CN112811429A

CN112811429A - Preparation method of silicon dioxide light diffusant and light diffusant obtained by preparation method

Info

Publication number: CN112811429A
Application number: CN202011627463.2A
Authority: CN
Inventors: 张磊磊; 陈晨; 方袁烽; 蒋攀
Original assignee: Zhejiang Sanshi New Material Technology Co Ltd
Current assignee: Zhejiang Sanshi New Material Technology Co Ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2021-05-18

Abstract

The invention relates to a preparation method of a silicon dioxide light diffusant, which comprises the steps of preparing an aqueous solution of alkyl silicic acid; adjusting the pH value of the aqueous solution to 7-13 so as to neutralize the hydroxyl of the alkyl silicic acid to obtain spherical polysiloxane; and drying and dispersing the spherical polysiloxane to obtain the silicon dioxide light diffusant. The invention also relates to the silicon dioxide light diffusant obtained by the preparation method. The silica light diffusant obtained by the invention has narrow particle size distribution, namely the most frequency diameter and the maximum particle size are very close, and the silica light diffusant has perfect sphere surface quality, namely, no pit is arranged on the sphere surface, no scattered light occurs when light is reflected, the light intensity can be kept on the premise of keeping soft light, the refractive index is high, and the silica light diffusant has good light diffusion effect.

Description

Preparation method of silicon dioxide light diffusant and light diffusant obtained by preparation method

Technical Field

The invention relates to a diffusant, in particular to a preparation method of a silicon dioxide light diffusant and the light diffusant obtained by the preparation method.

Background

The light diffusing agent is a microsphere product developed by means of crosslinking, grafting functional groups and the like by utilizing a high molecular polymerization technology. The light-emitting diode can be added into transparent resin such as PC, PVC, PS, PMMA, PET, epoxy resin and the like and an LED (light-emitting diode), so that the light scattering and transmission are increased, a light source and a glaring light source are shielded, the whole resin can emit softer, more attractive and more elegant light, and the comfortable effect of light transmission and opaqueness is achieved.

Obviously, the light diffusing agent must be added to substantially balance the transmission and scattering of light, and to control the scattering of light within a certain range. Therefore, there are certain requirements and limitations on the parameters of the light diffusing agent in the continuous medium (resin), such as refractive index (difference), sphericity, surface regularity of particles, particle size, and concentration. For example, the refractive index of the light diffusing agent and the refractive index of the continuous medium (resin) cannot be too different, otherwise the stronger the scattering effect, the total reflection is caused, the light is reflected back to the inside and cannot be guided out, and the light intensity is reduced.

Known inorganic light diffusers, such as barium sulfate, have poor particle size distribution and surface quality of the spheres, which severely affect the light diffusion effect. Known organic light diffusers, such as organic nanobeads, have a small refractive index (e.g., about 1.43) due to the organic component contained therein, and are poor in heat resistance (e.g., about 400 degrees).

Disclosure of Invention

In order to solve the problems that the quality of the dispersing agent in the prior art is poor or the refractive index is too small, the invention provides a preparation method of a silicon dioxide light dispersing agent and the light dispersing agent obtained by the preparation method.

According to one aspect of the present invention, there is provided a method for preparing a silica light diffuser, comprising the steps of: s1, preparing an aqueous solution of hydrocarbyl silicic acid; s2, adjusting the pH value of the aqueous solution to 7-13 to neutralize the hydroxyl of the alkyl silicic acid to obtain spherical polysiloxane; s3, drying and dispersing the spherical polysiloxane to obtain the silicon dioxide light dispersing agent.

Preferably, in step S1, the hydrocarbyl group is methyl, propyl, vinyl, or phenyl. In a preferred embodiment, the monohydrocarbylsilicic acid is methyltrimethoxysilane.

Preferably, in step S1, the aqueous solution includes an organic solvent or deionized water.

Preferably, in step S2, the pH of the aqueous solution is adjusted to 7-13 by adding alkali directly, or the pH of the aqueous solution is adjusted to 7-13 by adding acid before adjusting the pH of the aqueous solution to less than 7. It is understood that silica light diffusers of different particle sizes can be synthesized by adjusting to different pH values.

Preferably, in step S2, the acid added is an inorganic acid or an organic acid, and the base added is an inorganic base or an organic base.

Preferably, in step S2, after the PH of the aqueous solution is adjusted to 7 to 13, the aqueous solution is stirred uniformly and then left to stand, then hydrochloric acid, sulfuric acid, nitric acid or acetic acid is added while stirring to adjust the PH to neutrality, and then the mixture is filtered, washed with water and dried to obtain the spherical polysiloxane.

Preferably, in step S3, the spherical polysiloxane is heated to 300-1100 ℃ for dry dispersion.

Preferably, in step S3, the spherical polysiloxane is heated to 300-500 ℃ to remove the hydrocarbon group, and then heated to 800-1100 ℃ to be calcined. In a preferred embodiment, the spherical polysiloxane is heated to 1000 ℃ for dry dispersion.

According to another aspect of the present invention, there is provided a silica light diffuser obtained by the above production method.

Preferably, the average particle diameter of the silica light diffuser is 0.6 to 2.4 μm.

Preferably, the refractive index of the silica light diffuser is 1.44 to 1.474. More preferably, the refractive index of the silica light diffuser is 1.444 to 1.47. More preferably, the refractive index of the silica light diffuser is 1.45 to 1.464. More preferably, the refractive index of the silica light diffuser is 1.454-1.46. In a preferred embodiment, the refractive index of the silica light diffuser is 1.457.

According to the preparation method of the silica light diffusant, the obtained silica light diffusant is narrow in particle size distribution, namely the most frequency diameter and the maximum particle size are very close, the silica light diffusant has perfect sphere surface quality, namely no pits exist on the sphere surface, no scattered light occurs in reflected light, the light intensity can be kept on the premise of keeping soft light, the refractive index is high, and the silica light diffusant has a good light diffusion effect. In particular, the silica light diffusing agent of the present invention has a refractive index of about 1.457 which is small in difference from the refractive index of the main stream resin, and has a decomposition temperature of about 1650 ℃ or so, and is excellent in heat resistance. In conclusion, according to the preparation method of the silica light diffusant, the spherical polysiloxane is synthesized by the wet method, the obtained silica light diffusant does not contain large particles, spheres are uniform, the surfaces of the spheres are smooth and have no pits or nanoparticles, and the refraction and scattering effects on light are superior to those of the traditional light diffusant. Moreover, compared with the production of silicon dioxide from natural quartz ore, the preparation method of the silicon dioxide light diffusion agent has the advantages that the obtained silicon dioxide light diffusion agent has higher purity and does not contain other impurities.

Drawings

FIG. 1 is a particle size diagram of a silica light diffuser according to example 1 of the present invention;

FIG. 2 is an SEM photograph of a silica light diffuser according to example 1 of the present invention, in which the diameter of the marked spheres is 623.9 nm;

FIG. 3 is a particle size diagram of a silica light diffuser according to example 2 of the present invention;

FIG. 4 is an SEM photograph of the silica light diffuser of example 2 according to the present invention, in which the diameters of the spheres noted are 2.357 μm and 2.279 μm.

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Example 1

Putting 640 parts of deionized water into a reaction kettle with a stirrer at room temperature, starting the stirrer, adding 40 parts by mass of methyltrimethoxysilane and a small amount of acetic acid to adjust the pH value to about 5, hydrolyzing the methyltrimethoxysilane, adding 32 parts by mass of 5% ammonia water, stirring for 1 minute, stopping stirring, standing for one hour, filtering, drying to obtain spherical polysiloxane, introducing dry air into the obtained spherical polysiloxane for heat treatment at the temperature of 1000 ℃ for 10 hours to obtain the silicon dioxide light diffusant.

As shown in fig. 1, the particle size distribution of the silica light diffuser is narrow, and the product distribution of D50 ═ 0.6 μm is between 0.3 and 1.0 μm. As shown in fig. 2, the spherical surface of the silica light diffuser was smooth and free of pits or nanoparticle adhesion.

Example 2

Placing 700 parts of deionized water into a reaction kettle with a stirrer at room temperature, starting the stirrer, adding 80 parts by mass of methyltrimethoxysilane and a small amount of acetic acid to adjust the pH value to about 5, adding 3 parts by mass of 5% ammonia water after the methyltrimethoxysilane is dissolved, stirring for 10 minutes, stopping stirring, adding 22 parts by mass of 5% ammonia water, standing for one hour, filtering, drying to obtain spherical polysiloxane, introducing dry air into the obtained spherical polysiloxane for heat treatment at the temperature of 800 ℃, and the heat treatment time of 12 hours.

As shown in fig. 3, the particle size distribution of the silica light diffuser is narrow, and the product distribution of D50 ═ 2.4 μm is between 1.5 and 4.5 μm. As shown in fig. 4, the spherical surface of the silica light diffuser was smooth and free of pits or nanoparticle adhesion.

The above embodiments are merely preferred embodiments of the present invention, which are not intended to limit the scope of the present invention, and various changes may be made in the above embodiments of the present invention. All simple and equivalent changes and modifications made according to the claims and the content of the specification of the present application fall within the scope of the claims of the present patent application. The invention has not been described in detail in order to avoid obscuring the invention.

Claims

1. The preparation method of the silicon dioxide light diffusant is characterized by comprising the following steps:

s1, preparing an aqueous solution of hydrocarbyl silicic acid;

s2, adjusting the pH value of the aqueous solution to 7-13 to neutralize the hydroxyl of the alkyl silicic acid to obtain spherical polysiloxane;

s3, drying and dispersing the spherical polysiloxane to obtain the silicon dioxide light dispersing agent.

2. The method according to claim 1, wherein the hydrocarbon group is a methyl group, a propyl group, a vinyl group or a phenyl group.

3. The method of claim 1, wherein the aqueous solution comprises an organic solvent or deionized water.

4. The method of claim 1, wherein the aqueous solution is adjusted to pH 7 to 13 by adding a base directly in step S2, or the aqueous solution is adjusted to pH 7 to 13 by adding an acid after the pH of the aqueous solution is less than 7.

5. The process according to claim 4, wherein the spherical polysiloxane is obtained by adjusting the pH of the aqueous solution to 7 to 13, stirring the mixture uniformly, standing the mixture, adjusting the pH to neutral by adding hydrochloric acid, sulfuric acid, nitric acid or acetic acid while stirring the mixture, filtering the mixture, washing the filtrate with water, and drying the washed filtrate.

6. The method as set forth in claim 1, wherein in step S3, the spherical polysiloxane is heated to 1100 ℃ for dry dispersion.

7. The method as claimed in claim 6, wherein the spherical polysiloxane is heated to 500 ℃ at 300 ℃ to remove the hydrocarbon group, and then heated to 1100 ℃ at 800 ℃ to be calcined.

8. A silica light diffuser obtained by the production method according to any one of claims 1 to 7.

9. The silica light diffuser according to claim 8, wherein the average particle diameter of the silica light diffuser is 0.6 to 2.4 μm.

10. The silica light diffuser of claim 8 wherein the silica light diffuser has a refractive index of 1.44 to 1.474.