JP4114068B2 - Toner for developing electrostatic image, method for producing the same, and image producing apparatus - Google Patents

Description

  The present invention relates to a toner for developing an electrostatic charge image that visualizes an electrostatic charge latent image formed in an electrophotographic method, an electrostatic printing method, an electrostatic recording method or the like, a method for producing the toner, and a toner image Relates to the device.

  Waxes added to conventional toner for developing electrostatic images have generally been used for a long time as an anti-offset agent for toner, but on the other hand, the heat resistance, durability, storage stability and fluidity of the toner are reduced. There is a problem that fusion is likely to occur. There are many types of waxes such as natural waxes such as animal and plant waxes, mineral waxes and petroleum waxes, synthetic waxes such as Fischer-Tropish wax and polyethylene waxes, and processed waxes processed from these raw materials. It is used properly according to the.

  Waxes are aggregates of relatively low molecules having a molecular weight distribution, and their characteristics greatly depend on the molecular weight distribution. In general, the effect of wax is effective in preventing low temperature offset and improving low temperature fixing by increasing low molecular weight components in addition to preventing high temperature offset. Recently, low melting point waxes have attracted attention from the viewpoint of low-temperature fixing.

  For example, in order to improve low-temperature fixability, offset resistance, and non-aggregation properties of toner, a vinyl system in which ethylene or propylene and α-olefin copolymer having a viscosity at 140 ° C. of 10,000 poise or less has a specific molecular weight distribution It is added to the copolymer (for example, refer to Patent Document 1).

  For the same purpose, paraffin wax having a peak (melting point) of absorption heat by a differential scanning calorimeter (DSC) of 75 to 85 ° C. (see, for example, Patent Document 2), natural having a melting point by DSC of 85 to 100 ° C. Gas-based Fischer-Tropish wax (see, for example, Patent Document 3, Patent Document 4, and Patent Document 5), polyethylene wax having a melting point of 85 to 110 ° C. by DSC (see, for example, Patent Document 6), and melting point of 50 ° C. A polyethylene wax having a melting point of DSC of 70 to 120 ° C. from which the following components have been removed by distillation or the like (see, for example, Patent Document 7), a polyethylene wax having a weight average molecular weight (Mw) of less than 1000 (for example, Patent Document 8) Is added to the toner.

  However, when a low melting point wax is added to the toner, the heat resistance, durability, storage stability, and fluidity of the toner are reduced, and fusion to a development carrier and a photoreceptor is likely to occur. For this reason, attempts have been made to thoroughly cut the low molecular weight components of existing waxes and sharpen the molecular weight distribution. That is, in the molecular weight distribution that can be measured by gel permeation chromatography (GPC), the molecular weight of the wax is such that the weight average molecular weight (Mw) / number average molecular weight (Mn) is 1.5 or less, preferably 1.45 or less. It is disclosed that the distribution is sharpened (see, for example, Patent Document 9).

  For the same purpose, an ethylene-based olefin polymer wax having a melt viscosity at 140 ° C. of 0.5 to 10 mPa · s and a penetration of 3.0 dmm or less is used (for example, see Patent Document 10). The use of Fischer-Tropish wax having an average molecular weight of 1000 or more is disclosed (for example, see Patent Document 11).

JP-A-5-313413 JP-A-7-287413 JP-A-8-314181 JP-A-9-179335 JP-A-9-319139 JP-A-6-324513 JP 7-36218 A JP-A-8-114942 JP-A-6-123994 JP-A-7-209909 JP-A-7-287418

    However, according to the study by the present inventors, in the conventional electrostatic charge image developing toner, when the molecular weight distribution of the low melting point wax is sharpened as described above, particularly in the case of the fine particle toner, the heat resistance and durability of the toner. Further, it is difficult to improve the fixing performance while maintaining the storage stability and fluidity, and the fixing performance is lowered when high-speed printing of 10 pages or more per minute is repeated. I couldn't.

  Therefore, the present invention examines the effects of wax molecular weight distribution, melt viscosity, crystallinity, DSC curve measured by a differential scanning calorimeter, etc. on various properties of the toner, and the optimum wax to be added to the toner and the addition method. The toner's heat resistance, durability, storage stability, and fluidity are good and the developer life is reduced due to the carrier spent by the toner. Reduced storage stability due to toner and development characteristics due to decreased fluidity of toner, less energy required for fixing, and reduced temperature and pressure of heat roller when heat roller fixing method is adopted It is possible to provide a toner for developing an electrostatic charge image that can be caused to occur and is less likely to cause an offset phenomenon, and to provide an image manufacturing apparatus using the toner. To.

In order to achieve the above object, the electrostatic image developing toner of the invention according to claim 1 is an electrostatic image developing toner having at least a fixing resin and a wax. A wax having a weight average molecular weight (Mw) / number average molecular weight (Mn) exceeding 140, a melt viscosity at 140 ° C. of less than 10 mPa · s and a crystallinity of less than 90%, B: 1.5 or less A wax having a weight average molecular weight (Mw) / number average molecular weight (Mn), a melt viscosity at 140 ° C. of less than 10 mPa · s, and a crystallinity of 90% or more, C: weight average of 1.5 or less It has a molecular weight (Mw) / number average molecular weight (Mn), is less than s melt viscosity · 10 mPa at 140 ° C., the wax crystallinity of less than 90% of the B mainly the said a B ,Also Primarily the B, said has free also reduce any wax mixture of C and B, DSC curve of the wax mixture, the maximum endothermic peak of endothermic peak during heating is at less than 110 ° C. The onset temperature attributed to the maximum endothermic peak exceeds 50 ° C, and the lowest onset temperature among the onset temperatures attributed to the endothermic peak is in the range of 30 ° C to 50 ° C. Further, the electrostatic image developing toner of the invention according to claim 2 uses a wire mesh with an inner diameter of 75 mm for the vibrating screen, the wire diameter of the wire mesh is 50 μm, the mesh opening is 75 μm, and 5 g of the electrostatic image developing toner is supplied to the vibrating screen. When the amount of electrostatic charge image developing toner dropped is measured by applying vibration for 1 minute at an amplitude of 0.35 mm and a frequency of 50 Hz, the amount of fall is 2.0 g / min or more.

  The electrostatic charge image developing toner having this characteristic makes the electrostatic charge latent image formed on the electrostatic charge image holding member visible using a two-component developer composed of toner and carrier, and records the exposed toner image. In the electrostatic charge image recording process in which the toner image transferred onto the medium and remaining on the electrostatic charge holding member is cleaned, and the toner image transferred onto the recording medium is fixed to obtain a recorded image, the fluidity is reduced due to the environment. And the low-temperature fixability associated therewith can be improved. Further, in the electrostatic charge image recording step, the fluidity is good and an image can be stably formed during high-speed printing.

Toner over the electrostatic image developing of the invention according to claim 3, said wax mixture, that you cool the toner material to room temperature after heat melt kneading were kneaded (about 20 ° C.) containing said fixing resin Features.

The electrostatic image developing toner chromatography is by cold release up to room temperature after kneading (about 20 ° C.), to promote the phase separation between the molecules of the fixing resin and the wax in the cooling process, moderate wax domains in the toner To increase the crystallinity of the wax, which is a crystalline molecule.

According to a fourth aspect of the present invention, an electrostatic image latent image formed on an electrostatic charge image holding member is visualized using a two-component developer composed of a toner and a carrier, and the visualized toner In the electrostatic charge image recording step of transferring an image onto a recording medium, cleaning the toner image remaining on the electrostatic charge image holding member, and fixing the toner image transferred onto the recording medium to obtain a recorded image. The toner for developing an electrostatic image according to claim 1 , 2 or 3 is used.

  In the image forming apparatus having this configuration, since the toner fixing performance, heat resistance, durability, storage stability, and fluidity are good, a stable image can be obtained during high-speed printing.

  According to a fifth aspect of the present invention, in addition to the structure of the fourth aspect of the invention, the means for fixing the toner image transferred onto the recording medium is a contact heating fixing means. And

In the image forming apparatus having this configuration, when the electrostatic image developing toner according to any one of claims 1 to 3 is used, the temperature and pressure of the heat roller can be reduced.

As described above, according to the toner for developing electrostatic image according to claim 1 and 2 , the maximum endothermic peak of the endothermic peak at the time of temperature rise in the DSC curve of the wax is less than 110 ° C., and the maximum endothermic peak. And the lowest onset temperature among the onset temperatures attributed to endothermic peaks is in the range of 30 ° C to 50 ° C. It is possible to prevent a decrease in fluidity due to the environment and a corresponding decrease in toner development characteristics, and to improve the environmental stability of the toner. Further, since the fall amount of the toner fall amount measurement using a vibrating sieve is 2.0 g / min or more, the fluidity is good and an image can be stably formed during high-speed printing.

According to toner over the electrostatic image developing of claim 3, since the cooled discharge to room temperature (about 20 ° C.) after the kneading, to promote phase separation between the molecules of the fixing resin and the wax in the cooling step , By forming appropriate wax domains in the toner and increasing the crystallinity of the wax, which is a crystalline molecule, to improve heat resistance, durability, storage stability, and fluidity contrary to toner fixing performance and fixing performance Can be made.

According to the image producing apparatus of the fourth aspect, since the electrostatic image developing toner according to the first , second or third aspect is used in the electrostatic image recording process, the fixing performance, heat resistance, durability, With a toner having good storage stability and fluidity, a stable image can be obtained during high-speed printing.

According to the image producing apparatus of the fifth aspect, since the means for fixing the toner image transferred onto the recording medium is a contact heating fixing means, the electrostatic charge image according to the first , second or third aspect. When developing toner is used, it is possible to reduce the temperature and pressure of the heat roller, and the effect of releasing the toner onto the fixing roll prevents offset and increases the fixing strength. .

  Hereinafter, a laser beam printer 1 which is an example of an image forming apparatus using the electrostatic charge developing toner (hereinafter referred to as toner) of the present invention in an electrostatic charge image recording process will be described with reference to FIG. FIG. 1 is a central sectional view of the laser beam printer 1.

  As shown in FIG. 1, the laser beam printer 1 includes a printing unit 3, a contact-type heat fixing device 13, a cassette 8, discharge units 16 and 17, and a paper transport mechanism in a cross-sectional view of the apparatus frame 2. A, a paper conveyance switching member 15, and a paper feeding path 20 for double-sided printing. The printing unit 3 includes a photosensitive drum 4, a charger 5, a laser 6, a developing device 7, a transfer device 11, a cleaning device 18, and a toner replenishing device 19. The paper transport mechanism A includes a paper feed roller mechanism 10 and a transport belt 12. The contact-type heat fixing device 13 includes a fixing roller 14 including a pair of heat rollers 14a and a backup roller 14b.

  The printing unit 3 can be pulled out from the apparatus frame 2. The photosensitive drum 4 on which a toner image is recorded and formed by a known electrophotographic process is supported by a support shaft so as to rotate at a constant speed in the direction of arrow a.

  A charger 5 for uniformly charging the surface of the photosensitive drum 4 is disposed so as to face the surface of the photosensitive drum 4. The laser beam 6 that exposes the uniformly charged surface of the photosensitive drum 4 forms an electrostatic latent image on the surface of the photosensitive drum 4 in accordance with a print information signal supplied from the information processing apparatus.

  The developing device 7 is disposed so as to face the surface of the photosensitive drum 4 on which the electrostatic charge latent image is formed. The developing device 7 has a function of developing the toner image by attaching the above-described toner to the surface of the photosensitive drum 4 with the electrostatic force of the electrostatic charge latent image. Further, when the toner in the developing device 7 is insufficient, the toner is replenished from the toner replenishing device 19 as necessary.

  The cassette 8 accommodates the sheet-like paper 9 for transferring and fixing the toner image and performing image printing in a stacked state. The paper feed roller mechanism 10 takes in the paper 9 from the cassette 8 and sends it out toward the photosensitive drum 4.

  The paper 9 sent out from the paper supply roller mechanism 10 comes into contact with the surface of the photosensitive drum 4 so as to transfer the toner image onto the surface. The transfer unit 11 applies an electric charge having a polarity opposite to that of the toner image to the back surface of the paper 9 in contact with the surface of the photosensitive drum 4 to generate an electrostatic force, and the toner image formed on the surface of the photosensitive drum 4 is transferred to the paper. 9 is transferred. The cleaning device 18 removes foreign matters such as toner and paper dust remaining on the surface of the photosensitive drum 4 after passing through the transfer device 11 from the surface of the photosensitive drum 4.

  The conveyance belt 12 sends the paper 9 on which the toner image is transferred to the contact-type heat fixing device 13. A pair of fixing rollers 14 including a heat roller 14 a and a backup roller 14 b that are in pressure contact with each other heats and presses the paper 9 to fix the toner image on the surface of the paper 9.

  The paper 9 sent out from the contact-type heat fixing device 13 is discharged to the discharge unit 16 or the discharge unit 17 according to the position of the paper transport path switching member 15, or is once sent to the discharge unit 17 side, and is predetermined. At this time, the printing paper that has been transported to the double-sided printing paper feed path 20 side and has been printed on the front side is supplied again to the printing unit 3, and printing is performed on the back side of the paper 9.

  In FIG. 1, a laser beam printer equipped with a developing device equipped with one developing roller is illustrated, but a developing device equipped with two or more developing rollers may be used. It may be a laser beam printer equipped with a center feed type developing device provided with a developing roller that rotates in the same direction as the photosensitive drum and a developing roller that rotates in the opposite direction to the photosensitive drum.

  Next, the toner held in the toner replenishing device 19 and the manufacturing method thereof will be described.

  The basic material of the toner for developing an electrostatic image is composed of a fixing resin, a wax, a charge control agent, a pigment or dye as a colorant, magnetic powder, and, if necessary, other waxes and additives.

  Mix these materials thoroughly using a mixer such as a Henschel mixer or super mixer, and then melt and knead them using a hot melt kneader such as a heating roll, kneader or extruder to thoroughly mix the materials, and then remove them to room temperature. After cooling, solidification and fine pulverization and classification are performed to obtain a toner having an average particle size of 5 to 10 μm. Further, if necessary, a desired additive can be adhered and mixed on the surface of the toner by a mixer such as a Henschel mixer, and a toner to which the additive is externally added can be obtained.

Examples of the fixing resin used in the toner of the present invention include the following resins.
Styrene and its substituted homopolymers such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene -Acrylic acid ester copolymer, Styrene-methacrylic acid ester copolymer, Styrene-α-Chloromethyl methacrylate copolymer, Styrene-acrylonitrile copolymer, Styrene-vinyl methyl ether copolymer, Styrene-vinyl ethyl ether Styrene copolymers such as copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; and polyvinyl chloride, phenol Resin, natural modified phenolic resin, natural resin modified male Examples include inic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, chroman-indene resin, and petroleum resin. However, it is preferably styrene to a (meth) acrylic copolymer or a polyester resin. Further, a low hygroscopic resin obtained by graft copolymerization of styrene-acryl with the above-described polyester resin can also be used. The styrene- (meth) acrylic copolymer or polyester resin may be partially crosslinked or a mixed resin.

  Examples of the positive charge control agent for toner include modified products of nigrosine and its fatty acids; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonic acid and tetrabutylammonium tetrafluoroborate, and analogs thereof Onium salts such as phosphonium salts and these lake pigments, triphenylmethane dyes and these lake pigments, metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, Diorganotin borates such as dioctyl tin borate and dicyclohexyl tin borate; these can be used alone or in combination of two or more. Among these, charge control agents such as nigrosine, quaternary ammonium salts, and triphenylmethane dyes are particularly preferably used.

  As the negative charge control agent of the toner, an organic metal complex and a chelate compound are effective, and there are a monoazo metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid type metal complex. Others include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

  When these charge control agents are internally added to the toner, it is preferable to add 0.1 to 10 wt% with respect to the fixing resin. Further, the charge amount of the toner can be controlled to a desired value by blending (internal addition) or mixing (external addition) a charge control agent with the toner particles.

The colorant includes any suitable pigment or dye.
Examples of the pigment include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary and sufficient to maintain the optical density of the fixed image, and is preferably added in an amount of 0.2 to 15 wt% with respect to the resin.
Examples of the dye include azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, and these are added in an amount of 0.2 to 15 wt% with respect to the resin.

  The toner of the present invention is usually used as a two-component developer composed of a toner and a carrier. However, the toner further contains a magnetic material, and is also used as a one-component developer as a magnetic toner. In this case, the magnetic material can also serve as a colorant.

Magnetic materials include iron oxides such as magnetite, hematite and ferrite, and / or metals such as iron, cobalt and nickel, or aluminium, cobalt, copper, lead, magnesium, tin, zinc, antimony, calcium of these metals, Examples include alloys with metals such as manganese, selenium, titanium, tungsten, vanadium and mixtures thereof.
These magnetic materials preferably have an average particle size of 2 μm or less, preferably about 0.1 to 0.5 μm, and the amount contained in the toner is preferably 30 to 70 wt% with respect to the fixing resin.

  As the additive, for example, a silica powder, a Teflon resin powder, a zinc stearate powder, a lubricant powder such as a polyvinylidene fluoride powder, among them, polyvinylidene fluoride is preferable. Alternatively, a polishing agent such as cerium oxide powder, silicon carbide powder, and strontium titanate powder, among which strontium titanate is preferable. Alternatively, fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder, and particularly hydrophobic ones are preferred. A small amount of an anti-aggregating agent or a conductivity-imparting agent such as carbon black powder, zinc oxide powder, antimony oxide powder or tin oxide powder, and white and black fine particles having opposite polarity can also be used as a developability improver.

In the present invention, fine silica powder is used as an additive. The silica fine powder preferably has a specific surface area of 10 m ² / g or more by nitrogen adsorption measured by the BET method, and is externally added in the range of 0.01 to 5 wt% with respect to the toner. Further, if necessary, the silica fine powder is hydrophobized with various treating agents such as organosilicon compounds, or various treating agents, or the chargeability is controlled. By adding silica fine powder externally, developability, fluidity, charging stability, and durability can be improved.

The toner of the present invention is used by mixing with a carrier when used as a two-component developer. In this case, the mixing ratio between the toner and the carrier is preferably 2 to 10 wt% as the toner concentration.
Also, known carriers can be used as the carrier, for example, iron powder, ferrite, magnetite, glass beads and those whose surfaces are coated with fluorine resin, vinyl resin, silicone resin or the like.

In the present invention, as wax,
A: a wax having a weight average molecular weight (Mw) / number average molecular weight (Mn) exceeding 1.5, a melt viscosity at 140 ° C. of less than 10 mPa · s, and a crystallinity of less than 90%;
B: a wax having a weight average molecular weight (Mw) / number average molecular weight (Mn) of 1.5 or less, a melt viscosity at 140 ° C. of less than 10 mPa · s, and a crystallinity of 90% or more;
C: a wax having a weight average molecular weight (Mw) / number average molecular weight (Mn) of 1.5 or less, a melt viscosity at 140 ° C. of less than 10 mPa · s, and a crystallinity of less than 90%;
A wax containing at least one of the following is used.

  FIG. 2 is a graph showing the relationship between the wax viscosity at 140 ° C. and the toner fixing strength (tape peel strength%). The toner fixing strength is the ratio of the remaining amount of toner image after peeling the tape to the amount of toner image before sticking the tape when the toner image is fixed on the paper and then the tape is stuck on the toner image. Experiments were conducted on four types of waxes (O, P, Q, R), and the wax (R) had a higher viscosity and lower toner fixing strength than the three types of waxes (O, P, Q). It was. The straight line X is a linear approximation curve for the results of four types of waxes (O, P, Q, R). In practice, the toner needs to have a fixing strength of 75% or more, and the toner fixing strength of 75% or more on the straight line X is less than 10 mPa · s. Therefore, the viscosity of the wax at 140 ° C. is 10 mPa · s. It is necessary to be less than.

  In such a low-viscosity wax, the molecular weight distribution of the wax and the crystallinity have a certain degree of correlation. That is, the crystallinity tends to decrease as the molecular weight distribution of the wax increases, and the crystallinity tends to increase as the molecular weight distribution of the wax decreases.

  The former wax is rich in the effect of improving the fixing performance of the toner, but has the disadvantage of poor durability. The latter wax is rich in the effect of improving the durability of the toner, but has the disadvantage of poor fixing performance. Wax A belongs to the former and wax B belongs to the latter. In addition, there is a wax which does not belong to these and has a low crystallinity despite a low molecular weight distribution, which improves the fixing performance of the toner, but has the disadvantage of lowering the durability. The wax C of the present invention belongs to this.

  These waxes are used alone or in appropriate combination to improve various properties of the toner. The wax used in the present invention has a low viscosity and a melt viscosity at 140 ° C. of less than 10 mPa · s. When such a low-viscosity wax is added to the toner to improve the fixing performance, it is necessary to control the dispersibility of the wax in the toner, that is, the formation of wax domains.

To control the formation of the wax domain, when adding wax to the fixing resin is subjected to ordinary hot melt kneading, after obtaining a kneaded product cooled discharge to room temperature (about 20 ° C.), resulting solidified The product is pulverized and classified to obtain a toner. By performing the cold discharge of such kneaded material, phase separated between the molecules of the fixing resin and the wax is promoted during cooling, can form a suitable wax domains in the toner, the wax is a crystalline molecules By increasing the crystallinity, not only the toner fixing performance, but also the heat resistance, durability, storage stability, and fluidity of the opposite toner can be improved. In particular, the fluidity is significantly improved as compared with the case where the hot melt kneaded product is rapidly cooled.

  The added amount of wax is preferably 0.5 to 20 wt% with respect to the fixing resin in the total amount of wax. If it is less than 0.5 wt%, the effect of improving the fixing performance of the toner is reduced, and if it exceeds 20 wt%, the durability of the toner is lowered and high temperature offset is likely to occur.

  Next, DSC measurement for measuring the thermal characteristics of the wax and the toner of the present invention will be described. In the DSC measurement, the heat exchange of the wax is measured and the behavior thereof is observed. Therefore, it is preferable to measure with an ultrasensitive heat flux type differential scanning calorimeter from the measurement principle. For example, TA Instruments 2910 can be used. As measurement conditions, about 5 mg of wax was weighed and placed on the DSC, 50 ml of nitrogen gas was blown in one minute, the temperature was raised from 0 ° C to 220 ° C at a rate of 10 ° C per minute, The temperature is lowered from 220 ° C. to 0 ° C. at a rate of 10 ° C. per minute and the previous history is taken, and then the temperature is raised again at a rate of 10 ° C. per minute.

  When the peak temperature corresponding to the maximum value of the endothermic peak of wax (maximum endothermic peak), the onset temperature attributed to it, and a plurality of endothermic peaks are observed from the DSC absorption calorific value curve shown in FIG. The lowest onset temperature among the onset temperatures belonging to each endothermic peak is obtained. The onset temperature is defined as the temperature at the intersection of the tangent line and the baseline by drawing the tangent line of the curve at the point where the differential value of the endothermic peak curve is the smallest.

  On the other hand, the glass transition point (Tg) of the toner is obtained by measuring the absorption heat quantity curve of the toner by setting the heating end temperature of the toner to 160 ° C. in the above DSC measurement, and showing the absorption heat quantity curve attributed to the fixing resin. The glass transition point (Tg) can be determined from the shoulder shown in FIG. Further, the melting point (Tmp) of the toner can be obtained from the peak temperature of the maximum endothermic peak shown in FIG. 4 of the absorption heat quantity curve attributed to the wax in the same DSC measurement.

  The influence of the DSC curve characteristics of the wax on the toner is great, and the low end fixability of the toner can be improved by setting the maximum endothermic peak of the endothermic peak when the DSC temperature rises to less than 110 ° C. On the other hand, when the onset temperature attributed to the maximum endothermic peak is set to a temperature exceeding 50 ° C., it is possible to prevent a decrease in fluidity due to the environment of the toner and a decrease in the development characteristics of the toner associated therewith. Furthermore, by setting the lowest onset temperature among the onset temperatures belonging to each endothermic peak to be in the range of 30 ° C. to 50 ° C., the low temperature fixability of the toner can be improved.

  In addition, the toner is mixed with a carrier, the prepared developer is supplied to a laser beam printer, and the change in image quality due to the environment is evaluated. At that time, the mixing ratio of the toner and the carrier, that is, the so-called toner density changes depending on the environment, which causes deterioration of image quality. This is because the fluidity of the toner changes depending on the environment, and the fluidity of the toner decreases particularly at high temperature and high humidity (32 ° C., 80% RH). The density control device determines that the toner is insufficient, replenishes the toner excessively, and the image quality deteriorates due to the excessive development amount.

  Therefore, in order to obtain the environmental stability of the toner, the correlation between the change in the heat absorption characteristics of the wax and the fluidity of the toner and the deterioration of the image quality was examined. As a result, there is a correlation between the endothermic characteristics of the wax and the fluidity environment of the toner, mainly changes due to temperature, and the peak temperature of the maximum endothermic peak of the heat absorption curve at the time of temperature rise in the DSC curve of the wax is less than 110 ° C. If the onset temperature attributed to the maximum endothermic peak exceeds 50 ° C. and the onset temperature attributed to each endothermic peak is within the range of 30 ° C. to 50 ° C., the toner flow It has been found that the development characteristics can be stabilized by suppressing the change due to the environment, mainly temperature.

  The fluidity of the toner can be measured with a powder property measuring apparatus (Powder Tester PT-R type manufactured by Hosokawa Micron Corporation) using a vibrating sieve. That is, the toner is supplied to a vibrating screen of a powder tester, the amount of toner that falls for a certain time under a certain vibration condition is measured, and the fluidity of the toner is evaluated from the magnitude of this amount. In this embodiment, a stainless steel wire mesh with an inner diameter of 75 mm is used for the vibration sieve, the wire diameter of the wire mesh is 50 μm, the mesh opening is 75 μm, 5 g of toner is supplied to the vibration sieve, and the amplitude is 0.35 mm and the frequency is 50 Hz. The amount of toner falling is measured by applying vibration for minutes.

  FIG. 5 is a graph showing the relationship between the toner fall amount and the charge amount after 10 seconds of stirring of the developer. The circles in the figure are the results obtained from experiments by the inventors. From this result, it can be seen that the charge amount after 10 seconds of stirring with the developer increases as the toner fall amount increases. A straight line Y in the figure is a linear approximation curve for the experimental result. In practice, it is necessary to obtain a charge amount of 1 μC / g or more when the stirring time of the toner and the carrier is about 10 seconds. It can be seen from FIG. 5 that a toner drop amount of 2.0 g / min or more is necessary to obtain a charge amount of 1 μC / g or more. Therefore, if the falling amount is 2.0 g / min or more, it can be determined that the toner has good fluidity.

  The change in fluidity due to the temperature of the toner was determined by measuring 5% of the toner in a 50 ml wide-mouth plastic bottle, storing it in a thermostatic chamber set to the test temperature for 1 hour, and measuring the amount of fall in the same manner as above. Changes in fluidity with temperature can be measured. In this embodiment, the temperature of the fluidity was measured by changing the atmospheric temperature of the thermostatic chamber in which the toner is stored in the range of room temperature (about 20 ° C.) to 50 ° C. The change in fluidity within this temperature range was measured. In particular, since there is little change from 45 ° C. to 50 ° C., it is considered that deterioration in image quality at high temperature and high humidity (32 ° C., 80% RH) is reduced.

  This is because, in an environmental test of a printer, the temperature of a developing machine that conveys and supplies toner may be 45 ° C. or higher in an environment of high temperature and high humidity (32 ° C., 80% RH). The wax that has become apparently softened due to endotherm reduces the fluidity of the toner, and the same phenomenon appears for the toner stored in the thermostatic chamber as a drop in the drop in temperature change from 45 ° C to 50 ° C. . It is considered that the toner of the present invention having a small drop amount can achieve development stability with respect to the environment.

  Further, regarding the melt physical properties of the toner obtained by using the fixing resin and the wax of the present invention, the melting start temperature (Tfb) of the toner and the absorption heat amount curve at the time of temperature rise in the toner DSC curve are attributed to the wax. If the melting point (Tmp) corresponding to the maximum endothermic peak is Tmp <Tfb <110 ° C, the wax melts before the toner starts melting in the fixing process. The mold effect is enhanced to prevent offset and the fixing strength is increased. Further, the storage stability of the toner is ensured by setting the glass transition point (Tg) of the toner to a temperature exceeding 50 ° C.

  Accordingly, good fixing performance, heat resistance, durability, storage stability, and fluidity can be imparted to the toner. As a result, although the fixing performance of the toner is good, a decrease in the developer life due to the carrier spent by the toner and a decrease in the photoreceptor life due to the photoreceptor filming due to the toner are less likely to occur, and the stable electrostatic toner An image forming apparatus can be provided.

The melting start temperature (Tfb) of the toner is determined by the temperature rising method using the constant load extrusion capillary rheometer (Flow Tester CFT-500C, manufactured by Shimadzu Corporation) by the temperature rising method based on the piston stroke flow process shown in FIG. Is measured as Tfb. At this time, the measurement conditions of the flow tester, a load 20 kgf / cm ^2, die diameter 1 mm, die length 10 mm, and heating rate 6 ° C. / min.

  Next, a method for measuring the molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)), crystallinity, and melt viscosity representing the characteristics of the wax in the present invention will be described.

Molecular weight distribution is measured by gel permeation chromatography (GPC) at high temperature under the following conditions.
(GPC measurement conditions)
Equipment: ALC / GPC 150-C plus (Waters)
Separation column: GMH ₆ -HT30cm × 2, GMH ₆ -HTL30cm × 2 (Tosoh Corporation)
Column temperature: 140 ° C
Mobile phase: o-dichlorobenzene detector: differential refractometer flow rate: 1.0 ml / min
Sample concentration: 0.2wt%
Injection volume: 200 μl
Measured under the above conditions, the molecular weight of the sample is calculated by using a molecular weight calibration curve created with a monodisperse polystyrene standard sample and converting it using a conversion formula derived from the Mark-Houwink-Sakurada formula or the viscosity formula .

The molecular weight distribution of the fixing resin is measured by GPC under the following conditions.
(GPC measurement conditions)
Equipment: HLC-8120GPC (manufactured by Tosoh Corporation)
Separation column: TSKgel Super HM-H / H4000 / H3000 / H2000
Column size: 6.0mm I.D. × 150mm
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Pressure: 13.6MPa
Detector: Differential refractometer Flow rate: 0.6ml / min
Sample concentration: 3g / l THF
Injection volume: 20μl
Measurement is performed under the above conditions, and the molecular weight of the entire resin is calculated by using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample in calculating the molecular weight of the sample.

The melt viscosity is measured at 140 ° C. using a Brookfield type or E type viscometer. Further, the crystallinity of the wax is measured by the X-ray diffraction method under the following conditions.
X-ray: Cu-Kα ray (single color with graphite monochromator)
Wavelength λ = 1.5406mm
Output 40kV, 40mA
Optical system: reflection method, slit DS, SS = 1 °, RS = 0.3mm
Measuring range: 2θ = 10 ° ~ 35 °
Step interval: 0.02 °
Scanning speed: 2θ / θ continuous scan 1.00 ° / min Measured under the above conditions, the X-ray diffraction profile of the sample is separated into three crystal peaks and amorphous scattering. calculate.
Crystallinity (%) = Ic / (Ic + Ia) × 100
Ic: Sum of each crystal peak area
Ia: Sum of each crystal peak area + amorphous scattering area

The first embodiment of the present invention will be described below.
85 wt% of styrene-acrylic copolymer resin having a weight average molecular weight of about 230,000 consisting of 90 parts by weight of styrene and 10 parts by weight of n-butyl acrylate, chromium-containing dye (trade name: Bontron S- 34) Toner raw material composed of 1 wt%, carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Corporation) 10 wt%, wax B-1 2.8 wt%, wax A-1 1.2 wt% is preliminarily stored in a super mixer. After mixing by hot melt kneading with a twin-screw kneader, the mixture is allowed to cool to room temperature (about 20 ° C.) to obtain a solidified product, pulverized with a jet mill, and then classified with a dry air classifier to have an average particle size of about 9 μm. Obtained particles. Further, 0.8 wt% of hydrophobic silica (trade name: Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) was added to the particles, and the mixture was stirred with a Henschel mixer to adhere the hydrophobic silica to the surfaces of the particles. A toner was obtained.

  Wax B-1 is a polyethylene wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.20, a melt viscosity at 140 ° C. of 6.0 mPa · s, and a crystallinity of 93%. Wax A-1 is a mixture of paraffin wax and polyolefin wax, the weight average molecular weight / number average molecular weight (Mw / Mn) is 5.75, the melt viscosity at 140 ° C. is 4.3 mPa · s, and the crystallinity is 81%.

  The mixture of wax B-1 and wax A-1 (B-1 / A-1 = 7/3 weight) has a maximum endothermic peak at 61 ° C. in the DSC curve, and the onset temperature attributed to it is 61 ° C. 53 ° C. The other endothermic peaks are at 48 ° C. and 89 ° C., and the lowest onset temperature among the endothermic peaks is 37 ° C.

  The melting start temperature (Tfb) of the toner is 101 ° C., and in the toner DSC curve, the melting point (Tmp) corresponding to the maximum endothermic peak attributed to the wax in the absorption heat quantity curve at the time of temperature rise is 91 ° C., and the glass transition point of the toner. (Tg) was 51 ° C. Further, the flowability of the toner at room temperature (about 20 ° C.) is a drop amount of 3.24 g / min, and even if the storage temperature is changed from room temperature (about 20 ° C.) to 50 ° C., the toner fluidity is lowered. There were few.

  The toner is applied to an electrophotographic laser beam printer using OPC as a photoconductor. The charging potential of the OPC is −650 V, the residual potential is −50 V, the developing bias potential is −400 V, and the developing portion contrast potential is 350 V. Images were produced at a printing speed (printing process speed 26.7 cm / sec).

In the developing machine, a magnetite carrier (electric resistance: 4.1 × 10 ⁸ Ω · cm) coated with a conductive agent-containing silicone resin and having a weight average particle diameter of 100 μm is used as the carrier, and the toner concentration is 3.0 wt%. A developer is prepared, and the developing gap (distance between the photosensitive member and the developing roll sleeve) is set to 0.8 mm by the magnetic brush developing method, the photosensitive member and the developing roll are moved in the same direction, and the peripheral speed ratio between the two (developing roll) / Photosensitive member) was set to about 3, and an image was produced by reversal development.

  The fixing machine is a thin roll of aluminum cored bar covered with a fluororesin (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer: PFA) tube (thickness 40 μm) and a heater lamp installed in the center. A silicone rubber layer (thickness 7 mm) with a rubber hardness of about 30 degrees is installed on an aluminum core, and the outermost layer is covered with a PFA tube as a backup roll. Fixing conditions are a process speed of 26.7 cm / sec. The outer diameter of the hot roll and the backup roll was 60 mm, the pressing load was 50 kgf, the width of the contact area (nip) between them was about 7 mm, and the control temperature of the hot roll was 175 ° C. In addition, a Nomex paper take-up type cleaning machine impregnated with silicone oil was installed in the heat roll.

  The storage stability of the toner was evaluated by visual observation of the degree of aggregation of the toner by placing the toner in a metal petri dish and leaving it at 50 ° C. for 24 hours in a desiccator whose humidity was controlled at 65% RH. As a result, the toner did not cause noticeable aggregation and the storage stability was good. Also, when applied to the above laser beam printer and performing continuous printing, good fixing performance is obtained, and even if continuous printing of 300,000 pages is repeated, a decrease in developer life due to carrier spent by toner, and It was possible to obtain a stable image without deteriorating the life of the photoreceptor due to the filming of the photoreceptor with toner. Furthermore, even when continuous printing was performed at a high temperature and high humidity (32 ° C., 80% RH), an abnormal change in toner density did not occur, and a stable image could be obtained.

The second embodiment of the present invention will be described below.
85 wt% of styrene-acrylic copolymer resin having a weight average molecular weight of about 230,000 consisting of 90 parts by weight of styrene and 10 parts by weight of n-butyl acrylate, chromium-containing dye (trade name: Bontron S- 34) Toner raw material comprising 1 wt%, carbon black (product name: MA-100, manufactured by Mitsubishi Chemical Corporation) 10 wt%, wax B-1 3.0 wt%, wax C-1 1.0 wt% is preliminarily stored in a super mixer. After mixing by hot melt kneading with a twin-screw kneader, the mixture is allowed to cool to room temperature (about 20 ° C.) to obtain a solidified product, pulverized with a jet mill, and then classified with a dry air classifier to have an average particle size of about 9 μm. Obtained particles. Further, 0.8 wt% of hydrophobic silica (trade name: Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) was added to the particles, and the mixture was stirred with a Henschel mixer to adhere the hydrophobic silica to the surfaces of the particles. A toner was obtained.

  Wax B-1 is a polyethylene wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.20, a melt viscosity at 140 ° C. of 6.0 mPa · s, and a crystallinity of 93%. Wax C-1 is a paraffin wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.07, a melt viscosity of 2.4 mPa · s at 140 ° C., and a crystallinity of 86%.

  The mixture of wax B-1 and wax C-1 (B-1 / C-1 = 3/1 weight ratio) has a maximum endothermic peak at 63 ° C. in the DSC curve, and the onset temperature attributed to it. Is 56 ° C. The other endothermic peaks are at 51 ° C. and 89 ° C., and the lowest onset temperature among the onset temperatures attributed to each endothermic peak is 42 ° C.

The melting start temperature (Tfb) of the toner is 102 ° C., and the melting point (Tmp) corresponding to the maximum endothermic peak attributed to the wax in the absorption heat quantity curve at the time of temperature rise is 93 ° C. in the toner DSC curve. (Tg) was 52 ° C. Further, the fluidity of the toner at room temperature (about 20 ° C.) is a drop amount of 3.90 g / min, and even if the storage temperature is changed from room temperature (about 20 ° C.) to 50 ° C., the toner fluidity is lowered. There were few.
As a result of evaluating the toner by the same method as in the first embodiment, good results were obtained as in the first embodiment.

The third embodiment of the present invention will be described below.
85 wt% of styrene-acrylic copolymer resin having a weight average molecular weight of about 230,000 consisting of 90 parts by weight of styrene and 10 parts by weight of n-butyl acrylate, chromium-containing dye (trade name: Bontron S- 34) Preliminary toner material with a super mixer comprising 1 wt%, carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Corporation) 10 wt%, wax B-1 3.0 wt%, and wax C-2 1.0 wt% After mixing by hot melt kneading with a twin-screw kneader, the mixture is allowed to cool to room temperature (about 20 ° C.) to obtain a solidified product, pulverized with a jet mill, and then classified with a dry air classifier to have an average particle size of about 9 μm. Obtained particles. Further, 0.8 wt% of hydrophobic silica (trade name: Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) was added to the particles, and the mixture was stirred with a Henschel mixer to adhere the hydrophobic silica to the surfaces of the particles. A toner was obtained.

  Wax B-1 is a polyethylene wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.20, a melt viscosity at 140 ° C. of 6.0 mPa · s, and a crystallinity of 93%. Wax C-2 is a paraffin wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.06, a melt viscosity at 140 ° C. of 2.5 mPa · s, and a crystallinity of 89%.

  The mixture of wax B-1 and wax C-2 (B-1 / C-2 = 3/1 weight ratio) has a maximum endothermic peak at 68 ° C. in the DSC curve, and the onset temperature attributed to it. Is 60 ° C. The other endothermic peaks are at 58 ° C. and 90 ° C., and the lowest onset temperature among the onset temperatures attributed to each endothermic peak is 49 ° C.

The melting start temperature (Tfb) of the toner is 102 ° C., and in the DSC curve of the toner, the melting point (Tmp) corresponding to the maximum endothermic peak attributed to the wax in the absorption heat quantity curve at the time of temperature rise is 93 ° C., and the glass transition of the toner The point (Tg) was 53 ° C. Further, the fluidity of the toner at room temperature (about 20 ° C.) is a drop amount of 2.72 g / min, and even if the storage temperature is changed from room temperature (about 20 ° C.) to 50 ° C., the toner fluidity is lowered. There were few.
As a result of evaluating the toner by the same method as in the first embodiment, a good result was obtained as in the first embodiment.

Below, the 1st comparative example of this invention is demonstrated.
The first embodiment is the same as the first embodiment except that the toner raw material is premixed by a super mixer, and is not cooled to room temperature (about 20 ° C.) after hot melt kneading by a twin-screw kneader, but rapidly cooled. Similarly, a toner was prepared. As a result, the flowability of the toner at room temperature (about 20 ° C.) drops to 1.30 g / min, the development characteristics deteriorate, the fixing performance also deteriorates, and a stable image cannot be obtained. It was.

A second comparative example of the present invention will be described.
The second embodiment is the same as the second embodiment except that the toner raw material is premixed with a supermixer, is not melted to room temperature (about 20 ° C.) after hot melt kneading with a twin-screw kneader, and is rapidly cooled. Similarly, a toner was prepared. As a result, the flowability of the toner at room temperature (about 20 ° C.) drops to 1.65 g / min, the development characteristics deteriorate, the fixing performance also deteriorates, and a stable image cannot be obtained. It was.

A third comparative example of the present invention will be described.
The third embodiment is the same as the third embodiment except that the toner raw material is premixed with a supermixer, is not melted to room temperature (about 20 ° C.) after hot melt kneading with a twin-screw kneader, and is rapidly cooled. Similarly, a toner was prepared. As a result, the flowability of the toner at room temperature (about 20 ° C.) drops to 0.67 g / min, the development characteristics deteriorate, the fixing performance also deteriorates, and a stable image cannot be obtained. It was.

A fourth comparative example of the present invention will be described.
85 wt% of styrene-acrylic copolymer resin having a weight average molecular weight of about 230,000 consisting of 90 parts by weight of styrene and 10 parts by weight of n-butyl acrylate, chromium-containing dye (trade name: Bontron S- 34) Toner raw material composed of 1 wt%, carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Corporation) 10 wt%, wax A-2 3.2 wt%, wax C-1 0.8 wt% is preliminarily stored in a super mixer. After mixing by hot melt kneading with a twin-screw kneader, the mixture is allowed to cool to room temperature (about 20 ° C.) to obtain a solidified product, pulverized with a jet mill, and then classified with a dry air classifier to have an average particle size of about 9 μm. Obtained particles. Furthermore, 0.8 wt% of hydrophobic silica (trade name: Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) is added to the particles, and the mixture is stirred with a Henschel mixer to adhere the hydrophobic silica to the surface of the particles. Got.

  Wax A-2 is a polyethylene wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.71, a melt viscosity at 140 ° C. of 8.5 mPa · s, and a crystallinity of 83%. Wax C-1 is a paraffin wax having a weight average molecular weight / number average molecular weight (Mw / Mn) of 1.07, a melt viscosity of 2.4 mPa · s at 140 ° C., and a crystallinity of 86%.

  The mixture of wax A-2 and wax C-1 (A-2 / C-1 = 4/1 weight ratio) has a maximum endothermic peak at 62 ° C. in the DSC curve, and the onset temperature attributed to it. Is 46 ° C. The other endothermic peaks are at 82 ° C. and 109 ° C., and the onset temperature attributed to them is higher than 46 ° C. The onset temperature attributed to each endothermic peak is the above-mentioned 46 onset temperature. ° C.

  The melting start temperature (Tfb) of the toner is 100 ° C., the DSC curve of the toner has a melting point (Tmp) corresponding to the maximum endothermic peak attributed to the wax in the absorption heat quantity curve at the time of temperature increase, and the glass transition point of the toner. Was 51 ° C. Further, the flowability of the toner at room temperature (about 20 ° C.) was relatively good with a drop amount of 2.35 g / min, but when the storage temperature was changed from room temperature (about 20 ° C.) to 50 ° C., The fluidity of the toner was greatly reduced.

  As a result of evaluating the toner by the same method as in the first embodiment, the storage stability of the toner was almost good. Also, when applied to a laser beam printer and performing continuous printing, good fixing performance is obtained. Even if continuous printing of 300,000 pages is repeated, the life of the developer due to the carrier spent by the toner is reduced, and the toner is used. The life of the photoconductor was not reduced by the photoconductor filming, and a stable image could be obtained. However, when continuous printing was performed at high temperature and high humidity (32 ° C., 80% RH), the toner density increased abnormally, and a stable image could not be obtained.

  As described above, when the toner of the present invention is used, the fixing performance of the toner can be greatly improved, the toner has good heat resistance, durability, storage stability, and fluidity, and the development caused by the carrier spent by the toner. Providing a stable electrostatic toner image production device that reduces the life of the photoconductor, decreases the life of the photoconductor due to filming of the photoconductor, decreases the storage stability due to the environment, and reduces the development characteristics due to the decrease in the fluidity of the toner. it can.

An example of an electrostatic charge image recording process of the present invention. The figure which showed the relationship between the viscosity (140 degreeC) of a wax, and the fixing strength of a toner. Measurement example of endothermic peak and onset temperature by DSC absorption calorific value curve of wax. The measurement example of the glass transition point and melting | fusing point by the DSC absorption heat quantity curve of a toner. The figure which showed the relationship between the amount of fall of a toner, and the charge amount of 10 seconds after a developer stirring. Measurement example of melting start temperature with constant load extrusion type capillary rheometer.

Explanation of symbols

1 laser beam printer, 2 apparatus frame, 3 printing section, 4 photosensitive drum, 5 charger, 6 laser light, 7 developing apparatus, 8 cassette, 9 paper, 10 paper feed roller mechanism,
DESCRIPTION OF SYMBOLS 11 Transfer device, 12 Conveyor belt, 13 Contact-type heat fixing device, 14 Fixing roller, 14a Heat roller, 14b Backup roller, 15 Paper conveyance switching member, 16, 17 Discharge part, 18 Cleaning device, 19 Toner replenishing device, 20 Both sides Paper path for printing, A Paper transport mechanism

Claims (2)

The latent electrostatic image formed on the electrostatic charge image holding member is visualized using a two-component developer composed of an electrostatic charge image developing toner and a carrier, and the visualized toner image is transferred onto a recording medium. In the electrostatic charge image recording step of cleaning the toner image remaining on the electrostatic charge image holding member and fixing the toner image transferred onto the recording medium to obtain a recorded image, the electrostatic charge image developing toner comprises: possess at least a fixing resin and a wax, the wax is
A: a wax having a weight average molecular weight (Mw) / number average molecular weight (Mn) exceeding 1.5, a melt viscosity at 140 ° C. of less than 10 mPa · s, and a crystallinity of less than 90%;
B: a wax having a weight average molecular weight (Mw) / number average molecular weight (Mn) of 1.5 or less, a melt viscosity at 140 ° C. of less than 10 mPa · s, and a crystallinity of 90% or more,
C: a wax having a weight average molecular weight (Mw) / number average molecular weight (Mn) of 1.5 or less, a melt viscosity at 140 ° C. of less than 10 mPa · s, and a crystallinity of less than 90%,
The wax mixture of A and B, or the wax mixture of any one of the wax mixture of B and C , and the DSC curve of the wax mixture , The maximum endothermic peak of the endothermic peak at the time of temperature rise is less than 110 ° C, the onset temperature attributed to the maximum endothermic peak exceeds 50 ° C, and the lowest onset temperature among the onset temperatures attributed to the endothermic peak The temperature is in the range of 30 ° C. to 50 ° C., a wire mesh with an inner diameter of 75 mm is used for the vibration sieve, the wire diameter of the wire mesh is 50 μm, the mesh opening is 75 μm, and 5 g of the electrostatic charge image developing toner is supplied to the vibration sieve. Then, when the amount of dropping of the electrostatic image developing toner was measured by applying vibration for 1 minute at an amplitude of 0.35 mm and a frequency of 50 Hz, the amount of dropping was 2.0 g / min or more. An image forming apparatus, wherein toner for developing an electrostatic charge image is fixed on both sides of the recording medium . 2. The electrostatic charge image developing toner according to claim 1, wherein a toner raw material containing the wax mixture and the fixing resin is melted and kneaded and allowed to cool to room temperature (about 20 ° C.).
more than

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