JPH0756376A - Image receiving sheet - Google Patents

Abstract

PURPOSE:To obtain an image receiving sheet having a detection mark which changes into transparent by heating, by applying a resin varnish containing a resin, good solvent having rather low boiling point, and poor solvent having rather high boiling point on an image receiving sheet and then drying to form an opaque porous resin layer. CONSTITUTION:A detection mark 3 is formed on a receiving layer 2 formed on the one surface of a base sheet 1. This detection mark is formed by the following method. First, a resin varnish containing a resin, good solvent having rather low boiling point, and poor solvent having rather high boiling point is applied and dried on the receiving layer or the back surface of an image receiving sheet. In the drying process, the good solvent having rather low boiling point is first vaporized, the resin phase and the poor solvent phase remaining in the resin varnish separate from each other. The resin is gelled, while the poor solvent is dispersed as a particle state in the resin. Further, as drying proceeds, vaporization of the poor solvent having high boiling point in a particle state proceeds and an opaque porous resin layer is formed.

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 OHP sheet for an electrophotographic copying machine.

[0002]

2. Description of the Related Art OHP is an information transmission method widely used at lectures, schools, and other information sessions. As a method of forming an image on this OHP sheet, there have been adopted methods of handwriting with oil-based ink or the like, printing, and an electrophotographic copying machine. In order to reliably record and hold record information such as lines, characters, and images on the OHP sheet by using these means, what is generally used as the OHP sheet has a structure in which a receiving layer is formed on a transparent base material. Has become.
Therefore, the receiving layer surface of the OHP sheet to be recorded is
Must be positively identified. Therefore, a detection mark for identifying the receiving layer side, that is, the front and back of the OHP sheet is displayed on the sheet surface by, for example, a white arrow. This display has a function of mechanically distinguishing the OHP sheet from other paper such as plain paper. In addition, some electrophotographic copying machines operate by detecting the sheet transport position in the machine during copying, and therefore an OHP sheet provided with a white detection mark may be required.

The above-mentioned detection mark is unnecessary after the image is formed. Rather, since the detection mark is present even after the image is formed, the detection mark is also projected together with the image required when used in the OHP device. Since unnecessary things are mixed on the surface,
From the standpoint of viewing the projected image, there was the problem that obstructive things were visible and unsightly. In view of the above problems relating to the detection mark, Japanese Patent Laid-Open No. 3-170944 discloses an OHP sheet detection mark composed of an opaque porous resin layer which becomes transparent when heated during image formation. As a method for obtaining the porous resin layer, (1) a method of mixing a foaming agent at the time of applying a hydrophobic resin such as polystyrene resin, polyester resin or the like on the base material sheet and then applying the foaming agent, and (2) A method has been proposed in which the hydrophobic resin is applied onto a substrate sheet together with an extractable resin or solvent and then made porous by extraction with water or solvent. However, according to the study by the present inventors, the opacity of the detection mark is low in the above method (1), and the opacity of the detection mark due to heating is insufficient. The process requires a considerable amount of time, a large amount of extractant is required, and there is a problem that the extraction solvent may be contaminated by the extraction resin.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image-receiving sheet having a detection mark which becomes transparent when heated without the drawbacks of the prior art.

[0005]

In order to achieve the above object, the present invention provides an image-receiving sheet comprising a base sheet, a receiving layer and an opaque porous resin layer as a detection mark which becomes transparent by heating. The opaque porous resin layer is obtained by applying a resin varnish containing a resin, a good solvent having a relatively low boiling point and a poor solvent having a relatively high boiling point to the image receiving sheet, and then drying it. The image receiving sheet is characterized by The resin in the resin varnish is selected from the group consisting of acrylic resins, polyester resins, vinyl chloride-vinyl acetate copolymer resins and mixtures thereof. The amount of poor solvent used is resin 1
It is 10 to 70 parts by weight with respect to 00 parts by weight. Further, the resin varnish contains a granular lubricant. The average pore diameter of the opaque porous resin layer is 0, 05 to 2 μm.

[0006]

When the transparent resin varnish containing a resin, a good solvent having a relatively low boiling point and a poor solvent having a relatively high boiling point is applied onto the receiving layer or the back surface of the image receiving sheet and then dried, the boiling point is relatively low. The good solvent evaporates preferentially. With the progress of evaporation of the good solvent, the resin phase in the resin varnish and the remaining poor solvent phase are phase-separated, and the resin is gelated, while the poor solvent takes the form of particles dispersed in the resin. . As the drying progresses further, the evaporation of the high boiling poor solvent in the form of particles proceeds,
When the evaporation of the poor solvent is completed, an opaque porous resin layer is formed. The opaque porous resin layer formed by the above-mentioned method is one in which the resin is melted and becomes transparent due to heat during recording or heat treatment after recording.

[0007]

Preferred Embodiments A sectional view of a preferred example of the image-receiving sheet of the present invention is shown in FIGS. FIG. 1 shows a basic structure of an image receiving sheet of the present invention, in which a receiving layer 2 is provided on one surface of a base material sheet 1 and a detection mark 3 is provided thereon. FIG. 2 is an application example of the image-receiving sheet of the present invention, in which the receiving layer 2 is provided on one surface of the base material sheet 1 via the primer layer 4, and the back surface layer 5 is provided on the other surface of the base material sheet 1.
The detection mark 3 is provided via the.

As the base sheet, polypropylene, polyvinyl chloride, polyethylene terephthalate, polymethacrylate, polycarbonate, cellulose triacetate,
A stretched or unstretched transparent film or sheet of various plastics such as cellulose diacetate, polyamide, ethylene-vinyl acetate copolymer and its saponified product, polyarylate, polyether sulfone, etc. is used. The thickness of the base material sheet is appropriately determined depending on the recording means, required strength, etc., but the thickness is usually 50 to 300 μm.

The receiving layer provided on the transparent substrate is formed directly on the substrate sheet or via a primer layer. Examples of the resin forming the receiving layer include polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl resins such as polyacrylic acid ester and polystyrene, and polyethylene terephthalate. Polyester resins such as polybutylene terephthalate, 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. Preferably, vinyl resin and polyester resin are used. Further, a resin dyed with a sublimation dye, a resin that receives a heat-meltable ink, or the like can be used. As these resins, those having a melting point of 30 ° C. or higher and 200 ° C. or lower are used. Those having a melting point of 30 ° C. or lower are not preferable in terms of storage stability. Those having a melting point of 200 ° C. or higher are not preferable because they require a large amount of energy during image formation. The receiving layer is a composition prepared by further adding various auxiliaries to the above resin as necessary and dissolving or dispersing them in a suitable solvent,
It is formed by coating and drying on a substrate by a known method.
The thickness of this receiving layer is usually 1 to 20 μm. A primer layer may be provided between the receiving layer and the base sheet for the purpose of stabilizing the adhesion between the base sheet and the resin forming the receiving layer. The material forming the primer layer can be selected from ordinary materials such as linear polyester and isocyanate.

For the purpose of preventing contamination of the image-receiving sheet by dust, an antistatic layer containing the following surfactant may be provided on the receiving layer surface or the back surface of the substrate. When the antistatic layer is provided on the back surface of the base material as a back surface layer, it may be formed of the same resin as the surface of the receiving layer in order to prevent curling of the sheet. As the antistatic agent, if it is dispersible at the time of forming the receiving layer, conventionally known cations, anions, amphoteric ions,
Any nonionic antistatic agent can be used. Examples thereof include cationic antistatic agents such as quaternary ammonium salts and polyamine derivatives, anionic antistatic agents such as alkyl phosphates, and nonionic antistatic agents such as fatty acid esters. Further, when the antistatic layer is provided on the outermost layer of the base material sheet, slippage during heat fixing and stability of conveyance may be provided by incorporating a lubricant.

In order to prevent double feeding due to blocking that occurs when the image-receiving sheet is supplied to the printer, and to prevent defective conveyance inside the printer, inorganic or organic fine particles may be added to the receiving layer or the backside layer. it can. These fine particles are designed so as not to impair the transparency of the sheet. For example, inorganic fine particles such as silica, talc, alumina and calcium carbonate, Teflon fine particles, crosslinked urea resin fine particles, styrene / acrylic resin fine particles. A material having a refractive index close to that of the binder of the receiving layer or the back surface layer such as an organic filler such as melamine resin or polycarbonate is selected.

The detection mark of the present invention is obtained as an opaque porous resin layer by coating a resin varnish containing a resin, a good solvent and a poor solvent on an image receiving sheet (on the receiving layer or on the back side) and then drying.

To form the detection mark of the present invention, first,
A transparent resin varnish comprising a good solvent having a relatively low boiling point and a poor solvent having a relatively high boiling point is coated on or on the receiving layer of the image receiving sheet. The application of the resin varnish can be performed by a general coating method such as gravure coating and silk screen coating, generally to a thickness of 0.5 to 10 μm. Next, the coated resin varnish is dried. In this drying step, the good solvent having a relatively low boiling point evaporates first. With the progress of evaporation of this good solvent, the resin phase in the resin varnish and the remaining poor solvent phase undergo phase separation,
The resin gels, while the poor solvent takes the form of particles dispersed in the resin. As the drying progresses further, the evaporation of the high boiling point poor solvent in the form of particles proceeds, and a porous opaque resin layer is formed by the completion of the evaporation of the poor solvent.

In the above process, the drying may be carried out in one step, but first, low temperature drying is performed to complete the evaporation of only the good solvent having a relatively low boiling point, and then high temperature drying is performed to evaporate the residual poor solvent. It is preferable to carry out a two-step drying in which Drying conditions vary depending on the resin used, the type of good solvent and poor solvent, the desired pore size, etc., but in general,
In the case of one-step drying, the temperature is 80 to 100 ° C. for 3 to 10 seconds,
In the case of two-step drying, first, low-temperature drying is performed at 10 to 30 ° C.
High temperature drying for 1 to 5 at 80 to 120 ° C for 0 to 5 to 5 seconds.
It is preferable to carry out for 2 seconds. In addition, it is preferable that the low temperature drying in the two-step drying is performed under no wind.

The resin used for producing the detection mark according to the present invention is preferably an acrylic resin, a polyester resin and a vinyl chloride-vinyl acetate copolymer resin, and particularly preferably a vinyl chloride-vinyl acetate copolymer resin. These resins have melting points of 30 ° C or higher and 150 ° C or lower, especially 5
It is preferably in the range of 0 ° C to 130 ° C. Melting point 150
When the temperature is higher than 0 ° C., when the porous resin layer is melted during image formation (toner fixing), the base material may be thermally deformed, which is disadvantageous. Use of one having a temperature of 30 ° C. or lower is not preferable in terms of storage stability. These resins can be used alone
A mixture of two or more species can also be used.

The poor solvent for the above-mentioned resin is a solvent which is insoluble or has low solubility in the resin, specifically, aliphatic hydrocarbons, aromatic hydrocarbons, terpene-based hydrocarbons and the like. There are hydrocarbon solvents, halogenated hydrocarbons and alcohols. Further, for the above resin, a good solvent is
A solvent that has high solubility in resin, specifically,
For solvent-soluble resins, ketones such as acetone, methyl ethyl ketone, and cyclohexane, esters such as ethyl acetate, butyl acetate, and ethylene glycol monomethyl ether, or, depending on the resin, aromatic hydrocarbons and alcohols are applicable. . When a water-soluble resin is used, the poor solvent for the solvent-soluble resin becomes a good solvent, and the good 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 used in an amount of 10 to 70 parts by weight based on 100 parts by weight of the resin. Regarding the good solvent and the poor solvent, as will be understood from the above-described detection mark manufacturing process, the boiling point of the poor solvent must be relatively higher than the boiling point of the good solvent. 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 which are mutually soluble.

In the detection mark of the present invention, the resin varnish may further contain a granular lubricant. The use of this lubricant accelerates the evaporation of the solvent during the drying of the resin varnish and improves the productivity of the detection mark. Further, the use of this lubricant also has the effect of improving the film strength of the detection mark as a printed film and improving scratch resistance. As a lubricant, the particle size is 0.5 to 20μ.
m granular organic type is preferable. For example, petroleum wax which is an aliphatic hydrocarbon, synthetic paraffin, polyethylene wax and montan wax, higher fatty acid and its metallic salt, partic acid, stearic acid and its aluminum salt, tin salt, zinc salt, aliphatic alcohol, fat The granular esters such as n-butyl stearate, n-hexyl stearate, octyl stearate, amide stearate, amide palmitate, amide ethylene bispalmitate, and waxes such as carnauba wax are preferably used. The amount of lubricant used is generally 0.5 to 30 parts by weight, preferably 1 to 5 parts by weight, based on the resin.

The porous resin layer as the detection mark has a thickness of 0.
It is preferable to have an average pore size of 05 to 2 μm. If the average pore size is smaller than 0.05 μm, good opacity (whitening state) cannot be obtained, and the function as a detection mark is insufficient. If it is larger than 2 μm, the film strength becomes weak. The control of the pore diameter of the porous resin layer within the above range is performed by optimizing the drying temperature, the amount of drying air, the drying time, and the mixing ratio of the poor solvent and the good solvent. The formed detection mark is the heat of the heat roll (100 to 1) that fixes the toner on the image receiving sheet during image formation by the electrophotographic copying machine.
At 50 ° C.), the resin component is melted and re-solidified to be transparent.

The detection mark according to the present invention is 400 to 10
The transmittance in the wavelength region of 00 nm is 50% or less before printing, 75% or more after printing, and the reflectance is 20% before printing.
The above is 10% or less after printing. The detection mark can be provided on the receiving layer or on the back surface, and when forming the detection mark on the back surface, directly on the substrate sheet,
Alternatively, it can be provided on the antistatic layer (back surface layer) formed on the substrate sheet. The shape and number of the detection marks are not particularly limited, and they can be provided arbitrarily. The detection mark of the present invention is a pigment for sublimation transfer provided with a receiving layer for receiving a dye which is thermally transferred from a thermal transfer sheet provided with a dye layer containing a sublimation dye in a binder by heating with a thermal head. A thermal transfer sheet provided with a heat-melting ink layer containing a binder for heat-melting transfer provided with a receiving layer for receiving heat-melting ink to be thermally transferred by heating with a thermal head, water-soluble dye or the like as water, solvent It can also be used as an inkjet image-receiving sheet which is transferred by heating and pressing from a thermal transfer sheet provided with a transfer layer formed by melting.

[0020]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, parts and% are based on weight unless otherwise specified. Example 1 First, a transparent 100 μm thick polyethylene terephthalate (T-60, manufactured by Toray Industries, Inc.) was used as a base sheet, and a primer layer coating solution having the following composition was dried on a bar coater. A primer layer is formed by coating so that the coating amount becomes 1.0 g / m ^2, and a receiving layer coating solution having the following composition is applied thereon by a bar coater so that the coating amount is 5.0 g.
And forming a receiving layer was coated to a / m ^2. Furthermore,
A back surface layer coating solution having the following composition is applied to the back surface of the substrate sheet so that the coating amount when dried is 1 g / m ^2, and after forming the back surface layer, the detection mark ink A having the following composition is formed thereon. The gravure printer was used to print so that the coating amount when dried was ² to 3 g / m ^2, and the sheet was dried by drying at 80 ° C. for 5 seconds to provide a whitened detection mark, which was then sheeted and electrophotographic copying machine. An OHP sheet for use was obtained. Coating liquid for primer layer Polyester polyol Adcoat (manufactured by Toyo Morton Co., Ltd.) 15 parts Methyl ethyl ketone: toluene = 2: 1 85 parts Coating liquid for receiving layer Polyester resin (Byron 600 manufactured by Toyobo Co., Ltd.) 4 parts Vinyl chloride-vinyl acetate Polymer 6 parts (Dencarac # 1000A manufactured by Denki Kagaku Kogyo Co., Ltd.) Methyl ethyl ketone: toluene = 1: 1 90 parts Backside layer coating liquid Cationic acrylic resin Solid content 35% 65 parts (Saftomer No13 Mitsubishi Petrochemical Co., Ltd.) Antistatic agent (TB-34 manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.) 1 part Lubricant Teflon filler (particle size 7 μm) 2 parts (Lubron L-5 manufactured by Daikin Industries, Ltd.) Ethanol 32 parts Detection mark ink A Acrylic Resin (BR-85 manufactured by Mitsubishi Rayon Co., Ltd.) 20 parts Antistatic agent (TB-34 Matsumoto Oil and Fat Pharmaceutical Co., Ltd. 2 parts Lubricant Teflon filler (particle size 7 μm) 2 parts (Lubron L-5 Daikin Industries Co., Ltd.) Good solvent Methyl ethyl ketone: Toluene = 1: 1 56 parts Poor solvent Aliphatic hydrocarbon 20 parts (Isoper H Esso Oil Co., Ltd.)

Example 2 A detection mark ink B having the following composition was used.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark B Polyester resin (Byron 290 Toyobo Co., Ltd.) 20 parts Antistatic agent (TB-34 Matsumoto Yushi-Seiyaku Co., Ltd.) 2 parts Lubricant Teflon filler (particle size 7 μm) 2 parts (Lubron L-5) Daikin Industries, Ltd. Good solvent Methyl ethyl ketone: Toluene = 1: 1 56 parts Poor solvent Aliphatic hydrocarbon 20 parts (Isoper H Esso Oil Co., Ltd.)

Example 3 A detection mark ink C having the following composition was used.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark C Polyester resin (Byron 600, manufactured by Toyobo Co., Ltd.) 20 parts Antistatic agent (TB-34, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.) 2 parts Lubricant Teflon filler (particle size: 7 μm) 2 parts (Lubron L-5) Daikin Industries, Ltd. Good solvent Methyl ethyl ketone: Toluene = 1: 1 56 parts Poor solvent Aliphatic hydrocarbon 20 parts (Isoper H Esso Oil Co., Ltd.)

Example 4 The ink for the detection mark was the ink D for the detection mark having the following composition.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark D Acrylic resin (BR-85 manufactured by Mitsubishi Rayon Co., Ltd.) 11 parts Vinyl chloride-vinyl acetate copolymer Brushing resin A 5 parts Lubricant Carnauba wax CR-8 4 parts (particle size 5 μm Koyo Chemical Co., Ltd.) Good solvent Toluene 70 parts Poor solvent Aliphatic hydrocarbon 10 parts (ISOPAR H Esso Oil Co., Ltd.)

Example 5 Detection mark ink E was used as the detection mark ink E having the following composition.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark E Acrylic resin (BR-85 manufactured by Mitsubishi Rayon Co., Ltd.) 10 parts Vinyl chloride-vinyl acetate copolymer Brushing resin A 5 parts Lubricant Teflon filler (particle size 7 μm) 3 parts (Lubron L-5 Daikin Industries ( Good solvent Toluene 72 parts Poor solvent Aliphatic hydrocarbon 10 parts (Isoper H Esso Oil Co., Ltd.)

Example 6 The ink for the detection mark is the ink F for the detection mark having the following composition.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark F Acrylic resin (BR-85 manufactured by Mitsubishi Rayon Co., Ltd.) 10 parts Vinyl chloride-vinyl acetate copolymer Brushing resin A 5 parts Lubricant polyethylene wax AF-30 4 parts (particle size 10 μm Inktech Ink Co., Ltd.) Good solvent Toluene 73 parts Poor solvent Aliphatic hydrocarbons 8 parts (Isoper H Esso Oil Co., Ltd.)

Example 7 A detection mark ink G having the following composition was used.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark G Polyester resin (Byron 600 manufactured by Toyobo Co., Ltd.) 10 parts Vinyl chloride-vinyl acetate copolymer Brushing resin A 5 parts Lubricant Carnauba wax CR-8 3 parts (particle size 5 μm, manufactured by Koyo Chemical Co., Ltd.) Good solvent Toluene 72 parts Poor solvent Aliphatic hydrocarbons 10 parts (ISOPER H Esso Oil Co., Ltd.)

Example 8 A detection mark ink H having the following composition was used.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark H Vinyl chloride-vinyl acetate copolymer Brushing resin A 18 parts Lubricant Carnauba wax CR-8 5 parts (particle size 5 μm Koyo Chemical Co., Ltd.) Good solvent Acetone 42 parts Poor solvent n-butanol 35 parts

Example 9 The ink for detection mark was the ink I for detection mark having the following composition.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark I Vinyl chloride-vinyl acetate copolymer Brushing resin A 18 parts Lubricant Teflon filler (particle size 7 μm) 5 parts (Lubron L-5 Daikin Industries, Ltd.) Good solvent acetone 42 parts Poor solvent n-butanol 35 parts

Example 10 Ink for detection mark was used as ink J for detection mark having the following composition.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark J Vinyl chloride-vinyl acetate copolymer Brushing resin A 20 parts Acrylic resin (BR-83 Mitsubishi Rayon Co., Ltd.) 1.5 parts Good solvent toluene 8 parts Ethyl acetate 12 parts Methyl ethyl ketone 7.5 parts Acetone 17 Part poor solvent n-butanol 17 parts n-propanol 17 parts silica fine particles (average particle size 12 mμ) 0.1 part

Comparative Example 1 The ink for detection mark is the ink K for detection mark having the following composition.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark K Titanium oxide 20 parts Polyester resin (Byron 290 Toyobo Co., Ltd.) 20 parts Antistatic agent (TB-34 Matsumoto Yushi-Seiyaku Co., Ltd.) 2 parts Lubricant Teflon filler (particle size 7 μm) 2 parts ( Lubron L-5 Daikin Industries, Ltd. Good solvent Methyl ethyl ketone: toluene = 1: 1 56 parts

Comparative Example 2 A detection mark ink L was used as a detection mark ink L having the following composition.
An OHP sheet for an electrophotographic copying machine of the present invention was obtained in the same manner as in Example 1 except that the above was used. Ink for detection mark L Polyester resin (Byron 290 Toyobo Co., Ltd.) 20 parts Antistatic agent (TB-34 Matsumoto Yushi-Seiyaku Co., Ltd.) 2 parts Lubricant Teflon filler (particle size 7 μm) 2 parts (Lubron L-5) Daikin Industries, Ltd. Good solvent Methyl ethyl ketone: Toluene = 1: 1 61 parts

Evaluation Method For the OHP sheets obtained in the above Examples and Comparative Examples, an electrophotographic copying machine (Pixel CL manufactured by Canon Inc.) was used.
C-200) was used to form images on these sheets. Table 1 shows the results of measuring the transmittance and reflectance of near-infrared rays of 950 nm for the detection marks before and after copying with the following device. Measuring instrument Shimadzu Corporation spectrophotometer UV-310
0 Measurement wavelength λ = 950 nm Scan speed Very Slow Further, each sheet after copying was put on an overhead projector and the presence or absence of a detection mark on the projected image was observed.
As a result, in all the OHP sheets of the examples, no image of the detection mark was observed on the projected image, but in the case of the sheet of Comparative Example 1, the image of the detection mark was clearly observed. Further, in the case of the sheet of Comparative Example 2, as is clear from the data in Table 1, an opaque (whitened) resin layer capable of functioning as a detection mark was not obtained.

[0033]

[Table 1]

[0034]

INDUSTRIAL APPLICABILITY The detection mark of the present invention manufactured by a specific method is very excellent in its opacity and transparency due to heating during image formation. Also,
The detection mark can be manufactured by a simple process without requiring a complicated manufacturing process or a large amount of extraction solvent.

[Brief description of drawings]

FIG. 1 is a sectional view showing a basic structure of an image receiving sheet of the present invention.

FIG. 2 is a cross-sectional view showing an application example of the image receiving sheet of the present invention.

[Explanation of symbols]

 1. Base sheet 2. Receptive layer 3. Detection mark 4. Primer layer 5. Back layer

Claims (5)

[Claims] 1. An image receiving sheet comprising a base sheet, a receiving layer, and an opaque porous resin layer as a detection mark which becomes transparent by heating, wherein the opaque porous resin layer is a resin and is a good material having a relatively low boiling point. An image receiving sheet, which is obtained by applying a resin varnish containing a solvent and a poor solvent having a relatively high boiling point to the image receiving sheet and then drying it. 2. The resin in the resin varnish is an acrylic resin,
The image-receiving sheet according to claim 1, which is selected from the group consisting of polyester resins, vinyl chloride-vinyl acetate copolymer resins, and mixtures thereof. 3. The use amount of the poor solvent is 10 to 70 parts by weight based on 100 parts by weight of the resin.
The image-receiving sheet according to 2 above. 4. The image-receiving sheet according to claim 1, wherein the resin varnish further contains a granular lubricant. 5. The average pore diameter of the opaque porous resin layer is 0,
The image-receiving sheet according to claim 1, which has a thickness of 05 to 2 μm.