Note: Descriptions are shown in the official language in which they were submitted.
~06Z9~L6
BACKGROUND OF THE INVE~ITI ON
This invention relates to electrophotographic copying
' methods and to toner compositions used to develop electrostatic
latent images electrostatically biased with respect thereto.
More particularly, this invention relates to such
copying methods and compositions, wherein the toner is perman-
ently bonded to the copy member with pressure and/or heat.
The formation and development of images on the surface
of photoconductive materials by electrostatic means is well
known. The basic electrostatographic process, as taught by
C.F. Carlson in U.S. Patent 2,297,691, involves placing a uni-
form electrostatic charge on a photoconductive insulating
layer, exposing the layer to a light and shadow image to
~l dissipate the charge on the areas of the layer exposed to the
light and developing the resulting electrostatic latent image
~. I .
by depositing on the image a~finely divided electroscopic
matexial referred to in the art as "toner". The toner will
normally be attracted to those areas of the layer which retain
.~ .
a charge, thereby forming a toner image corresponding to the
electrostatic latent image. This toner ima~e may then be fixed
in place or transferred to a copy~substrate such as paper. ~he
image may subsequently be permanently affixed to the copy sub-
strate such as by fusion with heat. Instead of forming the
.,,
latent image by uniformly charging the photoconductive layer
and then exposing the layer to a light and shadow image, one
may form the latent image by directly charging an insulating
layer, which can be either photoconductive or non-photoconduc-
tive, in image configuration. The powder may be fixed directly
,j to the insulating layer if desired.
One of the important applications of electrostatography
,
~"
.s .~
2-
V
e 1o6z946
comprises its use in automatic copying machines for general
office use wherein an electrostatic latent image is developed
using a developer oomposition comprising a carrier mixed with
fine particles of thermoplastic resinous toner, and the thus
. . .
formed powder image is transferred to a copy substrate and then
fixed thereon~ Considerabie effort has been expended to provide
suitable developers and associated fixing techniques for modern
high speed copying machines. The toner material used must have `
suitable electrostatic properties to permit attraction by the
carrier and then selective attraction by the latent images. It
must further by physically strong to permit constant recycling
in a bouncing type of movement. The toner must further be re-
sistant to blocking or aggregating at ordinary operating temp-
eratures, but yet be capable of being readily fixed to the copy
., .
: ! sheet.
Fixing techniques employing heat, pressure~ solvents
~ and various combinations thereof have been devised; however,
-, each of these systems is subject to severe practical limitations
which inhere in the systems thëmselves and also the toner compo-
~ sitions heretofore available. The most commonly employed fixa-
;~3~ ~ tion techniques rely on heat alone or heat in combination with
-~ pressure. These techniques, although quite effective~ do in-
volve certain disadvantages in terms of the time required to
heat the toner particle up to its softening point, excessive
heat emanating from the copy apparatus, power consumption, and
;,1 initial warm-up time of the copy apparatus required to permit
~, heat fusing devices to reach proper fusing temperatures. Thus,
the provision of toner materials which can be properly fixed to
~ a given substrate either without the necessity of heat or with
i~ lesser amounts of heat would be of great advantage in electro-
,...
,", ,
~:,
~ ~3~
~;,,
' ~ '` ` .
~062946
photographic processes. Some of the problems faced in designing
a copying method and toner composition with reduced time and
energy demands in the bonding or fixing step are outlined in
U.S. Patent 3,590,000, at columns 2 and 3.
Various types of materials have been proposed in the
prior art for use as the resinous component in electrostato-
graphic toners. U.S. Patent RE 25,136 teaches heat fixable
toner material based on polystyrene or copolymers of styre~e
with monomers such as alkyl methacrylates. Goffe in U.S.
Patent 3,615,394 teaches a solvent fixation process employing
a wide variety of resinous materials as toner components,
including, generically, polyamide or polyester materials.
6~ Pressure fixation is accomplished in Claus U.S. Patent 3,080,318
using a liquid toner encapsulated in a hydrophilic colloid,
`i which dual structure is further encapsulated in a hydrophobic
.,
resin. British patent 1,210,665 discloses a pressure fixable
- toner composition based on a mixture of a long chain aliphatic
compound, such as a wax or fatty acid, and an appropriate pig-
~ ment. The composition may also~contain a thermoplastic resin
'! - such as a polyamide or modified resin. U.S. Patent 3,6~1,106
.. . .
!lj dLscloses a heat-fixable, low-melting resinous toner composition
comprising a polyester resin and an alkylene oxide derivative
of a polyether. U.S. Patent 3,764,538 teaches a developer
. ~ .
powder designed to fuse rapidly at a temperature below the
char point of copy paper, comprised of a relatively non-brittle
thermoplastic polyamide and a relatively brittle thermoplastic
resin modifier. While all of these and other materials offex
;,.j
~ certain advantages for various techniques of fixation, t~ere
s
is a continuing need for new and uncomplicated toner systems
which offer a proper balance of triboelectric properties,
h'~, .
,` ,
-4- )
:~ .
'. . ,
-` ~06Z946 ~
... ' ,
... .
pressure responsiveness and image quality.
:. SUMMARY OF THE INVENTION
.. . .
In accordance with one aspect of this invention there .:
!~ is provided an electrostatographic toner composition for use in .;
:, . ....
developing an electrostatic latent image in an electrostato-
graphic copying method, said toner comprising a colorant
;~ material and a resin blend, said resin blend comprising, (a)
,
~i. a polyamide resin prepared by reacting a diamine with a material : ~
... . .
'` containing a dimer fatty acid, said acid formed by combining two .`
. .
~ 10 molecules of an unsaturated fatty acid, and said diamine being .:
.i : '
a member selected from the group consisting of alkylene and .
. arylene diamines; (b) a polyester resin selected from the group
.~ consisting of: esterification products of diols and dicarboxy~
, .~ . .
~ lic acids; condensation products of mixtures of a polycarboxy- . ~ :
.. ~ lic acid, a diol,.and a member selected from the group consist- .:~ -
~'! ing of alkylene and arylPne oxides and organic glycols; and . - .
~ condensation products of mixtures of a polycarboxylic acid, a
~ diol,.an organic glycol, and a member selected from the group ~ :~
~ i, ~ . . . ... .
~ consisting of alkylene and arylene oxides.
;.. ~ ~ . .
~-~ 20 ~ In accordance with another aspect of this invention ~. .: -
there is provided in an electrostatographic copying method for
r ci , . .
reproducing original images which comprises forming an electro- ~
static latent image of the original on a recording member, ; ~;.
developing said latent image by applying thereto an electro-
statically attractive toner material, and bonding a toner image
.l to the surface of a copy member to produce the copy; the improve- : :
ment which comprises employing as the toner material a com~
position comprised of a colorant material and a resin blend,
wherein said blend is comprised of: (a) a polyamide resin pre-
~,' 30 pared by reacting a diamine with a material containing a dimer
", ~.
fatty acid, said acid formed by combining two molecules of an ~ ~
_ 5 _ ' .
'' ~',
1~6Z94~ ~
.. , - unsaturated fatty acid, and said diamine being a member selected
~ from the group consisting of alkylene and arylene diamines; (b)
.` a polyester resin selected from the group consisting of:
' esterification products of diols and dicarboxylic acids; con-
:~ densation products of mixtures of a polycarboxylic acid, a diol,
and a member selected from the group consisting of alkylene and
arylene oxides and organic glycols; and condensation products
`, of mixtures of a polycarboxylic acid, a diol, an organic glycol,
and a member selected from the group consisting of alkylene and
aryleae oxides.
.! , ::
S'
.~i'j ~,
" , ' ~'
.. ,; ~' ' ' ' ' `' ~'
.`,j' , ~ .
'''~ ' ' ' '; ,'
'i',: ~ ` ' . ' '
!',:, . ,~ ,
f ~
."
:~' 1 ' ' ' , ' ,`
.. ~ . .
' ! 1 j
.... .
j ' , ' :,
... 1 " , .,
.~ . . ,
~ 6Z946
By way of added explanation, according
to the present invention in one aspect, electrostato-
grap~ic images may be permanently fixed in place by the appli-
cation of pressure alone, or pressure and small amounts of heat,
~ or by heat alone at temperatures as low as the blocking tempera-
; ture of the toner composition of this invention, using a
specific particulate toner composition as the imaging material.
The toner composition is based on a blend of a polyamide resin
and a polyester resin, and also includes a minor amount of a
coloring material such as carbon black. The particulate toner
composition o the present in~ention is found to have good ~ ~ -
triboelectric properties, good imaging qualities and superior
vlsco-elastic characteristics such that when pressure is
applied, the material will be caused to undergo distinct
, physical changes. It will flow suf~iciently such that cohesive ;-
bonds are formed between the various particles to gi~e the
impression of a continuous film, and also flow sufficiently
" !
to adhere to a substrate material such as paper.
Speci~ically, the toner composition of this invention
possesses a time-variable complex modulus, i.e., stiffness,
:.: ~ . ~
~; ~ such that the toner is relatively brittle for forces applied
r~ ' over a short time span, such as those encountered during toner
preparation by micronizing (microseconds), and is relatively
deformable for forces applied over a longer time span, such as
encountered during pressure fixing (milliseconds). While the
,j . .
:~ energy input needed for bonding the instant toner to the copy
,~
member is considerably lower than the prior art requirements,
it is not so low as to allow the toner to block during storage
~1 or for the ¢opy member to block to other members.
Y~'~ , , ~
: :, ".
, . :. .
~ -5b-
:;
' ` 10629~6
.
ETAILED D:E:SCRIPTION OF I~IE INVENTION
~ he electrostatographic toners of this invention are
comprised of a resinous blend of an amorphous or partially
crystalline polyamide material and a polyester condensation
product. Preferred polyamides are thermoplastic materials~
having softening points within the range of about 80C to 200C,
more preferably from about 90 to 130C., and an average
molecular weight within the range of from about 1,000 to about
10,000, more preferably within the range of 1500 to 10,000.
Examples of suitable polyamides are those prepaxed by the
reaction of dimer or dimer and trimer unsaturated fatty acids,
especially oleic or linoleic acids, or acid derivatives with
aklylene and arylene diamines, such as the polyamides which
are commercially available from Emery Industries, Inc., under
1 the trade name "Emerez".
`3 Although polyamide materials such as described above
~ exhibit good pressure responsive characteristics and a desirably
;-~ low modulus under fixation conditions, the triboelectric
~i properties and image quality of such materials are generally
unsatisfactory for use in an electrostatographic toner compo-
sition. It has been discovered that the pressure responsive
characteristic of low modulus can be substantially retained
;:`
while triboelectric characteristics and image quality are
~i markedly improved by forming blends of the polyamide with a
.
relatively low molecular weight, glassy polyester material.
, Preferred polyester materials are those having a softening
~- point greater than about 40C, preferably within the range of
1 about 45C to 150C., and a molecular weight within the range
of about 1000 to about 180,000, preferably within the range
of about 1500 to 20,000. Suitable polyesters include those
~' .
.~ . ,
~,~ :. .
. 6
.` . .
;; . ~
` 1~6Z946 -.
formed as the esterfication products of diols and dibasic
carboxylic acids, or the condensation products of a mixture of
a polycarboxylic acid, a diol, and an alkylene or arylene oxide
and/or an organic glycol. Examples of suitable polyester
materials which may be employed are disclosed in U.S. Patents
3,590,000 and 3,681,106. Particularly preferred materials
comprise condensates of Bisphenol-A, ethylene oxide and fumaric
acid, or Bisphenol A, ethylene glycol and fumaric acid which
are available from Atlas Chemical Industries, Inc. of
Wilmington, Delaware under the tradename "Spar".
Especially good results in terms of pressure fixation,
image quality and image retention have been achieved using,
as the polyamide component, resins available from Emery Indus-
tries under the tradenames "Emerez 1536" and "Emerez 1538".
These materials are based on the reaction product of mixed
dimer and trimer unsaturated fatty acids~and a diamine, with
the resultant polymer terminated with phenol end groups. They
have an average molecular weight of 1800-2500, a softening
.~ ..
point of 105C. and a glass transition temperature in the
range of 82-85C.
., ~
The preferred resinous modifier for the polyamides
is a polyester material available from Atlas Chemical Industries,
Inc. of Wilmington, Delaware, undex the tradename "Spar II"
whiah is a condensate of Bisphenol-A and ethylene oxide with
fumaric acid. These materials typically have a molecular
weight within the range of about 1000 to 8000.
The proportion of polyamide and polyester resins 3
present in the blend may vary within wide limits. Generally,
the image quality and triboelectric characteristics of toner
prepared from the blend of resins is unsatisfactory at polester
,
.
~; :
. .
., : .
1C~6Z946
to polyamide ratios of less than 1:9; on the other hand~
undesirably excessive pressure is required to pressure-fix
toner where this ratio is greater than 9:1. Thus, the
preferred ratio of polyamide to polyester in the resin blend
is within the range of 1:9 to 9:1, and most preferably 1:4 to
4:1.
The resinous blend may be fabricated into electro-
statographic toner using any of the known techniques of the
prior art by mixing the blend with a colorant material.
., .
Mixing may be accomplished by melt blending the polyamide and
~ polyester in a heated two roll mill and dispersing the colorant
?
in the melted blend, hardening the composition and pulverizing
I the composition in a device such as a jet or hammermill to form
i~
it into small particles. Alternatively, mixing may be carried
~ out by combining tne colorant with a solution, dispersion or
;~ latex of the polymer blend, followed by recovery of the
.~
3~ mixture in finely divided form by spray drying techniques.
Still another technique or preparing the toner composition is
to individually prepare particulate toner based on a mixture
of the polyamide and colorant and the polyester and colorant,
.~ .
and subsequently mix the particulate components to form the
toner blends of this invention. Suitable method~ o mixing
are more thoroughly described in U.S. Patent 3,502,582. The
average particle size of the processed toner should be within
the range of about 1 to 30 microns, preferably betwe~n about
3 to 15 microns. A subsequent screening or sizing operation
'~, may be necessa~y to produce a toner having this particle size
` distribution. ~-
~!
~ - The colorant material used in preparing the toner
i ! composition may include any pigment or water or organic solvent
.,
.!
8-
,,,~ , "~ .'.
.
.
~ ~ 1062946
.
soluble dye. The most common pigmen~s used in electrostato-
graphic toner materials are finely divided carbon black, cyan,
magenta and yellow pigments. The most common dyes are the acid,
basic and dispersed dyes of suitable color as are known in the
, art. Typical examples of suitable colorants are discussed in
,!~ U.S ~ Patent 3,5~2,582. The pigment or dye should be present in
- the amount effective to render the toner highly colored so that
it will form a clearly visible image on a recording member.
Preferably, for sufficient color density and suitable imaging
characteristics, the pigment is employed in an amount from
!. ', .
' akout 1% to about 20% by weight, based on the total weight of
.
the colored toner. If the toner colorant employed is a dye,
quantities suhstantially smaller than about 1% by weight may be
used.
The toner composition may be formulated into an elec-
~3 trostatograp~ic developer composition by combining the finely
h~ divided toner with a suitable carrier material such that the
toner forms a coating on the carrier. The toner and carrier
material may be premixed or mixed inside the developer region
of a xerographic copying machine. Where the development process
is the well known magnetic brush process, the carrier material
will be magnetically attractive material such as finely
: ~; . . ,
divided iron particles of about 60 to 120 mesh size. For other
than magnetic brush development, the carrier material may be of
.. ;~ .
`i~ any of t~e known particulate substances exhibiting appropriate
triboelectric effects such that the carrier particles impart a
charge to the finer toner whereby the toner a~heres to and ~ -
coats each carrier particle. Examples of suitable carriers are
inorganic salts, glass, silicon, steel and other materials such
r~. :
~ as disclosed in the aforementioned U.S. Patent 3,502,582. The
.:;
t~` ~
9_
~"~
.i. , .
~, .
. 1[)62~3t46
particle size of the carrier is preferably significantly greater
than the toner, preferably within the range of about 50 to lO00
microns. The toner is most effectively employed at a level from
about 0.5 to lO parts by weight per 100 parts by weight of
carrier matexial. In some applications, no carrier is required.
For example, the toner composition containing a minor amount
of ferromagnetic material uniformly dispersed therein may be
used in a magnetic brush development system as, for example,
disclosed in U.S. Patent 3,563,734.
The toner and developer compositions of the present
invention may also contain any of the additives known to be
included in such compositions such as lubrication aids, anti-
'!
~` oxidants, sensitizing agents, polymeric or non-polymeric plasti-
cizers, triboelectric modifiers such as silica, and the like.
The toner composition of the present invention may be
9 fixed in image configuration to a substrate material such as
9 paper by the application of pressure alone at ambient tempera-
tures or pressure plus a moderate amount of heat. The pre-
ferred technique for fixation at ambient temperatures is to `
.
pass a substrate material containing the toner image through
the nip of a pair of spring biased pressure rolls at a speed
3 ~ and~under sufficient pressure such as to cause the toner to
';i i
cohesively flow and adhere to the substrate materialO In the
case of steel pressure rolls having a diameter of 2.25 inches
, and spring loaded with four steel spiral springs having a
, . .
,'! spring constant of 1630 pounds per inch, pressures within
5~ thé range of from about 10 to lO00 lbs. per lineal inch (~pli)
at a roll speed of about 56 revolutions per minute may be
applied to suitably fix the toner. In some ~ases, pressures
f`. above 500 lbs. pli may damage the substrate material and
~.
;,, :
.
--10--
- ~6Z946
pressures below about 20 pli may be insufficient to properly
fix the toner without heat assistance.
, Another device which may be used to pressure fix the
toner image is a contact type fusing device such as disclosed
in U.S. Patent 3,268,351. Such a device comprises a pair of
low pressure (less than 10 lbs pli.) contact rolls at least
, one of which is heated to assist the fixation process. This
1 device is adapted to be used with toner materials which are not
sufficiently fixable by pressure alone, and conse~uently the
,l toner bearing substrate must be heated to temperatures of
about 325F. for proper fixation. However, toner compositions
of the present invention may be adequately fixed using such a
low pressure device at temperatures corresponding to the
blocking temperature of the resinous blend, i.e., in the order
of 130 to 150F~, with a resulting saving in energy requirements
and a considerable lessening of machine heat output. Also,
o~ images composed of the present toner material may be adequately
~ fused to paper without pressure using conventional radiant heat
:1 .
fusing devices at temperatures as low as about 175F. This
may involve a power wattage saving of from about 15 to 40% as
.~
~ opposed to the amount of power required to properly fuse some
~,, .
commercially available styrene based toners such as disclosed
in the aforementioned U.S. Patent RE 25,136.
DESCRIPTION OF THE PREFERRED EMBODIMEiNTS
!
The following examples serve to illustrate the pre-
, paration of toner and developer compositions and preferred
, methods for fixation. For comparativ~ purposes, toner compo-
sitions were prepared containing only the polyamide resin,
only the polyester resin and a plurality containing mixtures
of polyamide and polyester resins in various ratios.
" ~ .
.~,. . .
;,
. . .
. . .
,, .
.
629~6
EXAMPLE I
` Toner material based on a polyamide resin as the sole
resinous component was prepared as follows. One hundred parts
by weight of "Emerez 1538" polyamide resin was melted and
introduced into a two roll rubber mill. "Emerez 1538" is
commercially available fro,n Emery Industries, Inc., It has a
softening point of about 105C., a Glass Transition temperature
of 82-85C., a percent Elongation of about 200 and an average
molecular weight within the range of 1800-2500. Ten parts by
weight of carbon black pigment was introduced by sprinkling
the pigment into the resin mass and milling was continued for
about 20 minutes to insure the formation of a homogeneous
dispersion of the pigment in the mass. The carbon blaak used
was a Long-Flow Furnace black available from Cabot Corporation
under the trade name "Black Pearls L". After 20 minutes
~ milling, the temperature of the mass was reduced and the
; milled product was removed from the rolls as one slab. The
`~ slab product was then ground in a hammermill and micronized.~ .
in a jet pulverizer to reduce the average particle size of -
the toner to the order of 15-20 microns.
,`~ .:~,
EXAMPLE II
Toner based solely on a polyester resin was prepared
by forming a blend of 100 parts be weight of "Spar II" resin
and 10 parts by weight of carbon black and processing the blend
~` as in Example I. "Spar II" is a polyester resin commercially -
s ~
~ available from Atlas Chemical Industries, Inc., of Wilmington,
'~ Delaware. This resin is the reaction product of Bisphenol-A,
i;~ ethylene oxide and fumaric acid, and has a molecular weig~t
of less than about 8000. The processed toner had an average
particle size of about 15 microns.
>
; ,, .
.~, . .
~':? : .
-12-
.',~~ . .
.;,~; . ~
.,.;~.. ~ .
. . .
; . . ..
.
1~6Z946
EXAMPLE III-V
Toner based on 50/50, 75/25 and 67/33 blends of
; polyamide to polyester resin were prepared by co-milling
varying amounts of the polyamide resin o~ Example I and the
polyester resin of Example II with lO, 5 and 5 parts respec-
tively of carbon black. The mixture was processed as in
Example l yielding toners having an average particle size
, in the order of about 15-20 microns~
! EXAMPLES VI-IX
$ Further samples of toner were prepared in the
i1 same manner as in the previous examples. The polyamide used
in these examples was "Emerez 1536" which has a softening point
.. .
f of about 105C., a Glass Transition temperature of 82-85C., a
peraent Elongation of about 20, a Tensile Stren~th of about
; 200 psi, and an average molecular weight within the range of
1800 to 2500. The polyester used is "Spar II", the same as
Examples II and III. The carbon black content was reduced from
i lO parts per hundred resin as in the previous examples to 5
'~ parts per hundred resin. In all cases, the average particle
size of the processed toner was in the range of l5 to 20
, microns. The resinous composition of ~he various toners is
as follows:
Example IV - 33 parts poLyamide, 67 parts polyester
Example V - 25 parts polyamide, 75 parts polyester
~ Example VI - 100% polyester
}~ Example VII - 100% polyamide
An electrostatographic developer material was pre-
pared by mixing each of the above toners at a 1% by weight
~, level with a carrier material comprising metal particles coated
,l with ethyl cellulose, said particles having an average particle
r
-13-
~,
., .
.. . . .
6~9~6
size of about 600 microns. Proper triboelectric charge was
obtained by tumbling the toner-carrier blend in a tin container
: ,
for 15 minutes.
Images were made on plain paper with each of the
above developer materials using a Xerox Corporation "Model D"
.,.1 ~, .
' electxostatographic machine~ A charged selenium plate was
,~j exposed to a light image on a NBS Resolution Test Chart (~PEG
7.011) standard test pattern, and the latent image was developed
using each of the developer compositions of Examples I through
VII. Each of the developed images were transferred to plain
bond paper and fixed by passing the paper through the nip of
;5, two steel spring biased rolls at a speed of about 400 inches, ,.j .
~ per minute. Results are shown in Table 1.
;1 TABLE I Roll
..,~
':r.? Carbon Blocking Pressure
Composition Black Temp.(l) (pli)(2)
~ Poly Amide 180 Parts18 Parts 140F 400
,ji Ex. 1
Polyester 180 Parts18 Parts 130F 400
;~ Ex. 2
Blend90 Parts Polyamide 18 Parts 140F 400
Ex. 390 Parts Polyester 200
Blend75 Parts Polyamide 5 Parts 130F 400
Ex. 425 Parts Polyester
Blend67 Parts Polyamide 5 Parts 130F 400
Ex. 533 Parts Polyester
~i Blend33 Parts Polyamide 5 Parts 130F 400
~' Ex. 667 Parts Polyester
Blend25 Parts Polyamide 5 Parts 130F 400
Ex. 775 Parts Polyester
Polyester 100 Parts 5 Parts 130F 400
Ex. 8
Poly Amide 100 Parts 5 Parts 130F --
~ Exo 9
,., :
~;~. -14-
i .......................................................... . .
.:, s
- . ,':
.. ...
` . ~06;~9~6
TABLE I (Cont'd) -
% Image
Pressure Density Image Retention (5~
- (3) (4) Before Fold After Fold
Poly Amide 34 .73 50% 0%
Ex. 1
Polyester 160 1.27 35% 5%
Ex. 2 ~ -
Blend 34 1.02 80% 30%
Ex. 3 36 .93 50% 25%
i~ .
Blend 34 1~10 ~0% 20%
Ex. 4
Blend 34 1.07 80% 20%
Ex. 5
Blend 34 1.42 75% 70%
Ex. 6
Blend 34 1.16 70% 20%
Ex. 7
Polyester 75 1.27 35% 0
Ex. 8
Poly Amide
(REVERSE IMAGE FORMED)
EXPLA~ATI0~
.,
1. The blocXing temperature of the toners was
determined using a Blue M isotemp oven. A 2-gram quantity of
the toner contained in an aluminum weighing dish was heated for
16-hour periods at an initial temperature of 110F and then at
temperatures raised in 10F increments. The blocking point was
recorded as being that temperature at w~ich a hard surface
crusting developed.
2. Toner evaluated for pressure fix were imaged on
standard 8 1/2" x 11" bond paper marketed by the Xerox Corpora~
tion. Fixing device consisted of two spring biased steel
pressure rolls having a diameter of 2~25 inches. ~prings con-
sist of four spiral springs having a spring constant of 1630
., .
.
-15-
..
,, . : , . : . :
106Z94G
pounds per inch. Pressure expressed in pounds per linear inch
(pli). Roll speed during fixation was 56 rpm.
3. % Pressure required to fix sample as compared to
pressure required to fix Xerox 813 brand toner as a standard
containing a styrene/methacrylate copolymer as the resinous
component to the same degree. Evaluated using a cotton swatch
test for comparative purposes. The "swatch`' test consists of
placing a 2 inch square cotton swatch on the top of the copy
sheet with a 500 gram balance weight on top of the swatch. The
weighted cloth is then drawn across the imaged area along the
11 inch length of the sheet. Using a set o~ standard made by
. .:.:
pressure fixing 813 toner at various pressures from 98 to 1170
pli, the images of the experimental toners were assessed for
degree of fix.
4. Image density was determined as an average of two
.' .
,~ readings on the capital alphabetic character "E" on a ~PEG -
7.011 standard test pattern using a General Analine and Film
Co. Micro-line Densitometer.
5. Image retention before folding was evaluated by
placing a strip of Scotch Magic Transparent Tape (~umber 810)
`~ on the imaged area and weighted with a 500 g balance weight
~ ~ for 5 second. The tape was then slowly peeled from the paper
;i at a uniform rate and angle. The image retained on the paper
was visually estimated. ~Samples evaluated after folding were
j- creased over a 10-mil shim and folded with a 2-kg balance
weight. T e fold was made on a heavy line image. A strip
; of Scotch Magic Transparent Tape Number 810 was placed on the
¦~ heavy line image and weighted with a 500-g balance weight for 5
seconds. The tape was then removed the same as in the unfolded
... .
~ t~st.
.;
~ra~ ~Ar~
-16-
, , , ':
` ~6;~946
,~ .
As can be seen from Table 1, the image retention ~. :
characteristic of the blends of this invention (Examples III-
VII) is considerably better than the image retention obtained
using solely a polyester or polyamide material as the resinous
toner component. Also, the percent pressure required to
properly fix a toner image based on the resin blends of
Examples III-VII is considerably less than what would be ex-
pected by a mere averaging of the pressures required to fix
the polyester toner or polyamide toner of Examples I, II, VII
or IX. In the case of Example IX, a reverse or negative image
was formed due primarily to the poor triboelectric properties
of the polyamide resin.
While the invention has been described with reference
to the embodiments disclosed herein, it is not confined to the
specific embodiments set forth, and this application is inten-
ded to encompass such operative modifications or changes as
may come within the scope of the following claims.
' ` '
~
'
`.
.~, ,.~ .
.,,.,~
,.. ~ . ,
~ "
;1,
~ 17-
.. ~
