WO2020078031A1 - 一种低比表面积高分散性增稠型二氧化硅及其制备方法 - Google Patents

一种低比表面积高分散性增稠型二氧化硅及其制备方法 Download PDF

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WO2020078031A1
WO2020078031A1 PCT/CN2019/092440 CN2019092440W WO2020078031A1 WO 2020078031 A1 WO2020078031 A1 WO 2020078031A1 CN 2019092440 W CN2019092440 W CN 2019092440W WO 2020078031 A1 WO2020078031 A1 WO 2020078031A1
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silica
surface area
specific surface
solution
sodium silicate
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PCT/CN2019/092440
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English (en)
French (fr)
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王宪伟
郑松玲
庹文喜
李飞虎
洪清华
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肇庆金三江硅材料有限公司
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Publication of WO2020078031A1 publication Critical patent/WO2020078031A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
    • C01B33/187—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates
    • C01B33/193—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates of aqueous solutions of silicates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/16—Pore diameter
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/19—Oil-absorption capacity, e.g. DBP values
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability

Definitions

  • the invention belongs to the technical field of silica, and particularly relates to a thickened silica with low specific surface area and high dispersion and a preparation method thereof.
  • Silica is a spherical porous structure, without sharp edges and corners, does not wear teeth too much, and has the characteristics of stable physical and chemical properties, good compatibility with toothpaste systems, and can be used in the preparation of transparent toothpaste. Used in the toothpaste industry.
  • Silica for toothpaste is divided into three series: friction type, comprehensive type and thickening type.
  • Thickened silica can provide good pseudoplasticity and thixotropy for the paste, because thickened silica is a three-dimensional network structure composed of silica tetrahedron, which can be highly dispersed in aqueous solution, and Turn a large amount of free water into bound water in the network structure.
  • this network structure is destroyed by external forces, it can quickly become a low-viscosity suspension. Once the external forces are eliminated, the network structure can use its surface The hydrogen bond of the hydroxyl group returns to the state of homogeneous plastic body, and the viscosity gradually increases.
  • the paste In the process of making and using toothpaste, the paste has good pseudoplasticity and thixotropy, can withstand mechanical processing, and the components will not be damaged. At the same time, during the fluidization process, the reduction of paste viscosity is beneficial to filling The friction force increases the production efficiency; after standing, the apparent viscosity of the paste gradually increases, the shape of the tube is full, and the extruded toothpaste has strong adhesion, while ensuring its storage stability to meet the requirements of toothpaste shelf life.
  • the addition amount of thickened silica is generally between 5% and 8%, and there is a phenomenon that the transparency of toothpaste will be reduced for a long time, and the thickened silica is in the aqueous solution and the sorbitol solution It is not easy to disperse and there is agglomeration phenomenon, which requires a long time for homogenization in the preparation of toothpaste.
  • due to the porous structure of silica it will absorb more flavors in the preparation of toothpaste, and the flavors evaporate quickly when brushing teeth. Not conducive to the purpose of keeping the mouth fresh and lasting. Therefore, it is necessary to develop a thickened silica with high dispersion, low specific surface area, high viscosity and high transparency.
  • Patent document CN106185956A discloses a method for preparing thickened silica for toothpaste, which includes (1) using solid sodium silicate with a modulus of 3.40 ⁇ 3.50 to dissolve and add water to prepare a density of 1.080 ⁇ 1.085g / cm 3 . It is 10-20% dilute sulfuric acid; (2) Synthesis reaction: A.
  • the silica has an oil absorption value of 250 to 300 ml / 100 g and a water absorption of 56 to 60 ml / 20 g, the viscosity is low, only 3000 to 4000 centipoise, and it needs to be added at 5% to 8% to be better It has a thickening effect and a large specific surface area of 240 to 280 m 2 / g, which results in poor dispersibility, easy absorption of fragrance, and low transparency, and is not suitable for use in transparent toothpaste.
  • the present invention provides a method for preparing silica.
  • the preparation method uses sodium silicate, Sulfuric acid and sodium sulfate are used as reaction raw materials, and through two-step hydrothermal precipitation reaction, thickened silica with high dispersibility, low specific surface area, high viscosity and high transparency is prepared.
  • the preparation method of the thickened silica with low specific surface area and high dispersion provided by the present invention specifically includes the following steps:
  • the silica slurry is filtered through the membrane, the sodium sulfate solution is recovered, and washed, so that the salt content of the washing water of the silica filter cake is 1.6 to 2.0%, and then spray dried, and the air mill is crushed to a particle size of 8 to 11 ⁇ m, thickened silica with low specific surface area and high dispersion was prepared.
  • the mass percentage concentration of the sodium sulfate solution is 0.3-0.5%.
  • the concentration of the sodium silicate solution is 2.0-3.0 mol / L.
  • the concentration of the sulfuric acid solution is 5.0-6.0 mol / L.
  • the concentration percentage of sodium sulfate is 0.15 to 0.25%
  • the concentration of sodium silicate is 1.0 to 1.5 mol / L.
  • the sulfuric acid solution is added dropwise at a flow rate of 3.0 to 3.5 m 3 / h.
  • staged heat preservation and aging is heat preservation and aging at 85 to 95 ° C for 5 to 10 minutes, and then the temperature is reduced to 70 to 75 ° C and the heat and aging is held for 10 to 15 minutes.
  • the concentration of the sodium silicate solution is 0.8-1.2 mol / L.
  • the concentration of the sulfuric acid solution is 1.5-2.0 mol / L.
  • the rotation speed of the stirring is 35-40 Hz.
  • a two-step hydrothermal precipitation reaction is adopted.
  • a low concentration of sodium sulfate is added as a reaction aid at the beginning of the reaction, and the acid drop alkali addition method is used to make the reaction system weakly alkaline, and The reaction is carried out at a low temperature of 50 to 60 ° C, so that the particles of the initial silica particles are uniform and fine, ensuring good dispersion of the subsequent products.
  • a low concentration of sodium sulfate at 50 to 60 ° C also helps to produce transparent and dense
  • water is used as the bottom liquid, at a high temperature of 85 ⁇ 95 °C, the same drop of acid and alkali is added to keep the reaction process
  • the pH value is weakly acidic, so that the silica shell has more microporous structure without reducing the pore size and pore volume, ensuring high oil absorption value, high transparency and low specific surface area of the finished product.
  • the present invention further optimizes the performance of silica and significantly improves the viscosity of silica through multiple heat preservation and aging methods. Specifically, the first step of the reaction is completed, and the heat preservation and aging at 50 to 60 ° C. 10 ⁇ 15min, to make the initial particles more uniform, and to further improve the dispersion of the finished product; after the second step of the reaction, two stages of heat preservation and aging are carried out.
  • Ageing is beneficial to increase the oil absorption value and dispersibility of silica, but under this aging condition, the low specific surface area of silica increases significantly, and the viscosity decreases significantly, and if the ageing temperature is directly reduced to below 80 °C , The viscosity is effectively increased, but the silica agglomeration, resulting in poor dispersion of the finished product, affecting the oil absorption value and transparency.
  • the present invention provides two stages of heat preservation and aging, the first stage of heat preservation and aging at 85 ⁇ 95 °C for 5 ⁇ 10min, at this high temperature for a short period of aging, to ensure dispersion and increase oil absorption value, and then the second The temperature is naturally reduced to 70 ⁇ 75 ° C and aged for 10 ⁇ 15min under this condition. On the one hand, it guarantees the dispersibility and oil absorption value; on the other hand, it reduces the low specific surface area and improves the transparency.
  • the finished product has an excellent thickening effect.
  • the aging temperature of the second stage can not be lower than 70 °C, otherwise the silica will agglomerate, affecting the performance of the finished product.
  • the pH value of the acid titration end point is 4.0 to 5.0, and the acidic system is aged for 10 to 15 minutes under the condition of no heat preservation to stabilize the structure of the silica to obtain high dispersion, low specific surface area and high Viscosity and highly transparent thickened silica.
  • the present invention also provides a low-specific surface area and high-dispersion thickened silica obtained by the above-mentioned preparation method.
  • the silica has an oil absorption value of ⁇ 250 mL / 100 g and a specific surface area of 80-120 m 2 / g.
  • the pore size is 10-14 nm, the viscosity of 15% aqueous dispersion is ⁇ 8000 centipoise, with excellent thickening effect and high dispersibility, the transparency in the range of refractive index 1.4350 ⁇ 1.460 ⁇ 96%, suitable for use in transparent toothpaste, And it can ensure that the transparency of the paste of transparent toothpaste remains basically unchanged after long-term storage.
  • the thickened silica of the present invention has a small specific surface area of 80 to 120 m 2 / g, a large pore volume and pore diameter, an oil absorption value of ⁇ 250 mL / 100 g, and a viscosity of 15% aqueous dispersion of ⁇ 8000 centipoise.
  • the transparency in the range of 1.4350 ⁇ 1.460 is ⁇ 96%, which has the characteristics of high dispersibility, low specific surface area, high viscosity and high transparency, so the amount of its addition can be reduced from the conventional 5% -8% to 2% -3%.
  • Example 1 Thick silica with low specific surface area and high dispersion of the present invention and preparation method thereof
  • the silica slurry is filtered through the membrane, the sodium sulfate solution is recovered, and washed, so that the salt content of the washing water of the silica filter cake is 1.6 to 2.0%, and then spray dried, and the air mill is crushed to a particle size of 8 to 11 ⁇ m, thickened silica with low specific surface area and high dispersion was prepared.
  • the silica slurry is filtered through the membrane, the sodium sulfate solution is recovered, and washed, so that the salt content of the washing water of the silica filter cake is 1.6 to 2.0%, and then spray dried, and the air mill is crushed to a particle size of 8 to 11 ⁇ m, thickened silica with low specific surface area and high dispersion was prepared.
  • Example 3 The present invention has a low specific surface area and high dispersion thickening silica and its preparation method
  • the silica slurry is filtered through the membrane, the sodium sulfate solution is recovered, and washed, so that the salt content of the washing water of the silica filter cake is 1.6 to 2.0%, and then spray dried, and the air mill is crushed to a particle size of 8 to 11 ⁇ m, thickened silica with low specific surface area and high dispersion was prepared.
  • the silica slurry is filtered through the membrane, the sodium sulfate solution is recovered, and washed, so that the salt content of the washing water of the silica filter cake is 1.6 to 2.0%, and then spray dried, and the air mill is crushed to a particle size of 8 to 11 ⁇ m, thickened silica with low specific surface area and high dispersion was prepared.
  • this comparative example differs only in that: S3 and sodium silicate solution are added, the acid addition is stopped, and the temperature is kept at 90 ° C for 15 minutes, and then the sulfuric acid solution is added until the pH value is 4.0. After 10 minutes, the silica slurry was prepared.
  • Example 3 Compared with Example 3, the difference of this comparative example is only that: after the addition of S3 and sodium silicate solution is completed, the addition of acid is stopped, and the aging is carried out at 80 ° C for 15 minutes, then the sulfuric acid solution is added to pH 4.0, and the aging is not carried out After 10 minutes, the silica slurry was prepared.
  • this comparative example differs only in that: in step S3, the second stage is naturally cooled down to 65 ° C and incubated for 15 minutes, then a sulfuric acid solution is added to pH 4.0, and aged for 10 minutes without holding. The silica slurry is prepared.
  • this comparative example differs only in that: in step S1, the mass percentage concentration of sodium sulfate in the mixed solution is 1.0%, while the reaction temperature is increased to 65 ° C.
  • this comparative example differs only in that in step S2, the reaction temperature is reduced to 80 ° C, and the pH value of the reaction process is controlled to 8.
  • Test example performance test of the present invention with low specific surface area and high dispersion thickening silica
  • Oil absorption value According to the national standard QB / T2346-2007 (5.13 oil absorption value);
  • Viscosity Disperse 15g silica samples in 85g water, use Brookfield viscometer (4 # rotor, 20 revolutions / min) to detect the viscosity of the water dispersion;
  • Dispersibility Disperse 5g silica samples in 95g water and 95g sorbitol solution with a mass fraction of 70%, and observe the dispersion of the silica samples;
  • Examples 1 to 4 of the present invention have a specific surface area of 80 to 120 m 2 / g, a pore size of 10 to 14 nm, a small specific surface area, and a large pore volume and pore size, which can reduce the amount of fragrance adsorption, thereby Reduce the amount of fragrance used, and the rate of evaporation of the fragrance will slow down relatively when you brush your teeth, achieving a lasting and refreshing mouthfeel;
  • the silica of Examples 1 to 4 of the present invention has an oil absorption value ⁇ 250mL / 100g, a viscosity of 15% aqueous dispersion ⁇ 8000 centipoise, and has an excellent thickening effect.
  • the addition amount can be from 5% to 8% reduced to 2% to 3%, effectively reducing the cost of toothpaste;
  • the silica of Examples 1 to 4 of the present invention has a transparency ⁇ 96% in the range of refractive index 1.4350 to 1.460, suitable for application in transparent toothpaste, and it has high dispersibility in water and sorbitol solution and is easy to disperse , No agglomeration, which is helpful to shorten the stirring and homogenization time, thereby reducing the energy consumption of toothpaste production.
  • the high dispersion and high transparency of the silica of the present invention can ensure that the transparent toothpaste paste remains crystal clear after long-term storage ;
  • Example 3 Compared with Example 3, after the reaction in the second step of Comparative Example 1, the product was kept and aged at 90 °C, the oil absorption value and specific surface area were significantly increased, and the pore size and viscosity were significantly reduced; After the second step reaction, the product was aged at 80 °C, and the agglomeration occurred during the aging process, resulting in poor dispersibility and reduced transparency; Comparative Example 3 changed the temperature of the second stage of aging, and the aging process agglomerated, resulting in the finished product The specific surface area increases and the dispersibility becomes worse; Comparative Example 4 changes the concentration and reaction temperature of sodium sulfate in step S1, the oil absorption value and transparency of the finished product decrease, the specific surface area increases and the dispersion becomes worse; Comparative Example 5 changes the steps The reaction temperature and pH value of S2, the specific surface area of the finished product are significantly increased, the pore size and transparency are significantly reduced, and the dispersibility is deteriorated. It can be seen that the steps of the preparation method of the present
  • the thickened silica of Examples 1 to 4 and Comparative Example 6 were applied to transparent toothpaste to prepare a transparent toothpaste with a viscosity of 300,000 centipoise, and the thickened silica of Examples 1 to 4 of the present invention
  • the added amount of silicon is 2% to 3% wt
  • the added amount of thickened silica of Comparative Example 6 is 7% wt. It can be seen that the added amount of thickened silica of the present invention is low, which can effectively reduce the cost of toothpaste;
  • the toothpaste using the thickened silica of Examples 1 to 4 of the present invention after being stored for 12 months, still maintains crystal clarity, and has no adverse phenomena such as water leakage and anti-coarse.

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Abstract

提供了一种低比表面积高分散性增稠型二氧化硅及其制备方法。方法包括S1、向反应罐中加入硫酸钠溶液和硅酸钠溶液，得到混合液，加热并保持反应温度为50~60℃，搅拌下滴加硫酸溶液至pH值为6~7，陈化；S2、继续向反应罐中加水，加热并保持反应温度为85~95℃，加入硅酸钠溶液和硫酸溶液进行并流反应，控制反应过程pH值为6~7；S3、加完硅酸钠溶液，进行分段陈化，接着加入硫酸至pH值为4.0~5.0，陈化，制得浆料；S4、浆料经过压滤，洗涤，喷雾干燥，气流磨破碎，制得增稠型二氧化硅。得到的增稠型二氧化硅兼备高分散性、低比表面积、高粘度和高透明的特性，具有良好的应用前景。

Description

一种低比表面积高分散性增稠型二氧化硅及其制备方法 技术领域
本发明属于二氧化硅技术领域，具体涉及一种低比表面积高分散性增稠型二氧化硅及其制备方法。
背景技术
二氧化硅是球状的多孔结构，没有尖锐的棱角不会过多的磨损牙齿，且具有物理化学性质稳定、与牙膏体系相容性好、能用于透明牙膏的制备等特点，目前已被广泛应用于牙膏行业中。
牙膏用二氧化硅分为磨擦型、综合型和增稠型三种系列。增稠型二氧化硅可为膏体提供很好的假塑性和触变性，这是因为增稠型二氧化硅是由硅氧四面体构成的三维网状结构，可在水溶液中高度分散，并使大量自由水转变为网络结构中的结合水，当这种网状结构在受到外力的破坏作用时，可迅速变为低粘滞性的悬浮液，外力一旦消除，网状结构可利用其表面羟基的氢键作用恢复成均相塑性体状态，粘度逐渐增大。在牙膏的制作和使用过程中，膏体的假塑性和触变性好，可经得起机械加工，组分不会受到破坏，同时在流态化过程中，膏体粘度的降低有利于灌装的磨擦力，提高生产效率；静止后，膏体表观粘度逐渐增大，管体形状丰满，挤出的牙膏粘附性强，同时保证其贮藏稳定性，以满足牙膏货架期的要求。
通常，中低档牙膏出于成本考虑，不愿使用价格较高的增稠型二氧化硅，只是单纯选用羧甲基纤维素钠作为增稠剂，但是依靠增加羧甲基纤维素钠的用量来提高膏体粘度，会使膏体过稠，牙膏长期贮存后会发生出水、反粗现象，且牙膏外观无光泽，刷牙粘口，影响消费者的购买欲。目前牙膏制备中，增稠型二氧化硅的添加量一般在5％～8％之间，且存在牙膏长时间保存透明度会降低的现象，并且增稠型二氧化硅在水溶液和山梨醇溶液中不易分散，存在团聚现象，导致在牙膏制备中需较长的搅拌均质时间，同时由于二氧化硅的多孔结构，用于牙膏制备中会吸附较多的香精，且在刷牙时香精挥发快，不利于达到保持口腔持久清爽的目的。因此，必要研发出一种具有高分散、低比表面积、高粘度、高透明的增稠型二氧化硅。
专利文献CN106185956A公开了一种牙膏用增稠型二氧化硅的制备方法，包括(1)使用模数3.40～3.50固体硅酸钠经溶解后加水配制成密度1.080～1.085g/cm 3，配制浓度为10～20％稀硫酸；(2)合成反应：A、将硅酸钠水溶液按每釜总量的71～90％加入到反应釜中，并同时按每釜硅酸钠水溶液总体积的10～20％加入水，开动搅拌，用饱和蒸汽直接升温，升温至80～90℃时，将10～20％稀硫酸滴加到反应釜中，当悬浮液pH值达到9.5～10.5时，停止加酸，控制加酸时间为30～40分钟；B、将每釜剩余的硅酸钠水溶液，占每釜总量的10～29％，和10～20％的稀硫酸同时滴加到反应釜中，反应时间40～50分钟，反应过程保持悬浮液pH值9.5～10.5，反应温度80～90℃；C、继续向反应釜中滴加10-20％稀硫酸，直至悬浮液pH值到 4.0～5.0，停止加酸，控制反应时间20～30分钟，反应温度80～90℃，然后保温陈化30～50分钟，反应结束；经过滤洗涤、滤饼浆化、干燥粉碎制得产品。虽然该二氧化硅的吸油值250～300ml/100g，吸水量56～60ml/20g，但是粘度低，仅为3000～4000厘泊，需要在5％～8％的添加量下才有较好的增稠效果，并且其比表面积大，为240～280m 2/g，导致其分散性较差，容易吸附香精，同时其透明度低，不适合应用于透明牙膏中。
因此，急需开发出一种具有高分散性、低比表面积、高粘度、高透明的增稠型二氧化硅。
发明内容
为了解决现有增稠型二氧化硅存在的问题(如分散性差、比表面积大、粘度和透明度低等)，本发明提供了一种二氧化硅的制备方法，该制备方法以硅酸钠、硫酸和硫酸钠作为反应原料，通过两步水热沉淀反应，制得兼备高分散性、低比表面积、高粘度和高透明的增稠型二氧化硅。
本发明提供的低比表面积高分散性增稠型二氧化硅的制备方法，具体包括以下步骤：
S1、往反应罐加入硫酸钠溶液和硅酸钠溶液，得到混合液10～14m 3，加热并保持反应温度为50～60℃，搅拌下滴加硫酸溶液至pH值为6～7，停止加酸，保温陈化10～15min；
S2、继续往反应罐加入水4～6m 3，接着加热并保持反应温度为85～95℃，然后以11～13m 3/h的流速加入硅酸钠溶液3～5m 3，30s后加入硫酸溶液进行并流反应，控制反应过程pH值为6～7；
S3、硅酸钠溶液添加完毕，停止加酸，进行分段保温陈化，接着加入硫酸溶液至pH值为4.0～5.0，陈化10～15min，制得二氧化硅浆料；
S4、二氧化硅浆料经过隔膜压滤，回收硫酸钠溶液，洗涤，使二氧化硅滤饼的洗涤水中盐含量为1.6～2.0％，再经喷雾干燥，气流磨破碎至粒径为8～11μm，制得低比表面积高分散性增稠型二氧化硅。
进一步地，所述硫酸钠溶液的质量百分比浓度为0.3～0.5％。
进一步地，所述步骤S1中，硅酸钠溶液的浓度为2.0～3.0mol/L。
进一步地，所述步骤S1中，硫酸溶液的浓度为5.0～6.0mol/L。
进一步地，所述混合液中，硫酸钠的质量百分比浓度为0.15～0.25％，硅酸钠的浓度为1.0～1.5mol/L。
进一步地，所述步骤S1中，以3.0～3.5m 3/h的流速滴加硫酸溶液。
进一步地，所述分段保温陈化为在85～95℃下保温陈化5～10min，然后降温至70～75℃并保温陈化10～15min。
进一步地，所述步骤S2中，硅酸钠溶液的浓度为0.8～1.2mol/L。
进一步地，所述步骤S2和S3中，硫酸溶液的浓度为1.5～2.0mol/L。
进一步地，所述搅拌的转速为35～40Hz。
在本发明的制备方法中，采用两步水热沉淀反应，第一步在反应初始加入低浓度的硫酸钠作为反应助剂，采用酸滴碱的加料方式，使反应体系呈弱碱性，并且在50～60℃中低温下进行反应，使得二氧化硅初始粒子的颗粒均匀、细腻，保证后续成品的良好分散性，同时在50～60℃下低浓度的硫酸钠也有助于制得透明致密的核结构，以提高二氧化硅的透明度和降低二氧化硅的比表面积；第二步以水作为底液，在85～95℃高温下，采用酸碱同滴的加料方式，保持反应过程的pH值为弱酸性，使得二氧化硅的外壳具有较多的微孔结构同时又不会降低孔径孔容，保证了成品高吸油值、高透明度以及低比表面积。
此外，本发明通过多次保温陈化的方式，进一步优化了二氧化硅的性能且显著提高了二氧化硅的粘度，具体地，第一步反应结束，在50～60℃下保温陈化10～15min，使初始粒子更加均一，进一步提高成品的分散性；第二步反应结束后进行两段保温陈化，发明人发现，体系pH值为6～7时，在85～95℃的高温下陈化，有利于提高二氧化硅的吸油值和分散性，但是该陈化条件下，二氧化硅的低比表面积明显增大，并且粘度明显下降，而如果直接降低陈化温度至80℃以下，粘度得到有效提高，可是二氧化硅发生团聚，导致成品分散性变差，影响至吸油值和透明度下降。因此，本发明设置了两段保温陈化，第一段在85～95℃下保温陈化5～10min，在此高温下进行短时间的陈化，保证分散性且提高吸油值，然后第二段自然降温至70～75℃并保温陈化10～15min，在此条件下陈化，一方面保证分散性和吸油值；另一方面降低低比表面积，提高透明度，再一方面显著提高粘度，使成品具有优良的增稠效果。在这分段保温陈化操作中，第二段的陈化温度不能低于70℃，否则二氧化硅发生团聚，影响成品性能。反应最后加酸滴定终点pH值至4.0～5.0，在此酸性体系且不保温的条件下陈化10～15min，使二氧化硅的结构稳定，以制得兼备高分散性、低比表面积、高粘度和高透明的增稠型二氧化硅。
相应地，本发明还提供了由上述的制备方法获得的低比表面积高分散性增稠型二氧化硅，该二氧化硅的吸油值≥250mL/100g，比表面积为80～120m 2/g，孔径为10～14nm，15％水分散液的粘度≥8000厘泊，具备优良的增稠效果和高分散性，在折光率1.4350～1.460范围内的透明度≥96％，适合应用于透明牙膏中，并且可保证透明牙膏的膏体在长时间存放后透明度基本不变。
因此，与现有技术相比，本发明的优势在于：
(1)本发明增稠型二氧化硅的比表面积小，为80～120m 2/g，孔容孔径大，吸油值≥250mL/100g，15％水分散液的粘度≥8000厘泊，在折光率1.4350～1.460范围内的透明度≥96％，兼备高分散性、低比表面积、高粘度和高透明的特性，因而其添加量可从常规的5％～8％降至2％～3％，并且有利于减少牙膏香精的用量，有效降低生产能耗与成本，相比于现有增稠型二氧化硅，具有更广阔的应用前景。
(2)本发明低比表面积高分散性增稠型二氧化硅的制备方法简单，工艺稳定，条件易控，可工业化生产，能推广应用。
具体实施方式
下面将结合具体实施例来详细说明本发明，在此本发明的示意性实施例以及说明用来解释本发明，但并不作为对本发明的限定。
实施例1、本发明低比表面积高分散性增稠型二氧化硅及其制备方法
使用模数为3.3～3.45的固体硅酸钠，经高温液化后，加水调制浓度分别为2.0mol/L和0.8mol/L的硅酸钠溶液。
S1、往反应罐加入质量百分比浓度为0.3％的硫酸钠溶液5m 3和浓度为2.0mol/L的硅酸钠溶液5m 3，得到混合液10m 3，加热并保持反应温度为50℃，35Hz转速搅拌下以3.0m 3/h的流速滴加浓度为5.0mol/L的硫酸溶液至pH值为6，停止加酸，保温陈化10min；所述混合液中，硫酸钠的质量百分比浓度为0.15％，硅酸钠的浓度为1.0mol/L；
S2、继续往反应罐加入水4m 3，接着加热并保持反应温度为85℃，然后以11m 3/h的流速加入浓度为0.8mol/L硅酸钠溶液3m 3，30s后加入浓度为1.5mol/L硫酸溶液进行并流反应，控制反应过程pH值为6；
S3、硅酸钠溶液添加完毕，停止加酸，进行分段保温陈化，第一段在85℃下保温陈化5min，然后第二段自然降温至70℃并保温陈化10min，接着加入硫酸溶液至pH值为4.0，不保温下陈化15min，制得二氧化硅浆料；
S4、二氧化硅浆料经过隔膜压滤，回收硫酸钠溶液，洗涤，使二氧化硅滤饼的洗涤水中盐含量为1.6～2.0％，再经喷雾干燥，气流磨破碎至粒径为8～11μm，制得低比表面积高分散性增稠型二氧化硅。
实施例2、本发明低比表面积高分散性增稠型二氧化硅及其制备方法
使用模数为3.3～3.45的固体硅酸钠，经高温液化后，加水调制浓度分别为3.0mol/L和1.2mol/L的硅酸钠溶液。
S1、往反应罐加入质量百分比浓度为0.5％的硫酸钠溶液7m 3和浓度为3.0mol/L的硅酸钠溶液7m 3，得到混合液14m 3，加热并保持反应温度为60℃，40Hz转速搅拌下以3.5m 3/h的流速滴加浓度为6.0mol/L的硫酸溶液至pH值为7，停止加酸，保温陈化15min；所述混合液中，硫酸钠的质量百分比浓度为0.25％，硅酸钠的浓度为1.5mol/L；
S2、继续往反应罐加入水6m 3，接着加热并保持反应温度为95℃，然后以13m 3/h的流速加入浓度为1.2mol/L硅酸钠溶液5m 3，30s后加入浓度为2.0mol/L硫酸溶液进行并流反应，控制反应过程pH值为7；
S3、硅酸钠溶液添加完毕，停止加酸，进行分段保温陈化，第一段在95℃下保温陈化10min，然后第二段自然降温至75℃并保温陈化15min，接着加入硫酸溶液至pH值为5.0，不保温下陈化10min，制得二氧化硅浆料；
S4、二氧化硅浆料经过隔膜压滤，回收硫酸钠溶液，洗涤，使二氧化硅滤饼的洗涤水中盐含量为1.6～2.0％，再经喷雾干燥，气流磨破碎至粒径为8～11μm，制得低比表面积高分散性增稠型二氧化硅。
实施例3、本发明低比表面积高分散性增稠型二氧化硅及其制备方法
使用模数为3.3～3.45的固体硅酸钠，经高温液化后，加水调制浓度分别为2.0mol/L和1.0mol/L的硅酸钠溶液。
S1、往反应罐加入质量百分比浓度为0.4％的硫酸钠溶液6m 3和浓度为2.0mol/L的硅酸钠溶液6m 3，得到混合液12m 3，加热并保持反应温度为55℃，35Hz转速搅拌下以3.0m 3/h的流速滴加浓度为5.0mol/L的硫酸溶液至pH值为6.5，停止加酸，保温陈化10min；所述混合液中，硫酸钠的质量百分比浓度为0.2％，硅酸钠的浓度为1.0mol/L。
S2、继续往反应罐加入水5m 3，接着加热并保持反应温度为90℃，然后以12m 3/h的流速加入浓度为1.0mol/L硅酸钠溶液4m 3，30s后加入浓度为1.5mol/L硫酸溶液进行并流反应，控制反应过程pH值为6；
S3、硅酸钠溶液添加完毕，停止加酸，进行分段保温陈化，第一段在90℃下保温陈化5min，然后第二段自然降温至70℃并保温陈化15min，接着加入硫酸溶液至pH值为4.0，不保温下陈化10min，制得二氧化硅浆料；
S4、二氧化硅浆料经过隔膜压滤，回收硫酸钠溶液，洗涤，使二氧化硅滤饼的洗涤水中盐含量为1.6～2.0％，再经喷雾干燥，气流磨破碎至粒径为8～11μm，制得低比表面积高分散性增稠型二氧化硅。
实施例4、本发明低比表面积高分散性增稠型二氧化硅及其制备方法
使用模数为3.3～3.45的固体硅酸钠，经高温液化后，加水调制浓度分别为3.0mol/L和1.0mol/L的硅酸钠溶液。
S1、往反应罐加入质量百分比浓度为0.4％的硫酸钠溶液6m 3和浓度为3.0mol/L的硅酸钠溶液6m 3，得到混合液12m 3，加热并保持反应温度为55℃，40Hz转速搅拌下以3.5m 3/h的流速滴加浓度为6.0mol/L的硫酸溶液至pH值为7，停止加酸，保温陈化15min；所述混合液中，硫酸钠的质量百分比浓度为0.2％，硅酸钠的浓度为1.5mol/L。
S2、继续往反应罐加入水6m 3，接着加热并保持反应温度为95℃，然后以12m 3/h的流速加入浓度为1.0mol/L硅酸钠溶液4m 3，30s后加入浓度为2.0mol/L硫酸溶液进行并流反应，控制反应过程pH值为6；
S3、硅酸钠溶液添加完毕，停止加酸，进行分段保温陈化，第一段在95℃下保温陈化5min，然后第二段自然降温至70℃并保温陈化15min，接着加入硫酸溶液至pH值为4.0，不保温下陈化15min，制得二氧化硅浆料；
S4、二氧化硅浆料经过隔膜压滤，回收硫酸钠溶液，洗涤，使二氧化硅滤饼的洗涤水中盐含量为1.6～2.0％，再经喷雾干燥，气流磨破碎至粒径为8～11μm，制得低比表面积高分散性增稠型二氧化硅。
对比例一
与实施例3相比，本对比例的区别仅在于：S3、硅酸钠溶液添加完毕，停止加酸，90℃下保温陈化15min，接着加入硫酸溶液至pH值为4.0，不保温下陈化10min，制得二氧化硅浆料。
对比例二
与实施例3相比，本对比例的区别仅在于：S3、硅酸钠溶液添加完毕，停止加酸，80℃下保温陈化15min，接着加入硫酸溶液至pH值为4.0，不保温下陈化10min，制得二氧化硅浆料。
对比例三
与实施例3相比，本对比例的区别仅在于：步骤S3中，第二段自然降温至65℃并保温陈化15min，接着加入硫酸溶液至pH值为4.0，不保温下陈化10min，制得二氧化硅浆料。
对比例四
与实施例3相比，本对比例的区别仅在于：步骤S1中，混合液中硫酸钠的质量百分比浓度为1.0％，同时反应温度提高至65℃。
对比例五
与实施例3相比，本对比例的区别仅在于：步骤S2中，降低反应温度至80℃，同时控制反应过程pH值为8。
对比例六
参考专利文献CN106185956A的实施例3，制得二氧化硅。
试验例、本发明低比表面积高分散性增稠型二氧化硅的性能检测
对实施例1～4、对比例一～六的二氧化硅的性能进行检测，检测方法和结果如下：
(1)吸油值：依据国标QB/T2346-2007(5.13吸油值)；
(2)比表面积和孔径：利用静态氮吸附法检测二氧化硅的比表面积和孔径；
(3)粘度：将15g二氧化硅样品分别分散于85g水中，使用Brookfield粘度计(4#转子、20转/min)检测水分散液的粘度；
(4)透明度：按照现有通用的方法(如王宪伟等发表在口腔护理用品工业杂志上的题为“高磨擦透明型二氧化硅的研制及其在牙膏中的应用”的论文中的相应方法)对二氧化硅样品在折光率1.4350～1.460范围内的透明度进行检测，取最高值作为检测结果。
(5)分散性：将5g二氧化硅样品分别分散于95g水和95g质量分数为70％的山梨醇溶液中，观察二氧化硅样品的分散情况；
检测结果如下表1所示。
表1 各二氧化硅的性能检测结果
Figure PCTCN2019092440-appb-000001
由上表1可知：
(3)本发明实施例1～4二氧化硅的比表面积为80～120m 2/g，孔径为10～14nm，具有比表面积小，孔容孔径大的特性，可减少香精的吸附量，从而减少香精的使用量，并且刷牙时香精的挥发速度相对会减慢，达到口腔持久清爽的口感效果；
(4)本发明实施例1～4二氧化硅的吸油值≥250mL/100g，15％水分散液的粘度≥8000厘泊，具备优良的增稠效果，应用于牙膏时，其添加量可从5％～8％降至2％～3％，有效降低了牙膏成本；
(5)本发明实施例1～4二氧化硅在折光率1.4350～1.460范围内的透明度≥96％，适合应用于透明牙膏中，并且其在水和山梨醇溶液中具有高分散性，易分散、不团聚，有利于缩短搅拌均质时间，从而降低 牙膏生产能耗，同时通过本发明二氧化硅的高分散性及高透明度，可保证透明牙膏的膏体在长时间存放后仍保持晶莹透亮；
(6)与对比例六(现有技术)相比，本发明实施例1～4二氧化硅的比表面积更小，孔容孔径更大，并且粘度大、透明度高，具有更好的应用前景；
(7)与实施例3相比，对比例一在第二步反应结束后，产物在90℃下保温陈化，吸油值和比表面积明显增大，孔径和粘度明显减少；对比例二在第二步反应结束后，产物在80℃下保温陈化，陈化过程发生团聚，导致分散性变差，透明度下降；对比例三改变第二段陈化的温度，陈化过程发生团聚，导致成品的比表面积增大，分散性变差；对比例四改变了步骤S1中硫酸钠的浓度及反应温度，成品吸油值和透明度下降，比表面积增大，分散性变差；对比例五改变了步骤S2的反应温度和pH值，成品比表面积明显增大，孔径和透明度明显减少，并且分散性变差。可见，本发明制备方法各步骤相辅相成，协同各操作参数，方能制备出兼备高分散性、低比表面积、高粘度和高透明的增稠型二氧化硅。
此外，分别将实施例1～4和对比例六的增稠型二氧化硅应用于透明牙膏中，制得粘度为30万厘泊的透明牙膏，本发明实施例1～4增稠型二氧化硅的添加量为2％～3％wt，而对比例六增稠型二氧化硅的添加量为7％wt，可见本发明增稠型二氧化硅的添加量低，能有效降低牙膏成本；同时，应用本发明实施例1～4增稠型二氧化硅的牙膏，在存放12个月以后仍保持晶莹透亮，且无出水、反粗等不良现象。
以上仅是本发明的优选实施方式，应当指出的是，上述优选实施方式不应视为对本发明的限制，本发明的保护范围应当以权利要求所限定的范围为准。对于本技术领域的普通技术人员来说，在不脱离本发明的精神和范围内，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。

Claims (10)

  1. 一种低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，包括以下步骤：
    S1、往反应罐加入硫酸钠溶液和硅酸钠溶液，得到混合液10～14m 3，加热并保持反应温度为50～60℃，搅拌下滴加硫酸溶液至pH值为6～7，停止加酸，保温陈化10～15min；
    S2、继续往反应罐加入水4～6m 3，接着加热并保持反应温度为85～95℃，然后以11～13m 3/h的流速加入硅酸钠溶液3～5m 3，30s后加入硫酸溶液进行并流反应，控制反应过程pH值为6～7；
    S3、硅酸钠溶液添加完毕，停止加酸，进行分段保温陈化，接着加入硫酸溶液至pH值为4.0～5.0，陈化10～15min，制得二氧化硅浆料；
    S4、二氧化硅浆料经过隔膜压滤，回收硫酸钠溶液，洗涤，使二氧化硅滤饼的洗涤水中盐含量为1.6～2.0％，再经喷雾干燥，气流磨破碎至粒径为8～11μm，制得低比表面积高分散性增稠型二氧化硅。
  2. 根据权利要求1所述低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，所述硫酸钠溶液的质量百分比浓度为0.3～0.5％。
  3. 根据权利要求1所述低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，所述步骤S1中，硅酸钠溶液的浓度为2.0～3.0mol/L。
  4. 根据权利要求1所述低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，所述步骤S1中，硫酸溶液的浓度为5.0～6.0mol/L。
  5. 根据权利要求1所述低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，所述混合液中，硫酸钠的质量百分比浓度为0.15～0.25％，硅酸钠的浓度为1.0～1.5mol/L。
  6. 根据权利要求1所述低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，所述步骤S1中，以3.0～3.5m 3/h的流速滴加硫酸溶液。
  7. 根据权利要求1所述低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，所述分段保温陈化为在85～95℃下保温陈化5～10min，然后降温至70～75℃并保温陈化10～15min。
  8. 根据权利要求1所述低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，所述步骤S2中，硅酸钠溶液的浓度为0.8～1.2mol/L。
  9. 根据权利要求1所述低比表面积高分散性增稠型二氧化硅的制备方法，其特征在于，所述步骤S2和S3中，硫酸溶液的浓度为1.5～2.0mol/L。
  10. 根据权利要求1～9任一项所述的制备方法获得的低比表面积高分散性增稠型二氧化硅，其特征在于，所述二氧化硅的吸油值≥250mL/100g，比表面积为80～120m 2/g，孔径为10～14nm，15％水分散液的粘度≥8000厘泊，在折光率1.4350～1.460范围内的透明度≥96％。
PCT/CN2019/092440 2018-10-16 2019-06-22 一种低比表面积高分散性增稠型二氧化硅及其制备方法 WO2020078031A1 (zh)

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