Introduction
Silicone Surface Additives are essentian in many industrial applications, such as the formulation of paints, inks and coatings. Their man advantage relies in their ability to reduce surface tension, improving wetting on various substrates. Additionally, they offer specific functionalities that enhance product performance.
With over 75 years of experience, Concentrol is a leading expert in the development and manufacture of chemical specialties. Throughout its history, the company has prioritized research and innovation, continually providing its customers with cutting-edge chemical solutions tailored to their needs.
At Concentrol we produce polydimethylsiloxane-polyether copolymers which form the foundation of our silicone surface additives. This expertise allows us to design unique structures customized for each application, ensuring optimal performance. Our non-hydrolyzable polysiloxane-polyether copolymers are particularly resistant to extreme conditions, offering longlasting stability even in harsh environments.
What do Silicone Surfactants mean as a chemical product?
Silicone surface additives belong to a specialized to one or more polar groups. The most common polar groups are non-ionic ethylene oxide (EO) and propylene oxide (PO) units, though other types exist. The length of the PDMS chain (determined by x and w units) controls the molecular weight, while the balance between these units defines the degree of branching. The PDMS and polyether groups are joined by a stable propyl linker (-CH2CH2CH2-), which is non-hydrolyzable, providing durability in various applications.
The ratio of EO (n) to PO (m) units influences the polarity of the polyether segment, which affects its interaction with different surfaces. The total number of these units determines the additive’s molecular weight. Another crucial factor is the terminal group of the polyether chain, which can either be a hydroxyl (-OH) group or substituted with other non-reactive functional groups. This is especially important in formulations containing reactive chemicals, such as isocyanates, where wetting agents with non-reactive terminal groups are preferred.
When applied to a surface, the non-polar PDMS segment aligns toward the air, while the polar part interacts with the liquid phase, giving these copolymers their surfactants properties. By reducing the surface tension of liquids, they lower the contact angle between the coating and the substrate, thereby improving surface wetting.
Applications and Benefits
Silicone wetting agents are crucieal in formulations designed for surface treatments, such as paints, coatings, varnishes, and printing inks. These additives are non-toxic, highly effective in low concentrations, and compatible with a wide range of water-based and solvent-based systems.
Low molecular weight silicone additives are particularly effective in preventing common surface defects, such as craters and fisheyes. They also enhance leveling and significantly reduce surface tension, making them ideal for water-based formulations or difficult-to-wet surfaces. Thease additives are commonly used in systems that require multiple layers of coatings.
Medium-and high-molecular-weight additives are equally important in preventing surface defects, though their impact on surface tnesion than the substrate’s surface energy. This ensures proper adhesion and defect-free coverage. Other surface issues, such as the orange peel effect, arise due to solvent evaporation or the coating’s curing process, which creates surface tension imbalances.
SURFACE TENSION
It refers to the energy required to increase a liquid’s surface area, which is a result of intermolecular forces between surfaces molecules. Liquids with strong intermolecular forces exhibit high surface tension.
Various methods are used to measure surface tension, one of the most common being the Du Noüy ring, which assesses the liquid’s static surface tension. However, in the dynamic industrial processes like roller coating or printing, measuring dynamic surface tension is more relevant. This can be achieved using the bubble processure method, where bubbles are generated at different frequencies in a liquid, and the pressure needed to form the bubbles is directly related to the liquid’s surface tension.
For pure liquids, surface tension remains constant regardless of bubble, lifetime. However, in the presence of surfactants, surface tension depends on how quickly the surfactants can migrate to newly form surfaces, meaning the dynamic surface tension varies with bubble lifetime. At Concentrol, our R&D labs are equipped with advanced bubble pressure tensiometers, capable of measuring dynamic surface tension across a wide range of bubble lifetimes, from 15 milliseconds to 100 seconds. This allows us to observe the behaviour or different wetting agents, predicting their performance in various coating systems and supporting the development of innovative additives.
Regulatory considerations – SVHC Free Additives
Since June 2018 (ED/61/2018), silicone additives containing more than 0.1% of cyclic silicones D4, D5 or D6 must be declared as Substances of Very High Concerned (SVHC) in the European Safety Data Sheets. Concentrol offers silicone surface additives with significantly reduced levels of cyclic silicones, thanks to an additional purification step during production. This process ensures that our additives contain less than 0.1% of D4, D5, and D6, meanung our ORDISOL range does not require SVHC labeling.
Furthermore, most of our silicone additives comply with FDA food contact regulations, and many meet the requirements of BfR Chapter XV and EU Regulation No. 10/2011.
Research and Development in Silicone Surface Additives
The ORDISOL family offers a wide range of silicone surface additives, providing optimal solutions for formulators seeking to enhance surface properties in their products. These additives are organofunctional silicones composed of non-hydrolyzable polysiloxane-polyether copolymers, ensuring excellent stability under extreme conditions such as high temperatures or corrosive enviroments. This product line is divided into two main categories:
- Substrate Wetting and Anti-crater additives (ORDISOL SWT)
- Surface Control Additives (SLP)
SUBSTRATE WETTING AND ANTI-CRATER ADDITIVES (ORDISOL SWT)
These are designed specifically for printing inks and water-based systems, where surface tensions needs to be drastically reduced. In these coatings, water’s high surface tension makes wetting difficult. Concentrol offers additives in this range that can reduce water’s surface tension to nearly 20mN/m, significantly improving leveling and reducing craters or contaminated surfaces. Two new products have been recently added to this range:
- ORDISOL SWT-28. Developed for water-based systems, printing inks, and overprint varnishes, it provides a strong reduction in surface tension while improving wetting and leveling. It is suitable for systems without organic cosolvents.
- ORDISOL SWT-49. Designed for water-based systems and adhesives, this additive improves leveling and flow, reduces surface tension and generates very low foam across all systems.
SURFACE CONTROL ADDITIVES (ORDISOL SLP)
They are suitable for solvent-based, solvent-free and water-based systems. These additives enhance leveling, flow and crater resistance, while also modifying surface properties to improve mechanical characteristics like scratch resistance and abrasion protection.
A recent addition to this range is ORDISOL SLP-35, a universal additive that provides excellent anti-crater performance and enhances surface slip. It also improves scratch resistance and boosts gloss, with a slight defoaming effect, stabilizing foam much less than other polysiloxane-polyether additives.
Concentrol is committed to offering the ideal solution for each customer’s unique needs. Our development team continuously experiments with innovative formulations, ensuring that we remain at the forefront of the chemical industry, recognized as a leading company.
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