In the previous part of  the article on chemicals in the printing industry, we learned about the types of chemicals, especially the types of compounds and chemicals used in it. In this article, you will get to know the chemicals of the printing industry with all kinds of solvents, deodorizers, waxes, etc. in the printing industry.

Chemicals: Solvents in the printing industry

 Alcohols: Alcohols are also used as solvents in the construction of printing compounds, especially in flexographic and heliogravure compounds, and include the following alcohols:

• Ethanol or Ethyl Alcohol: Ethanol is not used without water and pure in the compounding industry, but it is used as 96 % of which 4 % is water.
• Normal propanol: a very pure solvent and is one of IMS and is used in flexo and gravure compounds. The drying and adjustment of the ink drying after printing and on the printing machine can be controlled with this solvent.
•  Isopropanol IPA is a colorless water-colored IMS alcohol. It is one of the good resin solvents used in flexo and gravure.
•  Normal Butanol: It is an alcohol from the IMS group, which evaporates much later than the previous alcohols and has the ability to mix with most of the solvents used in heliogravure and flexography. It is mostly used in dyeing and compounding industries, especially in silk screen compounds. Most of the game’s colored fats based on oil and wax can also be dissolved in normal butanol.
•  Cyclohexanol: an oily substance, which has a limited use in screen compounds.
• Methylcyclohexanol: a completely oily liquid that is one of the best solvents for cellulose ethers, rosin esters and shellac.
•  Mono Ethylene Glycol: Mono Ethylene Glycol is a colorless and concentrated alcohol that absorbs moisture and mixes well with water. It is used in water -based letterpress cartons and water- based flexo .
•  Monopropylene glycol: This colorless solvent is very similar to ethylene glycol. It is used in food and pharmaceutical industries (perfume and essential oil). It is also used in the production of printing inks for food packaging.
•  Hexylene Glycol: It is a colorless and odorless liquid, which is most commonly used to delay the drying of flexographic and gravure compounds. Due to its high cost, it has little use, but it is used in water -based letterpress inks and food packaging printing industries. In some cases, this solvent can be used in the production of dry offset inks for printing on ice cream cups and dairy cups made of polystyrene. It can be mixed with vegetable oil and most of the oil solvents used in printing inks.
•  Diethylene glycol: It is a colorless and thick liquid that absorbs moisture and has the ability to mix with water, alcohols, acetone, and glycol ethers. It is mostly used in the formulation of water- based letterpress compounds in packaging industries, especially cartons.
• Dipropylene glycol: This colorless, concentrated solvent is almost as water-intensive as diethylene glycol in the production of carton and letterpress compounds. In order to adjust the degree of drying, this type of compound is coordinated with other glycols.
•  Triethylene glycol: is a colorless, stable, concentrated solvent; which uses glycolic solvents to dissolve maleic resins, shellac to produce water-based letterpress compounds .
•  Glycerin: It is a thick syrupy liquid, colorless, odorless and with a sweet taste . It is completely water absorbent and absorbs up to 50 % of its weight. The most common use of this liquid is to make consumable resins in printing inks and it is also used to make a type of antistatic ink. In addition, in most water -based compounds , especially flexo, it plays the role of softener in acrylic resins.
•  Aminoethyl glycol ether: It is a good solvent for nitrocellulose and a part of hydroxylated resins, which is oily and has a sweet smell.
•  Ethoxypropanol: This non-toxic and slow-volatile solvent has replaced ethoxyethanol for the solvent propylene glycol monoethyl ether (ethoxypropanol), which is the closest to ethylene oxide. It delays the solvent jump. It is used in letterpress, flexo and gravure compounds.
• Stane or dimethyl ketone: It is one of the most widely used industrial solvents and has a relatively reasonable price with high solvency. It is mostly used in the preparation of nitrocellulose lacquers. It is used in European countries in making flexo and gravure compounds.
•  Methyl ethylene ketone: It is a colorless solvent, soluble in all vegetable oils and ester solvents, its most and main use is in graver compounds, and its jumping power is one third of stane. Along with ethyl acetate solvents, alcohols are used to dissolve maleic, cellulose and polyamide resins to produce gravure compounds.
•  Methyl isobutyl ketone: It is a colorless solvent, it is almost immiscible with water, but it is miscible with most organic solvents and oils. It is used in silkscreen and gravure printing colors.
•  Cyclohexane: It is a very strong solvent, colorless and with a pungent smell. It does not mix with water. It is used to dissolve resins such as ethyl cellulose, nitro cellulose and polyvinyl chloride. Its most consumption is in the production of silk screen paint.

Sale of cyclohexanol

•  Methylcyclohexanone: Its trade name is Sectone B. Its color is amber and it has a very pungent smell, and it is used in silk screen printing inks like cyclohexanone.
•  Isoprene: A very good ketone solvent, the best solvent for oils and fats. It is mostly used for the production of metal printing compounds by the silk screen method and is the best solvent for nitrocellulose and PVC.
•  Distane alcohol (Pyranton alcohol): It is a clear solvent with a slightly yellow color, which gradually becomes more yellow as a result of staying. It is a completely exceptional solvent, because it has both alcoholic properties and ketone properties; This means that it can hold two resin groups together as an intermediary solvent. The best solvent for nitrocellulose is cellulose acetate, polyvinyl acetate, shellac, and it is the solvent of most isobasic and non-basic inks.
•  Ethyl acetate : It is a colorless solvent with a strong fruity smell. After the printing ink, it is also used in the dyeing industry to prepare industrial varnishes. In addition, it is also a solvent for nitro resins, cellulose, ethyl cellulose, polyvinyl acetate, polystyrene, rosin esters, and malenic resins.
• Isopropyl acetate: It has all the properties of ethyl acetate, with the difference that its volatility is half that of ethyl acetate, but its smell is sharper than ethyl acetate.
•  Normal Butyl Acetate: Colorless, with a fruity smell and specific to acetate solvents. It does not mix with water, but it mixes with vegetable and fossil oils, organic and hydrocarbon solvents. It is used in a very small amount in flexo and gravure printing compounds and mostly in decorative compounds and aluminum foil. In addition, hydrocarbon resins, rosin and rosin esters, chlorinated rubber, vinyl resins, polystyrene and acrylates are good solvents for nitrocellulose.
•  Normal propyl acetate: a water color with a fruity smell and a good solvent for nitrocellulose; Especially when it is mixed with other alcohols and acetates, it is used for flexo and gravure colors.

Chemicals: Softeners in the printing industry

Softeners in printing ink make the film from varnishes or printing ink flexible after printing and remove it from being brittle and brittle. Basically, plasticizers must not be volatile and remain in the polymer structure of the printed composite film to maintain the softness and flexibility of the printed film. A large number of plasticizers, with various chemical formulas, are used in composite printing construction. These softeners are used in the form of thick liquid or powdered solids in compound formulations. Qualitatively, the softener should not cause pigment migration from the underlying layers to the printed surface. The role of softeners is summarized as follows:

1. They add shine
2.  They prevent crystallization (usually due to temperature changes, printed surfaces may become brittle and brittle).
3. They prevent the accumulation of pigment.
4.  They give more flexibility to printed surfaces.
5.  They increase the adhesion of the printed film to the printed surface.
6.  At high temperature, they stabilize the color.

The best softeners used in the compounding industry are as follows:

1-D. B. Pi ( Di Butyl Phetalate ), 2-D. She. Di Octyl Phetalate , 3- Tricresyl Phosphate, 4- Epoxidized Soybean Oil, 5- Camphor, 6- Triethyl Stearate, 7- Diisobutyl Phthalate, 8- Modified castor oil compounds .

Chemicals: Waxes in the printing industry

Waxes make the printed surface smooth and slippery, and apart from being resistant to wear, they also make the printed surface water resistant. In addition, there is a large percentage of wax in the construction of compounds that are converted by heat . By adding a small amount of wax to the printing compound formula, a large amount of its adhesion is reduced . Among the waxes used in this industry are as follows:

1. Synthetic waxes: polyethylene waxes, polytetrafluoroethylene, fatty acid amides
2. Petroleum waxes: Montana wax

Chemicals: dryers in the printing industry

Dryers are used as catalysts to increase the drying properties of oils that are used in the construction of offset and letterpress compounds. In the presence of these chemicals, the oxidation steps and the formation of a dry film and turning it into a hard film are done in a short period of time instead of 4 hours. Most of these catalysts are mineral salts and soaps of organic acids.

In recent years, complex compounds and derivatives of metals have come to the market to increase the oxidation time of offset and letterpress compounds. There are two types of metal dryers:

1- Liquid driers: cobalt, manganese, sodium, lead, zirconium, calcium, lithium; And the organic acids that are used to produce liquid dryers are: octoic fatty acid; Fatty acid resin, naphthenic fatty acids, linseed oil fatty acids.

2- Pulp dryers: Pulp dryers are mostly used in four-color printing where the colors are placed on top of each other. This group of driers is obtained by spreading and grinding lead and manganese salts in linseed oil varnishes. Lead acetate and manganese borate are the most common salts used for this purpose. Cobalt salt can also be used, which is used alone or with manganese naphthenate. Mineral peroxides have recently been used to increase the drying power of offset and letterpress inks and have been very successful.

Chemicals: Antioxidants in the printing industry

Antioxidants are substances that combine with free radicals produced in the building of the printing compound and prevent the spontaneous oxidation of the compound. The antioxidant substances used in the printing ink are as follows:

trade name	chemical name
Eugenol	Hydroxyanisole
Hydroquinone	Methyl ethyl ketoxime
Follower of Cutshall	Aldoxim boutique
Guanycol	Cyclohexanone oxime

Chemicals: deodorants in the printing industry

Some of the materials that are used in the construction of composite printing have a strong and sometimes extremely unpleasant smell, so they create a nuisance. Volatile solvents are probably the worst sources of these unwanted odors. In some cases, the volatile by-products that are created by the oxidation reactions of the composite film or the storage and maintenance of the composite, as well as some materials used in the composite building, cause a bad and unpleasant smell due to the combination with the printed surface layer . , which is necessary to prevent these unwanted smells in any way. This problem can be prevented and solved by knowing the construction and properties of consumables in the production of printing ink.

In some cases, the use of detergents to wash rubber and compound clay rolls creates an unwanted smell on printed surfaces, so care must be taken in the selection of detergents and solvents. In some cases, in order to hide unwanted odors, materials with a strong and effective odor can be used in a small amount in the formula of the printing composition, thereby overpowering the odors in the mixture with the good odors. Such substances are called deodorants, which include amyl compounds, methyl salicylate, vanilla and some vegetable oils or the result of distillation of vegetable substances (essential oils of various fruits).

Chemicals: compounds dried by radiation

One of the great advances in the printing ink industry in recent years, especially in pulp printing inks, is the production of inks that are cured by radiation , or polymerized. Irradiation of UV rays on the compounds and light varnishes on the work leads to the reaction between the resin molecules in the structure of these compounds, and as a result, the compound becomes a shiny dry solid layer. In this way, in fact, as a result of radiation, the polymerization continues and the resins become a solid polymer. The raw materials used in this type of compounds are as follows :

1- epoxy acrylate resins, 2- polyester acrylates and unsaturated polyesters, 3- urethane ester resins