Solvent inks

Precipita.tlon. An ink may also be caused to dry by precipitation of its binder rather than by evaporation of solvent. This can be accompHshed by a dding a diluent, such as water in the form of steam or humidity, to a hygroscopic solvent ink system, which causes the solubiHty of the resin in the ink film to decrease sharply and causes it to precipitate when its tolerance for the diluent is reached. Eurther drying is accompHshed by absorption of the solvents into the stock and then by evaporation. Another form of precipitation setting is the quick-set mechanism. This utilizes resins held in solution in a relatively poor solvent, by means of a small amount of an exceUent solvent (called a sweetener) blended with it. When the ink film is printed on the paper, an amount of the solvents is absorbed reducing the content of the sweetener solvent to a point which causes the resins to precipitate and the ink to set. 

W-type inks use water, or mixtures of water and alcohol, as the solvent. Inks which are not of a recognized type are classified as X-type. The solvent required is specific to the ink formula and the ink maker makes proper recommendations. 

Inks for continuous ink-jet printers typically comprise dyes dissolved in water or solvent having salts added to make the ink conductive for electrostatic charging. Whenever waterproof printing is required, low boiling solvent inks ate used. For printers that ate used in office environments, water is used as the ink solvent. Using water-based inks, humectants may be added to inhibit drying of ink in the sump and surfactants ate added to wet the printing surface. 

Substances that frequently cause symptoms in chemically sensitive people include pesticides, perfume, fresh paint, new carpets, many building materials, solvents, ink, smoke, vehicle exhaust, industrial fumes, plastics, petrochemicals, many cleaning products... 

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. ... 

Similar to ink-jet dyes, dyes used for writing, drawing and marking materials fall into two categories water soluble dyes for aqueous inks and dyes for solvent inks [1,5]. Dyes are listed according to application in Tables 5.9-5.13. Many of these dyes can also be used for ink jet applications. However, ink jet dyes have to satisfy more stringent criteria with regard to purify and salt content. 

For commercial printing onto nonporous, hydrophobic materials such as plastics, metals, and glass, rapidly drying solvent inks which adhere to these substrates are needed. A typical solvent for these applications is methyl ethyl ketone (MEK). However, alternative alcoholic solvents tike ethanol and N-propanol have been introduced for ecological and safety reasons. The predominant color for industrial marking is black, and solvent soluble 2 1 azo chromium(m) complex, polyazo, Nigrosine, and sulfur dyes are used. Typical formulation of an... 

Solvent inks, interpreted literally, encompass a wide variety of inkjet inks. When speaking of solvent inks in this chapter, we will limit ourselves to inks based on organic solvents. 

This definition precludes aqueous inks, but further distinctions remain. There are solvent inks where the vehicle is a fluid with very low vapor pressure at room temperature. These inks are based either on glycols, or on oils and are used on absorbent substrates such as paper. The inks most commonly referred to as solvent inks are those in which the carrier is a solvent that evaporates or is driven off subsequent to printing. 

A further distinction, when referring to inkjet inks, is the printing mechanism. Solvent inks are used widely in drop-on-demand piezo inkjet printing (DOD PIJ) and in continuous inkjet (CIJ). To a lesser extent there is an effort to introduce solvents into thermal inkjet drop-on-demand (DOD TIJ). 

FORMULATING SOLVENT INKS FOR CONTINUOUS INKJET PRINTERS... 

For an in-depth understanding of the formulation of solvent inks for CIJ printers, we need to look at how CIJ technology works, the product applications and the history of ink formulation within the CIJ technology area. Although there are a few aqueous formulations used in CIJ printers, the vast majority of inks are indeed solvent-based, even if they are solvent/water or solvent/UV inks. Thus, solvent inks form the backbone of this industry and there are literally hundreds of unique solvent-based ink formulations being sold and used each day. 

There are many CIJ printers on the market today and each has its own set of physical requirements from an ink. The following is a basic list of properties into which the solvent ink formulations usually fall. 

As noted in previous sections, the colorant used in the CIJ solvent ink is a key component, which can often vary from application to application. Dyes tend to be used in these formulations for a number of reasons. In some instances the dye will give a color or property which is not possible when using pigments. Dyes, especially when they provide their own conductivity via a counter ion or residual salts, are usually easier to formulate with and provide ink stability, both upon storage and upon long term use in the printer. 

FORMULATING SOLVENT INKS FOR PIEZO DROP-ON-DEMAND PRINT HEADS... 

Radiation curable inks have been making inroads into markets where solvent inks reigned in the past, particularly wide format printing. UV and EB curable inks have the advantage of low emissions. In addition, these inks have an advantage over solvent inks in that they can be cross linked on the substrate, leading to durable prints, while the inks in the printer can be kept stable. 

Solvents have the advantage that they serve as a relatively inexpensive means with which to deliver a functional material to a substrate. One of the major drawbacks in the use of solvent inks are environmental issues. The environmental issues are both workplace related lists of volatile organic compounds that have restricted concentrations in the workplace, and broader concerns as expressed in regulations such as the Hazardous Air Pollutants (HAPS) hst that limits the amounts of specific compounds that can be emitted by an operation. In response to these concerns, many inks are now marketed with an environmental twist. 

Melinex 854. Fleat-sealable surface acceptable for both water and solvent ink systems.fi l... 

Uses Metalized dye for leather spray dyeing applies., wood stains, solvent inks, decorative coatings on metal foils and polymeric films Features Provides high lightfastness Properties Sol. in alcohol and various polar soivs. 

PEG-15 hydroxystearate solvent, injectables Glycofurol solvent, inkthinners 2-Hexanone solvent, inks... 

Recovery units are also more labour intensive and require more highly skilled operators than thermal destruction systems. Because of the capital investment in both the recovery unit and the purification system, and the technical limitations discussed above, recovery is normally only practical and economically sensible for single solvent inks at the largest printing sites. 

Flexography flek- sa-gr9-fe [fladhh + -o-+ -graphy] (1954) n. A typographic form of printing using rubber plates and relatively thin bodied resin-solvent inks. Formerly known as aniline printing. 

Rotary/platen press cleaning involves minimal exposure to only a few chemicals kerosene for the steel cylinder and a blanket wash for the rubber rollers. An aqueous solution of sodium hydroxide is used to clean many parts of the gravure press, whilst a typical cleanup solution will contain n-propyl acetate and toluene. Since the computerised presses now used in many larger establishments require little direct attention, solvents, inks and rubber gloves are responsible for most cases of dermatitis. 

The evaporated solvents, ink oils, and toxic gases such as carbon monoxide in the dryer exhaust are mixtures of hydrocarbons, i.e., carbon bonded to each other and/or to hydrogen in various lengths and configurations. The general term for these materials is volatile organic compounds (VOCs). Regulations for the total reduction of VOC emissions is a combination of destruction efficiency and capture efficiency. The United States is the only country... 

Anriidmintics industrial solvents, inks, dyes, varnish, paints, adhesives... 

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