Many plastic color printing factories sometimes need to replace ink manufacturers due to ink quality problems, costs, stability and other reasons, but they are more cautious about such problems. They are afraid that the replacement of ink will affect production and cause reciprocal fluctuations in product quality. Cause economic losses. The ink properties of different manufacturers will be different, and will also have different effects on printing.
There are many types of inks currently used in the plastic color printing industry, which can be divided into surface printing inks and internal printing inks according to different printing positions. Liyin ink is divided into polyester nylon ink, OPP special ink, aluminum foil special ink according to different printing materials; according to the use temperature, it is divided into ordinary ink, boiled ink, cooking ink, etc.
Many plastic color printing factories sometimes need to replace ink manufacturers due to ink quality problems, costs, stability and other reasons, but they are more cautious about such problems. They are afraid that the replacement of ink will affect production and cause reciprocal fluctuations in product quality. Cause economic losses. The ink properties of different manufacturers will be different, and will also have different effects on printing.
Common problems you may encounter when replacing ink
1. Ink color: Ink is divided into primary color ink and spot color ink. The primary color inks produced by the ink manufacturers are the same, which are primary red, primary yellow, primary blue, black, white, etc .; spot color inks include ultramarine, scarlet, light yellow, etc. In addition, the ink manufacturers will also mix according to the special requirements of customers Some spot color inks (generally for print orders with large print volume and special patterns).
2. Viscosity of ink: The viscosity of ink produced by different ink manufacturers will be slightly different. After the color printing factory dilutes the ink with a mixed solvent, the viscosity during ink printing is generally controlled between 16-26 seconds (No. 3 Chaanth Cup) . Because the printing color sequence and the nature of the ink itself are different, the viscosity required for each ink will be different. Generally, the viscosity of the white ink is the lowest, about 17 seconds; the viscosity of the black ink is the highest, about 25 seconds, other colors Ink is in between.
3. The fineness of the ink: the fineness of the same type of ink is generally the same between different ink manufacturers, but the difference between the inks of different ink manufacturers is that the normal distribution of the ink particles is different, and of course there are other aspects. Examples of differences are as follows: the inks produced by Factory A and the inks produced by Factory B have a particle size between 20 and 28 microns, but the particle size distribution of ink produced by Factory A is concentrated around 24 microns, while the ink of Factory B The distribution is more dispersed between 20 and 28 microns, so the printability of the ink of factory A is better than that of factory B (as shown in Figure A).
4. In addition to the performance of these inks, it should be noted that for the plastic color printing industry, there is also a performance requirement that is the release of residual organic solvents in the ink, because the products from the color printing factory are generally in direct contact with food, although the ink Substances such as glue do not directly contact food, but some of the small molecular substances will still migrate to the surface of the film and affect the hygiene of food. Therefore, there are corresponding national standards for residual solvents, and color printing plants should also purchase corresponding testing equipment. However, the current situation is that most small factories do not have such equipment. In addition, many domestic color printing plants with complete testing equipment are not strictly controlled on this indicator, resulting in unsatisfactory product hygiene indicators.
5. The production process is also a factor to be considered, but the process level of each color printing factory is basically mature, the difference is not big, but the difference in speed of the printing machine is particularly important. The printing speed between different color printing factories is about 80 ~ 250 meters / Min, if the color printing factory wants to change the ink, the viscosity characteristics of the ink should be considered, especially the ultra-high speed printing (more than 200 meters / minute), the ink viscosity should be very low, the color density should reach the standard, and the ink factory has high requirements .
Hue problems often encountered by ink color printing manufacturers
1. There is a color difference between the same hue inks produced by different ink manufacturers (as shown in figure B). From the figure, we can see that there is a certain difference in the hue between the inks of factories A and B, and there is no difference in the printing pattern. In the case of superimposed color inks, the color difference may not feel large, but if there is a superimposed part, the difference may be obvious. This requires the ink factory to make appropriate adjustments to the ink formulation to minimize this difference. Adding cost to the color printing factory, so we must consider this when replacing the ink manufacturer.
2. General products will produce superposition between different colors of inks due to screen screening, and there will be a slight difference in hue without revision and unchanged process conditions. At the same time, due to the characteristics of color printing, the printing colors are mostly more than 5 colors, and more than a dozen colors. Among them, in addition to the primary color ink, there are spot color inks, and other auxiliary printing materials, such as varnish, must be added according to special process requirements. Wait. Therefore, the application of spot color ink in color printing plants is also very common. Spot color inks are generally specially adjusted by color printing plant technicians. In the case of unchanged printing plates and other process conditions, the replaced inks are generally acceptable. It is close to the original color sample of the ink proofing, but if the printing pattern is complex and the process is special, it will often not meet the requirements of the color sample. If this is the case, the ink factory needs to adjust the ink formula or revise it. If it is the latter, then Will increase the cost of color printing plants, so this should also be considered when replacing ink manufacturers.
The general process of replacing ink (from factory A ink to factory B ink)
(1) First, the color samples of the primary color ink and spot color ink provided to the factory A ink of factory B, if it is a printed product, it is required that it is not superimposed, and it is preferably a solid color block.
(2) The color printing factory has multiple sets of printing plates. First, provide one or several sets of printing plates to the ink factory, and request the factory B to make proofs. Generally, the choice of the version provided to the factory B is usually primary color ink sticks and more common spot color inks.
(3) Enter the experimental stage, generally the technicians of the ink factory (proficient in printing process, and the performance of the ink) go to the site for debugging.
(4) In this process, there are mainly several primary color inks. The spot color inks commonly used basically meet the ink hue requirements of factory A, so the color printing factory can basically be replaced with the ink of factory B.
(5) But this does not mean that color printing factories can sit back and relax. Color printing factories generally have more difficult versions (more spot color inks), and ink factories generally have the production of spot color inks, so the difficulty lies in making such products. The color difference between the printed sample and the standard sample is caused by the spot color ink when the primary color ink is basically the same. The specific analysis is as follows:
a. In the printing pattern, if the spot color ink is not screened or overlapped, the spot color ink will have a color difference. Generally, the ink factory will readjust the ink formula. If the spot color ink is prepared by the ink factory, it is generally one of the spot color inks prepared by the ink factory (the spot color ink is prepared from several inks).
b. In the case where the printing pattern is screened and there is a superposition of different hue inks at the same time, it should be analyzed whether it is caused by the primary color ink or the spot color ink, and should be adjusted according to E1. If it is caused by primary color ink, the ink factory should be required to adjust the primary color ink formula, if it is caused by spot color ink, it should be adjusted according to E1.
c. There is a more special and more complicated situation, that is, there are multiple hues superimposed in the pattern of a product, that is, there are several patterns of the same plate. If the first proof is made, the proof result is inconsistent with the standard sample. Among them, the printed sample part is consistent, and the other part is inconsistent, then pay attention to analysis:
1. The hue of primary inks differs between different ink manufacturers.
2. There are differences in the shades of the same color ink (sometimes can be solved through revision).
The above briefly discusses the problems that color printing manufacturers often encounter when changing inks. I hope it will be helpful to related manufacturers. I hope to discuss related issues with you.
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