50% of China's talcum powder production The above is used in the paper industry. It is mainly used for papermaking fillers, resin adsorbents, and a small amount for paper coating pigments.
1 talc structure and its special properties
Talc powder is hydrated magnesium silicate, and its theoretical molecular formula is 3MgO· 4SiO2·H2O. It has a layered structure and is divided into three layers with an eight in the middle. The MgO layer of the facet is a tetrahedral layer of silica [1]; talcum powder The two -OH groups are inside and, therefore, the surface is hydrophobic. This is slippery Stone powder has different properties from other pigments.
Talc has its unique properties: layered structure: interlayer of talcum powder Van der Waals' weak force makes it easy to crack into a thin layer during grinding; hydrophobicity (pro Oily): the lower surface energy, the organic matter is easily adsorbed to its layered surface On the surface, in the production of colored paper, the addition of talc reduces the dye Consumption, effectively saving costs, in addition, its surface lipophilicity makes it Can be used as a resin, adhesive control agent and waste paper deinking agent; softness: make The surface of the coating is smooth and compliant, which reduces the breakage of the coating and reduces the printing pressure. Force, etc.; lower friction factor: can reduce the equipment (forming mesh, scraper and Printing machine) to abrade, thereby extending its service life; chemical inertness: not with Any chemical reaction is not affected by any other additives, and other The coating composition has good compatibility, which means that the pH value does not change. Sensitive, this chemical inertness also makes it environmentally friendly.
2 talc powder used as paper filler
In the early 1990s, the main use of talc in the papermaking field The technical significance is still filler, accounting for 60% of the total national talc consumption. right.
Talc powder has high whiteness, high density and high refractive index. Industry's fillers have the advantage of being chemically stable, not only suitable for acid strips Under the condition of papermaking, it can also be used with calcium carbonate to make paper under neutral conditions; Its friction coefficient is small (less than calcium carbonate), which can extend the paper making network Life expectancy, also suitable for high speed paper machine; it is flaky particles, which is beneficial to Preserving and improving paper opacity, smoothness and printability in the paper; The surface is lipophilic and can adsorb organic matter in the same way as a filler. At the same time, I also received the effect of removing the resin barrier, which helped in the deinking of waste paper. In the removal of ink, this is unmatched by kaolin and calcium carbonate fillers. Can be combined with a sizing agent to improve the retention of the sizing agent, and can be reduced The absorbency of the light paper sheet prevents the printing ink from penetrating the paper.
In the late 1990s, the domestic paper industry was made up of acid paper workers. Art shifts to alkaline papermaking, and because of the high quality and low price of calcium carbonate, Gradually replaced the dominant position of talc in the filler market. year 2002 The total consumption of CaCO3 is 1.24 million tons, which exceeds the talcum powder, and the city of talcum powder The market share was 41. 3% fell to 2005 23.5%. It is expected to decline in the next few years [2].
3 talc is used as a functional material
In the paper industry, low and mid-grade talcum powder will still be an important filling Material use, while high-grade talcum powder is mainly used as a function due to its high price. Use of sexual materials. Such as: resin adsorbent, waste paper deinking aids, etc. This side The United States has the largest consumption and its potential market demand is large.
The main component of talcum powder is MgO·SiO2, special for talcum powder. The layered crystal structure gives its surface hydrophobic and oleophilic properties. In addition, slip In addition to the surface tension of stone powder and water, glycerin, formic acid, aniline, etc. In addition to the contact angle, the contact angle with most other substances is 0 in any direction, so it is easy to adsorb organic matter.
The application of talc in resin control began in the 20th century generation. At present, talc powder has been used throughout the control of resins and stickies. world. More than 300,000 tons per year is consumed in this use, this use The amount is still increasing. The principle is: the surface of the talc powder is lipophilic and capable of Adsorb the resin and add it to the slurry to make the new free polymer The collected film-like resin is adsorbed onto its flat surface to lower the resin Apparent energy, causing the resin to lose its characteristic viscosity, thereby inhibiting the resin Adhesion, coalescence and deposition.
The purity, particle size and concentration of talc and control resin deposition Great relationship. The higher the purity, the more likely the layer peeling will occur, the lipophilic table The more faces, the better the effect. The smaller the particle size, the larger the specific surface, the surface energy The larger it is, the greater its adsorption capacity. Increased concentration, talc adsorption The amount of the resin increases linearly. Generally used to control resin deposition Fine talcum powder (high quality talc with a fineness of not less than 800 mesh) The sheet-like thin layer structure has an adsorption resin efficiency of more than 90%.
The mechanism of action of talc in deinking of waste paper is when waste paper is taken off When the ink is treated, talc powder can be used to adsorb ink and other organic substances. In the process of flotation deinking, talc can accumulate in the week of foam and ink Encircle and then pass the screening and purification to make ink and organic matter with talcum powder Separate together from the fiber.
4 talcum powder used as coating pigment
The use of talc in the paper industry has a long history, 20 Talc powder was first used as a filler in the early 2000s. With the technology of the paper industry Development, talc was introduced as a coating pigment in Finland and France in 1982 Into the industrial trial. Thereafter, talcum powder is applied as a furnish to the gravure LWC paper, coated without mechanical wood pulp paper (matte and matt coated paper) and Special coated paper (wallpaper and label paper).
As can be seen from Figures 2 and 3, the kaolin and talc particles are in the form of flakes. Flaky pigments give the coating good fiber coverage and high smoothness Degree; due to the orderly arrangement of pigment particles in the coating, the coating structure is dense In fact, it can improve the printing gloss and reduce the coating air permeability.
Because talc has a large form ratio and its particularity, there are foreign countries. Research shows that high quality talc processed products can be large or full Instead of water-selected kaolin for coating pigments, it produces medium and high-grade coated paper.
4.1 The main advantage of talc as a coating pigment [3]
Talc powder improves whiteness, opacity, smoothness and printing of coated paper Brush gloss gives the paper a high ink absorption.
As a high aspect ratio coating pigment, talc has excellent fiber Dimensional coverage and good printing results can also improve gravure printing quality the amount.
Used in combination with kaolin to change the rheology of the coating and shear thinning The pseudoplastic flow. A coating capable of formulating a high solid content, the coating The material has good rheology and stability.
Talc particles have a soft, multi-layered and low coefficient of friction Sex, which reduces friction and improves abrasion resistance, which improves matt Ink wear problem of coated paper (in the process of printing, paper The mutual friction between the self-weight and the paper causes stress on the surface. Use, which will abrade the surface ink layer of the print), thereby improving printing Quality of the product; the low friction factor of the talc makes the paper layer easier to slide and reduce The breakage of the paper core ensures that the gravure paper roll has good winding quality and can be modified. Good printing machine running performance.
Talc has special lubricity, and coated paper made of it High finish on the calender and reduced lubricant in the paint Dosage.
Low hardness and low wear are beneficial for blade coating.
4.2 The main disadvantages of talcum powder
Because of its hydrophobicity, talc is difficult to wet when preparing coatings. Dispersed, the resulting coating is also shear expandable.
The application of talcum powder in offset printing coated paper is easy to cause ink Pile up and paper lint and powder.
4.3 Indirect causes of talc powder used as coating pigments in China are not popular Domestic gravure printing has not yet become popular.
Since the 1990s, the development and utilization of talc has been mainly based on rough processing. Production-oriented, a small number of enterprises engaged in ultra-fine powder processing, surface modification and modification complex The deep processing is still basically not started, and the overall processing technology is backward [4]. Therefore, the quality of the coated grade talc is poor.
In recent years, due to the expansion of talc application, high grade slippage The price of stone is rising.
Domestic high-quality kaolin resources are few, and most of them are stick-shaped (not Suitable for coating), most of the flaky kaolin for coating is imported from abroad. The price is higher; domestic talcum powder is rich in resources, although talcum powder and kaolin Soil differs in their ease of use and effectiveness, but their use Basically, they can be replaced if they are partially replaced with domestic talcum powder. Imported kaolin produces coated paper, which not only saves resources, but also satisfies coating The different needs of cloth printing paper performance.
5 Development trend of talc in the paper industry
The unique properties of talc determine its uniqueness in the papermaking field. status.
From the perspective of future papermaking prospects, low-grade talcum powder will still be made Used for important fillers, while high quality talcum powder will perform as it should The most economical and technical value of the functional characteristics is in specialty papers, Resin and adhesive adsorbents and paper coating pigments. Application of modified talcum powder: surface treatment of talc powder Cationization, which can improve its adsorption, such as better adsorption of papermaking process Anionic garbage produced in the middle. Development and application of high calcium content talc: whiteness more than 95%, available For SC paper, newsprint and paper coatings. Relevant information indicates that it is used for filling It has better opacity, whiteness and better than single use of GCC. Filler retention also reduces anionic deposits. Can also be used in papermaking Coatings to improve whiteness, smoothness, printability and coating of paper coatings Water retention.
Development of black talc: After calcination, the whiteness can be reached More than 94%, changing its original hydrophobicity, making the pigments better Compatibility. Can be used in paper fillers and coatings instead of some TiO2 and Calcined kaolin.
1 talc structure and its special properties
Talc powder is hydrated magnesium silicate, and its theoretical molecular formula is 3MgO· 4SiO2·H2O. It has a layered structure and is divided into three layers with an eight in the middle. The MgO layer of the facet is a tetrahedral layer of silica [1]; talcum powder The two -OH groups are inside and, therefore, the surface is hydrophobic. This is slippery Stone powder has different properties from other pigments.
Talc has its unique properties: layered structure: interlayer of talcum powder Van der Waals' weak force makes it easy to crack into a thin layer during grinding; hydrophobicity (pro Oily): the lower surface energy, the organic matter is easily adsorbed to its layered surface On the surface, in the production of colored paper, the addition of talc reduces the dye Consumption, effectively saving costs, in addition, its surface lipophilicity makes it Can be used as a resin, adhesive control agent and waste paper deinking agent; softness: make The surface of the coating is smooth and compliant, which reduces the breakage of the coating and reduces the printing pressure. Force, etc.; lower friction factor: can reduce the equipment (forming mesh, scraper and Printing machine) to abrade, thereby extending its service life; chemical inertness: not with Any chemical reaction is not affected by any other additives, and other The coating composition has good compatibility, which means that the pH value does not change. Sensitive, this chemical inertness also makes it environmentally friendly.
2 talc powder used as paper filler
In the early 1990s, the main use of talc in the papermaking field The technical significance is still filler, accounting for 60% of the total national talc consumption. right.
Talc powder has high whiteness, high density and high refractive index. Industry's fillers have the advantage of being chemically stable, not only suitable for acid strips Under the condition of papermaking, it can also be used with calcium carbonate to make paper under neutral conditions; Its friction coefficient is small (less than calcium carbonate), which can extend the paper making network Life expectancy, also suitable for high speed paper machine; it is flaky particles, which is beneficial to Preserving and improving paper opacity, smoothness and printability in the paper; The surface is lipophilic and can adsorb organic matter in the same way as a filler. At the same time, I also received the effect of removing the resin barrier, which helped in the deinking of waste paper. In the removal of ink, this is unmatched by kaolin and calcium carbonate fillers. Can be combined with a sizing agent to improve the retention of the sizing agent, and can be reduced The absorbency of the light paper sheet prevents the printing ink from penetrating the paper.
In the late 1990s, the domestic paper industry was made up of acid paper workers. Art shifts to alkaline papermaking, and because of the high quality and low price of calcium carbonate, Gradually replaced the dominant position of talc in the filler market. year 2002 The total consumption of CaCO3 is 1.24 million tons, which exceeds the talcum powder, and the city of talcum powder The market share was 41. 3% fell to 2005 23.5%. It is expected to decline in the next few years [2].
3 talc is used as a functional material
In the paper industry, low and mid-grade talcum powder will still be an important filling Material use, while high-grade talcum powder is mainly used as a function due to its high price. Use of sexual materials. Such as: resin adsorbent, waste paper deinking aids, etc. This side The United States has the largest consumption and its potential market demand is large.
The main component of talcum powder is MgO·SiO2, special for talcum powder. The layered crystal structure gives its surface hydrophobic and oleophilic properties. In addition, slip In addition to the surface tension of stone powder and water, glycerin, formic acid, aniline, etc. In addition to the contact angle, the contact angle with most other substances is 0 in any direction, so it is easy to adsorb organic matter.
The application of talc in resin control began in the 20th century generation. At present, talc powder has been used throughout the control of resins and stickies. world. More than 300,000 tons per year is consumed in this use, this use The amount is still increasing. The principle is: the surface of the talc powder is lipophilic and capable of Adsorb the resin and add it to the slurry to make the new free polymer The collected film-like resin is adsorbed onto its flat surface to lower the resin Apparent energy, causing the resin to lose its characteristic viscosity, thereby inhibiting the resin Adhesion, coalescence and deposition.
The purity, particle size and concentration of talc and control resin deposition Great relationship. The higher the purity, the more likely the layer peeling will occur, the lipophilic table The more faces, the better the effect. The smaller the particle size, the larger the specific surface, the surface energy The larger it is, the greater its adsorption capacity. Increased concentration, talc adsorption The amount of the resin increases linearly. Generally used to control resin deposition Fine talcum powder (high quality talc with a fineness of not less than 800 mesh) The sheet-like thin layer structure has an adsorption resin efficiency of more than 90%.
The mechanism of action of talc in deinking of waste paper is when waste paper is taken off When the ink is treated, talc powder can be used to adsorb ink and other organic substances. In the process of flotation deinking, talc can accumulate in the week of foam and ink Encircle and then pass the screening and purification to make ink and organic matter with talcum powder Separate together from the fiber.
4 talcum powder used as coating pigment
The use of talc in the paper industry has a long history, 20 Talc powder was first used as a filler in the early 2000s. With the technology of the paper industry Development, talc was introduced as a coating pigment in Finland and France in 1982 Into the industrial trial. Thereafter, talcum powder is applied as a furnish to the gravure LWC paper, coated without mechanical wood pulp paper (matte and matt coated paper) and Special coated paper (wallpaper and label paper).
As can be seen from Figures 2 and 3, the kaolin and talc particles are in the form of flakes. Flaky pigments give the coating good fiber coverage and high smoothness Degree; due to the orderly arrangement of pigment particles in the coating, the coating structure is dense In fact, it can improve the printing gloss and reduce the coating air permeability.
Because talc has a large form ratio and its particularity, there are foreign countries. Research shows that high quality talc processed products can be large or full Instead of water-selected kaolin for coating pigments, it produces medium and high-grade coated paper.
4.1 The main advantage of talc as a coating pigment [3]
Talc powder improves whiteness, opacity, smoothness and printing of coated paper Brush gloss gives the paper a high ink absorption.
As a high aspect ratio coating pigment, talc has excellent fiber Dimensional coverage and good printing results can also improve gravure printing quality the amount.
Used in combination with kaolin to change the rheology of the coating and shear thinning The pseudoplastic flow. A coating capable of formulating a high solid content, the coating The material has good rheology and stability.
Talc particles have a soft, multi-layered and low coefficient of friction Sex, which reduces friction and improves abrasion resistance, which improves matt Ink wear problem of coated paper (in the process of printing, paper The mutual friction between the self-weight and the paper causes stress on the surface. Use, which will abrade the surface ink layer of the print), thereby improving printing Quality of the product; the low friction factor of the talc makes the paper layer easier to slide and reduce The breakage of the paper core ensures that the gravure paper roll has good winding quality and can be modified. Good printing machine running performance.
Talc has special lubricity, and coated paper made of it High finish on the calender and reduced lubricant in the paint Dosage.
Low hardness and low wear are beneficial for blade coating.
4.2 The main disadvantages of talcum powder
Because of its hydrophobicity, talc is difficult to wet when preparing coatings. Dispersed, the resulting coating is also shear expandable.
The application of talcum powder in offset printing coated paper is easy to cause ink Pile up and paper lint and powder.
4.3 Indirect causes of talc powder used as coating pigments in China are not popular Domestic gravure printing has not yet become popular.
Since the 1990s, the development and utilization of talc has been mainly based on rough processing. Production-oriented, a small number of enterprises engaged in ultra-fine powder processing, surface modification and modification complex The deep processing is still basically not started, and the overall processing technology is backward [4]. Therefore, the quality of the coated grade talc is poor.
In recent years, due to the expansion of talc application, high grade slippage The price of stone is rising.
Domestic high-quality kaolin resources are few, and most of them are stick-shaped (not Suitable for coating), most of the flaky kaolin for coating is imported from abroad. The price is higher; domestic talcum powder is rich in resources, although talcum powder and kaolin Soil differs in their ease of use and effectiveness, but their use Basically, they can be replaced if they are partially replaced with domestic talcum powder. Imported kaolin produces coated paper, which not only saves resources, but also satisfies coating The different needs of cloth printing paper performance.
5 Development trend of talc in the paper industry
The unique properties of talc determine its uniqueness in the papermaking field. status.
From the perspective of future papermaking prospects, low-grade talcum powder will still be made Used for important fillers, while high quality talcum powder will perform as it should The most economical and technical value of the functional characteristics is in specialty papers, Resin and adhesive adsorbents and paper coating pigments. Application of modified talcum powder: surface treatment of talc powder Cationization, which can improve its adsorption, such as better adsorption of papermaking process Anionic garbage produced in the middle. Development and application of high calcium content talc: whiteness more than 95%, available For SC paper, newsprint and paper coatings. Relevant information indicates that it is used for filling It has better opacity, whiteness and better than single use of GCC. Filler retention also reduces anionic deposits. Can also be used in papermaking Coatings to improve whiteness, smoothness, printability and coating of paper coatings Water retention.
Development of black talc: After calcination, the whiteness can be reached More than 94%, changing its original hydrophobicity, making the pigments better Compatibility. Can be used in paper fillers and coatings instead of some TiO2 and Calcined kaolin.
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