JP6181461B2 - Method for producing toner for developing electrostatic image - Google Patents

Description

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

  In recent years, with a reduction in energy consumption and an increase in printing speed, toners are required to have low temperature fixability. In addition, as the print-on-demand market grows, the demand for high reliability for electrophotographic technology is increasing. In particular, there is a demand for high heat-resistant storage stability of toners used in electrophotography.

  In many cases, the toner is produced by melt-kneading a composition mainly composed of a colorant and a binder resin, pulverizing and classifying the obtained kneaded product. There is a need for a highly productive toner manufacturing method that can efficiently perform these steps.

  Patent Document 1 discloses a crystalline polyester and an amorphous polyester as a method for producing an electrophotographic toner that has both low-temperature fixability and heat-resistant storage stability and also has excellent pulverizability when manufactured by melt-kneading pulverization. A glass transition point (Ttg) satisfying a specific relationship, and two endothermic peak temperatures (Ttq, Ttm) in differential scanning calorimetry derived from the crystal structure of the binder resin An electrophotographic toner manufacturing method comprising the step of heating and holding a toner composition containing the binder resin [step (1)], wherein the step (1) comprises: Step (A): A step of heating and holding the toner composition at a heating temperature Tra (° C.) satisfying a relationship represented by a specific formula; and Step (B): a heated holding material obtained in Step (A) The heating temperature Trb (10-70 ° C. lower than the heating temperature Tra (° C.) ) In including a step, of heating and holding method for producing a toner is disclosed for electrophotography.

JP 2009-128652 A

  However, a toner using carbon black widely used as a black colorant has a problem that a pressure required for pulverization increases. As described in Patent Document 1, although there are other attempts to improve the properties and manufacturing conditions of the binder resin to achieve both heat-resistant storage stability and productivity, it has not been sufficient.

  The present invention is a method for producing a toner having a low pressure required for pulverization, a good pulverization yield, and excellent productivity, and a method for producing a toner for developing an electrostatic image capable of obtaining a toner excellent in heat-resistant storage stability, and The present invention relates to a toner for developing an electrostatic image obtained by this method.

The present invention
[1] Step 1: A step of obtaining a resin mixture by melting and kneading a binder resin containing polyester and carbon fine particles using lignin as a raw material, and Step 2: pulverizing and classifying the resin mixture obtained in Step 1 A process for producing an electrostatic charge image developing toner, and [2] an electrostatic charge image developing toner obtained by the production process of [1].

  The method of the present invention is a method for producing a toner for developing an electrostatic charge image with low productivity required for pulverization, high pulverization yield, and high productivity. Furthermore, the electrostatic image developing toner obtained by the method of the present invention is excellent in heat-resistant storage stability.

The method for producing the toner for developing an electrostatic charge image of the present invention comprises:
Step 1: A step of obtaining a resin mixture by melt-kneading a binder resin containing polyester and carbon fine particles using lignin as a raw material, and Step 2: a step of pulverizing and classifying the resin mixture obtained in Step 1 This method has a great feature in that carbon fine particles using lignin as a raw material are used. By the method of the present invention, a toner having excellent heat-resistant storage stability can be obtained with high productivity. The reason is not clear, but it can be considered as follows.

  Since carbon black widely used in toner exhibits a filler effect in the resin, the pulverization pressure in the pulverization step increases. However, the carbon fine particles using lignin as a raw material used in the present invention generally have a larger particle diameter than carbon black, and thus hardly cause a filler effect. As a result, a toner containing carbon fine particles using lignin as a raw material is more easily pulverized at a lower pulverization pressure than a carbon black-containing toner using the same resin.

  Moreover, since the carbon fine particles using lignin as a raw material have low volume resistance and hardly cause electrostatic aggregation, aggregation between particles pulverized in a pulverizer or a classifier is suppressed. Therefore, since it is not necessary to repeatedly grind, it is not necessary to require an excessive crushing pressure, the generation of fine powder is reduced, and the crushing yield is improved.

  On the other hand, carbon fine particles using lignin as a raw material are synthesized by thermal decomposition of lignin, so the surface of the fine particles is considered to be oxidized to some extent. Therefore, it is considered that the polyester resin having a higher polarity has better dispersibility than the styrene acrylic resin, and as a result, electrostatic aggregation of the toner particles is suppressed, and heat resistant storage stability is improved.

[Carbon fine particles using lignin as raw material]
In the present invention, carbon fine particles using lignin as a raw material are prepared by forming fine droplets from a solution of an organic raw material containing lignin as a main component, and drying the fine droplets. Carbon fine particles produced by thermal decomposition in the range of 1200 ° C. are preferred (Japanese Patent Application Laid-Open No. 2009-155199 [Claim 1]). When used in the method of the present invention, the fired product is preferably pulverized and classified.

  Examples of commercially available carbon fine particles made of lignin as a raw material include “lignin black” (manufactured by Daio Paper Co., Ltd.).

  The volume-median particle size of carbon fine particles using lignin as a raw material improves the grinding efficiency of the resin mixture in Step 2, improves the toner productivity, improves the low-temperature fixability, and improves the image density. In view of the above, 1.0 μm or more is preferable, 5.0 μm or more is more preferable, and 10 μm or more is more preferable. Further, from the viewpoint of improving toner productivity, it is preferably 50 μm or less, more preferably 30 μm or less, and further preferably 20 μm or less.

  The maximum diameter of the carbon fine particles using lignin as a raw material is preferably 100 μm or less, more preferably 50 μm or less, from the viewpoint of improving toner productivity.

The specific surface area of the carbon fine particles having lignin as a raw material, from the viewpoint of improving the toner productivity is preferably 2~1000m ² / g, more preferably 5~800m ² / g, 200~700m More preferably, it is ² / g.

  The content of carbon fine particles using lignin as a raw material is 1 mass per 100 mass parts of the binder resin from the viewpoint of improving the productivity of the toner, the viewpoint of improving the heat-resistant storage stability, and the image density. Part or more, preferably 2 parts by weight or more, more preferably 3 parts by weight or more, and still more preferably 4 parts by weight or more. Moreover, from a viewpoint of improving the grinding | pulverization efficiency of the resin mixture in the process 2, 20 mass parts or less are preferable, 15 mass parts or less are more preferable, 12 mass parts or less are more preferable, and 8 mass parts or less are more preferable.

[Colorant]
As the colorant, only the above-mentioned carbon fine particles using lignin as a raw material may be used as a colorant, but all of dyes and pigments used as a colorant for toner can be used in combination. When obtaining a black toner, carbon black may be used in combination because it is easily available.

  When carbon black is used in combination, the content of carbon black is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of improving the image density. Further, from the viewpoint of improving the pulverization efficiency of the resin mixture in Step 2 and from an economical viewpoint, it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 5 parts by mass or less.

  From the viewpoint of improving toner productivity, heat-resistant storage stability, and image density, together with the content of carbon fine particles using lignin as a raw material, the content of the colorant is 1 to 100 parts by mass of the binder resin. It is preferably at least 2 parts by mass, more preferably at least 2 parts by mass, even more preferably at least 3 parts by mass, and even more preferably at least 4 parts by mass. Further, from the viewpoint of improving the pulverization efficiency of the resin mixture in Step 2 and from an economical viewpoint, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, further preferably 12 parts by mass or less, and 8 parts by mass or less. Even more preferred.

  When carbon black is used in combination, the mass ratio between the carbon fine particles using lignin and the carbon black (carbon fine particles using lignin / carbon black) is effective in improving the image density and the grinding efficiency of the resin mixture in step 2. From the viewpoint of improvement and economical viewpoint, 1/1 to 20/1 is preferable, 2/1 to 15/1 is more preferable, and 2.5 / 1 to 10/1 is further preferable.

[Binder resin]
The binder resin used in the present invention preferably contains polyester from the viewpoint of improving the low-temperature fixability of the toner. The polyester content is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, substantially more preferably 100% by mass, and more preferably 100% by mass in the binder resin. Further preferred. As the binder resin, a resin other than polyester may be contained as long as the effect of low-temperature fixability is not impaired. Examples of other binder resins include vinyl resins, epoxy resins, polycarbonates, polyurethanes, and the like.

  The polyester used in the present invention is obtained by polycondensation of an alcohol component composed of a divalent or higher alcohol and a carboxylic acid component composed of a divalent or higher carboxylic acid compound.

Examples of the divalent alcohol component include aliphatic diols having 2 to 12 main chain carbon atoms, aromatic diols, and alicyclic diols.
Specific examples of the aliphatic diol having 2 to 12 carbon atoms include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1.9-nonanediol, neopentyl glycol 1,4-butenediol and the like. The main chain carbon number is preferably 2 to 12, more preferably 2 to 8, and further preferably 3 to 6 from the viewpoint of improving toner productivity and low-temperature fixability, and is bonded to a secondary carbon atom. Even more preferred are aliphatic diols having 3 or 4 carbon atoms having a hydroxy group. Specific examples include 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, and 2,3-butanediol. From the viewpoint of improving toner productivity and low-temperature fixability, 1,2-propanediol and 2,3-butanediol are preferred, and 1,2-propanediol is more preferred.

  As the aromatic diol, the formula (I):

(Wherein R ¹ O and OR ¹ are oxyalkylene groups, R ¹ is an ethylene and / or propylene group, x and y represent the average number of moles of alkylene oxide added, each being a positive number; The average value of the sum of x and y is preferably 1 to 16, more preferably 1 to 8, and further preferably 1.5 to 4, and an alkylene oxide adduct of bisphenol A.

  Examples of the alicyclic diol include hydrogenated bisphenol A or adducts thereof having 2 to 4 carbon atoms of alkylene oxide (average added mole number of 1 to 16).

  Examples of the trihydric or higher alcohol include trihydric or higher polyhydric alcohols having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms. Specific examples include sorbitol, 1,4-sorbitan, pentaerythritol, glycerol, trimethylolpropane, and the like.

  Examples of the divalent carboxylic acid compound include 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, more preferably 3 to 10 carbon dicarboxylic acids, and their acid anhydrides and 1 to 3 carbon atoms. Examples thereof include derivatives such as alkyl esters. Specific examples include aromatic dicarboxylic acid compounds and aliphatic dicarboxylic acid compounds. Examples of the aromatic dicarboxylic acid compound include phthalic acid, isophthalic acid, and terephthalic acid. Examples of the aliphatic dicarboxylic acid compound include fumaric acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. Is mentioned. Specific examples of the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, octenyl succinic acid, and the like. Among these, from the viewpoint of improving toner productivity and low-temperature fixability, at least one selected from fumaric acid, terephthalic acid, dodecenyl succinic acid and acid anhydrides thereof is preferable, and terephthalic acid is more preferable.

  Examples of the trivalent or higher carboxylic acid compound include trivalent or higher polyvalent carboxylic acids having 4 to 30 carbon atoms, preferably 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms, and acid anhydrides thereof. And derivatives such as alkyl esters having 1 to 3 carbon atoms. Specific examples include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), and the like. Of these, trimellitic acid and its acid anhydride are preferred, and trimellitic acid anhydride is more preferred from the viewpoint of improving the low-temperature fixability and hot offset resistance of the toner.

  In addition, a monovalent alcohol may be appropriately contained in the alcohol component, and a monovalent carboxylic acid compound may be appropriately contained in the carboxylic acid component from the viewpoint of adjusting the softening point of the polyester.

  From the viewpoint of reducing the acid value of the polyester, the equivalent ratio (COOH group / OH group) of the carboxylic acid component and the alcohol component in the polyester is preferably 0.70 to 1.10, and more preferably 0.75 to 1.00.

  The polycondensation reaction between the alcohol component and the carboxylic acid component is carried out by polycondensation in an inert gas atmosphere at a temperature of about 180 to 250 ° C. in the presence of an esterification catalyst or a polymerization inhibitor, if necessary. Can be manufactured. Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamate. The amount of the esterification catalyst used is preferably 0.01 to 1.5 parts by mass, more preferably 0.1 to 1.0 part by mass with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. When the polymerization inhibitor is used, the amount used is preferably 0.001 to 0.5 parts by mass and more preferably 0.01 to 0.1 parts by mass with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

  As the polyester, either a crystalline polyester or an amorphous polyester can be used, or a mixture of both can be used. From the viewpoint of improving the high temperature offset resistance of the toner, it is preferable to use an amorphous polyester.

  Here, the crystallinity of the resin is represented by the crystallinity index defined by the ratio between the softening point and the maximum endothermic peak temperature measured by a differential scanning calorimeter, that is, the value of [softening point / maximum endothermic peak temperature]. The crystalline resin has a crystallinity index of 0.6 to 1.4, preferably 0.7 to 1.2, more preferably 0.9 to 1.2, and the amorphous resin is a resin having a value of 1.4 or less than 0.6. The crystallinity of the resin can be adjusted by the types and ratios of the raw material monomers, production conditions (for example, reaction temperature, reaction time, cooling rate) and the like. The highest endothermic peak temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. The maximum peak temperature is the melting point if the difference from the softening point is within 20 ° C., and the peak due to the glass transition if the difference from the softening point exceeds 20 ° C.

  The softening point of the polyester is preferably 70 ° C. or higher, more preferably 90 ° C. or higher, more preferably 105 ° C. or higher, and 115 ° C. or higher, from the viewpoint of improving low-temperature fixability, high-temperature offset resistance and productivity of the toner. Even more preferred. Also, it is preferably 160 ° C. or lower, more preferably 150 ° C. or lower, still more preferably 140 ° C. or lower, and even more preferably 135 ° C. or lower.

  The softening point of the polyester can be controlled by adjusting the types and composition ratios of the alcohol component and carboxylic acid component, the amount of catalyst, and the like, and selecting reaction conditions such as reaction temperature, reaction time, and reaction pressure.

  The glass transition temperature of the polyester is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, and further preferably 60 ° C. or higher, from the viewpoint of improving the low-temperature fixability, productivity and heat-resistant storage stability of the toner. Moreover, 85 degrees C or less is preferable, 80 degrees C or less is more preferable, and 75 degrees C or less is further more preferable. The glass transition temperature is a physical property unique to an amorphous resin.

  The glass transition temperature of the polyester can be controlled by the type and composition ratio of the alcohol component and carboxylic acid component.

  The acid value of the polyester is preferably 50 mgKOH / g or less, more preferably 30 mgKOH / g or less, still more preferably 20 mgKOH / g or less, from the viewpoint of improving the chargeability of the toner and improving the dispersibility of the additive. More preferably, it is 10 mgKOH / g or less.

  The acid value of the polyester can be controlled by adjusting the types and composition ratios of the alcohol component and the carboxylic acid component, the amount of the catalyst, etc., and selecting the reaction conditions such as the reaction temperature, reaction time, and reaction pressure.

  In the present invention, two or more polyesters may be used as the binder resin from the viewpoint of improving the low-temperature fixability, productivity, and heat-resistant storage stability of the toner.

  When two or more polyesters are used, the softening point of the binder resin as a whole is preferably within the above range from the viewpoint of improving the low temperature fixability, high temperature offset resistance and productivity of the toner. That is, 70 ° C. or higher is preferable, 90 ° C. or higher is more preferable, 105 ° C. or higher is more preferable, and 115 ° C. or higher is even more preferable. Also, it is preferably 160 ° C. or lower, more preferably 150 ° C. or lower, still more preferably 140 ° C. or lower, and even more preferably 135 ° C. or lower. The softening point of the entire binder resin can be obtained by a weighted average, that is, the sum of the products of the respective softening points and content ratios.

  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 or blocking with phenol, urethane, epoxy or the like by the method described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc. Polyester.

  The toner of the present invention may further contain a release agent, a charge control agent and the like.

[Release agent]
Examples of mold release agents include polypropylene wax, polyethylene wax, polypropylene polyethylene copolymer wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax and other aliphatic hydrocarbon waxes and oxides thereof, synthetic ester wax, carnauba wax. , Ester waxes such as montan wax, sazol wax and their deoxidized wax, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc., and these may be used alone or in combination of two or more. It may be used. Among these, paraffin wax, synthetic ester wax, and carnauba wax are preferable, and carnauba wax is more preferable from the viewpoint of improving low-temperature fixability and heat-resistant storage stability of the toner.

  The content of the release agent is 0.5% with respect to 100 parts by mass of the binder resin from the viewpoint of reducing mechanical force during melt-kneading and suppressing heat generation, and improving low-temperature fixability and heat-resistant storage stability of the toner. Part by mass or more is preferred, 1.0 part by mass or more is more preferred, 1.5 parts by mass or more is more preferred, and 2.0 parts by mass or more is even more preferred. Further, from the viewpoint of improving the heat resistant storage stability of the toner, it is preferably 10 parts by mass or less, more preferably 8.0 parts by mass or less, still more preferably 6.0 parts by mass or less, and even more preferably 4.0 parts by mass or less.

  The melting point of the release agent is preferably 120 ° C. or less, more preferably 100 ° C. or less, still more preferably 95 ° C. or less, and still more preferably 90 ° C. or less from the viewpoint of improving the low-temperature fixability of the toner. Further, from the viewpoint of improving the heat resistant storage stability of the toner, 50 ° C. or higher is preferable, 60 ° C. or higher is more preferable, 70 ° C. or higher is more preferable, and 80 ° C. or higher is even more preferable.

[Charge control agent]
As the charge control agent, either a negative charge control agent or a positive charge control agent 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, nitroimidazole derivatives, and benzyl acid boron complexes. Examples of metal-containing azo dyes include “Varifirst Black 3804”, “Bontron S-28”, “Bontron S-31”, “Bontron S-32”, “Bontron S-34”, “Bontron S-36” ( As mentioned above, “T-77”, “Eisenspiron Black TRH” (manufactured by Hodogaya Chemical Co., Ltd.) and the like can be mentioned. Examples of metal complexes of alkyl derivatives of salicylic acid include “Bontron E-81”, “Bontron E-82”, “Bontron E-84”, “Bontron E-304” (above, manufactured by Orient Chemical Industry Co., Ltd.) and the like. It is done. Examples of the benzyl acid boron complex include “LR-147” (manufactured by Nippon Carlit). Among these, a metal complex of an alkyl derivative of salicylic acid is preferable from the viewpoint of improving the charging stability of the toner.

  As a metal complex of a salicylic acid compound, for example, the formula (II):

(Wherein R ² , R ³ and R ⁴ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, M is chromium, Zinc, calcium, zirconium or aluminum, m is an integer of 2 or more, and n is an integer of 1 or more)
The compound represented by these is mentioned.

In the formula (II), R ³ is preferably a hydrogen atom, and R ² and R ⁴ are preferably branched alkyl groups, more preferably tert-butyl groups.

As a commercial product of the compound represented by the formula (II), “Bontron E-81” (R ³ : hydrogen atom, R ² and R ⁴ : tert-butyl group, Y: chromium, manufactured by Orient Chemical Industries), “Bontron E-84” (R ³ : hydrogen atom, R ² and R ⁴ : tert-butyl group, Y: zinc, manufactured by Orient Chemical Industries, Ltd.), “Bontron E-88” (R ³ : hydrogen atom, R ² And R ⁴ : tert-butyl group, Y: aluminum, manufactured by Orient Chemical Industry Co., Ltd., “Bontron E-304” (R ³ : hydrogen atom, R ² and R ⁴ : tert-butyl group, Y: zinc, orient chemistry) Kogyo Co., Ltd.), “TN-105” (R ³ : hydrogen atom, R ² and R ⁴ : tert-butyl group, Y: zirconium, manufactured by Hodogaya Chemical Co., Ltd.) and the like. Among these, “Bontron E-84” and “Bontron E-304” (manufactured by Orient Chemical Industry Co., Ltd.) are preferable from the viewpoint of improving the charging stability of the toner.

  Examples of the positively chargeable charge control agent include nigrosine dyes, triphenylmethane dyes, quaternary ammonium salt compounds, polyamine resins, and imidazole derivatives. Nigrosine dyes include, for example, “Nigrosine Base EX”, “Oil Black BS”, “Oil Black SO”, “Bontron N-01”, “Bontron N-07”, “Bontron N-09”, “Bontron N-11” (Above, manufactured by Orient Chemical Industry Co., Ltd.). Examples of the triphenylmethane dye include a triphenylmethane dye containing a tertiary amine as a side chain. Examples of quaternary ammonium salt compounds include “Bontron P-51”, “Bontron P-52” (manufactured by Orient Chemical Co., Ltd.), “TP-415” (Hodogaya Chemical Co., Ltd.), cetyltrimethylammonium bromide. , "COPY CHARGE PXVP435", "COPY CHARGE PSY" (manufactured by Clariant). Examples of the polyamine resin include “AFP-B” (manufactured by Orient Chemical Industry Co., Ltd.). Examples of the imidazole derivative include “PLZ-2001”, “PLZ-8001” (manufactured by Shikoku Kasei Co., Ltd.) and the like.

  From the viewpoint of improving the charging stability of the toner, the content of the charge control agent is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and more preferably 5 parts by mass or less, relative to 100 parts by mass of the binder resin. Is preferably 3 parts by mass or less, and more preferably 2 parts by mass or less.

  In the present invention, additives such as magnetic powder, fluidity improver, conductivity adjuster, reinforcing filler such as fibrous substance, antioxidant, anti-aging agent, and cleanability improver are suitably used as the toner material. You may contain.

<Toner production method>
The toner of the present invention is produced by a method including the following steps 1 and 2.
Step 1: Step of obtaining a resin mixture by melting and kneading components including a binder resin and carbon fine particles using lignin as a raw material Step 2: Step of pulverizing and classifying the resin mixture obtained in Step 1

  Step 1 can be performed using a known kneader such as a closed kneader, a uniaxial or biaxial kneader, or a continuous open roll type kneader, but is preferably performed with a biaxial kneader. A biaxial kneader is a closed type kneader in which two kneading shafts are covered with a barrel, and in a binder resin of carbon fine particles, colorants, release agents, and charge control agents made from lignin. From the viewpoint of improving the dispersibility, a type in which the shaft can rotate in the same direction is preferable. As a commercial product, from the viewpoint of improving toner productivity, a twin screw extruder PCM series manufactured by Ikekai Tekko Co., Ltd., which is good in high-speed twin screw engagement, is preferable.

  The toner raw material is preferably mixed in advance with a mixer such as a Henschel mixer or a ball mill and then supplied to the kneader.

  The melt kneading in the biaxial kneader is performed by adjusting the barrel set temperature (temperature of the inner wall surface of the extruder), the peripheral speed of biaxial shaft rotation, and the raw material supply speed. The barrel set temperature is designed to improve the dispersibility of carbon fine particles, colorants, mold release agents, and charge control agents from lignin in the binder resin, reduce the mechanical force during melt kneading, and generate heat. From the viewpoint of suppression, from the viewpoint of improving low-temperature fixability, heat-resistant storage stability and productivity of the toner, 80 ° C. or higher is preferable, and 90 ° C. or higher is more preferable. Moreover, 140 degrees C or less is preferable and 120 degrees C or less is more preferable.

  The peripheral speed of the biaxial shaft rotation is based on the viewpoint of improving the dispersibility of carbon fine particles, colorants, release agents, and charge control agents made from lignin in the binder resin, and the mechanical force during melt kneading. From the viewpoints of reducing and suppressing heat generation, and improving the low-temperature fixability, heat-resistant storage stability, and productivity of the toner, 0.1 m / sec or more is preferable, and 1 m / sec or less is preferable.

  The feed rate of the raw material to the biaxial kneader is appropriately adjusted according to the allowable capacity of the kneader to be used, the barrel set temperature and the peripheral speed of the shaft rotation.

  Step 2 is a step of pulverizing and classifying the resin mixture obtained in Step 1. The resin mixture obtained in Step 1 is preferably cooled to 40 ° C. or lower while being rolled to a thickness of 1 to 3 mm, and then subjected to a pulverization step and a classification step.

  The pulverization process may be performed in multiple stages. For example, the resin mixture may be coarsely pulverized to about 0.1 to 5 mm and further pulverized to a desired particle size.

  The pulverizer used in the pulverization step is not particularly limited, and examples of the pulverizer suitably used for coarse pulverization include a hammer mill, an atomizer, and a rotplex. Further, examples of the pulverizer suitably used for fine pulverization include a fluidized bed jet mill, a collision plate jet mill, and a rotary mechanical mill. From the viewpoint of pulverization efficiency, it is preferable to use a fluidized bed jet mill and a collision plate jet mill, and more preferably a collision plate jet mill.

  The production method of the present invention has a feature that it can be easily pulverized at a lower pulverization pressure in the pulverization step by containing carbon fine particles using lignin as a raw material. The pulverization pressure is preferably 0.45 MPa or less, more preferably 0.40 MPa or less, and more preferably 0.20 MPa or more from the viewpoint of suppressing generation of fine powder and improving toner productivity.

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

The volume median particle size (D ₅₀ ) of the toner base particles obtained in step 2 is preferably 3 μm or more, more preferably 4 μm or more, and even more preferably 6 μm or more from the viewpoint of improving the image quality of the toner. Further, it is preferably 15 μm or less, more preferably 12 μm or less, and further preferably 9 μm or less. 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.

  In the toner production method of the present invention, from the viewpoint of improving the chargeability, fluidity, and transferability of the toner, the obtained toner particles (toner mother particles) are further mixed with an external additive after the pulverization and classification steps. It is preferable to include a process. Specific examples include inorganic particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles. Two or more kinds may be used in combination. Among these, silica is preferable, and hydrophobic silica that has been subjected to a hydrophobic treatment is more preferable from the viewpoint of toner transferability.

  The number average particle diameter of the external additive is preferably 10 nm or more, more preferably 15 nm or more, more preferably 250 nm or less, and more preferably 200 nm or less, from the viewpoint of improving the chargeability, fluidity, and transferability of the toner. 90 nm or less is more preferable.

  The content of the external additive is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the toner base particles before being treated with the external additive, from the viewpoint of improving the chargeability, fluidity, and transferability of the toner. 0.5 parts by mass or more is more preferable, and 1 part by mass or more is more preferable. Further, it is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and further preferably 3 parts by mass or less.

  For mixing the toner base particles and the external additive, it is preferable to use a mixer equipped with a stirring tool such as a rotary blade, a high speed mixer such as a Henschel mixer or a super mixer is preferable, and a Henschel mixer is more preferable.

  The toner obtained by the method of the present invention is used as it is as a one-component developing toner as it is or as a two-component developing toner used by mixing with a carrier in an image forming apparatus of a one-component developing method or a two-component developing method, respectively. Can do.

  Also, the fixing method is not particularly limited, but an oilless fixing type image forming apparatus can also be suitably used. The oilless fixing is a method using a fixing device having a heat roll fixing device that does not include an oil supply device. The oil supply device has an oil tank and has a mechanism for quantitatively applying oil to the surface of the heat roll, as well as a device having a mechanism for bringing a roll pre-impregnated with oil into contact with the heat roll, etc. including.

[Softening point of resin]
Using a flow tester “CFT-500D” (manufactured by Shimadzu Corporation), a 1 g sample was heated at a heating rate of 6 ° C./min, a 1.96 MPa load was applied by a plunger, a nozzle with a diameter of 1 mm and a length of 1 mm Extrude from. 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.

[Maximum peak temperature of resin endotherm]
Using a differential scanning calorimeter “Q-100” (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample is weighed into an aluminum pan, and the temperature drops from room temperature to 0 ° C. at a rate of 10 ° C./min. Cool and let stand for 1 minute. Then, it measured with the temperature increase rate of 50 degrees C / min. Among the observed endothermic peaks, the temperature of the peak on the highest temperature side is defined as the highest endothermic peak temperature. If the maximum peak temperature is within 20 ° C of the softening point, the melting point is assumed.

[Glass transition temperature of resin]
Using a differential scanning calorimeter “Q-100” (manufactured by TA Instruments Japan), 0.01 to 0.02 g of sample is weighed into an aluminum pan, heated up to 200 ° C., and the temperature drop rate from that temperature Cooled to 0 ° C at 10 ° C / min. Next, the sample was heated and measured at a temperature rising rate of 10 ° C./min. The glass transition temperature is defined as the temperature at the intersection of the base line extension below the maximum peak temperature of endotherm and the tangent line indicating the maximum slope from the peak rising portion to the peak apex.

[Acid value of the resin]
Measured by the method of JIS K0070. However, only the measurement solvent is 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)).

[Specific surface area of carbon fine particles and carbon black using lignin as a raw material]
Using “Micrometrics FlowSorb III” (manufactured by Shimadzu Corporation), the BET specific surface area is measured under the following conditions.
・ Sample amount: 0.01 ~ 0.03g
・ Deaeration condition: 40 ℃, 10 minutes ・ Adsorption gas: Nitrogen gas

[Volume median particle size of carbon fine particles and carbon black using lignin as raw material]
Measuring machine: Laser diffraction / scattering particle size measuring device “Mastersizer 2000” (Malvern)
Measurement method: 10 mg of a measurement sample is added to 30 ml of Isopar G (manufactured by ExxonMobil Co., Ltd.) and dispersed for 1 minute with an ultrasonic disperser to prepare a sample dispersion. After introducing Isopar G into the measurement cell, add the sample dispersion, and adjust the volume under the conditions of a particle refractive index of 1.58 (imaginary part 0.1) and a dispersion medium refractive index of 1.42 at a concentration at which the scattering intensity is 5-15%. The median particle size (D ₅₀ ) is measured.

[Melting point of release agent]
Using a differential scanning calorimeter “DSC Q20” (manufactured by TA Instruments Japan), 0.01 to 0.02 g of sample is weighed into an aluminum pan and heated to 200 ° C. at a heating rate of 10 ° C./min. Then, the temperature is cooled to −10 ° C. at a temperature lowering rate of 5 ° C./min. Next, the sample is heated to 180 ° C. at a heating rate of 10 ° C./min and measured. The highest endothermic peak temperature observed from the melting endothermic curve obtained there is taken as the melting point of the wax.

[Number average particle diameter of external additives]
The particle size (average value of major axis and minor axis) of 500 particles is measured from a scanning electron microscope (SEM) photograph, and the average value is taken as the number average particle size.

[Volume-median particle size of toner]
Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 100μm
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) is dissolved in the electrolyte so as to have a concentration of 5% by mass.
Dispersion conditions: 10 mg of a measurement sample was added to 5 ml of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, then 25 ml of the electrolyte was added, and further dispersed for 1 minute with an ultrasonic disperser. Prepare sample dispersion.
Measurement conditions: The sample dispersion is added to 100 ml of the electrolytic solution so that the particle size of 30,000 particles can be measured in 20 seconds, and 30,000 particles are measured. Determine the median particle size (D ₅₀ ).

Resin Production Example 1 [Resin A, B]
The raw material monomers and esterification catalyst excluding trimellitic anhydride shown in Table 1 were mixed in a 5 L volume equipped with a nitrogen introduction tube, a dehydration tube equipped with a fractionation tube through which hot water of 98 ° C was passed, a stirrer and a thermocouple. The mixture was placed in a four-necked flask and heated from room temperature to 180 ° C. over 2 hours in a nitrogen atmosphere, and then heated from 180 ° C. to 210 ° C. at 10 ° C./hr. Thereafter, the reaction was continued at 210 ° C. until the reaction rate reached 90%. Trimellitic anhydride was added, reacted at 210 ° C. and normal pressure (101.3 kPa) for 1 hour, and then reacted at 20 kPa until the desired softening point was reached, thereby obtaining a polyester. Table 1 shows the physical properties of the obtained polyester. The reaction rate means a value of the amount of produced reaction water / theoretical product water amount × 100.

Resin Production Example 2 [Resin C]
The raw material monomers and esterification catalyst excluding trimellitic anhydride shown in Table 1 were placed in a 5 L four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. After raising the temperature to 2 ° C. over 2 hours, the temperature was raised from 200 ° C. to 230 ° C. at 10 ° C./hr. Thereafter, the reaction was continued at 230 ° C. until the reaction rate reached 90%. Trimellitic anhydride was added and reacted at 210 ° C. and 20 kPa until the desired softening point was reached to obtain a polyester. Table 1 shows the physical properties of the obtained polyester.

Resin Production Example 3 [Resin D]
1000 g of xylene was placed in a 5 L four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple, and stirred at 125 ° C. in a nitrogen atmosphere. The mixture was added dropwise from the dropping funnel over 2 hours. Furthermore, after maintaining at 125 ° C. for 1 hour, refluxing was performed at 150 ° C. for 1 hour. Thereafter, the reaction system was kept at 200 ° C. and 8.0 kPa, and xylene was removed over 2 hours to obtain a styrene acrylic resin. Table 2 shows the physical properties of the obtained styrene acrylic resin.

Table 3 shows the volume median particle size (D ₅₀ ) and specific surface area of carbon fine particles, carbon black, which are used in the examples and comparative examples described later, as raw materials.

Examples 1-4 and Comparative Examples 1-6 (Examples 3 and 4 are reference examples)
The specified amount of binder resin, colorant, negative charge control agent “Bontron E-304” (manufactured by Orient Chemical Co., Ltd.) 0.5 parts by mass, mold release agent “WAX-C1” (manufactured by Hiroyuki Kato) And 2.0 parts by weight of Carnauba wax (melting point: 84 ° C.) were mixed with a Henschel mixer for 1 minute. The resulting mixture was rotated in the same direction using a twin-screw extruder “PCM-30” (Ikegai Tekko Co., Ltd., shaft diameter 2.9 cm, shaft cross section 7.06 cm ² ) at a barrel setting temperature of 100 ° C. Kneading was performed at a feed rate of 10 kg / hr at several 200 r / min (shaft rotation peripheral speed 0.30 m / sec), and the kneaded discharge was immediately cooled to 25 ° C. while forming a sheet.

The obtained sheet was coarsely pulverized to 1.0 mm or less with a hammer mill (manufactured by Hosokawa Micron Corporation). The resulting coarsely pulverized product was crushed with a collision plate jet mill IDS-2 type (manufactured by Nippon Pneumatic Co., Ltd.) under the condition of a coarsely pulverized product supply rate of 4.0 kg / hr. Pulverization was carried out by adjusting the pulverization pressure so that (D ₅₀ ) was 6.5 μm. Table 4 shows the results of the grinding pressure at this time.

Thereafter, the toner was classified with a DSX-2 airflow classifier (manufactured by Nippon Pneumatic Co., Ltd.) to obtain toner base particles having a volume median particle size (D ₅₀ ) of 7.0 μm.

  The pulverization classification yield was calculated by the following formula (1) and used as an index of productivity. The higher the value, the better the productivity. The results are shown in Table 4.

[Crush classification yield] = ([Amount of toner base particles obtained] / [Total amount of coarsely pulverized charged product)] × 100 (1)

  500 g of the obtained toner mother particles and 10 g of hydrophobic silica “R972” (manufactured by Nippon Aerosil Co., Ltd., number average particle size: 16 nm) are charged into a 5 L Henschel mixer (manufactured by Nippon Coke Industries, Ltd.), and the rotational speed is 3700 r / min. The mixture was stirred for 180 seconds and classified with a sieve having an opening of 100 μm to remove the coarse powder, thereby obtaining a toner.

Test Example 1 [low temperature fixability]
The printer “MicroLine 5400” (Oki Data Co., Ltd.), modified so that unfixed images can be taken, was filled with toner, and 3 × 4 cm square solid images were fixed. With an external fixing device that modifies the oil-less fixing type "MicroLine 3010" (manufactured by Oki Data Co., Ltd.) (a device in which the fixing roll rotation speed is set to 188 mm / sec and the fixing roll temperature in the fixing device is variable). The fixing image was fixed at each temperature while increasing the temperature of the fixing roll from 100 ° C. to 230 ° C. by 5 ° C. to obtain a fixed image. The image obtained at each fixing temperature is rubbed 5 times with a sand eraser (Part No. LION ER502R) applied with a load of 500 g, and the image density ratio before and after rubbing ([image density after rubbing / image density before rubbing] × 100 ) First exceeds 90% as the minimum fixing temperature, and is used as an index of low-temperature fixing property. The smaller the value, the better the low-temperature fixability. The results are shown in Table 4.

Test Example 2 [Heat resistant storage stability]
4 g of toner was placed in a 20 ml polybin, and the polybin was opened, placed in a constant temperature and humidity chamber at 55 ° C. and 80% relative humidity, and stored for 48 hours. The degree of aggregation of the toner after standing was measured as follows and used as an index of heat resistant storage stability. The smaller this value, the better the heat resistant storage stability. The results are shown in Table 4.

[Degree of aggregation]
The degree of aggregation is measured using a powder tester (manufactured by Hosokawa Micron).
Three different sieve sieves are set in the order of 150 μm in the upper stage, 75 μm in the middle stage, and 45 μm in the lower stage, and 4 g of the toner is placed on the top and vibrated for 60 seconds with a vibration width of 1 mm. After the vibration, the amount of toner remaining on the sieve is measured, and the degree of aggregation is calculated using the following formula.

From the above results, it can be seen that the toners of Examples 1 to 4 are superior in heat-resistant storage stability while maintaining low-temperature fixability as compared with Comparative Examples 1 to 6. Moreover, it turns out that it is excellent also in productivity.
When Example 1 containing polyester having the same composition as the binder resin and Comparative Example 1 are compared, Example 1 containing carbon fine particles using lignin as a raw material has a pulverization pressure of 0.34 MPa and a yield of 93%. On the other hand, in Comparative Example 1 containing carbon black, the pulverization pressure was 0.50 MPa and the yield was 71%. In Example 1, the pulverization was performed at a pressure lower by 0.16 MPa, and the yield was improved by 22%. Similarly, when Example 2 and Comparative Example 2 and Example 3 and Comparative Example 3 are compared, the example containing carbon fine particles using lignin as a raw material is the comparative example containing carbon black. The yield is good at lower crushing pressure. On the other hand, when Comparative Examples 4 and 5 containing styrene acrylic resin as a binder resin are compared, in Comparative Example 4 containing carbon fine particles using lignin as a raw material, the crushing pressure is 0.34 MPa, and the yield is 63%. In Comparative Example 5 containing carbon black, the pulverization pressure is 0.40 MPa and the yield is 59%. Although the pulverization can be performed at a low pulverization pressure, the yield is low and the yield is due to the inclusion of carbon fine particles using lignin as a raw material. It can be seen that the improvement is small.

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

Claims (8)

Step 1: A step of obtaining a resin mixture by melt-kneading a binder resin containing polyester and carbon fine particles using lignin as a raw material, and Step 2: a step of pulverizing and classifying the resin mixture obtained in Step 1 A method for producing a toner for developing an electrostatic charge image , wherein the polyester comprises an alcohol component containing an aliphatic diol having 3 or 4 carbon atoms having a hydroxy group bonded to a secondary carbon atom, and a carboxylic acid component; A method for producing a toner for developing an electrostatic charge image, comprising a polyester obtained by polycondensation of a toner .   2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the volume median particle size of the carbon fine particles using lignin as a raw material in step 1 is 1.0 μm or more and 50 μm or less.   The method for producing a toner for developing an electrostatic charge image according to claim 1 or 2, wherein the content of the carbon fine particles using lignin as a raw material is 1 part by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the binder resin. The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 3, wherein the specific surface area of the carbon fine particles using lignin as a raw material is ² to 1000 m ² / g. The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 4 , wherein the aliphatic diol having 3 or 4 carbon atoms having a hydroxy group bonded to a secondary carbon atom is 1,2-propanediol. . The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 5 , wherein the content of the polyester in the binder resin is 80% by mass or more. The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 6 , wherein in step 2, pulverization is performed using a collision plate jet mill pulverizer. The method for producing a toner for developing an electrostatic charge image according to claim 7 , wherein the pulverization pressure at the time of pulverization is 0.20 MPa or more and 0.45 MPa or less.