JPH04216562A - Method for forming electrostatic polychrome toner image and receptor sheet - Google Patents

Abstract

PURPOSE: To form an image displayed outdoors by temporarily forming a multi- color intermediate image on a dielectric receptor by continuously developing an electrostatic image by toner and transferring the intermediate image on a permanent receptor. CONSTITUTION: A paper base material 2 having a dielectric layer 4 and a release cover 6 on one surface is included in the photoconductive intermediate receptor 1. The receptor 1 is passed through a station in a direction shown by an arrow 8 so that the surface thereof covered with a paper is passed through a needle type write head 10. By the head 10, electric charge 12 is accumulated along the image by leaving an uncharged surface area 14. Besides, the receptor 1 passed through the head 10 is passed through a toner station including a toner applicator 16 brought into contact with the liquid toner bath 18 of a container 20. Then, liquid toner 22 is carried by the applicator 16 and accumulated on the receptor 1 along the image so as to form an area with toner 24 and a no-toner area 26.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for producing large size full color images by electronic imaging means. In particular, the present invention relates to receptor sheets for use in multicolor electronic imaging methods in which a one-pass printer is used to transfer an image to a receptor surface.

0002

BACKGROUND OF THE INVENTION A general discussion of color electrophotography is provided by R.M. Schaffert.
fert), “Electrophotography” (Ele
Focal Press, London and New York (1975), pp. 178-190.

[0003] Full-color copying using electrophotography is
Although it was disclosed in an earlier patent by C.F. Charlson (US Pat. No. 2,297,691), the detailed mechanism was not described. Another early patent by C.W. Jacob (U.S. Pat. No. 2,752,833) was
A method is disclosed that is based on a single transparent drum coated with a photoconductor and around which a web of receptor paper is provided. An electrostatic image is formed on the drum, directed to receptor paper, and exposed to three-color line-scan light from inside the drum using a CRT. For each of these scan positions, with an appropriate time delay between scans,
It is preceded by a charging station, followed by a toner station. The final three-color image is assembled directly onto the image paper.

In US Pat. No. 4,033,688 (Agfa-Gevaert), a single photoconductive drum is exposed by three different color beams reflected from a color original. The resulting reflections occur at surrounding points, each point having the necessary charging and toner stations. Due to mechanical time delay,
A three-color image is written and then the image is transferred to a receptor sheet.

Other similar systems are disclosed in US Pat.
No. 03,848 and No. 4,467,334. All of these systems employ optical exposure without mechanical contact with the surface to address the imaging surface. Other methods (e.g. U.S. Pat. No. 4,728
Color prints can be made at higher production speeds by using successive exposure/toning stations immediately following each other, as opposed to multiple drum rotations such as those found in U.S. Pat.

[0006] Many patents (eg, US Pat. No. 2,98
No. 6,466, No. 3,690,756, No. 4,3
No. 70,047) uses three or four different photoconductor drums or belts for different colors to assemble a registered toner image onto a receptor sheet.

Conventional optical scanning exposure is disclosed in a number of patents, such as US Pat. No. 3,690,756, US Pat. . CRT scanning is covered by U.S. Patent No.
, 752,833, the laser scanning itself and its combination with conventional exposure
U.S. Patent No. 4,234,250, U.S. Patent No. 4,236,8
No. 09, No. 4,336,994, No. 4,348,
No. 100, No. 4,370,047, No. 4,403
, No. 848 and No. 4,467,334.

[0008] Unlike the electrophotographic methods previously described, electroimaging methods are well described in the art. In this method, an electrostatic latent image is formed by "shooting" a charge imagewise directly onto a dielectric receiving surface. To create such a charge pattern, styluses are often used and arranged in a linear array across the width of the moving dielectric surface. Such methods and necessary apparatus are described, for example, in U.S. Pat. No. 4,007,489;
No. 4, No. 4,731,542 and No. 4,808
, No. 832. U.S. Patent No. 4,569,
In the '584, only one row of needles is used, the receiving surface web is moved back and forth to create a continuous image, and toner stations are placed on either side of a single charging station. In the other three patents cited above, printers include three or more printing stations in series, each station including a charging array and a toner station. In all of these, a multicolor toner image is assembled onto a receiving surface and fixed and displayed on that surface which is a support. In these documents, transfer of the assembled image to the receptor surface is neither disclosed nor discussed.

C.F. Charleson (US Patent No. 2)
, 297, 691) is a dry powder. Staughan (U.S. Patent No. 2)
, 899, 335) and Metcalf (Metoka
lfe) and Wright (U.S. Pat. No. 2)
, 907,674) pointed out that dry toners are subject to a number of limitations with respect to image quality, particularly when used in superimposed color images. They recommend using liquid toner for this purpose. The liquid toner is a carrier having a high resistivity, for example 109 ohm-cm or more, and having both colorant particles dispersed in the liquid and, preferably, an additive to enhance the charge carried by the colorant particles. Contains liquid. Matkan (Matkan)
(U.S. Pat. No. 3,337,340) discloses that the initially deposited toner may be sufficiently conductive to interfere with the subsequent charging step, and that each colorant particle The patent claims that an insulating resin with a low dielectric constant (3.5 or less) (resistivity of 1010 ohm-cm or more) is used to cover the substrate.

No. 4,155,862 related the charge per unit amount of toner to the difficulties experienced in the art in superimposing several layers of different colored toners. This latter problem is approached differently in U.S. Pat. No. 4,275,136, which teaches that the adhesion of one toner layer to another is determined by the amount of water on the surface of the toner particles. Enhanced by coating with aluminum oxide or zinc additives.

Liquid toners that provide developed images that rapidly self-fix to smooth surfaces at room temperature after removal of the carrier liquid are disclosed in US Pat. Nos. 4,480,022 and 4,50.
No. 7,377. This toner image is said to have higher adhesion to the substrate and is less prone to cracking. However, it is not disclosed to employ this in a multicolor image assembly.

A number of methods have been disclosed in patent publications aiming at high quality transfer of liquid toner images.

The use of silicones and silicone-containing polymers as mold release layers and leveling compounds as additives to impart mold release properties to the layers is well known.

In the field of electrophotography, a photoconductive layer topcoated with a silicone layer is described in US Pat. No. 3,185,7.
No. 77, No. 3,476,659, No. 3,607,
No. 258, No. 3,652,319, No. 3,716
, No. 360, No. 3,839,032, No. 3,84
No. 7,642, No. 3,851,964, No. 3,9
No. 39,085, No. 4,134,763, No. 4,
No. 216,283 and Japanese Patent Publication No. 81699/65
It is described in.

No. 3,652,319 discloses that the melting point is between 20 and 95° C. during use under repeated cycling conditions.
A readily liquefied solid, such as a silicone wax, is continuously applied to the photoconductive surface. The temperature is raised slightly at the time of wax application to allow it to melt and develop. Later in the cycle, the wax solidifies into a layer before exposure. The wax layer is reapplied and renewed every cycle. The thickness of the wax layer is in the range 50-1500 nm, with 200-800 nm appearing to be the optimum range.

No. 3,839,032 and its two divisions, US Pat. No. 3,851,96
No. 4 and No. 3,939,085 relate to liquid toner and the transfer of a toner image from a photoconductor to a receptor; It adheres more easily to receptor surfaces than to the body. Novel liquid toner compositions with such properties are disclosed. Low adhesion to the photoconductor can be achieved by a method that involves coating the surface with a layer of silicone. The example shows the composition of these layers, but not their thickness. Two dependent claims describe "reducing the affinity of the photoconductive layer for adhesive images". Introduction (column 2, 1-1 of the same U.S. patent)
Line 6) states that the invention solves the problem of incomplete transfer of liquid toner and loss of sharpness experienced in the art.

US Pat. No. 3,850,829 is a later application and refers to the results of US Pat. No. 3,839,032 as showing a loss of sharpness. This patent discloses that the addition of silicone to the adhesive liquid toner provides better results than a silicone layer on the photoconductor.

[0018] In US Pat. No. 3,847,642, 2
A ~25 micrometer (preferably about 5 micrometer) transfer film is applied to the photoconductor surface during the imaging cycle. The material must have a sharp, low melting point in order to melt by heating after toner application, transfer the toner onto the image-transferred portion of the layer, and solidify again. Among the materials, low melting point silicone waxes have been proposed.

[0019] In US Pat. No. 4,216,283, 1
In one embodiment (column 8, lines 63-68 and column 9, lines 1-30), Sil-OFF (registered trademark)
A thin release layer, which may be a type of material, is applied to the zinc oxide photoconductor layer (or the layer that would include an organic photoconductor) to ensure transfer of the liquid toner image. No suggestion is made as to the relationship between sill-off layer thickness and toner release. The principal aspects and claims relate to the use of adhesive layer (e.g., sill-off) coated intermediate transfer sheets in xerographic systems.

In addition to the patents dealing with silicone release layers, there are patents describing the use of silicone in other ways. U.S. Patent No. 3,476,659
No. 3,594,161, No. 3,851,96
No. 4, No. 3,935,154 and No. 4,078
, 927 all disclose the use of silicone as an additive to the photoconductor layer itself to provide release properties to both toner and ink (electrophotographic printing plates). These patents also disclose transfer intermediate sheets, belts, rolls and blankets for transferring toner images from a photoconductor to a receptor, and suggest treatment of the intermediate sheet with silicone. Examples of patents are U.S. Pat. Nos. 3,554,836 and 3,99.
No. 3,825, No. 4,007,041, No. 4.0
No. 66,802 and No. 4,259,422.

Receptor sheets for transferring deposited liquid toner images are well known in the art. For example, US Pat. No. 4,337,303 discloses a receptor layer that encapsulates toner from the image surface pressed against the receptor at elevated temperatures. The necessary physical properties of the receptor surface, in particular complex dynamic viscosity, are disclosed.

US Pat. No. 3,854,942 describes transparency in multicolor electrostatic copying. A transparent thermoplastic sheet (eg, polysulfone or polycarbonate) with strength and heat resistance that allows repeated projection is coated with a mixed polymer composition such as poly(vinyl chloride-vinyl acetate) copolymer and acrylic resin.

US Pat. No. 4,074,000 describes a drafting film with a pressure sensitive adhesive layer for use in electrostatic copiers. The film includes a substrate having a matte coating of a softenable thermoplastic on one side and a pressure sensitive adhesive on the other side. Any film material may be used as the substrate, including polyvinyl chloride, polyolefins and polyesters.

US Pat. No. 4,510,225 discloses an electrostatic imaging method for producing opaque prints. The opaque surface carries a thin, flexible transparent layer of polymer. Opaque substrates include plain or coated paper, metal, stone and stretchable or expandable media.

In the present invention, "electronic imaging" (el
The term electrography refers to an imaging surface,
Usually on dielectric materials, static charges (e.g. from a needle)
refers to a method of forming an image by applying a toner to form a latent image, and then developing the latent image with a suitable toner. The term refers to "electrophotography," in which light is applied to a conductive surface to create a latent image of electrostatic charge.
y). "Electrostatic printing"
Terms such as tatic printing are commonly used in the literature and are believed to encompass both electronic imaging and electrophotography.

[0026]

OBJECTS OF THE INVENTION The present invention provides a method for producing stable, high quality, large size, full color images, particularly images for outdoor display. A compatible substrate of polyvinyl chloride or polyurethane is applied with a receptor coating on at least one side to form a receptor sheet. In a preferred embodiment, an adhesive is present on the other side of the substrate. The substrate itself must have properties that allow it to mask or obscure the visual characteristics of the surface on which the imaged article will ultimately be placed. To achieve this,
The substrate of the imaging sheet has a haze of greater than 30% (
haze value). Preferably it has a haze of 50% or more, more preferably 75% or more (for example 100% is possible).

[0027] Cloudiness is determined by ASTM D1003-61 (
Reapproved in 1977) [Title: Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics (
StandardTest Method for H
aze and Luminous Transmit
tance of Transparent Plus
tics)]. This test can be performed using commercially available equipment, such as the Gardner
・Model US10 ・Hazemeter
) and Gardner PG5500 Digital Photometric Unit, Recording Spectrophotometer (Digital Photometric
Unit, Recording Spectrop
htometer).

Haze above 30% indicates a diffuse or translucent substrate and excludes a transparent substrate. The reason for this is that the haze is deflected from the incident light by forward scattering, and the sample (substrate)
This is because it reflects the proportion of transmitted light that passes through.

Haze is a more relevant and important indicator of optical properties in the practice of the present invention than specular transmission optical density and diffuse transmission optical density, which are at least 1.0 or at least 0.5, respectively. .

Electronic imaging printers suitable for the method of the invention (eg, Synergy ComputerGraphi)
(such as a printer manufactured by C.S.) may have multiple printer stations that sequentially contact the imaging surface and have the following properties: a) a needle or electrostatic imaging bar that forms an electrostatic image on the imaging sheet having a dielectric surface as it passes through the station; b) at a different speed than the advancement of the dielectric surface; an apparatus for developing liquid toner generally comprising an applicator roll rotating in a direction opposite to the surface; c) a vacuum squeegee for removing excess toner and a solvent present in the toner deposited along the image; Drying system for removal.

In particular, the mechanical units of a), b) and c) are in physical contact with the imaging surface and are therefore less effective than non-contact methods such as light-based methods applied to electrophotographic materials. It's bad for the surface. Such printers have previously been used in a manner that permanently affixes toner images to the surface of dielectric imaging sheets. This kind of printer is
It has been found to be particularly suitable for making large size prints, and imageable surface webs of 3 to 4 feet wide and of virtually unlimited length have been produced. This is in contrast to the substantial size limitations of printers produced by various electrophotographic methods.

[0032] When large size prints are required, especially for outdoor display, the properties of dielectric imaging sheets are often not suitable as the final image support. A typical paper substrate is
Lacking the water and UV resistance required for outdoor signs, more resistant substrates such as Plexiglass and 3M Panaflex (
Panaflex. registered trademark), Scotchcal manufactured by the company (
Scotchcal. (registered trademark) and polyester films, either due to their mechanical or electrical properties.
Images cannot be formed directly.

Transfer of the image from the imaging sheet to another receptor sheet allows the receptor sheet to be selected to have the properties required for the final print. However, in this case, in the heat/pressure transfer method, the imaging sheet must have a weaker adhesive force for any of the several toners than the toner's adhesive force to the receptor sheet. This is due to the conflicting requirements that the image toner deposited on the image sheet must adhere strongly enough to the receptor and to each other to prevent it from falling off or becoming damaged as it passes through the one-pass printer. Easy to achieve, except in some cases. In fact, it has proven difficult to obtain a combination of properties that satisfies these requirements. Not only must the adhesion generated during the printing of each toner onto the imaging surface be weak enough to permit release during subsequent transfer, but the adhesion of one toner to another must be
It must be large enough to prevent separation, and the cohesion and strength of the toner layer created during the printing process must be high enough to prevent damage.

In the present invention, a combination of dielectric imaging layer, at least two (generally four) toner and receptor layers is provided to obtain the properties required in the method, and a suitable combination of materials is provided. is selected and obtained. It has been found important to employ measurements that indicate that the properties are exactly those encountered in the method. Suitable measurement methods should also be described.

FIG. 1 is a schematic diagram of a type of print station useful in practicing the invention. The photoconductive intermediate receptor 1 comprises a paper substrate 2 which first has a dielectric layer 4 and then a release coating 6 on at least one surface. The surface of the intermediate receptor 1 passes through the station in the direction of 8 such that the coated surface of the paper first passes the stylus writing head 10. The head 10 deposits a charge 12 along the image leaving an uncharged surface area 14. After passing through the writing head 19, the intermediate receptor 1
passes through a toner station comprising a toner applicator 16 in contact with a liquid toner bath 18 in a container 20. Liquid toner 22 is applied to toner applicator 16
The toner is deposited along the image on the intermediate receptor 1 to form a toned region 24 and a toner-free region 26 . The toned area of the intermediate receptor 1 then passes through a vacuum squeegee 28 where excess toner is removed.

FIG. 2 shows the temperature at 110°C for five types of substances.
FIG. The five substances are elvasite (E
lvacite. 2044 (A), clear and white (TiO2 filled) 1:1 blend of vinyl chloride and acrylic resin 4:1 blend (B), PVC
and a 4:1 blend of TiO2-doped acrylic resin (C
), Elvacite 2010 (D) and transparent cast polyvinyl chloride resin (E).

A typical electronic imaging printer station for practicing the method of the present invention is shown in FIG. At each printer station, each image is typically formed in one of four different colors: black, cyan, magenta, and yellow. One of the printer stations is shown in FIG. 1, in which the web 1 moves in contact over a needle charging bar 10, past a liquid developer roll 16, past a vacuum squeegee 28, and finally through a vacuum dryer or It is dried by air flow from squeegee 28 (or blower, not shown). In order to completely develop the electrostatic latent image with toner in the shortest possible time, the developer roll 16 rotates at a speed faster than the web speed, generally facilitating the delivery of toner to the surface having the dielectric coating 4. For this reason, it has an uneven surface. The properties of the toner are such that it adheres to the imaging surface and to the underlying toner sufficiently to ensure that the image is not removed again during development of the toner and subsequent development of other toners. It must be of such a nature that it must be strong. Development with a textured roll in contact with the image is in contrast to electrophoretic development, induced by an applied electric field, commonly used in electrophotographic systems, where there are no mechanical members in contact with the image.

Such printers are known in the art and can be purchased, for example, from Synergy Computer Graphics. The final image is displayed on the dielectric surface treated imaging material.

In the present invention, the process concludes with the transfer of the completed toner image from the dielectric surface to the receptor surface for the reasons discussed above. The imaging surface carrying the assembled toner image is pressed against the receptor surface and heat is briefly applied. This can be done by many methods known in the art, such as by passing the sheets together through heated nip rolls or by placing the sheets on a heated platen in a vacuum frame. . The latter method is preferred according to the invention.

If the final image on the receptor sheet is to be of high quality and color reproduction, the transfer must be perfect and free from distortion of the various color images. Therefore, under transfer process conditions, the toner image must be easily released from the imaging surface and adhere to the receptor surface.

In the previously described technology, the release layer used in the toner transfer process is common to that of electrophotographic systems. In the present invention, however, it is surprising that a release layer can be used without the deposited image toner being even partially peeled off even under the stress of continuous development using a textured roll. In fact, it has been found that severe image damage occurs in some cases and defective damage occurs in many cases, depending on the particular combination of toner, release layer and receptor surface. Alternatively, it has been found that the toner combinations currently used in printers such as Synergy's printers are not suitable for the present invention.

The disclosure herein teaches how to properly select the release surface, toner, and especially the receptor surface so that the image is undamaged and transfers completely.

It has been found that the surface energy values of the components used in each layer can be measured and the required adhesion/adhesion properties determined by these values.

That is, a) the dielectric imaging surface is 14-2
It must have a surface energy of 0 ergs/cm2 and its polar content must exceed 5%. b) The work of adhesion between any two overlapping toners on the imaging surface must be greater than the work of adhesion between the imaging surface and the toner deposited thereon. This does not apply to the last developed toner, since no other toner is deposited on top of the last developed toner. c) Any deposited toner at 50 ergs/cm2
It does not have a surface energy exceeding . d) The receptor surface should have a greater surface energy than the imaging surface.

The difference in b) and d) is at least 5
Preferably it is at least 10 ergs/cm2, more preferably at least 10 ergs/cm2. The polar component in the surface energy value contributes significantly to the adhesion level. The limitation on the polar component in the imaging surface in a) is necessary because it is a release surface and stems from this property.

It has also been found that even if the surface energy requirements are met, image damage can occur if the toner deposited in a sequential process is too soft or not mechanically strong. This requirement can be effectively determined by the scratch test defined later. It has been found that toner scratch strength is a valid criterion only when it is related to the process' own conditions. This test should be performed on toner samples immediately after toner deposition, preferably within a time period of no more than 8 minutes, and more preferably no more than 2 minutes, from the onset of drying following deposition. It has been found that toner samples left for several hours after deposition give misleading values. To obtain good performance in the present invention, the toner scratch strength, as indicated by surface compaction or cracking, must be 8.5% from the start of drying.
Must be at least 40 g when measured over a period not exceeding minutes.

Similarly, meeting the surface energy requirements of the receptor surface alone does not ensure good transfer. In addition, the Tg of the surface varies from 10°C to the temperature employed in the transfer process (high temperature, i.e. 30°C or higher, usually 50-15°C).
0°C, preferably about 90-130°C, e.g. 110°C)
The complex dynamic viscosity of the surface material should be about 2 x 105 poise or less at the transfer temperature. These added requirements provide better compatibility with the imaging surface at elevated temperatures during adhesion and transfer.

[0048] Here, the materials of each element used in the method will be explained in detail.

Imaging Sheet The imaging sheet consists of a flexible substrate with a dielectric layer on one surface. The substrate must either be conductive itself or have a conductive layer on the surface below the dielectric layer.

[0050] The substrate can be selected from a wide variety of materials including paper, plastic, and the like. If another conductive layer is required, it may be a thin metal such as aluminum or a material such as tin oxide, which is well known to be stable at room temperature and at high temperatures during transfer.

Dielectric layers on substrates used in electronic imaging prints are also well known in the art. for example,
Neblett's Handbo of Photography and Reprography by C.B. Neblette
OK of Photography and Rep
(John Strang)
Strang) 7th edition, (van Nostrand)
Van Nostrand Reinh
(1977). Such layers include polyvinyl acetate, polyvinyl chloride,
Generally includes polymers selected from polyvinyl butyral and polymethyl methacrylate. Other components can be selected from waxes, polyethylene, alkyd resins, nitrocellulose, ethylcellulose, cellulose acetate, shellac, epoxy resins, styrene/butadiene copolymers, chlorinated rubbers and polyacrylates. Performance criteria are given in the Neblett article cited above. Such a layer is also described in U.S. Pat.
No. 75,859, U.S. Patent No. 3,920,880,
No. 4,201,701 and No. 4,208,46
It is also mentioned in number 7. The layer thickness ranges from 1 to 20 micrometers, preferably from 5 to 15 micrometers. The surface of such a dielectric layer is advantageously rough to ensure charge transfer during passage under the needle bar. Surface roughness can be obtained by including particles in the layer that are large enough to impart irregularities to the layer. A suitable particle diameter is 1 to 5 micrometers. Such properties of dielectric layers are known in the art (e.g., U.S. Pat. No. 3,920).
, No. 880 and No. 4,201,701).

The required surface energy properties of the imaging sheet can be obtained by applying a release layer to the free surface of the dielectric layer or by modifying the dielectric material. Release layers commonly used in pressure sensitive tape materials, such as polyurethane, have been found to be too adhesive, while known release materials such as dimethylsiloxane are too adhesive. Among the available materials, polymers containing a controlled and low number of dimethylsiloxane units have been found to perform particularly well.

A release coating suitable for the present invention should have the following properties: 1. Do not affect the electronic imaging properties of the dielectric medium. 2. The transfer efficiency at the final stage of the process is high, preferably 95-100%. It is preferred that no appreciable amount of the release coating be transferred with the toner, as this may adversely affect any protective coating that may be applied to the transferred image. 3. The deposited toner itself must anchor to the release coating in order to survive sufficiently for subsequent processing. 4. No part of the release coating must dissolve in the hydrocarbon liquid carrier of the liquid toner and must not be detrimental to the toner (the release coating must not dissolve easily from the film into the liquid carrier, especially in a time of less than 2 minutes). (Do not dissolve or disperse.)

Image release layers tested included Dow Corning SIL-OFF 7610 (referred to as ``Premium Release'') and SIL-OFF 7610-based SIL-OFF 7610 (referred to as "Premium Release").
Controlled release.” The free silicone in the control release composition leached into the liquid toner and interfered with toner deposition. On the other hand, the premium release composition did not leach out, but caused significant abrasion damage to the toner image during processing.

A suitable release layer should therefore have controlled release properties imparted by the inclusion of a minor component, such as silicone, which is tightly bound to the polymer that is insoluble in the liquid carrier of the toner. It has to take hold. The presence of mobile silicone on the surface of the release layer has been found to be unacceptable as it makes the toner image more susceptible to damage during processing. The non-silicone portion of the release layer material needs to have a high softening point. An example of such a polymer is a polydimethylsiloxane (PDMS) content of 1 to 10% by weight.
is a silicone/urea block polymer. This copolymer is described in the reference examples below. This polymer is prepared in isopropanol and further diluted with isopropanol to 3% solids for coating dielectric surfaces. If the proportion of PDMS exceeds 20%, the density of the developed image decreases and the improvement in transfer efficiency is negated, which is not very preferable. However, if the process conditions are less demanding, the silicone content can be higher, even up to 65% or more.

Other controlled release compositions can be obtained using monomers capable of forming condensation products with silicone units via the terminal amine or hydroxy groups of the silicone units, where the monomer units are Polymerized. Examples of such compositions include urethanes, epoxies and acrylics and silicone moieties such as PDMS (
For example, in combination with PDMS).

A dielectric layer with built-in release properties has the additional advantage of eliminating extra coating steps and eliminating the electrical effects of separate release layer thickness. Known useful self-releasing dielectric polymers are described in the Reference Examples below. Such polymers are copolymers of methyl methacrylate (MMA) and PDMS or terpolymers of MMA, polystyrene and PDMS. Useful proportions of PDMS are 10-30% by weight of total polymer, with a range of 15-30% yielding transfer efficiencies of 90% or higher, although higher proportions reduce the optical density of the deposited toner. tends to decrease. Optimum values for these polymers are in the range of 10-20%.

Physical Requirements for Alternative Release Layers Apart from specific adhesion, the functional surface of the imaging sheet should have a controlled roughness to promote such charging to the dielectric layer itself. There must be. When release properties are imparted by another layer coated on the dielectric layer, the release layer is
phy) to provide a predetermined roughness.

If a separate releasable layer is used, its thickness must be carefully controlled. Too thin and the transfer will be incomplete, while too thick and the electrostatic image receptivity of the surface can be adversely affected. A suitable range is about 0.05-2
micrometer, and the preferred thickness range is 0.08
~03 micrometers. Between the properties of an uncoated dielectric surface and the properties of the same dielectric surface after coating with a releasable layer according to the present invention, no significant change in surface roughness is observed before and after coating.

The following examples demonstrate the coating weight (and therefore dry thickness) of the releasable layer on the imaging sheet, the surface charge deposited by the charging needle (measured as surface potential), the developed image density, and The relationship between image transfer efficiency is explained.

Syloff 23 (registered trademark)
(“Premium Release”) A solution of silicone in heptane was coated with 2089 dielectric paper (James River Graphics Corporation).
er Graphics Corp. ) on top of 2
The coating was applied so that only 2" wide paper was coated. The purpose of partial coating was to allow images to be formed simultaneously on the coated and uncoated areas. Different solution concentrations and Wire-wrapped coating rods (Meyer rods) of different sizes were used to form coatings of different thicknesses. In this experiment, the coating weight of the releasable layer was determined by the wetting layer obtained from Meyer bars of various sizes. It was calculated from the solution concentration and the size of the coating bar using the thickness described in the literature.That is, as the solution concentration increases or the bar number (#) increases, the thickness of the releasable layer increases.

The coated imaging sheet is made of Benson (B
Enson) 9322 printer. The surface potential on the imaging sheet was measured by an electrostatic probe mounted between the charging station and the liquid development station of the printer, and Benson T3 black liquid toner was used for image development.

After measuring the background and optical density (OD) of the image area of the developed imaging sheet, the toner image was transferred to a commercially available thermoplastic coated receptor paper (Schoeller 67-33-1). It has a surface coating of an ethylene/acrylic acid polymer sold as Primacor EAA. ] by heat and pressure. The background and residual optical density remaining in the image area were measured after transfer. Image transfer efficiency was calculated using the following formula:
Transfer efficiency (%) = [1-(ODr-ODBr)/(OD
−ODB)]×100 [where OD is the image optical density on the image sheet before transfer, ODr is the residual optical density in the image area after transferring the image, and ODB is the residual optical density in the background area before transfer. Optical density, and ODBr is the residual optical density in the background area after transfer. ]

Table 1 shows that increasing the thickness of the release layer on the surface of the imaging sheet gradually decreases the developed optical density. Table 2 shows the effect of the releasable layer on surface potential and image transfer efficiency. Increasing the thickness of the release layer increases image transfer efficiency, but reduces surface potential and therefore image density.

[0065]

[Table 1]

[0066]

[Table 2]

Toner The liquid toner used in the present invention can be selected from types of toner conceptually well known in the art. Toners consist of a stable dispersion of toner particles in an insulating liquid carrier, typically a hydrocarbon. Toner particles carry an electrical charge and include a polymer or resin and a colored pigment. Preferably, toner particles should satisfy the following general requirements in addition to the interplanar surface energy and scratch strength requirements described above. Such general requirements are described in U.S. Patent Application No. 279,424.
No. (filed December 2, 1988).

The requirements are: a) the ratio between the conductivity of the carrier liquid present in the liquid toner and the conductivity of the liquid toner itself is less than or equal to 0.6, preferably less than or equal to 0.4, most preferably less than or equal to 0.4; Must be 0.3 or less,
b) The zeta potential of the toner particles is in a narrow range of +60
It is centered between ~+200mV.

[0069] The liquid toner preferably also satisfies the following requirements: c) The deposited toner particles have a temperature of -20°C below 100°C.
Tg above, more preferably 70°C or below and -10°C or above
d) having a substantially monodisperse toner particle size with an average diameter of 0.1 to 0.7 microns; e) a solids concentration in the liquid toner of 0.5 to 3.0% by weight;
, preferably 1.0 to 2.0% by weight, and the electrical conductivity is in the range of 0.1 x 10 -11 to 20 x 10 -11 mho/cm.

The insulating carrier liquid in such liquid toners has been found to have additional importance in relation to the strength of the deposited toner layer during the process, as predicted from scratch strength tests. Ta. A wide variety of hydrocarbon-based carrier liquids with a range of boiling points [e.g.
r. registered trademark) series]. Isopar C, E, G, H,
K, L, M and V are respectively 98°C, 116°C, 1
It has boiling points of 56°C, 174°C, 177°C, 188°C, 206°C and 255°C. Mixtures of different components are often used in liquid toner compositions. The presence of high boiling components results in low strength, indicating low scratch strength. Particularly high proportions of Isopar L, as opposed to Isopar G, may be detrimental.

Toners are usually prepared as concentrates to reduce storage space and transportation costs. When the toner is used in a printer, the concentrate is diluted with another carrier liquid to form what is called a working strength liquid toner.

The toners may be superimposed on the surface of the image sheet in any order, but for color reasons, keeping in mind that transfer is performed in the present invention, the toners are applied in the order of black, cyan, magenta, and yellow. It is preferable to form the image with Previously used printers (including Synergy printers) put black toner on first, but because they didn't use transfer, the black was at the bottom of the assembled image. Because a lighter and generally more scattering colored toner forms on top of the black, the resulting image color appearance is lighter. In the image of the present invention, black is the top toner, giving depth to the color.

Preparation of toner 1. Preparation of Stabilizer Containing Chelating Groups and Grafting Sites In a 500 ml three-necked round bottom flask equipped with a stirrer, thermometer and condenser connected to a nitrogen source, lauryl methacrylate (LMA) (69 g), 5-methacryloxymethyl -8-Hydroxyquinoline (HQ) (4.5g
), 2-hydroxyethyl methacrylate (HEMA)
(1.5 g) and Isopar H (175 g) was added. The mixture was flushed with nitrogen and heated at 70° C. with stirring until the quinoline monomer was dissolved.

2,2'-Azobisisobutyronitrile (AIBN) initiator (1.5 g) was added to the solution and the mixture was polymerized at 70° C. for about 20 hours. The conversion rate was quantitative.

After heating at 90° C. for 1 hour to decompose residual AIBN, the mixture was cooled to room temperature, the nitrogen source was replaced with a drying tube, and 2-isocyanatoethyl methacrylate (IEM
) and dibutyltin dilaurate were added to the flask in equimolar amounts, ie 1.8 g and 0.36 g, respectively. The mixture was then stirred at room temperature for 24-48 hours. The conversion rate is quantitative and the resulting stabilizer solution can be used for the preparation of organosols.

The product is a copolymer of LMA, HQ and HEMA and contains IEM side chains. This is called LMA/HQ/HEMA-IEM.

2. Preparation of organosol containing polyvinyltoluene core

Case A Above 1. In a reaction flask similar to
/HEMA-IEM stabilizer (110g), vinyltoluene (33g), Isopar H (457g) and AI
BN (0.66 g) was added and the resulting mixture was polymerized at 70° C. for 21 hours. The conversion rate was 56%. Residual monomer was removed under reduced pressure and the product was ready for use as a bander in liquid toner compositions.

Case B Above 1. In the same apparatus, add stabilizer (LMA/HQ/HEMA-IEM=92.8/2.
9/2.0-2.3. solid content 30%) (110g), vinyltoluene (VT) (33g), Isopar H (45g), vinyltoluene (VT) (33g),
7g) and t-butyl peroxide (0.5g) was added. The resulting solution was flushed with nitrogen for 10 minutes and polymerized at 130° C. for 8.5 hours. Conversion yield is 9
5.3%, and the dispersion contained 10.74% solids.

The product is a poly(vinyltoluene) containing long grafts of LMA, HQ and HEMA copolymers.
It was an organosol. This is LMA/HQ/HE
It is called MA-IEM//VT.

3. Preparation of black toner for use in silicone-coated dielectric paper A toner concentrate with a solid content of 15% was prepared using BK
-8200 carbon black pigment and LMA/
HQ/HEMA-IEM//VT (Feed composition: 45.9
0/1.95/0.98-1.17//50.0) to 1
:1 in Isopar H and the dispersion was bead milled to reduce the average particle size to 367+/-114 nm. Zirconium neodecanoate charging agent was added in an amount of 0.238% based on the dispersion.

The concentrate was diluted with Isopar G and further organosol and zirconium neodecanoate were added to prepare a practical strength toner with the following properties:

0083
] Organosol/BK-8200 Weight ratio: 2.0 Solid content concentration: 2.0% Zirconium neodecanoate: 0.147
~0.2% Specific conductivity: 12.4 x 10-11 ~ 15.9
×-11/ohm. cm

Synergy Color Writer
Good image adhesion to silicone-coated dielectric paper was obtained using a Gy Colorwriter 400 printer. The reflected optical density (ROD) of the image is 1.1
4 or more.

4. Black liquid toner LMA/HQ/HEMA-IEM for urea/silicone coated dielectric paper
//VT (Feed composition: 44.92/2.93/0.98
-1.17//50) Organosol and Regal
al) A toner concentrate was prepared by dispersing 300R carbon black pigment and bead milled to an average particle size of 306 nm. The weight ratio of organosol to carbon black was 1.0, and the solids concentration was 15%.

A 1.08% working strength toner was prepared by diluting the concentrate with Isopar G and adding zirconium neodecanoate and more organosol to give an organosol to pigment ratio of 2.0. The concentration of zirconium neodecanoate in the toner was 0.13%.

[0087] The toner is 7.98×10-11/ohm
．． Images were formed on urea/silicone coated dielectric paper with a specific conductivity of cm and ROD 1.41.

5. Preparation of Cyan Liquid Toner for Urea/Silicone Coated Dielectric Paper A 15% solids toner concentrate was prepared using LMA/HQ/HEMA-IEM//VT (feed composition: 45.85/0.97/1.45- 1.74//5
0.0) Organosol and Sunf
ast) 248-3750 cyan pigment was prepared by bead milling 1:1 in Isopar H.

The concentrate was diluted with Isopar G and zirconium neodecanoate and further organosol were added to prepare a 1% solids practical strength toner with the following properties:

Organosol/pigment weight ratio: 2.0 Zirconium neodecanoate: 0.028% Particle size: 337+/-9
1 nm Specific conductivity: 7.02×10-11/ohm. cm image R
OD: 1.18

6. Preparation of Magenta Liquid Toner for Urea/Silicone Coated Dielectric Paper A 15% solids toner concentrate was prepared using Monastral 796.
D magenta pigment LMA/HQ/HEMA-I
EM//VT (feed composition: 45.85/0.97/1.
45-1.74//50.0) It was prepared by dispersing it in an organosol using a bead mill.

The concentrate was diluted with Isopar G and zirconium neodecanoate and further organosol were added to prepare a 1.15% solids practical strength toner with the following properties:

Organosol/pigment weight ratio: 2.0 Particle size: 4
56+/-158nm Specific conductivity: 3.90×10-11/ohm. cm image R
OD: 1.13

7. Preparation of yellow liquid toner for use on urea/silicone coated dielectric paper 6. above. A toner concentrate was prepared using the following pigments and organosols: Pigment: Sun's 274-
1744AAOT yellow organosol: LMA/HQ
/HEMA-IEM//VT (supply composition: 45.85/
0.97/1.45-1.74//50.0).

The concentrate was diluted with Isopar G and zirconium neodecanoate and further organosol were added to prepare a 1.0% solids practical strength toner with the following properties:

Organosol/pigment weight ratio: 2.0 Particle size: 3
88+/-87nm Zirconium neodecanoate: 0.014% Specific conductivity: 1
．． 31×10-11/ohm. cm image ROD: 1.0
9

Black, cyan, magenta and yellow toners 4-7 above were used in a Synergy Colorwriter 400 printer to print release coated dielectric paper (
Patches of all single colors and overlapping color combinations were printed onto the silicone/urea composition release layer. High quality images were obtained. That is, there were no scratch marks and the toner exhibited good overprint ability to create composite colors. The image is an improved version of Scotch Cal.
chcal. (Registered Trademark) Image Receptor (Scotchcal polyvinyl chloride top layer coated with a 30 micrometer thick butyl methacrylate top coat)
After thermal transfer, no residue remained on the release surface of the imaging sheet.

Receptor Sheets These sheets have a transmission optical density greater than 1.0 and generally consist of a substrate consisting of a polyvinyl chloride or polyurethane film with special requirements on properties, and a Tg of 10 to 105° C. as indicated above. It comprises a coating layer on one surface of the substrate which provides the necessary surface energy as well as the value. This layer must have a suitable complex dynamic viscosity to ensure conformance to the surface of the imaging sheet. The surface coating of the receptor sheet can be selected from a number of thermoplastic polymers that meet the requirements described above.

Examples of such substances are acrylates,
In particular methacrylates, such as methyl acrylate, butyl methacrylate, copolymers of methyl methacrylate with other acrylates, low molecular weight ethyl methacrylate, isobutyl methacrylate, vinyl acetate/
vinyl chloride copolymers, and aliphatic polyesters.

Examples of substances that do not provide satisfactory transferability are:
High molecular weight polymethyl methacrylate. It is known that the complex viscosity of a polymer is a function of its molecular weight [Polymer Rheology, by L.E. Nielsen].
, Marcel Dekker
) Publishing (1977)]. Low molecular weight, e.g. 40,0
At a molecular weight of 0.00, the complex viscosity is directly proportional to molecular weight. At high molecular weights, viscosity is an exponential function of molecular weight with an index of 3.4. Therefore, high molecular weight polymers may not be suitable for receptor coating of the present invention.

The receptor coatings of the present invention need not have a matte finish like many prior art imaging materials. Relatively smooth, non-matte surfaces are preferred. In order not to have a matte finish, particles with an average diameter of at least 10% of the layer thickness should be included in an amount of less than 0.25% by weight of the total coating layer. More preferably,
Less than 0.1% by weight of the receptor coating layer is present as particles with an average diameter greater than 10% of the coating layer thickness. Most preferably, the amount of particles with an average diameter of less than 90% of the layer thickness is less than 0.1% by weight. Certain particles, such as pigments, are present in the layer, but the matte surface caused by the pigments is undesirable.

[0102] The base material of the receptor sheet is 30 to 500
Made of flexible polyvinyl chloride or polyurethane with micrometer thickness. The receptor coating is 1
It has a Tg of 0-105°C, a complex dynamic viscosity of less than 2.0 x 105 poise and a thickness of 3-50 micrometers. The receptor sheet has the haze described above. Preferably, the flexible substrate of the sheet has a
It has a specular optical density of . This optical density is preferably achieved by adding pigments and/or air bubbles to the sheet. More preferably, the optical density coloration is white or ivory, but other colorations (especially tinted) are preferred.
white) can also be used.

Rheological evaluation of receptor substances is performed using a rheometric mechanical spectrometer (Rhe
ometrics Mechanical Spectr
(meter) model RMS-605. Calibration of this instrument is described in the Rheometrics Mechanical Spectrometer Operations Manual (
Rheometrics Mechanical Sp
electrometer operations man
ual) [Rheometrics Incorporated (
Rheometrics Inc. ]0381 No. 6-1
Polydimethylsiloxane (GE#
SE30). Complex viscosity is at a temperature of 110℃
, a vibration frequency of 10 radians/second, a strain of 2%, and a vibrating parallel plate measurement. The film samples used were either obtained from commercial sources (e.g. 3M standard cast white vinyl) or by casting a solution, air drying, and
It was obtained by drying in a vacuum oven for 3 to 5 days at a temperature approximately equal to or lower than g. Samples for measuring these receptor substances were placed between parallel plates with serrations of 25 mm in diameter so that the gap width was 0.5 to about 2.0 mm.
It was prepared to consist of a laminated film compressed at 10°C.

The image transfer efficiency of various receptor sheets was determined by performing the transfer process at 110° C. and 1 atm using a vacuum drawing device.
This was determined by measuring the amount of toner remaining on the imaging sheet after running for 1 minute. The "CIELAB Color Difference" (usually denoted ΔE) is the difference between image transfer and toner that remains on the image sheet after transfer, making the color appear different from the background, i.e., areas that do not contain any image. Give a good rating for efficiency. Lower values indicate better transfer. (For ΔE, see Hunt (R.
W. G. Hunt), Measuring Color (Mea)
suring Color) [John Wiley & Sons (
New York) Publishing (1987). ) Imaging sheets and corresponding receptor sheets were visually evaluated to determine acceptability and grading.

[0105] Color difference ΔE is determined by "Color Eye" manufactured by Macbeth.
Eye) A spectrophotometer was used to measure the area on the surface of the imaging sheet to which the toner image had already been transferred. The measurement aperture was 7 mm x 7 mm. For these measurements, the area where the black patch was transferred was used.

Table 3 shows the complex dynamic viscosity and shear modulus of various receptor coating materials and relates these values to the transfer properties in the present invention measured on the ΔE scale.

[0107]

[Table 3]

Description of the substance used: Elvacite (El
vacite. 2044 (Dupont): polybutyl methacrylate (Tg=15°C). Elvacite 2010 (DuPont): polymethyl methacrylate (Tg = 98°C). Elvacite 2041 (DuPont): polymethyl methacrylate (Tg = 95°C). *: Weight average molecular weight published by DuPont 323
,000, calculated according to "Polymer Rheology" by Nielsen (cited above). Acryloid
loid. (registered trademark) A21 (Rohm & Haas): polymethyl methacrylate (Tg=105°C). **: This value is questionable and probably too low since there were air bubbles in the sample used to measure the complex dynamic viscosity. Clear cast vinyl (polyvinyl chloride) (3M). 8951 (3M): 4:1 clear blend of PVC and acrylic resin. 8942 (3M):
A 4:1 white blend of PVC and acrylic resin with added TiO2 pigments. Standard cast white vinyl (manufactured by 3M).

When correlating the ΔE range with visual evaluation, a value of 4 was found to be associated with a somewhat unacceptable transferred image. Therefore, in the present invention, the ΔE value must be less than 4. The graph in FIG. 2 was drawn from the values in Table 3. This graph is a plot of complex dynamic viscosity versus ΔE value. A quadratic regression line can be drawn through the data points, as shown in FIG. Using a visually determined upper limit of ΔE of 4, it is shown in Figure 2 that the complex dynamic viscosity must be less than about 2.5 x 105 poise to achieve good transfer with a vacuum draw providing about 1 atm. It can be seen from Preferably, this value is less than about 2.0 x 105 poise. These values are at 110°C, and the relevant transfers were performed at that temperature. It is believed that similar complex dynamic viscosity limits apply for other transfer temperatures as long as the values are obtained at the same temperature. According to our experiments, the higher the transfer temperature, the less acceptable the receptor surface on the boundary gives a better result. This is to be expected from publications showing that complex dynamic viscosity gradually decreases with increasing temperature (see Nielsen, supra).

Preferably, the substrate should conform to the microscopic roughness of the imaging surface. Materials such as PVC and polyurethane are well suited to imaging surfaces, but
Materials such as polycarbonate are not compatible and therefore do not transfer well toner images. Other widely used materials that do not serve as preferred substrates in this invention are acrylics, polyolefins, polyethylene/acrylic acid copolymers, and polyvinyl acetals. Commercially available composite materials such as Scotchcal and Panaflex are also suitable substrates. On substrates such as PVC,
The thickness of the coating layer may be about 3 micrometers, but the thickness of the coating layer may be about 3 micrometers.
Te. On materials such as TM), a 30 micrometer thick coating layer may be required.

[0111] The polyvinyl chloride and polyurethane substrates are homopolymer compositions or copolymer compositions (
(including terpolymers and tetrapolymers). Vinyl chloride copolymers with vinyl acetate, vinylidene chloride, styrene, butadiene, and the like can be readily used in the practice of this invention. Graft or block copolymers of vinyl chloride and urethane can also be used. Preferably the substrate contains at least 50% by weight of units derived from vinyl chloride.

Transfer Conditions A preferred device for performing transfer in the present invention is a vacuum drawing frame. When such equipment is used in the present invention, typical pressures and temperatures are 1 atm and 11
It is 0°C. Although the pressure is defined by standard atmospheric pressure, increasing the atmospheric pressure locally means that higher transfer pressures occur in the vacuum device. By selecting the receptor layer according to the requirements mentioned above, at least 90
Temperatures ranging from 130°C to 130°C can be employed. This method is preferred because it does not cause image distortion during transfer due to flow of the receptor sheet coating or clamping of the receptor substrate. The nip roll transfer method applies higher pressures and is therefore much more prone to distortion, but it also allows for easier and more complete transfer and less stringent specifications as to the nature of the receptor coating. In the present invention,
The vacuum drawing method is preferred. This is because there is no distortion in the final image. However, the properties of the receptor must be carefully controlled.

Protective Coating A protective coating for a transferred image is a coating that protects the image from physical damage and/or damage caused by actinic radiation.
This will be done as necessary. The composition of protective coatings is well known in the art and typically consists of a transparent film-forming polymer dissolved or suspended in a volatile solvent. UV absorbers can also be added to the coating fluid. Lamination of protective coatings to image coatings is also well known in the art and can be employed in the present invention.

Surface Energy Measurement a) Sample Preparation On a release-coated clean glass plate (24 mm x 60 mm x 1 mm),
Release coated films were formed by dip coating a solution of the test substance (3-5%). In some cases,
The coating was dried at 40° C. at relatively low relative humidity (40%) to yield a transparent film.

The solution was applied onto the dielectric paper using a coating rod (#0 Mayer bar) to form a release coating. Wilhelmy method [Wilhelmy, Ann. Ph.
The sample plate required for the measurement of contact angle according to J. Ysik), Vol. 119, (1863)] was bonded to both sides of a 24 mm wide polyester film support in such a way that only the release coated surface was in contact with the test liquid after immersion. It was created by

Receptor Surfaces Receptor material test plates were prepared by dip coating clean microscope slides. However, if only an adhesive-backed film of the substance is used, the test plate can be assembled by peeling the protective liner from the adhesive and joining two 24 mm wide strips together (back side) so that only the desired surface is exposed to the test liquid. Back) It was possible to create by combining.

Liquid Toner Material A continuous, smooth liquid toner film was prepared by electroplating onto an anodized silicated aluminum plate from a dispersion of toner particles in an Isopar G carrier liquid. Particle deposition was carried out using an aluminum plate potential of -150V and a plating time of 10 to 60 seconds depending on the characteristics of the particular toner dispersion. After electroplating, the plates were rinsed in clear Isopar and dried in air at room temperature.

b) Measurement of contact angle Cahn-322 Model Dynamic Contact Angle Analyzer (Cahn-322 Model Dynamic Contact Angle Analyzer)
Dynamic Contact Angle
The advancing and receding contact angles of the wetting liquid on the Wilhelmy plate surface were measured using a probe (Alyzer). Advancing contact angles were measured at 3 to 5 different locations on the Wilhelmy plate surface. Measured values are often within ±1%, rarely ±
It was reproducible with an error within 2%. At least four liquids with a wide range of different γd and γp were used as wetting fluids for each test surface.

c) Calculation of surface energy from contact angle data From the advancing contact angle θ of the test liquid measured using the known γ1d and γ1p on the solid surface, the surface energy was calculated using the following formula [Erbil (H . Y. Erbil) and R. A. Meric, Colloids & Surfa
ces), Vol. 33 (1988) 85-97, and the original documents cited therein):

[0120]

[Math 1] In the formula, i represents a liquid, j represents a solid,

[0121]

[Equation 2] where i=1, 2, . ．． ．． ．． n (n is the number of test liquids in a set with literature surface energies covering the range of polarities).

The values of the surface tension γ (overall) and the dispersion and polar components γd and γp of the surface tension were determined by Koelble (D.
H. Kaelble et al. [Kelble, Dines (P.J.
．． Dynes) and L. Maus, Journal of Adhesion (J. Adhesion),
6 (1974) 239-258] (Table 1
reference). Values for ethylene glycol were determined by Wilhelmy balance using test liquids with known properties.

d) Work of Adhesion The thermodynamic work of adhesion (Wa) between the release layer and the toner film was calculated by the following formula:

[0124]

[Equation 3] Here, γs=surface energy of the release layer, γt=surface energy of the toner film.

To calculate the polar component Wa (polarity) of the work of adhesion, the following formula was used:

[0126]

[Math 4]

e) Interfacial tension between polymer layers Polymer layer 1
The interfacial tension between
Equation) [S. Ross and I.D. Morrison, “Colloidal
Systems and Interfaces” (Coll
Ooidal Systems and Interfa
ces) (1988), John Wiley & Sons]:

##EQU00005## where the .sigma. value represents the surface tension and W12 represents the work of adhesion between surfaces 1 and 2.

f) Spreading coefficient [Gilfalco-Good (G
irifalco-Good)]Φ

[0129]

[Math 6] In the formula, for complete extension, Φ=1, For incomplete extension, Φ<1. Release coefficient = 1/Φ The ease of layer release is proportional to 1/Φ.

Surface energy measurements were performed on a series of substances that are candidates for use in the present invention. Values for the silicone/urea release layer described above are shown in Table 4, and values for other selected candidates are shown in Table 5.

[0131]

[Table 4]

[0132]

[Table 5]

The work of adhesion of the toner to the release surface can be calculated from the surface energy according to the formula given in the explanation [d) Work of adhesion] above. This value Wa is a measure of the relative adhesion/adhesion of two surfaces of overlapping toner on the surfaces. Tables 6 and 7 show the values for toner/release layer and toner/toner, respectively. Table 8 shows the values of Wa between the toner layer and the uncoated dielectric paper (type 6 paper in Table 5). These are also higher than the values for added release layer in Table 6, with a P of 1%.
Much higher than the value for DMS. On the other hand, the values in Table 8 are very similar to the toner-toner adhesion values understood from Table 7.

[0134]

[Table 6]

[0135]

[Table 7]

[0136]

[Table 8]

Meaning of Surface Energy Measurement The effects of good or bad properties on the surface of an imaging sheet can be
A number of image toner deposition conditions can be affected depending on the type and number of toners in the species. 10% PDMS
With the release coating, the three toners are released together, but with the 0% PDMS release coating, the M-C
Separates at the interface. In the sixth image, separation occurs at the Y-C interface, and in the second image, separation occurs at the C-B interface. At all other imaging conditions, all of the toner is transferred because it is separated at the interface with the dielectric coating surface. With the proper release layer, no separation will occur within the toner assembly under any imaging conditions.
It occurs only at the interface with the release surface.

However, from this analysis, it is possible to make the cohesive strength of the toner layer itself such that separation does not occur within the toner layer. The cohesive strength is obtained by doubling the surface energy of the toner layer (the surface energies of the two surfaces shown above, keeping in mind that in the bulk of a single material the two sets of surface energy values are the same). (see relationship of work of adhesion to polar and dispersive components). Similar to the work of adhesion, this cohesive strength must be greater than the work of adhesion of the bottom toner to the dielectric (release) surface.

[0139] For the imaging method to be successful, a final criterion must be demonstrated. While carrying out the method, the deposited toner must be tough enough to withstand the wear caused by the needle bar and developer roll. The scratch test described in the next section provides a means of determining whether the abrasion strength of the toner is sufficient for this purpose.

Scratch Test The following describes the procedure for liquid toner films.

a) Sample Preparation A 35 mm wide by 95 mm long strip of 76 micrometer thick polyester film with an aluminum deposited layer on one surface was coated with a liquid toner dispersion (1-2% solids). The filled cell is placed with the aluminum surface 5 mm away from the counter electrode. After connecting the aluminum layer to the cathode of a DC power source and connecting the counter electrode to the anode, a voltage of 150 volts was applied for 20 seconds to electrodeposit toner particles onto the aluminum layer.

After toner deposition, the sample was
Soak, rinse and air dry for 5-7 minutes to remove excess liquid from the toner layer.

[0143] The transfer medium carrying the first color image has just arrived at the second color imaging station where the first image is frictionally contacted with the charging head, rotating development electrode and vacuum port within the printer. In order to test the properties of the toner layer under almost the same conditions as when
Do this immediately after the liquid film has evaporated. b) Scratch Test Procedure The scratch test consists of pulling a needle across the surface of the toner layer while applying a load. The radius of curvature of the tip of the needle (ball bearing) is approximately 0.75 mm
The load can be adjusted to change the load on the surface of the toner layer.

The scratches caused by the needle on the surface of the toner layer are examined under a microscope (194x magnification) and classified according to the following criteria (in order of severity of damage): (C) Toner layer is only compressed. (Scr) Layer compaction and fine scratch lines. (Cr) Compression and cracking of toner layer. (S) Needle skipping and partial delamination of layers. (TR) Full layer peeling with wide contact area. Toner layers that crack or exhibit "skips" at lower needle loads than other toner layers are considered mechanically weak. In the present invention, the scratch strength is defined as the load (g) that causes damage to the Cr level.

[0145]

[Table 9]

[0146]

EXAMPLE Dielectric paper type 2089 (manufactured by James River Graphics Corporation) was prepared using a 5% solution of silicone/urea copolymer in isopropanol (
Mayer bar 5 and 0 with silicone content 10%)
It was coated using a combination of The estimated dry thickness of the silicone/urea layer was approximately 0.11 micrometers. For imaging testing, release coated dielectric paper was used in a Synergy electrostatic printer.

In a series of tests, a Synergy Colorwriter® 400 electrostatic printer was used to create dense test patches and 40% halftone patches for black, cyan, magenta, and yellow liquid toners alone. Alternatively, the ability of various combinations of liquid toners to form high quality images was evaluated by printing in full color superimposition. The toners were evaluated for the susceptibility of the image to abrasion damage on a release coated imaging surface and the ability to form a uniform toner deposit over previously formed images of different colors.

Example 1 Release coated dielectric paper and liquid toner B-1 (
black), C-1 (cyan), M-2 (magenta)
and Y-1 (Yellow) were loaded into a Synergy printer and the above test image was printed at a paper travel speed of 3.18 mm/sec (0.125 inch/sec). The image on the release surface appears to be of high quality, i.e. there are no wear marks on any of the test patches and the deposition of the second color on top of the first color formed at the previous imaging station is uniform. and has sufficient thickness to provide good formation of the secondary colors green, blue, and red (yellow on cyan, magenta on cyan, and yellow on magenta, respectively).

Example 2 Different black and magenta and similar yellow toners in combination: B-2 (black), C-1 (cyan), M-1 (magenta) and Y
The same test as in Example 1 was conducted using -1 (yellow). The print quality obtained with this toner combination is completely different and unacceptable, as shown by the following description of each test patch:

Black (B) Some image wear. Cyan (C) No wear. Magenta (M) No wear. Yellow (Y) No wear. Green (C+Y) Slight wear damage. Blue (C+M) Slight wear damage. Red (M+Y) If Y is printed overlapping, M will be worn out. (C+M+Y) Severe wear damage. (B+M+Y) Worse wear than M+Y. (B+C+M) Severe wear damage. (B+C+Y) Severe wear damage.

Example 3 In the toner combination used in Example 2, M
-1 magenta was replaced with M-2 of a different composition. Using this toner set, no abrasion damage occurred on test patches containing fresh magenta (except when the magenta toner was deposited on the black toner layer).

B Some wear damage. C No wear. M No wear. Y No wear. (C+Y) Some wear damage. (C+M) No wear. (M+Y) No wear. (B+M+Y) Wear damage. (B+C+M) Wear damage.

Reference Examples The following block copolymer Examples 1-6 illustrate how to prepare polydimethylsiloxane release coating polymers that can be used in the present invention. A working description of these polymers is also provided.

The general composition of the release coating is as follows: -[-(silicone)a-(hard segment)b-(soft segment)c-]n-
5% 75%
20% or 10
% 75%
15% silicone
DIPIP/IPDI Jeff Amin (Je
ffamine) Here, silicone is PDMS, DI
PIP is dipiperidylpropane, IPDI is isophorone diisocyanate, and Jeffamine is polypropylene oxide with diamine end groups.

[0155] The amount of hard segment is very important in this application, and the results indicate that if there is a non-silicone soft segment, there should be at least 75% hard segment present. Tg result is 75%
The most direct way to show that is minimal is a symptom.

It has been shown that good images can be obtained with hard segments of less than 75% only if there are no soft segments and the proportion of silicone (PDMS) is higher, for example 30-50%.

[0157] This can be explained by the sample shown in the chart. In that case, “zero” silicone (PDM
All samples except sample S) gave good images.

PDMS% Jeffamine%
Hard segment% 5000Mn
Du-700 (800Mn) DIPIP/IPD
I 0 2
5 75
5 20
75
15 10
75 20
5
75 50
0
The solvent was isopropanol.

Silicone = (PDMS) polydimethylsiloxane Hard segment = DIPIP (dipiperidylpropane)/IPDI (isophorone diisocyanate) Soft segment = (Jeffamine) Du-700

[Chemical formula 1] Here, c=11.2.

[0160] Other segments with PDMS may function as a release material, but have been found to give blurry images. For example, hard segment = (
MPMD) Methylpentane methylenediamine/IPDI
or (BISAPIP) bisaminopropylpiperidine/IPDI, soft segment = (PPO) polypropylene oxide.

A preferred organopolysiloxane-polyurea block polymer comprises repeating units of the following formula:

[Case 2]

[In the formula, Z is phenylene, alkylene,
is a divalent group selected from the group consisting of aralkylene and cycloalkylene; Y is an alkylene group having 1 to 10 carbon atoms; R is at least 50% methyl and the remainder is 2 carbon atoms; D is a monovalent group selected from the group consisting of ~12 alkyl groups, vinyl groups, phenyl groups, and substituted phenyl groups; D is hydrogen and a carbon number of 1
B is selected from the group consisting of ~10 alkyl groups; B is alkylene, aralkylene, cycloalkylene, azaalkylene, cycloazaalkylene, phenylene, polyalkylene oxide, polyethylene adipate, polycaprolactone, polybutadiene and mixtures thereof and heterocyclic rings; selected from groups forming a ring structure containing A so as to form; A is -O- and >N-G (where G
is selected from the group consisting of hydrogen, an alkyl group having 1 to 10 carbon atoms, phenyl, and a group forming a ring structure containing B so as to form a heterocyclic ring. ); n is a number of 10 (preferably 70) or more; and m is a number of 0 to about 25. ]

[0163]
In preferred block polymers, Z is selected from the group consisting of hexamethylene, methylenebis(phenylene), isophorone, tetramethylene, cyclohexylene and methylenedicyclohexylene, and R is methyl.

The organopolysiloxane/polyurea block polymers useful in this invention are organic non-aqueous solvent compatible. The term "compatible" as used herein means that the copolymer is soluble in organic solvents (non-aqueous solvents only). Water-compatible polymers contain ionic groups in the polymer chain and are unsatisfactory when coated onto dielectric materials as functional toner release materials. Drying removes water, leaving polar non-silicone segments (quaternary amines) on the surface, and the silicone is almost completely buried beneath the polar non-silicone layer. Therefore, there is not enough silicone on the toner contacting surface and there is no toner release ability when attempting to transfer the image.

The block polymers useful in this invention can be prepared by polymerizing the appropriate ingredients under reaction conditions in an inert atmosphere.

[0166] The ingredients are: (1) a number average molecular weight of at least 500 and formula II:

0
167]

[Chemical formula 3]

[In the formula, R, Y, D and n have the same meanings as in formula I. ] A diamine with a molecular structure shown by;

[
(2) Formula III: OCN-Z-NCO [wherein,
Z has the same meaning as in formula I. ] At least one diisocyanate having a molecular structure shown in

(3) Up to 95% by weight of formula IV: H-A
-B-A-H [wherein A and B have the same meanings as above. ] Contains a diamine or dihydroxy chain extender with the molecular structure shown below.

The molar ratio of silicone diamine, diamine and/or dihydroxy chain extender to diisocyanate in the reaction is such that a block polymer with the desired properties is formed. Preferably, this ratio is maintained in the range 1:0.95 to 1:1.05.

In particular, the solvent compatible block polymers useful in this invention can be prepared by mixing the diisocyanate and the organopolysiloxane by mixing the organopolysiloxane diamine, the diamine and/or dihydroxy chain extender, if used, and the diisocyanate under reaction conditions. can be prepared by obtaining block polymers with hard and soft segments respectively derived from . The reaction is typically carried out in a reaction solvent.

[0173] The donor elements of the present invention can be prepared in a variety of ways. Although the donor element is easy to prepare, the surface to be treated must first be cleaned of any dirt and grease. Any established cleaning method can be used. The surface is then contacted with a solution of the organopolysiloxane/polyurea polymer to form a dry layer of polymer on the surface by various methods such as brushing, bar coating, spray coating, roll coating, flow coating, knife coating, etc. Process at a certain temperature for a certain time to form. For image release coatings, a suitable level of dry coating thickness is in the range of 0.05 to 2.0 micrometers, with a preferred thickness range of 0.08 to 0.3 micrometers, most Good results are obtained at about 0.12-0.18 micrometers.

The non-aqueous polymer solution is diluted with a solvent such as isopropanol to the appropriate solids content and then applied onto the dielectric material. Once dried, coating thickness can be suitably determined by chemical indicator methods if a suitable indicator is included in the non-aqueous release material prior to application to the dielectric material.

[0175] Thickness measurement method, for example, cutting and weighing method (cu
t weight method) is of no use since the coating is very thin.

A colorless pH indicator, preferably thymolphthalein, is added to the non-aqueous silicone/urea coating material (not exceeding 5% of the solids content of the silicone/urea polymer). This colorless indicator changes color to blue upon development of the alkaline solution prior to spectrophotometer absorption reading and calculation.

The requirement for the release coating is that it must be very thin so that a dense image can be developed between the toner and the dielectric material. The function of the indicator is to monitor the coverage of the silicone/urea layer in the submicron range. Since the amount of polymer applied is proportional to the amount of indicator, it is calculated by measuring the absorbance from the colored alkaline solution. The indicator within the block polymer must not only be colorless, but also remain stable and colorless at neutral pH conditions when applied onto the dielectric material. Furthermore, the colorless indicator must not affect the printing and transfer of the image or the aging of the transferred image.

Other indicators may function similarly to the preferred indicators described above, such indicators include m-nitrophenol, o-cresolphthalein, phenolphthalein, ethylbis(2,4-dinitrophenol). ) acetate, etc. Other types of indicators that may function similarly, although not evaluated, are reagents that respond to redox reactions.

A preferred composition giving the best results contains 15-20% soft segments and 7% hard segments.
Using silicone 5-10% consisting of 5%, 12.6%
Contains solid content.

This non-aqueous release polymer is diluted to 3-5% and applied onto James River Graphics dielectric paper #2089 using a #0 or #1 Meyer bar. Meyer bar #0 provides a release coating thickness of 0.12 microns and Meyer bar #1 provides a thickness of 0.18 microns. The allowable coating thickness range is 0
．． 08-0.3 microns, preferably 0.1-0.2 microns.

Example 1: Block polymer Polydimethylsiloxane (PDMS) diamine with number average molecular weight (Mn) 5000 (0.38 g), Jeffamine (Du-700) with number average molecular weight 800 (1.50 g)
and dipiperidylpropane (DIPIP) (2.52
g) in isopropanol (IPA) (242.5 g) at 25°C was added isophorone diisocyanate (IP
DI) (3.10 g) was added slowly over 5 minutes. The viscosity increased rapidly towards the end of the addition and the viscous but clear reaction mixture was stirred for an additional 15 minutes. This resulted in a 3% by weight solution of the block polymer in IPA. The block polymer was 5% by weight of PDMS soft segment and 7% DIPIP/IPDI hard segment.
5% by weight and 20% by weight Jeffamine soft segments.

Example 2: Block polymer Polydimethylsiloxane (PD) having a number average molecular weight of 5000
MS) Diamine (1.13 g), a solution of Jeffamine (Du-700) with number average molecular weight 800 (1.50 g) and dipiperidylpropane (DIPIP) (2.52 g) in isopropanol (IPA) (242.5 g) To,
At 25°C, isophorone diisocyanate (IPDI) (
3.02 g) was slowly added over 5 minutes. The viscosity increased rapidly towards the end of the addition and the viscous but clear reaction mixture was stirred for an additional 15 minutes. This results in
A 3% by weight solution of the block polymer in IPA was obtained. The block polymer had 15% by weight PDMS soft segments, 75% by weight DIPIP/IPDI hard segments and 10% by weight Jeffamine soft segments.

Example 3: Block polymer Polydimethylsiloxane (PDMS) diamine with number average molecular weight (Mn) 5000 (1.50 g), Jeffamine (Du-700) with number average molecular weight 800 (0.38 g)
and dipiperidylpropane (DIPIP) (2.65
g) in isopropanol (IPA) (242.5 g) at 25°C was added isophorone diisocyanate (IP
DI) (2.97 g) was added slowly over 5 minutes. The viscosity increased rapidly towards the end of the addition and the viscous but clear reaction mixture was stirred for an additional 15 minutes. This resulted in a 3% by weight solution of the block polymer in IPA. The block polymer had 20% by weight PDMS soft segments, 75% by weight DIPIP/IPDI hard segments and 5% by weight Jeffamine soft segments.

Example 4: Block polymer Polydimethylsiloxane (PD) having a number average molecular weight of 5000
MS) A solution of diamine (3.75 g), Jeffamine (Du-700) with number average molecular weight 800 (0 g) and dipiperidylpropane (DIPIP) (1.74 g) in isopropanol (IPA) (242.5 g); 25℃
So, isophorone diisocyanate (IPDI) (2.0
1 g) was slowly added over 5 minutes. The viscosity increased rapidly towards the end of the addition and the viscous but clear reaction mixture was stirred for an additional 15 minutes. This resulted in a 3% by weight solution of the block polymer in IPA. The block polymer is PDMS soft segment 50% by weight,
It had 50% by weight DIPIP/IPDI hard segments and 0% by weight Jeffamine soft segments.

Examples 1-4 were all highly functional for clear images upon transfer. Moreover, all the experiments were carried out in a nitrogen atmosphere. Example 5: Block Polymer A solution of polydimethylsiloxane (PDMS) diamine (65 g) of number average molecular weight (Mn) 5000 and bisaminopropylpiperazine (bisAPIP) (15.2 g) in isopropanol (IPA) (530 ml)
At 25°C, isophorone diisocyanate (IPDI) (
19.8 g) was slowly added over 5 minutes. The exothermic reaction was controlled by an ice-water bath to maintain a temperature of 15-25°C during the addition.
I kept it. The viscosity increases rapidly towards the end of the addition;
The viscous but clear reaction mixture was stirred for an additional hour. This resulted in a 20% by weight solution of the block polymer in IPA. The block polymer consists of 65% by weight PDMS soft segment and bisAPIP/IPD
It had 35% by weight I hard segment.

Example 6: Into a 250 ml three-necked flask of block polymer, PDMS diamine (5 g) with a number average molecular weight of 5000, bisAPIP (1.29
g), methylpentamethylenediamine (MPMD) (0
．． 56g) and isopropanol (IPA) (40g
) was added. IPDI (2.76 g) was added while the resulting solution was cooled to 20° C. in an ice bath. This allows the silicone/polyurea to form a viscous but transparent IP.
Obtained as a solution in A. Block polymer is PDM
S soft segment 52% by weight and hard segment 48% (bisAPIP/IPDI 35% by weight and M
PMD (13% by weight).

The following Examples 7 and 8 relate to polymeric materials used in self-releasing dielectric layers in practicing one embodiment of the present invention.

Example 7: Preparation of dielectric layer copolymers and terpolymers of vinyl monomers and siloxane macromonomers is described in US Pat. No. 4,72
No. 8,571. Using this preparation method, choosing methyl methacrylate (MMA) or a mixture of MMA and styrene as the vinyl monomer and polydimethylsiloxane as the siloxane macromonomer, we obtain the polymer used in the present invention for the self-releasing dielectric layer. .

Example 8: Dielectric Layer A dielectric layer was prepared by applying a coating solution containing a copolymer or terpolymer onto a paper substrate. The coating solution was prepared from a polymer solution with the following composition (
% is weight%):

Polymer solution
50
% (30% solids in ethyl acetate/toluene 2:1) Clay (Translink)
nk) 37) 3.7
5% calcium carbonate

2.50% titanium dioxide

1.25% toluene

50%

These solutions were ball milled for 4 hours and coated onto a James River Graphics "Dielectrically Treated" paper base using a #14 Meyer bar to obtain a layer with a wet thickness of 30.5 micrometers. Ta. After drying, the coatings were conditioned for 12 hours at 21°C (70°F) at 50% relative humidity before use for imaging.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of a print station useful in the present invention.

FIG. 2: Complex dynamic viscosity of the surface coating on the receptor sheet and CIELAB color difference value (Δ
It is a graph showing the relationship with E).

[Explanation of symbols]

1. Intermediate receptor 2 Base material 4 Dielectric layer 6 Release coating 10 Write head 12 Charge 14 Uncharged surface area 16 Toner applicator 18 Liquid toner bath 20 Container 22 Liquid toner 24 Area with toner 26 Toner-free area 28 Vacuum squeegee

Claims (12)

[Claims] 1. a) A flexible material having at least one surface exhibiting dielectric and toner release properties and characterized by a surface energy of 14 to 20 ergs/cm2, said surface energy consisting of a polar component not exceeding 5%. b) moving the imaging sheet through the printer at a substantially constant speed; c) depositing a first image on the surface of the imaging sheet by imagewise charge deposition; forming a first electrostatic latent image corresponding to a color, d
) Developing the first latent image using a rotating applicator bar with a first toner corresponding to the first color to produce a first latent image having a scratch strength of 40 g or more and a surface energy of 50 ergs/cm2 or more. forming a toner image, e) drying the toner image, and f) repeating steps c), d) and e) above with a toner corresponding to at least one other color so that the developed toner is When overlapping the previously developed toner, the work of adhesion at the interface formed between the first toner and the second toner is the same as the work of adhesion at the interface formed between the toner and the image sheet. g) applying the multicolored toner image formed on the surface of the imaging sheet to the surface of the imaging sheet at an elevated temperature under pressure; and has a Tg at the surface between 10°C and 5°C lower than the high temperature.
transferring the multicolored toner image without distortion to the surface of the receptor sheet by contacting the surface of the receptor sheet with the surface of the receptor sheet, the receptor sheet having a flexible substrate having the surface; is selected from the group consisting of acrylic, polyolefin, polyvinyl acetal, polyvinyl chloride film and polyurethane film;
An electronic imaging method for forming multicolor toner images with an electrostatic printer consisting of a polymer film having a haze greater than 0% and a thickness of 30 to 500 micrometers. 2. The flexible imaging sheet according to claim 1, comprising an electrically conductive substrate coated with a dielectric layer on one of its two main surfaces and another top layer having the releasability. electronic imaging method. 3. The top layer is a silicone-urea block polymer, urethane-silicone copolymer, epoxy-containing 1-65% by weight polydimethylsiloxane.
3. The electronic imaging method of claim 2, comprising a release material selected from the group consisting of silicone copolymers and acrylic-silicone copolymers. 4. The method of electronic imaging according to claim 1, wherein said polymer comprises polyvinyl chloride or polyurethane. 5. A terpolymer of polydimethylsiloxane, methyl methacrylate and polystyrene and a copolymer of polydimethylsiloxane and methyl methacrylate, wherein the dielectric layer contains 10 to 30% by weight of polydimethylsiloxane based on the total polymer weight. 5. The electronic imaging method of claim 4, further comprising a material selected from the group consisting of: 6. The receptor sheet comprises a substrate having a thermoplastic layer comprising a polymer selected from thermoplastic polymers having a complex dynamic viscosity of less than 2.5×10 poise at a temperature equal to the elevated temperature. The electronic image forming method according to claim 1. 7. The thermoplastic layer comprises methyl acrylate, butyl methacrylate, copolymers of methyl methacrylate and other acrylates, low molecular weight ethyl methacrylate, isobutyl methacrylate, vinyl acetate/vinyl chloride copolymers, polyurethanes and aliphatic polyesters. 7. The electronic imaging method of claim 6, comprising a polymer selected from the group. 8. The electronic image forming method according to claim 6, wherein the high temperature of the substrate is between 50 and 150°C. 9. The electronic image forming method according to claim 1, wherein the multicolor toner image is formed by one pass through the electrostatic printer. 10. A flexible 30-500 micrometer thick film formed from a resin selected from the group consisting of acrylics, polyolefins, polyvinyl acetals, polyvinyl chlorides and polyurethanes and having an optical density of at least 1.0. a polymeric substrate having a Tg of 10 to 105°C on one surface thereof.
, a complex dynamic viscosity of less than 1.0 x 105 poise and a
A receptor sheet with a receptor coating composition having a dry thickness of 30 micrometers. 11. The receptor sheet according to claim 10, wherein the substrate comprises polyvinyl chloride. 12. A receptor sheet according to claim 10 or 11, wherein the second surface of the substrate has an adhesive coating.