Title of Invention

AN INKLESS FINGER PRINT RECORDING DEVICE WITH COLOURLESS INK MEDIA

Abstract

This invention relates to development of an inkless fingerprint recording system with colourless ink media. The system for production of inkless fingerprint recording paper, in which suitable colourless reactive ink formulations are prepared, which adheres onto the finger bulbs which on pressing on a reactive paper surface, produces coloured impression of the finger bulb, thereby recording the finger print. The colourless reactive ink is prepared in a non-drying solvent medium with certain reactive dye intermediates and other supporting components, which is then kept absorbed in a suitable synthetic sponge with uniform microporosity which does not allow quick drying of the ink because of lesser capillary pressure.

Full Text

This invention relates to development of an inkless fingerprint recording system with colourless ink media. More particularly, this invention relates to the development of a system for production of inkless fingerprint recording paper, in which suitable colourless reactive ink formulations are prepared, which adheres onto the finger bulbs which on pressing on a reactive paper surface, produces coloured impression of the finger bulb, thereby recording the finger print. The use of finger prints as a system of identification is very ancient origin. The securing an impression of the papillary ridges on the finger tips for the purpose of identification, stands out as the only conclusive proof of personal identification. The only unchangeable and infallible means of positive identification is the fingerprinting as it cannot be duplicated. Finger prints help police force throughout the world to maintain criminal records. In India, the Central Fingerprint Bureau maintains records of finger prints of lacs of criminals and take out the record of the particular criminal when he is apprehended or absconded after leaving behind his latest fingerprints in the scenes of crime. Courts throughout the world hold fingerprint evidence as conclusive proof of crime/theft etc. Fingerprints particularly left hand thumb impression (LTI) are obtained in statutory documents and many times used by individuals for personal identification, as protection against foregeries and fraud. Fingerprint impressions are usually obtained by rolling the first joint of the finger over an inked surface and then lightly pressing the inked portion on a fingerprint card where the ridge patterns are recorded, which can be studied through a magnifying glass and then classified. Till to-day, in our country, direct fingerprint impressions are recorded with the help of ink pads or carbon paper like inked fingerprint papers. Latent fingerprint impressions are developed mechanically and/or chemically by known practices. The procedure followed in taking fingerprints for ordinary identification purpose is though not difficult and comprises of applying printer's ink from an inking surface onto the thumb and then pressing the thumb on a record paper. Many times plain writing fluid or regular stamp pad inks are used for taking finger impressions. These inks as they do not dry immediately produce impression, sometimes, illegible and smudged. Moreover, when inks are not properly made with microminiature uniform particles, the papillary ridges of the finger bulb are not exactly reproduced on the recording card. This, many times, produces faulty results. Another disadvantage of the present system of fingerprint recording is that if the finger bulb is not carefully placed on the inked plate or the pads, the ink does not properly flow from the tip to the point just below the first joint. It, therefore, becomes difficult to get full impression of the thumb bulb. Another disadvantage of the present system of direct fingerprint recording is that the coloured inks leave stains on the finger bulb which needs immediate cleaning. This is an inconvenience for using this type of inks for recording finger printing impressions. Moreover, many of the ink formulations contain basic dyes which may in the long run be injurious to health also. Apart from the above disadvantages associated with inked fingerprint papers, the image developable reactive papers available in the market cannot be used for the present device as these papers are mainly used for copying purposes. The ink system used in the inkless fingerprint recording device are different from that used in image developable reactive papers. Therefore, the main objective of the present invention is to provide a process for the production of colourless ink for recording fingerprint impressions which on coming onto contact with a receptor surface, produces dark image by an electreon donor aceptor solid surface chemical reaction with the colourless reactive inks. Another objective of the present invention is to provide a process for production of inkless fignerprint recording assembly in which colourless reactive ink is prepared in a non-drying solvent medium with certain reactive dye intermediates and other supporting components, which is then kept absorbed in a suitable synthetic sponge with uniform micro porosity, which will not allow quick drying of the ink because of lesser capillary pressure. Yet another objective of the present invention is to provide an improved process for production of inkless fingerprint recording assembly, in which the fingerprint impressions are developed on a receptor surface which is coated with reactive chemicals to develop the colurless dye intermediates incorporated in the ink formulation to produce excellent image density and stability. Still another objective of the present invention is to provide a process for production of inkless fingerprint recording assembly in which colourless ink formulation and the activator surface (receptor surface) of the coated paper, are formulated in such a way that the components of the formulations have not harmful effect to the human skin. Yet another objective of the present invention is to provide an improved process for production of inkless fingerprint assembly which on use does not soil or stain the fingers as the ink itself is colourless and needs no immediate cleaning/washing of the fingers. Accordingly the present invention relates to an Inkless finger print recording system with colorless ink media comprising of (i) a colorless ink media and a reactive recording paper where in the colorless ink is kept absorbed in a micro porous synthetic sponge, the said ink composition prepared consists of 20-25 parts of a black leuco-dye derivative (s) in 100 parts by weight of a vegetative oil preferably castor oil, linseed oil along with 0.2 to 0.5 parts by wt of a colour suppressant and (ii) the inkless finger print recording paper coated with a blend consisting of (a) 1.5-3 parts of carboxymethyl cellulose, 0.5 to 5 parts of polyvinyl alcohol as binder (b) 7.5 to 15 parts precipitated silica, 2.5 to 5.5 parts bentonite clay and 15 to 25 parts acid activated Kaolin clay as oil absorber (c) 0.15 to 2 parts zinc chloride, 1.0 to 3.0 parts 3,5 dimethyl benzyl salicilate, 4.5 to 10 parts bisphenol A, 0.1 to 0.25 parts sodium hexametaphosphate in 100 parts of water and the dried coated surface is calendered by known methods. In an embodiment of the invention the leuco-dye derivatives used may be in the range of 22.5-23.3 parts. In another embodiment of the present invention a colour suppressant polyethylenimine may be used in the range 0.25-0.35 parts by weight. In yet another embodiment of the present invention carboxy methyl cellulose (medium viscosity grade) and polyvinyl alcohol (water soluble grade) may be taken 2 parts and 4 parts respectively. In still another embodiment of the present invention precipitated silica, bentonite clay and acid activated Kaolin clay, preferably 10, 3.5 & 20 parts respectively may be used as oil absorbing media having an oil absorbance 45-65 and volume average particle sizes 4.5-6.5 microns. In yet another embodiment of the present invention zinc chloride and 3,5 dimethyl benzyl salicylate, may be used in the range of 1.5 parts and 2.5 parts respectively as enhancer of the electron donor aceptor reaction. In yet another embodiment of the present invention bisphenol A in the ranges from 4.5-10 parts by weight used as a dye developing agent. In still another embodiment of the present invention 0.20 parts of sodium hexameta phosphate may be used as dispersing agent. The present invention for production of inkless fingerprint recording assembly involves following steps : preparation of colourless ink formulation and then absorption of the prepared ink in micropropous synthetic sponge, to form the colourless ink media which consists of dissolving 20-25 parts by weight of a black leuco-dye derivative in 100 parts by weight of a vegetable oil such as castor oil or linseed oil, along with 0.2-0.5 parts by weight of colour suppressant like polyethylenimine, heating the mixture to 70-80°C for complete dissolution of the dye-intermeidates and then allowing the system to cool to room temperature, thereby forming the colourless ink formulation, which is then allowed to abscorb in a microporous synthetic sponge sheets, then wrapping the sponge sheets with thin polyethylene sheet to arrest evaporation of the oil, thereby making the source of colourless ink to be used in the system. The reactive activator sheet comprises of 1.5-3 parts precipitated silica (200 mesh powder), 2.5-5.5 parts bentonite clay, 4.25-10.50 parts Bisphenol A, 0.50-5 parts polyvinyl alcohol (water soluble grade), 0.15-2 parts Zinc chloride in 100 parts of water. This composition is prepared in a ball mill till a very fine and uniform paste is obtained to coat on paper of 60-100 g/m2 thickness. The coated paper with 6-8 g/m2 coating thus produced is lightly calendered in a super calender to impart gloss and smoothness to the coated surface. The present invention provides a device for producing inkless fingerprint recording paper with colourless ink and reactive recording paper, the process for which consists of the following steps : i. Preparation of colourless ink formulation. ii. Absorption of the prepared ink in microporous synthetic sponge to form the colourless ink media to be used in the system. iii. The preparation of receptor (activator) formulation in a ball mill or such other equipment to get a very fine and uniform paste. iv. Cooking of the receptor formulation on paper surface in a coating equipment and then drying and calendering the coated paper to get a glossy and smooth surface, on which the colourless ink on coming into contact, produces dark image by an electron donor acceptor solid surface chemical reaction. The following examples are given to illustrate the invention. The examples, should not, however, be construed to limit the scope of the invention. EXAMPLE-I PREPARATION OF COLOURLESS INK Pergascript Black IBRa) or React Schwarz SF 7968b) 22.5 parts Polyethylenimine 0.35 parts (Colour suppressant) Castor oil 100 parts 'a' is a colourless leuco-dye derivative manufactured by Ciba-Geigy, Switzerland, 'b' is a colourless leuco-dye derivative manufactured by BASF, Germany. Either of the dyes (22.5 parts) and polyethylenimine (0.25 parts) are weighed and mixed with castor oil (LR grade) (100 parts) and the mixture is heated to 75°C when a clear solution of the dye-intermediate is obtained. The solution is then allowed to cool to room temperature. A piece of microporous sponge (10 x 5 x 0.5 cm) having uniform porosity is taken and dipped into the dye solution and it is allowed to stand for 5-10 minutes. When the sponge is uniformily wet with ink solution, it is taken out and the excess ink solutions adhering to the surface are wipped with a blotting paper. The sponge piece is then put inside collapsible folder like polyethylene packets. PREPARATION OF ACTIVATOR SURFACE/IMPRESSION RECORDING SURFACE .Carboxy methyl cellulose 2.0 parts (medium viscosity grade) .Precipitated silica 10.0 parts (+200 mesh powder) .Bentonite clay 3.5 parts (+200 mesh powder) .Bisphenol A 4.5 parts (+200 mesh powder) .Polyvinyl alcohol 4.0 parts (Cold water soluble grade) Zinc chloride (AR grade) 0.15 parts .Sodium hexameta phosphate 0.20 parts .Water 100 parts Carboxy methyl cellulose (2.0 parts) is dissolved in a part of water (20 parts) and so also polyvinyl alcohol (5 parts) is dissolved in another of water (20 parts). Both these solutions are mixed together. To this mixture, precipitated silica (10.0 parts) bentonite clay (3.5 parts), bisphenol A (4.5 parts) and Zinc chloride (0.15 parts) are added and put into a ball mill. To this mixture rest of the water (60.0 parts) are added and the contents are milled for sufficiently long period ot get a smooth and uniform paste. The paste thus prepared is then used for coating on paper surface in a coating machine, wherein, a dry coating weight of 6-8 g/m2 is applied on the paper. The coated paper on drying and supercalendering produces smooth and glossy surface. The coated paper is now cut into strips as per requirement for recording fingerprint impressions. Generally in single print files, the paper strip (card) contain space for separate impressions of each of the ten fingers belonging to the person concerned (to whose fingerprints are to be recorded). RECORDING OF DIRECT FINGERPRINT IMPRESSIONS For recording fingerprints, first of all the subject has to lightly press the finger bulb on the surface of the ink containing sponge when the ink in the sponge will be transferred onto the finger bulb. Now the finger bulb is pressed upon the activator surface of the impression recording sheet. The dye in oil from the sponge will immediately react with the chemicals present in the activator surface in an electron donor acceptor solid surface chemical reaction producing distinctive colour on the activator surface, thereby exhibiting the papillary ridges of the finger tips on the paper surface. The tone of the colour produced on the surface of the activator sheet will greatly depend on the type of leuco-dye derivative used in the preparation of the colourless ink composition. EXAMPLE - II PREPARATION OF COLOURLESS INK Dye-derivative, TH-109C - 23.5 parts Polyethylenimine - 0.45 parts Castor oil - 100 parts 'c' is a colourless leuco-dye derivative manufactured by Hodogaya Chemical Ltd., Tokyo, Japan. The preparation is same as in Example I. PREPARATION OF ACTIVATOR SURFACE/IMPRESSION RECORDING SURFACE Acid activated clay - 20.0 parts Precipitated silica - 10.0 parts (+200 mesh powder) Bisphenol A - 10.0 parts (+ mesh powder) Carboxymethyl cellulose - 2.0 parts (medium viscosity grade) Polyvinyl Alcohol - 4.0 parts (water) (Cold water soluble grade) Sodium hexameta phosphate - 0.2 parts 3,5 di-methyl benzyl salicylate - 2.5 parts Water 100 parts Polyvinyl alcohol (4.0 parts) is dissolved in a part of water (40 parts) and to this solution acid activated Kaolin clay (20.0 parts), precipitated silica (10.0 parts), Bisphenol A (10.0 parts) and 3,5 di-methyl benzyl salicylate (2.5 parts) and sodium hexameta phosphate (0.2 parts) are added and put into a ball mill. The mixture is now milled in the ball mill after adding rest of the water to give a thorough homogeneously mixed paste. The paste is diluted if necessary, before coating on paper. The acid activated clay was prepared by treating 500 g Kaolin clay having oil absorbance 64 and a volume average particle size 6.5 micron in 350 g of 96% sulphuric acid at 90°C for 12 h. The acid treated clay is rinsed with water till the pH comes to neutral. The coating paste as prepared above is applied onto a base paper in a coating machine to obtain a dry weight of 6-8 g/m2. The coated paper on drying and calendering produces smooth and glossy surface. The coated paper is now cut into strips as per requirement. The recording of fingerprint impressions are done as described under Example-I. The main advantages and the distinguishing features of the present invention are : i. The direct fingerprint recording system obtained by the present invention is novel in the field and with this system dark and clear image of the finger bulbs can be obtained, ii. The system is clean and harmless to the human skin and can be carried to any place in the form of a kit containing ink absorbed media and activator papers for recording. The person concerned whose finger impressions have to be taken have not to wash his/her finger after recording the impressions. 111. IV. V. The activator paper as obtained by the present invention exhibits a soft, glossy and smooth surface on supercalendering and the image development takes place immediately on lightly pressing the inked finger bulb on the paper surface. The combination of colour suppressant in the ink formulation prevents undue development of colour on long time storage of the ink in the absorbing media. Either of the activator compositions can be adopted considering the economics for producing the activator sheets and the image density obtained in both the cases is comparable. We Claim: 1. An Inkless finger print recording system with colorless ink media comprising of (i) a colorless ink media and a reactive recording paper where in the colorless ink is kept absorbed in a micro porous synthetic sponge, the said ink composition prepared consists of 20-25 parts of a black leuco-dye derivative (s) in 100 parts by weight of a vegetative oil preferably castor oil, linseed oil along with 0.2 to 0.5 parts by wt of a colour suppressant and (ii) the inkless finger print recording paper coated with a blend consisting of (a) 1.5-3 parts of carboxymethyl cellulose, 0.5 to 5 parts of polyvinyl alcohol as binder (b) 7.5 to 15 parts precipitated silica, 2.5 to 5.5 parts bentonite clay and 15 to 25 parts acid activated Kaolin clay as oil absorber (c) 0.15 to 2 parts zinc chloride, 1.0 to 3.0 parts 3,5 dimethyl benzyl salicilate, 4.5 to 10 parts bisphenol A, 0.1 to 0.25 parts sodium hexametaphosphate in 100 parts of water and the dried coated surface is calendered by known methods. 2. A system as claimed in claim 1 wherein leuco-dye derivatives are used in the range 22.5- 23.3 parts. 3. A system as claimed in claims 1 and 2 wherein a polyethylenimine used in the range 0.25-0.35 parts by weight. 4. A system as claimed in claims 1-3 wherein carboxy methyl cellulose and polyvinyl alcohol are taken 2 parts and 4 parts respectively. 5. A system as claimed in claims 1-4 wherein precipitated silica, bentonite clay and acid activated Kaolin clay, preferably 10, 3.5 & 20 parts respectively are used as oil absorbing media: 6. A system as claimed in claims 1-5 wherein Zinc chloride and 3, 5 dim ethyl benzyl salicylate, are used in the range of 1.5 parts and 2.5 parts respectively. 7. A system as claimed in claims 1-6 wherein parts of phosphate is used as agent. 8. An inkless finger print recording system with colorless ink media substantially as herein described with reference to the examples.

Documents:

303-del-2001-abstract.pdf

303-del-2001-claims.pdf

303-del-2001-correspondence-others.pdf

303-del-2001-correspondence-po.pdf

303-del-2001-description (complete).pdf

303-del-2001-form-1.pdf

303-del-2001-form-18.pdf

303-del-2001-form-2.pdf

303-del-2001-form-3.pdf