Analysis of the composition and function of UV ink.

The main components of UV inks are polymer pre-polymers, photoresist monomers, light triggers, auxiliary components are coloring pigments, fillers, additives (leveling agents, polymer inhibitors) and so on.
1, polymer prejudgment
polymerization pre-polymer is an important component to determine the performance of UV photo-oil coating, is the most basic component in UV ink, is a film-forming substance, performance on the curing process and the nature of the cured ink film plays an important role. Generally classified according to the structure of the skeleton

. Skeleton structure affects coating hardness, friction resistance, adhesion, light resistance, chemical resistance and water resistance.
pre-polymer from the structural point of view, the polymer is containing "C-C" unsaturated double-bonds of low-molecular resins, such as acrylic, methyl acrylamide, vinyl, acrylic and so on. The main epoxy acrylic resin, polyurethane acrylic resin, polyester acrylic resin, polyether acrylic resin, polyacrylate acrylic, unsaturated polyester resin and other resin types. Under the same conditions, the photo-curing speed acrylamide is the fastest, so most of the polymer is acrylic resin.
2, photoresist monosome (active thinner)
.UV ink and UV light oil in the coating need to adapt to the viscosity of the coating machine, generally by adding 20% to 80% of the monomer to reduce the viscosity of the pre-polymer, while the monomer itself polymerization, become part of the curing film.
active thinner, also known as cross-link monosome, is a functional monosome, its role in ink is to regulate the viscosity of the ink, curing speed and curing film properties. The active thinner structure also contains "C-C" unsaturated double bonds, which can be acrylamide, methyl acrylic, vinyl and acrylic. Since acrylic-based photoresuming is the fastest, most of the active thinners currently in use are acrylic monos. Because the quantity containing acrylamide base is different, can be divided into single-official energy group, dual-official energy group three categories, all kinds of official energy group active thinner release effect and curing speed are different. Generally speaking, the more official energy, the faster the curing speed, but the worse the dilution effect.
traditional active thinners, such as styrene, first-generation acrylic monos, etc., they are highly toxic, some acrylates monosomes have a very strong stimulating effect on the skin. In order to reduce the irritation of active thinners to the skin, there are usually two methods: one is the use of ethylene oxide, epoxy propane and ester-opened ring polymerization to increase the molecular weight of the mono body; In the use of alcohol addition to acrylamide base, so that multi-erbodyme monogamed skin irritation greatly reduced, such as the new glycol diacrylate using esterification synthesis, PH value (skin irritation index) is 4.96, and the use of addition synthesis, PH value reduced to 0.3.
has recently developed a number of high-performance monosomes, such as: alkyl acrylates, carbonate monoacrylates, mimi-based monoacrylates, cyclocarbonate monoacrylates, epoxy silicone monogides, silicone acrylates and vinyl ether monosyl monosylenes. When selecting monosomes, the following principles should be followed:
a, low viscosity, good dilution effect,
b, fast curing,
c, good attachment in the material,
d, small irritation to the skin, low toxicity,
e, no odor in the coating.
3, light trigger
light trigger is able to absorb radiation energy, chemical changes to produce an active intermediate with the ability to trigger polymerization, but also any UV curing system needs the main components. Light trigger can be divided into hydrogen-grabbing type and lysate type, hydrogen-grabbing type is the need to cooperate with a compound containing active hydrogen (commonly known as a booster), through hydrogen-grabbing reaction, the formation of free-forming, is a dual-molecule light trigger, lysate type is the light trigger by the laser, the molecule decomposed into free-form, is a single-molecule light trigger.
(1) hydrogen-grabbing type: in the case of xylene (BP), for example, when using xylene ketone alone, it is not available to light polymerization of ene monosomes, and the need for it to become a light trigger is different. The reaction is different alkyl and aromatic, and when hydrogen atoms are extracted from alcohols and ethers, oxygen can easily quench the excitation state of diphenylone. When extracting hydrogen atoms from amines, the amine system is not easily quenched for oxygen, and compared with the alcohol ether system, it also reduces the possible type of energy transfer to the monomorphic body because the ketone forms an excitation state and then forms an excitation state complex with the amine, which avoids the energy transfer to the oxygen molecule. Therefore, in practice, the amine system is generally used. In addition to xybenzene, these light triggers also include lysine-like thiosterone, which is commonly used in UV inks with 2-isopropyl thiopental.
(2) lysate type: In the case of sabbath ether, for example, sabbath ether was once the most widely used light trigger, characterized by the excitation state grams directly decomposed into two sessions of total freelance. The resulting free base can raise a monosome aggregation. The excitation life of the sabbath ether is short, not easily quenched for oxygen, nor quenched by styrene, so it can be used for styrene polymerization. However, even if the sabbath ether does not see light also has different degrees of thermal decomposition, storage stability is not good, generally to add stabilizers and blockers, is currently commonly used to rest dimethyl incense ether.
the principles to be followed in selecting light triggers:
a, high efficiency of absorption of light in the UV range,
b, good relative stability,
c, low cost.
4, other additives
additives are mainly used to improve the performance of inks, UV inks commonly used additives have stabilizers, leveling agents, desiccants, dispersants, waxes and so on.
(1) stabilizer: Stabilizer is used to reduce thermal polymerization during storage and improve ink storage stability. Commonly used against phenol, methylphenol, parabens, 2,6-two statins, etc.
(2) leveling agent: leveling agent is used to improve the leveling of the ink layer, prevent the production of shrink holes, so that the surface of the ink film flat, but also increase the gloss of ink printing.
(3) deblister: Desmoticant is used to improve the leveling of the ink layer, prevent the production of shrink holes, so that the surface of the ink film flat, but also increase the gloss of ink printing.
(4) Dispersant: Dispersant can make the pigment in the ink in the connection material is very good low wetting, so that the pigment in the ink has a good dispersion, shorten the grinding time when the ink is manufactured; Dispersants are generally surfactants.
(5) wax: wax is mainly used to change the fluidity of ink, improve the properties of water-resistant combined printing (such as regulating viscosity), reduce dirt, pull paper hair and other ills, and can form a smooth wax film on the dry surface of the ink film ii to improve the wear resistance of the printed material. In UV ink, wax also blocks the air, reduces oxygen blocking, is conducive to surface curing. However, the addition of excessive wax in the ink and the selection of the wrong wax varieties, will reduce the gloss of the ink, damage the ink transfer performance, extend the drying time.
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