JPS63289558A - Electrostatic latent image developing black toner - Google Patents

Abstract

PURPOSE:To narrow a distribution of electrically charged quantities of toner particles and to prevent its scattering and fogging by electrostatically attaching a charge donor to the surface of each core particle of the toner and locally heating the surfaces of the core to fix the donor to the surface. CONSTITUTION:The toner to be used is an electrostatic latent image developing black toner, and composed of a thermoplastic resin, a colorant, and the charge donor, and the toner is obtained by electrostatically attaching 0.01-10pts.wt. of the positive or negative charge donor to 100pts.wt. of the core particles to their surfaces, then, locally heating the surfaces, and fixing the donor to the surfaces, thus permitting the distribution of the charge quantities of the toner particles to be narrowed, and the charge quantity to be stabilized, and consequently, fogging and scattering of the toner to be prevented.

Description

[Detailed description of the invention] Ru.

2. Description of the Related Art Development of an electrostatic latent image is carried out by electrostatically adhering triboelectrically charged toner to the electrostatic latent image formed on a photoreceptor.

Conventionally, as a method of imparting charge to toner, it has been known that in a two-component development method, charge is imparted by mixing and stirring with a substance generally called a carrier. Furthermore, in the -component development method, it is known that charge is imparted by contact with a developing sleeve, a toner regulating blade, a photoreceptor, or the like. In either method, if the toner is not uniformly charged, problems occur during development and transfer. For this reason, conventionally, charging toner is
This has been done by placing a charge imparting agent inside the toner having a triboelectric charging series opposite to that of the carrier or blade material.

For example, a pulverization method toner in which a charge imparting agent is mixed and kneaded with a thermoplastic resin and a colorant, and then crushed and classified to obtain toner particles, or a colorant and a charge imparting agent are dispersed in a monomer and then polymerized. suspension polymerization toner obtained by
Alternatively, a capsule toner in which a liquid containing a colorant, a low softening point substance such as wax, a fixing resin, and a charge imparting agent are surrounded by a wall material (capsule shell) with a higher softening point than these, or, Photoconductive toner whose surface is coated with a photoconductive substance is known. Also, Unexamined Japanese Patent Publication No. 6
1-210368, a microspherical resin, a binder resin, and a coloring agent are mixed and stirred at a temperature lower than the softening point of the spherical resin and higher than the softening point of the binder resin, and the molten binder resin forms a spherical shape. A method of attaching a coloring agent to the resin surface was disclosed in Japanese Patent Application Laid-Open No. 59-375.
No. 53 discloses a method of attaching a coloring agent to the surface of a resin.

Problems to be Solved by the Invention Pulverization method toner, suspension polymerization toner, by conventional manufacturing method,
In both capsule toner and photoconductive toner, a charge imparting agent is present inside the toner particles, and only a small amount of the added amount is present on the surface. Therefore, the distribution of the amount of charge on the toner becomes wide, and problems such as toner scattering and fogging occur accordingly. JP-A-61-210
The toner disclosed in Japanese Patent No. 368 also has the same problems as the toner produced by the conventional manufacturing method described above because the surface of the toner is coated with a binder resin having a low softening point. Furthermore, in the toner disclosed in Japanese Patent Application Laid-open No. 59-37553,
Since the colorant is attached only to the toner surface, ID is insufficient if a small amount of colorant is added, and if a large amount of colorant is added, the colorant may peel off from the toner and form a paint on the carrier surface, or cause damage to the developer. There is a problem that the printing durability may be deteriorated by mixing with the paper.

Means for Solving the Problems The present invention provides a black toner for developing electrostatic latent images comprising at least a thermoplastic resin, a colorant, and a charge-imparting agent, in which the toner has a core material containing the colorant and/or the charge-imparting agent. 0.01 parts by weight to 100 parts by weight of the core material on the surface
10 parts by weight of a positive or negative charge imparting agent is added to electrostatically adhere, and then heat is locally applied to the surface layer,
The method is characterized in that the charge imparting agent is fixed.

Specifically, in the toner of the present invention, a positive or negative charge imparting agent is electrostatically attached to the surface of the core material, and then heat is locally applied to the surface layer to fix the charge imparting agent. It can be obtained by

The toner core material used in the present invention is not particularly limited and may be any material as long as it can be obtained by a conventionally known method. In other words, pulverized toner obtained by mixing and kneading thermoplastic resin, coloring agent, and/or charge-imparting agent, and then pulverizing and classifying, spherical toner obtained by suspension polymerization, and spherical toner obtained by wrapping the core in a shell. There are capsule toners, photoconductive toners, and the like, but any toner may be used as long as it can fix a charge imparting agent and has a uniform charge, and is not particularly limited.

The thermoplastic resin that can be used in the present invention is not particularly limited as long as it is commonly used in toners, but examples include polystyrene, polyacrylate, polymethacrylate, styrene-acrylic copolymer resin, polyester, epoxy, and polystyrene. Ether, polycarbonate, polyacid anhydride, polyolefin such as polyurethane, polyethylene, polypropylene, polyamide, etc. are used.

Further, as the pigment, known pigments such as carbon black such as furnace black, channel black, and acetylene black can be used. In addition, organic and/or inorganic black or non-black coloring agents (
Pigments, dyes) may be used in combination.

A method for attaching a positive or negative charge imparting agent to the surface of the toner core material is to place the toner core material and the charge imparting agent in a tank equipped with rotating blades, such as a normal Henschel mixer or super mixer. There is a method in which the charge imparting agent is attached around the toner core material by frictionally charging each other by inserting the toner and rotating the toner core material. Any other method may be used for attaching the charge imparting agent to the surface of the toner core material. The amount of charge imparting agent attached to the surface of the toner core material is determined by how the charge is controlled. The amount of charge imparting agent added is 0.00 parts by weight per 100 parts by weight of the toner core material. It is possible to use up to about 1 part by weight of O to 1 part by weight, but preferably 0.05 part by weight to 5 parts by weight. When the amount added is 0.01 parts by weight or less, the amount of charge imparting agent that adheres to the surface of the toner core material is small, resulting in insufficient charge of the toner. Furthermore, if the amount added is 10 parts by weight or more, the charge imparting agent fixed to the toner may peel off and become spent on the surface of the carrier or be mixed into the developer, deteriorating printing durability.

The particle size of the core material used in the present invention is an average particle size of 4 to 20μ.
1 can be used. The particle size of the charge imparting agent that can be used practically is 0.02 μm to IO μm, preferably 0.02 μm to IO μm.
It is 1 μm to 3 μm order. Generally, a large particle size charge imparting agent is an agglomeration of small particles with an effective large particle diameter of 1μ or less, and even when a large particle size charge imparting agent is used, the charge imparting agent is electrostatically attached to the core. During the process of adhering to the core material, large particles are crushed due to mechanical stress, resulting in small-particle charge imparting agents adhering to the surface of the core material.

The charge imparting agent that can be used in the present invention is an inorganic material, as long as it is triboelectrically charged with the toner core material and imparts a positive or negative charge.
Anything organic is fine. Examples of positive charge imparting agents include quaternary ammonium salts (Pb0, manufactured by Orient Chemical Industries, Ltd.), nigrosine dyes such as Bontron N-01 (manufactured by Orient Chemical Industries, Ltd.), JP-A-59-78364; JP-A-59-136746, JP-A-59-
Publication No. 114546, and JP-A-59-123850
Charge-imparting agents described in the above publications and copolymers of aminoacrylate (for example, -styrene-diethylaminoethyl methacrylate copolymer) can be used.

Further, examples of negative charge control agents include Cr and Go.

With chelated dyes of metals such as Fe, Bontron 5
-34. S-40 (manufactured by Orient Chemical Industry Co., Ltd.), Spiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.)
The black dye described in Japanese Patent Application Laid-open No. 9-78361 and Japanese Patent Application Laid-Open No. 59-228259 is also used in Bontron E-81.
, E-84, E-85 (manufactured by Orient Chemical Industry Co., Ltd.), Kaya Charge N-1, N-2, N-3 (manufactured by Nippon Kayaku Co., Ltd.), JP-A-59-8F744, JP-A-59-8F744; Showa 59-50
42, JP-A-59-121055, JP-A-59-125750, JP-A-59-84258, etc., which are colorless or light-colored, can be used.

As a method for locally heating the surface layer of the toner to which the charge-imparting agent has adhered, an instant heating device as disclosed in JP-A-60-117258, a hybridizer (manufactured by Nara Kitan Seisakusho Co., Ltd.), a stirring device such as a Henschel mixer, etc. are used. Various methods can be used, such as heating the surface by stirring the mixture, heating with microwaves, etc.
Any method may be used regardless of the device or means.

Example Examples will be described below.

Adjustment of toner (1) Styrene-'acrylic copolymer resin (softening point (Tm): 135°C, glass transition point ('Tg)
: 58°C): 100 parts by weight Carbon black MA#8 (manufactured by Mitsubishi Chemical Industries, Ltd.) 26 parts by weight Viscoel 550P (manufactured by Mitsubishi Chemical Industries, Ltd.) : 5 parts by weight The above materials were thoroughly mixed in a ball mill. After mixing, the mixture was kneaded on three rolls heated to 130°C. After cooling the kneaded material,
After coarsely pulverizing with a feather mill, pulverizing with a pulverizer using a jet stream, and further classifying with air to obtain an insulating toner 1 having an average particle size of 13 μm.

100 parts by weight of the above toner i and 0.1 part by weight of Nigrosine (manufactured by Bontron N-0 Orient Chemical Industry Co., Ltd.)
The toner was placed in a 0g Henschel mixer and stirred for 2 minutes at a rotational speed of 1500 rpm to adhere nigrosine to the surface of toner i. Next, the particles are dispersed in an air stream heated to 200°C and instantaneously heated for about 1 to 3 seconds to locally melt the surface layer of the toner, fixing nigrosine to the toner surface and forming positively charged toner A. Obtained.

In the same manner, the following parts by weight of Bontron N-01 were added to the insulating toner i to obtain positively charged toners B to F.

In addition, 1 part of Spiron Black TRH (a Cr-containing oil-soluble dye manufactured by Hodogaya Chemical Industry Co., Ltd.) was added to the insulating toner i to obtain negatively charged toners G to K. . In addition,
Toner L () toner 1) that does not allow charge imparting agent to stick
And so.

The amount of the charge imparting agent adhered to the surface of the toner was determined by spectrophotometry as follows.

(2) A calibration curve is determined by determining the absorbance of Nigrosine Base EX at λmax=657 nm using a spectrophotometer using Wako Pure Chemical Industries, Ltd. special grade ethanol as a solvent. The calibration curve obtained at this time is shown in FIG.

■ Weigh approximately 50 JI9 of the toner sample, and
Nigrosine base EX on the toner surface is immersed in 5yQ ethanol and then shaken for an appropriate time.
elute. Ethanol solution is poorly soluble in resin and other components, so it can be used for this measurement.

(2) This eluate is filtered using No. 2J paper to separate the residual toner and the eluate filtrate.

■ The separated eluate was measured using a spectrophotometer to measure λma as in ■.
By determining the absorbance at x=567 nm, the amount of nigrosine base EX per unit toner weight is determined from the calibration curve and the amount of toner sample accurately weighed in (■).

A method similar to the above method can also be applied when quantifying spirone black TRH used as a charge imparting agent.

In addition, Spiron black TRH has λmax=577
Quantification was performed by determining the absorbance in nra.

A calibration curve for Subiron Black TRH is shown in FIG.

Toner adjustment (2) Polyester resin (softening point (Tm): 125°C, glass transition point (T9):
68°C): 100 parts by weight Carbon black M A #8 (manufactured by Mitsubishi Chemical Industries, Ltd.): 5 parts by weight Viscoel TS-200 (manufactured by Mitsubishi Chemical Industries, Ltd.): 2 parts by weight The above materials were ball milled. After thorough mixing, the mixture was kneaded on three rolls heated to 135°C. After cooling the kneaded material,
After coarsely pulverizing with a feather mill, pulverizing with a fine pulverizer using a jet stream, and then classifying with air to determine the average particle size. 1.
Insulating toner 11 with a 5μ shoulder was obtained.

100 parts by weight of the above toner II and nigrosine base E
Toner M-R was prepared by adding the following amounts of X (manufactured by Orient Chemical Industry Co., Ltd.) or Bontron S-34 (manufactured by Orient Chemical Industry Co., Ltd.) in the same manner as in toner preparation (1). Obtained. Note that the toner to which the charge imparting agent was not fixed was designated as toner S() toner ii).

(Hereinafter, blank space) Example 16 100 parts by weight of the insulating toner i with an average particle size of 13 μm obtained in toner preparation (1) and nigrosine (Bontron N
-01: Orient Chemical Industry Co., Ltd.) 1 part by weight was added to Nara Machinery Hybridization System NHS-1 model (
O, M (manufactured by Nara Kikai Seisakusho Co., Ltd.).

Using a dizer, the mixture was mixed and stirred at a rotation speed of 1500 rpm for 2 minutes to adhere nigrosine to the surface of one particle of the insulating toner. Next, using a hybridizer of the same hybridization system, treatment was carried out at 9000 rpm for 3 minutes to fix nigrosine to the surface of the insulating toner 1 to obtain a positively charged toner T.

Example 17 Styrenic polymer particles with very sharp particle size distribution obtained by seed polymerization, particle size 7μ, glass transition temperature 5
4°C, softening point 128°C) and 5 parts by weight of carbon black (manufactured by Mitsubishi Chemical Industries, Ltd.) were placed in a 10 & Henschel mixer and mixed and stirred for 2 minutes at a rotation speed of 1500 rpI+1 to coat the surface of the polymer particles with carbon black. was attached. Next, using a hybridizer of Nara Kikai Hybridization System NH3-1 (manufactured by Nara Kikai Seisakusho Co., Ltd.), treatment was performed at 9000 rpm for 3 minutes to immobilize carbon black on the surface of the polymer particles.

Furthermore, an acrylic resin coating layer was formed by using 100 parts by weight of the carbon black-treated polymer particles and 10 parts by weight of acrylic fine particles MP-1451 (manufactured by Soken Kagaku Co., Ltd., glass transition temperature: 110'C) in the same manner as above. Furthermore, 0.3 parts by weight of a negative charge control agent Spiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.) was added to 100 parts by weight of the polymer particles obtained here, and the toner surface was treated in the same manner as above. to obtain a negatively charged toner U.

Toner adjustment (1) Insulating toner material (styrene)
Acrylic copolymer resin: 100 parts by weight, carbon black MA#8: 6 parts by weight, Viscoel 550P:
5 parts by weight), 2 parts by weight or 5 parts by weight of Nigrosine (Bontron N-01), or Spiron Black TRH:
Adjust the toner by adding 2 parts by weight or 5 parts by weight (1
) was mixed and purified in the same manner as above, then crushed and classified to produce toner V-Y with an average particle size of 13 to 14 μm.
I got it. Incidentally, 0.05 parts by weight of Bontron N-01 was adhered to the surface of toner (1) to obtain positively charged toner Z.

The carrier constituting the developer used in this example is a binder type carrier and is manufactured as follows.

Magnetite (BL-SP: manufactured by Titan Kogyo Co., Ltd.): 500 parts by weight Styrene-acrylic copolymer resin (Prioride ACL: manufactured by Gutsdoyer Chemical Co., Ltd.): 100 parts by weight Nlica #200 (Nippon Aerosil Co., Ltd.) (product) = 2 parts by weight or more of the ingredients were thoroughly mixed in a super mixer, kneaded in a single-sleeve extrusion kneader, cooled and coarsely pulverized, crushed in a hammer mill to an average particle size of 50 μm, and crushed into coarse powder and air classifier in an air classifier. The fine powder was sucked into the tube to obtain an average of 40 μl of microcarriers. When the specific gravity was measured, it was 3.3.

Adjustment of developer and measurement of charge amount and scattering amount (a) Colloidal silica R-972 (manufactured by Nippon Aerosil Co., Ltd.) for 100 parts by weight of each of the above-mentioned toners A to Z: o, t
Surface treatment was performed using rt amount part (this colloidal silica is not fixed to the toner surface). In order to investigate the rise of the toner band Wffi when the surface-treated toner 59 and 27 g of microcarrier were placed in a 50 cc plastic bottle, placed on a rotating stand, and rotated at 120 rpm, the bottles were heated for 3 minutes, 10 minutes, and 30 minutes. The amount of charge after stirring for a minute was measured, and the amount of scattering at that time was also investigated.

The amount of scattering was measured using a digital dust meter model P5H2 (manufactured by Shibata Chemical Co., Ltd.). The dust meter and the magnet roll are
0CIl! After setting the developer 29 on top of this magnet roll, place the magnet 20 on top of the magnet roll.
The dust meter reads the toner particles generated when the toner is rotated at 0 Orpm as dust, and displays the number of counts per minute cpm. Table 1 shows the measurement results of the amount of charge and the amount of scattering.

(The following is a blank space) Table 1 Table 1 (Continued) From the results shown in Table 1, the toner of this example has a low charge amount but rises quickly, and the amount of scattering is small. there were.

It was also confirmed that as the amount of the charge imparting agent was increased, the amount of charge increased in accordance with the amount added, and the amount of scattering also decreased.

On the other hand, in the case of toner in which the number of added parts is increased to 15 parts by weight,
The initial charge (after 3 minutes) is high and the amount of scattering is small, but
As stirring continued, the amount of charge gradually decreased, and the amount of scattering far exceeded the practical level, so it was confirmed that it was not suitable for practical use. This is thought to be because the charge imparting agent that was not sufficiently immobilized was detached by stirring or the like and formed into spent particles on the surface of the carrier, resulting in a decrease in the amount of charge and an accompanying increase in the amount of scattering. The practical level of scattering amount was set at 500 cpm or less.

Further, in the case of a toner containing a charge imparting agent inside, it is possible to impart a charge level sufficient to produce a copy image, but the charge build-up is slow and the amount of scattering is large. Further, it was confirmed that the toner of Example 18, in which the charge imparting agent was fixed to the surface of the toner, had a quick rise in charge and a small amount of scattering.

In addition, toner obtained by attaching a colorant and a low softening point resin for a binder to the surface of a core resin has a low charge amount because the surface is covered with the binder resin and the charge imparting agent is internally added. It is low and the amount of scattering is also large.

Charge amount distribution measurement (b) To measure the charge amount distribution, there was a method announced by Aita et al. of Minolta Camera Co., Ltd. at the 58th Research Conference sponsored by the Electrophotographic Society held on November 28, 1986. A device was used. The details of the principle are described in the materials distributed at the same research discussion group, and will be briefly explained here. FIG. 1 shows its configuration.

The measurement method will be explained below.

The rotation speed of the magnet roll (3) was set to 100 rpm, and the developer used was one after stirring for 30 minutes.

This developer 39 is weighed with a precision balance, and the conductive sleeve (
2) Place it evenly over the entire surface. Next, a bias voltage of 0 to 10 KV is sequentially applied from the bias power supply (4), and the sleeve (2) is rotated for 5 seconds.
Read the potential vI11 when stopped. At this time, the weight of 1 kM i of the separated toner (7) adhering to the cylindrical electrode (1) is measured using a precision balance to determine the average toner charge amount. The second graph is a graph in which the weight percent of the toner mass determined in this way is plotted on the vertical axis, and the charge amount Q/M is plotted as a logarithm on the horizontal axis.
7 to 7.

In addition, in Figures 2 to 7, lθ on the horizontal axis (Q/M)
One scale obtained by dividing the range from 10.degree.

(The following is a blank space) Table 1 The toner of the example in which the charge imparting agent is fixed to the surface has a narrow charge amount distribution and 85% or more of the toner is contained within three channels, but the toner produced by the conventional method has no charge. The distribution of amounts is wide.

Printing durability test (c) The following toner was added to 100 parts by weight of the carrier.
A two-component developer was prepared by mixing at a ratio of ta.

Add the above developer to EP-470Z or EP-570Z (
A printing durability test was conducted using a printer (manufactured by Minolta Camera Co., Ltd.), and the amount of charge and fog at the initial stage and during printing were measured, and the results are shown in Table 3.

Regarding fog, ranking was performed based on image evaluation.

◎, There is almost no background fogging ○, The background fogging is not a practical concern △, The background fogging is noticeable It was confirmed that the toner had a stable charge amount and no fogging was observed.

On the other hand, it has been confirmed that the toner manufactured by the conventional method has an unstable charge amount during printing, and fog increases as the charge amount decreases.

From the above experimental results (a), (b), and (c), it can be seen that the toner of the comparative example with a wide charge amount distribution causes toner scattering and fogging during printing, but the toner of the example has a wide charge amount distribution. It was confirmed that the distribution was narrow and a stable charge amount was obtained, and toner scattering and fogging could be effectively prevented.

Effects of the Invention Since the toner of the present invention has a narrow charge amount distribution and a stable charge amount, fogging and toner scattering do not occur.

[Brief explanation of drawings]

FIG. 1 shows a charge amount distribution measuring device according to the present invention, and FIG.
FIG. 7 shows the measurement results of the charge amount distribution. FIG. 8 and FIG. 9 are diagrams showing calibration curves used in the spectrophotometric method. DESCRIPTION OF SYMBOLS 1... Cylindrical electrode, 2... Conductive sleeve, 3... Magnet roll, 4... Bias power supply, 5... Reference capacitor, 6... Developer, 7...
Separation toner. Patent applicant Minolta Camera Co., Ltd. Agent Patent attorney Aoyama Aoyama and 2 others Figure 1 b: Direction of Rishin's advice

Claims (1)

[Claims] 1. In a black toner for developing electrostatic latent images consisting of at least a thermoplastic resin, a colorant, and a charge imparting agent, this toner is applied to the surface of the core material containing the colorant and/or the charge imparting agent in an amount of 100 parts by weight of the core material. 0.01 to 10 parts by weight of a positive or negative charge imparting agent is added to the surface to electrostatically adhere, and then heat is applied locally to the surface layer to fix the charge imparting agent. A black toner for developing electrostatic latent images.