A collection of features and precautions for use of water-based inks

The difference between ink and alcohol-soluble ink
First, the difference between the main connecting material resin used:
ink is used in water-based resin, no matter what system (polyurethane or acrylic), except for the resin solid parts, the rest are all water. Alcohol-soluble inks are used in solvent-based resins, regardless of the system (polyurethane or acrylic), in addition to the resin solid components, the rest there are a large number of ester solvents and a small number of alcohol solvents. This is a new process determined by the formulation and process of the

.
, ink formula difference:
ink is composed of water-based resins, pigments, additives and water (or add a small amount of ethanol) and so on. Alcohol-soluble ink is composed of solvent-based resins, pigments, additives and esters, alcohol solvents, etc.
, the difference between application:
ink is currently diluted with water (or a mixture of ethanol and water) at printing time. Alcohol-soluble inks are diluted with alcohol-based solvents.
summary: alcohol-soluble ink "alcohol-soluble" performance, only in the above-mentioned third point to be reflected, its total use of organic solvents is not only alcohol solvents, as well as other solvents such as esters. Its end treatment is also difficult to achieve "single" recovery, but the printing cost per unit area can be lower than traditional solvent-based ink.
ink can theoretically achieve the total use of organic solvents zero, the current ink formulation and printing also introduced ethanol, mainly because most manufacturers in the market printing conditions are not satisfied. With the industry's understanding of ink and water and the improvement of the concept of application, I believe that its organic solvent use will continue to reduce until the ideal level. In addition, ink and water can now be done on the end of the treatment of "alcohol and water" recovery, without distillation can be reused in the printing dilution process. And can do the printing cost per unit area is lower than alcohol-soluble ink.
Plastic gravate ink application issues
the current plastic gravvy composite ink (hereinafter referred to as ink) in some color printing manufacturers have reached a batch use, but to promote large-scale, but also need ink factory and color printing plant between the characteristics of ink for a deeper degree of communication. In the author's opinion, there are two main aspects of communication content: cost and application.
First of all, let's talk about the cost, let's take the actual application of a color printing plant as an example:
solvent ink:
ink: diluent: 1:1
(based on all ethyl esters);
printing area: 6000m2;
cost per unit area is: 520 yuan / 6000m2 - 0.087 yuan / m2.
ink (modified):
ink: diluent: 1:1.2 (diluent ethanol: water: 6:4);
a barrel of ink printing costs about: 20Kg x 35 yuan / Kg x 24 Kg x 0.6 x 6 yuan / Kg x 786.4 yuan;
printing area of 12000m2;
cost per unit area is: 786.4 yuan / 12000m2 - 0.066 yuan / m2.
is calculated from above: ink printing cost per unit area is lower than solvent ink. However, the specific ink in the cost can show how much advantage, can affect many factors, and ultimately to color printing manufacturers' personal experience. The author is just stating an algorithm here.
let's focus on the application of ink. As the name implies, the biggest characteristic of ink is the ink itself and subsequent release are water- and water-containing. And some unique properties of water to a large extent affect the application of ink, today mainly talk about two aspects:
1, adhesion problem: table
: the surface stress value of common solvents:
from the table above, the surface strength of water is much larger than other solvents, so ink on the plastic substrate (BOPP, PET, PA, etc.) wetting is much more difficult than solvent ink. The main manifestation of poor wetting is the low adhesion between the ink film and the printing substrate, which affects the subsequent composite strength. How do I resolve such issues? Method 1: Add a small amount of water-based wetting agent, method two, add a certain proportion of low surface pressure solvent (e.g. ethanol). The essence of both methods is to reduce the surface pressure of the whole system of ink and water, improve humidity, and obtain qualified adhesion.
, drying problem: this
is the most common in the process of ink promotion. Once the solution is not good, not only affect the printing speed, reduce production efficiency, but also cause the subsequent composite process due to glue dry and cause white spots, bubbles, tunnels and other problems. The solution should focus on the ink, printing equipment, plate making three links in line with the actual scientific analysis.
ink link: water has a higher thermal capacity than other solvents and evaporative latent heat. A thermal capacity is an energy that is absorbed or released when a unit mass object changes its temperature. In general, the thermal capacity of water is 4.2 x 103 J/C, which is the largest of the common substances. Evaporative latent heat refers to the heat required to transform a substance from a liquid phase to a gas phase at a constant temperature. At 25 degrees C, the evaporative latent heat of water is 44KJ/mol, the highest of any known solvent. Due to the characteristics of the above water, the formulation of ink should follow the principle of high solidity and low adhesion, so that the water volume can be greatly reduced in the process of ink making and dilution. The advantages and disadvantages of printing drying effect, the amount of water content play a subjective role, this must have a clear understanding.
of printing equipment: the drying degree of ink printing is directly related to the drying system of printing equipment. Under constant air pressure, the factors affecting evaporation are: temperature, the size of the surface area of the liquid, and the speed at which air flows over the surface of the liquid. Corresponding to the printing press, it is reflected in the oven temperature, oven length (print width is quantitative), oven air volume. Among them, the temperature resistance of plastic film is limited, the oven temperature can not be increased in moderation, so the length and air volume of the oven is variable. As far as possible, the length and air volume of the oven should be modified to promote more efficient evaporation of water (and some ethanol) in ink.table
2: a equipment factory printing machine oven length corresponding value
plate-making link: ink printing, should be used as far as possible shallow version (general white ink version in 25-28 m) to reduce the amount of ink on the wet base, that is, indirectly reduce water volume, promote evaporation drying. Because ink is a high-solid low-stick formula design, so the dry base ink will not be due to the light plate and less, color cover will not be affected.
the author believes that the market in the face of ink printing, should take a scientific and rational attitude step by step, can notthe seedlings. The above discussion on the application of ink and water, belongs to a more ideal state, is the next step of plastic gravification from "alcohol water" to "pure water", from "emission reduction" to "zero row" transformation of the necessary measures. The vast number of future planning color printing manufacturers should consciously on the current market fish and dragon mixed aquatic products screening, do not be confused by the "gimmick" and "concept". At the same time also hope that the official and industry media on the promotion and development of ink to do scientific guidance.
ink link promotion thinking
the current market plastic gravation ink promotion in a steady process, during which there are no shortage of peers and the author to chat about the "bottleneck" problem. So ink in the promotion of the link there are still some "bottlenecks" to be resolved? In the author's opinion, there are three key points to think about, putting aside the practical application level: 1, feasibility;
feasibility:
is ink and ink feasible in the end? I'm afraid this is a problem that many ink manufacturers and printing manufacturers are still demonstrating. To be calm, ink in the development over the years has taken too many detours, the main reason for this is from the ink manufacturers themselves. A new product from the emergence to maturity, need a scientific development process, especially ink and water. It is regrettable that in the past many ink manufacturers, although at first occupied the initiative to promote, but did not seek truth from facts. From the one-sided advocacy of "all water", to the one-sided pursuit of speed, and so on, not only did not bring sustainability to their own product promotion, but also with the industry's awareness of ink-oriented, to combat the industry's enthusiasm for the use of ink. The industry must have a clear understanding: that is, the feasibility of ink is not said, but through the completion of large-volume printing orders reflected. This large batch is not a simple concept of two barrels of ink, one roll and two rolls. The source substitution of plastic gravation is a change in the ideology of printing. At present, there are some emerging ink manufacturers are working for this change. The author sincerely hope that printing manufacturers in the encounter with them, and then listen to their own ink products "feasibility" of the elaboration.
Pre-use evaluation:
ink promotion from the current development process, still need to cooperate in many ways: that is, "people, machines, things, law, rings" in the "things", the other four elements need to cooperate to reflect the "feasibility." Therefore, for ink promoters, through the "pre-evaluation" way to identify the target customers. First of all, for the evaluation of the degree of understanding of ink, this is the main premise, if the printing manufacturers in the understanding of ink and ink and promoter can not resonate, that the promotion work can not be carried out, even if reluctantly expand the effect will not be good. Under the premise of mutual understanding and resonance, we can further evaluate the application links such as printing equipment, plate making and operation process in order to obtain the active cooperation of the printing manufacturers. Therefore, "pre-use evaluation" work in the early stage of ink promotion must be done, with a view to doing more with less.
matching:
application of ink is "printing", but for plastic gravate orders, composites account for a large part of the process. The promotion of ink and water must not simply focus on the good-looking printing data, but ignore the match with the composite link. In particular, ink and ink is born with "water-containing" characteristics. Once the printing layer is not dry and thorough, for the use of two-component dry compound glue and solvent-free glue and other composite processes containing NCO components will cause adverse effects, especially after ripening. This must attract the attention of ink promoters and printers.
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