JPH0326149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for copying potentially hidden characters, symbols, etc. that develop color and become legible when brought into contact with an electron-donating organic compound or a phenolic hydroxyl group-containing compound. Regarding the seat.

Reflecting the information age, in various fields of society there is a special need to copy and transmit confidential information such as confidential texts and codes that would pose a problem if read and obtained by others or other parties. are very common.

One possible way to easily meet these demands is to utilize a coloring system consisting of an electron-donating organic compound and a phenolic hydroxyl group-containing compound, which has been widely used in pressure-sensitive copying paper, thermal copying paper, etc. . That is, for example, characters transferred onto general paper from a transfer layer containing microcapsules of a colorless electron-donating organic compound solution are colorless and cannot be read, but when a solution of a phenolic hydroxyl group-containing compound is applied thereon, the characters develop color, and the above-mentioned Able to respond to requests.

However, in the above-mentioned embodiment that directly applies the principle of pressure-sensitive copying paper, etc., since the electron-donating organic compound is dissolved in a solvent, the transferred characters etc. bleed during color development and are difficult to read. In some cases, information such as small letters and symbols may be transmitted incorrectly, resulting in an unexpected accident or damage.

The present inventors have solved the above-mentioned problems by using a carbon ink prepared by blending a fatty acid amide, which is solid at room temperature, with an electron-donating organic compound or a phenolic hydroxyl group-containing compound as a transition layer, thereby easily meeting the above-mentioned requirements. The present invention was completed by determining that the present invention can be met in an appropriate manner.

That is, as shown in the schematic longitudinal cross-sectional view of FIG. The present invention relates to a concealing copying sheet A comprising a carbon transfer sheet 1 and a carbon receiving sheet 2 having a carbon ink layer 3 obtained by coating under melting.

The colorless or light-colored electron-donating organic dye compounds used in the present invention include those conventionally used in pressure-sensitive copying papers, such as triphenylmethane phthalides, fluorans, phenothiazines, indolphthalides, and leuco It may be appropriately selected from auramines, spiropyrans, rhodamine lactams, etc., and is not particularly limited. Specifically, 3,
3-bis-(p-dimethylaminophenyl)-6-
Dimethylaminophthalide (the most useful), 3,
3-bis-(p-dimethylaminophenyl)-phthalide, rhodamine B lactone, 3-dimethylamino-6-methoxyfluoran, 3,6-diethoxyfluoran, 1,2-benzo-6-diethylaminofluoran , di-β-naphtose spiropyran, xantho-β-naphtose spiropyran, benzo-β-naphtho-isospiropyran, and any mixture thereof.

The colorless or light-colored phenolic hydroxyl group-containing compound used in the present invention is not particularly limited, but preferred ones include 4-t-butylphenol, 4-t-butylphenol, and 4-t-butylphenol.
Oxydiphenyl ether, β-naphthol, p
-methyl oxybenzoate, 2,2'-methylenebis(4-methyl-6-t-isobutylphenol),
p-phenylphenol, bisphenol A, 2
Examples include -oxy-1-naphthoic acid, zinc salicylate, zinc salts of salicylic acid polymers, gallic acid, propyl gallate, and any mixtures thereof.

Examples of fatty acid amides that are solid at room temperature according to the present invention include amides such as caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, aragidic acid, behenic acid, and oleic acid, and arbitrary mixtures thereof. be done.
Such fatty acid amides are also wax-like substances, but they can be distinguished from the general waxes described below because they significantly increase the solubility and dispersibility of the electron-donating organic compounds or phenolic hydroxyl group-containing compounds in the molten state. do.

The amount of fatty acid amide that is solid at room temperature is usually 3~
80% by weight, preferably 5-50% by weight.

The carbon ink according to the present invention may optionally contain colorless or light-colored waxes, that is, melting points of about 30 to
Wax or wax-like substances at 130°C, such as carnauba wax, aurichary wax,
Candelilla wax, Sugar Cane wax, Coconut wax, Sasol wax, Oxidized micro wax, Rice wax, Paraffin ( _C20 or higher), Low molecular weight polyethylene, Wood wax, Petrolatum, Stearic acid, Palmitic acid, Stearimide, Stearon etc. may be blended as appropriate.

The wax-type carbon ink prepared from the above-mentioned ingredients may be appropriately blended with additional oil such as mineral oil or non-drying vegetable oil (usually about 0 to 50% by weight) to plasticize it and improve transferability. .

The carbon transfer sheet according to the present invention is produced by melting the above-mentioned carbon ink at a temperature higher than its melting point, preferably at a temperature about 10°C higher than its melting point, and applying or spotting it onto a base sheet such as paper, cellophane, plastic film, etc. It is generally manufactured by the so-called cold set method in which the sheet is printed and immediately cooled to solidify and set.

The carbon transfer sheet thus obtained is used in combination with a carbon receiving sheet.
The carbon receiving sheet used in the present invention may be of any material or form as long as it can potentially conceal and receive the carbon ink that is transferred by the pressure applied to the carbon transfer sheet. General paper is commonly used.

Additionally, if a fine, random embossed pattern is applied to the carbon receiving sheet using a conventional method, it has the advantage of improving concealment by camouflaging the denting of printed characters caused by localized strong pressure during transfer, which makes them legible. .

The carbon receiving sheet is placed on the carbon ink layer of the carbon transfer sheet, and by applying pressure such as writing pressure or typewriter pressure from the transfer sheet side, the carbon ink layer corresponding to the pressure area is placed on the receiving sheet. The transfer is carried out in a potentially hidden state (unreadable to the naked eye) and this transfer surface is exposed to solvents, in particular aromatic volatile solvents, such as toluene,
When contacted with a phenolic hydroxyl group-containing compound solution or an electron-donating organic compound solution dissolved in xylene, trichlene, perchrene, methylene chloride, 1,1,1-trichloroethane, etc. by spraying or coating, the transferred area becomes legible. Develops color.

Furthermore, if two or more copies are required, the required number of transfer sheets may be inserted between the transfer sheet and the receiving sheet.

The copy sheet according to the present invention can transmit confidential information easily, safely and accurately, and is therefore extremely useful in various fields.

The present invention will be explained below with reference to Examples. In the examples, "parts" represent "parts by weight."

Example 1 Salicylic acid polymer 12.0 parts, basic zinc chloride 6.0 parts
part, stearic acid amide 25.0 parts, stearic acid
A mixture of 20.0 parts by weight, 5.0 parts by weight of Hoechst Wax S, and 32.0 parts of paraffin wax (melting point 135〓) was coated on India paper at a rate of about 4 g/m ² while heating to 100° C. to obtain carbon transfer paper.

Layer the carbon transfer paper with the coated side facing down on carbon receiving paper, which has been made with a fine random embossed pattern on high-quality paper using a conventional method, and then write on the carbon transfer paper with a ballpoint pen, making it completely legible with the naked eye on the carbon receiving paper. Hidden characters that cannot be printed were printed.

On the other hand, a developer solution prepared from 5.0 parts of 3,3-bis-(p-dimethylaminophenyl)-6-dimethylaminophthalide, 45.0 parts of methylene chloride, and 500 parts of 1,1,1-trichloroethane was added to the above solution. When it was applied onto the hidden characters using a brush, the hidden characters developed a blue color and were legible.

Example 2 3,3-bis-(p-dimethylaminophenyl)
-A mixture consisting of 8 parts of 6-dimethylaminophthalide, 32 parts of stearamide, 20 parts of stearic acid, 15 parts of Hoechst wax O, 15 parts of #1 carnauba wax, and 10 parts of paraffin wax (melting point 130〓). A carbon transfer paper was obtained by coating about 4 g/m ² on India paper while heating it to 100°C.

In the same manner as in Example 1, loose characters that were completely unreadable to the naked eye were printed on a carbon receiving paper with an embossed pattern.

Meanwhile, 5 parts of bisphenol A and 95 parts of toluene
When an aerosol of the color developer prepared from the above was sprayed onto the hidden characters, the hidden characters developed a blue color and were legible.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional view of a copying sheet according to the present invention. 1 is a carbon transfer sheet, 2 is a carbon receiving sheet, 3 is a carbon ink layer, and A is a copy sheet.

Claims (1)

[Claims] 1. A carbon transfer sheet obtained by applying either a colorless or light-colored electron-donating organic dye compound or a phenolic hydroxyl group-containing compound and a fatty acid amide that is solid at room temperature under hot melting conditions. and a concealment copy sheet consisting of a carbon acceptance sheet. 2. The copying sheet according to item 1, wherein the content of fatty acid amide is 3 to 80% by weight. 3. The copying sheet according to item 1, wherein the carbon receiving sheet is a sheet with a fine random embossed pattern.