JPS58179685A - Transfer sheet for preparation of secret document - Google Patents

Abstract

PURPOSE:To obtain a transfer sheet capable of effectively giving latent images composed of an ultraviolet rays absorber to an usual paper and also of permitting confirmation by a simple operation by using a paper coated with an usual paper transfer type recording layer containing ultraviolet rays absorber capsules and a wax. CONSTITUTION:A transfer sheet for preparation of secret documents is produced by forming a coated paper with an usual paper transfer type recording layer by using a coating liquid containing capsules with an ultraviolet rays absorber [2-(2'-hydroxy-5'-methylphenyl) benzotriazole, etc.] and a wax (paraffin wax, etc.). The ultraviolet rays absorber used is preferably dissolved in a nonvolatile oil as a vehicle, and its preferred amount to be dissolved in the vehicle is 0.5- 5wt%. The preferred amount of the wax is 5-100% on the basis of the solid content of the capsule. EFFECT:Latent image can be obtained simply by pressing the transfer sheet on usual papers and can also be confirmed by a fluorescent inspection lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer sheet for producing secret documents, which is capable of producing a latent image made of an ultraviolet absorber on a plain paper surface.

Traditionally, creating secret documents involved exposing them. If you write pictures or letters on plain paper with a specific solution and let it dry, it becomes difficult to identify after writing, but when you heat the plain paper, the pictures or letters will appear again.For example, blue coloring caused by cobalt chloride, Blackening occurs due to carbonization of cellulose with dilute sulfuric acid, and blackish brown coloring occurs due to squeezed orange juice.

I can't be satisfied with that.

On the other hand, Japanese Patent Application Laid-Open No. 56-75659 discloses a recording medium for creating secret documents that produces a magnetic latent image on a magnetic recording notebook. This has the advantage that pressure-sensitive paper, a magnetic recording sheet, and a high magnetic permeability material are sequentially laminated, and magnetic recording can be performed while viewing a visible image using the pressure-sensitive paper with a magnetic pen. There is complexity.

As a result of research conducted in order to solve the above-mentioned drawbacks, the inventor of the present invention has discovered that a coated paper having a plain paper transfer type recording layer containing ultraviolet absorber-containing capsules and wax as a component and plain paper are stacked and pressed together. The present invention provides a transfer device 7-1 for creating a secret document that can obtain a latent image made of an ultraviolet absorber transferred onto a plain paper surface.

The object of the present invention is to overlap the above-mentioned transfer sheet for creating a secret document with plain paper and apply pressure printing from the non-coated surface of the transfer sheet using a pen pressure of a ballpoint pen or the like, and when the transfer sheet I and the non-coated layer Simultaneously with printing on the paper surface, the ultraviolet absorbent-containing capsules on the coated surface are destroyed and the ultraviolet absorbent is transferred to the plain paper surface to obtain a latent image.

The resulting latent image is not discernible during normal handling, ie, in a visible state, and can only be confirmed by using a fluorescent inspection light.

By the way, various microencapsulation methods can be used for ultraviolet absorbent-containing capsules, such as complex coacervation method, interfacial polymerization method, in situ method, spray drying method, and in-liquid curing method, depending on the properties of the ultraviolet absorber itself. It can be separated and there is no difficulty in understanding it.

In the combination of the ultraviolet absorber capsule and wax, which are components of the plain paper transfer type recording layer of the present invention, the use of wax has the advantage that the ultraviolet absorber can be transferred to the plain paper surface very efficiently. For efficient transfer, the amount of wax used is preferably 5 to 100 percent by weight based on the solid content of the capsule.

Examples of the ultraviolet absorber of the present invention include 2,4-dimethoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, and 2-hydroxy-4-dodecyloxy. Be/Sopheno7.2.2'-dihydroxy-4-7toxybenzophenone/2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2.2+, A, 4'-Tetrahydroquine Benozof enone, 2-hydroquine-4-
Methoxy-2'-hydroxybenzophenone, 2-hydroxy-4-methoxy/-5-sulfobenzophenone, 2
-Hydroxy-4-oxybenozylbenzophenone, 2
-Hydroxy-4-chloropenzophenono, 2-hydroxy-5-chloro-benzophenone, 2-hydroxy-
4-Methoxy-4-methylbe/sophenone, 2-hydroquine-4-n-heptoxybenzophenone, 2-hydroxy-3,6-dichloro-4-methoxybe/sophenone, “2-hydroxy-q,6-dichloro-4 Benzophenone ultraviolet absorbers such as 2-hydroxybenzophenone, 2-hydroquine-4-(2-hydroxy-3-methylacryloxy)propoquine benzophenone; 2-(2'
-Hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-ternary-butylphenyl)benzotriazole, 2-(
2'-Hydroxy-31-tert-butyl-5'
-methylphenyl)penztriazole 2 (z,
I-hydroxy-4'-octoxyphenyl)bear 7
' l-Ryazur, 2-(2'-hydroxy-3,'
5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-, (27-hydroxy-3
/9-Shari-butyl-5'-methylphenyl)-
5-chloropenztriazole, 2-(2'-hydroxy-5-methoxyphenyl)benzotriazole, 2-
(2'-Hydroxy-5-ethoxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-ta-5-mono-shaributylphenyl)benzotriazole, 2-
Benzotriazole ultraviolet absorbers such as (2'-hydroxy-3,'5'-di-ternary-amylphenyl)benzotriazole; phenyl salicylate, p-octylphenyl salicyl'l', P-ternary butyl Examples include cyanoacrylate UV absorbers such as phenyl salicylate varnishes such as phenyl salicylate, carboxyphenyl salicylate, methyl phenyl salicylate, and dodecylphenyl salicylate. Among these UV absorbers, they are visible because they are colored. It can be used for objects by coloring the background of the plain paper to which the image is to be transferred in the same color.

When UV light is applied, the amount of UV absorber dissolved in the vehicle is 0.2 to 10 percent by weight.

6- Preferably it is 05 to 5 weight par 7/1.

Regarding waxes used in combination with UV absorbers, animal waxes such as beeswax, spermaceti wax, Chinese wax, lanolin, etc.
Canodelila wax, carnauba wax, wood wax,
Vegetable waxes such as rice wax and humpback wax, mineral waxes such as heptanowax, onkelite, cerezono, and lignite wax, petroleum waxes such as paraffin wax and microcrystalline wax, Monkun wax 44, paraffin wax derivatives, micro Modified waxes such as crystalline wax derivatives, hydrogenated waxes such as castor wax and opal wax, low molecular weight polyethylene and its derivatives,
Acrawax, synthetic waxes such as distearyl ketone, caproic acid amide, caprylic acid amide, pelargonic acid amide, capric acid amide, lauric acid amide, trideflyic acid amide, myristic acid amide,
Fatty acid amide waxes such as ethylene bisstearamide, and unsaturated fatty acid amides such as caproleic acid amide, myristoleic acid amide, oleic acid amide, elaidic acid amide, linoleic acid amide, erucic acid amide, ricinoleic acid amide, and linoleic acid amide You can list the ones you can choose from.

And these can be used alone or in combination.

The method of manufacturing the transfer plate for producing confidential documents according to the present invention includes a method of coating the entire surface of the support using a partial coater such as an air knife coater as an aqueous dispersion coating solution, or a method of spraying microcapsules. After drying, if necessary, it is mixed uniformly with powdered microcapsules at the melting temperature of wax to form a coating solution, which is printed on a part of the support using a normal carbon printing machine etc. You can choose any method you like.
1. When preparing the coating liquid according to the present invention, a liquid property improver can be added depending on various coaters and printing machines. Examples include thickeners that keep the viscosity constant and surfactants that improve dispersibility, but it is clear that they are not limited to these.

Paper is mainly used as the support for forming the coating layer according to the present invention, but various non-woven plastic films, synthetic papers, metal foils, etc., composites/sheets combining these, and sheets made by enovossing each of these may also be used. It will be done.

Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "parts" indicate parts by weight.

Example 1 Microcapsules containing an ultraviolet absorber were prepared as follows.

10% aqueous solution of ethylene/maleic anhydride copolymer
0 parts of urea, 1 part of resorcin, and 200 parts of water were prepared as a mixed solution, and the pH was adjusted to 20% sodium hydroxide aqueous solution. 2-(2'-hydroxy-
5'-methylphenyl)benzo l-IJ azole [Product name: 9-TINUVIN P, CIB string forceps manufactured by IGY] 14
1 part was dissolved in 9140 parts of Hysol SAS N-296 (diarylethane solvent, manufactured by Nippon Petrochemical Co., Ltd.) to prepare a UV absorber solution. This UV absorber solution was emulsified and dispersed in the above mixed aqueous solution, and oil droplets were After setting it to 5~6μ, 3
25 parts of a 7% formalin aqueous solution was added and the temperature of the system was maintained at 55° C. with stirring. After reacting for 2 hours, cool
The pH of the system was set to 95, and encapsulation was completed. 50 parts of the ultraviolet absorber-containing capsules (as solid content) prepared as above, 45 parts of 45% paraffin wax emulsion, 25 parts of wheat starch, 48% SBR, and 50 parts of latex were mixed and stirred, and water was added. An aqueous dispersion coating liquid with a solid content of 20" was prepared. This coating liquid had a basis weight of 4sy
/m' base paper to a total area of 697 m2 using a Meyer bar.

The coated side of the obtained transfer sheet for creating secret documents was placed opposite to plain paper, and pressure printing was performed using a reball pen from the non-coated side. When the printed portion of the plain paper was visually observed, no printed portion could be identified.

Next, when the printed area was irradiated with a fluorescent inspection light (manufactured by Tokyo Kogaku Kikai Co., Ltd., model Fl-3L) in a dark room, a clear conotrust character image was confirmed due to the absorption of fluorescent light. It's finally here.

Example 2 In place of the ultraviolet absorber 2-(2'-hydroxy-5'-methylphenyl)benzotriazole in the ultraviolet absorber-containing capsule prepared in Example 1, a benzophenono-based ultraviolet absorber 2,4] was used. Droxybenzophenono [Product name Sumisorb-10]
0, manufactured by Sumitomo Chemical Industries, Ltd.] was used for encapsulation and coating.

The coated surface of the obtained transfer sheet I for creating secret documents was slightly reddish.

On the other hand, the plain paper had a similar reddish background. When pressurized printing was performed in the same manner as in Example 1, it was impossible to visually identify the image, but a clear printed image could be identified on the red plain paper using a fluorescent inspection lamp in a dark room.

Claims (1)

[Claims] By overlapping and pressing plain paper with a coated paper having a plain paper transfer type recording layer containing ultraviolet absorber-containing capsules and waxes, a latent image made of the ultraviolet absorber is transferred to the surface of the plain paper. A transcription sheet for creating secret documents.