Dryness of flexographic ink
from the current application situation, its printing matrix can be divided into two types, namely, porous matrix and non porous matrix. Water based flexographic ink is generally used for printing on the surface of porous substrate; Solvent based inks are used for about two-thirds of the printing on the surface of non porous substrates. The use of water-based flexographic ink at home and abroad is an increasing trend
1. Type: as mentioned above, flexo ink is a liquid ink, and its drying method is to penetrate into the matrix (paper) or volatilize the solvent
2. Preparation method: the solvent used in this low viscosity (CPS) liquid ink is based on dissolving the polymer in the ink. The typical solvents used are water and alcohol, as well as a small amount of ethylene glycol ether, monobasic and aliphatic hydrocarbons. Its film-forming polymers are polyphthalamide, nitrocellulose, rosin, lac and acrylic vinegar - usually one of these polymers is used to modify the other (for example, nitrocellulose can increase heat resistance; polyphthalamide can increase gloss and flexibility). In most flexographic inks, more than two polymers or solvents are generally used to achieve a balance in performance. Principle of flexible universal material testing machine: the degree of force and stretch of the pattern being stretched to the predetermined force value at a fixed rate or until the pattern is broken. The flexible printing ink system generally contains 7-15 different components, which constitute the total components of pigments, polymers, solvents and additives used in typical flexible printing ink
the following is a brief description of the preparation of solvent based ink and water-based flexographic ink:
1 Solvent based flexographic ink: as mentioned above, solvent based flexographic ink is mainly prepared to print non porous substrate surfaces
about 75% of plastic inks are alcohol soluble polyamide resin used by the manufacturing industry of spring assemblies and product quality supervision departments at all levels. Its representative reference formula is as follows:
component weight% polyamide resin 13s/s nitrocellulose 2* organic pigment 15 filler 5 plasticizer, wax 5 ethanol 55 ester 5100
note: * if white ink based on TiO2: is manufactured, this amount can be doubled and the amount of ethanol can be reduced
the following reference formula is modified nitrocellulose ink, which has good gloss and heat resistance, and is suitable for printing foil, coated cellophane and paper:
component weight% polyphthalamide resin 10s/s nitrocellulose 5* organic pigment 1. The action is more compact and fast, and the system operation is more reliable and efficient. 5 filler 5 plasticizer, wax 10 ethanol 50 ester 5100 if you need to print ink for coated cellophane, Then it is necessary to replace the film-forming agent in the above formula, that is, modified rosin, with acrylic resin, so as not to affect the heat sealing
at present, flexible plastic film for composite packaging is developing rapidly, which requires an ink, that is, composite ink is suitable for printing this plastic film, and then compounded with another plastic film or paper to make sealed packaging with good printing and heat sealing performance. The composite ink used for printing here does not contact the inner packaging or the air. This composite ink does not need gloss, nor does it need to have scratch resistance and last point friction resistance (because they are protected by the composite film). This kind of ink contains no wax or very little, so it will not reduce the adhesion between composite films
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