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First, the position of flexo printing in their respective printing changes we often hear the domestic experts and manufacturers into: Flexographic printing is flat, convex, concave, soft, screen printing in the fastest growing and sustainable development of printing Flexo is the only durable plate in Letterpress; flexographic printing is the most promising printing method for packaging and printing. It is mentioned that this statement has not been exaggerated. Table 1 is the statistics and prediction of the ratio of BRUNO to the United States in 1997 and future flexo printing in various types of printing in 1988.
Similarly, there are similar trends in Europe. The Asian, African and Latin worlds have not yet formed such a clear state of affairs. However, in the long run, they are bound to develop in this direction.
Second, the new meaning of the water system flexo version and its advantages of the previous water flexible version, mainly refers to the water development flexo version. Today, water-based flexographic plates, in addition to development with water, also dissolve in water and disperse the photosensitive composition to coat a plate material and even a water-based ink. In the meantime, Wen Hao, in order to achieve the goal of saving resources as much as possible and reducing pollution, strives for a full range of water systems. This article discusses water developing flexo plates.
The advantages of water-based flexo are:
1. No chlorinated roast chicken (trichloroethylene, trichloroethane, perchloroethylene, etc.) is used for development. There is no problem of releasing chlorinated hydrocarbons into the atmosphere, rivers, and the surface, reducing the damage to the atmospheric ozone layer and the surface. The pollution achieved the so-called "green development."
The Monterey Protocol, enacted in 1987, restricted RCIn's production and emissions. In 1991, China made a formal commitment to the protocol. Therefore, traditional flexographic plates for halocarbon development must find new strategies.
2. It is beneficial to the operator's health and improves the production environment.
3. Save resources and avoid waste of solvents.
4. Avoid flammable, explosive and unpleasant smells when using non-chlorinated hydrocarbon organic solvents.
5, the developer cost is low.
Of course, there are some problems with the flexible version of the water system, which will be discussed later.
Third, the flexibility of the composition of the water system and classification Flexibility of the water system can be divided into two categories from the form: liquid curing and solid cross-linked dissolution type. The former is also referred to as a liquid photosensitive flexographic plate, the latter also referred to as a solid photosensitive flexographic plate.
1. Water-based liquid photosensitive flexo plate This is a type of flexographic plate developed on the basis of liquid photosensitive resin relief. As is known to all, the LETERFLEX version developed by Grice in the 1970s and the commercialized AR version of Asahi Kasei Corporation in Japan, in which the plate material with low hardness is very close to the flexographic plate, and is generally developed with alkali water. In the past few years, the United States, Western Europe and Japan have developed and developed water-developing liquid flexible plates, which have improved the flexibility, elasticity, strength, water resistance, and printing resistance of cured plates. This kind of flexible version has low resolution and poor accuracy of plate thickness. Its chemical composition is as follows:
(1) unsaturated resin + ethoxylated or propoxylated monomer or oligomer + photoinitiator. The main resin, unsaturated resin, is generally formed by condensation of unsaturated dibasic acid, saturated dibasic acid and polyetherdiol. This system is easy to obtain raw materials, simple synthesis, low cost; in addition to the solidified plate after the strength, resilience and poor print force.
(2) A system composed of unsaturated polyurethane plus the aforementioned monomer oligomer and photoinitiator. Since this is a design that replaces all of the unsaturated polyesters in the previous composition with a polyurethane obtained by modifying a low-molecular-weight polymer of the ester chain diol with unsaturation of the main chain 蔌 side chain with a diisocyanate (such as HDI), it is cured. The product's strength, resiliency, and other similar properties are significantly improved, becoming the mainstream of liquid-sensitive flexographic plates.
(3) Liquid polybutadiene, modified polyisoprene and other side chains with ethylene vinyl oligomers plus polythiol compound plus hydrogen abstraction photoinitiator. The design idea is similar to the LETERFLEX developed by Grice, but the starting materials are different. The so-called modified body is made to have a hydroxyl group or a carboxyl group so as to achieve water development.
(4) A low-molecular-weight liquid polyamide synthesized from polyether diamine is used as a host resin system.
2, water-based solid photosensitive flexible version This is not the current attention of the public see the flexible material, although the plate pre-molding is difficult, but the plate thickness and high precision, plate making operation is simple, fast and convenient, the resulting plate resolution, The performance is similar to that of the solvent-developed flexographic plate. The chemical composition of the main resin classification is: (to be continued)
In the past two years, new developments, new designs, and new results that are close to or in practical use have been emerging in the flexible version of the water development system, and the latest developments in this area are outlined.
January 26, 2019