JPH01221276A - Pressure-sensitive copying sheet for prevention of falsification - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure-sensitive copying sheet, and more particularly to a tamper-proof pressure-sensitive copying sheet that cannot be tampered with by additional writing.

(Prior art) Combination of an electron-donating color former such as crystal violet lactone or benzoyl leucomethylene blue and an electron-accepting color developer such as activated clay, a phenol-formaldehyde condensate, or a polyvalent metal salt of an aromatic carboxylic acid. (leuco recording material), or carboxylic acid nickel salt and N,N
' - Color reaction of two types of chromogen substances, such as dibenzyl-dithiooxamide, a combination of a metal salt such as organoiron phosphate and stearyl gallate, and a ligand compound (chelate-based recording material) Pressure-sensitive copying sheets using

In general, such pressure-sensitive copying sheets include an upper paper (transfer sheet) in which a support is coated with microcapsules containing a chromogen substance prepared by a method such as a phase separation method, an interfacial polymerization method, or an 1n-situ method, and a A bottom sheet (receiving sheet) in which the support is coated with another chromogen substance that reacts with the original substance to develop color, and an inner sheet in which the microcapsules and the chromogen substance described above are coated on different sides of the support. They are used in combination as appropriate.

In addition, there is also a so-called self-coloring pressure-sensitive copying sheet in which the above-mentioned microcapsules and chromogen material are coated as a laminated or mixed layer on the same side of a support. There is a self-coloring type pressure-sensitive copying sheet set in which a microcapsule layer is provided on the sheet, and the above-mentioned bottom paper and inner paper are appropriately combined.

However, while these pressure-sensitive copy sheets are convenient for making copies easily, they do not allow you to write on or erase them using a writing instrument, other pressure-sensitive copy paper of the same color tone, eraser, correction ink, knife, etc. Since it can be easily tampered with, various troubles may occur depending on the application.

Conventionally, pressure-sensitive copying paper with a tamper-proofing function has a microcapsule coating layer (5) containing a chromogen substance on the back side of the top paper, inner paper, etc., and another layer containing a chromogen substance. There is one in which (6) is thinly laminated and the back side is self-coloring (Figure 2). As a result, a tamper-proof record (8) is formed on the back side of the top paper along with the receptor layer (7) by the pressure of the pen when writing on the surface of the top paper, so even if the characters written on the front surface are erased or rewritten, The back side cannot be rewritten,
Tampering can be prevented.

However, this type of pressure-sensitive copying paper is completely powerless against tampering by means of writing on it, and also has the disadvantage that the back side of the upper paper is easily stained by color development due to pressure from handling the sheet.

(Problems to be Solved by the Invention) An object of the present invention is to provide a pressure-sensitive copying sheet for preventing tampering, which cannot be tampered with by additional writing and which does not cause colored stains on the back surface during handling.

(Means for Solving the Problems) The present invention combines a transfer sheet (1) having microcapsules containing a chromogen substance and a receptor sheet (2) that develops color by reacting with the chromogen substance in the microcapsules. In the pressure-sensitive copying sheet configured with the receiving sheet (2),
A pigment coating layer (3) is provided on the support, and a pigment coating layer (3) is further provided on the support.
3) A receiving layer (4) is provided on the transfer sheet (1) by printing or coating a dispersion ink or a dispersion coating liquid of another chromogen substance that reacts with the chromogen substance of the transfer sheet (1) to develop color. A tamper-prevention device characterized in that a part of the receptor layer (4) is transferred to the back side of the opposing transfer sheet (1) due to recording pressure, and a tamper-proof record is obtained on the back side of the transfer sheet (1). It is a pressure-sensitive copy sheet.

(Function) FIG. 1 is a cross-sectional view illustrating the tamper-proof pressure-sensitive copying sheet of the present invention. When writing on the surface of the transfer sheet (1) with a ballpoint pen (9), etc., the chromogen substance in the microcapsules is transferred from the transfer sheet (1) to the receptor layer (4) due to the pressure of the writing, and the chromogen substance is transferred onto the receptor layer (4). A copy is available.

In the present invention, the receptor layer (4) is formed by printing or applying a dispersion ink or a dispersion coating liquid of another chromogen substance that causes a coloring reaction with the chromogen substance of the transfer sheet (1). The other chromogen substance in the dispersion type is less likely to penetrate into the pigment coating layer (3) than in the dispersion type, and the chromogen substance tends to remain on the surface.

Therefore, a part of the receptor layer (4) formed from the dispersion ink or the dispersion coating liquid is easily peeled off by the pressure of the pen and transferred to the back surface of the opposing transfer sheet (1). As a result, a tamper-proof record (1) 1 is obtained on the back side of the transfer sheet (1).

Since the transfer sheet (1) is stored separately from the receiving sheet (2) after being filled out, even if an additional entry is made on the front side of the transfer sheet (+1) for the purpose of tampering, the record on the back side cannot be added.

Therefore, falsification due to additional entries can be prevented.

Furthermore, the back side of the transfer sheet (1) does not become colored or smudged during handling.

It has been known to form a receptor layer on a support such as high-quality paper by printing or coating. However, there has never been a structure in which a part of the receptor layer is transferred to the back surface of the transfer sheet, and therefore the receptor layer has never been used to prevent tampering.

Examples of the combination of chromogen substances used in the present invention include a combination of an electron-donating color former and an electron-accepting color developer, or a combination of a metal salt and a ligand compound. Usually, the chromogen substance contained in the microcapsules of the transfer sheet (1) is an electron-donating color former or a ligand compound, and the other chromogen substance used in the receptor layer (4) is an electron-accepting developer. Colorants or metal salts.

Examples of the electron-donating coloring agent include the following substances known in the field of pressure-sensitive copying paper.

3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(p-dimethylaminophenyl')-3-(1,2-dimethylindol-3-yl)phthalide, 3. 3-bis(l,2-dimethylindol-3-yl)-5-dimethylaminophthalide, 3,
3-bis(9-ethylcarbazol-3-yl)-6-
triallylmethane dyes such as dimethylaminophthalide, 4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-herophenylleukoolamine,
Diphenylmethane dyes such as N-2,4,5-trichlorophenylleucoolamine, thiazine dyes such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran , spiro dyes such as 3-propyl-spiro-dibenzopyran, lactam dyes such as rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (0-chloroanilino) lactam, 3-dimethylamino-7 -Methylfluorane, 3-diethylamino-6-
Methyl-7-chlorofluorane, 3-(N-ethyl-p
-)luidino)-7-methylfluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-cybenzylaminofluorane, 3-(N
-ethyl-p-)luidino)-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-(N-cyclohexyl-N-methylamino)- 6-Methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7
-phenylaminofluorane, 3-diethylamino-6
-Fluoran dyes such as methyl-7-xylidinofluorane, and mixtures thereof.

Examples of the electron-accepting color developer include the following substances known in the field of pressure-sensitive copying paper.

Acid clay, activated clay, attapulgite, zeolite,
Clays such as bentonite, as well as phenol resins, polyvalent metal salts of various aromatic carboxylic acids as described in Japanese Patent Publication No. 51-25174, and 2,2'-bisphenolsulfone compounds as described in Japanese Patent Publication No. 54-106316. organic color developers such as zinc salts and mixtures thereof.

Examples of combinations of metal salts and ligand compounds include the following combinations of substances known in the field of pressure-sensitive copying paper.

Nickel stearate and N,N'-dibenzyludithioxamide, nickel laurate and α-benzylglyoxime, tricaprylmethylammonium vanadate and dodecylamine 8-hydroxyquinolinesulfonate, benzyllauryldimethylammonium molybdate. and lauryl protocatechuate, titanium stearate and lauryl gallate, iron naphthenate and benzyl gallate, polyferrophenylmethylsiloxane and methylenebis(8-oxyquinoline), copper palmitate and N,N'
-bis-2-octanoyloxyethyldiethyldithiooxamide, cobalt laurate and di-o-tolylguanidine, hinokitiol and polyvanadophenylmethylsiloxane, organic iron phosphate described in JP-A-58-38191 and lauryl gallate, etc., and mixtures thereof.

The pigment coating layer (3) used in the receptor sheet (2) in the present invention prevents the ink or coating liquid of the receptor layer (4) from penetrating into the support, resulting in an excellent colored image on the receptor layer. It gives The pigment coating layer (3) is made by coating a support with an aqueous coating solution containing a pigment, a binder, and, if necessary, a dispersant, a colored dye, an optical brightener, an ultraviolet absorber, an antioxidant, an antifoaming agent, etc. form.

In addition, when microcapsules containing oil are included in the pigment coating layer (3), the transfer of the receptor layer (4) is further promoted and an extremely clear colored image is formed on the back side of the transfer sheet (1), making it difficult to tamper with. This is a preferred embodiment of the present invention because it can be used for prevention. Microcapsules and oil will be described later.

Pigments include oxides, hydroxides, carbonates, sulfates, and halides of aluminum, zinc, magnesium, calcium, and titanium, as well as clays such as colloidal silica, zeolite, ben I night, kaolin, and calcined kaolin. , melamine resin, urea resin, and other organic pigments.

Binders used in preparing aqueous coating solutions include water-soluble binders and latex binders. Examples of water-soluble binders include gelatin, albumin,
Proteins such as casein, starches such as grain starch, pregelatinized starch, oxidized starch, etherified starch, and esterified starch, celluloses such as carboxymethyl cellulose and hydroxyethyl cellulose, and multi-tJIs such as agar, sodium alginate, and gum arabic. Water-soluble natural polymer compounds such as
There are water-soluble synthetic polymer compounds such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, maleic acid copolymer, etc.5, and latex binders include styrene-butadiene latex, acrylonitrile-butadiene latex, and acrylic. These include acid ester latexes, vinyl acetate latexes, methyl methacrylate-butadiene latexes, and carboxy-modified (for example, acrylic acid) latexes thereof.

If the surface strength of the pigment coating layer (3) is weak, it will not be possible to obtain a layer with excellent printability when printing ruled lines and the like. Therefore, the binder in the coating liquid forming the pigment coating layer is usually contained in a total solid content of 10% by weight or more, more preferably 20% by weight or more.

The coating amount of the pigment coating layer (3) is not limited to this, but from the viewpoint of color development and economical efficiency, it is 1 to 15 g/
m is preferable, more preferably 3 to lOg/rd.

In addition, when the other chromogen substance that reacts with the chromogen substance contained in the microcapsules of the transfer sheet (1) to form a color is contained in the pigment coating layer (3), the pigment coating layer (3) The density and durability of the colored image formed can be improved.

The receptor layer (4) of the present invention is formed by printing or coating an aqueous or non-aqueous ink or coating liquid on the pigment coating layer (3).

The non-aqueous ink or coating liquid forming the receiving layer (4) contains, in addition to the other chromogen material that causes a coloring reaction with the chromogen material on the transfer sheet side and a non-aqueous medium, a binder, a pigment, Various auxiliary agents known in the ink field such as ultraviolet absorbers, antioxidants, fluorescent dyes, colored dyes, photopolymerization initiators, waxes, dryers, thickeners, gelling agents, etc. are added, and evaporative drying type and radiation curing type are used. , cured polymerizable ink, etc. are prepared.

In the case of an aqueous system, in addition to the chromogen substance and water, binders, pigments, ultraviolet absorbers, fluorescent dyes, dispersants, etc. are added as necessary.

When a leuco-based recording material is used as a chromogen substance, an electron-accepting color developer is usually used in the receptor layer (4), but when an organic color developer is used, it has particularly excellent print storage stability and good tamper-proofing properties. is obtained.

As the non-aqueous medium used when preparing the non-aqueous ink or coating liquid, those known in the printing industry can be used as appropriate, but specific examples include benzene, toluene, xylene, cyclohexane, hexane, ligroin, Methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, diethylene glycol monobutyl ether,
diethylene glycol monobutyl ether acetate,
Methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-7'tanol, n-hexonol, cyclohexanol, 2-ethylhexyl alcohol, polyethylene glycol diacrylate, propylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane diacrylate , trimethylolpropane triacrylate,
Pentaerythritol tetraacrylate, hexanediol diacrylate, 1,2-butanediol diacrylate, reaction product of epoxy resin and acrylic acid, reaction product of methacrylic acid, pentaerythritol and acrylic acid, reaction product of maleic acid, diethylene glycol and acrylic acid Condensates, methyl methacrylate, butyl methacrylate, styrene, vegetable oils (drying oils such as linseed oil and sunflower oil, semi-drying oils such as soybean oil, non-drying oils such as castor oil),
Examples include processing oils (dehydrated castor oil, polymerized oil, maleated oil, vinylated oil, urethanized oil), mineral oils (machine oil, spindle oil), and the like.

Among these media, in order to prepare a dispersion type ink or a dispersion type coating liquid, it is preferable to use a medium that does not easily dissolve the chromogen substance.

In the present invention, it is extremely important that a part of the receptor layer (4) is transferred to the transfer sheet (1) by pressure, but for this purpose, the ink must be in a dispersed state, not in a dissolved state. Alternatively, it is included in the coating liquid. That is, it is necessary to provide the receptor layer (4) by printing or coating a dispersion ink or a dispersion coating liquid.

The chromogen substance in a dissolved state easily penetrates into the pigment coating layer (3), and the formed receptor layer is extremely difficult to transfer to the back surface of the transfer sheet (1), so that a sufficient tampering prevention effect cannot be obtained.

Therefore, although it is acceptable for the chromogen substance to be partially dissolved in the medium of the ink or coating liquid, it is desirable that the chromogen substance in a dispersed state be contained in an amount of approximately 3% by weight or more based on the medium. .

In addition to the aqueous binders mentioned above, binders used in the receiving layer ink or coating solution include rosin (gum rosin, wood rosin, tall oil rosin), shellac, copal,
Natural resins such as Dalman, Giltonite, Zein, hardened rosin, ester gum and other rosin esters, maleic acid resin, fumaric acid resin, duplex rosin, polymerized rosin, rosin-modified phenolic resin, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, ethyl hydroxy Semi-synthetic resins such as ethyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, nitrocellulose, phenolic resin, xylene resin, urea resin, melamine resin, Kent resin, coumaron/indene resin, petroleum resin, terpene resin, cyclized rubber, Chlorinated rubber, alkyd resin, polyamide resin, acrylic resin, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polyvinyl acetate, polyvinyl butyral (butyral resin), polyvinylpyrrolidone, chlorinated polypropylene styrene resin, epoxy resin, polyurethane, etc. Synthetic resins include:

These binders are selected and used depending on the type of medium used, and the method disclosed in, for example, "1 Printing Ink Technology" published by CMC Co., Ltd. can be appropriately adopted.

Examples of the pigment include those mentioned above.

Dispersion-based inks or coating liquids usually contain water or a non-aqueous medium.
It is prepared by mixing and stirring 5 to 100 parts by weight of a chromogen substance per 00 parts by weight, or by further dispersing it using a ball mill, sand grinder, etc., and mixing it with other components. In the present invention, in order to improve the transferability and printing workability of the receptor layer (4), it is important to set the surface strength of the receptor layer (4) to be weaker than that of the pigment coating layer (3). Therefore, the binder usually has a total solid content of 0.1 to
It is blended in an amount of 30% by weight, preferably 1 to IO% by weight.

The amount of ink or coating liquid to be applied is not limited to this, but from the viewpoint of color development on the back side of the transfer sheet, etc.
1 g/rd-10 g/rd, more preferably 0.3
g/rd to 5 g/cd.

Next, the transfer sheet (1) is obtained by coating a support with a microcapsule dispersion coating liquid containing an oil containing a chromogen substance. In addition to microcapsules, this dispersion contains
If necessary, a binder, a capsule protector, a surfactant, an antifoaming agent, a pigment, a preservative, an ultraviolet absorber, an antioxidant, etc. can be added. The amount applied to the support is not particularly limited, but is preferably 1 to 10 glr.
d, more preferably 2 to 7 g/nf.

The microcapsules used in the present invention can be prepared by a conventionally known coacervation method (for example, U.S. Pat. No. 2,800,457).
interfacial polymerization method (for example, JP-B No. 38-19574, JP-B No. 42-
446, Special Publication No. 42-771, Special Publication No. 49-451
33 etc.), 1n-situ polymerization method (
For example, Special Publication No. 36-9168, Special Publication No. 51-9079
The method disclosed in Japanese Patent Publication No. 53-84881).

Examples of the oil used in the present invention include the following substances known in the field of pressure-sensitive copying paper.

Aromatic carbonization of vegetable oils such as cottonseed oil, mineral oils such as kerosene, paraffin, naphthenic oil, and chlorinated paraffin, alkylated biphenyls, alkylated terphenyls, alkylated naphthalenes, diarylethanes, triarylmethanes, diphenylalkanes, etc. Hydrogens, oleyl alcohol, tridecyl alcohol, benzyl alcohol, l-
Alcohols such as phenylethyl alcohol and glycerin, organic acids such as oleic acid, dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate, diethyl adipate, propyl adipate, di-n-butyl adipate, adipine Esters such as dioctyl acid, tricresyl phosphate,
Organic phosphorus compounds such as tributyl phosphate, tributyl phosphite, tributyl phosphine oxide,
Ethers such as phenylcellosolve, pendylcarbitol, polypropylene glycol, propylene glycol monophenyl ether, amides such as N,N-dimethyllauramide, N,N-dimethylstearamide, N,N-dihexyl octylamide, Ketones such as diisobutyl ketone and methylhexyl ketone, alkylene carbonates such as ethylene carbonate and propylene carbonate, and mixtures thereof.

In the present invention, the microcapsule coating liquid on the transfer sheet (l) and the pigment coating layer (3) on the receiving sheet are usually formed by methods such as air knife coating, roll coating, and blade coating.

When the receptor layer (4) is also formed on the entire surface of the receptor sheet, it is similarly formed by the above coating method.

When forming the receptor N(4) locally, printing methods such as letterpress printing, intaglio (gravure) printing, lithography (offset) printing, and screen printing are usually used, and among them, local printing is performed in the form of non-aqueous ink. This is preferable from the viewpoint of printing work and the purpose of preventing tampering, and is preferable because a copy sheet that can be easily flexographically printed using alcohol-based ink can be obtained.

Examples of the support used in the present invention include paper, synthetic fiber paper, and synthetic resin film.

(Examples) In order to further clarify the effects of the present invention, Examples and Comparative Examples are given below, but the present invention is not limited to these Examples. Parts and % in the examples represent parts by weight and % by weight, respectively, unless otherwise specified.

Example 1 An aromatic polyvalent isocyanate (trade name Coronate-L,
(manufactured by Nippon Polyurethane Co., Ltd.) and dissolved this into 2%
The system was added to 600 parts of an aqueous polyvinyl alcohol solution and emulsified to give an average particle size of 8°0μ.
A capsule dispersion was obtained by reacting for a period of time. 50 parts of starch particles and 20 parts (solid content) of carboxy-modified styrene-butadiene copolymer latex were added to this dispersion to give a concentration of 18%.
It was diluted to give a microcapsule coating solution.

The obtained capsule coating liquid was smeared onto 40 g/cd base paper using an artisan knife coater so that the solid content was 3.0 g/rd to obtain a top paper.

轡、F color ink TL 3.5-tert-butyl zinc salicylate 10
0 parts, ethyl cellulose (ethyl cellulose Na14.
(manufactured by Vercules), 360 parts of ethanol, 40 parts of n-hexyl alcohol, and 40 parts of water were ground in a ball mill to obtain a color developing ink.

Zinc 3.5-di(tert-butyl)salicylate was dispersed in an amount of about 15% by weight based on the medium.

A plate! 75 parts (solid content) of carboxy-modified styrene-butadiene copolymer latex was added to a dispersion obtained by adding 3 parts (solid content) of star bottom polyacrylic acid soda and 300 parts light calcium carbonate to 900 parts water. 40 g/n of coating liquid prepared by adding
1 of base paper was coated with an air knife coater so that the dry weight was 5 g/rd.

The dispersion color developing ink was partially printed on the pigment coating layer of the inner sheet (2) by flexographic printing to obtain a printed matter with an ink coverage of 1.5 g/d.

(2) When the transfer sheet (top paper) and the receiving sheet (bottom paper) were stacked and printed using a typewriter, a blue colored image was obtained on the printing portion of the receiving layer of the receiving sheet and on the back side of the transfer sheet.

Example 2 Ethylene-maleic anhydride copolymer (trade name EMA-3
1. 20 parts to 200 parts of a 3.0% aqueous solution of
After emulsifying 100 parts of alkyldiphenylethane (trade name: Hysol 5AS-296, manufactured by Nippon Petrochemical Co., Ltd.) in a solution with a pli of 6.0 by adding % caustic soda aqueous solution,
The system was heated to 55°C.

Separately, add 1 part of melamine to 30 parts of 37% formaldehyde aqueous solution.
0 part was added and reacted at 60° C. for 15 minutes to prepare an aqueous prepolymer solution.

This prepolymer aqueous solution was added dropwise to the emulsion, and while stirring, the prepolymer solution was added dropwise. I N = Add hydrochloric acid dropwise to reduce p)l to 5
．． 3, heated to 80°C, held at that temperature for 1 hour, lowered the pH to 4.0 with 0.2N hydrochloric acid, kept warm for an additional 3 hours, and then allowed to cool until the average particle size was 4. A dispersion of oil-encapsulated microcapsules of 0μ was obtained.

Oil microcapsules A: Cloth bottom To a coating solution prepared in the same manner as the coating solution used for forming the pigment coating layer in Example 1, the above oil capsule dispersion was added, and further 60 parts of starch particles and carboxy-modified A coating solution prepared by adding 20 parts (solid content) of styrene-butadiene copolymer latex was applied to 40 g/rd base paper with a dry weight of 5 g.
/rrl using an air knife coater.

Ink application 1).The dispersion developing ink prepared in the same manner as in Example 1 was partially printed on the pigment coating layer of the receiving sheet (for use) by flexographic printing. A printed matter of 5 g/m was obtained.

C) When the transfer sheet (upper paper) prepared in the same manner as in Example 1 and the above-mentioned receptor sheet (lower paper) were overlapped and printed using a typewriter, a blue color was printed on the receptor layer printed portion of the receptor sheet and on the back side of the transfer sheet. A colored image was obtained. It was found that the color development on the back side of the transfer sheet was better than that in Example 1.

Example 3 Developing Color 1 A Co.t 195 parts of light calcium carbonate, 60 parts of zinc oxide, 3.5 parts
-Mixture of zinc di(α-methylbenzyl)salicylate and α-methylstyrene/styrene copolymer (melt ratio: 8
0/20), 15 parts of polyvinyl alcohol aqueous solution (solid content), and 900 parts of water were ground in a ball mill for 24 hours, and 60 parts of carboxy-modified styrene-butadiene copolymer latex was added to the dispersion obtained. In addition, the prepared developer-containing pigment coating liquid was applied onto a 40 g/rd base paper using an air knife coater so that the dry weight was 5 g/rd.

A dispersed color developing ink prepared in the same manner as in Example 1 was partially printed on the above pigment coating layer of the six sheets (') by flexographic printing to obtain a printed matter with an ink coverage of 1.5 g/rd.

This value When the transfer sheet (upper paper) prepared in the same manner as in Example 1 and the above-mentioned receptor sheet (lower paper) were overlapped and printed using a typewriter, a blue color was printed on the receptor layer printed portion of the receptor sheet and on the back side of the transfer sheet. A colored image was obtained. It was found that the color development on the receiving layer was better than that of Example 1.

Example 4 An oil-encapsulated microcapsule dispersion prepared in the same manner as in Example 2 was added to a dispersion prepared in the same manner as the coating liquid used to form the developer-containing pigment coating layer in Example 3, and starch was further added. A coating solution prepared by adding 60 parts of particles and 20 parts (solid content) of carboxy-modified styrene-butadiene copolymer latex was applied to a 40 g/rd base paper using an air knife coater so that the dry weight was 5 g/rd. did.

A dispersed color developing ink prepared in the same manner as in Example 1 was partially printed on the pigment coating layer of the six sheets by flexographic printing to obtain a printed matter with an ink coverage of 1.5 g/rrf.

When the transfer sheet (upper paper) prepared in the same manner as in Example 1 and the above-mentioned receiving sheet (lower paper) were overlapped and printed using a typewriter, the difference between the receiving sheet (lower paper) and the transfer sheet (upper paper) was A clear blue colored image was obtained on the back side. It was found that both the color development on the receptor layer and the color development on the back side of the transfer sheet were better than those in Example 1.

Comparative Example 1 As a result of evaluation in the same manner as in Example 3 except that a receptor sheet was prepared in the same manner as in Example 3 without printing a receptor layer on the developer-containing pigment coating layer, it was found that the back side of the transfer sheet No colored image was produced at all, and no tampering prevention function was obtained.

Comparative Example 2 A pigment-coated sheet containing oil-encapsulated microcapsules and a color developer prepared in the same manner as in Example 4 as a receptor sheet was evaluated in the same manner as in Example 4, except that the receptor sheet was used without printing a receptor layer. As a result, no colored image was formed on the back side of the transfer sheet, and no tampering prevention function was obtained.

(Effects) The present invention provides an excellent tamper-proof pressure-sensitive copying sheet that cannot be tampered with by additional entries.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a tamper-proof pressure-sensitive copying sheet of the present invention. FIG. 2 is a sectional view showing the structure of a conventional tamper-proof pressure-sensitive copying sheet. (1)...Transfer sheet (2)...Receptor sheet (3)
... Pigment coating layer (4) ... Receptive layer (5) ...
・Microcapsule coating layer

Claims (3)

[Claims] (1) A pressure-sensitive copying sheet composed of a combination of a transfer sheet (1) having microcapsules containing a chromogen substance and a receptor sheet (2) that develops color by reacting with the chromogen substance in the microcapsules, The receiving sheet (2) has a pigment coating layer (3) provided on the support, and further includes a pigment coating layer (3).
A receiving layer (4) is provided thereon by printing or coating with a dispersion ink or dispersion coating liquid of another chromogen substance that reacts with the chromogen substance of the transfer sheet (1) to form a color. ,
A tamper-proof pressure-sensitive copying device characterized in that a part of the receptor layer (4) is transferred to the back side of the opposing transfer sheet (1) by recording pressure, and a tamper-proof record is obtained on the back side of the transfer sheet (1). sheet. (2) The tamper-proof pressure-sensitive copying sheet according to claim 1, wherein the pigment coating layer (3) of the receiving sheet (2) contains microcapsules encapsulating oil. (3) A claim in which the pigment coating layer (3) of the receptor sheet (2) contains another chromogen substance that develops color by reacting with the chromogen substance contained in the microcapsules of the transfer sheet (1). The tamper-proof pressure-sensitive copying sheet described in item (1).