introductory:
In the printing industry, the balance between cost control and basic printing quality has always been the focus of many enterprises. With its cost-effective advantages, ordinary economic offset printing inks are widely used in various printing scenarios that are sensitive to printing costs but have certain quality requirements, such as daily office document printing, ordinary commodity packaging printing, general publicity material printing, etc. In order to give full play to the effectiveness of this type of ink, this application scheme is specially formulated.
1. Ink characteristics
Color performance
The common pigment system is selected, which can realize the basic CMYK four-color printing and meet most of the conventional color needs. Although the color saturation is not as good as that of high-end ink, it can also present clear and recognizable colors under a reasonable printing process, which basically meets the visual requirements of daily prints.
Printability
It has moderate viscosity and fluidity, and can be transferred smoothly on ordinary offset presses, and evenly distributed on the surface of the printing plate and substrate. It has a good affinity with common paper such as offset paper, writing paper, light paper, etc., which can ensure that the ink is firmly adhered and not easy to fall off.
Drying performance
Mainly relying on oxidative polymerization drying method, under the normal printing workshop environment (temperature 20 - 25 °C, relative humidity 40% - 60%), the drying time generally ranges from a few hours to more than ten hours, depending on the thickness of the printing ink layer and environmental conditions.
2. Application scenarios
Office document printing
Documents, reports, meeting materials, etc. in the daily office are more sensitive to cost, and ordinary economic offset printing ink can effectively control the printing cost under the premise of ensuring the clear printing of text and charts.
Ordinary commodity packaging
Like some daily necessities, simple outer packaging of food, do not need too high ink gloss and special effects, economic offset printing ink can meet the basic printing needs of packaging, display product information.
General promotional materials
Such as leaflets of street shops, posters of community activities, etc., such promotional materials are printed in large quantities, and the use of economic offset printing inks can not only ensure the publicity effect, but also control the budget.
3. Ink selection
According to the printing material
If the printed paper is a writing paper with a rough surface, the ink with better fluidity and strong coverage of the rough surface should be selected to ensure that the ink can fully fill the pores of the paper and improve the printing clarity; If the surface is relatively smooth, you can choose an ink with a slightly higher viscosity to enhance the adhesion stability of the ink on the surface of the paper.
Combined printing process
For the conventional lithographic offset printing process, you can choose ordinary oxidative polymerization dry economic offset printing ink; If the printing equipment has a simple drying device, the ink formula can be adjusted appropriately to make it dry faster and improve production efficiency.
4. Pre-printing preparation
Equipment cleaning and commissioning
Thoroughly clean the ink fountain, ink roller, rubber cloth and other parts of the printing machine to prevent residual impurities from affecting ink transfer and printing quality. Adjust the printing pressure and accurately adjust it according to different paper thicknesses to ensure uniform ink transfer; At the same time, adjust the ink and water balance to ensure that the graphic part on the printing plate is clear, and the non-graphic part is clean and ink-free.
Ink preparation
Accurately mix the ink according to the color required for the printing order. Use stirring equipment to fully stir the ink to evenly disperse the pigments, fillers and additives to avoid the problem of inconsistent printing colors caused by pigment precipitation.
Printing material testing
Check the flatness, thickness uniformity, pH and other indicators of the paper. The uneven paper will lead to uneven printing pressure and affect ink transfer; Too acidic or too alkaline paper may react chemically with the ink, affecting the drying speed and printing effect. Problematic paper needs to be disposed of or replaced in advance.
5. Printing process control
Printing pressure control
According to the characteristics of the paper and ink, the printing pressure is controlled within the appropriate range. Excessive pressure can easily lead to the expansion of dots and the accumulation of ink, which will deepen the color of the printed matter and blur the image; If the pressure is too small, the ink transfer is insufficient, the color is light, and the graphics and text are not clear.
Ink and water balance control
Strictly control the amount and concentration of dampening solution. Too much dampening solution will emulsify the ink, reducing the adhesion and color saturation of the ink; If the dampening solution is too small, it is easy to cause the non-graphic part of the printing plate to be stained with ink, and the phenomenon of dirty plate will appear. In the printing process, it is necessary to monitor the balance of ink and water in real time and fine-tune according to the actual situation.
Drying control
Since ordinary economic offset printing inks mainly rely on oxidation and polymerization drying, the temperature and humidity of the printing workshop have a great impact on the drying speed. In the environment of low temperature or high humidity, the temperature of the workshop can be appropriately increased or ventilation equipment can be increased to speed up the drying speed of the ink and prevent the printing matter from being dirty and sticky in the drying process.
6. Quality inspection
Color detection
Use a colorimeter to detect the color of the printed matter, compare it with the standard color sample, and control the color difference within a certain range (generally the ΔE value is controlled within 5) to ensure the accuracy of the color of the printed matter.
Printing quality inspection
Check the clarity and uniformity of the dots of the printed matter through visual inspection or with the help of a magnifying glass, and check whether there are defects such as ghosting, pasting, and missing printing. At the same time, the adhesive adhesion of the ink is tested by the tape test method to ensure that the ink adheres firmly to the surface of the paper.
7. Storage & Transportation
Storage
It should be stored in a cool, dry and well-ventilated warehouse, away from direct sunlight and high temperatures. The storage temperature should be controlled at 10 - 30 °C and the relative humidity should be 40 - 70%. The ink should be sealed and stored to prevent solvent volatilization and dust impurities from mixing, regularly check the status of the ink, and deal with it in time if it is found that there are caking, thickening and other phenomena.
Transportation
During transportation, it is necessary to avoid the ink being subjected to violent collisions, squeezing and rain. Use a special means of transport to ensure that the ink packaging is intact. When loading and unloading, it should be handled with care to prevent ink leakage caused by packaging damage.
8. Precautions
Operator protection
Operators should wear protective gloves, masks and goggles to avoid direct skin contact with ink and inhalation of volatile organic solvent gases. The workplace should maintain good ventilation conditions and reduce the concentration of harmful gases.
Ink use management
Follow the principle of first-in, first-out, and use it reasonably according to the shelf life of the ink. For inks that are close to the expiration date or expired, quality testing is required, and they can be used only after they are qualified; For unqualified inks, they should be properly disposed of in accordance with relevant regulations.
Environmental management
The printing workshop should be kept clean and the ink residue and waste should be cleaned regularly. Ink-containing wastewater and waste gas should be discharged after treatment to meet the standards to reduce environmental pollution.
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