JP2009157236A - Method for manufacturing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner giving an image with little change in gloss regardless to a fixing temperature, and to provide a method for manufacturing the toner. <P>SOLUTION: The method for manufacturing a toner includes a step of melt-kneading a toner source material comprising at least a binder resin, a colorant and a release agent by use of an open-roll type kneading machine. The binder resin contains a low softening point resin having a softening point of from 70°C to less than 130°C and a high softening point resin having a softening point of from 130 to 170°C. In the above melt-kneading step, when an effective kneading length in the kneading machine, the end of kneading in an upstream side in the effective kneading length of the roll, and the end of kneading in a downstream side are denoted by L, 0L and 1L, respectively, the low softening point resin is supplied to the kneading machine at a position from 0L to 0.3L while the high softening point resin is supplied to the kneading machine at a position from 0.4L to 0.7L. A toner is obtained by the above method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and a manufacturing method thereof.

With the spread of full-color printers and the development of technology, development of toners corresponding to higher speed and higher image quality is desired. Therefore, as a method for producing toner that enhances the dispersibility of internal additives such as colorants and charge control agents, a method using an open roll type kneader and further examining the supply position of the internal additive to the kneader is known. (See Patent Documents 1 and 2).
JP 2005-234508 A JP 2002-196536 A

  However, using an open roll type kneader to knead the toner raw material containing a low softening point resin and a high softening point resin enables kneading of the release agent and the internal additive at a low temperature. The gloss of the resulting image varies greatly.

  An object of the present invention is to provide a toner capable of obtaining an image having a small gloss change regardless of the fixing temperature, and a method for producing the toner.

  As a result of the study by the present inventors on the relationship between the fixing temperature and the gloss of the image, when the toner raw material containing the low softening point resin and the high softening point resin is kneaded using an open roll kneader, the high softening point resin is softened. Therefore, it was found that a low molecular weight component was generated by the molecular chain scission of the high softening point resin, and that this low molecular weight component was involved in the change in image gloss as the toner fixing temperature increased. That is, the low molecular weight component generated by molecular chain scission tends to increase the gloss of the image obtained as the fixing temperature of the toner increases, but it causes a high temperature offset above a certain temperature and the gloss decreases sharply. It is estimated to be. Therefore, the present inventors have further studied a method for preventing the generation of low molecular weight, and have completed the present invention.

The present invention
[1] A toner production method including a step of melt-kneading a toner raw material containing at least a binder resin, a colorant, and a release agent using an open roll kneader, the binder resin Includes a low softening point resin having a softening point of 70 ° C. or higher and lower than 130 ° C. and a high softening point resin having a softening point of 130 to 170 ° C. In the melt-kneading step, the kneading effective length of the kneader is L, kneading rolls In the effective portion, when the upstream end of kneading is 0 L and the downstream end of kneading is 1 L, the low softening point resin is supplied to the kneader at a position of 0 L to 0.3 L, and 0.4 L to 0.7 L. And a toner production method in which the high softening point resin is supplied to a kneader at the position [2], and a toner obtained by the method [1].

  According to the method of the present invention, it is possible to produce a toner capable of obtaining an image with a small gloss change regardless of the fixing temperature.

  The present invention is a method for producing toner by a method including a step of melt-kneading a toner raw material containing at least a binder resin, a colorant, a charge control agent and a release agent using an open roll kneader. As the binder resin, a resin containing a low softening point resin having a specific softening point and a high softening point resin is used.

  The softening point of the low softening point resin is 70 ° C. or more and less than 130 ° C., preferably 75 to 110 ° C., more preferably 80 to 100 ° C., from the viewpoint of the balance between the toner fixing property to paper and high temperature offset resistance. ° C. Two or more kinds of resins in the above range can be used in combination to form a low softening point resin. In this case, the weighting average value of the softening points based on the weight of the resin is used as the softening point. On the other hand, the softening point of the high softening point resin is 130 to 170 ° C., preferably 130 to 160 ° C., more preferably 135 to 155, from the viewpoint of the balance between the fixing property of the toner to paper and the high temperature offset resistance. ° C. Two or more kinds of resins in the above range can be used in combination to form a high softening point resin. In this case, a weighted average value of softening points based on the weight of the resin is used as the softening point. By using these resins having different softening points in combination, it is possible to achieve both the fixing property of the toner to the paper and the high temperature offset resistance.

  The weight ratio of the low softening point resin to the high softening point resin (low softening point resin / high softening point resin) is preferably 20/80 to 80/20, and more preferably 40/60 to 60/40.

  The total amount of the low softening point resin and the high softening point resin is preferably 70% by weight or more, and more preferably 90% by weight or more in the binder resin.

  Examples of the binder resin used in the present invention include polyesters, vinyl resins, epoxy resins, polycarbonates, polyurethanes, and the like. Among these, polyesters are used from the viewpoint of toner fixability and image transparency. Is preferred.

  Polyester is obtained by using a carboxylic acid component and an alcohol component as raw material monomers and subjecting them to condensation polymerization.

  Examples of the alcohol component include polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane, which are represented by the formula (I):

(In the formula, RO is an oxyalkylene group, R is an ethylene and / or propylene group, x and y represent the number of added moles of alkylene oxide, each being a positive number, and the average of the sum of x and y) The value is preferably 1 to 16, more preferably 1 to 8, and further preferably 1.5 to 4)
Aromatic diols such as alkylene oxide adducts of bisphenol represented by: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 -Aliphatic diols such as hexanediol, 1,4-butenediol, 1,3-butanediol and neopentyl glycol, and trihydric or higher polyhydric alcohols such as glycerin.

  Examples of carboxylic acid components include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, etc. An aliphatic dicarboxylic acid such as phthalic acid, isophthalic acid and terephthalic acid; an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid; a trivalent or higher polyvalent carboxylic acid such as trimellitic acid and pyromellitic acid; And anhydrides of these acids, alkyl (1 to 3 carbon atoms) esters; rosins; rosins modified with fumaric acid, maleic acid, acrylic acid, and the like.

  The alcohol component may contain a monovalent alcohol and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoint of adjusting the molecular weight of the polyester and improving the offset resistance of the toner.

  The polyester is obtained by polycondensing an alcohol component and a carboxylic acid component at 180 to 250 ° C., for example, in an inert gas atmosphere, if necessary, in the presence of an esterification catalyst.

  In the present invention, the polyester may be a polyester modified to such an extent that the characteristics are not substantially impaired. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more kinds of resin units including a polyester unit.

  The glass transition point of the polyester is preferably from 40 to 80 ° C, more preferably from 50 to 70 ° C, from the viewpoint of pulverization and storage. The acid value of the polyester is preferably 50 mgKOH / g or less, more preferably 1 to 30 mgKOH / g.

  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, Isoindoline, Disazo Yellow and the like can be used, and the toner of the present invention may be either black toner or 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.

  As the charge control agent, any one of negative chargeability and positive chargeability can be used. Examples of the negatively chargeable charge control agent include metal-containing azo dyes, copper phthalocyanine dyes, metal complexes of salicylic acid alkyl derivatives, and nitroimidazole derivatives. Examples of the positively chargeable charge control agent include nigrosine dyes, triphenylmethane dyes, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and the like. Also, a polymer type such as a resin can be used. The content of the charge control agent is preferably 0.1 to 8 parts by weight and more preferably 0.2 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

  Mold release agents include polypropylene wax, polyethylene wax, synthetic wax such as Fischer Tropu, coal wax such as montan wax, petroleum wax such as paraffin wax, wax such as alcohol wax, carnauba wax, rice wax, and candelilla. Natural waxes such as wax may be used, and these may be used alone or in admixture of two or more. Carnauba wax is preferred from the viewpoint of offset resistance of the toner. The content of the release agent is preferably 0.5 to 10 parts by weight and more preferably 1 to 8 parts by weight with respect to 100 parts by weight of the binder resin.

  The melting point of the release agent is preferably from 65 to 110 ° C., more preferably from 70 to 90 ° C., from the viewpoint of offset resistance and storage stability of the toner.

  The toner material further includes additives such as magnetic powder, fluidity improver, conductivity modifier, extender pigment, reinforcing filler such as fibrous substance, antioxidant, anti-aging agent, and cleaning improver as appropriate. It may be contained.

  The present invention has a great feature in that the low softening point resin and the high softening point resin are supplied from a specific position to the kneader in the step of melt kneading the toner raw material using an open roll type kneader. That is, in the present invention, when the effective kneading length of the open roll kneader is L, the upstream end of kneading is 0 L in the effective kneading portion of the roll, and the downstream end of kneading is 1 L. From the viewpoint of the position of L and the dispersibility of the internal additives such as the colorant, the low softening point resin is preferably supplied to the kneader at a position of 0 L to 0.2 L (hereinafter also referred to as “feed 1”). The high softening point resin is supplied to the kneader at a position of 0.45 L to 0.7 L (hereinafter also referred to as “feed 2”) from the viewpoint of the change in gloss of the obtained image and the gloss of the obtained image. In other words, the present invention is characterized in that a resin having a high softening point is not melt-kneaded at the initial stage of kneading. Thereby, the production | generation of the low molecular weight component by the molecular chain cutting | disconnection in high softening point resin can be suppressed. In the present invention, by suppressing the generation of low molecular weight components caused by molecular weight cutting, it is possible to produce a toner that can obtain an image with a small gloss change regardless of the fixing temperature of the toner. The kneading effective length of the open roll type kneader means the length of the kneading effective portion having grooves used for kneading on the surface of the roll. The upstream side of kneading refers to the raw material supply port side, and the downstream side of kneading refers to the kneaded product discharge port side.

  Feed 1 and feed 2 are preferably separated by 0.4 L or more, more preferably 0.5 L or more, from the viewpoint of change in gloss of the obtained image.

  Further, in the present invention, the effect of the present invention can be obtained unless the molecular chain breakage of the high softening point resin occurs. Accordingly, a part of the low softening point resin may be supplied from the feed 2 or other supply port as long as the toner raw material supplied from the feed 1 can be melt-kneaded. From the viewpoint of melting and kneading the toner raw material, the amount of the low softening point resin supplied to the feed 1 is preferably 30% by weight or more, more preferably 50% by weight or more, and 90% by weight in the total amount of the low softening point resin used. The above is more preferable.

  Toner raw materials other than the binder resin, such as a colorant, may be divided and supplied to the kneader or supplied all at once, but supplied to the open roll kneader with feed 1 together with the low softening point resin. It is preferable to do. It is preferable that the toner raw material other than the binder resin and the low softening point resin are uniformly mixed and then supplied to the kneader.

  Examples of the mixer used for mixing the toner raw material include a Henschel mixer, a super mixer, and the like. From the viewpoint of dispersibility of internal additives such as a colorant, a Henschel mixer is preferable.

  The open roll type kneader means an open type kneading unit, and can easily dissipate heat of kneading generated during melt kneading. The open roll type kneader used in the present invention comprises a plurality of raw material supply ports and a kneaded product discharge port provided along the axial direction of the roll, and from the viewpoint of production efficiency, a continuous open roll type kneader. It is preferable that

  The open roll type kneader used in the present invention preferably has at least two kneading rolls having different temperatures. The roll temperature can be adjusted by, for example, the temperature of the heat medium passed through the inside of the roll, and each roll may be divided into two or more parts and passed through heat mediums having different temperatures.

From the viewpoint of the stability of melt kneading, in the roll having a higher set temperature upstream of kneading (also referred to as a heating roll), the set temperature upstream of kneading is (softening point (Tm _L ) of low softening point resin) The range of −10) to (softening point of low softening point resin (Tm _L ) +10) ° C. is preferable, and the range of (Tm _L −5) to (Tm _L +10) ° C. is more preferable. In addition, the set temperature on the downstream side of the kneading is determined from the same viewpoint (average softening point of low softening point resin and high softening point resin (Tm) -10 to (average softening point of low softening point resin and high softening point resin) The range of (Tm) + 20 ° C. is preferable, and the range of (Tm-5) to (Tm + 20) ° C. is more preferable.The average softening point of the low softening point resin and the high softening point resin is based on their weight. It is the weighted average value of the softening points.

From the viewpoint of the stability of melt kneading, the difference in the set temperature between the upstream side of kneading and the downstream side of kneading in the heating roll is [(average softening point (Tm) -low softening point of low softening point resin and high softening point resin]. Resin softening point (Tm _L ))-10) to [(average softening point of low softening point resin and high softening point resin (Tm)-softening point of low softening point resin (Tm _L )) + 20] A range of [(Tm−Tm _L ) −5] to [(Tm−Tm _L ) +20] ° C. is more preferable.

  In a roll having a lower set temperature on the upstream side of kneading (also referred to as a cooling roll), the set temperature on the upstream side of kneading may be the same as or different from the set temperature on the downstream side of kneading.

  The rolls of the open roll type kneader preferably have different peripheral speeds. In the open roll type kneader provided with the heating roll and the cooling roll, the heating roll has a peripheral speed from the viewpoint of dispersibility. The higher roll (high rotation side roll) and the cooling roll are preferably lower rolls (low rotation side roll).

  The peripheral speed of the high rotation side roll is preferably 2 to 100 m / min, more preferably 5 to 75 m / min. The peripheral speed of the low rotation side roll is preferably 2 to 100 m / min, more preferably 4 to 60 m / min, and further preferably 4 to 50 m / min. Further, the ratio of the peripheral speeds of the two rolls (low rotation side roll / high rotation side roll) is preferably 1/10 to 9/10, more preferably 3/10 to 8/10.

  The gap (clearance) between the two rolls is preferably 0.1 to 3 mm, more preferably 0.1 to 1 mm at the upstream end of the kneading. The gap between the two rolls at the downstream end of the kneading may be the same as the upstream end of the kneading, but from the viewpoint of suppressing the molecular chain breakage of the high softening point resin, from the upstream end of the kneading. The gap difference is preferably 0.1 to 2 mm, more preferably 0.1 to 1 mm.

  The structure, size, material, and the like of each roll are not particularly limited, and the roll surface has grooves used for kneading, and examples of the shape include a linear shape, a spiral shape, a corrugated shape, and an uneven shape. It is done.

  Since the feed rate and average residence time of the raw material mixture vary depending on the size of the roll used, the composition of the raw material, and the like, optimal conditions may be selected according to these conditions.

  Except for the melt-kneading step using an open roll kneader, the obtained melt-kneaded product is cooled to such an extent that it can be pulverized, and then the toner of the present invention can be obtained through ordinary methods such as a pulverization step and a classification step. it can.

  In the pulverization step, it is desirable to pulverize the volume-median particle size to 20 μm or less, more preferably 10 μm or less from the viewpoint of improving durability.

  The pulverization process may be performed in multiple stages. For example, the melt-kneaded product may be coarsely pulverized to about 1 to 5 mm and further finely pulverized. Moreover, in order to improve the productivity at the time of a grinding | pulverization and a classification process, you may grind | pulverize, after mixing melt-kneaded material with inorganic fine particles, such as hydrophobic silica.

  The pulverizer used in the pulverization step is not particularly limited. For example, examples of the pulverizer suitably used for the coarse pulverization include an atomizer and a rotoplex, but a hammer mill or the like may be used. Further, examples of the pulverizer suitably used for fine pulverization include a jet mill, a collision plate mill, and a rotary mechanical mill.

  Examples of the classifier used in the classification process include an air classifier, an inertia classifier, and a sieve classifier. In the classification step, the pulverized product which has been removed due to insufficient pulverization may be subjected to the pulverization step again, and may be repeated with the pulverization step and the classification step as necessary.

The toner particles obtained through the pulverization step and the classification step after the melt-kneading step may be used as toners as they are, or external additives may be externally added to the toner particle surfaces and used as toners. The volume median particle size (D ₅₀ ) of the toner (particles) is preferably 3 to 12 μm, and more preferably 4 to 10 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.

  Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide. Among these, silica having a small specific gravity is preferable from the viewpoint of preventing embedding.

As the external additive, silica having a small specific gravity is preferable from the viewpoint of exerting a spacer effect. From the viewpoint of environmental stability, the silica is preferably hydrophobic silica that has been subjected to a hydrophobic treatment. The method for hydrophobizing is not particularly limited, and examples of the hydrophobizing agent include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, methyltriethoxysilane, and the like. The treatment amount of the hydrophobizing agent is preferably 1 to 7 mg / m ² per surface area of the inorganic fine particles.

  The content of the external additive is preferably 0.01 to 10 parts by weight and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner particles.

  The external addition step is preferably a dry mixing method in which the external additive and toner particles are mixed using a high-speed stirrer such as a Henschel mixer or a super mixer, a V-type blender or the like. The external additives may be mixed in advance and added to a high-speed stirrer or a V-type blender, or may be added separately.

  The toner of the present invention can be used as a one-component developing toner or as a two-component developer mixed with a carrier.

[Softening point of resin]
Using a flow tester (Shimadzu Corporation, CFT-500D), a 1 g sample is heated at a heating rate of 6 ° C / min, and a 1.96 MPa load is 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 of resin]
Using a differential scanning calorimeter (DSCQ20, manufactured by TA Instruments Japan), the sample was heated to 200 ° C and cooled to 0 ° C at a temperature decrease rate of 10 ° C / min. The temperature is raised at ° C./min, and the temperature is the intersection of the base line extension below the maximum peak temperature of endotherm and the tangent that indicates the maximum slope from the peak rise to the peak apex.

[Resin acid value]
Measured by the method of JIS K0070. However, only the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Melting point of release agent]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the temperature was raised to 200 ° C, and the sample was cooled to 0 ° C at a temperature drop rate of 10 ° C / min. The maximum peak temperature of heat of fusion is taken as the melting point.

[Volume-median particle diameter of toner (D ₅₀ )]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 100 μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
Electrolyte: Isoton II (Beckman Coulter, Inc.)
Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) 5% electrolyte dispersion condition: 10 mg of measurement sample is added to 5 ml of dispersion, and dispersed for 1 minute with an ultrasonic disperser. Then, 25 ml of the electrolytic solution is added, and further dispersed with an ultrasonic disperser for 1 minute.
Measurement conditions: Add 100 ml of electrolyte and dispersion in a beaker, measure 30,000 particles at a concentration that can measure the particle size of 30,000 particles in 20 seconds, and determine the volume-median particle size ( determine the D _50).

Resin production example 1
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 2450 g, Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 975 g, terephthalic acid 963 g, dodecenyl succinic acid 343 g, 298 g of trimellitic anhydride and 10 g of dibutyltin oxide (esterification catalyst) were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, dehydration tube, stirrer and thermocouple, and 230 ° C under a nitrogen atmosphere. The reaction was continued until the reaction rate reached 90%, and then the reaction was carried out at 8.3 kPa until the desired softening point was reached to obtain a polyester (resin A). The obtained resin A had a softening point (Tm _H ) of 150 ° C., a glass transition point of 63 ° C., and an acid value of 3.4 mgKOH / g. The reaction rate was calculated from the amount of water produced during the reaction with respect to the theoretical amount of water produced.

Resin production example 2
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 3564g, terephthalic acid 761g, and titanium diisopropoxytriethanolamate (esterification catalyst) 24g, nitrogen introduction tube, dehydration tube, stirring The mixture was placed in a 5-liter four-necked flask equipped with a vessel and a thermocouple, and reacted under a nitrogen atmosphere at 230 ° C. until the reaction rate reached 90%, and then reacted at 8 kPa for 1 hour. Thereafter, the mixture was cooled to 185 ° C., 437 g of fumaric acid and 2.4 g of hydroquinone were added, reacted for 4 hours to 210 ° C., reacted at 8.0 kPa until the desired softening point was reached, and polyester (resin B ) The obtained resin B had a softening point (Tm _L ) of 92 ° C., a glass transition point of 52 ° C., and an acid value of 4.2 mgKOH / g.

Examples 1 and 2
Resin B 55 parts by weight as a low softening point resin, colorant “ECB-301” (manufactured by Dainichi Seika Co., Ltd., copper phthalocyanine pigment) 5.7 parts by weight, positive charge control agent “Bontron P-51” (Orient Chemical Industries) 1 part by weight) and 6 parts by weight of release agent “Carnauba Wax C1” (manufactured by Kato Yoko Co., Ltd., melting point: 83 ° C.) were mixed with a Henschel mixer, and the resulting mixture was fed from the raw material supply port F1 to 6.1 kg / h As a high softening point resin, 45 parts by weight of resin A is supplied at a feed rate of 3.9 kg / h from the raw material supply port F2, and each roll has a roll outer diameter of 0.12m and a kneading effective length (L) of 0.8m. The mixture was supplied to an open roll kneader and melt kneaded under the conditions shown in Table 1. The raw material supply port F1 is located at 0.05 L and the raw material supply port F2 is located at 0.55 L from the upstream side to the downstream side of kneading.

The obtained kneaded product was cooled and then roughly pulverized to about 2 mm with a hammer mill. Further, it was finely pulverized by a jet mill and classified to obtain toner particles having a volume median particle diameter (D ₅₀ ) of 7.5 μm.

  To 100 parts by weight of the obtained toner particles, 1.5 parts by weight of hydrophobic silica “R-972” (manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: DMDS) is added as an external additive, and mixed with a Henschel mixer. Got.

Comparative Examples 1-3
Resin A and resin B are used in the amounts (parts by weight) shown in Table 1, and resin A is mixed with resin B, colorant, etc., not from the raw material supply port F2, and supplied from the raw material supply port F1 to the kneader. Then, a toner was obtained in the same manner as in Example 1 except that it was melt-kneaded under the conditions shown in Table 1. In Comparative Examples 1 to 3, since the resin A having a high softening point is supplied by F1, the set temperature on the upstream side of the kneading of the heating roll is higher than that on the downstream side of the kneading in order to melt and knead the toner raw material. did. In Comparative Example 3, the roll interval was increased to 0.8 mm so that the molecular chain breakage of the high softening point resin was suppressed.

Test example 1
A laser beam printer “HL-3040” (manufactured by Brother Industries) was used as a printing apparatus, and 100 mm × 100 mm unfixed solid images of the toners of Examples 1 and 2 and Comparative Examples 1 to 3 were obtained. The obtained unfixed solid image was fixed at a speed of 100 mm / sec with an external fixing machine (roller diameter: 38 mm, silicone-coated soft roller) set to a predetermined roll temperature (fixing temperature). The glossiness (60 ° / 60 °) of a total of 5 locations (60 ° / 60 °) of the fixed solid image was measured with a gloss meter “Gloss Checker IG-330” (manufactured by Horiba). The results are shown in Table 2 and FIG.

  From the above results, it can be seen that in Examples 1 and 2, the change in gloss accompanying the change in fixing temperature is small, and a stable glossiness can be maintained especially at 160 to 200 ° C. regardless of the fixing temperature. On the other hand, in Comparative Examples 1 and 2 in which the high softening point resin was supplied to the kneading machine together with the low softening point resin and the colorant, the glossiness changed greatly at a peak of 170 ° C., and the glossiness was higher than 170 ° C. The decrease was due to a high temperature offset. Also in Comparative Example 3, it can be seen that the glossiness suddenly increases in the fixing temperature range of 160 ° C. to 180 ° C. This is due to the low molecular weight component generated by the molecular chain scission of the high softening point resin, and a comparative example in which melt temperature kneading was performed by selecting conditions for lowering shear on the resin at the roll temperature, rotation speed, and roll gap. In FIG. 3, although the molecular chain scission of the high softening point resin is suppressed as compared with Comparative Examples 1 and 2 and the occurrence of high temperature offset is prevented, the control of low molecular weight components is still possible as compared with Examples 1 and 2. Is inferior. In addition, although Comparative Examples 1 and 2 differ from Examples 1 and 2 in the compounding ratio of Resins A and B, Examples 1 and 2 are located between Comparative Examples 1 and 2 in the compounding ratio. It is considered that the difference in the blending ratio between the comparative example and the comparative example is not the main cause of the change in glossiness.

  The toner obtained by the present invention is used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

3 is a graph of glossiness measured in Test Example 1.

Claims (4)

  A method for producing a toner comprising a step of melt-kneading a toner raw material containing at least a binder resin, a colorant and a release agent using an open roll kneader, wherein the binder resin has a softening point Includes a low softening point resin having a softening point of 70 ° C. or more and less than 130 ° C. and a high softening point resin having a softening point of 130 to 170 ° C., and in the melt kneading step, the kneading effective length of the kneader is L, in the kneading effective portion of the roll When the upstream end of kneading is 0 L and the downstream end of kneading is 1 L, the low softening point resin is supplied to the kneader at a position of 0 L to 0.3 L, and at a position of 0.4 L to 0.7 L. A method for producing a toner, wherein the high softening point resin is supplied to a kneader.   The open roll type kneader has two rolls for kneading at different temperatures, and in the roll having the higher temperature on the upstream side of the kneading, the set temperature on the upstream side of the kneading is (softening point of the low softening point resin- 10)-(softening point of low softening point resin + 10) ° C, and the set temperature downstream of kneading is (average softening point of low softening point resin and high softening point resin-10)-(low softening point) The toner production method according to claim 1, wherein the toner is in a range of an average softening point of the resin and the high softening point resin + 20 ° C.).   The toner according to claim 1, wherein the open roll type kneader has two rolls, and the gap between the two rolls is wider at the downstream end of the kneading than at the upstream end of the kneading. Manufacturing method.   A toner obtained by the method according to claim 1.

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