How to avoid plate clogging when using gravure water-based ink in garment printing?
Release Time : 2025-11-19
Gravure water-based ink is widely used in garment printing due to its environmentally friendly properties. However, its poor resolubility and rapid drying speed easily lead to plate clogging problems, resulting in defects such as pinholes, missing text, and uneven ink color. By optimizing process parameters, improving equipment operation, and strengthening gravity water-based ink management, the risk of plate clogging can be systematically reduced, ensuring printing continuity.
Excessively rapid drying of gravity water-based ink is one of the core causes of plate clogging. When the solvent evaporation rate does not match the printing speed, the surface layer of gravity water-based ink within the cells solidifies prematurely, forming a dried film that hinders the transfer of the underlying gravity water-based ink. This can be addressed by adding a slow-drying agent to extend the open time of the gravity water-based ink, or by adjusting the alcohol-to-water ratio in the thinner, for example, increasing the proportion of alcohol in high-temperature and high-humidity environments to slow down drying. Simultaneously, the printing workshop needs to have a temperature and humidity buffer zone to prevent environmental temperature and humidity fluctuations from accelerating the surface curing of the gravity water-based ink. If the hot air from the printing equipment's drying chamber blows directly onto the printing rollers, the airflow direction needs to be adjusted or a baffle plate installed to reduce the direct impact of localized airflow on the printing plate.
Incompatible rheological properties of gravure water-based ink with printing requirements can exacerbate the risk of plate clogging. If the viscosity is too high, the leveling properties of the gravure water-based ink deteriorate, making it difficult to completely fill the cells, resulting in insufficient ink transfer. If the viscosity is too low, air bubbles are easily generated, causing white spots or thickened text on the printed product. Thinner should be added in a stepped manner according to the printing speed, balancing leveling properties and printing speed—appropriately reducing viscosity to improve flowability at high speeds and increasing viscosity to prevent ink splatter at low speeds. In addition, the pH value of the gravure water-based ink should be tested regularly. If the pH value is too low, resin precipitation will occur, requiring the addition of amine stabilizers to maintain its solubility and prevent scaling on the inner walls of the cells.
The cell structure of the printing plate is closely related to the risk of plate clogging. Insufficient cell depth reduces ink storage and accelerates the drying of gravity water-based ink; excessive depth can lead to thick ink layers and blurred images. Cell parameters need to be dynamically adjusted based on the characteristics of the image and text: for text plates, cells need to be deepened to ensure edge sharpness; for full-page images, depth and ink layer uniformity need to be balanced; for shallow plates, cell angles need to be optimized to improve ink release. A tapered cell structure is preferred, as its wider top and narrower bottom shape enhances gravity water-based ink release efficiency and reduces residue. For plates already clogged, a deep cleaning can be performed using an alkaline cleaning agent and a nylon brush. Stubborn clogging requires disassembling the plate, cleaning with an ester-alcohol mixture, and re-chrome plating the cell inner walls.
Proper printing operation procedures are crucial for preventing plate clogging. During intermittent shutdowns, a "shutdown without plate printing" operation must be implemented, maintaining the plate roller at a low speed to prevent irreversible solidification of the gravel water-based ink within the cells due to delayed resolution. If the shutdown is prolonged, a barrier film should be used to reduce air contact, or the plate roller can be directly immersed in the ink bath for continuous idle running. During printing, the gravel water-based ink in the ink bath must be stirred regularly to prevent pigment sedimentation and excessively high local concentrations. When adding new ink or solvent, it should be poured slowly to avoid air bubbles generated by impact. Furthermore, the condition of the doctor blade must be checked regularly; worn blades or improper angles will exacerbate gravel water-based ink residue and require timely replacement or adjustment.
Optimizing the resolution characteristics of gravel water-based ink requires starting with formulation design. Selecting water-based resins with a narrow molecular weight distribution can improve solvent re-permeation efficiency and enhance the secondary dissolution ability of the dried ink layer. Adding surfactants to reduce the surface tension of the gravel water-based ink can improve its wettability with the cell walls and reduce residue. For two-component reactive gravel water-based inks, the amount of hardener added must be strictly controlled to avoid cross-linking reactions during printing, which could lead to decreased fluidity. If the gravel water-based ink deteriorates or becomes insoluble due to contamination with other types of gravel water-based ink, it must be replaced immediately with new ink, and the printing equipment thoroughly cleaned to prevent residual gravel water-based ink from triggering a chain reaction.