Single-component non-magnetic toner developer for electrophotographic processes

A non-magnetic one-component toner developer for use in electrophotographic processes having a particle size distribution represented by the following expressions: d.sub.1 /d.sub.50 =0.32.about.0.55; d.sub.50 /d.sub.90 =0.50.about.0.70; and d.sub.50 =5-15.mu., wherein d.sub.1, d.sub.50, and d.sub.90 represent diameters of toner particles when the percentiles by volume or by weight of toner developer of that diameter are 1%, 50%, and 90%, respectively. The non-magnetic one-component toner developer disclosed in the present invention has a triboelectricity greater than 1.5 .mu.C/g, a bulk specific gravity than 0.36, and a compression ratio less than 0.24, and exhibits excellent triboelectrification characteristics and flowability, as well as provides uniformly clear images without foggy background.

FIELD OF THE INVENTION 
This invention relates to a single-component, or the so-called 
one-component, toner developer for electrophotographic processes. More 
particularly, this invention relates to a non-magnetic single-component, 
or the so-called one-component, toner developer for use in laser printers 
or copiers which exhibits excellent triboelectrification characteristics 
and flowability, and provides uniformly clear images without foggy 
background. 
BACKGROUND OF THE INVENTION 
An electrophotographic process typically comprises six main steps: 
charging, photocharging, imaging, image transfer, development, and 
cleaning. Toner developers are used in the image transfer step to 
transform electrostatic latent images into positive images, which are then 
transferred onto papers or transparent films to produce printed copies. 
With a binary- or two-component developing system, the toner developer 
contains toner particles and carrier particles. The toner particles are 
first electrostatically charged through triboelectrification with the 
carrier particles, so that the charged toner particles can be subsequently 
electrostatically attracted to an electrostatic latent image on a 
photoconductor. Electrophotographic processes using two-component toners 
have been widely used in electronic facsimile devices, mainly because of 
their excellent image resolution, and their high electric resistance which 
allows the image forming process relatively unaffected by humidity and 
other environmental variables. 
Two-component toner systems, however, have exhibit several disadvantages in 
that they involve relatively complicated machine construction and are 
difficult to maintain. Furthermore, since a toner in a two-component toner 
system is triboelectrically charged by mutual friction between the toner 
and the carrier, the surface of the carrier will be contaminated with the 
toner after the two-component toner is used for a certain period of time. 
When this occurs, the surface of the carrier will be contaminated with a 
very thin layer of minute toner particles, thus making it difficult or 
even impossible to apply sufficient triboelectric charge to the toner. 
In recent years, various electrophotographic processes utilizing a magnetic 
one-component toner developer have been developed. A one-component toner 
developer contains only the toner component and is free of any carrier. A 
magnetic one-component toner developer typically contains 30-60 wt % 
magnetic powders. U.S. Pat. Nos. 3,909,258 and 4,121,931 provide 
disclosures of such magnetic one-component toner developers, and the 
contents thereof are incorporated herein by reference. An 
electrophotographic process utilizing one-component toner developer has 
the advantages in that it involves a much simplified equipment 
construction, and is much easier to maintain. However, the magnetic 
one-component developers also have several disadvantages, for example: (1) 
because they contain large amounts (30-60 wt %) of magnetic powders, the 
electrical resistance thereof is substantially reduced, thus resulting in 
inferior resolution and susceptibility to environmental changes; (2) the 
large amounts of magnetic powders contained therein also adversely affect 
the thermal fixing ability of the resultant toner developers; and (3) 
because magnetic powders are mainly comprised of black colored Fe.sub.3 
O.sub.4 filler material, this makes it essentially impossible to obtain 
non-black color toner developers. 
In more recent years, electrophotographic processes utilizing non-magnetic 
one-component toner developer have also been developed. The non-magnetic 
one-component toner developer systems have a promising potential to 
provide all the advantages of the magnetic one-component toner developer 
systems, yet avoiding most if not all the of disadvantages thereof. 
However, it still remains a great challenge to develop a suitable 
non-magnetic one-component toner developer that fulfills it potential. 
First of all, a non-magnetic one-component toner developer must possess 
rapid triboelectrification characteristics as well as an ability to carry 
sufficient triboelectric charge, so as to allow the same to be adequately 
charged triboelectrically in order to form an image on a photoconductor 
during the very short duration of its frictional contact with a doctor 
blade or a conveyer roller. 
Because of its inadequate triboelectric charging characteristics, a toner 
designed for a conventional two-component toner developer cannot be used 
in a one-component toner electrophotographic imaging process. However, in 
a two-component toner developer system this shortcoming is overcome by the 
additional blending and friction between the toner and the carrier to 
achieve adequate triboelectrification. 
FIG. 1 is a simple illustrative diagram describing an electrophotographic 
device utilizing a non-magnetic one-component toner developer. Toner 2, 
which is stored in a toner storage tank 1, is carried by a spongy shaft 
carrier 3 to a developer sleeve 4. A doctor blade 5 controls the thickness 
of the toner on the developer sleeve. The frictional contact between the 
doctor blade 5 and the developer sleeve 4 causes the toner to become 
triboelectrically charged. The charged toner then is moved from the 
developer sleeve onto the electrostatic image on the photoconductor 6. 
It has been recognized that, in order to ensure excellent printing quality 
using a non-magnetic one-component toner developer, it is very important 
to design and control the particle size of the toner developer and the 
distribution thereof. The particle size distribution of toners directly 
affects the their triboelectrification characteristics and flowability. If 
the toner has a particle size distribution that is too broad, it will not 
be able to provide good printing quality, as the broadly distributed toner 
particles are likely to contain excessive amounts of very large and/or 
very small particles. Both could adversely affect the triboelectrification 
characteristics and flowability of the toner composition. Very large 
particles not only cause the triboelectrification characteristics of the 
toners to be lowered, they also directly cause a deterioration of the 
resolution of the printed copies. Some of the problems observed from using 
toners that contain excessive amounts of larger particles include: 
protruded characters in the printed documents; blocky graphics which are 
rough and non-smooth; decreased shininess in the prints; increased toner 
consumption; etc. 
If, however, the toner composition contains excessive amounts of very small 
particles, not only that the flowability of the toner will be impaired, 
thus causing non-uniform printing quality, the triboelectrification 
characteristics of the toner will also be adversely affected. The latter 
causes the problems of reduction in the print toner concentration, 
formation of ghost or fog background, deterioration in thermal fixability, 
as well as contamination of the copier or printer components. The main 
reason for these problems is that, due to their similarity in composition 
with the majority of the toner developer, these fine particles will 
possess excessively high triboelectricity, thus bringing in a competition 
with the main components of the toners during the image developing 
process. This results in a deterioration in the print quality. 
Furthermore, because of their excessively large surface area per unit 
weight, the fine particles will adversely affect the thermal fixing 
process, thus causing the printed characters or graphics to be easily 
peeled off. On the other hand, the fine particles, which are formed during 
the fine grinding step, often exhibit relatively non-uniform properties 
compared to the majority of the toner particles. This aberration causes 
some of these fine particles to be reversely charged or even carrying very 
low charges. The constitutes the main reason for the occurrence of ghost 
background. 
From the above described considerations, it is hence extremely important to 
design and control the size distribution of the toner particles, in order 
to ensure consistent printing and/or copying qualities, i.e., a uniformly 
clear image in the solid region and no fog or ghost in the background 
region. 
U.S. Pat. No. 5,063,133, issued to T. Kubo, et al., discloses a toner 
developer for electrophotographic process which satisfies the expression: 
d.sub.75 /d.sub.25 .ltoreq.d.sub.50 /40+1.2, wherein d.sub.25, d.sub.50, 
and d.sub.75 represent diameters of toner particles when the percentiles 
by volume or by weight or toner developer of that diameter are 25%, 50%, 
and 75%, respectively. The primary object of the '133 patent was to 
provide uniformly clear images without the fog or ghost background. 
However, the criterion disclosed in the '133 patent appears to be grossly 
inadequate, as illustrated below by results from tests conducted by the 
inventors. Many toner developers fit the criterion of the '133 patent but 
do not provide good printing quality. On the other hand, many toner 
developers that do not fit the criterion of the '133 patent actually 
provide excellent printing qualities. Therefore, a different but more 
rigorous as well as more accurate definition is necessary in order to 
design and control the optimum particle size distribution of toner 
developers. 
In addition to the particle size distribution, other factors can be equally 
important in ensuring a good quality of the printed products. These 
factors include triboelectrification characteristics and flowability of 
the toner developer. European Pat. App. No. 0 438 245 A2 discloses a 
non-magnetic one-component toner developer comprising colored fine 
particles and inorganic powders, such as silicon dioxide, which have been 
surface-treated with a silicone oil, a silane coupling agent or a silazane 
compound, to impart hydrophobicity. The blending of the hydrophobically 
treated fine powders with the toner developer improves the 
triboelectrification characteristics and flowability of the final toner 
composition. One of the disadvantages of the toner developers disclosed in 
the '245 prior art is that the silicon dioxide particles, which exhibit 
the characteristics of primary particles before the 
hydrophobicity-imparting surface treatment, are likely to form primary 
aggregates or even bulk aggregates after the treatment, regardless of 
whether the treatment is done using a spraying method or a solution 
soaking method. The formation of the aggregates prevents the toner/silicon 
oxide composition from being effectively blended, and greatly undermines 
the benefits that were originally designed to improve the 
triboelectrification characteristics and flowability thereof. 
SUMMARY OF THE INVENTION 
The primary object of the present invention is to develop a non-magnetic 
one-component toner developer for use in electrophotographic processes 
which overcomes many of the above-mentioned disadvantages of prior art 
toner developers. More particularly, the primary object of the present 
invention is to develop a non-magnetic one-component toner developer with 
an appropriate particle size distribution, which can be rigorously and 
accurately described by a set of mathematical expressions and controlled, 
to thereby ensure consistently good printing/copying qualities when used 
in electrophotographic processes. 
Another object of the present invention is to develop a non-magnetic 
one-component toner developer for use in electrophotographic processes 
which exhibits excellent triboelectrification characteristics and 
excellent particle flowability thus allowing excellent print/copying 
quality to be obtained. The copies or prints obtained from the 
electrophotographic process utilizing the non-magnetic one-component toner 
developer disclosed in the present invention exhibit uniformly clear 
resolution, and are free from many undesired poor print/copy qualities 
such as blurred edges, hollow defects, or ghost background. 
To achieve the objects described hereinabove, the present invention 
discloses a non-magnetic one-component toner developer whose particle size 
is described by the following expressions: d.sub.1 /d.sub.50 
=0.32.about.0.55; d.sub.50 /d.sub.90 =0.50.about.0.70; and d.sub.50 =5-15 
.mu.m, wherein d.sub.1, d.sub.50, and d.sub.90 represent diameters of 
toner particles when the percentiles by volume or by weight of toner 
developer of that diameter are 1%, 50%, and 90%, respectively. 
The non-magnetic one-component toner developer disclosed in the present 
invention exhibits excellent triboelectrification characteristics and 
excellent particle flowability. The triboelectric charge measured from the 
toner developer of the present invention exceeds 15 .mu.C/g (microcoulomb 
per gram), measured using a triboelectrometer. The flowability of the 
toner developer of the present invention is measured using a powder 
tester; the results show a bulk specific gravity greater than 0.36, and a 
compression ratio less than 0.24.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
In the present invention, the particle size and particle size distribution 
of the toner developers were measured using an ANALYSETT 22 TICLE 
SIZER, manufactured by FRITSCH, in Germany. All the toner developers of 
the present invention meet the following set of expressions: d.sub.1 
/d.sub.50 =0.32.about.0.55; d.sub.50 /d.sub.90 =0.50.about.0.70; and 
d.sub.50 =5-15 .mu.m, wherein d.sub.1, d.sub.50, and d.sub.90 represent 
diameters of toner particles when the percentiles by volume or by weight 
of toner developer of that diameter are 1%, 50%, and 90%, respectively. It 
has been observed by the inventors that if a toner developer has a d.sub.1 
/d.sub.50 &lt;0.32 or d.sub.50 /d.sub.90 &lt;0.50, it considered to have an 
improper particle size distribution, i.e., they have either an excessively 
large number of very fine particles or an excessively large number of very 
large particles, or both. This often results in poor printing/copying 
qualities. On the other hand, if d.sub.1 /d.sub.50 &gt;0.55 or if d.sub.50 
/d.sub.90 &gt;0.70, the production yield of toners would decrease 
substantially, thus resulting in increased production cost and rendering 
the production process uneconomic. 
Triboelectrification characteristics of the toner developers of the 
invention were measured using a q/m-meter type triboelectrometer 
manufactured by Dr. R. H. Epping PES-Laboratorium in Germany. Precisely 
one g of toner developer and 19 g of carrier (TEFV 100/200, from Powdertee 
K. K., Japan) were added to a 80-ml PE pot. The mixture was uniformly 
mixed using a ball mill at a constant rotational speed of 200 rpm for 15 
minutes to prepare a test sample. 1.0.about.1.1 g of the test sample was 
precisely measured and blown off, using a soft blow method and under a 
testing condition of 3 bar air pressure and 3 liter/min air flow rate, for 
90 seconds to measure triboelectricity. The triboelectricity of the toner 
developer should be greater than 15 .mu.C/g. Below 15 .mu.C/g, the toner 
developer will not be able to produce good quality prints and/or copies, 
due to inadequate triboelectrification. 
Flowability of the toner developer was tested using a powder tester Model 
KYT-3000 Tap Denser manufactured by Seishin Enterprises Co., Ltd. 
Flowability tests were conducted under the conditions of 100-ml tapping 
cell, 5-cm spacer height, and zero feed control; and the samples were 
repeatedly tapped 250 times to measure bulk specific gravity and 
compression ratio thereof. The toner developers of the present invention 
exhibited a bulk specific gravity of greater than 0.36, and a compression 
ratio less than 0.24. It was observed that good printing/copying results 
cannot be obtained if the bulk specific gravity was less than 0.36, or if 
the compression ratio was greater than 0.24. 
In the preferred embodiments of the present invention, a charge control 
agent can be added to the toner developer composition. A preferred charge 
control agent has the following formula: 
##STR1## 
The present invention will now be described more specifically with 
reference to the following examples. It is to be noted that the following 
descriptions of examples including preferred embodiments of this invention 
are presented herein for purpose of illustration and description; it is 
not intended to be exhaustive or to limit the invention to the precise 
form disclosed. 
Example 1 
87 parts of binder resin (styrene-acrylic copolymer, ZSR-1005, manufactured 
by Polytribo, U.S.A.), 13 parts of carbon black (Raven 5750, from Columbia 
Chemical Co., U.S.A.), 2 parts of low molecular weight wax (Viscol 660p, 
from Sanyo Chemicals, Japan), and 3 parts of negative charge control agent 
(Protoner 7, from ICI, U.K.) were homogenized. Then the homogenized 
mixture was subject to a series of processing steps including compounding, 
coarsely grinding, finely grinding, and classification, to obtain 5-30 
.mu.m particles. The final product was treated with 0.2 wt % hydrophobic 
silicon dioxide (TS 720, from Degussa, AG, Germany) to form a non-magnetic 
one-component toner developer suitable for use in laser printing or xerox 
copying operations. 
Particle size distribution, triboelectricity, and flowability of the 
non-magnetic one-component toner developer were measured, with the results 
shown in Table 1. The toner was then used in an OKI-DATA OKI-400 laser 
printer to produce 2,000 print copies on a continuous basis. The print 
results, including print toner concentration, uniformity of the prints, 
presence of blurred edges, print resolution, resistance to hollow defects, 
and background quality, were observed and reported in Table 2. 
Example 2 
87 parts of binder resin (styrene-acrylic copolymer, Himer TB 1000F, 
manufactured by Sanyo Chemicals, Japan) 13 parts of carbon black (Raven 
5750, from Columbia Chemical Co., U.S.A.), 2 parts of low molecular weight 
wax (Viscol 660p, from Sanyo Chemicals, Japan), and 2.5 parts of negative 
charge control agent (Protoner 7, from ICI, U.K.) were homogenized. Then 
the homogenized mixture was subject to a series of processing steps 
including compounding, coarse grinding, fine grinding, and classification, 
to obtain 5-30 .mu.m particles. The final product was treated with 0.2 wt 
% hydrophobic silicon dioxide (R972, from Degussa, AG, Germany) to form a 
non-magnetic one-component toner developer suitable for use in laser 
printing or xerox copying operations. 
Particle size distribution, triboelectricity, and flowability of the 
non-magnetic one-component toner developer were measured, with the results 
shown in Table 1. The toner was then used in an OKI-DATA OKI-400 laser 
printer to produce 2,000 print copies on a continuous basis. The print 
results, including toner concentration, uniformity of the prints, presence 
of blurred edges, print resolution, resistance to hollow defects, and 
background quality, were observed and reported in Table 2. 
Example 3 
87 parts of binder resin (styrene-acrylic copolymer, Himer TB 1000F, 
manufactured by Sanyo Chemicals, Japan) 13 parts of carbon black (Raven 
5750, from Columbia Chemical Co., U.S.A.), 2 parts of low molecular weight 
wax (Viscol 660p, from Sanyo Chemicals, Japan), and 3.5 parts of negative 
charge control agent (Protoner 7, from ICI, U.K.) were homogenized. Then 
the homogenized mixture was subject to a series of processing steps 
including compounding, coarse grinding, fine grinding, and classification, 
to obtain 5-30 .mu.m particles. The final product was treated with 0.4 wt 
% hydrophobic silicon dioxide (R812, from Degussa, AG, Germany) to form a 
non-magnetic one-component toner developer suitable for use in laser 
printing or xerox copying operations. 
Particle size distribution, triboelectricity, and flowability of the 
non-magnetic one-component toner developer were measured, with the results 
shown in Table 1. The toner was then used in an OKI-DATA OKI-400 laser 
printer to produce 2,000 print copies on a continuous basis. The print 
results, including toner concentration, uniformity of the prints, presence 
of blurred edges, print resolution, resistance to hollow defects, and 
background quality, were observed and reported in Table 2. 
Comparative Example 1 
87 parts of binder resin (styrene-acrylic ZSR-1005, manufactured by 
Polytribo, U.S.A.) 13 parts of carbon black (Raven 5750, from Columbia 
Chemical Co., U.S.A.), 2 parts of low molecular weight wax (Viscol 660p, 
from Sanyo Chemicals, Japan), and 3 parts of negative charge control agent 
(Protoner 7, from ICI, U.K.) were homogenized. Then the homogenized 
mixture was subject to a series of processing steps including compounding, 
coarse grinding, fine grinding, and classification, to obtain 5-30 .mu.m 
particles. The final product was treated with 0.2 wt % hydrophobic silicon 
dioxide (TS720, from Degussa, AG, Germany) to form a non-magnetic 
one-component toner developer suitable for use in laser printing or xerox 
copying operations. 
Comparative Example 2 
87 parts of binder resin (styrene-acrylic copolymer, Himer TB 1000F, 
manufactured by Sanyo Chemicals, Japan) 13 parts of carbon black (Raven 
5750, from Columbia Chemical Co., U.S.A.), 2 parts of low molecular weight 
wax (Viscol 660p, from Sanyo Chemicals, Japan), and 2.5 parts of negative 
charge control agent (Protoner 7, from ICI, U.K.) were homogenized. Then 
the homogenized mixture was subject to a series of processing steps 
including compounding, coarse grinding, fine grinding, and classification, 
to obtain 5-30 .mu.m particles. The final product was treated with 0.2 wt 
% hydrophobic silicon dioxide (R972, from Degussa, AG, Germany) to form a 
non-magnetic one-component toner developer suitable for use in laser 
printing or xerox copying operations. 
Comparative Example 3 
87 parts of binder resin (styrene-acrylic ZSR-1005, manufactured by 
Polytribo, U.S.A.) 13 parts of carbon black (Raven 5750, from Columbia 
Chemical Co., U.S.A.), 2 parts of low molecular weight wax (Viscol 660p, 
from Sanyo Chemicals, Japan), and 1 part of negative charge control agent 
(Kayacharge N-3, from Nippon Pharmachemicals, Japan) were homogenized. 
Then the homogenized mixture was subject to a series of processing steps 
including compounding, coarse grinding, fine grinding, and classification, 
to obtain 5-30 .mu.m particles. The final product was treated with 0.2 wt 
% hydrophobic silicon dioxide (TS720, from Degussa, AG, Germany) to form a 
non-magnetic one-component toner developer suitable for use in laser 
printing or xerox copying operations. 
Comparative Example 4 
87 parts of binder resin (styrene-acrylic ZSR-1005, manufactured by 
Polytribo, U.S.A.) 13 parts of carbon black (Raven 5750, from Columbia 
Chemical Co., U.S.A.), 2 parts of low molecular weight wax (Viscol 660p, 
from Sanyo Chemicals, Japan), and 1 part of negative charge control agent 
(Kayacharge T-3, from Nippon Pharmachemicals, Japan) were homogenized. 
Then the homogenized mixture was subject to a series of processing steps 
including compounding, coarse grinding, fine grinding, and classification, 
to obtain 5-30 .mu.m particles. The final product was treated with 0.2 wt 
% hydrophobic silicon dioxide (TS720, from Degussa, AG, Germany) to form a 
non-magnetic one-component toner developer suitable for use in laser 
printing or xerox copying operations. 
Comparative Example 5 
87 parts of binder resin (styrene-acrylic ZSR-1005, manufactured by 
Polytribo, U.S.A.) 13 parts of carbon black (Raven 5750, from Columbia 
Chemical Co., U.S.A.), 2 parts of low molecular weight wax (Viscol 660p, 
from Sanyo Chemicals, Japan), and 3 parts of negative charge control agent 
(Kayacharge T-3, from Nippon Pharmachemicals, Japan) were homogenized. 
Then the homogenized mixture was subject to a series of processing steps 
including compounding, coarse grinding, fine grinding, and classification, 
to obtain 5-30 .mu.m particles. The final product was treated with 0.2 wt 
% hydrophobic silicon dioxide (TS720, from Degussa, AG, Germany) to form a 
non-magnetic one-component toner developer suitable for use in laser 
printing or xerox copying operations. 
Comparative Example 6 
87 parts of binder resin (styrene-acrylic ZSR-1005, manufactured by 
Polytribo, U.S.A.) 13 parts of carbon black (Raven 5750, from Columbia 
Chemical Co., U.S.A.), 2 parts of low molecular weight wax (Viscol 660p, 
from Sanyo Chemicals, Japan), and 3 parts of negative charge control agent 
(Protoner 7, from ICI, U.K.) were homogenized. Then the homogenized 
mixture was subject to a series of processing steps including compounding, 
coarse grinding, fine grinding, and classification, to obtain 5-30 .mu.m 
particles. The final product was treated with 0.05 wt % hydrophobic 
silicon dioxide (TS720, from Degussa, AG, Germany) to form a non-magnetic 
one-component toner developer suitable for use in laser printing or xerox 
copying operations. 
Comparative Example 7 
87 parts of binder resin (styrene-acrylic ZSR-1005, manufactured by 
Polytribo, U.S.A.), 13 parts of carbon black (Raven 5750, from Columbia 
Chemical Co., U.S.A.), 2 parts of low molecular weight wax (Viscol 660p, 
from Sanyo Chemicals, Japan), and 2.5 parts of negative charge control 
agent (Protoner 7, from ICI, U.K.) were homogenized. Then the homogenized 
mixture was subject to a series of processing steps including compounding, 
coarse grinding, fine grinding, and classification, to obtain 5-30 .mu.m 
particles. The final product was treated with 0.05 wt % hydrophobic 
silicon dioxide (R972, from Degussa, AG, Germany) to form a non-magnetic 
one-component toner developer suitable for use in laser printing or xerox 
copying operations. 
The particle size distribution, triboelectricity, and flowability of the 
non-magnetic one-component toner developers prepared in Comparative 
Examples 1 through 7 were measured, with the results shown in Table 1. 
These toners were then used in an OKI-DATA OKI-400 laser printer to 
produce 2,000 print copies on a continuous basis. The print results, 
including toner concentration, uniformity of the prints, presence of 
blurred edges, print resolution, resistance to hollow defects, and 
background quality, were observed and reported in Table 2. 
Table 3 is a test of the criterion disclosed in the '133 patent, using the 
particle size distributions obtained from the toner developers prepared in 
Examples 1 through 3, and Comparative Examples 1 through 7. It is apparent 
that the criterion disclosed in the '133 patent fails to include the toner 
developers prepared in the present invention. 
The foregoing description of the preferred embodiments of this invention 
has been presented for purposes of illustration and description. Obvious 
modifications or variations are possible in light of the above teaching. 
The embodiments were chosen and described to provide the best illustration 
of the principles of this invention and its practical application to 
thereby enable those skilled in the art to utilize the invention in 
various embodiments and with various modifications as are suited to the 
particular use contemplated. All such modifications and variations are 
within the scope of the present invention as determined by the appended 
claims when interpreted in accordance with the breadth to which they are 
fairly, legally, and equitably entitled. 
TABLE 1 
__________________________________________________________________________ 
Tribo- 
Flowability 
Particle Size (.mu.) and Distribution 
electricity 
bulk specific 
compression 
Toner Developer 
d.sub.1 
d.sub.50 
d.sub.90 
d.sub.1/ d.sub.50 
d.sub.50 /d.sub.90 
(.mu.C/g) 
gravity 
ratio 
__________________________________________________________________________ 
Example 1 
4.4 
11.6 
20.1 
0.38 
0.58 
-22 0.42 0.18 
Example 2 
4.4 
9.0 
14.5 
0.49 
0.62 
-20 0.41 0.19 
Example 3 
4.5 
10.4 
17.7 
0.43 
0.59 
-23 0.43 0.17 
Comp. Example 1 
2.6 
10.4 
19.9 
0.25 
0.52 
-18 0.34 0.23 
Comp. Example 2 
1.9 
9.2 
18.4 
0.21 
0.50 
-16 0.32 0.24 
Comp. Example 3 
4.6 
11.0 
18.2 
0.42 
0.60 
-10 0.42 0.18 
Comp. Example 4 
3.8 
10.9 
18.4 
0.35 
0.59 
-8 0.41 0.19 
Comp. Example 5 
4.6 
10.2 
17.3 
0.45 
0.59 
-13 0.41 0.19 
Comp. Example 6 
4.4 
11.6 
20.1 
0.38 
0.58 
-21 0.36 0.23 
Comp. Example 7 
4.4 
9.0 
14.5 
0.49 
0.62 
-19 0.34 0.24 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
Absence of Absence of 
Print Toner Concentration 
Uniformity of 
Blurred Edges 
Anti-Hollow 
Ghost 
Toner Developer 
Solid Area 
Optical Density 
Prints and Resolution 
Defects 
Background 
__________________________________________________________________________ 
Example 1 
good 1.48 good good good good 
Example 2 
good 1.46 good good good good 
Example 3 
good 1.60 good good good good 
Comp. Example 1 
fair 1.00 fair poor poor fair 
Comp. Example 2 
fair 0.89 fair poor poor fair 
Comp. Example 3 
fair 1.06 poor poor fair fair 
Comp. Example 4 
poor 0.45 poor poor poor poor 
Comp. Example 5 
good 1.32 good poor good good 
Comp. Example 6 
fair 1.29 fair fair fair fair 
Comp. Example 7 
fair 1.31 fair fair fair fair 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
Particle Size (.mu.m) and Distribution 
d.sub.75 /d.sub.25 - d.sub.50 /40 = ? 
Toner Developer 
d.sub.25 
d.sub.50 
d.sub.75 
Result 
.ltoreq.1.2 ? 
Print Quality 
__________________________________________________________________________ 
Example 1 
8.7 11.6 14.1 1.33 no good 
Example 2 
6.9 9.0 10.6 1.31 no good 
Example 3 
8.0 10.4 12.6 1.32 no good 
Comp. Example 1 
7.2 10.4 13.3 1.59 no poor 
Comp. Example 2 
6.3 9.2 12.0 1.67 no poor 
Comp. Example 3 
8.2 11.0 13.2 1.32 no poor 
Comp. Example 4 
8.1 10.9 13.1 1.35 no poor 
Comp. Example 5 
7.8 10.2 12.3 1.32 no poor 
Comp. Example 6 
8.7 11.6 14.1 1.33 no poor 
Comp. Example 7 
6.9 9.0 10.6 1.32 no poor 
__________________________________________________________________________