Article containing a Thixotropic Additive and Cyanoacrylate Monomer employed for developing Latent Fingerprints

United States Patent [19] Thompson et al. [54] ARTICLE CONTAINING A THIXOTROPIC ADDITIVE AND CY ANOACRYLATE MONOMER EMPLOYED FOR DEVELOPING LATENT FINGERPRINTS [75] [73] [21] [22] [60] [51] [52] [53] [56] Inventors: Richard T. Thompson, Haddam View Heights; Philip Hinkle, West Hartford, both of Conn.; Robert B. Carroll, South Paris, Me. Assignee: Loctite Corporation, Newington, ' Conn. App]. No.: 681,961 Fi1ed- Dec. 14, 1984 Division of Ser. No. 743,585 filed as PCT US 84/01354, Aug. 24, 1984, published as WO 85/00963, Mar. 14, 1985, § 102(e) date Oct. 7, 1984. Int. Cl.4 ..................... .. A61B 5/10; B41K 1/00 U.S. Cl. ................................... .. 428/35; 118/31.5; 356/71; 427/1; 428/419; 428/516 Field of Search ................. .. 427/1, 145; 118/315; 356/71; 428/35, 419, 516 References Cited U.S. PATENT DOCUMENTS 3,380,646 4/1968 Dogen et al. ....................... .. 229/57 3,502,521 3/ 1970 Dogen et al. .. 156/69 3,523,628 1/1968 Colvin et al. .. 222/107 3,524,537 8/1970 Winter . . . . . . . . . . . . . . . . .. 206/47 3,663,501 5/1972 Adams et al. .... .. .. 260/41 R 3,839,065 10/1974 Overhults et al. .. 106/308 N 3,935,993 2/1976 Dogen et al . . . . . . . . . . . .. 229/53 3,940,362 2/ 1976 Overhults ..... .. 260/42.16 4,102,945 7/1978 Gleave .......... .. 260/879 4,180,913 1/1980 Takeuchi et al. 433/228 4,297,383 10/1981 Bourdon . . . . . . . . . . . .. 427/1 4,363,286 12/1982 Leavitt .............................. .. 427/ 1 4,379,178 4/1983 Meadows et al. ................ .. 427/ 1 4,407,842 10/1983 Shepard .................... .. 427/ 1 4,461,235 7/1984 Morton ................................. .. 427/ 1 FOREIGN PATENT DOCUMENTS 56-64933 6/1981 Japan . OTHER PUBLICATIONS C.A. 100(26)211222v, Oct. 1983 Takaoka Chem. C. Abs. 100(16)122406r, Sep. 1983 Taoka Chem. Co. lox‘ . 4,550,041 Oct. 29, 1985 Patent Number: Date of Patent: [11] [45] Chem. Abs. 100(2)8087n, Jun. 1983 Kowa K.K., JP No. 58/108135. Chem. Abs. 99(24)196228s, Mar. 1983 Taoka Chem. Co., JP No. 58/41068. Chem. Abs. 96(26)218971w Taoka, Feb. 1982, JP No. 57/23666. Chem. Abs. 96(12)80693v, Nov. 1981 Taoka, JP No. 56/142169. Chem. Abs. 96(12)86692u, Nov. 1981 T aoka, JP No. 56/142168. Chem. Abs. 95(18)151873z, Jun. 1981 Toagose, JP No. 56/64933. Chem. Abs. 92(4)23838t, Seiyaku, JP No. 54/106426. Chem. Abs. 91(22)176339k, May 1979 Koatsu Gas, No. 54/ 57539. Chem. Abs. 88(6)38738g, Sep. 1977 Ashiwara, JP No. 52/ 105939. Chem. Abs. 82(8)44562g, Feb. 1974 Toagose, JP No. 74/5728. Chem. Abs. 71(16)71543(f) 1969 Korshak et al. Identification News: May ’82, pp. 3-5; Jun. ’82, pp. 3-4; Jan. ’83, pp. 9-10; Feb. ’83, pp. 3-4; Feb. ’83, pp. 12, 13, 15; May ’83, p. 10. Duraprint Investigators Report, Mar./Apr. ’83. Police Chronicle, May ’83, “New Method of Finger- printing . . . ”. Payton Scientific, Undated, Visuprint Advertisment. Police Chief, Feb. ’83, p. 9, Superprint TM ad. Primary Examiner—I-Ierbert J. Lilling Attorney, Agent, or Firm—Wa1ter J. Steinkraus; Eugene F. Miller [57] ABSTRACT Latent fingerprints are developed by exposing them to vapors generated from a thin film of a storage stable cyanoacrylate monomer and a thixotropic additive in sufficient amount to render the composition substan- tially non-flowable. The monomer film should have a surface area of at least 129 sq. cm. An envelope package for the monomer composition has inner polyethylene surfaces. The envelope may be peeled open to expose the inner surfaces coated with a film of the composition. Aug. 1979 Matsumoto 8 Claims, 3 Drawing Figures ‘*7? _\ -s ....-, 15"" ;\" /Er U.S. Patent Oct. 29, 1985 I20 20 ‘§xu“mvL\un1“1 23 K .\ 26 4,550,041 1 ARTICLE CONTAINING A THIXOTROPIC ADDITIVE AND CY ANOACRYLATE MONOMER EMPLOYED FOR DEVELOPING LATENT FINGERPRINT S BACKGROUND OF THE INVENTION * This is a division of Ser. No. 743,585 filed as PCT US 84/01354, Aug. 24, 1984, published as W0 85/00963, Mar. 14, 1985, § I02(e) date Oct. 7, 1984. To those familiar with instant adhesives, it’s no sur- prise that their vapors can expose fingerprints with the white residue caused by monomer “blooming”. In fact, efforts to reduce this undesirable behavior date from the early days of cyanoacrylate technology. However, it was left until much later to discover that this same process could be tumed to the noble task of apprehending criminals through fingerprint identifica- tion. In 1978 the Tokyo Metropolitan Police are re- ported to have hosted a demonstration of cyanoacrylate fuming for development of fmgerprints by criminolo- gists of the Japanese National Police Agency. In May of 1979, Detective Inspector N. Edmunds and L. Wood of N orthamptonshire (England) Police are reported to have observed that fingerprints were developed when they repaired a black plastic developing tank with Loc- tite Super Glue TM . Within a month, they reported their findings to a regional police conference. Constable Paul Bourdon of the North Bay Ontario: Police Force was an early practitioner of the method and invented a fuming system which generates vapor in one chamber and pumps it into another which contains the evidence under investigation. His system has been patented in the U.S. and Canada (U.S. Pat. No. 4,297,383, incorporated herein by reference). Frank Kendall of the U.S. Bureau of Alcohol, To- bacco and Firearms, developed an improvement in the method which uses cotton treated sodium hydroxide to accelerate the generation of vapors. A description of this technique is given in Identification News, June 1982, page 3. The use of heat to accelerate generation of cyanoac- rylate vapors for fingerprint development use has also been reported. Identification News, January 1983, page 9, and May 1983, page 10. The cyanoacrylate vapor technique has become an accepted method for fingerprint development. In sev- eral cases, identifications have been made on evidence for which no previous methods had been workable. Recently, evidence provided by this method has been accepted in a Kansas court leading to criminal convic- tion. Abele, Identification News, February 1983, page 12. Recognized benefits of using cyanoacrylate mono- mers to develop fmgerprints which have been discov- ered to date are as follows: (a) Development of latent prints on objects where other methods have failed; (b) development of prints on difficult surfaces such as polyethylene bags or electrical tapes; (c) print images produced are easier to handle than powder-dusted prints which may blow away; (d) large enclosed areas, such as automobile interiors can be fumed for prints. The significant benefits of the cyanoacrylate finger- print development technique, however, have been ac- companied by other notable disadvantages. These dis- advantages include the instant bonding of cyanoacry- late adhesives to skin and clothing when contacted by l0 15 20 25 30 35 40 45 50 55 60 65 2 evidence technicians. Also, the typical low viscosity cyanoacrylate adhesive used in the prior techniques is easily spilled or dripped. This not only contributes to inadvertent bonding of clothes and skin but can also result in damage to the evidence. Initially, without ac- celeration of vapor generation, it has been reported that full development of a print takes at least about five hours and can take as long as 90 days. With acceleration of vapor generation, other disad- vantages have been identified as follows: Disadvantages of Sodium Hydroxide Acceleration: 1. Sodium hydroxide is a poison and corrosive, and can cause damage to skin if not mixed wearing gloves. 2. Preparation time is substantial. 3. The technique provides a small amount of fumes for the amount of adhesive used. Most of the adhesive polymerizes, within the saturated pad or as visible white smoke, rather than being evaporated into the atmosphere within the chamber. The polymerized white smoke does not react with the latent print. . Fumes from the pads rise to the top of the chamber, then filter down, failing to provide uniform exposure of the objects being processed to the vapors. Disadvantages of Heat Acceleration: 1. Temperature setting can be critical. Too hot may result in overdevelopment of the print and failure of the adhesive to polymerize within the print. Too cool may result in failure of the adhesive to be absorbed into the chamber as quickly as desired, requiring longer processing. 2. Use in smaller chambers, even in small amounts, may result in overdevelopment if the items being pro- cessed are not closely monitored. 3. Various methods of using heat as an accelerant also heat the entire chamber, affecting vinyls and plastics (especially black vinyl tapes). 4. Minor accidents involving the use of heated objects may result in bums or damage to the chamber. SUMMARY OF THE INVENTION The present invention is an improvement of develop- ing latent fmgerprints with cyanoacrylate vapors. The method comprises subjecting an article suspected of containing a latent fingerprint to cyanoacrylate vapors generated from a thin film of a storage-stable composi- tion comprising a cyanoacrylate monomer and a thixo- tropic additive in an amount effective to render the composition substantially nonflowable on a vertical surface. This thixotropic composition is preferably also stabilized against polymerization to a degree where the adhesiveness of the composition is substantially re- duced. In a preferred embodiment of the invention, the gel composition is contained in a thin envelope or pouch which is peeled open to expose two inner surfaces coated with a thin layer of the gel. The resulting large surface area generates vapor rapidly and evenly pro- longed periods of time. This rapid and sustained vapor generation can result in development of latent fmger- prints which are not developed by prior art methods. The following advantages have been identified for the inventive process over the prior art methods of generating vapors. 1. No poisons or corrosives. 2. No preparation time. 4,550,041 3 3. Produces an even amount of exposure to the adhesive evaporated within the chamber over a 20-minute plus time period. 4. Provides evaporation from a larger surface area than previous methods. 5. Room temperature operation. No critical effects of minor variations in the temperature. No heat to destroy vinyls or plastics. . Overdevelopment does not occur in a short period of time. Items can be left in the chamber up to one hour over the amount of time required without loss of ridge detail (items, as in previous methods, should not be placed closer than 3 inches to the envelope). 8. No burns or damaged chambers. 9. No spillage of adhesive or contamination of evidence. 10. Substantially reduces complexity of cyanoacrylate use making it feasible for use in the field by minimally trained technicians. DESCRIPTION OF THE DRAWINGS FIG. It is a side sectional view of a cyanoacrylate gel containing package preferred for use in the inventive method. FIG. 2 is a bottom plan view of the package of FIG. \-.°~ 1. FIG. 3 is a pictorial view of the opened package showing cyanoacrylate coated inner surfaces exposed to the air for vapor generation. DETAILED DESCRIPTION OF THE INVENTION Cyanoacrylate Gel Formulation A high vapor pressure cyanoacrylate monomer must be utilized in order to give adequate monomer vaporiza- tion. Methyl cyanoacrylate and ethyl cyanoacrylate are the preferred monomers. Allyl cyanoacrylate and iso- propyl cyanoacrylate are suitable monomers which may also be utilized alone or in a mixture. The formulation of a storage-stable nonflowable cya- noacrylate gel has long been a difficult problem because of the ease of polymerization of the monomer. Thus, while many formulations employing typical silica thixo- tropes have been reported in the art, such compositions typically are intended to be utilized immediately or have been subsequently shown to have poor shelf stabil- ity. While it has been discovered that storage stable formulations of certain silicas highly treated with di- methyldichlorosilane can be made, the high degree of surface treatment so dramatically affects the thixotropic capability of the silica that nonflowable gels cannot be prepared. More recently, it has been discovered that certain uniquely treated silicas produce storage-stable nonflowable gel compositions. Compositions of cyano- acrylate monomers with these silicas, are described more fully in co-pending application U.S. Ser. No. 528,275, filed Aug. 31, 1983, now U.S. Pat. No. 4,477,607, the disclosure of which is incorporated herein by reference. The compositions of U.S. Ser. No. 528,275 are suitable for use in the inventive method and provided the initial embodiments of the gel used in the inventive method. Working with the initial gel formulations, it was dis- covered that the stabilizer level could be substantially increased over that typically used in cyanoacrylate adhesive formulations. Since the fingerprints are devel- oped by polymerization of monomer vapors, the level of stabilizer in the base composition was not critical. Therefore, the stabilizer level in the base composition 5 10 15 20 25 30 35 40 45 50 55 60 65 4}- could be increased to the point where adhesive bonding is significantly reduced without affecting fingerprint development performance. This is especially advanta- geous in fingerprint development since the possibilities of monomer contact are substantial. The monomer con- tainers are open and have substantial surface areas (typi- cally 2”>< 103) Thixotropic Ratio 2.5 RPM/ 20 RPM 92 92 92 60 94 88 88 % I I 8|‘5|| O\ a ~°o I O\O'\O\ lolalll 801 3.0 3.0 5.7 5.3 7.3 5.7 'Aerosil is L! trademark of DeGussa Corp. R972, R976, R805, and 200 are fumed silicas with respective treatments: dimethyldichlorosilane, octyltrimethoxysilane. and untreated. lCabosil is a trademark of Cabot Corp. N70-TS is fumed silica treated with polydi- methylsiloxane. -‘see US. Pat. No. 4.105.775. The various formulations have different monomer evaporation characteristics depending on thixotrope and level. Formulations such as C and E are preferred 4,550,041 5 for evaporation charactertistics because they give faster evaporation rates and almost total evaporation at room temperature before polymerization from thin films on polyethylene. Composition D had the slowest evapora- tion and lowest total evaporation, presumably because of the high polymer content. Generating The Vapors In order to obtain rapid and uniform vapor genera- tion at room temperature, it is desirable that the mono- mer be distributed over a large surface area. Whereas development techniques using pourable liquid mono- mers must contain the monomer in a bowl on a horizon- tal surface, the nonflowable formulations used in the inventive method do not have to be contained. They may be thinly spread on vertical surfaces, e.g., on a sheet of paper or plastic film hung on a wall, without fear of damage to evidence or personnel. A preferred package for the fingerprint developing gels is shown in FIGS. 1-3. The package generally designated by the numeral 10 is an envelope con- structed from three sheets, 12, 12a and 13 of a laminate material having a polyethylene inner surface. The lami- nate is preferably a paper/polyethylene/aluminum/- polyethylene laminate material. A bonding primer be- tween the various layers is preferably included so that the material does not delaminate when the envelope is peeled open. Three heat sealed edges 14 bond sheets 12 and 12a together. Sheet 13 is heat sealed between the end flaps 16 and 160 at the fourth end of sheets 12 and 12a, thereby forming a closed envelope structure with separable but sealed end flaps 16 and 160. Inside the envelope is a thin layer of the gel cyanoacrylate formu- lation 20. To open and use, flap 16 and 16a are pulled apart as shown in FIG. 1 and sheet 13 is tom along the fold line 22. To facilitate substrate failure along the side edges 14, the central outer portions of sheets 12 and 12a may be reinforced by an additional layer of tape or label material 23. Sheets 12 and 12a are then peeled back as shown in FIG. 3 to open the package 10 and expose the cyanoacrylate gel 20 to the air. The gel sticks to the ’ inner surfaces of both sheets 12 and 12a so that a maxi- mum surface area of cyanoacrylate monomer is ex- posed. It is recommended that the package when opened provide a monomer coated surface area of at least 20 sq. in. (129 sq. cm.), preferably 40 sq. in. (258 sq. cm.) or more. Optionally package 10 may also be supplied with a strip 24 pressure sensitive adhesive located on the outer surface of flap 16a. Strip 24 is covered with a release paper 26 which may be pulled off when the package is to be used. The exposed adhesive layer 24 may then be used to adhere the open package to a desired surface such as a wall or window. Since the cyanoacrylate monomer is in gelled form it does not run off sheets 12 and 12a even when the open package is hung vertically or upside down. Although the seal is broken when the package is first opened, the package may be closed after use and reused over several weeks before the monomer is completely polymerized or vaporized. Developing The Fingerprints For small portable evidence items a fuming chamber such as an aquarium fitted with a lid may be used. The lid contains a hanging device such as a clothes hanger or alligator clips from which the evidence is suspended. A preferred envelope 10 contains about 3-4 grams of a l0 15 20 25 30 35 45 50 55 60 65 6 gel such as in formulation F in a 6£;”>