JP3347150B2 - Toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner. More specifically, it contains a styrene polymer having a specific molecular weight distribution and a linear polyester resin having a specific molecular weight distribution as a binder resin, and has excellent fixability (low-temperature fixability, fixing strength, and offset resistance) and is excellent in resistance. The present invention relates to an electrostatic image developing toner having excellent blocking properties.

[0002]

2. Description of the Related Art Conventionally, in a copying machine utilizing electrophotography, a binder resin is colored in order to visualize an electrostatic latent image formed on a photoreceptor having selenium and an organic photoconductor by a dry development method. A toner in which additives such as an agent are dispersed is used. In the developing method, an electrostatic latent image formed on the photoconductor by charging and exposure is developed with the toner, the developed toner image is transferred to a support such as transfer paper, and a heating roller and / or a heating roller are used. The toner image is fixed on a support by a pressure roller, and the electrostatic latent image is visualized. Then, after the toner image is transferred to the support, in order to clean the toner remaining on the photoconductor, the remaining toner on the photoconductor is scraped off by a cleaning member to prepare for the next image forming process. .

[0003] The above toner contains a colorant in a binder resin,
If necessary, the toner particles are resin particles having a particle size of 1 to 30 μm in which a toner control agent such as a charge controlling agent and magnetic particles are dispersed, and the toner is a two-component developer or a toner which is mixed with a carrier to form a developer. It is used as a one-component developer for developing electrostatic latent images.

Since these toners faithfully reproduce the original image in the developing process, the toner exhibits excellent fluidity in the developing device, makes the charge amount of each toner particle uniform, and is caused by uncharged and weakly charged particles. It is necessary to prevent the occurrence of fogging due to the adhesion of the toner to a portion other than the latent image, the accumulation of the toner in the developing device due to the excessively charged particles, and the decrease in the image density due to the decrease in the amount of the toner attached to the latent image. Further, in the fixing step to obtain a clear image, the toner is quickly fixed on the transfer material, and the toner is transferred to the surface of the fixing roller.
It is necessary not to cause so-called offset development.

Further, the toner must not be blocked during storage or transportation. Such toner has remarkably deteriorated fluidity, chargeability, and the like, and can no longer function as a developer. Therefore, the binder resin, which is a main component of the toner, is required to have delicate hardness and heat melting property, and the toner obtained by crushing and dispersing the binder resin in which the colorant and the like are dispersed is stirred in the developing device. It is necessary for the toner to exhibit good fluidity without generating fine powder due to mechanical shock caused by the toner and to prevent the toner itself from agglomerating. Needs to show cohesiveness.

It is extremely difficult to design a binder resin that satisfies all of these properties, and it is extremely difficult to achieve both of these properties because the fixability, the offset resistance, and the blocking resistance are contradictory. Technique.

[0007]

Accordingly, many proposals have been made on the molecular weight and molecular weight distribution of polymers used as binder resins. For example, in JP-A-56-16144, the molecular weight is 10 ³ to
It has been proposed to use a binder resin having at least one maximum in each region of 8 × 10 ⁴ and 10 ⁵ to 8 × 10 ⁶ .

However, although the toner disclosed in the above publication can certainly provide a certain effect with respect to impact resistance and fluidity in a developing device, it still has satisfactory fixability to a transfer material, particularly offset resistance. No results were obtained. Further, a toner containing 50 to 95% by weight of a low-temperature melting and high-fluidity resin having a number average molecular weight of 1,000 to 4000 has been proposed (Japanese Patent Publication No. 59-107360). The problem remains. Alternatively, the polyfunctional polycondensate is dissolved in a vinyl monomer and then dispersed and polymerized in water, or the above two types of resins, each of which has been polycondensed or polymerized alone, are dissolved in a common solvent, and the solution is mixed to form a solvent. The method of transpiration
There is a question about the solubility of the polyfunctional polycondensate, and even if partial dissolution is possible, it cannot be a completely homogeneous mixture. In addition, phase separation of the above two types of resins during the solvent evaporation process is inevitable. Therefore, it must be said that it is impossible in principle.

The present inventors have intensively studied to solve the above problems and provide a toner having excellent fixing properties (low-temperature fixing properties, fixing strength), offset resistance and blocking resistance, and as a result, satisfying the above performance. Has been completed. That is, in the present invention, in a toner for developing an electrostatic image containing a binder resin and a colorant, the chromatogram of the binder resin measured by gel permeation chromatography has a molecular weight of 1 × 10 ^{3 to} 5 × 10 ⁴ and A styrene resin having a peak in each region of 1 × 10 ⁵ to 1 × 10 ⁶ and a peak (molecular weight M) present on the lowest molecular weight side of the styrene resin, | M−N | ≦ 1 × 10
An electrostatic charge containing a linear polyester resin having a molecular weight N of ⁴ and a wax component dispersed or dissolved in the monomer during polymerization of the styrene resin and / or the linear polyester resin. Exists in toner for image development. In the present invention, a known ordinary method is used to measure the molecular weight at the peak position of the molecular weight distribution of the polymer. For example, an appropriate method in normal gel permeation chromatography may be used as follows.

[0010] 1. Measurement conditions Temperature: 40 ° C. Solvent: tetrahydrofuran Flow rate: 0.5 ml / min Sample concentration: 0.1
wt% sample injection volume: 100 μl

2. In order to properly measure the molecular weight region of the column 10 ^{3 to} 2 × 10 ^6, a combination of a plurality of commercially available polystyrene gel columns is used. In the measurement of the present invention, a GMH manufactured by Tosoh Corporation was used.
XL (30 cm × 2) was used.

3. Calibration curve The calibration curve is prepared using standard polystyrene. As standard polystyrene, for example, Pressure
chemical Co. Or Tosoh Corporation, for example, having a molecular weight of 6 × 10 ² , 2.8 × 10 ³ , 6.2 ×
10 ³ , 1.03 × 10 ⁴ , 1.67 × 10 ⁴ , 4.39
× 10 ⁴ , 1.02 × 10 ⁵ , 1.86 × 10 ⁵ , 4.2
It is suitable to use 2 × 10 ⁵ , 7.75 × 10 ⁵ , 1.26 × 10 ⁶ , and at least about 10 standard polystyrene.

4. Detector An RI (refractive index) detector is used as the detector.

The styrene resin used as the binder resin in the present invention is a homopolymer or a copolymer of any of the following styrene monomers and other unsaturated monomers, As styrene, α-
Methylstyrene, β-methylstyrene, o-methylstyrene, p-methylstyrene, p-ethylstyrene, p-
Methoxystyrene, o, m, p-chlorostyrene and the like can be mentioned, and as other unsaturated monomers, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate Phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate,
β-ethyl hydroxyacrylate, γ-propyl acrylate, σ-butyl butyl, β
-Acrylic monomers such as ethyl-hydroxymethacrylate, ethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate; vinyl esters such as vinyl formate, vinyl acetate and vinyl propionate; vinyl-n-butyl ether; vinyl Examples thereof include vinyl ethers such as phenyl ether and vinyl cyclohexyl ether; diolefins such as butadiene, isoprene and chloroprene; and monoolefins such as ethylene, propylene, isobutylene, butene-1, pentene-1, and 4-methylpentene-1. .

A particularly preferred combination is a multi-component copolymer of styrene and acrylic ester. The polymer used in the present invention is prepared by mixing the above-mentioned monomers by known polymerization means or blending in an amount of 1 × 10 ^{3 to} 5 × 10 ⁴ and 1 × 1.
It is adjusted so as to have a peak in each region of 0 ⁵ to 1 × 10 ⁶ .

The linear polyester used in the present invention is:
It is synthesized from diol and dicarboxylic acid,
Particularly, as the diol component, for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,4-bis (hydroxy Methyl) cyclohexane, bisphenol A, etherified bisphenol, hydrogenated bisphenol A, and modified products thereof are preferred. Examples of the dicarboxylic acid component include, for example, maleic acid, fumaric acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, oxalic acid or anhydrides or lower alcohols thereof. Esters are used.

Particularly preferred combinations include bisphenol A and etherified bisphenol as diol components, and fumaric acid, isophthalic acid and terephthalic acid as dicarboxylic acid components. The molecular weight N of the linear polyester is adjusted by a known polymerization means so that | M−N | ≦ 1 × 10 ⁴ with respect to the peak (molecular weight M) present on the lowest molecular weight side of the styrene resin. .
Outside of this range, low-temperature fixability and fixing strength are impaired when M <N, and offset resistance and blocking resistance are impaired when M> N.

Furthermore, by dispersing or dissolving the wax component in the monomer during the polymerization of the styrene resin and / or the linear polyester resin, the charge amount is stabilized when the toner is formed, and the image density during aging is kept constant. Will be kept. In the toner composition, the mixing amount of the polyester resin to 100 parts by weight of the styrene resin is preferably 10 to 60 parts by weight. If the mixing amount is less than 10 parts by weight, no improvement in fixability can be expected. On the other hand, if the mixing amount of the polyester resin with respect to 100 parts by weight of the styrene resin exceeds 60 parts by weight, the resistance to offset and blocking is impaired.
In particular, the offset resistance is significantly reduced.

As the colorant used in the toner of the present invention,
All known materials can be used, for example, carbon black, nigrosine, benzidine yellow, quinacridone,
Rhodamine B, phthalocyanine blue and the like. The amount of the colorant to be added to the toner is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the binder resin.
Parts by weight are desirable. Further, the toner of the present invention can be used for both dry one-component developer and two-component developer, and as a one-component magnetic material, ferromagnetic materials such as ferrite, magnetite, and other iron, cobalt, and nickel are used. Alloys or alloys that do not contain compounds or ferromagnetic elements, but which become ferromagnetic by appropriate heat treatment, such as manganese-copper-aluminum or manganese-
An alloy of a type called a Heusler alloy containing manganese and copper, such as copper-tin, or chromium dioxide can be given. The magnetic material is uniformly dispersed in the binder resin in the form of fine powder having an average particle size of 0.3 to 30 μm. The content of the magnetic particles is 20 to 7 per 100 parts by weight of the binder.
0 parts by weight, preferably 40 to 70 parts by weight.

The charge control of the toner may be performed by the binder resin and the colorant itself, but may be performed by using a charge control agent as needed. Use of a quaternary ammonium salt, a basic / electron-donating organic substance as a positive charge control agent, and use of a metal chelate, a metal-containing dye, an acidic or electron-withdrawing organic substance, etc. as a negative charge control agent. Can be. The amount of the charge control agent to be added can be determined in consideration of the conditions such as the chargeability of the binder resin, the production method including the amount and dispersion method of the colorant, and the chargeability of other additives. 0.1 to 10 parts by weight is appropriate for 100 parts by weight. In addition, inorganic particles such as a metal oxide or an inorganic substance surface-treated with the organic substance may be used. These charge control agents may be used by mixing and adding to the binder resin, or may be used in the form of being attached to the surface of toner particles.

Further, a solid electrolyte, a polymer electrolyte,
Electrical properties of the toner can be controlled by adding a charge transfer complex, a conductor such as a metal oxide such as tin oxide, a semiconductor, or a ferroelectric substance or a magnetic substance. In addition, auxiliary agents such as various plasticizers and release agents can be added to the toner for the purpose of adjusting thermal characteristics, physical characteristics, and the like. The addition amount is suitably from 0.1 to 10 parts by weight. Further, fine powders such as TiO ₂ , Al ₂ O ₃ , SiO _{2 and the} like are added to the toner particles, and the surface of the toner particles is coated with the fine particles to improve the fluidity and the aggregation resistance of the toner. The addition amount is preferably 0.1 to 10 parts by weight. Various conventional methods for producing a toner can be applied to the method for producing the toner of the present invention. For example, the following examples are given as typical production methods. First, a resin and a colorant (such as a charge control agent) are uniformly dispersed by a ball mill, a V-type mixer, an S-type mixer, a Henschel mixer, or the like. Next, the dispersion is melt-kneaded with a double-arm kneader, a pressure kneader, or the like. The mixture is pulverized by a pulverizer such as a hammer mill, a jet mill, and a ball mill, and the obtained powder is classified by an air classifier or the like.

The obtained toner is mixed with a carrier to form an electrophotographic developer, and can be used for electrophotographic copying which has been conventionally performed. The carrier is preferably a known magnetic substance such as an iron powder-based carrier or a ferrite-based carrier, or a carrier coated on the surface thereof, preferably in an amount of 10 to 100 parts per 1 part of the toner. Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples. In the examples, "parts" represents "parts by weight".

Reference Example 1 GPC chromatogram has a molecular weight of 4.7 × 10 ³ and a peak of 5.7 × 10 ⁵ styrene-n-butyl acrylate (monomer weight ratio 80:20), 100 parts by weight 40 parts of a linear polyester comprising a bisphenol A ethylene oxide adduct having a peak at 6.5 × 10 ³ and phthalic acid, 3 parts of Viscol 550P (polypropylene wax manufactured by Sanyo Chemical Co., Ltd.), carbon black # 30 (Mitsubishi Chemical) 6.0 parts) and 2.0 parts by weight of Bontron No. 4 (Nigrosine dye manufactured by Orient Chemical Co.) were mixed and then melt-kneaded using a twin-screw extruder.
After cooling, the mixture was roughly pulverized using a hammer mill, and then finely pulverized using a supersonic jet mill pulverizer. The obtained powder was classified by an air classifier to obtain a toner having an average particle size of 10.5 μm.

Example 1 Reference Example 1 was repeated except that 3 parts of Viscol 550P (a polypropylene wax manufactured by Sanyo Chemical Co., Ltd.) was dispersed in 100 parts of styrene-n-butyl acrylate (monomer weight ratio 80:20) during polymerization. The flat particle size is exactly 10.
5 μm of toner A was obtained.

The above toner and an average particle diameter of 50 to 80 μm
The ferrite carrier was mixed to obtain a developer having a toner concentration of 4.0%, and a fixing property test (lower fixing temperature, high-temperature offset occurrence temperature, fixing strength) and a blocking resistance test were performed. As shown in Table 1, The fixing property and the blocking resistance were good.

A commercially available copying machine (Sharp SF-88)
When the aging test was performed at 00), as shown in Table 2, even after 20,000 copies were made, no significant change was observed in both the image density and the charge amount, and the image was stable.

COMPARATIVE EXAMPLE 1 A styrene-n-butyl acrylate having a peak at a molecular weight of 4.7 × 10 ³ and 5.7 × 10 ⁵ in a GPC chromatogram (100 parts by weight of monomer: 80:20) has a molecular weight of 2. Toner B having an average particle size of 10.5 μm was obtained in the same manner as in Reference Example 1 except that 40 parts of a linear polyester comprising a bisphenol A ethylene oxide adduct having a peak at 0 × 10 ⁴ and phthalic acid was used.

The above toner and an average particle diameter of 50 to 80 μm
The ferrite carrier was mixed to obtain a developer having a toner concentration of 4.0%, and a fixing property test (lower fixing temperature, high-temperature offset occurrence temperature, fixing strength) and a blocking resistance test were performed. As shown in Table 1, Compared to Example 1,
The fixing lower limit temperature and the fixing strength were inferior.

Comparative Example 2 Styrene-methyl methacrylate-n-butyl acrylate having a peak at a molecular weight of 2.0 × 10 ⁴ and 8.2 × 10 ⁵ in a GPC chromatogram (monomer weight ratio: 8
0: 5: 15) In the same manner as in Reference Example 1, except that 20 parts of a linear polyester having a peak at a molecular weight of 5.5 × 10 ³ consisting of hydrogenated bisphenol A, ethylene glycol and terephthalic acid was used for 100 parts. A toner C having an average particle size of 9.5 μm was obtained.

The above toner and an average particle diameter of 50 to 80 μm
The ferrite carrier was mixed to obtain a developer having a toner concentration of 4.0%, and a fixing property test (lower fixing temperature, high-temperature offset occurrence temperature, fixing strength) and a blocking resistance test were performed. As shown in Table 1, As compared with Example 1, the hot offset occurrence temperature and the blocking resistance were inferior.

COMPARATIVE EXAMPLE 3 Styrene-n-butyl acrylate-n-butyl methacrylate having a peak at a molecular weight of 7.3 × 10 ³ and 5.3 × 10 ⁵ in a GPC chromatogram (monomer weight ratio 75: 5: 20) Toner D having an average particle size of 10.0 μm was prepared in the same manner as in Reference Example 1 except that 20 parts of a linear polyester having a peak at a molecular weight of 2.0 × 10 ⁴ composed of bisphenol A and terephthalic acid was used per 100 parts. Obtained.

The above toner and an average particle diameter of 50 to 80 μm
The ferrite carrier was mixed to obtain a developer having a toner concentration of 4.0%, and a fixing property test (lower fixing temperature, high-temperature offset occurrence temperature, fixing strength) and a blocking resistance test were performed. As shown in Table 1, The fixing lower limit temperature and the fixing strength were inferior to those of Example 1.

Comparative Example 4 N-butyl styrene-methacrylate-2-ethylhexyl-methacrylate having peaks at a molecular weight of 2.0 × 10 ⁴ and 3.0 × 10 ⁵ in a GPC chromatogram (monomer weight ratio: 80:15: 5) An average particle size of 10.1 was obtained in the same manner as in Reference Example 1 except that 10 parts of a linear polyester having a molecular weight of 4.5 × 10 ³ and composed of bisphenol A, ethylene glycol and terephthalic acid was used for 100 parts. 0 μm of toner E was obtained.

The above toner and an average particle diameter of 50 to 80 μm
The ferrite carrier was mixed to obtain a developer having a toner concentration of 4.0%, and a fixing property test (lower fixing temperature, high-temperature offset occurrence temperature, fixing strength) and a blocking resistance test were performed. As shown in Table 1, As compared with Example 1, the hot offset occurrence temperature and the blocking resistance were inferior.

Evaluation Method In the present invention, a fixing property (lower fixing temperature, high temperature offset occurrence temperature, fixing strength) test and a blocking resistance test were carried out by the following methods. Fixing lower limit temperature, high-temperature offset occurrence temperature: An undeveloped sample was passed through the paper while changing the roll temperature of a fixing device having a roll rotation speed of 400 mm / s. The minimum fixing temperature was set to the lowest temperature at which the fixing toner did not peel off, and the high-temperature offset occurrence temperature was set to a temperature at which the toner adhered to the roller by offset occurred.

Fixing strength: Roll rotation speed is 400 mm /
s, the unfixed sample is passed through a fixing device using a fixing device with a roll temperature of 190 ° C., and the image is fixed. The image density of the fixed image before and after peeling of the formed fixed image is measured with a reflection densitometer. I

[0036]

(Equation 1)

Anti-blocking test The toner was left under a constant pressure at 50 ° C for 2 days to evaluate the degree of aggregation.

[0038]

[Table 1]

[0039]

[Table 2]

(The image density was measured by a reflection densitometer, and the charge amount was measured by a blow-off method.)

[0041]

According to the present invention, it is possible to obtain a toner having excellent balance in fixing property (low-temperature fixing property, fixing strength), offset resistance and blocking resistance.

Continuation of the front page (72) Inventor Shuichi Maeda 1000 Kamoshita-cho, Midori-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Chemical Research Laboratory (56) References JP-A-4-178658 (JP, A) JP-A-59-107359 (JP, A) JP-A-63-27856 (JP, A) JP-A-63-127254 (JP, A) JP-A-2-167563 (JP, A) JP-A-60-244956 (JP, A) Kaisho 56-16144 (JP, A)

Claims (1)

(57) [Claims] 1. A toner for developing an electrostatic charge image containing a binder resin and a colorant, wherein the chromatogram of the binder resin measured by gel permeation chromatography has a molecular weight of 1 × 10 ^{3 to} 5 × 10 ^4. And a styrene resin having a peak in each region of 1 × 10 ⁵ to 1 × 10 ⁶ , and | M−N | ≦ 1 × with respect to a peak (molecular weight M) present on the lowest molecular weight side of the styrene resin.
A linear polyester resin having a molecular weight N of 10 ⁴ , wherein the wax component is the styrene-based resin and
And / or during polymerization of the linear polyester resin
A toner for developing electrostatic images, wherein the toner is dispersed or dissolved .