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Hydrophobic Coatings

Hydrophobic Coatings Explained

Posted on by chemical dynamics

Coatings that offer a hydrophobic (EU) or superhydrophobic surface can impart multiple advantages to the coating surface and substrate they are applied to. Advantages may include decreased dirt retention, self-cleanability, improved moisture and corrosion resistance, as well as extended life expectancy of the coating and substrate. To fully explain and quantify hydrophobicity, it is necessary to define the relationship between contact angle and the hydrophobic/hydrophilic (EU) character of a surface.

Figure 1 – Contact Angle for Hydrophobic Coating Surface and a Hydrophilic Coating Surface

hydro1
Hydrophobic Surface Contact Angle ≥ 120°
hydro2
Hydrophilic Surface Contact Angle ≤ 30°

Figure 2 – Contact Angle and Superhydrophobicity

Super Hydrophobic Contact Angle ≥ 150°
Super Hydrophobic Contact Angle ≥ 150°

Accordingly, the surface characteristics of a coating can range from being hydrophilic (water-loving) to superhydrophobic (or highly water repellent). Several factors impact the contact angle of a water drop on the surface of a coating. These include the macro, micro, nano-surface profile, and the surface tension of the coating on which the water droplet is resting. Surface tension is the elastic tendency of liquids that make them acquire the least surface area possible.

 

 

To read the full article written by Ron Lewarchik, Chemical Dynamics President, on UL Prospector, click here.

United Tactical Systems Testimonial

United Tactical Systems Testimonial

Posted on by chemical dynamics

“We had a coating project deadline requiring an immediate solution. Chemical Dynamics was able to solve our problem and provide a paint and formula that met our project goals. Based on our experience, I would recommend Chemical Dynamics to anyone requiring assistance in the formulation or development of a new paint product.”  

 

Rod Demeny, Operations Manager, United Tactical Systems, LLC Pepper Ball

Barrian Superhydrophobic Testimonial

Barrian Superhydrophobic Testimonial

Posted on by chemical dynamics

“Chemical Dynamic’s formulating experience and the ability to innovate provided invaluable assistance to optimize performance of paint systems using our superhydrophobic material for aerospace and other applications. I can recommend there company to anyone seeking expertise and support in paint and coatings”

 

Stewart Kennedy, President Business Development, Barrian  Barrian testimonial

Nanoparticles – When Smaller is Better

Nanoparticles – When Smaller is Better

Posted on by chemical dynamics

Nanoparticles (EU) are normally defined as those particles that have a dimension of between 1 and 100 nm. The use of nanoparticles in coatings has provided a means to further improve performance such as scratch resistance, hardness, antistatic properties and UV resistance. These performance attributes are derived from the property profiles of nanoparticles.

Nanoparticles provide the inherent properties of the material they are derived from. For example, nano alumina (EU)maintains the properties of alumina, such as hardness and scratch resistance, but only on a nanoscale. Likewise, nano silica(EU) provides hardness, nano titanium dioxide provides a high refractive index and UV stabilization, and nano zinc oxide(EU) remains a UV light absorber (EU), even if the zinc oxide particles are nano-sized. The benefits of these materials are imparted to the coatings that they are used in.

The most pronounced property that is influenced by the particle size is the change in light scattering. For example, nano-sized particles may produce transparent coatings as light-scattering decreases with decreasing particle size. Most objects are visible due to light scattering from their surfaces. Scattering of light depends on the wavelength or frequency of the light being scattered as well as the size, shape and type of particle.

Table I – Particle Size Perspective

nano1Since visible light has a wavelength on the order of micrometers, most particles much smaller than this, such as nano particles, are mostly transparent as their ability to scatter light diminishes with their size. However, light scattering is also dependent on the Refractive Index (RI) and the difference in RI between the interface of the particle and the surrounding medium. For example, if the surrounding medium has an RI similar to that of the RI of the particle, then the mixture of the two materials will be more transparent. To illustrate, silica has an RI of about 1.5 and polymethylmethacrylate (EU) has an RI of about 1.5, so a coating comprised of nano silica and an pMMA will be nearly transparent. The properties of nanoparticles based on their dimension can be quite dramatic.

 

To read the full article written by Ron Lewarchik, Chemical Dynamics President, on UL Prospector, click here.

 

Bio-based resins

Bio-based Resins for Coatings

Posted on by chemical dynamics

In recent years, there has been a growing interest in the use of bio-based resin building blocks in the synthesis of polymers for use in coatings. Bio-based products are derived from plants and other renewable agricultural, marine, and forestry materials and provide an alternative to conventional petroleum derived products.

Driving forces include a growing public and private awareness and interest in the use of renewable raw materials that can meet sustainability expectations and certifications such as Green Seal and Green Guard as well as the USDA BioPreferred Program for product labeling. Green Seal and Green Guard are environmentally driven, whereas the USDA BioPreferred Program functions to encourage the use of renewable agricultural raw materials in products. ASTM d6866 was developed to standardize, certify and classify the bio-based content of materials. Minimum renewable carbon content categories (MRCC) have been established for purchasing by Federal agencies and their contractors.

Table I – BioPreferred Coatings Categories[1]

resin1

Bio-based resins for coatings are normally referred to as alkyds (EU). Alkyds are comprised of fatty acid modified polyester resins. These resins are sometimes modified to include a urethane (EU) linkage and thus called uralkyds or oil modified urethanes. The fatty acid portion is derived from naturally occurring or renewable oils derived from sunflower (EU), safflower,soybean (EU), castor (EU), tall (EU) and others. Polyesters (EU) are derived from the reaction product of a polyol (EU) and a di or multifunctional acid or carboxylic acid and anhydride (EU) to form multiple ester linkages in a polymer chain.

 

To read the full article written by Ron Lewarchik, Chemical Dynamics President, on UL Prospector, click here.

Paint Cost Calculation

Paint Cost Calculations

Posted on by chemical dynamics

Paint Cost Calculations

How to Get the Most Mileage Out of Your Paint

Determining the effective cost of paint that can be made from naturally occurring elements involves several issues that must be considered. These include the volume solids of the paint, application method, and the geometry of the object to be painted. For example, a paint that sells for $20 per gallon at 20% volume solids is actually more expensive on an applied cost basis than a paint that sells for $40 per gallon at 45% volume solids.

Theoretical coverage

 =

Volume Solids

Dry mils required

 

To illustrate the cost of paint to apply one mil (0.001 inch) per 100 square foot of the $20 paint is as follows:

  • If a gallon of paint weighs 10 pounds and is $20/gallon at 20% volume solids = 10# of the 20 $/Gallon X 0.20 pounds of volume solids = 2.0 pounds of solid or dry paint per gallon of liquid paint for $20. Accordingly the cost of each dry pound of paint is $10. The square foot coverage of a paint is 1604 square feet per mil at 100% volume solids. Since our paint is 20% volume solids, at one mil dry film thickness, one gallon of paint will cover 1604 square feet/mil X 0.20 % volume solids = 320.8 square feet/gallon at a cost of $20. Accordingly the cost to paint 100 square feet of surface is $20 X 100/320.8 = $6.23

To illustrate the cost of paint to apply one mil (0.001 inch) per 100 square foot of the $40 paint is as follows:

  • A gallon of this paint weighs 12 pounds and is $40/gallon at 45% volume solids = 12# of the 40 $/Gallon X 0.45 pounds of volume solids = 5.14 pounds of solid or dry paint per gallon of liquid paint for $40. Accordingly the cost of each dry pound of paint is $7.78. The square foot coverage of a paint is 1604 square feet per mil at 100% volume solids. Since our paint is 45% volume solids, at one mil dry film thickness, one gallon of paint will cover 1604 square feet/mil X 0.45 % volume solids = 721.8 square feet/gallon at a cost of $40. Accordingly the cost to paint 100 square feet of surface is $40 X 100/721.8 = $5.54

 Accordingly, in this illustration, the $40 paint provides more value than the $20 paint as it provides lower cost coverage at equal dry film thickness. The table below illustrates paint coverage per mil for paint applied at 100% volume solids. 

 

Theoretical coverage

 =

Volume Solids

Dry mils required

Price of Paint Breakdown

US Patent on Coatings that Arrest Rust Granted to Chemical Dynamics LLC

New US Patent on Rust Coatings Granted

Posted on by chemical dynamics

US Patent on Coatings that Arrest Rust Granted to Chemical Dynamics LLC

US Patent 8,927,649 was awarded to Chemical Dynamics LLC on January 6, 2015. US Patent 8,927,649 covers of a film forming penetrant coating with a high cross-link density that arrests corrosion on rusty substrates.

Patent Abstract: A one part, storage stable polymerizable formulation is provided that includes an ethenically unsaturated polymerizable compound intermixed with a free radical polymerization initiator and an organic solvent. The organic solvent provides storage stability and upon evaporation of the solvent, the rate of polymerization of the compound accelerates independent of addition of a second part. The formulation includes at least 30 total weight percent solids upon cure. Optional additives to the formulation include at least one of a cure accelerator, a filler, a plasticizer, a colorant, and a cure inhibitor. A process for forming a polymerized coating on an article involves the application of this formulation to the substrate of an article and allowing sufficient time for the solvent to evaporate to form the polymerized coating on the article. The substrate of the article forms a corrosion barrier even without prior removal of a native corrosion layer on a surface of the substrate of the article.

Paint Material Evaluation

Paint Raw Material Evaluation

Posted on by chemical dynamics

SITUATION: A global company with multibillion dollar sales required a paint raw material evaluation from a paint expert of the performance and application potential of a new fluoropolymer resin that they developed.

ACTION: Due to the resident coating expertise in fluoropolymer coatings, the supplier contracted Chemical Dynamics to provide an independent evaluation of this new resin chemistry. Our company conducted paint and coatings testing to evaluate the material.

RESULT: Chemical Dynamics completed the evaluation and identified multiple new applications for the fluoropolymer resin chemistry.