CN111363471A - A kind of artificial fingerprint liquid and its preparation method and application - Google Patents

Abstract

An artificial fingerprint solution and a preparation method and application thereof, comprising the following steps: mixing lactic acid, pure acetic acid and deionized water for ultrasound; adding sodium chloride, sodium dihydrogen phosphate and urea, and continuously mechanically stirring after ultrasound to obtain a clear liquid; Take the clear liquid, add PDMS, an organic solvent, squalene, cholesterol, and stearic acid after ultrasonic continuous mechanical stirring to obtain an artificial fingerprint liquid mother liquor; the PDMS is a hydroxyl-terminated polydimethylsiloxane, and the organic solvent is Propylene glycol methyl ether; take the mother liquor, add nanoparticles, ultrasonically and continuously mechanically stir to obtain an artificial fingerprint solution. The binding force between the artificial fingerprint liquid and the surface of the substrate is similar to the binding force between the human fingerprint and the substrate, and has good stability. After the artificial fingerprint liquid is pressed on the surface of the substrate for several weeks, the fingerprint can still be easily observed. Macroscopically, the shape is similar to that of the human fingerprint after being pressed for several weeks.

Description

A kind of artificial fingerprint liquid and its preparation method and application

technical field

The invention belongs to the technical field of new chemical materials, and in particular relates to an artificial fingerprint solution and a preparation method and application thereof.

Background technique

Glass is widely used in products such as mobile phone screens, display screens, and optical lenses, but problems such as fingerprint (skin oil) residues often occur during use. These residues not only affect the aesthetics of the glass surface, but also the transparency and gloss of the glass surface. Therefore, more and more researchers have carried out research on the fingerprint resistance of glass surfaces. Fingerprint resistance makes the surface of the material self-cleaning or easy to clean, which can provide users with a beautiful interactive interface.

Although some progress has been made in the fingerprint resistance properties of material surfaces, the quantification of human fingerprint residues on surfaces has not been fully studied, and fingerprint tests performed by most researchers are qualitative and subjective because of different environmental conditions and different skin conditions. The residual composition of human fingerprints varies greatly under different conditions, which will lead to large errors in the characterization of the fingerprint resistance of the material surface. At present, the fingerprint liquid used in the fingerprint resistance test reported in the literature mainly considers that the surface energy of the fingerprint liquid is similar to the human body fluid in the real fingerprint, but the composition is very different from the human fingerprint. For example, Linda Y.L. Wu et al. (Wu LY L, Ngian S K, Chen Z, et al. Quantitative test method for evaluation of anti-fingerprint property of coated surfaces[J]. Applied Surface Science, 2011, 257(7):2965-2969 .) The surface of the artificial fingerprint liquid made of PDMS, propylene glycol methyl ether, nano-silica particles and other substances can be close to the human body fluid in the real fingerprint, and it is proposed that the contact angle of this artificial fingerprint liquid is greater than 90°, and the surface is completely anti-fingerprint. . In the actual test, it is found that this is not the case, and the composition of the artificial fingerprint liquid is very different from the composition of the human body fluid in the real fingerprint, which will cause deviations in the test results. Under the condition of ensuring surface energy, viscosity, and nanoparticle content, the invention adds substances such as squalene, cholesterol, stearic acid, etc., so that the surface energy and composition of the artificial fingerprint liquid are closer to the human body fluid in the real fingerprint, and can The human fingerprint is simulated more realistically, the cost is low, and the preparation is simple.

SUMMARY OF THE INVENTION

The technical problem solved: In view of the fact that the fingerprint residue is not easy to quantify in the research process of the current researchers on the fingerprint resistance of the material surface, which leads to a large deviation in the characterization results, an artificial fingerprint solution and a preparation method and application thereof of the present invention quantify the results. Fingerprints remain during the fingerprint resistance test and can be used to evaluate the fingerprint resistance of materials.

Technical scheme: a preparation method of artificial fingerprint liquid, characterized in that the preparation method comprises the following steps: (1) 3-5 parts of lactic acid with a mass concentration of 85%, 5-7 parts of pure acetic acid and 40-43 parts of deionized Mix with water and ultrasonicate for 3-5min to obtain a solution with a pH value of 3-6; (2) add 1 part of sodium chloride, 1 part of sodium dihydrogen phosphate and 2-3 parts of urea to the clear solution obtained in step (1). , use a cell crusher to pulverize at a power of 130w for 10-20 seconds, then ultrasonically disperse the liquid for 3-5min, and then continuously mechanically stir for 4-6h to obtain a clear liquid; (3) Take 3-5 parts of the clear liquid in step (2), Add 1-5 parts of PDMS, 2-5 parts of organic solvent, 1-2 parts of squalene, 1-2 parts of cholesterol, 2-3 parts of stearic acid, ultrasonic for 3-5min and continuous mechanical stirring for 5-10h to obtain artificial fingerprints liquid mother liquor; the PDMS is hydroxyl-terminated polydimethylsiloxane, and the organic solvent is propylene glycol methyl ether; (4) take the mother liquor in step (3), add nanoparticles with a particle diameter of 4-70 nm, until the nanometer The mass fraction of particles is 0.1-3%, crushed by a cell crusher with a power of 130w for 10-20 seconds, and then ultrasonically dispersed for 3-5min, and then continuously mechanically stirred for 1-2h to obtain an artificial fingerprint solution.

Preferably, the above-mentioned nanoparticles are silica, diatomaceous earth or alumina powder.

The artificial fingerprint liquid prepared by the above preparation method.

The surface energy of the artificial fingerprint liquid is 30-40 mJ/m ² , and the surface energy of the real human fingerprint liquid is 20-50 mJ/m ² .

The application of the above artificial fingerprint solution in the detection of the fingerprint resistance performance of materials.

The contact angle of water droplets on the glass surface after the above-mentioned artificial fingerprint solution is coated is 36-42°, and the contact angle of water droplets on the surface of the aluminum alloy sheet after the artificial fingerprint solution is coated is 40-42°. The contact angle of water droplets on the plastic surface is 38-41°.

The specific steps of the above-mentioned application are: first mechanically stir the fingerprint liquid for 15 minutes, then dip the wet end with a rubber fingerprint seal that simulates human thumb fingerprints, and press the seal to the substrate required for testing under the pressure of 5N/ ^cm2 . The surface of the seal can be removed after the residence time of 1-2s, and then the fingerprint resistance performance can be characterized. The size of the end of the seal is a square of 1cm×1cm.

The above artificial fingerprint solution increases the mass fraction of nanoparticles when simulating the residual fingerprint of a finger that has just been in contact with dust, and reduces the mass fraction of nanoparticles when simulating the residual fingerprint of a washed finger.

Beneficial effects: (1) the preparation method proposed by the present invention is simple in process, easy to obtain raw materials, and low in cost; (2) the artificial fingerprint solution prepared by the present invention, for 5 microliters of deionized water, is pressed on the glass surface of the artificial fingerprint solution. The contact angle is 36-42°. For 5 microliters of deionized water, the contact angle of the aluminum sheet surface pressed by the artificial fingerprint solution is 40-42°, which is close to the contact angle of water on the human fingerprint. (3) The present invention replaces dirt, skin care product residues, sterols and other substances in human fingerprint residues on the surface of the material with nanoparticles, and artificial sweat replaces glycerin, fatty acids and other substances in human fingerprint residues. The wettability of water droplets on the surface of the fingerprint solution, combined with optical microscope observation, was used as the evaluation criterion to judge whether the artificial fingerprint solution was representative. (4) Through the addition of nanoparticles, the pressing effect of human fingerprints on the surface of the substrate can be simulated under different conditions. For example, for freshly washed hands, there are few fingerprint residues, and the solid content of nanoparticles can be appropriately reduced during simulation; after touching some dirt or just after applying skin care products, the solid content of nanoparticles can be appropriately increased, while ultrasonic crushing and The mechanical stirring time is appropriately extended. (5) The binding force between the artificial fingerprint liquid of the present invention and the surface of the substrate is similar to the binding force between the human fingerprint and the substrate, and has good stability. Fingerprints can still be easily observed after the artificial fingerprint liquid is pressed on the surface of the substrate for several weeks. Through optical microscope observation, the liquid of the fingerprint can hardly be found, but the solid nanometers still exist. Macroscopically, it is similar to the human fingerprint after being pressed for several weeks. (6) The traditional fingerprint test uses human finger pressing. Different testers, different pressing forces, and different test time periods will affect the fingerprint residue. The present invention characterizes the fingerprint resistance performance of the material more rigorously by quantifying the fingerprint liquid, pressing area and pressure.

Description of drawings

Fig. 1 is the photomicroscope magnified 100 times of artificial fingerprint liquid residue among the embodiment 2;

Fig. 2 is the artificial fingerprint liquid residual industrial camera magnified 1.5 times photo in embodiment 2;

Fig. 3 is the photomicroscope magnified 100 times of artificial fingerprint liquid residue among the embodiment 7;

Fig. 4 is the artificial fingerprint liquid residual industrial camera magnified 4.5 times photo in embodiment 7;

FIG. 5 is a 1.5 times magnified photograph of an industrial camera of the residue of artificial fingerprint liquid in Example 7. FIG.

Detailed ways

Example 1

At room temperature, 3 parts of lactic acid with a mass concentration of 85%, 5 parts of pure acetic acid and 40 parts of deionized aqueous solution were dispersed and mixed by ultrasonic for 5 minutes, and then 10 parts of sodium chloride, 3 parts of urea, and 10 parts of disodium hydrogen phosphate were added, and the cells were used. The crusher was crushed with a power of 130w for 20 seconds, and the liquid was ultrasonically dispersed for 5 minutes and then mechanically stirred for 30 minutes to obtain a clear liquid. This liquid is characterized by a pH between 3-5. Take the above 12 parts of liquid, add dropwise 9 parts of propylene glycol methyl ether, 9 parts of PDMS, 1 part of squalene, 1 part of cholesterol, 2 parts of stearic acid, and mechanically stir for 5 hours to obtain an artificial fingerprint liquid mother solution. Take 10 parts of the above solution, add nano-silica particles with a diameter of 4-70nm until the mass fraction of nanoparticles is 1%, use a cell crusher to pulverize at a power of 130w for 20 seconds, and then ultrasonically disperse the liquid for 5min, and mechanically stir for 2h to obtain Artificial fingerprint liquid. The artificial fingerprint liquid obtained in this way is cheap, and can simulate the pressing residue of human fingerprints under normal circumstances. Compared with the fingerprint liquid mentioned in the literature to test the fingerprint resistance of the material, the composition is closer to that of human body fluids, and it can more realistically simulate the dirt residue in the fingerprint.

Example 2

The artificial fingerprint solution in Example 1 was mechanically stirred for 15 min, and poured evenly on the sponge in the seal groove. Dip the artificial fingerprint solution in the seal groove with the fingerprint seal, and the area of the fingerprint seal is about 1cm ² . Press the fingerprint seal on the glass substrate, and apply a pressure of 5N on the fingerprint seal to make the pressure reach about 5N/cm ² and stay for 2s. The contact angle of water droplets remaining in the artificial fingerprint solution was measured by a contact angle measuring instrument to be 36-42°. After 30 minutes, the residual fingerprints on the substrate were observed with an optical microscope. This test method is suitable for general fingerprint resistance testing, and the pressing method in this embodiment can be used when testing the fingerprint resistance of materials. Figures 1 and 2 are fingerprint residues in Example 2. It can be seen from the figure that compared with Figure 3, the fingerprint stains in Figure 1 are more uniformly dispersed, and there is no obvious concentrated distribution of contaminants, which can more reasonably simulate the distribution of sebum, dirt, etc. Fingerprint resistance is more reasonable.

Example 3

At room temperature, 4 parts of lactic acid with a mass concentration of 85%, 5 parts of pure acetic acid and 45 parts of deionized aqueous solution were dispersed and mixed by ultrasonic for 5 minutes, and then 10 parts of sodium chloride, 3 parts of urea, and 10 parts of disodium hydrogen phosphate were added, using The cell crusher was crushed with a power of 130w for 20 seconds, and the liquid was ultrasonically dispersed for 5 minutes and then mechanically stirred for 30 minutes to obtain a clear liquid. This liquid is characterized by a pH between 3-5. The above 10 parts of liquid were added dropwise to 2 parts of propylene glycol methyl ether, 2 parts of PDMS, 1 part of squalene, 2 parts of cholesterol, and 3 parts of stearic acid, and mechanically stirred for 5 hours to obtain an artificial fingerprint liquid mother solution. Take 10 parts of the above solution, add nano-silica particles with a diameter of 4-70nm until the mass fraction of nanoparticles is 1%, use a cell crusher to pulverize at a power of 130w for 20 seconds, and then ultrasonically disperse the liquid for 5min, and mechanically stir for 2h to obtain Artificial fingerprint liquid.

Example 4

At room temperature, 3 parts of lactic acid with a mass concentration of 85%, 5 parts of pure acetic acid and 45 parts of deionized aqueous solution were dispersed and mixed by ultrasonic for 5 minutes, and then 10 parts of sodium chloride, 3 parts of urea, and 10 parts of disodium hydrogen phosphate were added, and the cells were used. The crusher was crushed with a power of 130w for 20 seconds, and the liquid was ultrasonically dispersed for 5 minutes and then mechanically stirred for 30 minutes to obtain a clear liquid. This liquid is characterized by a pH between 3-5. 9 parts of propylene glycol methyl ether and 9 parts of PDMS were added dropwise to the above 12 parts of artificial sweat, 1 part of squalene, 1 part of cholesterol, and 3 parts of stearic acid were mechanically stirred for 5 hours to obtain an artificial fingerprint liquid mother solution. Take 10 parts of the above solution, add nano-diatomite particles with a diameter of 50-70nm until the mass fraction is 1%, use a cell crusher to pulverize at a power of 130w for 20 seconds, and then ultrasonically disperse it for 5min to obtain an artificial fingerprint solution.

Example 5

At room temperature, 3 parts of lactic acid with a mass concentration of 85%, 5 parts of pure acetic acid and 45 parts of deionized aqueous solution were dispersed and mixed by ultrasonic for 5 minutes, and then 8 parts of sodium chloride, 4 parts of urea, and 9 parts of disodium hydrogen phosphate were added. The crusher was crushed with a power of 130w for 20 seconds, and the liquid was ultrasonically dispersed for 5 minutes and then mechanically stirred for 30 minutes to obtain a clear liquid. This liquid is characterized by a pH between 3-5. The above 10 parts of artificial sweat were added dropwise to 2 parts of propylene glycol methyl ether and 2 parts of PDMS, 1 part of squalene, 1 part of cholesterol and 2 parts of stearic acid were mechanically stirred for 5h to obtain an artificial fingerprint liquid mother solution. Take 10 parts of the above solution, add nano-diatomite particles with a diameter of 50-70nm until the mass fraction is 1%, use a cell crusher to pulverize at a power of 130w for 20 seconds, and then ultrasonically disperse the liquid for 5min and mechanically stir for 2h to obtain artificial Fingerprint fluid.

Example 6

The artificial fingerprint solution in Example 5 was mechanically stirred for 15 min, and poured evenly on the sponge in the seal groove. Dip the artificial fingerprint solution in the seal groove with the fingerprint seal, and the area of the fingerprint seal is about 1cm ² . Press the fingerprint seal on the glass substrate, apply a weight of 5N on the fingerprint seal, make the pressure reach about 5N/ ^cm2 , and stay for 2s. The contact angle of water droplets remaining in the artificial fingerprint solution was measured by a contact angle measuring instrument to be 45-52°. After 30 minutes, the residual fingerprints on the substrate were observed with an optical microscope.

Example 7

(1) At room temperature, 3 parts of lactic acid with a mass concentration of 85%, 5 parts of pure acetic acid and 45 parts of deionized aqueous solution were dispersed and mixed by ultrasonic for 5 minutes, and then 8 parts of sodium chloride, 4 parts of urea, and 9 parts of disodium hydrogen phosphate were added. , using a cell crusher to crush for 20 seconds at a power of 130w, and then ultrasonically disperse the liquid for 5 minutes and then mechanically stir for 30 minutes to obtain a clear liquid. This liquid is characterized by a pH between 3-5. The above 10 parts of artificial sweat were added dropwise to 2 parts of propylene glycol methyl ether and 2 parts of PDMS, 2 parts of squalene, 2 parts of cholesterol, and 3 parts of stearic acid were mechanically stirred for 5 hours to obtain an artificial fingerprint liquid mother solution. Take 10 parts of the above solution, add nano-silica particles with a diameter of 50-70nm until the mass fraction is 2.5%, use a cell crusher to pulverize at a power of 130w for 20 seconds, and then ultrasonically disperse the liquid for 5min and mechanically stir for 2h to obtain artificial Fingerprint fluid. This situation can simulate the residual situation of fingerprint pressing when the finger is contaminated with dust or stains.

(2) Pour the artificial fingerprint solution in (1) evenly on the sponge in the seal groove. Dip the artificial fingerprint solution in the seal groove with the fingerprint seal, and the area of the fingerprint seal is about 1cm ² . Press the fingerprint stamp on the glass substrate, apply 5N pressure on the fingerprint stamp, make the pressure reach about 5N/cm ² , and stay for 2s. The contact angle of water droplets remaining in the artificial fingerprint solution was measured by a contact angle measuring instrument to be 51-53°. After 30 minutes, the residual fingerprints on the substrate were observed with an optical microscope. Figures 3, 4, and 5 are fingerprint residues in Example 7. Compared with Fig. 1, Fig. 3, 4, 5 due to the increase of nano-silicon dioxide content in the fingerprint liquid, lead to more residues and more concentrated distribution of simulated fingerprint pressing stains, which can simulate the fingerprint pressing when the finger is contaminated with dust or stains. residual situation.

Claims (8)

1. A preparation method of an artificial fingerprint liquid, characterized in that the preparation method comprises the following steps: (1) 3-5 parts of 85% lactic acid by mass concentration, 5-7 parts of pure acetic acid and 40-43 parts of deionized water Mixing, after ultrasonication for 3-5min, a solution with pH value of 3-6 is obtained; (2) 1 part of sodium chloride, 1 part of sodium dihydrogen phosphate and 2-3 parts of urea are added to the clear solution obtained in step (1), Use a cell crusher to pulverize at a power of 130w for 10-20 seconds, then ultrasonically disperse the liquid for 3-5min, and then continuously mechanically stir for 4-6h to obtain a clear liquid; (3) Take 3-5 parts of the clear liquid in step (2), add 1-5 parts of PDMS, 2-5 parts of organic solvent, 1-2 parts of squalene, 1-2 parts of cholesterol, 2-3 parts of stearic acid, ultrasonic for 3-5min and continuous mechanical stirring for 5-10h to obtain artificial fingerprint solution Mother liquor; the PDMS is hydroxyl-terminated polydimethylsiloxane, and the organic solvent is propylene glycol methyl ether; (4) take the mother liquor in step (3), add nanoparticles with a particle diameter of 4-70 nm, until the nanoparticles The mass fraction is 0.1-3%, crushed by a cell crusher with a power of 130w for 10-20 seconds, and then ultrasonically dispersed for 3-5min, and then continuously mechanically stirred for 1-2h to obtain an artificial fingerprint solution. 2. The artificial fingerprint solution according to claim 1 and the preparation method thereof, characterized in that the nanoparticle is silicon dioxide, diatomaceous earth or alumina powder. 3. The artificial fingerprint solution obtained by the preparation method of claim 1 or 2. 4 . The artificial fingerprint solution according to claim 3 , wherein the surface energy of the artificial fingerprint solution is 30-40 mJ/m ² , and the surface energy of the real human fingerprint solution is 20-50 mJ/m ² . 5. The application of the artificial fingerprint solution of claim 3 in the detection of fingerprint resistance of materials. 6. application according to claim 5, it is characterized in that the glass surface water drop contact angle after described artificial fingerprint liquid coating is 36-42 °, the aluminum alloy sheet surface water drop contact angle after described artificial fingerprint liquid coating is is 40-42°, and the contact angle of water droplets on the plastic surface after the artificial fingerprint liquid is coated is 38-41°. 7. application according to claim 5, it is characterized in that the concrete steps of application are: first to fingerprint liquid mechanical stirring 15min, dipping the rubber fingerprint seal of simulating human thumb fingerprint at the end part of dipping again, at pressure 5N/cm Under the conditions of ² , press the seal to the surface of the substrate to be tested, and take it off after a residence time of 1-2 s to carry out the fingerprint resistance performance characterization. The size of the end of the seal is a square of 1 cm × 1 cm. 8. The application according to claim 5, characterized in that the artificial fingerprint solution increases the nanoparticle mass fraction when simulating a finger that has just been in contact with dust to press the fingerprint residue; when simulating the clean finger pressing the fingerprint residue, the nanoparticle is reduced. quality score.

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