Analysis of Water-based Ink Formulation Components

Date: Jan 23 2025 From: Star Color

The application of water-based inks in the printing industry is increasingly widespread, with their environmental protection characteristics aligning with the current concept of sustainable development. Many industries with high safety requirements, such as food packaging and book printing, have switched to using water-based inks for printing. However, there are still many people who are unfamiliar with water-based inks. Below, we will analyze the characteristics of water-based ink formulations.

The main components of water-based inks include: resins, pigments, fillers, and additives.

Core Role of Resins

Resins serve as the cornerstone in water-based inks, playing a pivotal role in determining the ink's performance and having a significant impact on its gloss. Different types of resins, due to differences in their chemical structures and physical properties, exhibit vastly different effects in enhancing ink gloss.

Common water-based ink resins include acrylic resins and polyurethane resins. Acrylic resins possess good gloss and weather resistance. The double bonds in their molecular structure can undergo crosslinking reactions during the drying process, forming a dense coating structure, thereby effectively improving the ink's gloss. When the acrylic resin content reaches an appropriate proportion in the ink formulation, the printed surface can exhibit high gloss, vibrant colors, and a sense of texture. Excessive acrylic resin content may lead to increased ink viscosity, causing issues such as plate sticking during the printing process. Conversely, too low a content may fail to form a sufficiently dense coating, making it difficult to achieve the desired gloss.

Polyurethane resins are renowned for their excellent flexibility and abrasion resistance, and they can also enhance the ink's gloss to a certain extent. The carbamate groups in their molecular chains have strong polarity, enabling good bonding with pigments and other additives, allowing the ink to form a smooth and even surface after drying, thus enhancing gloss. In printing applications requiring high flexibility and gloss, such as plastic film printing, polyurethane resins are often the preferred choice.
Analysis of Water-based Ink Formulation Components

Correlation of Pigment Characteristics

Pigments are the key components that impart color to inks, and their characteristics also significantly affect gloss. Factors such as pigment particle size, shape, dispersion, and concentration all alter the ink's gloss performance to varying degrees.

Generally, smaller pigment particles tend to result in higher ink gloss. This is because smaller pigment particles can pack more tightly together, forming a smoother coating surface that reduces light scattering and thus improves gloss. When the pigment particle diameter is between 10-100 nanometers, the ink can achieve a high level of gloss. Excessively fine pigment particles may lead to increased pigment agglomeration, affecting the ink's dispersion and stability, and subsequently lowering gloss.

Pigment shape also influences gloss. Spherical pigment particles, compared to irregularly shaped particles, enable more uniform light reflection on the coating surface, thus enhancing gloss. In actual production, controlling the pigment manufacturing process to a certain extent can adjust the pigment shape to meet the requirements for ink gloss.

Pigment dispersion is another crucial factor affecting gloss. Uneven pigment dispersion in the ink can lead to granular protrusions or depressions on the coating surface, causing light scattering on these uneven surfaces and reducing gloss. To ensure good pigment dispersion, it is usually necessary to add an appropriate amount of dispersant and use efficient dispersion equipment for thorough mixing and grinding.

Furthermore, changes in pigment concentration also affect gloss. Excessive pigment concentration can interfere with light reflection due to the numerous pigment particles, lowering gloss. Conversely, too low a concentration may result in too light an ink color, failing to fully exhibit the desired gloss effect. Therefore, reasonable control of pigment concentration is crucial for achieving the desired gloss.
Analysis of Water-based Ink Formulation Components

Auxiliary Effects of Fillers and Additives

Fillers in water-based inks primarily serve to fill and reduce costs, but they also have an impact on the ink's gloss. Some fillers with smaller particle sizes and fine textures, such as calcium carbonate and kaolin, when added in appropriate amounts, can fill the gaps between pigment particles, making the coating more dense and, to some extent, improving gloss. If the filler particle size is too large or the addition amount is excessive, it can disrupt the ink's leveling properties, leading to a rough coating surface and decreased gloss.

Although additives are used in relatively small amounts in the ink formulation, they are diverse in type, including defoamers, leveling agents, and gloss enhancers. They play an indispensable role in adjusting the ink's pH value, viscosity, and enhancing the ink's overall performance, including gloss. For example, leveling agents can improve the ink's leveling properties during the printing process, enabling the ink to form a more even surface after drying, reducing gloss loss due to poor leveling. When the leveling agent is added at 0.5%-2% of the total ink amount, it can effectively improve the ink's leveling effect.

Gloss enhancers are specifically used to improve the ink's gloss. They can enhance light reflection by changing the ink's surface tension and optical properties, thereby significantly boosting gloss.

The above is an explanation regarding water-based ink formulations. For any inquiries about water-based inks, please contact: eva@starcolor-ink.com.