ANALYSIS ON THE DEVELOPMENT DIRECTION OF FUNCTIONALIZED CARBON BLACK IN THE FUTURE

УДК 678.742

Дата направления в редакцию: 11-03-2020 Дата рецензирования: 12-03-2020 Дата публикации: 20-06-2020

Ван Хонг Чу Линлин Wang Hong Chu Lingling

Qingdao Black Cat Carbon Qingdao Black Cat Carbon

Black Technology Co., Ltd., Black Technology Co., Ltd.,

Qingdao, Shandong, 266042 Qingdao, Shandong, 266042

АНАЛИЗ НАПРАВЛЕНИЯ РАЗВИТИЯ ФУНКЦИОНАЛИЗИРОВАННОГОТЕХНИЧЕСКОГО УГЛЕРОДА В БУДУЩЕМ

ANALYSIS ON THE DEVELOPMENT DIRECTION OF FUNCTIONALIZED CARBON BLACK IN THE FUTURE

Аннотация (на рус). В связи с растущим спросом на каучук для экологически чистых материалов, предприятия сажи в стране и за рубежом разработали функционализированную сажу с низким гистерезисом и низким сопротивлением качению, чтобы приспособиться к разработке зеленых шин. Окисление поверхности, модификация прививки и модификация оболочки являются обычными методами модификации технического углерода. Новые композитные материалы из углеродных нанотрубок / технического углерода и графена могут улучшить электрическую проводимость, теплопроводность и износостойкость резины протектора, уменьшить накопление тепла в резиновой основе протектора и повысить долговечность шины. Перспектива применения двух видов материалов также входит в поле изучения.

Abstract (in Eng). With the increasing demand of rubber for ecologically clean materials, soot enterprises in the country and abroad have developed functionalized soot with low hysteresis and low rolling resistance in order to adapt to the

development of green tires. Surface oxidation, grafting modification and cladding modification are the conventional modification methods of carbon black. The new composite materials of carbon nanotubes/carbon black and graphene/carbon black can improve the electrical conductivity, heat conductivity and wear resistance of the tread rubber, reduce the heat accumulation of the tread base rubber, and improve the durability of the tire. The application prospect of two kinds of materials is also entering the field of vision.

Functionalized carbon black refers to carbon black that is chemically or physically modified on the basis of carbon black so that the surface of the carbon black matrix material forms functional groups with certain chemical or physical properties and specific properties or functions.

With the development of the properties of carbon black, the application of carbon black has been expanded, including rubber, printing ink, coating, plastic, battery, electronic components, agriculture and synthetic leather and other industries and fields. At present, with the continuous upgrading of products in various fields, carbon black is regarded as the main raw material, and its product performance must continuously adapt to the new requirements of users. High-tech content and leading carbon

black products are becoming more and more popular. At present, the pressure of the global environmental pollution is very high. Whether the carbon black meets the environmental protection requirements in terms of the selection of raw materials, the whole process of the manufacturing process and the performance of final products and whether it can provide users with green, energy-saving and safe products has attracted more and more users& attention. All of these provide an opportunity for the development of various kinds of functionalized carbon black.

At present, functionalized carbon black for non-rubber purpose has developed rapidly. In particular, foreign famous carbon black enterprises have formed a series of high-end functionalized carbon black with complete functions, their own characteristics and standards

in recent ten years. These kinds of functionalized carbon black meet the green environmental protection development needs of printing ink, plastic, battery and other areas.

However, the development of functionalized carbon black for rubber purpose is lag mainly because the R D and upgrading period of new products is long, and the requirement of green environmental protection performance of raw materials by downstream traditional users is not particularly strong. However, as the environmental awareness of the whole society continues to strengthen, the demand for green

environmental performance materials will continue to increase, so green environmental-friendly materials for rubber will also be more and more applied and popularized.

The rapid development of carbon black post-treatment technology, especially the rapid development of carbon nanomaterials in recent ten years, has provided technical support for the development of various kinds of functionalized carbon black in the future. This is mainly reflected in the treatment of specific surface area of carbon black, structure, pH, surface functional group and other properties.

Table 1 Scope of main indexes of medium and high-end conductive carbon black

Project NSA103m2/kg DBP, 10-5m3/ kg PH value 325#ppm 2/9 resistance ratio

Mid >150 >150 6-8 <20 >1.8

High >400 >300 6-8 <20 >1.8

Table 2 Indexes of main pigment and conductive carbon black at home and abroad

S/N Special carbon index Blackness value M Color intensity % Volatile % Oil factor 10-5m3/Kg PH Ash % NSA 103m2/kg Size nm

Middle-end

These carbon black indexes endow with excellent properties of carbon black are mainly

excellent dyeing performance, high blackness, produced by treating the surface of the carbon

high conductivity, high dispersity, high purity, black, which are typical representativess of

and low pollution characteristics. Some of the functionalized carbon black. The development

trend of functionalized carbon black for non-rubber purpose in the future mainly focus on making carbon black have high specific

surface area, high structure, high dispersity, high acidity and alkali and low ash content and other characteristics through the treatment of the surface of carbon black.

[1] The surface of carbon black is activated by the polymer material with free radical trapping effect, so that it can initiate the activity and then initiate the polymerization and grafting of the monomer. For example, butyl acrylate is grafted onto the surface of carbon black by atom transfer radical polymerization (ATRP) by using carbon black particles with C6H4Na on the suface as a raw material. The experiments of thermal weight loss and light scattering show that a considerable amount of polymer has been grafted onto the surface of carbon black to obtain poly butyl acrylate. The grafted functionalized carbon black can form stable dispersion liquid in organic solvent.

[2] Carbon black is mixed with diazonium salt solution containing silver, copper, nickel, etc. The metal groups can be linked to the organic groups on the surface of carbon black and generate special functionalized properties. It is mainly used in the fields of catalysis, electron heat transfer, ion heat transfer, absorber and luminescence.

The structure of carbon black (DBP=20-40cc/10g, I2=30~200mg/g) can be effectively reduced by injecting auxiliary hydrocarbon gas into the reaction zone of carbon black.

This low-structure carbon black is used in the fields of toner, spray ink, pigment, and the like. The coating viscosity can be reduced. More carbon black is allowed to be added, and a higher optical density (reflecting the opacity of the material) can be obtained with few alkali metals, and low acidity and hydrophilicity. In the conventional production, alkali metal is injected into a reaction furnace to reduce the structure, so that more electriferous groups and charge are

accumulated on the surface of carbon black

This improves the viscosity of printing ink, pigment, coating, and makes carbon black acidic and hydrophilic, hindering the compatibility with printing ink, pigment and other polymers in the coating.

Mesoporous carbon black having void greater than 2 nm and a higher specific surface area is formed by oxidation of carbon black with oxidizing agent in a fluidized bed. The general specific surface area is over 600-1,200 m2/g, NSA/STSA = 0.95-1.1. Figure 1 is a process flow chart of oxidation modification.

The main process conditions include:

Oxidant: steam, CO2, nitrogen, or inert gas;

Fluidized bed temperature shall be greater than 800 °C;

Ratio of steam to carbon black weight =0.2;

Carbon black flow rate = 0.1 m/s, reaction time is more than 0.5 hour.

Figure 1 Process flow chart of oxidation modification

This kind of mesoporous functionalized carbon black is mainly used in conductive plastics, ink-jet ink, battery electrode and ultralarge capacitor. In the past, the carbon black with void is produced mainly by increasing the reaction time of the carbon black in the reaction furnace and adding alkali metal. However, this method can only obtain microporous carbon black with void of less than 2 nm.

In order to improve the structure of carbon black, a multistage reactor is used to spray raw

material at more than two positions in the axial direction. In addition, various kinds of oxidizing active agent are injected downstream of the reaction section, so that various functional groups are formed on the surface of carbon black, and the dispersity of carbon black is improved. The main indexes of functionalized carbon black: DBP > 170, STSA = 160220. The following diagram shows the structure of the multistage reactor.

Figure 2 Structure diagram of multistage reactor

Printing ink is the biggest pollution source of the printing industry at present and the environmental-friendly ink, mainly including the water-based ink, is the development direction in the future. The carbon black slurry with different concentration can be prepared by modifying and emulsifying the surface of carbon black, and the concentration can be adjusted arbitrarily by adding water, which is the most important material for preparing black water-based environmental-friendly ink.

Through the modification of carbon black and physical or chemical combination of carbon nano tubes and graphene, new nano-scale composite materials are produced. These new materials will improve the corrosion resistance of the coating, improve the storage capacity of the battery and fast charging. They are applied in anticorrosive paint, new energy automobile battery, mobile phone battery and so on.

Functionalized carbon black for non-tire rubber products is modified on the basis of existing ASTM standard and is mainly divided into two types.

One is to increase the purity of carbon black to meet specific performance requirements. The ash content and 325 mesh sieve residue of this

Figure 3 Conventional carbon black solution (delamination)

Figure 4 Carbon black emulsion slurry (uniform)

type of carbon black are very low. Ash content is typically less than 0.10% and 325 mesh sieve residue is less than 20 ppm; specific surface area is CTAB 30-45 m2/g, COAN 50-90 ml/100g. This type of carbon black is suitable for rubber extrusion, calendering and molded products, especially automotive sealing strips. Such carbon black products are not only improved in appearance but also extended in service life, and are more easily dispersed and more uniformly vulcanized during rubber processing to reduce the rejection rate.

The other is a special variety "tailored" for industrial rubber products for specific use. This kind of carbon black can be used for rubber products with different functions, such as door and window sealing strips, wiper, air-conditioning pipe, oil seal, transmission belt and sealing ring through improving comprehensive property by modification treatment including oxidation and grafting.

Throughout the development history of tire, from the initial solid tire to bias tire, and then to the radial tire, and finally to the current green tire, it is a process where tire rolling resistance constantly decreases. In 1992, Michelin produced the first green tire (containing silicon), meaning that low rolling resistance radial tires will begin to replace ordinary radial tires.

Currently, the concept of green tire extends to radial tire that uses new material and design to reduce rolling resistance, thus achieving low fuel consumption and low exhaust emission.

During the driving process of the automobile, the tires will be deformed to cushion the unevenness of the road surface, so they can provide grip and comfort. When the rubber sizing material is deformed, its temperature rises and it consumes part of the energy transmitted by the engine. This phenomenon is called rolling resistance. On average, 20%-30% of the fuel consumption is used to overcome rolling resistance, while the rest of the fuel consumption is used to combat air resistance, inertia, and internal friction (e.g., inside the engine or gearbox).

Shear and

Figure 5 Schematic diagram of tire rolling resistance formation

The tire industry focuses on environmental protection and safety, and the tire performance is developing towards the direction of low rolling resistance, high traction, good wear resistance and durability, which promotes the development and application of new carbon black varieties. At present, foreign carbon black enterprises

have developed some functionalized high-quality carbon black to meet the needs of highperformance tires and racing-car tires, including green low hysteresis carbon black, ultra-high structure carbon black, nano structure carbon black and modified carbon black and other new varieties, so that comprehensive performance of tires gets improved in the premise of maintaining tread wear resistance.

In order to adapt to the development of green tires, carbon black enterprises at home and abroad have developed functionalized carbon black with low hysteresis and low rolling resistance properties, such as two kinds of dualphase carbon black containing silicon developed by Cabot of the United States: CSDPF2000, with low silicon content and uniform distribution inside and outside of carbon black particles, is mainly used for truck tires; CSDF 4000, with high silicon content, and silicon covered on the surface of carbon black, is used for car tires.

Richardson Corporation of the United States developed and launched a new class of functionalized carbon black derived from chemical modification. ES 200,carbon black is mainly used for loader tires.

The modification methods of carbon black mainly include surface oxidation modification [3], grafting modification [4-7] and cladding modification. Surface oxidation modification can be divided into gas phase oxidation, liquid phase oxidation, plasma oxidation and catalytic oxidation. The main purpose is to increase the carbonyl group, hydroxyl group, carboxyl group and other functional groups on the surface of carbon black, so as to increase the combination of carbon black and rubber, increase the content of the combined rubber and improve the wear resistance of the sizing material. However, this has little effect on reducing the heat generation and hysteresis loss of the sizing material.

(1) Modification by liquid phase oxidation

Carbon black is treated with one or more kinds of ionic liquid. It can be found from the pictures that there are many "grape" particles. After amplification to observe particles, it can be found that different sizes of carbon black particles overlap together, carbon black is more compact in morphology, and irregular in shape.

Figure 6 Liquid phase oxidation modified carbon black

The wetting process and dispersion time of carbon black modified by liquid phase oxidation are obviously shortened, and the flexural fatigue resistance of styrene-butadiene rubber vulcanizates can be greatly improved by adding ionic liquid.

(2) Grafting modified carbon black

The process of linking a polymeric compound to the surface of carbon black by chemical action. It includes free radical grafting, polymerization grafting and grafting of surface functional groups of carbon black with polymer. The main purpose is to increase the bonding with a certain matrix, and the surface of carbon black is grafted with the same substance of the matrix to increase the bonding with a certain matrix.

In the above, butyl acrylate is grafted onto the surface of carbon black by atom transfer radical (ATRP) polymerization by using carbon black particle with sodium benzene carboxylate (-C6H4Na) on the surface as a raw material. The experiments of thermal weight loss and light

Figure 7 Electron microscope photo of liquid phase modified carbon black

Figure 8 Schematic diagram of grafting modified carbon black

scattering show that a considerable amount of polymer has been grafted onto the surface of carbon black to obtain poly butyl acrylate. The grafted carbon black may form stable dispersion in organic solvent.

(3) Cladding modified carbon black

The main purpose of the modification process of carbon black coated with white carbon black is to improve the dispersion of white carbon black in carbon black and sizing material.

Figure 9 Energy spectrum Figure 10 Electron microscope analysis photo of cladding modified carbon black

Figure 11 Electron microscope photo of common carbon black

A. Fullerene

It is a kind of carbon in elemental form with zero-dimensional structure. Among them,

C molecule was found earlier and has made

important progress. C60 molecule is a molecule made up of 60 carbon atoms. It resembles a

football, so it is also known as footballene. Cin

is a stable molecule formed solely by the binding of carbon atoms, with 60 vertexes and 32 faces, of which 12 are regular pentagons and 20 are regular hexagons, with a relative molecular mass of about 720. It has many excellent properties, such as superconductivity, strong magnetism, high pressure resistance, and chemical corrosion resistance, with broad application prospects.

B. Carbon nano tubes

Carbon nano tubes are in one-dimensional structures, mainly divided into single-walled and

Figure 12 Schematic diagram of fullerene C6n structure

multi-walled carbon nano tubes. Carbon nano tubes have good mechanical properties. The tensile strength reaches 50-200 GPa, which is 100 times higher than that of steel, but the density is only 1/6 of that of steel. The draw ratio of the carbon nano tubes is generally 1,000: 1 or more. carbon nano tubes are ideal high-strength fiber materials. Carbon nano tubes have good electrical conductivity, good heat transfer performance and high thermal conductivity. As long as a small amount of carbon nano tubes are doped into the composite, the thermal conductivity of the composite may be greatly improved.

Single-walled carbon nano tubes

Multi-walled carbon nano tubes

Figure 13 Schematic diagram of single-walled and multi-walled carbon nano tubes

Tear strength kN/M

Heat conductivity coefficient W/Mk

Volui resistivity

strength/MPa

Figure 14 Electron microscope photo of carbon nano tubes

C. Graphite [8-9]

Graphene is in two-dimensional structure, divided into single-layer, few-layer and multilayer graphene, with high electrical conductivity, extremely high heat conductivity coefficient (better thermal conductivity than carbon nano tube), high strength, ultra thin and light properties. The following is electron microscope photo of graphene.

Figure 15 Structure diagram of graphene

Single-layer

Few-layer

Multi-layer

Figure 16 Electron microscope photo of graphene

(2) Development of functionalized nano carbon black for tire purpose

Through the composite treatment of carbon nano tubes [10-15] with carbon black, graphene and carbon black, a composite material of carbon nano tube /carbon black and graphene/carbon black is formed, and the following objects are achieved:

A. To improve the dispersion of nano materials in rubber matrix, the interaction between composite fillers and the interaction

between fillers and rubber without destroying the properties of nano materials.

B. To improve the electrical conductivity, heat conduction and wear resistance of the tread rubber, reduce the heat accumulation of the tread base rubber, and improve the durability of the tire.

C. To solve the difficult dispersion of nano materials in sizing material, and to meet the need of higher mechanical properties of rubber composite.

Figure 17 Electron microscope photo of graphene/carbon black composite

Figure 18 Electron microscope photo of carbon nano tubes/ carbon black rubber compound

Figure 19 Electron microscope photo of graphene/carbon black composite

Properties of graphene/carbon black, carbon nano tubes/carbon black

The following data show a comparison of the sizing material properties of two composites with conventional N234 in a radial half steel tire formulation (Table 3).

Table 3 Comparison of properties of sizing material

N234 N-1 N-2

Heat conductivity coef- 100 135 125

ficient W/Mk

Volume resistivity/Q 100 1 1

Akron abrasion/ 100 70 75

cm3/1.6km

Hardness 100 103 102

Tensile strength/MPa 100 114 110

Tear strength kN/M 100 140 133

tion stress / mpa

Compression tempera- 100 95 98

ture rise/ °C

Note: N-1: graphene/carbon black composite; N-2: carbon nano tubes/carbon black composite.

In terms of the development course of carbon black, it has been more than 50 years since the birth of new process carbon black. with the rapid development of scientific and technological progress, major changes have taken place in

Figure 20 Electron microscope photo of carbon nano tubes/ carbon black composite

relevant industries related to carbon black, and environmental protection and safety have become a consensus, which requires the future development of the carbon black industry to adapt to these changes. The current production process of carbon black and the performance of raw materials can not meet these requirements, which requires researchers in the carbon black industry to break through the existing process, and to produce environmental-friendly and safe carbon black products needed by the market .based on the existing raw materials.

Therefore, the technical R D of functionalized carbon black will be an important aspect of the scientific and technological progress of carbon black in the future. However, the following technical difficulties still exist:

In the future, with the continuous increase of

scientific and technological input in the carbon black industry and the unremitting efforts of scientific research personnel, the above difficulties will also be broken through, so that functionalized carbon black will be widely used and popularized.

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© Wang Hong Chu Lingling, 2020

Ссылка на статью: Wang Hong Chu Lingling - Analysis on the Development Direction of Functionalized Carbon Black in the Future // Вести научных достижений. Естественные и технические науки - 2020. -№1. - С. 20-29. DOI: 10.36616/2687-1335-2020-1-20-29 URL: https://www.vestind.ru/journals/architecture/ releases/2020-1/articles?Viewpage=20