JP2011002592A - Electrophotographic toner and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner which is free of the problems of proper pulverizability, storage stability, fixability and odor even when a low molecular weight biodegradable resin subjected to hydrolysis treatment is used as a binder resin, and to provide a method for manufacturing the same.SOLUTION: The electrophotographic toner is obtained by adding an acid value adjuster to raw materials including at least a polylactic acid-based resin subjected to hydrolysis treatment so that it becomes a number average molecular weight of ≤20,000 as a binder resin and a colorant and carrying out melting, kneading, pulverization and classification, wherein the amount of the acid value adjuster used is set so that the acid value of the resulting toner is adjusted to be ≤10.

Description

  The present invention relates to a toner and a manufacturing method thereof, and more particularly to an electrophotographic toner using a biodegradable resin as a binder resin and a manufacturing method thereof.

  Image formation by electrophotography is performed by developing and visualizing an electrostatic image with toner, transferring the obtained toner image onto a sheet, and then fixing it with heat and pressure. As the toner used for such image formation, a toner prepared by melting and kneading a mixture obtained by blending a binder resin with a colorant, a charge control agent, and the like, and adjusting the particle size distribution to a predetermined particle size distribution is used.

  Conventionally, petroleum-derived resins such as styrene / acrylic resins and polyester resins have been used as binder resins. However, in recent years, in consideration of the environment, a method has been proposed in which a biodegradable resin that has a low environmental impact during disposal is used as a binder resin for toner.

  One of the most promising resins as a biodegradable resin is polylactic acid. However, general-purpose polylactic acid is a crystalline polyester having a melting point of about 170 ° C., a glass transition point of about 60 ° C., and a number average molecular weight of about 1 to 150,000, and the general-purpose polylactic acid is used as a toner resin as it is. There are problems that it is hard and has poor grindability and has a high softening temperature and is not suitable for low-temperature fixing.

  In order to solve such a problem, proposals have been made to add a large amount of plant wax to polylactic acid (see, for example, Patent Document 1). However, in this proposal, it is possible to lower the softening temperature of the toner by adding a large amount of wax, but the toner easily aggregates due to the wax component, so that the productivity due to the lowering of the classification efficiency deteriorates. As the toner fluidity deteriorates, problems such as inferior toner transportability in the developing device occur.

  There is also a proposal of blending a terpene phenol copolymer and a specific wax into a polylactic acid-based biodegradable resin (see, for example, Patent Document 2). In this proposal, blending a terpene phenol copolymer that has low toughness of polylactic acid and low resin strength but is effective for low-temperature fixability provides good low-temperature fixability and grindability without sacrificing durability. It is said that both can be achieved.

  However, the blending amount of the polylactic acid-based biodegradable resin is limited to about 30% by weight. If the blending amount is further increased, the grindability is deteriorated and it becomes difficult to prepare a toner. Also, the melt viscosity becomes high, and the low-temperature fixability deteriorates.

  Patent Document 3 describes that a polylactic acid-based biodegradable resin can be used as a fine powder in a resin for toner, but in view of its molecular weight, the particle size of 10 μm or less required by the toner is obtained. It is extremely difficult to grind.

  Therefore, the applicant of the present application has proposed to improve the grindability and fixability by controlling the molecular weight of the polylactic acid used to the low molecular weight side, but the low molecular weight polylactic acid has an increased number of terminal carboxyl groups. Further problems have been confirmed, such as deterioration of long-term storage due to the effects of residual monomers and the occurrence of a unique odor during fixing. Therefore, the range on the low molecular weight side that can be used and selected was narrow.

  As described above, there are many problems in using a biodegradable resin as a main component of the binder resin of the toner, and even when a part of the biodegradable resin is replaced, the blending amount is limited, while maintaining good characteristics. Therefore, it is desired that more biodegradable resin can be blended as a binder resin for toner.

Japanese Patent No. 2597452 Japanese Patent No. 3779221 JP 2007-197602 A

  The present invention has been made under the circumstances as described above, and even when a biodegradable resin having a low molecular weight by hydrolysis treatment is used as a binder resin, good grindability, storage stability, fixing An object of the present invention is to provide an electrophotographic toner free from problems of property and odor and a method for producing the same.

  In order to solve the above problems, the present inventors have conducted intensive research. As a result, when using a hydrolyzed low molecular weight biodegradable resin as a binder resin, the acid value of the biodegradable resin is adjusted. As a result, it has been found that a toner having good grindability and fixability and excellent storage stability and odor can be obtained.

  That is, according to the first aspect of the present invention, an acid value adjusting agent is added to a raw material containing at least a biodegradable resin hydrolyzed to a predetermined low molecular weight as a binder resin, and a colorant. An electrophotographic toner obtained by pulverization and classification, which is obtained by adjusting the acid value to 10 or less based on the acid value adjusting agent, is provided.

  The second aspect of the present invention provides a kneaded product by melting and kneading a raw material mixture containing a biodegradable resin hydrolyzed to a predetermined low molecular weight, a colorant, and an acid value adjusting agent. A melting / kneading step to be obtained, and a pulverizing / classifying step for pulverizing and classifying the kneaded product, and the amount of the acid value adjusting agent used is set to adjust the acid value of the obtained toner to 10 or less. An electrophotographic toner manufacturing method is provided.

  In the third aspect of the present invention, a kneaded product is obtained by kneading a raw material mixture containing a biodegradable resin hydrolyzed to a predetermined low molecular weight, a colorant, and an acid value adjusting agent while melting. A melting / kneading step to be obtained, and a pulverizing / classifying step for pulverizing and classifying the kneaded product, and the amount of the acid value adjusting agent used is set to adjust the acid value of the obtained toner to 10 or less. A method for adjusting the acid value of an electrophotographic toner is provided.

  In the electrophotographic toner, the electrophotographic toner manufacturing method, and the electrophotographic toner acid value adjusting method as described above, the biodegradable resin is a polylactic acid resin, and the predetermined low molecular weight is 20 in terms of a number average molecular weight. , 000 or less.

  According to the present invention, there is provided an electrophotographic toner that has good crushability and fixability and is excellent in terms of storage stability and odor despite containing a low molecular weight biodegradable resin as a binder resin.

Hereinafter, various embodiments of the present invention will be described.
The electrophotographic toner according to the first embodiment of the present invention is obtained by adding an acid value adjusting agent to a raw material containing at least a biodegradable resin hydrolyzed to a predetermined low molecular weight as a binder resin and a colorant. Obtained by melting, kneading, grinding, and classification.

The biodegradable resin used in the present invention is a polylactic acid resin and has the following structural formula.

  Here, so-called polylactic acid is a polymer in which lactic acid is bonded by an ester bond, and is a resin that has attracted attention in recent years. In other words, in nature, enzymes that cleave ester bonds (esterases) are widely distributed, so polylactic acid is gradually decomposed by such enzymes in the environment and converted into lactic acid as a monomer. And eventually carbon dioxide and water.

  The method for producing polylactic acid used in the present invention is not particularly limited, and a conventionally known method can be used. Fermenting starch such as corn as a raw material to obtain lactic acid, followed by dehydration condensation directly from lactic acid monomer, and synthesis by ring-opening polymerization in the presence of a catalyst via cyclic dimer lactide from lactic acid is there. In recent years, Nature Works has sold polylactic acid resin commercially.

  In addition, commercially available polylactic acid is synthesized by a ring-opening polymerization method capable of obtaining a higher molecular weight in order to improve heat resistance, and the number-average molecular weight is mainly 100,000 or more. . Such a high molecular weight polylactic acid has a too high softening point and poor fixability, and also has poor grindability. Therefore, it is necessary to hydrolyze the resin and reduce the molecular weight.

  The specific low molecular weight polylactic acid used in the present invention can be arbitrarily adjusted by varying the reaction conditions during the polymerization, but for example, by utilizing the hydrolysis characteristics of polylactic acid, A commercially available polylactic acid having a reduced molecular weight can be suitably used.

  That is, the polylactic acid used in the present invention is hydrolyzed to a number average molecular weight of 20,000 or less.

  As mentioned above, low molecular weight polylactic acid tends to deteriorate long-term storage due to the increase in carboxyl groups at the end and the effects of residual monomers, and to generate a unique resin odor during fixing, as described above. Odor is a big problem and a problem when used as a resin for toner.

  Therefore, in the electrophotographic toner according to the first embodiment of the present invention, when using hydrolyzed low molecular weight polylactic acid as a binder resin, the acid value is adjusted to 10 or less by adding an acid value adjusting agent. I decided to adjust.

  Thus, by reducing the molecular weight, polylactic acid, which has been difficult to pulverize conventionally, can be pulverized relatively easily, and polylactic acid can be added at a high concentration. In addition, polylactic acid whose molecular weight is too low can be used by adding an acid value adjusting agent.

  In the electrophotographic toner manufacturing method according to the second embodiment of the present invention and the acid value adjusting method according to the third embodiment, the following conventionally known methods can be employed.

  For example, after mixing a binder resin, a colorant, an acid value adjusting agent, and raw materials including other additives as necessary, kneaded with a kneader such as a biaxial kneader, a pressure kneader, or an open roll, and kneaded Get. After cooling this kneaded material, the toner can be obtained by pulverizing with a pulverizer such as a jet mill and classifying with an air classifier.

  Here, the particle size of the toner is not particularly limited, but is usually adjusted to be 5 to 10 μm. An external additive can be added to the toner thus obtained in order to improve fluidity, adjust chargeability, and improve durability.

  As the external additive, inorganic fine particles are generally used, and examples thereof include silica, titania, alumina, etc. Among them, silica subjected to hydrophobic treatment (commercially available from Nippon Aerosil Co., Ltd., CABOT Co., Ltd.) is preferable. The particle diameter of the inorganic fine particles is preferably 7 to 40 nm as the primary particle diameter, and two or more kinds may be mixed for improving the function.

  As the colorant used in the electrophotographic toner of this embodiment, a conventionally known colorant can be used. For example, as a black colorant, carbon black and as a blue colorant, C.I. I. Pigment 15: 3, and red colorants include C.I. I. Pigment 57: 1, 122, 269, and yellow colorants include C.I. I. Pigment 74, 180, 185 and the like. In consideration of the influence on the environment which is one of the objects of the present invention, a single colorant having high safety is preferable.

  The content of these colorants is preferably 1 to 10% by mass with respect to the whole toner. The colorant may be used in the form of a masterbatch in which a resin and a colorant are dispersed in high concentration in advance.

  A conventionally known release agent can be added to the toner according to the exemplary embodiment as necessary. Examples of such release agents include olefinic waxes such as polypropylene wax, polyethylene wax, and Fischer-Tropsch wax, natural waxes such as carnauba wax, rice wax, and scale insect wax, and synthetic ester waxes.

  In order to improve low-temperature fixability and high-speed printing performance, a release agent having a relatively low melting point of about 60 to 100 ° C. is preferable, and specifically, carnauba wax and synthetic ester wax are preferable. In consideration of environmental impact, natural product carnauba wax is more preferable. The compounding amount of the release agent is preferably 1 to 10% by mass with respect to the whole toner.

  A conventionally known charge control agent of positive charge or negative charge can be added to the toner according to the exemplary embodiment as necessary. Examples of the positive charge control agent include quaternary ammonium salts, resins containing amino groups, and the like. Examples of the negative charge control agent include metal complexes of salicylic acid, metal complexes of benzylic acid, and calixarene type phenolic compounds. Examples include condensates and resins containing carboxyl groups. The blending amount of the charge control agent is preferably 0.1 to 5% by mass with respect to the whole toner.

Examples of the present invention and comparative examples are shown below, and the present invention will be described more specifically.
1. Method for measuring physical properties of components used in Examples and Comparative Examples (Measurement of toner particle diameter)
Equipment: Multisizer II (manufactured by Coulter, Inc.)
Sample: A small amount of sample, purified water, and a surfactant were placed in a beaker and dispersed with an ultrasonic cleaner.
Measurement: The aperture was 100 μm, the count was 50,000, and the volume average particle size was obtained.

(Measurement of molecular weight)
Equipment: GPC (manufactured by Shimadzu Corporation), detector RI
The molecular weight Mn is a number average molecular weight measured by GPC (gel permeation chromatography) using a calibration curve prepared with a polystyrene sample having a known molecular weight as a standard.

2. Production of polylactic acid used in Examples and Comparative Examples (Production process of low molecular weight polylactic acid)
First, polylactic acid (manufactured by Kaisho Biochemical Co., Ltd .: REVODE101B, molecular weight (Mn = 120,000)) was placed in a constant temperature and humidity chamber set at a temperature of 80 ° C. and a humidity of 80% RH for hydrolysis. It was rinsed with water and dried in a hot air dryer (60 ° C. setting) for 1 hour.

  The hydrolysis treatment time was varied as shown in Table 1 below (Reference Examples 1 to 8) to produce polylactic acid having different molecular weights (resin Nos. 1 to 8).

  Next, toners of Reference Examples 1 to 8 in Table 1 were prepared using polylactic acid (resin Nos. 1 to 8) having different molecular weights related to the hydrolysis treatment as binder resins.

  That is, first, each component of the following blending amount was put into a Henschel mixer (standard feather mounted, manufactured by Mitsui Mining Co., Ltd.) and mixed.

Binder resin: Polylactic acid of resin No 1 to 100 100 parts by mass Colorant: Carbon black (MOGUL L manufactured by CABOT Co., Ltd.) 4 parts by mass Release agent: Carnauba wax No. 1 powder (manufactured by Nippon Wax Co., Ltd.) 3 parts by mass Charge control agent: “LR-147” (manufactured by Nippon Carlit Co., Ltd.) 1 part by mass After melt-kneading the obtained mixed powder with a twin screw extruder (screw diameter 43 mm, L / D = 34) The melt-kneaded product was stretched and cooled by setting the circulating water of the rolling roll to 10 ° C., and the cooled kneaded product was coarsely crushed with Rotoplex (manufactured by Hosokawa Micron Corporation, 2 mm screen). After that, the particles are pulverized and classified with a collision type pulverizer (Nippon Pneumatic Industry IDS-2) and a wind classifier (Nippon Pneumatic Industry DSX-2) so that the average particle diameter of the toner becomes 9.0 μm. Got.

  As an external additive, 2 parts by mass of “RY200” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica, primary particle size of 12 nm) is added to 100 parts by mass of the obtained fine particles, and a Henschel mixer (with stirring reinforcing wings, Mitsui) is added. (Mine Co., Ltd.) for 3 minutes with stirring to obtain a toner.

  The toners of Reference Examples 1 to 8 obtained as described above were tested, evaluated and confirmed by the following test methods for grindability, storage stability, fixability, odor and acid value.

(Test 1-grindability)
When pulverizing and classifying the kneaded coarsely pulverized product in the pulverization / classification step, the determination is made based on the yield (mass%) of the particles serving as the toner base. In reality, there is no problem if the yield is 70% or more. At this time, the pulverizing conditions are adjusted so that the volume average particle diameter of the toner is 9 μm, the number ratio of 3 μm or less as fine powder is 5% or less, and the volume ratio of 16 μm or more as coarse powder is 3% or less.

○: Yield 65% or more.
Δ: Yield 50% or more.
X: Yield less than 50%.

(Test 2-Storage stability)
The toner is put in a 50 cc beaker up to a 30 cc scale (about 15 g), and evaluated after being left in a constant temperature bath at 40 ° C. and 90% for 30 days. The value when the wire enters 15 mm with respect to the sample after standing for 30 days is measured using a spring balance.

○: Less than 0.5N ×: 0.5N or more (evaluation criteria)
-: Cannot be converted into toner.

(Test 3-Fixability)
Non-magnetic one-component developing device “Casio Page Presto N-5” (manufactured by Casio Computer Co., Ltd .: color printer 29 sheets per minute (A4 horizontal) machine, process speed 129 mm / sec) so that the temperature of the fixing part can be varied. Remodel and use as a fixing tester. After obtaining an unfixed image with this apparatus, the fixing temperature was varied in the range of 100 to 200 ° C. every 10 ° C., and the unfixed image was passed through a fixing device. The cold offset, hot offset, and peeled nail trace of the image sample were visually evaluated, and a non-offset area was obtained and evaluated. The process speed was 129.3 mm / sec, and the paper was XEROX P paper A4 size (weight 64 g / m ² ). The oil supply roll of the fixing device was removed.

○: The non-offset region is 20 ° C. or higher.
X: A non-offset area | region is 10 degrees C or less.
-: Cannot be converted into toner.

(Test 4-Odor)
2.0 g of toner is put in an oven at 180 ° C. in a sealed state, taken out after 30 minutes, and smelled and evaluated.

○: There is no smell.
X: There is a peculiar sweet smell.
-: Cannot be converted into toner.

(Test 5-Acid value (according to JIS: K-0070))
The sample was weighed into a beaker, chloroform was added, and the mixture was shaken until the sample was completely dissolved. This solution was subjected to potentiometric titration with a potassium hydroxide ethanol standard solution (0.1 mol / L) using a potentiometric titrator (AT-500N: Kyoto Electronics Industry Co., Ltd.), and determined by the following formula (1).

Acid value = 5.611 × A × f / B (1)
A: 0.1 mol / L potassium hydroxide ethanol standard solution used for titration (ml)
f: Factor of 0.1 mol / L potassium hydroxide ethanol standard solution B: Sample collection amount (g)

  From the results shown in Table 1 above, the following is found. That is, as the molecular weight of commercially available polylactic acid is lowered by hydrolysis treatment (Reference Examples 2 to 7), the acid value increases (Reference Examples 1 to 3 are acid values measured only for the resin). The pulverizability was also improved. In Reference Examples 4 and 5, the pulverizability reached a practical level of yield of 50% or more, and generally good results were obtained in general evaluation.

  In Reference Examples 6 and 7, which had a lower molecular weight than Reference Examples 4 and 5, the grindability was further improved, but storage stability and odor problems occurred.

  Incidentally, when Reference Examples 4 and 5 were compared with Reference Examples 6 and 7, in Reference Examples 4 and 5, the acid value was estimated to be approximately 10 or less.

  In addition, in Reference Example 1 of a commercial product and Reference Examples 2 and 3 in which the molecular weight was adjusted only to a value exceeding about 50,000, the grindability was poor and could not be used. On the other hand, in Reference Example 8 in which the molecular weight was reduced to about 5,000 by hydrolysis, the molecular weight of polylactic acid was too low, and fusion occurred in the pulverizer during toner pulverization, so that pulverization could be continued. There wasn't.

  Therefore, from the viewpoint of grindability, it was confirmed that toner could be formed by using polylactic acid having a molecular weight adjusted to a range of 5,000 to 50,000 by hydrolysis. However, with the toner production conditions shown in Table 1, it is difficult to make toner only in the low molecular weight range of Reference Examples 4 and 5, and the degree of freedom in production and design is low.

  Therefore, the present inventors inferred that the acid value is related to the difference in evaluation between Reference Examples 4 and 5 and Reference Examples 6 and 7, and by adjusting the acid value for Reference Examples 6 and 7, the storage stability was improved. The present inventors have studied whether or not odor can be improved and have achieved the present invention.

3. Production of electrophotographic toners of examples and comparative examples (Example 1)
Each component of the following blending amount was put into a Henschel mixer (standard feather mounted, manufactured by Mitsui Mining Co., Ltd.) and mixed.

Binder resin: Polylactic acid of resin No 6 (molecular weight 20,000) 100 parts by mass Colorant: Carbon black (MOGUL L manufactured by CABOT Co., Ltd.) 4 parts by mass Release agent: Carnauba wax No. 1 powder (Japanese wax ( 3 parts by mass Charge control agent: “LR-147” (manufactured by Nippon Carlit Co., Ltd.) 1 part by mass Acid value adjusting agent: “LA-1” (Carbodilite manufactured by Nisshinbo Industries, Ltd.) 1 part by mass The resulting mixed powder was melt-kneaded with a twin-screw extruder (screw diameter 43 mm, L / D = 34), and then the melt-kneaded product was stretched and cooled by setting the circulating water of the rolling roll to 10 ° C. The kneaded material after cooling was roughly crushed with a Rotoplex (manufactured by Hosokawa Micron Corporation, 2 mm screen). After that, the particles are pulverized and classified with a collision type pulverizer (Nippon Pneumatic Industry IDS-2) and a wind classifier (Nippon Pneumatic Industry DSX-2) so that the average particle diameter of the toner becomes 9.0 μm. Got.

  As an external additive, 2 parts by mass of “RY200” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica, primary particle size of 12 nm) is added to 100 parts by mass of the obtained fine particles, and a Henschel mixer (with stirring reinforcing wings, Mitsui) is added. (Mine Co., Ltd.) for 3 minutes with stirring to obtain a toner.

(Examples 2 to 4)
Toner was obtained in the same manner as in Example 1 except that the acid value adjusting agent: “LA-1” was set to various values shown in Table 2 below.

(Examples 5-7)
Acid value adjusting agent: “LA-1” to “UG-4040” (acrylic polymer manufactured by Toagosei Co., Ltd.)
And a toner was obtained in the same manner as in Example 1 except that various values shown in Table 2 below were set.

(Examples 8 to 10)
Instead of using polylactic acid (molecular weight 10,000) of resin No 7 as the binder resin, the acid value adjusting agent: “LA-1” was set to various values shown in Table 2 below. A toner was obtained in the same manner as in Example 1.

(Examples 11 to 12)
Instead of using resin No. 7 polylactic acid (molecular weight 10,000) as the binder resin, the acid value adjusting agent: “LA-1” is replaced with “UG-4040” (acrylic polymer manufactured by Toagosei Co., Ltd.). A toner was obtained in the same manner as in Example 1 except that the values shown in Table 2 below were set.

(Comparative Example 2)
A toner was obtained in the same manner as in Example 5 except that the acid value adjusting agent: “UG-4040” was set to 1 blend (part).

(Comparative Example 4)
Toner was obtained in the same manner as in Example 8 except that the acid value adjusting agent: “LA-1” was set to 1 blend (part).

(Comparative Examples 5 and 6)
Toner was obtained in the same manner as in Example 11 except that the acid value adjusting agent: “UG-4040” was set to the value shown in Table 2 below.

With respect to Examples 1 to 12 and Comparative Examples 2 and 4 to 6 obtained as described above, the grindability, storage stability, fixability, odor and acid value of the toner were tested and evaluated by the above test methods. .
The above results are shown in Table 2 below.

From Table 2 above, the following is clear.
That is, Comparative Example 1 (reprinted above Reference Example 6) was excellent in grindability and fixability, but had problems with storage stability and odor, whereas acid value adjuster LA-1 was 1-10. All of the toners according to Examples 1 to 4 in which the acid value was adjusted to 10 or less in addition to the blending (parts) showed excellent results in all the characteristics of pulverization property, storage stability, fixing property and odor.

  Further, Comparative Example 3 (reprinted above Reference Example 7) was excellent in grindability and fixability, but had problems with storage stability and odor. All of the toners according to Examples 1 to 4 in which the acid value was adjusted to 10 or less in addition to the blending (parts) showed excellent results in all the characteristics of pulverization property, storage stability, fixing property and odor.

  In contrast, in Comparative Example 4, although 1 part (part) of the acid value adjusting agent LA-1 was added, the acid value was 14, so the odor was not improved.

  From these facts, it can be seen that polylactic acid having a number average molecular weight reduced to 20,000 or less by hydrolysis treatment can be used as a toner by appropriately adding an acid value adjusting agent. In this case, although the addition amount of the acid value adjusting agent varies depending on the molecular weight of the polylactic acid to be used, the addition amount may be an amount that adjusts the acid value to 10 or less.

  This can be said also from the Example which changed the acid value adjusting agent. That is, Examples 5 to 7 and Examples 11 and 12 in which the acid value was adjusted to 10 or less with respect to polylactic acid whose number average molecular weight was reduced to 20,000 or less using the acid value adjusting agent UG-4040. All of the toners related to the above showed excellent results in all the characteristics of pulverization property, storage stability, fixing property and odor. On the other hand, Comparative Example 2 and Comparative Examples 5 and 6 have an acid value of 13 or more, and the odor is not improved.

  Thus, according to the present invention, it is possible to produce a toner by adjusting the acid value of polylactic acid having a low molecular weight.

  In the above embodiment, the acid value adjusting agent has been described with carbodilite (LA-1) or acrylic polymer (UG-4040), but it is of course not limited to these as long as there is a reaction with a carboxyl group. .

  For example, as such an acid value adjusting agent, neutral to weakly basic diisocyanate, neutral to weakly basic diglycidyl ether, neutral to weakly basic acid anhydride, non-functional of Toa Gosei Co., Ltd. Solventless acrylic polymers such as the base polymer “UP-1150”, the OH group-containing polymer “UH-2170”, and the epoxy-containing polymer “UG-4035” can be exemplified.

  The present invention can be used for an electrophotographic toner containing a polylactic acid resin as a biodegradable resin as a binder resin.

Claims (6)

An electrophotographic toner obtained by melting, kneading, pulverizing, and classifying a raw material containing at least a biodegradable resin hydrolyzed to a predetermined low molecular weight as a binder resin and a colorant and adding an acid value adjusting agent. There,
An electrophotographic toner obtained by adjusting an acid value to 10 or less based on the acid value adjusting agent.   2. The electrophotographic toner according to claim 1, wherein the biodegradable resin is a polylactic acid resin, and the predetermined low molecular weight is 20,000 or less in terms of number average molecular weight.   A melting and kneading step for obtaining a kneaded product by melting and kneading a raw material mixture containing a biodegradable resin hydrolyzed to a predetermined low molecular weight, a colorant, and an acid value adjusting agent, and pulverizing the kneaded product A method for producing an electrophotographic toner, comprising a pulverizing / classifying step for classifying, and setting the amount of the acid value adjusting agent to adjust the acid value of the obtained toner to 10 or less.   4. The method for producing an electrophotographic toner according to claim 3, wherein the biodegradable resin is a polylactic acid resin, and the predetermined low molecular weight is 20,000 or less in terms of number average molecular weight.   A melting and kneading step for obtaining a kneaded product by melting and kneading a raw material mixture containing a biodegradable resin hydrolyzed to a predetermined low molecular weight, a colorant, and an acid value adjusting agent, and pulverizing the kneaded product A method for adjusting the acid value of an electrophotographic toner, comprising a pulverizing / classifying step for classifying the toner, and setting the amount of the acid value adjusting agent to adjust the acid value of the resulting toner to 10 or less.   6. The method for adjusting an acid value of an electrophotographic toner according to claim 5, wherein the biodegradable resin is a polylactic acid resin, and the predetermined low molecular weight is 20,000 or less in terms of number average molecular weight.