Toner for developing electrostatic image

A toner for developing an electrostatic image is constituted by a binder resin and a colorant. The toner is characterized by a percentage change .sub.G' of at most 50% as calculated by the following formula (1): EQU .gamma..sub.G' =(1-G'.sub.50% /G'.sub.1%).times.100 (1), wherein .gamma..sub.G' denotes a percentage change of storage modulus, G'.sub.50% denotes a storage modulus at 50% strain at 150.degree. C., and G'.sub.1% denotes a storage modulus at 1% strain at 150.degree. C.; a percentage change .gamma..sub.G" of at most 50% as calculated by the following formula (2): EQU .gamma..sub.G" =(1-G".sub.50% /G".sub.1%).times.100 (2), wherein .gamma..sub.G" denotes a percentage change of loss modulus, G".sub.50% denotes a loss modulus at 50% strain, and G".sub.1% denotes a loss modulus at 1% strain; and a storage modulus G' of 3.times.10.sup.3 -7.times.10.sup.4 dyn/cm.sup.2 in a range of 1-50% strain at 150.degree. C. The toner is characterized by applicability to a wide variety of image forming apparatus, especially those having remarkably different fixing speeds.

FIELD OF THE INVENTION AND RELATED ART 
The present invention relates to a toner for developing electrostatic 
images used in image forming methods, such as electrophotography, 
electrostatic recording or electrostatic printing, particularly a toner 
suitable for hot roller fixation. 
Hitherto, a large number of electrophotographic processes have been known, 
inclusive of those disclosed in U.S. Pat. Nos. 2,297,691; 3,666,363; and 
4,071,361. In these processes, in general, an electrostatic latent image 
is formed on a photosensitive member comprising a photoconductive material 
by various means, then the latent image is developed with a toner, and the 
resultant toner image is, after being transferred onto a transfer material 
such as paper etc., as desired, fixed by heating, pressing, or heating and 
pressing, or with solvent vapor to obtain a copy or print carrying a fixed 
toner image. 
As for the step of fixing the toner image onto a sheet material such as 
paper which is the final step in the above process, various methods and 
apparatus have been developed, of which the most popular one is a heating 
and pressing fixation system using hot rollers. 
In the heating and pressing system, a sheet carrying a toner image to be 
fixed (hereinafter called "fixation sheet") is passed through hot rollers, 
while a surface of a hot roller having a releasability with the toner is 
caused to contact the toner image surface of the fixation sheet under 
pressure, to fix the toner image. In this method, as the hot roller 
surface and the toner image on the fixation sheet contact each other under 
a pressure, a very good heat efficiency is attained for melt-fixing the 
toner image onto the fixation sheet to afford quick fixation. 
Currently, different toners are used for different models of copying 
machines and printers. This is primarily because the different models 
adopt different fixing speeds and fixing temperatures. More specifically, 
in the fixing step, a hot roller surface and a toner image contact each 
other in a melted state and under a pressure, so that a part of the toner 
is transferred and attached to the fixing roller surface and then 
re-transferred to a subsequent fixation sheet to soil the fixation sheet. 
This is called an offset phenomenon and is especially affected by the 
fixing speed and temperature. Generally, the fixing roller surface 
temperature is set to be low in case of a slow fixing speed and set to be 
high in case of a fast fixing speed. This is because a constant heat 
quantity is supplied to the toner image for fixation thereof regardless of 
a difference in fixing speed. 
However, the toner on a fixation sheet is deposited in several layers, so 
that there is liable to occur a large temperature difference between a 
toner layer contacting the heating roller and a lowermost toner layer 
particularly in a hot-fixation system using a high heating roller 
temperature. As a result, a topmost toner layer is liable to cause an 
offset phenomenon in case of a high heating roller temperature, while a 
low-temperature offset is liable to occur because of insufficient melting 
of the lowermost toner layer in case of a low heating roller temperature. 
In order to solve the above problem, it has been found useful to increase 
the fixing pressure in case of a fast fixing speed in order to promote the 
anchoring of the toner onto the fixation sheet. According to this method, 
the heating roller temperature can be somewhat lowered and it is possible 
to obviate a high-temperature offset phenomenon of an uppermost toner 
layer. However, as a very high shearing force is applied to the toner 
layer, there are liable to arise several difficulties, such as a winding 
offset wherein the fixation sheet winds about the fixing roller, the 
appearance of a trace in the fixed image of a separating member for 
separating the fixation sheet from the fixing roller, and inferior copied 
images, such as resolution failure of line images and toner scattering, 
due to a high pressure. 
Accordingly, in a high-speed fixing system, a toner having a lower melt 
viscosity is generally used than in the case of low speed fixation, so as 
to lower the heating roller temperature and fixing pressure, thereby 
effecting the fixation while obviating the high-temperature offset and 
winding offset. However, when using such a toner having a low melt 
viscosity in low speed fixation, an offset phenomenon is liable to be 
caused because of the low viscosity. 
Accordingly, there has been desired a toner which shows a wide fixable 
temperature range and an excellent anti-offset characteristic and is 
applicable in the range from a low speed apparatus to a high speed 
apparatus. 
On the other hand, in recent years, there have been also desired 
high-quality copy or print images in accordance with the use of 
digitalized copying machines and fine toner particles. 
More specifically, it has been desired to obtain a photographic image 
accompanied with characters, so that the character images are clear while 
the photographic image is excellent in density gradation faithful to the 
original. Generally, in a copy of a photographic image accompanied by 
characters, if the line density is increased so as to provide clear 
character images, not only the density gradation characteristic of the 
photograph image is impaired, but also the halftone part thereof is 
roughened. 
Further, resolution failure (collapsing) of line images and scattering are 
liable to be caused at the time of fixation as described above, so that 
the image qualities of the resultant copy images are rather liable to be 
deteriorated. 
Further, in case where the line image density is increased, because of an 
increased toner coverage, a thick toner image is pushed against a 
photosensitive member to be attached to the photosensitive member in the 
toner transfer step, so that a so-called transfer failure (or a hollow 
image), i.e., a partial lack toner image (line images in this case), in 
the transferred image, is liable to be caused, thereby providing poor 
quality of copy images. On the other hand, in the case where the gradation 
characteristic of a photographic image is intended to be improved, the 
density of characters or line images are liable to be lowered, thus 
providing unclear images. 
The use of a smaller particle size toner can increase the resolution and 
clearness of an image but is also liable to be accompanied by various 
difficulties. 
First, a smaller particle size toner is liable to impair the fixability of 
a halftone image. This is particularly noticeable in high-speed fixation. 
This is because the toner coverage in a halftone part is small and a 
portion of toner transferred to a concavity of a fixation sheet receives 
only a small quantity of heat and the pressure applied thereto is also 
suppressed because of the convexity of the fixation sheet. A portion of 
toner transferred onto the convexity of the fixation sheet in a halftone 
part receives a much larger shearing force per toner particle because of a 
small toner layer thickness compared with that in a solid image part, thus 
being liable to cause offset or result in copy images of a lower image 
quality. 
Fog is another problem. If the toner particle size is reduced, the surface 
area of a unit weight of toner is increased, so that the charge 
distribution thereof is liable to be broadened to cause fog. As the toner 
surface area is increased per unit weight thereof, the toner chargeability 
is liable to be affected by a change in environmental conditions. 
If the toner particle size is reduced, the dispersion state of a polar 
material and a colorant is liable to affect the toner chargeability. 
When such a small particle size toner is applied to a high-speed copying 
machine, the toner is liable to be excessively charged to cause fog and a 
density decrease, particularly in a low-humidity environment. 
Further, in connection with a trend of providing a copying machine with a 
multiplicity of functions, such as a superposed multi-color copying by 
erasing a part of an image as by exposure and inserting another image into 
the erased part, or frame erasure by erasing a frame part on a copying 
sheet, fog of a small particle size is liable to remain in such a part 
which is erased into white. 
When an image is erased by providing a potential of a polarity opposite to 
that of a latent image potential with respect to a development reference 
potential as by irradiation with intense light from LED, a fuse lamp, 
etc., the erased part is liable to cause fog. 
Japanese Laid-Open Patent Application (JP-A) 3-219262 (Corresponding to 
U.S. Pat. No. 5,180,649) JP-A 3-64766 and JP-A 3-271757 have disclosed a 
toner having a storage modulus and a loss modulus in certain ranges, 
respectively. Such a toner may have excellent fixability and anti-offset 
characteristic under a certain fixing condition but it is not easy to 
satisfy fixability and anti-offset characteristic for various models of 
fixing devices having remarkably different fixing speeds, fixing pressures 
and shearing forces as described above and also to provide satisfactory 
image qualities. 
JP-A 3-41471 and JP-A 3-188468 have proposed methods of using a binder 
resin obtained by severing the gel content of a polyester resin or a 
styrene-acrylic copolymer. According to these methods, however, the 
resultant toner is caused to have large percentage changes in storage 
modulus (G') and loss modulus (G") as defined hereinafter because of a 
short distance between crosslinking points in the polymer chain. 
Accordingly, the toner is liable to be inferior in fixability and image 
quality particularly at a halftone part. 
SUMMARY OF THE INVENTION 
A generic object of the present invention is to provide a toner for 
developing electrostatic images having solved the above-mentioned 
problems. 
A more specific object of the present invention is to provide a toner for 
developing electrostatic images showing an excellent anti-offset 
characteristic without impairing the fixability from a low fixing speed to 
a high fixing speed. 
Another object of the present invention is to provide a toner for 
developing electrostatic images, even in a small particle size, capable of 
showing a good fixability at a halftone part and providing copy images of 
good image quality. 
Another object of the present invention is to provide a toner for 
developing electrostatic images capable of providing high-density copy 
images free from fog from a low to a high process speed. 
Another object of the present invention is to provide a toner for 
developing electrostatic images capable of providing good images in a 
low-humidity environment and also in a high-humidity environment without 
being affected by a change in environmental conditions. 
Another object of the present invention is to provide a toner for 
developing electrostatic images capable of providing good images even by a 
high-speed image-forming apparatus. 
Another object of the present invention is to provide a toner for 
developing electrostatic images having excellent durability and capable of 
providing copy images having a high image density and free from fog even 
in a long period of continuous image formation. 
Another object of the present invention is to provide copies of a 
photographic image with characters including clear character images and 
photographic images having a density gradation characteristic faithful to 
the original. 
According to the present invention, there is provided a toner for 
developing an electrostatic image, comprising: a binder resin and a 
colorant; wherein the toner has 
a percentage change .gamma..sub.G' of at most 50% as calculated by the 
following formula (1): 
EQU .gamma..sub.G' =(1-G'.sub.50% /G'.sub.1%).times.100 (1), 
wherein 
.gamma..sub.G' denotes a percentage change of storage modulus, G'.sub.50% 
denotes a storage modulus at 50% strain at 150.degree. C., and G'.sub.1% 
denotes a storage modulus at 1% strain at 150.degree. C., 
a percentage change .gamma..sub.G" of at most 50% as calculated by the 
following formula (2): 
EQU .gamma..sub.G" =(1-G".sub.50% /G".sub.1%).times.100 (2), 
wherein 
.gamma..sub.G" denotes a percentage change of loss modulus, G".sub.50% 
denotes a loss modulus at 50% strain, and G".sub.1% denotes a loss modulus 
at 1% strain, and 
a storage modulus G' of 3.times.10.sup.3 -7.times.10.sup.4 dyn/cm.sup.2 in 
a range of 1-50% strain at 150.degree. C. 
These and other objects, features and advantages of the present invention 
will become more apparent upon a consideration of the following 
description of the preferred embodiments of the present invention taken in 
conjunction with the accompanying drawing.

DETAILED DESCRIPTION OF THE INVENTION 
According to our detailed study, excellent fixability and anti-offset 
characteristic are attained under varying fixing conditions by using a 
toner having low percentage changes of storage modulus G' and loss modulus 
G" corresponding to changes in strain. 
The storage modulus G' and loss modulus G" are physical properties related 
with the anti-offset characteristic and fixability of a toner. A smaller 
storage modulus G' is liable to result in a lower anti-offset 
characteristic, and a larger loss modulus G" is liable to result in an 
inferior fixability. 
In a high-speed fixation, a higher shearing force is exerted than in a 
low-speed fixation. Accordingly, the toner according to the present 
invention having low strain-dependent percentage changes of storage 
modulus G' and loss modulus G" can show excellent anti-offset 
characteristic without impairing the fixability for a low-speed to a high 
speed image forming apparatus. 
The toner according to the invention has a storage modulus G' in the range 
of 3.times.10.sup.3 -7.times.10.sup.4 dyn/cm.sup.2 in the range of 1-50% 
strain at 150.degree. C. If the storage modulus G' is smaller than 
3.times.10.sup.3 dyn/cm.sup.2, a high-temperature offset is liable to 
occur and, if the storage modulus G' is larger than 7.times.10.sup.4 
dyn/cm.sup.2, the fixability is liable to be lowered. Particularly, in the 
case of a heat-pressure fixing device using a high fixing pressure, if the 
storage modulus G' is below 3.times.10.sup.3 dyn/cm, the high-temperature 
offset is liable to occur because of insufficient elasticity. 
It is further preferred that the toner has a percentage change 
.gamma..sub.G' of 0.1-35%, and a percentage change .gamma..sub.G" of 
0.1-35%. 
It is also preferred that the toner has a loss modulus G" in the range of 
2.times.10.sup.3 -6.times.10.sup.4 dyn/cm.sup.2 in the range of 1-50% 
strain at 150.degree. C. If the loss-modulus G" is below 2.times.10.sup.3 
dyn/cm.sup.2, a high temperature offset is liable to be caused and, if the 
loss modulus G" is above 6.times.10.sup.4 dyn/cm.sup.2, the fixability is 
liable to be lowered. 
Particularly, in the case of using a high fixing speed and a hot roller 
having a small diameter giving a large curvature radius of the hot roller 
at the time of discharging paper after the fixation, the satisfaction of 
the above-mentioned range of the loss modulus G" is effective for offset 
prevention. 
The binder resin used in the present invention may comprise a polyester 
resin, a vinyl resin or an epoxy resin. It is particularly preferred to 
use a polyester resin or a vinyl resin in view of the chargeability and 
the fixation characteristic. 
In the case where the binder resin comprise a polyester resin, it is 
preferred that the toner has a storage modulus G' in the range of 
4.5.times.10.sup.3 -6.5.times.10.sup.4 dyn/cm.sup.2, and it is also 
preferred that the toner has a loss modulus G" in the range of 
3.times.10.sup.3 -5.5.times.10.sup.4 dyn/cm.sup.2. 
The polyester resin preferably used in the present invention may have a 
composition as described below. 
The polyester resin used in the present invention may preferably comprise 
45-55 mol. % of alcohol component and 55-45 mol. % of acid component. 
Examples of the alcohol component may include: diols, such as ethylene 
glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 
diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 
neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, 
bisphenols and derivatives represented by the following formula (A): 
##STR1## 
wherein R denotes an ethylene or propylene group, x and y are 
independently 0 or a positive integer with the proviso that the average of 
x+y is in the range of 0-10; diols represented by the following formula 
(B): 
##STR2## 
wherein R' denotes 
##STR3## 
x' and y' are independently 0 or a positive integer with the proviso that 
the average of x'+y' is in the range of 0-10. 
It is preferred that dibasic acid constitutes at least 50 mol. % of the 
total acid. Examples of the dibasic acid may include benzenedicarboxylic 
acids, such as phthalic acid, terephthalic acid and isophthalic acid, and 
their anhydrides; alkyldicarboxylic acids, such as succinic acid, adipic 
acid, sebacic acid and azelaic acid, and their anhydrides; C.sub.6 
-C.sub.18 alkyl or alkenyl-substituted succinic acids, and their 
anhydrides; and unsaturated dicarboxylic acids, such as fumaric acid, 
maleic acid, citraconic acid and itaconic acid, and their anhydrides. 
An especially preferred class of alcohol components constituting the 
polyester resin is a bisphenol derivative represented by the above formula 
(A), and preferred examples of acid components may include dicarboxylic 
acids inclusive of phthalic acid, terephthalic acid, isophthalic acid and 
their anhydrides; succinic acid, n-dodecenylsuccinic acid, and their 
anhydrides, fumaric acid, maleic acid, and maleic anhydride. 
The polyester resin used for producing the toner according to the present 
invention may preferably have a glass transition temperature (Tg) of 
40.degree.-90.degree. C., particularly 45.degree.-85.degree. C., a 
number-average molecular weight (Mn) of 1,000-50,000, more preferably 
1,500-20,000, and a weight-average molecular weight of 3.times.10.sup.3 
-1.times.10.sup.5, more preferably 4.times.10.sup.4 -9.times.10.sup.4. 
Examples of a vinyl monomer to be used for providing the vinyl resin may 
include: styrene; styrene derivatives, such as o-methylstyrene, 
m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, 
p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, 
p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, 
p-n-nonylstyrene, p-n-decylstyrene, and p-n-dodecylstyrene; ethylenically 
unsaturated monoolefins, such as ethylene, propylene, butylene, and 
isobutylene; unsaturated polyenes, such as butadiene; halogenated vinyls, 
such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl 
fluoride; vinyl esters, such as vinyl acetate, vinyl propionate, and vinyl 
benzoate methacrylates, such as methyl methacrylate, ethyl methacrylate, 
propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl 
methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl 
methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and 
diethylaminoethyl methacrylate; acrylates, such as methyl acrylate, ethyl 
acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl 
acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 
2-chloroethyl acrylate, and phenyl acrylate, vinyl ethers, such as vinyl 
methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; vinyl ketones, 
such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl 
ketone; N-vinyl compounds, such as N-vinylpyrrole, N-vinylcarbazole, 
N-vinylindole, and N-vinyl pyrrolidone; vinylnaphthalenes; acrylic acid 
derivatives or methacrylic acid derivatives, such as acrylonitrile, 
methacryronitrile, and acrylamide; esters of the below-mentioned 
.alpha.,.beta.-unsaturated acids and diesters of the below-mentioned 
dibasic acids. 
Examples of a carboxy group-containing monomer may include: unsaturated 
dibasic acids, such as maleic acid, citraconic acid, itaconic acid, 
alkenylsuccinic acid, fumaric acid, and mesaconic acid; unsaturated 
dibasic acid anhydrides, such as maleic anhydride, citraconic anhydride, 
itaconic anhydride, and alkenylsuccinic anhydride; unsaturated dibasic 
acid half esters, such as mono-methyl maleate, mono-ethyl maleate, 
mono-butyl maleate, mono-methyl citraconate, mono-ethyl citraconate, 
mono-butyl citraconate, mono-methyl itaconate, mono-methyl 
alkenylsuccinate, monomethyl fumarate, and mono-methyl mesaconate; 
unsaturated dibasic acid esters, such as dimethyl maleate and dimethyl 
fumarate; .alpha.,.beta.-unsaturated acids, such as acrylic acid 
methacrylic acid, crotonic acid and cinnamic acid; 
.alpha.,.beta.-unsaturated acid anhydrides, such as crotonic anhydride, 
and cinnamic anhydride; anhydrides between such an 
.alpha.,.beta.-unsaturated acid and a lower aliphatic acid; alkenylmalonic 
acid alkenylglutaric acid alkenyladipic acid, and anhydrides and 
monoesters of these acids. 
The binder resin comprising a vinyl resin may preferably have a glass 
transition point of 45.degree.-80.degree. C., preferably 
55.degree.-70.degree. C., a number-average molecular weight (Mn) of 
2.5.times.10.sup.3 -5.times.10.sup.4, and a weight-average molecular 
weight (Mw) of 1.times.10.sup.4 -1.0.times.10.sup.6. 
In the present invention, it is also possible to add another type of resin, 
such as polyurethane, epoxy resin polyvinyl butyral, modified resin, 
terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, 
or aromatic petroleum resin, as desired, to the binder resin. 
In the case of using two or more species of resins in mixture to constitute 
a binder resin, it is preferred to preferred to mix resins having 
different molecular weights in appropriate proportions. 
In order to provide the toner having percentage changes of at most 50% 
between strains of 1% and 50% of storage modulus G' and loss modulus G", 
the properties of a binder resin constituting the toner constitute an 
important factor. For this purpose, it is preferred to use a resin having 
a relatively low molecular weight, i.e., a number-average molecular weight 
of 1,000-50,000, preferably 2,000-20,000, and a gel resin having a long 
distance between crosslinking points in its polymer chain to provide a 
binder resin. When the resins having the above-mentioned properties as the 
binder resin are used to produce a toner, the gel resin may be subjected 
to severance, thereby providing a polymer component having a long branch 
chain to suitably providing small percentage changes. 
In case where the polyester resin is used as a principal binder resin in a 
toner containing such a component formed by severance of the gel resin, 
the binder resin contained in the toner may preferably have a 
number-average molecular weight (Mn) of 1,000-50,000, more preferably 
1,500-20,000, and a weight-average molecular weight (Mw) of 
3.times.10.sup.3 -2.times.10.sup.6, more preferably 4.times.10.sup.4 
-1.5.times.10.sup.6. Also in the case where the vinyl resin is used as a 
principal binder resin in a toner containing such a component formed by 
severance of the gel resin, the binder resin contained in the toner may 
preferably have a number-average molecular weight (Mn) of 2,500-50,000 and 
a weight-average molecular weight (Mw) of 1.times.10.sup.5 
-1.times.10.sup.6. 
This is presumably for the following reason. 
In a case where two types of resins having an identical molecular weight 
but having different distances between crosslinking points in polymer 
chains are respectively subjected to severance to form polymer components, 
a resin having a longer distance between crosslinking points provides a 
polymer component having a longer branch length. Accordingly, the branch 
length is considered to have a large influence in interaction with a 
low-molecular weight resin when the polymer component is mixed with the 
low-molecular weight resin to provide a toner. Because of the presence of 
such a resin having a long branch, the entanglement thereof with a 
low-molecular weight resin is stronger than a resin having a short branch. 
As a result, a toner comprising such a resin mixture is caused to lower 
the percentage changes of storage modulus G' and loss modulus G" between 
those at 1% strain and 50% strain at 150.degree. C. to be below 50%. When 
a toner is constituted by a mixture of a linear high-molecular weight 
resin or a resin having a structure close thereto and a linear 
low-molecular weight resin through the use of a high-molecular weight 
polymer having a short distance between crosslinking points, it is 
difficult to realize the percentage changes of at most 50%. 
A polyester resin comprising a gel component having a long distance between 
crosslinking points may for example be produced in the following manner: 
(1) A linear polyester or a polyester having a small gel content is first 
formed, and then an alcohol or acid having 3 or more functional groups is 
added to cause polycondensation. 
(2) A polyester having a small gel content is formed by using an alcohol or 
acid having three or more functional groups through utilization of a 
difference in polycondensation activity, and a linear or nonlinear 
polyester and/or an alcohol or acid having thee or more functional groups 
is added thereto for further polycondensation. 
A vinyl copolymer resin comprising a gel component having a long distance 
may for example be produced by using a crosslinking agent having a long 
distance between crosslinking functional groups, examples of which may 
include diacrylate or dimethacrylate compounds having an intermediate 
alkyl chain; diacrylate or dimethacrylate compounds having an intermediate 
alkyl chain including an ether bond; and diacrylate or dimethacrylate 
compounds having an intermediate chain including an aromatic group and an 
ether bond. Among these crosslinking agents, it is preferred to use a 
crosslinking agent having a molecular weight of at least 300 for 
accomplishing the object of the present invention. 
Preferred examples thereof may include: tetraethylene glycol 
dimethacrylate, polyethylene glycol diacrylate, 
polyoxyethylene-(2)-3,3-bis(4-hydroxyphenyl)propane diacrylate, and 
polyoxyethylene (4)-2,2-bis(4-hydroxyphenyl)propane diacrylate. 
It is also possible to use a crosslinking agent having a molecular weight 
of below 300 in combination with one having a molecular weight of at least 
300 within an extent not adverse to the object of the present invention. 
Alternatively, it is also possible to mix a vinyl copolymer having a 
carboxyl group and/or a hydroxyl group with a polyester resin for further 
condensation. 
A resin composition comprising a mixture of a resin having a relatively low 
number-average molecular weight of 1,000-50,000 and a gel component resin 
having a long distance between crosslinking points may for example be 
prepared by (1) separately preparing such low-molecular weight resin and 
gel component resin and mixing them; and (2) preparing a polyester resin 
composition by adding a diamine or diisocyanate component, etc., having an 
effect of broadening the molecular weight distribution to (a) a system of 
synthesizing a linear polyester or (b) a system of synthesizing a 
gel-resin having a long distance between crosslinking points. 
The gel component may be severed to provide a high-molecular weight 
component having a long branch during melt-kneading as by a twin-screw 
kneader, an extruder or a pressurized kneader. 
In the toner for developing electrostatic images according to the present 
invention, it is preferred to add a charge control agent, as desired, in 
order to further stabilize the chargeability thereof. The charge control 
agent may be used in 0.1-10 wt. parts, preferably 0.1-5 wt. parts, per 100 
wt. parts of the binder resin. 
The charge control agent may for example be as follows. 
Examples of negative charge control agents may include organometal 
complexes and chelate compounds, inclusive of mono-azo metal complexes, 
aromatic hydroxycarboxylic acid metal complexes and aromatic dicarboxylic 
acid metal complexes. Other examples may include: aromatic 
hydroxycarboxylic acids, aromatic mono- and poly-carboxylic acids, metal 
salts, anhydrides and esters of these acids, and phenol derivatives of 
bisphenols. 
Examples of positive charge control agent for providing a positively 
chargeable toner may include: nigrosine, triphenylmethane compounds, 
rhodamine dyes, and polyvinylpyridine. A color toner may preferably be 
prepared by using a binder resin obtained by using an amino 
group-containing carboxylic acid ester, such as dimethylaminomethyl 
methacrylate, capable of providing a positive chargeability in an amount 
of 0.1-40 mol. %, preferably 1-30 mol. % of the monomer, or by using a 
colorless or pale-colored positive charge control agent not adversely 
affecting the toner hue. Examples of the positive charge control agent may 
include quaternary ammonium salts represented by the following formulae 
(A) and (B): 
Formula (A) 
##STR4## 
wherein Ra, Rb, Rc and Rd independently denote a C.sub.1 -C.sub.10 alkyl 
group or a substituted phenyl group denoted by 
##STR5## 
R' denoting a C.sub.1 -C.sub.5 alkyl group and Re denotes --H, --OH, 
--COOH or a C.sub.1 -C.sub.5 alkyl group. 
Formula (B) 
##STR6## 
wherein Rf denotes C.sub.1-5 alkyl group, and Rg denotes --H, --OH, --COOH 
or a C.sub.1 -C.sub.5 alkyl group. 
Among the quaternary ammonium salts represented by the above formulae (A) 
and (B), it is particularly preferred to use the compounds of the 
following formulae (A)-1, (A)-2 and (B)-1 as a positive charge control 
agent in order to provide a good chargeability little affected by an 
environmental change. 
##STR7## 
In the case of constituting a positively chargeable toner by using a 
polymer or copolymer of an amino group-containing ester, such as dimethyl 
aminomethyl methacrylate, showing a positive chargeability as a binder 
resin component, it is also possible to further add a positive charge 
control agent or a negative charge control agent, as desired. 
In case of not using such a polymer showing a positive chargeability, it is 
preferred to add 0.1-15 wt. parts, more preferably 0.5-10 wt. parts, of a 
positive charge control agent per 100 wt. parts of the binder resin. In 
the case of using such a polymer or copolymer of an amino group-containing 
ester, it is preferred to add at most 10 wt. parts, preferably at most 8 
wt. parts, of a positive charge control agent and/or a negative charge 
control agent, as desired, for the purpose of providing a good 
chargeability less affected by an environment condition. 
When the toner according to the present invention is constituted as a 
magnetic toner, the magnetic toner may contain a magnetic material, 
examples of which may include: iron oxides, such as magnetite, hematite, 
and ferrite; iron oxides containing another metal oxide; metals, such as 
Fe, Co and Ni, and alloys of these metals with other metals, such as Al, 
Co, Cu, Pb, Mg, Ni, Sn, Zn, Sb, Be, Bi, Cd, Ca, Mn, Se, Ti, W and V; and 
mixtures of the above. 
Specific examples of the magnetic material may include: triiron tetroxide 
(Fe.sub.3 O.sub.4), diiron trioxide (.gamma.-Fe.sub.2 O.sub.3), zinc iron 
oxide (ZnFe.sub.2 O.sub.4), yttrium iron oxide (Y.sub.3 Fe.sub.5 
O.sub.12), cadmium iron oxide (CdFe.sub.2 O.sub.4), gadolinium iron oxide 
(Gd.sub.3 Fe.sub.5 O.sub.12), copper iron oxide (CuFe.sub.2 O.sub.4), lead 
iron oxide (PbFe.sub.12 O.sub.19), nickel iron oxide (NiFe.sub.2 O.sub.4), 
neodymium iron oxide (NdFe.sub.2 O.sub.3), barium iron oxide (BaFe.sub.12 
O.sub.19), magnesium iron oxide (MgFe.sub.2 O.sub.4), manganese iron oxide 
(MnFe.sub.2 O.sub.4), lanthanum iron oxide (LaFeO.sub.3), powdery iron 
(Fe), powdery cobalt (Co), and powdery nickel (Ni). The above magnetic 
materials may be used singly or in mixture of two or more species. 
Particularly suitable magnetic material for the present invention is fine 
powder of triiron tetroxide or .gamma.-diiron trioxide. 
The magnetic material may have an average particle size (Dav.) of 0.1-2 
.mu.m, preferably 0.1-0.3 .mu.m. The magnetic material may preferably show 
magnetic properties when measured by application of 10 kilo-Oersted, 
inclusive of: a coercive force (Hc) of 20-150 Oersted, a saturation 
magnetization (.sigma.s) of 50-200 emu/g, particularly 50-100 emu/g, and a 
residual magnetization (.pi.r) of 2-20 emu/g. 
The magnetic material may be contained in the toner in a proportion of 
65-200 wt. parts, preferably 70-150 wt. parts, per 100 wt. parts of the 
binder resin. 
The toner according to the present invention may optionally contain a 
non-magnetic colorant, examples of which may include: carbon black, 
titanium white, and other pigments and/or dyes. For example, the toner 
according to the present invention, when used as a color toner, may 
contain a dye, examples of which may include: C.I. Direct Red 1, C.I. 
Direct Red 4, C.I. Acid Red 1, C.I. Basic Red 1, C.I. Mordant Red 30, C.I. 
Direct Blue 1, C.I. Direct Blue 2, C.I. Acid Blue 9, C.I. Acid Blue 15, 
C.I. Basic Blue 3, C.I. Basic Blue 5, C.I. Mordant Blue 7, C.I. Direct 
Green 6, C.I. Basic Green 4, and C.I. Basic Green 6. Examples of the 
pigment may include: Chrome Yellow, Cadmium Yellow, Mineral Fast Yellow, 
Navel Yellow, Naphthol Yellow S, Hansa Yellow G, Permanent Yellow NCG, 
Tartrazine Lake, Orange Chrome Yellow, Molybdenum Orange, Permanent Orange 
GTR, Pyrazolone Orange, Benzidine Orange G, Cadmium Red, Permanent Red 4R, 
Watching Red Ca salt, eosine lake; Brilliant Carmine 3B; Manganese Violet, 
Fast Violet B, Methyl Violet Lake, Ultramarine, Cobalt BLue, Alkali Blue 
Lake, Victoria Blue Lake, Phthalocyanine Blue, Fast Sky Blue, Indanthrene 
Blue BC, Chrome Green, chromium oxide, Pigment Green B, Malachite Green 
Lake, and Final Yellow Green G. 
In case of constituting the toner according to the present invention as a 
toner for a two-component type full color developer, various colorants 
inclusive of the pigment and dye may be added. 
Examples of a magenta pigment may include: C.I. Pigment Red 1, 2, 3, 4, 5, 
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 
32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 
64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207, 
209; C.I. Pigment Violet 19; and C.I. Violet 1, 2, 10, 13, 15, 23, 29, 35. 
The pigments may be used alone but can also be used in combination with a 
dye so as to increase the clarity for providing a color toner for full 
color image formation. Examples of the magenta dyes may include: 
oil-soluble dyes, such as C.I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 
49, 81, 82, 83, 84, 100, 109, 121; C.I. Disperse Red 9; C.I. Solvent 
Violet 8, 13, 14, 21, 27; C.I. Disperse Violet 1; and basic dyes, such as 
C.I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 
34, 35, 36, 37, 38, 39, 40; C.I. Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 
26, 27, 28. 
Other pigments include cyan pigments, such as C.I. Pigment Blue 2, 3, 15, 
16, 17; C.I. Vat Blue 6, C.I. Acid Blue 45, and copper phthalocyanine 
pigments represented by the following formula and having a phthalocyanine 
skeleton to which 1-5 phthalimidomethyl groups are added: 
##STR8## 
Examples of yellow pigment may include: C.I. Pigment Yellow 1, 2, 3, 4, 5, 
6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 83; C.I. Vat Yellow 1, 
13, 20. 
Such a non-magnetic colorant may be added in an amount of 0.1-60 wt. parts, 
preferably 0.5-50 wt. parts, per 100 wt. parts of the binder resin. 
In the present invention, it is also possible to incorporate one or two or 
more species of release agent, as desired within, toner particles. 
Examples of such a release agent which is solid at room temperature may 
include: aliphatic hydrocarbon waxes, such as low-molecular weight 
polyethylene, low-molecular weight polypropylene, microcrystalline wax, 
and paraffin wax, oxidation products of aliphatic hydrocarbon waxes, such 
as oxidized polyethylene wax, and block copolymers of these; waxes 
containing aliphatic esters as principal constituents, such as carnauba 
wax, sasol wax, montanic acid ester wax, and partially or totally 
deacidified aliphatic esters, such as deacidified carnauba wax. Further 
examples of the release agent may include: saturated linear aliphatic 
acids, such as palmitic acid, stearic acid, and montanic acid; unsaturated 
aliphatic acids, such as brassidic acid, eleostearic acid and parinaric 
acid; saturated alcohols, such as stearyl alcohol, behenyl alcohol, ceryl 
alcohol, and melissyl alcohol; polyhydric alcohols, such as sorbitol; 
aliphatic acid amides, such as linoleylamide, oleylamide, and laurylamide; 
saturated aliphatic acid bisamides, methylene-bisstearylamide, 
ethylene-biscaprylamide, and ethylene-biscaprylamide; unsaturated 
aliphatic acid amides, such as ethylene-bisolerylamide, 
hexamethylene-bisoleylamide, N,N'-dioleyladipoylamide, and 
N,N'-dioleylsebacoylamide, aromatic bisamides, such as 
m-xylene-bisstearoylamide, and N,N'-distearylisophthalylamide; aliphatic 
acid metal salts (generally called metallic soap), such as calcium 
stearate, calcium laurate, zinc stearate, and magnesium stearate; grafted 
waxes obtained by grafting aliphatic hydrocarbon waxes with vinyl 
monomers, such as styrene and acrylic acid partially esterified products 
between aliphatic acids and polyhydric alcohols, such as behenic acid 
monoglyceride; and methyl ester compounds having hydroxyl group as 
obtained by hydrogenating vegetable fat and oil. 
A particularly preferred class of release agent (wax) in the present 
invention may include aliphatic alcohol waxes and aliphatic hydrocarbon 
waxes. The aliphatic alcohol waxes may be represented by the following 
formula (C): 
EQU Formula (C): CH.sub.3 (CH.sub.2).sub.x CH.sub.2 OH(x=20-250). 
Specific examples of the wax preferably used in the present invention may 
include e.g., a low-molecular weight alkylene polymer obtained through 
polymerization of an alkylene by radical polymerization under a high 
pressure or in the presence of a Ziegler catalyst under a low pressure; an 
alkylene polymer obtained by thermal decomposition of an alkylene polymer 
of a high molecular weight; a hydrocarbon wax obtained by subjecting a 
mixture gas containing carbon monoxide and hydrogen to the Arge process to 
form a hydrocarbon mixture and distilling the hydrocarbon mixture to 
recover a residue; and hydrogenation products of the above. Fractionation 
of wax may preferably be performed by the press sweating method, the 
solvent method, vacuum distillation or fractionating crystallization to 
recover a fractionated wax. As the source of the hydrocarbon wax, it is 
preferred to use hydrocarbons having up to several hundred carbon atoms as 
obtained through synthesis from a mixture of carbon monoxide and hydrogen 
in the presence of a metal oxide catalyst (generally a composite of two or 
more species), e.g., by the Synthol process, the Hydrocol process (using a 
fluidized catalyst bed), and the Arge process (using a fixed catalyst bed) 
providing a product rich in waxy hydrocarbon, and hydrocarbons obtained by 
polymerizing an alkylene, such as ethylene, in the presence of a Ziegler 
catalyst, as they are rich in saturated long-chain linear hydrocarbons and 
accompanied with few branches. It is further preferred to use hydrocarbon 
waxes synthesized without polymerization because of their structure and 
molecular weight distribution suitable for easy fractionation. 
As for the molecular weight distribution of the wax, it is preferred that 
the wax shows a peak in a molecular weight region of 400-2400, further 
450-2000, particularly 500-1600. By satisfying such molecular weight 
distribution, the resultant toner is provided with preferable thermal 
characteristics. 
The release agent, when used, may preferably be used in an amount of 0.1-20 
wt. parts, particularly 0.5-10 wt. parts, per 100 wt. parts of the binder 
resin. 
The release agent may be uniformly dispersed in the binder resin by a 
method of mixing the release agent in a solution of the resin at an 
elevated temperature under stirring or melt-kneading the binder resin 
together with the release agent. 
The toner according to the present invention may preferably have a 
weight-average particle size of 3-10 .mu.m, more preferably 3-9 .mu.m, so 
as to provide high-quality images. 
A flowability-improving agent may be blended with the toner to improve the 
flowability of the toner. Examples thereof, particularly negatively 
chargeable ones may include: powder of fluorine-containing resin, such as 
polyvinylidene fluoride fine powder and polytetrafluoroethylene fine 
powder; titanium oxide fine powder, hydrophobic titanium oxide fine 
powder; fine powdery silica such as wet-process silica and dry-process 
silica, and treated silica obtained by surface-treating (hydrophobizing) 
such fine powdery silica with silane coupling agent, titanium coupling 
agent, silicone oil, etc.; titanium oxide fine powder, hydrophobized 
titanium oxide fine powder; aluminum oxide fine powder, and hydrophobized 
aluminum oxide fine powder. 
A preferred class of the flowability-improving agent includes dry process 
silica or fumed silica obtained by vapor-phase oxidation of a silicon 
halide. For example, silica powder can be produced according to the method 
utilizing pyrolytic oxidation of gaseous silicon tetrachloride in 
oxygen-hydrogen flame, and the basic reaction scheme may be represented as 
follows: 
EQU SiCl.sub.4 +2H.sub.2 +O.sub.2 .fwdarw.SiO.sub.2 +4HCl. 
In the above preparation step, it is also possible to obtain complex fine 
powder of silica and other metal oxides by using other metal halide 
compounds such as aluminum chloride or titanium chloride together with 
silicon halide compounds. Such is also included in the fine silica powder 
to be used in the present invention. 
It is preferred to use fine silica powder having an average primary 
particle size of 0.001-2 .mu.m, particularly 0.002-0.2 .mu.m. 
Commercially available fine silica powder formed by vapor phase oxidation 
of a silicon halide to be used in the present invention include those sold 
under the trade names as shown below. 
______________________________________ 
AEROSIL 130 
(Nippon Aerosil Co.) 200 
300 
380 
OX 50 
TT 600 
MOX 80 
COK 84 
Cab-O-Sil M-5 
(Cabot Co.) MS-7 
MS-75 
HS-5 
EH-5 
Wacker HDK N 20 
(WACKER-CHEMIE GMBH) V 15 
N 20E 
T 30 
T 40 
D-C Fine Silica 
(Dow Corning Co.) 
Fransol 
(Fransil Co.) 
______________________________________ 
It is further preferred to use treated silica fine powder obtained by 
subjecting the silica fine powder formed by vapor-phase oxidation of a 
silicon halide to a hydrophobicity-imparting treatment. It is particularly 
preferred to use treated silica fine powder having a hydrophobicity of 
30-80 as measured by the methanol titration test. 
Silica fine powder may be imparted with a hydrophobicity by chemically 
treating the powder with an organosilicone compound, etc., reactive with 
or physically adsorbed by the silica fine powder. 
Example of such an organosilicone compound may include: 
hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, 
trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, 
allyldimethylchlorosilane, allylphenyldichlorosilane, 
benzyldimethylcholrosilane, bromomethyldimethylchlorosilane, 
.alpha.-chloroethyltrichlorosilane, .beta.-chloroethyltrichlorosilane, 
chloromethyldimethylchlorosilane, triorganosilylmercaptans such as 
trimethylsilylmercaptan, triorganosilyl acrylates, 
vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, 
diphenyldiethoxysilane, hexamethyldisiloxane, 
1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 
dimethylpolysiloxane having 2 to 12 siloxane units per molecule and 
containing each one hydroxyl group bonded to Si at the terminal units. 
These may be used alone or as a mixture of two or more compounds. 
It is also possible to use a flowability-improving agent as a positive 
chargeability prepared by treating the above-mentioned dry-process silica 
with an amino group-containing silane coupling agent or silicone oil as 
shown below: 
##STR9## 
As a silicone oil, it is possible to use an amino-modified silicone oil 
having a partial structure including an amino group in its side chain as 
shown below: 
##STR10## 
wherein R.sub.1 denotes hydrogen, alkyl group, aryl group or alkoxy group; 
R.sub.2 denotes alkylene group or phenylene group; R.sub.3 and R.sub.4 
denote hydrogen, alkyl group or aryl group with the proviso that the alkyl 
group, aryl group, alkylene group and/or phenylene group can contain an 
amino group or another substituent, such as halogen, within an extent of 
not impairing the chargeability. m and n denote a positive integer. 
Commercially available examples of the amino group-containing silicone oil 
may include the following: 
______________________________________ 
Viscosity at 
Amine 
Trade name (Maker) 25.degree. C. (cPs) 
equivalent 
______________________________________ 
SF8417 (Toray Silicone K.K.) 
1200 3500 
KF393 (Shin'Etsu Kagaku K.K.) 
60 360 
KF857 (Shin'Etsu Kagaku K.K.) 
70 830 
KF860 (Shin'Etsu Kagaku K.K.) 
250 7600 
KF861 (Shin'Etsu Kagaku K.K.) 
3500 2000 
KF862 (Shin'Etsu Kagaku K.K.) 
750 1900 
KF864 (Shin'Etsu Kagaku K.K.) 
1700 3800 
KF865 (Shin'Etsu Kagaku K.K.) 
90 4400 
KF369 (Shin'Etsu Kagaku K.K.) 
20 320 
KF383 (Shin'Etsu Kagaku K.K.) 
20 320 
X-22-3680 (Shin'Etsu Kagaku K.K.) 
90 8800 
X-22-380D (Shin'Etsu Kagaku K.K.) 
2300 3800 
X-22-380IC (Shin'Etsu Kagaku K.K.) 
3500 3800 
X-22-3819B (Shin'Etsu Kagaku K.K.) 
1300 1700 
______________________________________ 
The amine equivalent refers to a g-equivalent per amine which is equal to a 
value of the molecular weight of an amino group-containing silicone oil by 
the number of amino groups in the silicone oil. 
The flowability-improving agent may have a specific surface area of at 
least 30 m.sup.2 /g, preferably 50 m.sup.2 /g, as measured by the BET 
method according to nitrogen adsorption. The flowability-improving agent 
may be used in an amount of 0.01-8 wt. parts, preferably 0.1-4 wt. parts, 
per 100 wt. parts of the toner. 
The toner according to the present invention may be prepared by 
sufficiently blending the binder resin, a magnetic or non-magnetic 
colorant, and a charge control agent or other additives, as desired, by a 
blender such as a Henschel mixer or a ball mill, followed by melt-kneading 
for mutual dissolution of the resins of the blend, cooling for 
solidification of the kneaded product, pulverization and classification to 
recover a toner product. 
The toner may be further sufficiently blended with an external additive 
such as a flowability-improving agent having a chargeability to a polarity 
identical to that of the toner by a blender such as a Henschel mixer to 
obtain a toner according to the present invention, wherein the external 
additive is carried on the surface of the toner particles. 
Various parameters characterizing the toner according to the present 
invention are based on values measured in the following manner. 
(1) Percentage changes .gamma.G' and .gamma.G" between strains of 1% and 
50% of storage modulus G' and loss modulus G" 
A toner is molded at room temperature under a pressure of 150 kg/cm.sup.2 
for 5 min. into a sample pellet of 25 mm in diameter and 2 mm in 
thickness. 
The sample pellet is disposed between parallel plates of 25 mm in diameter 
of a dynamic analyzer ("RDA-II", available from Rheometrics Co.) and 
subjected to application of a sinusoidal oscillation for measurement of G' 
and G". The measurement is performed at 150.degree. C. and the frequency 
is 1 Hz. The measurement of G' and G" is sequentially performed at strains 
in the range of 1%-100%. The percentage changes .gamma..sub.G', and 
.gamma..sub.G" are calculated by the following formulae: 
##EQU1## 
(2) Glass transition temperature Tq 
Measurement may be performed in the following manner by using a 
differential scanning calorimeter ("DSC-7", available from Perkin-Elmer 
Corp.). 
A sample in an amount of 5-20 mg, preferably about 10 mg, is accurately 
weighed. 
The sample is placed on an aluminum pan and subjected to measurement in a 
temperature range of 30.degree.-200.degree. C. at a temperature-raising 
rate of 10.degree. C./min in a normal temperature--normal humidity 
environment in parallel with a black aluminum pan as a reference. 
In the course of temperature increase, a main absorption peak appears in 
the temperature region of 40.degree.-100.degree. C. 
In this instance the glass transition temperature is determined as a 
temperature of an intersection between a DSC curve and an intermediate 
line passing between the base lines obtained before and after the 
appearance of the absorption peak 
(3) Molecular weight distribution 
The molecular weight (distribution) of a binder resin may be measured based 
on a chromatogram obtained by GPC (gel permeation chromatography). 
In the GPC apparatus, a column is stabilized in a heat chamber at 
40.degree. C., tetrahydrofuran (THF) solvent is caused to flow through the 
column at that temperature at a rate of 1 ml/min., and 50-200 .mu.l of a 
GPC sample solution adjusted at a concentration of 0.05-0.6 wt. % is 
injected. The identification of sample molecular weight and its molecular 
weight distribution is performed based on a calibration curve obtained by 
using several monodisperse polystyrene samples and having a logarithmic 
scale of molecular weight versus count number. The standard polystyrene 
samples for preparation of a calibration curve may be available from e.g., 
Pressure Chemical Co. or Toso K.K. It is appropriate to use at least 10 
standard polystyrene samples inclusive of those having molecular weights 
of, e.g., 6.times.10.sup.2, 2.1.times.10.sup.3, 4.times.10.sup.3, 
1.75.times.10.sup.4, 5.1.times.10.sup.4, 1.1.times.10.sup.5, 
3.9.times.10.sup.5, 8.6.times.10.sup.5, 2.times.10.sup.6 and 
4.48.times.10.sup.6. The detector may be an RI (refractive index) 
detector. 
For accurate measurement, it is appropriate to constitute the column as a 
combination of several commercially available polystyrene gel columns in 
order to effect accurate measurement in the molecular weight range of 
10.sup.3 -2.times.10.sup.6. A preferred example thereof may be a 
combination of .mu.-styragel 500, 10.sup.3, 10.sup.4 and 10.sup.5 
available from Waters Co.; a combination of Shodex KF-801, 802, 803, 804 
and 805 available from Showa Denko K.K.; or a combinations of TSK gel 
G1000H, G2000H, G2500H, G3000H, G4000H, G5000H, G6000H, G7000H, and GMH 
available from Toso K.K. 
(4) THF-insoluble content (gel content) 
The resinous residue (gel content) of a sample may be measured by Soxhlet's 
extraction in the following manner. About 0.5 g of a sample is weighed and 
placed in a cylindrical filter paper (e.g., "No. 86R" having a size of 28 
mm.times.100 mm, available from Toyo Roshi K.K.) on a Soxhlet's extractor 
and subjected to 6 hours of extraction with 200 ml of THF. At this time, 
the reflux rate is controlled so that each THF extraction cycle takes ca. 
4-5 minutes. After the extraction, the cylindrical filter paper is taken 
out and sufficiently dried to weigh the extraction residue. The gel 
content is calculated as (W.sub.2 /W.sub.1).times.100 (wt. %), wherein 
W.sub.1 denotes the sample resin weight and W.sub.2 denotes the resin 
weight in the extraction residue. For example, the weight W.sub.1 g refers 
to a sample toner weight minus the weight of a non-resinous THF insoluble 
matter such as a magnetic material and a pigment for a magnetic toner, or 
a sample toner weight minus the weight of a non-resinous THF-insoluble 
matter such as a pigment for a non-magnetic toner. Based on the weight 
W.sub.1 g and the weight W.sub.2 g obtained as the extraction residue 
weight minus the weight of a non-resinous THF-insoluble matter of the 
magnetic material and/or the pigment, the THF-insoluble resin content 
(gel) content is calculated as (W.sub.2 /W.sub.1).times.100%. 
Referring to the sole figure, in operation, THF 14 contained in a vessel 15 
is vaporized under heating by a heater 22, and the vaporized THF is caused 
to pass through a pipe 21 and guided to a cooler 18 which is always cooled 
with cooling water 19. The THF cooled in the cooler 18 is liquefied and 
stored in a reservoir part containing a cylindrical filter paper 16. Then, 
when the level of THF exceeds that in a middle pipe 17, the THF is 
discharged from the reservoir 17, the THF is discharged from the reservoir 
part to the vessel 15 through the pipe 17. During the operation, the toner 
or resin in the cylindrical filter paper is subjected to extraction with 
the thus circulating THF. 
Hereinbelow, the present invention will be described with reference to 
Production Examples and Examples for evaluation of image forming 
performances. 
Resin Production Example 1 
______________________________________ 
Terephthalic acid 18 mol. % 
n-Dodecenylsuccinic anhydride 
25 mol. % 
Trimellitic anhydride 5 mol. % 
Bisphenol derivative of the above- 
52 mol. % 
described formula (A) 
(R = propylene, x + y = 2.2) 
______________________________________ 
The above ingredients were subjected to polycondensation to obtain a 
polyester (called "Polyester Resin A") having Mn=3,000, Mw=15,000, 
Tg=55.degree. C., acid value=35 and THF-insoluble content=0%. 
______________________________________ 
Terephthalic acid 23 mol. % 
n-Dodecenylsuccinic anhydride 
23 mol. % 
Trimellitic anhydride 2 mol. % 
Bisphenol derivatives of the above- 
52 mol. % 
described formula (A) 
(R = propylene, x + y = 2.2) 
______________________________________ 
The above ingredients were subjected to polycondensation to obtain a 
polyester (called "Polyester Resin B") having Mn=6,000, Mw=45,000, 
Tg=62.degree. C., acid value=25 and THF-insoluble content=0%. 
______________________________________ 
Polyester Resin A 100 wt. parts 
Polyester Resin B 100 wt. parts 
Trimellitic anhydride 
8 wt. parts 
______________________________________ 
These ingredients were subjected to polycondensation to obtain a polyester 
(called "Polyester Resin I") having Mn=4,000, Mw=29,000, Tg=58.degree. C., 
and value=30, THF-insoluble content=35%. 
Resin Production Example 2 
100 wt. parts of Polyester Resin A and 5 wt. pats of trimellitic anhydride 
were subjected to polycondensation to obtain a-polyester (called 
"Polyester Resin II") having Mn=4500, Mw=32,000, Tg=56.degree. C., acid 
value=28 and THF-insoluble content=20%. 
Resin Production Example 3 
A prepolymer was prepared by reacting 1 mol of trimellitic anhydride with 3 
mol of a bisphenol derivative of the above-described formula (A) 
(R=ethylene, x+y=2.2). Then, 10 wt. parts of the prepolymer was mixed with 
100 wt. parts of Polyester Resin A and the mixture was subjected to 
further polycondensation to obtain a polyester (called "Polyester Resin 
III") having Mn=4,000, Mw=38,000, Tg=56.degree. C., acid value=26, and 
THF-insoluble content=28%. 
Resin Production Example 4 
______________________________________ 
Terephthalic acid 24 mol. % 
n-Dodecenylsuccinic anhydride 
24 mol. % 
Bisphenol derivative of the above- 
52 mol. % 
described formula (B) 
(R = propylene, x + y = 2.2) 
______________________________________ 
The above ingredients were subjected to polycondensation to obtain a 
polyester ("Polyester Resin C") having Mn=3,500, Mw=18,000, Tg=56.degree. 
C., acid value=30, and THF-insoluble content=0%. 
Then, 5 mol % of trimellitic anhydride was further added to Polyester Resin 
C and subjected to polycondensation to obtain a polyester ("Polyester 
Resin IV") having Mn=5,800, Mw=45,000, Tg=60.degree. C., acid value=22 and 
THF-insoluble content=45%. 
Resin Production Example 5 
______________________________________ 
Styrene 85 wt. parts 
n-Butyl acrylate 15 wt. parts 
Di-tert-butyl peroxide 
2.5 wt. parts 
Toluene 500 wt. parts 
______________________________________ 
The above mixture was subjected to polymerization to obtain a styrene 
copolymer resin (called "Vinyl Resin (a)") having Mn=5,500, Mw=13,000 and 
Tg=60.degree. C. 
______________________________________ 
Vinyl resin (a) 100 wt. parts 
Styrene 75 wt. parts 
n-Butyl acrylate 20 wt. parts 
Polyethylene glycol diacrylate 
5 wt. parts 
(crosslinking agent: 
CH.sub.2 .dbd.CHCOO(C.sub.2 H.sub.4 O).sub.n COCH.dbd.CH.sub.2, 
n = 14, Mw = 742) 
Benzoyl peroxide 3 wt. parts 
______________________________________ 
The above mixture was dispersed in an aqueous medium formed by dissolving 
(1 wt. part of polyvinyl alcohol in 1000 wt. parts of water and subjected 
to suspension polymerization, followed by washing with an NaOH aqueous 
solution to remove the polyvinyl alcohol to obtain a styrene 
copolymer-based resin composition (called "Vinyl Resin V") having 
Mn=8,000, Mw=60,000 and Tg=59.degree. C. 
Resin Production Example 6 
Resin Production Example 5 was repeated except for replacing the 
polyethylene glycol diacrylate with 4 wt. parts of tetraethylene glycol 
dimethacrylate (Mw=330) to obtain a resin composition (called "Vinyl Resin 
VI") having Mn=7,500, Mw=72,000 and Tg=60.degree. C. 
Resin Production Example 7 (comparative) 
______________________________________ 
Terephthalic acid 15 mol. % 
n-Dodecenylsuccinic anhydride 
12 mol. % 
Trimellitic anhydride 25 mol. % 
Bisphenol derivatives of the formula (A) 
(R = propylene, x + y = 2.2) 
20 mol. % 
(R = ethylene, x + y = 2.2) 
28 mol. % 
______________________________________ 
The above ingredients were subjected to polycondensation to obtain a 
polyester (called "Polyester Resin VII" (comparative)) having Mn=4,000, 
Mw=35,000, Tg=60.degree. C., and THF-insoluble content=40%. 
Resin Production Example 8 (comparative) 
______________________________________ 
Terephthalic acid 10 mol. % 
n-Dodecenylsuccinic anhydride 
17 mol. % 
Trimellitic anhydride 25 mol. % 
Bisphenol derivatives of the formula (A) 
(R = propylene, x + y = 2.2) 
15 mol. % 
(R = ethylene, x + y = 2.2) 
33 mol. % 
______________________________________ 
The above ingredients were subjected to poly-condensation to obtain a 
polyester (called "Polyester Resin VIII" (comparative)) having Mn=8,000, 
Mw=91,000, Tg=63.degree. C., and THF-insoluble content=45%. 
Resin Production Example 9 (comparative) 
Resin Production Example 5 was repeated except for replacing the 
polyethylene glycol diacrylate with 4 wt. parts of triethylene glycol 
dimethacrylate (Mw=286) to obtain a resin composition (called "Vinyl Resin 
IX" (comparative)) having Mn=7,000, Mw=70,000 and Tg=58.degree. C. 
Resin Production Example 10 (comparative) 
Resin Production Example 5 was repeated except for replacing the 
polyethylene glycol diacrylate with 2 wt. parts of divinylbenzene to 
obtain a resin composition (called "Vinyl Resin X" (comparative)) having 
Mn=6,000, Mw=80,000 and Tg=60.degree. C. 
EXAMPLE 1 
______________________________________ 
Polyester Resin I 100 wt. parts 
Magnetic iron oxide 90 wt. parts 
(average particle size (Dav.) = 0.1 .mu.m, 
Hc = 115 oersted, .sigma..sub.s = 80 emu/g, 
.sigma..sub.r = 11 emu/g) 
Long-chain alkyl alcohol of the above- 
5 wt. parts 
described Formula (C) (x = 50) 
Mono-azo metal complex 2 wt. parts 
(negative charge control agent) 
______________________________________ 
The above ingredients were pre-mixed by a Henschel mixer and melt-kneaded 
through a twin-screw extruder at 130.degree. C. After cooling, the 
melt-kneaded product was coarsely crushed by a cutter mill and finely 
pulverized by a jet stream pulverizer, followed by classification by a 
pneumatic classifier to obtain a magnetic toner having a weight-average 
particle size of 6.5 .mu.m. To 100 wt. parts of the magnetic toner, 1.0 
wt. part of hydrophobic dry-process silica (BET specific surface area 
(S.sub.BET)=300 m.sup.2 /g) was externally added to obtain a magnetic 
toner. 
The thus-obtained magnetic toner was subjected to measurement of storage 
modulus G' and loss modulus G" at strains in the range of 1-50% in the 
above-described manner to obtain G'.sub.1% =2.2.times.10.sup.4 
dyn/cm.sup.2 and G".sub.1% =1.6.times.10.sup.4 dyn/cm.sup.2 at a strain of 
1%, and G'.sub.50% =2.1.times.10.sup.4 dyn/cm.sup.2 thus giving percentage 
changes of .gamma..sub.G' =4.5% and .gamma..sub.G" =6.3%. 
The magnetic toner was charged and evaluated in a re-modeled machine of a 
commercially available laser beam printer ("LBP-A304", mfd. by Canon K.K.) 
under the conditions of a process speed of 50 mm/sec., a fixing roller 
diameter of 20 mm and a fixing pressure of ca. 1.3 kg/cm.sup.2, and also 
in a re-modeled machine of a commercially available copier ("NP-8582", 
mfd. by Canon K.K.) under the conditions of a process speed of 500 mm/sec, 
a fixing roller diameter of 60 mm and a fixing pressure of ca. 5 
kg/cm.sup.2). The evaluation was performed with respect to, e.g., image 
qualities, fixability and anti-offset characteristic, whereby good results 
as shown in Tables 2 and 3 appearing hereinafter were obtained. Regarding 
the fixability, the fixing initiation temperature was lowered by 
30.degree.-40.degree. C. than the conventional toner both in the low-speed 
system and in the high-speed system. 
EXAMPLES 2-4 
Magnetic toners were prepared and evaluated in the same manner as in 
Example 1 except that Polyester Resin I was replaced by Polyester Resins 
II-IV, respectively. The resultant magnetic toners showed viscoelastic 
properties as shown in Table 1 and good performances as shown in Tables 2 
and 3. 
EXAMPLES 5 and 6 
Magnetic toners were prepared and evaluated in the same manner as in 
Example 1 except that Polyester Resin I was replaced by Vinyl Resins V and 
VI, respectively. The resultant magnetic toners showed viscoelastic 
properties as shown in Table 1 and good performances as shown in Tables 2 
and 3. Regarding the fixability, the toners provided fixing initiation 
temperatures which were lower by 30.degree.-40.degree. C. in the low-speed 
system and lower by 10.degree.-20.degree. C. in the high-speed system, 
compared with those obtained by the conventional toners. 
Comparative Examples 1-3 
Magnetic toners were prepared and evaluated in the same manner as in 
Example 1 except that Polyester Resin I was replaced by Polyester Resin 
VII, Polyester Resin A and Polyester Resin VIII (all comparative). The 
resultant magnetic toners provided the results shown in Tables 1-3. 
Comparative Examples 4 and 5 
Magnetic toners were prepared and evaluated in the same manner as in 
Example 1 except that Polyester Resin I was replaced by Vinyl Resins IX 
and X (comparative). The resultant magnetic toners provided the results 
shown in Tables 1-3. 
The toner performances shown in Tables 2 and 3 were evaluated in the 
manners described below and basically at 5 levels of excellent (o), good 
(o.increment.), fair (.increment.), rather inferior (.increment.x) and 
inferior (x). 
Fixability 
A sample image after image formation on 1000 sheets was rubbed with a lens 
cleaning paper to measure a density decrease before and after the rubbing. 
The image densities were measured by a refractive densitometer ("Macbeth 
RD918", mfd. by Macbeth Co.). A solid image having an image density of 
1.1-1.5 and a halftone image having an image density of 0.4-0.7, 
respectively as measured before rubbing were evaluated. 
The performances were evaluated by a density decrease and indicated as o 
(0-10%), o.increment. (11-25%), .increment. (26-35%), .increment.x 
(36-45%) and x (46% or above). 
Fixing initiation temperature 
The fixing initiation temperature was measured by effecting fixation of 
un-fixed solid black toner images at varying temperatures of the fixing 
device and to evaluate the lowest temperature at which the fixation was 
effected through confirmation by rubbing of the fixed images. 
The results are shown in Tables 2 and 3 under the item of fixability for 
solid black images, e.g., 110.degree. C. (Table 2) and 155.degree. C. 
(Table 3) for Example 1. 
Low-temperature offset 
The fixability was evaluated in a low temperature/low humidity environment 
(10.degree. C./15% RH). 
High-temperature offset 
The high-temperature offset temperature was measured as the lowest 
temperature at which the high-temperature occurred as a result of fixing 
tests at varying fixing device temperatures. 
Web soiling 
Soiling of the fixing roller cleaning web was evaluated after image 
formation and fixation on 1000 sheets each of a solid black image and a 
halftone image in a normal temperature/normal humidity environment 
(23.degree. C./60% RH) and observing the soiling of the web by eyes. 
Maximum image density (Dmax) 
The maximum image density was evaluated according to the standards of o 
(.gtoreq.1.35), o.increment. (1.25-1.34), .increment. (1.15-1.24), 
.increment.x (1.00-1.14) and x (&lt;1.00). 
White background fog 
Fog was evaluated by measuring a worst or maximum reflection density (Ds %) 
on the white background after the image formation and an average 
reflection density (Dr %) of the white background on transfer paper before 
the image formation by using a reflective densitometer ("Reflectometer 
Model TC-6DS", mfd. by Tokyo Denshoku K.K.) and evaluated in terms of fog 
amount (=Ds-Dr %). The results are indicated as o (fog amount 
.ltoreq.1.5%), o.increment. (1.6-2.0%), .increment. (2.1-2.5%), 
.increment.x (2.6-3.5%) and x (.gtoreq.3.6%). 
Density gradation characteristic 
Evaluated by eye observation. 
Line scattering 
Evaluated by eye observation, 
Line collapsion (resolution failure) 
Evaluated by eye observation. 
Winding (offset). 
Evaluated by passing solid black images to observe whether winding offset 
occurred or not. 
Trace 
Solid black images were formed to observe whether some traces of a 
separating member are left on the fixed images. 
TABLE 1 
__________________________________________________________________________ 
Viscoelastic properties of toner 
.sup.G' 1% 
.sup.G" 1% 
.sup.G' 50% 
.sup.G" 50% 
.sup..gamma. G' 
.sup..gamma. G" 
Example 
Binder resin 
(dyn/cm.sup.2) 
(dyn/cm.sup.2) 
(dyn/cm.sup.2) 
(dyn/cm.sup.2) 
(%) (%) 
__________________________________________________________________________ 
Ex. 
1 Polyester Resin I 
2.2 .times. 10.sup.4 
1.6 .times. 10.sup.4 
2.1 .times. 10.sup.4 
1.5 .times. 10.sup.4 
4.5 6.3 
2 Polyester Resin II 
6.5 .times. 10.sup.3 
3.5 .times. 10.sup.3 
4.4 .times. 10.sup.3 
2.3 .times. 10.sup.3 
32.3 
34.3 
3 Polyester Resin III 
6.5 .times. 10.sup.4 
5.5 .times. 10.sup.4 
6.2 .times. 10.sup.4 
5.0 .times. 10.sup.4 
4.6 9.1 
4 Polyester Resin IV 
7.0 .times. 10.sup.4 
6.0 .times. 10.sup.4 
5.5 .times. 10.sup.4 
4.6 .times. 10.sup.4 
21.4 
23.3 
5 Vinyl Resin V 
1.0 .times. 10.sup.4 
9.0 .times. 10.sup.3 
9.5 .times. 10.sup.3 
8.5 .times. 10.sup.3 
5.0 5.6 
6 Vinyl Resin VI 
6.8 .times. 10.sup.4 
5.7 .times. 10.sup.4 
6.5 .times. 10.sup.4 
5.2 .times. 10.sup.4 
4.4 8.8 
Comp. 
Ex. 
1 Polyester Resin VII 
1.5 .times. 10.sup.4 
9.5 .times. 10.sup.3 
6.5 .times. 10.sup.3 
4.2 .times. 10.sup.3 
56.7 
55.8 
2 Polyester Resin A 
5.0 .times. 10.sup.3 
3.0 .times. 10.sup.3 
2.0 .times. 10.sup.3 
1.2 .times. 10.sup.3 
60.0 
60.0 
3 Polyester Resin VIII 
2.5 .times. 10.sup.5 
1.5 .times. 10.sup.5 
1.5 .times. 10.sup.5 
9.0 .times. 10.sup.4 
40.0 
40.0 
4 Vinyl Resin IX 
2.5 .times. 10.sup.4 
9.7 .times. 10.sup.3 
1.1 .times. 10.sup.4 
4.0 .times. 10.sup.3 
56 58.8 
5 Vinyl Resin X 
4.1 .times. 10.sup.5 
2.5 .times. 10.sup.5 
2.0 .times. 10.sup.5 
1.2 .times. 10.sup.5 
51.2 
52.0 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
(Process speed = 50 mm/sec) 
Fixability Low High 
Web soiling Image characteristics 
Solid 
Half- 
temp. 
temp. 
Solid 
Half- Grada- 
Line 
Line 
Example 
black 
tone 
offset 
offset 
black 
tone 
Winding 
Trace 
Dmax. 
Fog tion 
scatter 
collapse 
__________________________________________________________________________ 
Ex. 1 
.smallcircle. 
.smallcircle. 
.smallcircle. 
240.degree. C. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
110.degree. C. (1.40) 
(1.2%) 
Ex. 2 
.smallcircle. 
.smallcircle. 
.smallcircle. 
210.degree. C. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
100.degree. C. (1.40) 
(1.3%) 
Ex. 3 
.smallcircle. 
.smallcircle. 
.smallcircle. 
240.degree. C. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
110.degree. C. (1.40) 
(1.2%) 
Ex. 4 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle. 
240.degree. C. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
120.degree. C. (1.40) 
(1.3%) 
Ex. 5 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
230.degree. C. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
130.degree. C. (1.37) 
(1.8%) 
Ex. 6 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
240.degree. C. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
135.degree. C. (1.36) 
(1.8%) 
Comp. 
.DELTA. 
.DELTA.x 
.DELTA. 
200.degree. C. 
.DELTA. 
.DELTA.x 
.DELTA.x 
.DELTA.x 
.DELTA. 
.DELTA. 
.DELTA. 
.DELTA. 
.DELTA. 
Ex. 1 
145.degree. C. (1.20) 
(2.3%) 
Comp. 
.DELTA. 
.DELTA. 
.smallcircle..DELTA. 
190.degree. C. 
.DELTA.x 
.DELTA.x 
x x .DELTA. 
.DELTA. 
.DELTA. 
.DELTA. 
.DELTA. 
Ex. 2 
140.degree. C. (1.22) 
(2.2%) 
Comp. 
x x x 200.degree. C. 
x .DELTA.x 
.smallcircle. 
.smallcircle. 
.DELTA. 
.DELTA. 
.DELTA. 
x x 
Ex. 3 
150.degree. C. (1.20) 
(2.3%) 
Comp. 
.DELTA. 
x .DELTA.x 
200.degree. C. 
.DELTA.x 
.DELTA.x 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.DELTA. 
.DELTA.x 
.DELTA.x 
.DELTA.x 
.DELTA.x 
Ex. 4 
160.degree. C. (1.21) 
(3.0%) 
Comp. 
x x x 200.degree. C. 
x x .smallcircle. 
.smallcircle. 
.DELTA.x 
.DELTA.x 
.DELTA.x 
x x 
Ex. 5 
170.degree. C. (1.17) 
(3.1%) 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
(Process speed = 500 mm/sec) 
Fixability Low High 
Web soiling Image characteristics 
Solid 
Half- 
temp. 
temp. 
Solid 
Half- Grada- 
Line 
Line 
Example 
black 
tone 
offset 
offset 
black 
tone 
Winding 
Trace 
Dmax. 
Fog tion 
scatter 
collapse 
__________________________________________________________________________ 
Ex. 1 
.smallcircle. 
.smallcircle. 
.smallcircle. 
280.degree. C. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
155.degree. C. (1.40) 
(1.1%) 
Ex. 2 
.smallcircle. 
.smallcircle. 
.smallcircle. 
240.degree. C. 
.smallcircle. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
145.degree. C. (1.40) 
(1.2%) 
Ex. 3 
.smallcircle. 
.smallcircle. 
.smallcircle. 
280.degree. C. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
155.degree. C. (1.40) 
(1.0%) 
Ex. 4 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
280.degree. C. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
165.degree. C. (1.40) 
(1.2%) 
Ex. 5 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
270.degree. C. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
175.degree. C. (1.38) 
(1.7%) 
Ex. 6 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
280.degree. C. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle. 
.smallcircle..DELTA. 
.smallcircle..DELTA. 
185.degree. C. (1.38) 
(1.8%) 
Comp. 
.DELTA. 
x x 230.degree. C. 
x x .DELTA. 
x .DELTA. 
.DELTA. 
.DELTA. 
x x 
Ex. 1 
190.degree. C. (1.22) 
(2.4%) 
Comp. 
x x x 220.degree. C. 
x x x x .DELTA. 
.DELTA. 
.DELTA. 
x x 
Ex. 2 
185.degree. C. (1.21) 
(2.3%) 
Comp. 
x x x 230.degree. C. 
x .DELTA.x 
.DELTA. 
.DELTA. 
.DELTA. 
.DELTA. 
.DELTA. 
x x 
Ex. 3 
195.degree. C. (1.20) 
(2.2%) 
Comp. 
.DELTA. 
x x 230.degree. C. 
x x .DELTA.x 
x .DELTA. 
.DELTA.x 
.DELTA.x 
.DELTA.x 
.DELTA.x 
Ex. 4 
195.degree. C. (1.22) 
(2.8%) 
Comp. 
x x x 230.degree. C. 
x x .smallcircle. 
.smallcircle. 
.DELTA.x 
.DELTA.x 
.DELTA.x 
x x 
Ex. 5 
200.degree. C. (1.08) 
(3.0%) 
__________________________________________________________________________