Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
2 1. Fie1d of the Invention
3 The present invention relates to a composite
4 electrosensitive transfer material, and more particu-
larly, to a reusable electrosensitive transfer film.
6 2. Description of the Prior Art
7 In recent years, various systems have been
8 proposed for the rapid transmission and/or recording of
g information. One such system is an electric discharge
recording system.
11 The electric discharge recording system is a
12 process which comprises applying an electrical signal OL
13 several hundred volts and several watts in the form of
14 an electric voltage, and breaking a semiconductive
recording layer on the surface of a recording layer by
16 electric discharge, thereby to form an image on the
17 recording layer or on a substrate superimposed on the
18 recording layer. This process is a "direct imaging"
19 process which does not require processing operations
such as development and fixation, and is in widespread
21 use as a simple recording process. For example, the
22 process finds applications in facsimile systems, various
23 measuring instruments, recording meters, record displays
24 in computers, and processing of electrostencil master
sheets
26 In the electric discharge recording, a dis-
27 charge recording stylus is directly contacted with the
28 recording surface of an electric discharge recording
29 material. Discharging is performed through the stylus
to break the recording layer, and to form an image on
31 the recording surface.
~,
1 A more recent development is disclosed by
2 Nakano et al in U.S. Patent 4,163,075 and relates to the
3 use of an electrosensitive transfer film. To record
4 with this type of film it is laid over an untreated
sheet of a receiving medium, such as paper, and an
6 electric discharge stylus is moved in a regular pattern
7 across the back of the transfer film. Provision is
8 generally made to ground either one edge or the front
g surface of the transfer film. When a voltage on the
order of 150 to 200 volts is applied to the stylus,
11 current flows through the sheet and matter is caused to
12 be transferred to the receiving sheet, e.g., paper.
13 The film disclosed by Nakano et al in U.S.
14 Patent 4,163,075, comprises three layers, namely a film
support layer and two transfer layers. The support
16 layer is composed of a metal powder-containing resin
17 layer, eOg., electrolytic copper powder having an
18 average diameter of 2 microns dispersed in a vinyl
19 chloride resin.
Numerous disadvantages appear to exist with
21 the use of the products disclosed in the Nakano et al
22 patent. For example, the use of small metal particles
23 in the support layer results in a high cost product
24 affecting the commercial success of the product. A
need therefore exists for a transfer sheet exhibiting
26 improved image quality that can be produced at a low
27 cost compared to other commercially available products~
28 SUMMARY OF THE INVENTION
29 It is an object of this invention to provide
an electric discharge transfer film which is free from
31 the disadvantages described hereinabove.
1 According to the present invention, an elec-
2 tric discharge recording material is provided which
3 comprises (a) an electrically anisotropic support
4 layer having electroconductive particles dispersed in a
resin matrix wherein said electroconductive particles
6 are: (1) graphite particles having a particle size
7 between 0.1 to 20 microns, (2) carbon black particles
8 having a particle size between 25 to 500 millimicrons,
g or (3) metal powders; and (b) at least one thermal or
electrothermal transfer layer in the form of a resin
11 layer capable of being broken by electrical discharge
12 and transferred to a record sheet. A preferred resin
13 matrix comprises a phenoxy resin of the formula:
O = C ~ ~ O-C-C C
16 CH3 H H H
17 _ _ n
18 where n is about 100.
19 One embodiment of the present invention is an
electric discharge recording material which comprises:
21 (a) a semiconductive resin layer capable of being
22 broken by electric discharging which has a surface
23 resistance of 105 to 1016 ohms and a volume resistance
24 of 103 to 1014 ohms-cm; (b) an electroconductive elec-
trically anisotropic resin layer containing electro-
26 conductive particles such as graphite, carbon black or
27 metal powders as described above, which is laminated on
28 one surface of the semiconductive resin layer (a); and
29 a conductive layer having a surface resistance of not
more than 104 ohms and a volume resistance of not more
31 than 102 ohms-cm, which is laminated on the other
32 surface of the semiconductive resin layer (a).
1 Another embodiment of the present invention is
2 an electric discharge recording material which comprises
3 at least one resin layer capable of being thermally or
4 electrothermally transferable to another substrate, and
an electrically anisotropic carbon black or graphite-
h containing resin layer which is laminated on one surface
7 of one resin layer.
8 Still another embodiment of the present
g invention is an electric discharge recording material,
e.g., film, which comprises at least one resin layer
11 capable of being thermally or electrothermally trans-
12 ferred to another substrate and an electrically aniso-
13 tropic carbon black or graphite-containing support
14 layer. The graphite and carbon black particles exhibit
particle sizes previously defined herein. The support
16 layer is laminated onto one surface of the resin layerO
17 Other objects, features and effects of this
18 invention will become more apparent from the following
19 detailed description considered with the drawings
wherein:
21 Figure 1 is an expanded sectional view of the
22 transfer film of this invention.
23 DETAILED DESCRIPTION OF THE INVENTION
24 The film structure, as illustrated in FIGURE
1, comprises an electrically anisotropic (unidirection-
26 ally conductive) electroconductive particle-support
27 layer 2 and two transfer layers, namely layers 4 and 6.
28 When a graphite-containing resin is employed
29 as layer 2, it generally contains between 5 to 65% and
preferably between 15 to 45% by weight graphite based
1 on the weight of the resin. Best results are obtained
2 when the layer contains between 25 and 35~ by weight
3 graphite, based on the weight of the resin. The par-
4 ticle diameter of the graphite used in this layer
is also critical to the successful practice of the
~ subject invention. Generally, the particle size is
7 generally between 0.1 to 20 microns, and preferably
8 between 0.1-5 microns, with best results being achieved
g with particles between 0.1 and 1 microns.
According to an embodiment of this invention,
11 graphite particles useful in the anisotropic support
12 layer can be prepared by grinding the graphite particles
13 in the presence of water or other solvent having sub-
14 stantially the same freezing and vapor pressure proper-
ties as water, e.g., tertiary butyl alcohol, cyclohexane,
16 benzene, dioxane, and para-xylene. Generally~ between
17 about 70 and 80% by weight of the slurry is water or
18 solvent, as defined herein, the balance being solids,
19 namely the graphite particles. It is understood
that the amount of water or solvent employed is not
21 critical and can vary over wide ranges both below 70%
22 and above 80% because the solvent or water is eventually
23 driven off in accordance with this process. Grinding
2~ takes place for a period of time sufficient to achieve
substantially complete dispersion of the graphite
26 particles in the solvent or water. Generally, such
27 grinding takes place between 8 and 16 hours to achieve
28 the substantial dispersion of the graphite particles.
29 The term "substantial", as used in this context, means
at least 95% of the graphite being dispersed in the
31 water or solvent with as little as possible agglomeri-
32 zation of the graphite being present. Grinding is
33 generally accomplished by subjecting the slurry to a
34 ball mill, sand mill or any other clispersion technique
well~known to those of ordinary skill in the art. It
-- 6
is particularly preferred -to reduce agglomera-tes of
graphite and to obtain substantial dispersion of the
graphite particles with an "ATTRITOR" , Model 01,
made by Union Process Company, Dayton, Ohio.
A binding polymer is added to the graphite
slurry, either during the grinding step or immediately
after the grinding step for the purpose of forming a
film or coating on the individual particles of graphite.
The polymer employed is to be soluble in the water or
solvent of the slurry. Suitable polymers include, e.g.,
polyvinyl alcohol, gelatin or methyl cellulose.
Freezing of the slurry is achieved by lower-
ing the temperature to a point wherein the physical
state of the solvent changes from liquid to solid.
The frozen slurry is then dried, under conditions
such that the water solvent present is caused to
sublime, i.e., the solid is directly converted to
the vapor form, without passage through the liquid
state. The process results in the formation of a sub-
stantial amount of undamaged polymeric coated graphite
particles having a diameter of at least 0.2 microns.
By substantial amount, it is intended that a-t least
90% of the particles have a diameter of at least
0.2 microns.
Sublimation of water, or other solvents used
in place of wa-ter, which exists in the solid s-tate,
can be caused to change to a gaseous phase without an
intermediate phase, under well-known changes in pres-
sure alone, tempera-ture alone, or a change in both
temperature and pressure. Generally, sublimation can
be produced under the influence of a high-pressure
vacuum.
It is critical that the graphite particles be
dispersed in the resin in such a manner the graphi-te is
~D~Z~
not reduced in size to dust particles (under 0.1 micron).
Graphite particles are therefore dispersed in a resin,
generally in a mol-ten state, by means of a high sheer
blender, e.g., a Waring blender, Cowl or Greer blenders,
rather than by impact grinding methods, e.g., ball
milling or dispersing in an attritor. The latter
methods cause the graphite particles to greak up into
particles less than 0.1 micron size, adversely affect-
ing the electrically anisotropic properties of the
layer.
When the electroconductive particles are
carbon black particles, the electrically conductive
carbon-black-containing resin of layer 2 contains
generally between 60 to 70% by weight carbon black.
Best results are obtained when the layer contains 65%
by weight carbon black, based on the weight of the
resin and carbon black. The particle diameter of the
carbon black used in this layer is also eritieal to the
successful practice of the subject invention. Gener-
ally, the partiele size is generally between 25 and500 millimierons, with best results being aehieved
with partieles of about 350 millimierons.
Carbon blaek is available from numerous
commercial sources. For the present invention, channel
blacks, ~urnace blacks, and thermal blacks are useful
in the practice of the invention. Examples of suit-
able earbon blaeks inelude those sold under the mark
T~RMAXTM
The resin whieh eonstitutes the resin matrix
in whieh the elec-troeonduetive partieles of the aniso-
tropie layer are dispersed may be any thermoplastic or
thermosetting resin whieh has film-forming ability and
eleetrieal insulation (generally having a volume resis-
tanee of at least 107 ohms-em). Generally, the matrix
resin preferably has a great ability to bind the elec-
tro-conductive particle and can be formed into sheets or
films having high mechanical strength, flexibility and
high stiffness.
A preferred resin that is useful in the resin
matrix, in which the electro-conductive particles are
dispersed, is a phenoxy resin of the formula:
{ O \ ~ C ~ O-C-C-C n
wherein n is about 100.
A suitable phenoxy resin is sold by Union
Carbide Corporation under the trademark "PKH~I"
This resin has the following characteristics:
Approximate Molecular Weight 20,000 to 30,000
Specific Gravity 1.18
Melt Flow (g/10 minutes at 220C) 2.5-10
Ultimate Tensile Strength, psi 9,000-9,500
Ultimate Tensile Elongation 50-100
Softening Temperature 100C
Moisture Vapor Transmission 3.5 gms/mil/
24 hrs/100 in.
Molecular Structure As shown above
Generally, the matrix resin preferably has a
great ability to bind the elec-troconductive particles,
e.g., graphite, carbon black or the metal powders
disclosed in U. S. Patent ~,163,075 or other useful
electroconductive particles that may be used. These
resins can be formed into sheets or films having high
mechanical strength, flexibility and high stiffnessO
1 Examples oE suitable resins that can be used
2 in this invention are thermoplastic resins such as
3 polyolefins (such as polyethylene or polypropylene),
4 polyvinyl chloride, polyvinyl acetal, cellulose acetate,
polyvinyl chloride, polyvinyl acetal, cellulose acetate,
6 polyvinyl acetate, polystyrene, polymethyl acrylate,
7 polymethyl methacrylate, polyacrylonitrile, thermo-
8 plastic polyesters, polyvinyl alcohol, and gelatin; and
g thermosetting resins such as thermosetting polyesters,
epoxy resins, and melamine resins. The thermoplastic
11 resins are preferred, and polyethylene, polyvinyl
12 acetal, cellulose acetate, and thermoplastic polyesters
13 are especially preferred.
1~ As is conventional in the art, additives such
as plasticizers, fillers, lubricants, stabilizers,
16 antioxidants or mold releasing agents may be added as
17 needed to the resin in order to improve its moldability,
18 storage stability, plasticity, tackiness, lubricity,
19 etc.
Examples of the plasticizers are dioctyl
21 phthalate, dibutyl phthalate, dicapryl phthalate,
22 dioctyl adipate, diisobutyl adipate, triethylene glycol
23 di(2-ethyl butyrate), dibutyl sebacate, dioctyl azelate,
2~ and triethylhexyl phosphate, which are generally used as
plasticiæers for resins. The amount of the plasticizer
26 can be varied over a wide range according, for example,
27 to the type of the resin and the type of the plasticizer
28 Generally, its amount is at most 150 parts by weight,
29 preferably up to 100 parts by weight, per 100 parts
by weight of the resin. The optimum amount of the
31 plasticizer is not more than 80 parts by weight per 100
32 parts by weight of ~he resin.
-- 10 --
1 Examples of fillers are fine powders of
2 calcium oxide, magnesium oxide, sodium carbonate,
3 potassium carbonate, strontium carbonate, zinc oxide,
4 titanium oxide, barium sulfate, lithopone, basic mag-
nesium carbonate, calcium carbonate, silica, and kaolin.
6 They may be used either alone or as mixtures of two or
7 more.
8 The amount of the filler is not critical, and
9 can be varied over a wide range according to the type of
the resin, the type of the filler, etc. Generally, the
11 amount is up to 1000 parts by weight, preferably not
12 more than 500 parts by weight, more preferably up to 200
13 parts by weight.
14 Usually its thickness is at least 3 microns.
The upper limit of the thickness is not strict, but is
16 advantageously set at 100 microns for the reason stated
17 above. Preferably, the thickness is 5 to 60 microns,
18 more preferably 10 to 40 microns.
19 The semiconductive resin layer 4 laminated on
the electroconductive particle-containing resin layer is
21 broken by discharging. It has a surface resistance of
22 10 to 109 ohms, preferably 103 to 107 ohms, more prefer-
23 ably 104 to 1o6 ohms and a volume resistance of 11 to
24 106 ohms-cm, preferably 11 to 105 ohms-cm, more prefer-
ably 102 to 104 ohms-cm.
26 The semiconductive resin layer ~ can be formed
27 by dispersing a conductivity-imparting agent in a resin
28 matrix.
29 The resin matrix forming a substrate for the
semiconductive resin layer 4 may be chosen from those
31 which have been described hereinabove about the non-
1 recording layer composed of an electroconductive par-
2 ticle-containing resin. The thermoplastic resins are
3 especially suitable, and polyethylene, cellulose acetate
4 and polyvinyl acetal are used advantageously~ As
needed, the resin may contain additives of the types
6 described hereinabove such as plasticizers and fillers
7 in the amounts described.
8 When a filler having a different conductivity
g from the conductivity-imparting agent, generally having
a lower conductivity than the conductivity-imparting
11 agent, is included in the semiconductive resin layer 4,
12 the breakdown of the semiconductive resin layer 4 by
13 electric discharging occurs more sharply, and a recorded
]4 image which is clearer and has a higher contrast can
be obtained. Suitable fillers of this kind are fine
16 powders of inorganic substances such as magnesium oxide,
17 calcium oxide, sodium carbonate, potassium carbonate,
18 strontium carbonate, titanium oxide, barium sulfate,
19 lithopone, basic magnesium carbonate, calcium carbonate,
silica, kaolin clay, and zinc oxide. They can be used
21 singly or as a mixture of two or more. Of these,
22 titanium oxide and calcium carbonate are especially
23 suitable. The average particle diameter of the filler
24 is generally 10 microns at most, preferably not more
than 5 microns, more preferably 2 to 0.1 microns. The
26 amount of the filler can be varied over a wide range
27 according to the type of the resin, etc. The suitable
28 amount is generally 10 to 2,000 parts by weight, prefer-
29 ably 20 to 1,000 parts by weight, more preferably 50 to
400 parts by weight, per 100 parts by weight of the
31 resin.
32 The conductivity-imparting agent to be dis-
33 persed in the resin to impart semiconductivity may be
34 any material which has conductivity and gives the
1 surface resistance and volume resistance described above
2 to the resin layer. Generally, suitable conductivity-
3 imparting agents have a specific resistance, measured
4 under a pressure of 50 kg/cm2, of not more than 106
ohms-cm. Examples of such a conductivity-imparting
6 agent include carbon blacks; metals such as gold,
7 silver, nickel, molybdenum, copper, aluminum, iron
8 and conductive zinc oxide (zinc oxide doped with 0.03
g to 2.0% by weight, preferably 0.05 to 1.0% by weight,
based on the zinc oxide, of a different metal such as
11 aluminum, gallium, germanium, indium, tin, antimony or
12 iron); conductive metal-containing compounds such as
13 cuprous iodide, stannic oxide, and metastannic acid; and
14 zeolites. Of these, carbon blacks, silver, nickel,
suprous iodide, conductive zinc oxide are preferred,
16 and carbon blacks and conductive zinc oxide are more
17 preferred. The carbon blacks which also act as a
18 coloring agent are most preferred.
19 Carbon blacks differ somewhat in conductivity
according to the method of productionO Generally,
21 acetylene black, furnace black, channel black, and
22 thermal black can be used.
23 The conductivity-imparting agent is dispersed
24 usually in the form of a fine powder in the resin. The
average particle diameter of the conductivty-imparting
26 agent is 10 microns at most, preferably not more than 5
27 microns, especially preferably 2 to 0.005 microns. When
28 a metal powder is used as the conductivity-imparting
29 agent, it is preferably in a microspherical, dendric
or microlumpy form. Moreover, since a resin sheet
31 having the metal powder dispersed therein tends to be
32 electrically anisotropic if its particle diameter
33 exceeds 0.2 micron. ~lence, the particle size of a metal
34 powder in the above-mentioned form to be used as a
- 13 -
1 conductivity-imparting agent for the semiconductive
2 resin layer 4 or the conductive layer 6 should be at
3 most 0.5 micron, preferably not more than 0.2 micron,
4 more preferably 0.15 to 0.04 micron. Scale-like or
needle-like powders can also be used, but should be
6 combined with powders of the above forms.
7 The amount of the conductivity-imparting agent
8 to be added to the resin can be varied over a very wide
g range according to the conductivity of the conductivity-
imparting agent, etc. The amount is that sufficient
11 to adjust the surface resistance and volume resistance
12 f the semiconductive resin layer 4 to the above-
13 mentioned ranges. For example, carbon blacks are
14 incorporated generally in an amount of 1 to 300 parts by
weight, preferably 2 to 200 parts by weight, more
16 preferably 3 to 150 parts by weight, per 100 parts by
17 weight of the resin. The other conductivity-imparting
18 agents are used generally in an amount of 3 to 500 parts
19 by weight, preferably 5 to 400 parts by weight, more
preferably 10 to 300 parts by weight, per 100 parts by
21 weight of the resin.
22 The thickness of the semiconductive resin
23 layer 4 is not critical, and can be varied over a wide
24 range according to the uses of the final product,
etc. Generally, its thickness is at least 2 microns,
26 preferably 3 to 50 microns, more preferably 5 to 20
27 micronS.
28 According to the present invention, the
29 conductive layer 6 is laminated on the other surface of
the semiconductive resin layer 4.
31 The conductive layer 6 plays an important role
32 in performing electric discharge breakdown with high
- 14 -
1 accuracy by converging the current flowing through the
2 semiconductive resin layer at a point immediately
3 downward of the electric discharge recording stylus.
~ The conductive layer 6 has a surface resistance of not
more than 104 ohms, preferably not more than 5 x 103
6 ohms, more preferably 10~1 to 2 x 103 ohms and a volume
7 resistance of not more than 102 ohms-cm, preferably not
8 more than 50 ohms-cm, more preferably not more than 20
g ohms-cm.
The conductive layer 6 having such resistance
11 characteristics may be a conductive resin layer com-
12 prising a thermoplastic or thermosetting resin and a
13 conductivity-imparting agent dispersed in it, a vacuum-
14 deposited metal layer, or a metal foil layer.
The thermoplastic or thermosetting resin that
16 can be used in the conductive resin layer can also be
17 selected from those described hereinabove in connection
18 with the non-recording layer. Of these, the thermo-
19 plastic resins, especially polyethylene, cellulose
acetate and polyvinyl acetal, are used advantageously.
21 The conductivity-imparting agent to be dispersed in the
22 resin may be chosen from those described above in
23 connection with the semiconductive resin layer. Carbon
24 blacks and metal powders are especially suitable~
Carbon blacks are particularly preferred over metals in
26 view of cost factors.
27 The conductivity-imparting agents are added in
28 amounts which will cause the resin layer to have the
29 electrical resistance characteristics described above.
The amounts vary greatly according to the type of the
31 conductivity-imparting agent. For example, carbon
32 blacks are used in an amount of generally at least 10
33 parts by weight, preferably 20 to 200 parts by weight,
- 15 -
1 more preferably 30 to 100 parts by weight; the other
2 conductivity-imparting agents especially metal powders,
3 are used in an amount of at least 50 parts by weight,
4 preferably 100 to 600 parts by weight, more preferably
150 to 400 parts by weight, both per 100 parts by weight
6 of the resin.
7 As needed, the conductive resin layer may
8 contain the aforesaid additives such as plasticiæers and
g fillers in the amounts stated.
The thickness of the conductive resin layer is
11 not critical, and can be varied widely according to the
12 uses of the final products, etc. Generally, it is at
13 least 3 microns, preferably 3 to 50 microns, more
14 preferably 5 to 20 microns.
The conductive layer 6 may be a vacuum
16 deposited metal layer. Specific examples of the metal
17 are aluminum, zinc, copper, silver and goldO Of these,
18 aluminum is most suitable.
19 The thickness of the vacuum-deposited metal
layer is not critical. Generally, it is at least 4
21 millimicrons, preferably 10 to 300 millimicrons,
22 more preferably 20 to 100 millimicrons. By an ordinary
23 vacuum-depositing method for metal, it can be applied to
24 one surface of the semiconductive resin layer 4.
The conductive layer 6 may also be a thin
26 metal foil, for example, an aluminum foil. It can be
27 applied to one surface of the semiconductive resin layer
28 4 by such means as bonding or plating.
29 It is understood that at least one of the
layers 4 and 6 may contain a coloring substance. Useful
- 16 -
1 coloring substances are carbon black, inorganic and
2 organic pigments, and dyes.
3 Carbon black has superior conductivity and
4 acts both as a coloring substance and a conductivity-
imparting agent as stated above. Thus, when the semi-
6 conductive resin layer or the conductive resin layer
7 already contains carbon ~lack as a conductivity-impart-
8 ing agent, it is not necessary to add a further coloring
9 substance. The inclusion of other suitable coloring
substance is of course permissible.
11 Examples of pigments other than carbon black
12 include inorganic pigments such as nickel yellow,
13 titanium yellow, cadmium yellow, zinc yellow, ochre,
14 cadmium red, prussian blue, ultramarine blue, zinc
white, lead sulfate, lithopone, titanium oxide, black
16 iron oxide, chrome orange, chrome vermilion, red iron
17 oxide, red lead and vermilion, and organic pigments of
18 the phthalocyanine, quinacridone and benzidine series
19 such as aniline black, naphthol yellow S, hanza yellow
10G, benzidine yellow, permanent yellow, Permanent
21 Orange, Benzidine Orange G, Indanthrene Brilliant Orange
22 GK, Permanent Red 4R, Brilliant Fast Scarlet, Permanent
23 Red F2R, Lake Red C, Cinquasia Red Y (Dup) (C. I. 46500),
24 Permanent Pink E (F~l) [Quido Magenta RV 6803(~AR)],
and Phthalocyanine Blue (C.I. Pigment Blue 15).
Examples of useful dyes are azoic dyes,
27 anthraquinonic dyes, thionidigo dyes, quinoline dyes,
28 and indanthrene dyes.
29 The pigments and dyes described are used
either alone or in combination according to the color
31 desired to be formed on a transfer recording sheet.
- 17 -
1 The amount of the pigment or dye can be varied
2 over a wide range according to the type, color intensity,
3 etc. of the coloring substanceO Generally, it is at
4 least 1 part by weight, preferably 2 to 1,000 parts
by weight, more preferably 3 to 500 parts by weight, per
6 100 parts by weight of the resin.
7 When the pigment or dye is to be incorporated
8 in both of the semiconductive resin layer 4 and the
g conductive resin layer 6, it is desirable that pigments
or dyes be of an identical color or have colors of the
11 same series.
12 The composite electric discharge recording
13 material of this invention can be formed by known
14 methods, for example a melt-extrusion method, a melt-
coating method, a melt-calendering method, a solution
16 casting method, an emulsion casting method or combi-
17 nations of these methods.
18 The composite electric discharge recording
19 material of this invention described above is useful as
an electric discharge transfer recording material or an
21 electric stencil master sheet.
22 The electric discharge transfer recording
23 mediums of the present invention are generally employed
24 by superimposing the transfer recording medium onto a
recording sheet 8, e.g., cellulosic paper, a synthetic
26 paper-like sheet or a plastic sheet so that the conduc-
27 tive layer 6 contacts recording sheet 8. When electric
28 discharge recording is performed by a discharge record-
29 ing stylus in accordance with an ordinary method from
the side of the electroconductive powder-containing
31 resin layer 2, the semiconductive resin layer 4 and the
32 conductive layer 6 are simultaneously broken by electric
.~f~
- 18 -
1 discharging, and the broken pieces 10 are transferred to
2 the record sheet and fixed thereon, thereby achieving
3 transfer recording.
9 According to a further embodiment of the
present invention, a color coupler may be put in one or
6 more transfer layers to react with a material in the
7 recording material or paper, to generate a colored
8 image, e.g., bisphenol A and leuco dye.
g It is understood that the electric discharge
transfer film of this invention can be processed to any
11 desired width or length in accordance with its desired
12 use. For example, the transfer film can be used in the
13 form of a narrow tape, such as a typewriter ribbon.
14 In electric discharge recording, the semi-
conductive resin layer and the conductive layer of the
16 composite electric discharge transfer recording material
17 are broken down, but the electroconductive powder-
18 containing resin layer is not broken because of its
19 electric anisotropy and remains substantially unchanged.
Accordingly, dissipation of any offensive odor issued
21 at the time of electric discharge breakdown is inhibited,
22 and soot or a coloring substance such as carbon black is
23 prevented from scattering and adhering to the discharge
24 recording stylus. The troublesome inspection and
maintenance of the discharge recording stylus can be
26 markedly reduced, and recording can be performed with
27 high reliability. The term "electrical anisotropy"
28 refers to the low resistance of support layer or
29 electroconductive particle containing resin layer 2 in
the through direction and the high resistance of this
31 layer in the lateral direction.
-- 19 --
1 The use of the composite electric discharge
2 recording material can afford a sharp recorded image,
3 and in electric discharge transfer recording, a transfer
4 recorded image having a high density, a natural appear-
ance and a soft tone can be obtained.
6 The composite electric discharge recording
7 material of this invention can be used a plurality of
8 times.
9 The composite electric discharge recording
material of this invention can be conveniently used
11 in facsimile systems, terminal recording devices in
12 electronic computers, automatic recording devices of
13 automatic measuring instruments, and various types of
14 printers, etc.
In the present specification, the terms
16 "surface resistance" and "volume resistance" is deter-
17 mined in accordance with the method described by H. R.
18 Dalton in U.S. Patent 2,664,044.
19 In the detailed description of the present
invention, a transfer film comprising a support layer
21 and two transfer layers is disclosed. It is understood
22 that the present invention also encompasses the use of
23 a support layer, as disclosed herein, having only one
24 or possibly more than two resin layers provided that
at least one of the layers is thermally or electro-
26 thermally transferable to another substrate, e.g., a
27 paper sheet.
28 The following examples further describe the
29 present invention.
- 20 -
EXAMPLE 1
A transfer sheet in accordance with this
invention was prepared as follows.
A transfer sheet in accordance with this
inven-tion was prepared as follows.
A stock solution (A-l) containing 27.5 grams
Es-tane 5715 ~Polyurethane) sold by B. F. Goodrich Co.,
and 72.5 grams me-thyl ethyl ketone was mixed together
and stirred until complete dissolution was achieved.
A second solution containing 10 grams of particulate
graphite, sold as Micro 650 by Asbury Graphite, 90
grams resin solution, 40 grams methyl ethyl ke-tone,
and 2.1 grams Byk SpecialTM sold by Mallinckrodt
Chemical Company, was blended with the first solution
in a chilled ~aring blender for 15 minutes and then
allowed to settle for 15 minutes.
The resulting solution was coated on a release
sheet with a gap coater to a dry thickness of 1.~1 mils,
air dried for 5 minutes and then dried in an oven at
65C for 15 minutes.
Another solution (B) was prepared by intro-
ducing 22.5 grams poly-n-butyl methacrylate, sold as
ELVACITE 2044 by E. I. du Pont de Nemours & Co., and
74.4 grams TOLUSOL 25TM, sold by Shell Chemical Company,
into an 8 oz. plastic bottle. The bottle was rolled on
a jar null until the contents were dissolved. 7.5 grams
Black Pearls L which is carbon black, sold by Cabot
Corporation, and 600 grams of 1/4 stainless steel
(Type 440) shot was added to the solution and the same
was milled for 16 hours. The resulting solution was
coated over the firs-t coating to a dry thickness of 0.5
¦ mil using a Mayer rod (about # 22). The product was
oven dried at 65C for 3 minutes.
2~
A final solution (C-l) was prepared by intro-
ducing 25.0 grams Aquadag E (graphi-te dispersion, 22%
solids in water) and 75.0 grarns ethanol in an 8 oz.
bottle. The contents were stirred rapidly for 60
minutes with vortex blades. This solution was coated
over the second coating (from solution B) to a dry
thickness of 0~3 mil using a Mayer rod (about ~18)
and oven dried at 65C for 3 minutes.
EXAMPLE 2
A -transfer sheet was prepared in accordance
with Example 1 except that a solution (C-2) contain-
ing 25.0 grams AQUABLACK 548-17TM (24% carbon black
in water) or 428-238, sold by Borden Chemical Co.,
2.0 grams Rhoplex P-376 (acrylic resin dispersion
in water, 50% solids) and 27.0 grams water was sub-
stituted for solution C-l and processed in the same
manner as solution C-1.
