Flexo

Flexo inks Flexprene Flexricin Flexsorb FTP Flexsorb SE Flexure testing Flexzone3C [101-72-4]... 

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). 

The printing of newspapers is conducted at very high speeds, often reaching 3000 feet per miaute. AH three printing processes utilize similar quaHty newsptint which, essentiaHy, is made of groundwood or thermomechanical pulp. Presses are fed a continuous web of newsptint that unwiads from a feed roUer. Inks dry by absorption of Hquid iato the porosity of the substrate. Some evaporation of water ia a flexo pubHcation ink can accelerate the dryiag process. 

Flexo and gravure inks are both known as Hquid inks because of their low viscosity. The inks for both systems have basic components in common with inks for other printing processes. Vehicles disperse and carry the pigment, and also contribute most to the end use properties. Colorants provide color. Solvents dissolve resins in the vehicle and determine drying rate. Additives modify ink properties to overcome deficiencies. 

Rubber-mill chips are dissolved similarly to resins, to provide color concentrates. Dough mixer and chip concentrates must be diluted with solvent and other vehicles to make finished inks. Media milling is becoming a method of choice in both flexo and gravure ink manufacturing. Other high speed dispersing units, such as the Morehouse, Cowles, Kady, and others, are also used. 

Rotogravure Inks. Since there are no mbber or plastic components in contact with the solvents contained in gravure ink formulations, it is permissible to use solvents such as ketones and aromatic hydrocarbons which cannot be tolerated in flexo inks. This provides the gravure ink formulator with much greater latitude in regard to binder selection. In other respects the compositions generally are similar. 

Table 2. Commercially Used Flexo and Gravure Solvents ...

Flexo usage restricted to butyl mbber plates and rollers. 

Lamination Inks. This class of ink is a specialized group. In addition to conforming to the constraints described for flexo and gravure inks, these inks must not interfere with the bond formed when two or more films, eg, polypropylene and polyethylene, are joined with the use of an adhesive in order to obtain a stmcture that provides resistance properties not found in a single film. Laminations are commonly used for food applications such as candy and food wrappers. Resins used to make this type of ink caimot, therefore, exhibit any tendency to retain solvent vapor after the print has dried. Residual solvent would contaminate the packaged product making the product unsalable. 

Early fluorescent pigments were promoted and adopted for use in screen inks for poster boards and paints for safety applications. These thermoset pigments were not well-suited because of their poor fightfastness. Also, because of their relatively coarse particle size, their use in thinner film applications, such as gravure or flexo, was limited. 

Water-based flexo inks can be formulated with either a soluble toner or with the Day-Glo EPX Series which is a tme pigment and can be formulated like a conventional pigment dispersion. The Radiant Aquabest or the Day-Glo WST can be formulated in an alkaline water-soluble system to yield strong inks. They have limited shelf life and inferior fade, but do not necessarily requite additional binder. Day-Glo EPX must be formulated with a binder such as a hard resin or can be used with one of the soluble toners such as WST. The EPX Series has several advantages over soluble toners such as much superior fade, exceUent ink stabiHty, and some hiding power over kraft-type papers. A disadvantage of the EPX is its lower tinctorial strength than other fluorescent toners. 

Sulfonamide groups can be introduced into phthalocyanines to make them soluble in alcohols and glycol ethers. Their main appHcations are transparent paints, flexo and gravure printing inks, wood stains, plastics, and ballpoint inks. This includes products Hke Solvent Blue 24 (Cl 74380),... 

Includes fluorescent pigments for gravure, flexo, and screen inks. 

Another example of the coupling between microscopic and macroscopic properties is the flexo-electric effect in liquid crystals [33] which was first predicted theoretically by Meyer [34] and later observed in MBBA [35], Here orientational deformations of the director give rise to spontaneous polarisation. In nematic materials, the induced polarisation is given by... 

Wash deinking often used for flexo-printed waste and in older tissue mills, large water consumption. Flotation deinking for oil-based printings such as offset and rotogravure, technology from the mining industry. 

All members of this pigment family share good lightfastness, combined with poor solvent and migration resistance. These properties define and limit their application. Monoazo yellow pigments are used extensively in air-dried alkyd resin and in emulsion paints, and certain inks used in flexo and screen printing. Other applications are in letterpress and offset inks, as well as in office articles. 

Flexo and Screen Printing and Other Printing Processes... 

In applications where the pigment is fast enough to solvents to satisfy the requirements, it may also be used for offset, packaging gravure, and flexo printing inks. The resulting prints are soap, alkali, and acid resistant. They are not completely fast to paraffin and quite sensitive to butter and a number of other fats. P.R.14 prints are not fast to clear lacquer coatings and may not be sterilized. Heat stabil-... 

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