Everything about Superglue totally explained
Cyanoacrylate is the generic name for substances such as ethyl-2-cyanoacrylate, which is typically sold under trademarks like
Superglue and
Krazy Glue, and 2-octyl cyanoacrylate or n-butyl-cyanoacrylate, which are used in
medical glues such as
Dermabond and
Traumaseal. Cyanoacrylate adhesives are sometimes known as "instant adhesives". The acronym "CA" is quite commonly used for industrial grades.
History
Cyanoacrylate was discovered by
Harry Coover at
Eastman Kodak during
World War II when searching for a way to make plastic gun-sight lenses. It didn't solve this problem, since it stuck to all the apparatus used to handle it. It was first marketed to industry as well as consumers in February 1955 as a product called "Flash Glue" which is still available today and now owned by Gary Shipko, president of Super Glue International, a United States based firm. It was patented in 1956 and developed into
Eastman 910 adhesive in 1958. The new glue was demonstrated in 1959 on the television show
I've Got a Secret when the host
Garry Moore was lifted into the air by two steel plates held together with a drop of
Eastman 910. Cyanoacrylates are now a family of
adhesives based on similar chemistry.
Uses
General uses
Cyanoacrylate is a tenacious
adhesive, particularly when used to bond non-porous materials or those that contain minute traces of
water. It is also very good at bonding body tissue, and while this can be a bothersome (or even dangerous) side effect during everyday use, it has been exploited for the benefit of
suture-less
surgery.
Cyanoacrylate glue has a low shearing strength, which has also led to its use as a temporary adhesive in cases where the piece can easily be sheared off at a later time. Common examples include mounting a workpiece to a sacrificial glue block on a
lathe and also tightening pins and bolts.
Cyanoacrylates are often used to assemble prototype
electronics (see
wire wrap), flying
model aircraft, and as retention dressings for
nuts and
bolts. Their effectiveness in bonding metal and general versatility have also made them popular amongst
modeling and
miniatures hobbyists. They are used to re-harden the boxes and shanks of ballerinas'
pointe shoes as well.
Cyanoacrylate glues ability to resist water has made it popular with
marine aquarium hobbists for
fragging corals. The cut branches of
hard corals such as
Acropora can be glued to a piece of
live rock or
Milliput substrate to allow the new
frag to grow out.
When added to baking soda (
Sodium bicarbonate) Cyanoacrylate glue forms a hard, lightweight filler/adhesive (baking soda is first used to fill a gap then the adhesive is dripped into the baking soda). This works well with porous materials that the glue doesn't work well with alone. This method is sometimes used by aircraft modelers to assemble or repair polystyrene foam parts.
One non-adhesive use for cyanoacrylate is as a forensic tool. Fumes from warmed CA can develop latent fingerprints on smooth surfaces like glass, plastic, etc. The invisible fingerprint residues react with the CA fumes and atmospheric moisture to form a white polymer (polycyanoacrylate) on the fingerprint ridges and can then be recorded. The developed fingerprints are, on most surfaces (except on white plastic or similar), visible to the naked eye. Non-visible or poorly visible prints can be furthermore enhanced by applying a luminescent or non-luminescent stain. This technique was shown in the films
Beverly Hills Cop II and
National Treasure, and frequently features in the television series and its spin-offs.
Thin CA glue is also used as a wood finish, particularly among
woodturners. Its fast drying time and glossy finish make it ideal for small applications which generally look best when glossy (such as pens), although it's messy and somewhat expensive. A common mistake made by novice users is to use an accelerator, which can cloud and thus ruin the finish.
Some
climbers use glue to repair damage to the skin on their fingertips.
Medical uses
The use of cyanoacrylate glues in
medicine was considered fairly early on.
Eastman Kodak and
Ethicon began studying whether the glues could be used to hold human tissue together after surgery. In 1964, Eastman submitted an application to use cyanoacrylate glues to seal wounds to the
United States Food and Drug Administration (FDA). Soon afterward Dr. Harry Coover's glue did find use in
Vietnam—reportedly in 1966, cyanoacrylates were tested on-site by a specially trained surgical team, with impressive results. In an interview with Dr. Coover by the
Kingsport Times-News, Coover said that the compound demonstrated an excellent capacity to stop bleeding, and during the
Vietnam War, he developed disposable cyanoacrylate sprays for use in the battlefield.
The original Eastman formula wasn't FDA approved for medical use, however, because of a tendency to cause skin irritation and to generate heat. In 1998 the FDA approved 2-octyl cyanoacrylate for use in closing wounds and surgical incisions. Closure Medical has developed medical cyanoacrylates such as Dermabond, Soothe-N-Seal and
Band-Aid Liquid Adhesive Bandage.
Properties
In its liquid form, cyanoacrylate consists of
monomers of cyanoacrylate molecules. Methyl-2-cyanoacrylate (CH
2=C(CN)COOCH
3 or C
5H
5NO
2) has a molecular weight equal to 111.1, a
flashpoint of 79 °C, and 1.1 times the density of
water. Ethyl-2-cyanoacrylate (C
6H
7NO
2) has a molecular weight equal to 125 and a flashpoint of >75°C.
Generally, cyanoacrylate is an
acrylic resin which rapidly
polymerises in the presence of water (specifically
hydroxide ions), forming long, strong chains, joining the bonded surfaces together. Because the presence of moisture causes the glue to set, exposure to moisture in the air can cause a tube or bottle of glue to become unusable over time. To prevent an opened container of glue from setting before use, it must be stored in an airtight jar or bottle with a package of
silica gel.
Another important trait is that cyanoacrylate sets quickly, often in less than a minute. A normal bond reaches full strength in two hours and is waterproof. Accelerators such as
toluidine trigger setting in two or three seconds, with some loss of strength.
Acetone, which is sometimes found in nail polish remover, is a commonly available solvent capable of softening cured cyanoacrylate.
Nitromethane is also an excellent solvent.
Methylene chloride is the most effective but is toxic.
Gamma-butyrolactone is also effective at removing superglue, and has low toxicity.
Low temperatures cause cyanoacrylate to become brittle. Cyanoacrylate's bonds can be weakened (allowing disassembly) by placing a glued object in a household freezer for several hours.
Reaction to Cotton
Applying cyanoacrylate to materials made of cotton (such as cotton swabs, balls, or certain cotton yarns / fabrics) results in a powerful, rapid
exothermic reaction which is capable of setting the cotton product in question
on fire as well as releasing additional irritating vapor in the form of white smoke and causing minor burns if spilled on clothing.
Users should NOT wear cotton clothing, especially cotton gloves, when handling cyanoacrylate, nor should they apply cyanoacrylate to cotton items.
Toxicity
Cyanoacrylates bond skin and eyes in seconds. The National Toxicology Program and the United Kingdom Health and Safety Executive have concluded that the use of ethyl cyanoacrylate is safe and that additional study is unnecessary. 2-octyl cyanoacrylate degrades much more slowly due to its longer organic backbone which slows the degradation of the adhesive enough to remain below the threshold of tissue toxicity. Due to the toxicity issues of ethyl cyanoacrylate, 2-octyl-cyanoacrylate is used for sutures.
Cyanoacrylates give off vapor which is irritating to eyes,
mucous membranes and respiratory system.
ACGIH assign a
Threshold Limit Value exposure limit of 0.2
parts per million. On rare occasions inhalation may trigger
asthma. There are a wide variety of adhesives of which different cyanoacrylate formulations may be a component. It is wisest to obtain and consult a manufacturers
material safety data sheet for a product in order to consider the specific hazards associated with exposure.
According to the bottle label, Superglue may cause allergic skin reaction. If glue is stuck to eyes, flush with water for 15 minutes and call a doctor. If contact with skin, flush with water. If eaten/drunk, call a doctor and don't induce vomiting. Keep product away from children. Superglue is an eye and respiratory irritant.
Further Information
Get more info on 'Superglue'.
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