CN113180648A - Latent fingerprint developer and preparation method thereof - Google Patents

Latent fingerprint developer and preparation method thereof Download PDF

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Publication number
CN113180648A
CN113180648A CN202110466149.9A CN202110466149A CN113180648A CN 113180648 A CN113180648 A CN 113180648A CN 202110466149 A CN202110466149 A CN 202110466149A CN 113180648 A CN113180648 A CN 113180648A
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CN
China
Prior art keywords
molybdenum disulfide
perfluoroalkyl phosphate
latent fingerprint
mass
filtering
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CN202110466149.9A
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Chinese (zh)
Inventor
唐军利
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Jinduicheng Molybdenum Co Ltd
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Jinduicheng Molybdenum Co Ltd
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Priority to CN202110466149.9A priority Critical patent/CN113180648A/en
Publication of CN113180648A publication Critical patent/CN113180648A/en
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/117—Identification of persons
    • A61B5/1171—Identification of persons based on the shapes or appearances of their bodies or parts thereof
    • A61B5/1172—Identification of persons based on the shapes or appearances of their bodies or parts thereof using fingerprinting

Abstract

The invention discloses a latent fingerprint developer which comprises the following components in percentage by mass: 5-10 parts of perfluoroalkyl phosphate and 90-95 parts of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%. The invention also discloses a preparation method thereof, which comprises the steps of putting the weighed perfluoroalkyl phosphate into absolute ethyl alcohol, heating, dissolving and filtering, and keeping the temperature of filtrate at 40-50 ℃ in a closed container for later use; weighing molybdenum disulfide powder, putting the molybdenum disulfide powder into absolute ethyl alcohol, performing ultrasonic dispersion, adjusting the pH value to 6.5-7.0 by using a 30% sodium hydroxide solution, heating in a water bath at 50-60 ℃, and continuously performing ultrasonic dispersion; gradually and slowly adding the perfluoroalkyl phosphate ester ethanol solution into the obtained molybdenum disulfide ethanol solution, filtering the obtained mixed solution after continuous ultrasonic dispersion, washing with pure water, drying the solid obtained by filtering, and storing in a silica gel particle dryer. The invention can clearly develop fingerprints, has strong adhesion and obvious effect by modifying the adhesion promoter through the perfluoroalkyl phosphate ester, and has very outstanding fingerprint effect on the surfaces of metal and alloy products; by the coating of the perfluoroalkyl phosphate, the molybdenum disulfide is not easy to absorb water and agglomerate and is not easy to be oxidized.

Description

Latent fingerprint developer and preparation method thereof
Technical Field
The invention belongs to the technical field of fingerprint visualization, and particularly relates to a latent fingerprint developer and a preparation method of the latent fingerprint developer.
Background
Fingerprints are not changed and unique throughout the life, and are widely used in the fields of entry inspection, criminal search and the like. The powder method is the most common and convenient method for developing latent fingerprints, namely, various powders are brushed to a fingerprint area by a brush, and are adsorbed to fingerprint residues on mastoid lines through physical mechanical or electrostatic action, while small furrows and fingerprint carriers without fingerprint residues cannot adsorb the powders, and the final result is that the powders are adhered to the mastoid lines and form contrast with the small furrows and carriers without the adhered powders, so that the latent fingerprints are developed. The powder used to reveal latent fingerprints should satisfy several conditions: the granularity is appropriate; the adhesive force is strong; the powder is not easy to absorb water and agglomerate, the moisture absorption degree is generally less than 0.2%, and if the powder is wet, the boundary of the fingerprint lines is fuzzy and is not easy to distinguish; the color contrast is obvious; high specific gravity and strong penetrability. Fluorescent powder, magnetic powder and common powder can be generally used, wherein the fluorescent powder has small specific gravity, weak adsorption force and unsatisfactory dye-uptake effect; the magnetic powder is not suitable for objects with deeper background, and the contrast between the displayed fingerprint and the background is smaller; therefore, common powder (heavy metal powder such as gold, silver and the like) is widely used, but the common powder is easy to fly in operation, the health of a human body is influenced by inhalation, and the heavy metal such as gold, silver and the like is expensive and has high cost.
The molybdenum disulfide powder has a similar application range with gold powder, silver powder and other powders, and has a good display effect on metal products, and compared with gold powder and silver powder, the molybdenum disulfide powder is low in price, but the molybdenum disulfide powder is easy to absorb moisture, is easy to oxidize in the air, and has a fuzzy fingerprint line boundary after moisture absorption and is difficult to distinguish.
Disclosure of Invention
The invention aims to provide a latent fingerprint developer, which solves the problems that the boundary of the fingerprint lines is fuzzy and is difficult to distinguish due to the fact that the existing molybdenum disulfide powder is easy to absorb moisture and is easy to oxidize in fingerprint appearance.
The invention also aims to provide a preparation method of the latent fingerprint developer.
The technical scheme adopted by the invention is that the latent fingerprint developer consists of the following components in percentage by mass: 5-10 parts of perfluoroalkyl phosphate and 90-95 parts of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%.
The invention adopts another technical scheme that a preparation method of the latent fingerprint developer is implemented according to the following steps:
step 1, weighing the following components in percentage by mass: 5-10 parts of perfluoroalkyl phosphate and 90-95 parts of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%;
step 2, crushing the perfluoroalkyl phosphate weighed in the step 1 to 60-80 meshes, putting the crushed perfluoroalkyl phosphate into absolute ethyl alcohol, heating and dissolving the crushed perfluoroalkyl phosphate to be clear, filtering the solution, putting the filtrate into a closed container, and keeping the temperature of the filtrate at 40-50 ℃ for later use;
step 3, putting the molybdenum disulfide powder weighed in the step 1 into absolute ethyl alcohol, dispersing for 30-60 min by ultrasonic waves, adjusting the pH value to 6.5-7.0 by using 30% by mass of sodium hydroxide solution, and heating for 30-40 min in a water bath;
step 4, gradually and slowly adding the perfluoroalkyl phosphate ester ethanol solution obtained in the step 1 into the molybdenum disulfide ethanol solution obtained in the step 3, and continuously performing ultrasonic dispersion for 30-45 min;
and 5, filtering the mixed solution obtained in the step 4, washing the mixed solution for 2-3 times by using a proper amount of pure water, drying the solid obtained by filtering in a vacuum drying oven at 50-60 ℃, crushing the dried solid to form non-agglomerated blocks, and placing the non-agglomerated blocks in a silica gel particle dryer to obtain the silica gel particle-free silica gel.
The invention is also characterized in that:
in the step 1, the mass ratio of the perfluoroalkyl phosphate to the ethanol is 1: 50-80 parts.
In the step 2, the molybdenum disulfide is obtained by purifying natural mineral molybdenite, the purity is more than or equal to 95 percent, the granularity is 1-5 mu m, and the mass ratio of the molybdenum disulfide to ethanol is 1: 5 to 10.
The temperature of water bath heating in the step 3 is 50-60 ℃.
The invention has the beneficial effects that: the invention relates to a preparation method of a latent fingerprint developer, wherein the main component of the developer is molybdenum disulfide powder, and the latent fingerprint developer is prepared by coating phosphate of perfluoroalkyl groups on the surface of molybdenum disulfide, so that the developer is not easy to absorb water and agglomerate, is not easy to oxidize, and is convenient to store; the powder is not easy to fly, is safe to use, has less damage to human bodies than gold powder and silver powder, and the developing agent can clearly develop fingerprints and has high sensitivity.
Drawings
FIG. 1 is a photograph of a latent fingerprint collection of untreated molybdenum disulfide powder applied to a copper sheet;
FIG. 2 is a photograph of a latent fingerprint image of a latent fingerprint developer of the present invention applied to a copper sheet;
FIG. 3 is a photograph of a latent fingerprint collection of untreated molybdenum disulfide powder applied to a steel sheet;
FIG. 4 is a photograph of a latent fingerprint image of a latent fingerprint developer of the present invention applied to a steel sheet;
FIG. 5 is a laser particle size distribution plot of untreated molybdenum disulfide;
FIG. 6 is a laser particle size distribution plot of molybdenum disulfide after treatment with a latent fingerprint developer of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention relates to a latent fingerprint developer which comprises the following components in percentage by mass: 5-10 parts of perfluoroalkyl phosphate and 90-95 parts of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%.
The preparation method of the latent fingerprint developer is specifically implemented according to the following steps:
step 1, weighing the following components in percentage by mass: 5-10 parts of perfluoroalkyl phosphate and 90-95 parts of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%;
step 2, crushing the perfluoroalkyl phosphate weighed in the step 1 to 60-80 meshes, putting the crushed perfluoroalkyl phosphate into absolute ethyl alcohol, heating and dissolving the crushed perfluoroalkyl phosphate to be clear, filtering the solution, putting the filtrate into a closed container, and keeping the temperature of the filtrate at 40-50 ℃ for later use;
step 3, putting the molybdenum disulfide powder weighed in the step 1 into absolute ethyl alcohol, dispersing for 30-60 min by ultrasonic waves, adjusting the pH value to 6.5-7.0 by using 30% by mass of sodium hydroxide solution, and heating for 30-40 min in a water bath;
step 4, gradually and slowly adding the perfluoroalkyl phosphate ester ethanol solution obtained in the step 1 into the molybdenum disulfide ethanol solution obtained in the step 3, and continuously performing ultrasonic dispersion for 30-45 min;
and 5, filtering the mixed solution obtained in the step 4, washing the mixed solution for 2-3 times by using a proper amount of pure water, drying the solid obtained by filtering in a vacuum drying oven at 50-60 ℃, crushing the dried solid to form non-agglomerated blocks, and placing the non-agglomerated blocks in a silica gel particle dryer to obtain the silica gel particle-free silica gel.
Effect of Components in developer
1. The molybdenum disulfide powder has the characteristics of lipophilicity and hydrophobicity, and is used for clearly showing fingerprints on metal, glass, plastic and stainless steel surfaces.
2. The positive groups of the perfluoroalkyl phosphate ester are selectively and directionally adsorbed on the surface of the electronegative molybdenum disulfide particles to form a coating layer, so that the adhesive force is increased, and the surface tension of the particles is reduced; and because the particle state taking the molybdenum disulfide particles as the core generates repulsion force among particles in the presence of perfluoroalkyl phosphate and the steric hindrance effect, the agglomeration of the particles is effectively prevented. The method can improve the lipophilicity of the molybdenum disulfide powder, improve the interface compatibility with fingerprint grease, improve the affinity and ensure that the powder has good dispersibility.
When the latent fingerprint developer is used, the developer is brushed to a fingerprint area by a brush, the developer is adsorbed to fingerprint residues on mastoid lines through physical mechanical or electrostatic action, the developer cannot be adsorbed by small furrows and fingerprint carriers without the fingerprint residues, the developer is adhered to the mastoid lines and forms contrast with the small furrows and the carriers without the developer, and therefore the latent fingerprint is displayed.
The latent fingerprint developer can clearly develop fingerprints, has strong adhesion and obvious effect by modifying the adhesion promoter through the perfluoroalkyl phosphate ester, and particularly has very outstanding fingerprint effect on the surfaces of metal and alloy products; the powder has high sensitivity, can inhibit dust emission, is safe to use and has less damage to human bodies than gold powder and silver powder; by the coating of the perfluoroalkyl phosphate, the molybdenum disulfide is not easy to absorb water and agglomerate, is not easy to be oxidized and is convenient to store.
Fig. 1 is a photograph of a fingerprint collection of untreated molybdenum disulfide powder applied to a copper sheet, and fig. 3 is a photograph of a fingerprint collection of untreated molybdenum disulfide powder applied to a steel sheet, as can be seen from fig. 1 and 3: the fingerprint lines extracted from the untreated molybdenum disulfide powder have fuzzy boundaries and are difficult to distinguish; FIG. 2 is a photograph taken of a latent fingerprint applied to a copper sheet by a latent fingerprint developing agent of the present invention, and FIG. 4 is a photograph taken of a latent fingerprint applied to a steel sheet by a latent fingerprint developing agent of the present invention, as can be seen from FIGS. 2 and 4: the fingerprint lines extracted by the developer have high definition and good continuity.
Fig. 5 is a laser particle size distribution diagram of untreated molybdenum disulfide, and fig. 6 is a laser particle size distribution diagram of molybdenum disulfide after treatment with a latent fingerprint developer according to the present invention, as can be seen from fig. 5 and 6: the laser particle size distribution curve of untreated molybdenum disulfide is in non-normal distribution, and the laser particle size distribution curve of treated molybdenum disulfide is in normal distribution.
Example 1
Step 1, respectively weighing: 0.5g of perfluoroalkyl phosphate and 9.5g of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%;
step 2, crushing the perfluoroalkyl phosphate weighed in the step 1 to 60-80 meshes, putting the crushed perfluoroalkyl phosphate into 25g of absolute ethyl alcohol, heating and dissolving the mixture until the mixture is clear, filtering the mixture, and keeping the temperature of the filtrate at 40 ℃ in a closed container for later use;
step 3, putting the molybdenum disulfide powder weighed in the step 1 into 47.5g of absolute ethyl alcohol, performing ultrasonic dispersion for 30min, adjusting the pH value to 6.5-7.0 by using 30% by mass of sodium hydroxide solution, and heating for 30min under the water bath condition of 50 ℃;
step 4, gradually and slowly adding the perfluoroalkyl phosphate ester ethanol solution obtained in the step 1 into the molybdenum disulfide ethanol solution obtained in the step 3, and continuously performing ultrasonic dispersion for 30 min;
and 5, filtering the mixed solution obtained in the step 4, washing the mixed solution for 2-3 times by using a proper amount of pure water, drying the solid obtained by filtering in a vacuum drying oven at 50 ℃, crushing the dried solid to form non-agglomerated blocks, and placing the non-agglomerated blocks in a silica gel particle dryer to obtain the silica gel particle.
Example 2
Step 1, respectively weighing: 1g of perfluoroalkyl phosphate and 9g of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%;
step 2, crushing the perfluoroalkyl phosphate weighed in the step 1 to 60-80 meshes, putting the crushed perfluoroalkyl phosphate into 50g of absolute ethyl alcohol, heating and dissolving the mixture until the mixture is clear, filtering the mixture, and keeping the temperature of the filtrate at 50 ℃ in a closed container for later use;
step 3, putting the molybdenum disulfide powder weighed in the step 1 into 90g of absolute ethyl alcohol, performing ultrasonic dispersion for 60min, adjusting the pH value to 6.5-7.0 by using 30% by mass of sodium hydroxide solution, and heating for 40min under the water bath condition of 60 ℃;
step 4, gradually and slowly adding the perfluoroalkyl phosphate ester ethanol solution obtained in the step 1 into the molybdenum disulfide ethanol solution obtained in the step 3, and continuously performing ultrasonic dispersion for 45 min;
and 5, filtering the mixed solution obtained in the step 4, washing the mixed solution for 2-3 times by using a proper amount of pure water, drying the solid obtained by filtering in a vacuum drying oven at 60 ℃, crushing the dried solid to form non-agglomerated blocks, and placing the non-agglomerated blocks in a silica gel particle dryer to obtain the silica gel particle.
Example 3
Step 1, respectively weighing: 0.75g of perfluoroalkyl phosphate and 9.25g of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%;
step 2, crushing the perfluoroalkyl phosphate weighed in the step 1 to 60-80 meshes, putting the crushed perfluoroalkyl phosphate into 38g of absolute ethyl alcohol, heating and dissolving the mixture until the mixture is clear, filtering the mixture, and keeping the temperature of the filtrate at 45 ℃ in a closed container for later use;
step 3, putting the molybdenum disulfide powder weighed in the step 1 into 70g of absolute ethyl alcohol, performing ultrasonic dispersion for 45min, adjusting the pH value to 6.5-7.0 by using 30% by mass of sodium hydroxide solution, and heating for 35min under the water bath condition of 55 ℃;
step 4, gradually and slowly adding the perfluoroalkyl phosphate ester ethanol solution obtained in the step 1 into the molybdenum disulfide ethanol solution obtained in the step 3, and continuously performing ultrasonic dispersion for 38 min;
and 5, filtering the mixed solution obtained in the step 4, washing the mixed solution for 2-3 times by using a proper amount of pure water, drying the solid obtained by filtering in a vacuum drying oven at 55 ℃, crushing the dried solid to form non-agglomerated blocks, and placing the non-agglomerated blocks in a silica gel particle dryer to obtain the silica gel particle.

Claims (6)

1. The latent fingerprint developer is characterized by comprising the following components in percentage by mass: 5-10 parts of perfluoroalkyl phosphate and 90-95 parts of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%.
2. The latent fingerprint developer according to claim 1, wherein the molybdenum disulfide is purified from natural mineral molybdenite, has a purity of 95% or more and a particle size of 1 μm to 5 μm.
3. The preparation method of the latent fingerprint developer is characterized by comprising the following steps:
step 1, weighing the following components in percentage by mass: 5-10 parts of perfluoroalkyl phosphate and 90-95 parts of molybdenum disulfide powder, wherein the sum of the mass percentages of the components is 100%;
step 2, crushing the perfluoroalkyl phosphate weighed in the step 1 to 60-80 meshes, putting the crushed perfluoroalkyl phosphate into absolute ethyl alcohol, heating and dissolving the crushed perfluoroalkyl phosphate to be clear, filtering the solution, putting the filtrate into a closed container, and keeping the temperature of the filtrate at 40-50 ℃ for later use;
step 3, putting the molybdenum disulfide powder weighed in the step 1 into absolute ethyl alcohol, dispersing for 30-60 min by ultrasonic waves, adjusting the pH value to 6.5-7.0 by using 30% by mass of sodium hydroxide solution, and heating for 30-40 min in a water bath;
step 4, gradually and slowly adding the perfluoroalkyl phosphate ester ethanol solution obtained in the step 1 into the molybdenum disulfide ethanol solution obtained in the step 3, and continuously performing ultrasonic dispersion for 30-45 min;
and 5, filtering the mixed solution obtained in the step 4, washing the mixed solution for 2 to 3 times by using a proper amount of pure water, drying the solid obtained by filtering in a vacuum drying oven at the temperature of between 50 and 60 ℃, crushing the dried solid to form agglomeration-free blocks, and placing the agglomeration-free blocks in a silica gel particle dryer to obtain the silica gel particle.
4. The preparation method of the latent fingerprint developer according to claim 3, wherein the mass ratio of the perfluoroalkyl phosphate to the ethanol in the step 1 is 1: 50-80 parts.
5. The method for preparing the latent fingerprint developer according to claim 3, wherein the molybdenum disulfide in the step 2 is obtained by purifying natural mineral molybdenite, the purity is greater than or equal to 95%, the granularity is 1-5 μm, and the mass ratio of the molybdenum disulfide to ethanol is 1: 5 to 10.
6. The method for preparing latent fingerprint developer according to claim 3, wherein the temperature of the water bath heating in step 3 is 50 ℃ to 60 ℃.
CN202110466149.9A 2021-04-28 2021-04-28 Latent fingerprint developer and preparation method thereof Pending CN113180648A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1540147A (en) * 1977-09-28 1979-02-07 Secr Defence Developing latent fingerprints
JPH10155774A (en) * 1996-10-04 1998-06-16 Mikimoto Pharmaceut Co Ltd Powder for sampling fingerprint

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1540147A (en) * 1977-09-28 1979-02-07 Secr Defence Developing latent fingerprints
JPH10155774A (en) * 1996-10-04 1998-06-16 Mikimoto Pharmaceut Co Ltd Powder for sampling fingerprint

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
张丽梅等: "基于材料表面修饰技术的二硫化钼微粒悬浮液 显现胶带粘面上手印", 刑事技术, vol. 43, no. 5, pages 373 - 377 *

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