JPH09329910A - Electrostatic charge image developing toner and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an object to be copied which has a good flow property, caking resistance, image density, fogging and gradation characteristic, is free from brushing stripes, drop-out, filming, stripe-like image defects and cleaning defects and has high images and high image quality by incorporating titanium dioxide subjected to a surface treatment by trimethylol ethane. SOLUTION: The titanium dioxide subjected to the surface treatment by the trimethylol ethane is incorporated into the electrostatic charge image developing toners consisting of at least a resin and coloring agents. The surface treatment of the titanium dioxide by the trimethylol ethane is executed by mixing, for example, the trimethylol ethane alone or, if desired, the trimethylol ethane dissolved in a solvent, with the non-treated titanium dioxide, without heating or under heating, in a dispersing device, such as a Henschel blender or ball mill. The mixture is thereafter subjected to processes, such as cooling, drying, pulverizing, sieving, etc., at need, by which the titanium dioxide surface treated with the trimethylol ethane is obtd.

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 for developing an electrostatic latent image formed in electrophotography, electrostatic recording or the like.

[0002]

2. Description of the Related Art A developer used in an electronic copying machine or the like is once attached to an electrostatic charge image carrier such as a photoconductor on which an electrostatic charge image is formed in the developing process, and then in a transfer process. After being transferred from the photoreceptor to the transfer paper, it is fixed 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 Magnetic toner) is known.

Toners contained in the developer include positively chargeable toners and negatively chargeable toners. Conventionally, as those imparting positively chargeable property to the toners, nigrosine type dyes, quaternary ammonium salts and the like have been used. A charge control agent as an additive to a toner and a carrier coating agent that imparts a positive chargeability to the toner are known, while a metal-containing azo dye is used to impart a negative chargeability to the toner. Charge control agents such as the above, carrier coating agents that impart negative chargeability to the toner, and the like are known.

Further, the toner has good flowability, storage stability, and
It is essential to have environmental resistance, and for the purpose of imparting such properties, a method of mixing inorganic fine powder such as various metal oxides with toner particles has been proposed, and such inorganic fine powder Examples include titanium dioxide, silica, aluminum oxide, zinc oxide, magnesium oxide, cerium oxide, iron oxide, copper oxide, tin oxide and the like. It is known that these inorganic fine powders have a strong correlation with the dispersibility of the fine powders, such as the fluidity imparting effect, storage stability improving effect, environmental resistance improving effect, and charging property imparting effect given to the toner. . Generally, if the proportion of secondary agglomerates in the inorganic fine powder is large and the dispersibility is non-uniform, the desired properties of fluidity and caking resistance may not be obtained, or the chargeability may become non-uniform. May occur, or toner may adhere to or form a film on the photoconductor to form black spots on the copy image, or cleaning failure may occur. In addition, the chargeability of the developer may deteriorate with time, and the image quality may deteriorate.

As one of the methods for improving the poor dispersion of the inorganic fine powder which causes the deterioration of the image quality, physical or chemical surface treatment is applied to the primary particles of the inorganic fine powder,
Reduces the surface energy of the primary particles, prevents secondary aggregation,
Many methods for improving dispersibility have been proposed. Among such surface treatment methods, examples of chemical surface treatment methods include organic compound treatment, organic acid treatment, alcohol treatment, alumina treatment, silane treatment, and silicon treatment.

However, even if an inorganic fine powder having good dispersibility is obtained by such a treatment,
If the charging property of the fine powder is not good for addition to the toner, it will not be an effective toner additive. Generally, a good charging property to be added to a toner is a substance having a high charging speed, a narrow charge amount distribution, and a stable charge amount over a long period of time. If the charging speed is slow, the image density is likely to decrease due to an increase in the amount of charge in the early stage of aging, and if the distribution of the amount of charge is wide, the proportion of reverse polarity toner tends to increase, and the fog on the white background tends to increase. Further, if the charge stability is poor, the change in the charge amount when copying or printing for a long time is large, and the image quality such as image density and background fog may not be stable.
Therefore, in order to obtain the inorganic fine powder having good dispersibility and chargeability by the chemical surface treatment, selection of the surface treatment agent is most important.

[0007]

SUMMARY OF THE INVENTION The first object of the present invention is to provide a surface-treated titanium dioxide excellent in dispersibility and charging property, which solves the above-mentioned problems in the case of adding an inorganic fine powder to a toner. By adding, it has excellent fluidity and anti-caking property, good image density and fog, excellent gradation, no image defects such as brush marks, chips, filming and streak image defects, and no cleaning defects. , High image,
An object of the present invention is to provide a toner capable of obtaining a high quality copy.

A second object of the present invention is to provide a stable image / image quality even when repeatedly copied and printed repeatedly, less scattering in the machine, high transfer efficiency, stable toner consumption, and durability. It is to provide a toner having excellent economical efficiency. A third object of the present invention is to provide a toner having a wide usable environment range, which is excellent in high temperature storage stability and durability under high temperature and high humidity.

[0009]

As an additive to an electrostatic image developing toner, titanium dioxide is a substance whose effect has been widely recognized together with silica, alumina, and the like.
There has been proposed a method of using titanium dioxide fine powder which is used alone or treated with an organic compound, an organic acid, an alcohol, an alumina, a silane and a silicon as a toner additive. However, with the conventional technology, it is difficult to obtain surface-treated titanium dioxide having good dispersibility and good charging characteristics to be added to the toner. Even if the dispersibility is good, the charging speed is insufficient. On the contrary, in many cases, the dispersibility was insufficient even though the charging property was good.

In order to solve the above problems, the present inventors have
As a result of diligent investigation of surface-treated titanium dioxide having good dispersibility and good charging characteristics for addition to the toner, the addition of the surface-treated titanium dioxide with trimethylolethane shows that the image characteristics of the toner are improved. It was found that the high temperature storability and the durability under high temperature and high humidity can be greatly improved. In particular, trimethylolethane has a high melting point of 199 to 201 ° C. and is a stable substance in the environment where a developer is normally used. Titanium dioxide surface-treated with this substance has a high charging rate and is added to a toner. As a result, it was found that the high temperature storability and the environmental resistance such as high temperature and high humidity environment were significantly improved.

That is, the gist of the present invention is to provide an electrostatic charge image developing toner comprising at least a resin and a colorant,
A toner for developing an electrostatic charge image comprising titanium dioxide surface-treated with trimethylolethane.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The surface treatment of titanium dioxide with trimethylolethane is carried out, for example, by dissolving trimethylolethane alone or, if desired, dissolving trimethylolethane in a solvent and using a disperser such as a Henschel blender or a ball mill. It is carried out by heating with or without mixing with the treated titanium dioxide. Then, if necessary, trimethylolethane surface-treated titanium dioxide is obtained through a process such as cooling, drying, pulverizing, and sieving. Trimethylolethane and titanium dioxide may or may not be chemically bonded.

The titanium dioxide used may be of the rutile type, anatase type, amorphous, or a mixture, regardless of the crystalline type. Surface treatment amount is 0.1-10% by weight
Is particularly preferable, and 0.5 to 5% by weight is particularly preferable. Further, the primary particle size of titanium dioxide after surface treatment is preferably 1 nm to 1 μm, and particularly preferably 10 to 100 nm.

As the resin component of the toner that can be used in the present invention, various known ones suitable for the toner for developing an electrostatic image can be used. For example, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer. Copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer and styrene-acrylic Acid phenyl copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer and styrene-phenyl methacrylate copolymer) Polymer, etc.), styrene-α-black Styrene resins such as methyl acrylate copolymer and styrene-acrylonitrile-acrylic acid ester copolymer (styrene or homopolymers containing styrene substitution), vinyl chloride resin, rosin-modified maleic acid resin, phenol Resin, epoxy resin, saturated or unsaturated polyester resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer and the like, but as a particularly preferable resin for use in the present invention, Examples thereof include styrene resins, saturated or unsaturated polyester resins and epoxy resins. Further, the resin is not limited to use alone,
Two or more can be used in combination.

Furthermore, the cross-linking binder resins described in JP-B-51-23354 and JP-B-50-44836, or JP-B-55-6895 and JP-B-63-32180 are described. The non-crosslinked binder resin described above can also be used.

The flow softening point of the toner particles is from 80 to
The temperature is preferably about 150 ° C, more preferably 90 to 140 ° C. If the temperature is lower than 80 ° C, the fixing temperature on the paper is low and good, but hot offset is likely to occur, and the toner is liable to be crushed inside the developing tank. However, there is a problem in that the charging characteristics are deteriorated, the charging characteristics are deteriorated, and the durability performance of the developer is deteriorated. On the other hand, if the temperature is higher than 150 ° C., the fixing temperature on the fixing paper is high, and the toner pulverizability is poor.

The glass transition temperature of the toner particles is 45 to 70.
C. is preferably lower than 45.degree. C., and if the toner is left at a high temperature of 40.degree. C. for a long period of time, it may cause hard aggregation or sticking of the toner, resulting in poor storage stability. Easy to generate. Furthermore, it easily adheres to the screen and side walls of the sieving device to form aggregates, and when the toner is used for a long time in the developing machine, it may stick to parts such as bearings in the developing machine and spike control plates. There is a problem in using. On the other hand, when the temperature is 70 ° C. or higher, there is a problem that the fixing temperature on paper is high and the pulverizability of the toner is poor. The flow softening point and the glass transition temperature described in the text are characteristic temperatures defined by the following measurements.

[Flow Softening Point (Tm)] In a flow tester (CFT-500 manufactured by Shimadzu Corporation), 1 g of a sample was put into a die of 1 mm × 10 mm nozzle, a load of 30 kg,
The preheating time is 50 ° C. for 5 minutes and the temperature rising rate is 3 ° C./min. The temperature at the midpoint of the distance from the start to the end of the flow is the flow softening point (Tm).

[Glass transition temperature (Tg)] In a differential thermal analysis (DTA-40 manufactured by Shimadzu Corporation), a tangent line to a transition (inflection) start portion of a curve measured at a temperature rising rate of 10 ° C./min. The glass transition temperature (T
g).

As the colorant of the toner used in the present invention,
There is no particular limitation, and any suitable pigment or dye can be used. For example, titanium dioxide, zinc white, alumina white, calcium carbonate, navy blue, carbon black, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine dyes and pigments, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallyl methane dyes. , Anthraquinone dyes, monoazo and disazo dyes and pigments can be used alone or in combination for the corresponding toner color.
The content of the colorant may be an amount sufficient to color the toner capable of forming a visible image by development, and is, for example, about 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin. It is particularly preferable that the amount is 1 to 10 parts by weight.

In addition, if necessary, a small amount of an auxiliary agent may be added for the purpose of improving the thermal properties and physical properties of the toner. For example, polyalkylene wax, paraffin wax,
Higher fatty acid, fatty acid amide, metal soap and the like can be used.
The addition amount is 0.0 with respect to 100 parts by weight of the toner particles.
1 to 10 parts by weight is desirable. In addition, in order to adjust the chargeability of the toner, in the case of positively chargeable toner, a known charge control agent such as a nigrosine dye, a quaternary ammonium salt, a triaminotriphenylmethane compound, an imidazole compound, a negative charge In the case of a chargeable toner, a known charge control agent such as a metal-containing azo dye, a salicylic acid metal complex and an alkylsalicylic acid metal complex may be added in an appropriate amount. The addition amount thereof is preferably about 0.01 to 20 parts by weight, and particularly preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the resin.

In the present invention, it is preferable to use the toner having a positive charging property. Further, the present invention works effectively when a positively chargeable charge control agent is used, and more effectively when a quaternary ammonium salt charge control agent is used. When the toner of the present invention is used as a two-component developer, the carrier is preferably magnetite.

The toner of the present invention can also be used as a one-component magnetic toner or non-magnetic toner that does not use a carrier. As a method for producing toner particles, various conventionally used toner production methods can be applied. For example, as a general example, first, a resin, a colorant, a wax, a charge control agent and the like are uniformly mixed with a known mixer. Disperse and mix,
Then, the mixture may be melt-kneaded by a closed kneader, a single-screw or twin-screw extruder, cooled, pulverized, and classified. The kneading machine is, for example, a KTK twin-screw extruder manufactured by Kobe Steel, a TEM extruder manufactured by Toshiba Machine Co., or a P manufactured by Ikegai.
A CM type twin-screw extruder, a Buss Co-kneader, etc. are preferable.

The average particle size of the toner is preferably 3 to 20 μm. The trimethylolethane surface-treated titanium dioxide may be added to the toner when kneading the toner or externally added to the classified toner. As a method of externally adding trimethylolethane surface-treated titanium dioxide to the classified toner, stirring and mixing may be performed with a high-speed stirrer such as a super mixer or a Henschel mixer. The amount of addition used may be different. The two-component starting developer can be prepared by mixing the toner obtained in the above step and the carrier with a ball mill, a V-type mixer or the like for a predetermined time and stirring.

[0025]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In addition, in the following examples, the term "parts" simply means "parts by weight" and "temperature 23 to 25 ° C., relative humidity 50 to 60".
% Environment "is called" normal environment "and" temperature 34-36 "
℃, relative humidity 85-95% "" high temperature and high humidity environment "
Called. The image density of the solid black portion was measured using a densitometer RD914 manufactured by Macbeth.

Example 1 A black product having the composition shown below was kneaded using a continuous twin-screw extruder, and then pulverized and classified to obtain an average particle size of 10 μm and Tm = 1.
A black toner of 30 ° C. and Tg = 60 ° C. was obtained.・ Styrene / n-butyl acrylate copolymer 100 parts ・ Colorant carbon black 6 parts (Mitsubishi Chemical MA100) ・ Polypropylene wax 2 parts (SANYO Kasei Co. TP32M) ・ Charge control agent Bontron P51 0.8 parts (Orient) Chemical company quaternary ammonium salt)

To 100 parts of this black toner, trimethylolethane-treated titanium dioxide fine powder having a primary particle diameter of 10 to 60 nm was mixed with a super mixer so as to be 1.75 parts, and Toner A was prepared. Obtained. When the surface of this toner A was observed with a scanning electron microscope, the dispersibility of titanium dioxide was very good, and it was found that primary particles were uniformly attached to the entire toner surface.

8 parts of toner A and magnetite powder carrier 9 having an average particle size of 65 μm and surface-coated with silicone resin 9
Two parts were mixed by stirring to prepare a developer A. Next, the developer A is used as the start developer, the toner A is used as the replenishment toner, the organic photo-semiconductor is used as the photoconductor, and the elastic rubber blade cleaning method is used to set the copy speed 1 of the two-component magnetic brush.
The following normal environment durability test, high temperature storage test, and high temperature and high humidity environment test were conducted using a copying machine of 5 sheets / minute.

Normal environment durability test A copy test of 40,000 sheets was carried out under a normal environment. As a result, during the copying from the initial stage up to 40,000, the fluidity of the toner was good, image defects did not occur, the image was clear, the image density was high and stable, and the stains on the white background of the copy were The toner and developer were excellent in image characteristics and durability, with no increase in fog, no defective cleaning, no occurrence of black spots, and almost no toner scattering in the machine. The transfer efficiency was as good as 85 to 90%. Further, the toner charge amount also showed a stable transition during aging.

High Temperature Storage Test Toner A is put in a cartridge and sealed, and the temperature is set to 5
After standing in a high temperature environment of 0 ° C and relative humidity of 50% for 48 hours,
The toner was left for 12 hours in a normal environment to obtain a high temperature storage toner.
This toner is used as a replenishing toner, and the developer A stored under the normal environment is used as the starting developer.
A 000-copy test was performed. As a result, the fluidity of the toner is very good, the toner is stably supplied without solidifying in the cartridge, the fog that is the stain on the white background of the copy does not increase even during the actual copying of 10,000 sheets, and the image density is stable. The developer was high, free from stains inside the machine due to toner scattering, and excellent in fluidity, durability, and copy image stability even when left at high temperature for a long time. Transfer efficiency is 85-9
It was as good as 0%. Further, the toner charge amount showed a stable transition.

High Temperature and High Humidity Environment Test Toner A and developer A were left in a high temperature and high humidity environment for 12 hours or more, and then 20,000 copies were evaluated in the same environment. As a result, during the initial copying up to 20,000, the fluidity of the toner was good, image defects did not occur, the image was clear, the image density was high and stable, and there was no stain on the white background of the copy. The toner and the developer were excellent in image characteristics and durability even in a high temperature and high humidity environment, with no increase in a certain fog, no defective cleaning, no occurrence of black spots, almost no toner scattering in the machine. The transfer efficiency was as good as 85 to 95%. Further, the toner charge amount showed a stable transition.

Comparative Example 1 Two-component development was carried out in the same manner as in Example 1 except that titanium dioxide fine powder having a primary particle size of 10 to 60 nm which was not surface-treated was used in place of trimethylolethane surface-treated titanium dioxide. The agent was created. When the surface of this toner was observed with a scanning electron microscope, the dispersibility of titanium dioxide was considerably poor, and it was observed that titanium dioxide particles were aggregated to a size of about 500 nm. When a normal environmental durability test was performed on this toner and developer, solidification occurred in the toner box, and stable toner supply was not possible,
I couldn't evaluate the live-action film.

[0033]

[Table 1]

[0034]

EFFECTS OF THE INVENTION According to the present invention, excellent fluidity, anti-caking property, good image density, good fog, good gradation, no image defects such as brush marks, chipping, filming and streak image defects, It is possible to obtain a toner capable of obtaining a high-quality image and a high-quality copy without cleaning defects. Also,
It is possible to obtain a toner excellent in durability and cost efficiency, such as stable image / image quality, little scattering in the machine, high transfer efficiency, and stable toner consumption even when repeatedly repeatedly copying and printing. Further, it is possible to obtain a toner having a wide range of usable environment, which is excellent in high-temperature storability and durability under high temperature and high humidity.

Claims (6)

[Claims] 1. An electrostatic charge image developing toner comprising at least a resin and a colorant, which contains titanium dioxide surface-treated with trimethylolethane. 2. The toner for developing an electrostatic charge image according to claim 1, which has a flow softening point of 80 to 150 ° C. and a glass transition temperature of 45 to 70 ° C. 3. The toner for developing an electrostatic charge image according to claim 1, which is used in a two-component developer in which the carrier is magnetite. 4. The toner for developing an electrostatic charge image according to claim 1, which is used as a positively chargeable toner. 5. An image forming method using blade cleaning as a cleaning method for an electrostatic image carrier, wherein the electrostatic image developing toner according to claim 1 is used. Forming method. 6. The image forming method according to claim 5, wherein the electrostatic image carrier is an organic photoconductor.