The control of pH value is crucial during water-based ink printing. The pH value not only directly affects the printing performance and print quality of ink, but is also closely related to multiple technical indicators such as ink viscosity and drying speed. The following is a detailed explanation of pH control during water-based ink printing:
1、 The importance of pH value
The pH value is an indicator of the acidity and alkalinity of ink. For water-based ink, its pH value should usually be controlled within a certain range (generally 8.0-9.5) to ensure good printing suitability and stability of the ink. Excessive or insufficient pH value can lead to a decrease in ink performance and affect printing results.
2、 The influence of pH value on ink performance
Viscosity: Changes in pH value directly affect the viscosity of ink. Generally speaking, as the pH value increases, the viscosity of the ink will decrease; On the contrary, as the pH value decreases, the viscosity of the ink will increase. The change in viscosity can affect the transfer performance of ink and the color uniformity of printed materials.
Drying speed: PH value also has a significant impact on the drying speed of ink. When the pH value is too high, the alkalinity of the ink is too strong, which will slow down the drying speed and may cause the back of the printed matter to become dirty; When the pH value is too low, the alkalinity of the ink is too weak, which will accelerate the drying speed, but it is easy to cause problems such as plate blockage and paste.
Printing quality: Unstable pH value can cause fluctuations in ink performance during the printing process, thereby affecting quality indicators such as color saturation and clarity of printed materials.
3、 Methods for controlling pH value
Using pH stabilizer: Adding an appropriate amount of pH stabilizer to the ink can effectively adjust and control the pH value of the ink, keeping it within a stable range. The selection of pH stabilizers should be determined based on the specific formula of the ink and printing conditions.
Regular testing and adjustment: During the printing process, a pH meter should be used regularly to measure the pH value of the ink, and adjustments should be made in a timely manner based on the test results. When the pH value deviates from the set range, timely measures should be taken to correct it.
Control ink ratio: Reasonably controlling the ratio of each component in the ink, especially the content of alkaline substances, can effectively prevent pH fluctuations. When mixing ink, it is necessary to strictly follow the formula requirements and avoid making arbitrary changes.
Pay attention to environmental factors: Temperature and humidity in the printing workshop may also affect the pH value of ink. Therefore, during the printing process, attention should be paid to controlling the temperature and humidity conditions in the workshop to maintain a stable environment.
4、 Precautions
Avoid diluting ink with tap water: Impurities and hardness components in tap water may affect the pH value and stability of ink. Therefore, deionized water or purified water should be used when diluting ink.
Pay attention to the storage conditions of ink: Ink should be stored away from direct sunlight and high temperature environments to prevent deterioration and changes in pH value.
Regular maintenance of printing equipment: Keeping the printing equipment clean and in good condition is also an important means of controlling the pH value of ink. Regularly cleaning the printing machine and replacing worn parts can reduce ink contamination and loss during transportation.