JPH11143108A - Image receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image receiving sheet whose detection mark is erased by the heat and the pressure used in an image forming time so that it is inconspicuous when the image is formed by the copying machine or the printer of a high-speed electrophotographic system or a thermal transfer system. SOLUTION: This image receiving sheet has the opaque porous detection mark formed by coating with resin varnish consisting of resin, good solvent whose boiling point is low and poor solvent whose boiling point is high. Then, one or more resin layers which are not porous is formed on the detection mark. The detection mark becomes transparent when it is heated. By the detection mark, the optical detector in the image forming time is normally executed. When the detection mark is melted by the heat and the pressure used in a high-speed fixing time, it becomes a uniform layer and transparent because the porosity thereof is crushed. Since the ruggedness of the surface of the detection mark is covered with the resin layer which is not porous while keeping the opacity of the detection mark before the image is formed, the surface of the detection mark obtained after the image is formed is smooth and the detection mark is made transparent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image receiving sheet, and more particularly, to an opaque image formed by heat and pressure during image formation, which is used for an image forming apparatus such as an electrophotographic system or a thermal transfer system which is subjected to a heat treatment during image formation. The present invention relates to an image receiving sheet in which a detection mark becomes transparent.

[0002]

2. Description of the Related Art Recently, using an electrophotographic method, not only a black single-color image is formed, but also a full-color image is formed by mixing three color toners of yellow, magenta, and cyan or four colors obtained by adding black to the above three colors. Image forming methods have been put to practical use. The image receiving sheet used in the electrophotographic copying machine generally has a configuration in which a receiving layer is formed on a base material in order to reliably record and hold recorded information such as characters and images. This image receiving sheet, for example, lectures, schools,
It is used for OHPs (overhead projectors) as information transmission means used in companies, other briefings and exhibitions.

In the electrophotographic system, in order to detect a paper jam or the front and back of a paper, in the case of a color image, an image of three colors of yellow, magenta and cyan or a four-color image obtained by adding black to the above three colors is used. Detecting means is provided for forming the pattern in register on the same image receiving sheet. In particular, in order to form an image on a transparent image receiving sheet, for example, optical detection means for irradiating light from a light source to the transparent image receiving sheet and detecting the presence or absence of reflected light or transmitted light by a photo sensor is provided. I have.

For example, it has been practiced to provide a detection mark with opaque ink or metallic luster ink. In addition, the present applicant has disclosed in Japanese Patent Application Laid-Open Nos. 7-49581 and 7-56376.
In the opaque detection mark provided on the image receiving sheet,
It has been filed that the image is made transparent by heating at the time of image formation, and only a necessary image is projected when the OHP device is used, and the detection mark is inconspicuous and unobtrusive even when projected. JP-A-7-49581 and JP-A-7-56376 describe:
A transparent resin varnish consisting of a resin, a good solvent having a low boiling point, and a poor solvent having a high boiling point is applied, dried, and then gelled to form an opaque porous layer. It melts and becomes transparent, and the detection mark is erased.

[0005]

Recently, copying machines and printers of an electrophotographic type or a thermal transfer type for forming an image have been developed.
In order to improve the processing efficiency, the sheet is conveyed at a high speed, and each energy is lower than before under the conditions of heat and pressure during image formation. In such a situation, in a copying machine or a printer of a high-speed processing electrophotographic system, a thermal transfer system, or the like, a problem has arisen that a conventional image receiving sheet cannot erase a detection mark due to heating during image formation.

More specifically, since a sufficient amount of heat is no longer applied to the detection mark, the porous body is completely melted,
A problem has arisen that the surface cannot be crushed, and in particular, the unevenness on the surface of the detection mark cannot be smoothed. Therefore, when the image receiving sheet is projected by the OHP, the detection mark becomes conspicuous. Therefore, an object of the present invention is to solve the above-described problem by detecting an image by applying heat and pressure during image formation when forming an image with a copying machine or a printer such as a high-speed processing electrophotographic system or a thermal transfer system. An object of the present invention is to provide an image receiving sheet in which marks are erased so as to be inconspicuous.

[0007]

To achieve the above object, the present invention provides an opaque porous material formed by applying a resin varnish comprising a resin, a good solvent having a low boiling point and a poor solvent having a high boiling point. In the image receiving sheet having the detection mark described above, one or more non-porous resin layers are provided on the detection mark, and the detection mark is made transparent by heating.
Further, in an image receiving sheet provided with a receiving layer on a base material, the detection layer is provided on the receiving layer side or the back side of the base material, on the base material itself or on the outermost surface of the image receiving sheet, and on at least one surface. It is preferable to have a mark. Further, it is preferable that the solvent of the coating liquid for the non-porous resin layer does not dissolve the opaque detection mark of the porous body. Further, it is preferable that the non-porous resin layer contains a resin having antistatic properties. Further, the surface electric resistance value of the non-porous resin layer is 10 ⁸ to 10 ¹⁵ Ω / sq.
It is preferred that

The operation of the present invention is as follows. The present invention relates to an image receiving sheet having an opaque porous body detection mark formed by applying a resin varnish comprising a resin, a low-boiling good solvent, and a high-boiling poor solvent, wherein a porous material is provided on the detection mark. By providing at least one non-porous resin layer, the unevenness on the surface of the detection mark is covered, and the non-porous uniform resin layer has a smooth surface as the outermost surface of the image receiving sheet. When a non-porous resin layer is applied, the solvent of the coating liquid does not dissolve the detection mark of the porous body immediately below the coating surface, thereby maintaining the opacity of the detection mark.

Therefore, the detection mark allows the optical detection at the time of image formation to be performed normally, and the detection mark of the porous body is melted by the heat and pressure at the time of fixing in the high-speed processing to crush the porous material. This is to make the layer uniform and to make it transparent. With conventional detection marks, a sufficient amount of heat could not be applied, so the porous body was completely melted and could not be crushed.In particular, the problem was that irregularities on the surface of the detection mark could not be smoothed. In the image receiving sheet of the present invention, while maintaining the opacity of the detection mark before image formation, the unevenness of the surface of the detection mark is covered with a resin layer that is not a porous body, so that the surface of the detection mark after image formation is smooth. Yes,
In addition, the detection mark is made transparent.

In the image receiving sheet of the present invention, the detection mark is used to normally perform optical detection during image formation, and the detection mark of the porous body is melted by heat and pressure at the time of fixing in high-speed processing. To make it uniform and transparent.
While maintaining the opacity of the detection mark before image formation, the unevenness of the detection mark surface is covered with a non-porous resin layer, so that the detection mark surface after image formation is smooth and the detection mark Be transparent.

[0011]

Next, an embodiment of the present invention will be described. The image-receiving sheet of the present invention is provided with a receiving layer formed on a substrate as required, and a back layer provided on the other surface of the substrate, if necessary, on the receiving layer side of the substrate or the back layer. The detection mark is provided on the base material itself on the side or on the outermost surface of the image receiving sheet. Then, one or more non-porous resin layers are provided on the detection mark of the opaque porous body formed by applying a resin varnish comprising a resin, a good solvent having a low boiling point, and a poor solvent having a high boiling point. is there.

(Substrate) As the substrate used in the image receiving sheet of the present invention, when the image receiving sheet is, for example, an OHP sheet and the recorded image is observed by transmitted light, transparency, heat resistance, dimensional stability, Those formed of a thermoplastic resin having rigidity are preferred. Specifically, a polyethylene terephthalate resin, a polycarbonate resin, an acrylic resin, a polyvinyl chloride resin, a polypropylene resin, a polystyrene resin, a polyethylene resin, a cellulose diacetate resin, a cellulose triacetate resin, etc., have a thickness of 10 to 250 μm.
Film or sheet having a thickness of about 50 to 180 μm. Among them, polyethylene terephthalate resin, polyvinyl chloride resin, polypropylene resin,
Cellulose triacetate resin is more preferred in view of the above performance.

For use in observing recorded images by reflected light, these resin sheets or films are preferably opaque such as white due to the addition of a coloring agent or the like. In this case, the base material may be papers such as synthetic paper and coated paper. Moreover, if it is made of a translucent substrate, it can be used for illumination. For the purpose of improving the adhesion to the layer formed on the substrate, the surface of the substrate may be subjected to a known easy adhesion treatment such as a primer treatment or a corona discharge treatment.

(Receiving Layer) The receiving layer provided on one side of the base material is formed directly on the base material or via a primer layer. If the substrate itself has an ink receiving property, no receiving layer is provided. For example, in the case of sublimation transfer recording, if the base material itself has a dyeing property with a thermal transfer sheet and a release property like a polyvinyl chloride resin, the base material is not provided, and the base material is not provided. This is because it has the function of the receiving layer.

The structure of the receiving layer is different depending on the difference between the electrophotographic method and the thermal transfer method of melt transfer recording or sublimation transfer recording. In the electrophotographic method, as the resin forming the receiving layer, polyethylene, polyolefin resin such as polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyacrylate, polyethylene terephthalate, Polybutylene terephthalate, polystyrene resins, polyamide resins, copolymers of olefins such as ethylene and propylene with other vinyl monomers, ionomers, ethyl cellulose, cellulose resins such as cellulose acetate, polycarbonate resins and the like, and particularly preferred. Are vinyl resins, polyester resins, and vinyl chloride-vinyl acetate copolymer resins.

The receiving layer is prepared by adding various auxiliaries as necessary to the above resin, and dissolving or dispersing the composition in an appropriate solvent.
By forming means such as a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate,
Coated, dried and formed. The thickness of the receiving layer is usually 0.1 to 10 μm in a dry state. Further, as an auxiliary agent to be added to the electrophotographic receiving layer, for example, for the purpose of imparting lubrication, a fluorine-based polymer such as ethylene tetrafluoride polymer or ethylene-tetrafluoroethylene polymer,
Stearates such as zinc stearate, organic polymers such as polyethylene and polystyrene, inorganic fine particles such as silica and alumina, wax, silicone oil,
Surfactants, vegetable oils, animal oils, mineral oils and the like are used. Among them, fluorinated polymers are most suitable because the polymers themselves have excellent surface lubricity.

In addition, for the purpose of preventing double feed due to blocking generated when an image receiving sheet is supplied to a printer,
Organic polymer fine particles such as polyolefin fine particles such as polyethylene, polystyrene fine particles, polyacryl fine particles, ethylene acrylic acid copolymer fine particles, silica, kaolin, clay, talc, silica, aluminum hydroxide,
Any of inorganic fillers such as titanium dioxide, calcium carbonate, aluminum sulfate, and zinc oxide, and fine particles of glass beads can be added to the receiving layer. However, in the case of OHP, it is added in such an amount that the transparency of the receiving layer is not impaired.

The receiving layer for the melt transfer recording and the sublimation transfer recording is
It has the function of receiving the color material transferred from the thermal transfer sheet by heating, especially when the color material is a sublimable dye, accepts it, develops the color, and does not re-sublimate the dye once received. It is desired. This receiving layer
It is mainly composed of a receiving layer resin. The receiving layer resin is, for example, a resin having an ester bond, a resin having a urethane bond, a resin having an amide bond, a resin having a urea bond, a resin having a highly polar bond, or a mixture or copolymer resin thereof. For example, many resins can be used. In particular, a mixture of an ethylene-vinyl acetate copolymer and polyvinyl chloride is preferred. This receiving layer can be added with an organic or inorganic filler or the like as necessary to the above resin. Further, in the case of sublimation transfer recording, a release agent can be added in order to improve the thermal releasability from the thermal transfer sheet.

Examples of the release agent include silicone oil,
Phosphate-based surfactants, fluorine-based surfactants and the like can be mentioned, but silicone oil is preferred. Epoxy-modified, alkyl-modified,
Modified silicone oils such as amino-modified, carboxyl-modified, alcohol-modified, fluorine-modified, alkyl-aralkyl-polyether-modified, epoxy / polyether-modified, and polyether-modified are preferred. One or more release agents are used. The amount of the release agent added is 0.1 to 100 parts by weight of the binder resin forming the receiving layer.
5-20 parts by weight are preferred. If the addition amount is not satisfied, problems such as thermal fusion between the thermal transfer sheet and the receptor layer or reduction in printing sensitivity may occur.

Further, in order to impart an antistatic function, the following antistatic agents can be kneaded into the coating liquid for the receiving layer. This kneading can be carried out also in an electrophotographic receiving layer coating solution. Antistatic agents; fatty acid esters, sulfates, phosphates, amides, quaternary ammonium salts, betaines,
Amino acids, acrylic resins, ethylene oxide adducts, etc. The addition amount of the antistatic agent is 0.1 to
2.0% by weight is preferred. The method for forming the receptor layer for the melt transfer recording and the sublimation transfer recording may be the same as that for the above-mentioned receptor layer for electrophotographic copying. The thickness of the receiving layer for the melt transfer recording and the sublimation transfer recording is usually 0.1 to 10 μm when dried.
It is.

(Primer Layer) For the purpose of stabilizing the adhesion between the substrate and the receiving layer, a primer layer may be provided between the receiving layer and the substrate. The material constituting the primer layer can be selected from ordinary materials such as linear polyester and isocyanate.

(Back Layer) A back layer can be provided on the back surface of the substrate where no receiving layer of the substrate is provided. The back surface layer is provided to the image receiving sheet so as to have an appropriate sliding property for transport by a printer and also to prevent curling. The back surface layer is composed of, for example, a binder resin, organic or inorganic fine particles, and an antistatic agent. As the binder resin, the binder resin described in the receiving layer can be used in the same manner, and the antistatic agent described in the receiving layer can be used in the same manner. Further, as organic or inorganic fine particles,
Considered so as not to impair the transparency of the image receiving sheet, for example, inorganic fine particles such as silica, talc, alumina, calcium carbonate, Teflon fine particles, crosslinked urea resin fine particles, styrene / acrylic resin fine particles, melamine resin,
A material having a refractive index close to that of the binder of the back layer, such as an organic filler such as a polycarbonate resin, is selected.

(Intermediate Layer) In the present invention, an intermediate layer composed of various resins may be provided between the base sheet and the receiving layer. By making such intermediate layers play various roles, excellent functions can be added to the image receiving sheet.
As an example, as a resin that imparts cushioning properties, a resin having large elastic deformation or plastic deformation, for example, a polyolefin resin, a vinyl copolymer resin, a polyurethane resin, a polyamide resin, or the like, is used to form an image receiving sheet. Sensitivity can be improved, and roughness of an image can be prevented. In addition, when an intermediate layer is provided using a resin having a glass transition temperature of 60 ° C. or higher, or a resin cured with a curing agent or the like, the sheets adhere to each other when a plurality of image receiving sheets are stacked and stored. For example, the storage performance of the image receiving sheet can be improved, for example, by preventing the image receiving sheet from being lost.

For the intermediate layer, the above-mentioned resin and additives are optionally added, and the mixture is sufficiently kneaded with a solvent, a diluent or the like to produce a coating liquid, which is then placed on a substrate sheet. Like the layer forming means, for example, gravure printing, screen printing,
An intermediate layer is formed by applying and drying by forming means such as a reverse roll coating method using a gravure plate.

(Detection Mark) The image receiving sheet of the present invention is provided with a detection mark. The detection mark is an opaque mark formed by applying a resin varnish comprising a resin, a good solvent having a low boiling point, and a poor solvent having a high boiling point. The detection mark is made transparent by heating and pressing. The detection mark is a porous opaque layer before it is used in electrophotographic copiers (printers) or thermal transfer printers, but when images are formed by those printers, it is transparent due to heat and pressure during heating and fixing. It becomes something.

When a resin and a transparent resin varnish containing a good solvent having a low boiling point and a poor solvent having a high boiling point are applied to an image receiving sheet and then dried, the good solvent having a relatively low boiling point evaporates preferentially. . With the progress of the evaporation of the good solvent, the resin phase in the resin varnish and the remaining poor solvent phase undergo phase separation, and the resin gels, while the poor solvent takes the form of particles dispersed in the resin. . As the drying proceeds further, the evaporation of the high boiling point poor solvent in the form of particles proceeds, and an opaque porous resin layer is formed by the completion of the evaporation of the poor solvent. The opaque porous resin layer formed in this way is made transparent by melting the resin by heat during recording or heat treatment after recording.

In the detection mark of the opaque porous resin layer, the resin used is preferably an acrylic resin, a polyester resin, or a vinyl chloride-vinyl acetate copolymer resin, and particularly preferably a vinyl chloride-vinyl acetate copolymer resin. preferable. These resins preferably have a melting point of 30 ° C. or higher and 150 ° C. or lower, particularly in the range of 50 ° C. to 130 ° C. If the melting point exceeds 150 ° C., it is difficult to be transparent by heating and pressurizing, and if the heating temperature is increased, disadvantages such as thermal deformation of the substrate occur, which is not preferable. If the temperature is lower than 30 ° C., it is not preferable from the viewpoint of storage stability. These resins can be used alone or in combination of two or more.

With respect to the above resins, the poor solvent is a solvent having no solubility or low solubility in the resin, and specifically, an aliphatic hydrocarbon, an aromatic hydrocarbon, a terpene-based hydrocarbon. Hydrocarbon solvents such as hydrogen, halogenated hydrocarbons,
There are alcohols. In addition, for the above resin, a good solvent is a solvent having high solubility in the resin, specifically, for a solvent-soluble resin, acetone, methyl ethyl ketone, ketones such as cyclohexane, ethyl acetate,
Esters such as butyl acetate and ethylene glycol monomethyl ether, or aromatic hydrocarbons and alcohols depending on the resin. When a water-soluble resin is used, a poor solvent for the solvent-soluble resin becomes a good solvent, and the solvent is appropriately used depending on the compatibility with the resin so that the good solvent becomes a poor solvent. The poor solvent is generally resin 10
It is used in the range of 10 to 200 parts by weight with respect to 0 parts by weight. With respect to the above-mentioned good solvent and poor solvent, as understood from the above-mentioned detection mark manufacturing process, the boiling point of the poor solvent must be relatively higher than the boiling point of the good solvent. Also, from the viewpoint of stable dispersion in the resin varnish,
It is preferable to use a combination of a good solvent and a poor solvent that are mutually soluble. Here, in the present invention, a good solvent having a low boiling point and a poor solvent having a high boiling point have a high boiling point and a low point has a relative relationship between a good solvent and a poor solvent.

In the above detection mark, a granular lubricant may be further contained in the resin varnish. By using this lubricant, evaporation of the solvent during drying of the resin varnish is promoted, and the productivity of detection marks is improved. The use of the lubricant also has the effect of improving the film strength of the detection mark as a print film and improving the scratch resistance. As the lubricant, the particle size is 0.5 to 20.
Organic particles having a particle size of μm are preferred. For example, petroleum wax as an aliphatic hydrocarbon, synthetic paraffin, polyethylene wax or montan wax, higher fatty acid and its metal salt, partic acid, stearic acid and its aluminum salt, tin salt, zinc salt, aliphatic alcohol, fat Amides such as n-butyl stearate, n-hexyl stearate, n-hexyl stearate, octyl stearate and amide stearic acid, amide palmitate, amide ethylenebispalmitate, and granular particles of wax such as carnauba wax are preferably used. You. The amount of the lubricant to be used is generally 0.5 to 30 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the resin.

The porous resin layer as a detection mark has a thickness of 0.1 μm.
It preferably has an average pore size of 1 to 10 μm. If the average pore diameter is smaller than 0.1 μm, good opacity (white state) cannot be obtained, and the function as a detection mark is insufficient. On the other hand, when it is larger than 10 μm, the film strength becomes weak. The pore diameter of the porous resin layer is controlled within the above range by optimizing the drying temperature, the amount of drying air, the drying time, and particularly, the mixing ratio of the poor solvent and the good solvent. For example, by setting the difference in boiling point between a good solvent having a low boiling point and a poor solvent having a high boiling point to be about 20 to 50 ° C., the size of the particle size can be secured. For example, in the case of an electrophotographic copying machine, the formed detection mark is made transparent by melting and re-solidifying a resin component by heat (100 to 150 ° C.) of a heat roll for fixing toner on an image receiving sheet during image formation. Is what you do. The detection mark of the porous resin layer of the present invention,
The transmittance in the wavelength region of 400 to 1000 nm is 50% or less before printing and 75% or more after printing, and the reflectance is 20% or more before printing and 10% or less after printing.

The detection mark of the present invention can be provided in a limited part of the image receiving sheet or in a patterned form. That is, the detection mark is provided on a limited portion such as one end or the periphery of the image receiving sheet. In addition, if the detection mark is slightly visible when used in an OHP projector or the like, it is preferable to provide the detection mark in a portion other than the image forming portion if it is obstructive. Further, the detection mark of the present invention may be patterned. The patterning includes, for example, shapes such as stripes, circles, ellipses, triangles, and barcodes whose sizes are defined. Further, the detection mark of the present invention, in an image receiving sheet provided with a receiving layer on a substrate,
A detection mark can be provided on at least one surface, on the receiving layer side or the back surface side of the substrate, on the substrate itself or on the outermost surface of the image receiving sheet. That is, a detection mark can be provided by printing on one or both surfaces of the substrate, on the receiving layer side or the back surface, on the substrate itself, or on the outermost surface of the image receiving sheet. The detection mark is printed, dried, and formed on one or both surfaces of the image receiving sheet by a known printing means such as a gravure printing method, a screen printing method, and letterpress printing.

(Resin Layer Not Porous) The image receiving sheet of the present invention is provided with one or more resin layers which are not porous on the detection mark. When the detection mark is a solvent-soluble resin, without dissolving the detection mark layer, the resin layer functions to smooth irregularities on the surface of the detection mark layer, and the resin layer is an aqueous solvent, for example, water, methanol, It is composed of a resin that dissolves or disperses in a water-soluble organic solvent such as ethanol, isopropyl alcohol, and normal propyl alcohol. This is because organic solvents such as ketones such as acetone and methyl ethyl ketone and esters such as ethyl acetate that dissolve the detection mark layer are not used in the coating liquid for the resin layer. If a water-soluble resin is used for the detection mark, the relationship between the good solvent and the poor solvent is reversed from the above, so that the resin layer uses a solvent-soluble resin and does not dissolve the detection mark surface. be able to.

The non-porous resin layer is mainly composed of an ion-conductive resin. As the ion conductive resin,
If it is an ion conductive resin having antistatic performance, there is no particular limitation as long as it has adhesiveness to the detection mark layer, and if it is transparent for OHP applications. Preferably, a cation-modified acrylic resin is suitable. An example of the cation-modified acrylic resin is an acrylic resin having a quaternary ammonium base. In addition, a resin layer that is not a porous body includes a binder having good adhesion to the detection mark layer and a fourth antistatic agent, for example,
Quaternary ammonium salts, cationic antistatic agents such as polyamine derivatives, anionic antistatic agents such as alkyl phosphates, nonionic antistatic agents such as fatty acid esters, and π
It can also be formed using a conductive polymer material having an electron conjugated structure. However, in the case where the antistatic agent is used alone, it may be formed without a binder.

Examples of the binder having good adhesion to the detection mark layer include polyester resins and
Polyurethane resin, polyacrylic resin, polyvinyl formal resin, epoxy resin, polyvinyl butyral resin, polyamide resin, polyether resin,
Polystyrene-based resins, styrene-acrylic copolymer-based resins and the like, among which water-soluble or water-dispersible polyester resin having a carboxyl group, π
It is particularly preferable in terms of compatibility with a sulfonated polyaniline which is a conductive polymer material having an electron conjugated structure. For example, Polyester WR from Nippon Synthetic Chemical Industry Co., Ltd.
It can be obtained under a trade name such as -961 and used in the present invention.

Examples of the conductive polymer material having a π-electron conjugated structure used as an antistatic agent include, for example, sulfonated polyaniline, chemically doped polyacetylene, polyparaphenylenevinylene, polyparaphenylene sulfide Heat-treated products of chemically polymerized and doped polypyrrole, polythiophene, polyaniline, phenolic resin produced by heat treatment, heat-treated polyamide, and heat-treated perylene anhydride. The sulfonated polyaniline is soluble in a solvent containing water or alkaline water, and dissolves by forming an internal salt or an alkaline salt. These sulfonated polyanilines are available, for example, from Nitto Chemical Industry Co., Ltd.
It can be used in the present invention by obtaining it under the trade name of -01Z and as a solution of an aqueous solution or a mixed solvent of water and an organic solvent. These solutions are yellowish solutions, but are almost colorless when the concentration is low, and the transparency of the image receiving sheet is required for applications such as OHP sheets for observing recorded images with transmitted light. But can be used without any problems.

As described above, the non-porous resin layer contains a binder resin having an antistatic property as a resin having an antistatic property, and a resin of an antistatic agent as an additive. In the image receiving sheet of the present invention, the surface electric resistance value of the resin layer which is not a porous body is preferably in the range of 10 ⁸ to 10 ¹⁵ Ω / sq. It is good and has excellent image quality, and also has good transport suitability in electrophotographic copying machines and printers. The resin layer, that is, the surface resistance value of the front surface of the image receiving sheet, that is, the sheet resistance, is the thickness of each of the receiving layer, the coating layer of the resin layer and the base material, and the ratio of the resin having the antistatic property of the resin layer. The desired sheet resistance can be controlled by the mixing ratio of the water, the organic solvent, and the surfactant in the resin layer. For example, if the thickness of the resin layer is increased, the sheet resistance decreases.

The surface resistance of the front surface of the image receiving sheet is 1 ×
If it is lower than 10 ⁸ Ω / sq, image defects (image loss) tend to occur. Conversely, if it exceeds 1 × 10 ¹⁵ Ω / sq, image defects (insufficient density), static electricity and insufficient lubrication will cause electrophotographic copying machines. Poor transport is likely to occur in the printer. The non-porous resin layer is formed by using the above-mentioned binder, antistatic agent and the like, and as a forming method, an aqueous solvent such as water or a water-soluble solvent such as methanol, ethanol, isopropyl alcohol and normal propyl alcohol is used. A coating solution is prepared by dissolving or dispersing the binder, antistatic agent, and the like in an organic solvent. An optional additive such as a surfactant or an antifoaming agent for suppressing bubbles may be added to the coating liquid to improve the wettability of the substrate during coating. In particular, a phosphate ester-based surfactant is preferably used as the surfactant. However, since the resin layer needs to have a uniform structure instead of a porous structure, a coating solution in which a binder, an antistatic agent, and the like are dissolved in the above aqueous solvent is preferable.

The non-porous resin layer is formed by applying the coating liquid on the detection marks of the image receiving sheet in a pattern such that the entire surface of the image receiving sheet or at least the detection marks are covered.
For example, it is performed by coating and drying by a conventional coating method such as a gravure coater, a roll coater, and a wire bar.
The coating amount of the resin layer is about 0.05 to
1.0 μm, preferably in the range of 0.1 to 0.5 μm, and if the coating amount is less than the above range, the smoothing of unevenness on the surface of the detection mark is insufficient, while the coating amount is in the above range. Even if it is larger, the above performance is not improved in proportion to the thickness, which is not only economically disadvantageous but also undesirably lowers the density of an electrophotographic image.

[0039]

Next, the present invention will be described in detail with reference to examples. In the following description, parts or% are based on weight unless otherwise specified. Example 1 A receiving layer having the following composition was applied to one surface of a 75 μm-thick polyethylene terephthalate film substrate by a reverse roll coating method using a gravure plate so that the thickness became 3 μm in a dry state. did. Further, on the receiving layer, a detection mark was provided at a corner position of the image receiving sheet by gravure printing using a coating liquid 1 for a detection mark having the following composition so that the thickness became 2 μm in a dry state. . Further, on the detection mark, one layer of a coating liquid 1 for a resin layer which is not a porous material having the following composition and a reverse roll using a gravure plate on the entire surface not only on the detection mark but also on the receiving layer. The coating was applied by a coating method so as to have a thickness of 1 μm in a dry state, whereby an image receiving sheet of Example 1 was produced.

Receiving layer composition Vinyl chloride-vinyl acetate copolymer 6 parts (Dencarak # 1000A, manufactured by Denki Kagaku Kogyo Co., Ltd.) Polyester resin (Byron 600, manufactured by Toyobo Co., Ltd.) 4 parts Methyl ethyl ketone / toluene = 1/1 90 parts

Coating solution for detection mark 1 Vinyl chloride-vinyl acetate copolymer 30 parts (Denkalac TF100 manufactured by Denki Kagaku Kogyo KK: solid content 60%) Acetone 30 parts Propanol 40 parts

Coating liquid for resin layer 1 50 parts of cationic acrylic resin (PQ50B manufactured by Soken Chemical Industry Co., Ltd.) 50 parts of isopropyl alcohol

Example 2 The image receiving sheet of Example 2 was prepared in the same manner as in Example 1 except that the resin layer coating liquid 1 used in Example 1 was changed to a resin layer coating liquid 2 having the following composition. Produced. Coating liquid for resin layer 2 Cationic acrylic resin 50 parts (Safomer ST2100 manufactured by Mitsubishi Chemical Corporation) Isopropyl alcohol 50 parts

Example 3 The image receiving sheet of Example 3 was prepared in the same manner as in Example 1 except that the resin layer coating liquid 1 used in Example 1 was changed to a resin layer coating liquid 3 having the following composition. Produced. Coating liquid for resin layer 3 Polyamide resin (polyamide manufactured by Henkel Hakusui Co., Ltd.) 10 parts Isopropyl alcohol 90 parts

Comparative Example 1 The image receiving sheet of Comparative Example 1 was prepared in the same manner as in Example 1 except that the resin layer coating liquid 1 used in Example 1 was changed to a resin layer coating liquid 4 having the following composition. Produced. Coating liquid for resin layer 4 Vinyl chloride-vinyl acetate copolymer 10 parts (Denkalac # 1000A manufactured by Denki Kagaku Kogyo Co., Ltd.) 90 parts of methyl ethyl ketone

Comparative Example 2 An image receiving sheet of Comparative Example 2 was produced in the same manner as in Example 1 except that the resin layer of the image receiving sheet produced in Example 1 was not provided.

Using the image receiving sheets of the above Examples and Comparative Examples, the transmittance and reflectance of near infrared rays of 950 nm at the detection mark portion before image formation were measured. The measuring device is
A spectrophotometer UV-3100 manufactured by Shimadzu Corporation was used.
Further, using the image receiving sheets of the above Examples and Comparative Examples,
Electrophotographic copier (COLOR LA manufactured by Canon Inc.)
SER COPIER 700), a fixed image is formed, and the haze (cloudiness) of the detection mark portion after image formation is formed.
Is measured. As a measuring device, a haze meter manufactured by Nippon Denshoku Industries Co., Ltd. was used.

(Evaluation Results) Table 1 shows the evaluation results of the examples and comparative examples.

[Table 1]

The image receiving sheets of Examples 1 to 3 have a low transmittance of 4.5% at the detection mark portion before image formation, have excellent detection performance, have a low haze after image formation, and have a low haze even after being subjected to an OHP projector. Marks are inconspicuous. In contrast, Comparative Example 1
The image receiving sheet had a very high transmittance of 60.0% at the detection mark portion before image formation, and could not be read by the detection sensor of the electrophotographic copying machine, and no image was formed. that is,
In the image receiving sheet of Comparative Example 1, when a resin layer using an organic solvent of methyl ethyl ketone is provided on the detection mark, the organic solvent dissolves the detection mark and crushes the porous structure to form a uniform layer. Because it has been made transparent. Further, the image receiving sheet of Comparative Example 2 has a low transmittance of 4.0% at the detection mark portion before image formation and is excellent in detection performance, but has a high haze after image formation, and therefore, when used with an OHP projector. , The mark was conspicuous and obtrusive. that is,
Since the image receiving sheet of Comparative Example 2 does not have a resin layer that is not a porous body on the detection mark, it is difficult to smooth the unevenness of the surface of the detection mark when forming an image by high-speed processing. Is shown.

[0050]

According to the image receiving sheet of the present invention, the detection mark allows the optical detection at the time of image formation to be performed normally, and the detection mark of the porous body is melted by heat and pressure at the time of fixing in high-speed processing. Crush the porosity to make it a uniform layer and make it transparent.
While maintaining the opacity of the detection mark before image formation, the unevenness of the detection mark surface is covered with a non-porous resin layer, so that the detection mark surface after image formation is smooth and the detection mark Be transparent. Therefore, when the image receiving sheet of the present invention forms an image with a copying machine or a printer of a high-speed processing electrophotographic system or thermal transfer system, the detection mark is erased inconspicuously by heating and pressurizing during the image forming. be able to.

Claims (5)

[Claims] An image receiving sheet having an opaque porous detection mark formed by applying a resin varnish comprising a resin, a good solvent having a low boiling point, and a poor solvent having a high boiling point. An image receiving sheet, wherein at least one resin layer which is not a base material is provided, and the detection mark is made transparent by heating. 2. In an image receiving sheet provided with a receiving layer on a substrate, on the receiving layer side or the back side of the substrate, on the substrate itself or on the outermost surface of the image receiving sheet, on at least one surface, The image receiving sheet according to claim 1, wherein the image receiving sheet has the detection mark. 3. The image receiving sheet according to claim 1, wherein the solvent of the coating liquid for the non-porous resin layer does not dissolve the opaque detection mark of the porous body. 4. The image receiving sheet according to claim 1, wherein the non-porous resin layer contains a resin having an antistatic property. 5. The image receiving sheet according to claim 4, wherein the non-porous resin layer has a surface electric resistance of 10 ⁸ to 10 ¹⁵ Ω / sq.