Characteristics of the most popular matte ink and

Characteristics and printing technology of frosted ink (Part I)

Abstract: frosted ink is deeply loved and widely used in the field of packaging. The characteristics, application scope and precautions of frosting ink were introduced. The printing technology and quality control of frosted ink are discussed in detail

key words: frosted ink packaging printing plate printing

UV curing (UV) ink has been developed and launched for more than 30 years. It is an environmental friendly ink that has developed rapidly in recent years. It is widely used because of its instant UV curing (drying), non volatile solvents, simple and convenient application. There are many kinds of UV inks, including UV sanding, UV icing, UV foaming, UV wrinkles, UV refraction, UV gemstones and other inks. Among them, UV testing machine is also easy to destroy the sanding ink. Using the printing defects in the ink to produce scattering under the light, it will be printed on cardboard and other packaging materials, just like smooth metal treated by corrosion and carved sanding surface, producing a unique visual effect, It makes the packaging look noble, solemn, elegant and novel. It is widely used in the exquisite and unique packaging and printing of cigarettes, wine, cosmetics, health products, food, drugs and other products. However, due to the different substrates of UV matte ink, there are certain differences in formula and operation, while the level of formula design and operators are uneven, and there is no general standard for this ink in the world at present. Because the printing operators are not experienced enough in the use of this ink, there will be some problems in the printing process, especially in mass industrial production, which will affect the printing effect. Therefore, it is necessary to be familiar with the formula characteristics and use skills of UV frosting ink in order to be handy in printing and print exquisite prints satisfactory to customers

a main feature and application field

frosting ink is also called metal like etching ink, which can be divided into UV curing ink and non UV curing ink according to the drying method. Due to the high temperature drying, non UV curing frosting ink is easy to make paper, etc. 5 With the function of holding force, the substrate is deformed, and the ink does not meet the requirements of environmental protection, so it has been basically eliminated at present. UV sanding ink is a new type of UV curing ink, which takes UV curing as the drying method. It is an ink that is cured into a film instantly after the crosslinking polymerization reaction of the ink layer under the irradiation of UV light. UV sanding ink has the characteristics of fast drying speed, small paper deformation, thick ink layer, rough, not resistant to folding and rubbing, which can greatly reduce the back rubbing dirt, and meets the requirements of green printing. UV sanding inks are made up of 1.3 billion tons of food waste or consumables and binders in the world every year. Main agent (organosilicon) L5 ~ 3O μ M mainly plays the role of sand; The binder consists of UV curing agent (UV curing resin or photopolymerizable prepolymer), cross-linking agent, photosensitizer, polymerization inhibitor, photopolymerization initiator, organic pigment and additives. Among them, photopolymerization initiator is the most important part of the whole UV ink, which is the beginning of photopolymerization reaction. The curing process of UV ink is the reaction process of photopolymerization initiator. Photopolymerization initiator is equivalent to the action of atomic group, which can produce chain reaction. It has photosensitivity. After receiving light, it becomes an excited molecule, which spontaneously splits into two or more atomic groups. These atomic groups undergo chain polymerization, which is the curing process of UV ink. UV curing agent has an effect on the curing speed, gloss, adhesion, wear resistance and clarity of the ink; Photosensitizer has photosensitive effect, and its photosensitive range is mostly 360 ~ 420 mm; The crosslinking agent can crosslink with unsaturated polyester to form a substance, which improves the film-forming property; Polymerization inhibitor acts as polymerization inhibitor in the process of UV curing polymerization, and its monomer does not polymerize with unsaturated resin; Additives in UV ink mainly refer to pigments, which mainly play the role of ink coloration with organic pigments. UV frosting ink ink is short and thick, in which the diameter of additive particles is about 15 ~ 30 μ m. Therefore, after printing, due to the rough and uneven ink film surface, diffuse reflection (the so-called sand surface effect) is formed under light, and the film surface gloss is dark. Where there is metallic luster without film surface, under the light, the reflection is positive reflection, and the luster is strong, so the place with film surface is dark and concave, and the place without film surface is bright and convex, and the two effects are diametrically opposite. In order to reflect the inherent gloss of the substrate, UV sanding ink generally stirs photosensitive resin and other materials into a light transparent paste, but it can also be added to make color etching ink, and transparent ink should be used instead of ink with strong hiding power. UV imitating etching ink with excellent performance must first have good particle distribution and three-dimensional sense, and good etching effect. Only after printing can it produce satisfactory artistic effect. It is also required to have good adhesion and softness. Many cigarette and wine boxes will be rolled. If the softness is not good, it will burst, which will seriously affect the product quality. It also needs to solidify quickly, store for a long time, have good hand sensitivity, and cannot be too rough, otherwise rolling will occur in the cigarette, wine and other packaging production lines. The ink used for printing cigarette and food packaging must also have low odor, be safe for human health, and meet the requirements of food hygiene and green printing

uv sanding ink can be applied to flexo, offset, plate printing, etc., but plate printing has the best effect. UV ink has the characteristics of instant curing, high production efficiency, no volatile solvent, no solvent erosion and damage to the printed matter, no pollution to human body and environment, and no ink blockage. Therefore, it can print lines of the best quality with a very fine eye. The ink concentration is stable, and it will not cause uneven phenomena of too thick or too light due to different concentrations. The ink will not be dry and solid, and there is no odor of solvent; The UV curing speed is very fast, and the UV equipment is small, occupying less plant space. Most of the substrates suitable for UV matte ink printing are gold, silver paperboard or other paper plastic composites with strong mirror effect. Because the printed matter has a strong sense of sand, beautiful and elegant, it has a good packaging and decoration effect. For example, when printed on high gloss gold and silver mirror paperboard, the substrate is under direct light, and the small particles in the ink diffuse the light, forming a strong contrast, as if the mirror is corroded and produces a feeling of depression, The graphic area without ink has a protruding feeling due to the high gloss effect of the paperboard mirror, which makes the printed matter have a metallic gloss and a relief three-dimensional feeling after etching, producing the effects of sanding, matte and chemical etching, making the printed matter appear elegant and solemn, and greatly improving the decorative grade and artistic appreciation value. At present, frosted ink has been more and more favored by people in packaging and printing, and its application field has been continuously expanded. It is mainly used for the packaging and printing of cigarettes, sprinkles, cosmetics, food, greeting cards, clothing, etc., and it can also be used for special printing on the surface of glass products, stainless steel products, imitation metal signs, etc. According to the different thickness of sand mold, UV ink can be divided into many different models to adapt to the sand mold effect of different thickness. The common ones are coarse, medium and fine. For different substrates and needs, different types of inks and coarse and fine sand molds are used to produce different etching effects. For example, type A has low odor, good etching effect, excellent fastness and softness, and can be used for printing high-end cigarette, wine, moon cake, clothing and other packaging. Type C is a low-grade ink with low price. Type D is a foaming ink. The etching particles are very rough and have special effects. Type E is a super fine ink, which has a very fine and uniform sense of particles, and no residue, but the cost is expensive, so it is mostly used in some high-end packaging with special requirements. UV sanding ink will not dry until it is cured by a certain intensity of UV light. UV ink selectively absorbs UV light, and its drying is affected by the total energy of UV light source radiation and the distribution of light energy of different wavelengths. Under the irradiation of UV light, the photopolymerization initiator in UV ink absorbs photons of a certain wavelength and forms free radicals or ions in the excited state. However, the color after tempering is different. Through the transfer of energy between molecules, polymers such as polymeric prepolymers and photosensitive monomers become excited states, resulting in charge transfer complexation. These complexes are continuously crosslinked and polymerized, and solidified into films. Therefore, it should be determined according to factors such as the thickness of the ink layer and the belt speed of the light curing machine. The light curing machine is equipped with a cooling device to avoid thermal deformation failure of composite paper when passing through the light curing machine. Adjust the curing speed and lamp distance during operation, otherwise it will be easy to peel off and poor adhesion. Insufficient light curing function will make the ink dry insufficient, cause printing adhesion, and make the metal texture worse