derivatives are treated as raw material monomers for vinyl resins. The amount of both reactive monomers used is 1 to 2 in the raw material monomer of polyester for monomers having 2 or more functional groups and derivatives thereof, and in the raw material monomer of vinyl resins for monomers having 1 functional group and derivatives thereof. 10 mol% is preferable and 4-8 mol% is more preferable.

  When producing a hybrid resin, it is preferable to perform the condensation polymerization reaction and the addition polymerization reaction in the same reaction vessel. In addition, the progress and completion of each polymerization reaction do not need to be simultaneous in time, and the reaction temperature and time may be appropriately selected according to each reaction mechanism to advance and complete the reaction. Specifically, for example, a raw material monomer for polyester, a raw material monomer for vinyl resin, an amphoteric compound, etc. are mixed, and first has a functional group capable of a condensation polymerization reaction mainly by addition polymerization reaction at 50 to 180 ° C. After obtaining a vinyl resin component and then raising the reaction temperature to 190 to 270 ° C., it is preferable to form a polyester component mainly by a condensation polymerization reaction.

  When producing a hybrid resin, from the viewpoint of the dispersibility of the release agent and the durability of the toner, a release agent may be added to the reaction system and added internally to the resin. The addition amount of the release agent is preferably 0.5 to 25 parts by weight, more preferably 1 to 20 parts by weight, and further preferably 3 to 10 parts by weight with respect to 100 parts by weight of the total amount of raw material monomers.

  The softening point of the polyester in the present invention is 110 to 130 ° C, preferably 115 to 119 ° C, more preferably 117 to 125 ° C, from the viewpoint of low-temperature fixability. The softening point can be appropriately adjusted depending on the reaction temperature, reaction time, and the like.

  Moreover, the glass transition point of polyester is 45-70 degreeC from a viewpoint of fixability and a preservability, Preferably it is 47-65 degreeC, More preferably, it is 50-60 degreeC.

  Furthermore, an electrophotographic toner containing the binder resin of the present invention is provided. Such a toner may contain a binder resin other than the binder resin of the present invention, but the content of the binder resin of the present invention is preferably 20% by weight or more in the total binder resin, 30 -80% by weight is preferable, and 40-60% by weight is more preferable.

  The toner of the present invention further uses a monovalent long-chain aliphatic compound as a raw material monomer, and in addition to the above-mentioned polyester at 110 to 130 ° C., the softening point of the polyester is preferably 10 ° C. or more, more preferably It preferably contains a binder resin that is 15 to 30 ° C. lower. An electrophotographic toner containing a binder resin using both binder resins exhibits particularly excellent low-temperature fixability while maintaining offset resistance when mounted on an image forming apparatus with a low fixing pressure. To do.

  The binder resin using a monovalent long-chain aliphatic compound as a raw material monomer and having a softening point lower than that of the polyester may be any of polyester, styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and the like. From the viewpoint of compatibility with the polyester, polyester is preferred. Such a polyester is also obtained using the same raw material monomer as the polyester, and the presence or absence of a monovalent long-chain aliphatic compound is not particularly limited.

  The toner of the present invention further includes a colorant, a release agent, a charge control agent, a magnetic powder, a fluidity improver, a conductivity modifier, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, and an aging agent. Additives such as an inhibitor and a cleaning property improver may be appropriately contained.

  As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow and the like can be used, and the toner of the present invention may be either a black toner or a color toner. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

The toner of the present invention may be a toner obtained by any conventionally known method such as a melt-kneading method, an emulsion transfer method, or a polymerization method, but from the viewpoint of productivity and dispersibility of the colorant, Pulverized toner by a kneading method is preferred. In the case of pulverized toner by melt kneading method, raw materials such as binder resin, colorant, charge control agent, etc. are uniformly mixed with a mixer such as a Henschel mixer, then a sealed kneader, a single or twin screw extruder, open It can be produced by melt-kneading with a roll-type kneader or the like, cooling, pulverizing and classifying. The volume median particle size (D ₅₀ ) of the toner is preferably 3 to 15 μm. In the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

  The electrophotographic toner of the present invention can be used as a one-component developing toner or a two-component developer mixed with a carrier, but the toner of the present invention has good dispersibility of the internal additive. Also, it can be suitably used as a magnetic toner containing a large amount of magnetic powder. The content of the magnetic powder is preferably 30% by weight or more, more preferably 35 to 60% by weight in the toner. The magnetic powder may be contained as a black colorant.

Magnetic powder includes ferromagnetic materials such as cobalt, iron and nickel, alloys of metals such as cobalt, iron, nickel, aluminum, lead, magnesium, zinc and manganese, Fe ₃ O ₄ , γ-Fe ₃ O ₄ , cobalt Examples thereof include metal oxides such as added iron oxide, various ferrites such as Mn—Zn ferrite and Ni—Zn ferrite, magnetite and hematite. Furthermore, those surfaces may be treated with a surface treatment agent such as a silane coupling agent or a titanate silane coupling agent, or may be polymer-coated.

  The toner for electrophotography of the present invention fixes toner using an image forming apparatus having a low total pressure during fixing, that is, an image forming apparatus having a fixing machine having a pressing force of 600 N or less, more preferably 400 N or less. Used in the image forming method. Examples of such a fixing machine having a low pressure applied to the toner at the time of fixing include a belt nip type fixing machine and a non-contact heat fixing type fixing machine such as oven fixing and flash fixing. Among these, the belt nip method takes a long time to melt the toner (nip width) and easily causes paper wrapping around the roller, but the monovalent long-chain aliphatic compound is excellent in releasability. In addition, wrapping around the roller can be prevented. Therefore, the toner of the present invention is suitably used for a belt nip type fixing machine.

  The image forming method of the present invention can form an image through a known process except that it has a feature in a fixing process for fixing a transferred toner image. Typical processes in the image forming method include a process of forming an electrostatic latent image on the surface of the photoreceptor (charging / exposure process), a developing process of developing the electrostatic latent image, and the developed toner image being transferred to paper or the like. There are a step of transferring to a material (transfer step), a step of removing toner remaining on a developing member such as a photosensitive drum (cleaning step), and the like.

[Softening point]
Using a flow tester (Shimadzu Corp., CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C / min, and a 1.96 MPa load was applied by a plunger, and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. . The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[Glass transition point]
Using a differential scanning calorimeter (DSC210, manufactured by Seiko Denshi Kogyo Co., Ltd.), the sample was heated to 100 ° C at a temperature increase rate of 10 ° C / min and allowed to cool to -10 ° C at a temperature decrease rate of 100 ° C / min for 3 minutes. Thereafter, the temperature is raised to 25 ° C. at a temperature rising rate of 60 ° C./min, held for 2 minutes, and measurement is started at a temperature rising rate of 10 ° C./min. The glass transition point is defined as the temperature at the intersection of the base line extension below the glass transition point and the tangent that indicates the maximum slope from the peak rising portion to the peak apex.

Resin production example 1
The raw material monomer shown in Table 1 and 4 g of dibutyltin oxide were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and reacted at 230 ° C. for 12 hours. Resins A to F were obtained by reacting at 8.3 kPa until a predetermined softening point was obtained.

  Tables 2 and 3 show the breakdown of the number of moles added in BPA-PO (propylene oxide adduct of bisphenol A) and BPA-EO (ethylene oxide adduct of bisphenol A) used in resins A to F. As for the breakdown of each alcohol, the weight ratio was determined from the peak area ratio of gas chromatography, and the molar ratio was determined by converting the weight ratio into the molecular weight.

Examples 1 to 4 and Comparative Examples 1 and 2 (Examples 3 and 4 are reference examples)
Using binder resin shown in Table 4, charge control agent "T-77" (Hodogaya Chemical Co., Ltd.) 0.5 parts by weight, release agent "Carnauba Wax C1" (Kato Yoko Co., Ltd.) 3 parts by weight and magnetic powder 67 parts by weight of “MTS106HD” (manufactured by Toda Kogyo Co., Ltd.) was mixed with a Henschel mixer, and melt kneaded using a co-rotating twin screw extruder having a total kneading part length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm. The roll rotation speed was 150 r / min. The heating temperature in the roll was 130 ° C., the feed rate of the mixture was 20 kg / h, and the average residence time was about 18 seconds.

The obtained kneaded product was rolled with a cooling roller, and then mechanically pulverized and classified to obtain a toner having a volume median particle size (D ₅₀ ) of 7 μm.

  To 100 parts by weight of the obtained toner, 1.0 part by weight of hydrophobic silica “R-972” (manufactured by Nippon Aerosil Co., Ltd.) and 1.0 part by weight of strontium titanate “TiSr” (manufactured by Fuji Titanium) were added. Mixed.

Test Example 1 [Offset resistance]
An unfixed image (2 cm × 12 cm) having a toner adhesion amount of 0.6 mg / cm ² was obtained by a belt nip fixing type copying machine “LaserJet 4200” (manufactured by Hewlett-Packard).

The fixing machine of the copier "AR-505" (manufactured by Sharp Corporation) has been improved so that it can be fixed offline and the applied pressure is 40 kgf (392 N) (fixing speed: 200 mm / sec) Then, the unfixed image was fixed while sequentially increasing from 100 ° C. to 240 ° C. by 10 ° C. During fixing, the presence or absence of occurrence of offset was visually observed, and the offset resistance was evaluated according to the following evaluation criteria. As the fixing paper, “CopyBond SF-70NA” (manufactured by Sharp Corporation, 75 g / m ² ) was used. The results are shown in Table 4.

〔Evaluation criteria〕
A: The non-offset region is 60 ° C or higher.
○: The non-offset region is 20 to 50 ° C.
X: The non-offset area is 10 ° C. or less.

Test example 2 [wrapping paper]
Except that the fixing speed of the fixing machine was changed to 50 mm / sec, the unfixed image was fixed and the winding of the paper on the roller was observed in the same manner as in Test Example 1. The results are shown in Table 4.

Test Example 3 [Low-temperature fixability]
An unfixed image (2 cm × 12 cm) having a toner adhesion amount of 0.6 mg / cm ² was obtained by a belt nip fixing type copying machine “LaserJet 4200” (manufactured by Hewlett-Packard).

  The fixing machine of the copier "AR-505" (manufactured by Sharp Corporation) has been improved so that it can be fixed offline and the applied pressure is 40 kgf (392 N) (fixing speed: 200 mm / sec) Then, the unfixed image was fixed while gradually increasing from 80 ° C. in increments of 10 ° C.

  “UNICEF cellophane” (Mitsubishi Pencil Co., Ltd., width: 18 mm, JISZ-1522) was attached to the fixed image, passed through a fixing roll set at 30 ° C., and then the tape was peeled off. The optical reflection density before and after the tape was peeled off was measured using a reflection densitometer “RD-915” (manufactured by Macbeth), and the ratio of both (after peeling / before sticking) first exceeded 90%. The roller temperature was defined as the minimum fixing temperature. The results are shown in Table 4.

〔Evaluation criteria〕
A: The minimum fixing temperature is 90 ° C. or lower.
○: The minimum fixing temperature is 100 to 110 ° C.
X: The minimum fixing temperature is 120 ° C. or higher.

  From the above results, the toners obtained in Examples 1 to 4 are excellent in both offset resistance and low-temperature fixability, and no wrapping occurs even when used in a belt nip type fixing machine. I understand. On the other hand, in Comparative Example 1 which does not contain a polyester using a monovalent long-chain aliphatic compound, low temperature fixing is achieved in Comparative Example 2 which does not contain a polyester having a desired softening point in terms of offset resistance. Each of the toners of the comparative examples is lacking in the properties, and the winding of the paper occurs in any of the toners of the comparative examples.

  The binder resin for an electrophotographic toner of the present invention is suitably used as a binder resin for a toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like. Is.

Claims (5)

Containing a polyester having a softening point of 110 to 130 ° C. obtained by condensation polymerization of a raw material monomer containing a monovalent aliphatic carboxylic acid compound having 10 to 24 carbon atoms and a propylene oxide adduct of bisphenol A a Do that electronic toner binder resin for propylene oxide adduct of the bisphenol a, the content of propylene oxide adduct of bisphenol a obtained by adding propylene oxide 3 mol or more in 40 to 85 mole% A binder resin for toner for electrophotography . The binder resin for an electrophotographic toner according to claim 1, wherein the content of the monovalent aliphatic carboxylic acid compound is 0.1 to 20 mol% in the raw material monomer. Comprising the claims 1 or 2 binder resin according, electronic toner.   The toner for electrophotography according to claim 3, further comprising a binder resin having a softening point lower by 10 ° C or more than polyester having a softening point of 110 to 130 ° C.   The toner for electrophotography according to claim 3 or 4, further comprising 30% by weight or more of magnetic powder in the toner.