JPH01267559A - Electrophotographic dry toner - Google Patents

Abstract

PURPOSE:To obtain a toner having good color reproduction performance, and chemical and biochemical stability and safety, and stability against environmental conditions by using a specified binder resin. CONSTITUTION:The binder resin to be used is a polyol resin obtained by reacting an epoxy resin with a primary amine and divalent phenol to extend the chain length, reacting monovalent compounds having each an active hydrogen with 2 epoxy groups linked to both ends of each epoxy resin molecules. Said epoxy groups are reacted with the active hydrogen compounds to open the rings and to connect each epoxy resin molecule, thus permitting the obtained toner to be enhanced in color reproduction performance, chemically stable, especially stable against an amine type compounds, also biochemically stable, and excellent in stability against environmental conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry electrophotographic toner particularly suitable for forming color images.

In conventional dry electrophotography, an electrostatic latent image is formed on a photoconductor using a conventional method, developed with dry toner, the toner image is transferred onto copy paper, and then thermally fixed (usually using a heated roller). I'm getting a copy.

As is well known, the dry toner used in this method is mainly composed of a binder resin and a colorant, and contains additives such as a charge control agent and an anti-offset agent if necessary. Here, the binder resin has the properties required for toner use, namely transparency, insulation, water resistance, fluidity (as a powder), mechanical strength, gloss, and thermoplasticity.

Polystyrene, styrene-acrylic copolymers, polyester resins, epoxy resins, etc. are generally used from the viewpoint of crushability, etc. Among them, styrene resins are widely used because of their excellent crushability, water resistance, and fluidity. ing. However, in order to preserve copies obtained with styrene-based resin-containing toner, if they are placed in a document holder made of a vinyl chloride-based resin sheet, the image side of the copy is left in close contact with the sheet. The plasticizer contained in the vinyl chloride resin transfers to the fixed toner image, plasticizes it, and welds it to the sheet side.As a result, when the copy is separated from the sheet, the toner image is partially or completely peeled off from the copy, and the sheet It also had the disadvantage of getting dirty.

Such drawbacks are also seen in toners containing polyester resins.

As a measure to prevent the transfer to vinyl chloride resin sheets as described above, Japanese Patent Application Laid-open No. 60-263951 and No. 61-24025 have been proposed.
In this issue, a proposal is made to blend styrene resin or polyester resin with an epoxy resin that is not plasticized with a plasticizer for vinyl chloride resins.

However, when such blended resins are used especially for color toners, the incompatibility between different types of resins causes offset problems, curling of fixed images, and glossiness (in the case of color toner images, lack of gloss results in poor images). (visibility), colorability, transparency, and color development become issues.

Therefore, it may be possible to solve the above problem by using an epoxy resin alone, but a new problem arises: the reactivity of the epoxy resin with amines.

Epoxy resin is a thermoplastic resin, and is generally used as a curable resin with excellent mechanical strength and chemical resistance by reacting an epoxy group with a curing agent to form a crosslinked structure. Curing agents are broadly classified into amine type and organic acid anhydride type.

Of course, the epoxy resin used in toner for electrophotography is used as a thermoplastic resin, but some of the dyes, pigments, and charge control agents that are mixed with the resin in the toner are amine-based. It may cause a crosslinking reaction and cannot be used as a toner. Moreover, the chemical activity of this epoxy group is considered to be biochemical, that is, toxic, such as skin irritation, and its presence requires careful attention.

In addition, since epoxy groups exhibit hydrophilic properties, they absorb water significantly under high temperature and high humidity conditions, resulting in decreased charge and background stains.

This may cause poor cleaning, etc.

Furthermore, charging stability in epoxy resins is another problem.

Generally, a toner is composed of a binder resin, a colorant, a charge control agent, and the like. Various dyes and pigments are known as colorants, some of which have charge control properties.
Some have the dual functions of a coloring agent and a charge control agent.

Although it is widely practiced to use an epoxy resin as a binder resin to form a toner with the composition described above, a problem arises in the dispersibility of dyes and pigments, charge control agents, and the like.

Generally, the binder resin, dyes and pigments, charge control agents, etc. are kneaded using a hot roll mill, and it is necessary to uniformly disperse the dyes, pigments, charge control agents, etc. in the binder resin.

However, it is difficult to achieve sufficient dispersion, and poor dispersion of dyes and pigments as colorants results in poor color development and a low degree of coloration. In addition, if the charge control agent or the like is poorly dispersed, the charge distribution becomes uneven, which causes various defects such as poor charging, scumming, scattering, insufficient ID, dullness, and poor cleaning.

Furthermore, JP-A No. 52-86334 discloses a positively chargeable product made by reacting an aliphatic or secondary amine with the terminal epoxy group of a ready-made epoxy resin. As mentioned above, the epoxy group and the amine may cause a crosslinking reaction, and the toner may not be usable.

Although positive chargeability is imparted, it is difficult to set an arbitrary charge level by reaction with an epoxy group.

Furthermore, JP-A-52-156632 discloses reacting one or both of the terminal epoxy groups of an epoxy resin with alcohol, phenol, Grignard reagent, organic acid sodium acetylide, alkyl chloride, etc. However, if epoxy groups remain, problems such as reactivity with amines, toxicity, and wood affinity arise as described above. Furthermore, some of the above-mentioned reactants are hydrophilic, some affect charging, and some affect pulverizability during toner production, and not all of them are necessarily effective in the present invention.

In addition, a first object of the present invention is to provide a toner for dry electrophotography with excellent color reproducibility.

A second object of the present invention is to provide a toner for dry electrophotography that is stable against amine compounds and biochemically stable. - A third object of the present invention is to provide a dry electrophotographic toner with excellent environmental stability.

A fourth object of the present invention is to provide a toner for dry electrophotography that is positively chargeable and stable.

A fifth object of the present invention is to provide a toner that has good compatibility with other resins and has good dispersion of dyes and pigments.

A sixth object of the present invention is to provide a toner for dry electrophotography in which the toner image does not transfer to the vinyl chloride resin sheet even when the fixed image surface of the copy is brought into close contact with the sheet.

The toner of the present invention is a dry electrophotographic toner containing a colorant and a binder resin as main components, in which an epoxy resin as the binder resin is reacted with a primary amine and a dihydric phenol to extend its chain length. The present invention is characterized in that a polyol resin obtained by reacting a monovalent active hydrogen-containing compound with the epoxy groups at both ends of the epoxy resin is used.

As a result of various studies, the present inventors made a polyol resin by reacting the epoxy group of an epoxy resin with an active hydrogen compound and introducing a primary amine into the main chain of the epoxy resin, and used this as a binder resin. When I used it,
It has been found that the above object can be achieved.

Epoxy resin has two epoxy groups in one molecule, and these are located at the ends of the molecular chain.

By reacting with the epoxy groups at both ends, the ring is opened by the compound of the present invention, and the compound becomes bonded, thereby obtaining a resin that is chemically stable, biologically safe, and has excellent environmental properties. be able to.

The compound used in the present invention is a compound having one active hydrogen in one molecule. Here, active hydrogen refers to hydrogen capable of reacting with an epoxy group, and examples thereof include zero-order compounds, and one or more of these may be used.

Examples of monohydric phenols include phenol, cresol, isopropylphenol, aminophenol, nonylphenol, dodecylphenol, xylenol, p-cumylphenol, etc., and those having usually 6 to 40 carbon atoms are preferred.

Monovalent carboxylic M groups include acetic acid, propionic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, acrylic acid, oleic acid, margaric acid, alagic acid, and linoleic acid.

Examples include lyrinic acid, castor oil fatty acid, tall oil fatty acid, etc., and those having 6 to 25 carbon atoms are usually preferred.

The basic skeleton of the polyol resin according to the present invention is made by reacting an epoxy resin with primary amines and dihydric phenols to extend the chain length thereof. Due to the introduction of amine into the resin molecule, the polyol resin of the present invention exhibits positive charge, and the stability of charge is significantly higher than that of positively chargeable resins obtained by adding charge control agents or blending nitrogen-containing polymers. Improved and durable. Furthermore, it is possible to arbitrarily set the charging level depending on the amount introduced.

Further, by introducing the first R amine having a long-chain alkyl group, the polyol resin of the present invention forms a comb-shaped structure, thereby improving the dispersibility of dyes and pigments and improving the compatibility with other resins.

Specific examples of the primary amine used in the present invention include propylamine, butylamine, hexylamine, octylamine, laurylamine, stearylamine, palmitylamine, oleylamine, etc. as aliphatic primary amines. has 6 to 20 carbon atoms. Examples of aromatic primary amines include aniline, toluidine, xylidine, cumidine, hexylaniline, nonylaniline, dodecylaniline, etc. Preferably, the benzene nucleus of aniline has 3 to 20 carbon atoms.
It is a compound in which individual alkyl stores are bonded. The amount of amine introduced is 0.01 to 1.0 parts by weight per 100 parts by weight of the epoxy resin.
00 heavy view%.

In this manner, by simultaneously carrying out the terminal ring-opening reaction of the epoxy resin and the introduction of the amine into the main chain, the above-mentioned advantages can be achieved. Note that the terminal ring-opening reaction does not in any way impede the purpose achieved by introducing the amine, and vice versa.

On the other hand, the epoxy resin used in the present invention is typically a polycondensate of bisphenol A and epichlorohydrin. Commercially available epoxy resins include Epomic R301, Evomic R302, and Evomic R3.
04, Evomic R304P, Evomic R307, Epomic R309, Evomic R362, Epomic R
363, Epomic R364, Epomic R365, Epomic R366, Epomic R367 (manufactured by Mitsui Petrochemical Industries, Ltd.), and the like.

Furthermore, there are also epoxy resins with arbitrary softening points obtained by polyaddition reaction between liquid epoxy resins and bisphenols. As a commercially available liquid epoxy resin, Evamic R1
40, Epomic R139, Epomic R140P (manufactured by Mitsui Petrochemical Industries, Ltd.), and bisphenols such as bisphenol A, bisphenol F, and bisphenol AD.

Next, other materials used in the dry toner of the present invention will be explained.

First, all known dyes and pigments can be used as colorants, such as carbon black, nigrosine dye, iron black,
Naphthol Yellow S, Hansa Yellow (10G, 5G
, G), cadmium yellow, yellow iron oxide, loess, yellow lead, titanium yellow.

Polyazo Yellow, Oil Yellow, Hansa Yellow (
GR, A, RN, R), Pigment Yellow, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Palcan Fast Yellow (5G, R),
Tartrazine lake, quinoline yellow lake, anthrazan yellow BGL, isoindolinone yellow, red iron, red lead, lead powder, cadmium red, cadmium mercury red, antimony vermilion, permanent red 4
R, rose red, fissee red, parachlororthonitroaniline red, lithoulfast scarlet G, brilliant fast scarlet, brilliant carmine BS, permanent red (F2R, F4R,
FRL, FRLL, F4RH), Fast Scarlet VD, Belcampus Lupine B, Lysol Red, Lake Red (C, O), Anthosine B, Brilliant Scarlet G, Lysol Rubin GK, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL,
Bordeaux 10B, Bonmaroon Light, Bonmaroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Reddon, Oil Red, Cinchona Acridone Red, Pyrazolone Red, Polyazo Red, Chrome Permillion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkaline blue lake, peacock blue lake, Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, indanslen blue (RS , BC), indigo, ultramarine, navy blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt violet, manganese violet, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide,
These include pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, lithopone, and mixtures thereof. The amount used is generally 0.1 per 100 parts by weight of binder resin.
~50 parts by weight.

The toner of the present invention may contain other different resins and waxes in order to further improve offset resistance. Although the polyol resin of the present invention has good compatibility with other resins, it may have an adverse effect on fixing properties such as transparency and color development, so the amount of other resins used should be determined in order to fix the toner. It must be within a range that does not substantially affect the characteristics.

The toner of the present invention is charge-controlled by the resin alone, but may contain a charge control agent if necessary. All known charge control agents can be used. For example, nigrosine dyes, Triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts, alkylamides, phosphorus or compounds, tungsten or compounds, fluorine activators, These include salicylic acid metal salts, metal salts of salicylic acid derivatives, and hydrophobic silica.

Other additives include colloidal silica, hydrophobic silica, silicone oil, metal soap, nonionic surfactants, fatty acid metal salts (zinc stearate, aluminum stearate, etc.), metal oxides (titanium oxide,
(aluminum oxide, tin oxide, antimony oxide, etc.), fluoropolymer, etc.

The toner of the present invention made of the above materials may be used as a two-component developer together with a carrier, or may be used as a one-component developer with a carrier included.
The carriers used here include iron powder, ferrite,
Glass beads, etc., are the same as before. Note that these carriers may be coated with resin; in this case, the resin used is polyfluorocarbon or polyvinyl chloride.

These include polyvinylidene chloride, phenol resin, polyvinyl acetal, silicone resin, etc. In any case, the appropriate mixing ratio of toner and carrier is generally about 0.5 to 6.0 parts by weight of toner per 100 parts by weight of carrier.

The present invention will be explained below with reference to Examples. Note that all parts are parts by weight.

Example 1 250 g of bisphenol A epoxy resin (Evomic R140P, manufactured by Mitsui Petrochemical), 130 g of bisphenol A, 29 g of P-cumylphenol/Lz, '
Add tr silyl and t ton 50i+Q, heat up to 0°C under N2 atmosphere, and add 5N lithium chloride aqueous solution.

Thereafter, the temperature was raised to 150°C, and water and xylene were distilled off under reduced pressure. The reduced pressure was released, 12 g of stearylamine was added, and the mixture was reacted at 185°C for 5 hours to obtain a polyol resin (hereinafter referred to as resin A) having a softening point of 142°C and an N content of 0.14% by weight.

When resin A was subjected to epoxy equivalent cavitation using the hydrochloric acid-dioxane method, no reaction of epoxy groups was observed, and it was confirmed that no epoxy groups existed in resin A, and that all of the epoxy groups were ring-opened.

Next, a mixture of the following color toner formulations is melt-kneaded using a hot roll mill, cooled, coarsely ground using a hammer mill, and then finely ground using an air jet grinder to obtain a fine powder of 5 to 15 microns.
Toners of various colors were made by classifying the pus according to particle size.

Yellow toner formulation: 100 parts of resin A Magenta toner formulation: 100 parts of resin A Cyan toner formulation: 100 parts of resin A The red dye used in the magenta toner was amine-based, but no crosslinking reaction was observed during cross-linking and the toner was formed. did it.

Next, 3.5 parts of each color toner was mixed with 96.5 parts of iron powder carrier (Nippon Tetsukosha 1!TEFV23) and 2 parts of each color toner was added.
I made a component-based developer.

When the f-electricity of the obtained developer was measured using the blow-off method, it was +17.2 μC/g for the yellow developer, +14.0 μC/g for the magenta developer, and +1 for the cyan developer.
It was 5.5 μc/g.

Next, these three types of color developers are set in a commercially available color electrophotographic copying machine (a modified model of Ricoh Color 3000), and each color is developed separately. After each toner image is transferred to copy paper, a heated roller When it reaches a certain point, it turns bright yellow, ÷
Zenta and cyan monochrome images were formed.

Clear images were also formed in red, blue, and green fixed images by two-color overlapping development.

Furthermore, a clear full-color image was obtained even when the image was fixed by three-color overlapping development. Note that the lower limit fixing temperature was 110°C, and the hot offset generation temperature was 180°C.

When the above image forming experiment was conducted at 30° C. and 90% high temperature and high humidity, the fixed image had ID defects and background stains.

A clear image was formed with no transfer defects or blisters.

In addition, a full-color image is displayed using an overhead projector (
When the image was fixed on a transparent OHP sheet and projected on an OHP, a clear full-color image with no turbidity was projected. Furthermore, when we conducted a storage test in which a full-color image was closely attached to a vinyl chloride resin sheet and left at room temperature for 180 hours, no 1-ner transition was observed on this sheet.
Full color images were well maintained.

In addition, when a running test was conducted up to 50,000 prints using three-color overlapping development, no significant change was observed in the fixed image, and the image on the 50,000th print was also a bright image with no background smudges or shading. Also, the amount of charge on the 50,000th sheet is yellow developer + 1
5.8μc/g, magenta developer +13.0μc/g,
The cyan developer was +14°0 μc/g, and the charging was stable.

A black toner was also prepared using Resin A and the following recipe in the same manner as described above.

When 100 parts of resin A was similarly used as a developer and set in a commercially available electrophotographic copying machine (FT4820 manufactured by Ricoh Co., Ltd.) to form an image, a clear image was formed. Lower limit temperature of fixing is 110℃
The temperature at which hot offset occurred was 180°C. Images were clear and undisturbed even under high temperature and high humidity conditions. No toner transfer to the vinyl chloride sheet of the fixed image was observed.

- On the other hand, when we conducted a running test of up to 50,000 sheets,
Even with 50,000 images, the images were clear and free of any dirt or blur. In addition, the amount of charge is initially +15.3μc/g,
The charge was stable for the 50,000th sheet +16.7 μc/g.

Example 2 In Example 1, laurylamine was used instead of stearylamine, and synthesis was performed in the same manner as in Example 1 to produce a polyol resin (hereinafter referred to as resin B) with a softening point of 141°C and an N content of 0.15% by weight. I got it. When the epoxy equivalent of Resin B was measured in the same manner as Resin A, no reaction of the epoxy groups was observed.

Next, using this resin B, yellow, magenta, and cyan color toners were prepared in the same manner as in Example 1.

The formulation of each color toner is as follows.

Yellow toner formulation: Resin B 100 parts TP-3021 parts manufactured by Hodogaya Chemical Industry Co., Ltd. Magenta toner formulation: Resin 8100 parts TP-3021 parts Cyan toner formulation: Resin 8100 parts TP-3021 parts The red dye used in the magenta toner was Although it was amine-based, no crosslinking reaction was observed during kneading, and it was possible to form a toner.

Next, 3.5 parts of each color toner was mixed with 96.5 parts of iron powder carrier (TEFV23 manufactured by Nippon Tetsuko Co., Ltd.) to prepare two-component developers for each color.

When the charge amount of the obtained developer was measured by the blow-off method, the yellow developer was +18.5 μC/g, the magenta developer was +15.9 μC/g, and the cyan developer was +16
．． It was 2 μc/g.

When monochrome, two-color, and three-color images were formed using these developers, clear fixed images were obtained for single-color, two-color, and three-color full-color images. The lower limit fixing temperature was 110° C., and the temperature at which hot offset occurred was 180° C. 6 Also, when the above image forming experiment was conducted under high temperature and high humidity, no abnormal images were observed.

Furthermore, the projected image by OHP was clear, and there was no toner transfer to the vinyl chloride resin sheet.

Even in a running test of up to 50,000 sheets using 3-color overlapping, images,
No significant change in charge was observed.

Example 3 Synthesis was carried out in the same manner as in Example 1, except that stearic acid was used instead of P-cumylphenol and cyclohexylamine was used instead of stearylamine, and the softening point was 143°C and the N content was 0. A 15% by weight polyol resin (hereinafter referred to as resin C) was obtained.

When the epoxy equivalent of Resin C was measured in the same manner as Resin A, no reaction of the epoxy group was observed.

Next, when yellow, magenta, and cyan color toners were kneaded using this resin C in the same manner as in Example 2, toners were obtained without crosslinking. Furthermore, we made developers for each color and produced single colors as well.

When images were formed by two-color overlapping and three-color overlapping development, clear fixed images were obtained for single-color images, two-color overlapping images, and three-color overlapping full-color images. Clear fixed images were obtained even under high temperature and high humidity conditions.

Furthermore, the projected image by OHP was clear, and no toner transfer to the vinyl chloride resin sheet was observed. Furthermore, even in a running test of up to 50,000 sheets of three-color overlay, no significant change was observed in either single image or charge.

Example 4 In the same manner as in Example 1, 250 g of bisphenol A type epoxy resin (8140P), bisphenol Al2
A polyol resin (hereinafter referred to as "resin") having a softening point of 130 DEG C. was obtained by using 6 g of P-cumylphenol, 35 g of P-cumylphenol, and 12 g of stearylamine.

When the epoxy equivalent of the resin was measured in the same manner as Resin A, no reaction of the epoxy group was observed.

Next, when yellow, magenta and cyan color toners were kneaded using resin resin in the same manner as in Example 2, toners were obtained without crosslinking.

Furthermore, each color developer is made, and in the same way, single color, two color stack, and three color developer are made.
When forming an image by overlapping colors, a single color image, 2
Clear fixed images were obtained for both the color superimposed image and the three-color superimposed full-color image.

Clear fixed images were obtained even under high temperature and high humidity conditions.

Furthermore, the projected image by OHP was clear, and no toner transfer to the vinyl chloride resin sheet was observed.Furthermore, no significant change was observed in either single image or charge during a running test of up to 50,000 sheets using three-color stacking. .

A black toner was also made using this resin.

Rub Resin D 100 parts Carbon Black '44 12 parts When images were formed using the developer as in Example 1, clear images were obtained both at normal temperature and humidity, and at high temperature and high humidity.

Further, no toner transfer to the vinyl chloride sheet of the fixed image was observed.

Even in a running test of 50,000 sheets, no significant changes in image quality or charging were observed.

Comparative Example 1 Bisphenol A epoxy resin (Amic R368
A toner was kneaded using the same recipe as in Example 1, except that the toner (manufactured by Mitsui Petrochemical Co., Ltd.) was used as it was.

Then, a crosslinking reaction occurred during kneading of the magenta toner, and it solidified on a hot roll mill, making it impossible to form a toner.

When only yellow and cyan were converted into toner and used as a developer,
The charge amount of the yellow developer was 10 io, sμC/g, and the cyan developer was +8.5 μc/g. An image was formed using a single color or a two-color superimposition, but the image looked a little smudged. Similarly, when image formation was performed under high temperature and high humidity,
The result was an abnormal image with a smeared background and a bumpy appearance.

When we conducted a running test using two-color overlapping development,
After 1,000 sheets, the background smudge became severe and transfer defects occurred, and no image was formed after 1,600 sheets.

At this point, when the amount of charge of the developer was measured, it was found that both colors had negative polarity.

Note that there was no toner transfer to the vinyl chloride sheet in the initially obtained fixed image.

Comparative Example 2 Using the apparatus of Example 1, bisphenol A type resin 250
g, 139 g of bisphenol A, 30 g of P-cumylphenol, and 50 ml of xylene were added.

The temperature was raised to 70°C under an N2 atmosphere, a 1.8N aqueous lithium chloride solution was added, and the temperature was then raised to 185°C, during which water and xylene were distilled off under reduced pressure.

After the vacuum was released, the reaction was continued for another 5 hours to obtain a polyol resin with a softening point of 142°C. No reaction of epoxy groups was observed in the obtained resin.

Next, using this resin, yellow,
When magenta and cyan color toners were mixed, toners could be formed without crosslinking or the like. A developer was made from the obtained toner.

The charge amount of the yellow developer was +11.0 μc/g, the magenta developer was +7.2 μc/g, and the cyan developer was +9.0 μc/g. When images were formed by monochrome, two-color superimposed, and three-color superimposed development using these developers, fixed images were obtained for single-color images, two-color superimposed images, and three-color superimposed images, but the images were slightly smudged. Ta. Note that there was no toner transfer to the vinyl chloride resin sheet of the obtained image. Furthermore, when images were formed under high temperature and high humidity conditions, no abnormal images such as blurring were observed.

However, when we conducted a running test using three-color overlapping development, we found that after 1,000 sheets, the background smear became severe and transfer defects occurred, and no image was formed after 1,600 sheets.At that stage, the amount of charge of the developer When measured, 3
Both colors had negative polarity.

Comparative Example 3 Using the apparatus of Example 1, 250 g of bisphenol A type epoxy resin, 117 g of bisphenol A, and 50 mQ of xylene were added, the temperature was raised under N2 atmosphere, and 1 rtfl of 0.65N aqueous sodium hydroxide solution was added.

Thereafter, the temperature was raised to 150°C, and the pressure was reduced midway through to distill off xylene. After releasing the reduced pressure, add 11 g of stearylamine,
The reaction was carried out at 85°C for 5 hours to obtain an amine-modified epoxy resin with a softening point of 142°C. When a toner was mixed with this resin using the same recipe as in Example 1, a crosslinking reaction occurred during the mixing of the magenta toner, which solidified on a hot roll mill and could not be made into a toner.

When only yellow and cyan were converted into toner and used as a developer,
The charge amount was +17.6 μC/g for the yellow developer and 15.2 μC/g for the cyan developer.

Although it was possible to form images using a single color or two-color overlay.

When a similar image was formed under high temperature and high humidity conditions, an abnormal image with background smear and unevenness was obtained.

When a running test was conducted up to 50,000 copies by two-color overlapping development, no significant change was observed in the fixed image, and the image on the 50,000th copy was also a bright image with no background stains or unevenness. Also, the amount of charge on the 50,000th sheet is yellow developer + 15.8
μc/g, cyan developer +13.9 μc/g, and charging was stable.

Effects As described above, the dry electrophotographic toner using the specific binder resin of the present invention has good one-color reproducibility, is chemically and biochemically stable, safe, environmentally stable, and stable. A positive polarity JFi electrode with good compatibility with other resins, good dispersion of dyes and pigments, and no transfer to PVC matte can be obtained.

Patent applicant: 1 person other than Ricoh Co., Ltd.

Claims (1)

[Claims] 1. In a dry electrophotographic toner whose main components are a colorant and a binder resin, an epoxy resin as the binder resin is reacted with a primary amine and a dihydric phenol to extend the chain, and both ends of the epoxy resin are 1. A toner for dry electrophotography, characterized in that a polyol resin obtained by reacting an epoxy group with a monovalent active hydrogen-containing compound is used.