CN113321220A - Preparation method of precipitated silica with loose structure - Google Patents

Preparation method of precipitated silica with loose structure Download PDF

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Publication number
CN113321220A
CN113321220A CN202110758501.6A CN202110758501A CN113321220A CN 113321220 A CN113321220 A CN 113321220A CN 202110758501 A CN202110758501 A CN 202110758501A CN 113321220 A CN113321220 A CN 113321220A
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base solution
value
silicate
precipitated silica
concentration
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王永庆
马加佳
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Quechen Silicon Chemical Co Ltd
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Quechen Silicon Chemical Co Ltd
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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
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C08K7/22—Expanded, porous or hollow particles
    • C08K7/24—Expanded, porous or hollow particles inorganic
    • C08K7/26—Silicon- containing compounds
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
    • A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
    • A61K2800/41—Particular ingredients further characterized by their size
    • A61K2800/412—Microsized, i.e. having sizes between 0.1 and 100 microns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2220/00—Aspects relating to sorbent materials
    • B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
    • B01J2220/48—Sorbents characterised by the starting material used for their preparation
    • B01J2220/4806—Sorbents characterised by the starting material used for their preparation the starting material being of inorganic character
    • 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
    • C01P2006/17—Pore diameter distribution

Abstract

The invention discloses a preparation method of precipitated silica with a loose structure. The preparation method comprises the following steps: (1) mixing and dissolving silicate and electrolyte to obtain a base solution, wherein the electrolyte concentration in the base solution is 10-25 wt%; (2) adding an acidifier into the base solution, and then raising the temperature of the base solution to 4-16 ℃ until the pH value is 7-9; (3) adding silicate into the base solution, and adding an acidifying agent to keep the pH value basically unchanged; (4) and after the silicate is added, continuously adding an acidifier until the pH value is 4.5-6, and aging. Compared with the prior art, the method has the advantages of various and easily-obtained raw materials, simple and feasible process, loose structure, high ultrasonic depolymerization speed, high dispersibility and uniform pore distribution of the prepared precipitated silica, and has wide application fields.

Description

Preparation method of precipitated silica with loose structure
Technical Field
The invention relates to a preparation method of precipitated silica with a loose structure.
Background
Precipitated Silica (SiO)2·nH2O), a common inorganic non-metallic material, is commonly used as a filler for reinforcing polymers, as are inorganic materials such as carbon black, clay, china clay, calcium carbonate, and the like. Compared with carbon black, the silicon dioxide is more environment-friendly and has higher plasticity because the surface is rich in hydroxyl. Compared with clay, pottery clay and other inorganic fillers with rich functional groups on the surface, the precipitated silica is cheap and easily available, and has good application effect. Silica is an important chemical product and is widely applied to the fields of rubber, plastics, coatings, cosmetics, medicines, pesticides, feeds and foods.
The silicon source of precipitated silica is initially based on silica sand, from which silicates are prepared, and in the liquid phase, by hydrolysis of silicates by an acidifying agent, a process for the preparation of precipitated silica in general. The selection of silicate and the selection of acidifying agent can change the yield and specific surface area of the final product, but the size and distribution of pores and the dispersibility in the size are difficult to change through the selection and adjustment of raw materials. However, improving the internal aggregate structure of precipitated silica, adjusting the pore distribution, and the ability of the silica itself to depolymerize, would facilitate its dispersion during use, e.g., rubber, plastic, etc.
Disclosure of Invention
The invention aims to provide a method for preparing precipitated silica with a loose structure, and the precipitated silica prepared by the method is easy to depolymerize and disperse in a polymer.
A process for the preparation of a precipitated silica having a loose structure, said process comprising the steps of:
(1) mixing and dissolving silicate and electrolyte to obtain a base solution, wherein the electrolyte concentration in the base solution is 10-25 wt%;
(2) adding an acidifier into the base solution, and then raising the temperature of the base solution to 4-16 ℃ until the pH value is 7-9;
(3) adding silicate into the base solution, and adding an acidifying agent to keep the pH value basically unchanged;
(4) and after the silicate is added, continuously adding an acidifier until the pH value is 4.5-6, and aging.
In the present invention, the choice of acidifying agent, silicate and electrolyte is made in a manner known per se.
As the acidifying agent, a strong inorganic acid such as sulfuric acid, nitric acid or hydrochloric acid, or an organic acid such as acetic acid, formic acid or the like is generally used.
The acidifying agent can be diluted or used at high concentrations, in particular when the acidifying agent is sulfuric acid, the concentration can be between 6% and 10%, or between 95% and 99%.
As silicates, it is possible to use the customary forms of silicates, such as orthosilicates, disilicates, and also organometallic salts, in particular sodium or potassium silicates.
The silicate may be diluted or concentrated, and in particular, when the silicate is sodium silicate, the concentration may be 10% to 40% (as SiO)2Meter)
The electrolyte may be sodium chloride, sodium sulfate, potassium chloride or potassium sulfate, and preferably sodium sulfate.
As the acidifying agent, sulfuric acid is generally used, as the silicate, sodium silicate is generally used, and as the electrolyte, sodium sulfate is generally used.
Preferably, in the step (1), the temperature of the base solution is 70-90 ℃.
Preferably, in the step (1), the electrolyte concentration in the base solution is 15 to 20 wt%.
Preferably, in step (1), the silicate concentration in the base solution is SiO2The weight is 70-80 g/L; preferably 72-78 g/L.
Preferably, in the step (2), the acidifying agent is added within 50-60 min; more preferably, the adding is finished within 52-58 min, and the adding process is kept at a constant speed.
Preferably, in the step (2), the temperature of the base solution is increased by 7-12 ℃ until the pH value is 7.5-8.5, and then the step (3) is carried out under the condition of heat preservation.
More preferably, in the step (2), the temperature of the base solution is increased after the acidifying agent is added for 25-30 min. The temperature rising speed is not too fast, preferably, the temperature rising speed is controlled to be 0.5-3 ℃/min, and more preferably, the temperature rising speed is controlled to be 1-2 ℃/min.
Preferably, in the step (3), an acidifying agent is added to control the fluctuation range of the pH value within +/-0.2; more preferably, the fluctuation range of the pH value is controlled within. + -. 0.1. In general, silica is produced in large quantities during the process, the reaction system gradually forms a suspension (slurry) of silica, during which sufficient stirring should be maintained, and preferably, according to the invention, the solids content of the silica suspension is generally below 30% and above 15%.
Preferably, in the step (4), the acidifying agent is added continuously until the pH value is 4.8-5.2, and then the temperature and the pH value of the reaction system are maintained to be basically unchanged, and the aging is carried out for 3-30 min, and more preferably, the aging is carried out for 10-15 min.
After the aging is finished, washing and filtering the slurry, crushing (pulping) a filter cake in the presence of sodium aluminate, adjusting the pH value to 6-7, and then carrying out spray drying; preferably, the pH value is adjusted to 6.2-6.8.
The addition of sodium aluminate can reduce the viscosity of the filter cake and is beneficial to improving the atomization efficiency. The amount of the sodium aluminate is 1-3 wt% of the amount of the filter cake.
Using a common filtering method, and obtaining a filter cake with proper content by plate-and-frame filter pressing or rotary filtering.
Spray drying may employ a nozzle atomizer or a turbine atomizer.
Drying the mixture by using a turbine atomizer to obtain powder or microbeads with the average particle size of 5-100 mu m.
And drying by adopting a nozzle atomizer to obtain the microbeads with the average particle size of 100-350 microns.
In the present invention, the BET specific surface area is determined according to the method of b.e.t. (multipoint method), reference standard ISO 9277. CTAB specific surface area (external specific surface area) was determined according to the method described in ISO 5794-1. The D50 median particle size was measured by a laser particle sizer (Malvern Mastersizer 3000).
In particular, the depolymerization ability was tested by characterizing the D50 and R18 (content greater than 18 μm) of the product after disruption in a sonicator. The ultrasonicator is a 600 watt ultrasonicator, and is used at a standard power of 80%, and the ultrasonication time is usually 5.5 min.
Particularly, when the pore distribution of the product is analyzed, the mercury feeding condition under 0-400 mpa is measured by the principle of mercury penetration (thermoelectric mercury permeameter), and 0-200 mpa is preferred. Calculating modal aperture size P0And the function value of the hole distribution area corresponding to the modal aperture (mode pore size at dv/dlog (D): H0The calculation is located at H0/2, corresponding aperture P1And P2Calculating the aperture distribution width (W ═ P/P)1-P2︱/P0
After the precipitated silica prepared by the method is subjected to ultrasonic crushing, the average particle size of D50 is 2-8 mu m.
Precipitated silica prepared by the invention, the modal pore diameter P0At 20 nm-40 nm, the total pore volume S is 1.5cm3/g～2.5cm3The pore distribution width is 0.3-0.5.
The precipitated silica prepared by the method has the BET specific surface area of 80-400 m2A concentration of 100 to 300m is preferred2/g。
The precipitated silica prepared by the method has a CTAB external specific surface area of 70-320 m2Per g, preferably 100 to 250m2/g。
The BET/CTAB of the precipitated silica prepared by the invention is 1.0-1.2.
The DBP oil absorption value of the precipitated silica prepared by the method is 2.0-3.0 ml/g.
The precipitated silica prepared according to the method of the present invention has excellent effects in reinforcing both natural polymers and synthetic polymers.
Typically the natural polymer is Natural Rubber (NR).
Among the synthetic polymers, diene elastomers, for example polybutadiene (BR), polyisoprene (IR), in particular butadiene-styrene copolymers (styrene-butadiene rubber ESBR or SSBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR), isoprene-butadiene-styrene copolymers (SBIR).
Among the synthetic polymers, the precipitated silicas prepared according to the invention are also suitable, in particular, for Silicone Rubbers (SR), high-temperature vulcanizates (HTV), room-temperature vulcanizates (RTV).
The precipitated silica prepared by the method has a good reinforcing effect on engineering parts, particularly nitrile rubber or thermoplastic polyurethane elastomer for rubber rollers and rubber rings.
The precipitated silicas prepared according to the process of the invention can also be used as adsorbents for active materials (for example in the food industry, such as vitamin E), as tackifiers or as anticaking agents, additives for toothpastes, additives for papers.
The invention has the advantages that: (1) the prepared precipitated silica has a loose structure, high dispersibility and uniform pore size distribution. (2) The production process is simple, and the effect of applying the reinforcing polymer is good, and the range is wide.
Drawings
FIG. 1 is a schematic diagram of pore size distribution and its distribution width.
Detailed Description
The following description of the embodiments of the present invention is merely exemplary in nature and is in no way intended to limit the scope of the invention.
Example 1
Base solution preparation stage
The following were introduced into a reactor equipped with a propeller stirrer and a steam heating device:
6500g of water glass solution (specific gravity 1.144, concentration 16.6% by weight, in terms of SiO)2Calculated as SiO), 5400g of sodium sulfate solution (35% strength by weight), a small amount of water, sodium silicate (in SiO) in the base solution2Meter) was 76 g/l.
The base material was stirred to achieve a homogeneous distribution of the material and heated to 78 ℃ by steam.
Acidification stage
Adding a sulfuric acid solution (with the specific gravity of 1.05 and the concentration of 7.7 wt%) into a reactor at a rate of 97g/min, keeping stirring and heat preservation after about 55min, starting heating at a rate of 1 ℃/min after acidification reaches 30min, heating to 85 ℃, keeping stirring and heat preservation until acidification reaches a pH value of 8 of a reaction system, and ending acidification.
Stage of increasing silica concentration (simultaneous feed stage)
A water glass solution (specific gravity 1.144, concentration 16.6 wt%) was fed at 52g/min and a sulfuric acid solution (specific gravity 1.05, concentration 7.7 wt%) was fed at 39g/min to the reactor, and the feeding rate of sulfuric acid was adjusted to maintain the pH of the reaction system at 8. + -. 0.1. After 30min, the simultaneous feeding was completed, and the whole feeding process was kept under stirring and kept at 85 ℃.
Post-acidification stage
The sulfuric acid solution (specific gravity 1.05, concentration 7.7% by weight) was fed into the reactor at a rate adjusted to adjust the pH of the reaction medium to 5.1 within 15 min.
Stage of thermal ageing
And stopping feeding the reactor, maintaining stirring and preserving heat for 5-10 min.
Post-treatment stage
The reaction slurry was discharged, filter-pressed with a plate and frame filter and washed 4 times with soft water to give a filter cake with a solids content of about 19%. The filter cake was then mechanically crushed in the presence of a small amount of water and 2 wt% of sodium aluminate and the pH was adjusted to 6.5 to give a silica slurry having a solids content of about 18%.
Drying with spray drying tower to obtain silica product 1 #.
Example 2
Base solution preparation stage
The following were introduced into a reactor equipped with a propeller stirrer and a steam heating device:
6500g of water glass solution (specific gravity 1.144, concentration 16.6 wt%), 5400g of sodium sulfate solution (concentration 35 wt%), a small amount of water, sodium silicate (as SiO) in the base solution2Meter) was 76 g/l.
The base material was stirred to achieve a homogeneous distribution of the material and heated to 78 ℃ by steam.
Acidification stage
Adding a sulfuric acid solution (with the specific gravity of 1.05 and the concentration of 7.7 wt%) into a reactor at the rate of 97g/min, keeping stirring and heat preservation after about 55min, starting heating after acidification reaches 30min, heating to 90 ℃ after 7min, keeping stirring and heat preservation until the acidification is carried out until the pH value of a reaction system is 8, and ending acidification.
Stage of increasing silica concentration (simultaneous feed stage)
A water glass solution (specific gravity 1.144, concentration 16.6 wt%) was fed at 52g/min and a sulfuric acid solution (specific gravity 1.05, concentration 7.7 wt%) was fed at 39g/min to the reactor, and the feeding rate of sulfuric acid was adjusted to maintain the pH of the reaction system at 8. + -. 0.1. After 30min, feeding is completed simultaneously, and stirring and heat preservation are maintained at 90 ℃ in the whole feeding process.
Post-acidification stage
The sulfuric acid solution (specific gravity 1.05, concentration 7.7% by weight) was fed into the reactor at a rate adjusted to adjust the reaction medium pH to 4.9 within 15 min.
Stage of thermal ageing
And stopping feeding the reactor, maintaining stirring and keeping the temperature for 5-10 min.
Post-treatment stage
The reaction slurry was discharged, filter-pressed with a plate and frame filter and washed 4 times with soft water to give a filter cake with a solids content of about 19%. The filter cake was then mechanically crushed in the presence of a small amount of water and 2% by weight of sodium aluminate and the pH was adjusted to 6.5 to give a silica slurry having a solids content of about 18%.
Drying with spray drying tower to obtain silica product No. 2.
Example 3
Base solution preparation stage
The following were introduced into a reactor equipped with a propeller stirrer and a steam heating device:
6500g of water glass solution (specific gravity 1.144, concentration 16.6 wt%), 5400g of sodium sulfate solution (concentration 35 wt%), a small amount of water, sodium silicate (as SiO) in the base solution2Meter) was 72 g/l.
The base material was stirred to achieve a homogeneous distribution of the material and heated to 78 ℃ by steam.
Acidification stage
Adding a sulfuric acid solution (with the specific gravity of 1.05 and the concentration of 7.7 wt%) into a reactor at the rate of 97g/min, keeping stirring and heat preservation after about 55min, starting heating after acidification reaches 30min, heating to 82 ℃ after 7min, keeping stirring and heat preservation until the acidification is carried out until the pH value of a reaction system is 8, and ending acidification.
Stage of increasing silica concentration (simultaneous feed stage)
A water glass solution (specific gravity 1.144, concentration 16.6 wt%) was fed at 52g/min and a sulfuric acid solution (specific gravity 1.05, concentration 7.7 wt%) was fed at 39g/min to the reactor, and the feeding rate of sulfuric acid was adjusted to maintain the pH of the reaction system at 8. + -. 0.1. After 30min, the simultaneous feeding was completed, and the whole feeding process was kept under stirring and kept at 82 ℃.
Post-acidification stage
The sulfuric acid solution (specific gravity 1.05, concentration 7.7% by weight) was fed into the reactor at a rate adjusted to adjust the reaction medium pH to 4.5 within 15 min.
Stage of thermal ageing
The reactor was stopped from feeding, maintained under stirring and maintained at temperature for 20 min.
Post-treatment stage
The reaction slurry was discharged, filter-pressed with a plate and frame filter and washed 4 times with soft water to give a filter cake with a solids content of about 19%. The filter cake was then mechanically crushed in the presence of a small amount of water and 2% by weight of sodium aluminate and the pH was adjusted to 6.5 to give a silica slurry having a solids content of about 18%.
Drying with spray drying tower to obtain silica product No. 3.
Example 4
Base solution preparation stage
The following were introduced into a reactor equipped with a propeller stirrer and a steam heating device:
6500g of water glass solution (specific gravity 1.144, concentration 16.6 wt%), 5400g of sodium sulfate solution (concentration 35 wt%), a small amount of water, sodium silicate (as SiO) in the base solution2Meter) was 96 g/l.
The base material was stirred to achieve a homogeneous distribution of the material and heated to 78 ℃ by steam.
Acidification stage
Adding a sulfuric acid solution (with the specific gravity of 1.05 and the concentration of 7.7 wt%) into a reactor at the rate of 97g/min, keeping stirring and heat preservation after about 55min, starting heating after acidification reaches 30min, heating to 94 ℃ after 7min, keeping stirring and heat preservation until the acidification is carried out until the pH value of a reaction system is 8, and ending acidification.
Stage of increasing silica concentration (simultaneous feed stage)
A water glass solution (specific gravity 1.144, concentration 16.6 wt%) was fed at 52g/min and a sulfuric acid solution (specific gravity 1.05, concentration 7.7 wt%) was fed at 39g/min to the reactor, and the feeding rate of sulfuric acid was adjusted to maintain the pH of the reaction system at 8. + -. 0.1. After 30min, the simultaneous feeding was completed, and the whole feeding process was kept under stirring and heat-insulated at 94 ℃.
Post-acidification stage
The sulfuric acid solution (specific gravity 1.05, concentration 7.7% by weight) was fed into the reactor at a rate adjusted to adjust the pH of the reaction medium to 5.1 within 15 min.
Stage of thermal ageing
The reactor was stopped from feeding, maintained under stirring and held at temperature for 10 min.
Post-treatment stage
The reaction slurry was discharged, filter-pressed with a plate and frame filter and washed 4 times with soft water to give a filter cake with a solids content of about 19%. The filter cake was then mechanically crushed in the presence of a small amount of water and 2% by weight of sodium aluminate and the pH was adjusted to 6.5 to give a silica slurry having a solids content of about 18%.
Drying with spray drying tower to obtain silica product No. 4.
TABLE 1 Final Properties of silicas from examples 1 to 4
BET(m2/g) CTAB(m2/g) pH D50(μm) R18(％) W
1# 175 155 6.5 3.74 2.66 0.35
2# 115 105 6.5 4.55 3.62 0.37
3# 210 195 6.5 3.56 2.55 0.32
4# 95 80 6.5 4.95 4.00 0.41
Example 5
Ultrasonic depolymerization rate comparison
Generally, the white carbon black is subjected to a crushing process in the use process, the structure of microbeads or briquettes of the white carbon black is crushed, and the distribution condition of the particle size after crushing determines the dispersibility of the white carbon black to a certain extent.
The dispersibility of the white carbon black is represented by comparing the particle size distribution of the white carbon black with the same specific surface area after ultrasonic depolymerization.
The ultrasonication method used in this example involved:
step 1: passing the white carbon black sample through a 50-mesh screen, and taking the rest white carbon black fine powder
Step 2, taking 1.4g of fine powder in a 100ml beaker, mixing and shaking the fine powder and 60ml of deionized water
Step 3, in an ice-water bath, carrying out ultrasonic crushing for 3min, 5.5min and 10min by using an ultrasonic crusher (QSonica) with 80% power
And 4, analyzing the particle size distribution of the ultrasonically crushed white carbon black by using a particle size analyzer (Malvern 3000).
The control sample # 1 was used for comparison, and the control commercial ULTRASIL-VN3GR (Evonik Corp.) had the following properties:
BET specific surface area: 175m2/g
CTAB specific surface area: 155m2/g
TABLE 2 depolymerization Properties of silica
D(50)(μm) D(50) D(50) R18(％)
Time of ultrasound 3min 5.5min 10min 10min
1# 15.2 3.74 3.54 1.5
Reference sample 20.3 6.94 6.51 3.9
It can be seen that the silica has higher depolymerization speed, smaller depolymerized particles and fewer large particles under the condition of the same specific surface area, and is favorable for improving the dispersibility of the white carbon black in the due process.
Therefore, according to the present invention, it is possible to obtain silica having a loose structure, a uniform pore size distribution, and a high dispersibility, and particularly, having an excellent depolymerization rate, so that it has an advantage of a high dispersibility in various application fields.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A method for preparing precipitated silica having a loose structure, said method comprising the steps of:
(1) mixing and dissolving silicate and electrolyte to obtain a base solution, wherein the electrolyte concentration in the base solution is 10-25 wt%;
(2) adding an acidifier into the base solution, and then raising the temperature of the base solution to 4-16 ℃ until the pH value is 7-9;
(3) adding silicate into the base solution, and adding an acidifying agent to keep the pH value basically unchanged;
(4) and after the silicate is added, continuously adding an acidifier until the pH value is 4.5-6, and aging.
2. The method of claim 1, wherein: in the step (1), the temperature of the base solution is 70-90 ℃.
3. The method of claim 1, wherein: in the step (1), the electrolyte concentration in the base solution is 15-20 wt%.
4. The method of claim 1, wherein: in the step (1), the silicate concentration in the base solution is SiO2The weight is 70-80 g/L; preferably 72-78 g/L.
5. The method of claim 1, wherein: in the step (2), the acidifying agent is added within 50-60 min; preferably, the addition is completed within 52-58 min.
6. The method of claim 1, wherein: in the step (2), the temperature of the base solution is raised to 7-12 ℃ until the pH value is 7.5-8.5.
7. The production method according to claim 1 or 6, characterized in that: in the step (2), adding an acidifying agent for 25-30 min, and then raising the temperature of the base solution.
8. The method of claim 1, wherein: in the step (3), adding an acidifying agent to ensure that the fluctuation range of the pH value is within +/-0.2; preferably, the fluctuation range of the pH value is within. + -. 0.1.
9. The method of claim 1, wherein: in the step (4), adding an acidifying agent continuously until the pH value is 4.8-5.2, and aging for 3-30 min;
preferably, after the aging is finished, washing and filtering the slurry, crushing a filter cake in the presence of sodium aluminate, adjusting the pH value to 6-7, and then carrying out spray drying.
10. Precipitated silica prepared according to the process of one of claims 1 to 9.
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Cited By (1)

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Publication number Priority date Publication date Assignee Title
CN114735713A (en) * 2022-03-02 2022-07-12 福建省三明同晟化工有限公司 Preparation process of synthetic silicon dioxide for papermaking additive

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Publication number Priority date Publication date Assignee Title
CN1100001C (en) * 1997-05-26 2003-01-29 罗狄亚化学公司 Precipitated silica used as reinforcing filler for elastomers
CN1669922A (en) * 2005-02-22 2005-09-21 山东海化集团有限公司 Preparation method of precipitated silicon dioxide

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CN1100001C (en) * 1997-05-26 2003-01-29 罗狄亚化学公司 Precipitated silica used as reinforcing filler for elastomers
CN1669922A (en) * 2005-02-22 2005-09-21 山东海化集团有限公司 Preparation method of precipitated silicon dioxide

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114735713A (en) * 2022-03-02 2022-07-12 福建省三明同晟化工有限公司 Preparation process of synthetic silicon dioxide for papermaking additive
CN114735713B (en) * 2022-03-02 2024-03-29 福建同晟新材料科技股份公司 Preparation process of synthetic silicon dioxide for papermaking additive

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