JPH06175404A - Toner for developing electrostatic image and method for producing the same - Google Patents

Abstract

PURPOSE:To reduce generation of fogging and scattering of a toner as well as improving an electrostatic charge building up property and stability of picture image density at the time of continuous use by containing a granulating carbon black with specified ultraviolet absorbance and specified particle hardness. CONSTITUTION:At least a resin and a granulating carbon black are contained. As the favourable resin, there are styrene resin, saturated or unsaturated polyester resin and epoxy resin. The ultraviolet absorbance of the carbon black is made to be 0.05 or less, favourably 0.04 or less. The granulating carbon black is manufactured in a compression granulation method, and load to compress a material carbon black is selected as particle hardness of the granulating carbon black after compression to be 2g or less in average and favourably 0.1-1g. The rough injection density of the granulating carbon black is selected to be 0.10-0.50g/cc or favourably, 0.15-0.45g/cc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge image developing toner used in electrophotography, electrostatic recording and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A developer used in an electronic copying machine or the like is once attached to an image carrier such as a photoconductor on which an electrostatic charge image is formed in the developing process, and then is transferred to the photoconductor in the transferring process. After being transferred from the sheet to the transfer sheet, it is fixed on the copy sheet surface in the fixing step. At that time, as a developer for developing the electrostatic charge image formed on the latent image holding surface, a two-component developer consisting of a carrier and a toner and a one-component developer not requiring a carrier (magnetic toner, non-magnetic toner). ) It has been known.

Toners contained in the developer include positively chargeable toners and negatively chargeable toners. Conventionally, as those imparting chargeability to positively chargeable toners, nigrosine dyes and quaternary ammonium salts have been used. Further, as a material for imparting chargeability to a negatively chargeable toner, a charge control agent such as a metal-containing dye or a coating agent for imparting a predetermined chargeability to a carrier has been known.

[0004]

With conventional toners, carbon black often fly during the handling of raw materials in the toner manufacturing process, causing problems such as environmental pollution around the operator's body and the workplace, and in the resin of the toner. There is a problem that the toner charging characteristics cannot be maintained at a high level because carbon black is not properly dispersed at a stable level, and one means for solving these problems was proposed in Japanese Patent Application No. 4-52784 filed earlier. . However, even these toners have insufficient charging characteristics such as charge rising property, charge amount distribution, and charge retention property, and there is a problem to be further improved.

For example, the charge build-up property of the toner (the time from when the copier or the like is started to start mixing with the carrier until a predetermined charge amount is obtained), the stability of the image density during continuous use, and the occurrence of fog Problems such as (image stains) and the occurrence of stains inside the machine due to toner scattering inside the copier have been problems. As another example, it is difficult to maintain a suitable chargeability of the toner irrespective of environmental conditions (temperature, humidity, etc.), and to obtain a form in which the change with time of the chargeability is preferable. When changed and used in a copying machine or the like, there are problems such as stability of image density, occurrence of image stain such as fog, and occurrence of stain inside the machine due to toner scattering.

An object of the present invention is to provide a toner having a good charge rising property of the toner, good stability of image density during continuous use, and less fog generation or stain inside the copying machine due to toner scattering. Especially. Another object of the present invention is to provide a toner capable of obtaining appropriate chargeability and stable image density regardless of environmental conditions such as temperature and humidity, and having less fog and toner scattering.

Another object of the present invention is to provide a toner having a small amount of opposite polarity toner and a good charge amount distribution and excellent charging characteristics. Another object of the present invention is to provide a toner that causes less flying of carbon black when handling raw materials and reduces problems such as environmental pollution.

[0008]

Means for Solving the Problems As a result of intensive studies on such a problem, the present inventors have found that the granules have a specific ultraviolet absorbance and are appropriately adjusted in hardness, density and crushability (dispersibility). It has been found that the use of the carbon black thus obtained provides a toner having excellent charging characteristics such as imparting an appropriate charge control effect to the toner, less reverse polarity, and exhibiting a good charge amount distribution. The invention was reached. (1) A toner for developing an electrostatic charge image, which comprises at least a resin and granulated carbon black having an ultraviolet absorbance of 0.05 or less and a particle hardness of 2 g or less. (2) The coarse packing bulk density of the granulated carbon black is 0.1.
The toner for developing an electrostatic charge image according to item 1, which is 0 to 0.50 g / cc. (3) The toner for developing an electrostatic image according to item 1, wherein the granulated carbon black is a granulated carbon black produced by a compression granulation method.

[0009]

The present invention will be described in detail below. As the resin component that can be used in the present invention, known types suitable for toner can be used. For example, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer,
Styrene-butadiene copolymer, styrene-chlorinated copolymer, styrene-vinyl acetate copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene -Butyl acrylate copolymer, styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-
Ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic ester copolymer, etc. Styrene resins (styrene or styrene-substituted homopolymers or copolymers), vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane Resins, silicone resins, ketone resins, ethylene-ethyl acrylate copolymers, xylene resins, polyvinyl butyral resins, polycarbonate resins and the like are available, but styrene resins and saturated resins are particularly preferred resins for use in the present invention. Can either be unsaturated polyester resin and epoxy resin are exemplified. Further, the above resins are not limited to be used alone, but may be used in combination of two or more kinds.

Furthermore, the cross-linking binder resins described in JP-B-51-23354 and JP-A-50-44836, or JP-B-55-6895 and JP-B-63.
The non-crosslinked binder resin described in Japanese Patent No. 32180 can also be used. Further, the glass transition temperature of the binder resin for toner has a transition start temperature (inflection point) of 50 ° C. or higher when measured by a thermal analysis method (differential thermal analysis device, differential scanning calorimetric analysis device, etc.). preferable. When the glass transition temperature is lower than 50 ° C., when the toner is left at a high temperature of 40 ° C. or higher for a long time, the toner may be agglomerated or adhered to cause a problem in use.

As the colorant used in the present invention, at least carbon black is used, and other conventionally used colorants may be used in combination without any particular limitation. Any other suitable pigment or dye may be used as the other colorant. For example, titanium oxide, zinc white, alumina white, calcium carbonate, navy blue, carbon black, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine dye, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallyl methane dye, Anthraquinone dyes, monoazo and disazo dyes and pigments may be used alone or in combination with a colorant corresponding to the color of the toner.

The content of the colorant may be an amount sufficient to color the toner so that a visible image can be formed by development, and is, for example, 1 to 20 parts by weight based on 100 parts by weight of the resin. Is preferred. Further, preferably 3 to 15 parts by weight is suitable. The UV absorbance of the carbon black used in the present invention is 0.05 or less, preferably 0.04.
If it is higher than 0.05, the charging property of the toner becomes poor, which is not preferable. That is, the inventors of the present invention focused on limiting the ultraviolet absorbance of carbon black, particularly the toluene extract, to a specific value or less.

UV absorption of carbon black (λc)
Is calculated by the following method. First, 3 g of carbon black was sufficiently dispersed and mixed in 30 ml of toluene, and then this mixed solution was mixed with No. Filter using 5C filter paper. After that, the filtrate was put in a quartz cell having a 1 cm square light-absorbing part and the value (λs) at which the absorbance at a wavelength of 336 nm was measured using a commercially available ultraviolet spectrophotometer, and the value at which the absorbance of toluene alone was measured as a reference by the same method. From (λo), the ultraviolet absorbance is determined by λc = λs−λo.

Examples of commercially available spectrophotometers include an ultraviolet-visible spectrophotometer (UV-3100PC) manufactured by Shimadzu Corporation. The carbon black of the present invention is preferably manufactured by the furnace method. Also, carbon black B
The specific surface area due to nitrogen adsorption by the ET method is 20 to 500 m ^2.
/ G, dibutyl phthalate (DBP) oil absorption is 30 ~
The range of about 150 ml / 100 g is preferable. In particular, if the BET specific surface area is lower than 20 m ² / g, the particles become too large and the dispersibility of carbon black deteriorates.
On the other hand, if it is higher than 500 m ² / g, the particles will be finely divided and it will be difficult to apply shear during kneading, resulting in poor dispersion of carbon black. Considering further improving the dispersibility of carbon black in the resin during toner kneading, the specific surface area is 80
~ 150m ² / g, DBP oil absorption is 50 ~ 120ml
/ 100 g is preferable.

Further, in order to improve the charging characteristics of the toner,
Acidic carbon black is particularly preferable. Acidic carbon black refers to one having a value of 6 or less when the pH of a suspension after boiling carbon black and pure water is measured,
More preferably, the pH is 5 or less. In order to adjust the pH to 6 or less, the carbon black may be subjected to an oxidation treatment by a known method, and it is presumed that the presence of an oxidizing compound on the surface of the carbon black increases the miscibility of the resin and the carbon black in the toner. To do. Acid type carbon black manufactured by the furnace method includes MA7, MA8, MA11, MA100, # manufactured by Mitsubishi Kasei.
1000, # 2200B, # 2350, # 2400B
Etc., MOGUL L, REGAL 4 made by Cabot
00R, MONARCH 1000, etc. Colombian REVEN series 1035, 1040, 125
5,3500 and the like are listed as specific examples, and in order to reduce the ultraviolet absorbance of these carbon blacks, for example, reduction of impurities in the raw materials used, manufacturing conditions by the furnace method (for example, processing flow rate, processing time, etc.) Should be properly managed.

The raw material of the granulated carbon black used in the present invention is not particularly limited as long as it is the granular carbon black having the above-mentioned UV absorbance of 0.05 or less. A method for granulating granular carbon black is described in, for example, Japanese Patent Application Laid-Open No. 2-1.
No. 42858, Japanese Patent Laid-Open No. 3-193129, it is preferable to carry out by a compression granulation method using a compression granulation device such as a roll compression molding machine. The raw material granular carbon black preferably has a BET specific surface area of 50 to 500 m ² / g.

The load for compressing the raw material carbon black is
Considering the bulk density and particle size of the raw material, the average hardness of the granulated carbon black after compression is 2 g or less, preferably 0.1 to
1 g, and further, the rough packing density is 0.10 to
0.50 g / cc, preferably 0.15-0.45 g /
It may be appropriately selected so as to be cc. When the coarse packing density is 0.10 g / cc or less, carbon is often scattered, the bulk density of the raw material is increased, the shear during kneading is less likely to occur, the dispersibility is deteriorated, and the toner performance is deteriorated. When the bulk packing bulk density is 0.50 g / cc or more, the handling property of carbon is good, but the cohesive force of carbon increases too much, sufficient dispersibility cannot be obtained during kneading, and the toner performance deteriorates. Further, the stability of the image density during continuous copying / printing of toner, the stability of fog, and the state of toner scattering are favorably improved by using the granulated carbon having a particle hardness of 2 g or less according to the present invention.

<Testing Method> The coarse packing bulk density is based on the method for measuring the apparent specific gravity of granulated carbon black according to JIS K6221, and the unit is g / cc. The hardness of the granulated particles is measured according to the hardness measurement method of the granulated carbon black according to JIS K6221, and the unit is g.
Expressed as

For the purpose of surface modification, carbon black may be subjected to surface treatment with metal soap or the like, if necessary, and may be used in combination with untreated one and surface treated one. . Alternatively, the granulated carbon black of the present invention may be used in combination with the granular carbon black, or the different types of carbon black may be used in combination with other colorants (dye, pigment, etc.).

Further, the toner of the developer of the present invention may use a known positively or negatively chargeable charge control agent alone or in combination, and the amount thereof is selected depending on the desired charge amount. Well, the addition amount of the charge control agent is preferably about 0.05 to 10 parts by weight with respect to 100 parts by weight of the resin. Examples of positively chargeable charge control agents include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, imidazole compounds, and polyamine resins. As a negatively charged control agent, Cr, Co, Al, F
Examples thereof include metal-containing azo dyes such as e, metal salicylate compounds, and metal alkylsalicylate compounds.

In addition, as a toner constituent component of the developer of the present invention, in order to improve fixability and fluidity, additives such as low molecular weight olefin polymer and fine powder of silica, alumina, titania, etc., and resistance adjustment and lubricants. For the purpose of magnetite, ferrite, cerium oxide, strontium titanate, inorganic fine powder such as conductive titania, styrene resin,
Organic fine powder such as acrylic resin may be contained as an internal additive or an external additive. The amount of these additives used may be appropriately selected depending on the desired performance, and for example, is preferably about 0.05 to 10 parts by weight with respect to 100 parts by weight of the resin.

As the method for producing toner particles of the developer of the present invention, various conventional toner production methods can be applied. For example, as a general example, first, a resin, a colorant,
Wax, charge control agent, etc. are uniformly dispersed and mixed in a mixer,
Next, the mixture is melt-kneaded by a closed kneader or a single-screw or twin-screw extruder, cooled, crushed by a crusher, hammer mill, etc., finely crushed by a jet mill, high-speed rotor rotary mill, etc. The classification may be performed with a classifier (for example, an inertia classification type elbow jet, a centrifugal classification type microplex, a DS separator, etc.). The average particle size of the toner is preferably 3 to 20 μm.

When the toner is externally added, the classified toner and the external additive are mixed with a high-speed stirrer (Henschel mixer,
It may be mixed by stirring with a super mixer, etc.). The toner of the obtained developer of the present invention does not use a carrier.
It can also be used as a component type developer (a magnetic one-component toner containing a magnetic substance such as magnetite or a non-magnetic one-component toner containing no magnetic substance).

When the toner of the present invention is used in a two-component developer, it may be used by mixing it with a magnetic carrier. As the magnetic carrier, iron powder, ferrite powder, magnetic resin having an average particle size of about 20 to 200 μm can be used. A conventionally known carrier such as a carrier can be used. Further, a known silicone resin, acrylic resin, fluorine resin, styrene resin, epoxy resin, polyester resin, polyamide resin, or the like, or a mixture of these resins is coated on the surface in a single layer or multiple layers. You can also use the ones.
In addition, as a ferrite core material, a general formula (MO) _m (F
e ₂ O ₃ ) _n ferrite powder is preferable, and (M
O) components include CuO, ZnO, NiO, FeO,
One or more components such as MnO, MgO, and BaO may be selected and used.

The carrier particle size is not particularly limited, but those having an average particle size of 10 to 200 μm are preferable. The mixing ratio of the carrier and the toner is preferably 5 to 100 parts by weight of the carrier with respect to 1 part by weight of the toner.

[0026]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, simply "parts" means "parts by weight".

[0027]

Table 1 <Example 1> Styrene / n-butyl acrylate = 82/18 copolymer resin 100 parts (flow softening temperature 130 ° C, glass transition temperature 61 ° C) Colorant carbon black S granulated product 6 parts ( Mitsubishi Kasei Co., UV absorbance 0.02, BET specific surface area 130 m ² / g, DBP oil absorption 100 ml / 100 g, pH 3, bulk density 0.28 g / cc ・ Low molecular weight polypropylene 550P 2 parts (manufactured by Sanyo Kasei Co., Ltd.) ) ・ Charging control agent Hongtron P51 1 part (Orient Chemical Co., Ltd., quaternary ammonium salt) was blended, kneaded using a continuous twin-screw extruder, cooled, crushed, classified, and averaged particles A black toner a having a diameter of 9.5 μm was obtained. To 100 parts of this black toner a, 0.2 part of silica powder (R972 manufactured by Nippon Aerosil Co., Ltd.) and 0.3 part of magnetite powder (average particle size 0.3 μm) are externally added with a Henschel mixer to give toner A. Obtained. The obtained toner A (4 parts) and a resin containing methyl silicone were surface-coated with an average particle diameter of 100 μm and a saturation magnetization of 55 emu / g.
96 parts of the Cu-Zn ferrite carrier of No. 1 were mixed and stirred to prepare a developer A.

Next, using the starting developer A and the replenishment toner A as an organic photoconductor as a photoconductor, a heat roll fixing system, a blade cleaning system, and a toner replenishment control to the developer in the developing tank are controlled. A copying machine with a normal development method (photoconductor surface potential; normal mode DC-700V, photo mode DC-500V, bi-eye voltage DC-200V) with a copying speed of 50 sheets (A4) / min, which employs a permeability sensor method. Environmental temperature 23-25 ° C, humidity 50-5
A live-action test of 5,000 sheets was carried out in an environment of 5% RH.

As a result of this actual copying test, the copy image density is stable and high even during the actual copying of 5,000 sheets, and there is no increase in fog which is a stain on the white background portion of the copy. It was a developer and toner excellent in durability and copy image stability even after continuous copying. Figure 1 shows live-action data in a normal environment. Further, the charge rising characteristic of Toner a was good as shown in FIG.

Comparative Example 1 Colorant Carbon black N Granulated product 6 parts (manufactured by Mitsubishi Kasei Co., UV absorbance 0.10, BET specific surface area 130 m ² / g, DBP oil absorption 100 ml / 100 g, pH 3, bulk) Density 0.28 g / cc) Toner b was produced in the same manner as in Example 1 except that the above colorants were used, and toner B was further added externally, and toner B and a carrier were mixed and stirred to give developer B. Then, the same 50,000-sheet live-copy test as in Example 1 was performed in a normal environment.

As a result, the image density stability in the photographic mode was poor, the initial fog was high, and the amount of scattered toner on the bottom of the developing tank was large (the amount of scattered toner was about four times that of Example 1), Further, the transfer efficiency was slightly poor, and there was a problem in the durability performance during copying and the stability of copy image quality. Fig. 2 shows live-action data in a normal environment. Further, the charge rising characteristic of the toner b was slightly worse than that of the toner a. (See Figure 3)

[0032]

<Example 2> Styrene / n-butyl acrylate = 85/15 copolymer resin 100 parts (flow softening temperature 128 ° C., glass transition temperature 60 ° C.) Colorant carbon black S granulated product 6 parts ( Mitsubishi Kasei Co., UV absorbance 0.02, BET specific surface area 130 m ² / g, DBP oil absorption 100 ml / 100 g, pH 3, bulk density 0.28 g / cc) Low molecular weight polypropylene NP-505 2 parts (Mitsui Petrochemical (Manufactured by the company) ・ Charge control agent Hongtron S51 1 part (manufactured by Orient Chemical Industry Co., Ltd., quaternary ammonium salt) was blended, kneaded using a large continuous twin-screw extruder, cooled, crushed, and classified. A black toner c having an average particle diameter of 9.0 μm was obtained. To 100 parts of this black toner c, 0.3 part of silica powder (R972 manufactured by Nippon Aerosil Co., Ltd.) and 0.2 part of magnetite powder (average particle size 0.3 μm) are externally added with a Henschel mixer to give toner C. Obtained. The obtained toner C (4 parts) and a resin containing methyl silicone were surface-coated with an average particle diameter of 100 μm and a saturation magnetization of 55 emu /
96 parts of Cu-Zn ferrite carrier of g was mixed and stirred to prepare a developer C. Then, as in Example 1, 5
A 10,000-sheet live-copy test was performed in a normal environment. As a result of this actual copying test, the toner and the developer were excellent in durability performance and copy image stability as in Example 1. In addition,
The photographed data is shown in FIG. Further, the charge amount rising characteristic of the toner c was good as shown in FIG.

Comparative Example 2 Colorant Carbon black N Granulated product 6 parts (manufactured by Mitsubishi Kasei Co., UV absorbance 0.10, BET specific surface area 130 m ² / g, DBP oil absorption 100 ml / 100 g, pH 3, bulk) Density 0.28 g / cc) Toner d was prepared in the same manner as in Example 2 except that the above colorants were used, and toner D was externally added to the toner D and the carrier D was mixed and stirred to give the developer D. Then, the same 50,000-sheet live-copy test as in Example 2 was carried out in a normal environment.

As a result of this actual shooting test, the change in image density in the photographic mode was large, the amount of toner scattered on the bottom of the developing tank was a little large, and the transfer efficiency was also a little bad, and the durability performance during copying and the stability of copy image quality were improved. There was a problem. Note that the photographed data is shown in FIG. Further, the charge rising characteristics of the toner d tended to decrease from the middle, and were inferior to those of the toner c. (See Figure 4)

[0035]

<Table 3><Simple description of measurement method, etc.> Image density: A value obtained by measuring a black portion on which an image is formed with a Macbeth reflection densitometer. Fog: For the stains on the white background where no image is formed, the whiteness (Wb) of the Hunter paper before and after actual copying of the paper used was measured using a Nippon Densoku color difference meter, and the value obtained from the difference before and after that was taken as the fog. Toner charge amount: The developer was sampled and measured with a Toshiba chemical blow-off charge amount measuring device. Toner concentration: The developer was sampled, the toner was removed, and the toner concentration was determined by gravimetric analysis. Toner consumption: The weight of a toner replenishing device containing replenishment toner was measured, and the amount of change in weight was calculated. Transfer efficiency: The toner on the photoconductor is collected in a toner collecting device by blade cleaning, the weight of the collecting device is measured, and the toner collecting amount is obtained from the change in the weight. Then
The toner transfer efficiency was calculated by the following formula.

[0036]

[Equation 1]

[0037]

[Chart 4] Charge build-up characteristics: 4 parts of toner and 96 parts of ferrite carrier (F-100 made by Powdertech Co., Ltd.) are mixed and stirred under a normal environment, and the toner charge amount is measured by a blow-off charge amount measuring device made by Toshiba Chemical Co. Was measured using. Normal environment (hereinafter abbreviated as NN): Temperature 23 to 25
Environment of ℃, humidity 50-55% RH.

[0038]

EFFECT OF THE INVENTION The developer for developing an electrostatic image of the present invention has a good distribution of charge amount, good charging performance such as always exhibiting proper and stable chargeability, and a stable image even when continuously used. Great industrial benefits such as high density, no image stains such as fog, little pollution due to toner scattering in printers and copiers, and stable maintenance of stable image characteristics against environmental changes. Is provided.

[Brief description of drawings]

FIG. 1 is data obtained when a 50,000 copy actual copying test was performed in a normal environment of Example 1.

FIG. 2 shows data obtained when a 50,000 copy actual copying test was performed in a normal environment of Comparative Example 1.

FIG. 3 shows the charging rising characteristics of toner a of Example 1 and toner b of Comparative Example 1.

FIG. 4 shows charging rising characteristics of toner c of Example 2 and toner d of Comparative Example 2.

FIG. 5 shows data obtained when a copy actual copying test of 50,000 sheets was performed in a normal environment of Example 2.

FIG. 6 shows data obtained when a 50,000-copy actual copying test was performed in a normal environment of Comparative Example 2.

Claims (4)

[Claims] 1. A toner for developing an electrostatic charge image, comprising at least a resin and granulated carbon black having an ultraviolet absorbance of 0.05 or less and a particle hardness of 2 g or less. 2. The toner for developing an electrostatic charge image according to claim 1, wherein the coarsely packed bulk density of the granulated carbon black is 0.10 to 0.50 g / cc. 3. The toner for developing an electrostatic charge image according to claim 1, wherein the granulated carbon black is a granulated carbon black produced by a compression granulation method. 4. A resin and an ultraviolet absorbance of at least 0.
A method for producing a toner for developing an electrostatic charge image, which comprises a step of mixing and kneading a granulated carbon black having a particle hardness of 05 or less and a particle hardness of 2 g or less.