JPH03220563A - Toner composite - Google Patents

Abstract

PURPOSE:To improve the environmental stability of the electrostatic chargeability of a toner, especially the amt. of electrostatic charges by sticking inorg. fine powder as an additive obtd. by forming a dense coating film contg. amorphous silica on the surface of inorg. fine powder to the surfaces of the toner particles. CONSTITUTION:An additive is stuck to the surfaces of toner particles each composed of a binding resin and a colorant. This additive has a smaller average particle size than the toner particles and is composed of inorg. fine powder and a coating film of amorphous silica or an amorphous silica-alumina mixture stuck to the surface of the inorg. fine powder. Fine powder of rutile type TiO2, other TiO2, ZrO or ZnO may be used as the inorg. fine powder but fine powder of rutile type TiO2 is preferably used. A toner composite having superior environmental stability of the electrostatic chargeability, especially the amt. of electrostatic charges is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic toner composition for developing an electrical latent image.

(Prior Art) Conventionally, electrophotographic developers used to visualize the static Ysa image formed on the electrophotographic photosensitive layer include resins such as polystyrene, styrene-butadiene copolymer, and polyester. A one-component developer consisting of a toner obtained by melt-kneading and pulverizing a pigment or dye such as carbon black or phthalocyanine blue as a coloring agent, or a carrier whose average particle size is the same as that of the toner. A two-component developer is generally used in which a toner is mixed with particles of glass beads, iron, nickel, ferrite, etc. of approximately the same size or up to 500 mm, or particles coated with various resins.

However, these developers alone do not have sufficient properties such as storage stability (blocking resistance), transportability, developability, transferability, and chargeability. Therefore, in order to improve these properties, external additives are often used. As external additives, it is known to use, for example, hydrophobic fine powder such as hydrophobic silica, silica fine particles mixed with alumina or titanium fine particles, or alumina-coated titanium oxide fine particles. There is. (Unexamined Japanese Patent Publication 1986-
129868, Publication No. 57-79961, etc.) (
(Problems to be Solved by the Invention) By the way, by using hydrophobic fine powder such as silica, which is often used at present, storage stability, transportability, developability, transferability, etc. can be considerably controlled. There is a problem that if an amount sufficient for improvement is used, it will adversely affect charging properties. In other words, regarding chargeability, it is required to satisfy requirements such as charge amount, charge rise, charge amount distribution, atomicity, and environmental stability of charge. However, when using silica etc. It has a negative effect on the rise of the charge, the distribution of the amount of charge, the atomicity, and the environmental stability.

On the other hand, if alumina, titanium particles, etc. are mixed into silica particles to improve charge build-up, charge amount distribution, atomicity, and environmental stability, there is a problem that the charge amount becomes extremely low. The tolerance range for satisfying the various physical properties requirements is narrow, the improvement effect is not sufficient, and in particular, the environmental stability of the amount of charge is poor. Further, even when fine particles of titanium oxide or the like are added to fine silica particles, the above-mentioned requirements regarding chargeability are not fully satisfied.

The present invention has been made in view of the above-mentioned problems in the conventional technology. Therefore, the object of the present invention is to
It is an object of the present invention to provide a toner composition that has excellent charging properties, particularly environmental stability of the amount of charging.

(Means for Solving the Problems) The toner composition of the present invention comprises toner particles made of a binder resin and a colorant, and an additive having an average particle size smaller than the toner particles attached to the surface of the toner particles. The additive is characterized by comprising an inorganic fine powder and an amorphous silica film or a mixture film of amorphous silica and alumina attached to the surface of the inorganic fine powder.

The present invention will be explained in detail below.

Examples of the inorganic fine powder used as an additive in the present invention include rutile-type TiO2 and other types of TiO2, Zr01ZnO, and rutile-type TiO2 is particularly preferably used.

Although the average particle size of the inorganic fine powder is not particularly limited, it is necessary that the particle size is smaller than that of the toner particles, and preferably a particle size in the range of 0.005 to 0.2-0.2 is used.

An amorphous silica film or a mixture film of amorphous silica and alumina is formed on the surface of these inorganic fine powders. These films have a dense structure and are physically firmly attached to the surface of the inorganic fine powder, and can be formed, for example, by the method described in Japanese Patent Publication No. 47-45173. . That is, titanium dioxide fine particles are dispersed in water, and a basic compound such as ammonia is added to adjust the pH.
is adjusted to at least 8, then the sodium silicate solution is added slowly with sufficient stirring to maintain alkaline conditions, and water is added if necessary.

After heating the solution at 90° C. for about 1 hour, 10% sulfuric acid is added to gradually lower the pH and precipitate the silica onto the titania particles. After adding sulfuric acid, the mixture was further stirred and aged for at least 1 hour, then filtered, washed, and dried at 125-150°C.
Smash. This treatment causes the silica to precipitate onto the titanium dioxide particles, forming a dense, adhesive, amorphous film.

In the present invention, the coating formed on the inorganic fine powder is
Alumina may be present along with amorphous silica. In that case, the amount of alumina needs to be 25% by weight or less. If the amount of alumina exceeds 25% by weight, the above objectives of the invention will not be achieved.

When alumina is present together with amorphous silica, for example, aluminum sulfate is used and
The film can be formed by the method described in Japanese Patent No. 73.

The additive formed as described above is mixed with toner particles, and the mixing amount in this case is set in the range of 0.1-10% by weight based on the toner particles.

The toner particles using the above additives are not particularly limited, and any particles can be used as long as they are made of a known colorant and a known binder resin.

Binder resins used for toner particles include styrene,
Styrenes such as chlorostyrene, monoolefins such as ethylene, propylene, butylene, isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl acetate, methyl acrylate, ethyl acrylate, butyl acrylate, acrylic α-methylene aliphatic monocarboxylic acid esters such as dodecyl acid, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether, etc. Examples include homopolymers or copolymers of vinyl ketones such as vinyl ether, vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone. Particularly representative binder resins include polystyrene and styrene-alkyl acrylate. Examples include copolymers, styrene-alkyl methacrylate copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-maleic anhydride copolymers, polyethylene, and polypropylene. Furthermore, polyester, polyurethane, epoxy resin,
silicone resin, polyamide, modified rosin, paraffin,
I can give you waxes. Among these, it is particularly effective when polyester is used as the binder resin.

When polyester is used as a binder resin for a toner, it is said that because the polyester itself has negative chargeability, negative chargeability can be obtained without using a chargeability control agent or by using a small amount of chargeability control agent. However, it has a drawback that the charging depends on the environment, that is, there is a large difference in the amount of charging under high temperature and high humidity conditions and under low temperature and low humidity conditions. This is particularly noticeable when a pigment other than carbon black is used as a toner colorant. In the present invention, when polyester resin is used, the above-mentioned drawbacks of polyester resin are eliminated. Although the detailed mechanism is not clear, the negative chargeability of polyester is thought to be due to the carboxyl group, which is a polar group in polyester, or the ester bond, but the chargeability of these polar groups is affected by changes in temperature and humidity. Therefore, even when it is made into a toner, its chargeability is considered to be affected by changes in temperature and humidity.

Furthermore, attempts have been made to improve temperature and humidity changes in charging by adding a charge control agent to the polyester resin, but this is not always sufficient. According to the present invention, the presence of titanium oxide with a silica film formed on the toner surface improves the charge build-up by increasing the uniformity of charge on the toner surface and speeding up charge exchange between toners, especially at low temperature and low humidity. It is thought that the charge distribution can be made sharper.

Toner colorants include carbon black, nigrosine dye, aniline blue, calcoyl blue, chrome yellow, ultramarine blue DuPont oil red,
Quinoline Yellow, Methylene Blue Chloride, Phthalocyanine Blue, Malachite Green Oxalate, Lamp Black, Rose Bengal, C,1, Pigment Red 48:1°C,1, Pigment Red 122, C
11, Pigment Red 57: lSC, 1, Pigment ◆ Yellow 97, C01゜Pigment Yellow 12
, C,1, Pigment Blue 15:lSC,1, Pigment Blue 15:3, etc. can be exemplified as representative examples.

These toner particles may optionally contain a known charge control agent,
Additives such as fixing aids may also be included.

In the present invention, toner particles having an average particle size of less than about 3011 IA, preferably from 3 to 20 microns, can be used.

The electrophotographic toner of the present invention may be a one-component toner developer that does not use a carrier, or may be a two-component developer that uses a carrier.

However, it is preferably used as a two-component developer.

When using a carrier, there is no particular restriction as long as it is a known carrier, and iron powder carriers, ferrite carriers, surface-coated ferrite carriers, magnetic powder dispersed carriers, and the like can be used.

In the electrophotographic toner of the present invention, the additives can be attached to the surface of the toner particles by known means, such as a high-speed mixer.

Specifically, a Henschel mixer, a V-type blender, etc. can be mentioned.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Production of additives 14 g of Tie2 fine powder with a particle size of 15-15 mm was dispersed in 100 cc of pure water, and an ammonia aqueous solution was added to raise the pH to 9.1, and the mixture contained 8% by weight of SiO□ based on TiO□. Add the sodium silicate solution over 2 hours with stirring. The pH at this time was 11.0.

This slurry was diluted with water and heated at 90°C for 1 hour. After that, while stirring the obtained slurry well,
Add 10% sulfuric acid dropwise to lower the pH gradually and add 5in2 to T.
Precipitated onto iO2 microparticles. Next, based on T i O2, a sodium aluminate solution containing the equivalent of 2% by weight Al2O3 is added together with sulfuric acid while adjusting the pH of the slurry with acid so as to maintain it at 3.5. Next, add 50% NaOH solution little by little until the pH of the system reaches equilibrium.
7 and precipitated alumina, filtered, washed, dehydrated, dried, and pulverized. The powder thus treated contained 3% Al2O, 8% 5% Al2O, based on the weight of TiO2.
It contained in2. This fine powder is used as an external additive (a).

Production of toner particles Toner A: 100% by weight styrene butyl methacrylate copolymer (Tg = 85°C, Mn-15000, My-35000) Magenta pigment (C, l, Pigment Red 57>3
Weight % Tetraphenyl Potassium Boron 1 Weight % The above mixture was kneaded with an extruder, pulverized with a jet mill, and then classified with a wind classifier to obtain magenta toner particles of d 50-12-.

Toner B: Linear polyester resin (bis 100% by weight phenolic polyester) (Tg-62°C, Mn-4000, Mv-15000,
Acid value - 12, hydroxyl value - 25) Magenta pigment (C, l,
Pigment Red 57〉3% by weight The above mixture was kneaded with an extruder, pulverized with a jet mill, and then classified with a wind classifier to obtain d 50-1.
274111 magenta toner particles were obtained.

Production of Toner Composition Toner compositions were produced by adding the above additives or additives for comparison to the above toner particles.

To the toner composition, 8,100 parts by weight of toner and 8,018 parts by weight of external additives were added and mixed using a high-speed mixer.

Toner composition 2: To 100 parts by weight of toner A, 1.0 parts by weight of external additive a was added and mixed using a high-speed mixer.

Toner composition 3: To 100 parts by weight of toner A, silica (hydrophobic silica, R9
72, manufactured by Nippon Aerosil Co., Ltd.) was added and mixed using a high-speed mixer.

Toner composition 4: To 100 parts by weight of toner A, silica (hydrophobic silica, R
812, manufactured by Nippon Aerosil Co., Ltd.) and 0.8 parts by weight of titanium oxide (P-25, manufactured by Nippon Aerosil Co., Ltd.) were added and mixed using a high-speed mixer.

Toner composition 5: To 8100 parts by weight of toner, silica (hydrophobic silica, R9
72 (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed using a high-speed mixer.

5 parts by weight of each of the above toner compositions were added to 100 parts by weight of a carrier made of ferrite with a particle size of about 50 uIA coated with methyl methacrylate-styrene copolymer, mixed in a tumbler-shaker mixer, and developed for evaluation. It was used as a drug.

Using these developers, an electrophotographic copying machine (PX-77
90 modified machine, manufactured by Fuji Xerox ■), we conducted a covey test to determine the amount of charge, charge distribution, and reverse polarity toner under high temperature, high humidity (30 degrees Celsius, 85% R1+) and low temperature and low humidity (10 degrees Celsius, 15% R11) environment. The amount was measured. In addition, 1.7 g of toner particles were added to 100 parts by weight of the developer and mixed, and the above-mentioned components were measured after 10 seconds to evaluate the atomicity.

Note that the charge amount is a value obtained from C3G image analysis, and the charge distribution is the 20% charge amount Q (20) of the cumulative integration of the charge distribution.
The difference between and 80% charge amount Q (80) is calculated as 50% charge amount Q (
Value divided by 50): [Q(80)-Q(20))
/Q(50).

The obtained results are shown in Table 1 below.

Example 2 Styrene-〇-butyl meth 97 parts by weight acrylate (70/30) copolymer (Mn - about 7000, My - about 40000) Cyan pigment (β-type phthalocyanine C,1, PIglent Blue 15:3)
After melting and mixing 3 parts by weight of the above components, they were finely pulverized and classified to produce cyan toner particles having an average particle size of 12 m. The cyan toner particles exhibited good fluidity.

8017 parts of the external additive used in Example 1 was mixed with 100 parts by weight of the cyan toner particles using a high-speed mixer to obtain a cyan toner composition.

Methyl methacrylate to ferrite with a grain size of 50-
6 parts by weight of the above cyan toner composition were mixed with 100 parts by weight of a carrier coated with a styrene copolymer to obtain a developer.

Using this developer, a copy test was conducted using a copying machine (PX4700, manufactured by Fuji Xerox ■), and the results ranged from high temperature and high humidity (30°C, 85% R11) to low temperature and low humidity (10°C).
, no stains in the background under conditions up to 15%R11),
High-density, high-quality images were obtained from the beginning. Further to, o
o.

When continuous copying was performed, almost no change in image quality was observed. The results are shown in Table 2.

Examples 3 and 4 3 parts by weight of the cyan pigment of Example 2 was replaced with magenta pigment (Brilliant Carmine 6B, C,1, Plgaent R
ed57) 3 parts by weight, and yellow pigment (Disazo Yellow, C,1, Plgaent Yellow 12
) 3 parts by weight, and the same method was used to reduce the average particle size to 12
- magenta toner particles and yellow toner particles were obtained.

The above magenta toner particles and yellow toner particles 1
00 parts by weight, respectively, the external additive a used in Example 2
1.0 part by weight was added and mixed using a high speed mixer to obtain a magenta toner composition (Example 3) and a yellow toner composition (Example 4).

These toner compositions exhibited good flowability.

A developer was prepared in the same manner as in Example 2, and a copy test was conducted in the same manner. Under conditions ranging from high temperature and high humidity to low temperature and low humidity, high-density, high-quality images were obtained with no background stains. . Furthermore, when io and ooo copies were made continuously, almost no change in image quality was observed. The results are shown in Table 2.

Example 5 Styrene-n-butyl meth 96 parts by weight acrylate (70730) copolymer (Mn - about 7000, My - about 40000) Cyan pigment (β-type phthalocyanine C,1, Plgsent Blue 15:3)
3 parts by weight Cetylpyridinium chloride 1 part by weight The above components were melted and mixed, then finely pulverized and classified to produce cyan toner particles having an average particle size of 12a.

1.0 parts by weight of the external additive a used in Example 1 was mixed with 100 parts by weight of the cyan toner particles using a high-speed mixer to obtain a cyan toner composition.

A developer was obtained by mixing 3 parts by weight of the above cyan toner composition with 100 parts by weight of a carrier coated with a methyl methacrylate-styrene copolymer on ferrite having a particle diameter of 100 m.

Using this developer, a copy test was conducted in the same manner as in Example 2, and under conditions ranging from high temperature and high humidity to low temperature and low humidity, images with high density and good quality were obtained from the initial stage without staining in the background area. Furthermore, when to and ooo copies were made continuously, almost no change in image quality was observed. The results are shown in Table 2.

Comparative Example 1 In Example 2, instead of 8017 parts by weight of the external additive,
A toner composition was obtained in the same manner as in Example 2, except that 0.8 parts by weight of hydrophobic silica (R972, manufactured by Nippon Aerosil Co., Ltd., primary particle size 18 ann) was used.

A developer was prepared in the same manner as in Example 2, and a copy test was conducted in the same manner. When the developer was prepared in the same manner as in Example 2, the background area was severely stained under high temperature and high humidity conditions, and the image density was low under low temperature and low humidity conditions. The results are shown in Table 2.

Comparative Example 2 In Example 2, instead of 8017 parts by weight of the external additive,
A toner composition was obtained in the same manner as in Example 2, except that 0.4 parts by weight of hydrophobic silica (R972, manufactured by Nippon Aerosil Co., Ltd., carbon particle size: 16 sa) was used.

A developer was prepared in the same manner as in Example 2, and a copy test was conducted in the same manner. As a result, staining occurred in the background under high temperature and high humidity conditions, and the image density slightly decreased under low temperature and low humidity conditions. These results are shown in Table 2.

In Table 2, regarding stains in the background area, ◯ means that no stains were generated, △ means that stains were slightly generated, and X means that stains were significantly generated.

(Effects of the Invention The toner composition of the present invention has, as described above, an inorganic fine powder in which a dense film containing amorphous silica is formed on the surface of the toner particles attached as an additive. The charging properties are improved, especially the environmental stability, and the charge distribution range is narrow in environments ranging from high temperature and high humidity to low temperature and low humidity, and even when used continuously for a long period of time, it maintains a high charge amount, Copy images with stable image quality and no fog can be obtained with less generation of polar toner.

Claims (3)

[Claims] (1) Toner particles consisting of a binder resin and a colorant, and an additive having an average particle size smaller than that of the toner particles adhered to the surface of the toner particles, and the additive has an inorganic fine powder and an inorganic fine powder. A toner composition comprising an amorphous silica film or a mixture film of amorphous silica and alumina attached to the surface of a fine powder. (2) The toner composition according to claim (1), wherein the binder resin is a polyester resin. (3) The toner composition according to claim (1), wherein the inorganic fine powder is a rutile-type titanium dioxide fine powder.