Electrostatic image developing toner

The present invention provides an electrophotographic toner free of metal such as chromium. A novel electrostatic image developing toner is provided, comprising as a charge-controlling agent one or more selected from the group consisting of compounds represented by formulae (I) and (II): ##STR1## wherein A, B and R are as defined in the specification.

FIELD OF THE INVENTION 
The present invention relates to an electrostatic image developing toner 
comprising a specific compound. 
BACKGROUND OF THE INVENTION 
In the electrophotographic image formation process, an electrostatic latent 
image is formed on an inorganic photoreceptor such as selenium, selenium 
alloy, cadmium sulfide and amorphous silicon or an organic photoreceptor 
comprising a charge-generating agent and a charge-transporting agent. The 
electrostatic latent image thus formed is developed with a toner, 
transferred to a paper or plastic film, and then fixed to obtain a visible 
image. 
Photoreceptors can be charged positively or negatively depending on their 
configuration. Photoreceptors which allow a printed area to be left as an 
electrostatic latent image are developed with an oppositely-chargeable 
toner while those which allow a printed area to be destaticized to effect 
reversal development are developed with a toner chargeable to the same 
sign as the printed area. 
A toner comprises a binder resin, a colorant, and other additives. In order 
to have desirable friction chargeability (charging rate, charging level, 
charging stability, etc.), age stability and environmental stability, the 
toner normally comprises a charge-controlling agent incorporated therein. 
This charge-controlling agent has a great effect on the properties of the 
toner. 
A color toner requires a charge-controlling agent having a light-colored, 
preferably colorless charge-controlling agent that has no effect on the 
hue of the image. Examples of such a light-colored or colorless 
charge-controlling agent employable in negatively-chargeable toners 
include metal complex salts of hydroxybenzoic acid derivatives as 
disclosed in JP-B-55-42752 (The term "JP-B" as used herein means an 
"examined Japanese patent publication"), JP-A-61-69073, and JP-A-61-221756 
(The term "JP-A" as used herein means an "unexamined published Japanese 
patent application"), metallic salts of aromatic dicarboxylic acids as 
disclosed in JP-A-57-111541, metal complex salts of anthranilic acid 
derivatives as disclosed in JP-A-61-141453, and JP-A-62-94856, organic 
boron compounds as disclosed in U.S Pat. No. 4,767,688, and JP-A-1-306861, 
and biphenol compounds as disclosed in JP-A-61-3149. Examples of such a 
charge-controlling agent for positively-chargeable toners include 
quaternary ammonium salt compounds as disclosed in JP-A-57-119364, 
JP-A-58-9154, and JP-A-58-98742. 
However, these charge-controlling agents have many disadvantages. For 
example, some of these charge-controlling agents are chromium compounds 
which are liable to cause environmental pollution. Some other 
charge-controlling agents cannot fully become colorless. These 
charge-controlling agents exert insufficient effect of providing electric 
charge. Most of these charge-controlling agents can be used only for 
oppositely-chargeable toners. Further, these charge-controlling agents 
exhibit a poor dispersibility and insufficient stability. Thus, none of 
these charge-controlling agents exhibits sufficient properties. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a toner which exhibits 
no deterioration during its preparation, an excellent stability in the 
form of toner compound, an excellent dispersibility in a binder resin, and 
an excellent friction chargeability under various environmental conditions 
and thus provides an invariably high quality image. 
The foregoing object of the present invention will become more apparent 
from the following detailed description and examples. 
The inventors have found a colorless stable compound which exhibits an 
excellent dispersibility in a binder resin and can provide a toner with an 
excellent chargeability. By using this compound as a charge-controlling 
agent, the inventors have invented an excellent toner. 
In some detail, the present invention relates to an electrostatic image 
developing toner, comprising as a charge-controlling agent one or more 
selected from the group consisting of compounds represented by the 
following general formulae (I) and (II): 
##STR2## 
wherein A and B each independently represent a hydrogen atom, a halogen 
atom, an alkoxyl group, a carboxyl group, a hydroxyl group, an ester 
group, a nitro group, an amino group, an alkylamino group, an alkyl group 
which may contain a substituent(s), or a phenyl group which may contain a 
substituent(s); R represents a hydrogen atom, an alkyl group which may 
contain a substituent(s), a phenyl group which may contain a 
substituent(s), or a naphthyl group which may contain a substituent(s); m 
represents an integer 2 to 16; and n represents an integer 4 to 8. 
DETAILED DESCRIPTION OF THE INVENTION 
The electrostatic image developing toner essentially comprises a binder 
resin, a colorant, and a compound represented by the general formula (I) 
or (II) according to the present invention. Examples of the process for 
the preparation of the toner according to the present invention include a 
process which comprises kneading these materials with the binder resin 
being molten in a heat-mixer, cooling the mixture, coarse-grinding the 
mixture, finely grinding the grains, and then classifying the fine grains, 
a process which comprises dissolving these materials in a solvent, 
spraying the solution to make finely divided grains, drying the grains, 
and then classifying the grains, and a process which comprises dispersing 
a colorant and a charge-controlling agent represented by the general 
formula (I) or (II) in a suspension comprising droplets of monomers for 
constituting a binder resin, and then subjecting the dispersion to 
polymerization. 
The amount of the charge-controlling agent is generally from 0.1 to 7% by 
weight, preferably from 0.3 to 5% by weight, based on the toner. When the 
toner is used as a single component development, the amount of the binder 
resin is generally from 30 to 70% by weight based on the toner, and when 
it is used as a two component development, the amount of the binder resin 
is generally from 80 to 95% by weight based on the toner. The amount of 
the colorant is generally from 1 to 10% by weight, preferably from 2 to 7% 
by weight, based on the toner. 
The average particle size of the toner is preferably from 4 to 15 .mu.m. 
Examples of the binder resin include polystyrene, styrene-methacrylic ester 
copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, 
acrylic resin, styrene-maleic acid copolymer, olefinic resin, polyester, 
epoxy resin, polyurethane resin, and polyvinyl butyral resin. These binder 
resins may be used singly or in admixture. 
With reference to colorant, carbon black is normally used for black toners. 
For color toners, there can be used the following known colorants. The 
term "C.I." as used below is the abbreviation of "Colour Index". 
Examples of yellow colorants include azo organic pigments such as C. I. 
pigment yellow 1, C. I. pigment yellow 5, C. I. pigment yellow 12 and C. 
I. pigment yellow 17, inorganic pigments such as ocher, and oil-soluble 
dyes such as C. I. solvent yellow 2, C. I. solvent yellow 6, C. I. solvent 
yellow 14 and C. I. solvent yellow 19. 
Examples of magenta colorants include azo pigments such as C. I. pigment 
red 57, xanthene pigments such as C. I. pigment violet 1 and C. I. pigment 
red 81, thioindigo pigments such as C. I. pigment red 87, C. I. vat red 1 
and C. I. pigment violet 38, and oil-soluble dyes such as C. I. solvent 
red 19, C. I. solvent red 49 and C. I. solvent red 52. 
Examples of cyan colorants include triphenylmethane pigments such as C. I. 
pigment blue 1, phthalocyanine pigments such as C. I. pigment blue 15 and 
C. I. pigment blue 16, and oil-soluble dyes such as C. I. solvent blue 25, 
C. I. solvent blue 40 and C. I. solvent blue 70. 
The compounds represented by formula (I) or (II) are explained in more 
detail below. 
The alkoxyl group of A or B is preferably an alkoxyl group having 1 to 12 
carbon atoms, the ester group of A or B is preferably an ester group 
represented by --COOX wherein X is an alkyl group having 1 to 12 carbon 
atoms or a phenyl group which may contain a substituent(s) (such as an 
alkyl group having 1 to 12 carbon atoms, an acetyl group, an amino group, 
a nitro group, a hydroxyl group, a halogen atom, an alkoxyl group having 1 
to 8 carbon atoms, an acethylamino group, or an alkylamino group), the 
alkylamino group of A or B is preferably an alkylamino group having 1 to 8 
carbon atoms, and the alkyl group which may contain a substituent(s) of A 
or B is preferably an alkyl group having 1 to 12 carbon atoms which may 
contain a substituent(s). 
Examples of the substituent for the alkyl group of A or B include a phenyl 
group, an acetyl group, an amino group, a nitro group, a hydroxyl group, a 
halogen atom, and an alkoxyl group having 1 to 8 carbon atoms. Examples of 
the substituent for the phenyl group of A or B include an alkyl group 
having 1 to 12 carbon atoms, an acetyl group, an amino group, a nitro 
group, a hydroxyl group, a halogen atom, an alkoxyl group having 1 to 8 
carbon atoms, and an acethylamino group. 
The alkyl group which may contain a substituent(s) of R is preferably an 
alkyl group having 1 to 16 carbon atoms which may contain a 
substituent(s). 
Examples of the substituent for the alkyl group of R include an alkoxyl 
group having 1 to 8 carbon atoms, a hydroxyl group, a residue of a 
heterocyclic group having a nitrogen atom or an oxygen atom, and a halogen 
atom. Examples of the substituent for the phenyl group of R include an 
alkoxyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 
carbon atoms, an acetyl group, a hydroxyl group, a carboxyl group, a nitro 
group, an alkylamino group having having 1 to 8 carbon atoms, an amino 
group, and a halogen atom. Examples of the substituent for the naphthyl 
group of R include a hydroxyl group, a carboxyl group, a nitro group, an 
alkyl group having 1 to 8 carbon atoms, a carbamoyl group, and a halogen 
atom. 
The compounds represented by formula (I) or (II) can be prepared easily 
according to known methods. 
Specific examples of compounds of the present invention which can be used 
as charge-controlling agents include the following compounds: 
##STR3## 
The toner of the present invention may comprise a hydrophobic silica, 
metallic soap, fluorinic surface active agent, dioctyl phthalate, wax, tin 
oxide, electrically conductive zinc oxide, etc. incorporated therein as 
additives for the purpose of protecting photoreceptor and carrier, 
enhancing the fluidity and fixability of the toner, controlling the 
thermal, electrical and physical properties, resistance and softening 
point or like purposes. 
If the toner according to the present invention is incorporated in a two 
component development, a binder type carrier comprising minute glass 
beads, iron powder, ferrite powder or magnetic grains dispersed therein or 
resin-coated carrier comprising a polyester resin, fluoride resin, acrylic 
resin, silicon resin or the like coated on the surface thereof may be used 
as a carrier. The mixing ratio by weight of the toner of the present 
invention to the carrier is generally between 2/98 and 10/90. 
Further, the toner according to the present invention can also exhibit 
excellent properties as a unitary toner (single component development). 
The present invention will be further described in the following examples, 
but the present invention should not be construed as being limited 
thereto. The term "parts" as used herein means "parts by weight".

EXAMPLE 1 
One part of Compound No. (1), 5 parts of carbon black and 94 parts of a 
styrene-ethylhexyl methacrylate copolymer were kneaded in a heat-mixer at 
110.degree. to 150.degree. C., cooled, and then subjected to coarse 
grinding in a hammer mill. The coarse grains were subjected to fine 
grinding in a jet mill, and then classified to obtain a black toner having 
a size of 10 to 12 .mu.m. The toner thus obtained was mixed with an iron 
powder carrier in a weight ratio of 4:100, and then shaken. As a result, 
the toner was negatively charged. The toner was measured for charge by 
means of a blow-off powder charge meter (manufactured by Toshiba Chemical 
Co., Ltd.). The result was -21 .mu.c/g. With this toner, an image was 
reproduced by means of a remodelled commercial duplicating machine. As a 
result, a sharp image could be obtained at the initial stage as well as 
after duplicating 10,000 sheets. 
EXAMPLE 2 
One part of Compound No. (12), 5 parts of carbon black and 94 parts of a 
styrene-ethylhexyl methacrylate copolymer were kneaded in a heat-mixer at 
110.degree. to 150.degree. C., cooled, and then subjected to coarse 
grinding in a hammer mill. The coarse grains were subjected to fine 
grinding in a jet mill, and then classified to obtain a black toner having 
a size of 10 to 12 .mu.m. The toner thus obtained was mixed with an iron 
powder carrier in a weight ratio of 4:100, and then shaken. As a result, 
the toner was negatively charged. The toner was measured for charge by 
means of a blow-off powder charge meter. The result was -18 .mu.c/g. With 
this toner, an image was reproduced by means of a remodelled commercial 
duplicating machine. As a result, a sharp image could be obtained at the 
initial stage as well as after duplicating 10,000 sheets. 
EXAMPLE 3 
One part of Compound No. (1), 5 parts of Spilon Blue 2BNH (available from 
Hodogaya Chemical Co., Ltd.) as a copper phthalocyanine oil-soluble dye 
and 94 parts of a styrene-butyl methacrylate copolymer were kneaded in a 
heat-mixer at 110.degree. to 150.degree. C., cooled, and then subjected to 
coarse grinding in a hammer mill. The coarse grains were subjected to fine 
grinding in a jet mill, and then classified to obtain a blue toner having 
a size of 10 to 12 .mu.m. The toner thus obtained was mixed with an iron 
powder carrier in a weight ratio of 4:100, and then shaken. As a result, 
the toner was negatively charged. The toner was measured for charge by 
means of a blow-off powder charge meter. The result was -23 .mu.c/g. With 
this toner, an image was reproduced by means of a remodelled commercial 
duplicating machine. As a result, a sharp image could be obtained at the 
initial stage as well as after duplicating 10,000 sheets. 
EXAMPLE 4 
One part of Compound No. (1), 5 parts of carbon black and 94 parts of a 
styrene-ethylhexyl methacrylate copolymer were kneaded in a heat-mixer at 
110.degree. to 150.degree. C., cooled, and then subjected to coarse 
grinding in a hammer mill. The coarse grains were subjected to fine 
grinding in a jet mill, and then classified to obtain a black toner having 
a size of 10 to 12 .mu.m. The toner thus obtained was mixed with a silicon 
coating carrier in a weight ratio of 4:100, and then shaken. As a result, 
the toner was negatively charged. The toner was measured for charge by 
means of a blow-off powder charge meter. The result was -14 .mu.c/g. With 
this toner, an image was reproduced by means of a remodelled commercial 
duplicating machine. As a result, a sharp image could be obtained at the 
initial stage as well as after duplicating 10,000 sheets. 
EXAMPLE 5 
One part of Compound No. (14), 5 parts of carbon black and 94 parts of a 
styrene-ethylhexyl methacrylate copolymer were kneaded in a heat-mixer at 
110.degree. to 150.degree. C., cooled, and then subjected to coarse 
grinding in a hammer mill. The coarse grains were subjected to fine 
grinding in a jet mill, and then classified to obtain a black toner having 
a size of 10 to 12 .mu.m. The toner thus obtained was mixed with an acryl 
coating carrier in a weight ratio of 4:100, and then shaken. As a result, 
the toner was negatively charged. The toner was measured for charge by 
means of a blow-off powder charge meter. The result was -18 .mu.c/g. With 
this toner, an image was reproduced by means of a remodelled commercial 
duplicating machine. As a result, a sharp image could be obtained at the 
initial stage as well as after duplicating 10,000 sheets. 
EXAMPLE 6 
One part of Compound No. (11), 60 parts of magnetic iron powder and 100 
parts of a styrene-acryl copolymer were kneaded in a heat-mixer at 
110.degree. to 150.degree. C., cooled, and then subjected to coarse 
grinding in a hammer mill. The coarse grains were subjected to fine 
grinding in a jet mill, and then classified to obtain a black toner having 
a size of 10 to 12 .mu.m. With this unitary toner, an image was reproduced 
by means of a remodelled commercial duplicating machine. As a result, a 
sharp image could be obtained at the initial stage as well as after 
duplicating 10,000 sheets. 
EXAMPLES 7 to 22 
Toners were prepared in the same manner as in Example 1 except that 
compounds as set forth in Table 1 were used instead of Compound No. (1). 
The results are set forth in Table 1. 
TABLE 1 
______________________________________ 
Image quality 
Toner charge 
Initial 
After 10,000 
Example Compound (-.mu./g) stage 
sheets 
______________________________________ 
7 Compound No. (2) 
13 Sharp 
Sharp 
8 Compound No. (3) 
16 Sharp 
Sharp 
9 Compound No. (5) 
21 Sharp 
Sharp 
10 Compound No. (6) 
22 Sharp 
Sharp 
11 Compound No. (8) 
23 Sharp 
Sharp 
12 Compound No. (9) 
14 Sharp 
Sharp 
13 Compound No. (10) 
17 Sharp 
Sharp 
14 Compound No. (16) 
18 Sharp 
Sharp 
15 Compound No. (15) 
17 Sharp 
Sharp 
16 Compound No. (17) 
19 Sharp 
Sharp 
17 Compound No. (18) 
17 Sharp 
Sharp 
18 Compound No. (19) 
14 Sharp 
Sharp 
19 Compound No. (20) 
15 Sharp 
Sharp 
20 Compound No. (21) 
23 Sharp 
Sharp 
21 Compound No. (22) 
25 Sharp 
Sharp 
22 Compound No. (23) 
17 Sharp 
Sharp 
______________________________________ 
The toner comprising a compound according to the present invention as a 
charge-controlling agent exhibits an excellent environmental resistance 
and age stability. As a result, a high quality electrostatic image 
developing toner which causes no duplicating stain or other troubles is 
provided. Further, since the charge-controlling agent is white or 
substantially colorless itself and hence has no effect on the saturation 
of the colorant, an arbitrary colorant can be selected depending on the 
hue necessary for color toner, by no means impairing the characteristic 
hue of dyes and pigments. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.