(19) TZZ¥_ Z_T (11) EP 3 168 270 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.: 17.05.2017 Bulletin 2017/20 C09D 11/04 (2006.01) B41M 3/14 (2006.01) B41F 17/00 (2006.01) C09D 11/50 (2014.01) (21) Application number: 16185655.4 (22) Date of filing: 25.08.2016 (84) Designated Contracting States: (72) Inventors: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB • LEE, Myoung Ku GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO Gangwon-do (KR) PL PT RO RS SE SI SK SM TR • RYU, Jeong Yong Designated Extension States: Gangwon-do (KR) BA ME • KIM, Chang Geun Designated Validation States: Gangwon-do (KR) MA MD • LEE, Kwang Seob Gangwon-do (KR) (30) Priority: 13.11.2015 KR 20150159856 • LEE, Jae Hoon Gangwon-do (KR) (71) Applicants: • CHO, Han Je • Kwangwon National University Seoul (KR) Gangwon-do (KR) • KWON, Hyeok Jun • Daehan Paper Co., Ltd. Gyeonggi-do (KR) Chungcheongbuk-do (KR) • Taekyung Polymer Co., Ltd. (74) Representative: Wablat Lange Karthaus Gyeonggi-do (KR) Anwaltssozietät • Centre Technique de l’Industrie des Papiers, Potsdamer Chaussee 48 Cartons et Celluloses 14129 Berlin (DE) 38044 Grenoble Cedex 9 (FR) (54) SYMPATHETIC PRINTED-MATTER AND METHOD OF PRODUCING THE SAME (57) Using the sympathetic printed-matter according the sympathetic printed-matter has been read by any oth- to the present invention, a hidden content can be visual- er person can be easily determined. In the sympathetic ized just by wetting. Therefore, it is possible to remove printing method according to the present invention, a hy- necessities of the sympathetic ink and a special material drophobic substrate can be formed using an existing gas such as reagent or equipment for visualizing hidden con- grafting facility, and an ester hydrolase composition and tents. In addition, since the hidden contents disappear the reading confirmation portion can be formed using an by removing water from the sympathetic printed-matter, existing printing method. Therefore, a large amount of the sympathetic printed-matter can be used repeatedly. sympathetic printed-matters can be produced inexpen- Using the reading confirmation portion, whether or not sively and efficiently. EP 3 168 270 A1 Printed by Jouve, 75001 PARIS (FR) EP 3 168 270 A1 Description CROSS REFERENCES TO RELATED APPLICATIONS 5 [0001] The present invention contains subject matter related to Korean Patent Application No. 2015-0159856, filed in the Korean Patent Office on November 13, 2015, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION 10 Field of the Invention [0002] The present invention relates to a sympathetic printed-matter having a hydrophilic substrate portion formed on a hydrophobic substrate and a method of producing the same. 15 Description of Related Art [0003] As industries are developing, and competitions become violent, demands for convenient and reliable stega- nography increase. In particular, a sympathetic printing method using a sympathetic ink promotes new demands for anti-forgery techniques in the field of securities or exchange checks. Sympathetic printed-matters using a sympathetic 20 ink are advantageous in that a confidentiality status can be easily checked because whether or not a printed matter has been read by any other person can be easily confirmed. The term "sympathetic" means a phenomenon in which something is invisible on application or soon but can be visible later by developing the hidden parts. The sympathetic printed-matter is a printed matter produced using a sympathetic ink, on which a script written with a sympathetic ink can be visualized through heating or other methods such as a chemical reaction. The sympathetic ink may include a body fluid such as 25 blood, saliva, sweat, and urine, various foods or compounds containing acidic or basic properties such as vinegar, fruit juice, sodium bicarbonate, salt, sugar, rice, aspirin, Arabian gum, boric acid, starch, ammonia, magnesium sulfate (epsom salts), caustic silver, soap, glue, or adhesive. As a representative material of the sympathetic ink, lead acetate (Pb(CH3COO)2) is known in the art. The lead acetate has a colorless crystalline material obtained by dissolving lead monoxide (PbO) or tri-lead tetra-oxide (Pb 3O4) in acetic acid. A sympathetic ink is obtained by dissolving the lead acetate 30 in an alum solution. As a method of visualizing hidden contents written on a sympathetic printed-matter, there are known an optical method in which a hidden part is visualized by irradiating light using a special light source such as infrared or ultraviolet rays or irradiating such light at a particular angle, a mechanical method in which a hidden part is visualized by dispersing minute powder such as graphite and sweeping away the powder, and a physical chemical method in which a hidden part is visualized by exposing the sympathetic printed-matter in the hot air, fumes, or vapors of a chemical 35 agent or immersing it in a chemical agent. The sympathetic printed-matter using a sympathetic ink of the related art is based on an irreversible sympathetic phenomenon in which the printed part appears and does not disappear continuously thereafter. Even when it is reversible, it is difficult to know whether or not the hidden part of the sympathetic printed- matter has been already read by any other person. In addition, it is necessary to provide a separate reagent or tool for visualizing the hidden part on the sympathetic printed-matter. 40 [Citation List] [Patent Literatures] 45 [0004] [Patent Literature 1] Korean Patent No. 0173103 SUMMARY OF THE INVENTION [0005] In view of the aforementioned problems, the present invention provides a sympathetic printed-matter and a 50 method of producing the same, by which a hidden part can be visualized just by wetting, and the visualized part disappears by removing water, so that it can be reused repeatedly. In addition, the present invention provides a sympathetic printed- matter having a reading confirmation portion by which whether or not the hidden part has been read by any other person can be easily confirmed. [0006] According to an aspect of the present invention, there is provided a sympathetic printed-matter having a hy- 55 drophilic substrate portion formed on a hydrophobic substrate. [0007] According to an embodiment of the invention, the sympathetic printed-matter is formed without using a sym- pathetic ink. In the sympathetic printed-matter according to the present invention, visualization is performed based on a brightness difference between a wetted substrate and an unwetted substrate. Therefore, the sympathetic ink is not 2 EP 3 168 270 A1 necessary. [0008] According to another embodiment of the invention, the hydrophobic substrate is obtained by performing fatty- acid-chloride gas grafting for a substrate formed of a material containing a hydroxyl group (-OH) to hydrophobize the substrate. Preferably, the substrate formed of a material containing the hydroxyl group (-OH) is cellulose or polyvinyl 5 alcohol (PVA). More preferably, the substrate is a paper sheet or a paper board. Any substrate may be employed as long as it can be wetted by water. Considering print quality and use purposes, a paper sheet or a paper board having a high water absorption property is preferable. The fatty-acid-chloride grafting may be performed based on any gas grafting method known in the art (refer to Korean Patent Application Publication Nos. 10-2015-0077380 and 10-2015-0077379). 10 [0009] According to an implementation of the invention, the hydrophilic substrate portion is formed by partially printing an ester hydrolysis enzyme composition on the hydrophobic substrate. As a printing method of the enzyme composition, any method may be employed without a limitation as long as the enzyme composition can be printed on the hydrophobic substrate in a desired shape, and the enzyme composition can be sprayed uniformly with a constant thickness to uniformly generate the ester hydrolase reaction. 15 [0010] According to an implementation of the invention, the hydrophilic substrate portion additionally has a reading confirmation portion. The reading confirmation portion is used to irreversibly visualize whether or not a hidden part on the sympathetic printed-matter has been read by any other person. [0011] According to another aspect of the invention, there is provided a method of printing a sympathetic printed- matter having a hydrophilic substrate portion formed on a hydrophobic substrate, the method including: (a) forming a 20 hydrophobic substrate by performing gas grafting using fatty acid chloride; (b) partially printing an ester hydrolase composition of 0.3 to 0.7 g/m 2 on the hydrophobic substrate and generate a reaction for 20 to 40 minutes under a room temperature to form a hydrophilic substrate portion; (c) washing and drying the hydrophobic substrate having the hy- drophilic substrate portion; and (d) printing a reading confirmation portion on the hydrophilic substrate portion. [0012] Other objects and technical characteristics of the present invention will become apparent by reading the following 25 description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The foregoing and additional features and characteristics of this disclosure will become more apparent from 30 the following detailed description considered with reference to the accompanying drawings, wherein: FIG. 1 illustrates a reversible sympathetic phenomenon of a sympathetic printed-matter. DETAILED DESCRIPTION OF THE INVENTION 35 [0014] The present invention provides a sympathetic printed-matter in which a hydrophobic substrate portion and a hydrophilic substrate portion are formed distinguishably, hidden contents are visualized by wetting, the hidden contents disappear by drying, and a reading confirmation portion is formed to allow a user to confirm whether or not the hidden contents have been read by any other person. 40 <Sympathetic Printed-Matter> [0015] The term "sympathetic printed-matter" means a printed matter or sheet on which contents such as scripts, symbols, or pictures are invisible in ordinary times, and they are visualized when a particular condition is satisfied.