With the improvement of people’s living standards , food packaging also put forward higher requirements for packaging inks in extraordinary attention . Ink as printed materials, should be required to meet a variety of different functions , such as non-toxic, heat, cold , solvent , oil , abrasion and corrosion -rays. Internationally recognized food printing ink used must comply with the principle of non- transfer ; may not use conventional inks printed on the surface within the food packaging ; printing manufacturers must ensure that the printing ink solvents entire evaporation, ink requires cured completely and achieve application sectors corresponding standards. Thus , the role of food packaging and printing ink in the extraordinary. The following characteristics from food packaging inks are used, with regard to adaptation printing , printing materials used are described .

Benzene -soluble chlorinated polypropylene ink is currently the most extensive use of plastics mainly for food packaging printing inks.

Whether such inks are mature manufacture and use of technology , mainly used for BOPP ( biaxially oriented polypropylene ) material in India , and the use of gravure clamshell packaging . Although such an ink excellent printability , good finishing properties, fast drying, but due to the relatively high toxicity of toluene , the high value of the residual solvent printed ; chlorinated polypropylene and the heat stability is poor, and the production during storage , easy to release chlorine to form hydrogen chloride, the ink was strong acidity , the printing plate roller serious corrosion problems , so that the ink tends to be eliminated. Because
As people have realized the benzene -soluble ink can damage the ozone layer , in the course will result in harm to workers’ health and safety , and packaging products remaining in the residue in food packaging under certain conditions would cause a certain degree within pollution. So in Europe , and some countries have banned or have been developed to control the use of aromatic solvent inks. Therefore , the development of environmentally friendly inks with food hygiene requirements is a serious problem .

Environmentally friendly ink should neither pollute the environment , without causing harm to the operation of worker ‘s body, but also will not damage the interior of food .

1 . Water-based ink

The vast majority of domestic water-based ink is used in flexo packaging printing ink , which is mainly composed of water-soluble resins, organic pigments, solvents and additives processed by the relevant composite grinding. Water-soluble resin is water-based ink binders , often used in domestic water-soluble acrylic resin as binders modified , its heat resistance, weather resistance, chemical resistance, stain and gloss etc has significant advantages , either directly dispersed dissolution or synthetic polymer emulsion , have shown excellent performance , water-based ink does not contain volatile organic solvents , not only can reduce the toxicity of the residual printing , and can prevent electrostatic contact with flammable solvents fire , is a new plastic trays ” green ” printing ink. Water-based inks also replace benzene -soluble ink the best products.

2 . UV (LIV) curable ink

UV -curable inks are ultraviolet light irradiation means in a certain wavelength , the ink binders in the crosslinking reaction , the transition from liquid to solid ink curing is completed , the link material before it is dissolved , i.e. firmly macromolecular prepolymer forming the ink film.

UV packaging design -curable flexographic printing ink is mainly used for the plastic packaging flexible substrate , which consists of a prepolymer , a reactive diluent , pigments , additives , photoinitiators / composite components. Wherein the selection of the reactive diluent of the ink formulations migration affects the reaction ; additive properties of the ink ( printability , ink migration resistance, substrate wetting , friction coefficient, wear resistance, and dispersion stability of the pigment resistance ) , and adjust the print odor ; required spectral range of ultraviolet light absorbing pigment as small as possible . Ideal pigment dispersion should have a good , good leveling , strong coloring plastic packaging box , irradiation of ultraviolet light absorption in the small , the polymerization reaction vac tray without prejudice to other characteristics.

Should note that the use of UV-curable ink -related inhibition of the polymerization reaction , the surface tension and wetting of the ink viscosity and humidity expansion of the printing plate and the like. Because of the poor adhesion of the ink to the plastic , thus the need for a plastic substrate made ??flame treatment or corona discharge treatment to improve the adhesion of the plastic surface .

3 . Electron beam-curable ink (EB ink ) refers to an electron beam curable inks in high energy electron beam irradiation can be quickly converted from a liquid to a solid ink , also known as EB ink. High electron beam energy , the solid pigments and fillers with a strong penetrating power , the case of the pigment plastic box ink is absorbed or filler will not impede the ink drying inside the membrane will not be affected . EB ink mainly composed of a pigment , binders , auxiliary agents , due to curing of the ink is achieved by an electron beam , so the choice of binders have specific requirements , the main component is an acrylic resin and participate in the reaction the reactive monomer . ,

Most of the food and beverage packaging industry uses electron beam curing printing, printing to offset printing. EB ink printing industry to adapt to high-speed , multi-color printing once the direction of development . Foreign applications have been developed in the 1980s , the country has only recently began to apply . As the electron beam energy saving assimilation ink , solvent-free components , the environment , the packaging is no pollution , short curing time, processing speed, high-volume , low dot gain , imprinted brightness is good, with wear and resistance to chemical attack etc., so this technology is the rapid diffusion and application , especially in the field of food packaging application prospects. The main difference LIV EB curable ink and the ink compound that is linked photoinitiator when EB was added an amount of the ink photoinitiator can be cured with ultraviolet rays . Thicker EB curable ink , the ink without photoinitiators , the cost is relatively low compared to LIV ink, electron beam curing equipment investment but higher than the curing LIV .
4 . Digital printing inks

Digital printing technology is increasing as people ‘s demand for personalized packaging penetrate into the food packaging and printing industry. Can be achieved using digital printing technology sufficiently high resolution image can be desirably reproduced image details . In addition, the digital printing technology to provide more efficient services in small quantities . Digital printing ink according to the printing method adopted can be divided into plastic packaging design : dye ink jet printing , xerographic toner solids and liquid ink electronic digital offset and the like.

After being heated to melt the toner is fixed on the substrate by a ceramic crystal materials . Printing materials are mostly foils, aluminum , PET ( polyester ) , paper, etc. , and is suitable for printing roll. Suitable selection of the fixing temperature of the clear plastic packaging toner is important because the best fixing temperature of the toner fusing can be well controlled process. Toner should have some flexibility, ease of printing materials folding process . Solvent resistance for static digital printing is also extremely important , solvent resistance bad print will not be completed after the procedure , as light , film and so on.

In the green and packaging requirements for food safety, high quality, multi-color printing today, printing inks should adapt to the times , toward benzene , environmental protection direction.

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