In the packaging printing, with the printing technology and equipment continue to improve, as well as the increasingly fierce competition in goods, it is printed on the packaging requirements of the appearance of more and more attention has introduced novel specific method of packaging and packaging print surface treatment technology , in which technology has been polishing the application of universal, so that the packaging of goods to a new height. Glazing not only protect the print, but also changed the texture and the appearance of printed visual effects, and promote sales. Consumers in print or in the increasingly high demand for packaging, the printed matter printed matter has become a value-added glazing and modern goods an important means of promotion.

Polishing characteristics and the impact of packaging a major factor in the quality polish

Alone have been printed on the completion of the printed surface of coated with a layer of colorless, transparent coatings, thin film layer was bright. When polishing products in India as a result of coating the surface of the stream level, and enhance the printing surface smoothness, not only improves the surface gloss of printed matter, and to improve the surface properties of the printed matter to enhance the light-fastness properties of ink, the ink layer to increase heat and moisture capacity, served to protect the printing machine, the role of landscaping products, has been widely used for book covers processing and packaging, catalogs, substantially decoration, posters and other printed matter in the surface processing.

Many of the methods of polishing by polishing polymer coatings can be divided into oxide coatings glazing, glazing coatings solvent evaporation, heat-curable coatings glazing, light-cured coatings, such as polishing. Coating according to polish coating can be divided into polish, printing glossy coating on the light and special coating polishing machine. If they could be divided into polishing equipment, polishing glazing machine and printing machine interaction. Moreover, the product can polish the whole surface is divided into light, the local polishing, matting, art polishing.

Regardless of the polishing techniques and materials, are required to have a good quality polish to achieve the intended purpose. From the material point of view, to polish the main factor in the quality of printing paper, printing ink and paint polish polish between good fit.

(1) printing paper. Printed on glossy paper, coated paper, the greatest impact is smooth and absorbent surface, they affect the leveling of the coating, and the impact of coating formed on the surface of the printing of high-liang film smoothness. High degree of smoothness of paper, paper surface contact with the coating layer, and coating leveling easy to form the high smoothness of the membrane surface. The surface of absorbent paper, and paint flow normally, paper fibers absorb the paint too quickly, making the flow of paint to deteriorate, it is difficult to leveling. In contrast, the weak absorbent surface of paper, paper fiber coating to absorb too slow, not easy leveling of coating solidification conjunctiva, it is difficult to form a high smoothness of the light membrane. Therefore, to select a different paper to match the paint, polish coating leveling adjustment time, conditions such as drying temperature.

(2) printing ink. Ink ink particle size effects of the wetting layer and thus the impact of the role of the flow coating and brightness level. If the ink particles, and India is bound to rough surface, wetting is not easy, not easy leveling.

(3) glazing coatings. Glazing Glazing impact the quality of paint is also a major factor, not only to have the polish coating colorless, tasteless, non-toxic, strong sense of gloss, chemical resistance, fast drying properties, but also transparent, and difficult to change, with more Sophie good flexibility, heat resistance, leveling, and adhesion of. Paint and polish the greatest impact on the quality of the polish of its viscosity, followed by surface tension and volatile solvents. Paint as a result of volatile solvents, permeation, diffusion, such as less and less effect, a gradual increase in viscosity. Power leveling took place is the surface tension coating, the surface tension of the coating in as far as possible, the smallest contraction into the shape of the surface of the process to have traces of leveling the surface into a smooth surface. Therefore, the coating surface tension convection-ping has a greater impact.

Two main types in use on varnished

Attention should be paid to the issue of

Paint polish can be divided into oxidative polymerization-type (mainly relying on the reaction with oxygen and dry film-forming polymer), solvent evaporation type (mainly dependent on the solvent evaporation coating film drying, leveling it, and applied to a variety of grade of high-volume printing glazing), heat-curing type (mainly relying on the resin and catalyst react when hot dry film), light-cured type (through-ray irradiation polymerization coating molecules conjunctival drying, glossy coating, and film resistance grinding, folding, heat), etc. 4. At present, the development of better and have better prospects for UV Varnish and Varnish Waterborne.
               
Varnish 1.UV the use of technology and the exclusion of a number of failures by UV Varnish Photoinitiators, prepolymers (oligomers), monomer (reactive diluent), additive (leveling agent, plasticized agent, antioxidant) and so on. At the appropriate wavelength and light intensity of ultraviolet radiation, the photoinitiator was inspired to produce radicals, triggered the prepolymer and monomer unsaturated group (typically acyl-propylene) polymerization occurred, and ultimately into a solid from the liquid rapidly generally only 0.1 to 0.3 seconds.

Print glossy UV coating are mainly oil and UV curing process of the two. In fact, the printing ink itself is coated in the process of the substrates, and UV Varnish can also be coated by printing method to the substrates, but require dense surface of substrates, non-dialysis varnished, because the viscosity of Oil much lower than the ink. Coated paper, white paper, gold paper, plastic film, etc. can be UV coated oil.

UV Varnish coated on the substrates, varnished leveling after a period of time zones into the ultraviolet radiation curing. Curing process is the process of chemical cross-linking, that is, prepolymers, monomers in the unsaturated carbon-carbon double bonds (liquid) Photoinitiators accept delivery of energy into each other cross-linked polymer network structure of the molecule (solid). However, with the UV curing of thick oil, time and changes in the intensity of UV radiation. UV radiation energy transfer and the relationship between oil thickness is reduced index. Approximately 90% of the UV energy in the upper absorbed within 1 micron, 2 microns on the lower can only be 9%. To make the lower 2-micron also get the same energy, the initial energy of UV irradiation to increase by 10 times. Coating thickness generally only 3 to 5 microns, the lower Varnish curing almost simultaneously. However, when thick coatings (such as wire mesh machine, polishing machine) will be curing the upper, middle and lower classes is not curing phenomenon.

Curing change over time, a large number of Photoinitiators lead time is generally 0.1 to 0.3 seconds, but the remaining part (not the full response) Photoinitiators will continue to respond to 6 to 24 hours after the so-called polymerization. If the beginning of the excessive light, UV will be as a result of oil and after polymerization becoming brittle, so when UV exposure polish should not be too large.

The use of UV curing equipment, generally according to the first with a lamp and lamp with appropriate adjustment according to the distance of objects (typically 5 ~ 15cm), if not a light-curing, curing light should be added to enhance the exposure. Curing with UV radiation changes in UV intensity per unit area increases, will accelerate the curing rate, but the relationship is not linear but increased several times. UV Varnish is applied to high-grade glossy print.

In the use of UV light, due around the tube to maintain above 800 ℃ high temperature gasification molecule of mercury is needed to benefit the conductivity, but it needs to be cooled according to objects. Therefore, the design of lamps and cooling devices should be considered in the overall. Lamp type used when the focus was not on the focus according to the location of objects in order to avoid excessive exposure.

At present, the use of UV glazing There are two main ways.

① three roller (ie, ink roller, coating roller, pressure roller). The advantage of this approach is fast and adjustable; disadvantage is not the glazing in the paper. Although some wind polishing machine knife, but the effect of tissue on the poor polish, thick oil. Therefore compared in this way for paperboard.

② Diao tooth type (that is, Diao embossing rollers with teeth). In this way the advantage of being thin, suitable for thick paper, fuel-efficient, easy to tune the thickness of layers, because the diameter of embossing rollers, and pressure; drawback is the speed of transfer is not easy. Used in the packaging printing UV Varnish, due to technology, materials, equipment, environment and other factors, often there will be some failures, can be summarized into the following problems.

(1) UV Varnish incompatible with the ink, the phenomenon of striped and orange peel. Is a concrete manifestation of some kind of UV oil coating from Mexico at the end of the beads, after curing, like orange skin, or are able to non-foaming coating evenly, but with sharp curettage, UV oil out with. Mainly due to high viscosity UV Varnish; Anilox coating lines are too thick (heavy coating), the surface is not smooth; coating uneven pressure; UV Varnish poor leveling. Solution is to run layer, and then UV oil coating, or UV spark to deal with later on oil, amount of infrared Varnish mixed with alcohol.

(2) UV Varnish poor adhesion, oil-coated. UV Varnish is the main reason for the viscosity is too small, too thin coating; ink in the ink transfer oil or dry oil content is too high; printed ink surface crystallization; printing ink additives in inappropriate; ink the surface of anti-adhesion material (silicon oil, spray) over; Anilox coating lines are too small; light-cured inappropriate conditions. Solution is to reduce the viscosity UV varnished, coated to reduce the volume; uniform pressure adjustment; coated roll should be ground, polished; adding bright leveling agent. Glazing should be in accordance with the conditions of the printing to take corresponding measures; UV Varnish coating thickness can be more appropriate; when necessary on special varnished; in printed products to enhance adhesion of the coating.

(3) UV gloss and brightness after polishing is not ideal. Mainly due to inadequate supply; paper surface brightness or surface roughness is not enough dense, too absorbent; UV Oil viscosity is too small, too thin coating; ethanol and other non-reactive solvent dilution excessive; UV oil coating uneven. solution is run. In addition, UV oil or UV expired oil quality will also does not shine after polishing. According to the paper an appropriate increase in the different UV Varnish viscosity and coating weight, strong infiltration of absorbent paper layer can be coated or replaced good smoothness of paper.

(4) UV oil over crisp crease when folding rattle Department. Polyurethane can be used oil, folding when the first indentation, do not use paper folding hands folding bamboo. UV reservoir thickness will also appear in this failure to adjust the volume.

(5) alcohol after curing of UV oil-ethanol dissolved easily. UV oil, such as the wine after the bottle during transport if the breakdown of UV Reservoir reception will be dissolved. Solution is the use of UV oil-soluble alcohol.

(6) not drying, curing is not complete, the surface of hair sticky. The main reason is the lack of UV radiation intensity; UV lamp aging, diminished strength; UV Varnish stored too long; the diluent does not participate in the response by adding too much; the machine too fast. Solution: In the curing speed is less than 0.5s, the general should ensure that high-pressure mercury lamps not less than the power 120W/cm; lamp to update: if necessary, by adding a certain amount of UV Varnish curing accelerator to speed up the dry.

(7) UV oil coating thickness may also result in neither rattle the economy. UV solution is heated to 50-55 ℃ oil or oil increases in UV diluent.

(8) UV Curing automatically burst oil. The reason is excessive UV light, according to surface temperature was too high. Solution is to increase the lamp and the surface according to the distance, so that objects far away from the shade according to the focus of the rapid cooling after solidification can be cool or cold rolling or by air-cooled, water-cooled source.

(9) have the oil spot glazing. The thickness of the main reasons is not enough oil to eat, not the temperature optical pressure, light pressure plate inappropriate, inconsistent quality of the paper. Should be adjusted for specific conditions or replacement of suitable material. (10) polish coating and pinhole white. Mainly due to thin coating; glue roller are too small; non-reactive diluent (such as ethanol) by adding excessive; print more surface dust. Production environment should be maintained and clean print surface; increase in coating thickness; adding a small amount of smoothing agent: the best diluent for the reaction of the reactive diluent to participate.

(11) large residual odor. The main reason is not completely UV Curing Varnish; ultraviolet lamp aging or inadequate; UV Varnish poor antioxidant capacity; UV Varnish Africa's accession to excessive reactive diluent. Should make a thorough curing UV varnished to enhance the ventilation, if necessary, replace the UV Varnish varieties.

2. Water-based Varnish applications should pay attention to the issue of

Also known as water based glaze oil dispersed polishing agent, with colorless, odorless, transparent and strong sense of non-toxic, non-volatile organic compounds (VOC), low cost, widely source with good gloss, and folding, and wear resistance and chemical resistance characteristics. As a result of water based glaze oil diluent water using a small amount of volatile ethanol solution for the auxiliary, in operation on the human body to eliminate hazards and pollution to the environment is conducive to production safety and improve the working conditions of workers in line with the requirements of environmental protection , especially for food, cigarettes, drugs packaging and so on.

Water based glaze oil mainly by the main agents, solvents, composed of three main types of auxiliaries. Waterborne Varnish is the main agent resin film, the film is the polish material, usually synthetic resin, and dominated it affects various physical properties of the deep layer of polish and quality, such as gloss, and adhesion , and dry, and so on. Many varieties of water-based resin film, but more common at home and abroad is the use of acrylic copolymer resin system. Water-based acrylic resin copolymer depends on the composition of monomer, monomer synthesis and the synthesis process. Water-based acrylic resin copolymer film has good gloss, and transparency, drying quickly, wear-resistant, water-resistant properties of a series of fine, applied to a large number of water-borne and water-based polish polish paint.

Auxiliaries for the improvement of water-based polishing agent and processing characteristics of physical and chemical properties. Auxiliaries include the following.

① Curing Agents: Improving the main water-borne film-forming agent to increase the cohesive strength of the film. ② surfactant: water-based solvents to reduce the surface tension and improve leveling. ③ antifoamer: polish to a long-term control of the foaming agent, the elimination of fish eyes, pinholes and other defects. ④ desiccant: water-based coating to increase the speed of drying agent to improve the relevance of printing paper. ⑤ Adhesives help: To improve the film-forming material and the adhesion capacity of substrates. ⑥ wetting dispersing agent: To improve the dispersion of the main agent to prevent sticking dirty to improve the wear resistance. ⑦ other additives: to improve the performance of the plasticizer, such as folding.

Supporting many different types of agents, according to the different types of polish and a different usage. Water based glaze oil such as infrared, Yaguang polishing are different types of oil glaze oil, so the composition of auxiliaries are also different. But bearing in mind that the use of various types of additives should not exceed 5% of the total will be affected polish adaptive processing.

The main function of the solvent is dispersed or dissolved synthetic resin, various additives. Water-based Varnish solvent is water. Colorless, tasteless, non-toxic, the source of broad, low prices. Volatile water is almost zero, very good leveling properties. However, water-based solvent polishing agents for their inadequacies, such as slow drying, easy to instability caused by products such as process failure size. Therefore, in the use of ethanol is often added to enhance the performance of water-based solvents, drying, water based glaze oil to improve the adaptive processing. In addition, as a result of UV Varnish in dry areas such as more ideal, if its a reference to the water based glaze oil in, you can complement each other. Accordingly, the present has developed a new method of drying Varnish. UV paint coating can be formed in a matter of seconds light membrane, as well as the use of ultraviolet and infrared radiation hybrid polishing paint dry.

Varnish and solvent-based as compared to the advantages of water based glaze oil also:

(1) transparency, and good preservation. Coating of the printed matter in which it can be preserved a long time in the long-term exposure under strong sunlight, yellowing water based glaze oil is not easy, do not change color.

(2) good wear resistance. Packaging of the latter the need for strong resistance to abrasion, in particular, cigarette case, in terms of speed of up to 300 ~ 500 packs / minute high-speed operation to be exposed to high mechanical load. Therefore, the print coating to increase the resistance to abrasion, water based glaze oil to meet this requirement.

(3) fast conjunctiva. Water-based Varnish 30 percent of the drying process by evaporation, 70% absorbed by the material permeability, dry quickly, about a few seconds to complete. When not with Varnish 20% ~ 30% of the water when you can conjunctiva. Therefore do not need any drying method used. The use of infrared or hot air drying methods, drying faster.

(4) good sealing performance. At present, widely used in PP film packages as a package, Waterborne Varnish has a good sealing performance, even if the use of celluloid, but also can be a good sealing effect.

(5) good flatness polishing products, anti-roll power. Gravure printing is a headache after a few color substrates for group dry, low moisture content of paper, are particularly vulnerable to curling. Varnish applied to the soft-pack water-based coating, the product by cutting large sheets, and then hot cut, remained good and the formation of anti-vol. This is to offset printing for the future, especially in hot gravure to provide a new path.

Application of water based glaze oil, it is necessary to consider the way polish, paper type, factors such as product quality requirements. In the use of water based glaze oil to pay attention to the following questions:

(1) viscosity control: in the coating process, the control must be reasonable Oil viscosity and solid content. Therefore, a certain degree of dilution can only be carried out within the scope of solid content. Varnish Waterborne the diluent normally used for ethanol and water mixture 1:1, viscosity reduction effect.

(2) select the type of paper. Dimensional stability of thick paper, and paper and poor dimensional stability. Dimensional stability is the print quality is one of the key indicators, with the amount of water in the printing, paper, humidity, drying time and method of controlling the viscosity is very closely related. If the product is printed below 90g/m2 paper, the water based glaze oil to be used with caution.

(3) control of coating weight. Coating of water based glaze oil volume is not easy to control. Because the coating is easy when volatile ethanol, and water is colorless and transparent coating on white paper water-based liquid coating with the naked eye it is difficult to identify the size of the volume, it is essential to control viscosity. Ethanol content in a timely manner to increase and ensure the stability of products.

(4) the use of anti-dirty agent. In the use of water based glaze oil can completely cancel or reduce the use of anti-dirty agent, as water based glaze oil curing completely, dirty little sticky. After polishing with printing (wet wet printing pressure) can have two hours of paper punching and indentation.

(5) the control of drying time. Varnish solvent-based dry almost always volatile, and the infiltration of water based glaze oil drying of great value. However, in multi-color printing, if the final color is a coating on the glazing, then the drying time will be slow because the paper has absorbed more internal ink and wetting liquid. Water-based Varnish can be infrared, through the use of infrared drying device dry. Dry glaze oil is heated, the bottom of the rapid infiltration of dry, polish at the same time the water was heated to high temperatures, evaporation, drain away by the exhaust pipe.