You might not think much about solvents, but these invisible ingredients are the unsung heroes of the coating world. They’re the key to creating smooth, durable, and beautiful finishes on everything from cars and furniture to buildings and bridges. But how do solvents work, and why are they so important?
The Magic of Solvents: Dissolving, Blending, and Enhancing
Imagine a world where paint was thick and gooey, impossible to apply evenly. That’s where solvents come in. These special liquids act like magic potions, dissolving resins and other coating ingredients, reducing viscosity, and creating a smooth, workable consistency. But solvents do more than just make coatings easier to apply; they also play a crucial role in enhancing their performance.
The Right Solvent for the Right Job: Tailoring Coatings for Success
Just like choosing the right ingredients for a recipe, selecting the right solvent is crucial for achieving the desired results. Different solvents have different properties, and the choice depends on the specific coating application and the desired performance characteristics. For example, some solvents are better at dissolving certain types of resins, while others enhance adhesion, corrosion resistance, or outdoor durability.
The Solvents You Need to Know: A Guide to the Coating World
The world of solvents is vast and diverse, with each type offering unique properties and applications. Here’s a quick rundown of some common solvents used in coatings:
- Aliphatic Hydrocarbons: These solvents are known for their fast evaporation rates and are often used in paints and varnishes.
- Aromatic Hydrocarbons: These solvents are powerful dissolvers and are commonly used in high-performance coatings.
- Chlorinated Hydrocarbons: These solvents offer excellent adhesion and durability but are facing increasing scrutiny due to their environmental impact.
- Alcohols: These solvents are versatile and are used in a wide range of coatings, including paints, varnishes, and stains.
- Esters: These solvents are known for their slow evaporation rates and are often used in coatings that require a long drying time.
- Ketones: These solvents are powerful dissolvers and are used in high-performance coatings and adhesives.
The Takeaway: Solvents, the Unsung Heroes of the Coating World
Solvents are essential components of coatings, playing a crucial role in their performance, durability, and appearance. Choosing the right solvent is essential for achieving the desired results, and understanding the properties and applications of different solvents is key to creating high-quality coatings. So, next time you admire a beautifully finished surface, remember that solvents might be the hidden heroes behind the magic.
Solvent is an important component in coating formulations. It is not only used to dissolve resin and reduce viscosity to improve processing performance, but also affects the adhesion, anti-corrosion, outdoor durability and appearance of the coating film, such as blistering, Sagging, leveling, etc. Certain properties of coatings can be improved through solvent selection.
Commonly used solvents for coatings
Aliphatic hydrocarbons
Aliphatic hydrocarbons, naphtha, gasoline and chain alkanes, as a class of inert substances in the chemical field, exhibit extremely high stability and are ideal solvents. These solvents have excellent solubility for a wide range of substances, including mineral oils, fatty oils (except castor oil), waxes and similar chain alkanes. In addition, they can effectively dissolve polymer materials such as rubber, polyisobutylene, molten polyethylene, polyacrylate 5, polymethacrylate and polyvinyl ether. However, for most polar resins and cellulose derivatives, their solubility is relatively limited.
In the subdivision of aliphatic hydrocarbons, based on different boiling point ranges, they can be further divided into three categories: special boiling point hydrocarbons, petroleum ether and No. 200 solvent oil. Special boiling point hydrocarbons are widely used in the manufacture of quick-drying paints, impregnating paints and quick-drying adhesives due to their low flash point (less than 21°C). However, special attention must be paid to their safe use in explosion-proof areas. Petroleum ether, as a specific component in the petroleum distillation process, has a boiling point between 40 and 60°C. It is one of the commonly used solvents in the chemical industry. No. 200 solvent oil occupies an important position in the coating industry due to its wide applicability. It is often used as a solvent or diluent to optimize oil-based paints, alkyd resin paints, chlorinated rubber coatings and vinyl chloride copolymers. properties of physical coatings.
As for naphtha specially used for coatings, its boiling point range is set at 100 to 150°C. Its main function is as a diluent, which plays a key role in the coating preparation process and improves the uniformity and construction performance of the coating.
Alicyclic hydrocarbons
Alicyclic hydrocarbons show a unique intermediate state in terms of solubility, which is neither as widespread as aliphatic hydrocarbons nor as powerful as aromatic hydrocarbons. They exhibit excellent solubility properties for fats, oils, oil-modified alkyd resins, styrene-modified oils, and copolymer materials such as alkyd resins, asphalt, and rubber. However, when faced with polar resins (such as urea-formaldehyde, melamine formaldehyde, phenolic resin, etc.), alcohol-soluble synthetic resins and cellulose esters, alicyclic hydrocarbons are unable to effectively dissolve. Alicyclic hydrocarbons are well miscible with most solvents, but are insoluble in water. There are several common alicyclic hydrocarbons:
cyclohexane
It is a colorless and transparent liquid with a gasoline smell that is easily miscible with most organic solvents, but is incompatible with solvents of similar polarity such as methanol and dimethylformamide.
Methylcyclohexane
Its properties are similar to cyclohexane, but its volatility is slightly milder, providing users with a more stable operating environment.
1,2,3,4-Tetralin
It is a colorless liquid with a unique odor similar to naphthalene. It is also insoluble in water, but can be easily miscible with all conventional organic solvents. It plays an important role in the production of coatings, floor waxes and shoe polishes, imparting superior properties to products by dissolving fats, oils, oxidized linseed oil, rubber, wax, asphalt and other materials. In addition, it can effectively dissolve various resins such as rosin, Congo gum, and alkyd resin to improve the fluidity and gloss of the paint. It is worth noting that 1,2,3,4-tetralin has autoxidative properties and plays a key role as an oxygen carrier in dry oil.
Decalin
As a colorless solvent, its pungent odor and high volatility are noticeable. Although its solubility is slightly inferior to tetralin, it still shows value that cannot be ignored in a variety of applications.
Aromatic hydrocarbons
Compared with aliphatic hydrocarbons, aromatic hydrocarbon solvents exhibit stronger dissolving capabilities for a variety of materials, including but not limited to oils, castor oil, oil-modified alkyd resins, styrene-modified oils and alkyd resins , saturated polyester resin, polystyrene, polyvinyl ether, polyacrylate and polymethacrylate series, polyvinyl acetate, and copolymers of vinyl chloride and vinyl acetate and other low-polarity resins. In applications, aromatic hydrocarbons are often used as diluents in nitrocellulose solutions, cellulose esters and ether solutions, acting synergistically with true solvents esters and ketones. At the same time, they can also effectively dissolve rubber, polyisobutylene and molten polyethylene, but have limited solubility in materials such as polyvinyl chloride, solid polyethylene, polyamide and shellac, or can only produce a swelling effect. There are several common aromatic hydrocarbons:
Toluene
Toluene is widely used in nitrocellulose paints, heat-curing paints based on urea-formaldehyde resins, melamine-formaldehyde resins or phenolic resins, alkyd resin paints and chlorinated rubber paints. It also has high dissolving power for materials such as polystyrene, polyacrylate or polyvinyl acetate. In addition, the use of toluene and ester mixtures can effectively dissolve vinyl chloride copolymers and post-chlorinated polyvinyl chloride.
xylene
It usually contains a trace amount of toluene and a large amount of vinylbenzene. It plays an important role in the coating industry and is one of the indispensable aromatic hydrocarbon solvents. It is worth noting that xylene alone is difficult to dissolve polyvinyl acetate and needs to be used in conjunction with alcohols or glycol ethers. Otherwise, its solubility characteristics are similar to toluene.
Ethylbenzene
It has a transparent appearance, has a characteristic odor, and is miscible with a variety of organic solvents, but is incompatible with water. Although its use as a solvent in the coatings industry is relatively limited, ethylbenzene plays a key industrial starting material role in the catalytic dehydrogenation to styrene. In addition, through catalytic oxidation reactions, ethylbenzene can also be converted into products such as acetophenone and methylphenylcarbitol, and can help improve the shock-absorbing performance of four-stroke engine fuel.
Styrene
As a colorless liquid, it is mainly used to dissolve unsaturated polyester resin. Due to the risk of polymerization during storage, stabilizers need to be added to ensure safe storage. Styrene is not only an important raw material for the synthesis of various polymers and copolymers, but is also widely used in the manufacture of styrene-modified alkyd resins and oil products.
Terpene hydrocarbons and terpenoids
turpentine
Essence derived from the distillation of pine resin, the composition of which varies from region to region. Turpentine from North America and Greece is rich in D-pinene, while turpentine from France, Spain and Portugal is mainly L-pinene. Domestic turpentine cleverly combines 60% to 65% α-pinene and 30% to 38% β-pinene to form its unique composition. Gum turpentine is a liquid with high fluidity and a unique smell. After long-term storage, its boiling point will decrease and it will gradually become resinous. This solvent shows excellent solubility for fats, greases, waxes and hydrocarbon resins, and its solubility even exceeds that of No. 200 solvent naphtha, so it is also commonly used in the formulation of oil-based and alkyd resin paints.
Tung oil
It is a yellow acidic liquid known for its characteristic unpleasant odor. Although exposure to air or purification can lighten its color, its odor becomes increasingly pungent. Therefore, tung oil is more suitable as an exclusive solvent for dark paints and varnishes.
wood turpentine
Its properties are similar to sulfated turpentine in the production process of wood pulp. In particular, its high boiling point component is rich in terpineol. This part is specially called “pine oil” and is an indispensable high boiling point solvent in baking enamel. Wood turpentine itself is colorless and transparent, and is quite similar to gum turpentine in many properties.
Through the distillation process of turpentine we gain access to valuable terpenes. Among them, α-pinene is the key raw material for preparing camphor. Hydrogenated terpine is the product of the hydration reaction of pine oil and is often used as a substitute for turpentine. In oil-based and alkyd paints, terpenoids also play an important role as high-boiling solvents. It is worth mentioning that the application of dipentene in air-drying paint can effectively prevent coating skinning and improve the overall performance of the coating.
Chlorinated hydrocarbons
For most resins, polymers, rubbers, waxes, asphalts, etc., chlorinated hydrocarbons have greater solubility than their corresponding non-chlorinated compounds. Chlorinated hydrocarbons have a sweet taste and are compatible with other organic solvents but insoluble in water. Increasing the number of chlorine substitutions can reduce flammability and improve solubility, but will increase toxicity.
All chlorinated hydrocarbons will degrade under the influence of light, air, heat and water. Adding stabilizers can slow down the degradation but cannot completely prevent it. Due to their harm to human health, some chlorinated hydrocarbons can no longer be used as general solvents, such as carbon tetrachloride, tetrachloroethylene, and pentachloroethane. Due to water pollution, methylene chloride, trichlorethylene, perchlorethylene and 1,1,1-trichloroethane are gradually being replaced as industrial hygiene and environmental protection are promoted.
Dichloromethane
Colorless, highly volatile neutral liquid with a special odor, insoluble in water, but miscible with organic solvents. It has good solubility for many organic substances, such as fats, oils, waxes and resins. It dissolves asphalt, rubber, chlorinated rubber, polystyrene, post-chlorinated polyvinyl chloride, vinyl copolymers, polyacrylates, cellulose esters. Adding other solvents can extend its solubility. Methanol or mixtures of ethanol and methylene chloride are good solvents for cellulose ethers and acetyl cellulose, but they do not dissolve nitrocellulose. Methylene chloride is a component of paint strippers, but is gradually being replaced by water-based systems. It is also used as a solvent in the production of cellulose acetate films, leather, metal, rubber, adhesives and plastics.
Chloroform
Has a strong anesthetic effect and is not widely used.
1,2-Dichloroethane
It is one of the most stable chlorinated hydrocarbons and has good solubility for fats, oils, resins, rubber, asphalt and tar asphalt. Highly toxic, the olfactory threshold is higher than the MAK value. 1,2-Dichloroethane is used in the production of building protective agents, roofing felt and cold asphalt.
1,1,2,2-Tetrachloroethane
It is a good solvent for resin, rubber and cellulose acetate. Due to its potential health hazards, there are certain limits on its use.
1,1,1-Trichloroethane
Insoluble in water, but miscible with organic solvents. Can dissolve fat, oil, resin, wax and asphalt. It can be used for degreasing metals and as a solvent in the coatings, adhesives and plastics industries.
trichlorethylene
Insoluble in water, but miscible with organic solvents. It dissolves fats, oils, waxes, rubber, and many resins; it is also used as a solvent and extractant. Trichlorethylene can raise the flash point in paints and is also used as a solvent in paint strippers. Due to environmental reasons, it is gradually being replaced by other systems.
1,2-Dichloropropane
It is a solvent for asphalt, tar pitch, building protectants and roofing linoleum.
chlorobenzene
It is a colorless neutral liquid with a weak benzene-like odor. Insoluble in water, miscible with organic solvents. Chlorobenzene is a good solvent for fats, oils, resins, polymers, rubber and chlorinated rubber. In the presence of a small amount of alcohol, cellulose ethers can be dissolved, but nitrocellulose cannot be dissolved. Chlorobenzene is a solvent in bitumen used in building protection and in the production of bituminous coatings.
Alcohols
Alcohol compounds, because of their unique hydroxyl structure, exhibit completely different chemical properties from aliphatic hydrocarbons, aromatic hydrocarbons and chlorinated hydrocarbons. Its high polarity and strong ability to form hydrogen bonds profoundly affect dissolution behavior. The interaction between the non-polar hydrocarbon chain and the hydroxyl group precisely regulates the solubility characteristics of alcohol. Specifically, lower alcohols exhibit excellent solubility properties for highly polar resins such as shellac and couba resin, but are difficult to dissolve non-polar resins such as fats and oils. As the hydrocarbon chain lengthens, the solubility of alcohol to polar substances gradually weakens, causing the solubility of propanol and higher alcohols in polar resins such as nitrocellulose to significantly decrease, and is instead used as a diluent. Can be enhanced by adding acetates.
The mild solubility of higher alcohols makes them an ideal choice for topcoat solvents. They do not soften the primer, form a good bond with plastics, and avoid bleeding in paper coatings and rubber roller swelling. Further broken down, each type of alcohol has its own unique properties and application fields:
Methanol
Colorless and transparent, with a special odor, strong water absorption, can be mixed with water and various organic solvents in any proportion, but is almost insoluble in fats and oils. Its dissolution range covers polar resins, nitrocellulose, etc., but its solubility to some polymers is limited.
ethanol
Colorless and transparent, with pleasant smell, highly miscible with water and various organic solvents. As a solvent, ethanol is widely used to dissolve polar resins, polymers and natural substances, especially in paper, plastic coatings and ink formulations.
Isopropyl alcohol
Colorless liquid, wide solubility makes it an important raw material in cosmetics, medicine, coatings and ink industries.
Butanol
It has high solubility for a variety of resins and oils, but is insoluble in certain polymers such as cellulose esters. It acts as a diluent in vinyl chloride copolymers and water-based paints, while improving the dilutability and paintability of nitrocellulose.
Isobutanol
Similar to butanol, but slightly different in solubility characteristics, it is particularly effective in improving the fluidity and gloss of paint films, and is suitable for the production of nitrocellulose and other coatings.
sec-butanol
Because of its good water absorption, it is used in paint strippers and co-solvents for water-based coatings.
tert-butyl alcohol
High antioxidant and halogen resistance make it a preferred solvent and co-solvent, especially in wax removal and oil dealkylation processes.
Hexanol
It has a high boiling point and is suitable for improving the fluidity and surface properties of coatings. It is also a good solvent for fats, waxes and dyes.
2-Ethylhexanol
It has high solubility for vegetable oils, fats and various resins. It can be used as a solvent and grinding aid to improve the performance of coatings and baking enamels.
Benzyl alcohol
Benzyl alcohol is an organic solvent that is unique in that it is miscible with a wide range of organic solvents except aliphatic hydrocarbons. It exhibits high solubility in cellulose esters, ethers, fats, oils, alkyds and colorants, but remains insoluble in most polymers, with the exception of lower polyvinyl ethers and polyvinyl acetate. . In the coating industry, the addition of trace amounts of benzyl alcohol can significantly improve the fluidity and gloss of the coating, prolong the evaporation time of the solvent, and produce a plasticizing effect on the physical drying process of the coating film. It is also widely used in the formulation of ballpoint pen ink, effectively reducing the viscosity of two-component epoxy systems.
Methylbenzyl alcohol (1-phenylethanol)
Methylbenzyl alcohol, a nearly colorless neutral liquid with a subtle bitter almond aroma, has limited water miscibility. This solvent exhibits excellent solubility for alcohol-soluble nitrocellulose, cellulose acetate ester series, a variety of natural and synthetic resins, fats and oils. Compared with benzyl alcohol, methylbenzyl alcohol has further expanded its application range and can be miscible with No. 200 solvent oil. In baking enamels, methylbenzyl alcohol shows significant advantages. It not only improves the fluidity of the coating film, but also effectively prevents the coating film from turning white in high-humidity environments. Its unique dissolution characteristics and long evaporation time also make it an important additive in efficient paint strippers. Methyl benzyl alcohol is comparable to benzyl alcohol in its ability to dissolve colorants.
cyclohexanol
Cyclohexanol has a camphor-like aroma, has a solubility in water of approximately 2%, and is compatible with a variety of solvents. It can effectively dissolve fats, oils, waxes and asphalt, but has no dissolving effect on cellulose derivatives. In nitrocellulose paints and oil-based paints, cyclohexanol significantly improves paint performance by extending drying time, preventing whitening, and enhancing fluidity and gloss. It also effectively prevents dissolution of primers in topcoat and clearcoat applications. Cyclohexanol is also used in mineral oil treatments to remove paraffins and as a solvent and spray wetting agent in wax products, cleaners and polishes.
Methylcyclohexanol
Methylcyclohexanol, often sold on the market as a mixture of isomers, has a camphor aroma and is insoluble in water but miscible with all organic solvents. Its dissolving properties are similar to those of cyclohexanol, and it is particularly good at dissolving fats, thus enhancing the adhesion of coatings to incompletely degreased substrates.
Tetrahydrofurfuryl alcohol
As a colorless solution, tetrahydrofurfuryl alcohol is easily miscible with water and various organic solvents except aliphatic hydrocarbons. It is an excellent solvent for nitric acid and cellulose acetate, chlorinated rubber, shellac and various resin base materials.
diacetone alcohol
Diacetone alcohol, an almost odorless ketol alcohol, is slightly acidic because it can be rearranged into the enol form and is widely compatible with water and organic solvents except aliphatic hydrocarbons. As a high-quality solvent for cellulose esters, ethers, alcohol-soluble resins, castor oil and plasticizers, diacetone alcohol can also partially dissolve or swell polyvinyl acetate and chlorinated rubber, but is not effective in polymerizing polystyrene, polyvinyl chloride, etc. The substance remains insoluble. In baking enamel paint, it acts as a high boiling point solvent, effectively improving the fluidity and gloss of the paint.
ketones
Ketone solvents, as colorless, transparent and highly fluid liquids, are known for their unique odor, high volatility and chemical stability. Its core feature lies in the hydrogen bond acceptor ability conferred by the carbonyl group, thereby exhibiting excellent solubility properties. Lower ketones are good at dissolving polar substances such as resins, fats and oils, while higher ketones show more advantages in dissolving non-polar resins.
acetone
Acetone is easily miscible with water and a variety of organic solvents, and its solubility range is wide, covering cellulose esters, ethers, vinyl chloride copolymers, polyacrylates, polystyrene and other resins, as well as fats, natural and synthetic oils . It can also swell polyvinyl chloride and polymethyl methacrylate, but remains insoluble in polyacrylonitrile, polyamide and rubber. Acetone plays an important role as a highly volatile solvent in fast-drying cellulose varnishes and adhesives.
Methyl ethyl ketone
Methyl ethyl ketone has similar solubility to acetone but is only slightly soluble in cellulose acetate and cannot dissolve natural and synthetic waxes. In the coatings industry, it is often used as a replacement for ethyl acetate, especially in wood paints, although its pungent odor limits its range of applications.
Methyl butyl ketone
Methyl butyl ketone is slightly soluble in water, but perfectly miscible with organic solvents. As a medium boiling point solvent, it is good at dissolving nitrocellulose, vinyl resin, etc., and can improve the dilution efficiency of non-solvents and diluents. In the field of coatings, methyl butyl ketone is mostly used in thermal spray and coil coatings. Its photochemical inertness ensures that no “light haze” is produced during use.
Methyl isobutyl ketone
This colorless, sweet-tasting liquid is partially soluble in water but fully compatible with organic solvents. Its dissolution range is wide, including nitrocellulose, polyvinyl acetate, epoxy resin and other resins, as well as fats and oils. In the coatings industry, methyl isobutyl ketone not only gives nitrocellulose varnishes excellent fluidity and gloss, but also enhances whitening resistance and enables the production of highly concentrated solutions. It is an important solvent for epoxy resin paints, PVC and acrylic paints, and also plays a key role as an anhydrous, hydroxyl-free solvent in polyurethane coatings.
Methyl amyl ketone and methyl isoamyl ketone
Both are high boiling point solvents and exhibit excellent solubility, similar to the solubility characteristics of methyl isobutyl ketone.
Ethyl amyl ketone
It is insoluble in water but completely miscible with organic solvents. As a high-boiling point solvent, it effectively improves the fluidity of coatings and is a leader in the field of solvents.
diisopropyl ketone
As a high boiling point solvent, it is widely used in the production of nitrocellulose emulsion (used for leather coating) and chlorinated rubber coatings. At the same time, it is also an indispensable diluent for polyvinyl chloride organosol.
diisobutyl ketone
It is a colorless, low-viscosity liquid, which is a mixture of specific isomers. Although it is insoluble in water, it is easily miscible with all commonly used organic solvents. Its high boiling point characteristic gives it strong dissolving power for various materials such as nitrocellulose and vinyl resin.
cyclohexanone
It is a high boiling point solvent, insoluble in water but miscible with a variety of organic solvents. It is particularly good at dissolving a range of materials such as cellulose nitrate ester, rosin, and alkyd resins, exhibiting extraordinary solubility properties.
Methylcyclohexanone
As a mixture of industrial isomers, its solubility is similar to that of cyclohexanone, but it should be noted that it does not dissolve cellulose acetate ester.
dimethylcyclohexanone
The nature of its cis-trans isomer mixture allows it to maintain consistency in solubility and miscibility with methylcyclohexanone.
Trimethylcyclohexanone
This colorless, high-boiling solvent has a light menthol aroma and is partially soluble in water but fully miscible with organic solvents. In the coating industry, it is not only a leveling agent in air drying and drying systems, reducing bubbles and shrinkage holes, but also improving the fluidity and gloss of coatings. Trimethylcyclohexanone plays an important role in polyvinyl chloride processing, leather coating and pesticide formulations, and its oxime compound is an anti-scaling tool in air-drying coatings.
Isophorone
It is composed of α-isophorone and a small amount of β-isophorone isomers. It is a stable water-white liquid with a slight odor and is fully compatible with organic solvents. Its broad solubility covers a wide range of natural and synthetic materials from PVC to alkyds, but it remains insoluble in certain materials such as polyethylene.
In the fields of leather coating, plastic ink, plant protection agent and adhesive, isophorone has shown its unique value, especially in reducing solution viscosity, improving adhesion and emulsion stability.
Esters
Ester solvents are transparent liquids, usually with a pleasant fruity smell, neutral and very stable, but can be hydrolyzed by heating in the presence of strong acids and alkalis. They are less polar than the corresponding alcohols but have very good solubility for polar substances. As the carbon chain in the hydroxyl and carboxyl groups of the ester grows, its solubility for polar substances decreases, but its solubility for low-polarity substances increases. Lower esters are partially water-soluble. Acetate is the most important ester solvent in the coatings industry. Formate esters are rarely used because they are easily hydrolyzed. Propionate, butyl, and isobutyl are also unimportant because they have too strong a fruity flavor. Certain glycolate and lactate esters and dimethyl ester mixtures of dicarboxylic acids are also important.
Isobutyl formate
Slightly soluble in water, it is good at dissolving fats, oils, various polymers and chlorinated rubber, but is ineffective for cellulose acetate. Commercially, it is often used as a component of solvent mixtures for coatings.
Methyl acetate
It is miscible with water and most organic solvents, and has good solubility in a variety of cellulose esters, resins and ethers, but is not suitable for specific materials such as shellac and Cuban resin. As a highly volatile solvent, it can reduce paint viscosity when used alone or mixed with alcohols and esters.
Ethyl acetate
It is colorless and neutral, with a slight fruity aroma, and has good solubility in many resins, polymers and fatty oils. It is especially outstanding in cellulose nitrate ester coatings, but it requires ethanol to assist in dissolving cellulose acetate ester and is insoluble in polyvinyl chloride. It is a key solvent in fast-drying coatings and is also commonly used in polyurethane coatings to enhance dilution.
Butyl acetate
Colorless, neutral, water-incompatible liquid with a pleasant fruity smell, it is very effective in cellulose nitrate esters, cellulose ethers, chlorinated rubber, post-chlorinated polyvinyl chloride, vinyl chloride copolymers, and polyvinyl chloride copolymers. Styrene, polyvinyl acetate, polymethacrylate, alkyd resins, fats and oils have good solubility, but do not dissolve cellulose acetate.
Butyl acetate is the most important moderately volatile solvent in the coatings industry. Its volatility is high enough to evaporate quickly from the coating film, but low enough to prevent shrinkage, whitening and disordered flow. The solubility of butyl acetate is considerably improved by the addition of butyric acid. In coating formulations, butyl acetate is often used together with aromatic solvents. Since butyl acetate has low intrinsic viscosity, it is very suitable as a co-solvent for high solid content paints. It is also the most widely used solvent in polyurethane coatings.
Isobutyl acetate has better volatility and lower flash point than butyl acetate and is therefore used in the production of fast-drying nitrocellulose varnishes. Due to its low water content, it can be used as a solvent and diluent for polyurethane coatings. Isobutyl acetate is also used as a viscosity-reducing cosolvent in low-solvent coatings.
Acetic acid (2-ethylhexyl ester)
It is a high boiling point solvent with good solubility and is used for baking enamel paint.
Octyl acetate and nonyl acetate
Both are high-boiling mixtures of isomers used in baking enamels.
Hexyl acetate
Good solubility for resins, polymers, cellulose derivatives, fats and oils. Does not dissolve cellulose acetate. Small amounts of hexyl acetate can be used as a leveling agent in paints.
Cyclohexyl acetate
Slightly soluble in water, but completely miscible with commonly used organic solvents. Its solubility is comparable to amyl acetate. Cyclohexyl acetate can dissolve oil, fat and resin. Wax, cellulose nitrate, cellulose tripropionate and butylcellulose acetate, alkyd resin, polyester resin, phenolic resin, amino resin, polyvinyl chloride, vinyl chloride copolymer, polyvinyl acetate, poly Vinyl ether, epoxy resin, acrylic resin and asphalt, etc. In metallic paints, cyclohexyl acetate improves wetting and flow and prevents blistering.
Benzyl acetate
It is a water-insoluble liquid with the smell of aromatic hydrocarbons. It is used as a high-boiling point solvent in printing inks.
Methyl glycol acetate
Neutral liquid with slight odor, miscible with water and organic solvents, and has good solubility for many natural and synthetic resins. Methyl glycol acetate gives the coating good fluidity and high dilutability, preventing foaming and whitening. Due to its teratogenicity, it has been replaced by other solvents in paints.
lactate
It can improve pigment wetting, reduce coating viscosity, is suitable for high solid content systems, and enhances the permeability of wood coatings.
Butyl hydroxyacetate
Comparable solubility and volatilization behavior to butyl acetate. Good solubility for fats, oils, alkyds, nitrocellulose esters and many resins. It has high dilutability against alcohols and aromatic hydrocarbons.
Butyl glycolate reduces the viscosity of alkyd resin coatings and improves the flow and gloss of air-drying and oven-drying paints, especially coil coatings and leather varnishes. It can also be used in polyvinyl acetate emulsion to reduce the film-forming temperature.
Dimethyl adipate, glutarate and succinate
Used as a high boiling point mixture with good solubility. Used in baked enamels, coil coatings and automotive coatings.
propylene carbonate
It is liquid at room temperature and has a high boiling point. Used as a high boiling point solvent and film-forming additive in coatings, especially polyvinyl fluoride and polyvinylidene fluoride systems. It can also be used as a co-solvent in pigments and dyes.
Alcohol ethers
Ethylene glycol monomethyl ether and ethylene glycol monoethyl ether
It has a slight odor and is miscible with water and all organic solvents except aliphatic hydrocarbons. It is a good solvent for many natural and synthetic resins. But it does not dissolve fats, oils (except castor oil), dammar resin, rubber, asphalt, aliphatic hydrocarbon resins, polystyrene, polyvinyl chloride and vinyl chloride copolymers, etc. Due to its teratogenic properties, it is no longer used as a solvent in the paint and stain industry.
Ethylene glycol monopropyl ether and ethylene glycol monoisopropyl ether
It has comparable solubility and miscibility with ethylene glycol monoethyl ether, but evaporates more slowly and has better solubility for low-polarity resins. It is less toxic than ethylene glycol monoethyl ether, so it is gradually replacing ethylene glycol monoethyl ether.
Ethylene glycol monobutyl ether
Neutral colorless liquid with a slight pleasant odor. It is miscible with water at room temperature, but has an immiscible zone with water at high temperatures. It is miscible with organic solvents and is nitrocellulose ester and cellulose. Excellent solvent for ether, rosin, shellac, chlorinated rubber, polyacrylate, alkyd resin, phenolic, urea-formaldehyde and melamine formaldehyde resin, oil, fat, etc. Ethylene glycol monobutyl ether is widely used in solvent-based coating systems to improve the fluidity and surface quality of coatings. Due to its dissolution behavior, it is increasingly used in water-thinner coatings.
Diethylene glycol monomethyl ether
Adding a small amount as a low-volatile solvent in paint can improve the gloss and fluidity of the paint. It is also used as a solvent in printing inks and ballpoint pen oils.
Diethylene glycol monoethyl ether
It is used in the coating industry to improve the gloss and fluidity of coatings and increase dilutability. Diethylene glycol monoethyl ether can also be used to predissolve alcohol-soluble dyes and is a component of many wood stains. It can also be used as a cleaning agent in printing inks and offset printing, and is a component of ink and ballpoint pen oil. The phthalate ester of diethylene glycol monoethyl ether is an excellent plasticizer for vinyl resins.
Diethylene glycol monobutyl ether
Colorless, transparent, neutral liquid with a pleasant mild odor, miscible with water and organic solvents including aliphatic hydrocarbon compounds. Diethylene glycol monobutyl ether has soluble power on nitrocellulose esters, cellulose ethers, chlorinated rubber, polyvinyl acetate, polyacrylates and many other synthetic and natural resins. But does not dissolve polystyrene, polyvinyl chloride, fats and most oils.
Diethylene glycol monobutyl ether is a high boiling point solvent used to improve the gloss and fluidity of coatings. Due to its high volatility value, adding <5% can significantly improve the properties of the coating without significantly increasing the baking time. . In cellulose nitrate ester and cellulose ether varnishes, even smaller additions are effective. In latex paints and room temperature curing coatings, diethylene glycol monobutyl ether can increase the coating rate and surface gloss. Due to its good solubility in resins and dyes, it can also be used in coatings and printing inks in conjunction with other low-volatility solvents.
Triethylene glycol monoethyl ether
Almost colorless, neutral, mild-smelling liquid with low water absorption. Soluble in water and most organic solvents, but only partially compatible with aromatic hydrocarbons and aliphatic hydrocarbons. Triethylene glycol monoethyl ether can dissolve nitrocellulose, shellac, rosin, ketone resin, maleic resin, chlorinated rubber, alkyd resin and many other coating resins. But it does not dissolve cellulose acetate, polyvinyl chloride, vinyl chloride copolymer, fat, oil and rubber.
The uses of triethylene glycol monoethyl ether are similar to those of diethylene glycol monoethyl ether. It can also be used as a solubilizer for immiscible liquids, and can also be used in the manufacture of pesticides and hand washing detergents. It is also used in printing ink. Adding a small amount of triethylene glycol monoethyl ether to wood paint can prevent the wood fibers on the surface from turning upside down during the painting process.
Triethylene glycol monobutyl ether
An almost colorless, neutral, slightly odorous liquid, soluble in water and most organic solvents, but only partially soluble with aromatic hydrocarbons and aliphatic hydrocarbon solvents. Its solubility is comparable to diethylene glycol monobutyl ether. Triethylene glycol monobutyl ether can be used as a solubilizer for immiscible liquids and is used in the production of household paints, metal cleaners and wood preservation. In the coating industry, it is suitable as a high boiling point solvent for baking paint, as a leveling agent and as a co-solvent in wood paint to prevent wood fibers from standing upside down from the surface.
1-methoxy-2-propanol
The product contains a small amount of 2-methoxy-1-propanol. Colorless neutral solution with some pleasant slight odor, miscible with water and organic solvents in any ratio. Its properties are roughly equivalent to those of ethylene glycol monoethyl ether. It has a slightly higher volatility and can be used as a solvent component in coatings and printing inks to improve the wetting of some pigments and colorants. For cellulose nitrate, cellulose ether, chlorinated rubber, polyvinyl acetate, polyvinyl butyral, phenolic resin, shellac, rosin, phenolic, melamine formaldehyde resin, urea-formaldehyde resin, alkyd resin, polyacrylate , castor oil, linseed oil and some vinyl chloride copolymers have good solubility. But it does not dissolve rubber, asphalt, cellulose acetate, polystyrene, polyvinyl alcohol and polyvinyl chloride. Due to its pleasant mild odor, it is ideally suited for use in nitrocellulose ester lacquers for coating wood, paper and metal. As a volatile solvent, it can improve the permeability, fluidity and gloss of the paint film, and prevent the formation of whitening, fish eyes and blistering. Adding 1-methoxy-2-propanol will not prolong the drying time of the coating system, but can increase the dilutability of cheap non-solvents, reduce and stabilize the viscosity of the coating, and improve the coating performance of the coating. Since it only swells dry coatings, it is suitable for topcoats. It can also be used as a solvent to improve the gloss and flow of printing inks. Due to its good solubility properties for dyes and ability to wet pigments, it can deepen the color of inks.
Ethoxypropanol
The physical properties are very similar to ethylene glycol monoethyl ether, and it is a low-toxicity substitute for ethylene glycol monoethyl ether.
Isopropoxypropanol
It is a mixture of 1-isopropoxy-2-propanol and 2-isopropoxy-1-propanol. It has a relatively high boiling point and is miscible with water and organic solvents. Its solubility properties, volatility properties and uses are similar to those of ethylene glycol monobutyl ether. It is an effective plasticizer and can be used as a co-solvent for high solid content and water-based coatings.
Isobutoxypropanol
Often appears as a mixture of 1-isobutoxy-2-propanol and 2-isobutoxy-1-propanol. It has a slight odor, a high boiling point, and is miscible with water and organic solvents. Its solubility, volatility and uses are similar to those of ethylene glycol monobutyl ether. It is an efficient solubilizer and can be used as a co-solvent for high solid content and water-based coatings. Propylene glycol tert-butyl ether is similar to isobutoxypropanol.
Methyl dipropylene glycol
It is a high boiling point solvent, transparent, miscible with water in any ratio, and has only a slight special odor. Easily dissolves cellulose nitrate esters, cellulose esters and ethers as well as many other natural and synthetic resins. Due to its low evaporation rate, adding a small amount to the paint can control the fluidity, evaporation rate and dilutability of the paint with non-solvents. It can improve the coating performance of nitrocellulose ester varnish, chlorinated rubber coatings, and alkyd resin coatings. It is also suitable as a film-forming aid for dispersion systems, a co-solvent for water-based coatings, a solubilizing agent for cleaning agents, and a solvent for inks, printing inks, and ointments.
Methoxybutanol (3-methoxy-1-butanol)
Mild odor liquid, miscible with water and organic solvents, suitable for nitrocellulose ester, cellulose ester, polyvinyl butyral, phenolic, urea-formaldehyde, melamine formaldehyde resin, alkyd, maleic acid resin, plasticizer, fat Has good solubility in dry oils. But it does not dissolve mineral oil, wax, rubber, chlorinated rubber, cellulose acetate, polyisobutylene, polystyrene, polyvinyl chloride, vinyl chloride copolymer, etc. It can be used as a low volatility solvent like butanol.
other
1,1-Dimethoxyethane
Neutral liquid, miscible with water and organic solvents. It dissolves nitrocellulose, cellulose ethers, some vinyl chloride copolymers, synthetic and natural resins. But it does not dissolve polyvinyl chloride, polystyrene, chlorinated rubber and cellulose acetate. It can be used in the production of coatings, adhesives and toe hardeners.
N,N-dimethylformamide (DMF)
Miscible with water and all organic solvents except aliphatic hydrocarbons, cellulose esters and ethers, polyvinyl chloride, vinyl chloride copolymers, polyvinyl acetate, polyacrylonitrile, polystyrene, chlorinated rubber, polyacrylates A good high boiling point solvent for phenolic resins, etc. But it does not dissolve polyethylene, polypropylene, urea-formaldehyde resin, rubber and polyamide. It is often used as a solvent in printing inks, polyacrylonitrile textile solutions and the synthesis of acetylene.
N,N-Dimethylacetamide (DMA)
Miscible with water and organic solvents, it has very good solubility for many resins and polymers. Used in the production of acrylic fibers, films, sheets and coatings, and as reaction media and intermediates in organic synthesis.
Dimethyl sulfoxide (DMSO)
Colorless and transparent liquid, miscible with water and organic solvents except aliphatic hydrocarbons. It is a soluble compound of cellulose esters and ethers, polyvinyl acetate, polyacrylates, vinyl chloride copolymers, polyacrylonitrile, chlorinated rubber and many resins. Good high boiling point solvent. It can also be used in polyacrylonitrile spinning solutions and paint strippers, as film-forming aids for dispersions, as well as extractants and reaction media in organic synthesis.
1-nitropropane
Colorless, non-hydroabsorbent liquid with mild odor. Can dissolve nitrocellulose, cellulose ether, alkyd resin, chlorinated rubber, polyvinyl acetate, vinyl chloride copolymer, etc. But it does not dissolve polyvinyl chloride, rosin, polyacrylonitrile, wax, rubber and shellac. Used as a co-solvent in coatings to improve the wetting, fluidity and electrostatic process of pigments and reduce the drying time of coatings.
N-methylpyrrolidone
Quite mild, ammonia smell, miscible with water and most organic solvents. It has good dissolving power for cellulose ether, butadiene-acrylonitrile copolymer, polyamide, polyacrylonitrile, wax, polyacrylate, vinyl chloride copolymer and epoxy resin. Used in paint strippers and paint stripping coatings to reduce the viscosity of the paint and improve the wetting power of the paint system.
1,3-dimethyl-2-imidazolidinone
Colorless, high boiling point, highly polar inert protic solvent. Low toxicity, good chemical and thermal stability. Miscible with water and most organic solvents, it is a component of nail polish, ballpoint pen oil and paints.
Hexamethyltriamine phosphate
Alkaline, highly polar, non-flammable solvent with very good solubility. Its solubility is comparable to DMSO and DMA. It can also be used as antifreeze and antistatic agent.
write at the end
Whether you are a coating manufacturer or a professional in the application field, solvent selection should be regarded as a crucial task. You must consider its solubility, drying speed, and impact on construction performance, as well as environmental regulations and Human health safety requirements. Only in this way can we continue to move forward in this ever-changing industry, promote coating technology in a more efficient, environmentally friendly, and humane direction, and jointly draw a more colorful and beautiful picture of the world.