Paint Chemicals Industry Newsletters Vol. 3
FOAMING CONTROL IN PAINTS AND COATINGS
Foam means a two-phase stable dispersion in which gas molecules becomes enclosed by liquid.
Pure liquids do not foam. When shaking pure liquid, the gas absorbed tends to form spherical bubbles since this involves the least amount of surface energy. However, the bubbles will rise toward the surface and collapse immediately due to the absence of any stabilization.
There are no surface-active agents present in pure liquids.
As the air in the bubble is released, the liquid quickly rushes into the space vacated by the air; hence, a stable foam is not achieved in pure liquids.
One of the primary reasons for foam formation is the presence of other components that reduce the surface tension.
When does foaming occur?
One of the primary reasons for foaming is the presence of additives that reduce surface tension in the coating formulation. These additives are surfactants and wetting agents, emulsifying agents, dispersing agents, levelling agents and other additives. In paints, coatings and inks, the air gets incorporated into a system resulting in foaming at various stages like manufacturing, packaging, handling & transport, application, drying.
How to avoid Foam
Controlling foam is one of the main challenges for both the manufacturers and the applicators to ensure the smooth and uniform appearance of the paint film. Foam control agents are added to coating and ink formulations to prevent air entrapment and foaming.
Foam control agents are classified into:
- Anti-foam additives
- De-foamers and Deaerators or Air-release agents
Antifoams/Anti-foaming Agents are added in paints to reduce:
- Foam problems during manufacturing.
- Aeration during can filling.
- Air bubble formation during application.
An anti-foam agent should not cause pigment flocculation or emulsion instability, possess poor compatibility resulting in defects in the wet or dry film and affect tint colour appearance.
Defoamers: Defoamers destroy foam after it has been formed.
Defoamers are low surface tension liquids that can enter the foam lamella. It acts as a carrier medium to transport hydrophobic particles into the foam lamella, resulting in the collapse of the foam lamella.
In emulsion paints, foaming can lead to the undesirable formation of surface defects: craters and pores in the coating film. Defoamers reduce the surface tension of the liquid to such an extent that the air bubbles in the foam collapse.
For aqueous coatings, two distinct properties of defoamers are important: defoaming itself and deaerating.
- To destroy macroscopic foam formed in the coating after application – defoaming
- To remove air trapped during the coating process – deaerating.
Adekunle Adebayo Quality Control Manager, Berger Paints Nigeria Limited
Q. Kindly give a brief background about yourself and your company?
Ans. My name is Adekunle Adebayo Kayode, Quality Control Manager of Berger paints Nigeria plc. I hold a Master’s degree in Chemistry from Ladoke Akintola University of Technology, Ogbomoso. I have occupied this position since August 15, 2018, and I have considerably reduced customer complaints during my time as the QAM.
Berger paints Nigeria Plc is one of the leading companies in the paints and coating industry in the country and has been in existence for over 60years.
Q. Cormart is one of your major vendors. How will you access, in terms of quality, the products your organization purchase from Cormart?
Ans.Cormart has been supplying top quality raw materials to Berger paints. It is always a pleasure working with materials from cormart because they align with the expected performance from our R/D team.
Q. What products does your organization purchase from cormart?
Ans. Berger Paints purchases Vinkocryl CMT 50N, Natrosol, Foam Master, Sipernate 820A, Nitrocellulose Chips, Tego Foamex 9 and Dispex AA4140.
Q.Is there a way Cormart can help you achieve your organizational goals?
Ans. Cormart can help us achieve part of our organizational goals by:
- consistently supplying us Vinkocryl CMT 50N binder to meet our annual volume target of 4million litres of water-based products.
- ensuring that our quality standards are met at every supply as agreed.
- expand their range of products to incorporate raw materials for our non-decorative products
- organizing technical seminars with their partners and customers
Q. Any further comment?
Ans.Cormart is an organization that has helped us in sustaining our production rate, and the technical abilities of their sales team are worthy of note. Our relationship with Cormart is based on integrity, prompt delivery and professionalism at all times.
Product Spotlight: NATROSOL™
NATROSOL 250 HHBR
Natrosol™ 250 HHBR by Ashland Specialty Chemical is a non-ionic, water-soluble hydroxyethylcellulose surface-treated with glyoxal.
It is a high-efficiency non-ionic thickener, water retention aid and rheology modifier in all types of water-based paints and surface coatings. It is used as a protective colloid, stabilizer and suspending agent. It offers good pseudo-plastic flow behaviour and wide compatibility with other materials such as emulsion polymers, natural & synthetic gums, emulsifiers, defoamers, pigments, surfactants and preservatives that shows mechanical and chemical stability. It controls rheology before, during, and after application.
Natrosol™ 250 HHBR provides a good colour acceptance, colour development and viscosity retention on tinting, fast dispersion and easier dissolving in water.
- Coatings > Waterborne
- Resins > Acrylics & Acrylic Copolymers
- Resins > Vinyls
Contact your Paint Chemical sales representatives for more information.
Technical Advice & Tips
Solutions Propelling Antimicrobial Coatings into the Future
Companies are beginning to recognize the need to implement a rapid and cost-effective holistic approach to help accelerate the creation of a successful product in a given period.
Across the globe, researchers and engineers have strived to come up with innovations to drive the continuing success of their companies.
In the coatings industry, this has resulted in the development of new or improved processes such as mixing, heat and UV curing processes, and application methods ranging from padding for textiles and impregnation to powder and spray coating. These practices have enabled developers to create new formulations, incorporating additives with properties such as antimicrobial protection for the different product ranges, expanding the scope of coatings beyond just paints.
Research and development are just one part of establishing antimicrobial functionality in coating applications. It is equally important to evaluate the short and long-term consequences of the approach taken irrespective of safety and applicable regulations. Navigating the regulatory landscape can be challenging.
Companies require a great deal of support to ensure that any costly violations or false claims for products are avoided.
Every antimicrobial coating on the market must comply with all associated regulations, from manufacturing & testing to marketing & distribution across multiple regions, to safeguard the manufacturers and consumers.
This situation is further complicated, with every jurisdiction handling antimicrobials differently; some regulate them as chemical substances and others as pesticides or biocidal additives.