JP2001265061A - Positively chargeable toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positively chargeable toner excellent in static charge characteristics such as rising property and static charge stability and capable of obtaining excellent images continuously without causing any contamination of a photoreceptor or any deterioration of picture quality even when it is used for a high speed machine. SOLUTION: The positively chargeable toner contains a binder resin containing polyester having <=10 KOHmg/g acid value, coloring agent and nigrosine dye. The difference in the UV absorption spectrum between 570 nm and 600 nm is 0.08 to 0.18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In a high-speed machine having a photoreceptor having a peripheral speed of 400 mm / sec or more, the rising property of the charge amount of toner becomes important. If sufficient start-up property is not obtained at the time of toner replenishment, image deterioration due to toner having a poor charge amount is caused. Furthermore, since high-speed machines require long-term printing, how to maintain the toner charge amount stably is an important issue.

Therefore, in order to improve the rise of the charge amount, a method of adding a large amount of a charge control agent to the toner is used. In particular, a toner containing a polyester is excellent in fixability, durability and the like. However, it is necessary to add a larger amount of a charge control agent in order to use the resin itself for negatively chargeable toner due to its negative chargeability. However, if a large amount of the internal additive is added, various problems such as poor dispersion, increased cost, contamination of the photoconductor, and contamination of the carrier may occur.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an excellent charging characteristic such as rising property and charging stability, and to prevent contamination of a photoreceptor and image quality even when used in a high-speed machine. An object of the present invention is to provide a positively chargeable toner capable of continuously obtaining excellent images.

[0005]

According to the present invention, an acid value of 10 m is provided.
A positively chargeable toner containing a binder resin containing a polyester of not more than gKOH / g, a colorant and a nigrosine dye, wherein the difference between the UV absorption spectra of the toner at 570 nm and 600 nm is 0.08 to 0. .18 regarding the positively chargeable toner.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the positively chargeable toner of the present invention, a specific polyester is used as a binder resin, and a dispersion state of a nigrosine dye contained as a charge control agent on the toner surface is adjusted to a specific range. It is characterized by points. That is, a specific polyester as a binder resin,
Only by appropriately dispersing the nigrosine dye in this, the subject of the present invention is solved. It is considered that the absorption at 570 nm correlates with the toner surface amount of the nigrosine dye, and the absorption at 600 nm correlates with the dispersion diameter of the nigrosine dye.
The dispersion state of the nigrosine dye can be adjusted by adjusting the difference between the ultraviolet absorption spectra of the toner of the present invention at 570 nm and 600 nm (hereinafter referred to as _Δ570-600 ). In the present invention, Δ _570-600 is 0.08
To 0.18, preferably 0.10 to 0.16, more preferably 0.12 to 0.15. Δ _{570-60 0} is 0.0
If it is less than 8, the nigrosine dye is excessively dispersed, and a large amount of the nigrosine dye is present not only on the toner surface but also inside the toner. Abundance becomes relatively small. On the other hand, when _Δ570-600 exceeds 0.18, the dispersion of the nigrosine dye is insufficient, so that the nigrosine dye is detached from the toner surface during the pulverization and classification in the toner production process, and the distribution of the toner surface becomes uneven. This causes contamination of the photoreceptor and image defects. Although the details of the interaction between the specific polyester and the nigrosine dye are unknown, it is considered that the compatibility between the two is in an appropriate range, so that the nigrosine dye can take an optimal dispersion state.

The ultraviolet absorption spectrum of the toner at 570 nm and 600 nm can be measured by the method described in Examples. Further, _since the adjustment of _Δ570-600 varies depending on the production equipment and scale of the toner, it cannot be unconditionally determined. However, for example, the premixing time of the raw material composition, the supply amount of the raw material composition to the extruder, Examples include a method of adjusting the barrel temperature during kneading and the like, and a method of preliminarily kneading a part of the binder resin and the nigrosine dye and then kneading them together with the remaining raw material composition. Specifically, in order to increase the dispersion of the nigrosine dye, it is effective to increase the pre-mixing time, reduce the supply amount to the extruder, lower the barrel temperature, and the like. It is preferable to obtain a desired dispersion state by appropriately combining them.

The toner of the present invention contains a binder resin, a colorant and a nigrosine dye, and the binder resin contains polyester. The content of the polyester, the dispersibility of the colorant,
From the viewpoints of fixability and chargeability, the content is preferably 50 to 100% by weight, more preferably 90 to 100% by weight, and particularly preferably 100% by weight in the binder resin. In addition, as a resin that can be used other than polyester, styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and the like can be given.

The raw material monomer of the polyester in the present invention is not particularly limited, and a known alcohol component and a known carboxylic acid component such as carboxylic acid, carboxylic anhydride and carboxylic acid ester are used.

The alcohol component includes a compound represented by formula (I):

[0011]

Embedded image

(Wherein, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, the sum of x and y is 1 to 16,
(Preferably 1.5 to 5.0).

The compounds represented by the formula (I) include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene (2.
2) Bisphenol A alkylene (C2-3) such as -2,2-bis (4-hydroxyphenyl) propane
Oxide (average addition mole number 1 to 16) adduct and the like. Other alcohol components include ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or their alkylene (2-4 carbon atoms) oxides (average addition moles 1-1).
16) adducts and the like, and it is preferable to contain one or more of these.

The content of the compound represented by the formula (I) in the alcohol component is 5 mol% or more, preferably 50 mol%.
Above, more preferably 100 mol% is desirable.

Examples of the carboxylic acid component include dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid and maleic acid; alkyl groups having 1 to 20 carbon atoms such as dodecenyl succinic acid and octyl succinic acid; ~
Succinic acid, trimellitic acid, pyromellitic acid, anhydrides of these acids and alkyl (C1-8) esters of those acids, etc. substituted with 20 alkenyl groups; Those containing are preferred.

The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to polycondensation in an inert gas atmosphere, if necessary, using an esterification catalyst at a temperature of 180 to 250 ° C. it can.

The acid value of the polyester is 10 mgKOH / g or less, preferably 7 mgKOH / g or less in order to obtain a sufficient charge amount as a positively chargeable toner. The polyester has a hydroxyl value of 20 to 40 mgKOH / g, a softening point of 110 to 160 ° C, and a glass transition point of 50 to 70 ° C.
Are each preferable.

As the coloring agent, all dyes and pigments used as coloring agents for toner can be used. Carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment green B, rhodamine- B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, quinacridone, carmine 6B, disazo yellow, and the like, and these can be used alone or in combination of two or more. The content of the coloring agent is as follows.
The amount is preferably 1 to 10 parts by weight with respect to 00 parts by weight.

Nigrosine dyes include "Nigrosine Base EX", "Oil Black BS", "Oil Black SO", "Bontron N-01", and "Bontron N-
04 "," Bontron N-07 "," Bontron N-0 "
9 "and" Bontron N-11 "(all manufactured by Orient Chemical Industries, Ltd.). The content of the nigrosine dye is preferably from 1.5 to 3.5 parts by weight, more preferably from 2.0 to 3.0 parts by weight, based on 100 parts by weight of the binder resin.

In the present invention, an appropriate amount of a charge control agent other than the nigrosine dye may be blended if necessary.

In the present invention, additives such as a release agent, a conductivity modifier, a reinforcing pigment such as an extender, a fibrous substance, an antioxidant, an antioxidant, a fluidity improver, and a cleaning improver. May be appropriately added to the toner.

The toner of the present invention is preferably a pulverized toner obtained by a kneading and pulverizing method. For example, after a binder resin, a colorant, a nigrosine dye, and the like are uniformly mixed by a mixer such as a ball mill, a closed kneader or It can be produced by melt-kneading with a single-screw or twin-screw extruder, cooling, pulverizing and classifying. Further, a fluidity improver or the like may be added to the surface of the toner as needed. The weight average particle diameter of the toner thus obtained is preferably 3 to 15 μm.

Since the positively chargeable toner of the present invention is excellent in charging characteristics such as rising property of the charge amount and durability, a high-speed toner having a photosensitive member having a peripheral speed of 400 mm / sec or more, particularly 500 mm / sec or more. Can also be suitably used.

The toner of the present invention can be used alone as a developer when it contains a magnetic fine powder, as a non-magnetic one-component developer when it does not contain a magnetic fine powder, or as a mixture with a carrier. Used as a component developer. The use as a two-component developer is preferable from the viewpoint of the high-speed machine.

[0025]

[Examples] [Acid value and hydroxyl value] Measured according to the method of JIS K0070.

[Softening point] The temperature at which half of the resin flows out is taken as the softening point using a high-quality flow tester (CFT-500D, manufactured by Shimadzu Corporation) (sample: 1 g, heating rate: 6 ° C.)
/ Min, load: 1.96MPa, nozzle: 1mmφ × 1m
m).

[Glass transition point] Differential scanning calorimeter "DSC"
210 "(manufactured by Seiko Denshi Kogyo KK) at a heating rate of 10 ° C / min.

[Ultraviolet absorption spectrum] Toner 0.50
g in a 500 ml glass bottle, and ethanol 20
and 250 ml / min using a ball mill stirrer.
And stir for 20 minutes. After stirring, further ethanol 20m
After the mixture was left for 1 hour, the UV absorption spectra at 570 nm and 600 nm were measured using the supernatant by the following measuring apparatus. Ethanol used as a solvent in the present invention does not dissolve the toner itself and only the nigrosine dye present on the toner surface dissolves. Therefore, by examining the UV spectrum, the state of the nigrosine dye present on the toner surface is estimated. It is thought that we can do it.

<Measuring Apparatus> Measuring instrument: Shimadzu UV-visible spectrophotometer UV-160A (manufactured by Shimadzu Corporation) (Ethanol is used as a base) Cell: quartz optical path 1 cm cell

Resin Production Example 1 Polyoxypropylene (2.2) -2,2-bis (4-
735 g of hydroxyphenyl) propane, 293 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 280 g of isophthalic acid, 60 g of isooctenylsuccinic acid, 72 g of trimellitic acid and dibutyltin oxide (esterification catalyst 2) ASTM E28 while stirring 2 g under vacuum at 230 ° C. under nitrogen atmosphere
The reaction was carried out until the softening point measured by -51T reached 136 ° C to obtain resin A. Resin A is a pale yellow solid, having an acid value of 3.1 mgKOH / g and a hydroxyl value of 35.2.
mg KOH / g, glass transition point was 63 ° C.

Resin Production Example 2 Resin B was obtained in the same manner as in Resin Production Example 1, except that the amount of isooctenyl succinic acid was changed to 72 g and the amount of trimellitic acid was changed to 66 g. Resin B has an acid value of 6.2 mg KOH / g and a hydroxyl value of 30.9 mg KO
H / g and glass transition point were 63 ° C.

Resin Production Example 3 The amount of isooctenyl succinic acid used was changed to 72 g and the amount of trimellitic acid used was changed to 70 g, respectively.
Resin C was obtained in the same manner as in Resin Production Example 1 except that the time reached OH / g. Acid value of Resin C is 12.5mg
KOH / g, hydroxyl value was 31.2 mg KOH / g, softening point was 145 ° C, and glass transition point was 64 ° C.

Resin Production Example 4 The amount of isophthalic acid used was 199 g, the amount of isooctenyl succinic acid was 214 g, and the amount of trimellitic acid was 1
Resin D was obtained in the same manner as in Resin Production Example 1 except that the reaction was terminated at a point when the acid value reached 23.0 mgKOH / g, instead of following the softening point. Was. Resin D has an acid value of 23.0 mgKOH / g, a hydroxyl value of 31.2 mgKOH / g, a softening point of 145 ° C.,
The glass transition point was 64 ° C.

Examples 1-4, Comparative Examples 1-5 100 parts by weight of the binder resin shown in Table 1, 5 parts by weight of carbon black "R330R" (manufactured by Cabot Corporation), and Nigrosine dye "Bontron N-01" (Orient Chemical Co., Ltd.) 2 parts by weight) and 2 parts by weight of the release agent "NP-055"
Premixed and melt-kneaded under the kneading conditions shown in Table 1 by an extruder “PCM-30” (manufactured by Ikegai Co., Ltd.), finely pulverized by a jet mill, and classified by an airflow classifier to obtain a weight average particle diameter of 10 μm.
m were obtained. For 100 parts by weight of the obtained powder,
0.3 parts by weight of hydrophobic silica "HVK-2150" (manufactured by Wacker Chemicals) was mixed and attached using a Henschel mixer to obtain a toner.

Example 5 20 parts by weight of resin B and nigrosine dye "Bontron N-0"
1 "(manufactured by Orient Chemical Industry Co., Ltd.) and 2 parts by weight were previously mixed and kneaded, and coarsely pulverized by a rotoplex. The obtained coarsely pulverized product, 80 parts by weight of resin B, carbon black “R”
330R "(manufactured by Cabot Corporation) and 5 parts by weight
After preliminarily mixing and melt-kneading 2 parts by weight of P-055 under the kneading conditions shown in Table 1, a toner was obtained in the same manner as in Example 1.

Comparative Examples 6 and 7 Toner was prepared in the same manner as in Example 1 except that the amount of Bontron N-01 was changed to 1 part by weight in Comparative Example 6 and 4 parts by weight in Comparative Example 7. I got

Table 1 shows the UV absorption spectra of the toners obtained in Examples 1 to 5 and Comparative Examples 1 to 7 at 570 nm and 600 nm, and their differences.

[0038]

[Table 1]

Test Example 1 A developer was prepared by stirring 4 parts by weight of a toner and 96 parts by weight of a silicon ferrite carrier having an average particle diameter of 100 μm with a V blender for 15 minutes. The obtained developer is used as a selenium photosensitive member (peripheral speed: 600 mm) for forming a positively charged electrostatic image.
/ Sec) and 500,00
Zero images were printed continuously. 200 for continuous printing
A small amount of developer is sampled after printing 0 sheets (initial printing) and after printing (after printing), and the charge amount of the toner is measured with a “q / m meter” (manufactured by Epping Corporation).
The image quality and the degree of photoconductor contamination were evaluated. Table 2 shows the results.

[0040]

[Table 2]

From the above results, the toners of Examples 1 to 5 have an appropriate dispersion of the nigrosine dye, so that they have stable charging characteristics even after printing, and excellent images can be obtained without contamination of the photoreceptor. You can see that. On the other hand, in the toners of Comparative Examples 1 to 6, since the nigrosine dye was excessively dispersed and the toner surface amount was small, the rise of the charge amount was slow and the charge stability was lacking. Has a large dispersion diameter and good charging characteristics, but the nigrosine dye is detached and the charge distribution of the toner becomes non-uniform.

[0042]

According to the present invention, since the charge control agent is appropriately dispersed in the polyester, the charge control agent has excellent charging characteristics such as rising properties and charging stability. It has become possible to provide a positively chargeable toner capable of continuously obtaining excellent images without causing contamination and image quality deterioration.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shinji Moriyama 1334 Minato, Wakayama City, Kao Corporation Research Institute (72) Inventor Koji Akiyama 1334 Minato, Wakayama City, Kao Corporation Research Institute F-term (reference) 2H005 AA01 AA06 CA08 CA21 DA03 EA10

Claims (2)

[Claims] 1. A positively chargeable toner comprising a binder resin containing a polyester having an acid value of 10 mg KOH / g or less, a colorant and a nigrosine dye,
A positively chargeable toner having a difference in ultraviolet absorption spectrum of the toner between m and 600 nm of 0.08 to 0.18. 2. The positively chargeable toner according to claim 1, which is used for a high-speed machine having a photosensitive member having a peripheral speed of 400 mm / sec or more.