CN115385346B - Friction type silicon dioxide and preparation method and application thereof - Google Patents
Friction type silicon dioxide and preparation method and application thereof Download PDFInfo
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- CN115385346B CN115385346B CN202210996943.9A CN202210996943A CN115385346B CN 115385346 B CN115385346 B CN 115385346B CN 202210996943 A CN202210996943 A CN 202210996943A CN 115385346 B CN115385346 B CN 115385346B
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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
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K8/00—Cosmetics or similar toiletry preparations
- A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
- A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
- A61K8/25—Silicon; Compounds thereof
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
- A61Q11/00—Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
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- 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
- C01P2006/10—Solid density
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- C—CHEMISTRY; METALLURGY
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
- C01P2006/65—Chroma (C*)
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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- Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction
Abstract
The invention discloses friction type silicon dioxide and a preparation method and application thereof. The preparation method of the friction type silicon dioxide comprises the following steps: 1) Uniformly mixing a sodium sulfate solution, a sodium hydroxide solution and a sodium silicate solution to obtain a reaction base solution; 2) Continuously adding a sodium silicate solution and a sulfuric acid solution into a reaction base solution, and carrying out a first acid-base parallel flow reaction under an acidic condition to obtain a silica primary product dispersion liquid; 3) Continuously adding a sodium silicate solution and a sulfuric acid solution into the silica primary product dispersion liquid, and carrying out a second acid-base parallel flow reaction under neutral conditions to obtain a silica dispersion liquid; 4) And (3) ageing, press-filtering, washing, drying and crushing the silicon dioxide dispersion liquid to obtain the friction silicon dioxide. The friction type silicon dioxide has the advantages of high apparent density, moderate friction performance, strong cleaning power, good fluorine compatibility, high transparency and the like, and is suitable for being used as an abrasive for preparing transparent toothpaste.
Description
Technical Field
The invention relates to the technical field of toothpaste abrasive materials, in particular to friction type silicon dioxide and a preparation method and application thereof.
Background
Toothpaste is a tooth-cleaning product with very wide application, and mainly comprises abrasive materials (such as silica, calcium hydrophosphate, calcium carbonate and the like), humectant, thickener, surfactant, flavoring agent and the like. The silicon dioxide has the advantages of stable physical and chemical properties, acid and alkali resistance, high temperature resistance, good cleaning performance and the like, and is widely applied to toothpaste in recent years.
The high friction type silicon dioxide needs to keep the transparency to be more than 70 percent (the refractive index is about 1.435-1.460) so as to meet the requirement of transparent toothpaste on the transparency of abrasive materials, but the general apparent density of the silicon dioxide meeting the transparency requirement prepared by the prior art is lower than 0.60g/mL, and the lower apparent density of the silicon dioxide brings adverse effects to a certain extent on the preparation, transportation and application processes (for example, the lower apparent density of the silicon dioxide can cause low package receiving rate of a packaging process, package expansion and bag explosion easily occur in the package receiving process, the apparent density of the silicon dioxide is low, dust emission easily occurs to pollute the air in the use process, and the human body is inhaled to bring a certain effect on the health). The higher the apparent density of the high-friction silica, the higher the RDA value (radioactive enamel abrasion value), whereas an RDA value greater than 250 would cause damage to the teeth (upper RDA value of 250 is prescribed by the american dental association ADA), so the higher the apparent density of the high-friction silica is not.
Therefore, the development of the silicon dioxide with the advantages of high apparent density, moderate friction performance, strong cleaning power, good fluorine compatibility, high transparency and the like has very important significance.
Disclosure of Invention
The invention aims to provide friction type silicon dioxide, and a preparation method and application thereof.
The technical scheme adopted by the invention is as follows:
the preparation method of the friction type silicon dioxide comprises the following steps:
1) Uniformly mixing a sodium sulfate solution, a sodium hydroxide solution and a sodium silicate solution, heating to 50-65 ℃, and adding a sulfuric acid solution until the pH value of the system is 2.0-5.0 to obtain a reaction base solution;
2) Continuously adding a sodium silicate solution and a sulfuric acid solution into a reaction base solution to perform a first acid-base parallel flow reaction, wherein the pH value of the reaction solution is kept at 2.0-5.0 and the reaction temperature is kept at 50-65 ℃ in the reaction process to obtain a silica primary product dispersion liquid;
3) Heating the silica primary product dispersion liquid to 65-70 ℃, regulating the pH value to 6.5-7.5, continuously adding sodium silicate solution and sulfuric acid solution to perform a second acid-base parallel flow reaction, and keeping the pH value of the reaction liquid to 6.5-7.5 and the reaction temperature to 65-70 ℃ in the reaction process to obtain the silica dispersion liquid;
4) Adding 65-70 ℃ water into the silicon dioxide dispersion liquid for ageing, keeping the temperature of the silicon dioxide dispersion liquid at 65-70 ℃ in the ageing process, adjusting the pH value of the silicon dioxide dispersion liquid to 3.0-4.0, performing filter pressing, washing with water with the temperature of more than or equal to 40 ℃ until the conductivity of the washing water is less than or equal to 1000 mu s/cm, and drying and crushing to obtain the friction silicon dioxide.
Preferably, the volume ratio of the sodium sulfate solution, the sodium hydroxide solution and the sodium silicate solution in the step 1) is 20-30:2-10:1.
Preferably, the mass fraction of the sodium sulfate solution in the step 1) is 4.0% -6.0%.
Preferably, the mass fraction of the sodium hydroxide solution in the step 1) is 0.5% -1.0%.
Preferably, the mass fraction of the sodium silicate solution in the step 1) is 18% -23%.
Preferably, the mass fraction of the sulfuric acid solution in the step 1) is 28.5% -32%.
Preferably, the volume ratio of the sodium silicate solution, the sulfuric acid solution and the reaction base solution in the step 2) is 0.49-1.30:0.06-0.47:1.
Preferably, the mass fraction of the sodium silicate solution in the step 2) is 18% -23%.
Preferably, the mass fraction of the sulfuric acid solution in the step 2) is 28.5% -32%.
Preferably, the feeding speed ratio of the sodium silicate solution to the sulfuric acid solution in the step 2) is 2-7.5:1.
Preferably, the volume ratio of the sodium silicate solution, the sulfuric acid solution and the silica primary product dispersion liquid in the step 3) is 0.09-0.34:0.02-0.13:1.
Preferably, the mass fraction of the sodium silicate solution in the step 3) is 18% -23%.
Preferably, the mass fraction of the sulfuric acid solution in the step 3) is 28.5% -32%.
Preferably, the feeding speed ratio of the sodium silicate solution to the sulfuric acid solution in the step 3) is 1.6-10:1.
Preferably, in the step 3), a sodium silicate solution with the mass fraction of 18-23% is adopted to adjust the pH value of the silica primary product dispersion liquid to 6.5-7.5.
Preferably, in the step 4), the volume ratio of the water and the silicon dioxide dispersion liquid at the temperature of 65-70 ℃ is 0.18-0.40:1.
Preferably, the aging time in the step 4) is 20-40 min.
Preferably, in the step 4), the pH value of the silica dispersion liquid is adjusted to 3.0-4.0 by adopting a sulfuric acid solution with the mass fraction of 28.5-32%.
A friction silica made by the method described above.
A toothpaste comprising the abrasive silica described above.
The beneficial effects of the invention are as follows: the friction type silicon dioxide has the advantages of high apparent density, moderate friction performance, strong cleaning power, good fluorine compatibility, high transparency and the like, and is suitable for being used as an abrasive for preparing transparent toothpaste.
Specifically:
1) According to the invention, a mixed solution of sodium sulfate and sodium hydroxide is used as a reaction base solution, a step-by-step heating two-stage acid-base parallel flow reaction mode is adopted, the first stage is acid-base parallel flow reaction under an acidic condition, the second stage is acid-base parallel flow reaction under a neutral condition, sodium hydroxide and sulfuric acid solution are added into the reaction base solution to react to generate sodium sulfate, sodium sulfate content in a reaction system is higher and higher before sodium silicate and sulfuric acid react, the effect of improving the density of silicon dioxide can be achieved, the transparency and fluorine stability of silicon dioxide can be controlled by adopting a step-by-step heating and lower-temperature reaction mode (low reaction rate at low temperature), and finally the silicon dioxide obtained by the reaction has high apparent density, high fluorine stability and high transparency, and has unique sand feeling when being applied to a toothpaste formula and high cleaning capability;
2) The invention adopts water washing products with the temperature more than or equal to 40 ℃ in the filter-pressing washing link, so that the problem of reduced transparency of the products caused by large temperature difference can be avoided;
3) The method firstly carries out acid-base parallel flow reaction under an acidic condition, hydrogen ions dissociated by sulfuric acid in a reaction system are more than alkaline ions dissociated by sodium hydroxide and sodium silicate, gel particles can be generated in the reaction process, and the gel particles have special gritty feel after being dried;
4) The invention adopts two-section acid-base parallel flow reaction, so that the dispersibility and uniformity of the obtained silicon dioxide can be improved;
5) The fluorine compatibility of the friction type silicon dioxide in the stannous fluoride system can reach more than 90%, and the fluorine compatibility in the stannous fluoride system can still reach 80% after 72 hours;
6) The RDA value (radioactive enamel abrasion value) of the friction type silicon dioxide is 180-200, the PCR value (film cleaning rate) is more than or equal to 90, the apparent density is more than or equal to 0.6g/mL, the transparency is more than or equal to 75% (the refractive index is 1.435-1.460).
Detailed Description
The invention is further illustrated and described below in connection with specific examples.
Example 1:
a method for preparing abrasive silica comprising the steps of:
1) Will be 10m 3 Sodium sulfate solution with mass fraction of 5.0% and 5m 3 Adding 1.0% sodium hydroxide solution into a reaction tank 1#, and adding 0.5m 3 Heating sodium silicate solution with mass fraction of 18% with steam to 65deg.C, starting stirrer, and heating with 2.0m 3 Adding sulfuric acid solution with the mass fraction of 28.5% at the feeding speed of/h until the pH value of the system is 3.5, and stopping adding acid to obtain reaction base solution;
2) Continuously adding a sodium silicate solution with the mass fraction of 18% and a sulfuric acid solution with the mass fraction of 28.5% into a reaction tank 1# for carrying out a first acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 At a feed rate of 10m 3 The feed rate of the sulfuric acid solution was 2.5m 3 And/h, maintaining the pH value of the reaction solution at 3.5 and the reaction temperature at 65 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silica primary product dispersion;
3) The reaction tank 1# is communicated with the reaction tank 2# to ensure that the silicon dioxide primary product dispersion liquid is in reflux balance in the reaction tank 1# and the reaction tank 2# until the heights of the feed liquid in the two reaction tanks are consistent, then steam heating is started to ensure that the silicon dioxide primary product dispersion liquid in the two reaction tanks is heated to 65 ℃, a stirrer is started, then a sodium silicate solution with the mass fraction of 18% is added to adjust the pH value of a system to 7.0, and then the sodium silicate solution with the mass fraction of 18% and the mass fraction are addedContinuously adding sulfuric acid solution with the fraction of 28.5% into two reaction tanks to perform a second acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 At a feed rate of 10m 3 The feed rate of the sulfuric acid solution was 2.5m 3 And/h, maintaining the pH value of the reaction solution at 7.0 and the reaction temperature at 65 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silicon dioxide dispersion liquid;
4) Will be 10m 3 Adding process water with the temperature of 65 ℃ into two reaction tanks, stirring and aging for 30min at the temperature of 65 ℃, adding sulfuric acid solution with the mass fraction of 28.5% to adjust the pH value of the system to 4.0, performing filter pressing, washing with the process water with the temperature of 45 ℃ until the conductivity of the washing water is less than or equal to 1000 mu s/cm, and drying and crushing to obtain the friction type silicon dioxide.
As tested, the abrasive silica of this example had an RDA value of 188.54, a PCR value of 196.55, a whiteness of 98.87%, an apparent density of 0.64g/mL, a transparency of 90.9% (refractive index 1.4390), a fluorine compatibility of 95.5% and a special gritty feel for toothpaste.
Note that:
RDA value (radioactive enamel abrasion value): the Hefferren abrasion test recommended by ADA and ISO was used to determine the abrasiveness of the dentifrice in dentine (samples were sent to the university of Indiana in the U.S.A.).
PCR value (film cleaning rate): the method comprises the steps of embedding a tooth standard sample (bovine incisor) on methyl methacrylate resin, polishing the surface of the tooth standard sample to be smooth by utilizing a grinding polisher under constant water flow, sequentially treating the tooth standard sample with hydrochloric acid, sodium carbonate and phytic acid, putting the tooth standard sample into a dyeing device, alternately immersing the tooth standard sample into a dyeing liquid and dry air at a rotating speed of 1r/min, changing the dyeing liquid every two days, evaluating the color change of the standard sample by utilizing a color difference meter, taking an L-shaped value as a qualified standard sample in a range of 30-45, evaluating the L-shaped value on a tooth brushing machine under the condition of respectively using a calcium pyrophosphate suspension and tested grinding brush 800, and calculating a PCR value.
Apparent density: the test was performed with silica in reference to "QB/T2346-2007 toothpaste".
Transparency: the test was performed with silica in reference to "QB/T2346-2007 toothpaste".
Fluorine compatibility:
reagent: sodium fluoride, disodium edetate, trimethylamine, tris, sodium hydroxide, sodium dihydrogen phosphate (1 part of crystal water) and disodium hydrogen phosphate (no water or 2 parts of crystal water).
Instrument: reference electrode, PH/mV meter, fluoride ion selective electrode, glass electrode, high-speed centrifuge, test tube rotator, plastic jar, sealed plastic bottle, plastic centrifuge test tube and magnetic stirrer.
Measurement procedure: 7g of friction silica is added into a plastic beaker, 30g of NaF 1624ppm stock solution is slowly added, the mixture is placed on a rotating frame after being sealed (liquid volatilization is prohibited), the mixture is heated in a rotating way for 1h at 60 ℃, and is centrifuged at 15000rpm for 15min, 2g of supernatant is added into a plastic bottle, 9 times of EDTA/THAM buffer solution with volume is added, the mixture is placed on a stirrer, a fluoride ion selective electrode is inserted, the mixture is read after 1min/72h, and the fluorine compatibility is calculated according to the following formula:
fluorine compatibility (%) = (F in sample solution - F in concentration/Standard solution - Concentration) ×100%.
Preparation of NaF 1624ppm stock solution: 0.6697g of stannous fluoride and 0.9618g of sodium gluconate are dissolved in 98.37g of water and stirred until clear.
Preparation of EDTA/THAM buffer: 74.4g EDTA-2Na+24.2g THAM+800mL H 2 O, pH was adjusted to 8.0 with 5N NaOH solution (50 g NaOH in water and transferred to a volumetric flask, diluted to 250mL and shaken well), transferred to a 1000mL volumetric flask, diluted to scale and transferred to a 1000mL white reagent bottle.
Preparation of a standard sample solution:
a) High standard solution (162.4 ppm): 10g of NaF 1624ppm stock solution was added with 90g of EDTA/THAM buffer and filled into polypropylene plastic bottles;
b) Low standard solution (16.24 ppm): 1g of NaF 1624ppm stock solution is added into 9g of water, then 90g of EDTA/THAM buffer solution is added, and the mixture is filled into a polypropylene plastic bottle;
c) 90% high standard liquid: 9g of NaF 1624ppm stock solution was added to 1g of water, and 90g of EDTA/THAM buffer was added and filled into polypropylene plastic bottles.
Example 2:
a method for preparing abrasive silica comprising the steps of:
1) Will be 15m 3 6.0% sodium sulfate solution and 5m 3 Adding 1.0% sodium hydroxide solution into a reaction tank 1#, and adding 0.5m 3 23% sodium silicate solution by mass fraction, starting steam heating to heat the solution in the reaction tank 1# to 65 ℃, starting a stirrer, and adding 2.0m 3 Adding a sulfuric acid solution with the mass fraction of 32% at the feeding speed of/h until the pH value of the system is 5.0, and stopping adding acid to obtain a reaction base solution;
2) Continuously adding a sodium silicate solution with the mass fraction of 23% and a sulfuric acid solution with the mass fraction of 32% into a reaction tank 1# for carrying out a first acid-base parallel flow reaction, wherein the addition amount of the sodium silicate solution is 15m 3 A feed rate of 15m 3 The feed rate of the sulfuric acid solution was 5.0m 3 And (h) maintaining the pH value of the reaction solution at 5.0 and the reaction temperature at 65 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silica primary product dispersion;
3) The reaction tank 1# is communicated with the reaction tank 2# to ensure that the silicon dioxide primary product dispersion liquid is in reflux balance in the reaction tank 1# and the reaction tank 2# until the heights of the feed liquid in the two reaction tanks are consistent, then steam heating is started to ensure that the silicon dioxide primary product dispersion liquid in the two reaction tanks is heated to 70 ℃, a stirrer is started, then 23 mass percent sodium silicate solution is added to regulate the pH value of the system to 7.5, and then 23 mass percent sodium silicate solution and 32 mass percent sulfuric acid solution are continuously added into the two reaction tanks to carry out second acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 A feed rate of 15m 3 The feed rate of the sulfuric acid solution was 5.0m 3 And/h, maintaining the pH value of the reaction solution at 7.5 and the reaction temperature at 70 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtainA silica dispersion;
4) Will be 10m 3 Adding process water with the temperature of 70 ℃ into two reaction tanks, stirring and aging for 30min at the temperature of 70 ℃, adding sulfuric acid solution with the mass fraction of 32% to adjust the pH value of the system to 3.0, performing filter pressing, washing with process water with the temperature of 50 ℃ until the conductivity of the washing water is less than or equal to 1000 mu s/cm, and drying and crushing to obtain friction type silicon dioxide.
As tested (test method is the same as in example 1), the abrasive silica of this example has an RDA value of 197.73, a PCR value of 104.23, a whiteness of 97.87%, an apparent density of 0.72g/mL, a transparency of 88.9% (refractive index 1.4390), a fluorine compatibility of 97.3% and a special gritty feel for toothpaste.
Example 3:
a method for preparing abrasive silica comprising the steps of:
1) Will be 12m 3 Sodium sulfate solution with mass fraction of 4.0% and 1m 3 Adding 0.5% sodium hydroxide solution into a reaction tank 1#, and adding 0.5m sodium hydroxide solution 3 The sodium silicate solution with the mass fraction of 20 percent is heated by starting steam, so that the temperature of the solution in the reaction tank 1# is raised to 60 ℃, a stirrer is started, and the temperature is increased by 2.0m 3 Adding sulfuric acid solution with the mass fraction of 30% at the feeding speed of/h until the pH value of the system is 4.0, and stopping adding acid to obtain reaction base solution;
2) Continuously adding 20% sodium silicate solution and 30% sulfuric acid solution into a reaction tank 1# to perform a first acid-base parallel flow reaction, wherein the addition amount of the sodium silicate solution is 12m 3 A feed rate of 12m 3 The feed rate of the sulfuric acid solution was 3.0m 3 And (3) maintaining the pH value of the reaction solution at 4.0 and the reaction temperature at 60 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silica primary product dispersion;
3) The reaction tank 1# is communicated with the reaction tank 2# to ensure that the silicon dioxide primary product dispersion liquid is in reflux balance in the reaction tank 1# and the reaction tank 2# until the heights of the feed liquid in the two reaction tanks are consistent, and then steam heating is started to ensure that the silica primary product dispersion liquid in the two reaction tanks is subjected to dioxide heatingHeating the silicon initial product dispersion liquid to 65 ℃, starting a stirrer, adding 20% sodium silicate solution by mass fraction to adjust the pH value of the system to 6.5, continuously adding 20% sodium silicate solution by mass fraction and 30% sulfuric acid solution by mass fraction into two reaction tanks to perform a second acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 12m 3 A feed rate of 12m 3 The feed rate of the sulfuric acid solution was 3.0m 3 And/h, maintaining the pH value of the reaction solution at 6.5 and the reaction temperature at 65 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silicon dioxide dispersion liquid;
4) Will be 10m 3 Adding process water with the temperature of 65 ℃ into two reaction tanks, stirring and aging for 30min at the temperature of 65 ℃, adding sulfuric acid solution with the mass fraction of 30% to adjust the pH value of the system to 3.0, performing filter pressing, washing with process water with the temperature of 45 ℃ until the conductivity of the washing water is less than or equal to 1000 mu s/cm, and drying and crushing to obtain friction type silicon dioxide.
As tested (test method is the same as in example 1), the abrasive silica of this example has an RDA value of 192.73, a PCR value of 99.23, a whiteness of 99.87%, an apparent density of 0.68g/mL, a transparency of 91.4% (refractive index 1.4390), a fluorine compatibility of 98.8% and a special gritty feel for toothpaste.
Comparative example 1:
a silica, the preparation method comprising the steps of:
1) Will be 10m 3 Adding 5.0% sodium sulfate solution into reaction tank 1#, heating with steam to 65deg.C, starting stirrer, and adding 2.0m solution into the reaction tank 1# 3 Adding a sulfuric acid solution with the mass fraction of 32% at the feeding speed of/h until the pH value of the system is 3.5, and stopping adding acid to obtain a reaction base solution;
2) Continuously adding a sodium silicate solution with the mass fraction of 23% and a sulfuric acid solution with the mass fraction of 32% into a reaction tank 1# for carrying out a first acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 At a feed rate of 10m 3 The feed rate of the sulfuric acid solution was 2.5m 3 /h, after reactionIn the process, the pH value of the reaction solution is kept at 3.5, the reaction temperature is 65 ℃, and when the sodium silicate solution is added, the addition of the sulfuric acid solution is stopped immediately, so that the silica primary product dispersion liquid is obtained;
3) The reaction tank 1# is communicated with the reaction tank 2# to ensure that the silicon dioxide primary product dispersion liquid is in reflux balance in the reaction tank 1# and the reaction tank 2# until the heights of the feed liquid in the two reaction tanks are consistent, then steam heating is started to ensure that the silicon dioxide primary product dispersion liquid in the two reaction tanks is heated to 65 ℃, a stirrer is started, then 23 mass percent sodium silicate solution is added to regulate the pH value of the system to 7.0, and then 23 mass percent sodium silicate solution and 32 mass percent sulfuric acid solution are continuously added into the two reaction tanks to carry out second acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 At a feed rate of 10m 3 The feed rate of the sulfuric acid solution was 2.5m 3 And/h, maintaining the pH value of the reaction solution at 7.0 and the reaction temperature at 65 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silicon dioxide dispersion liquid;
4) Will be 10m 3 Adding process water with the temperature of 65 ℃ into two reaction tanks, stirring and aging for 30min at the temperature of 65 ℃, adding sulfuric acid solution with the mass fraction of 32% to adjust the pH value of the system to 4.0, performing filter pressing, washing with process water with the temperature of 45 ℃ until the conductivity of the washing water is less than or equal to 1000 mu s/cm, and drying and crushing to obtain the silicon dioxide.
The comparative silica has an RDA value of 178.66, a PCR value of 96.25, a whiteness of 98.42%, an apparent density of 0.53g/mL, a transparency of 76.7% (refractive index 1.4395), a fluorine compatibility of 92.1% and a special gritty feel for toothpaste, as tested (test method is the same as in example 1).
Comparative example 2:
a silica, the preparation method comprising the steps of:
1) Will be 10m 3 Sodium sulfate solution with mass fraction of 5.0% and 5m 3 Adding 1.0% sodium hydroxide solution into a reaction tank 1#, and adding 5m 3 23% sodium silicate solution by mass, and heating with steam to reactThe solution in tank 1# was warmed to 80℃and the stirrer was started, again at 2.0m 3 Adding a sulfuric acid solution with the mass fraction of 32% at the feeding speed of/h until the pH value of the system is 3.5, and stopping adding acid to obtain a reaction base solution;
2) Continuously adding a sodium silicate solution with the mass fraction of 23% and a sulfuric acid solution with the mass fraction of 32% into a reaction tank 1# for carrying out a first acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 At a feed rate of 10m 3 The feed rate of the sulfuric acid solution was 2.5m 3 And/h, maintaining the pH value of the reaction solution at 3.5 and the reaction temperature at 80 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silica primary product dispersion;
3) The reaction tank 1# is communicated with the reaction tank 2# to ensure that the silicon dioxide primary product dispersion liquid is in reflux balance in the reaction tank 1# and the reaction tank 2# until the heights of the feed liquid in the two reaction tanks are consistent, then steam heating is started to ensure that the silicon dioxide primary product dispersion liquid in the two reaction tanks is heated to 80 ℃, a stirrer is started, then 23 mass percent sodium silicate solution is added to regulate the pH value of the system to 7.0, and then 23 mass percent sodium silicate solution and 32 mass percent sulfuric acid solution are continuously added into the two reaction tanks to carry out second acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 At a feed rate of 10m 3 The feed rate of the sulfuric acid solution was 2.5m 3 And/h, maintaining the pH value of the reaction solution at 7.0 and the reaction temperature at 80 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silicon dioxide dispersion liquid;
4) Will be 10m 3 Adding process water with the temperature of 80 ℃ into two reaction tanks, stirring and aging for 30min at the temperature of 75 ℃, adding sulfuric acid solution with the mass fraction of 32% to adjust the pH value of the system to 4.0, performing filter pressing, washing with normal-temperature process water until the conductivity of the washing water is less than or equal to 1000 mu s/cm, and drying and crushing to obtain the silicon dioxide.
The comparative silica has an RDA value of 231.44, a PCR value of 101.80, a whiteness of 98.56%, an apparent density of 0.62g/mL, a transparency of 67.4% (refractive index 1.4430), a fluorine compatibility of 96.5% and a special gritty feel for toothpaste as tested (test method is the same as example 1).
Comparative example 3:
a silica, the preparation method comprising the steps of:
1) Will be 10m 3 3.0% sodium sulfate solution and 1m 3 Adding 0.5% sodium hydroxide solution into a reaction tank 1#, and adding 0.5m sodium hydroxide solution 3 Heating sodium silicate solution with mass fraction of 18% with steam to 65deg.C, starting stirrer, and heating with 2.0m 3 Adding sulfuric acid solution with the mass fraction of 28.5% at the feeding speed of/h until the pH value of the system is 3.5, and stopping adding acid to obtain reaction base solution;
2) Continuously adding a sodium silicate solution with the mass fraction of 18% and a sulfuric acid solution with the mass fraction of 28.5% into a reaction tank 1# for carrying out a first acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 At a feed rate of 10m 3 The feed rate of the sulfuric acid solution was 2.5m 3 And/h, maintaining the pH value of the reaction solution at 3.5 and the reaction temperature at 65 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain a silica primary product dispersion;
3) The reaction tank 1# is communicated with the reaction tank 2# to ensure that the silicon dioxide primary product dispersion liquid is in reflux balance in the reaction tank 1# and the reaction tank 2# until the heights of the feed liquid in the two reaction tanks are consistent, then steam heating is started to ensure that the silicon dioxide primary product dispersion liquid in the two reaction tanks is heated to 65 ℃, a stirrer is started, then a sodium silicate solution with the mass fraction of 18% is added to adjust the pH value of a system to 7.5, and then 10m of the solution is added 3 Continuously adding a sodium silicate solution with the mass fraction of 18% and a sulfuric acid solution with the mass fraction of 28.5% into two reaction tanks to perform a second acid-base parallel flow reaction, wherein the adding amount of the sodium silicate solution is 10m 3 At a feed rate of 10m 3 The feed rate of the sulfuric acid solution was 2.5m 3 And/h, maintaining the pH value of the reaction solution at 7.0 and the reaction temperature at 65 ℃ in the reaction process, and immediately stopping adding the sulfuric acid solution when the sodium silicate solution is completely added to obtain the silicon dioxide dispersion liquid；
4) Will be 10m 3 Adding process water with the temperature of 65 ℃ into two reaction tanks, stirring and aging for 30min at the temperature of 65 ℃, adding sulfuric acid solution with the mass fraction of 28.5% to adjust the pH value of the system to 4.0, performing filter pressing, washing with the process water with the temperature of 45 ℃ until the conductivity of the washing water is less than or equal to 1000 mu s/cm, and drying and crushing to obtain the silicon dioxide.
The comparative silica has an RDA value of 168.58, a PCR value of 108.28, a whiteness of 98.62%, an apparent density of 0.41g/mL, a transparency of 90.3% (refractive index 1.4390), a fluorine compatibility of 96.4% and a less pronounced gritty feel for toothpaste as tested (test method is the same as example 1).
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (8)
1. A method for preparing friction silica, comprising the steps of:
1) Uniformly mixing a sodium sulfate solution, a sodium hydroxide solution and a sodium silicate solution, heating to 50-65 ℃, and adding a sulfuric acid solution until the pH value of the system is 2.0-5.0 to obtain a reaction base solution;
2) Continuously adding a sodium silicate solution and a sulfuric acid solution into a reaction base solution to perform a first acid-base parallel flow reaction, wherein the pH value of the reaction solution is kept at 2.0-5.0 and the reaction temperature is kept at 50-65 ℃ in the reaction process to obtain a silica primary product dispersion liquid;
3) Heating the silica primary product dispersion liquid to 65-70 ℃, regulating the pH value to 6.5-7.5, continuously adding sodium silicate solution and sulfuric acid solution to perform a second acid-base parallel flow reaction, and keeping the pH value of the reaction liquid to 6.5-7.5 and the reaction temperature to 65-70 ℃ in the reaction process to obtain the silica dispersion liquid;
4) Adding 65-70 ℃ water into the silicon dioxide dispersion liquid for ageing, keeping the temperature of the silicon dioxide dispersion liquid at 65-70 ℃ in the ageing process, adjusting the pH value of the silicon dioxide dispersion liquid to 3.0-4.0, performing filter pressing, washing with water with the temperature of more than or equal to 40 ℃ until the conductivity of the washing water is less than or equal to 1000 mu s/cm, and drying and crushing to obtain the friction silicon dioxide.
2. The method for producing a silica according to claim 1, wherein: the volume ratio of the sodium sulfate solution to the sodium hydroxide solution to the sodium silicate solution in the step 1) is 20-30:2-10:1; the mass fraction of the sodium sulfate solution in the step 1) is 4.0% -6.0%; the mass fraction of the sodium hydroxide solution in the step 1) is 0.5% -1.0%; the mass fraction of the sodium silicate solution in the step 1) is 18-23%.
3. The method for producing a silica according to claim 1, wherein: the volume ratio of the sodium silicate solution to the sulfuric acid solution to the reaction base solution in the step 2) is 0.49-1.30:0.06-0.47:1; the mass fraction of the sodium silicate solution in the step 2) is 18% -23%; the mass fraction of the sulfuric acid solution in the step 2) is 28.5% -32%.
4. The method for producing a silica abrasive according to claim 3, wherein: the feeding speed ratio of the sodium silicate solution to the sulfuric acid solution in the step 2) is 2-7.5:1.
5. The method for producing a silica according to claim 1, wherein: the volume ratio of the sodium silicate solution to the sulfuric acid solution to the silica initial product dispersion liquid in the step 3) is 0.09-0.34:0.02-0.13:1; step 3), the mass fraction of the sodium silicate solution is 18% -23%; the mass fraction of the sulfuric acid solution in the step 3) is 28.5% -32%.
6. The method for producing abrasive silica according to claim 5, wherein: the feeding speed ratio of the sodium silicate solution to the sulfuric acid solution in the step 3) is 1.6-10:1.
7. The method for producing a silica according to any one of claims 1 to 6, wherein: the volume ratio of the water with the temperature of 65 ℃ to 70 ℃ and the silicon dioxide dispersion liquid in the step 4) is 0.18 to 0.40:1.
8. The method for producing a silica according to any one of claims 1 to 6, wherein: the ageing time in the step 4) is 20-40 min.
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Application publication date: 20221125 Assignee: GUANGZHOU FEIXUE MATERIAL TECHNOLOGY Co.,Ltd. Assignor: Jinsanjiang (Zhaoqing) silicon material Co.,Ltd. Contract record no.: X2023980039858 Denomination of invention: A friction type silica and its preparation method and application Granted publication date: 20230704 License type: Common License Record date: 20230818 |