In a previous article dated March 31, 2022, we addressed the issue of CBRN protective gloves. In this new blog, we’d like to describe butyl rubber insulating gloves in more detail, and show how they’re evolving towards ever-greater performance.
We can remind you that gloves protect the hand, a complex and very fragile organ of prehension, indispensable to everyday life.
Gloves can provide “mechanical” protection, such as handling gloves, cut-resistant gloves, abrasion-resistant gloves… In these cases, the structures are varied and adapted to the protection required: woodcutter’s gloves are not comparable to the cut-resistant gloves worn by butchers….but in all cases, they meet standards that enable their capacities to be assessed and compared.
In the case of CBRN protective gloves, the focus is entirely on protecting the skin, which plays a fundamental physiological role: thermal regulator, protection against infection, waterproofing through sebum protection, temperature, pain and pressure sensor, vitamin D production and much more….
Many products cause chemical burns, sometimes with serious consequences. In the CBRN field, gloves have to protect against a wide spectrum of toxic chemicals in liquid, gaseous or aerosol form.
Filtering gloves
and in particular Ouvry® “Target” gloves protect against chemical warfare agents in liquid, vapor or aerosol form for 24 hours, in accordance with NATO recommendations (AEP38 standard). Made from robust, flame-retardant and water-repellent leather and textiles, they provide filtration that maintains the exchange of air and water vapor between inside and outside. Evaporated sweat cools the skin and the glove remains comfortable, especially in hot weather.
They can be considered general-purpose gloves for handling weapons, radios or electronic devices in an environment that may, at any time, be contaminated by CBRN agents. Their interfaces are optimally managed for any type of suit or jacket. They have been validated for intervention forces, law enforcement agencies and armed forces. They complement a protective garment on the hands.
When made of butyl, these gloves are completely hermetically sealed and offer 2 additional advantages: they protect against a wide spectrum of chemical and industrial toxins, and enable precise movements thanks to maximum dexterity. Compared with previous gloves, they are not only resistant to chemical warfare agents, but also to a wide range of industrial chemical toxins, making them a key component in the handling of hazardous substances.
Insulating gloves: constituent materials
Several materials can be used in the composition of chemical protection gloves;
PVC, Latex, Nitrile, Neoprene, Butyl, Viton…
Butyl gloves offer several advantages: flexible and elastic, they provide excellent protection for the user’s hands against esters, ketones, aldehydes and alcohols, strong bases, nitric, sulfuric and hydrochloric acids, and peroxides. Butyl is also used in the military world as protection against chemical warfare agents. They are generally used when workers are in prolonged contact with a substance. They also offer resistance to water and vapor permeation.
Butyl does, however, have a few drawbacks: it is rather costly due to its very high and specific level of protection against chemicals.
Structure: butyl, also known as butyl rubber, is a synthetic polymer used in many industrial products, including gloves, gaskets, hoses and coatings. It is known for its exceptional resistance to chemicals, making it a material commonly used in environments exposed to corrosive substances.
In organic chemistry, butyl is a four-carbon alkyl group with the formula -C4H9. The butyl group is generally linear. n-Butyl group: CH3-CH2-CH2-CH2- (systematic name: butyl).
Butyl rubber is the synthetic elastomer resulting from the copolymerization of isobuthylene and isoprene. It offers excellent resistance to extreme temperatures ( – 60°C to + 180°C ), weathering and aging.
Resistance
Structure : la structure moléculaire constituée de longues chaines carbonées reliées par des liaisons covalentes est compacte et stable.
Chemical inertness: butyl is chemically inert: it has no double or triple bonds and reacts very little with other chemical compounds. It resists oxidation and corrosion caused by aggressive substances such as strong acids, strong bases and other solvents.
Steric shielding: alkyl groups are very bulky in space, and therefore prevent access to any reactive molecules.
Hydrophobicité : le butyle est hydrophobe et rejette ainsi les solvants polaires comme l’eau souvent impliquée dans les réactions chimiques.
Imperméabilité : la grande imperméabilité du butyle empêche aussi le passage des différents produits à l’intérieur de la structure.
Butyl has good chemical resistance to: concentrated mineral acids (hydrochloric, sulfuric, hydrofluoric, nitric, phosphoric), ammonia and concentrated alkalis, halogenated or nitrated derivatives, organic acids (acetic, lactic), ketones, alcohols and esters.
For highly aggressive materials, such as acetone, ketone and esters, the only material that can withstand them is butyl. Using any other material would inevitably allow the product to penetrate the glove.
Exceptions: note that butyl is not resistant to all products, such as liquefied petroleum gas and fuel oil, petroleum (both aromatic and non-aromatic), hydrocarbons, aliphatic, aromatic or chlorinated solvents, oils and greases.
Butyl is also highly resistant to extreme temperatures.
Butyl rubber applications: Air chambers, gloves, roofing, shock absorbers
Butyl sectors: construction, tires, personal protective equipment…
The OG05 butyl glove [1]
A detailed study of this glove will give us a better understanding of how a butyl glove works and the different standards it must meet.
Description
The glove is manufactured in a single piece using an injection molding process. Its butyl thickness is very low: 0.5 mm, the lowest of any butyl glove on the market. This thickness ensures maximum dexterity. What’s more, the textured pattern at grip points such as the fingertips and palm of the hand ensures excellent grip, preventing objects from slipping.
Fingertips are not textured, enabling nursing staff to take pulses, insert infusions or use touch screens, for example.
Gussets at the knuckles prevent tension when bending the fingers, thus enhancing comfort. In addition, a stretch underglove enhances comfort.
Technical performance
Hardness
To measure the hardness of a material, a point (penetrator) is pushed against the material with a known force. Depending on the hardness, the tip will penetrate to a certain depth, which is measured. The Shore A scale is designed to test the hardness of rubber. It is expressed on a scale of 0 to 100. For example, 30 Shore A is much softer than 80 Shore A. For the OG05 glove, hardness is 53 Shore A.
Elongation at break
Elongation at break (A%) is a dimensionless characteristic of materials. It defines a material’s capacity to elongate before breaking when subjected to tensile stress. A% is determined by a tensile test. In the case of Og05, the glove can stretch by 526% before breaking.
Tear resistance
ASTM D624 is a test method for determining the tear resistance of vulcanized rubber and thermoplastic elastomers. Tear strength is defined as the maximum force divided by the thickness of the specimen. The value of 30.5 kN/m for the Og05 glove enables comparison with other products on the market.
Mechanical standard EN 388
This standard classifies the mechanical properties of rubber according to ;
Abrasion test: the number of cycles required for the abrasive paper to wear the sample down to the hole.
The cut-off test: an index obtained from the number of cycles required for the circular blade to cut the sample and a control specimen at constant speed and pressure.
Tear resistance: is the force required to tear the sample. It is measured in Newtons.
Puncture resistance: the force required to pierce the material with a standardized punch. It is also measured in Newtons.
The different levels correspond to the results: the higher the number, the better the performance, not forgetting that there is also a level 0! These values enable comparisons between different products.
La dextérité : EN 420
A test to determine dexterity level. It consists in recording the smallest diameter of a pin that can be grasped with the gloved hand 3 times in 30 seconds. The smaller the diameter, the higher the dexterity level (5 performance levels, level 5 being the best).
Flame behavior
The EN ISO 15025 test method analyzes the limited spread of flame on samples. The OG05 glove complies with this standard.
Contact heat
EN ISO 12127-1 measures the contact heat transfer produced by a heating cylinder. The sample is placed on a metal cylinder heated to 250°C. On the other side, a calorimeter measures the temperature rise. For the Og05 glove, it takes 17 seconds for the temperature to reach 100°C.
Chemical permeation resistance
Permeation is the process by which a hazardous liquid chemical passes through the fabric of a protective garment, at the molecular level. The outer surface of a test fabric is exposed to the chemical in liquid or gaseous form using a permeation test cell. The penetration of the chemical into the inner surface of the tissue is monitored by taking a sample from the collection side of the cell and determining by analysis, using mass spectrometry techniques, when the chemical has penetrated through the tissue. Classes are defined according to the time taken for the chemical to pass through to the other side of the sample. For the OG05 glove, the values are over 480 min for acetone, methanol and sulfuric acid, and 120 min for ethyl acetate. For chemical warfare agents, HD, VX and GD, the products do not pass through before 24 hours, making it compliant with NATO AEP 38.
Virus penetration
The small size of viruses enables them to pass easily through the micro-holes of ordinary protective gloves. Nevertheless, gloves complying with EN 374-5 VIRUS or ASTM F 1671 standards form an effective barrier against small viruses.
Protection against ionizing radiation and radioactive contamination
Compliant
Protection against ionizing radiation and radioactive contamination
Compliant
The logos corresponding to all these properties are shown below.
Conclusion
Butyl gloves are invaluable when it comes to protecting hands against chemicals, whether they be CBRN or industrial toxins. Very thin, they provide maximum dexterity, and can be used by medical staff to perform tasks such as taking pulses or inserting perfusions. However, before they can be marketed, they have to undergo a large number of tests to meet the numerous standards that guarantee their effectiveness.
Butyl CBRN gloves OG05