Chemical Agent Resistant Coating

Last updated

Chemical Agent Resistant Coating (CARC) is a paint commonly applied to military vehicles to provide protection against chemical and biological weapons. [1] [2]

Contents

The surface of the paint is engineered to be easily decontaminated after exposure to chemical warfare and biological warfare agents. The paint is also resistant to damage and removal by decontaminating solutions. Two-component systems (e.g. epoxy or polyester-based) are often employed. This coating is described in MIL-DTL-53072G.

Background

As of 2018, the U.S. Army Research Laboratory (ARL) led research and development activity for CARC and was the approving authority of CARC products for the Department of Defense (DoD). [3] [4]

Since 1985, U.S. Army Regulation 750-1 mandated the use of CARC systems on all tactical equipment. Regulations mandated the hardening of equipment (i.e. ground support equipment, tactical wheeled vehicles, and aircraft) against the impacts of chemical attacks and subsequent cleaning agents following contamination. These same regulations were followed by the Marine Corps and Air Force. [3]

Applications

As of 1985, most military vehicles and equipment have a topcoat applied with camouflaged CARCs. These topcoats produced a non-porous finish that acted as a protectant against radioactive, biological and chemical contamination. CARC repelled chemical by preventing absorption, with chemicals beading up on the finish surface where they could be washed away. [3]

CARC coatings were also used by government contractors who refurbish vehicles and parts for the U.S. military. Examples included Light Armored Vehicles (LAVs), High Mobility Multi-Purpose Wheeled Vehicles (HMMWV), generators, containers and shelter exteriors. [3]

Solvent-borne CARCs were developed in the early 1980s. The impetus for CARC development was the need to protect costly military equipment. Operation Desert Storm further increased concern of the potential for chemical attacks. [5]

Since 2000, high-performance water-reducible CARCs were commonly used. These materials met DoD’s VOC objective of 1.8 lb/gal and contained no hazardous air pollutants. [5]

Description

The impetus for improved CARC formulations was to reduce the cost of material degradation for the DoD. An improved topcoat was composed to have 44% primary pigments and inorganic extenders, 24% resins, 30% solvent, and 2% additives. Formulations changed from inorganic to polymeric-based extenders in order to enhance the protective features of the topcoat and reduce the cost of material degradation. Additionally, air pollution regulations required reformulation of the coating’s solvent content to reduce the emission of hazardous air pollutants. [3]

Design

As of 2000, two different CARC topcoats included: [5]

1) One-component, moisture-cure urethane (MCU): MCU CARCs cured in a two-stage process where water and isocyanate groups combined to produce a cured paint film. The materials were designed for resistance to windblown dust, sand and chemical agents. An improvement to solvent-borne polyurethanes, MCU materials offered both lower levels of volatile organic compounds and elimination of hazardous air pollutants.

2) Two-component, high-performance, water-reducible polyurethane: Waterbased CARCs, most commonly used by the military, were composed of water-reducible polyurethane resins, marking the first time a water-based two-component CARC was commercially available. This formulation eliminated several solvents, including methyl isobutyl ketone, toluene and xylene.

Related Research Articles

<span class="mw-page-title-main">Paint</span> Pigment applied over a surface that dries as a solid film

Paint is a liquid pigment that, after applied to a solid material and allowed to dry, adds a film-like layer, in most cases to create an image, known as a painting. Paint can be made in many colors and types. Most paints are either oil-based or water-based, and each has distinct characteristics.

<span class="mw-page-title-main">Polyurethane</span> Polymer composed of a chain of organic units joined by carbamate (urethane) links

Polyurethane refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials. This chemical variety produces polyurethanes with different chemical structures leading to many different applications. These include rigid and flexible foams, and coatings, adhesives, electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016.

<span class="mw-page-title-main">Epoxy</span> Type of material

Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also collectively called epoxy. The IUPAC name for an epoxide group is an oxirane.

<span class="mw-page-title-main">Varnish</span> Transparent hard protective finish or film

Varnish is a clear transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmented as desired. It is sold commercially in various shades.

<span class="mw-page-title-main">Enamel paint</span> Paint with a glossy finish that dries hard.

Enamel paint is paint that air-dries to a hard, usually glossy, finish, used for coating surfaces that are outdoors or otherwise subject to hard wear or variations in temperature; it should not be confused with decorated objects in "painted enamel", where vitreous enamel is applied with brushes and fired in a kiln. The name is something of a misnomer, as in reality, most commercially available enamel paints are significantly softer than either vitreous enamel or stoved synthetic resins, and are totally different in composition; vitreous enamel is applied as a powder or paste and then fired at high temperature. There is no generally accepted definition or standard for use of the term "enamel paint", and not all enamel-type paints may use it.

<span class="mw-page-title-main">Thermosetting polymer</span> Polymer obtained by irreversibly hardening (curing) a resin

In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst. Heat is not necessarily applied externally, and is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.

<span class="mw-page-title-main">Polyurea</span> Class of elastomers

Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and an amine component. The isocyanate can be aromatic or aliphatic in nature. It can be monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer or a prepolymer. The prepolymer, or quasi-prepolymer, can be made of an amine-terminated polymer resin, or a hydroxyl-terminated polymer resin.

<span class="mw-page-title-main">Electrophoretic deposition</span>

Electrophoretic deposition (EPD), is a term for a broad range of industrial processes which includes electrocoating, cathodic electrodeposition, anodic electrodeposition, and electrophoretic coating, or electrophoretic painting. A characteristic feature of this process is that colloidal particles suspended in a liquid medium migrate under the influence of an electric field (electrophoresis) and are deposited onto an electrode. All colloidal particles that can be used to form stable suspensions and that can carry a charge can be used in electrophoretic deposition. This includes materials such as polymers, pigments, dyes, ceramics and metals.

<span class="mw-page-title-main">Primer (paint)</span> Preparatory coating put on materials before painting

A primer or undercoat is a preparatory coating put on materials before painting. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted.

CARC may refer to:

<span class="mw-page-title-main">Truck bedliner</span>

A truck bed liner, or simply a bed liner, is a protector applied or installed into a truck. It can be used to protect the bed of the truck from impact damage and abrasive damage. There are two broad classifications of bed liners: "Drop-in" and "Spray-on/in". "Drop-in" bed liners are installed into a truck bed with limited preparation work and are removable for cleaning. Spray-in bed liners require specific preparation to allow the coating to adhere correctly into the truck bed. How well the coating adheres will determine how long it will last.

<span class="mw-page-title-main">Powder coating</span> Type of coating applied as a free-flowing, dry powder

Powder coating is a type of coating that is applied as a free-flowing, dry powder. Unlike conventional liquid paint which is delivered via an evaporating solvent, powder coating is typically applied electrostatically and then cured under heat or with ultraviolet light. The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint. Powder coating is mainly used for coating of metals, such as household appliances, aluminium extrusions, drum hardware, automobiles, and bicycle frames. Advancements in powder coating technology like UV-curable powder coatings allow for other materials such as plastics, composites, carbon fiber, and MDF to be powder coated due to the minimum heat and oven dwell time required to process these components.

Conformal coating is a protective, breathable coating of thin polymeric film applied to printed circuit boards (PCB). It is named as such because it conforms to the contours of the PCB. Conformal coatings are typically applied at 25–250 μm to the electronic circuitry and provide protection against moisture, dust, chemicals, and temperature extremities. More recently, conformal coatings have been used to reduce the formation of whiskers, and can also prevent current bleed between closely positioned components.

A UV coating is a surface treatment which either is cured by ultraviolet radiation, or which protects the underlying material from such radiation's harmful effects. They have come to the fore because they are considered environmentally friendly and do not use solvents or produce volatile organic compounds (VOCs), or Hazardous Air Pollutant (HAPs), although some materials used for UV coating, such as PVDF in smart phones and tablets, are known to contain substances harmful to both humans and the environment.

<span class="mw-page-title-main">Release agent</span> Substance applied to prevent adhesion to a surface

A release agent is a chemical used to prevent other materials from bonding to surfaces. It can provide a solution in processes involving mold release, die-cast release, plastic release, adhesive release, and tire and web release.

<span class="mw-page-title-main">Automotive paint</span> Coloring and resistance to corrosion of cars

Automotive paint is paint used on automobiles for both protective and decorative purposes. Water-based acrylic polyurethane enamel paint is currently the most widely used paint for reasons including reducing paint's environmental impact.

Title 40 is a part of the United States Code of Federal Regulations. Title 40 arranges mainly environmental regulations that were promulgated by the US Environmental Protection Agency (EPA), based on the provisions of United States laws. Parts of the regulation may be updated annually on July 1.

Encasement is the coating over, covering or "encasing" of all building components, interior and exterior. This includes all roofing and toxic hazards materials, such as asbestos, lead-based paint, mold/mildew and other harmful substances, found in buildings. The technique of encasing all building components, including unsafe ones, with green coatings is by far the most efficient way to reduce the harmful effects on people and the environment while lengthening the life of buildings. It is an economical alternative to other abatement methods such as removal, disposal and replacement.

Waterborne resins are sometimes called water-based resins. They are resins or polymeric resins that use water as the carrying medium as opposed to solvent or solvent-less. Resins are used in the production of coatings, adhesives, sealants, elastomers and composite materials. When the phrase waterborne resin is used, it usually describes all resins which have water as the main carrying solvent. The resin could be water-soluble, water reducible or water dispersed.

References

  1. "CARC Technical Paper" (PDF). Milspray.com. Archived from the original (PDF) on 2007-02-21.
  2. "MIL-SPECS". Every Spec.
  3. 1 2 3 4 5 "Evaluation of Chemical Agent Resistant Coatings That Are Exposed to Ultraviolet Radiation" (PDF). Archived (PDF) from the original on February 27, 2021.
  4. "Camouflage Coating and Corrosion | U.S. Army Research Laboratory". www.arl.army.mil. Archived from the original on 2018-09-04. Retrieved 2018-09-04.
  5. 1 2 3 McElroy, Bob. "Protecting the Troops—and Their Equipment". www.pfonline.com. Retrieved 2018-09-04.