TW202138298A - Silica sol and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of semiconductor chemical mechanical polishing, and specifically discloses a silica sol and a preparation method thereof. A silica sol, the degree of association of colloidal particles is 1.2-5.0, and the ratio of the low-field nuclear magnetic wet method specific surface area of the colloidal particle to the dry gas adsorption BET specific surface area is S_N /S_B ＞3.5.The preparation method includes the following steps: preparing several groups of acidic combination liquids with a mass content of alkoxysilane ≥95% and mother liquids containing alkali catalysts, high-purity water and organic solvents; adding a group of the acidic combination liquids to the mother liquid to obtain a first silica sol; add high-purity water and a group of the acidic combination liquid to the obtained first silica sol at least once to obtain a silica sol primary solution; concentrate and replace the solvent with water to obtain a silica sol product. The preparation method provided by the present invention realizes the controllability of the silica sol particle morphology by regulating the acid value of the acidic combination liquid of alkoxysilane and adjusting the change of the acid value of each group of acidic combination liquids added, and obtains spherical and non-spherical particles. The primary solid content of the obtained silica sol＞10%, metal ion content ＜1ppm.

Description

Silica sol and preparation method thereof

The invention relates to the technical field of semiconductor chemical mechanical polishing, in particular to a silica sol and a preparation method thereof.

In recent years, with the continuous development of semiconductor technology, people have higher and higher requirements for the surface quality of the substrate materials used. Therefore, Chemical Mechanical Polishing (CMP) technology, which achieves global planarization, has become one of the key technologies in semiconductor manufacturing.

At present, the monodisperse spherical colloidal silica used as the grinding medium of the polishing liquid has the disadvantage of low polishing efficiency, while the cocoon-shaped, long-chain type and other non-spherical colloids with approximately the same cross-sectional diameter and a certain degree of association are used. Silicon oxide has a good application prospect in semiconductor CMP because it has a large drag area and is not easy to cause scratches.

The commonly used method in the preparation technology of non-spherical silica sol is to convert water glass into silica sol. The raw material contains a large amount of sodium ions and other metal ions. Although some metal ions can be removed by ion exchange resin, this method can remove metal ions. There is a certain upper limit, and the residual amount of metal ions is large, which limits the application of silica sol in semiconductor polishing. In addition, if the alkoxysilane hydrolysate is used as the raw material to convert silica sol, because the alkoxysilane hydrolysate has a strong tendency to gel, generally only silica sols with a silica mass concentration of less than 5% can be prepared, and the final result is The one-time solid content of silica sol is too low, resulting in lower production efficiency. It is also known to use tetramethoxysilane as a raw material to prepare spherical or non-spherical colloidal particles. Since the reaction is usually carried out at a low temperature and a high catalyst concentration, the resulting silica sol product usually contains a large amount of colloidal oligomers. Residues can easily cause problems such as scratches on the object to be polished when used in semiconductor CMP polishing solutions.

In view of the above-mentioned technical problems of conventional silica sol in semiconductor CMP, the present invention provides a silica sol and a preparation method thereof.

One kind of silica sol, the degree of association 1.2-5.0 micelles, colloidal particles of the low-field nuclear magnetic wet adsorption BET specific surface area ratio S _N / S _B> 3.5, the metal ion content <1ppm and a specific surface area of dry gas.

In order to achieve the above-mentioned purpose of the invention, the following technical solutions are adopted in the embodiments of the present invention:

A method for preparing silica sol with controllable particle morphology includes the following steps:

S1: Prepare a plurality of alkoxysilanes with a mass content of ≥95% of the acidic combination liquid and a mother liquid containing alkali catalysts, high-purity water and organic solvents and 7＜pH＜11;

S2: adding a set of the acidic combination liquid to the mother liquor to obtain the first silica sol;

S3: Add high-purity water and a set of the acidic combination liquid to the obtained first silica sol at least once to obtain a silica sol primary liquid;

S4: The primary silica sol solution obtained is concentrated and the solvent is replaced to obtain a silica sol product.

In step S1, the acid value of the acidic composition is ^{characterized by phenolphthalein acidity c(H +} ). The phenolphthalein acidity c(H ⁺ ) means that a certain volume _{of the acidic composition of V A} is added to the ethanol solvent and added to the ethanol solvent phenolphthalein indicator, containing a molar concentration c (OH ^-) alcoholic solution of KOH as the titrant, continuous titrated to alcoholic KOH consumed red solution volume V (OH ^-), and in accordance with c (H ⁺ )=V(OH ^- )*c(OH ^- )/V _{A is} calculated, and then the acid value N(H+) of the acidic combined liquid can be calculated from the volume of ^{c(H +) and the acidic combined liquid.}

In step S3, when adding high-purity water, add it slowly or all at once, but the acidic composition must be added after the high-purity water is added, otherwise it will easily lead to the formation of silicic acid exceeding the saturated concentration and cause some particles It grows sharply and affects the uniformity of particle size. Among them, the high-purity water is distilled water, double-distilled water, multi-distilled water, or ultra-pure water with a resistivity> 15 megohm made by RO membrane and polishing resin. Preferably, the high-purity water is distilled water, double-distilled water, multi-distilled water or RO The ultrapure water with a resistivity> 18.2 megaohms prepared by the membrane and polishing resin is preferably ultrapure water with a resistivity> 18.2 megaohms or a resistivity = 18.2.

Compared with the prior art, the method for preparing silica sol with controllable particle morphology provided by the present invention is to alternately add an acidic composition solution with a certain acid value and high-purity water to a mother liquor containing an alkali catalyst by adjusting the alkoxy group. The acid value of the acidic combination liquid of silane and the change of the acid value of each group of acidic combination liquids added are adjusted to realize the controllability of the particle morphology of the silica sol. The secondary particle size measured by the dynamic light scattering method is between 20-500nm , The particle association degree (D ₂ /D ₁ ) can be controlled between 1.2-10. When the ratio of the low-field nuclear magnetic wet method specific surface area of the colloidal particles to the dry gas adsorption BET specific surface area S _N /S _B ＞3.5, Randomly test the particle size of the primary particles with more than 200 particles (the particle size of the particles with no association degree or the short axis of the particles with the degree of association), the coefficient of variation CV<10, the primary solid content of the obtained silica sol> 10%, the solid content of the finished product It can reach 15-50%, the pH is between 6.5-8, the viscosity is less than 8mPa•s, the conductivity is less than 250μS/cm, the true density of the particles is more than 1.95g/cm ³ , and the total content of all metal ions is less than 1ppm.

Among them, the primary solid content refers to the silicon dioxide content of the solution before the concentration or solvent replacement process is completed. The higher the primary solid content, the higher the production efficiency.

The primary particle size D ₁ is obtained by the gas adsorption BET method, D ₁ =2727/S _BET , S _BET is the specific surface area of the particles measured by the gas adsorption BET method; the secondary particle size D ₂ is measured by the dynamic light scattering method Average diameter of hydration kinetics.

Further, the acidic combination liquid is a mixture of alkoxysilane and acidic substance or a mixture of alkoxysilane and high-purity water that is formed by partial hydrolysis reaction and contains acidic substance.

Furthermore, the mixture of alkoxysilane and acidic substance is mixed immediately and quickly added to the reaction system.

The acidic substance is at least one of silicon-containing or non-silicon-containing acidic substances, silicon-containing substances that are acidic after reacting with water, and silicon-containing compounds that are more likely to generate acidic hydrolysates than alkoxysilanes themselves.

Further, the acidic substance without silicon includes at least one of organic acid, inorganic acid, or strong acid and weak base salt, wherein the inorganic acid includes hydrochloric acid, nitric acid, sulfuric acid, hydrobromic acid, and hydrogen peroxide; the organic acid includes formic acid, Acetic acid, oxalic acid, citric acid and malic acid; strong acid and weak base salts including ammonium chloride, ferric chloride and aluminum chloride are used to adjust the acidity of the reaction system.

Further, the silicon-containing acidic liquid contains at least one of silicic acid, silanol, or siloxane containing acidic groups such as mercapto, sulfonic acid or carboxyl groups, wherein silicic acid includes silicic acid and polysilicon Acid and silanol include trialkoxysilanol, dialkoxydisilanol and alkoxytrisilanol.

Further, the silicon-containing substance that reacts with water and has acidity includes at least one of halogenated silanes or halogenated siloxanes, such as silicon tetrachloride, trichlorosilane, and chlorine-containing alkoxysilanes.

Furthermore, the silicon-containing compound that is more likely to generate acidic hydrolysate than the alkoxysilane itself is at least one of n-polymers (n≧2) containing alkoxysilanes and alkoxysilanes having a methoxy group. Such as tetraethoxysilane dimer, tetraethoxysilane tetramer, methoxytriethoxysilane, dimethoxydiethoxysilane and so on.

The acidic substance can also be an acidic substance that contains or does not contain silicon, a mixture of substances that contain silicon that is acidic after reacting with water, and alkoxysilanes that are more likely to generate acidic hydrolysates than alkoxysilanes. Polymer. In order to avoid introducing additional cations or anions, it is preferable to select silicon-containing acidic liquids and/or silicon-containing substances that have acidity after reaction with water and/or those that are more likely to generate acidic hydrolysates than alkoxysilanes. The silicon compound acts as an acid substance.

Further, the acidic substance is an acidic substance that does not contain other elements except for the four elements of Si, O, H, and C.

Further, the acidic combination liquid is a two-component or plural component in which an alkoxysilane and an acidic substance are used at the same time but are not pre-mixed. It adopts the simultaneous and independent rapid addition mode or the mode of rapid addition after instant mixing to avoid premature hydrolysis of alkoxysilane, which affects the control of particle morphology and the adjustment of particle uniformity. Among them, the mass content of alkoxysilane is calculated by the total mass of the two-component or plural components.

Further, if the expected morphology of the silica particles in the silica sol product is spherical, then N _n-1 (H ⁺ ) ≥ 0.5N _n (H ⁺ ), and N _i (H ⁺ )/V _s ＜6×10 ^-4 mol/L; if the expected morphology of the silica particles in the silica sol product is a cocoon shape, then N _n-1 (H ⁺ ) _{≤ N n} (H ⁺ ), and N _i ( H ⁺ )/V _s ＞3.5×10 ^-4 mol/L; if the expected morphology of the silica particles in the silica sol product is a curved long chain shape, then N _n-1 (H ⁺ ) _{≤ N n} ( H ⁺ ), and N _i (H ⁺ )/V _s ＞5.5×10 ^-4 mol/L, where N _n (H ⁺ ) is the acid value of the acidic composition added for the nth time and n is greater than or an integer equal to 2, the unit is mol, N _i (H ⁺⁾ acid value of the acidic liquid composition is added at any one time, in units of mol, V _S mother liquor for the volume of the organic solvent, the unit is L, wherein the mother liquor is The mixed liquid containing organic solvent, water, catalyst, etc. added to the acidic combination liquid. The acid value of the system is controlled by the addition of the acidic combination liquid, and the change of the acid value of each group of acidic combination liquids added subsequently is adjusted to realize the controllability of the morphology of the silica sol particles.

）×100，其中S為一次粒子的標准偏差，

為一次粒子的平均粒徑，S=

，其中n≧200，

為某個一次粒子直徑，

為一次粒子平均徑。本發明中把1＜締合度＜1.5看作球形顆粒，1.5＜締合度＜2.5當作蠶繭形，締合度＞2.5當作彎曲長鏈形。The particle morphology of silica sol includes spherical shape, cocoon shape and curved long chain shape. In the transmission electron microscope picture, if the particle is regarded as a cylindrical body, the thickness of the cylindrical body and the length along the thickness in the same direction are the short axis and the long axis of the particle, respectively. The ratio of the long axis and the short axis of the particle shape is reflected by The degree of association of particles is positively correlated, so the degree of association can roughly reflect the shape of the particles, and the degree of association = D ₂ /D ₁ . Among them, the primary particle size D ₁ is obtained by the gas adsorption BET method, D ₁ =2727/S _BET , S _BET is the particle specific surface area measured by the gas adsorption BET method; the secondary particle size D ₂ is measured by the dynamic light scattering method Obtain the mean diameter of hydration kinetics. Use IMAGE-J software to randomly select the average value of the minor axis of more than 200 particles in the transmission electron microscope image as the primary particle size. Coefficient of variation of primary particle size CV=(S/

)×100, where S is the standard deviation of the primary particle,

Is the average particle size of the primary particles, S=

, Where n≧200,

Is the diameter of a certain primary particle,

Is the average diameter of the primary particles. In the present invention, 1<degree of association<1.5 is regarded as a spherical particle, 1.5<degree of association<2.5 is regarded as a cocoon shape, and an association degree>2.5 is regarded as a curved long chain shape.

Further, in steps S2 and S3, N ₁ (SiO ₂ )/V _S > 1.5 mol/L, and N _i (SiO ₂ )/N ₁ (SiO ₂ )> 1.2, where N ₁ (SiO ₂ ) is The amount of silicon dioxide material formed by the acidic combination liquid added for the first time, N _i (SiO ₂ ) is the amount of silicon dioxide material formed by the acidic combination liquid added for the i-th time, and i is an integer greater than or equal to 2, The unit is mol, and V _{S is} the volume of the organic solvent in the mother liquor. Together with the acid value of the acidic combination liquid, the growth rate of the particles can be controlled by adjusting the amount of silica, ensuring the uniformity of the particle size, and increasing the solid content of the resulting silica sol.

Further, step S2 and / or ^{_{S3,, N i (H +):}} N i (SiO 2): N i (H 2 O): N (N): N i (OS) = (0 ~ 10 -3 ): 1: (4 to 10) :( 0.003 to 0.03): (1.5-5), where, N _i (H ₂ O) was added in an amount of the i-th liquid acidic composition prior to the end of the liquid material of high water ; N (N) is the amount of the base catalyst; N _i (OS) is the amount of the organic solvent in the base solution before adding the acidic composition for the i-th time, in mol. The bottom liquid is the mother liquid or reaction liquid before the acid combination liquid is added, that is, the mother liquid or silica sol solution that receives the acid combination liquid. By controlling the acid value of the acid combination liquid and the proportion of alkoxysilane, alkali catalyst, high-purity water and organic solvent, the morphology of silica sol particles can be controlled. Further, step S2 and / or ^{_{S3,, N i (H +):}} N i (SiO 2): N i (H 2 O): N (N): N i (OS) = (6 × 10 -5 ~10 ^-3 ):1:(4~10):(0.003~0.03): (1.5-5).

Further, in step S2 and/or S3, the reaction temperature is 35-80°C. Too low temperature will cause the hydrolysis rate to be too slow, which will cause the pH fluctuation range to be too low within a period of time after adding the acidic composition, thereby affecting the morphology Too high temperature will cause the formation of a large amount of silicic acid exceeding the saturation concentration in a short period of time, which will lead to the rapid growth of some particles and affect the uniformity of particle size.

Further, in step S2 and/or S3, the reaction temperature is 50-75°C.

Further, in step S3, when the acidic combination liquid is added, the time interval from the previous addition of the acidic combination liquid is 0.5-5 h, which can ensure the hydrolysis of the alkoxysilane added last time.

Further, in step S3, when the acidic composition is added, the time interval from the previous addition of the acidic composition is 1-3 hours.

Furthermore, in step S3, the reaction time is 12-15 hours after the acidic combination liquid is added for the last time, and the primary silica sol liquid is obtained by fully reacting.

Further, the alkoxysilane is tetraethoxysilane or its condensation polymer. In this case, the silanol in the acidic liquid containing silicon is preferably triethoxysilanol, diethoxydisilanol, One or more of ethoxytrisilanol, tetraethoxysilane dimer and polymer, so that no additional impurities are introduced, and solvent recovery and reuse are convenient. Among them, the above-mentioned silanol is obtained by partial hydrolysis of tetraethoxysilane.

Further, the base catalyst is a nitrogen-containing non-metallic base catalyst, that is, a metal-free nitrogen-containing base catalyst, such as at least one of ammonia or organic amine, wherein the organic amine is tetramethylammonium hydroxide, tetraethyl Base ammonium hydroxide, triethanolamine, diethanolamine, triethylamine, ethylenediamine, triethylamine, triethylenediamine, pyridine, 3-ethoxypropylamine, etc. Preferably, the nitrogen-containing non-metallic base catalyst is at least one of the nitrogen-containing non-metal weak base catalysts, such as ammonia or organic amines. The organic amines include triethylamine, triethylenediamine, pyridine, and 3-ethoxypropylamine. Wait.

Further, the nitrogen-containing non-metal weak base catalyst is ammonia water, which is convenient for removal in the subsequent process.

Further, the organic solvent is an alcohol solvent, including methanol, ethanol, propanol, and isopropanol. Preferably, ethanol consistent with the hydrolyzate of tetraethoxysilane is selected.

The present invention also provides a silica sol with a controllable particle shape, which is prepared by the above-mentioned preparation method of the silica sol with a controllable particle shape.

Compared with the prior art, the primary solid content of the silica sol provided by the present invention is> 10%, the metal ion content is less than 1 ppm, and the morphology of the silica sol particles includes spherical and non-spherical forms. The silica sol particle morphology provided by the present invention includes spherical shape (with an association degree of 1.0-1.5), a cocoon shape (with an association degree of 1.5-2.5), a curved long chain shape (with an association degree> 2.5), as well as a spherical shape and a cocoon shape or long chain shape. Type of mixed form.

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention.

The embodiment of the present invention provides a method for preparing a silica sol with a controllable particle shape, which includes the following steps:

S1: Prepare a plurality of alkoxysilanes with a mass content of ≥95% of the acidic combination liquid and a mother liquid containing alkali catalysts, high-purity water and organic solvents and 7＜pH＜11;

S2: adding a set of the acidic combination liquid to the mother liquor to obtain the first silica sol;

S3: Add high-purity water and a set of the acidic combination liquid to the obtained first silica sol at least once to obtain a silica sol primary liquid;

S4: The obtained primary silica sol solution is concentrated and solvent replaced to obtain a silica sol product.

After the acidic combination liquid is quickly added to the mother liquor, with the continuous hydrolysis of the alkoxysilanes, the concentration of silicic acid and silanol groups in the solution will continue to increase for a period of time after the nucleation, and the pH of the system will gradually decrease. After the hydrolysis and condensation reach the equilibrium, that is, after the nucleating particles are formed, the concentration of silicic acid and silanol groups in the solution remains within a certain concentration, and as the particles grow and the concentration of alkoxysilanes decreases, silicic acid and silane The alcohol base concentration began to drop, and the pH value began to rise again. With the replenishment of high-purity water and acidic combination liquid, a new balance will be formed after hydrolysis and condensation, and the pH value of the system will once again fluctuate. When the system has a lower pH value and a higher concentration of silicic acid or silanol, The particles have a tendency to grow linearly, and on the contrary, the particles have a tendency to grow in a three-dimensional direction. The change of the initial acid value in the acidic combination liquid will affect the acid value when the system reaches an equilibrium state, thereby affecting the morphology of the particles. In this way, the growth state of the particles is adjusted to obtain silica sols with different particle morphologies.

For quick addition, it refers to the addition state of non-controlled flow. The method of adding the non-controlled flow is not particularly limited. It can be natural inflow, or can be added by pressurization. There is no particular limitation on the container for receiving the acidic combination liquid, and it may be a tank-type container with stirring, or a tube-type reactor.

The temperature of the fast-added high-purity water or acidic combination liquid itself can be appropriately set according to the temperature of the mother liquid, that is, the temperature of the mother liquid needs to be maintained approximately constant after the high-purity water or the acidic combination liquid is rapidly added.

The secondary particle size test method of the dynamic light scattering method is to dilute the silica sol sample with high-purity water to 0.4%w/w solid content, and use the dynamic light scattering method nanoparticle sizer to test its kinetic hydration average diameter.

BET specific surface area method: The obtained silica sol was dried at (300 ℃) to obtain a dry gel powder, taking 0.2g dried gel powder obtained by the nitrogen adsorption specific surface area S _B BET method.

Wet specific surface area method: Ultrasound the obtained silica sol sample for 5 minutes, place it at a constant temperature of 35°C for 30 minutes, and test it in a low-field nuclear magnetic resonance surface characteristic analyzer. The test conditions are: magnetic field strength 0.5T, nuclear 1H NMR measurement, measurement method: CPMG pulse sequence method, sample volume 1.0ml, temperature 35°C. Calculated by the following formula: S _N = (R _b *R _sp )/(Ψ _{p *} k _A ), where k _A =0.000044 or 0.00026, R _b is the reciprocal of the relaxation time of the solvent, and R _sp is the silica sol The relative relaxation coefficient of the sample, Ψ _p is the volume ratio of silica gel particles in the silica sol sample.

In order to better illustrate the preparation method of the silica sol with controllable particle morphology provided in the embodiments of the present invention, the following examples are used to further illustrate.

Example 1

A method for preparing silica sol with controllable particle morphology includes the following steps:

S1: Add 123.8g of tetraethoxysilane with a water content of 0.23% to a 500ml flask with a reflux tube which is connected to the atmosphere through a glass tube containing a desiccant, and heat to reflux under normal pressure to obtain an acidity of 0.01mol /L of acidic liquid. Take 665.3g of tetraethoxysilane and 47.5g of the above-mentioned acidic liquid as the first group of two-component acidic combination; 76.3g of the above-mentioned acidic liquid and 1068.5g of tetraethoxysilane as the second group of two-component acidic combination The mother liquor is composed of 1460.2g ethanol, 572.4g high-purity water, and 8.6g26% ammonia water;

S2: Add the two components of the first acid combination liquid to the above mother liquor in a 10L four-neck flask containing a reflux device, a thermometer and two feeding ports at 55°C at the same time to obtain a reaction liquid;

S3: Add 829.4g of high-purity water to the obtained reaction solution after an interval of 2 hours. After the addition is complete, quickly add the second acid combination solution and react at 55°C for 12 hours to obtain a silica sol primary solution.

Transfer 2671.4g of the above-mentioned silica sol primary liquid with a mass solid content of 11.3% into a 3L three-necked flask with a constant pressure funnel, thermometer and fractionation head, and take another 2056.8g of the above-mentioned silica sol primary liquid with a mass solid content of 11.3% as supplements The liquid is added to the constant pressure funnel, the silica sol is distilled and concentrated to a mass solid content of 20% under the condition of maintaining a constant liquid level. Continue to add high purity water into the constant pressure funnel while keeping the liquid level in the container approximately constant. Distillation is stopped until the distillate and solution temperature are both 100°C.

The primary solid content of the silica sol primary liquid and the solid content, pH, viscosity, conductivity, particle true density, secondary particle size D ₂ (measured by dynamic light scattering method), primary particle size D ₁ (gas adsorption) of the final product obtained Measured by BET method), the degree of association, the coefficient of variation of primary particle size CV and the sum of metal content (<1ppm) are shown in Table 1 and Table 2. The resulting final silica sol product can be seen in the TEM that the particles are quasi-spherical (as shown in Figure 1). Table 1 project index One-time solid content% 11.3 Solid content% 19.8 pH 7.3 Viscosity mPa•s 3.6 Conductivity μS/cm 192 True density of particles g/cm ³ 1.95 Primary particle size (Gas adsorption BET method) nm 35.3 Secondary particle size (dynamic light scattering) nm 43.2 Degree of association 1.22 S _N /S _B 4.7 Coefficient of variation of primary particle size CV 6.2 Table 2 Metal ion ppm (ICP-MS) Na Al Ca Ni Zn Pb Mg K Fe Cu Sn Ti 0.089 0.04 ＜0.02 ＜0.005 ＜0.02 ＜0.005 0.006 0.101 0.007 0.006 ＜0.005 ＜0.005

Example 2

A method for preparing silica sol with controllable particle morphology includes the following steps:

S1: Put 990g of tetraethoxysilane with 0.23% water content into a 1000ml flask with a condenser reflux tube. The condenser tube is connected to the atmosphere through a glass tube containing a desiccant, and heated to reflux under normal pressure to obtain an acidity of 0.00167mol/ The first group of alkoxysilane acidic combination liquid of L; add 1145g of tetraethoxysilane with 0.23% water content into a 2000ml flask with a condenser reflux tube, the condenser tube is connected to the atmosphere through a glass tube containing a desiccant, Heat to reflux under normal pressure to obtain the second group of alkoxysilane acidic combination liquid with acidity of 0.00077mol/L; add 1145g of tetraethoxysilane with a water content of 0.23% into a 2000ml flask with a condenser reflux tube, condenser tube Connected to the atmosphere through a glass tube containing a desiccant, and heated to reflux under normal pressure to obtain the third group of alkoxysilane acidic combination liquid with acidity of 0.00057mol/L; the mother liquor is composed of 1460.2g ethanol, 572.4g high-purity water, and 8.6g26% ammonia ；

S2: Add the first group of alkoxysilane acidic combination liquids to the above-mentioned mother liquid in a 10L four-neck flask containing a reflux device, a thermometer and two feeding ports at 55°C to obtain a reaction liquid;

S3: Add 829.4g of high-purity water to the obtained reaction solution after an interval of 2 hours. After the addition is complete, quickly add the second group of alkoxysilane acidic combination solution to continue the heat preservation reaction;

S4: After an interval of 3 hours, continue to add 829.4g of high-purity water. After the addition is completed, quickly add the third group of alkoxysilane acid combination liquid, and react at 55°C for 15 hours to obtain a silica sol primary liquid.

Transfer 4711.5g of the above-mentioned primary silica sol with a mass solid content of 13.5% into a 5L three-necked flask with a constant pressure funnel, thermometer and fractionation head, and take 2268.5g of the above-mentioned primary silica sol with a mass solid content of 13.5% as supplement The liquid is added to the constant pressure funnel, the silica sol is distilled and concentrated to a mass solid content of 20% under the condition of maintaining a constant liquid level. Continue to add high purity water into the constant pressure funnel while keeping the liquid level in the container approximately constant. Distillation is stopped until the distillate and solution temperature are both 100°C.

The primary solid content of the silica sol primary liquid and the solid content, pH, viscosity, conductivity, particle true density, secondary particle size D ₂ (measured by dynamic light scattering method), primary particle size D ₁ (gas adsorption) of the final product obtained Measured by BET method), the degree of association, the coefficient of variation of primary particle size CV and the sum of metal content (<1ppm) are shown in Table 3 and Table 4. The resulting final silica sol product can be seen in the TEM that the particles are quasi-spherical (as shown in Figure 2). table 3 project index One-time solid content% 13.5 Solid content% 19.9 pH 7.2 Viscosity mPa•s 3.2 Conductivity μS/cm 187 True density of particles g/cm ³ 1.92 Primary particle size (Gas adsorption BET method) nm 43.2 Secondary particle size (dynamic light scattering method) nm 59.1 Degree of association 1.37 S _N /S _B 5.2 Coefficient of variation of primary particle size CV 8.3 Table 4 Metal ion ppm (ICP-MS) Na Al Ca Ni Zn Pb Mg K Fe Cu Sn Ti 0.109 0.04 ＜0.02 ＜0.005 ＜0.02 ＜0.005 0.006 0.120 0.007 0.008 ＜0.005 ＜0.005

Example 3

A method for preparing silica sol with controllable particle morphology includes the following steps:

S1: Add 266.9g of tetraethoxysilane with 0.23% water content to a 500ml flask with a condenser reflux tube. The condenser tube is connected to the atmosphere through a glass tube containing a desiccant and heated to reflux under normal pressure to obtain an acidity of 0.01 mol. /L of acidic liquid. Mix 866.2g of tetraethoxysilane and 123.8g of the above-mentioned acidic liquid as the first group of alkoxysilane acidic liquid; mix 1001.7g of tetraethoxysilane and 143.1g of the above-mentioned acidic liquid as the second group Alkoxysilane acid combination liquid; mother liquor is composed of 1460.2g ethanol, 572.4g high-purity water, 8.6g26% ammonia water;

S2: The first group of alkoxysilane acidic combination liquids are quickly added to the above-mentioned mother liquid in a 10L four-neck flask containing a reflux device, a thermometer and two feeding ports at 60°C to obtain a reaction liquid;

S3: Add 829.4g of high-purity water to the obtained reaction solution after an interval of 1.5 hours. After the addition is complete, quickly add the second group of alkoxysilane acidic combination solution, and continue the reaction at 60°C for 12 hours to obtain a silica sol primary solution.

Transfer 2671.4g of the above-mentioned primary silica sol with a mass solid content of 11.3% into a 3L three-necked flask with a constant pressure funnel, thermometer and fractionating head, and take another 2056.8g of the above-mentioned primary silica sol with a mass solid content of 11.3% as supplement The liquid is added to the constant pressure funnel, the silica sol is distilled and concentrated to a mass solid content of 20% under the condition of maintaining a constant liquid level. Continue to add high purity water into the constant pressure funnel while keeping the liquid level in the container approximately constant. Distillation is stopped until the distillate and solution temperature are both 100°C.

The primary solid content of the silica sol primary liquid and the solid content, pH, viscosity, conductivity, particle true density, secondary particle size D ₂ (measured by dynamic light scattering method), primary particle size D ₁ (gas adsorption) of the final product obtained Measured by BET method), the degree of association, the coefficient of variation of primary particle size CV and the sum of metal content (<1ppm) are shown in Table 5 and Table 6. The resulting final silica sol product can see the particles in the shape of a cocoon under TEM (as shown in Figure 3). table 5 project index One-time solid content% 11.3 Solid content% 19.7 pH 7.5 Viscosity mPa•s 3.3 Conductivity μS/cm 199 True density of particles g/cm ³ 1.96 Primary particle size (Gas adsorption BET method) nm 34.1 Secondary particle size (dynamic light scattering method) nm 69.6 Degree of association 2.04 S _N /S _B 4.8 Coefficient of variation of primary particle size CV 5.3 Table 6 Metal ion ppm (ICP-MS) Na Al Ca Ni Zn Pb Mg K Fe Cu Sn Ti 0.097 0.03 ＜0.02 ＜0.005 ＜0.02 ＜0.001 0.005 0.112 0.008 0.008 ＜0.005 ＜0.005

Example 4

A method for preparing silica sol with controllable particle morphology includes the following steps:

S1: Take 0.25g of silicon tetrachloride with an acidity of 35.2mol/L as the acidic liquid; prepare 0.12g of the above acidic liquid and 989.9g of tetraethoxysilane as the two-component first group of alkoxysilane acidic combination liquid . Prepare 0.13g silicon tetrachloride acidic liquid and 1144.7g tetraethoxysilane as the two-component alkoxysilane acidic combination liquid of the second group; the mother liquor is composed of 1460.2g ethanol, 572.4g high-purity water, and 8.6g26% ammonia;

S2: Add the two components of the first group of alkoxysilane acidic combination liquid to the above-mentioned mother liquid in a 5L four-necked flask containing a reflux device, a thermometer and two feeding ports at 60℃ to obtain a reaction liquid;

S3: Add 829.4g of high-purity water to the resulting reaction solution after an interval of 1.5h. After the addition is complete, immediately and quickly add the two components of the second group of alkoxysilane acidic combination solution, and react at 60°C for 12 hours to obtain a silica sol. liquid.

Transfer 2671.4g of the above-mentioned primary silica sol with a mass solid content of 11.3% into a 5L three-necked flask with a constant pressure funnel, thermometer and fractionating head, and take another 2056.8g of the above-mentioned primary silica sol with a mass solid content of 11.3% as supplements The liquid is added to the constant pressure funnel, the silica sol is distilled and concentrated to a mass solid content of 20% under the condition of maintaining a constant liquid level. Continue to add high purity water into the constant pressure funnel while keeping the liquid level in the container approximately constant. Distillation is stopped until the distillate and solution temperature are both 100°C.

The primary solid content of the silica sol primary liquid and the solid content, pH, viscosity, conductivity, particle true density, secondary particle size D ₂ (measured by dynamic light scattering method), primary particle size D ₁ (gas adsorption) of the final product obtained Measured by BET method), the degree of association, the coefficient of variation of primary particle size CV and the sum of metal content (<1ppm) are shown in Table 7 and Table 8. The resulting final silica sol product can be seen in the form of cocoon particles under TEM (as shown in Figure 4). Table 7 project index One-time solid content% 11.3 Solid content% 19.7 pH 7.3 Viscosity mPa•s 3.6 Conductivity μS/cm 212 True density of particles g/cm ³ 1.97 Primary particle size (Gas adsorption BET method) nm 31.6 Secondary particle size (dynamic light scattering method) nm 57.6 Degree of association 1.82 S _N /S _B 4.3 Coefficient of variation of primary particle size CV 6.7 Table 8 Metal ion ppm (ICP-MS) Na Al Ca Ni Zn Pb Mg K Fe Cu Sn Ti 0.129 0.03 ＜0.02 ＜0.005 ＜0.02 ＜0.005 0.007 0.122 0.007 0.005 ＜0.005 ＜0.005

Example 5

A method for preparing silica sol with controllable particle morphology includes the following steps:

S1: Take 0.25g of silicon tetrachloride with an acidity of 35.2mol/L as the acidic liquid A; add 143.1g of tetraethoxysilane with a water content of 0.23% into a 250ml flask with a reflux tube, and the condenser passes through the The glass tube of the desiccant is connected to the atmosphere and heated to reflux under normal pressure to obtain acidic liquid B with an acidity of 0.01 mol/L. Prepare 0.12g of the above-mentioned acidic liquid A and 989.9g of tetraethoxysilane as the two-component first group of alkoxysilane acidic combination liquid; prepare 0.13g of the above-mentioned acidic liquid A and 1144.7g of tetraethoxysilane as the two-component The second group of alkoxysilane acidic combination liquid; 143.1g of the above acidic liquid B and 1001.7g of tetraethoxysilane are mixed as the third group of alkoxysilane acidic combination liquid. The mother liquor is composed of 1460.2g ethanol, 572.4g high-purity water, and 8.6g26% ammonia water;

S2: Add the two components of the first group of alkoxysilane acidic combination liquid at 60°C simultaneously and quickly into the above-mentioned mother liquor in a 10L four-neck flask containing a reflux device, a thermometer and two feeding ports to obtain a reaction liquid;

S3: Add 829.4g of high-purity water to the resulting reaction solution after an interval of 1 hour. After the addition is complete, immediately and quickly add the two components of the second group of alkoxysilane acidic combination solution at the same time, and continue the heat preservation reaction;

S4: After an interval of 1.5h, continue to add 829.4g of high-purity water. After the addition is completed, quickly add the third group of alkoxysilane acid combination liquid, and react at 60°C for 15h to obtain a silica sol primary liquid.

Transfer 4711.5g of the above-mentioned primary silica sol with a mass solid content of 13.5% into a 5L three-necked flask with a constant pressure funnel, thermometer and fractionation head, and take another 2268.5g of the above-mentioned primary silica sol with a mass solid content of 13.5% as supplement The liquid is added to the constant pressure funnel, the silica sol is distilled and concentrated to a mass solid content of 20% under the condition of maintaining a constant liquid level. Continue to add high purity water into the constant pressure funnel while keeping the liquid level in the container approximately constant. Distillation is stopped until the distillate and solution temperature are both 100°C.

The primary solid content of the silica sol primary liquid and the solid content, pH, viscosity, conductivity, particle true density, secondary particle size D ₂ (measured by dynamic light scattering method), primary particle size D ₁ (gas adsorption) of the final product obtained Measured by BET method), the degree of association, the coefficient of variation of primary particle size CV and the sum of metal content (<1ppm) are shown in Table 9 and Table 10. The resulting final silica sol product can be seen in the form of cocoon particles under TEM (as shown in Figure 5). Table 9 project index One-time solid content% 13.5 Solid content% 19.9 pH 7.2 Viscosity mPa•s 3.9 Conductivity μS/cm 205 True density of particles g/cm ³ 1.93 Primary particle size (Gas adsorption BET method) nm 34.3 Secondary particle size (dynamic light scattering method) nm 66.7 Degree of association 1.94 S _N /S _B 4.3 Coefficient of variation of primary particle size CV 5.2 Table 10 Metal ion ppm (ICP-MS) Na Al Ca Ni Zn Pb Mg K Fe Cu Sn Ti 0.119 0.03 ＜0.02 ＜0.005 ＜0.02 ＜0.005 0.008 0.131 0.008 0.005 ＜0.005 ＜0.005

Example 6

A method for preparing silica sol with controllable particle morphology includes the following steps:

S1: Add 1067.5g of tetraethoxysilane with 0.23% water content to a 2000ml flask with a condenser reflux tube. The condenser tube is connected to the atmosphere through a glass tube containing a desiccant, and heated to reflux under normal pressure to obtain an acidity of 0.005mol /L of acidic liquid. Mix 495.0g of tetraethoxysilane and 495.0g of the above acidic liquid to obtain the first group of alkoxysilane acidic liquid; mix 572.5g of tetraethoxysilane and 572.5g of the above acidic liquid to obtain the second group of alkoxy Base silane acid combination liquid. The mother liquor is composed of 1460.2g ethanol, 572.4g high-purity water, and 8.6g26% ammonia water;

S2: The first group of alkoxysilane acidic combination liquids are quickly added to the above-mentioned mother liquid in a 5L four-neck flask containing a reflux device, a thermometer and two feeding ports at 65°C to obtain a reaction liquid;

S3: Add 829.4 g of high-purity water to the obtained reaction solution after an interval of 1 hour. After the addition is complete, quickly add the second group of alkoxysilane acidic combination liquid, and react at 65°C for 12 hours to obtain a silica sol primary liquid.

Transfer 3561.9 g of the above-mentioned silica sol primary liquid with a mass solid content of 11.3% into a 5L three-necked flask with a constant pressure funnel, thermometer and fractionation head, and take another 1166.3 g of the above-mentioned silica sol primary liquid with a mass solid content of 11.3% as supplements The liquid is added to the constant pressure funnel, the silica sol is distilled and concentrated to a mass solid content of 20% under the condition of maintaining a constant liquid level. Continue to add high purity water into the constant pressure funnel while keeping the liquid level in the container approximately constant. Distillation is stopped until the distillate and solution temperature are both 100°C.

The primary solid content of the silica sol primary liquid and the solid content, pH, viscosity, conductivity, particle true density, secondary particle size D ₂ (measured by dynamic light scattering method), primary particle size D ₁ (gas adsorption) of the final product obtained Measured by BET method), the degree of association, the coefficient of variation of primary particle size CV and the sum of metal content (<1ppm) are shown in Table 11 and Table 12. The resulting final silica sol product can be seen in the shape of curved long chains under TEM (as shown in Figure 6). Table 11 project index One-time solid content% 11.3 Solid content% 15.1 pH 7.4 Viscosity mPa•s 5.2 Conductivity μS/cm 192 True density of particles g/cm ³ 1.93 Primary particle size (Gas adsorption BET method) nm 37.3 Secondary particle size (dynamic light scattering method) nm 146.3 Degree of association 3.92 S _N /S _B 5.1 Coefficient of variation of primary particle size CV 3.7 Table 12 Metal ion ppm (ICP-MS) Na Al Ca Ni Zn Pb Mg K Fe Cu Sn Ti 0.096 0.01 ＜0.02 ＜0.005 ＜0.003 ＜0.005 0.005 0.087 0.006 0.003 ＜0.005 ＜0.005

Example 7

A method for preparing silica sol with controllable particle morphology includes the following steps:

S1: Prepare an acetic acid solution to obtain acidic liquid A with an acidity of 0.1 mol/L; add 533.8 g of tetraethoxysilane with a water content of 0.23% to a 1000 ml flask with a condenser reflux tube, and the condenser tube passes through a glass containing a desiccant The tube is connected to the atmosphere and heated to reflux under normal pressure to obtain acidic liquid B with an acidity of 0.005 mol/L. Prepare 742.5g of tetraethoxysilane, 9.9g of the above-mentioned acidic liquid A, 247.5g of the above-mentioned acidic liquid B as the three-component first group of alkoxysilane acidic combination liquid; prepare 11.5g of the above-mentioned acidic liquid A, 286.3g The above-mentioned acidic liquid B and 858.7g of tetraethoxysilane are used as the three-component second group of alkoxysilane acidic combination liquid; prepare 11.5g of the above-mentioned acidic liquid A, 286.3g of the above-mentioned acidic liquid B and 858.7g of tetraethoxy Silane is a three-component acidic combination of alkoxysilanes. The mother liquor is composed of 1460.2g ethanol, 562.6g high-purity water, and 9.0g26% ammonia water;

S2: The three components of the first group of alkoxysilane acidic combination liquids are simultaneously and quickly added to the above-mentioned mother liquid in a 10L four-necked flask containing a reflux device, a thermometer and two feeding ports at 65°C to obtain a reaction liquid;

S3: Add 88.1 g of high-purity water to the resulting reaction solution after an interval of 1 hour. After the addition is complete, immediately and quickly add the three components of the second group of alkoxysilane acidic combination solution at the same time, and continue the heat preservation reaction;

S4: Continue to add 88.1 g of high purity water after an interval of 1 hour. After the addition is complete, immediately add the three components of the third group of alkoxysilane acidic combination liquid at the same time, and react at 60°C for 15 hours to obtain a silica sol primary liquid.

Transfer 6282g of the above-mentioned primary silica sol with a mass solid content of 13.5% into a 10L three-necked flask with a constant pressure funnel, thermometer and fractionating head, and add 698g of the above-mentioned primary silica sol with a mass solid content of 13.5% as the replenishing solution. In the constant pressure funnel, the silica sol is distilled and concentrated to a mass solid content of 15% while maintaining a constant liquid level. Continue to add high-purity water to the constant pressure funnel, while keeping the liquid level in the container approximately constant, while distilling to The temperature of the distillate and the solution is stopped at 100°C.

The primary solid content of the silica sol primary liquid and the solid content, pH, viscosity, conductivity, particle true density, secondary particle size D ₂ (measured by dynamic light scattering method), primary particle size D ₁ (gas adsorption) of the final product obtained Measured by BET method), the degree of association, the coefficient of variation of primary particle size CV and the sum of metal content (<1ppm) are shown in Table 13 and Table 14. The resulting final silica sol product can be seen in the shape of curved long chains under TEM (as shown in Figure 7). Table 13 project index One-time solid content% 13.5 Solid content% 14.9 pH 7.2 Viscosity mPa•s 5.8 Conductivity μS/cm 215 True density of particles g/cm ³ 1.93 Primary particle size (Gas adsorption BET method) nm 43.2 Secondary particle size (dynamic light scattering method) nm 206.6 Degree of association 4.78 S _N /S _B 5.6 Coefficient of variation of primary particle size CV 4.5 Table 14 Metal ion ppm (ICP-MS) Na Al Ca Ni Zn Pb Mg K Fe Cu Sn Ti 0.107 0.03 ＜0.02 ＜0.005 ＜0.02 ＜0.005 0.006 0.121 0.007 0.008 ＜0.005 ＜0.005

From the above data, the method for preparing silica sol with controllable particle morphology provided by the embodiment of the present invention is to alternately add the acid composition liquid containing alkoxysilane and high-purity water to the mother liquor containing the alkali catalyst by controlling each The change of the acid value of the acidic combination liquid realizes the control of the particle morphology of the silica sol, and the spherical and non-spherical silica sol is obtained. The primary solid content of the obtained silica sol is more than 10%, and the metal ion content is less than 1 ppm.

The present invention has been described in detail above, but what is described above is only a preferred embodiment of the present invention, and should not be used to limit the scope of implementation of the present invention, that is, everything made in accordance with the scope of the patent application of the present invention is equal Changes and modifications should still fall within the scope of the patent of the present invention.

Figure 1 is a TEM image of the silica sol in Example 1 of the present invention.

Figure 2 is a TEM image of the silica sol in Example 2 of the present invention.

Figure 3 is a TEM image of the silica sol in Example 3 of the present invention.

Figure 4 is a TEM image of the silica sol in Example 4 of the present invention.

Figure 5 is a TEM image of the silica sol in Example 5 of the present invention.

Figure 6 is a TEM image of the silica sol in Example 6 of the present invention.

Figure 7 is a TEM image of the silica sol in Example 7 of the present invention.

Claims (10)

A method for preparing silica sol with controllable particle morphology includes the following steps: S1: Prepare a plurality of alkoxysilanes with a mass content of ≥95% of the acidic combination liquid and a mother liquid containing alkali catalysts, high-purity water and organic solvents and 7＜pH＜11; S2: adding a set of the acidic combination liquid to the mother liquor to obtain the first silica sol; S3: Add high-purity water and a set of the acidic combination liquid to the obtained first silica sol at least once to obtain a silica sol primary liquid; S4: The obtained primary silica sol solution is concentrated and the solvent is replaced to obtain a silica sol product. The method for preparing silica sol with controllable particle morphology according to claim 1, wherein the acidic composition liquid is a mixture of alkoxysilane and acidic substance, or a partial hydrolysis reaction between alkoxysilane and high-purity water contains acidic substance. mixture. The method for preparing silica sol with controllable particle morphology according to claim 1, wherein the acidic combination liquid is a mixture of alkoxysilane and acidic substance or a double-use alkoxysilane and acidic substance at the same time but not pre-mixed. Ingredients or plural ingredients. The method for preparing silica sol with controllable particle morphology according to claim 1, wherein, if the expected morphology of the silica particles in the silica sol product is spherical, N _n-1 (H ⁺ ) ≥ 0.5 N _n (H ⁺ ), and N _i (H ⁺ )/V _s <6×10 ^-4 mol/L; if the expected morphology of the silica particles in the silica sol product is a cocoon shape, then N _{n- 1} (H ⁺ )≤N _n (H ⁺ ), and N _i (H ⁺ )/V _s ＞3.5×10 ^-4 mol/L; if the expected morphology of the silica particles in the silica sol product is curved and long In chain shape, N _n-1 (H ⁺ ) _{≤ N n} (H ⁺ ), and N _i (H ⁺ )/V _s ＞5.5×10 ^-4 mol/L, where N _n (H ⁺ ) is added to the acid value of the n-th liquid acidic composition, and n is an integer of 2 or more, the unit is mol, N _i (H ⁺⁾ was added to the acid value of any of the liquid acidic composition, expressed in mol, V _{S is} the volume of the organic solvent in the mother liquor, and the unit is L. The method for preparing silica sol with controllable particle morphology according to claim 2, wherein N ₁ (SiO ₂ )/V _S > 1.5 mol/L, and N _i (SiO ₂ )/N ₁ (SiO ₂ )> 1.2, where N ₁ (SiO ₂ ) is the amount of silicon dioxide formed by the acidic combination liquid added for the first time, and N _i (SiO ₂ ) is the amount of silicon dioxide formed by the acidic combination liquid added for the i-th time The quantity and i is an integer greater than or equal to 2, and the unit is mol. The particle morphology of the requested item 3 controllable silicon sol preparation, wherein the step S2 and / or ^{_{S3,, N i (H +):}} N i (SiO 2): N i (H 2 O): N (N): N _i (OS)=(6×10 ^-5 ~10 ^-3 ):1:(4~10):(0.003~0.03): (1.5-5), where N _i (H ₂ O) is the amount of the high-purity water in the bottom solution before adding the acidic composition for the i time; N (N) is the amount of the alkali catalyst; N _i (OS) is the amount before adding the acidic composition for the i The amount of the organic solvent in the base liquid, the unit is mol. The method for preparing silica sol with controllable particle morphology according to claim 1, wherein in step S2 and/or S3, the reaction temperature is 35-80°C. The method for preparing silica sol with controllable particle morphology according to claim 1, wherein, in step S3, when the acidic composition is added, the time interval from the previous addition of the acidic composition is 0.5-5h; and/or In step S3, the reaction time after adding the acidic combination liquid for the last time is 12-15 hours. The method for preparing a silica sol with controllable particle morphology according to any one of claims 1 to 8, wherein the alkoxysilane is tetraethoxysilane or a condensation polymer thereof, and the alkali catalyst is a nitrogen-containing non-metallic type Alkaline catalyst, the organic solvent is an alcohol solvent. A silica sol with controllable particle morphology is prepared by the preparation method of silica sol with controllable particle morphology according to any one of claims 1 to 9.

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