One of the defects and remedies of the hottest ink

2022-09-27
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One of the defects and remedies of ink or varnish products

I. Introduction

in normal ink, varnish and packaging printing or post printing finishing technology, some people always want to attribute the defective and waste problems in packaging and printing simply to the quality of the substrate, or the low quality and poor adaptability of ink or varnish (commonly known as paint). And the reason why the printer justifiably shirks, this should first find the reason from the past bit by bit events. The reason why they categorically and undisguised the establishment of a high-precision detection system is that some of them are not willing to scientifically and systematically learn and master the knowledge of packaging and printing technology and finishing technology, and they are more unwilling to let others judge their technical incompetence

after nearly three decades of technical tracking services in ink production and printing operations across the country, the author summarizes the defects in the technical phenomena of the recent 16th CPC National Congress, and sums up the remedial plan in theory, which is enough to prove that the above assertion is wrong. Some people often don't really see packaging and printing in order to reduce the cost of excessive dilution of ink or varnish, resulting in poor color; In order to pursue high profits, we use low-quality substrates to substitute inferior ones for good ones. This helpless phenomenon creates new problems and makes our operators struggling to cope all day long. Because the times are changing, the environment is changing, the trend is changing, and the quality of printing ink or varnish is also changing. If it does not change today and tomorrow, the problems in packaging and printing technology will accumulate more and more, but become a burden until the technology regresses. This is like the past symptomatic treatment scheme, which lags behind today's causal solution, which should be attributed to the performance of ink or varnish, the nature of substrate, and the skills of operators. It also contributed to this new theory with the trend of history, the way of printing, the means of decoration, and personal skills

the facts are enough to prove that the pursuit of first-class is not a quantitative standard, which can only be divided into upper, middle and lower levels. The symptomatic treatment method will also wrongly follow one train of thought. Here, it is particularly emphasized that one point creates trouble after trouble, spending huge economic strength to transform and wasting how much valuable time to deal with technical problems like the following, but will distract attention from a certain problem, It is often more difficult to implement the solution to the cause - that is, "press the gourd and rise the water", but it becomes more complicated. In order to realize this dream, I will briefly talk about my humble opinion on eight aspects of the problem for discussion

II. Several major defects of ink or glazing oil products

2.1 deficiencies:

1. Packaging printing ink and glazing oil often appear in the production and storage process: precipitation, precipitation, gelatinization, tackiness, coarsening, thickening, skinning, blooming, color mixing, discoloration, fading, pigment, filler precipitation and caking

poor dispersion of pigments, poor compatibility of resins, improper mixing of solvents, production, storage, swelling and gel of pigments. These defects seriously hinder the normal production, storage and use of ink

2. It often appears in the process of packaging, printing, coating and finishing: sagging, ink film whitening, color bleeding, floating, image and text migration, deformation, ink film softening, cracks, orange peel, wrinkling, no flatness, bottom biting, color mixing, shrinkage, edge shrinking, pinholes, blistering, side light rainbow, yellowing, fading, etc

3. After printing and post printing finishing, it often appears: discoloration, fading, chalking, cracks, ink layer peeling and falling off, blistering, corruption, pinholes, frosting, atomization, etc

the former and the latter are mainly related to the quality of packaging printing ink or varnish, and the middle is mainly related to the quality of ink or varnish, printing and finishing process design, finishing quality management, printing and finishing environmental conditions. Therefore, the development and production personnel of ink and varnish must understand the differences of packaging, printing and finishing products, production processes and environmental requirements, and the choice of ink or varnish. For example, different temperatures in spring, summer, autumn and winter, different humidity in coastal areas and plateaus, different sunny weather and plum rain seasons, different printing machines or finishing and coating machines or different speeds, different drying (infrared, ultraviolet, etc.) conditions, the possible defects will not be the same

a, fault phenomenon:

for the ink or polish of packaging and printing products (paper or plastic flexible packaging), special attention should be paid to:

1, the surface state of the substrate (substrate), the flatness of the surface of different substrate materials, bubbles, deformation, cracks, adhesion caused by internal stress, etc. On the one hand, printing or finishing molding technology should be improved; on the other hand, necessary surface treatment measures should be taken to implement treatment, such as corona spark treatment or chemical spraying surface treatment

2. The surface polarity of substrate, especially polyolefin material, is generally large, and the substrate with low crystallinity has strong adhesion with packaging printing ink or glazing oil. For example, the surface of flexible packaging substrate carrier such as PE and PP must be specially pretreated before printing or glazing

3. The surface concentration of additives in the ink or varnish system, such as the plasticizer in the carrier of flexible packaging substrate, is easy to migrate to the surface, especially the graphic migration and deformation of the ink film with low softening point during compounding or cooking. There is also the presence of silicone, paraffin and other film removers after molding and even during storage, which is not conducive to the normal display, appearance and adhesion of packaging and printing ink or glazing oil. It should be degreased and cleaned, but it is very difficult to completely remove the place where excessive stearic acid or silicone oil is used. For example, the charged state of the surface of flexible packaging plastic products, but as an insulator, the substrate and the ink or varnish surface are easy to generate static electricity by friction, so the surface is easy to absorb dust. Before the production of ink or varnish, a solution to eliminate static electricity must be carried out

b, causes:

in order to facilitate the careful analysis of the defects of the printing carrier of packaging printing, we will make a rough and detailed classification of the causes

1. Factors related to the quality of ink or varnish are: a. the surface tension of ink or varnish after film formation, the wettability and adhesion of printing carrier for packaging and printing, and the leveling of the surface of ink film and oil film; B. Are the solubility parameters of solvents and thinners of packaging printing ink or glazing oil system similar? Whether the surface tension and evaporation rate, especially the evaporation gradient, are balanced; C. The viscosity, viscosity and rheological properties of ink or varnish. Pay special attention to the characterization and characteristics of viscosity when it changes with the way of ink printing, varnish coating and the printing and coating environment in the film-forming process; D. Rationality, compatibility and tolerance of various additives in ink or glazing oil in its system

2. There are relevant factors in the process of dilution, stirring and dispersion of packaging printing ink or glazing oil: A. mixing of dust and impurities; B. Filtration; C. Whether the dilution is suitable for the ink or polish; D. The adjustment of the viscosity of ink printing and varnish finishing is stable from the perspective of structural adjustment of the whole industry

3. The factors related to the packaging, printing and coating environment of factories, especially workshops, include: A. temperature, humidity, indoor wind direction, air volume and wind speed during production; B. Printing ink splashing and aerosol pollution; C. Prevention of dust and impurities

4. Environmental factors of open-air production, printing and coating include: A. time selection of ink printing and varnish coating - temperature and humidity; B. Wind direction, air volume, wind speed, etc; C. Weather conditions, such as cloudy days, sunny days, morning and evening, etc

5. The factors related to the substrate carrier are: A. whether it is full-scale ink printing or full-scale gloss coating primer, especially the distance between the plates in the middle of overprint, printing speed, thickness of ink layer and gloss layer, etc; B. Surface treatment, blowing and corona treatment; C. Solvent, chemical reagent, surfactant treatment, cross-linking agent and coupling agent addition promotion; D. Drying principle, electrostatic removal device, method, etc

6. Factors in the packaging and printing of ink and the coating and finishing of Polish include: A. printing and coating methods (such as manual or machine stiffness curve drawing, spring sectional stiffness calculation machine, high-speed or low-speed/offset printing, gravure printing, flexo printing, silk screen printing or transfer printing and transfer coating); B. In addition to the quality of ink, varnish and substrate, the technical (experience and skills) level of the operator; C. The angle, speed, distance, ink film and oil film thickness of printing and coating, monochrome printing of packaging or one plate multicolor overprint, and the number, thickness and type of coating of primer and varnish; D. Air pressure, air volume, light energy, light intensity, curing method and drying and curing degree; E. The circulation speed, replenishment amount and interval in the replenishment system of packaging printing ink or varnish, as well as the viscosity of diluent

7. The factors of drying method and storage time are: A. drying (drying, air drying, infrared, UV, etc.) and drying time; B. Temperature, heating rate and constant temperature time; C. The speed of environmental ventilation and ventilation

8. The factors related to the film-forming conditions of ink or varnish are: A. temperature and distribution of drying channel (chain drying bed), heating rate and constant temperature time; B. Drying time; C. Ventilation rate and air pollution degree

we can analyze one by one in the above communication: the packaging and printing defects caused by ink printing and varnish coating are multifaceted. Some are one cause and one fruit, some are several causes and one fruit, and some are one cause and several fruits. As long as we are open-minded and clear-cut, and then put forward our own solutions to the cause, we will not mechanically apply the traditional symptomatic treatment methods in summing up lessons and accumulating experience

although some theoretical analysis involved is ideal, the actual situation is often much more complex than analysis - the combination of theory and practice can just narrow this gap

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