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A kind of preparation method of core-shell structure latent fingerprint revealing powder

A core-shell structure and latent fingerprint technology, applied in the field of detection, can solve the problems of weak hydrogen bonds and difficult bonding, and achieve the effects of rapid recovery, rapid display, and large magnetic energy product.

Active Publication Date: 2019-10-18
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the hydrogen bond between PVA powder and potential fingerprint residues may be quite weak, which makes it difficult to bond between them, and in order to enhance the bonding force, the PVA particles need to be modified

Method used

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  • A kind of preparation method of core-shell structure latent fingerprint revealing powder
  • A kind of preparation method of core-shell structure latent fingerprint revealing powder
  • A kind of preparation method of core-shell structure latent fingerprint revealing powder

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] A preparation method for a core-shell structure latent fingerprint display powder, comprising the following steps:

[0041] (1) Pour 150ml of alcohol into a beaker, and put the beaker into a constant temperature water bath at 40°C;

[0042] (2) Take 8g polyvinyl alcohol, polyvinyl alcohol powder adopts polyvinyl alcohol with a degree of polymerization of 2688, slowly dissolve in the alcohol solution, stir while adding, until a white suspension is formed;

[0043] (3) Weigh 0.5g graphene and add it to the suspension, put it into an ultrasonic instrument for ultrasonic dispersion, the ultrasonic frequency is 90HZ, and the time is 15 to 20 minutes to obtain solution A;

[0044] (4) Aging the solution A for 10h, putting it into a lyophilizer until lyophilized, and obtaining the composite coating material B of graphene and polyvinyl alcohol;

[0045] (5) Weigh 8.5g of coated powder B and 16g of ferrite powder and add them to a ball mill tank for mixing, stir evenly, add ste...

Embodiment 2

[0049] A preparation method for a core-shell structure latent fingerprint display powder, comprising the following steps:

[0050] (1) Pour 150ml of alcohol into a beaker, and put the beaker into a constant temperature water bath at 40°C;

[0051] (2) Weigh 10g polyvinyl alcohol, polyvinyl alcohol powder adopts polyvinyl alcohol with a degree of polymerization of 1788, slowly dissolve in the alcohol solution, stir while adding, until a white suspension is formed;

[0052] (3) Weigh 0.5g graphene and add it to the suspension, put it into an ultrasonic instrument for ultrasonic dispersion, the ultrasonic frequency is 90HZ, and the time is 15 to 20 minutes to obtain solution A;

[0053] (4) Aging the solution A for 20h, putting it into a lyophilizer until lyophilized, obtaining graphene and polyvinyl alcohol composite coating material B;

[0054] (5) Weigh 8g of coated powder B and 16g of ferrite powder and add them to a ball mill tank for mixing, stir evenly, add steel balls, p...

Embodiment 3

[0058] A preparation method for a core-shell structure latent fingerprint display powder, comprising the following steps:

[0059] (1) Pour 150ml of alcohol into a beaker, and put the beaker into a constant temperature water bath at 40°C;

[0060] (2) Take 8g polyvinyl alcohol, polyvinyl alcohol powder adopts polyvinyl alcohol with a degree of polymerization of 2488, slowly dissolve in the alcohol solution, stir while adding, until a white suspension is formed;

[0061] (3) Weigh 1g of graphene and add it to the suspension, put it into an ultrasonic instrument for ultrasonic dispersion, the ultrasonic frequency is 90HZ, and the time is 15 to 20 minutes to obtain solution A;

[0062] (4) Aging the solution A for 10h, putting it into a lyophilizer until lyophilized, and obtaining the composite coating material B of graphene and polyvinyl alcohol;

[0063] (5) Weigh 8g of coated powder B and 14g of ferrite powder and add them to a ball mill tank for mixing, stir evenly, add stee...

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Abstract

The invention relates to a method for preparing latent fingerprint development powder with a core-shell structure. The method specifically comprises the following steps of dissolving polyvinyl alcoholin ethanol, and stirring to form white suspension; adding graphene into the white suspension and carrying out ultrasonic dispersion to obtain solution A; aging the solution A and putting into a freeze drier until the solution A is freeze-dried in order to obtain a graphene and polyvinyl alcohol composite coating material B; uniformly mixing the composite coating material B with ferrite powder, putting into a ball mill to carry out ball milling, screening the power after ball milling in a vibrating screen, and selecting powder C with the particle size being larger than or equal to 200 mesh; and uniformly mixing the powder C and coated iron powder to obtain the latent fingerprint development powder. According to the method, trace substances contained in the fingerprints are combined througha chemical method, the rapid development of the latent fingerprints is realized, the ferrite powder is added, a ball milling process is adopted, the prepared powder coats the surface of the ferrite powder, and magnetic powder is obtained through screening, so that the fingerprint powder can be recycled, and the occurrence of dust clouds is avoided.

Description

technical field [0001] The invention belongs to the technical field of detection, and in particular relates to a preparation method of a core-shell structure latent fingerprint revealing powder. Background technique [0002] Fingerprints have always been recognized as the "king of evidence" by the judiciary, because fingerprints have the following characteristics: fingerprints are unique symbols inherent in individuals, and are unique; The surface of the skin is covered with sweat and sebum, leaving traces of touch objects; the pattern of lines on the surface of the end of the fingers is neat and orderly. Therefore, fingerprints play an important evidential role in forensic science and criminal proceedings. However, as the means of committing crimes adopted by criminals become more and more concealed, the fingerprints appearing at the crime scene are often latent, and some special display methods are needed to make the lines appear. [0003] Since 1887, French doctor Auber...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F1/00A61B5/1172
Inventor 陆伟钱立伟王韬磊向震罗振益
Owner TONGJI UNIV
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