GB2039789A - Electrostatic Imaging Sheet - Google Patents
Electrostatic Imaging Sheet Download PDFInfo
- Publication number
- GB2039789A GB2039789A GB7939093A GB7939093A GB2039789A GB 2039789 A GB2039789 A GB 2039789A GB 7939093 A GB7939093 A GB 7939093A GB 7939093 A GB7939093 A GB 7939093A GB 2039789 A GB2039789 A GB 2039789A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sheet
- polymer
- smectite clay
- water dispersible
- electrostatic imaging
- 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.)
- Granted
Links
- 238000003384 imaging method Methods 0.000 title claims abstract description 26
- 229920000642 polymer Polymers 0.000 claims abstract description 45
- 239000004927 clay Substances 0.000 claims abstract description 37
- 239000000463 material Substances 0.000 claims abstract description 31
- 229910021647 smectite Inorganic materials 0.000 claims abstract description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000000203 mixture Substances 0.000 claims abstract description 24
- AZJYLVAUMGUUBL-UHFFFAOYSA-A u1qj22mc8e Chemical compound [F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].O=[Si]=O.O=[Si]=O.O=[Si]=O.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3 AZJYLVAUMGUUBL-UHFFFAOYSA-A 0.000 claims abstract description 23
- 239000008199 coating composition Substances 0.000 claims abstract description 21
- 239000006185 dispersion Substances 0.000 claims abstract description 17
- 239000002245 particle Substances 0.000 claims abstract description 10
- 229920000098 polyolefin Polymers 0.000 claims abstract description 10
- 230000004888 barrier function Effects 0.000 claims abstract description 9
- 229920000058 polyacrylate Polymers 0.000 claims abstract description 6
- -1 polytetrafluoroethylene Polymers 0.000 claims abstract description 6
- 229920001909 styrene-acrylic polymer Polymers 0.000 claims abstract description 6
- 230000008961 swelling Effects 0.000 claims abstract description 6
- 239000004952 Polyamide Substances 0.000 claims abstract description 5
- 239000005062 Polybutadiene Substances 0.000 claims abstract description 5
- 239000004793 Polystyrene Substances 0.000 claims abstract description 5
- 229920001577 copolymer Polymers 0.000 claims abstract description 5
- 229920002647 polyamide Polymers 0.000 claims abstract description 5
- 229920002857 polybutadiene Polymers 0.000 claims abstract description 5
- 229920000515 polycarbonate Polymers 0.000 claims abstract description 5
- 239000004417 polycarbonate Substances 0.000 claims abstract description 5
- 229920000728 polyester Polymers 0.000 claims abstract description 5
- 229920002223 polystyrene Polymers 0.000 claims abstract description 5
- 229920002554 vinyl polymer Polymers 0.000 claims abstract description 5
- 229920001328 Polyvinylidene chloride Polymers 0.000 claims abstract 4
- 239000005033 polyvinylidene chloride Substances 0.000 claims abstract 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims abstract 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims abstract 3
- 239000011248 coating agent Substances 0.000 claims description 29
- 238000000576 coating method Methods 0.000 claims description 29
- 238000000034 method Methods 0.000 claims description 29
- 125000002091 cationic group Chemical group 0.000 claims description 11
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- KWLMIXQRALPRBC-UHFFFAOYSA-L hectorite Chemical group [Li+].[OH-].[OH-].[Na+].[Mg+2].O1[Si]2([O-])O[Si]1([O-])O[Si]([O-])(O1)O[Si]1([O-])O2 KWLMIXQRALPRBC-UHFFFAOYSA-L 0.000 claims description 6
- 239000011256 inorganic filler Substances 0.000 claims description 6
- 229910003475 inorganic filler Inorganic materials 0.000 claims description 6
- 239000000725 suspension Substances 0.000 claims description 4
- 230000009974 thixotropic effect Effects 0.000 claims description 3
- 229940094522 laponite Drugs 0.000 description 7
- XCOBTUNSZUJCDH-UHFFFAOYSA-B lithium magnesium sodium silicate Chemical compound [Li+].[Li+].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Na+].[Na+].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3 XCOBTUNSZUJCDH-UHFFFAOYSA-B 0.000 description 7
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 6
- 239000005995 Aluminium silicate Substances 0.000 description 5
- 235000012211 aluminium silicate Nutrition 0.000 description 5
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 239000000835 fiber Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000004698 Polyethylene Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 241001417490 Sillaginidae Species 0.000 description 2
- 238000005703 Whiting synthesis reaction Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007812 deficiency Effects 0.000 description 2
- 239000003989 dielectric material Substances 0.000 description 2
- 239000004815 dispersion polymer Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910000271 hectorite Inorganic materials 0.000 description 2
- 239000003906 humectant Substances 0.000 description 2
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 2
- 229920000867 polyelectrolyte Polymers 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000004408 titanium dioxide Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000004908 Emulsion polymer Substances 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- 230000001588 bifunctional effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000003490 calendering Methods 0.000 description 1
- 238000001246 colloidal dispersion Methods 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052901 montmorillonite Inorganic materials 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 150000003856 quaternary ammonium compounds Chemical class 0.000 description 1
- 239000013557 residual solvent Substances 0.000 description 1
- 238000000518 rheometry Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
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
- G03G5/10—Bases for charge-receiving or other layers
- G03G5/101—Paper bases
-
- 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
- G03G5/0217—Inorganic components
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Paper (AREA)
Abstract
An electrostatic imaging sheet wherein one side of the sheet, e.g. paper, is electrically conductive and the other side of the sheet has a continuous dielectric layer comprising a mixture of a smectite clay e.g. a synthetic hectorite swelling clay and an electrically insulating polymer, preferably in particle form. The dielectric layer may comprise a layer of a smectite clay which forms a barrier between the electrically conductive layer and the layer of insulating polymer. The invention is also a dielectric coating composition comprising a mixture of electrically insulating polymer in aqueous dispersion and a water dispersible smectite clay. The polymer may be selected from the group consisting of polyalkenes, substituted polyalkenes, acrylic polymers, vinyl polymers, polystyrene, polyesters, polyvinylidene chloride, polyamides, polycarbonates, polytetrafluoroethylene, polybutadiene, co-polymers of these materials and styrene acrylic copolymers.
Description
SPECIFICATION
Electrostatic Imaging Sheet
The invention relates to a method of coating sheet material and to a dielectric coating composition for use in the method. More particularly the invention relates to an electrostatic imaging sheet comprising a base, e.g. of paper, having an electroconductive layer and having on one side a continuous layer of a dielectric material.
From U.S. Patent Specification No. 3075859 of A.B. Dick Company it is known that a latent electrostatic image may be transferred from a suitably charged array to a copy sheet and that this latent image may then be developed by means of applying and fixing charged toner particles. For this process to operate satisfactorily it is necessary for the copy sheet to have certain properties, particularly in that it should comprise two layers, one being an electrically conducting base sheet and the other being an electrically insulating or dielectric layer which receives the latent image in the form of an electrostatic charge and is capable of retaining the charge for a period of time sufficient to allow development and fixing.
It is known to produce an electrically conducting base sheet by adding to a base paper conducting salts or polyelectrolyte resins or humectant materials or combinations of these materials. The conducting salts, humectants and polyelectrolyte resins being water soluble may be added to the fibre slurry in the papermaking process or may be applied by various means after formation of the paper sheet.
It is also known to coat such a conducting base sheet with a solvent solution of an electrically insulating polymer and by removal of residual solvent to produce a dielectric copy sheet.
It has been appreciated for a long time that it would be advantageous for the dielectric layer to be applied as an aqueous coating and a number of attempts have been made in this direction involving the use of different water soluble polymers, emulsion polymers and the like. These attempts have not been significantly successful because of inherent deficiencies in the materials themselves, and also because of production difficulties, since as the conductive elements of the base sheet are intrinsically water miscible they tend to migrate into the dielectric coating with consequent deleterious effect upon its resistivity, its ability to perform as a charge receptor, and the ability of the sheet as a whole to form and hold an image in use.
It is an object of this invention to provide an electrostatic imaging paper using an aqueous system to apply the dielectric layer, but in such a manner as to overcome the prior art deficiencies.
From a first aspect the invention provides an electrostatic imaging sheet wherein one side of the sheet is electrically conductive and the other side of the sheet has a continuous dielectric layer comprising a mixture of a smectite clay and an electrically insulating polymer.
From another aspect the invention provides an electrostatic imaging sheet wherein one side of the sheet is electrically conductive and the other side of the sheet has a layer of a smectite clay which forms a barrier between the electrically conductive layer and a dielectric layer of an insulating polymer.
From a further aspect the invention provides a dielectric coating composition comprising a mixture of electrically insulating polymer jn aqueous dispersion and a water dispersible smectite clay.
From yet another aspect the invention provides a method of coating a sheet material which comprises dispersing a mixture of an electrically insulating polymer and a water dispersible smectite clay in an aqueous system and coating the sheet material with the aqueous dispersion.
From a still further aspect the invention provides a method of coating a sheet material to produce an electrostatic imaging sheet comprising coating one side of the sheet material with an aqueous dispersion of water dispersible smectite clay, to form a barrier on the sheet prior to coating the sheet with an aqueous system containing an electrically insulating polymer.
In practice a coating composition as described above will usually be in the form of a colloidal suspension, although alternatively it can be in the form of a thixotropic gel. The coating composition may incorporate other materials, e.g. inorganic fillers such as kaolin, titanium dioxide, whitings, china clay and the like.
Suitable polymers may be selected from the following namely polyalkenes, substituted polyalkenes, acrylic polymers, vinyi polymers, polystyrene, polyesters, polyvinylidine chloride, polyamides, polycarbonates, polytetrafluoroethyíene, polybutadiene, copolymers of these materials, and styrene acrylic co-polymers. The polymer may be in fibre or particle form or as a solution, dispersion or colloidal suspension. The polymer is preferably in the form of an aqueous suspension of fine particles e.g. in the range 0.1 to 10 microns.
The water dispersible smectite clay possesses a layered lattice or platelet type structure, and includes the so called swelling clay varieties montmorillonite, bentonite and hectorite.
Particularly useful is the synthetic hectorite swelling clay sold by Laporte Industries Ltd. under the registered trade mark LAPONITE. This material disperses in water or aqueous polymer containing compositions to give colloidal dispersions of suitable rheology for sheet coating purposes. The colloidal nature, primary particle size and morphology of the synthetic hectorite is advantageous since the hectorite containing composition has the property of remaining on the surface of the sheet rather than soaking in and mixing with conducting layer. This is particularly of importance where it is desired to coat a groundwood or mechanical paper, which has a relatively open structure.The primary particle morphology, namely a platelet-like structure, and the excellent film forming properties of the synthetic hectorite are of further value in that they tend to prevent penetration and poisoning of the dielectric layer by conductive elements. The synthetic hectorite possesses a further useful property namely that in aqueous dispersion the synthetic hectorite is anionic in character. It will therefore react with cationic materials such as those typically used to provide the conductivity of the base sheet to form an ionically inert material, and when this reaction occurs a physical barrier against migration is formed between the two layers.Once dried, the synthetic hectorite film ceases to be ionic and therefore does not detract from the dielectric properties of the polymer present in the composition, and indeed contributes to the establishement and maintentance of the desired electrical properties of the sheet surface. The film forming properties and structure of the film also serve to prevent lifting of fibres from the base sheet.
A sheet of dielectric paper in accordance with the invention may be produced in a number of ways, for example:- (1) By applying a coating composition comprising the polymer and synthetic hectorite to a sheet of paper which has been previously treated to render it electrically conductive.
(2) By applying the coating composition comprising the polymer and synthetic hectorite to a sheet of untreated paper as a first step and applying the conductive coating or treatment as a second step.
Either of these two processes may be applied as a continuous or machine process during the manufacture of the paper, or part or all of the coating operation may be carried out as an offmachine process on suitable pre-produced base paper. Alternatively it may be advantageous to add either the electrically conductive material, or the dielectric composition to the fibre slurry before formation of the web. Other processes normally applied in the manufacture of paper will of course be relevant in the manufacture of the sheet within the scope of this invention, e.g.
drying, calendaring etc. In the case of drying, it may be necessary to apply heat additonal to that required for drying per se, in order fully to cure the dielectric coating
It is also proposed to form an electrostatic imaging sheet in the following manner. A coating of synthetic hectorite in aqueous dispersion is first applied to a base sheet, which is either treated to render it conductive or plain as desired, and the coating, which forms a barrier, is then dried. A second coating comprising an aqueous polymer system is then applied on top of the synthetic hectorite layer. The second coating would normally include inert filler material such as kaolin, and may beneficially contain synthetic hectorite in dispersion.In the case of application of the above described two coat system to plain untreated base paper a further treatment of the base paper with electrically conductive resin is then required.
It might be desirable to mitigate against the possibility of the electrical charging of dielectric sheet material due to the ionic properties of the synthetic hectorite when in the presence of water.
To achieve this in accordance with the invention the synthetic hectorite may be reacted with a cationic agent so as to block at least partly the ionic sites on the hectorite structure. The ionic blocking has the effect of preventing an increase in the electrical conductivity of the coating at high relative humidity and also has the effect of breaking down the colloid or gel with a consequent improvement in ease of coating.
The cationic agent may be a bifunctional cationic, a polymeric cationic, or a quaternary ammonium compound.
The reaction may be carried out stoichiometrically or alternatively an excess of the cationic agent may be used and the excess charge neutralised subsequently.
The invention will now be specifically described by means of the following examples.
Dielectric material aqueous dispersion coating compositions were prepared as follows, in which all parts are by weight.
Example 1
Parts
An acrylic polymer dispersion,
e.g. that sold by Ashland
Chemical Company Inc. under
the trade name ASHLAND DEA-015 200
Kaolin 100
Laponite (Registered Trade Mark) 4
Example 2
Polyethylene polymer dispersion 200
Titanium dioxide 80
Laponite 8
Example 3
Styrene acrylic polymeric
dispersion e.g. VINACRYL
7170 (Vinyl Products Ltd.) 180
Silica pigment material 20
Laponite 5
Example 4
Polyvinyl Butyral e.g.Butvar B
76 (Monsanto Europe N.V.) 100
Water 100
Kaolin 110
Dispersant 0.5
Laponite 4
Example 5
Polyethylene pulp fibre e.g
Pulpex (Solvay Cie) 10
Water 190
Kaolin 50
Laponite 4
Example 6
Polyethylene polymer particle size
between 0.2-10 microns 100
Whitings 1 00
Water 200
Laponite 6
Coating compositions within the scope of the invention contain between 0.25 and 5% by weight of synthetic hectorite and preferably between 2 and 4% by weight of synthetic hectorite, on the assumption that the filler is excluded from the calculation. The proportions and nature of both the polymer and filler present may vary within wide limits governed by factors including the electrical properties of the materials, the viscosity of the composition, the behaviour of the composition under shear and so on.
The dielectric coating is applied to a base paper to give coat weights between 2 and 25 gms/m2 and preferably between 5 and 10 gms/m2.
Electrostatic imaging paper produced by coating paper with the compositions of the above
Examples was tested by the normal procedures established for evaluating dielectric papers and was found to be satisfactory.
Claims (45)
1. An electrostatic imaging sheet wherein one side of the sheet is electrically conductive and the other side of the sheet has a continuous dielectric layer comprising a mixture of a smectite clay and an electrically insulating polymer.
2. An electrostatic imaging sheet according to claim 1, wherein the mixture of smectite clay and polymer comprises an inorganic filler.
3. An electrostatic imaging sheet according to claim 1 or claim 2, comprising a layer of smectite clay forming a barrier on the sheet between the electrically conductive layer and the dielectric layer.
4. An electrostatic imaging sheet wherein one side of the sheet is electrically conductive and the other side of the sheet has a layer of a smectite clay which forms a barrier between the electrically conductive layer and a dielectric layer of an insulating polymer.
5. An electrostatic imaging sheet according to any preceding claim, wherein the water dispersible smectite clay is a synthetic hectorite swelling clay.
6. An electrostatic imaging sheet according to any preceding claim, wherein the polymer is selected from the group consisting of polyalkenes, substituted polyalkenes, acrylic polymers, vinyl polymers, polystyrene, polyesters, polyvinylidene chloride, polyamides, polycarbonates, polytetrafiuornethylene, polybutadiene, co- polymers of these materials and styrene acrylic co-polymers.
7. An electrostatic imaging sheet according to claim 6, wherein the polymer is in particle form.
8. An electrostatic imaging sheet according to
claim 7, wherein the particle size of the polymer is
in the range 0.1 to 10 microns.
9. An electrostatic imaging sheet according to
any preceding claim, wherein the sheet is paper.
1 0. An electrostatic imaging sheet according
to claim 9, wherein the paper is a mechanically
produced paper.
11. An electrostatic imaging sheet according
to any preceding claim, wherein the sheet is
rendered electrically conductive by a cationic
material.
12. An electrostatic imaging sheet according
to any preceding claim, wherein the water
dispersible smectite clay is a synthetic hectorite which has been reacted with a cationic agent to
block at least partly the ionic sites on the
hectorite structure.
13. An electrostatic imaging sheet
substantially as hereinbefore described.
14. A dielectric coating composition
comprising a mixture of electrically insulating
polymer in aqueous dispersion and a water
dispersible smectite clay.
1 5. A dielectric coating composition according
to claim 14, wherein the water dispersible
smectite clay is a synthetic hectorite swelling
clay.
1 6. A dielectric coating composition according
to claim 14 or claim 15, wherein the polymer is
selected from the group consisting of polyalkenes,
substituted polyalkenes, acrylic polymers, vinyl
polymers, polystyrene, polyesters, polyvinylidene
chloride, polyamides, polycarbonates,
polytetrafluoroethylene, polybutadiene, co
polymers of these materials and styrene acrylic
co-polymers.
1 7. A dielectric coating composition according
to claim 16, wherein the polymer is in particle form.
18. A dielectric coating according to claim 17,
wherein the particle size of the polymer is in the
range 0.1 to 10 microns.
1 9. A dielectric coating composition according to any one of claims 1 6 to 18, wherein the
polymer is in aqueous dispersion.
20. A dielectric coating composition according
to any one of claims 14 to 19, comprising an
inorganic filler.
21. A dielectric coating composition according
to any one of claims 14 to 20, wherein the
mixture of polymer and water dispersible smectite
clay forms a thixotropic gel,
22. A dielectric coating composition according
to any one of claims 14 to 20, wherein the mixture
of polymer and water dispersible smectite clay
forms a colloidal suspension.
23. A dielectric coating composition according
to any one of claims 14 to 22, wherein the water dispersible smectite clay is a synthetic hectorite which has been reacted with a cationic agent to block at least partly the ionic sites on the hectorite structure.
24. A dielectric coating composition according to any one of claims 14 to 23, wherein the amount of smectite clay is in the range 0.5 to 5% by weight of the composition excluding inorganic filler.
25. A dielectric coating composition according to claim 24, wherein the amount of smectite clay is in the range 2 to 4% by weight of the composition, excluding inorganic filler.
26. A dielectric coating composition substantially as hereinbefore described with reference to any one of the Examples.
27. An electrostatic imaging sheet coated with the composition of any one of claims 14 to 26.
28. A method of coating a sheet material which comprises dispersing a mixture of an electrically insulating polymer and a water dispersible smectite clay in an aqueous system and coating the sheet material with the aqueous dispersion.
29. A method according to claim 28, wherein the mixture of polymer and water dispersible smectite clay forms a thixotropic gel.
30. A method according to claim 28, wherein the mixture of polymer and water dispersible smectite clay forms a colloidal suspension.
31. A method according to any one of claims 28 to 30, comprising coating the sheet material with an aqueous dispersion of the water dispersible smectite clay to form a physical barrier on the sheet prior to coating the sheet with the mixture of electrically insulating polymer and water dispersible smectite clay.
32. A method of coating a sheet material to produce an electrostatic imaging sheet comprising coating one side of the sheet material with an aqueous dispersion of water dispersible smectite clay to form a barrier on the sheet prior to coating the sheet with an aqueous system containing an electrically insulating polymer.
33. A method according to claim 32, wherein the aqueous system containing an electrically insulating polymer also coantains water dispersible smectite clay.
34. A method according to any one of claims 28 to 33, wherein the smectite clay is a synthetic hectorite swelling clay.
35. A method according to any one of claims 28 to 34, wherein the polymer is selected from the group consisting of polyalkenes, substituted polyalkenes, acrylic polymers, vinyl polymers, polystyrene, polyesters, polyvinylidene chloride, polyamides, polycarbonates, polytetrafluoroethylene, polybutadiene, copolymers of these materials, and styrene acrylic co-polymers.
36. A method according to claim 35, wherein the polymer is in particle form.
37. A method according to claim 35, wherein the particle size of the polymer is in the range 0.1 to 10 microns.
38. A method according to any one of claims 35 to 37, wherein the polymer is in aqueous dispersion.
39. A method according to claim 38, wherein the aqueous dispersion of polymer comprises an inorganic filler.
40. A method according to any one of claims 28 to 39, wherein the sheet material is paper.
41. A method according to claim 40, wherein the paper is a mechanically produced paper.
42. A method according to any one of claims 28 to 41, wherein the sheet material is rendered electrically conductive by the application of a cationic material.
43. A method according to any one of claims 28 to 42, wherein the water dispersible smectite clay is a synthetic hectorite and comprising the step of reacting the synthetic hectorite with a cationic agent to block at least partly the ionic sites on the hectorite structure.
44. A method of coating a sheet material substantially as hereinbefore described.
45. An electrostatic imaging sheet coated by the method of any one of claims 28 to 44.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7939093A GB2039789B (en) | 1978-11-13 | 1979-11-12 | Electrostatic imaging sheet |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7844242 | 1978-11-13 | ||
| GB7939093A GB2039789B (en) | 1978-11-13 | 1979-11-12 | Electrostatic imaging sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2039789A true GB2039789A (en) | 1980-08-20 |
| GB2039789B GB2039789B (en) | 1983-04-13 |
Family
ID=26269555
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7939093A Expired GB2039789B (en) | 1978-11-13 | 1979-11-12 | Electrostatic imaging sheet |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2039789B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2202464A (en) * | 1987-03-20 | 1988-09-28 | Ecc Int Ltd | Paper coating |
| EP0337771A1 (en) * | 1988-04-12 | 1989-10-18 | Ecc International Limited | Paper coating |
| US5360643A (en) * | 1992-02-11 | 1994-11-01 | International Paper Company | Electrostatic recording media |
| US5929155A (en) * | 1995-01-20 | 1999-07-27 | Le Groupe Recherche I.D. Inc. | Method and composition for providing repulpable moisture vapor barrier coating for flexible packaging |
| EP4183843A4 (en) * | 2020-07-15 | 2023-11-22 | Denka Company Limited | Composition and cured body |
-
1979
- 1979-11-12 GB GB7939093A patent/GB2039789B/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2202464A (en) * | 1987-03-20 | 1988-09-28 | Ecc Int Ltd | Paper coating |
| EP0337771A1 (en) * | 1988-04-12 | 1989-10-18 | Ecc International Limited | Paper coating |
| WO1989009852A1 (en) * | 1988-04-12 | 1989-10-19 | Ecc International Limited | Paper coating |
| US5360643A (en) * | 1992-02-11 | 1994-11-01 | International Paper Company | Electrostatic recording media |
| WO1994028465A1 (en) * | 1992-02-11 | 1994-12-08 | International Paper Company | Electrostatic recording media |
| US5929155A (en) * | 1995-01-20 | 1999-07-27 | Le Groupe Recherche I.D. Inc. | Method and composition for providing repulpable moisture vapor barrier coating for flexible packaging |
| EP4183843A4 (en) * | 2020-07-15 | 2023-11-22 | Denka Company Limited | Composition and cured body |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2039789B (en) | 1983-04-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |