RU2157393C2 - Falsification-protected paint for color jet print - Google Patents

Abstract

FIELD: paint-and- varnish industry. SUBSTANCE: paint contains 1.1-1.3% of microcapsules of alcohol-soluble pigment and 1.1-1.3% of protective compound, the two being adsorbed on ultrafine silver chloride particles in the form of microcapsules with shells of structured polyethylenimine form of melamine-formaldehyde resin. Paint further contains, wt %: surfactant OP-7 3.0-3.2, surfactant OS-20 1.5-1.7, thiourea 4.5-4.7, vegetable oil 1.0-1.2, and distilled water - the balance. EFFECT: improved characteristics of paint thereby assuring higher-quality print when compared with falsified paint.

Description

 The invention relates to printing inks and inks, and more particularly, to counterfeit inks for inkjet printing methods. The main area of use of the invention is the manufacture, execution or filling out of office, accounting and other important business documents using printers.

 Known ink compositions for inkjet printing contain a binder, a dispersed dye, a surfactant and a solvent, typically water / US patent N 5395431, MKI C 09 D 11/02, NCI 106-20 P, 1994; Japan Application N 8612223, MKI C 09 D 11/18, 1996; Japanese application N 6013653, MKI C 09 D 11/00, 1994 /. Inkjet paints are strictly balanced systems. The introduction into their composition of any additional substances in order to give them special properties leads to destabilization and destruction of the dispersion. In connection with this, ink-proof inkjets protected from counterfeiting are little known. Of the many patents relating to inkjet inks, US Pat. No. 5,395,432 A, MKI C 09 D 11/00, NCI 106-21 A, 1993 (prototype) was selected as a prototype of the claimed technical solution, which proposes a composition of a non-counterfeit ink for ink printing method. According to the patent, the paint contains a binder - alcohol-soluble resins - polyamide, polyketone, acrylic and others, denatured ethyl alcohol, nonionic surfactant, deionized water and technological additives - defoamers. As a protective compound, zinc chloride or iron chloride in an amount of from 0.5 to 10% is introduced into the paint composition. An image made with such ink on white or slightly colored paper (substrate) is invisible and appears only when a special chemical substance (marker) is applied to the sealed area.

 The disadvantages of the composition proposed in the prototype should include the fact that it does not allow printing of visible information or images protected from falsification, and also requires the use of additional tools for visualization. In addition, inkjet ink is not water-resistant and the printed image made by it with wetting spreads out, which is unacceptable for important business documentation.

 The technical problem to which this invention is directed is to determine the composition of a waterproof, ink-protected ink jet printing method. In this case, ink on the prints must be protected by known chemical compounds, for example, phosphors, optical brighteners, photochromes, etc. It should also provide the ability to create not only hidden, but also visible printed image.

A positive result is achieved by the fact that the proposed inkjet paint contains an alcohol-soluble organic pigment and a protective compound in the form of microcapsules with a size of 0.1 - 0.2 microns. The microcapsules themselves consist of a core - ultrafine particles of silver chloride, on which an organic pigment or protective compound is deposited, and a shell of melamine-formaldehyde resin structured with polyethyleneimine. In addition, a mixture of surface-active substances OP-7 (monoalkylphenyl ether of polyethylene glycol containing 7-8 hydroxyethylated groups) and OS-20 (polyethylene glycol ether of a fatty acid, C _18-20 ), thiourea and vegetable oil are introduced into the paint. The finished paint is an aqueous dispersion and has the following ratio of ingredients,%:
Microcapsules with alcohol-soluble organic pigment - 1.1 - 1.3
Microcapsules with protective compound - 1.1 - 1.3
Surfactants
OP-7 - 3.0 - 3.2
OS-20 - 1.5 - 1.7
Thiourea - 4.5 - 4.7
Vegetable oil - 1.0 - 1.2
Distilled Water - Else
The use of a coloring substance and a protective compound in the form of microcapsules with a size of 0.1 - 0.2 μm in the inkjet ink composition, as well as a mixture of two surfactants having different chemical and conformational structures, thioureas as a regulator of the rheology of the dispersed system provide using inkjet methods of printing a hidden anti-fake (if microcapsules with pigment are excluded from the system) and a visible image on paper.

 Comparative analysis with the prototype allows us to conclude that the claimed fake-protected inkjet paint differs from the known both in chemical nature of the main ingredients and in form, i.e. the proposed technical solution meets the criterion of "novelty."

 This composition of the ink ingredients gives the prints new properties - moisture resistance, color fastness, provides the ability to obtain and protect against falsification of color images, which allows us to draw conclusions about the conformity of the proposed solution to the criterion of "significant differences".

 Information confirming the possibility of carrying out the invention.

 The anti-counterfeit color inkjet ink proposed in this invention can be used to apply a visible or hidden text and art image on porous substrates, mainly on paper and cardboard. The authenticity of the printed impressions can be checked using a conventional quartz-analytical lamp.

 To formulate the paint composition, microcapsules with organic pigments and protective compounds in the form of their dispersions in an aqueous medium were previously prepared.

From various groups of alcohol-soluble organic pigments to obtain a triad in relation to the subtractive method of color reproduction, implemented using an inkjet printer, pigments were selected, characterized by high purity of color tone:
- with the purple color component Hostaperm - Rosa E Efal 305 of the company "Hoechst"(Germany);
- yellow color component Permanent - Gelb GRX84 VP 2265 of the company "Clariant"(Germany); or Optacylgelb HR DLDA 005 from Farbwerke Hoechst AG (Germany);
- with the blue color component PV - Echtblau BG DJHL 502 from Clariant GmbH (Germany) or Neozapon Blau 807 from BASF AG (Germany).

As protective compounds used:
- phosphor - yellow-green luminor 540 T (TU 6-09-477-76, chemical plant named after Voikov, Moscow);
- optical bleach uvitex OB 45420 "Ciba-Geigy"(Switzerland);
- UV - absorber - Advastab 46 from Advance (Germany) 2-Hydroxy-4-octyloxybenzophenone or Tinuvin P 2- (2'-Hydroxy-5'-methylbenzotriazole from Ciba-Geigu (Switzerland); organic photochrome - 6 ^1- thermo-1,3,3 ¹ -trimethylspiro - [(2H ¹ -1 -1 ¹ -benzpyran) -2,2 ¹ -indoline], thermochromic compound - 6 ¹ , 8 ¹ -dichloro-1,3,3 ¹ - trimethylspiro - [(2H ¹ -1 ^1- benzpyran) -2,2 ¹ -indoline].

The listed pigments are encapsulating substances. For each of them, a mixture was prepared consisting of, g: encapsulated substance - 0.9; thiourea - 2.1; surfactants - OP-7 - 1.4; OS-20 - 0.7; sunflower oil - 0.5. The mixture was dissolved with stirring in 20 ml of ethanol until a homogeneous solution was formed. Then the alcohol was evaporated at 75-80 ^o C in a water bath. The resulting paste-like mass was dissolved in 33 g of distilled water and subjected to ultrasound using a PP - 01/100 piezoelectric transducer with an acoustic field intensity of 25 W / cm ² at a frequency of 20 MHz for 1 hour. During the ultrasonic treatment every 15 minutes to the mixture 2.5 wt.% aqueous solutions of polyethylenimine (mol. m. 10000) - 2 g; silver nitrate - 1.5 g and hydrochloric acid 2.5 wt.% aqueous solution of melamine-formaldehyde resin (pH 1.42) - 3 g. In this case, a sol of encapsulated substance was obtained in an aqueous medium containing surfactants, thiourea and sunflower oil. As a result of the interaction of silver nitrate and hydrochloric acid, the formation of silver chloride microparticles occurred, which adsorbed from the mixture primarily the sol of the encapsulated substance, and then the melamine-formaldehyde resin. The latter was structured by polyethyleneimine. In this way, microcapsules were obtained in the reaction mixture, consisting of microparticles of silver chloride with an encapsulated substance adsorbed on them and a shell of melamine-formaldehyde resin structured with (crosslinked) polyethyleneimine. The size of the microcapsules was 0.1 - 0.2 μm with a distribution of 98%. Surfactants, thiourea and sunflower oil are not included in the composition of microcapsules. They provide respectively the possibility of the emulsification process, regulation of the rheological properties of the system and its fixing after printing on paper. The mixtures thus obtained are aqueous dispersions containing microcapsules with organic pigments, and can be used as inks for color inkjet printing. Dispersions of microcapsules with protective compounds are used for printing latent images, observed only when irradiated with filtered UV light.

In order to obtain counterfeit ink for color inkjet printing, each of the dispersions of the microcapsules with purple, yellow and blue pigments was mixed with an equal amount of the dispersion of the microcapsules with one of the protective compounds. Thus, the formulation of anti-counterfeit ink for color inkjet printing includes, g (%):
Microcapsules with organic pigment (purple, yellow or blue) - 1.1 (1.2)
Microcapsules with one of the protective compounds - 1.1 (1.2)
Surfactants - OP-7 - 2.8 (3.1)
OS-20 - 1.4 (1.6)
Thiourea - - 4.2 (4.6)
Sunflower oil - 1.0 (1.1)
Distilled water - 79.0 (87.2).

 According to this recipe, a triad of protected inks was prepared - purple, yellow and blue.

 To print a printed image on Chaika writing paper, we used a Model 690 inkjet printer with HP 51629 cartridges manufactured by Hewlett Packard (USA) coupled with an IBM PC computer - 486 DX 33, and for color prints - a Lexmark 7000 three-chamber cartridge Model "A I980".

 The test program contained color text and art images.

 Color printed images made by a triad containing microcapsules with a phosphor or optical brightener when irradiated with UV light (λ = 365 nm), intensively fluoresce. When using a UV adsorber in the ink, the printed image appears dark against the general light background of the paper. The presence of organic photochrome in the ink gives the printed image a photochromism effect - when irradiated with UV light (λ = 365 nm), the luminescence intensity of the ink in the visible region gradually increases by 7-8 times over 1-3 minutes. The color of luminescence varies from pink to bright crimson. In daylight for 3-5 minutes, the color becomes original.

In the case of using microcapsules with a thermochromic substance, a colorful printed image when the print is heated on a special thermostat (it is possible to use any electric heating appliance with a closed heating element) up to 120 ^o C changes color from faint red to intense blue. In daylight, the paint gradually restores its color.

 The presence of the listed effects on the printed matter or documentation issued using an inkjet printer indicates their authenticity.

 The proposed inkjet inks containing encapsulated colorants and protective compounds are water resistant and have high printing and technical characteristics. Paints penetrate the depth of the paper by 30-40 microns with a paper thickness of 80-90 microns. Puncture of paint on the back of the paper was not observed.

Tests of prints 45 minutes after printing showed that when wetted, the colorful image does not blur and does not have a halo, and after a day the prints can withstand even short-term immersion in hot (60-80 ^o C) water.

 The use of microencapsulated substances in the paint is a kind of technological protection for the documentation they have executed, since technical difficulties practically impossible for counterfeiters are created.

Thus, the use of the proposed inkjet inks provides the following advantages compared to known inks:
- a high degree of reliability of printed products in relation to counterfeit;
- simplicity and speed of authentication, since the use of special activators is not required;
- in the process of control and authentication, samples are not subject to irreversible changes and are suitable for further use as intended.

Claims (1)

A fake-protected color inkjet ink containing pigment microparticles, a protective compound, a surfactant and distilled water, characterized in that it contains an alcohol-soluble pigment and a protective compound adsorbed on ultrafine particles of silver chloride, in the form of microcapsules with a shell made of structured polyethyleneimine melamine-formaldehyde resin, and as surface-active substances - a mixture of OP-7 based on monoalkylphenyl ethers of polyethylene glycol containing 7-8 ox ethylated groups and OC-20 on the basis of polyethylene glycol fatty acid esters with carbon numbers 18-20 and additionally thiourea and vegetable oil in the following ratio, wt.%:
The indicated microcapsules of alcohol-soluble pigment - 1.1 - 1.3
The specified microcapsules of the protective compound is 1.1 - 1.3
Surfactant: OP-7 based on monoalkylphenyl ethers of polyethylene glycol containing 7-8 ethoxylated groups - 3.0 - 3.2
OS-20 based on polyethylene glycol fatty acid esters with the number of carbon atoms 18-20 - 1.5 - 1.7
Thiourea - 4.5 - 4.7
Vegetable oil - 1.0 - 1.2
Distilled Water - Else