Silicone micropowder, method for producing the same, and use thereof

Abstract

The present application relates to the technical field of optical materials, and discloses silicone micro powder, a preparation method and application thereof. The disclosed silicone micro powder is composed of a plurality of polysiloxane microspheres, the relative smoothness of the surface of each polysiloxane microsphere is R, 1.02≤R≤1.30, wherein R=Rq / Ra, Rq is the root mean square surface roughness of the polysiloxane microsphere, and Ra is the average surface roughness of the polysiloxane microsphere; the relative size uniformity of the silicone micro powder is RSU, RSU=1-φ / d 2 ≥0.992, wherein φ is the variance of the diameter of the silicone micro powder, and d is the average diameter of the silicone micro powder. The silicone micro powder has high light utilization, high light transmittance, and good uniformity of light scattering and diffusion; when applied to light diffusion materials, the light control precision is high, the light transmittance and diffusion are good, the light transmittance and brightness are higher; and when used as a raw material for forming a coating, the formed coating has good flatness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical materials, in particular to a silicone micro powder and a preparation method and application thereof. BACKGROUND

[0002] Point light source is the main light-emitting form of LED light source, which is prone to problems such as glare and spotlight, and directly used for indoor lighting can cause damage to the human eye. The shell material for LED lighting, i.e. light scattering material, is a material that can both transmit light and effectively scatter light, which can convert point and line light sources into line and area light sources. The two main indicators for evaluating light scattering materials are light transmittance and haze. To achieve a soft and uniform light effect, the light scattering material is generally required to have a light transmittance of more than 80% and a haze of more than 90%. In order to cope with the rapid development of the LED lighting industry, the production of shell materials must be continuous and high-yield. Therefore, most new light scattering materials are prepared by blending transparent polymer matrix materials and light diffusers. Common light scattering material matrixes mainly use transparent polymers such as polycarbonate (PC), polystyrene (PS), transparent polyolefin materials, polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), etc.

[0003] The commonly used light diffusers at present are mainly inorganic or silicone micro powders. The microspheres of inorganic components as light diffusers often improve the haze by greatly reducing the light transmittance, which affects the optical performance; in the process of back-end application, the microspheres of inorganic components have poor compatibility with the polymer matrix and are prone to agglomeration, which is not conducive to the mechanical properties of the material; the microspheres of inorganic components have high hardness and can cause wear to the processing equipment during processing. Therefore, the microspheres of inorganic components as light diffusers have obvious disadvantages.

[0004] Silicone light diffusers are a kind of materials that have attracted widespread attention in recent years, and their application potential in the field of optics is highly regarded. It is a material that can change the path of light propagation, and by improving the transmission and scattering characteristics of light, it can improve the utilization and uniformity of light. The current silicone diffusers applied to light scattering materials are also difficult to meet the requirements of high light transmittance and haze at the same time.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide a silicone micro powder and a preparation method and application thereof, aiming to improve at least one problem mentioned in the background art.

[0007] The present application is implemented as follows:

[0008] In a first aspect, the present application provides a silicone micro powder composed of a plurality of polysiloxane microspheres, each polysiloxane microsphere having a relative smoothness R of 1.02≤R≤1.30, wherein R=Rq / Ra, Rq is the root mean square surface roughness of the polysiloxane microsphere, and Ra is the average surface roughness of the polysiloxane microsphere;

[0009] The relative size uniformity of the silicone micro powder is RSU, RSU=1-φ / d 2 ≥0.992, wherein φ is the variance of the diameter of the silicone micro powder, and d is the average diameter of the silicone micro powder.

[0010] In an optional embodiment, each polysiloxane microsphere has a root mean square surface roughness Rq≤120 nm and an average surface roughness Ra≤100 nm.

[0011] In an optional embodiment, each polysiloxane microsphere has a root mean square surface roughness 48 nm≤Rq≤101.1 nm and an average surface roughness 38 nm≤Ra≤97.2 nm.

[0012] In an optional embodiment, at least one of the following features (1) and (2) is included:

[0013] (1) The average diameter d of the silicone micro powder is 0.5-10 μm;

[0014] (2) The polysiloxane microspheres in the silicone micro powder have a maximum diameter of d max , a minimum diameter of d min , and (d max -d min ) / d×100%≤20%.

[0015] In a second aspect, the present application provides a method for preparing a silicone micro powder, comprising:

[0016] providing a hydrolysis solution, the hydrolysis solution being obtained by reacting siloxane and water at a mass ratio of 1:3-20, the hydrolysis solution having a conductivity of 3-20 μS / cm;

[0017] providing a mixed solution, the hydrolysis solution and a base being mixed at a temperature of ≤0 ℃ to obtain a mixed solution having a pH of 9-11.5;

[0018] raising the temperature of the mixed solution to a polycondensation temperature of 40-60 ℃, the temperature of the mixed solution being controlled to reach the polycondensation temperature within ≤60 s during the temperature raising process, so that the substances in the mixed solution undergo a polycondensation reaction, and a solid-liquid mixture containing polysiloxane microspheres is obtained after the reaction is completed;

[0019] extracting the polysiloxane microspheres from the solid-liquid mixture to obtain the silicone micro powder.

[0020] In optional embodiments, at least one of the following features (1) to (7) is also included:

[0021] (1) The siloxane is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane and vinyltrimethoxysilane;

[0022] (2) The hydrolysate and alkali are mixed at -5~0℃;

[0023] (3) The heating rate of the mixture to the polycondensation temperature is 60~100℃ / min;

[0024] (4) The base is selected from at least one of sodium hydroxide and potassium hydroxide;

[0025] (5) The reaction temperature of siloxane and water is 20~30℃, and the reaction time is 0.5~3h;

[0026] (6) The alkali is mixed with the hydrolysate in the form of an alkali solution. The mixing method is as follows: the alkali solution is divided into multiple batches and mixed with the hydrolysate batch by batch.

[0027] (7) The method of extracting polysiloxane microspheres from solid-liquid mixture includes: solid-liquid separation of solid-liquid mixture, and washing and drying the obtained solid.

[0028] In an optional embodiment, the conductivity of the hydrolysate is 4~15 μS / cm.

[0029] Thirdly, the present invention provides a light scattering material, comprising organosilicon micropowder as described in any of the foregoing embodiments or organosilicon micropowder prepared by any of the foregoing embodiments.

[0030] Fourthly, the present invention provides a silica powder, which is obtained by calcining organosilicon micro powder;

[0031] The organosilicon micro powder is the organosilicon micro powder as described in any of the foregoing embodiments or the organosilicon micro powder prepared by any of the foregoing embodiments.

[0032] Fifthly, the present invention provides a copper-clad laminate whose constituent components include silicon dioxide powder as described in the foregoing embodiments.

[0033] The present invention has the following beneficial effects:

[0034] The organosilicon micropowder provided by this invention has a relative surface smoothness R of microspheres satisfying 1.02 ≤ R ≤ 1.30. Within this range, the surface of the microspheres is guaranteed to be smoother. Smooth organosilicon micropowder can reduce irregular reflection and scattering of light on the particle surface, thereby improving light utilization efficiency and light transmittance. Microspheres with high surface smoothness exhibit high sphericity, meaning that the particle size is more uniform in all directions, which is conducive to uniform scattering and diffusion of light and avoids the generation of obvious light spots or dark areas. The more microspheres with high sphericity in the powder, the more times the light is deflected on the surface of the spheres, and the more regular the reflection angle. The light diffusion materials prepared with it have higher haze, better performance, and lower addition amount. The relative size uniformity (RSU) of organosilicon micropowder is ≥0.992. Its high uniformity means that its particle size distribution is narrow, the light transmission control is highly precise, and the light transmittance and diffusion are good. The narrower the particle size distribution, the more uniform the scattering of light in the material is ensured, reducing the reflection and refraction of light inside the material, thereby improving the light transmittance and brightness, and realizing more precise light transmission control. Microspheres with narrow particle size distribution are more likely to form a smooth surface during coating or molding processes, reducing surface defects. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 Here is a SEM image of the organosilicon micropowder prepared in Example 1;

[0037] Figure 2 Here is a SEM image of the organosilicon micropowder prepared in Example 2;

[0038] Figure 3 Here is a SEM image of the organosilicon micropowder prepared in Example 8;

[0039] Figure 4 Atomic force microscope 2D and 3D images of the organosilicon micropowder prepared in Example 8;

[0040] Figure 5 The image shows the SEM image of the organosilicon micropowder prepared in Comparative Example 1.

[0041] Figure 6 SEM image of the organosilicon micropowder prepared in Comparative Example 2;

[0042] Figure 7 The image shows the SEM image of the organosilicon micropowder prepared in Comparative Example 4.

[0043] Figure 8 SEM image of the silicone micro powder prepared for Comparative Example 6. DETAILED DESCRIPTION

[0044] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. If specific conditions are not indicated in the embodiments, conventional conditions or conditions suggested by manufacturers are adopted. If the reagents or instruments used are not indicated by manufacturers, they are all conventional products that can be purchased in the market.

[0045] The terms involved in the present application are explained as follows:

[0046] Rq (root mean square roughness): the root mean square value of the profile deviation from the average line within the sampling length. It is a statistical parameter of surface roughness, reflecting the fluctuation of surface height.

[0047] Ra (profile arithmetic average deviation): the arithmetic average value of the absolute value of the distance of each point on the measured profile from the reference line within the sampling length. It is a commonly used index of surface roughness, reflecting the characteristics of the micro-geometric shape of the surface.

[0048] When the values of Rq and Ra are closer, it means that the height fluctuation of the surface is smaller, i.e. the roughness of the surface is lower. This is because Rq and Ra are both parameters used to describe the surface roughness, but they measure the unevenness of the surface from different angles:

[0049] Rq reflects the root mean square value of the surface height, while Ra reflects the arithmetic mean value of the surface height; if the two values are close, it means that the height fluctuation of the surface is within a small range, and the surface is relatively smooth.

[0050] Relative size uniformity RSU of the silicone micro powder, RSU = 1-φ / d 2 wherein φ is the variance of the diameter of the silicone micro powder, and d is the average diameter of the silicone micro powder.

[0051] The larger the RSU value is, the narrower the particle size distribution is, which means that the consistency of the particle size is better. It should be noted that variance is a special term in applied mathematics, and in the present application, the variance of the silicone micro powder is the average of the square of the difference between each diameter and the average diameter of the microspheres.

[0052] The features and properties of the present application will be further described in detail below in combination with the embodiments.

[0053] The organic silica powder provided by the present application is composed of a plurality of polysiloxane microspheres, the relative roundness of the surface of each polysiloxane microsphere is R, 1.02≤R≤1.30, wherein R=Rq / Ra, Rq is the root mean square surface roughness of the polysiloxane microsphere, and Ra is the average surface roughness of the polysiloxane microsphere.

[0054] The relative size uniformity of the organic silica powder is RSU, RSU=1-φ / d2≥0.992, wherein φ is the variance of the diameter of the organic silica powder, and d is the average diameter of the organic silica powder.

[0055] The relative roundness of the surface of the microspheres of the organic silica powder provided by the present application is R, which satisfies 1.02≤R≤1.30. When the relative roundness is within the range, the surface of the microspheres is smoother. The organic silica powder with a smooth surface can reduce irregular reflection and scattering of light on the surface of the particles, thereby improving the utilization efficiency of light and the light transmittance. The microspheres with high surface smoothness have high sphericity, which means that the size of the particles in each direction is more uniform, which is conducive to uniform scattering and diffusion of light and avoids the generation of obvious light spots or dark areas. The more the microspheres with high sphericity in the powder, the more the number of deflection of light on the surface of the spheres, and the more regular the reflection angle. The light diffusion material prepared by using the organic silica powder has higher haze, and the use effect is better, and the addition amount is reduced. The relative size uniformity of the organic silica powder is RSU, RSU=1-φ / d2≥0.992. The uniformity is high, which means that the particle size distribution is narrow, the light transmission control precision is high, and the light transmittance and diffusivity are good. The narrower the particle size distribution, the more uniform the scattering of light in the material, which reduces the reflection and refraction of light in the material, thereby improving the light transmittance and brightness and realizing more precise light transmission control. The microspheres with narrow particle size distribution are more likely to form a smooth surface in the coating or molding process, and the surface defects are reduced.

[0056] Therefore, the organic silica powder provided by the present application has a relative roundness and a relative size uniformity within the range required by the present application, which can ensure that the organic silica powder has a high light utilization rate, a high light transmittance, and good uniformity of light scattering and diffusion. When the organic silica powder is applied to a light diffusion material, the light control precision is high, the light transmittance and diffusivity are good, and the light transmittance and brightness are higher. When the organic silica powder is used as a raw material for forming a coating, the coating has good flatness.

[0057] Optionally, in order to further improve the optical performance of the organic silica powder, the root mean square surface roughness of each polysiloxane microsphere is Rq≤120nm, and the average surface roughness is Ra≤100nm.

[0058] Optionally, in order to further improve the optical performance of the organic silica powder, the root mean square surface roughness of each polysiloxane microsphere is 48nm≤Rq≤101.1nm, and the average surface roughness is 38nm≤Ra≤97.2nm.

[0059] Optionally, to further make the silicone micro powder have better optical performance, the average diameter d of the silicone micro powder is 0.5-10 μm.

[0060] The prior art view is that the smaller the particle diameter in the silicone micro powder, the more the number of particles in the same mass, the more the light is deflected when passing through, the greater the diffusion is generated, and the higher the haze is. However, when the particle diameter is too small, the particle size distribution is difficult to control, and the transmittance will decrease slightly under the same haze. Therefore, when the average diameter d of the silicone micro powder is 0.5-10 μm, the powder haze value is high and the transmittance is good.

[0061] Optionally, to further make the silicone micro powder have better optical performance, the maximum diameter of the polysiloxane microspheres in the silicone micro powder is d max , and the minimum diameter is d min , (d max -d min ) / d×100%≤20% (size difference x).

[0062] (d max -d min ) / d×100% can measure the size distribution of the silicone micro powder. The smaller the value, the smaller the difference between the maximum and minimum sizes of the silicone micro powder particles. When (d max -d min ) / d×100%≤20%, it can basically reflect that the silicone micro powder does not have a significant size problem, and the average diameter of the microspheres does not need to be controlled to be smaller.

[0063] The preparation method of the silicone micro powder provided in the embodiment of the application comprises:

[0064] The hydrolysis liquid is obtained by reacting siloxane and water in a mass ratio of 1:3-20, and the conductivity of the hydrolysis liquid is 3-20 μS / cm.

[0065] The mixing liquid is obtained by mixing the hydrolysis liquid and the base to obtain a mixing liquid with a pH of 9-11.5.

[0066] The temperature of the mixing liquid is increased to the polycondensation temperature of 40-60 ℃, the temperature of the mixing liquid is controlled to reach the polycondensation temperature within 60 s during the temperature increasing process, the substances in the mixing liquid are subjected to a polycondensation reaction, and a solid-liquid mixture containing polysiloxane microspheres is obtained after the reaction is completed.

[0067] The polysiloxane microspheres are extracted from the solid-liquid mixture, and the silicone micro powder is obtained.

[0068] The preparation method provided by the application is as follows: The conductivity of the hydrolysis solution can reflect the degree of hydrolysis of the siloxane in the hydrolysis solution to a certain extent. If the degree of hydrolysis of the siloxane is too high (the conductivity is too high), the consistency of the crosslinking degree of the hydrolysis product may be poor, thereby leading to poor size uniformity of the microspheres finally generated. If the degree of hydrolysis of the siloxane is too low (the conductivity is too low), the siloxane molecules fail to form active silicon hydroxyl groups (Si-OH) sufficiently, leading to insufficient active sites for subsequent polycondensation reaction, thereby leading to uneven polycondensation rate and poor surface smoothness and relatively low roundness of the microspheres prepared. The basic environment (pH 9-11.5) causes the deprotonation of the silanol (Si-OH) in the hydrolysis solution to form highly active silanol anions (Si-O⁻) ), and the charge repulsion inhibits the agglomeration between the cores. At low temperature (≤0 ℃), the molecular thermal motion energy is reduced, the collision probability of the silanol anions is reduced, the nucleation induction period is prolonged, the excessive catalysis of OH⁻ on condensation is inhibited, and local explosive nucleation is avoided. Then, the temperature is rapidly increased to a suitable temperature, so that the hydrolysis product in the mixed solution undergoes polycondensation reaction to generate polysiloxane microspheres with high surface roundness and good size uniformity in the solution system.

[0069] The preparation method is specifically as follows:

[0070] S1, providing a hydrolysis solution

[0071] The siloxane and water are mixed and reacted at a mass ratio of 1:3-20 (for example, 1:3, 1:5, 1:10, 1:15 or 1:20), and a uniform transparent hydrolysis solution with a conductivity of 3-20 μS / cm (for example, 3 μS / cm, 5 μS / cm, 10 μS / cm, 15 μS / cm or 20 μS / cm) is obtained by stirring reaction.

[0072] Optionally, the mixing reaction temperature is 20-30 ℃ (20 ℃, 25 ℃ or 30 ℃), and the mixing reaction time is 0.5-3 h. Under this reaction temperature and time, a hydrolysis solution with a conductivity in the range of 3-20 μS / cm can be obtained.

[0073] Preferably, the conductivity of the hydrolysis solution is 4-15 μS / cm (for example, 4 μS / cm, 8 μS / cm, 12 μS / cm or 15 μS / cm). When the conductivity of the hydrolysis solution is in this range, polysiloxane microspheres with better size uniformity and better surface relative roundness can be obtained.

[0074] Optionally, the siloxane is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane and vinyltrimethoxysilane.

[0075] S2, providing a mixed solution

[0076] The hydrolysate and alkali are mixed at ≤0℃ to obtain a mixture with a pH of 9~11.5 (e.g., 9, 9.5, 10, 10.5, 11, or 11.5). A nucleation reaction occurs when the hydrolysate and alkali are mixed. If the temperature is too high, the reaction rate is fast, easily leading to uneven nucleation. Controlling the mixing temperature at ≤0℃ avoids this problem. Furthermore, the amount of alkali added in this process is inversely related to the size of the nuclei formed; increasing the amount of alkali increases the OH⁻ concentration in the system, leading to the ionization of more silanol groups. The density of nucleation sites increases; with the monomer supply remaining constant, the amount of raw material obtained by each nucleus decreases, resulting in a smaller final particle size. Therefore, to ensure that the size and uniformity of the obtained polysiloxane microspheres are within the range required by this invention, the amount of alkali mixed is determined by achieving a pH value of 9-11.5 in the resulting mixture.

[0077] Optionally, to better ensure uniform alkali dispersion and improve the quality of the resulting organosilicon micropowder, the alkali is added in the form of an alkaline solution.

[0078] Optionally, the alkaline solution is at least one of sodium hydroxide solution and potassium hydroxide solution.

[0079] Optionally, the alkaline solution is an aqueous solution of sodium hydroxide with a mass concentration of 0.08 to 5% (e.g., 0.08%, 0.1%, 0.15%, 0.2%, 0.4% or 0.5%).

[0080] Since a higher pH value means more OH- is added per unit volume. - The more alkali is added to the hydrolysate, the more likely a nucleation reaction will occur. Therefore, if it is necessary to adjust the pH to a higher value, in order to ensure uniform nucleation, it is preferable to mix the alkali with the hydrolysate in batches, and mix each batch thoroughly before mixing the next batch.

[0081] Specifically, a mixer can be used to mix the alkaline solution with the hydrolysate. For example, the alkaline solution can be mixed in batches, with the mixture passed through a mixer in N (1≤N≤5) batches, and the total mixing time can be controlled within 20s to 3min (e.g., 20s, 1min, 2min, or 3min).

[0082] Optionally, the flow rate ratio of the hydrolysate and the alkaline solution through the mixer is (5~100):1 (e.g., 5:1, 10:1, 20:1, 50:1, 80:1 or 100:1).

[0083] S3, Polycondensation reaction

[0084] The temperature of the mixed solution is raised to the condensation temperature of 40-60°C (for example, 40°C, 50°C or 60°C), the temperature of the mixed solution is controlled to reach the condensation temperature from 0°C in less than 60 seconds, and the substances in the mixed solution are subjected to condensation reaction, so that a solid-liquid mixture containing polysiloxane microspheres is obtained.

[0085] The condensation temperature needs to be in the range of 40-60°C. If the temperature is too low, the condensation reaction kinetics is limited, the condensation rate of silicon hydroxyl (Si-OH) is too slow, the surface of the microspheres is not fully crosslinked, a porous or loose structure is formed, the residual silanol groups are increased, the mechanical strength of the microspheres is decreased, the molecular chain movement ability is insufficient, the surface tension cannot effectively repair defects, and the surface is rough. If the temperature is too high, the condensation reaction is intense, which causes side reactions: rearrangement of the siloxane skeleton causes internal stress cracks in the microspheres; volatile small molecules (such as H2O / ROH) rapidly escape to form internal bubbles, and the mechanical strength is reduced; high temperature inter-core curing aggravates the particle size distribution, and the uniformity is poor.

[0086] The condensation reaction will gradually begin during the temperature raising process, and the faster the temperature is raised, the more conducive it is to generate microspheres with high surface smoothness and high size uniformity. When the time taken to raise the temperature from 0°C to the condensation temperature is less than or equal to 60 seconds, the microspheres prepared can meet the requirements of surface relative smoothness and relative size uniformity.

[0087] Optionally, the condensation reaction time is controlled to be 0.5-1.5 hours (for example, 0.5 hours, 1 hour or 1.5 hours) to ensure that the reaction is sufficient.

[0088] Optionally, the temperature raising time is 30-42 seconds (for example, 30 seconds, 35 seconds, 40 seconds or 42 seconds). This temperature raising time is the best temperature raising time for preparing microspheres of better quality.

[0089] Optionally, the temperature raising rate is 60-100°C / min (for example, 60°C / min, 70°C / min, 80°C / min, 90°C / min or 100°C / min).

[0090] Optionally, a microwave reactor can be used to achieve rapid temperature raising.

[0091] Preferably, to ensure sufficient nucleation and faster temperature raising to the condensation temperature, the hydrolysis solution and the base are mixed at a temperature of -5 to 0°C (for example, -5°C, -3°C or 0°C).

[0092] S4, extraction of reaction product

[0093] The solid-liquid mixture is subjected to solid-liquid separation, and the obtained solid is washed and dried.

[0094] Optionally, the washing is multiple washing of the solid product obtained by solid-liquid separation with deionized water.

[0095] Optionally, the drying temperature is 80-120℃ (for example, 80℃, 100℃ or 120℃). Specifically, the drying can be performed by using an infrared drying method.

[0096] The embodiment of the present application provides a light scattering material, which comprises the organic silicon micro powder provided by the embodiment of the present application or the organic silicon micro powder prepared by the preparation method provided by the embodiment of the present application.

[0097] The embodiment of the present application provides a silicon dioxide powder, which is obtained by calcining the organic silicon micro powder; the organic silicon micro powder is the organic silicon micro powder provided by the embodiment of the present application or the organic silicon micro powder prepared by the preparation method provided by the embodiment of the present application.

[0098] The size uniformity of the silicon dioxide powder prepared by calcining the organic silicon micro powder provided by the present application is high, which can better ensure the uniformity of the electric field distribution of the copper-clad plate, reduce the interface polarization of the copper-clad plate and optimize the filler dispersibility of the copper-clad plate when the silicon dioxide powder is applied to the copper-clad plate; the particle surface of the silicon dioxide powder is smooth, which can inhibit the surface defects of the copper-clad plate, reduce the dielectric loss of the copper-clad plate and improve the breakdown strength and interface bonding force of the copper-clad plate when the silicon dioxide powder is applied to the copper-clad plate.

[0099] The preparation method is specifically as follows:

[0100] The first stage heat treatment: the environment where the organic silicon micro powder is located is heated to 500-800℃ (for example, 500℃, 600℃, 700℃ or 800℃) in the presence of oxygen, and the heat preservation treatment is performed for 4-10h (for example, 4h, 6h, 8h or 10h). Optionally, in this step, the heating rate is 1-5℃ / min (for example, 1℃ / min, 3℃ / min or 5℃ / min).

[0101] The second stage heat treatment: the temperature is continuously increased to 850-1100℃ (for example, 850℃, 900℃, 950℃, 1000℃ or 1100℃), and the heat preservation treatment is performed for 4-10h (for example, 4h, 6h, 8h or 10h). Optionally, in this step, the heating rate is 5-10℃ / min (for example, 5℃ / min, 8℃ / min or 10℃ / min).

[0102] Finally, the temperature is decreased to room temperature. Optionally, the cooling rate is 10-20℃ / min (for example, 10℃ / min, 15℃ / min or 20℃ / min).

[0103] The dielectric loss of the finally prepared spherical inorganic silicon dioxide powder is 0.00015-0.0003.

[0104] The embodiment of the present application also provides a copper-clad plate, and the composition of the copper-clad plate comprises the silicon dioxide powder provided by the embodiment of the present application.

[0105] The application will be described in more detail below with reference to more specific embodiments.

[0106] Example 1

[0107] S1: methyltrimethoxysilane is mixed with water to hydrolyze, obtaining a uniform and transparent hydrolysis solution. The mass ratio of methyltrimethoxysilane to water is 1:10, the mixing temperature is controlled at 20℃, the stirring time is 0.5h, and the conductivity of the hydrolysis solution is 4.3μS / cm;

[0108] S2: the hydrolysis solution is mixed with lye (an aqueous solution of sodium hydroxide with a mass concentration of 0.15%) uniformly at -4℃ to obtain a mixed solution with a pH of 10.1; the mixing process uses a flow mixer to mix, wherein the hydrolysis solution and the lye pass through the flow mixer at a temperature of -4℃ at a flow rate ratio of 9.2:1, and the passing number N is 1;

[0109] S3: the mixed solution is quickly heated to 50℃ until the polycondensation reaction is complete, obtaining a solid-liquid mixture containing polysiloxane microspheres; wherein the heating rate is 80℃ / min (37.5s from 0℃ to 50℃); the microwave reactor is selected for rapid heating during the heating process, and the polycondensation reaction time is 1h;

[0110] S4: the solid-liquid mixture is subjected to solid-liquid separation, and the obtained solid is washed with deionized water and then dried at 100℃ to obtain silicone micro powder.

[0111] The prepared silicone micro powder is tested by atomic force microscope (AFM) to obtain Rq: root mean square surface roughness; Ra: average surface roughness, and the relative smoothness R=Rq / Ra is calculated;

[0112] The sample is tested and analyzed by scanning electron microscope (SEM) to obtain φ: variance; d: average diameter, and the relative size uniformity RSU=1-φ / d is calculated 2 .

[0113] The product parameters are shown in Table 1.

[0114] Examples 2-8

[0115] Examples 2-8 are basically the same as Example 1, only the specific parameter settings in the preparation process are different, and the specific parameter settings are shown in Table 1, and the product parameters obtained are shown in Table 1.

[0116] Table 1: Parameters of each example

[0117]

[0118] As can be seen from Table 1, the preparation method provided by the application can prepare silicone micro powder with a surface relative smoothness R and a relative size uniformity RSU within the range required by the application.

[0119] The atomic force microscope 2D and 3D pictures of Example 8 are shown in Figures 1 and 2, respectively, from which it can be seen that the micro-powder has a high spheroidization rate and good uniformity, and the 3D picture shows a smooth surface. Figure 4

[0120] Comparative Example

[0121] The preparation method of the comparative example is basically the same as that of Example 1, except for the differences shown in Table 2.

[0122] Parameters of each comparative example in Table 2

[0123]

[0124] As can be seen from Table 2, at least one of the relative slip rate R and the relative size uniformity RSU of the silicone micro-powder prepared in each comparative example is not within the range required by the present application.

[0125] Comparing Comparative Example 1 with Example 2, the ratio of siloxane to water is increased, which is beyond the range required by the present application, and the conductivity of the hydrolysis solution is also beyond the range required by the present application. The SEM picture of the silicone micro-powder prepared shows that the size uniformity is poor, and there are some pits on the surface. The size difference between the large and small spheres is 7.1 μm.

[0126] Comparing Comparative Example 2 with Example 3, the ratio of siloxane to water is increased, which is beyond the range required by the present application, and the conductivity of the hydrolysis solution is also beyond the range required by the present application. Under the catalysis of alkali, the condensation speed is more intense, which makes the size uniformity of the prepared organic microspheres poor.

[0127] Comparing Comparative Example 3 with Example 3, the mixing temperature is increased, which accelerates the condensation reaction, and the non-uniform nucleation and growth during the heating process leads to the production of particles with non-uniform sizes.

[0128] Comparing Comparative Example 4 with Example 2, the pH of the mixed solution is lower than the range required by the present application. At low alkali concentration, the prepolymer is generated slowly, and there are not enough catalytically active groups, which leads to insufficient crosslinking of the molecular chains, and the surface of the spheres is prone to residual unreacted groups or pores, reducing the smoothness.

[0129] Comparing Comparative Example 5 with Example 3, the pH of the mixed solution is controlled at 12, which is higher than the range required by the present application, and the catalytic activity is higher, which accelerates the condensation speed, leading to excessive local supersaturation in the reaction system, which triggers explosive nucleation; a large number of crystal nuclei are formed instantaneously, and the molecular chains are stacked in disorder, which reduces the surface roughness of the spheres and makes the size uniformity poor.

[0130] ​Comparative Example 6, compared with Example 2, reduces the heating rate, so that the heating time exceeds the requirement of the present application, the slow heating prolongs the pre-polymer aging time, the partial pre-polycondensation of silanol (Si-OH) causes the disordered stacking of the molecular layer on the surface of the sphere, forming micron-level protrusions or pores, and the roughness is reduced.

[0131] Comparative Example 7, compared with Example 2, reduces the polycondensation temperature, which leads to a decrease in the polycondensation rate, and the asynchronous nucleation phenomenon is prominent. The high-activity pre-polymer preferentially nucleates to form small particles, and the free monomer slowly adheres to form large particles. In addition, the low-temperature crosslinking is insufficient, the surface molecular orientation is disordered, and the surface is rough.

[0132] Experimental Example

[0133] The silicone micro-powder prepared in each example and comparative example is used to prepare a light scattering material according to the following preparation method.

[0134] Preparation method: the silicone micro-powder and polycarbonate pellets (optional, available from Dongguan Shidaishi Polymer Material Co., Ltd.) are mixed at a weight ratio of 1:100, and then subjected to melting, mixing, extrusion, water cooling, and pelletization by a double-screw extruder. The extruded pellets are dried in a forced air drying oven at 150°C for 3h, and then injection molded into a light scattering material using an injection molding machine. The sample is tested for light transmittance and haze according to GB / T2410-2008 using a light transmittance and haze tester.

[0135] The pure polycarbonate pellets are used as a blank control.

[0136] The test results are recorded in Table 3.

[0137] Table 3: Performance test results of the materials prepared in each example, comparative example, and blank control group

[0138]

[0139] As can be seen from Table 3, the light transmittance of the silicone micro-powder prepared in each example of the present application is above 90%, and the haze can reach above 90%.

[0140] In each comparative example, the R value of a part is not within the range required by the present application, and the RSU value of a part is not within the range required by the present application. The measured light transmittance and haze are significantly poorer than those of the examples, which indicates that when the relative smoothness and relative size of the silicone micro-powder are within the range required by the present application, it can be ensured that the light scattering material has a higher light transmittance and haze.

[0141] Example 9

[0142] The present example provides a preparation method of a silicon dioxide powder, specifically:

[0143] First stage heat treatment: the organic silicone micro-powder prepared in Example 1 was placed in an environment with oxygen, and the environment of the organic silicone micro-powder was heated to 600℃ at a heating rate of 4℃ / min, and heat preservation treatment was performed for 6h.

[0144] Second stage heat treatment: continued heating to 1000℃ at a heating rate of 6℃ / min, and heat preservation treatment was performed for 6h.

[0145] Finally, the temperature was decreased to room temperature at a cooling rate of 15℃ / min to obtain the silicon dioxide powder.

[0146] The dielectric loss of the prepared silicon dioxide powder was 0.00025, and the results showed that the silicon dioxide powder after calcination conversion of the organic microspheres had excellent dielectric properties.

[0147] In summary, the organic silicone micro-powder provided by the present application has a relatively smooth degree and a relatively uniform size, and the relative size is within the range required by the present application, which can ensure that the organic silicone micro-powder has a high light utilization rate, a high light transmittance, and a good uniformity of light scattering and diffusion. When applied to light diffusion materials, the light control precision is high, the light transmittance and diffusion are good, the light transmittance and brightness are higher, and the formed coating has good flatness when used as a coating forming raw material.

[0148] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A silicone fine powder, characterized by, It is composed of a plurality of polysiloxane microspheres, the relative smoothness of the surface of each polysiloxane microsphere is R, 1.02≤R≤1.30, wherein, R=Rq / Ra, Rq is the root mean square surface roughness of the polysiloxane microsphere, Ra is the average surface roughness of the polysiloxane microsphere; The relative size uniformity of the silicone micropowder is RSU, RSU = 1 - φ / d 2 ≥ 0.992, wherein φ is the variance of the diameters of the silicone micropowder, and d is the average diameter of the silicone micropowder.

2. The silicone micropowder according to claim 1, characterized in that, The root mean square surface roughness Rq of each polysiloxane microsphere is ≤120nm, and the average surface roughness Ra is ≤100nm.

3. The silicone micropowder of claim 1, wherein The root mean square surface roughness Rq of each polysiloxane microsphere is 48nm≤Rq≤101.1nm, and the average surface roughness Ra is 38nm≤Ra≤97.2nm.

4. The silicone micropowder of claim 1, wherein It includes at least one of the following features (1) and (2): (1) The average diameter d of the organic silicon micro powder is 0.5-10μm; (2) the maximum diameter of the polysiloxane microspheres in the silicone micro powder is d max , the minimum diameter is d min , (d max -d min ) / d x 100% ≤ 20%.

5. A method for producing silicone fine powder, characterized by, It includes: A hydrolysis solution is provided, which is obtained by reacting siloxane and water in a mass ratio of 1:3-20, and the conductivity of the hydrolysis solution is 3-20μS / cm; A mixed solution is provided, the hydrolysis solution and the base are mixed under the condition of ≤0℃ to obtain a mixed solution with pH of 9-11.5; The temperature of the mixed solution is raised to the polycondensation temperature of 40-60℃, the time used for controlling the temperature of the mixed solution from 0℃ to reach the polycondensation temperature is ≤60s, the substances in the mixed solution are subjected to polycondensation reaction, and the reaction is completed to obtain a solid-liquid mixture containing polysiloxane microspheres; The polysiloxane microspheres are extracted from the solid-liquid mixture, and the organic silicon micro powder is obtained.

6. The preparation method according to claim 5, characterized in that, It also includes at least one of the following features (1)-(7): (1) The siloxane is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane and vinyltrimethoxysilane; (2) The hydrolysis solution is mixed with the base under the condition of-5-0℃; (3) The heating rate of the mixed solution to the polycondensation temperature is 60-100℃ / min; (4) The base is selected from at least one of sodium hydroxide and potassium hydroxide; (5) The reaction temperature of the siloxane and water is 20-30℃, and the reaction time is 0.5-3h; (6) The base is mixed with the hydrolysis solution in the form of a base solution, and the mixing method is: the base solution is divided into multiple batches, and each batch is mixed with the hydrolysis solution; (7) The way of extracting the polysiloxane microspheres from the solid-liquid mixture includes: solid-liquid separation is performed on the solid-liquid mixture, and the obtained solid is washed and dried.

7. The preparation method according to claim 5, characterized in that, The conductivity of the hydrolysis solution is 4-15μS / cm.

8. A light scattering material, characterized in that, It includes the organic silicon micro powder of any one of claims 1-4 or the organic silicon micro powder prepared by the preparation method of any one of claims 5-7.

9. A silica powder, characterized by, It is obtained by calcining the organic silicon micro powder; The organic silicon micro powder is the organic silicon micro powder of any one of claims 1-4 or the organic silicon micro powder prepared by the preparation method of any one of claims 5-7.

10. A copper clad plate characterized by, Its composition includes the silicon dioxide powder of claim 9.

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