What is the role of uv ink and eb resin?
Ink is one of the main consumables in the printing industry and a major factor in the reproduction of originals. Ink manufacturers are also constantly improving the printability of inks. Binders are the fluid component of inks. With the continuous development of modern industry, new types of ink binders are constantly being used. From the original binders with vegetable oils and natural resins as the main components, to the present, with synthetic resins as the main components. The ink industry has developed by leaps and bounds. Among the available synthetic resins, acrylic resins are the most widely used and can be found in products such as ultraviolet curing (uv) inks, electron beam curing (eb) inks, and water-based inks. The roles and reaction mechanisms of acrylic resins in the above inks are different and the following examples are given. I. Application of acrylic resin in uv ink and eb ink uv ink is an ink that changes from liquid to solid under certain ultraviolet light irradiation. uv ink has wide printing suitability and can be printed by offset, flexographic or screen printing. It has good printing performance on most substrates, and the ink dries quickly, with less organic volatile compounds (voc), and has an impact on the environment. Printed products are small, with strong adhesion fastness, good abrasion resistance, high gloss and other advantages. In recent years, uv ink in offset printing, screen printing, flexographic printing is widely used, its market share has a high annual growth rate, its growth rate far exceeds other types of printing inks. uv ink reaction mechanism is free radical polymerization or cationic polymerization. uv ink composition is important. The structure of the resin prepolymer in the formula and the activity of the functional groups determine the speed of the overall cross-linking polymerization reaction.
At present, the resin used to manufacture uv ink is mostly acrylic resin. Acrylic resins have unsaturated double bond “c = c”. This unsaturation activates the initiator acrylic resin for ink under UV irradiation, which triggers the chain. Reaction polymerization into solid resins, widely used in the manufacture of uv inks. The main acrylic resins used in the ink industry are epoxy acrylate resins, urethane acrylate resins, etc. Epoxy acrylate resin is made by the direct reaction of epoxy resin and acrylic acid. It has the characteristics of fast curing speed, high hardness of paint film and good gloss. uv ink using epoxy acrylate resin can achieve faster product curing speed. In addition, there is an epoxy acrylate resin, which is an epoxy oil acrylate resin obtained by reacting epoxy soybean oil and epoxy linseed oil with acrylic acid. It has low viscosity, good flowability and good pigment wetting and dispersion. However, the curing speed is slow and the film is soft, so it is generally used only as an auxiliary resin in uv ink. Polyester acrylate resin is made by direct esterification dehydration of polyester polyol and acrylic acid, which has good adhesion to materials. Widely used in uv ink. Low molecular weight can be used as a diluent, high molecular weight can be used as the main resin, but polyester acrylate resin high viscosity. If modified with fatty acid, not only can reduce the viscosity of the resin, but also can improve the moisturizing effect of the pigment. Wet dispersibility. Polyurethane acrylate resin is produced by condensation reaction of polyacrylic acid with diisocarbamic acid ethyl ester and ethyl acrylate. The molecular weight of polyurethane acrylate resin can be adjusted and the curing speed can be adjusted to suit the different printing requirements of uv ink.
Polyurethane acrylate resin has strong polyurethane bonds in its molecular structure, so it has high adhesion to plastic, metal and wood, but the cost of polyurethane acrylate resin is high. And temperature has a certain influence on viscosity, room temperature is mostly solid, should be used with active diluent. The following will be combined with a specific formulation of uv ink to introduce the curing mechanism of uv ink. Sheet-fed offset UV ink formulation example: (see Table 1) epoxy acrylate resin 45% benzene even marriage dimethyl ether 4% tetraethylene glycol diacrylate 23% 2-chlorothione 3% diphenylacetone 5% phthalocyanine blue bgs 18% polyethylene microcrystalline wax 2% uv ink drying mechanism is under the action of ultraviolet light, excitation photoinitiator to produce free radicals or ions, these radicals or ions and hydroxyl polymerization . The unsaturated bonds in the compound react with the monomer to form monomeric groups, and then these monomeric groups undergo a chain reaction to complete the curing process. Figure 1: light source → photoinitiator → free radicals —- → with vinyl – → polymer curing film of monomers and prepolymers to trigger the polymerization reaction, the molecular formula of the double bond breakage for Polymerization reaction acrylic resin for ink, to generate polymerized polymer resin. Tetraethylene glycol diacrylate as an active diluent in the ink mainly plays a role in regulating the viscosity of the ink, thereby regulating the printability of acrylic resins. eb ink and uv ink are active ink, drying mechanism is basically the same. In uv inks, photosensitivity to photons is excited by ultraviolet light. It activates the polymer and triggers the polymerization of double bonds in the resin and monomer.
eb ink relies on high-energy electron beam directly bombard the resin prepolymer, so that the resin and monomer double bond polymerization. eb ink used in the resin prepolymer, monomer and UV-curable ink requirements and reaction mechanism is basically the same, here is not repeated. Second, the application of acrylic tree in water-based ink Acrylic resin is not only used in uv ink and eb ink, but also widely used in water-based ink. Water-based ink as an environmentally friendly ink, with less organic volatile compounds (VOC) in the printing process, the health of the printing operator is harmless, the environmental impact is small. It is favored and is beginning to expand into the newspaper printing industry. Water-based ink is a liquid ink that uses water instead of organic solvents. The base component consists of an organic amine component, a solvent and an additive. The base component is organic amine or ammonia, the solvent is water and a small amount of alcohol, and the additives include defoamer, dispersant and wax. Water-based resin is an important part of water-based ink, which directly affects the adhesion performance, drying speed, anti-fouling performance and heat resistance of the ink, and also affects the gloss and ink transfer performance. Therefore, choosing the right resin is the key to water-based inks. It must have easy to form water-soluble salts, good affinity with colorants, high adhesion fastness after printing into film, wear resistance, scratch resistance, good heat resistance, good gloss, etc. High, and need good water release, easy crosslinking and film-forming properties when printed and dried. Commonly used adhesives can be divided into three main categories: water-soluble adhesives, diffusion adhesives and alkali-soluble adhesives.
The main resins used in adhesives are acrylic, polyamide and polyester, but the commonly used ones are acrylic. Acrylic resin is an efficient wetting agent and abrasive, helps dispersion and coloring, good gloss, can reduce the amount of pigments, and is good for environmental protection. According to the practical application in water-based inks, acrylic resins can be divided into two major types: solution type and emulsion type. Compared with these two types, the former is more compatible and stable than the latter. Solution type acrylic resin usually has a molecular weight of 5000-10000 mw. It does not have the characteristics of emulsion state, but has good solubility and gloss, and has good wettability as a carrier and dispersion of pigments. However, its disadvantage is slow drying and poor continuous film formation, so it is generally not used alone, but combined with other emulsions. There are many varieties of emulsion acrylic resins, but the state of emulsion particles formed by different components is also different, and the physical and chemical properties are also different. There are usually two kinds of colloidal dispersions and conjugate emulsions. Colloidal dispersions are mostly copolymers of acrylic acid and styrene, with molecular weights between 15000-40000mw. Since the particle number is less than the limit required for emulsion, it is not a true emulsion, but the particle size is large enough to add a large amount of water. Dilution. This emulsion is generally used for printing inks for corrugated boxes. Junction film emulsions have good oil and water resistance and good gloss due to their high molecular weight. It has good adhesion on non-absorbent substrates, low glass transition temperature, good film formation and resistance, and is widely used for printing on impermeable and dry substrates such as films and metal foils. The following combined with the reference formula description: (see Table 2) ingredient ratio glycol 0.5% acrylic resin 26% isopropyl alcohol 1.5% pigment carbon ink 16% defoaming additives 1% ammonia (28%) 4% water 50% phthalocyanine blue b1% water-based ink drying is mainly volatile drying and osmotic drying, drying mechanism is the main resin in the binder contains carboxyl (acrylic resin) (-cooh), adding After adding a certain amount of amine group (-nh2) alkaline substance, the amine group reacts with the carboxyl group in the resin to produce water-soluble organic amine salt. In the drying process of the ink, after the oxygen evaporates, the resin in the ink returns to a water-insoluble ink film, thus completing the drying and curing of the ink. The above formula requires strict control of the amount of ammonia, and generally control the ph value of the ink.
UV Photoinitiator Same series products
|Ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate
|Sinocure® 819 DW
|Irgacure 819 DW
|1-Hydroxycyclohexyl phenyl ketone
|Benzene, (1-methylethenyl)-, homopolymer,ar-(2-hydroxy-2-methyl-1-oxopropyl) derivs
|Difunctional alpha hydroxy ketone
|Benzeneacetic acid, alpha-oxo-, Oxydi-2,1-ethanediyl ester
|(4-Methylphenyl) [4-(2-methylpropyl)phenyl] iodoniumhexafluorophosphate
|Sinocure® 6992 MX
|75482-18-7 & 74227-35-3
|Cationic Photoinitiator UVI-6992
|71449-78-0 & 89452-37-9
|Mixed type triarylsulfonium hexafluoroantimonate salts
|4-Thiophenyl phenyl diphenyl sulfonium hexafluoroantimonate
UV Monomer Same series products
|Dipropylene Glycol Dienoate
|(10) ethoxylated bisphenol A diacrylate
|Ethoxylated trimethylolpropane triacrylate
|(4) ethoxylated bisphenol A diacrylate
|Sinomer® GPTA ( G3POTA )
|GLYCERYL PROPOXY TRIACRYLATE
|(4) ethoxylated nonylphenol
|Neopentyl glycol diacrylate
|Phthalate diethylene glycol diacrylate
|Polyethylene Glycol Diacrylate
|Poly(ethylene glycol) dimethacrylate
|NEOPENTYL GLYCOL PROPOXYLATE DIACRYLATE
|Triethylene glycol dimethacrylate
|Tripropylene glycol diacrylate