Note: Descriptions are shown in the official language in which they were submitted.
~06Z532
~his invention relates to a combination of materials
suitable for producing fixed toner images and to a method for
the production of fixed toner images.
Electrophotography and electrography are well-known
imaging technigues wherein electrostatic charge patterns are
made visible with finely divided electrostatically attractable
material called "toner".
Historically, a one-component dry powder toner was first
used for developing electrostatic images. Other development
processes presently known as cascade, fur brush, powder cloud,
magnetic brush and liquid electrophoretic development were
introduced. A survey and description of these processes is
given e.g. by R.M. ~chaffert, ~he Focal Press, London and
~ew York (1965)~ In the same book a variety of electrophoto-
graphic, electrographic and magnetic printing processes using
toner development is described.
Many of the powdered toners used in xerography consist
primarily of fusible resins. When such toners are deposited
or transferred to a receptor paper sheet, the toner images
can be permanently fixed by heating or by applying a solvent
vapour, which partially dissolves the toner and causes it to
fuse into the paper.
Developers of the electrophoretic type initially com-
prised basically a simple dispersion of a pigment and no
binder was present. It was later proposed e.g. by Metcalfe
and Wright, Journal of Oil and Colour Chemists'Association,
GV.819 PCT - 1 -
~ 6Z53Z
39 (1956) pages 851-853, to use liquid developers incorporating
a resin. ~he resultant images are then made of so-called
"self-fixing" toners.
Electrophoretically formed toner images using a liquid
comprising dispersed toner particles are fixed by adhesion and
absorption into paper supports and usually do not reguire
additional fixing on said supports.
A problem of permanent adherence arises, however, when
electrophoretlcally deposited toner particles have to be
adhered to smooth non-porous supports e.g. resin, metal or
glass supports.
Even self-fixing toners are still not sufficiently per-
manently adhering to smooth surfaces and therefore the resul-
tant toner images have to be fixed by a subseguent procedure.
One use~ul procedure for subsequent fixing of toner images
is by the application of a lacquer overcoat. Various pro-
cedures have been suggested for applying such a lacquer over-
coat. In practice the lacquer is usually applied by spraying
a resin solution on the toner image. Another method has been
to apply the resin solution with an applicator roller.
~he applicator roller system has the disadvantage that
the resin solution is exposed to the air, which causes drying
of the solution.
The spraying technique requires a propellant gas or air
under pressure, which makes the apparatus rather sophisticated.
In addition thereto the spray nozzle is blocked when the
GV.819 E~ - 2 -
~Z532
apparatus is out of run.
Further it has been suggested that a transparent sheet
be laminated over the toner images. When carefully done the
protection of the image is excellent but the image is often
damaged during the application of the protective material.
From the United Kingdom Patent 1,149,265 a method for
fixing photoelectrophoretic toner images is known in which
the photo-electrophoretically formed particle image is embed-
ded in a thermo-adhesive layer while the thermo-adhesive
layer is in an adhesive state, and following the embedding
the thermo-adhesive layer is returned to its non-adhesive
state.
~he photoelectrophoretic toner particles are pigments that
are free from resin and have a fairly high melting point.
When the support of the toner image is a resin sheet or
fllm a strong heating in order to fix the toner image will
result in the shrinking or wrinkling of the support. ~his
is particularly disadvantageous in machine processing because
materials that are liable to shrink or wrinkle may yield
choking or jamming in the machine during their transport.
Because of their transparency thermoplastic resin supports
such as polyester resin supports are particularly useful in ob-
taining electrographic or electrophotographic transparencies.U~ng
such supports one should take care that in the heat-fixing of
the toner image the temperature be not surpassed at which
permanent deformation of the support occurs.
GV.819 PC~ - 3 -
~6Z53Z
It is an object of the presen-t invention to provide a
combination of materials suitable for producing by heating
fixed toner images on a thermoplastic resin support without
causing permanent deformation of said support.
It has been found that a particularly well fixed toner
image on a sheet or web material is obtained in a process
comprising the steps of image-wise depositing toner particles
on a thermo-adhesive fixing layer that itself is permanently
adhering to a support and heating the material carrying the
toner image to such a degree that softening of the thermo-
adhesive fixing layer takes place without reaching a
temperature at which permanent deformation of the support
occurs, characterized thereby,that the support is a
thermoplastic resin support whose glass transition temperature
is higher than the glass transition temperature of the thermo-
plastic polymer or polymer composition of the thermo-adhesive
layer, and the toner particles comprise at least 10 % by
weight of a polymer or polymer composition whose glass
transition temperature is at least 10C higher than that of
the thermoplastic polymer or polymer composition of the
thermo-adhesive fixing layer.
~ he definition of "glass transition temperature" (Tg)
and practical tests for its determination are given e.g. by D.H.
Solomon in ~he Chemistry of Organic Film Formers, John Wiley &
Sons, Inc. New York (1967) p.26-27 a~d by F.W. Billmeyer, Jr.
in the ~extbook of Polymer Chemistry (1957) p.40-44. ~he
specific ~g valuesm~ntioned in the present description are
GV.819 PC~ _ 4 _
1062532
measured by constan-t heating stream thermal analysis (see E.
~teffens, J.Appl.Pol.Sci., 12, 2317-2324 (1968).
'~he '~g of a polymer is related to its chemical composition,
molecular weight,crystallinity, and degree of cross-linking.
The glass transition temperature of a copolymer is inter-
mediate between those of the two homopolymers.
An alternative method of modifying the Tg is to add a low
molecular weight compound as a plasticizer for the polymer.
'~herefore, when speaking of "thermoplastic polymer or polymer
composition" such wording includes according to the present in-
vention a mixture of a thermoplastic polymer or of a polymer
composition comprising (a) plasticizing agent(s) that modifies
or modify the 'lg of the polymer or polymer compositions for
the toner fixing purposes of the present invention.
According to a preferred embodiment of the present invention
the '~g of the polymer or polymer composition of the thermo-
adhesive fixing layer is at least 30C and preferably below
60C and the 'lg of the resin support at least 60C e.g.
between 60 and 85C.
'~he polymer(s) of the thermo-adhesive fixing layer and the
polymer(s) of the toner have not to be compatible,in other
words have not to form a solid solution after melting together.
'~he thickness of the thermo-adhesive layer is not critical
and can be adapted according to the desired result. Preferably,
however, the thickness is in the range of 2 to 20 ~m.
The thermo-adhesive fixing layer for use according to the
present invention preferably comprises one of the polymers
GV.819 PC'l - 5 -
~062532
listed with their ~g in the following ~able 1.
~able 1 ~ ~ C
B 1. PICCOLAS~IC A 75 (trade name of Pennsylvania Ind. 33
Chem.Corp., Clairton, Penn. U.S.A. for a
plasticized polystyrene)
2. PICCOVAR ~ 60 (trade name of Pennsylvania Ind.Chem. 32
Corp., Clairton, Penn. U.S.A. for an alkyl-
aromatic polymer)
3. LEMAC 541-10 (trade name of Borden Comp., New York, 38
N.Y. U.S.A. for a copo]ymer of vinyl acetate and
crotonic acid having the following structure :
2 ~
co L COOH J
CH3
_ x
x : 96.3 % by weight
y : 3.7 % by weight
4. NEOCRYL~ 707 (trade name of Polyvinyl Chemie 30
Holland, Waalwijk, Netherlands for a copolymer
of vinyltoluene-isobutyl methacrylate-acrylic
acid-stearate having the following structure :
~ E12-CE~ ~ E2 ~ H2-CE - ~ tearat
L CH3J OEI3 1 OOE
n = 70-75 % by weight
m = 21 % by weight
p = 0.3 % by weight
q = 5 to 10 % by weight
t~le ~k
GV.819 PC~ - 6 -
~ ~;Z53Z
5. CVP E 041 (trade name of Cray Valley Prod/Ltd., ~5
3L3 St.Mary, Orpington, Kent, U.K. for a copolymer
of styrene-vinyl acetate-ethyl acrylate-acrylic
acid and having the following structure :
CH2-CH ~ FH2-cH -~ h LCH2-CH-- ~ H2 CH
L ~ ~ O-CO-CH3~ L cooc2H5~ L COOH ~
x = 30 % by weight
y = 25 % by weight
z = 44 % by weight
m = 1 yo by weight
6. ACRONAL 500 L (trade name of BASF - Ludwigshafen, 24
W.Germany for a 55 % by weight solution of poly-
acrylate containing a plasticizing agent)
7. I ~ SGA (trade name of SO~VAY-Belgium for a 47
copolymer of vinyl chloride-vinylidene chloride-
maleic acid-maleic anhydride acrylonitrile)having
the following structure :
~2-~C~2~8_o~ c~2c~j
Cl m Cl Cl n P CO CN x
OH H q
20m = 58 % by weight
n = 39 % by weight
~p = 1 % by weight
q = 1 % by weight
x = 1 % by weight
8. ~LIO~I~ ~S5E (trade name of Goodyear - U.S.A., The 36
Goodyear ~ire and Rubber Comp. Akron, Ohio, USA
for a copolymer of butadiene-styrene)
~2-c~=c~-c~2~ff~2-~ t
~ t~ldQ ~ k
GV.819 PCT _ 7 -
~6Z532
x _ 15 % by weight
y = 85 % by weight
9. PO~YSTYROL-B (trade name of BASF, ~udwigshafen,
W.Germany for a copolymer of styrene and butyl
acrylate) 56
10.E~VACIT ~2046 (trade name of E.I. du Pont de 42
Nemours & Co. (Inc.) Wilmington, Del., U.S.A. for
a n-butyl methacrylate-isobutyl methacrylate
having the followi~ structure :
CH3 CH3
_--CH2-C . --CX2-C-
C=O \
(C 2)3 x _ H3C CH3 _ Y
x = 50 % by weight
y = 50 % by weight
11.A copolymer of acrylic acid-glycidyl
methacrylate having the following structure : 36
2 ~ ~ CX3 _ _
l COOH~ 2
I ~0 Y
x = 5 % by weight
y = 95 % by weight
The toner particles may be of the type used in "dry"
development, which includes developing techniques known as
t~ r~k~
GV.819 ECT - 8 -
106Z532
powder cascade, powder cloud, free brush and magnetic brush
development. Suitable thermo~Lastic resin constituents for
the production of toner particles applied in dry development
e.g. powder cloud development are e.g. a polymer or polymer
mixtures including homo- and copolymer of methacrylic acid
esters, e.g. poly(methyl methacrylate) ~g: 105C, and poly
(ethyl methacrylate ) q~g: 65C, poly(styrene) lg: 100C and/
or poly~inyl butyral ~g: 49 C,optionally in ad~nixture with
acrylic acid esters having a lower ~g value e.g. poly(methyl
acrylate) q~g: 8C.
A preferred toner is described in the ~rench Patent
2,120,948 filed December 27, '1971 by the Applicant. According
to said patent the toner consists essentially of finely
divided particles formed of a generally uniform mixture
comprising 5 to 15% by wei~ht of a coloured material and
95 to 85 % by weight of resin mixture consisting essentially of
(A) 40 to 60 % by weight of a polymer having at least 50 %
of the recurring units thereof constituted by at least
one styrene monomer of the formula:
R
R-CzCH
~,
~IJ R
wherein R is hydrogen or methyl, and the balance of such
recurring units derived from at least one alkyl meth-
acrylate monomer wherein alkyl comprises 1-4 carbon atoms,
GV.819 PCl - 9 -
~06Z532
(B) 20 to 40 % by weight of a homopolymer of butyl acrylate or
butyl methacrylate, or copolymers thereof with up to 80 %
by weight of methyl acrylate or methyl methacrylate, and
(C) 5 to 20 % by weight of a polymeric plasticizer selected
from polyvinylbutyral, polyethylene and co(vinyl acetate/
ethylene).
Said electrostatic toner material consists of particles
having a diameter between 1 and 30 ~m.
The Tg values of said electrostatic toner material are in
the range of 40 to 60 C
The toner particles may likewise beof the "wet" electro-
phoretic type incorporating a resin or resin mixture.
The preparation and composition of such toner particles
suitable for use in electrophoretic development and fixing
according to the present invention is described e.g. in the
United Kingdom Patents 1,151,141 filed February 4, 1966 by
Gevaert-Agfa N.V. and 1,312,776 filed July 25, 1969 by the
Applicant and in the published German Patent Applications
(DOS) P 2,334,353 filed July 6, 1973 and P 2,333,850 filed
July 3, 1973 both by Agfa-Gevaert A.G. Normally the electro-
phoretic toner consists essentially of finely divided resin-
coated pigment particles dispersed in an insulating liquid
having a dielectric constant of not more than 3.
Particularly useful toners for electrophoretic development and
fixing according to the present invention contain a polymer
essentially consisting of methacrylic acid esters. The
pigment or colouring agent contained in the toner particles
GV.819 PCT - 10 -
106Z53Z
may be any of the pigments or dyestuffs commonly employed
for that purpose.
The resin support of the thermo-adhesive fixing layer
when being transparent may be made e.g. of cellulose nitrate,
cellulose ester e.g. cellulose triacetate, cellulose acetate
butyrate, polyvinylacetal, polystyrene,polymethacrylic acid
esters or highly polymeric linear polyesters e.g. polyethylene
terephthalate having in amorphous and crystalline state a
glasstransition temperature of 67 and 81C respectively
(see V.V. Korshak and S.V. Vinogradova in "Polyesters"
Pergamon Press N.Y. (1945) p.339.
~ hese supports being highly transparent for visible light
allow the inspection of the toner image with light projected
through the image-containing material e.g. on a light-table
or in a transparency projector (slide projector).
Preferred are the polyethylene terephthalate supports
because of their moisture resistance and high mechanical
strength obtained e.g. by stretching.
Particularly strong adherence of the thermo-adhesive
layer to the resin support is obtained when the hydrophobic
resin support,preferably a polyethylene terephthalate support,
is subbed with a layer, which is directly adherent to the said
hydrophobic film support and substantially consists of a
copolymer formed from 45 to 99.5 % by weight of at least one
of the chlorine-containing monomers vinylidene chloride and
vinyl chloride, from 0~5 to 10 % by weight of at least an
ethylenically unsaturated hydrophilic monomer, and from 0 to
GV.819 PCT - 11 -
106Z53Z
54.5 % by weight of at least one other copolymerisable
ethylenically unsaturated monomer.
~ he vinylidene chloride copolymer may be formed from
vinylidene chloride and/or vinyl chloride and hydrophilic
monomeric units alone in the ratio indicated above. Preférably
up to 54.5 % by weight of other recurring units, for instance
acrylamides, methacrylamides, acrylic acid esters, methacrylic
acid esters, maleic esters and/or N-alkylmaleimides, may also
be present.
10Suitable vinylidene chloride copolymers are e.g.:
the copolymer of vinylidene chloride, N-t-butylacrylamide,
n-butyl acrylate, and N-vinylpyrrolidone (70:23:3:4),
the copolymer of vin~lidene chloride, N-t-butylacrylamide,
n-butyl acrylate, and itaconic acid (70:21:5:2),
the copolymer of vinylidene chloride, N-t-butylacrylamide,
and itaconic acid (88:10:2),
the copolymer of vinylidene chloride, n-butylmaleimide, and
itaconic acid (90:8:2),
the copolymer of vinyl chloride, vinylidene chloride, and
20methacrylic acid (65:30:5),
the copolymer of vinylidene chloride, vinyl chloride, and
itaconic acid (70:26:4),
the copolymer of vinyl chloride, n-butyl acrylate, and
itaconic acid (66:30:4),
the copolymer of vlnylidene chloride, n-butyl acrylate, and
itaconic acid (80:18:2),
-the copolymer of vinylidene chloride, meth;yl acrvlate, and
GV.819 PCT - 12
106Z53Z
itaconic acid (90:8:2),
the copolymer of vinyl chloride, vinylidene chloride, N-t-
butylacrylamide, and itaconic acid (50:30:18:2).
All the ratios given between brackets in the above-
mentioned copolymers are ratios by weight.
~ he above copolymers are only examples of the combinations,
which can be made with the different monomers.
~ he different monomers indicated above may be copolymerised
according to varioùs methods. ~or example, the copolymeri-
sation may be conducted in aqueous dispersion containing a
catalyst and an act;vator. Alternativelyj polymerisation of
the monomeric components may occur in bulk without added
diluent, or the monomers are allowed to react in appropriate
organic solvent reaction media.
~he vi ~ lidene chloride copolymers may be coated on the
hydrophobic film base according to any suitable technique, e~g.,
by dip-coating or immersion of the surfaces of the film into
a solution of the coating material. Theymay also be applied
by spray, brush, roller, doctor blade, air brush, or wiping
techniques. ~he thickness of the dried layer may vary between
0.3 and 3 lum preferably.
D ~
D Various wetting or dispersing agents e.g. UL~RAVO~ (trade
name) and/or HOS~APO ~(trade name) may be used when the
vinylidene chloride copolymer layer is applied from an agueous
dispersion. These dispersions are obtained directly when the
copolymer has been made by an emulsion polymerisation process.
When coating aqueous dispersions of vnylidene chloride copolymer
k
. 81 9-ePC~ - 13
106Z532
on a polyethylene terephthalate film support a very strong
adherence to the support is obtained when said dispersions are
applied before or during stretching of the polyethylene tere-
phthalate film. The aqueous dispersion may be applied to at
least one side of the non-stretched film, but may also be
applied to polyethylene terephthalate film, ~ich has been
oriented biaxially. ~he vinylidene chloride copolymer layer
may also be coated on at least one side of a polyester film,
which has been stretched in only one direction, e.g. longi-
tudinally, whereafter the subbed polyester film is stretchedin a direction perpendicular thereto, in this case transvers-
all~.
~ he thickness of the subbing layer is already sufficient
from about 0.3 ~m.
~ he preparation of said vinylidene chloride copolymers
suited for said subbing layer is described e.g. in the United
Kingdom Patent 1,234,755 filed September 28, 1967 by the
Applicant.
A subbing layer polymer prepared according to the following
preparation receipt yields particularly good adherence to the
polyethylene terephthalate support and to the thermo-adhesive
layer applied for fixing a toner image according to the
present invention.
- Preparation of a copolymer of vinylidene chloride, vinyl
chloride, n-butyl acrylate and itaconic acid (30:50:18:2 by
weight).
GV.819 PC~ - 14 -
-
106253Z
In an autoclave were placed 1650 ml of water and 9.6 g of
itaconic acid. After dissolution a solution of 6 g of sodium
hydrogen carbonate in 120 ml of water was added. Subsequently
98 ml of a 10 % aqueous solution of the disodium salt of
disulphonated dodecyl diphenyl ether and 49 ml of a 10 %
agueous solution of the sodium salt of sulphonated dodecylben-
zene were added as emulsifying agents. ~hen 96 g of n-butyl
acrylate, 144 g of vinylidene chloride, 9.8 g of ammonium
persulphate, and 4.9 g of potassium metabisulphite were
added. The autoclave was sealed and stirring started.
Under nitrogen pressure 240 g of vinyl chloride were pressed
into the autoclave, which was then heated to50C, while
stirring. When this temperature had been reached, stirring
was continlled for 15 to 30 min. The temperature of the latex
rose to about 65C. The reaction was contimled for about 3 h
whereupon the latex was cooled to room temperature. The pH
thereof amounted to 2.6 and was brought to 6 by means of 100 ml
of 1~ agueous sodium hydroxide. The latex was readily
filtrable and consisted of the copolymer of vinylidene chloride,
vinyl chloride, n-butyl acrylate, and itaconic acid (30:50:18:2)
in a concentration of 20 %.
In "indirect" electrophotography the toner image is formed
on a photoconductive recording member e.g. selenium_coated
drum and transferred to a receiving material e.g. plain paper
or transparent resin sheet. The transparent resin sheet for
use in "indirect" electrophotography is according to the
GV.819 PCT - 15 -
~06Z532
present invention coated with the described thermo-adhesive
fixing layer.
In electrographic systems, an electrostatic charge
pattern is produced by in~ormation-wise applying electric
charge carriers e.g. electro~sand/or ions to an electrically
insulating surface. For example in electrography an electro-
static charge pattern is built up by image-wise modulated
corona-charging, information-wise modulated charge deposition
with a conductor e.g. a conductive stylus or pin-matrix or
with an information-wise modulated electron beam.
A survey of electrographic recording techniques is given
by R.M. Schaffert in the already above mentioned book.
A special type of producing electrostatic charge patterns
is based on photo-emission of charged particles.
Processes in which the electrostatic image formation is
based on photo~electron emission are described e.g. in the
United States Patents 2,221,776 of Chester F.Carlson issued
November 19, 1940, 2,692,948 of Kurt S.~ion issued October
26, 1954, 2,900,515 of Eduard ~.Criscuolo and Donald ~.O'Conner
issued August 18, 1959, 3,057,997 of Edward E.Eaprelian
issued October 9, 1962 and 3,526,767 of Walter Roth and Alex
F.Jvirblis issued September 1, 1970 and the United Kingdom
Patent 778,330 filed April 15, 1955 by Compagnie Fran~aise
Ihomson-Houston, the German Patent 1,497,093 filed ~ovember
11, 1962 by Siemens A.G., and the published German Patent
Applications 2,231,954 filed June 29, 1972 and 2,233,538
filed July 7, 1972 both by Diagnostic Instruments. Except
GV.819 PC~ - 16 -
106Z53Z
for the processes described in the latter three patents
the photoelectron emission proceeds with a solid photocathode.
A particularly interesting recording technique is known
as ionography in which the formation of the electrostatic
charge pattern proceeds through the information-wise ionization
of photo-ionizable gas e.g. as described in the Belgian
Patent 792,334 filed December 6, 1972 by Xonics Inc.
According to the radiographic process described in said
Belgian Patent an electrostatic charge pattern is formed on a
dielectric sheet in an imaging chamber, which comprises between
electrodes an interspace filled with a gas having an atomic
number of at least 36, e.g. xenon, that is kept at a pressure
above atmospheric pressure. During the image-wise X-ra~
exposure a potential difference is applied between the
electrodes and electrons and positive ions formed in said
interspace are attracted and moved towards the anode and
cathode respectively whereby a charge pattern is formed with
one of the types of charged particles on said dielectric
sheet.
~he recording materials applied in X-ray recording are
preferably transparent for visible light so that smooth resin
films or sheets, which give rise to the above explained problem
with regard to toner adherence, are normally used. ~he combin-
ation of thermo-adhesive fixing la~er and toner having the
characteristics specified in the present description is of
particular interesting advantage in the use of said trans-
parent filn~or sheets.
GV.819 PC~ - 17 -
1062532
~he recording of a charge pattern by photo-emission or
ionographic techniques asks for an insulating charge-reeeiving
thermo-adhesive layer that retains the applied eharge for a
sufficiently long time to enable the toner development of the
charge pattern to take place.
In order to prevent -that the deposited charge pattern
after its deposition fades, the rear side of the charge-
receiving material is provided with a transparent electrically
eonductive layer that makes contact with an electrode of
opposite eharge sign with respect to the deposited charge
pattern.
In order to offer a good adherenee of the eonduetive layer
to the transparent hydrophobic resin support a subbing layer of
the above deseribed type is used. Suitable eonduetive layers
B are on the basis of polyionic resins, for example CALGON ~
aONDUC~IVE PO~YMER 261 (trade name) containing 39.1 % by weight
of active conductive solids, whieh contain a conductive poly-
mer having reeurring units of the following type :
H3C~+,CH3
H2C CH2 .Cl
- HC CH-CH2
H2
and the polyionic resins deseribed in the United Kingdom
Patent 1,301,661 filed January 29, 1969 ~y the Applieant or
in the published German Patent Applieations (DOS~ P 23 01 266
filed January 11, 1973 and P 23 26 413 filed May 24, 1973
both by Agfa-Gevaert A.G.
~ trade r~k
GV.819 PC~ - 18 -
106253Z
Other conductive coatings are e.g. vapour-deposited films
of chromium or nickel-chromium about 3.5 llm thick and being
transparent for about 65 to 70 % in the visible range.
Copper(I) iodide conducting films or sheets can be made by
vacuum depositing copper on a relatively thick resin base and
subsequently treating with iodine vapour under controlled
conditions (see J.Electrochem.Soc., 110-119, Feb. 1963). Such
films are over 90 % transparent and have surface resistivities
as low as 1500 ohms per square.
~he heating of the thermo-adhesive layer for fixing the
toner image may proceed by infrared irradiation as described
e.g. in the United ~tates Patent ~,772,497 of Donald R.Gray
and Richard W.Germuska issued ~ovember 1~, 197~ or by contact
of the support of the thermo-adhesive layer with a hot body.
~he present invention is illustrated by the following
examples without, however, limiting it thereto.
Exam~le
To one side of a longitudinally stretched polyethylene
terephthalate film of 0.8 mm thickness a subbing layer was
applied at 25C at a coverage of 50 mg/sq.m from a latex con-
taining 5% by weight of the copolymer of vinylidene chloride,
vinyl chloride, n-butyl acrylate and itaconic acid
(30:50:18:2 by weight), the preparation of which has been
described hereinbefore.
lhis subbed film was simultaneously stretched longitu-
dinally and transversally to about 3.5 times its original
size and heat-setted. lhe lg of the polyethylene terephtha-
GV.819 PC~ - 19 -
106Z532
la-te was 75C.
~ o the subbed film a thermo-adhesive fixing layer was
applied by coating it at 25C at a coverage of 70 g per sq.m
with a 10% (weight/volume) NEOCRY~ B 707 (trade name3 polymer
(lg=30C) solution in a 3/1 by volume mixture of dichloro-
ethane and methylene chloride.
~ he dried film was electrostatically charged at the side
of the thermo-adhesive layer with a negative corona whose
ion stream was directed through image-wise distributed aper-
tures in a copper plate while the rear side of the filmduring the charging was held in contact with a copper plate
as counter electrode.
~ he corona charge was of such an intensity that the
average voltage of the charge applied to the subbed layer
was -1000 V.
~ he charge pattern was developed according to the powder
cloud technique (see United States Patent 2,725,304 of Richard
B.Landrigan, Ray ~.Tom and Donald L.Fauser issued November 29,
1955) with toner particles prepared by mixing 5.2 parts
by weight of polystyrene having a molecular weight of approxi-
mately 30,000 and 1 part by weight of polyvinylbutyral
having a molecular weight of approximately 30,000, which
in addition to the vinylbutyral groups contains also approxi-
mately 20% by weight of vinyl alcohol groups and 2.5 %
by weight of vinyl acetate groups, 2.8 parts by weight of
copoly(methyl methacrylate/n-butyl methacrylate)(50:50 mole
% with an intrinsic viscosity of 0.2 measured in chloroform
GV.819 PC~ - 20 -
~06Z532
~ at 20C) and ~ part by weight of Spezialschwarz IV~ trade
- name for carbon black sold by Deutsche Gold- und Silberscheide-
anstalt, Frankfurt a/M, W.Germany).
~ he components were mixed in dry condition and then melted
at 150-160C. ~he melt was then kneaded for approximately
30 min at the same temperature. After cooling and breaking
to a particle size of approximately 1 mm the powder was
ground in aqueous medium in a vibration ball mill for 30 h.
After drying and sievi~g a toner having a particle size of
4 ~m was obtained. Ihe lg value of this toner was 42C.
lhe transparent recording material carrying the non-fixed
toner image on the thermo-adhesive fixing layer was introduced
into a drying oven whose temperature was kept at 1~0C.
At that temperature the fixing of a toner image on a poly-
ethylene teréphthalate film sheet having no thermo-adhesive
fixing layer did not proceed within a period of 30 s.
On the film sheet provided with the thermo-adhesive
fixing layer the toner image was fixed already at 120C within
15 s. ~he resistance to abrasion of the fixed toner image
was very good.
Ihe thermoadhesive layer did not show fingerprints when
manipulated below 40C.
Example 2
200 g of S~AYBELI~E ES~ER 10 (registered trade name
of ~he Hercules Powder Company Inc., Wilmington, Del., U.S.A.
for a glycerin ester of hydrogenated wood rosin with acid
number 8) and 100 g of HELIOECH~ BLAU H ~(trade name of Bayer
G ~ 8~ PC~ ~ - 21 -
106Z53Z
AG, Leverkusen, W.Germany) were mixed at 60-65C in a mixing
and kneading apparàtus of Meili, Switserland, type ~iliput
030 ~.N. ~he kneaded mass was cooled and ground in a grinding
apparatus I.K.A., model A10 (of Janke & Kunkel, W.Germany)
to obtain a fine powder of resin-coated pigment.
In a ball-mill 2 g of the above resin-coated pigment
powder were ground for 10 h together with:
- 11.5 g of a 25 % by weight solution of ~EOCRYL B 702 (trade
name of Polyvinylchemie, ~he Netherlands for a copolymer
of butyl methacrylate and stearyl methacrylate comprising
about 1 % by weight of methacrylic acid in ISOPAR G (trade
name of Esso Standard Oil Company for an aliphatic hydro-
carbon solvent having a boiling range of 160-175C and a
Kauri-Butanol value of 27,
- 0.5 g of a 25 % by weight solution of ANlARON~$216 (trade
name of General Aniline & ~ilm Corporation, ~ew York, ~.Y.,
USA) in ISOPAR G (trade name)
- 2 ml of a 0.2 % (g/100 ml solution in ISOPAR G (trade name)
of the zinc salt of mono-2-butyloctyl phosphate,
- 25 ml of ISOPAR G (trade name)
When 10 ml of the above concentrated liquid developing
composition were diluted with 1 litre of ISOPAR G (trade name)
a stable positive-working electrostatographic liquid developer
was formed suited for the development of a latent electrostatic
image formed on a conventional electrophotographic recording
element comprising paper coated with photoconductive zinc
oxide in a resinous binder by negative charging and image-
a ~
GV.819 P~ - 22 -
106253Z
wise exposure to light.
The Tg value of the resin coating of the toner particles
was above 200C.
~ he obtained developer was used for the development of
a charge pattern formed according to the technique of
Example 1 on a transparent material, which was different from
the material of Example 1 in the composition of the thermo-
adhesive fixing layer.
The fixing layer was prepared by dissolving 2.5 g of the
vinyl acetate-crotonic acid copolymer (Tg=38C) (compound 3
of Table 1) ir. a solvent mixture of 27 ml of sym.dichloroethane
and 8 ml of methylene chloride.
The solution was coated on the subbed polyethylene
terephthalate film of Example 1 at such a coverage that the
weight of the dried coating obtained was 4 g per sq.m~
On the film sheet provided with the thermo-a&esive
fixing layer the toner image was fixed already at 120C
within 15 s.
The resistance to abrasion of the fixed toner image
was very good.
GV.819 PCT - 23 -
