JPH07120975A - Electrophotographic toner and its production - Google Patents

Abstract

PURPOSE:To produce an electrophotographic toner with which the deinking is easily performed and the recycling of the used copying paper can be promoted and the waste disposal problem is avoided by using a specific lactic acid resin as the major resin component of the toner. CONSTITUTION:This toner contains as the binder resin a lactic acid resin represented by the formula H-(-O-CH(CH3)-CO-)n-OR. In the formula, R is hydrogen atom, an alkyl group, preferably alkyl group having 1 to 20 carbon atoms or an alkali or alkaline earth metal, and (n) is a 10 to 20,000, preferably 200 to 4000 integer. The lactic acid resin represented by this formula is produced by polymerizing the constituent monomer in the presence of at least one additive selected from a colorant, charge control agent and anti-offset agent. The process for polymerizing the constituent monomer of the lactic acid resin in the presence of at least one additive selected from among a colorant, charge control agent and anti-offset agent is also provided. This toner is provided with hydrolyzability and biodegradability due to the presence of the lactic acid resin represented by the formula.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic toner. More specifically, the current deinking system can be used as it is. It has hydrolyzable and biodegradable properties and is easy to deink,
In addition, the present invention relates to an electrophotographic toner that is easy to dispose of waste.

[0002]

2. Description of the Related Art In recent years, there has been an active movement worldwide to promote the use of waste paper from the viewpoints of both forest resource protection, global warming control, environmental protection and waste disposal. As a method for promoting the use of waste paper, there are methods such as improving the deinking pulp blending ratio in recycled paper and examining the deinking pulp blending method for high-quality paper and information industry paper. For this purpose, it is necessary to improve the quality of deinked pulp obtained from waste paper generated from printed matter such as newspapers and magazines by improving whiteness, deinking rate and dust removal rate. On the other hand, since electrophotographic copying machines and printers have become widespread, the amount of used copying paper to be discarded has been increasing. Therefore, attempts have been proposed to obtain deinked pulp from used copy paper. However, in copying paper, it is difficult to obtain high-quality deinked pulp by the conventional deinking treatment method, because the toner mainly composed of the colorant and the binder resin is firmly fixed on the surface of the paper. .

From the viewpoint of protecting the global environment, the safety of waste is also an important issue. Italy has been taxing 100 lira per non-degradable shopping bag since 1987 to solve the plastic waste problem. In addition, since 1991, legislation promulgated that shopping bags and bottles must be made of biodegradable materials. Other European countries and the US states are also considering legislation regarding restrictions on the use of plastics and conversion to degradable polymers. Under such circumstances, the development of biodegradable resins is being promoted, and there are considerable practical examples of medical materials. In the agricultural field, it has been put to practical use as multi-file, sustained-release pesticides, fertilizers, horticultural materials, etc. In the leisure field, it has been put to practical use in fishing lines, fishing gear, golf tees, and the like. Further, as a packaging material for daily necessities, some containers for daily life have been put to practical use.

As for the waste toner produced in the used copying paper or the electrophotographic process, a toner having no problem in disposal is required. Japanese Unexamined Patent Publication No. 4-179967 proposes a toner containing a specific polyester-based biodegradable binder resin. However, this toner has a problem that the deinking property is insufficient because it has a large hygroscopic property, the charging property is not stable, and it is insoluble in alkali. The conventional method for producing an electrophotographic toner is generally as follows. The binder resin, the colorant, the offset preventing agent, and other additives that are added as necessary, which are the constituent components of the toner, are premixed. The mixture is heated and kneaded in a state where the binder resin and the like are melted, and the obtained lump is pulverized to produce a toner having a required particle size. However, in this conventional manufacturing method, the dispersibility of various additives in the binder resin was poor during melt kneading. For this reason, it was necessary to set extremely strict conditions during melt-kneading. In addition, the obtained toner often has problems in practical physical properties such as toner charge uniformity and offset prevention property.

[0005]

SUMMARY OF THE INVENTION The present invention satisfies not only various characteristics as a toner, but also facilitates deinking in a conventional deinking process using an alkali so that used copying can be performed. An object of the present invention is to provide an electrophotographic toner that can promote the reuse of paper and can overcome the problem of environmental destruction due to waste toner, and a method for producing the toner.

[0006]

Means for Solving the Problems The present invention relates to compounds of formula (1) H - [- O -CH (CH 3) -CO-] n -OR (1) [ wherein, R represents a hydrogen atom, an alkyl group, Preferably, it represents an alkyl group having 1 to 20 carbon atoms, an alkali metal or an alkaline earth metal, and n represents an integer of 10 to 20,000, preferably 200 to 4000]. The present invention provides an electrophotographic toner characterized by being contained as. The invention further polymerized formula (1) is a component of electrophotographic toner H - [- O-CH ( CH 3) -CO-] n -OR (1) [ wherein, R represents a hydrogen atom , An alkyl group, an alkali metal or an alkaline earth metal, and n is an integer of 10 to 20,000], a colorant, a charge control agent, and an anti-offset agent. There is provided a method for producing an electrophotographic toner, comprising a step of polymerizing in the presence of at least one additive selected from

The inventors of the present invention have made intensive studies to make it easier to discard toner and recycle used copying paper. As a result, the lactic acid obtained by lactic acid fermentation of glucose,
If the lactic acid-based resin obtained by direct dehydration condensation or ring-opening polymerization of a cyclic dimer (lactide) of lactic acid is contained in the toner as a binder, it is possible to impart hydrolyzability and biodegradability to the toner. , It was found that this can achieve the above purpose.

The cyclic dimer (lactide) of lactic acid can be obtained by subjecting a lactic acid polycondensate obtained by concentrating an aqueous lactic acid solution to a heating reaction (140 to 200 ° C.) in the presence of a catalyst. Distilled, recrystallized and dried product is used as a raw material for ring-opening polymerization. As a catalyst used for ring-opening polymerization of lactide, tin compounds are preferably used. An extruder, a pressure kneader, a Banbury mixer, etc. are illustrated as an apparatus for producing a lactic acid resin. Examples of the lactic acid-based resin include "Lacty" (trade name) manufactured by Shimadzu Corporation. Lactic acid resin is
It is easily hydrolyzed by the presence of alkaline water. Therefore, there is an advantage that the toner containing the dye such as carbon black can be efficiently removed from the copied paper.

Examples of the colorant used in the present invention include carbon black, monoazo red pigment, disazo yellow pigment, quinacridone magenta pigment, anthraquinone dye and the like. Examples of the charge control agent include nigrosine dyes, quaternary ammonium salts, monoazo metal complex dyes, and the like. As the offset preventing agent, a polyolefin having a weight average molecular weight of about 1,000 to 45,000 can be preferably used. This polyolefin has an appropriate range because it is necessary to improve the dispersibility of the lactic acid monomer or dimer, or the lactic acid resin, and if the melting point is too high, the fusing temperature of the toner is increased. It is preferable to select and use from the molecular weight. A particularly preferred range is about 2000-600 by weight average molecular weight.
It is 0. These polyolefins also have a softening point of 1
It is preferable to select and use one in the range of 00 to 180 ° C, particularly preferably 130 to 160 ° C. Specific examples of such polyolefins include polyethylene, polypropylene, polybutylene and the like. Of these, polypropylene is particularly preferable.

In the present invention, the following can be further exemplified as the offset preventing agent that can be effectively used. Zinc salt of stearic acid, barium salt, lead salt, cobalt salt,
Fatty acid metal salts such as calcium salts and magnesium salts, olefinic acid zinc salts, manganese salts, iron salts and lead salts, palmitic acid zinc salts, cobalt salts and magnesium salts: higher fatty acids having 16 or more carbon atoms: carbon atoms Number 16 or higher higher alcohols: esters of polyhydric or monohydric alcohols: natural or synthetic paraffins: fatty acid esters or partially saponified products thereof: ethylene bis stearoyl amides: the above-mentioned offset preventing agent alone Alternatively, two or more kinds may be appropriately combined and used. The anti-offset agent is generally 0.1 per 100 parts by weight of the binder resin or the monomer constituting the binder resin.
10 to 10 parts by weight, preferably 0.5 to 5 parts by weight.

The electrophotographic toner of the present invention may contain other thermoplastic resin as a binder resin in addition to the lactic acid resin. Other thermoplastic resins are exemplified below. Polystyrene, polyacrylic acid ester, styrene-acrylic acid ester copolymer, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, phenol resin, epoxy resin, polyester resin and the like. When other thermoplastic resin is used together with the lactic acid resin as the binder resin, the mixing ratio of the other thermoplastic resin is 80% by weight or less, particularly 50% by weight or less, based on the entire binder resin. preferable. When the proportion of the other thermoplastic resin is more than 80% by weight, the binding strength of the other binding resin to the paper surface becomes too strong, and the deinking property is deteriorated. When used as a biodegradable toner, it is preferable not to mix other thermoplastic resins.

The electrophotographic toner of the present invention comprises a lactic acid resin as a binder, a colorant, a charge control agent, an anti-offset agent and other additives, and melt-kneading, followed by cooling and solidification. Obtained by crushing and classifying. More preferably, a lactic acid-based resin polymerized in the presence of at least one additive selected from a colorant, a charge control agent and an offset preventive agent, and if necessary, a colorant, a charge control agent and an offset preventive agent. It can be obtained by adding additives, melt-kneading, cooling, solidifying and pulverizing and classifying.

In the latter one of the above-mentioned production methods, the binder resin may contain additives such as a colorant, a charge control agent and an anti-offset agent in a very sufficiently uniformly dispersed state. There is an advantage that you can. This is because by polymerizing the monomer in a state where the additive is mixed with the monomer that gives the binder resin, the additive is mixed during the liquid state before the polymerization of the monomer is completed. Is. That is, when the monomer itself is in a liquid state (may be in a solution state), the additive can be dispersed in the monomer sufficiently uniformly. As a result, after the completion of the polymerization, the additive is sufficiently uniformly dispersed between the molecular chains of the resin.

When the colorant, especially carbon black, is uniformly dispersed in the binder resin, the volume resistivity of the toner is lowered and an electrophotographic toner exhibiting stable charging characteristics can be obtained. The charge control agent has the same effect as that of the colorant. When the offset preventing agent is uniformly dispersed in the binder resin, it is possible to obtain the electrophotographic toner for fixing the heating roller, which has practically effective non-offset properties. In order to impart fluidity to the electrophotographic toner of the present invention, a fluidizing agent such as hydrophobic silica or colloidal silica, magnetic powder or the like may be added.
These additives may be sprinkled on the surface of the toner particles before use. The electrophotographic toner of the present invention can be mixed with a carrier composed of iron powder, ferrite, granulated magnetite or the like and used as a two-component developer. When the magnetic substance is contained in the toner, it can be used as it is as a one-component developer without being mixed with a carrier.

A more detailed description will be given below based on embodiments.
In the following examples, parts and% mean parts by weight and% by weight, respectively, unless otherwise specified. Synthesis Example 1 L-lactide (manufactured by Shimadzu Corporation) 100 parts Lauryl alcohol 0.05 part Tin octylate (“Cosmos 29” manufactured by Gold Schmidt Co., Ltd., a catalyst for ring-opening polymerization) 0.2 parts Biaxial raw materials having the above composition It was supplied to the raw material supply section of the kneading extruder. Cylinder temperature 190 ℃, rotation 6 in the same direction
Nitrogen gas was supplied from the supply port at 0 rpm. The average residence time in the twin-screw kneader was 15 minutes. The obtained polymer was extruded from a nozzle having a diameter of 2 mm. After cooling and solidifying, the chips were cut to obtain lactic acid resin chips. The weight average molecular weight of the obtained chips was 100,000. In the formula (1), n is 1400 and R is a dodecyl group.

Example 1 100 parts of the lactic acid-based resin obtained in Synthesis Example 1 Polyolefin wax ("NP-105" manufactured by Mitsui Petrochemical Co., Ltd.) 2 parts Charge control agent ("NXVP434" manufactured by Hoechst) 2 parts Carbon black ( Mitsubishi Kasei's "MA-100") 6 parts The raw materials having the above composition are mixed by a super mixer, melt-kneaded by a twin-screw kneader, crushed by a jet mill, and then classified by a dry airflow classifier and averaged. Negatively charged toner particles having a particle diameter of 12 μm were obtained. Toner particles 100 obtained
And hydrophobic silica ("R972" manufactured by Nippon Aerosil Co., Ltd.)
Stir 0.3 parts for 1 minute using a Henschel mixer,
Hydrophobic silica was adhered to the toner particles to obtain an electrophotographic toner (A).

Example 2 In Example 1, the compounding amount of the lactic acid resin was 50 parts,
An electrophotographic toner (B) was prepared in the same manner as in Example 1 except that 50 parts of styrene / acrylic acid ester copolymer resin (“NC-6550” manufactured by Nippon Carbide Co., Ltd.) was added.

Comparative Example 1 The styrene / acrylic acid ester copolymer resin 100 used in Example 2 instead of the lactic acid resin in Example 1 was used.
An electrophotographic toner (C) was prepared in the same manner as in Example 1 except that parts were added.

Example 3 Lactic acid-based resin obtained in Synthesis Example 1 100 parts Polyolefin wax ("NP-105" manufactured by Mitsui Petrochemical Co., Ltd.) 2 parts Charge control agent ("Bontron S-34" manufactured by Orient Chemical Industry Co., Ltd.) 2 parts Ferrous tetroxide (average particle size 0.2 μm) 40 parts A raw material having the above composition was treated in the same manner as in Example 1 to prepare an electrophotographic toner (D).

Comparative Example 2 Example 1 was repeated except that a styrene / acrylic acid ester copolymer resin was used in place of the lactic acid resin in Example 3.
In the same manner as described above, an electrophotographic toner (E) was prepared.

Synthesis Example 2 L-lactide (manufactured by Shimadzu Corporation) 100 parts Lauryl alcohol 0.05 parts Tin octylate ("Goldschmitt" Cosmos 29 ", catalyst for ring-opening polymerization) 0.2 parts Carbon black (Mitsubishi Kasei) "MA-100" manufactured by Mfg. Co., Ltd.) 6 parts The raw material having the above composition was supplied to the raw material supply part of the twin-screw kneading extruder. Cylinder temperature 190 ℃, rotation 6 in the same direction
Nitrogen gas was supplied from the supply port at 0 rpm. The average residence time in the twin-screw kneader was 15 minutes. The obtained polymer was extruded from a nozzle having a diameter of 2 mm. After cooling and solidifying, the chips were cut to obtain lactic acid resin chips. The weight average molecular weight of the obtained chips was 110,000. In the formula (1), n is 1500 and R is a dodecyl group.

Example 4 Lactic acid resin obtained in Synthesis Example 2 106 parts Polyolefin wax ("NP-105" manufactured by Mitsui Petrochemical Co., Ltd.) 2 parts Charge control agent ("NXVP434" manufactured by Hoechst) 2 parts From the above composition These raw materials were mixed with a super mixer, melt-kneaded with a twin-screw kneader, pulverized with a jet mill, and then classified with a dry air stream classifier to obtain negatively charged toner particles having an average particle diameter of 12 μm. Toner particles 100 obtained
And hydrophobic silica ("R972" manufactured by Nippon Aerosil Co., Ltd.)
Stir 0.3 parts for 1 minute using a Henschel mixer,
Hydrophobic silica was adhered to the toner particles to obtain an electrophotographic toner (F).

Synthesis Example 3 L-lactide (manufactured by Shimadzu Corporation) 100 parts Lauryl alcohol 0.05 parts Tin octylate ("Goldschmitt Cosmos 29", a catalyst for ring-opening polymerization) 0.2 parts Charge control agent (Hoechst) "NXVP434" manufactured by the company) 2 parts The raw material having the above composition was supplied to the raw material supply part of the twin-screw kneading extruder. Cylinder temperature 190 ℃, rotation 6 in the same direction
Nitrogen gas was supplied from the supply port at 0 rpm. The average residence time in the twin-screw kneader was 15 minutes. The obtained polymer was extruded from a nozzle having a diameter of 2 mm. After cooling and solidifying, the chips were cut to obtain lactic acid resin chips. The weight average molecular weight of the obtained chips was 110,000. In the formula (1), n is 1500 and R is a dodecyl group.

Example 5 102 parts of lactic acid-based resin obtained in Synthesis Example 3 carbon black ("MA-100" manufactured by Mitsubishi Kasei) 6 parts Polyolefin wax ("NP-105" manufactured by Mitsui Petrochemical Co., Ltd.) 2 parts above The raw materials having the composition were mixed with a super mixer, melt-kneaded with a twin-screw kneader, pulverized with a jet mill, and then classified with a dry airflow classifier to obtain negatively charged toner particles having an average particle diameter of 12 μm. . Toner particles 100 obtained
And hydrophobic silica ("R972" manufactured by Nippon Aerosil Co., Ltd.)
Stir 0.3 parts for 1 minute using a Henschel mixer,
Hydrophobic silica was adhered to the toner particles to obtain an electrophotographic toner (G).

Synthesis Example 4 L-lactide (manufactured by Shimadzu Corporation) 100 parts Lauryl alcohol 0.05 parts Tin octylate ("Goldschmitt" Cosmos 29 ", a catalyst for ring-opening polymerization) 0.2 parts Polyolefin wax (Mitsui Sekiyu) "NP-105" manufactured by Kagaku Co., Ltd.) 2 parts The raw material having the above composition was supplied to the raw material supply part of the twin-screw kneading extruder. Cylinder temperature 190 ℃, rotation 6 in the same direction
Nitrogen gas was supplied from the supply port at 0 rpm. The average residence time in the twin-screw kneader was 15 minutes. The obtained polymer was extruded from a nozzle having a diameter of 2 mm. After cooling and solidifying, the chips were cut to obtain lactic acid resin chips. The weight average molecular weight of the obtained chips was 100,000. In the formula (1), n is 1400 and R is a dodecyl group.

Example 6 Lactic acid-based resin obtained in Synthesis Example 4 102 parts Carbon black ("MA-100" manufactured by Mitsubishi Kasei) 6 parts Charge control agent ("NXVP434" manufactured by Hoechst) 2 parts The raw materials were mixed with a super mixer, melt-kneaded with a twin-screw kneader, pulverized with a jet mill, and then classified with a dry airflow classifier to obtain negatively charged toner particles having an average particle diameter of 12 μm. Toner particles 100 obtained
And hydrophobic silica ("R972" manufactured by Nippon Aerosil Co., Ltd.)
Stir 0.3 parts for 1 minute using a Henschel mixer,
Hydrophobic silica was adhered to the toner particles to obtain an electrophotographic toner (H).

Synthesis Example 5 L-lactide (manufactured by Shimadzu Corporation) 100 parts Lauryl alcohol 0.05 parts Tin octylate ("Goldschmitt" Cosmos 29 ", catalyst for ring-opening polymerization) 0.2 parts Carbon black (Mitsubishi Kasei) "MA-100" manufactured by Mfg. Co., Ltd. 6 parts Polyolefin wax ("NP-105" manufactured by Mitsui Petrochemical Co., Ltd.) 2 parts Charge control agent ("NXVP434" manufactured by Hoechst Co., Ltd.) 2 parts Biaxial kneading extruder It was supplied to the raw material supply section. Cylinder temperature 190 ℃, rotation 6 in the same direction
Nitrogen gas was supplied from the supply port at 0 rpm. The average residence time in the twin-screw kneader was 15 minutes. The obtained polymer was extruded from a nozzle having a diameter of 2 mm. After cooling and solidifying, the chips were cut to obtain lactic acid resin chips. The weight average molecular weight of the obtained chips was 120,000. In the formula (1), n is 1650 and R is a dodecyl group.

Example 7 The raw material consisting of the lactic acid resin obtained in Synthesis Example 5 was mixed with a super mixer, melt-kneaded with a twin-screw kneader, pulverized with a jet mill, and then classified with a dry air stream classifier. As a result, negatively chargeable toner particles having an average particle diameter of 12 μm were obtained. 100 parts of the obtained toner particles and 0.3 part of hydrophobic silica (“R972” manufactured by Nippon Aerosil Co., Ltd.) are stirred for 1 minute by using a Henschel mixer to adhere the hydrophobic silica to the toner particles, and the electrophotographic toner ( I) was obtained.

Example 8 Lactic acid resin obtained in Synthesis Example 1 100 parts Natural wax (“Rice wax” manufactured by Noda Wax Co., Ltd.) 2 parts Charge control agent (“NXVP434” manufactured by Hoechst Co., Ltd.) 2 parts Raw material having the above composition Was operated in the same manner as in Example 1 to obtain a white toner (J) having an average particle diameter of 12 μm.

Comparative Example 3 A white toner (K) having an average particle diameter of 12 μm was obtained in the same manner as in Comparative Example 1 except that carbon black was not used.

Each of the electrophotographic toners obtained in the above Examples and Comparative Examples was tested for the following items. (1) Deinkability Using the electrophotographic toners obtained in Examples 1 to 7 and Comparative Examples 1 and 2, a test image having a black-white ratio of 6% was 75 g / m ^2.
A test paper was prepared by imaging on the surface of the paper. Using this test paper, a handmade evaluation sheet was prepared under the following conditions. Disaggregation: Test paper 5.0%, NaOH 0.7%, sodium silicate 3.0%, H ₂ O ₂ 1.0%, deinking agent ("Liptor S2800" manufactured by Lion Corporation) 0.2% water. Disperse the dispersion by stirring in a beaker at 50 ° C. for 20 minutes. Dilution / dehydration / kneader treatment: Add 5% water to the water dispersion.
After diluting to 1, the mixture is centrifuged and dehydrated, and pulp, sodium silicate, etc. are added so that the pulp becomes 20%, sodium silicate 3.0%, and NaOH 0.5%, and the mixture is disintegrated with a kneader. Aging: The kneader disaggregated product is aged at 50 ° C. for 2 hours. Flotation: Water is added to aged product and pulp concentration is 1%
The dispersion liquid is prepared, fine bubbles are discharged into the dispersion liquid for 7 minutes, the toner in the liquid is adsorbed by the bubbles and floated on the water surface,
Separate toner and water. Washing: 2.4 g of deinked pulp is washed twice with 1 liter each of water. Preparation of test hand-made sheet: Hand-made sheet by tapping sheet machine (100 g / m ² basis weight)
To create. Evaluation of deinking property: The number of toner particles present in 9 cm ^{2 of a} handmade sheet is evaluated by visual observation and with a microscope in two types of 100 μm or more (visible size) and 60 to 100 μm.

The test results are shown in Table 1. The numerical values in the table represent the number of residual toners. Table 1 60 ■ 100 μm 100 μm or more Total number Number Number Example Example 1 9 6 15 Example 2 10 10 20 Example 3 9 4 13 Example 4 8 6 14 Example 5 10 5 15 Example 6 10 4 14 Example 7 8 5 13 Comparative Example 1 34 28 62 Comparative Example 2 28 25 53 As is clear from Table 1, the electrophotographic toner of the present invention showed excellent deinking property.

(2) Biodegradability test toners (A), (B), (D), (F),
(G), (H), (I) and (J) and comparative toners (C), (E) and (K) were melt-molded into a film having a thickness of about 50 μm and left in soil for 6 months. . As a result, (A), (D), (F), (G), (H), (I)
The films of (J) and (J) lose their shape completely,
Most of the film of (B) disappeared. On the other hand, the films of (C), (E) and (K) remained in the same shape. The white toners (J) and (K) were left in the soil as they were for 3 months. (J) was completely decomposed, but (K) was not decomposed. From the above results, it is clear that the electrophotographic toner of the present invention has biodegradability.

(3) Confirmation of Colorant Dispersion State The kneaded products obtained in Examples 1, 2, 4 and 7 before crushing were cut into a thickness of 0.5 μm, and their cross sections were observed with an optical microscope (40).
(0 times). Table 2 shows the dispersed particle size of carbon black in that view. The numerical values in the table indicate the number of carbon blacks in the particle size.

Table 2 10 μm or more 10 to 5 μm 5 μm or less Number Number Number Example 1 7 21 Countless Example 2 6 13 Countless Example 4 0 4 Countless Example 7 0 3 Countless From Table 2, Examples 1, 2, 4 It can be seen that the dispersed state of the colorant has practically no problem in Nos. 7 and 7, and the dispersed state is particularly good in Examples 4 and 7.

(4) Image characteristics and practical characteristics Toner 4 obtained in Examples 1, 2, 4, 5, 6 and 7
Part, ferrite carrier ("F15" manufactured by Powder Tech Co., Ltd.)
30 ") 96 parts were mixed to prepare a two-component developer for image evaluation. This developer was used as an electronic copying machine" BD-3 "manufactured by Toshiba Corporation.
When evaluated with 810 ″, a good image with high image density and no fog was obtained. Initial copy and 5000
Table 3 shows the image characteristics after copying one sheet. The evaluation method of each characteristic is shown below. Triboelectric chargeability: Measured using a blow-off triboelectric charge amount measuring device manufactured by Toshiba Chemical Corporation. Image density: Measured using a reflection densitometer "RD-914" manufactured by Macbeth. Fog: Measured using a color difference meter "Z-1001DP" manufactured by Nippon Denshoku Co., Ltd.

Table 3 Amount of triboelectricity in developer Image density Fog toner density (μc / g) Initial 5000 sheets Initial 5000 sheets Initial 5000 sheets Initial 5000 sheets Example 1 4.0 4.4 -21.8 -18.6 1.42 1.45 0.68 0.82 Example 2 4.0 4.2 -22.4 -21.2 1.41 1.42 0.62 0.75 Example 4 4.0 4.1 -22.3 -21.5 1.42 1.43 0.41 0.52 Example 5 4.0 3.9 -23.5 -24.2 1.41 1.42 0.48 0.60 Example 6 4.0 4.2 -22.5 -21.2 1.42, 1.44 0.52 0.65 Example 7 4.0 3.9 -23.4 -24.0 1.42 1.42 0.33 0.45 Example 1, 2, 4, 5 , 6 and 7 have no practical problems,
In particular, in Examples 4 and 7, it was found that the fog in the image characteristics was very excellent. Electrophotographic toner 2 obtained in Example 3
5 parts of magnetite carrier 75 having an average particle size of 60 μm
To obtain a two-component developer. When this developer was evaluated by a printer ("KX-P4430" manufactured by Matsushita Electric Industrial Co., Ltd.), a good image without density unevenness and fog was obtained. Table 4 shows the image characteristics after printing 5000 sheets.
It was shown to.

Table 4 Triboelectric charge amount in developer Image density Fog toner density (μc / g) Initial 5000 sheets Initial 5000 sheets Initial 5000 sheets Initial 5000 sheets Example 3 25.0 27.9 -18.4 -17.6 1.42 1.43 0.64 0.76

[0039]

The electrophotographic toner using the lactic acid-based resin of the present invention as a main resin is alkaline and reacts with water to hydrolyze the resin molecules to lower the binding force. For this reason, it is possible to provide a toner that is easy to be deinked and can use the current deinking system as it is, and there is an advantage that recycling of used copy paper can be promoted. At the same time, since it has biodegradability, it is possible to provide a toner having no problem in disposal.

Claims (3)

[Claims] 1. A formula (1) H - [- O -CH (CH 3) -CO-] n -OR (1) [ wherein, R represents a hydrogen atom, an alkyl group, an alkali metal or alkaline earth metal And n represents an integer of 10 to 20,000], the electrophotographic toner containing the lactic acid resin as a binder resin. 2. A formula (1) H-[— O—CH (CH ₃ ) —CO—] _n —OR (1) [wherein R represents a hydrogen atom, an alkyl group, an alkali metal or an alkaline earth metal]. , N is an integer of 10 to 20,000], and is polymerized in the presence of at least one additive selected from a colorant, a charge control agent and an offset preventive agent. The toner for electrophotography according to claim 1, wherein the toner is present. 3. The formula (1) H-[— O—CH (CH ₃ ) —CO—] _n —OR (1), which is a constituent component of an electrophotographic toner polymerized by polymerization, wherein R is a hydrogen atom. , An alkyl group, an alkali metal or an alkaline earth metal, and n is an integer of 10 to 20,000], a colorant, a charge control agent, and an anti-offset agent. A method for producing an electrophotographic toner, comprising a step of polymerizing in the presence of at least one additive selected from the group consisting of: