Ink, printing

A process is in use for printing onto transparent plastic sheet, e.g. polyethylene film for packaging. The sheet is usually irradiated or exposed to ozone which modifies the surface structure, after which a printing ink 

After curing, the fully reacted polyurethane resin formed is no longer chemically active and is not a hazard to health unless heated to the point of decomposition. Handling materials containing prepolymers is not likely to give rise to an inhalation hazard from the isocyanate unless they are heated, sprayed or distributed into the air as dust before the curing process has had time to go to completion. This could happen in some printing processes where the characteristics of the ink and the process can lead to the production of spray. In addition, solvents are used in some ink formulations and these are dried by the application of heat, which would drive off any residual isocyanate as vapour. 

The exhaust ducts fitted to the machine to remove solvent vapours prevent contamination from this source, but regular monitoring of the workroom atmosphere should be undertaken, preferably using personal samplers, to ensure that the TLV is not being exceeded from any source. In common with all isocyanate materials, it is essential to ensure that occasional lapses in operating methods or machine malfunctions do not give rise to short-term exposure of operators to levels above the TLV. 

Polyurethane adhesives were originally made from TDI by mixing it with a hydroxylic compound dissolved in ethyl acetate. More recently, polyisocyanates have been used which do not normally give rise to a vapour hazard unless curing is carried out by heat. Precautions may need to be taken if the adhesive is applied by spray, as mentioned before. Otherwise the hazards and precautions applying to the use of adhesives are similar to those for surface coatings and printing inks. 

All the main classes of pigments are used in the printing ink industry, but the high-performance pigments, e.g. quinacridones, which can be thirty times dearer than azo pigments, are reserved for use in the highest quality printing. 

In flexographic printing there has been a move away from solvent inks to the more environmentally friendly water-based inks. This has led to a renewed interest in the use of this technology.  

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Dehydrated (e.g. AICI3) to cyclohexene. Used in the manufacture of celluloid, esters (plasticizers), detergents and printing inks. 

Colourless liquid with a strong peppermintlike odour b.p. 155" C. Manufactured by passing cyclohexanol vapour over a heated copper catalyst. Volatile in steam. Oxidized to adipic acid. Used in the manufacture of caprolactam. Nylon, adipic acid, nitrocellulose lacquers, celluloid, artificial leather and printing inks. 

Eihyl-l-buianol, b.p. 147 "C, is used in synthesis and as a solvent for printing inks and surface coatings. 

Dearomatized or not, lamp oils correspond to petroleum cuts between Cio and C14. Their distillation curves (less than 90% at 210°C, 65% or more at 250°C, 80% or more at 285°C) give them relatively heavy solvent properties. They are used particularly for lighting or for emergency signal lamps. These materials are similar to kerosene solvents , whose distillation curves are between 160 and 300°C and which include solvents for printing inks. 

Zinc is also used extensively to galvanize other metals such as iron to prevent corrosion. Zinc oxide is a unique and very useful material for modern civilization. It is widely used in the manufacture of paints, rubber products, cosmetics, pharmaceuticals, floor coverings, plastics, printing inks, soap, storage batteries, textiles, electrical equipment, and other products. Lithopone, a mixture of zinc sulfide and barium sulfate, is an important pigment. 

Screen printing inks Screen-process inks Screens Screw dislocation theory Scrip set Scrubbers... 

Heico Chemicals is the only producer of acetamide in the United States. Small amounts are imported from Europe and Asia. It is shipped in 32-L (35-gal) dmms weighing about 80 kg. Acetamide appears to have a wide spectmm of appHcations. It suppresses acid buildup in printing inks, lacquers, explosives, and perfumes. It is a mild moisturi2er and is used as a softener for leather, textiles, paper, and certain plastics. It finds some appHcations in the synthesis of pharmaceuticals, pesticides, and antioxidants for plastics. 

R. Holman, ed., UU andEB Curing Formulations for Printing Inks, Coatings and Paints, SITA Technology, London, 1984. 

Hydrocarbon resin is a broad term that is usually used to describe a low molecular weight thermoplastic polymer synthesized via the thermal or catalytic polymerization of coal-tar fractions, cracked petroleum distillates, terpenes, or pure olefinic monomers. These resins are used extensively as modifiers in the hot melt and pressure sensitive adhesive industries. They are also used in numerous other appHcations such as sealants, printing inks, paints, plastics, road marking, carpet backing, flooring, and oil field appHcations. They are rarely used alone. 

Hydrocarbon resins based on CPD are used heavily in the adhesive and road marking industries derivatives of these resins are used in the production of printing inks. These resins may be produced catalyticaHy using typical carbocationic polymerization techniques, but the large majority of these resins are synthesized under thermal polymerization conditions. The rate constants for the Diels-Alder based dimerization of CPD to DCPD are weU known (49). The abiHty to polymerize without Lewis acid catalysis reduces the amount of aluminous water or other catalyst effluents/emissions that must be addressed from an environmental standpoint. Both thermal and catalyticaHy polymerized DCPD/CPD-based resins contain a high degree of unsaturation. Therefore, many of these resins are hydrogenated for certain appHcations. 

Hydrocarbon resins are used extensively as modifiers in adhesives, sealants, printing inks, paints and varnishes, plastics, road marking, flooring, and oil field appHcations. In most cases, they ate compounded with elastomers, plastics, waxes, or oils. Selection of a resin for a particular appHcation is dependent on composition, molecular weight, color, and oxidative and thermal stabiHty, as weU as cost. A listing of all hydrocarbon resin suppHers and the types of resins that they produce is impractical. A representative listing of commercially available hydrocarbon resins and their suppHers is included in Table 6. 

There are four principal classes of printing ink, which vary considerably in physical appearance, composition, method of appHcation, and drying mechanism. These also fall into two general types of consistency or viscosity, paste and Hquid. The classes are letter press and Hthographic (Utho) inks, which are called paste inks, and flexographic (flexo) and rotogravure (gravure) inks, which are called Hquid inks (1). 

Drying. Drying may be defined as any process that results in the transformation of a fluid-printing ink into a very high viscosity or soHd film. 

Polymerization. Thermal polymerization or curing of an ink film at elevated temperatures can foUow many different chemical paths. Condensation and cross-linking reactions may be accompHshed with or without the use of catalysts. However, this method of drying generally has not been widely used for printing inks, except those used for metal and glass decoration, and some clear coatings. 

Occupational Safety and Health J ct. OSHA regulations deal principally with physical aspects of safety and those things generally associated with accident prevention. These federal regulations deal especially with the need for estabHshed material safety data sheets and the proper labeling of printing inks under the Hazard Communication Laws. 

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