CN1301904C - Process for preparing silicon dioxide for green high transparent toothpaste - Google Patents

Abstract

The present invention relates to silicon dioxide for green high transparent toothpaste, which is prepared by an acidifying agent and an alkaline silicate solution. In raw materials, food-grade aluminium sulfate and phosphoric acid are adopted as addition agents to obviously enhance the light transmittance of the prepared precipitated silicon dioxide. All through the processes of the preparation, deionized water is adopted to prepare products with few impurities and high purity. The control of technological parameter is strict so as to prepare products with high stability and good flow performance. When the temperature of operating environment is changed, the toothpaste can not harden or soften, thereby satisfying the technological requirement of high-grade transparent toothpaste. The various parameters of the prepared toothpaste are all conform to or superior to the trade standard. The silicon dioxide for green high transparent toothpaste has a significance for satisfying the requirements of domestic high-grade toothpaste preparation and substitutes for imported goods.

Description

Preparation method of silicon dioxide for green high-transparency toothpaste

technical field

The invention belongs to ultrafine silicon dioxide for toothpaste production, in particular to a preparation method for producing green high-transparency silicon dioxide for toothpaste by a precipitation method.

Background technique

In order to adapt to the multi-functional and high value-added development direction of toothpaste products, toothpaste technology is also constantly innovating. Transparent toothpaste is made of a new type of soft abrasive, which has been rapidly popularized throughout the country due to its good performance, and this new type of soft abrasive is silica produced by precipitation. The production of transparent toothpaste requires precipitated silica to have high light transmittance and low refractive index, and the requirements for process and raw materials are very strict. At present, the light transmittance of domestically produced precipitated silica is about 70%, which is far from meeting the market demand for high-grade transparent toothpaste. Most of the precipitated silica used in high-grade transparent toothpaste relies on imports.

The preparation of precipitated silica can be divided into gas phase method and precipitation method. The gas phase method is expensive, and the dosage is small, while the precipitation method is relatively low in cost and has a wide range of applications.

In the prior art, the precipitation method is used to produce silica. Concentrated sulfuric acid and sodium silicate are usually added to the reactor according to the weight ratio for reaction, and the reacted material is cooled and pumped into the filter press for filtration. , washing, and drying, so that the liquid-solid two-phase reaches a certain ratio, and the filter cake is beaten by high pressure, matured, stored in a thick slurry tank, and then dried to obtain silica.

The precipitated silica produced by the above-mentioned method has poor stability and easily hardens the toothpaste; it has low transparency and low purity and is not suitable for the production of high-grade transparent toothpaste.

Toothpaste grade silica is a new type of functional material emerging from traditional inorganic materials in the chemical industry after industrial upgrading and product structure adjustment. Due to the obvious advantages of toothpaste grade silica in the field of daily chemicals such as toothpaste and cosmetics and the irreplaceability of its chemical structure and performance, it has become a hot field of international scientific research and technology development. With the development of my country's fine chemical ultrafine functional materials, the development of toothpaste grade silica with independent intellectual property rights has become one of the key research topics for many researchers.

Through domestic on-line search, there is no patent literature report on the precipitated silica for toothpaste with the same production method as the present invention.

Contents of the invention

The main technical problem to be solved by the present invention is to use additives to further improve the purity of raw materials, so that the produced precipitated silica meets the raw material requirements of highly transparent toothpaste; through the optimization and control of process parameters, highly dispersed, pure, fine Amorphous, stable, green and highly transparent silica for toothpaste.

The present invention prepares the main raw material of silicon dioxide for green high-transparency toothpaste is sodium silicate and sulfuric acid, and its reaction equation is:

The preparation method of silicon dioxide for green high transparency toothpaste of the present invention is as follows:

A. Preparation of acidifying agent: Add aluminum sulfate with a concentration of 1.08ml/g to sulfuric acid with a concentration of 3.0-4.5N, and the volume ratio of concentrated sulfuric acid to aluminum sulfate is 1-4:1.

B. Preparation of alkaline silicate solution: sodium silicate with a concentration of 1.2-2.2N, phosphoric acid with a concentration of 10%, and 0.05-0.1 cubic phosphoric acid added to each cubic sodium silicate.

C. Add 3000-4000L of the above-mentioned alkaline silicate solution into the reaction kettle, stir and raise the temperature to 80-90°C evenly, then add the acidulant, the flow rate of the acidulant is controlled at 2-3m3/h, and the reaction time is 25 ~45min, when the pH value reaches 7.5~9, age for 20min; continue to add acidifier, control the flow rate at 1~1.5m3/h, acidify for 5~8min, when the pH value reaches 4~5, continue to stir for 10min, and then put the slurry Put it into the aging tank, aging for 30 minutes, and then filter, wash, dry and pulverize, the final product is 1000 mesh white powder, namely precipitated silica.

The process water required for the preparation of the above raw materials is deionized water.

Aluminum sulfate and phosphoric acid in the above raw materials belong to food additives.

In the present invention, food-grade aluminum sulfate and phosphoric acid are used as additives in the raw materials, so that the light transmittance of the produced precipitated silica is significantly improved; deionized water is used in the preparation process, and the produced product has less impurities and high purity; process parameters Strict control ensures that the product has high stability and good fluidity. When the ambient temperature changes, the toothpaste produced will not become hard or soft, which can meet the process requirements of high-grade transparent toothpaste.

The green high-transparency silicon dioxide for toothpaste produced according to the invention has the characteristics of controllable structure, low specific surface area, high filling density and the like. All technical performance indicators can meet the technical requirements of high-grade transparent toothpaste, in which the content of silicon dioxide ≥ 96%, heavy metal (calculated as pb) ≤ 20ppm, loss on heating ≤ 8.0%, loss on ignition ≤ 8.0%, pH 6.5～8.5, Refractive index 1.440～1.465N, light transmittance ≥95%, water absorption 17-34ml/20g, particle size: 200 mesh ≥99.5%, 320 mesh ≥98%, total number of bacteria <100cfu/g, The above parameters are in line with or better than industry standards.

The invention adopts a unique process technology to produce non-toxic, harmless and highly transparent precipitated silica for toothpaste, which is of great significance for meeting the production demand of domestic high-grade toothpaste and replacing imported products.

Detailed ways

According to the preparation method of silicon dioxide for green high-transparency toothpaste, the present invention can produce three types of transparent combination type, transparent friction type and transparent thickening type.

Example 1

The preparation method of transparent composite precipitated silica is as follows:

A, prepare acidulant: concentration is that the aluminum sulfate that concentration is 1.08ml/g is added in the sulfuric acid of concentration 3.9～4.2N, the volume ratio of concentrated sulfuric acid and aluminum sulfate is 4:1.

B. Preparation of alkaline silicate solution: sodium silicate with a concentration of 1.65-1.70N, phosphoric acid with a concentration of 10%, and 0.05-0.1 cubic phosphoric acid added to each cubic sodium silicate.

C. Add 3500L of the above-mentioned alkaline silicate solution into the reaction kettle, stir and raise the temperature to 86±1°C evenly, then add the acidulant, the flow rate of the acidulant is controlled at 3m ³ /h, and the reaction time is 30-35min. When the pH value reaches 8-9, age for 20 minutes; continue to add acidifier, control the flow rate at 1.5m ³ /h, acidify for 5-8 minutes, and when the pH value reaches 4-5, continue to stir for 10 minutes, and then put the slurry into the aging tank , matured for 30 minutes, and then filtered, washed, dried and pulverized, the final product is a 1000-mesh white powder, that is, transparent combined precipitated silica.

Example 2

The preparation method of transparent thickened precipitated silica is as follows:

A, prepare acidulant: concentration is that the aluminum sulfate that concentration is 1.08ml/g is added in the sulfuric acid of concentration 3.0～3.2N, and the volume ratio of concentrated sulfuric acid and aluminum sulfate is 1:1.

B. Preparation of alkaline silicate solution: sodium silicate with a concentration of 1.20-1.40N, phosphoric acid with a concentration of 10%, and 0.05-0.1 cubic phosphoric acid added to each cubic sodium silicate.

C. Add 3500L of the above-mentioned alkaline silicate solution into the reaction kettle, stir and raise the temperature to 81±1°C evenly, add the acidulant, the flow rate of the acidulant is controlled at 2m ³ /h, and the reaction time is 40-45min. When the pH value reaches 7.5-7.8, age for 20 minutes; continue to add acidifying agent, the flow rate is controlled at 1m ³ /h, acidify for 6-8 minutes, and when the pH value reaches 4-4.5, continue to stir for 10 minutes, and then put the slurry into the aging tank. Aging for 30 minutes, followed by filtration, washing, drying and crushing, the final product is a 1000-mesh white powder, that is, transparent thickened precipitated silica.

Example 3

The process parameters for preparing transparent friction-type precipitated silica are as follows:

A, preparation of acidifying agent: concentration is the aluminum sulfate that concentration is 1.08ml/g is added in the sulfuric acid of concentration 4.0～4.2N, and the volume ratio of concentrated sulfuric acid and aluminum sulfate is 4:1.

B. Preparation of alkaline silicate solution: sodium silicate with a concentration of 2-2.05N, phosphoric acid with a concentration of 10%, and 0.05-0.1 cubic phosphoric acid added to each cubic sodium silicate.

C. First add 1350-1400L of sodium sulfate solution with a concentration of 4-8% into the reaction kettle, stir and make the temperature rise to 89±1°C uniformly, and adjust the pH value to 9-10 with the above-mentioned alkaline silicate solution. , while adding acidifying agent and alkaline silicate solution. Among them, the flow rate of alkaline silicate solution is 5.5-6.0m ³ /h, the flow rate of acidifying agent is controlled at 3m ² /h, the reaction time is 25-30min, and when the pH value reaches 9.0, it is aged for 20min; continue to add acidifying agent, the flow rate is controlled At 1.5m ² /h, acidify for 5-8 minutes, and when the pH value reaches 4.5-4.7, continue to stir for 10 minutes, then put the slurry into the aging tank, mature for 30 minutes, and then filter, wash, dry and pulverize, and the final product is 1000 Purpose White powder, that is, transparent friction-type precipitated silica.

Deionized water is used for the process water required in the preparation of raw materials in the above examples, and aluminum sulfate and phosphoric acid in the raw materials are food additives.

Claims (5)

1. A preparation method of greenhigh-transparency silica for toothpaste is characterized by comprising the following steps:

A. preparing an acidifier: adding 1.08ml/g aluminum sulfate into 3.0-4.5N sulfuric acid, wherein the volume ratio of concentrated sulfuric acid to aluminum sulfate is 1-4: 1;

B. preparing an alkali silicate solution: sodium silicate with the concentration of 1.2-2.2N and phosphoric acid with the concentration of 10%, wherein 0.05-0.1 cubic of phosphoric acid is added into each cubic of sodium silicate;

C. adding 3000-4000L of the alkali silicate solution into a reaction kettle, stirring, uniformly heating to 80-90 ℃, adding an acidifying agent, and controlling the flow rate of the acidifying agent to be 2-3 m³H, aging for 20min when the reaction time is 25-45 min and the pH value reaches 7.5-9; continuously adding an acidifying agent, and controlling the flow rate to be 1-1.5 m³Acidifying for 5-8 min, continuing stirring for 10min when the pH value reaches 4-5, then pumping the slurry into a curing tank, curing for 30min, filtering, washing, drying and crushing to obtain a final product which is 1000-mesh white powder, namely precipitated silicon dioxide;

the aluminum sulfate and the phosphoric acid in the raw materials belong to food additives.

2. The method for preparing silica for green high transparent toothpaste according to claim 1, characterized in that the method for preparing the transparent combination type precipitated silica is as follows:

A. preparing an acidifier: adding 1.08ml/g aluminum sulfate into 3.9-4.2N sulfuric acid, wherein the volume ratio of concentrated sulfuric acid to aluminum sulfate is 4: 1;

B. preparing an alkali silicate solution: sodium silicate with the concentration of 1.65-1.70N and phosphoric acid with the concentration of 10%, wherein 0.05-0.1 cubic of phosphoric acid is added into each cubic of sodium silicate;

C. adding 3500L of the above alkaline silicate solution into a reaction kettle, stirring, uniformly heating to 86 + -1 deg.C, adding acidifying agent, and controlling the flow rate of acidifying agent at 3m³H, aging for 20min when the reaction time is 30-35 min and the pH value reaches 8-9; the acidifying agent was continuously added, and the flow rate was controlled at 1.5m³Acidifying for 5-8 min, continuing stirring for 10min when the pH value reaches 4-5, then pumping the slurry into a curing tank,aging for 30min, filtering, washing, and dryingDrying and crushing to obtain white powder of 1000 meshes, namely transparent combined precipitated silica;

the aluminum sulfate and the phosphoric acid in the raw materials belong to food additives.

3. The method for preparing silica for green high transparent toothpaste according to claim 1, characterized in that the transparent thickening type precipitated silica is prepared as follows:

A. preparing an acidifier: adding 1.08ml/g aluminum sulfate into 3.0-3.2N sulfuric acid, wherein the volume ratio of concentrated sulfuric acid to aluminum sulfate is 1: 1;

B. preparing an alkali silicate solution: sodium silicate with the concentration of 1.20-1.40N and phosphoric acid with the concentration of 10%, wherein 0.05-0.1 cubic of phosphoric acid is added into each cubic of sodium silicate;

C. adding 3500L of the above alkaline silicate solution into a reaction kettle, stirring, uniformly heating to 81 + -1 deg.C, adding acidifying agent, and controlling the flow rate of acidifying agent at 2m³H, aging for 20min when the reaction time is 40-45 min and the pH value reaches 7.5-7.8; adding acidifying agent continuously, and controlling the flow rate at 1m³Acidifying for 6-8 min, continuing stirring for 10min when the pH value reaches 4-4.5, then pumping the slurry into a curing tank, curing for 30min, filtering, washing, drying and crushing to obtain a final product which is 1000-mesh white powder, namely transparent thickening precipitated silica;

the aluminum sulfate and the phosphoric acid in the raw materials belong to food additives.

4. The method for preparing silica for green high transparent toothpaste according to claim 1, wherein the process parameters for preparing transparent abrasive type precipitated silica are as follows:

A. preparing an acidifier: adding 1.08ml/g aluminum sulfate into 4.0-4.2N sulfuric acid, wherein the volume ratio of concentrated sulfuric acid to aluminum sulfate is 4: 1;

B. preparing an alkali silicate solution: sodium silicate with the concentration of 2-2.05N and phosphoric acid with the concentration of 10%, wherein 0.05-0.1 cubic of phosphoric acid is added into each cubic of sodium silicate;

C. firstly, 1350-1400L of sodium sulfate solution with the concentration of 4-8% is added into a reaction kettle, the mixture is stirred, the temperature of the mixture is uniformly raised to 89 +/-1 ℃, the pH value of the mixture is adjusted to 9-10 by using the alkaline silicate solution, and meanwhile, an acidifying agent and the alkaline silicate solution are added; wherein the flow rate of the alkali silicate solution is 5.5-6.0 m³H, the flow rate of the acidifying agent is controlled at 3m³H, aging for 20min when the reaction time is 25-30 min and the pH value reaches 9.0; the acidifying agent was continuously added, and the flow rate was controlled at 1.5m³Acidifying for 5-8 min, continuing stirring for 10min when the pH value reaches 4.5-4.7, then pumping the slurry into a curing tank, curing for 30min, filtering, washing, drying and crushing to obtain a final product which is 1000-mesh white powder, namely transparent friction type precipitated silica;

the aluminum sulfate and the phosphoric acid in the raw materials belong to food additives.

5. The method for preparing the silica for the green high-transparency toothpaste as claimed in claim 1, wherein the process water required for preparing the raw materials is deionized water.