UV-print inks

Radiation-Curable Polyester Coatings. Radiation-curable polyester paints (see also Section 3.7) are particularly suitable for coating flat surfaces (strips, boards, sheets) and for temperature-sensitive substrates (paper, plastics). Acrylate-modified polyester resins are used for UV printing inks, UV varnishes for paper and plastics, as well as for pigmentable, electron beam-curable gloss and matt paints [2.86]. Radiation-curable polyester paints are also suitable for metal coatings with good elasticity. 

Uses Slip agent, leveling agent for UV printing inks and overprint varnishes... 

During the past 15-20 years, the use of UV-curable acrylates in inks and coatings has increased tremendously. In the can-coating industry, UV-printing inks are used on beverage and beer cans as well as on crown caps and aerosol containers. UV-curable acrylate coatings are used as wood finishes, mat varnishes, parquet varnishes and sealers, and as varnishes and coatings in the manufacture of furniture (Bjorkner... 

For operatives who had traditionally worked with alkyd systems, the acrylics received some criticism on account of the odour. For this reason, polyesters were found to offer flexibility advantages over acrylics, but suffered from pinholing tendencies and proved to be more critical for adhesion in the case of UV printing inks. 

Graphic screen printing ink appHcations on mirrors (uv-curable inks)... 

Inks. Refined kaolin is a common ingredient in a large variety of printing inks (qv). In addition to extending the more expensive polymers present, ka olin also contributes to improved color strength, limits the penetration of the ink into the paper, controls rheology, and improves adhesion. Kaolin for this appHcation must usually be as white as possible and free from oversize particles. Surface treated clays are used to improve compatibiHty with oil-based ink. Clays can also be an ingredient in the newer water-based or uv-cured inks. 

Case study UV drying printing inks in packaging printing ... 

Direction of innovation (from the standpoint of market actors - 6al Some companies made bad experiences with skin irritation cansed by acrylates and photo initiators in the latmched UV-drying printing inks (warning by employers hability insnrance and trade union 1981) and the formation of bertzene in catiorric processes. 

Also the Quality Community on mineral wool and the industiy regulation on low-chromate cement are examples of a co-operation for hazardous substance substitution that does finally function. The example of UV-drying printing inks, on the other hand, does demonstrate under which combination of negative network effects in the innovation system the diffusion of a technology can also fail (at least provisionally). 

Examples of such effects are the SubChem cases for the substitution of DEHP as a plasticiser in PVC by other phthalates (instead of switching over to underbody hard shells), optimisation of formulations in water-soluble cooling lubricants (instead of switching over to minimum quantity lubrication) or the use of water-based flexographic inks (instead of switching over to UV-drying printing inks). 

Carbon black includes several forms of artificially prepared carbon, such as furnace black, channel black, lamp black, and animal charcoal. It is a finely divided form of carbon consisting of particles of extremely fine size. It is obtained by partial combustion (in 50% required air) of vapors of heavy oil fraction of crude oil in a furnace or by thermal cracking of natural gas. Carbon black is used in many abrasion-resistant rubber products including tire treads and belt covers. It also is used in typewriter ribbons, printing inks, carbon paper, and paint pigments. It also can be an absorber for solar energy and UV radiation. 

Zinc oxide occurs in nature as mineral zincite. It is the most important zinc compound and has numerous industrial applications. Zinc oxide is the pigment in white paints. It is used to make enamels, white printing inks, white glue, opaque glasses, rubber products and floor tiles. It is used in cosmetics, soaps, pharmaceuticals, dental cements, storage batteries, electrical equipment, and piezoelectric devices. Other applications are as a flame retardant, as a UV absorber in plastics, and a reagent in analytical chemistry. A major application of zinc oxide is in the preparation of most zinc salts. In medicine, the compound is used as an antiseptic, an astringent and a topical protectant. 

UV inks have been readily and successfully adopted by flexographic label printers, many of them having had several years of experience with letterpress UV systems. Because the common thickness of the printed ink in flexography is typically 2 to 4 pm, in multicolor printing it is often necessary to cure individual layers of inks by UV. With radical UV-curable flexographic printing inks, it is possible to achieve printing speeds of 250 m/min (750 ft/min) or even more.22... 

The chemical drying of printing inks involves oxidation (where unsaturated oils are cross-linked by atmospheric oxygen) or polymerization of binder constituents by UV light. The first setting is often by striking in, even with chemically-dried printing inks. 

Chemistries available now for the UV-curing of printing inks include ... 

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