JP3971374B2 - toner - Google Patents

Description

  The present invention relates to a toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

As a kind of colorant, aniline black is known (see Patent Documents 1 to 3).
JP-A-4-145449 (page 3, upper left column, lines 9 to 17) JP-A-4-306666 ([0008]) JP-A-3-109573 (Claim 1)

  However, in Patent Documents 1 and 2, aniline black is only exemplified as one of the colorants, and the invention described in Patent Document 3 is characterized by the combined use of carbon black and aniline black. Yes. However, none of Patent Documents 1 to 3 discusses the physical properties of aniline black itself.

  An object of the present invention is to provide a toner excellent in print quality charge stability.

The present invention is a toner containing a binder resin and aniline black, wherein the chromium content in the aniline black is 0.1 g or less per kg of aniline black, and the copper contained in the aniline black. Relates to a toner whose content is 0.09 g or less per kg of aniline black.

  The toner of the present invention has an excellent effect of having charging stability with good print quality.

  The toner of the present invention has a great feature in that it contains aniline black whose chromium or copper content is controlled. Aniline black is a black dye obtained by oxidative polymerization of aniline. In the production process, usually, a copper salt is used as a catalyst and a chromium salt is used as an oxidizing agent. The toner of the present invention has extremely excellent charging stability because the chromium and copper contents in aniline black are controlled. If there is a large amount of chromium and copper, there will not be much effect under normal temperature and humidity, but under high temperature and high humidity, the charge level will decrease, print quality such as image density and background fog, and transfer efficiency. In addition, toner consumption is significantly deteriorated. This is presumably because, under high temperature and high humidity, the electrical conductivity is increased by chromium and copper, and the charging property of the toner is inhibited.

  The content of chromium contained in aniline black is 0.1 g or less, preferably 0.09 g or less, more preferably 0.05 g or less, per 1 kg of aniline black from the viewpoint of charging stability.

  In addition, the content of copper contained in aniline black is 0.09 g or less, preferably 0.08 g or less, more preferably 0.05 g or less, per 1 kg of aniline black from the viewpoint of charging stability.

  In the present invention, it is sufficient that either one of the chromium and copper contents is adjusted within the above range, but it is more preferable that both are adjusted within the above range.

  The chromium and copper contents are controlled by the amount of chromium salt and copper salt used in the production of aniline black, etc., and examples of aniline black in the present invention include those described in JP-A-10-245497. By the method described, aniline black produced without using a chromium salt or a copper salt can be used.

The content of aniline black is preferably 3 to 30 parts by weight, more preferably 6 to 20 parts by weight, and even more preferably 7 to 15 parts by weight with respect to 100 parts by weight of the binder resin.

  In the toner of the present invention, for the purpose of complementary color, other colorants such as carbon black and metal composite oxides may be appropriately contained within a range not impairing the effects of the present invention.

  Examples of the binder resin in the present invention include polyester, styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, a hybrid resin in which two or more kinds of resin components are partially chemically bonded, and the like. Among them, from the viewpoint of dispersibility and transferability of the colorant, polyester and a hybrid resin having a polyester component and an addition polymerization resin component such as a vinyl resin are preferable, and a polyester is more preferable. The content of the polyester is preferably 50 to 100% by weight, more preferably 80 to 100% by weight, and particularly preferably 100% by weight in the binder resin.

  The polyester may be either amorphous polyester or crystalline polyester, but in the present invention, amorphous polyester is preferable. In the present invention, “crystallinity” means that the ratio of the softening point to the maximum peak temperature of the heat of fusion (softening point / peak temperature) is 0.6 to 1.3, preferably 0.9 to 1.2, more preferably. Is greater than 1 and 1.2 or less, and “amorphous” means that the ratio of the softening point to the maximum peak temperature of heat of fusion (softening point / peak temperature) is greater than 1.3 and 4 or less, Preferably it is 1.5-3.

  The polyester is obtained by polycondensing a raw material monomer comprising an alcohol component comprising a divalent or higher alcohol and a carboxylic acid component comprising a divalent or higher carboxylic acid compound.

  Examples of the divalent alcohol include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane. Bisphenol A alkylene (carbon number 2 or 3) oxide adduct (average addition mole number 1 to 10), ethylene glycol, propylene glycol, 1,6-hexanediol, bisphenol A, hydrogenated bisphenol A and the like. .

  Examples of trihydric or higher alcohols include sorbitol, 1,4-sorbitan, pentaerythritol, glycerol, trimethylolpropane, and the like.

  Examples of the divalent carboxylic acid compound include phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid and other dicarboxylic acids, succinic acid substituted with an alkyl group or alkenyl group having 1 to 20 carbon atoms, Examples include acid anhydrides and alkyl (C1-12) esters.

  Examples of the trivalent or higher carboxylic acid compounds include 1,2,4-benzenetricarboxylic acid (trimellitic acid), its acid anhydride, and alkyl (C1-12) ester.

  The alcohol component and the carboxylic acid component may appropriately contain a monovalent alcohol and a monovalent carboxylic acid compound from the viewpoint of molecular weight adjustment and offset resistance improvement.

  Polyester is produced by, for example, polycondensation of an alcohol component and a carboxylic acid component in an inert gas atmosphere, if necessary, using an esterification catalyst, and at a temperature of 180 to 250 ° C. under reduced pressure. be able to.

  The softening point of the amorphous polyester is preferably 80 to 170 ° C., but in the present invention, from the viewpoint of improving the low-temperature fixability, it is preferable that two or more resins having different softening points of 10 ° C. or more are contained. .

  When two kinds of resins are used, the softening point of the resin having a higher softening point (high softening point resin) is preferably 120 to 170 ° C, more preferably 130 to 170 ° C, and particularly preferably 135 to 155 ° C. On the other hand, the softening point of the lower softening point resin (low softening point resin) is preferably 80 ° C. or higher and lower than 120 ° C., more preferably 90 to 115 ° C., and particularly preferably 95 to 110 ° C. Further, the difference in softening point between the high softening point resin and the low softening point resin is preferably 10 ° C. or more, more preferably 20 to 80 ° C., further preferably 30 to 60 ° C., and the high softening point resin and the low softening point. The resin weight ratio (high softening point resin / low softening point resin) is preferably 10/90 to 90/10, and more preferably 40/60 to 70/30.

  Further, the glass transition point of the amorphous polyester is preferably 50 to 85 ° C., and the acid value is preferably 0.5 to 60 mgKOH / g, and the hydroxyl value is 1 to 60 mgKOH from the viewpoint of dispersibility and transferability of the colorant. / G is preferred.

  The hybrid resin may be obtained from two or more kinds of resins as raw materials, or may be obtained from a raw material monomer of one kind of resin and another kind of resin. Although it may be obtained from a mixture of resin raw material monomers, in order to obtain a hybrid resin efficiently, those obtained from a mixture of two or more resin raw material monomers are preferred.

  The toner of the present invention may contain magnetic powder from the viewpoint of suppressing toner scattering. Examples of the magnetic powder include alloys such as magnetite, hematite, and ferrite, and ferromagnetic metal powders such as iron, cobalt, and nickel. The content of the magnetic powder is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  The toner of the present invention further includes a charge control agent, a release agent, a fluidity improver, a conductivity modifier, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an anti-aging agent, and an improved cleaning property. Additives such as additives may be appropriately added internally or externally.

  The method for producing the toner of the present invention may be any conventionally known method such as a kneading and pulverizing method, an emulsification phase inversion method, and a polymerization method, but the kneading and pulverizing method is preferred because it is easy to produce. For example, in the case of a pulverized toner by a kneading and pulverizing method, a binder resin, a colorant, and the like are uniformly mixed with a mixer such as a Henschel mixer, and then melt-kneaded with a hermetic kneader or a uniaxial or biaxial extruder. It can be produced by cooling, pulverization and classification. The weight average particle diameter of the toner is preferably 3 to 15 μm.

  When the toner of the present invention contains a magnetic fine powder, it is used alone as a developer, and when it does not contain a magnetic fine powder, it is used as a non-magnetic one-component developer or mixed with a carrier to develop a two-component developer. The toner of the present invention is preferably used as a two-component developer because it is excellent in durability.

  Since the toner of the present invention has high blackness, little toner scattering, excellent reproducibility of fine halftone dots, and prevention of leading edge drawing, it can be suitably used not only for forward development but also for reversal development. Can do.

  Furthermore, since the toner of the present invention is similar to the resistance of colorants such as yellow, cyan, and magenta, it can be suitably used for forming full-color images.

[Chromium or copper content in aniline black]
1. Samples are prepared by the wet decomposition method shown in (1) to (3) below.
(1) Collect 0.1 g of sample (aniline black) in a decomposition container.
(2) Using a microwave wet ashing apparatus (PROLABO, A-300), add 2 ml of sulfuric acid and heat, carbonize the sample, then gradually add hydrogen peroxide, Decompose.
(3) Replace the sample with a volumetric flask, add pure water and increase to 50 ml.
2. Using an ICP emission analyzer (manufactured by JobinYbon, JY238), the prepared sample is subjected to elemental analysis under the following measurement conditions to determine the chromium or copper content.
Measurement conditions High frequency power supply frequency: 40.68 MHz
Plasma output: 1000W
Plasma gas: 14L / min
Auxiliary gas: 0L / min
Sheath gas: 0.3 L / min

[Softening point of resin]
Using Koka-type flow tester “CFT-500D” (manufactured by Shimadzu Corporation), the temperature at which half of the resin flows out is defined as the softening point (sample: 1 g, heating rate: 6 ° C./min, load: 1.96 MPa, Nozzle: 1 mmφ × 1 mm).

[Glass transition point of resin]
A differential scanning calorimeter “DSC210” (manufactured by Seiko Denshi Kogyo Co., Ltd.) is used to measure at a heating rate of 10 ° C./min. The glass transition point is a physical property unique to an amorphous resin.

[Carrier saturation magnetization]
(1) Fill a plastic case with a lid with an outer diameter of 7 mm (inner diameter of 6 mm) and a height of 5 mm while tapping the carrier, and calculate the mass of the carrier from the difference between the weight of the plastic case and the weight of the plastic case filled with the carrier. .
(2) Set a plastic case filled with a carrier in the sample holder of the magnetic property measuring device “BHV-50H” (VS Magnetometer) of RIKEN ELECTRONICS CO., LTD. And add the plastic case using the vibration function. While shaking, a saturation magnetic field is measured by applying a magnetic field of 79.6 kA / m. The obtained value is converted into saturation magnetization per unit mass in consideration of the mass of the filled carrier.

Resin production example 1
2450 g of propylene oxide adduct of bisphenol A (average addition mole number: 2.2 mol), 975 g of ethylene oxide adduct of bisphenol A (average addition mole number: 2.2 mol), 259 g of isododecenyl succinic acid, terephthalic acid 961 g, trimellitic anhydride 278 g and dibutyltin oxide (esterification catalyst) 9.8 g were reacted at 230 ° C. for 8 hours under a nitrogen stream, and then the system was depressurized to 8.3 kPa to ASTM D36-86. It was made to react until the softening point measured according to this reached about 150 degreeC. The obtained resin is referred to as Resin A. Resin A had a softening point of 148 ° C., a glass transition point of 62 ° C., and an acid value of 8 mgKOH / g.

Resin production example 2
3087 g of propylene oxide adduct of bisphenol A (average addition mol number: 2.2 mol), 59 g of ethylene oxide adduct of bisphenol A (average addition mol number: 2.2 mol), 994 g of terephthalic acid, 33 g of trimellitic anhydride, After reacting 4.5 g of t-butylcatechol and 8.9 g of dibutyltin oxide (esterification catalyst) under a nitrogen stream at 230 ° C. for 6 hours, the mixture was cooled to 180 ° C., 298 g of fumaric acid was added, and 180 ° C. The temperature was raised from 10 to 210 ° C. at a rate of 10 ° C./hour, and then reacted at 210 ° C. and 8.3 kPa until the softening point measured according to ASTM D36-86 reached about 100 ° C. The resulting resin is referred to as Resin B. Resin B had a softening point of 104 ° C., a glass transition point of 61 ° C., and an acid value of 11 mgKOH / g.

Examples 1 to 4 and Comparative Examples 1 and 2
50 parts by weight of resin A, 50 parts by weight of resin B, 12 parts by weight of aniline black shown in Table 1, 2 parts by weight of charge control agent “Bontron N-01” (manufactured by Orient Chemical Co., Ltd.), charge control agent “Copy Charge PSY” 0.2 parts by weight (manufactured by Clariant), 1 part by weight of polypropylene wax “Biscol 660P” (manufactured by Sanyo Chemical Co., Ltd.) and 1.5 parts by weight of “Carnauba Wax C1” (manufactured by Kato Yoko) are preliminarily used in a Henschel mixer. After mixing, the mixture was melt kneaded with a twin screw extruder, cooled, pulverized and classified to obtain a powder having a volume average particle diameter of 10 μm.

  To 100 parts by weight of the obtained powder, 0.3 part by weight of hydrophobic silica “HVK2150” (manufactured by Clariant) was mixed and adhered by a Henschel mixer to obtain a toner.

Test example 1
The resistivity of the toner in each environment of normal temperature and normal humidity (24 ° C./50%) or high temperature and high humidity (35 ° C./85%) was measured by the following method. The results are shown in Table 1. In practice, a preferable range of the toner resistivity is 0.90 × 10 ¹¹ Ωcm or more from the viewpoint of charging, development, and transfer processes. If it is smaller than this range, the image density becomes excessively high due to a decrease in charge amount, and ground fogging occurs.

[Measurement of resistivity]
An electrode and a sample (toner pellet) are placed in a constant temperature and humidity chamber “LH-40” manufactured by Nagano Scientific Machinery Co., Ltd., and left for 3 hours in each environment. G) is measured.

5 g of toner is put into a press mold for tableting with an inner diameter of 59 mm so that the surface is uniform, and this mold is set in an electric sample molding machine (C / N: 9302/30, manufactured by Maekawa Tester Co., Ltd.). The toner pellet having a diameter of 59 mm and a thickness of about 1.7 mm is obtained by applying pressure of 10 tons for 10 seconds with the scale of the attached Bourdon tube load meter.
Using the obtained toner pellets with a precision LCR meter; HP4284 and dielectric measurement electrode; HP16451B (electrode used: electrode A) (both manufactured by Yokogawa Hewlett-Packard Company), the electrical conductivity (G) of the toner pellets at 1 kHz taking measurement.

Further, the thickness (d) of the toner pellet is measured with a micrometer, and the resistivity ρ is calculated from the following equation. In the formula, S is the main electrode area (11.34 cm ² ).
Resistivity ρ (Ωcm) = 1 / G × S / d

Test example 2
39 parts by weight of toner and 1261 parts by weight of a ferrite carrier (average particle size: 110 μm) coated with fluorine / acrylic resin and having a saturation magnetization of 60 Am ² / kg were mixed with a Nauta mixer to obtain a two-component developer. .

  The developer is mounted on the contact development method "Infoprint4000IS1" (Japan IBM Co., Ltd .: linear speed 1066mm / sec, resolution 240dpi, development system: 3 magnet rolls, selenium photoreceptor, reversal development), and a 2.5cm square solid A print pattern containing an image with a blackening rate of 8% is printed on an 11 × 18 inch continuous paper at a normal temperature and humidity (24 ° C / 50%) or high temperature and high humidity (35 ° C / 85%). Ten thousand sheets were printed. After the printing was completed, the toner charge amount, image density, and background fogging were measured by the following methods. The results are shown in Table 1.

[Charge amount]
Measure using a Q / M meter (Epping).
A specified amount of developer is put into a cell attached to the Q / M meter, and only the toner is sucked through a mesh having a mesh size of 32 μm (stainless steel, twill weave, wire diameter 0.0035 mm) for 90 seconds. The voltage change on the carrier generated at that time is monitored, and the value of the total amount of electricity (μC) / the amount of attracted toner (g) after 90 seconds is calculated as the charge amount (μC / g).

[Image density]
Four 2.5 cm square black solids using “Gretag SPM50” (Gretag, absolute white calibration; Pol filter, observation field: 2 ° C., illumination type: +, Wbase: Abs, Dstd: DIN NB, Sample mode) For each part, the image density at five locations is measured, and after measuring the image density at a total of 20 locations, the average value is taken as the image density. Practically, the preferable range of image density is 2.0 to 2.7.

[Ground cover]
Using “Model 938 Spectrodensitometer” (X-Rite, aperture: 20 mm, measurement mode: Yxy, light source: D ₆₅ , viewing angle: 10 degree), non-image of pre-printed paper (Yb) and printed paper (Ya) Part is measured, and the value of Yb-Ya is obtained. In practice, the preferred range of ground fog is 0.9 or less.

  From the above results, it can be seen that the toner containing aniline black having a low chromium or copper content has a higher resistivity and excellent charging stability against environmental changes. In particular, with respect to charging stability against environmental changes, there is no significant difference between the examples and the comparative examples at normal temperature and humidity, and both are within the preferred range. It can be seen that the decrease in the image density and the occurrence of background fogging are remarkable.

  The toner of the present invention is used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (2)

Ri Na contain a binder resin and aniline black, a toner containing no carbon black, the content of chromium contained in the aniline black, or less 0.1g per aniline black 1 kg, the aniline black A toner having a copper content of 0.09 g or less per kg of aniline black (excluding a toner containing a metal material blackened by surface treatment with aniline black) .   The toner according to claim 1, wherein the binder resin contains polyester.