CA1046825A - Electrographic recording element with polyester resin coated on base support - Google Patents
Electrographic recording element with polyester resin coated on base supportInfo
- Publication number
- CA1046825A CA1046825A CA198,559A CA198559A CA1046825A CA 1046825 A CA1046825 A CA 1046825A CA 198559 A CA198559 A CA 198559A CA 1046825 A CA1046825 A CA 1046825A
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- CA
- Canada
- Prior art keywords
- recording element
- electrographic recording
- acid
- equal
- polyester resin
- 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
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Classifications
-
- 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
- G03G5/02—Charge-receiving layers
- G03G5/0202—Dielectric layers for electrography
- G03G5/0205—Macromolecular components
- G03G5/0211—Macromolecular components obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
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- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Polyesters Or Polycarbonates (AREA)
- Photoreceptors In Electrophotography (AREA)
- Thermal Transfer Or Thermal Recording In General (AREA)
Abstract
ELECTROGRAPHIC RECORDING ELEMENT
ABSTRACT OF THE DISCLOSURE
An electrographic recording element having improved charge acceptance and charge retention properties is disclosed. The element comprises a base support having coated thereon a layer comprising a poly-ester resin prepared from a dicarboxylic acid and a polyol having the following general formula wherein a is O or 1, R is selected from the group consisting of Cl to C5 alkylene, oxygen, sulfur, or a divalent radical having one of the following formulas , or
ABSTRACT OF THE DISCLOSURE
An electrographic recording element having improved charge acceptance and charge retention properties is disclosed. The element comprises a base support having coated thereon a layer comprising a poly-ester resin prepared from a dicarboxylic acid and a polyol having the following general formula wherein a is O or 1, R is selected from the group consisting of Cl to C5 alkylene, oxygen, sulfur, or a divalent radical having one of the following formulas , or
Description
BACKGROUND OF THE INVENTION
Field of the Invention ; The present invention relates generally to electro-graphic recording elements. More particularly, the invention --relates to an electrographic recording element comprising a base support having coated thereon a layer comprising a poly-ester resin prepared from a dicarboxylic acid and a polyol, said polyol having the following general formula 10Il-EO-C-C~ o~( R) a~ O~ C-C-O}H
H m A A A H H n wherein a is 0 or 1, R is selected from the group consisting of Cl to C5 alkylene, oxygen, sulfur, or a divalent radical having one of the following formulas ~j,. . . .
~ O = S = O, C = O or S = O
,. . . .
. A
,, A is halogen or hydrogen, m and n are integers each of which is equal to at least 1 and the sum of which is equal to from 2 to , , ~ 20 less than 7 and X and Y are methyl, phenyl, or hydrogen provided ., that, in any X and Y pair on adjacent carbon atoms, either X or Y is hydrogen.
Description of the Prior Art Electrographic recording elements are well known in the art. These recording elements generally comprise a base support having coated thereon a layer of a dielectric-i.e., insulating-material. Resins suitable for use in the dielectric layers are also known in the prior art. See, in this regard, .:
U.S. patent 3,639,640 issued to Gager; U.S. patent 3,385,730 30issued to Relph; U.S. patent 3,634,135 issued to Akiyama; and .
Field of the Invention ; The present invention relates generally to electro-graphic recording elements. More particularly, the invention --relates to an electrographic recording element comprising a base support having coated thereon a layer comprising a poly-ester resin prepared from a dicarboxylic acid and a polyol, said polyol having the following general formula 10Il-EO-C-C~ o~( R) a~ O~ C-C-O}H
H m A A A H H n wherein a is 0 or 1, R is selected from the group consisting of Cl to C5 alkylene, oxygen, sulfur, or a divalent radical having one of the following formulas ~j,. . . .
~ O = S = O, C = O or S = O
,. . . .
. A
,, A is halogen or hydrogen, m and n are integers each of which is equal to at least 1 and the sum of which is equal to from 2 to , , ~ 20 less than 7 and X and Y are methyl, phenyl, or hydrogen provided ., that, in any X and Y pair on adjacent carbon atoms, either X or Y is hydrogen.
Description of the Prior Art Electrographic recording elements are well known in the art. These recording elements generally comprise a base support having coated thereon a layer of a dielectric-i.e., insulating-material. Resins suitable for use in the dielectric layers are also known in the prior art. See, in this regard, .:
U.S. patent 3,639,640 issued to Gager; U.S. patent 3,385,730 30issued to Relph; U.S. patent 3,634,135 issued to Akiyama; and .
- 2 - ~
`:~' qF
lV4t;825 U.S. patent 3,653,894 issued to Levy et al.
The electrographic recording elements are useful in what is generally referred to as an electrographic or electro-static printing process to provide a permanent record of the information generated by such a process. Although the de-tails of the recording processes involved are not necessary to a complete understanding of the present invention which is related only to electrographic elements which may be used in such processes, a basic explanation of the process is useful in understanding the invention. Basically, electrostatic re-cording is accomplished by depositing a pattern of electrical charge upon the surface of the dielectric layer of the recording element, which charge pattern is made visible by bringing the element into contact with a suitable, usually powdered, electri-cally conductive ink or toner which adheres to the charged areas, and then, if desired, fixing the ink by subjecting the ; developed recording element to heat and/or pressure.
Electrographic printing processes are generally cate-gorized in one of two ways. In the first or direct electro-graphic recording process, the information to be recorded isgenerated by way of an electrically energized stylus or an ; electrostatic writing tube, commonly referred to as a CRT pin tube, which is in close proximity to the electrographic record-ing element. Energization of the stylus or the electrostatic writing tube results in the deposition of a charge pattern on the surface of the electrographic recording element which charge pattern is commonly referred to as a "latent image". This charge pattern is then developed by any of the well-known electrostatic developing techniques to form a permanent and visible image or print. In the direct process, the charge pattern is developed or imaged directly upon the surface on which it is formed. Alternatively, in a transfer electrogra-phic recording process, the charge pattern or latent image is originally formed on a surface other than the surface of the electrographic recording element, for example, on the surface ' of a photoconductive element, and the charge pattern is then transferred to the electrographic recording element in order '; to enable a permanent visible record to be made of the thus formed latent image. After transfer of the latent image to the electrographic recording element, development of the image is achieved in a manner similar to that employed in a direct process.
In either process, it is important that the dielectric layer in the electrographic recording element be able to accept and retain a high level of charge. If the material either does ' not initially accept a high level of charge or if the accepted ' charge is substantially dissipated or lost before a visible image is formed, the recording element is of limited utility in commercial applications.
It is an object of the present invention to provide an electrostatic recording element which both accepts a high level of charge-i.e. has a high charge acceptance - and which retains a high percentage of that charge for a period of time sufficient to allow development of the charge pattern to form a visible image - i.e. has a high charge retention~
~UMMARY OF THE INVENTION
In accordance with the present invention electro-graphic recording elements having improved properties such as increased charge acceptance and improved charge retention are prepared comprising a base support having coated thereon a ;
layer of a polyester resin prepared by reacting a dicarboxylic acid selected from the group consisting of alpha-unsaturated dicarboxylic acids and aromatic dicarboxylic acids with a polyol having the following general formula X Y A A A A _ _ H- -O-C-C -O ~ (R) ~ O- C-C-O I H -H H m A A A A H H n wherein a is 0 or 1, R is selected from the group consisting ; of Cl to C5 aIkylene, oxygen, sulfur, or a divalent radical having one of the following formulas O = S = O, C = O or S = O
A is halogen or hydrogen, m and n are integers each of which is equal to at least 1 and the sum of which is equal to from 2 to less than 7 and X and Y are methyl, phenyl or hydrogen provided that, in any X and Y pair on adjacent carbon atoms, either X or Y is hydrogen.
- DESCRIPTION OF THE PREFERRED EMBODIMæNTS
.
As mentioned above, the electrographic recording elements of the present invention comprise a base support having coated thereon a layer comprising a polyester resin prepared by reacting a polyol with a dicarboxylic acid. Each of these components is described in detail below.
Base Support The base support used to prepare the electrographic recording elements of the present invention may be any one of a number of base supports conventionally employed in electro-graphic recording elements. Representative base supports which may be employed include, for example, metal foil, an electri-, - - ' ~0468ZS
cally conductive paper, an electrically conductive film and an electrically conductive cloth. Of these, it is preferred to employ an electrically conductive paper.
When a base support other than a metal foil is em-ployed, electrical conductivity can be imparted to the base by impregnating or coating the base with any of the compositions or materials which have previously been employed to impart electrical conductivity to such bases. Illustrative of such materials are materials such as carbon black; inorganic electro-lytes such as sodium chloride, calcium chloride, and lithiumchloride; and electrically conductive resinous polymers such as resinous polymers of quaternary ammonium salts. Since materials such as carbon black impart a color to the base which might ~ be considered to be objectionable and materials such as inorganic ;j electrolytes are somewhat dependent on the ambient relative humidity for their effectiveness as conductive agents, the use of electrically conductive resinous polymers to impart electrical conductivity to the base supports is preferred. Examples of - such polymers can be found, for example, in U.S. patent 3,011,918 which relates to homopolymers and copolymers of vinylbenzyl quaternary ammonium compounds and papers coated with such com-pounds. Other compounds which are useful for this purpose in-clude, for example, polymers of vinyl pyridine quaternized with aliphatic esters, such as a polymer of vinyl pyridine which has been quaternized with diethyl sulfate.
Polyester Resin The polyester resins which have been found to be especially useful in the preparation of electrographic recording elements in accordance with the present invention are prepared ; 30 by reacting a dicarboxylic acid with a polyol. The polyols ,, . ., ,.~
.
which may be employed in the preparation of the polyester resins may be represented by the following general formula ~ ~O-C-C} o ~ (R)a ~ O ~C-C-O~ H
; H H m A A A H H n wherein a is 0 or 1, R is selected from the group consisting of Cl to C5 alkylene, oxygen, sulfur, or a divalent radical ;having one of the following formulas , . . .
:'- ' ' ' O = S = O, C = O or S = O
''- ' ' ' ' ' .
A is halogen or hydrogen, m and n are integers each of which "; .
is equal to at least 1 and the sum of which is equal to from 2 to less than 7 and X and Y are methyl, phenyl, or hydrogen provided that, in any X and Y pair on adjacent carbon atoms, either X or Y is hydrogen.
;
j~These polyols are prepared by reacting an alkylene oxide, such as ethylene oxide or propylene oxide, or styrene oxide, with a dihydric phenol having the following general ~., formula ~ A A A A
,~HO ~ (R)a ~ OH
,,;, .
-wherein R, A, and a are as defined above. The sum of m and n in the previous formula is determined by the number of mols of alkylene oxide or styrene oxide added per mol of the dihydric phenol. Thus, in preparing the polyols useful in the present invention, an average of from about 2 to about 7 mols of alkylene oxide or styrene oxide should be reacted with each mol .
'30 of the dihydric phenol.
;:~
. - 7 -- 1~46825 The polyester resins are prepared from the resulting polyol by reacting the polyol with an approximately equimolar amount of a dicarboxylic acid selected from the group consisting of alpha-unsaturated dicarboxylic acids and aromatic dicarboxylic acids. Representative alpha-unsaturated dicarboxylic acids which may be used to carry out this esterification reaction include, for example, maleic acid and fumaric acid. Represen-tative aromatic dicarboxylic acids which may be employed in-clude, for example, phthalic acid, isophthalic acid and tere-phthalic acid. Anhydrides of these acids, such as maleic an-hydride and phthalic anhydride, may also be employed. The acid employed in the esterification reaction may also contain a minor amount of a saturated acid, a second aromatic acid or another unsaturated aliphatic acid. If a mixture of acids is employed, it is preferred that at least about 80 mol percent of the acid be an alpha-unsaturated dicarboxylic acid or an aro-matic dicarboxylic acid as described above. The preferred poly-ester resins for use in the present invention are those prepared from alpha-unsaturated dicarboxylic acids.
The reaction of the polyol and the dicarboxylic acid may be pe,rformed in an inert a~mosphere and at moderate tempera-tures and substantially atmospheric pressures during the early stage, thus minimizing the loss of dicarboxylic acid by volati-lization. As the reaction proceeds the temperature may be in-creased and the pressure reduced. An esterification catalyst may be used although it is generally preferred to carry out the reaction in the absence of excessive amounts of catalyst to avoid contamination of the final resinous product. Where an unsaturated dicarboxylic acid is used, it is usually desirable to include a small amount of a polymerization inhibitor such as . .
~0468;25 hydroquinone or pyrogallol. The procedure employed to prepare the polyesters useful in this invention generally include heating to about 200C for a period of time during the course of the reaction. The resulting polyesters generally have low acid numbers - i.e. up to about 30. As used herein, and as is well known to those skilled in the art, the acid number of the resin is determined by measuring the number of milligrams of potassium hydroxide required to neutralize one gram of resin. Also, as mentioned above, the ratio of carboxyl groups to hydroxyl groups in the reaction mixt~re employed in preparing the polyester resins , of this invention is preferably about 1. However, ratios as low as about 0.8 and as high as about 1.2 can also be employed. ~ -The preferred polyester resins employed in carrying out the present invention are the polyoxyalkylene bisphenol A
fumarates such as polyoxypropylene bisphenol A fumarate contain- -ing an average of 2.2 oxypropylene groups per mol of the bispheol A. As is well known in the art, bisphenol A refers to the following compound HO ~ CH3 OH
The electrographic recording elements of the present invention are prepared by coating a layer comprising one of `~, the above-described polyester resins on any of the above-men-~` tioned base supports. This coating operation may be carried out by techniques which are well known in the art. Additives which are conventionally employed in the preparation of electro-graphic recording elements may also be included in the dielec-tric layer. These additives include, for example, whitening agents and toothing agents.
..
:~ , . . . . : .
In preparing the recording elements, the polyester resin and any additives are first dissolved in or dispersed in a suitable solvent, such as toluene, and the resulting slurry , or solution is then coated onto a suitable base support and the material dried to remove the solvent. The amount of resin employed in the preparation of said elements may be varied over a wide range depending upon the desired properties and intended application of the electrographic recording element.
However, for most applications it has been found that an amount of resin which will result in a coating weight of from about ' 0.5 to about 10 pounds per ream (3,000 square feet) is preferred.
,,~ Especially preferred results are achieved at coating weights equal to from about 1 to about 5 pounds per ream.
~' .
`:~' qF
lV4t;825 U.S. patent 3,653,894 issued to Levy et al.
The electrographic recording elements are useful in what is generally referred to as an electrographic or electro-static printing process to provide a permanent record of the information generated by such a process. Although the de-tails of the recording processes involved are not necessary to a complete understanding of the present invention which is related only to electrographic elements which may be used in such processes, a basic explanation of the process is useful in understanding the invention. Basically, electrostatic re-cording is accomplished by depositing a pattern of electrical charge upon the surface of the dielectric layer of the recording element, which charge pattern is made visible by bringing the element into contact with a suitable, usually powdered, electri-cally conductive ink or toner which adheres to the charged areas, and then, if desired, fixing the ink by subjecting the ; developed recording element to heat and/or pressure.
Electrographic printing processes are generally cate-gorized in one of two ways. In the first or direct electro-graphic recording process, the information to be recorded isgenerated by way of an electrically energized stylus or an ; electrostatic writing tube, commonly referred to as a CRT pin tube, which is in close proximity to the electrographic record-ing element. Energization of the stylus or the electrostatic writing tube results in the deposition of a charge pattern on the surface of the electrographic recording element which charge pattern is commonly referred to as a "latent image". This charge pattern is then developed by any of the well-known electrostatic developing techniques to form a permanent and visible image or print. In the direct process, the charge pattern is developed or imaged directly upon the surface on which it is formed. Alternatively, in a transfer electrogra-phic recording process, the charge pattern or latent image is originally formed on a surface other than the surface of the electrographic recording element, for example, on the surface ' of a photoconductive element, and the charge pattern is then transferred to the electrographic recording element in order '; to enable a permanent visible record to be made of the thus formed latent image. After transfer of the latent image to the electrographic recording element, development of the image is achieved in a manner similar to that employed in a direct process.
In either process, it is important that the dielectric layer in the electrographic recording element be able to accept and retain a high level of charge. If the material either does ' not initially accept a high level of charge or if the accepted ' charge is substantially dissipated or lost before a visible image is formed, the recording element is of limited utility in commercial applications.
It is an object of the present invention to provide an electrostatic recording element which both accepts a high level of charge-i.e. has a high charge acceptance - and which retains a high percentage of that charge for a period of time sufficient to allow development of the charge pattern to form a visible image - i.e. has a high charge retention~
~UMMARY OF THE INVENTION
In accordance with the present invention electro-graphic recording elements having improved properties such as increased charge acceptance and improved charge retention are prepared comprising a base support having coated thereon a ;
layer of a polyester resin prepared by reacting a dicarboxylic acid selected from the group consisting of alpha-unsaturated dicarboxylic acids and aromatic dicarboxylic acids with a polyol having the following general formula X Y A A A A _ _ H- -O-C-C -O ~ (R) ~ O- C-C-O I H -H H m A A A A H H n wherein a is 0 or 1, R is selected from the group consisting ; of Cl to C5 aIkylene, oxygen, sulfur, or a divalent radical having one of the following formulas O = S = O, C = O or S = O
A is halogen or hydrogen, m and n are integers each of which is equal to at least 1 and the sum of which is equal to from 2 to less than 7 and X and Y are methyl, phenyl or hydrogen provided that, in any X and Y pair on adjacent carbon atoms, either X or Y is hydrogen.
- DESCRIPTION OF THE PREFERRED EMBODIMæNTS
.
As mentioned above, the electrographic recording elements of the present invention comprise a base support having coated thereon a layer comprising a polyester resin prepared by reacting a polyol with a dicarboxylic acid. Each of these components is described in detail below.
Base Support The base support used to prepare the electrographic recording elements of the present invention may be any one of a number of base supports conventionally employed in electro-graphic recording elements. Representative base supports which may be employed include, for example, metal foil, an electri-, - - ' ~0468ZS
cally conductive paper, an electrically conductive film and an electrically conductive cloth. Of these, it is preferred to employ an electrically conductive paper.
When a base support other than a metal foil is em-ployed, electrical conductivity can be imparted to the base by impregnating or coating the base with any of the compositions or materials which have previously been employed to impart electrical conductivity to such bases. Illustrative of such materials are materials such as carbon black; inorganic electro-lytes such as sodium chloride, calcium chloride, and lithiumchloride; and electrically conductive resinous polymers such as resinous polymers of quaternary ammonium salts. Since materials such as carbon black impart a color to the base which might ~ be considered to be objectionable and materials such as inorganic ;j electrolytes are somewhat dependent on the ambient relative humidity for their effectiveness as conductive agents, the use of electrically conductive resinous polymers to impart electrical conductivity to the base supports is preferred. Examples of - such polymers can be found, for example, in U.S. patent 3,011,918 which relates to homopolymers and copolymers of vinylbenzyl quaternary ammonium compounds and papers coated with such com-pounds. Other compounds which are useful for this purpose in-clude, for example, polymers of vinyl pyridine quaternized with aliphatic esters, such as a polymer of vinyl pyridine which has been quaternized with diethyl sulfate.
Polyester Resin The polyester resins which have been found to be especially useful in the preparation of electrographic recording elements in accordance with the present invention are prepared ; 30 by reacting a dicarboxylic acid with a polyol. The polyols ,, . ., ,.~
.
which may be employed in the preparation of the polyester resins may be represented by the following general formula ~ ~O-C-C} o ~ (R)a ~ O ~C-C-O~ H
; H H m A A A H H n wherein a is 0 or 1, R is selected from the group consisting of Cl to C5 alkylene, oxygen, sulfur, or a divalent radical ;having one of the following formulas , . . .
:'- ' ' ' O = S = O, C = O or S = O
''- ' ' ' ' ' .
A is halogen or hydrogen, m and n are integers each of which "; .
is equal to at least 1 and the sum of which is equal to from 2 to less than 7 and X and Y are methyl, phenyl, or hydrogen provided that, in any X and Y pair on adjacent carbon atoms, either X or Y is hydrogen.
;
j~These polyols are prepared by reacting an alkylene oxide, such as ethylene oxide or propylene oxide, or styrene oxide, with a dihydric phenol having the following general ~., formula ~ A A A A
,~HO ~ (R)a ~ OH
,,;, .
-wherein R, A, and a are as defined above. The sum of m and n in the previous formula is determined by the number of mols of alkylene oxide or styrene oxide added per mol of the dihydric phenol. Thus, in preparing the polyols useful in the present invention, an average of from about 2 to about 7 mols of alkylene oxide or styrene oxide should be reacted with each mol .
'30 of the dihydric phenol.
;:~
. - 7 -- 1~46825 The polyester resins are prepared from the resulting polyol by reacting the polyol with an approximately equimolar amount of a dicarboxylic acid selected from the group consisting of alpha-unsaturated dicarboxylic acids and aromatic dicarboxylic acids. Representative alpha-unsaturated dicarboxylic acids which may be used to carry out this esterification reaction include, for example, maleic acid and fumaric acid. Represen-tative aromatic dicarboxylic acids which may be employed in-clude, for example, phthalic acid, isophthalic acid and tere-phthalic acid. Anhydrides of these acids, such as maleic an-hydride and phthalic anhydride, may also be employed. The acid employed in the esterification reaction may also contain a minor amount of a saturated acid, a second aromatic acid or another unsaturated aliphatic acid. If a mixture of acids is employed, it is preferred that at least about 80 mol percent of the acid be an alpha-unsaturated dicarboxylic acid or an aro-matic dicarboxylic acid as described above. The preferred poly-ester resins for use in the present invention are those prepared from alpha-unsaturated dicarboxylic acids.
The reaction of the polyol and the dicarboxylic acid may be pe,rformed in an inert a~mosphere and at moderate tempera-tures and substantially atmospheric pressures during the early stage, thus minimizing the loss of dicarboxylic acid by volati-lization. As the reaction proceeds the temperature may be in-creased and the pressure reduced. An esterification catalyst may be used although it is generally preferred to carry out the reaction in the absence of excessive amounts of catalyst to avoid contamination of the final resinous product. Where an unsaturated dicarboxylic acid is used, it is usually desirable to include a small amount of a polymerization inhibitor such as . .
~0468;25 hydroquinone or pyrogallol. The procedure employed to prepare the polyesters useful in this invention generally include heating to about 200C for a period of time during the course of the reaction. The resulting polyesters generally have low acid numbers - i.e. up to about 30. As used herein, and as is well known to those skilled in the art, the acid number of the resin is determined by measuring the number of milligrams of potassium hydroxide required to neutralize one gram of resin. Also, as mentioned above, the ratio of carboxyl groups to hydroxyl groups in the reaction mixt~re employed in preparing the polyester resins , of this invention is preferably about 1. However, ratios as low as about 0.8 and as high as about 1.2 can also be employed. ~ -The preferred polyester resins employed in carrying out the present invention are the polyoxyalkylene bisphenol A
fumarates such as polyoxypropylene bisphenol A fumarate contain- -ing an average of 2.2 oxypropylene groups per mol of the bispheol A. As is well known in the art, bisphenol A refers to the following compound HO ~ CH3 OH
The electrographic recording elements of the present invention are prepared by coating a layer comprising one of `~, the above-described polyester resins on any of the above-men-~` tioned base supports. This coating operation may be carried out by techniques which are well known in the art. Additives which are conventionally employed in the preparation of electro-graphic recording elements may also be included in the dielec-tric layer. These additives include, for example, whitening agents and toothing agents.
..
:~ , . . . . : .
In preparing the recording elements, the polyester resin and any additives are first dissolved in or dispersed in a suitable solvent, such as toluene, and the resulting slurry , or solution is then coated onto a suitable base support and the material dried to remove the solvent. The amount of resin employed in the preparation of said elements may be varied over a wide range depending upon the desired properties and intended application of the electrographic recording element.
However, for most applications it has been found that an amount of resin which will result in a coating weight of from about ' 0.5 to about 10 pounds per ream (3,000 square feet) is preferred.
,,~ Especially preferred results are achieved at coating weights equal to from about 1 to about 5 pounds per ream.
~' .
3 As compared to the previously available electrographic recording elements, materials prepared in accordance with the present invention have been found to have improved charge accept-~, ance and improved charge retention properties.
,', Charge acceptance is measured by recording the amount of voltag,e on the electrographic recording element immediately after exposure to a source such as a corona discharge.
Charge retention is measured by recording the amount of voltage remaining on the recording element after a predeter-~, mined period of time. This property is generally defined in terms of the percentage of charge retained over a period of ~ .
time.
'', As mentioned above, in an electrographic recording or " printing process it is important that the recording element accept and retain a high charge. In this regard, it should be noted that both the charge acceptance and charge retention are frequently related to the amount of dielectric or insulating :
~.ID4682S
resin employed in the layer of the recording element. Thus, in addition to having high charge acceptance and charge re-tention properties it is desirable to achieve these properties at a relatively low coating weight as is possible with the resins which have been found to be useful for this purpose in accordance with the present invention.
In order to describe the present invention so that it may be more clearly understood, the following examples are set forth. These examples are set forth primarily for the 10 purpose of illustration and any enumeration of detail contained therein should not be interpreted as a limitation on the con-cept of the present invention.
In the examples the following standard tests were employed.
Charge acceptance was measured by a Most Stati-Tester available from M. K. Associates, Bosto~" Ma~s. and is expressed f in terms of volts. ~ -Charge retention was also measured on the Most Stati-Tester and is also given in volts. An important characteristic 20 of the materials prepared with the resins of the present inven-tion is the ability to retain a high charge during the period of from about 1 to about 4 minutes after termination of charging. The percent charge retention in the examples refers to the percent of the charge on the recording element after one minute which is retained by the material after 4 minutes. This is determined as follows:
., .
charge remaining % charge retention = after 4 minutes charge remaining after 1 minute Coating weight was determined by weighing a sample of \
` 1046825 the electrographic recording element, subtracting the weight - of the base support and calculating the weight of the coating in pounds per ream.
The following resins were used in the examples:
Resin A refers to a polyester resin, having an acid . number of 10 - 20, prepared by condensing 580 grams of fumaric acid with 1833 grams of polyoxypropylene(2.2)bisphenol A.
Resin B refers to a polyester resin, having an acid number of 21.7, comprising the reaction product of , 10 1810 grams of polyoxypropylene(2.2) bisphenol A, 15 grams of glycerine, and ,1' 6~3 grams of fumaric acid.
.:. ~
:' /
~ ' /
~1 /
~! /
il /
.~ /
., /
. /
' / ' , ': ' ;
,, ;~ ' Resin C refers to a polyester resin, having an acid number of 32.9, comprising the reaction product of 1737 grams of polyoxypropylene (2 2)bisphenol A, 86.3 grams of polyoxypropylene(6)sorbitol, and 676 grams of fumaric acid.
Resin D refers to a polyester resin, having an acid number of 21.25, comprising the reaction product of 423 grams of polyoxypropylene(2.2)bisphenol A, and 177 grams of phthalic anhydride.
r~A
A coating composition was prepared comprising 50 grams of Resin A
50 grams of toluene.
The composition was coated using a wire wound rod on Fletcher Tek (Registered Trade Mark) conductive papers and dried.
The properties of the resulting electrographic recording element are given below.
Coating Charge Charge Retention % Charge weightAcceptance after after Retention 20(lbs/ream) (volts) 1 min. 4 min.
2.7 588 197 177 90 8.1 718 580 515 89 Employing the procedure described in Example 1, several additional compositions were prepared, used to prepare electrographic recording elements and tested. The compositions and test results are given in the following Table:
:-, ';
' ':
, ~
. . ~ ~ ., ., W ~ U~, .. ,p~ ~ W W ~ ~ ~ ~ g ;~ O O ~ ~ ~
" U~.
,, o' a~ J ~I ~ ~--o o ~ ~ ~
'.~, ~g co 1~ ~ ~ ~ ~
i . w w co ~ w w ~2 . . ~
:~
00 ~ J Q ~ n .~ ao O O N~11 0 1--ID
CO O t~ ~ (Q
,,-,, , . U~ ID
;;, i ~D
' __ :. ~ n ~ .
~ o ~ _~ ~h ' . O ~ 0 00 0 0 ,,i . .
., . ~ W Ul ~ ~ ~n ~p) rD
'.' O X ~n W ~n Ul ~, ~t ~
~ ~ O-;' CO CO ~ CO ~D ~I ~D
',.............. ~ ~ O ~I ~S
., , . ul ~n Ul ~
.,~,, _ _ ~,;.,,
,', Charge acceptance is measured by recording the amount of voltag,e on the electrographic recording element immediately after exposure to a source such as a corona discharge.
Charge retention is measured by recording the amount of voltage remaining on the recording element after a predeter-~, mined period of time. This property is generally defined in terms of the percentage of charge retained over a period of ~ .
time.
'', As mentioned above, in an electrographic recording or " printing process it is important that the recording element accept and retain a high charge. In this regard, it should be noted that both the charge acceptance and charge retention are frequently related to the amount of dielectric or insulating :
~.ID4682S
resin employed in the layer of the recording element. Thus, in addition to having high charge acceptance and charge re-tention properties it is desirable to achieve these properties at a relatively low coating weight as is possible with the resins which have been found to be useful for this purpose in accordance with the present invention.
In order to describe the present invention so that it may be more clearly understood, the following examples are set forth. These examples are set forth primarily for the 10 purpose of illustration and any enumeration of detail contained therein should not be interpreted as a limitation on the con-cept of the present invention.
In the examples the following standard tests were employed.
Charge acceptance was measured by a Most Stati-Tester available from M. K. Associates, Bosto~" Ma~s. and is expressed f in terms of volts. ~ -Charge retention was also measured on the Most Stati-Tester and is also given in volts. An important characteristic 20 of the materials prepared with the resins of the present inven-tion is the ability to retain a high charge during the period of from about 1 to about 4 minutes after termination of charging. The percent charge retention in the examples refers to the percent of the charge on the recording element after one minute which is retained by the material after 4 minutes. This is determined as follows:
., .
charge remaining % charge retention = after 4 minutes charge remaining after 1 minute Coating weight was determined by weighing a sample of \
` 1046825 the electrographic recording element, subtracting the weight - of the base support and calculating the weight of the coating in pounds per ream.
The following resins were used in the examples:
Resin A refers to a polyester resin, having an acid . number of 10 - 20, prepared by condensing 580 grams of fumaric acid with 1833 grams of polyoxypropylene(2.2)bisphenol A.
Resin B refers to a polyester resin, having an acid number of 21.7, comprising the reaction product of , 10 1810 grams of polyoxypropylene(2.2) bisphenol A, 15 grams of glycerine, and ,1' 6~3 grams of fumaric acid.
.:. ~
:' /
~ ' /
~1 /
~! /
il /
.~ /
., /
. /
' / ' , ': ' ;
,, ;~ ' Resin C refers to a polyester resin, having an acid number of 32.9, comprising the reaction product of 1737 grams of polyoxypropylene (2 2)bisphenol A, 86.3 grams of polyoxypropylene(6)sorbitol, and 676 grams of fumaric acid.
Resin D refers to a polyester resin, having an acid number of 21.25, comprising the reaction product of 423 grams of polyoxypropylene(2.2)bisphenol A, and 177 grams of phthalic anhydride.
r~A
A coating composition was prepared comprising 50 grams of Resin A
50 grams of toluene.
The composition was coated using a wire wound rod on Fletcher Tek (Registered Trade Mark) conductive papers and dried.
The properties of the resulting electrographic recording element are given below.
Coating Charge Charge Retention % Charge weightAcceptance after after Retention 20(lbs/ream) (volts) 1 min. 4 min.
2.7 588 197 177 90 8.1 718 580 515 89 Employing the procedure described in Example 1, several additional compositions were prepared, used to prepare electrographic recording elements and tested. The compositions and test results are given in the following Table:
:-, ';
' ':
, ~
. . ~ ~ ., ., W ~ U~, .. ,p~ ~ W W ~ ~ ~ ~ g ;~ O O ~ ~ ~
" U~.
,, o' a~ J ~I ~ ~--o o ~ ~ ~
'.~, ~g co 1~ ~ ~ ~ ~
i . w w co ~ w w ~2 . . ~
:~
00 ~ J Q ~ n .~ ao O O N~11 0 1--ID
CO O t~ ~ (Q
,,-,, , . U~ ID
;;, i ~D
' __ :. ~ n ~ .
~ o ~ _~ ~h ' . O ~ 0 00 0 0 ,,i . .
., . ~ W Ul ~ ~ ~n ~p) rD
'.' O X ~n W ~n Ul ~, ~t ~
~ ~ O-;' CO CO ~ CO ~D ~I ~D
',.............. ~ ~ O ~I ~S
., , . ul ~n Ul ~
.,~,, _ _ ~,;.,,
Claims (16)
1. An electrographic recording element comprising a base support having coated thereon a layer comprising a poly-ester resin, said polyester resin comprising the reaction product of a dicarboxylic acid and an aromatic polyhydric alcohol of the following general formula wherein a is 0 or 1, R is selected from the group consisting of Cl to C5 alkylene, oxygen, sulfur, or a divalent radical having one of the following formulas , or A is halogen or hydrogen, m and n are integers each of which is equal to at least 1 and the sum of which is equal to from 2 to less than 7 and X and Y are methyl, phenyl, or hydrogen provided that, in any X and Y pair on adjacent carbon atoms, either X or Y is hydrogen, provided that at least 80 mol percent of the di-carboxylic acid is selected from the group consisting of alpha-unsaturated dicarboxylic acids and aromatic dicarboxylic acids.
2. An electrographic recording element as claimed in Claim 1 wherein the said aromatic polyhydric alcohol is prepared by reacting from 2 mols to 7 mols of an alkylene oxide selected from ethylene, propylene or styrene oxide with one mol of a dihydric phenol of the formula wherein A is halogen or hydrogen, a is 0 or 1 and R is selected from C1 to C5 alkylene, oxygen, sulfur or a divalent radical having one of the formulas , or
3. An electrographic recording element, as claimed in Claim 1, wherein the base support is selected from electric-ally conductive paper, film, cloth and metal foil.
4. An electrographic recording element as claimed in Claim 1, wherein the dicarboxylic acid is selected from the group consisting of alpha-unsaturated dicarboxylic acids and aromatic dicarboxylic acids.
5. An element as claimed in Claim 3 wherein the alpha-unsaturated dicarboxylic acid is selected from maleic acid and fumaric acid, or anhydrides of these acids.
6. An element as claimed in Claim 3 wherein the aromatic dicarboxylic acid is selected from phthalic acid, isophthalic acid and terephthalic acid, or anhydrides of these acids
7. An electrographic recording element as claimed in Claim 1 wherein the amount of dicarboxylic acid employed in the preparation of the polyester resin is such that the mol ratio of carboxyl groups to hydroxyl groups is equal to from about 0.8 to about 1.2.
8. An electrographic recording element as claimed in Claim 7 wherein the mol ratio is equal to about 1.
9. An electrographic recording element as claimed in Claim 1 wherein a mixture of acids is employed in the pre-paration of the polyester resin.
10. An electrographic recording element as claimed in Claim 9 wherein at least 80 mol percent of said mixture is a dicarboxylic acid selected from the group consisting of alpha-unsaturated dicarboxylic acids and aromatic dicarboxylic acids.
11. An electrographic recording element as claimed in Claim 1 wherein the sum of m and n is equal to about 2,
12. An electrographic recording element as claimed in Claim 1 wherein the coating weight is equal to from about 0.5 to about 10 pounds per ream.
13. An electrographic recording element as claimed in Claim 1 wherein the coating weight is equal to from about 1 to about 5 pounds per ream.
14. An electrographic recording element as claimed in Claim 1 wherein the polyester resin is a polyoxyalkylene bisphenol A fumarate.
15. An electrographic recording element as claimed in Claim 1 wherein the polyester resin is a polyoxypropylene bisphenol A fumarate.
16. An electrographic recording element as claimed in Claim 14 wherein the polyoxypropylene bisphenol A fumarate contains an average of 2,2 oxypropylene groups per mol of bisphenol A.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US36241773A | 1973-05-21 | 1973-05-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1046825A true CA1046825A (en) | 1979-01-23 |
Family
ID=23426045
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA198,559A Expired CA1046825A (en) | 1973-05-21 | 1974-04-30 | Electrographic recording element with polyester resin coated on base support |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5720620B2 (en) |
| CA (1) | CA1046825A (en) |
| GB (1) | GB1431415A (en) |
| IT (1) | IT1011416B (en) |
| NL (1) | NL176982C (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4173472A (en) * | 1976-06-15 | 1979-11-06 | Eastman Kodak Company | Polyester interlayer and binder component in multilayer photoconductive element |
| US4284699A (en) * | 1977-02-14 | 1981-08-18 | Eastman Kodak Company | Polyester binder component in multilayer photoconductive element |
| US9682000B2 (en) | 2013-01-20 | 2017-06-20 | Bioness, Inc. | Methods and apparatus for body weight support system |
| EP3373880A4 (en) | 2015-11-11 | 2019-05-01 | Bioness Inc. | Apparatus and methods for support track and power rail switching in a body weight support system |
| CA3050322A1 (en) | 2017-02-14 | 2018-08-23 | Bioness Inc. | Methods and apparatus for body weight support system |
-
1974
- 1974-04-26 GB GB1839074A patent/GB1431415A/en not_active Expired
- 1974-04-30 CA CA198,559A patent/CA1046825A/en not_active Expired
- 1974-05-08 NL NL7406164A patent/NL176982C/en not_active IP Right Cessation
- 1974-05-10 IT IT5089674A patent/IT1011416B/en active
- 1974-05-14 JP JP5295374A patent/JPS5720620B2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IT1011416B (en) | 1977-01-20 |
| GB1431415A (en) | 1976-04-07 |
| NL176982B (en) | 1985-02-01 |
| NL176982C (en) | 1985-07-01 |
| NL7406164A (en) | 1974-11-25 |
| JPS5720620B2 (en) | 1982-04-30 |
| JPS5020727A (en) | 1975-03-05 |
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