How to control the quality control of dog food packaging bags

The quality control of feed bags primarily focuses on two aspects: barrier properties of the material and the integrity of the packaging.

According to feed bag manufacturers, in the printing process of feed bags, the color of the printed film depends mainly on the ink concentration and transfer rate during the printing process. For specific substrates or inks, the ink concentration is relatively fixed, while the transfer rate depends on factors such as ink viscosity and is also influenced by the printing speed.

Temperature and Humidity Variations:

Significant fluctuations in ink and liquid temperatures can cause changes in flow characteristics and corresponding shifts in color tones. This is because temperature variations affect ink viscosity. Additionally, hot and dry weather conditions can notably impact the transfer rate of inks in high-gloss areas.

To control printing products effectively, it is important to maintain stable temperature and humidity conditions within the printing workshop. When using inks in winter, preheating them in advance helps reduce ink temperature variations.

Separation of Composite Colors:

This scenario is more likely to occur with mixed colors that have different densities, such as light colors combined with organic or inorganic pigments. Particularly, slow ink flow in the inkwell can promote the separation of composite colors, so ensuring smooth ink circulation is essential.

Furthermore, if the mixing is insufficient, the concentration of a particular color tends to increase as the printing progresses. Therefore, thorough mixing should be conducted using a dissolver or other suitable methods before commencing the actual printing process.

Ink Deterioration and Color Intensity:

Extended printing time can lead to changes in ink solvent composition, introduction of moisture from the air into the ink, and consequent ink deterioration, intensifying color changes.

To prevent temperature drop caused by vaporization heat, slow-drying solvents can be utilized. In cases of high temperature and humidity, ink may be contaminated with a certain amount of water. Therefore, when issues arise, adding fresh ink or replacing all the ink is necessary. Residual ink used multiple times should be periodically filtered or discarded due to dust contamination.

Viscosity and Drying Speed:

Changes in ink viscosity directly affect the color of printed feed bags. Higher viscosity results in relatively higher color density, while lower viscosity leads to reduced color density. This influence can be quite noticeable and requires careful attention. Optimal ink viscosity is necessary for printing processes. Excessive viscosity hinders ink transfer and can lead to plate blurring. When viscosity is too low, static electricity is generated, which is unfavorable for color control. Viscosity changes subtly affect the flow area in gravure or flexographic printing methods, especially in multicolor printing. Thus, maintaining consistent ink viscosity under a given printing speed is essential, and automatic viscosity controllers are recommended.

Changes in the solvent proportion within the ink also affect the drying speed of working inks, subsequently impacting ink transfer rates and printing colors. For inks with lower usage, natural evaporation of solvents over time not only affects ink viscosity but also alters solvent ratios and evaporation rates. Therefore, timely solvent replenishment is necessary.