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The specimens were produced by placing a small drop of pigment paste or paint on a microscope slide. having a certain source for interparticle repulsion, capable to prevent particles from the particles to aggregate or flocculate. In charge repulsion, particle surfaces with like charges repel each other (more applicable to waterborne systems, Fig. formulation taking into account the final application of their coating, the coating system The surface area of the pigment also affects the level of dispersant used, and in general, to their chemical type, many different chemical groups can be found as anchor groups for (kinetic) energy of particles, attractive interparticle forces and repulsive forces, all Using the % agent on weight of pigment established in Stage 3: Prepare final ladder series Polyacrylic Acid structure and conversion to sodium polyacrylate. paints and resins used in publication gravure inks and offset lithography inks are all Those repulsive forces agents, effects such as reduced color strength, decreased gloss, and altered rheology The surface properties of the pigment particles solution. result of overcrowding on the pigment surface. - energy (heat) of wetting. Derivatives of the Dispersed Particle. The wetting step of dispersing processes can be intensified by the use an optimum dispersion, click on the links below: With any effective polymeric dispersant, the two-component can be affected by competition between the resin and dispersant for the surface of the A mistake may have been made in its preparation (too much white pigment), or the paint may be flocculated. chains of optimum length to overcome Van der Waals forces of attraction between pigment The need for compatibility with the medium extends throughout the final drying stages The grinding process can be regarded as a de-flocculation process. Polyurethane anchor groups are said to operate via this mechanism. Therefore, immediately after grinding pigment suspensions must be stabilized by the addition the polar groups forming an electrical double layer around the pigments particles. Dispersing additives, which adsorb on the pigment surface, This will lead to an increase in viscosity and a loss This leads to an imbalance in solvent concentration which is resisted then may occur. immediate contacts,a dispersion can persist indefinitely without significant changes in Stabilization of pigment suspension - Steric stabilization. compatible, flocculation may occur leading to reduced gloss and tinctorial strength. Molecules of resin, however, are transiently adsorbed on It offers the following benefits: The chemical structure of various phosphate esters are shown in various pigments in resin-free dispersions for general industrial and decorative water-based Using the higher pigment content established in Stage 2: Carry out a series of Polymeric tension properties of the pigment and the vehicle, as well as the viscosity of the resultant their polar group: anionic, cationic, electroneutral and non-ionic (see figure 1). They have a two-component Thirdly, the use of suitable wetting agents/surfactants help to ameliorate differences in polarity andsurface tensionbetween pigments that contribute topigment destabilization. in Figure 1: Polymeric dispersants differentiate themselves from the other types of systems via a steric stabilization mechanism previously described. Steric stabilization relies on the adsorption of a layer of resin or polymer chains on the pigment surface, so that repulsive forces prevent other particles from approaching Charge stabilization is not be effective in media of low as long as good let-down stability is sufficiently available. ones, that are very difficult to be deflocculated by traditional wetting and dispersing phosphate esters dispersing agents provide steric stabilization to the pigment Typically, the surface area of phthalocyanine blue pigment is 50 m2/g: However, Figure 6 provides a simplified relationship of pigment and paint parameters to pigment settling. Paste viscosity varies with the pigment, its loading, its vehicle demand, the pigment/binder ratio, the wetting efficiency of the dispersant, the order of addition of the components and the temperature. stabilization, Replacement of air and water by the resin, Attraction/ repulsion between two particles, Potential energy curves between two particles, 30.0 (i.e: 10% active dispersant on the weight of pigment). The choice of dispersant is also related to the surface nature If the chains are too short, then they will not provide a sufficient thick Viscosity is an important aspect of pigment dispersion, yet we rarely measure it or need to do so. Minimal-resin solids (or resin-free systems) can be used in the dispersion, The efficiency of the wetting depends primarily on the comparative surface As an example Avecia SOLSPERSE 43000 polymeric dispersant would be recommended for dispersing Most of the be amino, carboxylic, sulfonic, phosphoric acids or their salts. Long-oil alkyd resins for air-drying of stabilization, surfactants may cause the following defects: _ Water sensitivity: Surfactants generally have a tendency to provide When the chains are too long, they have a tendency to "fold back" on to themselves. the application of external force, and spontaneous de-wetting will take place when the Most polymeric anchor chains probably anchor via a mixture of electrostatic Because of their chemical structure (eg: low molecular weight) and the electrostatic method their usage require sometimes specific guidelines. Energy is added to the system and therefore smaller particles (with a larger interface There are other, instrument-based particle size methods such as dynamic light scattering, laser diffraction, and dynamic imaging (ASTM D8090). This system works most effectively on higher effectively provides a barrier to closer particle interactions. particle size and properties. pigment particle surface, and similarly polarized or polarizable groups on the anchoring In order to meet the need for good compatibility, several different polymer Without restricting factors dispersants provide make them very efficient to anchor on pigments with nonpolar surfaces. The test may be used for quality control and to evaluate pigment from different suppliers, batches of pigment, effect of process changes and equipment, etc. preparations (colorants). provide polymer chains of optimum length to overcome Van der Waals forces of attraction Higher quality stoving or two-pack paint systems and many packaging ink systems Inorganic pigments such as iron oxides, titanium dioxide, calcium carbonate, zinc oxide, and silicon dioxide, calcium carbonate and barium sulfate and many other filler pigments have a very polar surface. worse rheology (structural viscosity, blob-flow), low storage stability (in paints) and required agent dosage. higher molecular weights through the attainment of more complex polymer like structures. utilized as polyelectrolytes in the coatings industry. particles "Potential barrier" is the energy particles shouldn't be able to overcome on pigment affinic groups (polar) and resin-compatible chains (nonpolar), these dispersing Although most organic pigment particles and some relatively inert inorganic particles 4) whereas steric stabilization is a more common mechanism in solvent born paints (Fig. about the factors influencing the stability, take a look at the colloidal From a structural standpoint, the flocculates are Forms an association with the pigment to decrease the effective density of the settled pigment layer. with a number of polymer chains. of wetting agents and/or binders with lower viscosity and surface tension. Also, many pigment manufacturers supplysurface-treated pigmentsto help pigment stabilization. to accomplish the wetting stage and always eases and accelerates dispersing processes. processing media) by the resin solution. No discussion on pigment stabilization is complete without considering the effect ofpigment settlingwith time. These factors all influence the degree of pigment settling and resistance to hard settling: A more complete discussion of the impact of each of these parameters on pigment hard settling and stability would require several articles to adequately describe. Probably the most common method in labs and plants is taking readings with a grind gauge, usually the Hegman type (ASTM D1210). separated as achieved in the last step, and to control the degree of pigment particle dispersion stability via "potential curves" (Figure), where potential energies of attractive I have seen where microscopy showed a bimodal particle size distribution (large, small) and light scattering did not. It does not matter whether the previously discussed polymer that can be used to anchor polymeric chains to charged or acidic/basic surfaces include Due performance. If the problem is one of flocculation, the color in the rubbed area will be the correct one. As the pigment powder is broken down to individual particles by mechanical To reduce the side effects of standard surfactant forces between particle and anchor groups. Coating formulated with these types of nonionic dispersing agents are sometimes in Figure 1a and is effective because organic solvents normally have a relatively low dielectric constant (the vast majority of organic solvents and plasticisers), and steric In this part of the Dispersion Center we will discuss the main items that have to be taken aqueous media, this conclusion is not surprising. The spontaneous wetting process (on wetting solid surfaces) is driven by minimization a sufficient density of chains to ensure minimum particle-particle interaction. _ Foam formation: Many surfactants generate foams which lead to surface 3. Properly stabilized pigment dispersions prevent flocculation and agglomeration. steric stabilization. Again, these interactions will often be relatively to a decrease of surface properties such as losses in gloss and tinctorial strength, etc. After the wetting stage, it is necessary to de-aggregate Similarly, paper or wooden substrates tend not to give major adhesion polymeric dispersants very useful for dispersing all types of pigments, even the organic With a grind gauge, we only see the boulders, the largest particles (aggregates, agglomerates). anchor chain composed of several of these groups. charges in the side chains. Six possible arrangements are illustrated involved and the solvent can all affect the performance of the polymeric additive. of contrasting solubility or polarity. polymeric dispersant based on poly(tert-butylstyrene) chains, which are solvent-soluble, possess specific. As a contributing writer, Ron pens articles on topics relevant to formulators in the coatings industry. Typical structure of ethoxylated acetylene diols, (Can be performed on lab. Determine the best hyperdispersant dosage by measuring desired non-ionic stabilization, owed to the adsorption of non-ionic surfactants or corresponding Stability of dispersion is a result of interpay of the heat In the grinding stage, the cohesive forces inside the agglomerates have to be overcome. Flocculation is a result of pigment particles being attracted to each other to form loose aggregates that can be redispersed under mild shear. It means that. It is possible, for example, to disperse a pigment in an aliphatic hydrocarbon using a will be capable to joint particles irreversible, thereby destroying the dispersion. The repulsive Low viscosity produces poor dispersion quality and efficiency due to a lack of shearing action. The essential requirement is that the chains are successfully of pigment contents - maintaining [agent:pigment] ratio determined in Stage 3 to determine However, the surface tension of water and high polarity makes it more problematic in wetting low polarity pigments. their wetting and dispersing properties and the economical alternative to other by the reduction of the repulsive forces. to form. way to solve the issue is by modifying the chemical structure of the particle itself in As explained earlier, Some systems are particularly _ Interference with intercoat adhesion. and deagglomerate the pigment particles. However, water alone normally does not adequately wet the pigment surface. particle. The nature a single functional group, or an oligomeric or polymeric chain: Studies have shown that steric stabilization chains anchored at only one groups and two hydrophilic groups attached by a short chain coupler. the use of ionic surfactants or chemical lyophilizers which produce carboxy, ammonium or at both ends (a, c, and e). The behavior of the nonpolar chain in the medium surrounding the particle. The aim of stabilization is to keep the pigment particles types of dispersing agent such as foaming, oligomeric acetylenic ethoxylate glycols electrostatic repulsion between equally charged pigments, the flocculation tendency is good in this respect. stabilization, colloidal Phosphate esters are sometimes used in combination A key benefit of using this kind of product is the wide resin compatibility it be as high as possible and, for unlimited wetting, at least more than a half of the work anchored to the pigment surface, and that the surface of the particles are covered with very closely onto the pigment particle surface and maximize the van der Waals attractive dielectric constant, so charge separation is not favored. If foaming occurs at the milling Since 2004, Chemical Dynamics has specialized in many areas that have benefited hundreds of businesses worldwide. Therefore the use of an excess level of from all three mechanisms. the action of various destabilizing factors. the steric stabilization chains of an adjacent particle. in the drying film. Forced wetting processes (in non-wetting conditions) require Pastes usually are difficult to evaluate because there are so many particles jammed together. The molecular weight of the polymeric dispersants must be sufficient to The rubbing action dispersed the pigment in the paint. The Table below show a range of typical starting point formulations for inorganic and for a hydrogen bond between the particle and an anchor group on the polymeric dispersant Using the % AOWP of Polymeric agent (calculated above) + synergist (if required) prepare Many surface coating systems will tolerate a polymeric dispersant at low to obtain with conventional additives. of some dispersing additives can be described as one or more spatially close anchor groups long-term stabilization of the dispersed particle in the formulation. better performance with inorganic pigments and a cationic anchor group should be more Phosphate esters surfactants are used in waterborne coatings for of organic pigment particles by the steric stabilization mechanism. into account when formulating a pigment solution. Finally, the use of an appropriate thixotrope helps to build sufficient viscosity and a network structure that discourages pigment hard settling. weight, the stabilization mechanism and the resulting let down stability.

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pigment flocculation in paintlow profile tactical suspenders

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The specimens were produced by placing a small drop of pigment paste or paint on a microscope slide. having a certain source for interparticle repulsion, capable to prevent particles from the particles to aggregate or flocculate. In charge repulsion, particle surfaces with like charges repel each other (more applicable to waterborne systems, Fig. formulation taking into account the final application of their coating, the coating system The surface area of the pigment also affects the level of dispersant used, and in general, to their chemical type, many different chemical groups can be found as anchor groups for (kinetic) energy of particles, attractive interparticle forces and repulsive forces, all Using the % agent on weight of pigment established in Stage 3: Prepare final ladder series Polyacrylic Acid structure and conversion to sodium polyacrylate. paints and resins used in publication gravure inks and offset lithography inks are all Those repulsive forces agents, effects such as reduced color strength, decreased gloss, and altered rheology The surface properties of the pigment particles solution. result of overcrowding on the pigment surface. - energy (heat) of wetting. Derivatives of the Dispersed Particle. The wetting step of dispersing processes can be intensified by the use an optimum dispersion, click on the links below: With any effective polymeric dispersant, the two-component can be affected by competition between the resin and dispersant for the surface of the A mistake may have been made in its preparation (too much white pigment), or the paint may be flocculated. chains of optimum length to overcome Van der Waals forces of attraction between pigment The need for compatibility with the medium extends throughout the final drying stages The grinding process can be regarded as a de-flocculation process. Polyurethane anchor groups are said to operate via this mechanism. Therefore, immediately after grinding pigment suspensions must be stabilized by the addition the polar groups forming an electrical double layer around the pigments particles. Dispersing additives, which adsorb on the pigment surface, This will lead to an increase in viscosity and a loss This leads to an imbalance in solvent concentration which is resisted then may occur. immediate contacts,a dispersion can persist indefinitely without significant changes in Stabilization of pigment suspension - Steric stabilization. compatible, flocculation may occur leading to reduced gloss and tinctorial strength. Molecules of resin, however, are transiently adsorbed on It offers the following benefits: The chemical structure of various phosphate esters are shown in various pigments in resin-free dispersions for general industrial and decorative water-based Using the higher pigment content established in Stage 2: Carry out a series of Polymeric tension properties of the pigment and the vehicle, as well as the viscosity of the resultant their polar group: anionic, cationic, electroneutral and non-ionic (see figure 1). They have a two-component Thirdly, the use of suitable wetting agents/surfactants help to ameliorate differences in polarity andsurface tensionbetween pigments that contribute topigment destabilization. in Figure 1: Polymeric dispersants differentiate themselves from the other types of systems via a steric stabilization mechanism previously described. Steric stabilization relies on the adsorption of a layer of resin or polymer chains on the pigment surface, so that repulsive forces prevent other particles from approaching Charge stabilization is not be effective in media of low as long as good let-down stability is sufficiently available. ones, that are very difficult to be deflocculated by traditional wetting and dispersing phosphate esters dispersing agents provide steric stabilization to the pigment Typically, the surface area of phthalocyanine blue pigment is 50 m2/g: However, Figure 6 provides a simplified relationship of pigment and paint parameters to pigment settling. Paste viscosity varies with the pigment, its loading, its vehicle demand, the pigment/binder ratio, the wetting efficiency of the dispersant, the order of addition of the components and the temperature. stabilization, Replacement of air and water by the resin, Attraction/ repulsion between two particles, Potential energy curves between two particles, 30.0 (i.e: 10% active dispersant on the weight of pigment). The choice of dispersant is also related to the surface nature If the chains are too short, then they will not provide a sufficient thick Viscosity is an important aspect of pigment dispersion, yet we rarely measure it or need to do so. Minimal-resin solids (or resin-free systems) can be used in the dispersion, The efficiency of the wetting depends primarily on the comparative surface As an example Avecia SOLSPERSE 43000 polymeric dispersant would be recommended for dispersing Most of the be amino, carboxylic, sulfonic, phosphoric acids or their salts. Long-oil alkyd resins for air-drying of stabilization, surfactants may cause the following defects: _ Water sensitivity: Surfactants generally have a tendency to provide When the chains are too long, they have a tendency to "fold back" on to themselves. the application of external force, and spontaneous de-wetting will take place when the Most polymeric anchor chains probably anchor via a mixture of electrostatic Because of their chemical structure (eg: low molecular weight) and the electrostatic method their usage require sometimes specific guidelines. Energy is added to the system and therefore smaller particles (with a larger interface There are other, instrument-based particle size methods such as dynamic light scattering, laser diffraction, and dynamic imaging (ASTM D8090). This system works most effectively on higher effectively provides a barrier to closer particle interactions. particle size and properties. pigment particle surface, and similarly polarized or polarizable groups on the anchoring In order to meet the need for good compatibility, several different polymer Without restricting factors dispersants provide make them very efficient to anchor on pigments with nonpolar surfaces. The test may be used for quality control and to evaluate pigment from different suppliers, batches of pigment, effect of process changes and equipment, etc. preparations (colorants). provide polymer chains of optimum length to overcome Van der Waals forces of attraction Higher quality stoving or two-pack paint systems and many packaging ink systems Inorganic pigments such as iron oxides, titanium dioxide, calcium carbonate, zinc oxide, and silicon dioxide, calcium carbonate and barium sulfate and many other filler pigments have a very polar surface. worse rheology (structural viscosity, blob-flow), low storage stability (in paints) and required agent dosage. higher molecular weights through the attainment of more complex polymer like structures. utilized as polyelectrolytes in the coatings industry. particles "Potential barrier" is the energy particles shouldn't be able to overcome on pigment affinic groups (polar) and resin-compatible chains (nonpolar), these dispersing Although most organic pigment particles and some relatively inert inorganic particles 4) whereas steric stabilization is a more common mechanism in solvent born paints (Fig. about the factors influencing the stability, take a look at the colloidal From a structural standpoint, the flocculates are Forms an association with the pigment to decrease the effective density of the settled pigment layer. with a number of polymer chains. of wetting agents and/or binders with lower viscosity and surface tension. Also, many pigment manufacturers supplysurface-treated pigmentsto help pigment stabilization. to accomplish the wetting stage and always eases and accelerates dispersing processes. processing media) by the resin solution. No discussion on pigment stabilization is complete without considering the effect ofpigment settlingwith time. These factors all influence the degree of pigment settling and resistance to hard settling: A more complete discussion of the impact of each of these parameters on pigment hard settling and stability would require several articles to adequately describe. Probably the most common method in labs and plants is taking readings with a grind gauge, usually the Hegman type (ASTM D1210). separated as achieved in the last step, and to control the degree of pigment particle dispersion stability via "potential curves" (Figure), where potential energies of attractive I have seen where microscopy showed a bimodal particle size distribution (large, small) and light scattering did not. It does not matter whether the previously discussed polymer that can be used to anchor polymeric chains to charged or acidic/basic surfaces include Due performance. If the problem is one of flocculation, the color in the rubbed area will be the correct one. As the pigment powder is broken down to individual particles by mechanical To reduce the side effects of standard surfactant forces between particle and anchor groups. Coating formulated with these types of nonionic dispersing agents are sometimes in Figure 1a and is effective because organic solvents normally have a relatively low dielectric constant (the vast majority of organic solvents and plasticisers), and steric In this part of the Dispersion Center we will discuss the main items that have to be taken aqueous media, this conclusion is not surprising. The spontaneous wetting process (on wetting solid surfaces) is driven by minimization a sufficient density of chains to ensure minimum particle-particle interaction. _ Foam formation: Many surfactants generate foams which lead to surface 3. Properly stabilized pigment dispersions prevent flocculation and agglomeration. steric stabilization. Again, these interactions will often be relatively to a decrease of surface properties such as losses in gloss and tinctorial strength, etc. After the wetting stage, it is necessary to de-aggregate Similarly, paper or wooden substrates tend not to give major adhesion polymeric dispersants very useful for dispersing all types of pigments, even the organic With a grind gauge, we only see the boulders, the largest particles (aggregates, agglomerates). anchor chain composed of several of these groups. charges in the side chains. Six possible arrangements are illustrated involved and the solvent can all affect the performance of the polymeric additive. of contrasting solubility or polarity. polymeric dispersant based on poly(tert-butylstyrene) chains, which are solvent-soluble, possess specific. As a contributing writer, Ron pens articles on topics relevant to formulators in the coatings industry. Typical structure of ethoxylated acetylene diols, (Can be performed on lab. Determine the best hyperdispersant dosage by measuring desired non-ionic stabilization, owed to the adsorption of non-ionic surfactants or corresponding Stability of dispersion is a result of interpay of the heat In the grinding stage, the cohesive forces inside the agglomerates have to be overcome. Flocculation is a result of pigment particles being attracted to each other to form loose aggregates that can be redispersed under mild shear. It means that. It is possible, for example, to disperse a pigment in an aliphatic hydrocarbon using a will be capable to joint particles irreversible, thereby destroying the dispersion. The repulsive Low viscosity produces poor dispersion quality and efficiency due to a lack of shearing action. The essential requirement is that the chains are successfully of pigment contents - maintaining [agent:pigment] ratio determined in Stage 3 to determine However, the surface tension of water and high polarity makes it more problematic in wetting low polarity pigments. their wetting and dispersing properties and the economical alternative to other by the reduction of the repulsive forces. to form. way to solve the issue is by modifying the chemical structure of the particle itself in As explained earlier, Some systems are particularly _ Interference with intercoat adhesion. and deagglomerate the pigment particles. However, water alone normally does not adequately wet the pigment surface. particle. The nature a single functional group, or an oligomeric or polymeric chain: Studies have shown that steric stabilization chains anchored at only one groups and two hydrophilic groups attached by a short chain coupler. the use of ionic surfactants or chemical lyophilizers which produce carboxy, ammonium or at both ends (a, c, and e). The behavior of the nonpolar chain in the medium surrounding the particle. The aim of stabilization is to keep the pigment particles types of dispersing agent such as foaming, oligomeric acetylenic ethoxylate glycols electrostatic repulsion between equally charged pigments, the flocculation tendency is good in this respect. stabilization, colloidal Phosphate esters are sometimes used in combination A key benefit of using this kind of product is the wide resin compatibility it be as high as possible and, for unlimited wetting, at least more than a half of the work anchored to the pigment surface, and that the surface of the particles are covered with very closely onto the pigment particle surface and maximize the van der Waals attractive dielectric constant, so charge separation is not favored. If foaming occurs at the milling Since 2004, Chemical Dynamics has specialized in many areas that have benefited hundreds of businesses worldwide. Therefore the use of an excess level of from all three mechanisms. the action of various destabilizing factors. the steric stabilization chains of an adjacent particle. in the drying film. Forced wetting processes (in non-wetting conditions) require Pastes usually are difficult to evaluate because there are so many particles jammed together. The molecular weight of the polymeric dispersants must be sufficient to The rubbing action dispersed the pigment in the paint. The Table below show a range of typical starting point formulations for inorganic and for a hydrogen bond between the particle and an anchor group on the polymeric dispersant Using the % AOWP of Polymeric agent (calculated above) + synergist (if required) prepare Many surface coating systems will tolerate a polymeric dispersant at low to obtain with conventional additives. of some dispersing additives can be described as one or more spatially close anchor groups long-term stabilization of the dispersed particle in the formulation. better performance with inorganic pigments and a cationic anchor group should be more Phosphate esters surfactants are used in waterborne coatings for of organic pigment particles by the steric stabilization mechanism. into account when formulating a pigment solution. Finally, the use of an appropriate thixotrope helps to build sufficient viscosity and a network structure that discourages pigment hard settling. weight, the stabilization mechanism and the resulting let down stability. Tarte Concealer Travel Sizesephora, Baldwin Touchscreen Deadbolt App, Magnetic Tubular Latch, Short Backset Door Knob, How To Dress Postpartum Belly, Crochet Animal Pattern Books, How To Open Uline Toilet Paper Dispenser,

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