Double-coated mica powder and method for producing the same

Abstract

The application discloses double-layer coated mica powder and a preparation method thereof. The double-layer coated mica powder has a core-shell structure, and sequentially comprises a mica powder core, an amino acid coating layer and a coupling agent coating layer from inside to outside. The preparation method comprises the following steps: S1. uniformly stirring mica powder, adding inorganic coating agent, and uniformly mixing the inorganic coating agent with the mica powder to obtain mica powder containing hydroxyl groups; S2. calcining the mica powder containing hydroxyl groups in an air atmosphere to obtain powder A; S3. adding amino acid surfactant to the powder A, uniformly stirring and mixing to obtain mica powder coated with an amino acid layer; and S4. adding coupling agent to the mica powder coated with the amino acid layer, uniformly stirring and mixing to prepare a coupling agent coating layer, and drying to obtain double-layer coated mica powder. The double-layer coated mica powder prepared by the application not only has a low friction coefficient, but also has good hydrophobicity and good antibacterial effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of mica powder preparation, and particularly relates to a double-coated mica powder and a preparation method thereof. BACKGROUND

[0002] Mica powder is a non-metallic mineral, and its main component is SiO2 and Al2O3. Mica powder is a layered silicate composed of two layers of silicon-oxygen tetrahedrons sandwiching one layer of aluminum-oxygen octahedrons. Mica powder has a wide range of applications, and is currently widely used in the fields of coatings, cosmetics, plastics, electronics, rubber, refractory materials, welding rods, and the ceramic industry.

[0003] Due to the layered structure of mica powder, its specific surface area is relatively large, and its surface energy is as high as 2400-2500 erg / cm 2 , which is several times or even dozens of times that of other powders. For example, the surface energy of calcium carbonate is 65-70 erg / cm 2 , the surface energy of graphite is 110 erg / cm 2 , the surface energy of titanium dioxide is 650 erg / cm 2 , the surface energy of quartz is 780 erg / cm 2 , and the surface energy of aluminum oxide is 1900 erg / cm 2 . The greater the surface energy of an object, the more difficult it is to modify and coat the surface.

[0004] At present, there are many patents on the surface modification and coating of mica powder in China. In patent CN111269462A, the inventors use a wet treatment method to add a small amount of coupling agent and a large amount of water-based polyacrylate solution to mica powder, ultrasonic dispersion, then dropwise addition of hydrochloric acid and sodium chloride solution, and drying to obtain modified lipophilic mica powder. In this patent, a large amount of polyacrylate is used to modify the mica powder, and a large amount of polyacrylate forms a film on the surface of the mica powder. After drying, the modified mica powder has the problems of poor skin feel, dryness, and poor hydrophobicity. In patent CN105153759A, the inventors crush mica powder, add a titanate coupling agent, and directly dry-pulverize the mixture, then dry at 80-95 DEG C to obtain modified mica powder. The titanate coupling agent used in this patent has poor thermal stability and is easily decomposed at high temperatures. Moreover, the skin feel and antibacterial effect of the powder treated with the titanate coupling agent are poor. SUMMARY

[0005] In order to solve the above problems, the application provides a double-coated mica powder and a preparation method thereof. The mica powder is modified by double-coating, the surface energy of the mica powder is reduced by dry treatment, and then the mica powder is treated by amino acid surfactant and silane coupling agent in steps to prepare the double-coated mica powder. The friction coefficient (improve skin adhesion), hydrophobic property and antibacterial property of the mica powder are greatly improved.

[0006] The first aspect of the application provides a double-coated mica powder, which has a core-shell structure and sequentially comprises a mica powder core, an amino acid coating layer and a coupling agent coating layer from inside to outside.

[0007] The second aspect of the application provides a preparation method of the double-coated mica powder, comprising the following steps:

[0008] S1. Stirring the mica powder uniformly, adding an inorganic coating agent, and mixing the inorganic coating agent with the mica powder uniformly to obtain a mica powder containing hydroxyl groups;

[0009] S2. Calcining the mica powder containing hydroxyl groups in an air atmosphere to obtain a powder A;

[0010] S3. Adding an amino acid surfactant to the powder A, stirring and mixing uniformly to obtain a mica powder coated with an amino acid layer;

[0011] S4. Adding a coupling agent to the mica powder coated with an amino acid layer, stirring and mixing uniformly to prepare a coupling agent coating layer, and drying to obtain a double-coated mica powder.

[0012] In an embodiment of the application, in step S1, the inorganic coating agent is added in a spraying manner. It should be noted that the inorganic coating agent can also be added in a conventional operation method in the art, which can uniformly distribute the inorganic coating agent on the surface of the powder. Here, the spraying manner is used to better uniformly distribute the inorganic coating agent on the surface of the powder.

[0013] In an embodiment of the application, in step S1, the inorganic coating agent is one or more of acidic silica sol, alkaline silica sol, neutral silica sol, acidic aluminum sol, alkaline aluminum sol and neutral aluminum sol, preferably neutral silica sol and / or neutral aluminum sol, and more preferably neutral aluminum sol. The inorganic coating agent mainly provides hydroxyl groups to prepare the mica powder containing hydroxyl groups.

[0014] In an embodiment of the application, in step S1, the amount of the inorganic coating agent is 0.1-10 Wt% of the mica powder, preferably 1-8 Wt%, and more preferably 2-6 Wt%.

[0015] In one embodiment of the present application, in step S1, the particle size of the inorganic coating agent is 40-120 nm, preferably 60-100 nm, and more preferably 80 nm.

[0016] In one embodiment of the present application, the calcination in step S2 is performed in a muffle furnace. It is worth mentioning that the equipment used for the calcination is not limited, as long as high-temperature calcination can be achieved. After calcination, the hydroxyl group is more firmly attached to the surface of the mica powder, so that the surface of the mica powder can be reduced.

[0017] In one embodiment of the present application, the calcination temperature in step S2 is 400-800℃, and preferably 600℃.

[0018] In one embodiment of the present application, the calcination time in step S2 is 1-8 hours, preferably 3-5 hours, and more preferably 4 hours.

[0019] In one embodiment of the present application, in step S3, the amino acid surfactant is added in a spraying manner. It is worth mentioning that the method of adding the amino acid surfactant can also be a conventional operation method in the art, which can uniformly spray the amino acid surfactant on the surface of the powder, so that the coating is uniform.

[0020] In one embodiment of the present application, step S3 is specifically: transferring the powder A into a stirrer, slowly stirring, spraying the amino acid surfactant into the stirrer in a spraying manner, stirring for a period of time, and obtaining the mica powder coated with an amino acid layer. The amino acid surfactant can react with the hydroxyl group on the surface of the powder A, and then form an amino acid coating layer.

[0021] In one embodiment of the present application, the stirring for a period of time is 1-8 hours, and preferably 3-5 hours.

[0022] In one embodiment of the present application, in step S3, the amino acid surfactant is one or more of sodium lauroyl sarcosinate, sodium lauroyl glutamate, sodium cocoyl glutamate, potassium cocoyl glycinate, sodium stearoyl glutamate, disodium stearoyl glutamate, and sodium lauroyl lysine, and preferably sodium lauroyl glutamate and / or sodium lauroyl lysine. The sodium salt and potassium salt in the amino acid surfactant react with the hydroxyl group on the surface of the powder A and are separated, and the free amino acid in the amino acid surfactant is adsorbed on the surface of the mica powder, and then forms an amino acid coating layer.

[0023] In one embodiment of the present application, in step S3, the amount of the amino acid surfactant is 0.1-5 Wt% of the mica powder, and preferably 1-3 Wt%.

[0024] In one embodiment of the present application, in step S4, the coupling agent is added by spraying. It is worth mentioning that the coupling agent can also be added by other conventional methods, which can ensure that the coupling agent is evenly sprayed on the surface of the powder, so that the coating is uniform.

[0025] In one embodiment of the present application, in step S4, the drying device is not limited, as long as it can achieve the purpose of drying.

[0026] In one embodiment of the present application, in step S4, the coupling agent is sprayed onto the mica powder coated with the amino acid layer, stirred for a period of time, dried in an oven at 100-120°C, and then cooled to obtain a double-coated mica powder.

[0027] In one embodiment of the present application, the stirring time is 1-12 hours, preferably 3-5 hours.

[0028] In one embodiment of the present application, the coupling agent in step S4 is one or more of octyltrimethoxysilane, octyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, dodecyltrimethoxysilane, and dodecyltriethoxysilane, preferably octyltrimethoxysilane and / or dodecyltrimethoxysilane.

[0029] In one embodiment of the present application, the amount of the coupling agent in step S4 is 0.1-5 Wt% of the mica powder, preferably 1-4 Wt%.

[0030] The present application has the following advantages:

[0031] Firstly, the present application uses a dry process to avoid the complicated process of dehydration, drying, and crushing in the wet coating process.

[0032] Secondly, in the present application, the inorganic coating agent is first sprayed onto the surface of the mica powder, and then sintered at high temperature to reduce the surface energy of the mica powder and firmly adhere the hydroxyl groups to the surface of the mica powder. Then, the amino acid surfactant is sprayed in and stirred. The amino acid surfactant reacts with the hydroxyl groups on the surface of the mica powder to form amino acid, which can be tightly coated on the surface of the mica powder to reduce the friction coefficient, thereby improving the skin feel and smooth feel, and also having good antibacterial effect.

[0033] Thirdly, the coupling agent is coated on the mica powder by the second re-coating process, which can provide good hydrophobic property to the mica powder. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1The hydrophobic angle test diagram of the double-layer coated mica powder prepared in Embodiment 6 of the present application is shown in the following. DETAILED DESCRIPTION

[0035] The present application will be further described in conjunction with specific embodiments so that those skilled in the art can better understand and implement the present application. However, the embodiments are not intended to limit the present application. The embodiments described below can be combined with each other or with any of the technical features to form new embodiments.

[0036] In the present application, the materials and equipment used in the embodiments are commercially available, except for the specifically described.

[0037] Embodiment 1

[0038] The present embodiment provides a preparation method of double-layer coated mica powder, and the specific steps are as follows:

[0039] S1. 100 g of mica powder was added to a stirrer and slowly stirred to be uniform to obtain powder A;

[0040] S2. 2 g of 80 nm neutral aluminum sol was sprayed into S1 by spraying to obtain powder B;

[0041] S3. The obtained powder B was transferred into a muffle furnace and calcined at 600 ℃ under air atmosphere for 4 hours. After cooling, powder C was obtained;

[0042] S4. Powder C was transferred into a stirrer and slowly stirred. 1 g of sodium lauroyl glutamate was sprayed into the stirrer by spraying, and stirred for 5 hours to obtain powder D;

[0043] S5. 1 g of octyltrimethoxysilane was sprayed into powder D by spraying, and stirred for 5 hours to obtain powder E;

[0044] S6. Powder E was dried in an oven at 100-120 ℃. After cooling, a double-layer coated mica powder was obtained.

[0045] Embodiment 2

[0046] The present embodiment provides a preparation method of double-layer coated mica powder, and the specific steps are as follows:

[0047] S1. 100 g of mica powder was added to a stirrer and slowly stirred to be uniform to obtain powder A;

[0048] S2. 4 g of 80 nm neutral aluminum sol was sprayed into S1 by spraying to obtain powder B;

[0049] S3. The obtained powder B was transferred into a muffle furnace and calcined at 600 ℃ under air atmosphere for 4 hours. After cooling, powder C was obtained;

[0050] S4. The powder C is transferred into a stirrer, slowly stirred, 1g of sodium lauroyl glutamate is sprayed into it in a spraying manner, stirred for 5 hours to obtain powder D;

[0051] S5. 1g of octyltrimethoxysilane is sprayed into the powder D in a spraying manner, stirred for 5 hours to obtain powder E;

[0052] S6. The powder E is dried in an oven at 100-120°C, and a double-layer coated mica powder is obtained after cooling.

[0053] Example 3

[0054] The embodiment provides a preparation method of a double-layer coated mica powder, and specific steps are as follows:

[0055] S1. 100g of mica powder is added into a stirrer, slowly stirred to obtain powder A;

[0056] S2. 6g of 80nm neutral aluminum sol is sprayed into S1 in a spraying manner to obtain powder B;

[0057] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C under an air atmosphere for 4 hours, and cooled to obtain powder C;

[0058] S4. The powder C is transferred into a stirrer, slowly stirred, 1g of sodium lauroyl glutamate is sprayed into it in a spraying manner, stirred for 5 hours to obtain powder D;

[0059] S5. 1g of octyltrimethoxysilane is sprayed into the powder D in a spraying manner, stirred for 5 hours to obtain powder E;

[0060] S6. The powder E is dried in an oven at 100-120°C, and a double-layer coated mica powder is obtained after cooling.

[0061] Example 4

[0062] The embodiment provides a preparation method of a double-layer coated mica powder, and specific steps are as follows:

[0063] S1. 100g of mica powder is added into a stirrer, slowly stirred to obtain powder A;

[0064] S2. 6g of 80nm neutral aluminum sol is sprayed into S1 in a spraying manner to obtain powder B;

[0065] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C under an air atmosphere for 4 hours, and cooled to obtain powder C;

[0066] S4. The powder C is transferred into a stirrer, slowly stirred, 2g of sodium lauroyl glutamate is sprayed into it, stirred for 5 hours to obtain powder D;

[0067] S5. 1g of octyltrimethoxysilane is sprayed into the powder D, stirred for 5 hours to obtain powder E;

[0068] S6. The powder E is dried in an oven at 100-120°C, and a double-layer coated mica powder is obtained after cooling.

[0069] Example 5

[0070] The embodiment provides a preparation method of a double-layer coated mica powder, and the specific steps are as follows:

[0071] S1. 100g of mica powder is added into a stirrer, slowly stirred to obtain powder A;

[0072] S2. 4g of 80nm neutral aluminum sol is sprayed into S1 to obtain powder B;

[0073] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C for 4 hours in an air atmosphere, and cooled to obtain powder C;

[0074] S4. The powder C is transferred into a stirrer, slowly stirred, 3g of sodium lauroyl glutamate is sprayed into it, stirred for 5 hours to obtain powder D;

[0075] S5. 1g of octyltrimethoxysilane is sprayed into the powder D, stirred for 5 hours to obtain powder E;

[0076] S6. The powder E is dried in an oven at 100-120°C, and a double-layer coated mica powder is obtained after cooling.

[0077] Example 6

[0078] The embodiment provides a preparation method of a double-layer coated mica powder, and the specific steps are as follows:

[0079] S1. 100g of mica powder is added into a stirrer, slowly stirred to obtain powder A;

[0080] S2. 4g of 80nm neutral aluminum sol is sprayed into S1 to obtain powder B;

[0081] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C for 4 hours in an air atmosphere, and cooled to obtain powder C;

[0082] S4. The powder C is transferred into a stirrer, slowly stirred, 2g of lauroyl glutamic acid sodium is sprayed into it in a spraying manner, stirred for 5 hours to obtain powder D;

[0083] S5. 2g of octyl trimethoxysilane is sprayed into the powder D in a spraying manner, stirred for 5 hours to obtain powder E;

[0084] S6. The powder E is dried in an oven at 100-120°C, and a double-layer coated mica powder is obtained after cooling.

[0085] Example 7

[0086] The embodiment provides a preparation method of a double-layer coated mica powder, and the specific steps are as follows:

[0087] S1. 100g of mica powder is added into a stirrer, slowly stirred to obtain powder A;

[0088] S2. 4g of 80nm neutral aluminum sol is sprayed into S1 in a spraying manner to obtain powder B;

[0089] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C for 4 hours in an air atmosphere, and cooled to obtain powder C;

[0090] S4. The powder C is transferred into a stirrer, slowly stirred, 2g of lauroyl glutamic acid sodium is sprayed into it in a spraying manner, stirred for 5 hours to obtain powder D;

[0091] S5. 3g of octyl trimethoxysilane is sprayed into the powder D in a spraying manner, stirred for 5 hours to obtain powder E;

[0092] S6. The powder E is dried in an oven at 100-120°C, and a double-layer coated mica powder is obtained after cooling.

[0093] Example 8

[0094] The embodiment provides a preparation method of a double-layer coated mica powder, and the specific steps are as follows:

[0095] S1. 100g of mica powder is added into a stirrer, slowly stirred to obtain powder A;

[0096] S2. 4g of 80nm neutral aluminum sol is sprayed into S1 in a spraying manner to obtain powder B;

[0097] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C for 4 hours in an air atmosphere, and cooled to obtain powder C;

[0098] S4. The powder C is transferred into a stirrer, slowly stirred, 2g of sodium lauroyl glutamate is sprayed into it, and stirred for 5 hours to obtain powder D;

[0099] S5. 2g of octyltrimethoxysilane is sprayed into the powder D, and stirred for 5 hours to obtain powder E;

[0100] S6. The powder E is dried in an oven at 100-120°C, and cooled to obtain a double-layer coated mica powder.

[0101] Example 9

[0102] The embodiment provides a preparation method of a double-layer coated mica powder, and the specific steps are as follows:

[0103] S1. 100g of mica powder is added into a stirrer, slowly stirred, and uniformly obtained as powder A;

[0104] S2. 4g of 80nm neutral aluminum sol is sprayed into S1 to obtain powder B;

[0105] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C for 4 hours in an air atmosphere, and cooled to obtain powder C;

[0106] S4. The powder C is transferred into a stirrer, slowly stirred, 2g of sodium lauroyl glutamate is sprayed into it, and stirred for 5 hours to obtain powder D;

[0107] S5. 2g of octyltrimethoxysilane is sprayed into the powder D, and stirred for 5 hours to obtain powder E;

[0108] S6. The powder E is dried in an oven at 100-120°C, and cooled to obtain a double-layer coated mica powder.

[0109] Example 10

[0110] The embodiment provides a preparation method of a double-layer coated mica powder, and the specific steps are as follows:

[0111] S1. 100g of mica powder is added into a stirrer, slowly stirred, and uniformly obtained as powder A;

[0112] S2. 4g of 80nm neutral aluminum sol is sprayed into S1 to obtain powder B;

[0113] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C for 4 hours in an air atmosphere, and cooled to obtain powder C;

[0114] S4. The powder C is transferred into a stirrer, slowly stirred, 2g of lauroyl glutamic acid sodium is sprayed into it in a spraying manner, stirred for 5 hours to obtain powder D;

[0115] S5. 2g of dodecyl trimethoxysilane is sprayed into the powder D in a spraying manner, stirred for 5 hours to obtain powder E;

[0116] S6. The powder E is dried in an oven at 100-120°C, and a double-layer coated mica powder is obtained after cooling.

[0117] Example 11

[0118] The embodiment provides a preparation method of a double-layer coated mica powder, and the specific steps are as follows:

[0119] S1. 100g of mica powder is added into a stirrer, slowly stirred to obtain powder A;

[0120] S2. 4g of 80nm neutral silica sol is sprayed into S1 in a spraying manner to obtain powder B;

[0121] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C for 4 hours in an air atmosphere, and cooled to obtain powder C;

[0122] S4. The powder C is transferred into a stirrer, slowly stirred, 2g of lauroyl glutamic acid sodium is sprayed into it in a spraying manner, stirred for 5 hours to obtain powder D;

[0123] S5. 2g of dodecyl trimethoxysilane is sprayed into the powder D in a spraying manner, stirred for 5 hours to obtain powder E;

[0124] S6. The powder E is dried in an oven at 100-120°C, and a double-layer coated mica powder is obtained after cooling.

[0125] Example 12

[0126] The embodiment provides a preparation method of a double-layer coated mica powder, and the specific steps are as follows:

[0127] S1. 100g of mica powder is added into a stirrer, slowly stirred to obtain powder A;

[0128] S2. 4g of 80nm neutral silica sol is sprayed into S1 in a spraying manner to obtain powder B;

[0129] S3. The obtained powder B is transferred into a muffle furnace, calcined at 600°C for 4 hours in an air atmosphere, and cooled to obtain powder C;

[0130] S4. The powder C is transferred into a stirrer, and 2 g of lauroyl lysine sodium is sprayed into the powder C slowly under stirring for 5 hours to obtain a powder D;

[0131] S5. 2 g of dodecyltrimethoxysilane is sprayed into the powder D under stirring for 5 hours to obtain a powder E;

[0132] S6. The powder E is dried in an oven at 100-120 ℃, and a double-layer coated mica powder is obtained after cooling.

[0133] Comparative Example 1

[0134] The present comparative example provides a mica powder, which is different from the mica powder of Example 1 in that the mica powder is not subjected to coating modification treatment.

[0135] Performance test

[0136] (1) Coefficient of friction test: the coefficient of friction refers to the ratio of the friction force between two surfaces and the vertical force acting on one surface thereof, which is related to the roughness of the surface and is independent of the size of the contact area. According to the nature of motion, the coefficient of friction is divided into dynamic coefficient of friction and static coefficient of friction. The static coefficient of friction and the dynamic coefficient of friction are determined by an MXD-02 coefficient of friction instrument. Specifically, one sample is fixed on an experimental plate, and another sample is fixed on a special sliding block. Then, the sliding block is placed on the central part of the first sample on the test plate according to the specific operation steps, and the test directions of the two samples are parallel to the sliding direction, and the force measuring system is not under stress. After the test starts, the sliding block slides on the sample at a standard specified test speed for a certain distance, and the reading of the coefficient of friction instrument is read. The higher the static coefficient of friction and the dynamic coefficient of friction, the greater the friction force, which means that the surface of the powder is rougher, and the sliding feeling is relatively worse. Table 1 shows the test results of the static coefficient of friction and the dynamic coefficient of friction of the mica powders prepared in Examples 1-14 and Comparative Example.

[0137] (2) Hydrophobicity test: measuring the contact angle of water droplets and powder is a common method for representing the hydrophobicity of powder. The SZ-CAMD3 contact angle measuring instrument is used for measurement. An appropriate amount of mica powder is pressed into a cake using a mold, and the measurement is carried out according to the operation steps of the measuring instrument. The larger the contact angle, the better the hydrophobicity of the silica powder. Table 2 shows the test results of the hydrophobicity of the mica powders prepared in Examples 1-14 and Comparative Example. The test results of the hydrophobicity of the mica powder prepared in Example 6 are shown in Table 2. Figure 1

[0138] ​(3) Bacteriostatic effect test: according to the specific morphology and culture characteristics of bacteria and mold, 1 g of mica powder was taken, bacteria were cultured on nutrient agar medium at 37°C for 48 hours, and mold was cultured on a tiger red medium at 28°C for 72 hours, and the number of bacteria and mold grown was calculated. The calculation method: first count the number of bacteria and mold colonies grown on each plate, and calculate the average number of colonies per dilution. The determination result: select the plate count within the range of 5-50 colonies, multiply by the dilution factor (10 times), and the number of bacteria and mold contained in each g (or each mL) of the sample is obtained. Table 3 is the bacteriostatic effect test results of the mica powder prepared in Examples 1-14 and Comparative Examples.

[0139] The following Tables 1-3 are the effect tests of Examples 1-14 and Comparative Examples, mainly testing the change of the friction coefficient (including static friction coefficient and dynamic friction coefficient), hydrophobic effect and bacteriostatic effect of the double-coated mica powder.

[0140] Table 1 Test results of static friction coefficient and dynamic friction coefficient of mica powder prepared in Examples 1-14 and Comparative Example 1

[0141]

[0142] In Table 1, it can be seen from Examples 2, 4 and 5 that with the increase of amino acid surfactant, the static friction coefficient and the dynamic friction coefficient show a trend from rapid decline to tend to be flat, indicating that amino acid can significantly reduce the friction coefficient of mica powder, achieving the purpose of increasing the sliding feeling of mica powder. In the above examples, when the amount of amino acid surfactant is 2Wt% of mica powder, it is the optimal ratio.

[0143] From Examples 1 to 3, it can be seen that with the increase of inorganic coating agent, the static friction coefficient and the dynamic friction coefficient show a trend from rapid decline to slow, indicating that inorganic coating agent will also affect the coating efficiency of mica powder to some extent. With the increase of inorganic coating agent, the hydroxyl group attached to the surface of mica powder after calcination will also increase, which helps the generation of amino acid, and further affects the friction coefficient of mica powder. However, when the amount of inorganic coating agent increases to a certain amount, there is no space on the surface of mica powder to accommodate too much hydroxyl group, resulting in overflow of hydroxyl group, and further leading to waste of inorganic coating agent. From the above examples, when the amount of inorganic coating agent is 4Wt% of mica powder, it is the optimal ratio.

[0144] From the comparison of Examples 4, 6 and 7, the friction coefficient changes little, indicating that the amount of coupling agent has little effect on the friction coefficient.

[0145] From the comparison of Example 6 and Example 8, the friction coefficient of the mica powder prepared by using neutral aluminum sol is smaller than that prepared by using neutral silicon sol, which indicates that the effect of using neutral aluminum sol is better than that of using neutral silicon sol.

[0146] From the comparison of Example 6 and Example 9, the friction coefficients are basically the same, and the effect of sodium lauroyl glutamate is equivalent to that of sodium lauroyl lysine, which indicates that the amino acid surfactant has little effect on the friction coefficient of the modified mica powder.

[0147] From the comparison of Example 6, Example 13 and Example 14, when the particle size of the inorganic coating agent is 40 nm and 120 nm, the friction coefficient is larger than that when the particle size of the inorganic coating agent is 80 nm, which indicates that when the particle size of the inorganic coating agent is too large or too small, the coating effect of the mica powder is affected. This is because when the particle size of the inorganic coating agent is too large, it is easy to precipitate, and when the particle size of the inorganic coating agent is too small, its surface energy is large, which is not conducive to the surface coating of the amino acid. Therefore, when the particle size of the inorganic coating agent is 80 nm, it is the optimal particle size.

[0148] Table 2 Hydrophobicity test results of the mica powder prepared in Example 1-Example 14 and Comparative Example

[0149]

[0150] From the comparison of Example 4, Example 6 and Example 7, when the amount of the coupling agent increases, the hydrophobic angle shows a trend of rapid growth first and then tends to be flat, which indicates that the coupling agent has a great influence on the hydrophobicity. When the amount of the coupling agent increases, the hydrophobic angle increases, and when the amount increases to a certain extent, the hydrophobic angle changes little, which indicates that the coating is relatively complete, and the coupling agent overflows. Therefore, when the amount of the coupling agent is 2 wt% of the mica powder, it is the optimal proportion.

[0151] From the comparison of Example 2, Example 4 and Example 5, when the amount of the amino acid surfactant increases, the hydrophobic angle shows a trend of rapid growth first and then tends to be flat, which indicates that the amino acid surfactant will affect the hydrophobicity to a certain extent. When the amount of the amino acid surfactant increases, the hydrophobic angle increases, but when the amount reaches a certain extent, the hydrophobic angle changes little, which indicates that the amino acid coated on the surface of the powder is already relatively large, and further increase will result in overflow. Therefore, when the amount of the amino acid surfactant is 2 wt% of the mica powder, it is the optimal proportion.

[0152] From the comparison of Example 1 to Example 3, with the increase of the inorganic coating agent, the hydrophobicity is basically unchanged, which indicates that the inorganic coating agent has little effect on the hydrophobicity of the mica powder.

[0153] From the comparison of Example 6 and Example 8, the hydrophobic angles are basically the same, which indicates that the effect of the neutral aluminum sol is equivalent to that of the neutral silicon sol.

[0154] From the comparison of Example 6 and Example 9, the hydrophobic angle is basically consistent, indicating that the effect of sodium lauroyl glutamate is comparable to that of sodium lauroyl lysine.

[0155] From the comparison of Example 6, Example 13 and Example 14, the particle size of the inorganic coating agent has a certain influence on the hydrophobicity of the final mica powder. When the particle size of the inorganic coating agent is too small or too large, it will affect the attachment of hydroxyl groups, thereby affecting the coupling effect of the coupling agent, and finally resulting in a difference in hydrophobicity. Therefore, when the particle size of the inorganic coating agent is 80 nm, it is the optimal particle size.

[0156] Table 3: Bacteriostatic effect test results of the mica powder prepared in Example 1-Example 14 and Comparative Example

[0157]

[0158]

[0159] In Table 3, from the comparison of Example 2, Example 4 and Example 5, with the increase of the amino acid surfactant, the total number of bacteria and the total number of mold have a tendency to decrease obviously, and when the amount reaches a certain amount, the bacteriostatic effect tends to be stable, so when the amount of amino acid surfactant is 2Wt% of the mica powder, it is the optimal proportion.

[0160] From the comparison of Example 1 to Example 3, with the increase of the inorganic coating agent, the total number of bacteria and the total number of mold do not change, indicating that the amount of inorganic coating agent has no effect on the bacteriostatic effect of the mica powder.

[0161] From the comparison of Example 4, Example 6 and Example 7, with the increase of the coupling agent, the total number of bacteria and the total number of mold do not change, indicating that the amount of coupling agent has no effect on the bacteriostatic effect of the mica powder.

[0162] From the comparison of Example 6, Example 13 and Example 14, the particle size of the inorganic coating agent will affect the bacteriostatic effect of the final mica powder. When the particle size of the inorganic coating agent is too large or too small, it is not conducive to the coating of amino acids, thereby causing the bacteriostatic performance to decrease. Therefore, when the particle size of the inorganic coating agent is 80 nm, it is the optimal particle size.

[0163] From the above determination of the friction coefficient (Table 1), the hydrophobicity (Table 2, Figure 1 ) and the bacteriostatic effect (Table 3) of the double-coated mica powder, Example 6 has the best effect, i.e. when the particle size of the inorganic coating agent is 80 nm, the amount of inorganic coating agent is 4Wt% of the mica powder, the amount of amino acid surfactant is 2Wt% of the mica powder, and the amount of coupling agent is 2Wt% of the mica powder, the performance and cost are optimal in combination.

[0164] The above merely describes preferred specific embodiments of the present application, and the protection scope of the present application is not limited thereto. Any person skilled in the art, according to the technical solution and the improvement concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, and should be covered within the protection scope of the present application.

Claims

1. A double-coated mica powder, characterized by, The double-layer coated mica powder has a core-shell structure, from inside to outside, the mica powder core, the amino acid coating layer, and the coupling agent coating layer. The preparation method of the double-layer coated mica powder comprises the following steps: S1. uniformly stirring the mica powder, adding an inorganic coating agent, and uniformly mixing the mica powder to obtain a mica powder containing hydroxyl groups; S2. calcining the mica powder containing hydroxyl groups in an air atmosphere to obtain powder A; S3. adding an amino acid surfactant to the powder A, and uniformly stirring and mixing to obtain a mica powder coated with an amino acid layer; S4. adding a coupling agent to the mica powder coated with an amino acid layer, uniformly stirring and mixing to prepare a coupling agent coating layer, and drying to obtain a double-layer coated mica powder; The inorganic coating agent is one or more of acidic silica sol, alkaline silica sol, neutral silica sol, acidic aluminum sol, alkaline aluminum sol, or neutral aluminum sol; The amount of the inorganic coating agent is 0.1-10wt% of the mica powder; The particle size of the inorganic coating agent ranges from 40nm to 120nm; The amount of the amino acid surfactant is 0.1-5wt% of the mica powder; The amount of the coupling agent is 0.1-5wt% of the mica powder.

2. The double-coated mica powder according to claim 1, characterized in that, In step S1, the inorganic coating agent is added in a spraying manner.

3. The double-coated mica powder according to claim 1, characterized in that, In step S2, the calcination temperature is 400-800℃, and the time is 2-8h.

4. The double-coated mica powder according to claim 1, characterized in that, In step S3, the amino acid surfactant is one or more of sodium lauroyl sarcosinate, sodium lauroyl glutamate, sodium cocoyl glutamate, potassium cocoyl glycinate, sodium stearoyl glutamate, disodium stearoyl glutamate, and sodium lauroyl lysine.

5. The double-coated mica powder according to claim 1, characterized in that, In step S3, the amino acid surfactant is added in a spraying manner; and / or, in step S4, the coupling agent is added in a spraying manner.

6. The double-coated mica powder according to claim 1, characterized in that, In step S4, the coupling agent is one or more of octyltrimethoxysilane, octyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, dodecyltrimethoxysilane, and dodecyltriethoxysilane.

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