KR940007771B1 - Imageable toner powder - Google Patents

Abstract

No content.

Description

Image receptor

FIELD OF THE INVENTION The present invention relates to imaging systems, and more particularly to imaging systems containing elements useful for thermal imaging systems.

BACKGROUND OF THE INVENTION Image generation processes are known in which heat is applied to make a heat sensitive material viscous at an image site or fluidize and then attach and develop the image powder to a viscous image site. Such a process is described in US Pat. Nos. 3, 941, 596.

To form a latent image, a thermally sensitive material (referred to as a thermally sensitive material, referred to below as heat sensitive material) must be viscous or flowed using a thermal print head. A simple thermal print head has at least one resistive element between two conductors. Thermal print heads are listed as resistive elements. Therefore, there may be 5-7 elements in the print head. In addition, the print head is fixed to or detachable from the surface being imaged.

The resistive element is brought into contact with the thermosensitive material, the current is allowed to flow in the device for a time sufficient to heat the device, the temperature is raised to a level sufficient for the material to melt at the contact, then the current is cut off and the device Rearrangement forms a latent image. The contact, heating, and repositioning steps are repeated until a sufficient number of dot-melt sites appear in the desired latent liquid image. When the printhead consists of only one element, the steps necessary for latent image formation must be repeated several times before the distinct image needed is displayed. When the print heads are listed as elements or in a matrix, the steps required to form the latent image are repeated for much less time than above.

A serious problem with thermal print heads is that the thermal material on the surface containing the image is contaminated. Typically the print head is placed in direct contact with the thermosensitive material. If a small amount of thermally sensitive coating is transferred to the print head to form deposits there, the resolution or image density, or both, will be drastically reduced.

In most cases, thermal print heads are not easy to clean. Some manufacturers of thermal printers suggest passing rough bond paper through the printer to remove deposits from the print head. In order to shorten time and improve resolution, it is desirable to widen the spacing of the cleanly cleaned thermal print heads.

The medium which receives (receives) the image of the present invention is a sheet-like substrate, which is a substrate on which at least one surface is covered with a thermosensitive material; The thermosensitive material coating includes at least one antifouling agent selected from the group consisting of (a) a substance that can be present in a supercooled state after heating and cooling, (b) a wax, silica, metal silicate or mixture thereof, and ( c) optionally consists of a binder.

When an image heated with a thermal print head appears, the sheet with the thermally sensitive coating described above sticks to the image portion. Imaging powder particles may adhere to these adhesive sites. Optionally, the calculated image can be fixed at the same time or later.

The advantage of the thermosensitive coating described above is to prevent the thermal print head from being contaminated with the coating material residue to ensure an image that exhibits excellent resolution over long periods of time without requiring frequent cleaning of the print head.

Substances which may be present in the supercooled state after heating and cooling (hereinafter referred to as supercoolable substances) should have a melting temperature higher than the circulation temperature and about 10 ° C higher. The circulation temperature refers to the ambient temperature (eg, room temperature of 19 ° C.-20 ° C.) when the imaging process is started.

In addition, the coating material forms a supercooled melt when cooled to a temperature below the melting temperature. That is, these materials are melted and then cooled to a lower temperature than melting and then, at least temporarily, as a fluid modification liquid and then cooled to below the melting temperature. Once a latent image is formed it must wet the substrate surface. In addition, the image must remain fluid until the latent image contacts (or develops) with the dry image powder.

Alternatively, the image may be cooled to a temperature below the melting temperature to form a supercooled melt before the image portion is developed. It is because the supercooled liquid is not obtained in the solid state, and therefore the substance has sufficient memory in the image portion to be developed and fixed. If the substance is obtained in the solid state at the imaging site, the latent image no longer exists as a distinguishable site.

Preferably, the supercoolable material melts at a temperature of 40-140 ° C.

Since no chemical literature describes suitable data that can define the supercoolable material useful in the practice of the present invention, a robust definition test procedure is provided below.

An object of the present invention is to place a small amount of material in powder form on a glass microscope slide, cover it with carver glass, and then heat the material on a microscope equipped with a high temperature stage with a temperature measuring device, and then observe the temperature at which the particles melt and fuse. To determine the melting point or melting range of supercooled materials.

The test to determine whether the material is a supercoolable material suitable for the present invention can be easily performed using the same sample as used in the melting point measurement test. Leitz's high temperature stage microscopes, equipped with an electrically heated stage that can be cooled by circulation of coolant, are used to determine the two mentioned above: the melting point of the supercooled material and whether it is supercooled.

After the stage is heated to a temperature above the melting point of the sample, it is cooled to determine the crystallization temperature or the solidification temperature. Heating and cooling can be carried out at a higher rate of temperature change than normal temperature for more accurate measurements. The material thus treated is useful as the supercoolable material of the present invention when it remains liquid at a temperature below its melting point, ie at 60 ° C. after heating and cooling; Materials that crystallize or solidify at melting or similar temperatures cannot be used to make hidden images with powders suitable for the present invention. Some materials are solidified into glass, rather than a visually indistinguishable crystalline state, and are readily measurable when applied to a carver glass with a suitable spatula, retaining its form as glass kernels, while liquid droplets flow or quickly crystallize.

Precision tests for determining supercoolable materials suitable for the present invention are described in US Pat. No. 3,360,367, which is incorporated herein by reference. Numerous supercooled materials are useful as coatings of the present invention. Representative examples of such materials include dicyclohexine phthalate, diphenyl phthalate, triphenyl phosphate, dimethyl fumarade, benzotriazole, 2, 4-dihydroxy benzophenol, tribenzylamine, benzyl, vanillin and phthalophenone do.

Other useful materials of this type include ortho- and para-toluene sulfonamide mixtures marketed as "Santicizer 9" by Monsanto Chemical Company. Mixtures of such materials are also useful. Supercoolable materials themselves are also not supercooled but may be mixed with two or more materials to form a supercoolable material.

Antifouling agents can be selected from the following classes of materials:

A. Wax

B. Silica

C. Metal Silicate

D. Silica or Metal Silicate

Mixture of these two with wax

As described above. "Anti-contamination agent" means a substance that is a chemical compound or mixtures thereof, which refers to a substance that is added to a thermosensitive composition that prevents or prevents deposits on the thermal print head. Waxes, silicas, metal silicates useful as antifouling agents in the compositions of the present invention can sometimes be considered lubricants and anti-sticking agents.

Suitable waxes for the compositions of the present invention include symmetric ketones derived from at least 10 carbon aliphatic alcohols, at least 12 carbon fatty acids, at least 12 carbon fatty amides, at least 12 carbon fatty acid esters, and at least 12 carbon fatty acids, Metal salts of at least 12 carbon atoms and fluorocarbon polymers.

Aliphatic alcohols suitable for the composition of the present invention are represented by the following formula.

R ¹ -CH ₂ OH

Wherein R ¹ is a saturated or unsaturated hydrocarbon radical, for example alkyl, alkenyl having 9 to 21 carbon atoms. Representative examples of such aliphatic alcohols are cetyl, stearyl, lauryl, myristyl and mixtures thereof.

Fatty acids suitable for the composition of the present invention can be represented by the following formula.

R ² here is a saturated or unsaturated hydrocarbon radical, for example alkyl, alkenyl having 11-21 carbon atoms. Representative examples of such fatty acids are palmitic acid, stearic acid, lauryl acid, myristic acid and mixtures thereof.

Fatty amides suitable for the compositions of the present invention can be represented by the formula:

또는 H를 나타낸다. 이러한 지방아미드의 대표적인 예로는 스테아르아미드, 라울 아미드, 올레아미드, 에틸렌-비스-스테알아미드, 이것의 혼합물이 있다.Where R ² is as described above and X is

Or H. Representative examples of such fattyamides are stearamide, lauryl amide, oleamide, ethylene-bis-stealamide, mixtures thereof.

Fatty acid esters suitable for the composition of the present invention can be represented by the following formula.

Wherein R ² is as described above and R ³ is a saturated or unsaturated hydrocarbon radical, for example alkyl, alkenyl having 1-22 carbon atoms, wherein the hydrocarbon radical is unsubstituted or substituted with a hydroxy group.

Representative examples of such fatty acid esters are glyceryl stearate, for example glyceryl monostearate, diethylene glycol monostearate, glycol stearate, cetyl palmitate, stearyl stearate, n-butyl stearate and n-octyl There is stearate.

Symmetric ketones suitable for the composition of the present invention can be represented by the following formula.

Where R ² is as described above.

Representative examples of symmetric ketones derived from fatty acids useful in the compositions of the present invention are stearone and lauron.

Metal salts of fatty acids suitable for the composition of the present invention can be represented by the following formula.

Where M is a metal atom, n is an integer of 1-3 and R ² is as defined above.

Metal salts of fatty acids suitable for the compositions of the present invention are octoates, laurates, palmitates and stearates of aluminum, lead, cadmium, barium, calcium, lithium, magnesium and zinc. Of these, metal stearate is most preferred. Mixtures of metal salts of fatty acids such as zinc stearate and fatty acids such as stearic acid are used as antifouling agents in the compositions of the present invention.

One or more hydrogen atoms in the hydrocarbon radicals R ¹ , R ² , R ³ may be replaced by other elements, such as halides, or by elements such as hydroxyl groups, which adversely affect the antifouling properties of the wax decontamination agent. Possible to the extent that does not cause.

Suitable fluoro carbon polymers for the compositions of the present invention are polymerizable tetrafluoroethylene.

Silicas and metal silicates can be used as antifouling agents in the compositions of the present invention, and representative examples of such antifouling agents are silica gel, fumed silica, precipitated silica, clay, kaolin and talc. Silica and metal silicates may be mixed with metal salts of fatty acids such as metal stearate, fluoro carbon polymers such as polytetrafluoroethylene, fatty amides such as stearamide, and the like to enhance the antifouling action.

A binder may be included in the thermosensitive composition of the image receiving device. The thermosensitive compositions tend to peel from each other under conditions without binder. Representative examples of organic polymerizable binders suitable for the present invention include water-soluble binders such as polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, and binders dissolved in organic solvents such as cellulose acetate, ethyl cellulose and provinyl chloride.

Suitable materials for use in the present invention may be selected from anhydrous solid materials which are compatible with coatings which are generally solid and non-stick materials. Examples of suitable materials are polymerizable films, metal foils and papers. Preferred material is paper.

In the thermosensitive coating material, the concentration range of each component is very important. Thermal printheads are contaminated relatively quickly when very little antifouling agent is used. When an excess amount of antifouling agent is used, the optical density of the tinted image is very low. The concentration range of each component depends on the nature of the antifouling agent used. When the wax is used as an antifouling agent, the essential ingredient concentration ranges of the thermosensitive coating material are as follows.

When silica or metal silicate is used as antifouling agent, the concentration range of the thermosensitive essential ingredient is as follows.

When silica or metal silica or both are used in combination with wax as antifouling agent, the concentration range of the thermosensitive material essential component is the same concentration as when silica or metal silicate were each used alone as antifouling agent.

The coating material may be applied to the substrate surface using various techniques such as solvent coating and dry coating. For example, the thermosensitive coating can be dissolved or dispersed in a suitable solvent (acetone, water) and the solvent is evaporated after the solution or dispersion is applied to the substrate. The previously dissolved or dispersed solid material may then be crystallized.

If desired, solvent evaporation can be facilitated by heating the coated substrate. However, great care must be taken to ensure that the substrate does not shrink or adversely affect as a result of heating. In addition, crystallization of the dissolved or dispersed solid material can be facilitated by seeding the coated substrate with a solid material.

Dry coating techniques may also be used. The thermosensitive coating in solid form can be brushed or rubbed on the substrate. Preferably, the solid form material is in a form that can be easily converted into a powder or in powder form. Dry coating techniques are an effective means of applying a substrate to a substrate. Materials treated with dry coating techniques are not absorbed into the substrate as solvent coating techniques did.

Dry coating techniques are more desirable because they reduce the amount of coating applied to the substrate while continuing to provide good images as applied by solvent coating techniques. In addition, when coating a flat paper engine by dry coating technology, the resulting sheet can be used immediately after coating because it is indistinguishable from an uncoated paper sheet.

The actual amount of coating material present on the substrate may vary. There must be sufficient coating to form the latent image, but excess material is undesirable because it can adversely affect the thermal print head, causing the product to be electrically energized, slippery, or smudged. Once the latent image is formed, triboelectric or magnetic forces or both forces are generated. To solve this problem, a sufficient amount of coating material must be used to create sufficient adhesion between the latent image and the image powder.

Excellent results are obtained when an amount of about 0.1-5 g / m 2 is used. When solvent coating is used, the substrate contains 0.1-2 g / m 2 of material, more preferably 0.1-2 g / m 2 of material, most preferably 0.2-1.0 g / m 2 of material. This relatively small amount of coating is sufficient to provide a latent image that can be developed and permanently fixed to the substrate.

When dry coating techniques are used, particulate matter is absorbed on the substrate surface. When the substrate is paper, the material adheres to the surface of the paper fiber.

The imaging area must provide sufficient adhesion to the dry imaging powder. The imaging area can react with the imaging powder; It can form a solution with powder; It can soak powder; It can also be absorbed or adsorbed to the powder. Whatever the interaction between the powder and the image area, the image area must have powder until the powder is fixed to the substrate.

The coating was evaluated by printing a solid bar (26 inches long) of the thermal print head of the EMT 9140 Facsimile Machine (3M). The latent image was then developed with the toner powder of the toner powder and the VQC compact copyer 3M described in Example (1) of US Pat. No. 3,925,219. The size of the toner particles was 10-45 micrometers.

The printing machine used a film print head with a thickness of 100 steel / inch, commercially available from Rolm Corporation.

The printhead residue was evaluated by visual inspection by enlarging the head by 5 × times and the printhead residue based on the following criteria.

None-No deposits with the naked eye.

Trace-There is a small deposit of coating that adheres to the printhead.

There is a small amount of deposit that forms a continuous coating at the site of the Light-Printhead, but this does not prevent the head from contacting the paper.

Medium-deposits that form a continuous coating on half of the printhead

Heavy-There is a large amount of deposits at the front and back of the printhead (this prevents the head from contacting the paper and heat carrier).

Post-development image density was measured with a MacBeth TR 924 density meter with reflection mode.

Example 1-8

Coating formulations are shown in Table (I). The amounts in the following table are parts by weight.

TABLE 1

101 kaolin(Engelhard Minerals and Chernicals Corp. 에서 시판)1 AST

101 kaolin (commercially available from Engelhard Minerals and Chernicals Corp.)

2 Fluo HT2 (commercially available from Micro Powders, Inc.)

X-6000(W.R.Grace and Co.에서 시판)3 Sylcid

X-6000 (commercially available from WRGrace and Co.)

Phthalates and cellulose binders were dissolved in acetone. The wax antifouling agent was dispersed in a phthalate / binder / acetone solution using an ultrasonic bath. The antifouling agent, filler, was dispersed in a phthalate / binder / acetone solution using a homogenizer. The dispersion was coated on paper using a # 8 wire rod with a diameter of 1/2, and drying the air yielded a dry coating having a weight of 0.28-0.36 g / ft ² .

Each coated sheet was measured and the results are shown in Table (II).

TABLE 2

Printhead deposits ranged from grades 3 to 5, where there was no contamination inhibitor in the thermosensitive material. The printhead deposits changed from grade 1 to grade 2 when at least one antifouling agent was contained in the thermosensitive binder.

Example 9

This example shows the coating weight effect on printhead deposits.

The following formulation was used to prepare test samples.

1 N-200 grade available from Hercules Inc

2 Fluo HT2 available from Micro Powders Inc

Formulation samples were coated on paper in a coating weight range of 0.26 g / m 2-0.95 g / m 2. Using different Mayer rods changed the coating weight. The evaluation results for the print head deposits are shown in Table (III).

TABLE 3

Table III provides the maximum optical density values without print head deposits when the dry coat weight was 0.62 g / m 2.

Example 10-16

These examples show the effect of various waxes mixed with metal silicates (aluminum silicates) in coating compositions.

The following formulation was used in these examples. In the following table, the amount is parts by weight.

TABLE 4

101 kaolin(Engelhard Minerals and Chernicals Corp. 에서 시판)1 AST

101 kaolin (commercially available from Engelhard Minerals and Chernicals Corp.)

2 Fluo HT2 (commercially available from Micro Powders, Inc.)

3 Polyfluo 540 (commercially available from Micro Powders Inc.)

Each coating was evaluated and the results are shown in Table (V).

TABLE 5

Modifications and variations of the present invention are possible by those skilled in the art without departing from the scope and spirit of the present invention, and the present invention is not limited only by the above embodiments.

Claims (21)

A coating containing (a) a material which may be present in supercooled state after melting and cooling on at least one surface, and (b) at least one antifouling agent selected from the group consisting of waxes, silicas, metal silicates and mixtures thereof. An image receiving device comprising a substrate covered. The device of claim 1, further comprising a binder. The device of claim 1 wherein said antifouling agent comprises a wax. The device of claim 2, wherein the antifouling agent comprises a wax. 4. The device of claim 3, wherein said antifouling agent is selected from the group consisting of aliphatic alcohols, fatty acids, fatty amides, fatty acid esters and symmetric ketones derived from fatty acids. 6. The device of claim 5, wherein the antifouling agent is represented by the following formula. R ¹ -CH ₂ OH Wherein R ¹ is a saturated or unsaturated hydrocarbon radical of 9-21 carbon atoms. 6. The device of claim 5, wherein the antifouling agent is represented by the following formula.

In which R ² represents a saturated or unsaturated hydrocarbon radical of 11-21 carbon atoms. 6. The device of claim 5, wherein the antifouling agent is represented by the following formula.

Wherein R ² is a saturated or unsaturated hydrocarbon radical of 11-21 carbon atoms and X is

Or H. 6. The device of claim 5, wherein the antifouling agent is represented by the following formula.

Wherein R ² is a saturated or unsaturated hydrocarbon radical of 11-21 carbon atoms and R ³ is a hydrocarbon radical of 1-21 carbon atoms. 6. The device of claim 5, wherein the antifouling agent is represented by the following formula.

Wherein R ² is a saturated or unsaturated hydrocarbon radical of 11-21 carbon atoms. 4. A device according to claim 3, wherein said antifouling agent is a metal salt of a fatty acid. The device of claim 11, wherein the antifouling agent is represented by the following formula.

Wherein R ² is a saturated or unsaturated hydrocarbon radical of 11-21 carbon atoms, n is an integer of 1-3 and M is a metal atom. 4. The device of claim 3 wherein said antifouling agent is a fluorochemical wax. The method of claim 1, wherein the material, which may be present in the supercooled state after melting and cooling, comprises 55-99% by weight of the coating, the wax comprises 1-16% by weight of the coating, and the binder comprises An element characterized by occupying 40% by weight or less. 3. The material of claim 2 wherein the material, which may be present in the supercooled state after melting and cooling, comprises 55-99% by weight of the coating, the wax comprises 1-16% by weight of the coating, and the binder is coated. An element which occupies 40% by weight or less of the device. The device of claim 1, wherein the antifouling agent comprises silica or metal silicate. 17. The method of claim 16, wherein the material, which may be present in the supercooled state after melting and cooling, comprises 50-95% by weight of the coating, the antifouling agent comprises 5-40% by weight of the coating, and the binder is coated. Device comprising from 3 to 40% by weight of. The device of claim 1, wherein the antifouling agent comprises a mixture of wax and silica or metal silicate. The device of claim 2, wherein the antifouling agent comprises a mixture of wax and silica or metal silicate. 19. The method of claim 18, wherein the material, which may be present in the supercooled state after melting and cooling, comprises 50-95% by weight of the coating, the antifouling agent comprises 5-40% by weight of the coating, and the binder A device comprising 3-40% by weight of the coating. 20. The method of claim 19, wherein the material, which may be present in the supercooled state after melting and cooling, comprises 50-95% by weight of the coating and the antifouling agent comprises 5-40% by weight of the coating. Wherein the binder comprises 3-40% by weight of the coating.