The relationship between powder and medicine

What should you do if you have a cold, fever, or diarrhea?

Of course you have to take medicine!

People's healthy life is inseparable from medicine. Common types of medicine include pills, granules, etc. They are all made from raw materials after making powder!

Let’s take a look at the inseparable relationship between medicine and powder...

Raw material-powder-medicine

In pharmaceutical products, solid pharmaceutical preparations account for about 70% to 80%. The dosage forms containing solid drugs include powders, granules, capsules, tablets, powder injections, and suspensions.

The preparation process of pharmaceutical solid dosage forms is as follows:

What are the pharmaceutical powder equipment

Solid dosage form preparation

Crushing: ball mill, impact mill, vibration mill, jet mill, etc.

Screening: rotary vibrating screen, sample sieve, cyclone separator, etc.

Mixing: trough mixer, cone mixer, three-dimensional motion mixer, V-type mixer, etc.

Granulation: fluidized granulator, stirring granulator, centrifugal granulator, extrusion granulator, etc.

Tableting: single-punch tablet machine, rotary multi-punch tablet machine, high-speed tablet press, etc.

Drying: spray desiccant, granulating desiccant, hollow paddle dryer, fluidized bed dryer, etc.

Detection: laser particle size analyzer, density meter, surface area and pore size distribution meter, powder rheometer, etc.

Most solid dosage forms need to be processed according to different requirements to improve the properties of the powder and meet the requirements of product quality and powder operation.

The powder processing process is different, the powder properties of the particles are also very different!

• Fluidized granulation

It is suitable for tableting, with low particle density, high porosity and low strength.

• Stirring granulation

It is suitable for encapsulating, with compact particles and high strength.

• Centrifugal granulation

It is suitable for encapsulating and coating, the particles are round, dense and uniform.

What are the effects of powder properties on the process and quality of pharmaceutical preparations

The nature of the powder

The first property is the property of a single particle, such as shape, size, surface area, porosity, etc. The second property is the properties of the powder aggregate, such as fluidity, filling property, compression molding property, etc.

Solid pharmaceutical products are often mixed with multiple ingredients. In order to ensure the uniformity of the drug content in the formulation, each ingredient needs to be crushed and sieved to form a powder with a certain particle size before mixing.

• Influence of powder properties on mixing uniformity

From the perspective of powder, the factors that affect the uniformity of mixing include particle size, particle size difference and density difference between components, particle morphology and surface state, static electricity and surface energy.

• Influence of powder properties on divided doses of solid preparations

The fluidity of powder is related to particle size, particle size distribution, particle morphology, surface state, and bulk density. When the angle of repose α<30°, the fluidity is good, and when α>45°, the fluidity is poor. In actual production, α<40° can meet the production requirements of divided doses.

The size, shape, particle size distribution, bulk density and porosity of the powder particles can intuitively reflect its filling properties.

• Influence of powder properties on compression formability

The radial crushing force of the powder—hardness, and the crushing force per unit area—tensile strength are measured, and the ability of the powder to reduce volume under pressure and form a certain shape tightly combined is obtained.

• The effect of powder properties on the quality of preparations

The process of solid pharmaceutical preparations is to disintegrate, release the drug and be absorbed by the human body; increase the porosity to promote disintegration, reduce the particle size to increase the dissolution, and reduce the particle size to enhance the efficacy.

• Influence of powder properties on bioavailability and curative effect

The smaller the particle size, the greater the bioavailability; the larger the specific surface area, the greater the bioavailability; the smaller the particle size, the greater the bioavailability.

What are the applications of powder technology in pharmaceutical preparations?

• Application in prescription design

Ensure the quality of pharmaceutical preparations: dissolution, disintegration, stability, appearance, uniformity of active substances, strength, etc.

To ensure the smooth progress of the production process: fluidity, filling, compression molding, sticking, pushing, etc.

• Application in solid preparation production process

Control parameters: particle size, particle size distribution, fluidity, filling, moisture content, upper and lower punching pressure, residual pressure on the mold wall, etc., and finally a qualified product.

• Convenient to control the quality of solid preparations, which is conducive to the implementation of GMP

Promote automated, continuous, and modern production to prevent drug contamination, cross-contamination and confusion.

• Promote the development of modern technology and new dosage forms

The advantages of ultra-fine pulverization technology in the production and application of Chinese medicine include: cell wall breakage, improving the dissolution rate of active ingredients; improving the utilization of medicinal materials, effectively protecting Chinese medicinal resources; promoting drug absorption and enhancing efficacy; safe and hygienic, and convenient for clinical application.

The advantages of nanotechnology in pharmaceutical applications include: enabling drugs to act on the central nervous system through the blood-brain barrier, penetrating the epidermis to enhance the absorption of the preparation, and enhancing the targeting effect of the drug.

The powder + medicine complement each other, and the prospects are promising!

Powder and medicine are closely related. With the promotion and implementation of GMP standardization in the pharmaceutical industry, powder technology has received more and more attention from people in the pharmaceutical industry, providing new development paths for the research of higher-efficiency drugs; at the same time, the pharmaceutical industry continues to Development also puts forward higher requirements on powder technology and equipment. The two industries complement each other for mutual benefit and win-win!

[Knowledge Popularization] Do you know what mineral drugs are available?

by ALPA Powder

Carbon black modification & its application in rubber

Carbon black is a loose, light, extremely fine, black powdery amorphous carbon. It is the most important reinforcing filler in the rubber industry and is widely used in printing and dyeing, rubber, plastic processing, and transportation industries. Studies have shown that chemical modification of carbon black can greatly improve various properties of carbon black, which is also a hot topic in the current research on carbon black.

In order to meet the special requirements for the performance of carbon black in some applications, the purpose of modification can be achieved by post-processing the carbon black. Starting from the element composition and surface functional groups of carbon black, there are three ways to enhance the hydrophilic modification of carbon black: oxidation modification, graft modification, and coating modification.

Graft modification

Graft modification is one of the most widely studied methods of rubber modification. Graft modification is to graft polymer chains or low-molecular compounds on the surface of carbon black and bond them firmly to the surface of carbon black to prevent aggregation between particles to achieve the purpose of dispersion.

1.  Grafting of carbon black and low molecular weight

AO-80 (an organic antioxidant) decomposes under high temperature conditions to generate small molecular free radicals. In supercritical CO₂ fluid, small organic molecules (AO-80) are used to graft carbon black on the surface to prepare small organic molecules Grafted nano carbon black particles. The analysis of the particle size map after grafting AO-80 molecules onto the surface of carbon black draws the conclusion that the particle size of the modified carbon black aggregates is smaller and narrower.

2.  Grafting of activated carbon black and polymer

Utilizing the characteristics of a large number of end groups of hyperbranched polymers, and modifying carbon black with light end hyperbranched polymers can weaken the aggregation of modified carbon black particles. Hyperbranched polymer graft modified carbon black: the carbon black is first methylated, and then AB₃ type hyperbranched poly(amide ethyl) is grafted onto the surface of the carbon black.

3. Grafting to capture free radicals on the surface of carbon black

Sodium polystyrene sulfonate (PSS) is a water-soluble polymer with good interfacial activity. In an ultrasonic environment, the monomer sodium styrene sulfonate undergoes free radical polymerization, and the generated polymer long-chain free radicals are captured by the surface of the carbon black to prepare polymer grafted carbon black.

Oxidation modification

Carbon black particles are oxidized by an oxidant to undergo modification. The oxidation treatment of carbon black can change the specific surface area, porosity and conductivity of carbon black.

Surface oxidation treatment (gas phase oxidation and liquid phase oxidation) increases the type and number of oxygen-containing functional groups on the surface of carbon black, which can increase the volatile content of carbon black, reduce pH, and improve surface activity and polarity.

1. Gas phase method

Gas-phase modification of carbon black is a traditional modification method. Oxygen, ozone, dry air, and atomic oxygen or humid air are the main oxidants. The inert gas is introduced under closed conditions, and then the temperature is raised to the reaction temperature, and then the oxidant is introduced to carry out the modification reaction. After the reaction, inert gas is introduced. The experimental results show that as the test time increases and the reaction temperature increases, the more oxygen-containing groups on the carbon black surface, the better the dispersibility in the rubber matrix.

2. Liquid phase method

Liquid phase method, also known as chemical oxidation method, is a modification method in which an oxidant reacts with carbon black to generate a few radicals, carboxyl radicals and light radicals on the surface of the carbon black. The Cabot Elastomer Composite (CEC) researched by Wang Mengjiao and others is the first NR filler masterbatch produced by a continuous liquid phase mixing process. This technology makes it possible for environmental protection, low energy consumption, simple process, and low labor consumption. Compared with dry rubber compounding, this material can significantly improve the properties of vulcanized rubber, including reducing hysteresis loss, improving cutting resistance and flexing resistance, and increasing the wear resistance of vulcanized rubber when the amount of filler is increased.

Coating modification

Mix carbon black with water-dispersed white carbon black to make a slurry, add a proper amount of methanol, methyl triethoxy silane, sodium silicate and other dispersants to make the white carbon black coat the surface of the carbon black, and the resulting modified carbon black is filled In tires, conveyor belts and rubber rollers, it can give vulcanized rubber excellent physical properties such as high wear resistance, high grip and low rolling resistance.

Application of modified carbon black in rubber

In the rubber industry, carbon black is widely used as a reinforcing agent, and 90% of global carbon black production is used in the rubber industry.

• Application in NR (Natural Rubber)

The carbon black modified by the pyrolysis gas is used as a reinforcing agent and added to the rubber with HAF. As the amount of modified carbon black increases, the 300% tensile stress of the vulcanized compound increases, the elongation decreases, and the compression set decreases. The tear strength has been reduced.

The effect of pyrolysis gas modification-I and HAF on the performance of NR

• Application in EPDM (ethylene propylene diene monomer rubber)

EPDM rubber (EPDM) has excellent ozone resistance and aging resistance. It is often filled with carbon black modified by glycidyl methacrylate (GMA) monomer grafting to improve its processing and mechanical properties.

Carbon black was modified with unsaturated light fatty acid to enhance the vulcanization and physical and mechanical properties of EPDM rubber. It was found that the addition of unsaturated fatty acid significantly improved the tearing performance and flexing performance of the vulcanized rubber while maintaining relatively high performance. Good thermal oxygen aging performance can be well applied to shock-absorbing rubber products.

• Application in SBRL (vulcanized styrene butadiene rubber)

Styrene butadiene rubber is a commonly used industrial latex, which has the advantages of low cost and wide sources. Sodium styrene sulfonate is used to modify carbon black to prepare nano-dispersed carbon black suspension, and then the carbon black suspension is mixed with SBRL to prepare modified carbon black reinforced SBRL, which is applied to tire repair fluid.

• Application in polyurethane sealant

In the presence of the initiator benzoyl peroxide, the surface of ordinary carbon black is organically modified with styrene.

Performance comparison of carbon black added to sealant before and after modification

The sealant made of modified carbon black compound has good tensile strength, hardness, elongation and shear strength, and reduces the cost, and is widely used in sealing fields such as construction and automobiles.

by ALPA Powder

Five key points for quality control of silicon powder products

Silica powder is a silica powder material made from natural quartz ore, fused quartz, etc., processed by multiple processes such as grinding, precision classification, and impurity removal. Grinding is one of the core processes in the production of silicon powder products. It directly affects its purity, particle size distribution and production cost.

In order to produce silicon powder products with stable quality and high performance, it is necessary to strengthen management and control from the following points:

1.  Ball mill control

It is possible to effectively control the impurity content and increase the service life of the equipment by reasonably selecting the grinding media material, controlling the media ratio and filling rate; according to the length to diameter ratio of the ball mill, the structure and distribution of the liner, and the particle size of the grinding, the speed of the ball mill can be reasonably adjusted to promote the grinding The material in the cavity maintains a good state of motion, thereby improving the grinding effect.

2.  Particle shaping

By optimizing the process conditions such as equipment operating speed, internal pressure and temperature, material residence time, etc., the regularity of the surface of the silicon powder can be improved, and the fluidity of the product can be improved. dispersion.

3.  Mixed compound

Unimodal silica powder cannot achieve the tightest packing, difficult to meet high filling requirements, and cannot maximize the excellent performance of silica powder. One of the ways to increase the filling rate is to mix the silicon micropowder products with different particle size distributions, and form a multimodal distribution through the mixing ratio, which achieves high filling and reduces the oil absorption value of the silicon micropowder.

4.  Surface modification

As an inorganic filler, silicon micropowder has problems of poor compatibility and difficulty in dispersion when mixed with organic resins, resulting in poor heat resistance and moisture resistance of materials such as integrated circuit packaging and substrates, which affects the reliability and stability of the product. In order to improve the problem of interface bonding between silicon micropowder and organic polymer materials and improve its application performance, it is generally necessary to modify the surface of silicon micropowder.

5.  Production condition control

The key to the production of electronic grade silicon powder is to remove the conductive impurities in the quartz. Therefore, in addition to the selection of purer raw materials, every link of production should minimize the pollution of the product by containers, the environment, and chemicals, and operate strictly.

To avoid contamination of materials during grinding, the grinding media used should be non-metallic materials, such as alumina ceramic balls or silica; the barrel of the mill must also be lined with high-strength wear-resistant materials, such as alumina ceramics, silica or Polyurethane rubber.

by ALPA Powder

Powder in life

No powder is not a material. Powder is the foundation of modern industry, the most important technical support force for high-tech industry, the most important cornerstone of modern defense industry, and the most basic raw material for all walks of life. Powder is everywhere and is closely related to our lives.

The term powder first appeared in the early 1950s. It is characterized by many discontinuous surfaces, a relatively large specific surface area, and is composed of many small granular materials. In a further generalization, powder is an aggregate composed of countless relatively small granular substances.

Powder refers to a collection of solid fine particles, <100μm is powder (dust), >100μm is (particle).

Powder exists in liquid, gas, and solid forms. The powder usually refers to a small-sized solid. The solid substance is divided into a dispersed state and an aggregate state. Most powders are in a dispersed state.

Basic properties of powder

• The geometric properties of the powder: the size, particle size distribution, particle shape, and accumulation state of the powder particles.
• Mechanical properties of powder: friction angle of powder, powder pressure, fluidity and movement properties in fluid.
• Other physical and chemical properties of the powder: the electrical, magnetic, optical, acoustic, and thermal properties of the powder, as well as its adhesion, adsorption, cohesion, wettability, and explosive properties.

Classification of powder

According to the cause, it can be divided into natural powder and artificial powder. According to the preparation method, it can be divided into mechanical crushing method and chemical method powder. According to the particle size, it can be divided into primary particles, aggregate particles, aggregate particles, and floc particles. According to the dispersion state, it can be divided into coarse powder (>0.5mm), medium and fine powder (0.074~0.5mm), fine powder (10~74μm), fine powder (0.1~10μm), nano powder (<100nm).

Common powder materials

Metal powders include reduced iron powder, zinc powder, copper powder, nickel powder, and aluminum powder. Non-metal powders include perlite, diatomaceous earth, tourmaline, icelandite, brucite, organic materials, natural rubber, and synthetic fibers. , Starch, cellulose, synthetic resin, inorganic materials include calcium carbonate, silicate, aluminate, phosphate, silicon powder.

In addition, there are carbon-based materials such as carbon black, graphene, carbon fiber, nanomaterials, composite materials, and powdered Chinese medicine.

Powder technology

• Preparation: various physical, chemical and mechanical methods.
• Processing: crushing, classification, dispersion, mixing, granulation, surface treatment, fluidization, drying, forming, sintering, dust removal, dust explosion, transportation, storage, packaging, etc.
• Test: Characterization of various geometric mechanical, physical and chemical properties of powder.

Powder in life

• Clothes

The different colors of clothes are due to the addition of oxides, chromates, sulfates, silicates, hydroxides, sulfides, metals, etc. Different powder materials can be used to make various buttons, such as resin buttons, ceramic (zirconia) buttons, plastic buttons, metal buttons (copper), etc. Adding calcium carbonate, kaolin, talc, barite and other powders to rubber shoes can enhance the tensile strength and wear resistance of the shoes. Adding nano titanium dioxide, nano zinc oxide, nano silicon oxide, etc. can inhibit bacteria and deodorize the worn socks. Adding carbon black, tin dioxide, zinc oxide, titanium dioxide, etc. can make clothes antistatic; adding some far-infrared nano ceramic powder can make clothes warmer.

• Food

Common food flour, soy milk, milk powder, coffee, salt, etc. are all powders; baking soda is needed to make bread and steamed bread; medical stone mineral water is called a treasure in mineral water; zeolite has also been developed as a health product. For anti-aging, remove heavy metals accumulated in the body. Commonly used bezoar detoxification pills and heat-clearing detoxification granules may be added with talc, lumps, pumice, alunite, arsenic, gypsum, etc.; aseptic tableware and aseptic food packaging made of nano-materials are already available.

• Residence

cement. Diatom mud with diatomaceous earth as the main raw material has good air purification and formaldehyde adsorption functions. Perlite insulation board is not only light in bulk density, but also high in strength, suitable for all kinds of buildings. Commonly used architectural coatings are added with kaolin, sepiolite, bentonite, gypsum powder, quartz powder, etc. Refractory materials such as silicon, magnesia, and carbon are used in various constructions.

• Travel

Carbon fiber, aluminum, and magnesium help reduce the weight of vehicles and airplanes; car tires, seats, steering wheels, etc. are filled with calcium carbonate, wollastonite powder, mica powder, aluminum hydroxide, etc.; carbon nanotubes can be used in integrated circuits; metals Lithium is used in the manufacture of lithium batteries; aluminum powder, mica powder, etc. are added to the paint.

Powder materials, powder technology, equipment and operations are used in various industries such as chemicals, plastics, paints, coatings, textiles, building materials, food, electronics, national defense, and environmental protection.

Intensify research efforts in mineral homogenization, purification, ultra-fine grinding, classification and grading, surface modification, etc.; develop in the direction of miniaturization, functionalization, high purification, and refinement; modernization and intelligentization of powder equipment.

Strengthen the application of mineral functional materials in energy saving and fire protection, filling and coating, environmental protection management, energy storage and moisturizing, etc.; extend to the fields of life science and information science.

by ALPA Powder

Preparation method of spherical alumina

Spherical alumina is also called sand alumina, alpha alumina. In the crystal lattice of α-type alumina, oxygen ions are densely packed in hexagons, and AI³⁺ is symmetrically distributed in the octahedral coordination center surrounded by oxygen ions. The lattice energy is large, so the melting point and boiling point are high. It has the characteristics of corrosion resistance, wear resistance, high temperature resistance, high strength, good insulation, large surface area, high hardness, and oxidation resistance.

Spherical alumina preparation process

• Ball milling method (high energy ball milling)

Ball milling is the most common method for preparing ultrafine alumina powder. The ball mill itself is a horizontal cylinder with built-in steel ball grinding media, so that after the material enters the cylinder, the impact force generated by the collision with the steel ball achieves the effect of crushing. Adding a grinding aid during the ball milling process can improve the uniformity of powder particle size.

The factors affecting the preparation of ultra-fine alumina powder by high-energy ball milling are ball milling time and ball milling speed. The advantages are simple operation, low cost and high output. The disadvantage is that the particle size distribution of the product is not uniform, the minimum particle size is mechanically restricted, and it is difficult to obtain spherical particles.

• Polymer network sol-gel method

The advantage is that the prepared alumina powder has a small particle size. The disadvantage is that the sphericity is very poor.

• Alkoxide hydrolysis

The advantage is that the particle size of the prepared powder is small. The disadvantage is that the cost is too high and the sphericity is poor.

• Template method

The template method uses a spherical raw material as a reagent for controlling the morphology in the process. The product is usually hollow or has a core-shell structure.

The main process is to use polystyrene microspheres as a template, coating with carbonic acid functionalized alumina nanoparticles, and then washing with toluene to prepare hollow alumina spheres.

The advantage is a good way to prepare hollow spheres. The disadvantages are high requirements for the template agent, many steps in the preparation process, and difficult operation.

• Aerosol decomposition method

Aerosol decomposition usually takes aluminum alkoxides as raw materials, uses the properties of aluminum alkoxides to be easily hydrolyzed and high-temperature pyrolysis, and adopts the physical means of phase change to vaporize the aluminum alkoxides, and then contact with water vapor to hydrolyze and atomize. After high-temperature drying or direct high-temperature pyrolysis, the gas-liquid-solid or gas-solid phase transformation is realized, and finally spherical alumina powder is formed.

The advantages are that water decomposition can be carried out without adding alkali, the reaction conditions are mild, and the operation is simple. The disadvantage is the high cost.

• Drop ball

The drop ball method is to drop alumina sol into the oil layer (usually paraffin, mineral oil, etc.), and form spherical sol particles by the action of surface tension, and then the sol particles are gelled in the ammonia solution, and finally the gel particles A method of drying and sintering to form spherical alumina.

The advantage is that the emulsion technology is applied to the aging stage of the sol, and the oil phase is kept intact, eliminating the need for separation of powder and oily reagents. The disadvantage is that it is usually used to prepare spherical alumina with a larger particle size, which is mainly used for adsorbents or catalyst supports.

• Radio frequency induction plasma method

Irregularly shaped alumina particles are sprayed into the plasma torch by a carrier gas through a feeding gun, and are quickly heated and melted. The molten particles form highly spherical droplets under the action of surface tension, and in a very short time The inside solidifies quickly, forming spherical particles.

• Flame melting

The flame melting method is to directly spray irregularly shaped alumina powder into the flame, so that the alumina powder is melted into a ball in the flame.

The advantage is that the process is simple, the cost control is more advantageous than the plasma flame spray method, the spheroidized product has high thermal conductivity, good sphericity, and controllable particle size.

• Homogeneous precipitation

The precipitation process in the homogeneous precipitation method is the formation of crystal nuclei, then agglomeration and growth, and finally the process of precipitation from the solution, usually in a non-equilibrium state, but if the concentration of the precipitation agent in the homogeneous solution can be reduced, even slowly The formation of nuclei will uniformly generate a large number of tiny crystal nuclei, and the resulting fine precipitation particles will be uniformly dispersed in the entire solution, and will maintain a state of equilibrium for a long time. This method of obtaining precipitation It is called homogeneous precipitation method.

The advantages are simple process, low cost, high purity, mass production of equipment, simple manufacturing, and short process flow. The disadvantage is that the existing colloids are difficult to precipitate, wash and filter, the powder is easy to mix with precipitating agent, the powder components are not easy to separate during precipitation, the precipitate can be re-dissolved during the washing process, and the precipitating agent will also cause a large amount of complex ions .

• Emulsion method

In order to obtain spherical powder particles, people use the interfacial tension between the oil phase and the water phase to produce tiny spherical droplets, so that the formation and gelation of the sol particles are limited to the tiny droplets, and finally spherical precipitates are obtained. Particles.

The advantage is simple operation. The disadvantage is that the cost is too high and the sphericity is poor.

• Sol-emulsion-sol method

Takashi Ogihara et al. used aluminum alkoxide hydrolysis to prepare spherical alumina powder through a sol-gel process. The entire hydrolysis system is relatively complicated. Among them, the octanol dissolving aluminum alkoxide accounts for 50%, the ethanol solvent accounts for 40%, and the octanol butanol disperses water. Alcohol accounted for 9% and 1% respectively, and propyl cellulose was used as a dispersant to obtain spherical γ-alumina powder with very good sphericity.

The advantage is that no impurity ions are introduced during the process. The disadvantage is that the price of raw materials is high, the particle size of the obtained powder is small, and the distribution is narrow.

• Spray method

The essence of the spray method for preparing spherical alumina is to realize the phase transition in a relatively short time. The product is made spherical by the effect of surface tension. According to the characteristics of the phase transition, it can be divided into spray pyrolysis, spray drying and spray melting. Law.

The advantages are stable chemical composition, high purity, excellent performance, and mass production. The disadvantage is that it is only effective for soluble salts and has certain limitations.

Application of spherical alumina

• Ceramic material

Under the same process conditions, spherical alumina powder has advantages in shape, which can change the microstructure of the material, increase the strength and density of the ceramic, reduce the sintering temperature, and significantly improve the performance of the ceramic.

• Surface protection layer material

Spraying ultra-fine alumina powder on the surface of plastic, paint, glass, alloy and metal materials can improve the wear resistance, corrosion resistance, stability and surface strength of the material.

• Catalyst and catalyst carrier

Ultra-fine alumina has strong adsorption characteristics, has many surface active points, has high reaction activity and selectivity, and provides necessary conditions for catalytic reactions. The spherical alumina used directly as a catalyst can reduce abrasion and increase the service life of the catalyst, thereby reducing production costs.

• Chemical mechanical polishing abrasive

Chemical mechanical polishing has been widely used in integrated circuit chips, microelectronic mechanical systems, and computer hard drives. As a polishing material, spherical alumina can avoid slip marks. Spherical alumina powder has a high packing density, which can reduce the scattering of the luminous body, effectively reduce the loss of transmitted light, and thus can improve the brightness of the screen.

• Luminescent material

Spherical alumina powder has a high packing density, which can reduce the scattering of the luminous body, effectively reduce the loss of transmitted light, and thus can improve the brightness of the screen.

• Petrochemical industry

In the petrochemical industry, alumina is the most widely used carrier.

Article source: China Powder Network

by ALPA Powder

Preparation & application of nano-silica

Nano-silica is an inorganic chemical material, commonly known as "ultra-fine white carbon black". It is a non-toxic, odorless, and pollution-free inorganic non-metallic material and high-tech ultra-fine inorganic new material. The size is between 1~100nm, and it has a three-dimensional network structure, which is easy to agglomerate and has poor storage stability.

Preparation of nano-silica

At present, the research on nano-silica mainly uses sodium silicate and ethyl orthosilicate as raw materials, while the raw materials for industrial production are mainly low-cost sodium silicate.

• Physical method

It is mainly mechanical pulverization. The large-particle silica is ultra-finely pulverized through the combined action of impact, shear, friction and other forces generated by the ultra-fine pulverizing machine. Then, a high-efficiency grouping device is used to separate the particles of different particle sizes, so as to realize the uniformity and specificity of the particle size distribution of the nano-silica powder.

The physical production process is simple, the production volume is large, and the production process is easy to control. However, the requirements for raw materials are higher, and as the particle size decreases, the particles agglomerate due to the increase of surface energy, and it is difficult to further reduce the particle size of the powder particles.

• Chemical method

1.Chemical gas phase reaction

This method uses organosilicon compounds (such as organohalosilanes, silanes, etc.), hydrogen and oxygen or air to mix and burn. After the organosilicon compounds are burned at high temperatures, they undergo high-temperature hydrolysis in the water produced by the reaction to prepare nano-silica.

The chemical gas phase reaction method has uniform particle size, small particle size and spherical shape, high product purity and few surface hydroxyl groups. In order for this method to cause chemical reactions, heating, radiation or plasma must be used to activate the reactants into molecules. Therefore, the equipment used in this method requires high requirements, the raw materials used are expensive, and the product prices are relatively high.

2.  Precipitation

The precipitation method is to mix the reactant solution with other auxiliary agents, then add an acidifier to the mixed solution to precipitate, and the resulting precipitate is dried and calcined to obtain nano-silica.

The precipitation method has a simple process and a wide range of raw materials and has been widely studied and applied, but the problem of difficult control of its product properties has not been solved.

3.  Sol-gel method

This method generally uses silicate or silicate as the precursor to dissolve in a solvent to form a uniform solution, and then adjust the pH value to hydrolyze and polymerize the precursor to form a sol.

The sol-gel process is easy to control and has been extensively studied, and the resulting product has a larger specific surface area. However, difficulty in washing, high requirements for raw materials and too long drying time limit its use.

4.  Microemulsion method

By adding acidulant or catalyst dropwise to the microemulsion prepared from the precursor, the preparation reaction takes place in the microemulsion bubble, and the microemulsion is used to confine the nucleation, growth, coagulation, and agglomeration of the solid phase to a tiny spherical shape. In the droplet microbubbles, nano-spherical particles are formed, and further agglomeration between the particles is avoided, and it is easy to realize the controllable production of the body size.

Because of its nano-scale self-assembly ability, it is easy to realize the controllable preparation of particle size and morphology, which has attracted the interest of many researchers and has become a research hotspot in recent years. Because of its high cost, difficult to remove organic ingredients and easy environmental pollution, it has not been widely used in industry.

Surface modification of nano-SiO₂

There are a large number of active silicon light bases on the surface of nano-silica, with small size and large specific surface area, which makes it easy to agglomerate. Filled directly into organic materials, because it is difficult to infiltrate and disperse, and has poor compatibility, it is difficult to play a role, which limits its industrial application.

• Physical method

The surface coating method is a modification method in which the surface is modified and there is no chemical reaction with nano-SiO₂ , and the coating and the particles are connected by intermolecular force.

The heat treatment modification is a comprehensive process in which nano SiO₂ is placed on the back of a certain medium for heating, heat preservation and cooling, and the performance is controlled by changing the surface or internal structure of the nano SiO₂ .

• Chemical method

Fatty alcohol reacts with the hydroxyl groups on the surface of SiO₂ to remove water molecules. The hydroxyl groups on the surface of SiO₂ are replaced by alkyl groups, and alcohols are used as modifiers.

Application of Nano SiO₂

• coating

Nano-silica has a three-dimensional network structure, has a huge specific surface area, shows great activity, can form a network structure when the coating is dried, and improves the suspension of the pigment, which can keep the color of the coating without fading for a long time. In building interior and exterior wall coatings, it has excellent self-cleaning ability and adhesion.

• Adhesive/sealant field

In the field of adhesives and sealants, nano-silica is an important product with a large amount and a wide range of applications. At present, domestic high-end sealants and adhesives mainly rely on imports.

• rubber

It can improve the strength, toughness, and life of rubber products. In addition, it can also be used to make transparent rubber soles, and this type of products used to rely on imports.

• plastic

Improve the toughness, strength, abrasion resistance, aging resistance of plastics and improve the aging resistance of plastics.

• Textile field

The composite powder of the appropriate ratio of nano-silica and nano-titanium dioxide is an important additive for anti-ultraviolet radiation fibers, and can also increase the warmth retention effect and reduce the weight of clothes.

• Antimicrobial agent field/catalysis field

Nano-silica is physiologically inert and highly absorbent. It can absorb antibacterial ions to achieve antibacterial purposes. It can be used in the manufacture of refrigerator shells and computer keyboards.

• Agriculture and food

Can make the vegetables ripen earlier.

by ALPA Powder

Characteristics and application of high-purity quartz sand raw materials

Quartz sand includes ordinary quartz sand, refined quartz sand, high-purity quartz sand, and fused quartz sand. High-purity quartz sand generally refers to fine quartz powder with a SiO₂ content of more than 99.9%. It is a neutral inorganic filler and does not react with the filler. It is a very stable mineral filler.

The difference between high purity quartz sand and ordinary quartz sand

High-purity quartz sand has unique physical and chemical properties, especially its inherent crystal structure, crystal shape and crystal lattice change law, making it resistant to high temperature, small thermal expansion coefficient, piezoelectric effect, corrosion resistance, high insulation, and resonance effect And unique optical characteristics.

Chemical composition of high-purity quartz sand (μg/g)

 Particle size distribution of high purity quartz sand

 Raw material of high-purity quartz sand

• Natural Crystal

The advantages are high purity, low impurity content, less inclusions, and pure crystals can be directly used to produce electro-quartz.

The disadvantage is that the softening point is low, and a large amount of industrial production is difficult to ensure the uniformity of the mineral structure and the consistency of the internal quality and chemical content; the crystal reserves are small, and the distribution is uneven, and there are few high-grade crystals.

• Natural rock minerals (vein stone, quartz stone, etc.)

The advantage is that the raw material reserves are abundant and there are many types.

The disadvantage is that the direct extraction of ultra-pure quartz sand is currently the most advanced technology for producing ultra-pure quartz sand in the world, and only the United States, Japan, and Germany have mastered this technology.

Application of high purity quartz sand

• Quartz glass

Known as the "King of Glass", it is widely used in aerospace technology, light curing, circuit manufacturing, semiconductors, ultraviolet sterilization, laser technology, high-tech lighting sources and other fields and civilian fields.

• Electronics industry

Packaging materials, basic electronic materials, used to prepare monocrystalline silicon and polycrystalline silicon.

• Photovoltaic industry

Solar panels, semiconductor chip materials, etc.

by ALPA Powder

Nano coating preparation and application

Nano-coatings are generally made by mixing nano-materials and organic coatings. Therefore, more scientifically speaking, it should be called nano-composite coatings. It is generally believed that two conditions must be met before it can be called a nano-coating: the particle size of at least one phase in the coating is in the range of 1-100nm; the existence of the nano-phase makes the performance of the coating significantly improved or has new functions .

Nano coatings are composed of film-forming substances, pigments and fillers, additives, and solvents. Compared with ordinary coatings, nano coatings have the following characteristics: they can produce negative ions and have a health care effect on the human body; they can decompose and absorb harmful substances in the air, such as formaldehyde, etc.; have unique anti-mildew and sterilization functions; and have super self-cleaning Function; has super resistance to washing; super resistance to artificial aging; has the function of waterproof and super heat insulation.

Classification

• Nano silica coating

Silica architectural coatings do not delaminate, are thixotropic, anti-sagging, have good application performance, and greatly improve stain resistance, and have excellent self-cleaning performance and adhesion. The nano-silica coating can form a network structure when it is dried, which can improve the smoothness and anti-aging degree of the coating of vehicles and ships.

• Nano titanium dioxide coating

Nano-titanium dioxide architectural coatings can improve the weather resistance of latex paint to a new level. The application technology of the catalytic composite coating is simple and low in cost. The atmospheric environment purification coating made by the nano-titanium dioxide photocatalytic oxidation technology has a good purification effect on nitrogen oxides in the air and can also degrade other pollutants in the atmosphere.

• Nano calcium carbonate coating

Calcium carbonate is an excellent filler and white pigment with the characteristics of low price, abundant resources, good color and high grade. Application studies have shown that the flexibility, hardness, leveling and gloss of nano-calcium carbonate filled coatings are greatly improved.

Main equipment used in production

The application of nano-materials in coatings has greatly improved the performance and environmental protection of coatings, and has become the darling of the market. The main equipment for the production of nano-coatings has the following five types.

• High-speed dispersion machine

The high-speed disperser is used to pre-mix the paint and the grinding slurry.

• Ball mill

It is mainly used to grind difficult-to-disperse pigments, fillers, and coatings into color pastes or grind to the specified fineness.

• Paint mixing equipment

After dispersion, the finely ground paint slurry and some coating resins, coating additives, solvents and color pastes are mixed uniformly with paint mixing equipment, and reach the specified color, viscosity and other indicators. Some coatings also need to use a high-speed disperser to adjust the paint.

• Filter equipment

Filtering equipment is used to filter a small amount of coarse slag and other impurities in the paint after the paint is finished, so as to achieve the purpose of purification. The commonly used equipment is a vibrating screen, which is easy to operate and easy to clean.

• Filling equipment

Filling equipment is divided into manual and automatic paint filling equipment, which is used to seal the finished paint packaging of specified volume and quality.

Application field

• Nano waterproof coating

Nano-waterproof technology mainly uses nano-scale molecular organic coating materials. In a vacuum and dust-free environment, the electronic products are perfectly packaged through ultrasonic vibration to achieve the same function in the water nano-waterproof coating as in the normal state of use.

• Self-cleaning nano coating

The self-cleaning nano-coating makes it easier to keep the solar panels clean and higher working efficiency, reducing maintenance and operating costs. Utilizing the dual phobic mechanism of nanomaterials, the water in the coating can be effectively discharged, and the intrusion of external water can be prevented, so that the coating film has the performance of breathing. At the same time, the physical properties of the dual interface of nanomaterials are used to effectively discharge the intrusion of dust and oil, so that it maintains good self-cleaning properties.

• Nano coatings for optical applications

The particle size of the nano-particles is much smaller than the 400-750nm wavelength of visible light, and has a transmission effect, thus ensuring the high transparency of the nano-composite coating. Nano particles have a strong absorption effect on ultraviolet light. Add TiO₂, SiO₂ and other nanoparticles to exterior wall architectural coatings to improve weather resistance, and add TiO₂ to automotive topcoats to improve the aging resistance of automotive coatings.

• Stealth Nano Coating

Nano stealth material has excellent absorbing characteristics, and at the same time has the characteristics of good compatibility, small quality and thin thickness. The coating made of it can reduce the detection distance of the detector in a wide frequency band. Visible light, infrared and sound have a stealth effect, so they have a wide range of applications in the military.

• Nano antibacterial coating

The irradiation of light can cause the TiO₂ surface to form a wonderful super amphiphilic property where the hydrophilic and lipophilic two phases coexist in the area where the negative ions are washed and returned to the ecological protection rice. Domestically, industrially produced nano antibacterial powders have been used in coatings, and nano antibacterial coatings can be made, which can be applied to building materials, such as sanitary ware, indoor spaces, appliances, walls and floors in hospital operating rooms and wards, etc. Sterilization and cleaning effect.

Reference

Li Xunsheng et al. "Application Examples of Composite Nanomaterials in Coatings"

Ke Changmei et al. "Preparation of Nanocomposite Coatings"

Wang Zhiqiang et al. "Nano Coating and Its Preparation"

Zhang Xiaojuan. "Overview of the Development of Nano Coatings"

by ALPA Powder

Heavy calcium + superfine processing equipment

There are many types of heavy calcium grinding and processing equipment. They are combined with ultra-fine grade machines to form an ultra-fine processing system, which can generally achieve the effect of ultra-fine production. At present, the mainstream demand for heavy calcium products in heavy calcium market is 600 to 1500 mesh heavy calcium products. The value-added rate of heavy calcium products is relatively low (compared with talc, barite, kaolin, etc.), and scale is one of the main factors affecting benefits.

Heavy calcium ultra-fine processing equipment is divided into grinding equipment and grading equipment. The grinding equipment includes Raymond mill, vibration mill, dry stirring mill, ring roller mill, vertical mill, ball mill, and impeller-type ultra-fine grade machine adopts the principle of forced eddy current.

Comparison of various types of ultra-fine processing equipment

Although Raymond mills are currently commonly used equipment in heavy calcium enterprises, most of the equipment is difficult to achieve large-scale production of ultra-fine heavy calcium.

Practice has proved that in the dry large-scale production of ultra-fine heavy calcium products with more than 600 meshes, there are mainly two types of technologies and equipment suitable for the development of the industry, namely, high-fine ball mills with ultra-fine grade machines and ultra-fine vertical mills with ultra-fine mills. Subdivision level machine.

Comparison of processing systems between vertical mill and ball mill

Regarding the fluctuation of the quality (fineness) of the powder (lower grade) under the secondary classification of the vertical mill, the description is as follows: the vertical mill produces heavy calcium, and the fineness of the milled product is generally below 1000 mesh. If 1250 mesh is produced The above products must be classified twice. Similarly, the secondary classification of 800-mesh powder produced by the vertical mill results in different particle size distributions of the two lower products, which makes it difficult to define the quality of the lower products.

The use of ball mills and large classifiers makes it possible to produce single-machine heavy calcium on a large scale. The single-machine capacity of the ball mill is the largest, and its performance is more prominent when producing products with more than 1250 mesh. The superfine vertical mill has obvious energy saving effect when producing 400~1000 mesh heavy calcium products. The production of large classifiers has been very mature and reliable, producing heavy calcium powder below 2500 mesh, which greatly reduces investment costs and maintenance costs. The combined use of multiple large classifiers is an effective way to diversify products at the same time. The demand for ultrafine heavy calcium powder below 2μm is increasing rapidly, and the research on large-scale sub-micron classifiers is the main task at present.

Article source: China Powder Network

by ALPA Powder

Preparation and modification method of white carbon black

White carbon black is a general term for fine powder or ultrafine particle anhydrous and hydrated silicon dioxide or silicate. It is a white, non-toxic, amorphous fine powder or granular substance, and its silicon dioxide content is greater than 90%, the original particle size is generally 5-40nm, because the surface contains more hydroxyl groups, it is easy to absorb water and become aggregated fine particles.

White carbon black products can be divided into precipitation method white carbon black and gas phase method white carbon black according to the manufacture, and can be divided into gas phase method white carbon black, ordinary precipitated white carbon black and highly dispersed precipitated white carbon black according to the market.

The gas-phase white carbon black has small particle size (15-25nm), low impurities and high purity, superior water resistance, good dielectric properties, great flying properties, and superior reinforcement, but the process is complex and the price is high.

The precipitated silica has a large particle size (20-40nm), low purity, poor reinforcement and dielectric properties, but it can change the flexure and cracking properties of the rubber, and has good process performance and low price.

Preparation of white carbon black

The traditional method of preparing white carbon black is to use sodium silicate, silicon tetrachloride, and ethyl orthosilicate as the silicon source. Except for sodium silicate, other costs are very high. The new method uses cheap non-metallic minerals as the silicon source, which greatly reduces the production cost of white carbon black.

The use of non-metallic minerals to produce white carbon black is technically feasible and has good economic benefits. Commonly used raw materials are diatomite, serpentine, bentonite, kaolin, wollastonite, quartz sand, sepiolite, and bumps. Rod stone, fly ash, axonite, coal gangue, yellow phosphorite, etc.

Surface modification of white carbon black

The surface modification of white carbon black is to use the modifier to make the hydroxyl groups on the white carbon black surface react with the modifier through a chemical process to eliminate or reduce the silanol group on the surface to achieve the purpose of changing the surface properties.

There are three types of hydroxyl groups on the surface of white carbon: isolated and undisturbed isolated hydroxyl groups, adjacent hydroxyl groups that form hydrogen bonds with each other, and two hydroxyl groups connected to a Si atom.

The dry modification process is simple, the post-processing procedures are few, and the large-scale production is easy. The wet modification production process is simple, uses less equipment and lower production cost.

Application of white carbon black

Reinforcing agent and filler in rubber field

Carrier and filler for feed, pesticide and medicine

Matting, thickening and anti-settling of paint and ink

Friction agent and thickener for toothpaste, filling for papermaking

by ALPA Powder