U.S. patent number 3,652,271 [Application Number 05/030,238] was granted by the patent office on 1972-03-28 for photoelectrostatic recording member.
This patent grant is currently assigned to Addressograph-Multigraph Corporation. Invention is credited to Dennis M. Bornarth, Frank Schneidinger.
United States Patent |
3,652,271 |
Bornarth , et al. |
March 28, 1972 |
PHOTOELECTROSTATIC RECORDING MEMBER
Abstract
A photoelectrostatic copy sheet is prepared by using a paper
base sheet having a roughness in the range of from 100 to 250
Sheffield units. Bonded to the rough surfaced paper is a
photoconductive layer comprising zinc oxide and in another
embodiment sub-millimicron sized particles of hydrophobic silica
dispersed in a resin binder. The layer conforms to the rough fiber
textured surface of the base sheet to provide a finished recording
surface having a roughness in the range of from 70 to 250 Sheffield
units and a gloss (75.degree., Gardner) not in excess of 20
percent. This sheet has the appearance, feel and handle of an
uncoated piece of paper.
Inventors: |
Bornarth; Dennis M. (Palatine,
IL), Schneidinger; Frank (Marengo, IL) |
Assignee: |
Addressograph-Multigraph
Corporation (Mount Prospect, IL)
|
Family
ID: |
26705808 |
Appl.
No.: |
05/030,238 |
Filed: |
April 20, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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664958 |
Sep 1, 1967 |
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Current U.S.
Class: |
430/64; 430/89;
101/462; 430/96 |
Current CPC
Class: |
G03G
5/0507 (20130101); G03G 5/142 (20130101) |
Current International
Class: |
G03G
5/14 (20060101); G03G 5/05 (20060101); G03g
005/08 () |
Field of
Search: |
;96/1.5,1.6,1.7,1.8
;252/501 ;117/76,56,155,201,215,218 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Van Horn; Charles E.
Parent Case Text
This application is a continuation-in-part of copending U.S.
application Ser. No., 664,958, filed Sept. 1, 1967 and now
abandoned.
Claims
What is claimed as new and desired to be secured by Letters Patent
of the United States is:
1. A photoelectrostatic recording member having improved visual
readability properties comprising:
1. a paper base support having the following physical
characteristics:
2.
2. a barrier coating applied to said base support providing a
solvent holdout in excess of 60 mm;
3. a photoconductive layer covering and bonded to said base support
comprising an organic solvent laid coating of zinc oxide dispersed
in an insulating resin binder having the following physical
characteristics:
said recording member having a basis weight in the range of from 15
to 25 lbs. per (17 inches .times. 22 inches - 500) and a caliper of
3.0 to 4.5
mils. 2. The recording member as defined in claim 1 wherein said
layer additionally includes sub-millimicron size particles of a
hydrophobic silica, said silica being present in an amount not
exceeding about 5 percent by weight of the zinc oxide.
3. The recording member as defined in claim 2 wherein said resin
binder is a mixture of at least two resins, one of said resins
having vinyl acetate as the major monomeric component and the other
resin being a silicone resin, said mixture comprising no more than
10 percent by weight of the silicone resin.
4. The recording member as defined in claim 1 wherein said resin
binder includes a styrenated acrylic copolymer resin.
5. A photoelectrostatic recording member having improved visual
readability properties comprising:
1. paper base support having the following physical
characteristics
a. basis weight (pounds per 17 by 22 inches - 500 sheets) 12-20
b. caliper (Sheffield) (mils) 2.5--4.0
c. roughness (Sheffield) 40--250
d. stiffness (mg., Gurley, at 72.degree. F. and 50 percent relative
humidity)
machine direction 100--200
cross direction 50--125
2. said base support providing a solvent hold-out in excess of 60
millimeters;
3. a photoconductive layer covering and bonded to said base support
comprising an organic solvent laid coating comprising a resin
binder having a finely divided photoconductive zinc oxide and
sub-millimicron sized hydrophobic silica particles dispersed
therein, said silica particles being present in an amount not
exceeding about 5 percent by weight of the zinc oxide, and having
the following physical characteristics:
a. roughness (Sheffield) 100--250
b. gloss (75.degree., Gardner) below about 10 percent said
recording member having a basis weight in the range of from 15 to
25 pounds per (17 inches by 22 inches - 500).
6. The recording member as defined in claim 5 wherein the layer has
a thickness in the range of from 0.1 to 0.5 mil.
7. The recording member as defined in claim 5 wherein the particle
size of the silica is about 0.20 millimicrons.
8. The recording member as defined in claim 5 wherein said paper
base is treated with a solvent barrier precoat to render said
support surface resistant to the penetration of organic solvents,
said precoat being selected from the group consisting of polyvinyl
alcohol, starch, casein, animal glue, carboxymethyl cellulose,
methyl cellulose, styrene-butadiene latex, acrylic latex,
polytetraflouroethylene, and align.
9. The recording member as defined in claim 5 wherein said resin
binder is selected from the group consisting of multipolymers
containing vinyl acetate as the major monomeric component,
polyvinyl acetate resin, polyester resin, copolymers of vinyl
chloride-vinyl acetate, phenoxy resin, acrylic resin, and
copolymers of styrene-butadiene.
10. A photoelectrostatic recording member having improved visual
readability properties comprising:
1. a paper base support having the following physical
characteristics:
a. basis weight (pounds per 17 inches by 22 inches - 500)
12--20
b. caliper (mils) 2.5--4.0
c. roughness (Sheffield) about 55
d. stiffness mg., Gurley, at 72.degree. F. and 50 percent relative
humidity)
machine direction 50--150
cross direction 25--100
2. a barrier coating applied to said base support providing a
solvent hold-out in excess of 60 millimeters;
3. a photoconductive layer covering and bonded to said base support
comprising an organic laid coating of finely divided
photoconductive zinc oxide and sub-millimicron sized hydrophobic
silica particles dispersed in an insulating resin binder containing
from 0.1 percent to 10 percent by weight of a silicone resin, and
having the following physical characteristics:
a. roughness (Sheffield) about 100
b. gloss (75.degree., Gardner) below about 7 percent said recording
member having a basis weight in the range of from 15 to 25 pounds
per (17 inches .times. 22 inches - 500) and a caliper of 3.0 to 4.5
mils.
11. The recording member as defined in claim 10 wherein the
remainder of said resin binder is a resin having polyvinyl acetate
as the major component.
12. A photoelectrostatic recording member having improved visual
readability properties comprising:
1. a paper base support having the following physical
characteristics:
2. a barrier coating applied to said base support providing a
solvent holdout in excess of 60 mm;
3. a photoconductive layer covering and bonded to said base support
comprising an organic solvent laid coating of zinc oxide dispersed
in an insulating resin binder having the following physical
characteristics:
said recording member having a basis weight in the range of from 15
to 25 lbs. per (17 inches .times. 22 inches - 500) and a caliper of
3.0 to 4.5 mils.
13. The recording member as defined in claim 11 wherein said resin
binder includes a styrenated acrylic copolymer resin.
Description
BACKGROUND OF THE INVENTION:
This invention relates generally to an improved photoelectrostatic
recording member and, more particularly, to a novel copy sheet
which, despite being coated, has the general appearance, feel and
handle of ordinary, uncoated bond paper.
Known photoelectrostatic recording members comprise a conductive
base or substrate, ordinarily paper, and a photoconductive layer
bonded to and supported by the substrate. The layer is a resinous
substance having dispersed therein finely divided particles of
photoconductive material, such as zinc oxide. Such members are
imaged in accordance with the well known photoelectrostatic copying
process, and developed using a pigmented thermoplastic powder that
is attracted to the image areas and fixed to the recording surface
of the sheet.
In accordance with the conventional method of preparing copy sheets
of the photoelectrostatic type, the resin material is dissolved in
an organic solvent medium, principally toluene, with
photoconductive particles of zinc oxide being mixed with this
liquid medium until a paint-like consistency is achieved. This
mixture is applied as a coating to a paper base, and the solvent
medium is then evaporated leaving a thin, homogeneous,
photoconductive layer bonded to the support surface of the paper
base.
In general, conventional copy sheets of this type do not look, feel
or handle like ordinary uncoated writing or bond type paper, and
for this reason have not enjoyed more widespread commercial
success.
For example, known photoelectrostatic copy papers have a smooth
recording surface which does not readily receive pencil markings or
the like and tends to be glossy, reflecting illumination in a
mirror-like fashion to produce glare. In fact, in the preparation
of conventional copy sheets, care is taken to insure against
producing a rough recording surface, since it has heretofore been
considered important to have maximum recording surface smoothness
in order to avoid mechanical entrapment of the developer powder in
the background or non-imaged areas of the sheet. Thus, known
recording members, although having a surface which does not tend to
entrap developer powder, provide a surface that is somewhat
difficult to read and is a poor medium on which to write with pen
or pencil.
Known copy sheets suffer from a further disadvantage in that, as a
result of employing a dense, low-bulk, supercalendered paper base
which enhances the smoothness of the recording surface, the copy
sheet, tending to be heavier than ordinary paper, feels limp. Such
a sheet does not readily lend itself to vertical filing.
SUMMARY OF INVENTION
Accordingly, it is the general object of this invention to provide
an improved photoelectrostatic copy sheet prepared in accordance
with organic solvent coating techniques which looks, feels, and
handles like ordinary, uncoated writing or bond paper.
It is another object of the present invention to provide an
improved photoelectrostatic copy sheet which is easy to read being
substantially glare-free, readily receives pencil markings or the
like, and has the aesthetic qualities of bond paper.
It is a further object of the present invention to provide a light
weight, bond-like photoelectrostatic copy sheet prepared in
accordance with organic solvent coating techniques having a
semi-rough fiber-type recording surface which, although rougher
than conventional copy sheets, will not mechanically entrap
developer powder in background areas.
Contrary to what is generally accepted as desirable, a recording
surface can have a limited degree of roughness and need not be as
smooth as heretofore considered necessary for high quality copy. We
have discovered that a recording surface having a roughness in the
range of from about 70 to 250 Sheffield units and a gloss
(75.degree., Gardner) of less than 20 percent provides a finish
which does not entrap developer material and has an uncoated and
substantially glare-free appearance. Moreover, even though it has
this rough surface a sheet of this type can readily be converted
into a lithographic master that produces excellent prints. Sheets
having rough surfaces ordinarily do not function well as
lithographic masters. Recording surfaces which have a roughness in
the range of 125 to 175 Sheffield units provide even better
results.
In preparing a copy sheet having the proper recording surface
smoothness, two techniques were developed.
a. The first technique calls for applying a zinc oxide resin binder
coating to a paper base having a critical support surface roughness
in the range of from 100 to 250 Sheffield Units. The resinous
coating, upon distributing itself over the rough support surface in
conformity with the contours of the fibrous structure of the base
provides a recording surface which has the same or substantially
the same degree of roughness as the support surface. Thus, a
recording surface is formed which is sufficiently smooth to avoid
mechanical entrapment of the developer powder, but has numerous
irregularities acting to scatter or diffuse incident light rather
than reflect the light in an orientated or mirror-like fashion.
Resins which enhance or re-enforce the surface effect of light
scattering are preferred. The thickness of the photoconductive
layer lies within the range of from 0.1 to 0.5 mil, and is
preferably within the range of from 0.2 to 0.4 mil. Microscopic
examination of the recording surface reveals that a layer of this
thickness conforms substantially to the fiber texture of the
base.
b. The second technique calls for dispersing in the resin binder,
in addition to the zinc oxide, particles of hydrophobic silica.
When applied to a relatively smooth base having a support surface
roughness as low as 40 Sheffield units, a coating containing this
type of silica forms a recording surface which has a roughness of
about 100 Sheffield units. Preferably, silica/zinc oxide/binder
coatings are applied to a base sheet having a roughness in the
range of from 100 to 250 Sheffield units.
Ordinarily, the addition of silica to a photoconductive coating
interferes with the photoconductive properties of the sheet. We
have discovered, however, that when hydrophobic silica is added to
the photoconductive coating in small amounts, usually not more than
5 percent by weight of the zinc oxide, the photoconductive
properties of the copy sheet are not impaired, and, surprisingly,
print density is generally improved. The preferred amount of silica
is from 0.2 percent to 1.5 percent by weight of the zinc oxide. If
the resin binder comprises from about 0.1 percent to 10 percent by
weight of a silicone resin, and silica is incorporated into the
coating, the surface roughness of the copy sheet is further
enhanced. The addition of a small amount of a silicone resin to the
binder also improves the performance of the sheet at high humidity
conditions.
A preferred hydrophobic silica is sold by the Pigments Division of
the Degussa Corporation of New Jersey under the trade name Aerosil
R972. This silica has a very fine particle size of approximately
0.20 millimicrons. Treatment of raw silica with an oil or the like
in accordance with standard processing techniques imparts to the
R972 silica a hydrophobic character. Why this type of silica does
not interfere with the photoconductive properties of the copy sheet
is not clearly understood. However, it is believed that because
water is not absorbed by this type of silica, the coating will
remain free of this aqueous contamination which interferes with the
electrical properties of the sheet. It is clear that the silica
must have a hydrophobic character. This is critical. It is believed
that the small particle size may be important, however, particle
size does not seem to be per se critical.
We have also found that, in order for a copy sheet to handle like
uncoated paper, it is necessary for the sheet to be light weight,
have a high degree of bulk, and have the proper degree of
stiffness. In accordance with another feature of this invention, an
uncalender paper base having a relatively low basis weight and high
degree of stiffness is employed. Using such a base having the
proper support surface roughness, a copy sheet is provided which
handles like ordinary paper.
The following table lists the preferred physical properties, other
than roughness, of the uncoated base as well as the finished copy
sheet of this invention:
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TABLE 1
Paper Base Copy Sheet (optimum range)
__________________________________________________________________________
Basis weight (lbs. per 17 inches .times. 22 12-20 15-25 inches -500
) Caliper (mil) 2.4-4.0 3.0-4.5 Stiffness (mg, Gurley at 72.degree.
F. and 50% relative humidity) Machine direction 50-150 100-200
Cross Machine direction 25-100 50-125
__________________________________________________________________________
Before the base sheet is coated the support surface is usually
treated with a solvent holdout precoat, care being taken to insure
that the critical roughness of the support surface is kept intact.
Examples of suitable precoat materials are: polyvinyl alcohol,
starch, casein, animal glue, carboxymethyl cellulose, methyl
cellulose, styrenebutadiene latex, acrylic latex,
polytetrafluoroethylene and algin. The polyvinyl alcohol has been
found to be especially well suited for this purpose.
The effectiveness of the barrier coating holdout may be tested in
accordance with conventional techniques using an I.G.T.
printability tester which is manufactured by the Institute of
Graphic Techniques, Amsterdam Holland. The I.G.T. tester consists
of a pendulum having a sector to which a test specimen is clamped,
and a printing disc. A test dye solution, applied to the test
specimen by means of the printing disc, is used to stain the
specimen. The solution comprises a blend of the binder resin,
toluene, and Irisol dye (General Aniline and Film Corporation). The
viscosity of this solution is about 14.5 seconds when measured at
74.degree. F. using a No. 2 Zahn Cup. A drop (0.005 cc.) of the
solution is applied to the disc and the pendulum is permitted to
swing freely. When the pendulum and disc come into contact during
the swing of the pendulum the dye solution is spread over the test
specimen staining it. The longer the stain on the specimen, the
better the holdout. Test results indicate that the length of the
stain must exceed 60 mm. and preferably should exceed 100 mm.
The photoconductive coating which is applied to the substrate is
prepared in accordance with standard techniques. The resin, silica
and zinc oxide are blended together in an organic solvent medium
and applied to the support surface using conventional coating
equipment. As the solvent is evaporated, the resinous coating
conforms to the fibrous support surface to form a rough, irregular
layer. The coating weight and weight of the base are controlled in
order to keep the weight of the copy sheet in the preferred range
of 15 to 25 lbs. per ream (17 inches .times. 22 inches - 500
sheets).
A variety of suitable resins are available, the preferred resins
being: multipolymers containing vinyl acetate as the major
monomeric component, polyvinyl acetate resins, polyester resins,
copolymers of vinyl chloride-vinyl acetate, phenoxy resins, acrylic
resins styrenated acrylic copolymers and copolymers of
styrene-butadiene. It has been found that resins containing a
polyvinyl acetate component as the major polymeric constituent of
the resin are particularly well suited for the purposes of this
invention, since they tend to dry to a dull finish, more so than
the other resins.
As a result of our discoveries, two types of bond-like
photoelectrostatic recording members are provided:
a. The first type of member comprises a light weight, stiff,
precoated paper base having a rough support surface, and bonded to
the support surface a thin, solvent laid photoconductive layer
which conforms to the rough support surface. The roughness of the
fiber textured support surface is within the range of from about
100 to 250 Sheffield units, preferably in the range of from 125 to
175 Sheffield units. The photoconductive layer comprises finely
divided particles of zinc oxide dispersed in an insulating resin
binder. This layer on conforming to the support surface provides a
recording surface having a roughness in the range of from 70 to 250
Sheffield units, preferably from 125 to 175 Sheffield units, and a
gloss (75.degree., Gardner) not in excess of 20% preferably in the
range of 7 percent to 15 percent.
b. The second type of member comprises a light weight, stiff,
precoated paper base having either a smooth or, preferably a rough
support surface, and bonded to the support surface a thin, solvent
laid zinc oxide/resin binder photoconductive layer containing
submillimicron size particles of hydrophobic silica. As a result of
the silica, the photoconductive layer formed on a relatively smooth
base has a rough character and low gloss (75.degree., Gardner),
i.e., less than 10 percent. When a layer containing silica is
formed on a rough base, an even greater bond-like surface
appearance is achieved.
As a result of the recording surface roughness of the recording
member, a copy sheet is provided which greatly resembles ordinary
uncoated paper in general appearance, the ability to accept pencil
markings, and reading quality.
DESCRIPTION OF PREFERRED EMBODIMENTS
The invention is disclosed in further detail by means of the
following examples which are provided for purposes of illustration
only. It will be understood by those skilled in the art that
modifications in barrier coatings, relative proportions of binder
materials and operating conditions can be made within the
disclosure of this invention without departing from the spirit and
scope thereof.
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EXAMPLE I
PAPER BASE SUPPORT:
__________________________________________________________________________
Bleached Sulfite (Fitchburg Paper Company, Fitchburg,
Massachusetts) Basis weight (lbs./17 inches .times. 22 inches -
500) 14 Caliper (mils) 2.9 Stiffness (mg., Gurley) Machine
direction 70 Cross Machine direction 39
__________________________________________________________________________
Using such conventional coating means as an air knife applicator,
an aqueous solution of polyvinyl alcohol is applied to the support
surface of the base. A suitable polyvinyl alcohol is sold by the
DuPont de Nemours & Co., Inc. under the tradename ELVANOL 5105.
The base is then dried by slowly passing it through an oven
maintained at a temperature of 200.degree. F. The preferred barrier
coating weight is in the range of from 0.3 to 0.6 lb. per 3,000
square feet, with the optimum barrier coat being 0.5 lb. per 3,000
square feet. Such a thin coating has sufficient solvent holdout
strength to prevent the penetration of the solvent and resin into
the base. Since the barrier layer is thin, the rough, fibrous
character of the support surface remains intact and is not masked
or
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otherwise materially altered.
Photoconductive Coating: % by Weight
__________________________________________________________________________
Polyvinyl Acetate Copolymer 12.0 (78-3306, National Starch %
Chemical Company) Zinc Oxide 31.7 (Photox 80, New Jersey Zinc Co.)
Toluene 45.0 Methyl Ethyl Ketone 11.3
__________________________________________________________________________
The resins, pigments and solvents are milled together for about 1
hour to thoroughly disperse the pigment particles in the resin,
insuring a uniform consistency. Using conventional roller coating
equipment, the paint-like resinous blend is applied to the
pretreated base support surface. Next, the solvent is volatilized
at a temperature of about 115.degree. F. leaving on the support
surface of the base a dried photoconductive layer about 0.3 mil
thick which weighs about 15 lbs. per 3,000 square feet. The
photoconductive layer has a paper-like finish and the copy sheet is
light, weighing 19 lbs. per ream (17 inches .times. 22 inches -
500). This sheet has excellent photoconductive properties and
provides a very dense image on being developed.
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EXAMPLE II
PAPER BASE SUPPORT:
__________________________________________________________________________
Bleached Sulfite (West Virginia Pulpand Paper Company) Basis weight
(lbs./17 inches.times..times. 22 inches - 500) 17.5 Caliper (mils)
3.1 Roughness of support surface (Sheffield units) 55 Stiffness
(mg, Gurley) machine direction 100 Cross machine direction 50
__________________________________________________________________________
The support surface is treated as described in Example I with
polyvinyl alcohol.
Photoconductive Coating: % By Weight
__________________________________________________________________________
Polyvinly acetate copolymer 8.1 (78-3306, National Starch and
Chemical Company) Silicone resin (SR82, General Electric Company)
0.3 Zinc Oxide (Photox 80, New Jersey Zinc Company) 32.6
Hydrophobic Silica 0.2 (Aerosil R972, Degussa) Tolulene 46.3 Methyl
ethyl ketone 12.5
__________________________________________________________________________
The resins, pigments and solvents are milled together as described
in Example I and applied to the precoated paper base which has a
roughness of 55 Sheffield units. As a result of the silica, a
roughness of about 100 Sheffield units is imparted to the recording
surface formed. This sheet has excellent photoconductive properties
and provides copies of superb contrast and print density.
EXAMPLE III
This example differs from Example I in the substitution of a
different type of polyvinyl acetate copolymer, Resyn 26-1404,
manufactured by National Starch, for resin 78-3306. The weights,
mixing procedures and coating techniques are substantially the same
as in Example II.
EXAMPLE IV
This example differs from Example II in the substitution of a
polyvinyl acetate terpolymer, 5912 A manufactured by Midland
Industrial Finishing Company of Waukegan, Illinois, for resin
78-3306. The weights, mixing procedures and coating techniques are
substantially the same as in Example II. The member prepared in
accordance with this example performs equally as well as that of
Example II.
EXAMPLE V
This example differs from Example I in the substitution of a
polyvinyl acetate, Vinac B-100, manufactured by Air Reduction
Chemical and Carbide Company of New York for resin 78-3306. Pure
methyl ethyl ketone is used in place of toluene as the solvent
medium.
EXAMPLE VI
This example differs from Example II in the substitution of a
polyvinyl acetate Daratak 9228, manufactured by Dewey and Almy
Company of Cambridge, Massachusetts, for resin 78-3306. The weights
mixing procedures and coating techniques are substantially the same
as in Example II.
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EXAMPLE VII
Photoconductive Coating % By Weight
__________________________________________________________________________
Acrylic resin 33.3 (AT-56, Rohm & Hass) Zinc Oxide (Photox 80,
New Jersey Zinc Co.) 6.7 Toluene 60.0
__________________________________________________________________________
The resin, pigments and solvents are blended together as described
in Example I and applied in the same manner to the pretreated paper
substrate having a roughness in the range of from 100 to 250
Sheffield units. The recording member of this example, upon being
developed, has very good image density.
EXAMPLE VIII
This example differs from Example VII in the of a different acrylic
resin, Bakelite 150, manufactured by the Union Carbide Corporation
for resin AT-56.
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EXAMPLE IX
Photoconductive Coating % Weight
__________________________________________________________________________
Polyester resin 33.3 (S-705-45, manufactured by 1-SIS, Chemical Co.
of Springdale, Conn.) Zinc Oxide 6.7 (Photox 80, New Jersey Zinc
Co.) Hydrophobic Silica 0.1 (Aerosil R972, Degussa) Toluene 30.0
Methyl ethyl ketone 30.0
__________________________________________________________________________
These materials were blended together as in Example I and applied
to the rough support surface of the paper base described in Example
I.
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EXAMPLE X
Photoconductive Coating % Weight
__________________________________________________________________________
Phenoxy resin 32.0 (PKHS, manufactured by Union Carbide Company)
Zinc Oxide (Photox 80, New Jersey Zinc Co.) 4.0 Methyl ethyl ketone
32.0 Toluene 32.0
__________________________________________________________________________
These materials are blended together and applied to the paper base
support as described in Example I.
EXAMPLE XI
This example differs from Example I in the substitution of a
styrene-butadiene copolymer, Pliolite CPR 1141A, manufactured by
the Goodyear Company, for the polyvinyl acetate copolymer resin.
78-3306.
EXAMPLE XII
This example differs from Example I in the substitution of vinyl
chloride-vinyl acetate copolymer, VAGH resin, manufactured by the
Union Carbide Company for the polyvinyl acetate copolymer resin,
78-3306.
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EXAMPLE XIII
PAPER BASE SUPPORT
__________________________________________________________________________
Bleached Sulfite (Weyerhauser Paper Company, Fitchburg,
Massachusetts) Basis Weight (lbs/17 inches .times. 22 inches-500)
19 Caliper (mils) 3.9 Roughness of Support Surface 159 (Sheffield
units) Stiffness (mg., Gurley at 72.degree. F. and 50% relative
humidity) Machine direction 125.2 Cross machine direction 58.2
__________________________________________________________________________
Using such conventional coating means as a trailing blade
applicator, an aqueous solution including polyvinyl alcohol is
applied to the support surface of the base. The base is then dried
by slowly passing it through an oven maintained at a temperature of
about 200.degree. F. The preferred barrier coating weight is in the
range of from 3.0 to 5.0 lbs. per 3,000
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square feet.
Photoconducting Coating: % Weight
__________________________________________________________________________
Styrenated acrylic copolymer resin 10.4 (DeSoto Chemical Co. E-041
45% resin) Zinc Oxide 36.9 (AZO 661, American Zinc, Lead and
Smelting Co.) Chlorothene 22.8 Toluene 29.9
__________________________________________________________________________
The resin, pigment, etc., are milled together as described in
Example I and applied to the precoated paper base which has a
roughness of 159 Sheffield units, resulting in a recording surface
having a roughness of 79 Sheffield units. This sheet has excellent
photoconductive properties and provides copies with excellent
contrast and print density.
The following table lists the physical properties of the novel copy
paper prepared in accordance with Examples I, II and XIII standard
bond paper and a typical prior art copy paper. This table, serving
as a basis for comparison, illustrates the marked improvement in
paper-like appearance and feel exhibited by the copy paper of this
invention as compared to the like properties of the prior art
material. The results of Examples I, II, and XIII are
representative of all the examples. ##SPC1##
The values in Table II were obtained using well known standard test
procedures with all samples being conditioned at 72.degree. F. and
50 percent relative humidity. All roughness measurements were made
using a Sheffield Smoothness Tester manufactured by the Sheffield
Company of Dayton, Ohio, a division of the Bendix Corporation. The
smoothness and gloss values set forth hereinabove impart to the
copy paper of this invention properties, such as a bond-like
appearance and feel, similar to those of the standard bond paper.
The relatively low gloss value of lack of glare also indicates that
the sheet is of a good reading quality. The basis weight, caliper,
and pencil take of the copy paper of this invention correspond to
like properties in the standard bond sheet. The ratio of caliper to
basis weight gives an indication of the bulkness of the sheet. As
seen from Table II the sheet of this invention having a bulk even
greater than that of bond paper is far superior to the prior art
material. And, although the sheet of this invention is relatively
light weight, it still has the same or substantially the same
degree of stiffness as that of the bond paper.
* * * * *