JPH03164750A - Manufacture of toner - Google Patents

Abstract

PURPOSE:To enhance dispersibility and coloring power of a colorant by executing the 2 steps of melt kneading operations, of the constituent materials of the toner; a binder resin, an electric charge controller, and a colorant, under prescribed conditions. CONSTITUTION:The toner is prepared by melt kneading the binder resin, the charge controller, and the colorant in advance to form a composition containing the charge controller in a concentration less than a desired value and the colorant in a concentration higher than a desired value, then, further adding the binder resin and the charge controller to the composition, and again melt kneading the mixture so as to obtain the desired concentrations of both, in the first kneading step, adding the charge controller in a concentration smaller than the prescribed value in order to give its sufficient dispersibility into the binder resin, and in the second step, adding the resin and the controller and dispersing the charge controller by considering the selective dispersion of the controller into the toner surface, thus permitting dispersibility of the colorant and the coloring power to be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing toner, and particularly to
The present invention relates to a method for producing full-color toner that has high chroma and excellent charging stability.

[Prior Art] In general, toner produced by the pulverization method is produced by melting and kneading raw materials such as a coloring agent, an anti-offset agent, and a charge control agent using a styrene resin, styrene-acrylic resin, or polyester resin as a binder resin. After that, it is manufactured by cooling, pulverizing and classifying.

Conventionally, known methods for melting and kneading toner include a screw type extruder, a pressurized and heated Nigoo, a two-roll mill, a three-roll mill, and a Banbury mixer.

In the manufacturing process of color toner for electrophotography, this melt-kneading step is an important element that influences the dispersibility of colorants and charge control agents. That is, if the dispersibility of the colorant contained in the binder resin is insufficient, especially in the case of color toner, the desired coloring power may not be obtained, the saturation may decrease, The color tone may change, and the colorant may become uneven in density due to segregation of the secondary agglomerated colorant in the binder resin.

Furthermore, poor dispersion of the charge control agent causes a fatal defect in the charging characteristics of the toner for electrophotography. For example, the rise of charging is slow, a desirable amount of charging cannot be obtained, and there are significant differences in charging characteristics in environments such as low temperature, low humidity, and high temperature and high temperature.

In addition, (by repeatedly copying a large number of sheets, the charge level easily decreases, causing fogging and scattering, and the toner tends to have a broad charge distribution and lack durability and environmental stability.

Several methods have been proposed to solve the problem of poor dispersion. For example, there is a method in which the melt-kneaded material is passed through a kneading device multiple times to improve dispersion. In this method, it is not possible to obtain a dispersibility higher than the dispersion equilibrium peculiar to the kneading equipment, and even if the kneading equipment is passed through the kneading equipment many times,
It is not possible to obtain the expected effect.

Another method is to use a device that facilitates dispersion and uniformity, such as a flow mixer, Henschel mixer, micro speed mixer, flash mixer, etc., as a premixing device.

However, most of these methods involve rotating stirring blades at high speed inside the container to effect dispersion, and the temperature inside the container rises during mixing, causing the binder resin to adhere to the blades or the inner wall of the container.
Problems such as fusion to the main shaft part tend to occur.

Another method is to obtain a desired kneaded product by previously obtaining a resin composition containing a high concentration of colorant and then diluting it with a binder resin. There is a so-called masterbatch method.

As one of these methods, Japanese Unexamined Patent Publication No. 62-30259 discloses a method in which a finely pulverized masterbatch is obtained and then diluted and melted. The above method requires a plurality of pulverization steps until the desired toner is obtained, and requires a large amount of energy and cost. Furthermore, this method does not take into account the dispersibility of the charge control agent, which has a large effect on the charging characteristics of the toner.

[Problems to be Solved by the Invention] However, the present invention provides a toner manufacturing method that significantly improves the above-mentioned drawbacks. That is, an object of the present invention is to provide a method for producing a toner that allows a toner with good colorant dispersibility and high tinting power to be obtained. Another object of the present invention is to provide a method for producing a color toner with high saturation and excellent transparency. Another object of the present invention is to provide a method for producing a toner with excellent charging stability.

Another object is to provide a method for producing color toner that is less susceptible to charge deterioration even after repeated copying.

Another object of the present invention is to provide a method for producing a toner that provides charging characteristics with excellent environmental stability.

[Means and Effects for Solving the Problems J] The feature of the present invention is that the charge control agent and colorant are melted together with the binder resin in advance so that the concentration of the charge control agent is below the desired concentration and the concentration of the colorant is above the desired concentration. A kneaded and dispersed composition is obtained, and then a binder resin and a charge control agent are further added to the composition obtained in the previous step to obtain the desired colorant concentration and charge control agent concentration.
, a method for producing a toner characterized by melt-kneading.

The toner manufacturing method of the present invention is similar to the conventional method up to the step of obtaining a masterbatch containing a high concentration of colorant in advance in order to improve the dispersibility of the colorant.

However, we pay particular attention to imparting chargeability to the toner, and in order to provide sufficient dispersibility of the charge control agent into the binder resin as a first step, we add the charge control agent to the masterbatch at a concentration below the desired concentration. The feature of the present invention lies in the addition and dispersion of the binder resin and the charge control agent in consideration of the selective dispersion of the charge control agent onto the toner surface as a subsequent stage of the dispersion.

That is, in order to obtain sufficient dispersibility of the colorant, it is essential to go through the kneading process multiple times (at most, about two times) until dispersion equilibrium is reached.

However, it would be premature to think that a toner with preferable charging properties can be obtained by simply containing and dispersing the charge control agent and aiming for uniformity. This is because it is generally believed that a favorable charge can be obtained only when the surface of the toner contacts and mixes with other materials, and charge is exchanged there. At this time, it is only the surface properties, surface composition, and surface shape of the toner that make a significant contribution to triboelectrification, and it is difficult to think that the composition within a few micrometers from the toner surface at least controls charging.

It is reasonable to assume that when a certain amount of charge control agent is sufficiently dispersed, the control agent is almost uniformly dispersed inside and on the surface of the toner. Therefore, the effective charge control agent on the surface of the toner inevitably decreases by the amount that is divided into the inside and the surface. Therefore, in the present invention, although the charge control agent exists inside the toner, it is considered that most of the charge control agent exists on the surface of the toner.

As a result, the frictional charging of the toner is preferably improved, and rapid charging rise and uniform charging can be achieved.

At the same time, sufficient coloring power can be obtained by forming the colorant into a masterbatch.

Further, since a charge control agent exists near the colorant, even if a colorant having a polarity opposite to that of the toner is used, the presence of the charge control agent makes it possible to control the charge polarity and charge amount to desired values. In many cases, using a colorant of opposite polarity alone will result in
The toner may have a low charge level that does not reach the desired charge level, or a large amount of toner may be produced that is poorly controlled and causes fog.

In order to obtain the composition of the first stage of the present invention, the amount of colorant added to 100 parts by weight of the binder resin is 20 to 50 parts by weight, preferably 25 to 40 parts by weight. Further, in order to obtain the final formulation, the amount of binder resin and charge control agent added in the melt-kneading step of the latter stage may be determined by adding and dispersing the necessary amounts in consideration of the composition ratio of the former stage.

The toner manufacturing method of the present invention can be used by appropriately combining conventionally used premixers and kneading devices, and when moving from melt-kneading in the former stage to melt-kneading in the latter stage, the kneaded composition in the former stage can be mixed. There is no separate restriction on the particle size as long as it can be fed into the kneading device used in the subsequent process. Generally, the particle size is around 1 mm to 100 mm.

As the binder resin for toner of the present invention, the following can be used as long as the gist of the present invention is not impaired.

For example, polystyrene, chloropolystyrene, poly-α-
Methylstyrene, styrene-chlorostyrene copolymer,
Styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-
Vinyl acetate copolymer, styrene-maleic acid copolymer,
Styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate) copolymers, etc.), styrene-methacrylate ester copolymers (styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, styrene-butyl methacrylate copolymers, styrene-phenyl methacrylate copolymers) etc.), styrene-based resins such as styrene-α-methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer (styrene or a homopolymer or copolymer containing styrene substituted product)
Vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl Examples include acrylate copolymers, xylene resins, polyvinyl butyral resins, etc. In the toner of the present invention, particularly preferred resins include styrene-acrylic acid ester resins;
There are styrene-methacrylic acid ester resins and polyester resins.

In particular, the following formula (wherein R is ethylene or propylene group, X13
' is each a positive integer of 1 or more, and the average value of x+y is 2 to lO. ) or a substituted product thereof as a diol component, and a carboxylic acid component consisting of a divalent or higher carboxylic acid, its acid anhydride, or its lower alkyl ester (for example, fumaric acid,
A polyester resin obtained by cocondensation polymerization with at least maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) is more preferable because it has sharp melting characteristics.

Coloring agents suitable for the purpose of the present invention include the following pigments or dyes.

Examples of dyes include c, r, direct red 1, and c.
,1, Direct Red 4, C,1, Acid Red 1
, C,1, Basic Red 1, C,1, Modern Tread 30, C,1, Direct Blue 1, c,r, Direct Blue 2, C,1, Acid Blue 9, C,1,
Acid Blue 15, C, 1, Basic Blue 3, C
,I.

There are basic blue 5, C, 1, modern blue, etc.

Pigments include Naphthol Yellow S, Hansa Yellow G1 Permanent Yellow NCG, Ver7ent Orange GTR, Pyrazolone Orange, Benzidine Orange G
1 Permanent Red 4R, Watching Red Calcium Salt, Brilliant Carmine 3B, First Violet B1 Methyl Violet Lake, Phthalocyanine Blue First Sky Blue, Indan Stremburu
There are BC etc.

Preferably, the pigments are disazo yellow, insoluble azo, and copper phthalocyanine, and the dyes are basic dyes and oil-soluble dyes.

Particularly preferably C,L pigment yellow 17, C,1
, Pigment Yellow 15, C,1, Pigment Yellow 13, C,1, Pigment Yellow 14, c, r, Pigment Yellow 12, C,1, Pigment Red 5,
C.I.

Pigment Red 3, C, 1, Pigment Red 2, C
, I, Pigment Red 6, C,1, Pigment Red 7, C,1, Pigment Blue 15, c, r, Pigment Blue 16, carboxybenzamidomethyl group 2-
Copper phthalocyanine pigment having 3 or Ba having the structural formula (I) shown below and having 2 to 3 carboxybenzamidomethyl groups substituted on the phthalocyanine skeleton
These include copper phthalocyanine pigments, which are salts.

n = 2 to 3 (blank space below) except when all are -H (.) The dyes are C,1, Solvent Red 49, C,1,
Solvent Red 52, C, 1, Solvent Red 10
9, C, 1, Basic Red 12, C, 1, Basic Red
These include Socle Cito 1, C, 1, and Paysic Red 3b.

The content of yellow toner, which sensitively reflects the transparency of OHP films, is 1/1 of the binder resin.
The amount is 12 parts by weight or less, preferably 0.1-12 parts by weight, more preferably 0.5-7 parts by weight.

If the amount is 12 parts by weight or more, the reproducibility of green and red, which are mixed colors of yellow, and human skin color in images is poor.

Regarding other magenta toners and cyan toners, the amount is preferably 15 parts by weight or less, preferably 0.1 to 15 parts by weight, more preferably 0.1 to 9 parts by weight, based on 100 parts by weight of the binder resin.

Particularly in the case of a black toner that uses two or more colorants in combination, adding a total colorant amount of 20 parts by weight or more not only tends to cause the carrier to be spent, but also exposes a large amount of the colorant on the toner surface. This increases the adhesion of the toner to the drum, further destabilizing the fixing properties and anti-offset properties. Therefore, in the black toner, the amount of colorant is preferably 3 to 15 parts by weight based on 100 parts by weight of the binder resin.

A preferred combination of colorants for forming a black toner includes a combination of a disazo yellow pigment, a monoazo red pigment, and a copper phthalocyanine blue pigment. The mixing ratio of each pigment is 1:1.5 to 2.5:0.5 to 1.5 of yellow pigment, red pigment, and blue pigment.
is preferred. As a disazo yellow pigment, C,1
, Pigment Yellow 13 or 17 are preferred, and monoazo red pigments include C,1, Pigment Red 5.
or 7 is preferable, and C,1, Pigment Blue 15 is preferable as the copper phthalocyanine blue pigment.

As an essential attribute of the charge control agent according to the present invention, first, it must have a colorless or light color tone that does not affect the color tone of the color toner. Next, due to the addition of the control agent, the amount of charge must change by 10% or more compared to the product without the addition.

Typical examples of negative charge control agents include metal complexes of alkyl-substituted salicylic acids, such as chromium complexes and aluminum complexes of ditertiary-butylsalicylic acid.

Examples include organometallic complexes such as zinc complexes and copper complexes.

The amount of the charge control agent added in the composition of the first part of the present invention is 0.00 parts by weight per 100 parts by weight of the binder resin. O1-5.5 parts by weight (
(preferably 0.05 to 4.0 parts by weight), and in the final formulation, 0.1-1 to 100 parts by weight of the binder resin.
0 parts by weight (preferably 0.5 to 8 parts by weight).

Note that the present invention does not preclude the addition of other known additives.

[Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

The above formulation was premixed using a high-speed Henschel mixer, and then passed through three rolls set at a temperature of 150°C to be melt-kneaded.

Next, the kneaded composition was crushed to a particle size of 2 mm using a speed mill, and 532 parts by weight of the polyester resin,
and 22 parts by weight of the chromium-containing complex were added to the composition and melt-kneaded using a twin-screw extruder. This final kneaded product was pulverized and classified, and appropriate silica was added to obtain a cyan toner having a volume average of 8.0 μm.

This cyan toner was mixed with a coated ferrite carrier coated with styrene acrylic resin and having an average particle size of 45 μm to prepare a starter having a toner concentration of 5%.

Copying was carried out using a color electrophotographic apparatus having an OPC photosensitive drum and a replenishment/development system shown in FIGS. 1 and 2.

An example of the replenishment-development system used in the present invention is as follows.
The replenishment toner sent by the supply screw 16 in the toner conveyance cable 4 is supplied to the developing device 2 through the toner replenishment port 14.
2 and is supplied into the developing device.

When the developing device rotates and comes to a position facing the photosensitive drum 1, the replenishing toner is uniformly mixed with the developer within a very short time by the mixing/conveying screw 11, and the developer is mixed with the developer at a constant developer concentration. Become.

The developer becomes a constant amount of developer on the developing sleeve 12 by the developer regulating blade 15, and a negative charge is applied to the photosensitive drum by a reversal development method at a portion facing the photosensitive drum 1 having a negatively charged electrostatic latent image. The sexual toner is transferred.

Using this method, 2.0 in cyan single color under low temperature and low humidity environment.
A 10,000-sheet printing test was conducted, and even after 20,000 sheets, the image remained as good as the initial one without fogging.

There was also no fading or loss of density during continuous copying.

By the way, the amount of charge at the initial stage and after 2,000,000 sheets is -45.
, 7 c/g, -48, 2 c/g.

Table 1 shows the above-mentioned first stage, second stage and final kneaded product (toner)
The additive amounts or contents of the resin, colorant, and charge control agent are collectively shown in Example 2.3 and Comparative Example 1 below. In the table, the numbers in parentheses in the first part indicate the content of the colorant or charge control agent when the resin in the first stage is converted to 100 parts by weight, and the numbers in parentheses in the final kneaded product indicate the content of the final kneaded product. The content of the colorant or charge control agent is shown in terms of 100 parts by weight of the resin.

A yellow toner was obtained in the same manner as in Example 1 except that a yellow pigment (C, 1, Pigment Yellow 17) was used instead of the phthalocyanine pigment, and the toner concentration was 4.0%. Copying was repeated in a high-temperature environment (30° C., 80% R), and good images with no fog or toner scattering were obtained even after 20,000 copies.

A kneaded composition was obtained using the above recipe as in Example I. Furthermore, 540 parts by weight of the styrene-acrylic copolymer and 33 parts by weight of the aluminum-containing complex were added to the kneaded composition as in Example 1 (kneading-grinding- Classified and added silica to 8.5
A magenta toner of μ was obtained.

Using the cyan, yellow, and magenta toners of Example 1, Example 2, and Example 3, the toner density was 5% and 4%, respectively.
%, 4.5%, and made 50,000 full-color copies in a normal temperature environment using a full-color copying machine as shown in Figure 19 and Figure 2, but the image deteriorated such as fogging, fading, and decreased density. It was a good one.

However, in Example 1, a cyan toner was obtained without adding the chromium-containing complex during kneading in the latter stage.

The rest was the same as in Example 1 (copying was performed repeatedly, but the image density gradually decreased, and the initial optical density was 1.5 (using a Macbeth reflection densitometer RD-914 model red filter). However, after about 10,000 sheets, it was 0.95.

It is assumed that this is due to toner charge-up that occurs uniquely in low temperature, low humidity environments.

[Effects of the Invention] According to the present invention, the dispersibility of the colorant can be improved by melt-kneading the binder resin, charge control agent, and colorant, which are the materials forming the toner, in two stages under certain conditions. It is possible to obtain a toner with good coloring, excellent transparency and charging stability.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of a color electrophotographic apparatus having an oPC photosensitive drum and a replenishment/development system.

Claims (1)

[Claims] (1) A composition is prepared by melt-kneading and dispersing a charge control agent and a colorant together with a binder resin in advance so that the concentration of the charge control agent and the coloring agent are below the desired concentration and above the desired concentration of the colorant, and then the desired colorant concentration and charge are obtained. A method for producing a toner, comprising further adding a binder resin and a charge control agent to the composition obtained in the first step so as to achieve a control agent concentration, and melt-kneading the mixture.