What are the mechanisms by which textile printing binders improve washing fastness?

Textile printing binders play a crucial role in the textile industry, especially when it comes to enhancing the washing fastness of printed fabrics. As a textile printing binders supplier, I have witnessed firsthand the importance of these binders in ensuring that printed designs on textiles remain vibrant and intact even after multiple washes. In this blog post, I will delve into the mechanisms by which textile printing binders improve washing fastness.

1. Film - Formation Mechanism

One of the primary ways textile printing binders improve washing fastness is through film - formation. When a binder is applied during the textile printing process, it forms a continuous film over the printed area. This film acts as a protective barrier between the dye or pigment and the external environment, including water during washing.

Most binders are polymers, such as polyurethanes, acrylates, or a combination of both. For example, polyurethane - based binders like Impranil Dls Dl1116 Alternative PUD have excellent film - forming properties. When the binder is dried after printing, the polymer chains align and entangle with each other, creating a cohesive and durable film.

This film prevents the dye or pigment from leaching out into the wash water. It physically encapsulates the colorants, holding them firmly in place on the fabric surface. The film also has a certain degree of flexibility, which allows it to withstand the mechanical stresses associated with washing, such as agitation and rubbing.

2. Adhesion to the Fabric

Another key mechanism is the binder's ability to adhere strongly to the fabric fibers. A good textile printing binder must have high affinity and adhesion to different types of fabrics, including cotton, polyester, silk, and blends.

The adhesion is achieved through various intermolecular forces. For instance, hydrogen bonding can occur between the functional groups of the binder and the fabric fibers. In the case of cotton, which has hydroxyl groups on its surface, binders with groups that can form hydrogen bonds, such as carboxyl or hydroxyl groups themselves, can adhere well to the cotton fibers.

Chemical bonding can also play a role in some cases. Some binders are designed to react with the fabric fibers under certain conditions, such as heat treatment. This covalent bonding provides a very strong attachment between the binder and the fabric, ensuring that the printed design stays in place during washing.

The strong adhesion not only keeps the binder on the fabric but also helps to hold the dye or pigment in position. If the binder does not adhere well to the fabric, it may peel off during washing, taking the colorants with it.

3. Cross - Linking

Cross - linking is an important mechanism for improving the washing fastness of textile printing binders. Cross - linking refers to the formation of chemical bonds between the polymer chains of the binder.

Cross - linking can be achieved through different methods. One common method is the use of cross - linking agents. These agents react with the functional groups on the polymer chains of the binder, creating bridges between them. For example, in some acrylate - based binders, cross - linking agents can react with the double bonds in the acrylate monomers, forming a three - dimensional network structure.

The cross - linked network has several benefits. Firstly, it increases the mechanical strength of the binder film. A stronger film is more resistant to the forces exerted during washing, such as abrasion and stretching. Secondly, it reduces the solubility of the binder in water. A less soluble binder is less likely to dissolve or swell in the wash water, which helps to prevent the dye or pigment from being released.

Some high - performance binders, like those used in Matte PU Top Coat Textile Printing and High Gloss Shining PU Top Coat Textile Printing, often rely on cross - linking to achieve excellent washing fastness.

4. Resistance to Chemicals in Wash Water

Wash water often contains various chemicals, such as detergents, bleaches, and softeners. These chemicals can have a negative impact on the printed design if the binder is not resistant to them.

Textile printing binders are formulated to be resistant to these chemicals. For example, they are designed to be stable in the presence of detergents, which are typically alkaline. The binder's chemical structure is engineered to withstand the pH changes and the surfactant action of detergents.

Some binders also have resistance to bleaches. Bleaches can oxidize the dye or pigment, causing color fading. A binder that can protect the colorants from the oxidative action of bleaches helps to maintain the colorfastness of the printed design during washing.

5. Compatibility with Dyes and Pigments

The compatibility between the textile printing binder and the dyes or pigments used in the printing process is crucial for improving washing fastness. A binder that is compatible with the colorants ensures that they are evenly dispersed and held in the binder matrix.

If the binder and the colorants are not compatible, the colorants may agglomerate or separate from the binder during the drying or washing process. This can lead to poor color distribution and reduced washing fastness.

Binders are often formulated to have good affinity for different types of dyes and pigments. They can interact with the colorants through physical or chemical means, such as adsorption or complex formation. This interaction helps to keep the colorants in a stable state within the binder film, preventing them from being washed out.

6. Particle Size and Distribution

The particle size and distribution of the binder can also affect the washing fastness. In emulsion - based binders, the size of the polymer particles can influence the properties of the binder film.

Smaller particle size generally leads to a more uniform and dense film. A uniform film provides better coverage of the dye or pigment, reducing the chances of the colorants being exposed to the wash water. The smaller particles can also pack more closely together, creating a more cohesive structure that is more resistant to washing.

On the other hand, a narrow particle size distribution ensures that the binder has consistent properties throughout the film. If the particle size varies widely, there may be weak spots in the film where the dye or pigment can be more easily washed out.

Conclusion

Textile printing binders improve washing fastness through multiple mechanisms, including film - formation, adhesion to the fabric, cross - linking, resistance to chemicals in wash water, compatibility with dyes and pigments, and appropriate particle size and distribution. As a textile printing binders supplier, we are constantly researching and developing new binders to optimize these mechanisms and provide our customers with products that offer excellent washing fastness.

If you are in the textile printing industry and are looking for high - quality textile printing binders with superior washing fastness, we would be glad to discuss your requirements. Contact us to start a procurement negotiation and find the perfect binder solution for your printing needs.

References

• Zollinger, H. (2003). Color Chemistry: Synthesis, Properties and Applications of Organic Dyes and Pigments. Wiley - VCH.
• Lewis, D. M. (2001). Textile Coloration. Woodhead Publishing.
• Cegarra, J., & Navarro, T. (2010). Textile Printing: Principles, Processes and Performance. Woodhead Publishing.