JP3129074B2 - Electrophotographic toner composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner composition used for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like.

[0002]

2. Description of the Related Art Conventionally, dry developers used in electrophotography include a one-component developer using a toner itself in which a colorant is dispersed in a binder resin, and a two-component developer in which a carrier is mixed with the toner. And can be broadly divided into However, with these developers alone, storage stability, transportability,
Insufficient properties such as developability, transferability, and chargeability. In order to improve these properties, additives are often externally added to the toner. Examples of the additive include hydrophobic silica fine powder (Japanese Patent Application Laid-Open No. 56-128957), silica fine particles to which aluminum oxide or titanium oxide fine particles are added (Japanese Patent Application Laid-Open No. 60-238847), and vapor-phase titanium oxide. (Japanese Patent Application Laid-Open No. 59-5)
No. 2255), anatase-type titanium oxide (Japanese Unexamined Patent Publication No.
No. 0-112052) and aluminum oxide-coated titanium oxide (Japanese Patent Application Laid-Open No. 57-79961). Further, an external additive whose surface has been treated with an inorganic compound, for example, a titanium oxide fine particle whose surface has been treated with a coupling agent (JP-A-4-40467, JP-A-4-34)
No. 8354) has also been proposed.

[0003]

Heretofore, hydrophobic fine powders such as silica have often been used as additives, and the preservability, transportability, developability, transferability, etc. are considerably improved by this. However, the use of a sufficient amount for these improvements has the problem of adversely affecting the chargeability. That is, regarding the chargeability, the charge amount, the charge speed, the charge amount distribution, the admixability of the toner, it is required to satisfy requirements such as environmental stability of the charge, but when using silica or the like, This adversely affects the charging speed, the distribution of the charging amount, the admixing property of the toner and the environmental stability. Also,
When a polyester resin is used as a binder resin for a toner, the polyester resin itself has a negative charge property, and thus it is said that a negative charge property can be obtained by not using a charge control agent or using a small amount. . However,
The polyester resin has the drawback that the charge dependence on the environment, that is, the difference in charge amount between high temperature and high humidity and low temperature and low humidity is large, and that the charge amount distribution is wide. In particular, when a pigment other than carbon black is used as a colorant for a toner, these disadvantages appear remarkably. These problems are alleviated by using, as an additive, titanium oxide surface-treated with a specific treating agent. When an additive is used, the state of attachment of the additive fine particles when attached to the surface of the toner particles is also an important factor. For example, additive fine particles having weak or non-adhesive force with toner particles are likely to migrate to and adhere to the photoreceptor, causing image defects. However, if the adhesive force with the toner particles is increased, when the developer (toner and carrier) is stirred for a long time in the developing device, the toner receives a large stress and the additive fine particles are easily embedded in the toner. The phenomenon occurs. When new toner is added to the toner in which the additive fine particles are embedded, charge exchange failure between the toner particles is caused, and there is a toner having a different charge amount distribution. As a result, fogging occurs in a copy image. Become. The present invention has been made in view of the above-described circumstances in the related art. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic toner having excellent charge amount, environmental stability of charge, toner admix property, durability and the like. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic toner capable of obtaining a high-quality image free from image quality defects due to contamination of a photoreceptor with additive fine particles and fog due to embedding of additive fine particles.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks in the prior art, the present inventors have earnestly studied the relationship between the adhesion of additive fine particles to toner particles and toner characteristics such as image quality improvement. As a result of the study, it has been found that when the specific additive and its adhesive force have a predetermined relationship, the above object is achieved, and the present invention has been completed. That is, the electrophotographic toner composition of the present invention comprises toner particles containing at least a colorant and a binder resin and additive fine particles, wherein the binder resin is a polyester resin, and the additive fine particles Is a titanium oxide fine particle having a water-soluble component content of less than 0.2% by weight produced by a wet method, which is surface-treated with a coupling agent or silicone oil, and satisfies the following expression. A: 0 to 10 B: 30 to 50 C: 45 to 70 B ≦ C [where A represents ultrasonic vibration (output 60
W, a frequency of 20 kHz) for 30 minutes represents a weight ratio (%) to the total amount of additive fine particles adhering without detaching from the toner particles, and B represents ultrasonic vibration (output) in the toner dispersion. 20 W, frequency 20 kHz) for 1 minute, represents a value (%) obtained by subtracting A from the weight ratio to the total amount of the additive fine particles adhering without detaching from the toner particles, and C represents the total amount ( 100) is the value obtained by subtracting A and B from the value. ]

Hereinafter, the present invention will be described in detail. As the colorant constituting the toner particles of the present invention, known ones can be used. For example, carbon black is used as the black toner, and C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 57: 1, C.I.
I. Pigment Yellow 97, C.I. I. Pigment
Yellow 12, C.I. I. Pigment Yellow 17,
C. I. Pigment Blue 15: 3 and the like can be exemplified as typical ones.

As the binder resin constituting the toner particles, a known polyester resin can be used. The polyester resin can be produced by reacting a polyhydroxy compound with a polybasic carboxylic acid or a reactive derivative thereof. Examples of the polyhydric hydroxy compound constituting the polyester include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,
Diols such as 1,4-butanediol, bisphenol A alkylene oxide adducts such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A and polyoxypropylene bisphenol A, and other dihydric alcohols and divalent such as bisphenol A Phenol and the like.

The polybasic carboxylic acids include, for example, malonic acid, succinic acid, adipic acid, sebacic acid, alkyl succinic acid, maleic acid, fumaric acid, mesaconic acid,
Examples thereof include citraconic acid, itaconic acid, glutaconic acid, cyclohexanedicarboxylic acid, fumaric acid, isophthalic acid, terephthalic acid, other divalent carboxylic acids, and reactive derivatives thereof such as acid anhydrides, alkyl esters, and acid halides. . In addition to these carboxylic acids, a trivalent or higher polyhydric hydroxy compound and / or a trivalent or higher polycarboxylic acid can be added to make the polymer non-linear to the extent that tetrahydrofuran insolubles do not occur.

[0008] Among these polyester resins, a polyester resin comprising a polycondensate containing a bisphenol-based diol component and an aromatic polycarboxylic acid as a main monomer component, particularly a linear polyester resin, can be preferably used.
The physical properties of the polyester resin are as follows:
Those having a temperature of 50 ° C and a glass transition point of 50 to 70 ° C are preferred. In particular, a resin having a number average molecular weight of 2,000 to 6,000, a weight average molecular weight of 8,000 to 15,000, an acid value of 5 to 30, and a hydroxyl value of 5 to 40 can be particularly preferably used.

In the present invention, the content of the colorant in the toner particles is preferably in the range of 1 to 8 parts by weight based on 100 parts by weight of the binder resin. When the content of the colorant is less than 1 part by weight, the coloring power is weakened, and when the content is more than 8 parts by weight, the transparency of the toner is deteriorated. The toner particles have an average particle size of about 30 μm or less, preferably 5 to 2 μm.
Those having a range of 0 μm can be used. If necessary, known additives such as a charge control agent and a fixing aid may be contained in the toner particles.

In the present invention, the additive fine particles to be added to the toner particles include water-soluble components produced by a wet method and having a water-soluble component content of 0.2% by weight obtained by washing with water.
Less than titanium oxide whose surface is surface-treated with a coupling agent or silicone oil is used. Here, the wet method is a method of producing a compound through a chemical reaction in a solvent, and a main production method includes a sulfuric acid method and a hydrochloric acid method. In the sulfuric acid method, a reaction represented by the following reaction formula proceeds in a liquid phase, and insoluble titanium oxide hydroxide is formed. FeTiO ₃ + 2H ₂ SO ₄ → FeSO ₄ + TiOSO ₄ + 2H ₂ O TiOSO ₄ + 2H ₂ O → TiO (OH) ₂ + H ₂ SO _{4 In} the hydrochloric acid method, titanium tetrachloride is first dissolved in water. At this time, the aqueous solution becomes an aqueous hydrochloric acid solution. Next, a strong base such as caustic soda is added, and titanium hydroxide Ti (OH) ₄
And titanium hydroxide is precipitated. Both of the above-mentioned hydrous titanium oxide and titanium hydroxide are converted into titanium oxide fine particles through a firing step.

In the present invention, the titanium oxide fine powder must have a water-soluble component content of less than 0.2% by weight. When the amount of the water-soluble component is 0.2% by weight or more, the charge amount is low as in the case of conventional titanium oxide, and the charge amount does not become sufficiently high even after the surface treatment. When the amount of the water-soluble component is less than 0.2% by weight of titanium oxide,
The charge amount increases, and when the surface treatment is performed, a higher charge amount is maintained. Titanium oxide itself is insoluble in water and has no water-soluble components, but in the case of titanium oxide produced by a wet method, trace amounts of water-soluble components remain inevitable from the production process. When the water-soluble component remains, the water-absorbing component becomes water-absorbing and easily attracts water, thereby lowering its own resistance and lowering the charge amount. Therefore, it is presumed that by removing or reducing the water-soluble component, the resistance increases and a high charge amount is maintained. As water-soluble components, K ⁺ , Na ⁺ , L contained in a treating agent and a flocculant used in the production process are used.
i ⁺ , Mg ²⁺ , PO ₄ ²⁻ , SO ₄ ²⁻ , Cl ⁻ , and the like. The water-soluble component was measured by boiling 5 g of titanium dioxide in 250 ml of water, cooling, and filtering the filtrate.
It is carried out by evaporating 0 ml and drying the remaining amount. The details are described in JIS K5116-1973 titanium dioxide (pigment), and the water-soluble component of the present invention is measured according to JIS. It was done.

As the treating agent used for the surface treatment of the titanium oxide fine particles, those which react with hydroxyl groups are used.
For example, a coupling agent such as a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zirconium coupling agent, and a silicone oil can be used. Among them, silane coupling agents and silicone oils represented by the following chemical formulas are preferred. _{R 4-x Si (NCO)} x R 4-x Si (OR 1) x R 4-x SiCl x (x is an integer from 1 to 3, R represents an alkyl group or a perfluoroalkyl of 1 to 16 carbon atoms And OR ₁ represents a lower alkoxy group such as a methoxy group or an ethoxy group.)

Specifically, (CH ₃ ) ₂ Si (NCO)
₂ , CH ₃ Si (NCO) ₃ , C ₁₀ H ₂₁ Si (OC
H ₃ ) ₃ , CF ₃ Si (OCH ₃ ) _{3 and the} like can be mentioned, but those having x of 3 are preferable in terms of increasing the charge amount.
For the same reason, R is preferably an alkyl group having 7 to 16 carbon atoms or a perfluoroalkyl group. As the silicone oil, dimethyl silicone, methylphenyl silicone, monomethyl silicone, etc., as well as modified silicone oil can be used.

In the toner composition of the present invention, the titanium oxide fine particles are added in an amount of 0.5 to 3% by weight based on the toner particles. Further, titanium oxide fine particles having an average particle diameter in the range of 5 to 30 nm are used, and may be used in combination with other additives such as silica and alumina.

The additive can be held on the surface of the toner particles by, for example, a high-speed mixer. Specifically, a Henschel mixer (manufactured by Mitsui Miike), a mechanofusion system (manufactured by Hosokawa Micron), a mechanomill (manufactured by Okada Seiko Co., Ltd.) and the like can be mentioned. However, the device for holding the additive particles on the surface of the toner particles is not limited to these. When a Henschel mixer is used as an example, the additive fine particles can be satisfactorily adhered by appropriately adjusting the shape, peripheral speed, mixing time and the like of the stirring blade.

In this case, it is necessary to mix the toner particles and the additive particles so as to satisfy the following relationship. A: 0 to 10%, B: 30 to 50 %, C: 45 to 70
%, B ≦ C, where A + B + C = 100% A, that is, ultrasonic vibration (output 60
W, a frequency of 20 kHz) for 30 minutes, when the weight ratio of the additive fine particles adhering without detaching from the toner particles to the total added amount is more than 10%, the toner is embedded in the toner before receiving stress. It shows that there are many additives, and the stress in the developing unit
An image with much fog is likely to occur. B, that is, when ultrasonic vibration (output: 20 W, frequency: 20 kHz) is applied for 1 minute in the toner dispersion, the weight ratio based on the total amount of additive fine particles adhering without detaching from the toner particles is calculated. When the value obtained by subtracting A is less than 30%, the amount of free external additives or external additives that are easily released increases.
Adhesion to photosensitive member arising. In the case of B> C, the specific gravity of the external additive that is easily embedded in the toner due to the stress is high, so that fog is likely to occur.

In the case where aggregates are generated at the time of the above mixing, when coarse particles are contained in the additive, or when coarse powder toner is not removed in the classification, means for removing these coarse particles is as follows. Usually, a method of sieving using an eye net of several tens μm to several hundred μm is used. In this sieving, the weakly adhering additives are detached or strongly adhered, so that the adhesive force at the time of mixing and the adhesive force at the time of sieving may be different. It is necessary to obtain the adhesive force considered.

The electrophotographic toner composition of the present invention is used as a two-component developer using a carrier. The carrier is not particularly limited as long as it is a known carrier, and iron powder-based carriers, ferrite-based carriers, surface-coated carriers, magnetic powder-dispersed carriers, and the like can be used.

[0019]

The present invention will be described below with reference to examples. 1) Production of Toner Particles 100 parts by weight of polyester resin (condensation product of bisphenol A-ethylene oxide adduct and terephthalic acid, Mn = 3000, Mw = 9000) Magenta coloring material (CI pigment red 57: 1) 4 parts by weight The above components are melted, kneaded, pulverized and classified to obtain an average particle size of 9 μm.
m was obtained.

2) Production of Additives In the production of the following additives, rutile-type titanium oxide (MT-150A; manufactured by Teica Co., Ltd.) having an average particle size of 15 nm produced by a sulfuric acid method was used as wet titanium oxide. used. The titanium oxide contained 0.30% by weight of a water-soluble component. Additive a 10 g of titanium oxide fine powder which was washed with water in a mixed solvent of methanol-water (95: 5) in which 1.0 g of methyltrimethoxysilane was dissolved to reduce the water-soluble component to 0.09% by weight.
Was added and ultrasonically dispersed. Next, after evaporating methanol and the like in the dispersion with an evaporator and drying,
Heat-treated in a dryer set at 0 ° C, crushed in a mortar,
Titanium oxide surface-treated with methyltrimethoxysilane was obtained. Additive b To a toluene solvent in which 2.0 g of decyltrimethoxysilane was dissolved, 10 g of titanium oxide fine powder which had been washed with water and had a water-soluble component of 0.10% by weight was added and ultrasonically dispersed. Thereafter, the same treatment as in the production of the additive a was performed to obtain titanium oxide surface-treated with decyltrimethoxysilane. Additive c Silicone oil (KF99; Shin-Etsu Chemical Co., Ltd.) 2.0 g
Was washed with water in toluene in which
10 g of titanium oxide fine powder of 8% by weight was added and ultrasonically dispersed. Then, the toluene in the dispersion was evaporated with an evaporator, dried, and then heat-treated with a drier set at 140 ° C., pulverized with a mortar, and titanium oxide surface-treated with silicone oil was obtained. Additive d Titanium oxide in which the water-soluble component was reduced to 0.11% by weight without surface treatment was obtained by merely washing the titanium oxide with water.

Example 1 To 100 parts by weight of the above toner particles, 1.0 part by weight of an additive a was added and mixed with a high-speed mixer (5 liter Henschel mixer, manufactured by Mitsui Miike Co., Ltd.). , B = 43,
A toner composition having C = 52 was obtained. Example 2 1.0 part by weight of the additive a was added to 100 parts by weight of the toner particles, and mixed with a 5 liter Henschel mixer under conditions different from those in Example 1, so that A = 10 and B = 4.
5, a toner composition having C = 45 was obtained. Example 3 To 100 parts by weight of the toner particles, 1.0 part by weight of the additive b was added and mixed with a 5-liter Henschel mixer to obtain a toner composition having A = 3, B = 29, and C = 67. Obtained. Example 4 To 100 parts by weight of the toner particles, 1.0 part by weight of the additive c was added and mixed with a 5-liter Henschel mixer to obtain a toner composition having A = 6, B = 46, and C = 48. Obtained.

COMPARATIVE EXAMPLE 1 1.0 part by weight of an additive a was added to 100 parts by weight of the above toner particles, and the conditions were different from those in Examples 1 and 2.
Mix with a 5 liter Henschel mixer, A = 2
3, a toner composition having B = 50 and C = 27 was obtained. Comparative Example 2 1.0 part by weight of an additive d was added to 100 parts by weight of the toner particles, and mixed with a 5-liter Henschel mixer to obtain a toner composition having A = 4, B = 42, and C = 54. Obtained. Comparative Example 3 To 100 parts by weight of the toner particles, 1.0 part by weight of the additive b was added and mixed with a 5-liter Henschel mixer to obtain a toner composition having A = 1, B = 19, and C = 80. Obtained.

The adhesion strengths A, B and C of the obtained additive fine particles of Examples 1 to 4 and Comparative Examples 1 to 3 were measured by the following methods. An ultrasonic vibrator (ultrasonic homogenizer US300) in which 2 g of toner particles are immersed in 40 ml of a 0.2% concentration triton solution (polyoxyethylene octylphenyl ether having a degree of polymerization of 10; manufactured by Wako Pure Chemical Industries)
T, manufactured by Nippon Seiki Seisakusho) was operated at an output of 20 W for 1 minute and similarly at an output of 60 W for 30 minutes to desorb the titanium oxide fine particles. Thereafter, a 50 cc centrifuge with a sedimentation tube (a small-sized cooled high-speed centrifuge Model M160)
-IV, manufactured by Sakuma Seisakusho) to separate the toner particles under the conditions of 1000 rpm × 2 minutes and remove the supernatant liquid.
It was washed twice with pure water and dried. The dried toner particles were molded, and the amount of titanium oxide fine particles remaining in the toner particles was quantified using a fluorescent X-ray analyzer (System 3370, manufactured by Rigaku Corporation).

Preparation of Developer Iron powder having an average particle size of 50 μm coated with a fluorine-containing acrylic resin was used as a carrier, and the toner composition was mixed to a toner concentration of 8% by weight to prepare a developer.

Using the obtained developer, a copier (A-Co
lor 635, manufactured by Fuji Xerox Co., Ltd.). In the evaluation, continuous 25,000 copies were made in a low-temperature and low-humidity environment, the state of deposits on the surface of the photoreceptor was examined, and image quality defects and fogging of the obtained image were examined. Table 1 shows the results.

[0026]

[Table 1] As shown in Table 1, when the toner composition of each example was used, both fog and image quality defects were superior to the toner composition of the comparative example despite continuous copying of many sheets. You can see that.

[0027]

The toner composition for electrophotography of the present invention uses a polyester resin as a binder resin and the above-mentioned specific titanium oxide fine particles as additive fine particles. It is excellent in toner admixability, durability, etc., and can suppress image quality defects due to contamination of the photoconductor with additive fine particles and fog due to embedding of additive fine particles for a long time. It has the effect of being able to.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Emi Takahashi 1600 Takematsu, Minamiashigara, Kanagawa Prefecture Inside Fuji Xerox Corporation (72) Inventor Susumu Saito 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Corporation (56) References JP-A-4-30961 (JP, A) JP-A-7-175258 (JP, A) JP-A-7-43931 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name ) G03G 9/08

Claims (3)

(57) [Claims] 1. An electrophotographic toner composition comprising toner particles containing at least a colorant and a binder resin and additive fine particles, wherein the binder resin is a polyester resin,
Additive particles obtained by subjecting titanium oxide particles having a water-soluble component content of less than 0.2% by weight produced by a wet method to a surface treatment with a coupling agent or silicone oil,
A toner composition for electrophotography, wherein the toner particles and the additive particles satisfy the following relationship. A: 0 to 10 B: 30 to 50 C: 45 to 70, B ≦ C [where A is an ultrasonic vibration (output 60
W, a frequency of 20 kHz) for 30 minutes, represents a weight ratio (%) to the total amount of the additive fine particles adhering without detaching from the toner particles, and B represents ultrasonic vibration (toner vibration) in the toner dispersion. When output (20 W, frequency 20 kHz) is applied for 1 minute, A represents a value (%) obtained by subtracting A from the weight ratio to the total amount of additive fine particles adhering without detaching from toner particles, and C represents total addition. The value (%) obtained by subtracting A and B from the amount is shown. ] 2. The electrophotographic toner composition according to claim 1, wherein the polyester resin is a polycondensate containing a bisphenol-based diol component and an aromatic polycarboxylic acid component as main monomer components. 3. The polyester resin has a softening point of 90 to 150.
The toner composition for electrophotography according to claim 1, wherein the toner composition has a glass transition point of 50 to 70C.