CA1066759A - Technique for making electrical ground contact with the intermediate conductive layer of an electrostatographic recording member - Google Patents
Technique for making electrical ground contact with the intermediate conductive layer of an electrostatographic recording memberInfo
- Publication number
- CA1066759A CA1066759A CA218,089A CA218089A CA1066759A CA 1066759 A CA1066759 A CA 1066759A CA 218089 A CA218089 A CA 218089A CA 1066759 A CA1066759 A CA 1066759A
- Authority
- CA
- Canada
- Prior art keywords
- conductive
- electrically
- recording member
- hole
- adhesive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/75—Details relating to xerographic drum, band or plate, e.g. replacing, testing
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
- G03G5/10—Bases for charge-receiving or other layers
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Photoreceptors In Electrophotography (AREA)
- Discharging, Photosensitive Material Shape In Electrophotography (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An eloctrostatographic recording member includes an electrically-insulating substrate, an intermediate layer overlying the substrate, the intermediate layer being electrically conduc-tive, an outer layer overlying the intermediate layer, the outer layer comprising a photoconductive material or a dielectric mate-rial of high volume resistivity, and means for establishing a ground connection to the electrically-conductive intermediate layer, wherein said ground connection meand comprises at least one hole or aperture disposed through the thickness of the re-cording member from a surface thereof at least to the depth of the conductive intermediate layer and substantially completely filled with an electrically-conductive composition comprising a plastic adhesive and a sufficient amount of an electrically-conducting pigment to make the composition electrically-conductive.
The aperture or hole may extend through the entire thickness of the recording member and is located in a non-image area thereof.
An eloctrostatographic recording member includes an electrically-insulating substrate, an intermediate layer overlying the substrate, the intermediate layer being electrically conduc-tive, an outer layer overlying the intermediate layer, the outer layer comprising a photoconductive material or a dielectric mate-rial of high volume resistivity, and means for establishing a ground connection to the electrically-conductive intermediate layer, wherein said ground connection meand comprises at least one hole or aperture disposed through the thickness of the re-cording member from a surface thereof at least to the depth of the conductive intermediate layer and substantially completely filled with an electrically-conductive composition comprising a plastic adhesive and a sufficient amount of an electrically-conducting pigment to make the composition electrically-conductive.
The aperture or hole may extend through the entire thickness of the recording member and is located in a non-image area thereof.
Description
10667~9 .
The present invention relates generally to electrophoto-graphic and electrostatic recording elements and processes for making the same; and more particularly to an improved technique for making an electrical ground connection to the intermediate electrically-conductive layer of such elements.
As used in the present specification, the term "electrostato-graphic" is intended to mean and cover both electrographic and ` ~' electrophotographic members.
~, Both types of recording elements are employed in reproduc-1 10 tion processes. Essentially, a latent image is formed in these ~ elements by providing an imagewise surface charge on an insulat-`, ing surface of the element, and thereafter developing the charg-`~3 ^~ ed latent image by means of an electrically-attractable material, ~ such as a "toner" (i.e., directionally charged colloid carbon - ~ 15 particles suspended in an insulating liquid or on a dry carrier).
Specifically, an electrophotographic element normally ~; comprises at least a substrate having coated thereon a layer containing a suitable photoconductor. The support layer i3 ma~`~e conductive either by the inclusion therein of electrically-con-ductive materials or by coating its surface ~the surface designed to receive the photoconductive layer) with an electrically-conductive material. Images are usually formed on the photo-conductive layer by first applying a uniform electrostati:c charge to the photoconductive layer by any suitable method, i 25 thereafter imaging the charged material by exposing it to light . ~ ` -1- ~
,'~ ~F
~ ~ .
. ~ .. . .. . . .. . .. .: . :, . . . .
-10f~6759 through a transparent master or by reflection from an opaque master which is being reproduced, thereby causing the photocon-ductive layer to become conductive, resulting in the dissipation of the charge in those areas of the layer exposed to light. In 5 a subsequent step, the charge pattern or latent image on the image layer is rendered visible by the application thereto of a colored or black electroscopic toner.
An electrographic recording element is similar in construc-tion to the electrophotographic element, with the photoconductive `` 10 layer being replaced with a high dielectric layer or a "charge retentive layer", that is, a material having a volume resistivity of not less than about 1012 ohm-centimeters. During this "print-; ing" process the electrical charge is applied in the image areas by a stylus and developed in the same manner as the electrophoto-` 15 graphic element.
With either type of element, it is often desirable during one or more of the processing steps (e.g., during charging or during toning) to establish a ground connection (to a reference potential) to the conductive layer of the recording element in .~ ~
`~ 20 order to create a highly conducting reference plane which is held at or near ground potential. For example, during the electrostatic charging of the photoconductive layer or during . ~.
the "printing" of the dielectric layer, the potential of the conducting layer has a tendency to build-up with respect to } 25 ground if it is not grounded. If this should occur, then there '`'t~ iS a less than desirable difference in potential between the areas truck by light and those not struck in an electrophotographic ' ~J element, and between the areas retaining or not xetaining "print"
charges in an electrographic element, resulting in a latent image 30 which is difficult to develop in the subseque~t toning step, .i ~ -2-.
, - . :
.
.. ..
1(366759 thereby resulting in copies which exhibit poor image quality, high background discoloration and/or poor contrast.
The prior art is replete with suggestions as to how to assure proper electrical grounding of the conductive layer in such elements. The classical approach is to provide an elec-trically-conductiv,e substrate which is easy and conventional if the substrate is a permeable or non-homogeneous substrate such as paper, since the substxate can be filled during manufacture with an electrically-conduc~ive pigment such as carbon black, or saturated with a solution of an ionic, hygroscopic substance, such as salt of a polyelectrolyte. However, there are disadvantages in such a technique. For example, the ionic hygroscopic impregnant is not generally effective in low porosity papers and the conduc-tivity it imparts is not stable but varies by several orders of ; 15 magnitude with the relative humidity o the environment. The use of carbon black as a filler insures the stability of the conduc- -` ~-`tivity, but may be unacceptable for aesthetic reasons, especially if a white substrate is desired. Moreover, it tends to weaken the ` substrate physically. Finally, it must be formulated into the ` 20 substrate at the time of manufacture and thus, cannot be applied to separately-made substrates. In addition, the primary dis-~ , .
advantage of this technique is that it cannot be applied to homo-geneous, impermeable substrates, such as extruded or cast films made from, for example, synthetic resins such as polyesters.
A further approach has been to provide a conductive inter-mediate layer between a non-conducting substrate and the photo-conductive or dielectric layer~ It has been suggested to con-; tact this conductive intermediate layer by removing the di- ~-electric or photoconductive layer from a limited area thereby exposing the intermediate conductive layer so that an electrode - -~
' ~
~ 1~)66759 can be physically contacted with the conductive layer. Other approaches have been to cut, punch, scratch or otherwise disrupt the physlcal integrity of the dielectric or photoconductive layer with an ele~trode which is forced into contact with the intermediate conductive layer.
- A further alternative of the prior art has been to provide a conductive pathway established from the conduative layer to the outer surface of the member where an electrode can establish contact with ito Since it is a part of the recording member, it 10 must be inexpensive to apply, inconspicuous, flexible (in flex- -ible recording elements) and of course both effective and ` reliable.
:;i An example of the prior art's solutions to this problem is ~ shown in U.S. Patent NoO 3,118,789, Wiswell et al. The patent ,,.; ~ ~
~ 15 discloses an electrophotographic recording member comprising a ... .
paper substra~e, a conductive interlayer and a photoconductive layer overlying the conductive interlayer with, optionally, a " conductive layer coating the back side of the papèr substrate.
The paper substrate is perforated with fine holes so that the ; .
`~ 20 conductive lacquer of which the conductive interlayer is composed ~ will penetrate through the paper during the coating ope~ation and `~
`j thus enable the establishment of an electrical connection there-~$ through to the conductive interlayer. A disadvantage with this 3 type o~ electrical connection is that it is not useful with im-permeable substrates such as polyester films. If the substrate , ~ iQ a film, and transparency and use as a photographic member is required, the methods suggestèd in the ~iswell et al Patent can--~ not be employèd tO establish contact with the conductive inter-layer because of the damage such a technique will cause to the film's optical characteristics~
.~. - ~. ,, . ~, .
Another solution to the problem is disclosed in U.S. Patent No. 3,639,121, York. The patentee discloses electrophotographic elements comprising a support, an intèrmediate conducting layer and an uppermost ~hotoconductive layer wherein electrical contact to the conducting layer is accomplished by coating the edge of the lamina~e with a ~onducting lacquer, whiah coating can be connected to ground to thereby electr~cally ground the intermediate conduct-ing layerO
` U.SO Patent No. 3,533,692, Blanchette et al, discloses a ` 10 photoconductive medium wherein the photoconductive layer is remov-ed ~rom an area to expose the conductive interlayer, with which contact is ~hen made with an elec~rode, or in which a conductive -metal strap ox rive~ is used to establish an electrical connection between the inte~layer and a conductive area coated on the back of ~ 15 ~ the laminateO _~
-: U.S. Pa~ent No~ 3,5S2,957, Hodges, discloses the use of .
i- mechanical devices such as straps, clamps and rivets applied to ~;
c an èxposed area of ~he conductive interlayer of an electrophoto-? graphic recording member to establish elect~ical connection with the interlayer~
~t Similarly, U.S~ Patent No. 3,574,615, Morse, discloses a con-.. ; . .
nection scheme as in Hodges except that an electrically-conductive elastomeric pad is in~erted between the clamp-electrode and the , .
exposed surface of the condu~tive interlayer.
Further, U S. Paten~ NoO 3,543,023, ~ellin et al, eliminates ~, the necessity for stLipping the dielectric or photoconductive layer away to expose the conductive interlayer, and discloses instead the use of a coLona discharge at the edge o the member to -~
establish the necessary electrical connection. -~
A disclosure relzted to thc ahove discussed York Patent appears ~-;
~' t ~' .
~ 106~759 in U.S. Patent No. 3,684,503, Humphriss et al. Humphriss et al achieves the necessary electrical connection by providing in a non-recording section of the element, a solid dispersion of a particul-ate electrically conducting material which extends from an external surace of the element through à portion of at least one of the layers overlying ~he conductive layer to electrically contact the conducting layerO Alternatively, the dispersion can extend into the element from an edge thereof.
Although the prior ar~ recording members generally function as intended, there has been a need for a technique of providing the necessary ele~trical ground connection to the conductive interlayer in an ~lectrostatographic recording member which is simple to fabricate and yet is effective in establishing good electrical con-nection with the conductive interlayer.
.. . . .
lS Ac~ording to the present invention there is provided an electro- `
;~ ~-statographic recording member which includes an electrically-insulat- _~
ing subst~ate, an electrically-condUctiVe layer overlying a first surfaoe of said subs~ra~e, an electrically-insulating outer layer ` overlying s~id ~onductive layer, said outer layer containing a photo-conductive material or being composed of a dielectric ma*erial of high volume resistivity, and means for establishing a ground connec-tion to said conductive layer; and wherein said ground connection means comprises a hole in a non-image area of said recording member ;~` extending from a surface thereof at least to said conductive layer `~ 25 and an electrically-conductive composition in said hole, said elec-trically-conductive composition comprising an adhesive and a suffi- -`
cient amount of an electrically-conduCtiVe pigment to make said com-position conductive, said composition being in electrical contact with said conductive layer and the exposed composition at the sur-face of said recording medium being covered by a oonductive metallic foil.
., ~ `
Thus, in the recording member of the present invention, there is formed at least one hole or aperture disposed through the entire thickness (or only partially therethrough) of the recording member in a non-image area thereof, which hole or aperture is sub-stantially completely filled with an electrically-conductive compo-sition comprising a plastic adhesive and a sufficient amount of an electrically-conducting pigment dispersed therein to make the com-position electrically conductive. A piece of metallic foil is employed to cover the exposed adhesive composition in the hole or aperture which has the effect of reducing the contact resistance between the exterior electrode and the electrically-conductive plas-tic material in the hole or aperture and further improves the per-. formance and reliability of the technique of the present invention.
According to the present invention, there is provided a lS process for establishing ground connection with an intermediate conductive layer of an electrostatographic recording member, said recording member comprising at least:
. an electrically-insulating substrate;
an intermediate conductive layer overlying a first . `:' . 20 surface of said substrate; and an electrically-insulating outer layer overlying said conductive layer, said outer layer containing a photoconductive ~, material or being composed of a dielectric material of high volume resistivity said process comprising:
(1) forming a hole in a non-image area of said recording member extending from a surface thereof to at least said intermediate conductive layer;
The present invention relates generally to electrophoto-graphic and electrostatic recording elements and processes for making the same; and more particularly to an improved technique for making an electrical ground connection to the intermediate electrically-conductive layer of such elements.
As used in the present specification, the term "electrostato-graphic" is intended to mean and cover both electrographic and ` ~' electrophotographic members.
~, Both types of recording elements are employed in reproduc-1 10 tion processes. Essentially, a latent image is formed in these ~ elements by providing an imagewise surface charge on an insulat-`, ing surface of the element, and thereafter developing the charg-`~3 ^~ ed latent image by means of an electrically-attractable material, ~ such as a "toner" (i.e., directionally charged colloid carbon - ~ 15 particles suspended in an insulating liquid or on a dry carrier).
Specifically, an electrophotographic element normally ~; comprises at least a substrate having coated thereon a layer containing a suitable photoconductor. The support layer i3 ma~`~e conductive either by the inclusion therein of electrically-con-ductive materials or by coating its surface ~the surface designed to receive the photoconductive layer) with an electrically-conductive material. Images are usually formed on the photo-conductive layer by first applying a uniform electrostati:c charge to the photoconductive layer by any suitable method, i 25 thereafter imaging the charged material by exposing it to light . ~ ` -1- ~
,'~ ~F
~ ~ .
. ~ .. . .. . . .. . .. .: . :, . . . .
-10f~6759 through a transparent master or by reflection from an opaque master which is being reproduced, thereby causing the photocon-ductive layer to become conductive, resulting in the dissipation of the charge in those areas of the layer exposed to light. In 5 a subsequent step, the charge pattern or latent image on the image layer is rendered visible by the application thereto of a colored or black electroscopic toner.
An electrographic recording element is similar in construc-tion to the electrophotographic element, with the photoconductive `` 10 layer being replaced with a high dielectric layer or a "charge retentive layer", that is, a material having a volume resistivity of not less than about 1012 ohm-centimeters. During this "print-; ing" process the electrical charge is applied in the image areas by a stylus and developed in the same manner as the electrophoto-` 15 graphic element.
With either type of element, it is often desirable during one or more of the processing steps (e.g., during charging or during toning) to establish a ground connection (to a reference potential) to the conductive layer of the recording element in .~ ~
`~ 20 order to create a highly conducting reference plane which is held at or near ground potential. For example, during the electrostatic charging of the photoconductive layer or during . ~.
the "printing" of the dielectric layer, the potential of the conducting layer has a tendency to build-up with respect to } 25 ground if it is not grounded. If this should occur, then there '`'t~ iS a less than desirable difference in potential between the areas truck by light and those not struck in an electrophotographic ' ~J element, and between the areas retaining or not xetaining "print"
charges in an electrographic element, resulting in a latent image 30 which is difficult to develop in the subseque~t toning step, .i ~ -2-.
, - . :
.
.. ..
1(366759 thereby resulting in copies which exhibit poor image quality, high background discoloration and/or poor contrast.
The prior art is replete with suggestions as to how to assure proper electrical grounding of the conductive layer in such elements. The classical approach is to provide an elec-trically-conductiv,e substrate which is easy and conventional if the substrate is a permeable or non-homogeneous substrate such as paper, since the substxate can be filled during manufacture with an electrically-conduc~ive pigment such as carbon black, or saturated with a solution of an ionic, hygroscopic substance, such as salt of a polyelectrolyte. However, there are disadvantages in such a technique. For example, the ionic hygroscopic impregnant is not generally effective in low porosity papers and the conduc-tivity it imparts is not stable but varies by several orders of ; 15 magnitude with the relative humidity o the environment. The use of carbon black as a filler insures the stability of the conduc- -` ~-`tivity, but may be unacceptable for aesthetic reasons, especially if a white substrate is desired. Moreover, it tends to weaken the ` substrate physically. Finally, it must be formulated into the ` 20 substrate at the time of manufacture and thus, cannot be applied to separately-made substrates. In addition, the primary dis-~ , .
advantage of this technique is that it cannot be applied to homo-geneous, impermeable substrates, such as extruded or cast films made from, for example, synthetic resins such as polyesters.
A further approach has been to provide a conductive inter-mediate layer between a non-conducting substrate and the photo-conductive or dielectric layer~ It has been suggested to con-; tact this conductive intermediate layer by removing the di- ~-electric or photoconductive layer from a limited area thereby exposing the intermediate conductive layer so that an electrode - -~
' ~
~ 1~)66759 can be physically contacted with the conductive layer. Other approaches have been to cut, punch, scratch or otherwise disrupt the physlcal integrity of the dielectric or photoconductive layer with an ele~trode which is forced into contact with the intermediate conductive layer.
- A further alternative of the prior art has been to provide a conductive pathway established from the conduative layer to the outer surface of the member where an electrode can establish contact with ito Since it is a part of the recording member, it 10 must be inexpensive to apply, inconspicuous, flexible (in flex- -ible recording elements) and of course both effective and ` reliable.
:;i An example of the prior art's solutions to this problem is ~ shown in U.S. Patent NoO 3,118,789, Wiswell et al. The patent ,,.; ~ ~
~ 15 discloses an electrophotographic recording member comprising a ... .
paper substra~e, a conductive interlayer and a photoconductive layer overlying the conductive interlayer with, optionally, a " conductive layer coating the back side of the papèr substrate.
The paper substrate is perforated with fine holes so that the ; .
`~ 20 conductive lacquer of which the conductive interlayer is composed ~ will penetrate through the paper during the coating ope~ation and `~
`j thus enable the establishment of an electrical connection there-~$ through to the conductive interlayer. A disadvantage with this 3 type o~ electrical connection is that it is not useful with im-permeable substrates such as polyester films. If the substrate , ~ iQ a film, and transparency and use as a photographic member is required, the methods suggestèd in the ~iswell et al Patent can--~ not be employèd tO establish contact with the conductive inter-layer because of the damage such a technique will cause to the film's optical characteristics~
.~. - ~. ,, . ~, .
Another solution to the problem is disclosed in U.S. Patent No. 3,639,121, York. The patentee discloses electrophotographic elements comprising a support, an intèrmediate conducting layer and an uppermost ~hotoconductive layer wherein electrical contact to the conducting layer is accomplished by coating the edge of the lamina~e with a ~onducting lacquer, whiah coating can be connected to ground to thereby electr~cally ground the intermediate conduct-ing layerO
` U.SO Patent No. 3,533,692, Blanchette et al, discloses a ` 10 photoconductive medium wherein the photoconductive layer is remov-ed ~rom an area to expose the conductive interlayer, with which contact is ~hen made with an elec~rode, or in which a conductive -metal strap ox rive~ is used to establish an electrical connection between the inte~layer and a conductive area coated on the back of ~ 15 ~ the laminateO _~
-: U.S. Pa~ent No~ 3,5S2,957, Hodges, discloses the use of .
i- mechanical devices such as straps, clamps and rivets applied to ~;
c an èxposed area of ~he conductive interlayer of an electrophoto-? graphic recording member to establish elect~ical connection with the interlayer~
~t Similarly, U.S~ Patent No. 3,574,615, Morse, discloses a con-.. ; . .
nection scheme as in Hodges except that an electrically-conductive elastomeric pad is in~erted between the clamp-electrode and the , .
exposed surface of the condu~tive interlayer.
Further, U S. Paten~ NoO 3,543,023, ~ellin et al, eliminates ~, the necessity for stLipping the dielectric or photoconductive layer away to expose the conductive interlayer, and discloses instead the use of a coLona discharge at the edge o the member to -~
establish the necessary electrical connection. -~
A disclosure relzted to thc ahove discussed York Patent appears ~-;
~' t ~' .
~ 106~759 in U.S. Patent No. 3,684,503, Humphriss et al. Humphriss et al achieves the necessary electrical connection by providing in a non-recording section of the element, a solid dispersion of a particul-ate electrically conducting material which extends from an external surace of the element through à portion of at least one of the layers overlying ~he conductive layer to electrically contact the conducting layerO Alternatively, the dispersion can extend into the element from an edge thereof.
Although the prior ar~ recording members generally function as intended, there has been a need for a technique of providing the necessary ele~trical ground connection to the conductive interlayer in an ~lectrostatographic recording member which is simple to fabricate and yet is effective in establishing good electrical con-nection with the conductive interlayer.
.. . . .
lS Ac~ording to the present invention there is provided an electro- `
;~ ~-statographic recording member which includes an electrically-insulat- _~
ing subst~ate, an electrically-condUctiVe layer overlying a first surfaoe of said subs~ra~e, an electrically-insulating outer layer ` overlying s~id ~onductive layer, said outer layer containing a photo-conductive material or being composed of a dielectric ma*erial of high volume resistivity, and means for establishing a ground connec-tion to said conductive layer; and wherein said ground connection means comprises a hole in a non-image area of said recording member ;~` extending from a surface thereof at least to said conductive layer `~ 25 and an electrically-conductive composition in said hole, said elec-trically-conductive composition comprising an adhesive and a suffi- -`
cient amount of an electrically-conduCtiVe pigment to make said com-position conductive, said composition being in electrical contact with said conductive layer and the exposed composition at the sur-face of said recording medium being covered by a oonductive metallic foil.
., ~ `
Thus, in the recording member of the present invention, there is formed at least one hole or aperture disposed through the entire thickness (or only partially therethrough) of the recording member in a non-image area thereof, which hole or aperture is sub-stantially completely filled with an electrically-conductive compo-sition comprising a plastic adhesive and a sufficient amount of an electrically-conducting pigment dispersed therein to make the com-position electrically conductive. A piece of metallic foil is employed to cover the exposed adhesive composition in the hole or aperture which has the effect of reducing the contact resistance between the exterior electrode and the electrically-conductive plas-tic material in the hole or aperture and further improves the per-. formance and reliability of the technique of the present invention.
According to the present invention, there is provided a lS process for establishing ground connection with an intermediate conductive layer of an electrostatographic recording member, said recording member comprising at least:
. an electrically-insulating substrate;
an intermediate conductive layer overlying a first . `:' . 20 surface of said substrate; and an electrically-insulating outer layer overlying said conductive layer, said outer layer containing a photoconductive ~, material or being composed of a dielectric material of high volume resistivity said process comprising:
(1) forming a hole in a non-image area of said recording member extending from a surface thereof to at least said intermediate conductive layer;
(2)inserting in said hole an electrically-conductive composition comprising an adhesive and a sufficient amount of an . 30 electrically-conductive pigment to make said composition electric-~ ally-conductive; and ., ~ -7-B
. - . .
`
... . . .
.
. - . .
`
... . . .
.
(3) bonding said adhesive composition in said hole to said recording member, said adhesive composition providing the sole electrically-conductive path between the conductive layer of the recording medium and a conductive metallic foil covering said adhesive composition.
Other advantages will be apparent to those skilled in the art from a consideration of the description of the preferred embodiments which follows hereinbelow, when taken in conjunction with the accompanying drawings, in which:
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.
:
:
,.
';~
~, ~
. .~
:
~ ~ -7a-,j 1~6759 . . .
Figu~es 1 and 2 cchematicaily show, in cross-section alterna-tive embodiments of con~entional electrophotographic recording members.
Figure 3 schematically illustrates a process for providing the imprcved electrical ground connection of the present invention.
Figure 4 schematically illustrates an electrophotographic re-cording member provided with the improved electrical connecting , means of the present invention.
`~ Figures 5 and 6 show alternative embodiments of the improved electrical conne~ting means of the present invention.
, As pointed out above, the present invention is applicable , ' equally to electrophotographic recording memb,ers as well as elec-trographi~ recording members, Examples of the former are shown in Figures 1 and 2 of the drawings. ~eferring to Figure 1, .
support layer 10 is ooated with a conductive layer 11 which' in , ,' ~turn is coated with a photo~onductive layer 12. The support is ' ~ -' normally ele~txi~al1y insulating and may comprise any of ~he well~
, ' known materials used fGr such purposes. Any conventional conduc-., ~ . ....
tive pigment may be employed to render layer 11 electrically con- ~''-ductive. Similarly, any ~onventional photoconductive material may ' ' be incorporated into layer 12 to render the same photoconductive, -' : ......................................................................... .
'; and any convent_onal binder can be employed in photoconductive , ' layer 12 and conducr;ve layer 11. '~
' To assure good adhesion between the conductive layer and the ' ; 25 support, if the two mater-als employed are not capable o~ good ad-' hesion to one another, a bcnding layer or subbiny may be interposed between conductive layer 11 and support 10, as is conventional in ; the art.
Figure 2 shows an alternative embodiment wherein on the back side of support 10 is disposed a conductive back layer 13. The ~3 ' ' ,~ .
~' 106675g latter layer functi^r,s as the grounding layer for the element and replaces an exterior electrode which is used with the recording member shown in Figure l.
;: Electrographic re~ording members are similar in structure to the electrophotographic recording members shown in Figures 1 and 2.
In essence, ~he pho~oconductiYe laye~ 12 of the electrophotographic recording member is replaced with a dielectric layer having a high volume resistivity, normally a minimum of 1012 ohm-centimeters.
Any conventional dielectric material can be employed as is obvious to those skilled in the art.
With either the electrogxaphic or the electrophotographic re-:: , cording members, it is important to electrically connect the con-ductive layer 11 to gro-~nd during the -harging and development of `` the uppermost layerc If the conductive layer is not electrically ~- .
, lS grounded, the difference in potential between the upper layer and -~
the conductive layer diminishes as a result of build-up of charge in the conducti~e layer. The mcre equal charge d..minishes the quality and clarity of the image since the imaged areas in the upper layer have les~ or a tendency to selectively attract the developing materiàl, as compared to the non-imaged areas, due to ` the small di~ference in potential between the upper layer and the conductive layer. If the conductive layer is properly grounded, the difference ln potential is signi~icant and therefore the imaged ` :`
areas are easily c~pable of attracting the electrically-directed ;~ 25 developlng material, the ~.oner, thereby producing a clear image.
The improved electrical ground connection of the present inven-~' tion possesses numerous advanta~es over the priox art. Essentially, electrical ground connecr.ion to the electri.cally-conduc~ive inter-mediate layer in the record~ng meI~er is made by first punching or othexwise cutting a hoie in a non-image area of the xecoxding membex ..9_ ., .
: : ,, .. : : : . .
,: : ~ ... . . . . . .
~ 1066759 and filling the hole with and bonding thereto an electrically-con-ductir.g plastic adhesive thereby establishing both a mechanical bond with the walls defined by the hole and an electrical contact with the exposed conductive intermediate layer therein. The plastic ad-hesive ~omposition may or may not contain a solvent for the plasticmaterial, the adhesive without the sol~ent being preferred in order to eliminate the need for drying the adhesive and to avoid possible shrinkage problems a~socia~ed with the loss of solvents from the adhesive composition as the composition dries. Further, any known adhesive c~mposition can be employed in the practice of the present invention without limitationO
~n a preferred embodiment, a metallic foil coated with the ad-.. . .
hesive composition of the present invention can be applied to ~oth ~-sides ~f the record~ng member over th~ hole ~if the hole extends thro~gh the entire thi~kne~s) and the adhesive coating may be ~forced into rhe hole fx~m both sides to form the electrical connec- -`-tion of the present invention.
~` Alternatively, ins~ead of punching or cutting a hole through the re~ording member, ~he photoc~nductivè or dielectric coating may be selectively removed from a certain area such as by using a solv-ent, or by scoring, scl~atching or otherwise destroying the physical ~-integrity of the coat~ng, to expose the underlying conducting intermediate layerO The adhesi~e composi~ions of the present in-vention can then be inserl:ed intc the resulting channel, which `, 25 extends at leas~ tc the conductive intermediate layer. This embodi-ment may also he utllized with the adhesive-coated metallic foil.
To be more specific, the first step in the p,rocess for form-ing the improved electrical connection of the present invention is to cleanly p~nch or otherwi e cut a hole in the recording member is not critical as long as it i5 în a non-image area thereof. Pre-111 1(~66759 ferably, the hole should be cleanly sheared or punched entering from the side of the member on which the photoconduc~ive or di-electric layer is coated. The hole should be punched as neatly as possible in order ~o preserve the integrity and continuity of the electrically-conductive intermediate layer around the edge of the hole.
The adhesive that is used to fill the hole can be any conven-tional plastic adhesive known to those skilled in the art. The adhesive is made electrically conductive by mixing therein an electrically conducting pigment such as carbon black; graphite;
acetylene blac~; metal powders such as nickel, silver, etc.; con-ductive zinc oxide, pcwdered se~i-conductor material; and the like.
Generally, the pigment employed is not critical as long as it is - electrically conductive so as to provide the adhesive with a sufficient conductiYity to prevent build-up of potential in the conductive layer~ Normally, the adhesive has a maximum resistance value of about 108 to 1016 ohm~ cm. The resistance of the conduc-tive adhesive ~hould be less than 1011 ohm cm., and it can be varied by changes in the formulation. The total resistance of the entire insert should not be greater than 109 ohms.
Any suitable mixing technique can be employed to disperse the conductive pigment through the adhesive. As an example, a ball milling technique can be employed to uniformly disperse the conduc- -tive pigment through the adhesive composition.
- 25 The adhesive e~ployed ~in the embodiment which requires a solvent) is not limited and includes any Xnown adhesive composi-tion which is compatible with the recording members of the inven-tion, is capable of being made conductive by the inclusion therein of a conductive pigment and is capable of being applied from a solvent solution or dispersion.
Typical solvent-free adhesive formulations include those adhesives which are known to those skiIled in the art and include without limitation hot_melt a & esives and pressure-sensitive ad-hesives. A typical example of the former is as follows, the parts being parts by weight:
Hot-Melt Adhesive Component Parts Kraton 1101 10.00 Shawinigan Black Acetylene2.00 Plastanox 2246 0.05 Plastanox LTDP 0~05 Toluene 55.00 Methyl Ethyl Ketone 32.90 ,. 100 00 '' To obtain a solvent-free, hot_melt adhesive, the formulation of the example is coated on an all~;num foil and the solvent is removed in a drying oven. The film thickness of the resulting hot-melt coating is kept in the neighborhood of 1/2 to l/3 the thickness of the electro-` photographic or electrographic member to which the coated foil is to be ` 20 applied by heat and/or pressure. The tbickness of the coating may be ~ adjusted to the desirability of the amount of "flash", i.e., the flow !`. of the hot-melt surrounding the aluminum foil used as a covering material in such a laminate.
The Kraton I101 is a styrene-butadiene copolymer and is available from the Shell Chemical Company. The Shawinigan Black Acetylene is available from the Monsanto Chemical Company, and oom-prises essentially acetylene black. Both Plastanox components are av~;lable from American Cyanamid and are anti-oxidants used to d prevent embrittlement of the resins in which they are employed.
; 30 Plastanox LTDP is dilaurylthiodipropionate and n astanox 2246 is '' ' '' '`~:
Regi~tered Trademark ~ :' -12_ 2,2'-methylenebis-(4-methyl-6-tertiarybutylphenol). The ~urface resistance of the above hot-melt adhesive is 8.0 x 102 ohm~ per square centimeter. The relationship between surface resistance and resistivity is disclosed in columns 2 and 3 of York 3,639,121, and the curface resistance given herein may be determined by the method described in said patent.
A typical example of a pressure-sensitive adhesive is as follows:
` Pressure-Sen~itive Adhesive - 10 Component Parts Monsanto RA 1151 23.0 Shawinigan ~lack Acetylene 2.0 Ethyl Acetate 40.0 Toluene 35.0 100.O
The Monsanto RA 1151 is a resin available from the Monsanto Chemical Company and cQmprises about 35% solids, with the balance being a solvent comprising ethylacetate (55~) and toluene (45~).
The surface resistance of the pressure-sensitive adhesive described above i~ 2.0 x 102 ohms per 3quare centimeter.
Suitable hot-melts that are conductivized by pigments dispera-ed in solvents and coated on the foil and dried may be chosen from the following:
Solid fatty polyamides, poly(vinyl acetate) - rosin, ethylene -vinyl acetate copolymer, petroleum wax, laminating grade micro-crystalline wax, rosin or ester gum, vinyl acetate-crotonic acid, beta-pinene polymer, polyvinylacetate, polyethylene, paraffin wax, dimerized rosin, modified rosin or rosin ester, ethyl cellulose, e~ter wax, paraffin mineral wax, polyterpene, polyterpene urethane, B-pinene resins, terpene wax - polyethylene covinyl-acetate (Elvax ,~
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260 DuPont), and the like.
If the adhesi~e composition is applied using a solvent, after the adhesive compcsiticn solution is inserted into the hole in the recording member, it is then dried to establish a firm mechanical bond with the ins~de of the hole and also to establish the electrical contact with the exposed conductive layer on the inner surface of the hole. The hoi-melt type of solvent-free adhesive is simply hea~ed ~o mel~ the same and it can be easily flowed into the hole.
It i~ not necessary to heat the pressure-sensitive adhesive since the application of pxessure alone is sufficient to assure that the adhesive completely fills the hole in the recording member.
The particle size of the conductive pigment is not at all critical, and any conventionally-sized conductive pigment can be employed~ Gener~lly, the particle size of the conductive pigment will vary depending upon the particular material used and generally ranges from 5 to 200 millimicrons, although it is not intended to limit the particle size of the ~onductive pigment used in the pres-ent invention to th~s range. Those skilled in the art can determine the optimum parti~le s~ze depending upon the desired surface resistance, the thick~ess of the adhesive, the amount of pigment contained in the adhesive, and various other considerations.
~ he amoun~ of the conductive pigment that is present in the adhesive varies from the minimum amount necessary.to make the ad-hesive conductiv~ to a maximum amount which is limited only by the -25 ability of the adhesive to retain the pigment dispersed or mixed ~-therein. Generally, the amount of conductive pigmen~ will vary from a minim~m of 0.5 par~s by weight to a maximum of 15 parts by weight, based on the ~eigh~ of the adhesive composition. A mixture of conduc~ e pigments may also be employed depending upon the end 30 use. ` -, : .
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The solvent-free adhesives are preferred in the practice of the present in~ention sin~e the need for drying is eliminated and the shrinkage problems associated with the loss of solvents or possible solvent retention therein in the event o~ incomplete dxy-ing, are avcided~ The plasticity necessary for a solvent-free ad-hesive may be obtained either by melting the adhesives at the time of application ~in the case of a hot-melt adhesive) or by formulating i~ with various polymeric materials, tackifying agents, etc. and applying it as a pressure-sensitive adhesive. Since these other ingredients are not part of the present invention per se, and since those skilled in the art can readily prepare such compositions, they will not be described in aetail here for purposes of bre~ity.
In a preferred embodiment, an adhesive-coated metallic foil ;-` lS is employed to fill the hole in the recording member. Rèference ~ `r ~ig made to Figures 3 and 4 which show this preferred emhodiment.
; ~; Figure 3 shows a ~ecording member compri~ing a substrate or support 14, an intermediate conductive layer lS and an uppermost .
pho~oconductive layer 16, or dielectric layer. A hole 17 is pro-vided in a non-image area of the recording member, thereby expos-ing the intermediate conductive layer 15 on the inner sùrface of the hole. As shown in Figure 3, two piece~ of adhesive-coated metallic foils 18 and 21, generally, are disposed on opposite ends ' of the hole. The adhesive-coated metallic foil gene~ally com- -prises a thin metallic foil 19 having a coating 20 thereon of the adhesive. The metallic foil can be any conducting metallic foil, such as aluminum, copper, tin, etc., and the thickness of the adhesive can be regulated to provide a complete filling of the hole. The adhesive-coated foil pieces are inserted into the hole 30 such as by the use of pressure as indicated in Figuxe 3. If a hot- -' .. ~ . ~ ; , .. . . .
~: `
~ 1~ 1066759 ~ melt adhesive is employed, the only pressure necessary is that ¦ sufficient to push the heated adhesive material of the upper and ` lower pieces of adhesive-coated foils into the hole for contact and fusion. Figure 4 shows the finished product after the ad-` S hesive-coated foil pieces axe inserted into the hole punched in the recording member. The advantage of using the adhesive-coated foil pieces is that the contact resistance between the exterior elec-trode and the conductive adhesive is reduced thereby providing im-proved perfo~mance and reliability. It is further possible to easily extend the conducti-e area from the hole over the surface of the recording member to whatever contact area and shape is re-qu-red. Moreover, the metallic foil is more durable and in parti-cular mcre resistant to abrasion than the exposed conductive ad-'~ hesive, and in the case of the pressure-sensitive adhesive, it 15 covers and pxotects the tacky surface frcm dirt and prevents its - :
inadvertent a~hesion or blocking to other surfaces. :-:......................................................................... .:
~` Although ~igures 3 and 4 show the use of two adhesive-coated foil pieces, ~he ir.vention is equally as applicable to the use of -~ only a single piece appl~ed from only one side of the recording mem-ber. The adhesive-coated foil can be conveniently made by pre-coat-ing one side of the metallic foil with the adhesive composition, for example, from a sol~ent solation of the same. After drying, the ; coated foil may be heated or slit and wound up to ~he desired size.
.~ ~. .. ~ . .
In the case of the pressu~e-sensitive adhesive, it will usually be necessary to protect the exposed surface of the adhesive such as ~` by the use of the adhesive-coated metallic foil. The use of the adhesive-coated foil provides the additional advantage that the pre-coated foil can be employed to apply a metered amount of the re- --~
~ quired adhesive to the hole in ~he recording member.
-~ 30 The use of two adhesive-coated foil pieces is preferred since ~ -16-, .
~066759 not only will a bond be established with the inside of the hole and with the adjQining surface areas underlying both.pieces of foil, but the adhesive surfaces will meet in the hole and bond both pieces of foil flrm`y to each other, which substantially strengthens the electrical connection. A further advantage o~ using two ad-hesive-coated foil pieces is evident with electrostatographic re-cording m~ers ~hich have a conductive back layer as illustrated in Figure 2. It is func~ionally important to provide electrical con-nection between the intermediate conductive layer ll ~referring now ~o Figure 2) and the conductive ~ack layer 13~ The use of the `~ technique shown in Figures 3 and 4 is tery effective for accomplish-- ing this purpose. The adhesive-coated foil which is applied simultaneously to the back of the member with the application of . the adhesive-coated foil to the front of the member simultaneously establishes contac~ with the interlayer and with the conductive .~ack layer surrounding ~he punched hole.
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Altern3tive emb~dimen~s of ~he improved electrical connection technique of ~he present invention are shown in Figures 5 and 6.
Figure 5 shows a recording member ccmprising a support 21, an intermediate layer 22 which is conductive and an uppermost layer 23 which compr~ses either a photoconductive material or a high di-electric materialc A "slot" or "hole" 24 can be pxovided through the uppermost layer 23 and intermediate layer 22 of the recording member as shown in Figure S. This can be done by any suitable 25 technique, such as by scoring or scratching the surface, or general- -ly by using any technique which destroys the physical integrity of ;.~.
the uppermost layer 23 down to a point into and through the inter-mediate conductive 12yer 220 This can be performed for example by - the use of a solvent which selectively dissolves the upper layer 23 and the conductive layex 22, thereby providing access to the con-.
' -1'~7 ' ' . 10667~9 ductive layer 22~ Whlle a condu~tive adhesive composition by itself can be filled into this slot or hole, it is preferred to use the ad-hesive-coated foi~ as shown in Figure 5, the adhesive being designat-ed 26 and the foil 25o Figure 6 sho~s a related embodiment wherein the slot or hole 30 is only made in the uppermost layer 29 down to but not into the con-ductive layer 28, which overlies support 27. The adhesive 32 con-tacts conductive layer 28 at the bottom of the slot 30, and the ad-hesive 32 is shown in Figure 6 as being covered by a foil member 31.
The improved technique of the present invention is advantageous compared to methods and techniques taught in the prior art. For example, the technique cf the present invention increases the options one has for making contact with an electrode in the appa-` ratus emplcyed in imaging the recording member, in that the loca-tion of the hole is not limited to an edge and any non-image area can be chosen, and in addition the front or back of the member can be contacted. Further, the connection of the present invention provides an effective in~erconnection between the interlayer and the back coat in recording members having a condu~tive back layer. -Further, since the connection is made with an adhesive, it is flex-` ible and durable, especially with the use of the metallic foil. The present inventicn also makes it unnecessary to remove or render conductive the upper laysr in order to establish contact with the intermediate conductive layer.
i 25 If a hot-melt or pressure-sensitivs adhesive is used, the problems associated with the use of a solvent are avoided as indi-cated above. If an adhesive-coated foil is employed, this provides a convenient and effec~ive mannex of metering and applying the con-ductive adhesive, as well as providing a low contact resistance con-nection assuring better and more reproducible image quality. Because . .
~ i . ~066759 of t~he hi~h conductivity of the foil, it can be used in any desired size or shape~ The preferred ~ize is one having a surface area of from about 0.1 cm2 to about 3 cm2, and is easily applied in squares or discs Lastly, if a pre~sure-sensitive adhesive-coated on foil is employed, it is easy to apply, no heat being necessary, thereby avoiding the risk of thermal damage to the recording member.
The present invention relates speci~ically to the improved technique ~or making ground connection to the electrically-conductive intermediate layer of the reco~ding members above described. The ` 10 inventicn does no~ per se reside in the composition, basic structure or other characteristics of the recording member per se~ The pres-ent invention i~ expressly applicable to any conventional electro-`~ statographic record ng member having at least three layers, a support wh~ch is electrically insulati~g, an electrically conduct-ing layer o~erlying the suppoxt and an uppermost layer which is either pho~oconducti~e (_n the case of ele~trophotographic members) or a dielectr~c material ha~ing a high volume resistivity (in the case of an electrographic recording member). An optional fourth ` ~-layer is the conductive baek layer on the~opposite side of the 20 support from ~he in~ermedia~e conducting layer and either the pho~o- `
, conductive ¢r dielectric layer~.
One ckilled in the art can select appropriate materials to form these conventional recording members. Thus, as the support various materials can be u~ed, such as paper or synthetic resins ~25 such as polyesters (e~g~, polyethylene terephthalate) or cellulose " esters ~e.g~, cellulose acetate~ and the like. Preferably, the support is formed of a transparent material such as polyethylene terephthalate or cellulose acetate when the recording member is to be used as a maste~ in a photographic reproduction process where the information imaged thereon is to be exposed from ~he back side -19- , ., . . ~ ~
1(~66759 of the re~ording member. The thickness of the support may vary depending upon the end use, there being no particular limitation as to the thickne~s of the support.
The intermediate conducting layer which i9 coated onto the support, evaporated thereon or formed as a part of the upper ~ur-face of the support, can comprise literally any conducting compo-sition. Normally, the conducting layer comprises an electrically-conducting material dispersed in a binder therefor and coated onto the support, such as from a ~olvent solution thereof. ~he elec-trically-conducting material may be the same as that used in appli-cant's adhesives and the binder may be polymeric in nature, such as polyolefins, vinyl polymers such as polyvinyl chloride, acryl-ates, methacrylates, polyesters, styrene-butadiene copolymers, polyvinyl acetate, polystyrene, polyamides, polycarbonates, copoly-mers thereof, etc. Illustrative of the electrically-conducting materials which may be employed in such intermediate conducting layers are ionizable polyelectrolyte salts, polymeric quaternary ammonium salts, polystyrene ~ulfonic acid salts, salts of copoly-mers of vinyl compounds with maleic acid, Calgon 261, vinyl acetate, and metal coatings deposited by sputtering ox vacuum deposition to r~nder the component electrically conducting. The thickness of the conducting layer is not particularly limited, and those skilled in the art can vary the thickness as desired.
In an electrophotographic element, ~he upper layer is photo-conductive and normally comprises an organic or inorganic photocon-ductor dispersed in a binder therefor. Any or~ani¢ or inorganic `~ photoconductor i8 useful in the electrophotographic elements of the present invention. Typical organic photoconductors include, for example, qu~nacridones, carboxamides, carboxanilides, triazines, anthraquinones, ano compounds, salts and lakes of compounds derived ., , . , :
.
E~
` ~066759 from 9-phenylxanth~ne, dioxazines, lakes of fluorescein dyes, pyrenes, phtha'ocyanines, ~Rtal salts and lakes of azo dyes, poly-vinyl carbaæole, substit.uted phenylene diamines, and the like.
Several substituted phenylene diamines axe described in detail in ~.S. Patents 3,314,788 issued April 18, 1967 to Mattor and 3,615,404 issued October 26, 1971 to Price et al. The amount of the photoconductive material in the photoconductive layer is at least the minimum required to render the layer photoconductive, with the amount generally varying from 5% to 65% by weight, based on the weight of the photoconduc~ive layer. The disclosures of the aforementioned Mattor and Pxice et al Patents are hereby in-corporated herein by reference for their disclosures of suitable ` photocondu~tive ma~erials.
Also operab'e in ~he photoconductive layer, and preferred, are sensitizing compounds which further increase the sensitivity ~of the photoconductive ma~erials to light of certain wavelengths.
Any conventional sensitizing compounds may be employed in the photoconductive layer of the present invention to be used in com-bination wi~h related photc~onduetive materials to further in-crease the sensitization of the photoconductive layer. The amountof the sensitizer in the photoconductive layer can vary within wide ranges, with the optimum concentration in any given case vary-- ing with the speeific phcto~onducto~ employed and the sensitizing compound usedO Normally, sensitlzers are employed in amounts of :1 .
2S from 0.05% to 0O3% by weight, based on the weight of the photocon- -ductive layer, or about 3 ml. of a 1% solution of the sensitizer ;-for each 25 grams of photoconductor employed. ~-;
. The photoconductive layer may be coated onto ~he electrically-; conductive inte~mediate layer such as frsm a solvent solution of the composition. ~he solvent will o~ course vary depending upon the -21- ~
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. ~066759 photoccnductor and ser.sirizer, if one is present, and the binder.
Those ~killed in the art can certainly practice the present inven-tion using ~arious solven~s wlth a m-nimum amount of experimentation.
With the ele~trographic recording elements of the present in-vention, the supp~rt and intermediate electrically-conductive layers would be the same and can be formed of any of the above described materials. The upper layer is formed of a material having a high volume resistivity, prefexably a minimum of 1012 ohm-centimeters.
Typical materials are as follows: styrenebutadiene copolymers;
silicone resins; styrene-alkyd resins; silicone alkyd resins; soya-alkyd resins; poly(v~nyl chloride); poly(vinylidene chloride);
vinylidene chloride-acrylonitr * e copolymers; poly~vinyl acetate);
`i vinyl acetate-vinyl chloride~copolymers; poly(vinyl acetals), such as polytvinyl butyral); polyacrylic and methacrylic esters, such as polytmethylmetha~rylate), poly(n-butylmethacrylate), poly~iso-butyl methacrylate), etcO; polystyrene, nitrated polystyrene; poly-methylstyrene; isobutylene po1ymers; polyesters, such as poly(ethyl-enealkaryloxyalkylene terephthalate~; phenol-formaldehyde resins;
ketone resins; polyamide; polycarbcnates; polythiocarbonates; poly-(ethyleneglycol-co-b~shydroxyethoxphenyl-propane terephthalate);
etc. Methods~of making resins o~ this type have been described in the prior ar~ for example, styrene-alkyd resins can be prepared according to the method described in U.S. Patents 2,361,019 and 2,250,423. Suitable resins of the type contemplated for use in the photoconductive layers of the invention are sold under such trade J' names as Vitel* PE-101, Cymac*, Piccopale* 100, and Saran* F-~20 -and Lexan* 105~ O~her ~ypes of binders which can be used in the photoconductive layers of the invention include such materials as paraffin, mineral waxes, etc. ~-With regard to the electri~ally-conductive back layer used in *Registered ~rademark ~22-v .. . . . .
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. : . . 1066759 certain embodimenrs, this can be formed of materials which are similar to or the ~ame as the _ntermedia~e electrically-conductive layer. In addikicn, both of these conductive layers can be formed of electrically-~onducti~e materials per se instead of conductive pigments dispersed in a binder. For example, U~S. Patent No.
; 3,011,918 discloses a oonductive resinous polymer, polyvinyl benzyl trimethyl ammonium chloride, whi~ch is itsel~ conductive. Alterna-tively, these layers may be made by printing or coatin~ the support suxface with an elec~rocondu~tive ink, or a metal or a suitable semi-conductor may be vacuum deposi~ed or sputtered onto the support. See, for example, U.S. Patent Nos. 3,207,625; 2,756,16i;
3,148,083; 3,245,833; and 3,428,451.
` ` As will be apparent from th& above description, the preferred compositions are ~hose which provide a flexible recording member, r ~ 15 particularly thcse matexials are preferred whi~h are flexible and transparent to prov-de a transparent recording member. In addition, it is preferred that the suppor~ be substantially electrically insu~ating in nature.
. . . .
While the inv~ention has been shown and described with reference 20~ to p~eferred embodiments thereof, it is to be expressly understood ` that ~arious changes and modîfi~ations may be made without departing from the spirit and s~ope of 'the present invention, as defined in ;
~ the appended ~lai~. :
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Other advantages will be apparent to those skilled in the art from a consideration of the description of the preferred embodiments which follows hereinbelow, when taken in conjunction with the accompanying drawings, in which:
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Figu~es 1 and 2 cchematicaily show, in cross-section alterna-tive embodiments of con~entional electrophotographic recording members.
Figure 3 schematically illustrates a process for providing the imprcved electrical ground connection of the present invention.
Figure 4 schematically illustrates an electrophotographic re-cording member provided with the improved electrical connecting , means of the present invention.
`~ Figures 5 and 6 show alternative embodiments of the improved electrical conne~ting means of the present invention.
, As pointed out above, the present invention is applicable , ' equally to electrophotographic recording memb,ers as well as elec-trographi~ recording members, Examples of the former are shown in Figures 1 and 2 of the drawings. ~eferring to Figure 1, .
support layer 10 is ooated with a conductive layer 11 which' in , ,' ~turn is coated with a photo~onductive layer 12. The support is ' ~ -' normally ele~txi~al1y insulating and may comprise any of ~he well~
, ' known materials used fGr such purposes. Any conventional conduc-., ~ . ....
tive pigment may be employed to render layer 11 electrically con- ~''-ductive. Similarly, any ~onventional photoconductive material may ' ' be incorporated into layer 12 to render the same photoconductive, -' : ......................................................................... .
'; and any convent_onal binder can be employed in photoconductive , ' layer 12 and conducr;ve layer 11. '~
' To assure good adhesion between the conductive layer and the ' ; 25 support, if the two mater-als employed are not capable o~ good ad-' hesion to one another, a bcnding layer or subbiny may be interposed between conductive layer 11 and support 10, as is conventional in ; the art.
Figure 2 shows an alternative embodiment wherein on the back side of support 10 is disposed a conductive back layer 13. The ~3 ' ' ,~ .
~' 106675g latter layer functi^r,s as the grounding layer for the element and replaces an exterior electrode which is used with the recording member shown in Figure l.
;: Electrographic re~ording members are similar in structure to the electrophotographic recording members shown in Figures 1 and 2.
In essence, ~he pho~oconductiYe laye~ 12 of the electrophotographic recording member is replaced with a dielectric layer having a high volume resistivity, normally a minimum of 1012 ohm-centimeters.
Any conventional dielectric material can be employed as is obvious to those skilled in the art.
With either the electrogxaphic or the electrophotographic re-:: , cording members, it is important to electrically connect the con-ductive layer 11 to gro-~nd during the -harging and development of `` the uppermost layerc If the conductive layer is not electrically ~- .
, lS grounded, the difference in potential between the upper layer and -~
the conductive layer diminishes as a result of build-up of charge in the conducti~e layer. The mcre equal charge d..minishes the quality and clarity of the image since the imaged areas in the upper layer have les~ or a tendency to selectively attract the developing materiàl, as compared to the non-imaged areas, due to ` the small di~ference in potential between the upper layer and the conductive layer. If the conductive layer is properly grounded, the difference ln potential is signi~icant and therefore the imaged ` :`
areas are easily c~pable of attracting the electrically-directed ;~ 25 developlng material, the ~.oner, thereby producing a clear image.
The improved electrical ground connection of the present inven-~' tion possesses numerous advanta~es over the priox art. Essentially, electrical ground connecr.ion to the electri.cally-conduc~ive inter-mediate layer in the record~ng meI~er is made by first punching or othexwise cutting a hoie in a non-image area of the xecoxding membex ..9_ ., .
: : ,, .. : : : . .
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~ 1066759 and filling the hole with and bonding thereto an electrically-con-ductir.g plastic adhesive thereby establishing both a mechanical bond with the walls defined by the hole and an electrical contact with the exposed conductive intermediate layer therein. The plastic ad-hesive ~omposition may or may not contain a solvent for the plasticmaterial, the adhesive without the sol~ent being preferred in order to eliminate the need for drying the adhesive and to avoid possible shrinkage problems a~socia~ed with the loss of solvents from the adhesive composition as the composition dries. Further, any known adhesive c~mposition can be employed in the practice of the present invention without limitationO
~n a preferred embodiment, a metallic foil coated with the ad-.. . .
hesive composition of the present invention can be applied to ~oth ~-sides ~f the record~ng member over th~ hole ~if the hole extends thro~gh the entire thi~kne~s) and the adhesive coating may be ~forced into rhe hole fx~m both sides to form the electrical connec- -`-tion of the present invention.
~` Alternatively, ins~ead of punching or cutting a hole through the re~ording member, ~he photoc~nductivè or dielectric coating may be selectively removed from a certain area such as by using a solv-ent, or by scoring, scl~atching or otherwise destroying the physical ~-integrity of the coat~ng, to expose the underlying conducting intermediate layerO The adhesi~e composi~ions of the present in-vention can then be inserl:ed intc the resulting channel, which `, 25 extends at leas~ tc the conductive intermediate layer. This embodi-ment may also he utllized with the adhesive-coated metallic foil.
To be more specific, the first step in the p,rocess for form-ing the improved electrical connection of the present invention is to cleanly p~nch or otherwi e cut a hole in the recording member is not critical as long as it i5 în a non-image area thereof. Pre-111 1(~66759 ferably, the hole should be cleanly sheared or punched entering from the side of the member on which the photoconduc~ive or di-electric layer is coated. The hole should be punched as neatly as possible in order ~o preserve the integrity and continuity of the electrically-conductive intermediate layer around the edge of the hole.
The adhesive that is used to fill the hole can be any conven-tional plastic adhesive known to those skilled in the art. The adhesive is made electrically conductive by mixing therein an electrically conducting pigment such as carbon black; graphite;
acetylene blac~; metal powders such as nickel, silver, etc.; con-ductive zinc oxide, pcwdered se~i-conductor material; and the like.
Generally, the pigment employed is not critical as long as it is - electrically conductive so as to provide the adhesive with a sufficient conductiYity to prevent build-up of potential in the conductive layer~ Normally, the adhesive has a maximum resistance value of about 108 to 1016 ohm~ cm. The resistance of the conduc-tive adhesive ~hould be less than 1011 ohm cm., and it can be varied by changes in the formulation. The total resistance of the entire insert should not be greater than 109 ohms.
Any suitable mixing technique can be employed to disperse the conductive pigment through the adhesive. As an example, a ball milling technique can be employed to uniformly disperse the conduc- -tive pigment through the adhesive composition.
- 25 The adhesive e~ployed ~in the embodiment which requires a solvent) is not limited and includes any Xnown adhesive composi-tion which is compatible with the recording members of the inven-tion, is capable of being made conductive by the inclusion therein of a conductive pigment and is capable of being applied from a solvent solution or dispersion.
Typical solvent-free adhesive formulations include those adhesives which are known to those skiIled in the art and include without limitation hot_melt a & esives and pressure-sensitive ad-hesives. A typical example of the former is as follows, the parts being parts by weight:
Hot-Melt Adhesive Component Parts Kraton 1101 10.00 Shawinigan Black Acetylene2.00 Plastanox 2246 0.05 Plastanox LTDP 0~05 Toluene 55.00 Methyl Ethyl Ketone 32.90 ,. 100 00 '' To obtain a solvent-free, hot_melt adhesive, the formulation of the example is coated on an all~;num foil and the solvent is removed in a drying oven. The film thickness of the resulting hot-melt coating is kept in the neighborhood of 1/2 to l/3 the thickness of the electro-` photographic or electrographic member to which the coated foil is to be ` 20 applied by heat and/or pressure. The tbickness of the coating may be ~ adjusted to the desirability of the amount of "flash", i.e., the flow !`. of the hot-melt surrounding the aluminum foil used as a covering material in such a laminate.
The Kraton I101 is a styrene-butadiene copolymer and is available from the Shell Chemical Company. The Shawinigan Black Acetylene is available from the Monsanto Chemical Company, and oom-prises essentially acetylene black. Both Plastanox components are av~;lable from American Cyanamid and are anti-oxidants used to d prevent embrittlement of the resins in which they are employed.
; 30 Plastanox LTDP is dilaurylthiodipropionate and n astanox 2246 is '' ' '' '`~:
Regi~tered Trademark ~ :' -12_ 2,2'-methylenebis-(4-methyl-6-tertiarybutylphenol). The ~urface resistance of the above hot-melt adhesive is 8.0 x 102 ohm~ per square centimeter. The relationship between surface resistance and resistivity is disclosed in columns 2 and 3 of York 3,639,121, and the curface resistance given herein may be determined by the method described in said patent.
A typical example of a pressure-sensitive adhesive is as follows:
` Pressure-Sen~itive Adhesive - 10 Component Parts Monsanto RA 1151 23.0 Shawinigan ~lack Acetylene 2.0 Ethyl Acetate 40.0 Toluene 35.0 100.O
The Monsanto RA 1151 is a resin available from the Monsanto Chemical Company and cQmprises about 35% solids, with the balance being a solvent comprising ethylacetate (55~) and toluene (45~).
The surface resistance of the pressure-sensitive adhesive described above i~ 2.0 x 102 ohms per 3quare centimeter.
Suitable hot-melts that are conductivized by pigments dispera-ed in solvents and coated on the foil and dried may be chosen from the following:
Solid fatty polyamides, poly(vinyl acetate) - rosin, ethylene -vinyl acetate copolymer, petroleum wax, laminating grade micro-crystalline wax, rosin or ester gum, vinyl acetate-crotonic acid, beta-pinene polymer, polyvinylacetate, polyethylene, paraffin wax, dimerized rosin, modified rosin or rosin ester, ethyl cellulose, e~ter wax, paraffin mineral wax, polyterpene, polyterpene urethane, B-pinene resins, terpene wax - polyethylene covinyl-acetate (Elvax ,~
,, ,: . , .: .. ~ .. .
;`~ <
260 DuPont), and the like.
If the adhesi~e composition is applied using a solvent, after the adhesive compcsiticn solution is inserted into the hole in the recording member, it is then dried to establish a firm mechanical bond with the ins~de of the hole and also to establish the electrical contact with the exposed conductive layer on the inner surface of the hole. The hoi-melt type of solvent-free adhesive is simply hea~ed ~o mel~ the same and it can be easily flowed into the hole.
It i~ not necessary to heat the pressure-sensitive adhesive since the application of pxessure alone is sufficient to assure that the adhesive completely fills the hole in the recording member.
The particle size of the conductive pigment is not at all critical, and any conventionally-sized conductive pigment can be employed~ Gener~lly, the particle size of the conductive pigment will vary depending upon the particular material used and generally ranges from 5 to 200 millimicrons, although it is not intended to limit the particle size of the ~onductive pigment used in the pres-ent invention to th~s range. Those skilled in the art can determine the optimum parti~le s~ze depending upon the desired surface resistance, the thick~ess of the adhesive, the amount of pigment contained in the adhesive, and various other considerations.
~ he amoun~ of the conductive pigment that is present in the adhesive varies from the minimum amount necessary.to make the ad-hesive conductiv~ to a maximum amount which is limited only by the -25 ability of the adhesive to retain the pigment dispersed or mixed ~-therein. Generally, the amount of conductive pigmen~ will vary from a minim~m of 0.5 par~s by weight to a maximum of 15 parts by weight, based on the ~eigh~ of the adhesive composition. A mixture of conduc~ e pigments may also be employed depending upon the end 30 use. ` -, : .
, .. . . . .. . . .
1~ 1()66~59 . ~
The solvent-free adhesives are preferred in the practice of the present in~ention sin~e the need for drying is eliminated and the shrinkage problems associated with the loss of solvents or possible solvent retention therein in the event o~ incomplete dxy-ing, are avcided~ The plasticity necessary for a solvent-free ad-hesive may be obtained either by melting the adhesives at the time of application ~in the case of a hot-melt adhesive) or by formulating i~ with various polymeric materials, tackifying agents, etc. and applying it as a pressure-sensitive adhesive. Since these other ingredients are not part of the present invention per se, and since those skilled in the art can readily prepare such compositions, they will not be described in aetail here for purposes of bre~ity.
In a preferred embodiment, an adhesive-coated metallic foil ;-` lS is employed to fill the hole in the recording member. Rèference ~ `r ~ig made to Figures 3 and 4 which show this preferred emhodiment.
; ~; Figure 3 shows a ~ecording member compri~ing a substrate or support 14, an intermediate conductive layer lS and an uppermost .
pho~oconductive layer 16, or dielectric layer. A hole 17 is pro-vided in a non-image area of the recording member, thereby expos-ing the intermediate conductive layer 15 on the inner sùrface of the hole. As shown in Figure 3, two piece~ of adhesive-coated metallic foils 18 and 21, generally, are disposed on opposite ends ' of the hole. The adhesive-coated metallic foil gene~ally com- -prises a thin metallic foil 19 having a coating 20 thereon of the adhesive. The metallic foil can be any conducting metallic foil, such as aluminum, copper, tin, etc., and the thickness of the adhesive can be regulated to provide a complete filling of the hole. The adhesive-coated foil pieces are inserted into the hole 30 such as by the use of pressure as indicated in Figuxe 3. If a hot- -' .. ~ . ~ ; , .. . . .
~: `
~ 1~ 1066759 ~ melt adhesive is employed, the only pressure necessary is that ¦ sufficient to push the heated adhesive material of the upper and ` lower pieces of adhesive-coated foils into the hole for contact and fusion. Figure 4 shows the finished product after the ad-` S hesive-coated foil pieces axe inserted into the hole punched in the recording member. The advantage of using the adhesive-coated foil pieces is that the contact resistance between the exterior elec-trode and the conductive adhesive is reduced thereby providing im-proved perfo~mance and reliability. It is further possible to easily extend the conducti-e area from the hole over the surface of the recording member to whatever contact area and shape is re-qu-red. Moreover, the metallic foil is more durable and in parti-cular mcre resistant to abrasion than the exposed conductive ad-'~ hesive, and in the case of the pressure-sensitive adhesive, it 15 covers and pxotects the tacky surface frcm dirt and prevents its - :
inadvertent a~hesion or blocking to other surfaces. :-:......................................................................... .:
~` Although ~igures 3 and 4 show the use of two adhesive-coated foil pieces, ~he ir.vention is equally as applicable to the use of -~ only a single piece appl~ed from only one side of the recording mem-ber. The adhesive-coated foil can be conveniently made by pre-coat-ing one side of the metallic foil with the adhesive composition, for example, from a sol~ent solation of the same. After drying, the ; coated foil may be heated or slit and wound up to ~he desired size.
.~ ~. .. ~ . .
In the case of the pressu~e-sensitive adhesive, it will usually be necessary to protect the exposed surface of the adhesive such as ~` by the use of the adhesive-coated metallic foil. The use of the adhesive-coated foil provides the additional advantage that the pre-coated foil can be employed to apply a metered amount of the re- --~
~ quired adhesive to the hole in ~he recording member.
-~ 30 The use of two adhesive-coated foil pieces is preferred since ~ -16-, .
~066759 not only will a bond be established with the inside of the hole and with the adjQining surface areas underlying both.pieces of foil, but the adhesive surfaces will meet in the hole and bond both pieces of foil flrm`y to each other, which substantially strengthens the electrical connection. A further advantage o~ using two ad-hesive-coated foil pieces is evident with electrostatographic re-cording m~ers ~hich have a conductive back layer as illustrated in Figure 2. It is func~ionally important to provide electrical con-nection between the intermediate conductive layer ll ~referring now ~o Figure 2) and the conductive ~ack layer 13~ The use of the `~ technique shown in Figures 3 and 4 is tery effective for accomplish-- ing this purpose. The adhesive-coated foil which is applied simultaneously to the back of the member with the application of . the adhesive-coated foil to the front of the member simultaneously establishes contac~ with the interlayer and with the conductive .~ack layer surrounding ~he punched hole.
: .. ~ - - .
Altern3tive emb~dimen~s of ~he improved electrical connection technique of ~he present invention are shown in Figures 5 and 6.
Figure 5 shows a recording member ccmprising a support 21, an intermediate layer 22 which is conductive and an uppermost layer 23 which compr~ses either a photoconductive material or a high di-electric materialc A "slot" or "hole" 24 can be pxovided through the uppermost layer 23 and intermediate layer 22 of the recording member as shown in Figure S. This can be done by any suitable 25 technique, such as by scoring or scratching the surface, or general- -ly by using any technique which destroys the physical integrity of ;.~.
the uppermost layer 23 down to a point into and through the inter-mediate conductive 12yer 220 This can be performed for example by - the use of a solvent which selectively dissolves the upper layer 23 and the conductive layex 22, thereby providing access to the con-.
' -1'~7 ' ' . 10667~9 ductive layer 22~ Whlle a condu~tive adhesive composition by itself can be filled into this slot or hole, it is preferred to use the ad-hesive-coated foi~ as shown in Figure 5, the adhesive being designat-ed 26 and the foil 25o Figure 6 sho~s a related embodiment wherein the slot or hole 30 is only made in the uppermost layer 29 down to but not into the con-ductive layer 28, which overlies support 27. The adhesive 32 con-tacts conductive layer 28 at the bottom of the slot 30, and the ad-hesive 32 is shown in Figure 6 as being covered by a foil member 31.
The improved technique of the present invention is advantageous compared to methods and techniques taught in the prior art. For example, the technique cf the present invention increases the options one has for making contact with an electrode in the appa-` ratus emplcyed in imaging the recording member, in that the loca-tion of the hole is not limited to an edge and any non-image area can be chosen, and in addition the front or back of the member can be contacted. Further, the connection of the present invention provides an effective in~erconnection between the interlayer and the back coat in recording members having a condu~tive back layer. -Further, since the connection is made with an adhesive, it is flex-` ible and durable, especially with the use of the metallic foil. The present inventicn also makes it unnecessary to remove or render conductive the upper laysr in order to establish contact with the intermediate conductive layer.
i 25 If a hot-melt or pressure-sensitivs adhesive is used, the problems associated with the use of a solvent are avoided as indi-cated above. If an adhesive-coated foil is employed, this provides a convenient and effec~ive mannex of metering and applying the con-ductive adhesive, as well as providing a low contact resistance con-nection assuring better and more reproducible image quality. Because . .
~ i . ~066759 of t~he hi~h conductivity of the foil, it can be used in any desired size or shape~ The preferred ~ize is one having a surface area of from about 0.1 cm2 to about 3 cm2, and is easily applied in squares or discs Lastly, if a pre~sure-sensitive adhesive-coated on foil is employed, it is easy to apply, no heat being necessary, thereby avoiding the risk of thermal damage to the recording member.
The present invention relates speci~ically to the improved technique ~or making ground connection to the electrically-conductive intermediate layer of the reco~ding members above described. The ` 10 inventicn does no~ per se reside in the composition, basic structure or other characteristics of the recording member per se~ The pres-ent invention i~ expressly applicable to any conventional electro-`~ statographic record ng member having at least three layers, a support wh~ch is electrically insulati~g, an electrically conduct-ing layer o~erlying the suppoxt and an uppermost layer which is either pho~oconducti~e (_n the case of ele~trophotographic members) or a dielectr~c material ha~ing a high volume resistivity (in the case of an electrographic recording member). An optional fourth ` ~-layer is the conductive baek layer on the~opposite side of the 20 support from ~he in~ermedia~e conducting layer and either the pho~o- `
, conductive ¢r dielectric layer~.
One ckilled in the art can select appropriate materials to form these conventional recording members. Thus, as the support various materials can be u~ed, such as paper or synthetic resins ~25 such as polyesters (e~g~, polyethylene terephthalate) or cellulose " esters ~e.g~, cellulose acetate~ and the like. Preferably, the support is formed of a transparent material such as polyethylene terephthalate or cellulose acetate when the recording member is to be used as a maste~ in a photographic reproduction process where the information imaged thereon is to be exposed from ~he back side -19- , ., . . ~ ~
1(~66759 of the re~ording member. The thickness of the support may vary depending upon the end use, there being no particular limitation as to the thickne~s of the support.
The intermediate conducting layer which i9 coated onto the support, evaporated thereon or formed as a part of the upper ~ur-face of the support, can comprise literally any conducting compo-sition. Normally, the conducting layer comprises an electrically-conducting material dispersed in a binder therefor and coated onto the support, such as from a ~olvent solution thereof. ~he elec-trically-conducting material may be the same as that used in appli-cant's adhesives and the binder may be polymeric in nature, such as polyolefins, vinyl polymers such as polyvinyl chloride, acryl-ates, methacrylates, polyesters, styrene-butadiene copolymers, polyvinyl acetate, polystyrene, polyamides, polycarbonates, copoly-mers thereof, etc. Illustrative of the electrically-conducting materials which may be employed in such intermediate conducting layers are ionizable polyelectrolyte salts, polymeric quaternary ammonium salts, polystyrene ~ulfonic acid salts, salts of copoly-mers of vinyl compounds with maleic acid, Calgon 261, vinyl acetate, and metal coatings deposited by sputtering ox vacuum deposition to r~nder the component electrically conducting. The thickness of the conducting layer is not particularly limited, and those skilled in the art can vary the thickness as desired.
In an electrophotographic element, ~he upper layer is photo-conductive and normally comprises an organic or inorganic photocon-ductor dispersed in a binder therefor. Any or~ani¢ or inorganic `~ photoconductor i8 useful in the electrophotographic elements of the present invention. Typical organic photoconductors include, for example, qu~nacridones, carboxamides, carboxanilides, triazines, anthraquinones, ano compounds, salts and lakes of compounds derived ., , . , :
.
E~
` ~066759 from 9-phenylxanth~ne, dioxazines, lakes of fluorescein dyes, pyrenes, phtha'ocyanines, ~Rtal salts and lakes of azo dyes, poly-vinyl carbaæole, substit.uted phenylene diamines, and the like.
Several substituted phenylene diamines axe described in detail in ~.S. Patents 3,314,788 issued April 18, 1967 to Mattor and 3,615,404 issued October 26, 1971 to Price et al. The amount of the photoconductive material in the photoconductive layer is at least the minimum required to render the layer photoconductive, with the amount generally varying from 5% to 65% by weight, based on the weight of the photoconduc~ive layer. The disclosures of the aforementioned Mattor and Pxice et al Patents are hereby in-corporated herein by reference for their disclosures of suitable ` photocondu~tive ma~erials.
Also operab'e in ~he photoconductive layer, and preferred, are sensitizing compounds which further increase the sensitivity ~of the photoconductive ma~erials to light of certain wavelengths.
Any conventional sensitizing compounds may be employed in the photoconductive layer of the present invention to be used in com-bination wi~h related photc~onduetive materials to further in-crease the sensitization of the photoconductive layer. The amountof the sensitizer in the photoconductive layer can vary within wide ranges, with the optimum concentration in any given case vary-- ing with the speeific phcto~onducto~ employed and the sensitizing compound usedO Normally, sensitlzers are employed in amounts of :1 .
2S from 0.05% to 0O3% by weight, based on the weight of the photocon- -ductive layer, or about 3 ml. of a 1% solution of the sensitizer ;-for each 25 grams of photoconductor employed. ~-;
. The photoconductive layer may be coated onto ~he electrically-; conductive inte~mediate layer such as frsm a solvent solution of the composition. ~he solvent will o~ course vary depending upon the -21- ~
:' -. .: ~ .
.~.
. ~066759 photoccnductor and ser.sirizer, if one is present, and the binder.
Those ~killed in the art can certainly practice the present inven-tion using ~arious solven~s wlth a m-nimum amount of experimentation.
With the ele~trographic recording elements of the present in-vention, the supp~rt and intermediate electrically-conductive layers would be the same and can be formed of any of the above described materials. The upper layer is formed of a material having a high volume resistivity, prefexably a minimum of 1012 ohm-centimeters.
Typical materials are as follows: styrenebutadiene copolymers;
silicone resins; styrene-alkyd resins; silicone alkyd resins; soya-alkyd resins; poly(v~nyl chloride); poly(vinylidene chloride);
vinylidene chloride-acrylonitr * e copolymers; poly~vinyl acetate);
`i vinyl acetate-vinyl chloride~copolymers; poly(vinyl acetals), such as polytvinyl butyral); polyacrylic and methacrylic esters, such as polytmethylmetha~rylate), poly(n-butylmethacrylate), poly~iso-butyl methacrylate), etcO; polystyrene, nitrated polystyrene; poly-methylstyrene; isobutylene po1ymers; polyesters, such as poly(ethyl-enealkaryloxyalkylene terephthalate~; phenol-formaldehyde resins;
ketone resins; polyamide; polycarbcnates; polythiocarbonates; poly-(ethyleneglycol-co-b~shydroxyethoxphenyl-propane terephthalate);
etc. Methods~of making resins o~ this type have been described in the prior ar~ for example, styrene-alkyd resins can be prepared according to the method described in U.S. Patents 2,361,019 and 2,250,423. Suitable resins of the type contemplated for use in the photoconductive layers of the invention are sold under such trade J' names as Vitel* PE-101, Cymac*, Piccopale* 100, and Saran* F-~20 -and Lexan* 105~ O~her ~ypes of binders which can be used in the photoconductive layers of the invention include such materials as paraffin, mineral waxes, etc. ~-With regard to the electri~ally-conductive back layer used in *Registered ~rademark ~22-v .. . . . .
. . ~ : ; . .
. . . . . .
~ ~ .
. : . . 1066759 certain embodimenrs, this can be formed of materials which are similar to or the ~ame as the _ntermedia~e electrically-conductive layer. In addikicn, both of these conductive layers can be formed of electrically-~onducti~e materials per se instead of conductive pigments dispersed in a binder. For example, U~S. Patent No.
; 3,011,918 discloses a oonductive resinous polymer, polyvinyl benzyl trimethyl ammonium chloride, whi~ch is itsel~ conductive. Alterna-tively, these layers may be made by printing or coatin~ the support suxface with an elec~rocondu~tive ink, or a metal or a suitable semi-conductor may be vacuum deposi~ed or sputtered onto the support. See, for example, U.S. Patent Nos. 3,207,625; 2,756,16i;
3,148,083; 3,245,833; and 3,428,451.
` ` As will be apparent from th& above description, the preferred compositions are ~hose which provide a flexible recording member, r ~ 15 particularly thcse matexials are preferred whi~h are flexible and transparent to prov-de a transparent recording member. In addition, it is preferred that the suppor~ be substantially electrically insu~ating in nature.
. . . .
While the inv~ention has been shown and described with reference 20~ to p~eferred embodiments thereof, it is to be expressly understood ` that ~arious changes and modîfi~ations may be made without departing from the spirit and s~ope of 'the present invention, as defined in ;
~ the appended ~lai~. :
~ . .
I ' ~-.'`''` .
, ,~
. , :
., . :"
:~
Claims (16)
1. In an electrostatographic recording member comprising at least:
an electrically-insulating substrate;
an electrically-conductive layer overlying a first surface of said substrate;
an electrically-insulating outer layer overlying said conduc-tive layer, said outer layer containing a photoconductive mater-ial or being composed of a dielectric material of high volume resistivity; and means for establishing a ground connection to said conductive layer;
the improvement comprising said ground connection means com-prising a hole in a non-image area of said recording member ex-tending from a surface thereof at least to said conductive layer and an electrically-conductive composition in said hole, said electrically-conductive composition comprising an adhesive and a sufficient amount of an electrically-conductive pigment to make said composition conductive, said composition being in electrical contact with said conductive layer and the exposed composition at the surface of said recording member being covered by a conduc-tive metallic foil.
an electrically-insulating substrate;
an electrically-conductive layer overlying a first surface of said substrate;
an electrically-insulating outer layer overlying said conduc-tive layer, said outer layer containing a photoconductive mater-ial or being composed of a dielectric material of high volume resistivity; and means for establishing a ground connection to said conductive layer;
the improvement comprising said ground connection means com-prising a hole in a non-image area of said recording member ex-tending from a surface thereof at least to said conductive layer and an electrically-conductive composition in said hole, said electrically-conductive composition comprising an adhesive and a sufficient amount of an electrically-conductive pigment to make said composition conductive, said composition being in electrical contact with said conductive layer and the exposed composition at the surface of said recording member being covered by a conduc-tive metallic foil.
2. The recording member of claim 1, further comprising a second electrically-conductive layer on the second surface of said substrate opposite said first surface.
3. The recording member of claim 2, wherein said hole ex-tends through the entire thickness thereof, said composition being in electrical contact with both of said conductive layers.
4. The recording member of claim 1, wherein said adhesive comprises a hot-melt adhesive.
5. The recording member of claim 1, wherein said adhesive comprises a pressure-sensitive adhesive.
6. The recording member of claim 1, wherein the volume resistivity of said dielectric material is at least 1012 ohm-centimeters.
7. The recording member of claim 1, wherein said hole extends through the entire thickness of said recording member.
8. The recording member of claim 7, wherein the exposed composition at both surfaces of said recording member is covered by a conductive metallic foil.
9. The recording member of claim 1, wherein said hole ex-tends from a surface of said recording member only to said con-ductive layer.
10. A process for establishing a ground connection with an intermediate conductive layer of an electrostatographic recording member, said recording member comprising at least:
an electrically-insulating substrate;
an intermediate conductive layer overlying a first surface of said substrate; and an electrically-insulating outer layer overlying said conductive layer, said outer layer containing a photoconductive material or being composed of a dielectric material of high vol-ume resistivity said process comprising:
(1) forming a hole in a non-image area of said record-ing member extending from a surface thereof to at least said in-termediate conductive layer;
(2) inserting in said hole an electrically-conductive composition comprising an adhesive and a sufficient amount of an electrically-conductive pigment to make said composition electri-cally-conductive; and (3) bonding said adhesive composition in said hole to said recording member, said adhesive composition providing the sole electrically-conductive path between the conductive layer of the recording medium and a conductive metallic foil covering said adhesive composition.
an electrically-insulating substrate;
an intermediate conductive layer overlying a first surface of said substrate; and an electrically-insulating outer layer overlying said conductive layer, said outer layer containing a photoconductive material or being composed of a dielectric material of high vol-ume resistivity said process comprising:
(1) forming a hole in a non-image area of said record-ing member extending from a surface thereof to at least said in-termediate conductive layer;
(2) inserting in said hole an electrically-conductive composition comprising an adhesive and a sufficient amount of an electrically-conductive pigment to make said composition electri-cally-conductive; and (3) bonding said adhesive composition in said hole to said recording member, said adhesive composition providing the sole electrically-conductive path between the conductive layer of the recording medium and a conductive metallic foil covering said adhesive composition.
11. The process of claim 10, wherein said hole is formed through the entire thickness of said recording member.
12. The process of claim 11, wherein two pieces of conduc-tive metallic foil, coated on one side with said composition are forced into the opposite ends of said hole, the coated sides facing each other, whereby the ends of said hole are covered by said metallic foil.
13. The process of claim 12, wherein said adhesive is a hot-melt adhesive and said steps (2) and (3) are performed by heating said pieces of coated metallic foil and forcing the melted ad-hesive into the hole.
14. The process of claim 12, wherein said adhesive is a pressure-sensitive adhesive.
15. The process of claim 10, wherein said hole is formed from said surface only to said intermediate conductive layer.
16. The process of claim 15, wherein a piece of conductive metallic foil, coated on one side with said composition, is forced into said hole, whereby the end of the hole at said sur-face is coated by said foil.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US43439874A | 1974-01-18 | 1974-01-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1066759A true CA1066759A (en) | 1979-11-20 |
Family
ID=23724074
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA218,089A Expired CA1066759A (en) | 1974-01-18 | 1975-01-17 | Technique for making electrical ground contact with the intermediate conductive layer of an electrostatographic recording member |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS50124645A (en) |
| BE (1) | BE824460A (en) |
| CA (1) | CA1066759A (en) |
| DE (1) | DE2502249B2 (en) |
| FR (1) | FR2258652B1 (en) |
| GB (1) | GB1490001A (en) |
| IT (1) | IT1026377B (en) |
| NL (1) | NL7500655A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1115334A (en) * | 1978-06-22 | 1981-12-29 | Eastman Kodak Company | Electrographic element provided with electrical connection means |
| JPS58117549A (en) * | 1982-01-06 | 1983-07-13 | Toray Ind Inc | Electrostatic image recording body |
-
1975
- 1975-01-13 GB GB138275A patent/GB1490001A/en not_active Expired
- 1975-01-16 BE BE1006403A patent/BE824460A/en unknown
- 1975-01-17 IT IT4772675A patent/IT1026377B/en active
- 1975-01-17 CA CA218,089A patent/CA1066759A/en not_active Expired
- 1975-01-17 FR FR7501498A patent/FR2258652B1/fr not_active Expired
- 1975-01-17 JP JP770175A patent/JPS50124645A/ja active Pending
- 1975-01-17 DE DE19752502249 patent/DE2502249B2/en active Granted
- 1975-01-20 NL NL7500655A patent/NL7500655A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| IT1026377B (en) | 1978-09-20 |
| BE824460A (en) | 1975-07-16 |
| NL7500655A (en) | 1975-07-22 |
| FR2258652B1 (en) | 1978-02-03 |
| DE2502249A1 (en) | 1975-07-31 |
| AU7738675A (en) | 1976-07-22 |
| DE2502249B2 (en) | 1976-11-18 |
| FR2258652A1 (en) | 1975-08-18 |
| GB1490001A (en) | 1977-10-26 |
| JPS50124645A (en) | 1975-09-30 |
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