Mar 30, 2010
PIGMENTS -Types
PIGMENTS -Types
Pigment ussually divide into some categories : White and colored pigment; metallic pigment; and functional pigment.
White pigments : lithopone and titanium dioxide
Colored pigments : red/yellow - iron oxide, blue/green-phtalocyanine, black-carbon or lamp black.
Metallic pigment : metallic appearance-alluminium flake, pearlescene-titania and surface modified talc
Functional pigments : filler-limestone and clay, UV stabilizer-lithopone and zinc sulfide, conductive ability-nickel/copper/silver powder and barium titanate.
Pigment ussually divide into some categories : White and colored pigment; metallic pigment; and functional pigment.
White pigments : lithopone and titanium dioxide
Colored pigments : red/yellow - iron oxide, blue/green-phtalocyanine, black-carbon or lamp black.
Metallic pigment : metallic appearance-alluminium flake, pearlescene-titania and surface modified talc
Functional pigments : filler-limestone and clay, UV stabilizer-lithopone and zinc sulfide, conductive ability-nickel/copper/silver powder and barium titanate.
Resin - Convertible Binders
Resin - Convertible Binders
1. Oils and Oleoresinous Varnishes
The use of oils in paint formulation has already decline. Their use are limited in certain types of primer for steel and timber (refined linseed oil and linseed stand oil). Oils are often used for preparation of oleoresinous varnishes, specially for oil-modified alkyd resins.
Vegetable oils are classified as drying or nondrying oils.
Drying oils : linseed oil and tung oil will readily dry when exposed to oxygen. Soybean oil is called as semidrying oil, because of not drying quickly. The drying process is oxidative polimerization or auto-oxidation. The oxidation rate is slow but can be accelerated by the addition of driers such as cobalt or lead naphthenates.
Nondrying oils : castor oil and olive oil. The nondrying oil can not be oxidized readily. It can be converted to drying oil by heating (to 280 deg. C) for several hours to break down some of the constituent acids of the oil.
2. Alkyd resins
Alkyd resins are modified with some oils such as soya, linseed, dehydrated castor, and coconut oil.
Alkyds can be made directly from oil (triglyceride), a polyol, or an acid. The percentage of oil that contained in an alkyd will classifies the end use of the alkyd and affects properties such as speed of drying, flexibility, durability, etc.
The resin can be combined with such resins as acrylics, vinyl toluene, silicones, and amino-resins. They are fairly inexpensive and they have a variety of properties. These makes them popular for use in industrial coatings.
3. Polyester resins
Polyester resins are typically used in heat-cured coatings that need to be high in paint solids and low in solvent content. They have extremely good color retention that provides good over-bake protection and very good UV resistance.
4. Acrylic resins
Acrylic resins are very versatile and popular for industrial liquid coatings. It is happen because they provide toughness, good weathering ability, and has good resistance to abrasion and chemical attack.
The resins are the polymers and copolymers of the esters of methacrylic and acrylic acids.
5. Amino resins
They are usually used in baked coatings as cross-linking agents. They are used in proportions up to 50% of the total vehicle binder. They can be used with alkyds, polyesters, epoxies, thermosetting acrylics, phenolics, and other heat reactive resins.
Melamine and urea–formaldehyde are the most common examples of this resin.
6. Epoxy resins
Epoxy resins are have excellent corrosion and chemical resistance. But they tend to fade and chalk when exposed to sunlight (UV). They are used for interior applications or as primer for exterior applications. The epoxy resin is usually cross-linked with melamine or urea resin at high curing temperatures.
7. Urethane resins
Urethane resins are very good in chemical resistance, toughness and abrasion resistance, and exterior durability.
Urethanes are the reaction products of isocyanates with materials that have hydroxyl groups. The isocyanates are can be in many different forms, but the most widely used is Toluene Diisocyanate (TDI). The TDI has a noticeable vapor pressure and has an irritant effect on the mucous membranes and so requires special handling.
1. Oils and Oleoresinous Varnishes
The use of oils in paint formulation has already decline. Their use are limited in certain types of primer for steel and timber (refined linseed oil and linseed stand oil). Oils are often used for preparation of oleoresinous varnishes, specially for oil-modified alkyd resins.
Vegetable oils are classified as drying or nondrying oils.
Drying oils : linseed oil and tung oil will readily dry when exposed to oxygen. Soybean oil is called as semidrying oil, because of not drying quickly. The drying process is oxidative polimerization or auto-oxidation. The oxidation rate is slow but can be accelerated by the addition of driers such as cobalt or lead naphthenates.
Nondrying oils : castor oil and olive oil. The nondrying oil can not be oxidized readily. It can be converted to drying oil by heating (to 280 deg. C) for several hours to break down some of the constituent acids of the oil.
2. Alkyd resins
Alkyd resins are modified with some oils such as soya, linseed, dehydrated castor, and coconut oil.
Alkyds can be made directly from oil (triglyceride), a polyol, or an acid. The percentage of oil that contained in an alkyd will classifies the end use of the alkyd and affects properties such as speed of drying, flexibility, durability, etc.
The resin can be combined with such resins as acrylics, vinyl toluene, silicones, and amino-resins. They are fairly inexpensive and they have a variety of properties. These makes them popular for use in industrial coatings.
3. Polyester resins
Polyester resins are typically used in heat-cured coatings that need to be high in paint solids and low in solvent content. They have extremely good color retention that provides good over-bake protection and very good UV resistance.
4. Acrylic resins
Acrylic resins are very versatile and popular for industrial liquid coatings. It is happen because they provide toughness, good weathering ability, and has good resistance to abrasion and chemical attack.
The resins are the polymers and copolymers of the esters of methacrylic and acrylic acids.
5. Amino resins
They are usually used in baked coatings as cross-linking agents. They are used in proportions up to 50% of the total vehicle binder. They can be used with alkyds, polyesters, epoxies, thermosetting acrylics, phenolics, and other heat reactive resins.
Melamine and urea–formaldehyde are the most common examples of this resin.
6. Epoxy resins
Epoxy resins are have excellent corrosion and chemical resistance. But they tend to fade and chalk when exposed to sunlight (UV). They are used for interior applications or as primer for exterior applications. The epoxy resin is usually cross-linked with melamine or urea resin at high curing temperatures.
7. Urethane resins
Urethane resins are very good in chemical resistance, toughness and abrasion resistance, and exterior durability.
Urethanes are the reaction products of isocyanates with materials that have hydroxyl groups. The isocyanates are can be in many different forms, but the most widely used is Toluene Diisocyanate (TDI). The TDI has a noticeable vapor pressure and has an irritant effect on the mucous membranes and so requires special handling.
Resin - Nonconvertible resins
Resin - Nonconvertible resins
1. Cellulose Ester
Some of the cellulose ester are cellulose acetate, cellulose acetate butyrate (CAB), and cellulose acetate propionate (CAP).
Cellulose acetate is the simplest organic cellulose ester, offers excellent properties in coating films (e.g., flame resistance, high melting point, toughness, and clarity).
2. Nitrocellulose
Nitrocellulose is an outstanding film-forming substance which displays rapid solvent evaporation (short drying time). Nitrocellulose is the common name for the nitration product of cellulose. It is derived from cellulose, a material from plants, and therefore a renewable source. The commercial product is made by reacting cellulose with nitric acid.
Soluble nitrocellulose has a unique combination of properties such as toughness, durability, solubility, gloss, and rapid solvent release. The most important areas of use of nitrocellulose lacquers are for coating wood, metal (e.g., automotive repair), paper, foil (cellophane, aluminum), leather,and textiles and in nail polish.
3. Chlorinated Rubber
Chlorinated rubber (CR) is manufactured by using natural or synthetic rubber such as polyethylene, polypropylene or polyisoprene which is degraded to low molecular mass compounds by mastication or addition of radical formers and dissolved in carbon tetrachloride (CTC). Chlorine contents are typically 64-68 wt %. Chlorine gas is introduced into this solution and reacts with the raw material to form CR. The solution is then introduced into boiling water. The CR is precipitated, and the solvent vaporizes. The CR is separated from water, rinsed, dried and ground to form a white powder which is the saleable product.
The main area of use of chlorinated rubber paints is for underwater coatings on ships. Favorable properties for this application are high water resistance, rapid drying, good mutual adhesion of the individual layers, and the fact that old coats of paint can easily be renewed.
4. Vinyl resins
Vinyl resins are synthesized by polymerization of monomers that contain CH2=CH groups.
Paints and coating materials based on vinyl resins are generally physically drying.
Vinyl resins are include polyolefins, poly(viny1 halides) and vinyl halide copolymers, poly(viny1 esters), poly(viny1 alcohol), poly(viny1 acetals), poly(viny1 ethers), and polystyrene.
1. Cellulose Ester
Some of the cellulose ester are cellulose acetate, cellulose acetate butyrate (CAB), and cellulose acetate propionate (CAP).
Cellulose acetate is the simplest organic cellulose ester, offers excellent properties in coating films (e.g., flame resistance, high melting point, toughness, and clarity).
2. Nitrocellulose
Nitrocellulose is an outstanding film-forming substance which displays rapid solvent evaporation (short drying time). Nitrocellulose is the common name for the nitration product of cellulose. It is derived from cellulose, a material from plants, and therefore a renewable source. The commercial product is made by reacting cellulose with nitric acid.
Soluble nitrocellulose has a unique combination of properties such as toughness, durability, solubility, gloss, and rapid solvent release. The most important areas of use of nitrocellulose lacquers are for coating wood, metal (e.g., automotive repair), paper, foil (cellophane, aluminum), leather,and textiles and in nail polish.
3. Chlorinated Rubber
Chlorinated rubber (CR) is manufactured by using natural or synthetic rubber such as polyethylene, polypropylene or polyisoprene which is degraded to low molecular mass compounds by mastication or addition of radical formers and dissolved in carbon tetrachloride (CTC). Chlorine contents are typically 64-68 wt %. Chlorine gas is introduced into this solution and reacts with the raw material to form CR. The solution is then introduced into boiling water. The CR is precipitated, and the solvent vaporizes. The CR is separated from water, rinsed, dried and ground to form a white powder which is the saleable product.
The main area of use of chlorinated rubber paints is for underwater coatings on ships. Favorable properties for this application are high water resistance, rapid drying, good mutual adhesion of the individual layers, and the fact that old coats of paint can easily be renewed.
4. Vinyl resins
Vinyl resins are synthesized by polymerization of monomers that contain CH2=CH groups.
Paints and coating materials based on vinyl resins are generally physically drying.
Vinyl resins are include polyolefins, poly(viny1 halides) and vinyl halide copolymers, poly(viny1 esters), poly(viny1 alcohol), poly(viny1 acetals), poly(viny1 ethers), and polystyrene.
Mar 25, 2010
Additives
Additives are chemicals that added to paint in small quantities, to achieve special effects.
Typical paint additives may be classified by their effect on the properties of liquid or dry paint. Additives can affect the paint material characteristics and the finished film properties.
Examples of properties that can be adjusted with paint additives include flowability, viscosity, foaming, skinning, pigment dispersion, stability, flexibility, hardness, gloss, UV resistance, fire resistance, bacteria resistance, and etc.
Solvent
A solvent is a pure or mixed liquid that is used to make the paint flowable when it is applied. Solvents are chemical substances that can dissolve, suspend, or extract other materials. Solvents work on the principle of “like dissolves like.” Therefore, a solvent will work if it has similar chemical characteristics to the substance that it is trying to dissolve.
Water is also a solvent, which is described as “inorganic” (not containing carbon). Types of solvent are ester (ethyl acetate, butyl acetate), ketone (acetone, methyl ehtyl ketone, MIBK), alcohol (ethanol, buthanol), aromatic hydrocarbon (toluen, xylene, benzene), aliphatic hydrocarbon (n-hexane, heptane), ether (ethylene glycol monoethyl ether).
Solvents are volatile liquids added to paints to dissolve the binder (the resin component) and to modify the paint viscosity. The solvent must have an evaporation rate that works well in the application environment. Ideally, the solvent should also be nontoxic, of low cost, and have an acceptable odor.
Pigment (Colorant)
Pigments are solid particle that are dispersed in paints to provide characteristics such as, color, opacity, durability, mechanical strength, and corrosion protection for metallic substrates.
Pigments may be inorganic and organic materials.
Organic pigments are used primarily for decorative purposes, while inorganic materials are used for protective properties.
Pigments have to be uniformly dispersed in the binder to provide good appearance. They have to be in suspension or be easy to disperse if it is settle.
Resin (Binder)
The resin is the film-forming component that make the paint. A wide variety of resins are used in paints.
The formulation of a paint material used are influenced by the particular resin or resin combination used. The blend of resin and solvent is sometimes referred to as the paint vehicle.
Paint binders may be referred to as convertible and nonconvertible types.
Convertible paints are materials that are used in an unpolymerized or partially polymerized state and will react (polymerization) to form a solid film after applied to the substrate.
Nonconvertible paints are based on polymerized binders dispersed or dissolved in a thinner or solvent that evaporates after the coating has been applied and make film on the substrate surface.
Convertible binders include oils, oleoresinous varnishes, alkyds, amino resins, epoxy resins, phenolic resins, polyurethane resins, and thermosetting acrylics.
Nonconvertible resins such as cellulose, nitrocellulose, chlorinated rubber, and vinyl resins.
What is Paint??
Paint has been used for art for thousands of years. The oldest civilizations such as the Greeks, Romans, and Egyptians used paint
made with a mixture of mineral pigments (copper, iron, etc.),
beeswax, and resin and then fixed with heat. The caveman use to decorated their cave with the picture of their dailiy activity (like hunting).
In nowadays modern live, paint has lot of function, as protection, decorative, and some special purpose.
As protection, paint will protect the material that its covered by giving insulation or barrier from the environtment (water, chemical, UV, etc.), so the material will not be affected by the environment.
As decorative purpose, paint gives color, gloss, or texture to the product that it is applied.
And some time paint was applied to have some special purpose such as corrosion resistance, insulation, wear resistance, etc.
Paint was made by four component : resin, pigment, solvent, and additive.
made with a mixture of mineral pigments (copper, iron, etc.),
beeswax, and resin and then fixed with heat. The caveman use to decorated their cave with the picture of their dailiy activity (like hunting).
In nowadays modern live, paint has lot of function, as protection, decorative, and some special purpose.
As protection, paint will protect the material that its covered by giving insulation or barrier from the environtment (water, chemical, UV, etc.), so the material will not be affected by the environment.
As decorative purpose, paint gives color, gloss, or texture to the product that it is applied.
And some time paint was applied to have some special purpose such as corrosion resistance, insulation, wear resistance, etc.
Paint was made by four component : resin, pigment, solvent, and additive.
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